Details of a Researcher - Namerikawa, Toru

Papers - Namerikawa, Toru

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Safe cooperative control of CAVs at signal-free intersection under realistic scenarios

Y Nakai, T Namerikawa

SICE Journal of Control, Measurement, and System Integration (The Society of Instrument and Control Engineers ) 17 ( 1 ) 106 - 121 2024.04

Research paper (scientific journal), Joint Work, Last author, Accepted

This research deals with the cooperative control of CAVs (Connected and Automated Vehicles) at signal-free intersection. CAVs communicate with each other and adjust their speeds to safely pass through the intersection without having to stop. This is expected to improve intersection throughput and reduce fuel consumption. In order to execute cooperative control, a two-stage control structure is considered. In the first stage, the merging time, defined for each CAV as the time at which the CAV reaches the intersection, is obtained by solving mixed integer linear programming (MILP). In the second stage, each CAV solves an optimal control problem to determine the control input that allows it to reach the intersection at the merging time obtained in the first stage. In this research, a nonlinear model that considers air resistance, rolling resistance, and slope resistance is used to take into account the real environment. We propose a method using a control barrier function to guarantee the safety of CAVs even with nonlinear models, and an input correction method using a disturbance observer to suppress modelling errors caused by complex dynamics. We also propose a method that consists of establishing a speed regulation zone to avoid the possibility of passing through an intersection at an unsafe speed to improve throughput. Finally, a comparison with previous studies shows the superiority of the proposed method in reducing fuel consumption.

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Passivity-Short-Based Conditions of System-Wide Stability and L2 gain Performance for Heterogeneous Nonlinear Power System

H Kang, T Namerikawa

2024 SICE International Symposium on Control Systems (SICE ISCS), 94-98 2024.03

Research paper (international conference proceedings), Last author, Accepted

Optimal Resilient Sensor Placement Problem for Secure State Estimation

Shinohara Takumi, Namerikawa Toru

Proceedings of the Japan Joint Automatic Control Conference (The Japan Joint Automatic Control Conference) 160 ( 0 ) 140 - 142 2024.02

Research paper (scientific journal), Joint Work, Last author, Accepted, ISSN 00051098

In this paper, we consider a sensor placement problem for secure state estimation in an adversarial environment. Specifically, this paper deals with a system consisting of n agents where up to l sensor measurements are potentially compromised by malicious adversaries and tackles the problem of sensor placement such that the system state can be reconstructed even if the measurements are compromised. However, since it is costly to deploy sensors for all agents, we also aim to place sensors at the lowest possible cost. We call this problem the optimal resilient sensor placement problem (ORSPP) and show that this problem is coNP-hard. Therefore, it is, in general, impossible to compute the ORSPP in polynomial time unless P=coNP. On the positive side, however, we also provide that this problem can be solved in polynomial time if the network structure of the agents satisfies certain conditions. The concrete algorithm for the ORSPP is provided, and further, in the process of providing the coNP-hardness, we also derive a new form of a necessary and sufficient condition for secure state estimation. Finally, we show the results of numerical simulations using a random graph and a diffusion process.

Consistent event-triggered consensus on complete graphs

DJ Antunes, D Meister, T Namerikawa, F Allgöwer, W Heemels

2023 62nd IEEE Conference on Decision and Control (CDC), 3911-3916 (Proceedings of the IEEE Conference on Decision and Control) 3911 - 3916 2023.12

Research paper (international conference proceedings), Joint Work, Accepted, ISSN 07431546

This paper starts by considering an optimal control formulation of the consensus problem on complete graphs with a cost capturing disagreement and agents modeled by integrators. An optimal control policy for this problem is shown to be the well-known consensus algorithm by which each agent resets its state to the average of its and other agents' state values received at every time step. The framework is extended to the case where agents can only exchange information periodically, with a period larger than one. Then an event-triggered control strategy is proposed that results in a better cost than that of the optimal periodic one with the same average transmission rate, that is, it is consistent. According to this strategy, each agent distributedly transmits its state if the error between its current state and a common consensus estimate based on previously transmitted agents' data exceeds a threshold. Simulation results are presented to illustrate the proposed strategy.

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Decentralized Optimal Parking Lot Allocation via Dynamic Parking Fee

Y Fujimaki, T Namerikawa

2023 28th Asia Pacific Conference on Communications (APCC), 261-266 (Proceedings - 2023 28th Asia Pacific Conference on Communications, APCC 2023) 261 - 266 2023.11

Research paper (international conference proceedings), Joint Work, Accepted

This paper proposes a novel decentralized optimal parking lot allocation algorithm by using dynamic parking fee. Information about drivers and parking lots used to be collected by a system manager in smart parking systems, and the allocation is determined centrally. However, the computational load increases exponentially as the target area expands. Therefore, a decentralized system is needed that can flexibly respond to the expansion of the area size, in which the allocation is determined by communicating the results of the calculations performed by each participant. In building a decentralized system, it is desirable for the system to be fair and efficient. Therefore, we propose a decentralized parking system that satisfies this property by using matching theory, a field that studies how people and things should be matched in a market. We propose a unique matching method that takes into account the difference between drivers as consumers and parking service providers. We also propose a reallocation method based on dynamic parking fee to reduce the number of unallocated drivers.

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Battery Management of Microgrids Based on Scenario Optimization

S Wakabayashi, T Namerikawa

2023 62nd Annual Conference of the Society of Instrument and Control … (2023 62nd Annual Conference of the Society of Instrument and Control Engineers, SICE 2023) 1248 - 1253 2023.09

Research paper (international conference proceedings), Last author, Accepted

This paper proposes an optimal battery management methodology in microgrids. Every microgrid gives other microgrids a fair deal of electric power based on Generalized Nash Bargaining Solution, which is a kind of optimal solutions of a fair trade in game theory. In this paper, we use a method of scenario optimization in order to take optimal and safe estimates for generations from renewable energy sources. First, many scenarios of the amount of generation are prepared. Then, we calculate the total cost of microgrids for each scenario and find the highest cost. We determine the strategy which corresponds to the highest-cost-scenario as each microgrid's final strategy. Through this method, the number of violations of the limitations of the batteries and the extra cost caused by those violations has been reduced. Power flow in networks which connect each microgrid and an electric power company is also considered.

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Robust Energy Management Using Tube-Based Model Predictive Control for a Building with Solar Power and Batteries

K Takano, T Namerikawa

2023 62nd Annual Conference of the Society of Instrument and Control … (2023 62nd Annual Conference of the Society of Instrument and Control Engineers, SICE 2023) 1344 - 1349 2023.09

Research paper (international conference proceedings), Accepted

The power generation from renewable energy sources, which is being promoted for mass adoption due to environmental issues, is affected by weather conditions, and therefore, it is necessary to predict the amount of power generation. In this study, we propose an algorithm for BEMS that takes into account the uncertainty of solar power generation using Tube-Based MPC, which is a type of robust MPC. We confirm through simulations that the algorithm is more robust against forecast errors by comparing it with a conventional method [3].

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Passivity-Short-based Stability Analysis of Load Frequency Control System with Demand Response

Y Shibata, T Namerikawa

2023 62nd Annual Conference of the Society of Instrument and Control … (2023 62nd Annual Conference of the Society of Instrument and Control Engineers, SICE 2023) 1232 - 1237 2023.09

Research paper (international conference proceedings), Accepted

This paper deal with a stability analysis for a load frequency control (LFC) system including Demand Response (DR). To analyze system stability, LFC system is formulated to facilitate the application of passivity theory, and the passivity and passivity-short of the system are analyzed. At first, we express LFC system decomposing into a network system and area systems. Specifically, area systems include DR that occurs time-varying communication delay. Then, passivity analysis is applied to each system. As a result, we can clarify the area systems are output strictly passive if certain inequalities are satisfied, and the network system is passive. Simulation results show that the frequency deviation converges to a constant value under the derived inequality condition.

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Cooperative Control of CAVs Using Control Barrier Function at Signal-free Intersection Considering Real Environment

Y Nakai, T Namerikawa

2023 62nd Annual Conference of the Society of Instrument and Control … (2023 62nd Annual Conference of the Society of Instrument and Control Engineers, SICE 2023) 1001 - 1006 2023.09

Research paper (international conference proceedings), Last author, Accepted

This study addresses the cooperative control of CAVs(Connected and Automated Vehicles) at Signal-free Intersection. The purpose is to reduce fuel consumption by crossing intersection without stopping as much as possible while ensuring safety. For this problem, We consider a two-stage control structure.The first stage is to calculate the merging time of each CAV by solving mixed integer linear programming (MILP). In the second stage, each CAV solves the optimal control problem and determines the input in time for the merging time. In this study, We propose an optimal control method using control barrier function considering more realistic scenario, and a speed regulation zone to cross the intersection at a pre-determined terminal speed. By using input corrections and trajectory tracking of speed and position, simulation results show that fuel consumption can be reduced while ensuring safety. Finally, compared to conventional research, the system achieves low fuel consumption, and demonstrating its superiority.

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Robust Model Predictive Control of Large-Scale Power Network with Moving Horizon Estimation

T Namerikawa

2023 IEEE Conference on Control Technology and Applications (CCTA), 823-828 (2023 IEEE Conference on Control Technology and Applications, CCTA 2023) 823 - 828 2023.08

Research paper (international conference proceedings), Single Work, Accepted

In this paper, we discuss the load frequency control problem for large-scale power network systems. The control is conducted to preserve the demand-supply power balance by controlling the output of generators in a power network. However, it becomes difficult to retain the balance because of the injection of a large amount of renewable energy whose output is uncertain. This paper proposes a new control application framework, especially focused on a large-scale connected power network system that contains a large-volume wind turbine generator, thermal turbine generator, and battery. More concretely, to satisfy the constraints of state and input control, we propose a method of load frequency control using moving horizon estimation and robust model predictive control.

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Command Value Determination Considering Generation Cost and Control Performance Using Model Predictive Control in Load Frequency Control

D Sano, T Namerikawa

IFAC-PapersOnLine 56 (2), 1534-1539 (IFAC-PapersOnLine) 56 ( 2 ) 1534 - 1539 2023.07

Research paper (international conference proceedings), Joint Work, Accepted, ISSN 2405-8963

This paper deals with load frequency control (LFC) problem for power system. The control is conducted to retain power demand supply balance by controlling output of generators in power network. In order to realize LFC with low power generation cost while maintaining control performance, this paper proposes frequency control method using Moving Horizon Estimation (MHE) and Model Predictive Control (MPC). First, MHE is used to estimate the state of the system. Next, optimization calculation is performed using MPC to determine the command values for each generator. Finally, simulation of load frequency control is carried out to verify the effectiveness of the proposed method.

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Reducing Air Pollutant Emissions and Optimizing Fuel Economy by Controlling Torque and Catalyst warm-up in mild HEV via Cascaded MPC

Y Umezawa, H Seto, T Imamura, T Namerikawa

IFAC-PapersOnLine 56 (2), 670-675 (IFAC-PapersOnLine) 56 ( 2 ) 670 - 675 2023.07

Research paper (international conference proceedings), Accepted, ISSN 2405-8963

In this paper, Cascaded MPC (Model Predictive Control) including Supervisory MPC, Heating MPC and Torque MPC is applied to mild HEVs (Hybrid Electric Vehicles) in order to improve fuel economy and reduce NOx emissions. There is a difference in the timescale between Heaitng MPC and Torque MPC, which are connected via the battery. Supervisory MPC treats the power and temperature systems comprehensively and calculates reference values for NOx emissions to be tracked in Heating MPC. In Heating MPC, the optimal amount of heating from the battery to the catalyst in the exhaust gas after-treatment system is determined. The amount of heating must be determined in a way that the catalyst can optimally purify NOx emitted from the engine. At Torque MPC, the optimal torque distribution for the engine and motor is determined. Finally, the effectiveness of our proposed method is demonstrated by simulations.

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Distributed Route Optimization for Mixed Package-Passenger System Incorporating Ridesharing Passenger Matching

Yamamoto Eri, Itoh Yutaro, Ikemoto Noriaki, Namerikawa Toru

Proceedings of the Japan Joint Automatic Control Conference (The Japan Joint Automatic Control Conference) 56 ( 2 ) 2365 - 2370 2023.07

Research paper (international conference proceedings), Accepted, ISSN 2405-8963

This paper proposes an algorithm for optimizing the route in a mixed package-passenger system where taxicab drivers, who transport passengers, are assigned the task of delivering packages. The main aim is to address the shortage of package delivery drivers and to reduce the amount of CO2 emitted by delivery vehicles. The paper also proposes a stable ridesharing matching scheme, which reduces fares for taxicab passengers. Furthermore, the problem is formulated as a mixed integer linear programming problem to identify the optimal route and driver task assignments. A distributed method based on Lagrangian relaxation is proposed to reduce the computational effort. The paper concludes by demonstrating the effectiveness of the proposed algorithm through numerical simulations.

Decentralized optimal parking lot allocation by static and dynamic two-stage matching

Y Fujimaki, Y Shibata, R Namerikawa, T Namerikawa

IFAC-PapersOnLine 56 (2), 689-694 (IFAC-PapersOnLine) 56 ( 2 ) 689 - 694 2023.07

Research paper (international conference proceedings), Accepted, ISSN 2405-8963

In this paper, we propose an optimal parking lot allocation method based on matching theory that takes into account the desires of both drivers searching for parking lots and parking lot managers. In the conventional method, the allocation calculation is performed centrally, making it difficult to expand the area. We propose a decentralized allocation method that combines static and dynamic matching. In this method, individual drivers and parking lots perform calculations, and the allocation is determined in a decentralized manner through information communication, making it possible to expand the area. Finally, we confirm the effectiveness of the proposed method through numerical simulations.

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Secure State Estimation for Multi-Agent Systems: On the Relationship between the Number of Agents and System Resilience

T Shinohara, T Namerikawa

2023 American Control Conference (ACC), 1006-1011 (Proceedings of the American Control Conference) 2023-May 1006 - 1011 2023.06

Research paper (international conference proceedings), Joint Work, Accepted, ISSN 07431619

This paper addresses the problem of secure state estimation in multi-agent systems consisting of n agents. For the problem, the sparse observability index is a well-known measure of the system resilience. This index is defined as the largest integer δ for which the system observability is preserved even if any δ sensors are eliminated. The larger δ is, the more the system state can be reconstructed even if the system is subjected to more sensor attacks. In this paper, we analyze the relationship between the number of agents n and the sparse observability index δ especially when the network structure is path and cycle graphs. Intuitively, it is assumed that, as the number of agents n increases, the system resilience, i.e., δ, increases accordingly. However, as this study provides, δ does not monotonically increase with an increase in n. In path graphs, δ depends on whether n+1 is prime or composite, and the system resilience is enhanced when n+1 is prime. In cycle graphs, δ obeys whether n is prime or composite, and the system is more resilient when n is prime.

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Safe exploration method for reinforcement learning under existence of disturbance

Yoshihiro Okawa, Tomotake Sasaki, Hitoshi Yanami, Toru Namerikawa

Joint European Conference on Machine Learning and Knowledge Discovery in … (Springer Nature) 13716 LNAI 132 - 147 2023.03

Research paper (international conference proceedings), Joint Work, Accepted, ISSN 03029743

Recent rapid developments in reinforcement learning algorithms have been giving us novel possibilities in many fields. However, due to their exploring property, we have to take the risk into consideration when we apply those algorithms to safety-critical problems especially in real environments. In this study, we deal with a safe exploration problem in reinforcement learning under the existence of disturbance. We define the safety during learning as satisfaction of the constraint conditions explicitly defined in terms of the state and propose a safe exploration method that uses partial prior knowledge of a controlled object and disturbance. The proposed method assures the satisfaction of the explicit state constraints with a pre-specified probability even if the controlled object is exposed to a stochastic disturbance following a normal distribution. As theoretical results, we introduce sufficient conditions to construct conservative inputs not containing an exploring aspect used in the proposed method and prove that the safety in the above explained sense is guaranteed with the proposed method. Furthermore, we illustrate the validity and effectiveness of the proposed method through numerical simulations of an inverted pendulum and a four-bar parallel link robot manipulator.

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Optimal Parking Lot Allocation Considering Demand Situation

FUJIMAKI Yuto, NAMERIKAWA Toru

Transactions of the Society of Instrument and Control Engineers (The Society of Instrument and Control Engineers) 59 ( 3 ) 176 - 182 2023.03

Research paper (scientific journal), Joint Work, Corresponding author, Accepted, ISSN 04534654

In this paper, we propose a new smart parking system that determines the optimal parking allocation in the long run. In this system, the demand situation is acquired earlier than the respective parking start time by motivating drivers to apply for early parking, and the system performs long-term optimization instead of optimization only for the current time. We propose three optimization methods focusing on the time axis. The first one ignores the time axis constraint, the second one has the time axis constraint but lacks driver motivation, and the third one is the proposed method that solves those problems. Finally, numerical simulations will be used to confirm the effectiveness of the proposed method.

Mild HEVにおけるトルクおよび触媒暖機制御によるNOxの排出低減と燃費最適化

UMEZAWA Yuka, SETO Hiroki, IMAMURA Toshiro, NAMERIKAWA Toru

Transactions of the Society of Instrument and Control Engineers (The Society of Instrument and Control Engineers) 59 ( 3 ) 110 - 120 2023.03

Research paper (scientific journal), Joint Work, Corresponding author, Accepted, ISSN 04534654

In this paper, we consider fuel economy optimization problem for mild HEV (Hybrid Electric Vehicle) via hierarchical model predictive control. In our algorithm, we deal with two problems; one is eco-driving, and the other is torque distribution. In the eco-driving problem, we control vehicle speed. Considering the reduction of fuel consumption and NOx emission, we calculate the required torque to follow target speed. Next, in the torque distribution problem, we calculate the distribution between the engine and motor torque. In that phase, engine characteristics are considered. These problems differ in terms of time scales, hence we propose hierarchical model predictive control. Finally, numerical simulation results show the effectiveness of this research.

Construction of One-Way Car Sharing System Considering Coalition Rationality based on Mechanism Design

Shun Sasaki, Eri Yamamoto, and Toru Namerikawa

IEEE Transactions on Control of Network Systems (IEEE Transactions on Control of Network Systems) 9 ( 4 ) 1655 - 1665 2022.12

Research paper (scientific journal), Joint Work, Corresponding author, Accepted, ISSN 2325-5870

This paper proposes a control algorithm for one-way car sharing. The problem with one-way car sharing is that the origin and the destination parking lots, tend to be biased because user traffic demands, and the cost of relocating the vehicle to increase the operating rate is high. To solve this problem, we propose providing incentives to users in the form of discounts and also changing the parking lots and departure times to prevent bias in the number of vehicles in the parking lots. In this study, based on the Vickrey-Clarke-Groves (VCG) mechanism design, an incentive design was created to satisfy desirable properties, such as strategy-proofness, individual rationality, and coalition rationality. In the proposed one-way car sharing system, the system manager decides the proposal based on the information reported by the users. Therefore, satisfying these properties not only guarantees not only that the users will benefit from agreeing to the proposal, but also that even in case of a false declaration or shill bidding, the discount will not be unreasonably profitable. Finally, the increase in demand acceptance by applying the proposed method was confirmed by numerical simulation.

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Parking Lot Allocation Using Rematching and Dynamic Parking Fee Design

Takuya Nakazato, Yuto Fujimaki and Toru Namerikawa

IEEE Transactions on Control of Network Systems (IEEE Transactions on Control of Network Systems) 9 ( 4 ) 1692 - 1703 2022.12

Research paper (scientific journal), Joint Work, Corresponding author, Accepted, ISSN 2325-5870

In this study, we propose a novel smart-parking system that allocates parking lots based on the matching theory, considering both the drivers and parking managers preferences. Some drivers may be unable to be allocated to parking lots because of the high traffic volume in urban areas that makes many parking lots full. Therefore, we propose a prior reservation system that can reallocate parking lots considering the waiting time until vacant parking spaces appear. The drivers preference is redetermined considering the waiting time obtained by both the parked drivers and reallocated drivers information. We also present a parking lot allocation algorithm, including rematching, and discuss stability and strategy-proofness, which are important properties of matching. Furthermore, we propose a dynamic parking fee design, considering different parking statuses. By combining the price increase with the price decrease based on parking status, the proposed dynamic parking fee aims not only to level out parking utilization, but also to secure the parking managers profit. Finally, numerical simulations confirm the effectiveness of the proposed method.

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Power Demand-Supply Adjustment via Negawatt Trading Based on Regret Matching

Toru Namerikawa

2022 IEEE 61st Conference on Decision and Control (CDC) (IEEE) 2022-December 4394 - 4399 2022.12

Research paper (international conference proceedings), Single Work, Accepted, ISSN 07431546

This study deals with power demand-supply management based on negawatt trading. The aim of this study is to minimize the social cost of negawatt trading and maintain a demand-supply balance. Power consumers and independent system operators participate in the electricity market and each consumer acts based on regret matching, which is one of the learning algorithms. Furthermore, we consider strategy-proofness and individual rationality using VCG mechanism design. In this study, we propose a novel negawatt trading procedure based on regret matching and VCG mechanism design. Finally, the simulation results confirm the effectiveness of the proposed algorithm.

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Cooperative Control of Connected and Automated Vehicles at Signal-free Intersections Considering Passenger Comfort

Akira Kuchiki, Toru Namerikawa

2022 61st Annual Conference of the Society of Instrument and Control Engineers of Japan, SICE 2022 (IEEE) 909 - 914 2022.09

Research paper (international conference proceedings), Joint Work, Corresponding author, Accepted

In this research, we deal with the coordination problem of Connected and Automated Vehicles (CAVs) at signal-free intersections. First, the problem is formulated to find the appropriate merge time for each CAV. Next, an optimal motion planning problem is formulated to find the control input (jerk) necessary to accurately achieve the given optimal merging time while minimizing the jerk and acceleration. We also present an analytical solution for this motion planning problem with inequality constraints on jerk and acceleration, which achieves both passenger comfort and reduced fuel consumption. Finally, the simulation results show the effectiveness of the proposed method.

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Optimal Incentive Design for One-Way EV Car Sharing System

Shun Sasaki, Toru Namerikawa

2022 IEEE Conference on Control Technology and Applications, CCTA 2022 (IEEE) 851 - 856 2022.08

Research paper (international conference proceedings), Joint Work, Corresponding author, Accepted

This paper deals with an optimal control and scheduling algorithm for one-way car sharing systems. One of the most critical problems of one-way car sharing system is that the parking lots, which tends to be the origins and the destinations, are biased due to the traffic demand of the users, and the cost of relocating the vehicles is becoming high. In order to solve this cost problem, we propose a novel mechanism to give incentives to users in the form of discounts and propose changes to parking lots and departure times to prevent bias in the number of vehicles in parking lots. The optimal parking lot is determined by using a queue information in order to consider the traffic demand distribution of users. Furthermore, an incentive is designed so as to satisfy desirable properties based on VCG mechanism. Finally, the effectiveness of the proposed method is confirmed via several numerical simulations.

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Optimization of fuel consumption and NOx emission for mild HEV via hierarchical model predictive control

Yuka Umezawa, Ken Yamauchi, Hiroki Seto, Toshiro Imamura, Toru Namerikawa

Control Theory and Technology (Springer) 20 ( 2 ) 221 - 234 2022.06

Research paper (scientific journal), Corresponding author, Accepted, ISSN 20956983

In this paper, we consider the fuel economy optimization problem for a mild hybrid electric vehicle (HEV) using hierarchical model predictive control. In the proposed algorithm, two problems are addressed: eco-driving and torque distribution. In the eco-driving problem, vehicle speed was controlled. Considering the reduction in fuel consumption and NOx emissions, the torque required to follow the target speed was calculated. Subsequently, in the torque distribution problem, the distribution between the engine and motor torques were calculated. In this phase, engine characteristics were considered. These problems differ in terms of time scales; therefore, a hierarchical model predictive control is proposed. Lastly, the numerical simulation results demonstrated the efficacy of this research.

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Reducing NOx Emissions and Optimizing Fuel Economy by Controlling Torque and Catalyst Warm-up in Mild HEVs

UMEZAWA Yuka, SETO Hiroki, IMAMURA Toshiro, NAMERIKAWA Toru

ASCC 2022 - 2022 13th Asian Control Conference, Proceedings (IEEE) 59 ( 3 ) 1914 - 1919 2022.05

Research paper (international conference proceedings), Joint Work, Corresponding author, Accepted, ISSN 04534654

In this paper, hierarchical model predictive control is applied to mild HEVs (Hybrid Electric Vehicles) in order to improve fuel economy and reduce NOx emissions. There is a difference in the timescale between the temperature control (high-level) and the torque control (low-level), which are connected via the battery. In high-level of the hierarchical control, the optimal amount of heating from the battery to the catalyst in the exhaust gas after-treatment system is determined. The amount of heating must be determined in a way that the catalyst can optimally purify NOx emitted from the engine. At the low-level of the hierarchical control, the optimal torque distribution for the engine and motor is determined. The controller at both levels then applies model predictive control to consider the future behavior of the HEV's components. Fuel consumption, battery SoC and NOx emissions from the engine are taken into account. Finally, the effectiveness of our proposed method is demonstrated by simulations.

Route Optimization of Mixed Package-Passenger System with Matching Based on Cost Sharing among Passengers

Eri Yamamoto, Toru Namerikawa

ASCC 2022 - 2022 13th Asian Control Conference, Proceedings (IEEE) 2292 - 2297 2022.05

Research paper (international conference proceedings), Joint Work, Corresponding author, Accepted

This paper proposes a route optimization algorithm for a mixed package-passenger system that assigns the task of package delivery to taxicab drivers carrying passengers. The goal is to compensate for the shortage of manpower among package delivery drivers and to reduce CO 2 emissions from delivery vehicles. In this paper, we propose a system that achieves fare reduction for passengers using taxicabs by incorporating stable passenger matching considering the cost sharing among passengers. In addition, we formulate it as a mixed integer linear programming problem to determine the allocation of delivery tasks to taxicab drivers and optimal route. Finally, the effectiveness of the proposed algorithm is shown through numerical simulations.

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Distributed secure state estimation with a priori sparsity information

Takumi Shinohara, and Toru Namerikawa

IET Control Theory & Applications (IET Control Theory and Applications) 16 ( 11 ) 1086 - 1097 2022.04

Research paper (scientific journal), Joint Work, Corresponding author, Accepted, ISSN 17518644

This paper addresses the problem of distributed secure state estimation of a discrete-time linear dynamical system in an adversarial environment. Much of the recent work on this problem has imposed redundancy requirements on measurement and communication networks for state estimation in the presence of attacks. In this paper, the authors aim to relax this redundancy requirement by using prior information about the state to be estimated. A scenario where sparsity information of the state is given is especially considered, and it is shown that the a priori sparsity information alleviates the redundancy requirement. An algorithm for distributed secure state estimation is then derived and a sufficient condition on the convergence of the algorithm is given. Numerical simulations finally illustrate the effectiveness of the algorithm.

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Decentralized Energy Trading Systems for Multiple BEMS Based on Solar Power Generation Forecasting

UMEZAWA Yuka, OKAWA Yoshihiro, NAMERIKAWA Toru

Transactions of the Society of Instrument and Control Engineers (The Society of Instrument and Control Engineers) 58 ( 4 ) 236 - 244 2022.04

Research paper (scientific journal), Joint Work, Corresponding author, Accepted, ISSN 04534654

This paper proposes an optimal trading algorithm for a decentralized energy trading system among multiple building energy management systems (BEMS). Each building generates solar power and has a battery. As a decentralized energy trading algorithm, we first solve the proposed optimization problem to determine the optimal trading volume that minimizes the total purchase price of electricity while satisfying the battery capacity constraint under the consideration of the solar power generation error and the time-varying electricity price. To take into account the foregoing, model predictive control and a scenario-based robust optimization are applied. After the information on the desired amount of electricity transactions is communicated between buildings, the electricity sales price is updated. These steps are iterated until the termination condition is satisfied, and the final trading volume is determined. The convergence of the proposed algorithm is analyzed and the sufficient conditions for the convergence of the price update parameters are shown. Finally, the total price cost and computational cost are compared with the centralized one, and the effectiveness and the superiority of the decentralized control system are shown by several numerical simulations.

Fuel Economy Optimization for mild HEV via Hierarchical Model Predictive Control

YAMAUCHI Ken, UMEZAWA Yuka, SETO Hiroki, IMAMURA Toshiro, NAMERIKAWA Toru

Transactions of the Society of Instrument and Control Engineers (The Society of Instrument and Control Engineers) 58 ( 4 ) 203 - 212 2022.04

Research paper (scientific journal), Joint Work, Corresponding author, Accepted, ISSN 04534654

Carriers Collaboration Routing Optimization of Mixed Cargo and Passenger Vehicles

Eri Yamamoto, Toru Namerikawa

Transactions of the Society of Instrument and Control Engineers (The Society of Instrument and Control Engineers) 58 ( 2 ) 81 - 91 2022.02

Research paper (scientific journal), Joint Work, Corresponding author, Accepted, ISSN 0453-4654

In this paper, we propose a route optimization algorithm for mixed cargo and passenger vehicles by incorporating ridesharing based on matching theory to the delivery planning problem for cargo transportation in order to reduce the total route cost in transportation. First, we consider the cargo-specific delivery route problem, which is formulated as two alternative mixed integer linear programming problems aimed at minimizing the transportation route cost by sharing the delivery tasks among multiple carriers. We then present an algorithm for determining passengers for ridesharing based on stable matching that considers the detour distance of each passenger, describe the passenger travel route search problem based on the cargo transportation route, and propose a series of algorithms for determining the optimal route of mixed cargo and passenger vehicles. Finally, the effectiveness of the proposed algorithm is evaluated through numerical simulations.

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Distributed Partial State Estimation via Virtual Distributed Observers

NAMERIKAWA Ryo, NAMERIKAWA Toru

Transactions of the Society of Instrument and Control Engineers (The Society of Instrument and Control Engineers) 57 ( 11 ) 488 - 498 2021.11

Research paper (scientific journal), Accepted, ISSN 0453-4654

In this paper, we propose virtual distributed observers which are built by virtually excluding some redundant sensors from conventional distributed observers. By using these observers, we can construct not only robust estimators against sensor attacks but detectors of attacks by malicious agents. We also consider the new framework of estimation problem which is more useful to adapt under distributed conditions. This relaxed problem makes it possible to estimate partial state under sensor attacks even if the whole observer system is not detectable. Finally, we confirm the effectiveness of our proposed method through numerical simulations.

Resilient Control of Cyber-Physical System Using Nonlinear Encoding Signal Against System Integrity Attacks

Y Joo, Z Qu, T Namerikawa

IEEE Transactions on Automatic Control 66 ( 9 ) 4334 - 4341 2021.09

Research paper (scientific journal), Joint Work, ISSN 0018-9286

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Robust Voltage Control of a Single-Phase Grid-connected Inverter by H∞ Controller Considering the Load Fluctuation

Yuya Fujie, Kazuhiro Nagira, and Toru Namerikawa

2021 60th Annual Conference of the Society of Instrument and Control Engineers of Japan, SICE 2021 (IEEE) 1215 - 1220 2021.09

Research paper (international conference proceedings), Corresponding author, Accepted

In this paper, we address the new voltage control system of a single-phase grid-connected inverter. In this paper, we apply the standard H∞ control theory and specifically we formulate the voltage control problem as mixed sensitivity problem. By using this method, we can realize both the fastness and robustness of the voltage control under the condition that the uncertainty exists such as fluctuation of the load and the distribution lines. Finally, we confirm the effectiveness of the proposed method through numerical simulation.

Construction of distributed cooperative EMS in multiple homes based on EV state prediction and MPC

小方裕貴，山内賢，滑川徹

電気学会論文誌 C (電子・情報・システム部門誌) (The Institute of Electrical Engineers of Japan) 141 ( 5 ) 685 - 693 2021.05

Research paper (scientific journal), Joint Work, Corresponding author, Accepted, ISSN 0385-4221

In this paper, we propose a novel energy management system (EMS) in which multiple homes cooperate. A buffer with a storage battery is needed to realize efficient power control in response to fluctuations in power demand and supply. Since there are problems such as economic cost and securing of installation place to apply the storage battery, it is conceivable to use electric vehicles (EV) instead. However, EVs need to be charged or discharged at home in preparation for traveling. The purpose of this paper is to propose a distributed cooperative energy management method for multiple homes based on EV state prediction and model predictive control (MPC). Finally, numerical simulation results show the effectiveness of the proposed algorithm.

Cooperative transport control by a multicopter system

Kento Kotani, Zhiqin Guo, Toru Namerikawa, Zhihua Qu

IET Control Theory & Applications (The Institution of Engineering and Technology) 15 ( 6 ) 861 - 876 2021.04

Research paper (scientific journal), Joint Work, Accepted, ISSN 17518644

To date, multicopters have mainly been used in the entertainment and information-gathering fields, but can potentially be used to transport payloads. Specifically, multicopters are more suited for manoeuvring tough terrains and delivering payloads to areas unaccessible by other means. The authors propose a control method to achieve cooperative transport with a plural multicopter system and address the problem of delivering a payload being suspended via cables from multicopters. In cooperative transport using a multicopter system, disturbance (weight, wind, and inertia force) may cause destabilization. A consensus algorithm is used to coordinate flight of helicopters in a formation and to ensure that the payload follows a virtual leader. Disturbances (such as wind and cable tension) are primary causes of destabilization and, in the multicopter setting, they are suppressed by an adaptive robust control, Robust Integral of Sign of the Error control. It is shown that the proposed control design can achieve not only convergence under the ideal setting but also robust operation under significant disturbances. In addition, additional control objectives such as cable tension, payload attitude, and collision avoidance can be integrated and achieved. As an auxiliary method, cable tension control, maintaining a horizontal payload attitude, and collision avoidance are considered. The usefulness of the proposed method was verified by simulations and laboratory flight testing demonstrations.

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Data-Driven Wide-Area Control Design of Power System Using the Passivity Shortage Framework

Y Xu, Z Qu, R Harvey, T Namerikawa

IEEE Transactions on Power Systems (IEEE Transactions on Power Systems) 36 ( 2 ) 830 - 841 2021.03

Research paper (scientific journal), Joint Work, Accepted, ISSN 08858950

A novel wide-area control design is presented to mitigate inter-area power frequency oscillations. A large-scale power system is decomposed into a network of passivity-short subsystems whose nonlinear interconnections have a state-dependent affine form, and by utilizing the passivity shortage framework, a two-level design procedure is developed. At the lower level, any generator control can be viewed as one that makes the generator passivity-short and L-2 stable, and the stability impact of the lower-level control on the overall system can be characterized in terms of two parameters. While the system is nonlinear, the impact parameters can be optimized by solving a data-driven matrix inequality (DMI), and the high-level wide-area control is then designed by solving another Lyapunov matrix inequality in terms of the design parameters. The proposed methodology makes the design modular, and the resulting control is adaptive to operating conditions of the power system. Standard test systems are used to illustrate the proposed design, including DMI and the wide-area control, and simulation results demonstrate its effectiveness in damping out inter-area oscillations.

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Optimal Parking Lot Allocation Using Rematching in Prior Reservation System

NAKAZATO Takuya, NAMERIKAWA Toru

Transactions of the Society of Instrument and Control Engineers (The Society of Instrument and Control Engineers) 57 ( 3 ) 185 - 194 2021.03

Research paper (scientific journal), Joint Work, Corresponding author, Accepted, ISSN 0453-4654

In this paper, we propose a novel Smart Parking System which determines optimal parking lot allocation based on matching theory. In this Smart Parking System, parking lot allocation is determined considering both driver's preference and parking lot manager's preference. Then, there is a possibility that a parking lot allocation is not possible due to no vacant parking space at current time and so on. For the driver who cannot be allocated a parking lot, Prior Reservation System (PRS) conducts the optimal parking lot reallocation considering waiting time of each parking lot until a vacant parking space is available. Also, the driver in PRS is satisfied with individual rationality. So, optimal parking lot allocation including rematching in PRS is determined based on matching theory. Finally, numerical simulation results show the effectiveness of proposed method.

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Incentive Design for One-way Car-sharing Based on Mechanism Design

SASAKI Shun, NAMERIKAWA Toru

Transactions of the Society of Instrument and Control Engineers (The Society of Instrument and Control Engineers) 57 ( 3 ) 168 - 176 2021.03

Research paper (scientific journal), Joint Work, Corresponding author, Accepted, ISSN 0453-4654

This paper proposes a novel car sharing algorithm which changes OD (Origin-Destination) and departure time to the user in exchange for the charge discount, and aims to prevent the bias of the number of vehicles in one-way car-sharing stations. First, a one-way car sharing model based on discrete event systems is described. Next, we will explain how to calculate the optimal combination of the origin, destination, and the departure time in real time, and the method of deciding on incentives that meet strategy-proofness and individual rationality based on mechanism design. Finally, the increase in demand acceptance by the proposed method is confirmed by numerical simulation.

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Self Attack Detection and State Estimation Algorithm in Distributed Observer System under Combination Attack

S Sato, T Namerikawa, Z Qu

2020 59th IEEE Conference on Decision and Control (CDC), 5011-5016 (Proceedings of the IEEE Conference on Decision and Control) 2020-December 5011 - 5016 2020.12

Research paper (international conference proceedings), Joint Work, Corresponding author, Accepted

A problem of attack detection and state estimation in continuous time distributed observer system under combination attack which is defined as in the presence of measurement attack and observer communication attack is considered in this paper. We adopt the notion of virtual state to design an algorithm for attack detection. The algorithm is distributedly used in each local observer and does not need nonlocal information, thus it can be run by only itself. Additionally, we derive the inequality relationship between system graph connectivity and the number of the allowable attacked observer to achieve the detection and estimation with the proposed algorithm as a necessary and sufficient condition. A simple numerical example, finally, illustrates the effectiveness of the proposed algorithm.

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Transient and stability analysis of heterogeneous micro-grid networks subject to uncertainties

Mendoza F.G, Bauso D, Namerikawa T

IET Smart Grid (IET Smart Grid) 3 ( 6 ) 851 - 859 2020.12

Research paper (scientific journal), Joint Work, Accepted

In this study, networks of interconnected heterogeneous micro-grids are studied. The transient dynamics is modelled as an averaging process whereby micro-grids are assimilated to dynamic agents in a network. An analysis of the convergence of the consensus dynamics is carried out under different assumptions on the damping and inertia parameters and the topology of the network. This study provides an insight into the relation between the network topology and the system's response. An analysis of the ways in which the heterogeneous inertial parameters affect the transient response of the network is also implemented. Additionally, the conditions that guarantee stability are identified when the system is under the influence of uncertain non-linear parameters. Finally, simulations are carried out based on a model calibrated on an existing network in the UK under parameter uncertainties.

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Non-Cooperative Optimization Algorithm of Charging Scheduling for Electric Vehicle

M Yoshihara, MHM NOR, A Kono, T Namerikawa, Z Qu

SICE Journal of Control, Measurement, and System Integration (The Society of Instrument and Control Engineers ) 13 ( 6 ) 265 - 273 2020.11

Research paper (scientific journal), Joint Work, Last author, Accepted, ISSN 1882-4889

In this paper, we aim to propose a charging scheduling algorithm for electric vehicles on highways. While the number of electric vehicles has been increasing recently, charging stations are not becoming widespread compared to gas stations. The distance that an electric vehicle can run on one charge is only around 120km to 400km. Therefore, it is necessary to plan to recharge in advance when driving long distances. Problems related to planning algorithms are called charging scheduling problems of electric vehicles. In this paper, we assume that there is no difference in the power of the electric vehicle and the charging station, and consider the situation where each acts to maximize its profit. First, since the electric vehicle can select the charging station freely, it motivates us to solve the optimal allocation problem of the electric vehicle to the charging station using matching theory. Then, non-cooperative game theory is utilized to obtain the energy demand and energy price for the electric vehicles and charging stations, respectively. In addition, the convergence condition of the non-cooperative game is theoretically derived. Finally, the effectiveness of the proposed non-cooperative charging scheduling algorithm is confirmed by numerical simulation.

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Optimal Electric Vehicle Charging Scheduling by Matching Theory and Repeated Game

KONO Akari, NAKAZATO Takuya, NAMERIKAWA Toru

Transactions of the Society of Instrument and Control Engineers (The Society of Instrument and Control Engineers) 56 ( 11 ) 495 - 503 2020.11

Research paper (scientific journal), Accepted, ISSN 0453-4654

In this paper, the driver chooses the optimal charging station and determines the optimal energy demand when the highway enters, with the charging station and the electric vehicle controlled. The purpose of this study is to propose optimal charging scheduling. In previous studies, we considered that the charging price was not included in the driver's preference and also the price of the charging station was not optimal. In this paper, the price is included in the preference when the driver selects the charging station, and the optimal price for maximizing the profit is determined by a repeated game by designing the new utility function of the charging station. We theoretically prove the conditions under which repeated game converges, and finally perform numerical simulations to confirm the effectiveness of the proposed algorithm in a more realistic situation than in previous studies.

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Event-triggered and self-triggered formation control of a multi-agent system

T Namerikawa, R Toyota, K Kotani, M Akiyama

Artificial Life and Robotics 25 (4), 513-522 (Springer) 25 ( 4 ) 513 - 522 2020.10

Research paper (scientific journal), Joint Work, Lead author, Accepted, ISSN 1433-5298

In this paper, a distributed event-triggered formation control algorithm for a multi-agent system which consists of linear discrete-time agents is proposed based on control theory. For agents to achieve a formation, it is necessary to communicate with each other to feedback their information. For communication, wireless communications are desirable for various tasks since wired networks can constrain their movement. Also, each agent have to observe their states from sensors. Those energy consumption due to unnecessary calculation and communication of agents may shorten battery life of agents. By using the event-triggered protocol, which updates the control input aperiodically only when certain triggering condition is satisfied, we aim to reduce those calculation and communication by reducing the input update frequency. Also the multi-agent system is guaranteed to achieve a formation by determining the triggering condition of the control input based on Lyapunov’s stability theorem. At the end of the paper, the effectiveness of the proposed algorithm is verified by numerical simulation.

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Detection of Attacks in Smart Grids via Extended Kalman Filter and Correlation Analysis

J Sawodny, O Riedel, T Namerikawa

2020 59th Annual Conference of the Society of Instrument and Control … (2020 59th Annual Conference of the Society of Instrument and Control Engineers of Japan, SICE 2020) 663 - 669 2020.09

Research paper (international conference proceedings), Joint Work, Last author, Accepted

This paper discusses the detection of attacks on decentralized and intelligent power networks, so-called smart grids. The approach used here, estimates the states of the power network, which is modelled by its power flow, via an Extended Kalman Filter. The use of this filter allows the consideration of nonlinearities, thus enabling the modelling of the losses of the systems. The final detection of attacks on a generator in a power network is realized by a correlation analysis. The correlation analysis provides the result of the inner correlation of sequential signals. Based on this, an assessment can be made as to whether or not the network is affected by an attack.

Autonomous multi-robot tracking system for oil spills on sea surface based on hybrid fuzzy distribution and potential field approach

M Pashna, R Yusof, ZH Ismail, T Namerikawa, S Yazdani

Ocean Engineering 207, 107238 (Ocean Engineering) 207 2020.07

Research paper (scientific journal), Joint Work, Accepted, ISSN 0029-8018

© 2020 Elsevier Ltd Oil spill, may happen as a result of the offshore well vessel failures. The precise information about the location and real-time situation of the oil spill is essential to perform an efficient treatment of these environmental catastrophes. A novel approach of multi robot's system which can navigate autonomously and track oil spill on the sea surfaces. This system is able to self-adapt and path plan amidst environmental changes, including the temporospatial variation of the oil concentration. The method consists of two main parts, which are the modelling of the oil spill, the tracking system and autonomous control of the robots. The simulated model depicts the morphological complexities of the spatiotemporal changes in the oil spills. The fuzzy controller is designed to control the robots to control nonlinear and non-crisply distributed water surfaces where oil pollution occurs. Meanwhile, the multi-robot path planning system hybridised with artificial potential field approach to avoid the collision. Several numerical simulations with different scenarios are done to show the robustness of the methods, based on the accuracy and precision of tracking. The evaluation with the simulated ground truth demonstrates that accuracy and precision of the tracking system are more than 70 and 80 percent respectively.

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Load Frequency Control Using Iterative Gradient Method for Connected Power System Including Distributed Energy Resources

SEKINE Tetsuya, MIZUNO Keisuke, NAMERIKAWA Toru

Transactions of the Society of Instrument and Control Engineers (The Society of Instrument and Control Engineers) 56 ( 7 ) 361 - 369 2020.07

Research paper (scientific journal), Joint Work, Last author, Accepted, ISSN 0453-4654

This paper deals with load frequency control problem of power system. In recent years, due to the large introduction of generators using renewable energy, the relative load fluctuation increases, making it difficult to maintain power balance. Therefore, this paper proposes frequency control method using Moving Horizon Estimation and iterative gradient method for connected power system. In this paper, since system handles frequency control problems in real time, the system manager needs to grasp all states of power system every moment, and estimates the state of power system by using Moving Horizon Estimation. Next, control inputs are determined such that each area minimizes evaluation function including barrier function considering constraint conditions for generator and battery by using iterative gradient method. At this time, since the control target is connencted power system, it is represented as a model including the state of adjacent area, so that each area shares information with each other and performs cooperative control between areas. Finally, simulation of load frequency control using Moving Horizon Estimation and iterative gradient method is carried out and the effectiveness is confirmed.

Frequency Response-Based Initial Parameter Estimation for SOC of Lithium-Ion Battery

K Natori, K Mizuno, T Namerikawa, S Sartori, F Eliassen

IFAC-PapersOnLine 53 (2), 12695-12700 (IFAC-PapersOnLine) 53 ( 2 ) 12695 - 12700 2020.07

Research paper (international conference proceedings), Accepted, ISSN 2405-8963

In this paper, we propose a novel parameter initial value estimation method of Lithium-ion battery for state of charge (SOC) estimation by using Local Regression Modeling (LRM) and Vector Fitting (VF). To estimate SOC accurately using nonlinear Extended Kalman Filter(EKF), an adequate set of initial parameters of the battery model are required. Therefore, we apply LRM and VF method to derive the initial parameters and the battery model from a constructed database of frequency response data. In addition, we demonstrate the SOC estimation method using EKF by the determined initial value and model. Finally, the effectiveness of the proposed method is shown via several experimental results.

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Non-cooperative Optimization of Charging Scheduling for Electric Vehicle via Stackelberg Game and Matching Theory

M Yoshihara, T Namerikawa

IFAC-PapersOnLine 53 (2), 17029-17034 (IFAC-PapersOnLine) 53 ( 2 ) 17029 - 17034 2020.07

Research paper (international conference proceedings), Accepted, ISSN 2405-8963

In this paper, we deal with the charging scheduling optimization problem of electric vehicle in highway via Stackelberg game and matching theory. At first, we propose an algorithm for electric vehicle allocation to charging station which aims to uniformize waiting time of each charging station. In addition, we present energy demand and price decision problem and solve it using Stackelberg game. We compare Stackelberg equilibrium point and Nash equilibrium point and confirm Stackelberg game provide bigger benefit to charging station. Finally, we show validation of proposed algorithm via numerical simulations.

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Improving Rate of Convergence via Gain Adaptation in Multi-Agent Distributed ADMM Framework

T Rahman, Z Qu, T Namerikawa

IEEE Access 8, 80480-80489 (IEEE Access) 8 80480 - 80489 2020.05

Research paper (scientific journal), Joint Work, Last author, ISSN 2169-3536

© 2013 IEEE. In this paper, the Alternating Direction Method of Multipliers (ADMM) is investigated for distributed optimization problems in a networked multi-agent system. In particular, a new adaptive-gain ADMM algorithm is derived in a closed form and under the standard convex property in order to greatly speed up convergence of ADMM-based distributed optimization. Using Lyapunov direct approach, the proposed solution embeds control gains into weighted network matrix among the agents and uses those weights as adaptive penalty gains in the augmented Lagrangian. It is shown that the proposed closed loop gain adaptation scheme significantly improves the convergence time of underlying ADMM optimization. Convergence analysis is provided and simulation results are included to demonstrate the effectiveness of the proposed scheme.

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Local Attack Detection Algorithm under Combination Attacks in the Distributed Observers

SATO Shotaro, NAMERIKAWA Toru

Transactions of the Society of Instrument and Control Engineers (The Society of Instrument and Control Engineers) 56 ( 5 ) 284 - 292 2020.05

Research paper (scientific journal), Accepted, ISSN 0453-4654

In this paper, we propose an algorithm for state estimation and attack detection in distributed observer system and derive the condition for achieving the estimation and detection. In detail, the algorithm using the notion of virtual states can be used in each local observer for distributedly attack detection by oneself. In the perspective of attack, we define, not only measurement attack, but an observer communication attack which is the falsification of the transmitted data between local observers and also define a combination attack which combines the observer communication attack and measurement one. We derive the condition for estimation and detection under the combination attack as the theorem and, finally, verify the effectiveness of the proposed algorithm by numerical simulations.

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An optimized input/output-constrained control design with application to microgrid operation

R Harvey, Z Qu, T Namerikawa

IEEE Control Systems Letters 4 (2), 367-372 (IEEE Control Systems Letters) 4 ( 2 ) 367 - 372 2020.04

Research paper (scientific journal), Joint Work, Last author, Accepted, ISSN 2475-1456

© 2017 IEEE. In this letter, a nonlinear control design is presented for systems whose input and output vectors are saturated. The proposed synthesis includes an optimal tracker as the seed controller and explicitly imposes all the relevant constraints on system input, on the rate of change in the input, and on system output by using the tools of barrier functions, input-output feedback linearization, comparison argument, Lyapunov argument, and a real-Time constrained optimization. The proposed design is applied to microgrid operation with high penetration of renewable generation, where net load and variable generation must be balanced and the microgrid should be operated at an optimal or near-optimal performance level. Since traditional generation has a limited ramping rate, battery storage devices, and demand responses become necessary to effectively deal with variability of renewable generation and to maintain frequency stability, but their capacities are also limited. It is shown that the proposed design is effective for coordinated control of traditional generation, storage and demand response so that the power system frequency is guaranteed to be within the required operational limits and that renewable curtailment is eliminated or minimized.

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Optimization of Bidding Price and Power Dispatch in Electricity Market by Iterative Bidding

KATO Yusuke, NAMERIKAWA Toru

Transactions of the Society of Instrument and Control Engineers (The Society of Instrument and Control Engineers) 56 ( 4 ) 249 - 258 2020.04

Research paper (scientific journal), Last author, Accepted, ISSN 0453-4654

In this paper, a day-ahead electricity market where multiple consumers and suppliers in several regions bid for per unit electricity price and ISO decides power disaptch and inter-regional power flow amount is considered. We show that if ISO maximizes the difference between payment from customers and payment to suppliers, then the social welfare will be maximized. Then, we propose an algorithm to solve the optimal power dispatch problem using dual decomposition. Finally, simulation results show the effectiveness of the proposed algorithm.

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PV Power Prediction via Residual Correction and Hierarchical Multiple Buildings Energy Management

YAMAUCHI Ken, NAMERIKAWA Toru

Transactions of the Society of Instrument and Control Engineers (The Society of Instrument and Control Engineers) 56 ( 4 ) 208 - 216 2020.04

Research paper (scientific journal), Last author, Accepted, ISSN 0453-4654

This paper deals with photovoltaic (PV) power prediction and building energy management system (BEMS) in multiple buildings. First, we consider PV power prediction. We predict PV power by using k-means method and SVR. However, there is an error between prediction and actual generation. In order to solve this issue, we estimate prediction error in advance by markov process and revise the prediction. And, by applying copula to calculated point prediction, calculate interval prediction. Second, we consider 2 level BEMS. At first level, in each building, power consumption is determined considering comfort. At second level, in order to reduce total cost in all buildings, battery scheduling is calculated with robustness by applying scenario robust theory. And, at the end of each section, simulation results show the effectiveness of proposed prediction method and energy management method.

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Event-triggered and Self-triggered Formation Control of a Linear Multi-agent System

豊田凌，小谷健人，滑川徹

IEEJ Transactions on Electronics, Information and Systems 140 ( 3 ) 303 - 311 2020.03

Research paper (scientific journal), Last author, Accepted

Optimal Motion Planning of Connected and Automated Vehicles at Signal-Free Intersections with State and Control Constraints

MHM NOR, T Namerikawa

SICE Journal of Control, Measurement, and System Integration (公益社団法人計測自動制御学会) 13 ( 2 ) 30 - 39 2020.03

Research paper (scientific journal), Joint Work, Last author, Accepted, ISSN 1882-4889

This paper presents the optimal motion planning problem for connected and automated vehicles (CAVs) to cross a conflict area at an intersection with state and control constraints. First, we formulate the scheduled merging (or crossing) time for all CAVs as a mixed integer linear programming (MILP) problem where the merging time is solved frequently. Second, we formulate the optimal motion planning problem so that the CAVs can achieve their scheduled merging time as well as minimizing the energy consumption. Since we solve the motion planning problem analytically, not all the solutions are feasible to comply with the frequently updated merging time. To solve this problem, we propose a feasibility enforcement period (FEP). Then, we validate the proposed solution through simulation, and the results show that even the merging time is frequently updated, the CAVs can still achieve the merging time with a minimal deviation. Besides, our proposed framework also shows a significant improvement in terms of travel time as compared to the conventional one.

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Resilient Reinforcement in Secure State Estimation against Sensor Attacks with a priori Information

T Shinohara, T Namerikawa, Z Qu

IEEE Transactions on Automatic Control (IEEE Transactions on Automatic Control) 64 ( 12 ) 5024 - 5038 2019.12

Research paper (scientific journal), Joint Work, Accepted, ISSN 00189286

© 1963-2012 IEEE. Recent control systems severe depend on information technology infrastructures, especially the Internet of things (IoT) devices, which create many opportunities for the interaction between the physical world and cyberspace. Due to the tight connection, however, cyber attacks have the potential to generate evil consequences for the physical entities, and therefore, securing control systems is a vital issue to be addressed for building smart societies. To this end, this paper especially deals with the state estimation problem in the presence of malicious sensor attacks. Unlike the existing work, in this paper, we consider the problem with a priori information of the state to be estimated. Specifically, we address three prior knowledge - the sparsity information, (\alpha, \bar{n}_0)-sparsity information, and side information, and in each scenario, we show that the state can be reconstructed even if more sensors are compromised. This implies that the prior information reinforces the system resilience against malicious sensor attacks. Then, an estimator under sensor attacks considering the information is developed and, under a certain condition, the estimator can be relaxed into a tractable convex optimization problem. Further, we extend this analysis to systems in the presence of measurement noises, and it is shown that the prior information reduces the state-estimation error caused by the noise. The numerical simulations in a diffusion process finally illustrate the reinforcement and error-reduction results with the information.

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Optimal coordination and control of connected and automated vehicles at intersections via mixed integer linear programming

MHM NOR, T Namerikawa

SICE Journal of Control, Measurement, and System Integration (公益社団法人計測自動制御学会) 12 ( 6 ) 215 - 222 2019.11

Research paper (scientific journal), Joint Work, Accepted, ISSN 1882-4889

This paper addresses the crossing order problem for connected and automated vehicles at an intersection where the problem can lead to higher traffic congestion, especially in high traffic density. First, we formulated the problem with mixed integer linear programming where the solution yields optimal crossing time for each vehicle to cross the intersection. Then, we present an optimization framework to drive each vehicle towards the assigned crossing time while conserving the fuel consumption. Finally, we simulate the intersection scenario with the proposed solution, where it is shown that both congestion and fuel consumption can be reduced significantly.

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Integrating Demand Response Aggregators with Negawatt Trading Mechanisms in Electricity Markets

A Algarni, T Namerikawa

2019 North American Power Symposium (NAPS), 1-5 (51st North American Power Symposium, NAPS 2019) 2019.10

Research paper (international conference proceedings), Joint Work

© 2019 IEEE. In this paper, we propose a distributed power supply-demand management mechanism in a real-time market by utilizing various resources including demand reduction, balancing generators, and power flow changes. The proposed method aims to minimize the cost of balancing the supply with the demand. We simulate the results on the IEEJ EAST 30-machine system with four connected areas. The results show the feasibility of the proposed method and the establishment of a relationship between the demand response (DR) aggregator and the independent system operator (ISO).

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Traffic Signal Control Considering Switching Timing via Distributed Model Predictive Control

S Sasaki, T Namerikawa

2019 19th International Conference on Control, Automation and Systems (ICCAS … (International Conference on Control, Automation and Systems) 2019-October 286 - 291 2019.10

Research paper (international conference proceedings), Joint Work, Accepted

© 2019 Institute of Control, Robotics and Systems - ICROS. In this paper, we aim to alleviate traffic congestion on each link online by traffic signal control for local road transport network to be controlled. We first propose a transportation model with time delay system considering the travel time of the vehicle and calculate the optimal signal phases with variable cycle length and offset using distributed model predictive control for that model to reduce congestion rate on local roads. We then explain algorithms for distributed control that each intersection solves the optimization problem in parallel sharing information only with adjacent intersection. Finally, the effectiveness of the proposed method is confirmed by numerical simulation.

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Parking Lot Allocation Based on Matching Theory using Prediction-based Optimal Vehicle Routing

T Nakazato, T Namerikawa

2019 19th International Conference on Control, Automation and Systems (ICCAS … (International Conference on Control, Automation and Systems) 2019-October 1004 - 1009 2019.10

Research paper (international conference proceedings), Joint Work, Accepted

© 2019 Institute of Control, Robotics and Systems - ICROS. The purpose of this paper is to relax traffic congestion caused by the decrease in vehicle speed in case of a driver searching for a parking lot in traffic network, by using Smart Parking System. Smart Parking System is a system that allocates parking lot considering both the driver's preference and the parking lot manager's preference in advance. At that time, driver should know the optimal route and its time from currrent location to each parking lot. In this paper, Smart Parking System consider the road condition in traffic network and present the driver time by the optimal route from the driver's current location to each parking lot. Then, the parking lot allocation is determined by using matching theory considering both the driver's preference including information of optimal route and its time and the parking lot manager's preference. Finally, the effectiveness is confirmed by numerical simulations and results of parking lot allocation using optimal vehicle routing.

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Plug & Play Control System Design for Suprt Smart Society Based on Dissipativity

KOJIMA Chiaki, NAMERIKAWA Toru

Journal of The Society of Instrument and Control Engineers (The Society of Instrument and Control Engineers) 58 ( 8 ) 600 - 605 2019.08

Research paper (scientific journal), Last author, ISSN 0453-4662

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Optimal control of connected and automated vehicles at intersections with state and control constraints

MHBM Nor, T Namerikawa

2019 IEEE/ASME International Conference on Advanced Intelligent Mechatronics … (IEEE/ASME International Conference on Advanced Intelligent Mechatronics, AIM) 2019-July 1397 - 1402 2019.07

Research paper (international conference proceedings), Joint Work, Accepted

© 2019 IEEE. This paper addresses the optimal control problem (optimal acceleration and deceleration to minimize fuel consumption) for Connected and Automated Vehicles (CAVs) to cross an intersection with state and control constraints. First, we obtain the crossing time for the CAVs to cross the intersection with Mixed Integer Linear Programming (MILP). Then, the crossing time is used as a terminal time to formulate the optimal control problem and we utilized analytical solution (Hamiltonian analysis) to solve the problem. Finally, we simulated the proposed approach and the results show that, even with the frequently changing crossing time, the controller is capable of providing the solution to the optimal control problem.

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Parking lot allocation and dynamic parking fee system based on a mechanism design approach

H Nakanishi, T Namerikawa

2019 American Control Conference (ACC), 2683-2689 (Proceedings of the American Control Conference) 2019-July 2683 - 2689 2019.07

Research paper (international conference proceedings), Joint Work, Accepted

© 2019 American Automatic Control Council. In this paper, we present a discussion on smart parking systems in urban traffic networks. Reduced vehicle speed when drivers search for parking lots contributes to increased traffic jams in recent urban traffic networks. We aim to shorten the searching time for parking lots, which is one of the causes of traffic jams, by allocating available parking lots to drivers. Furthermore, we design a dynamic parking fee system and redistribute parking lots to equalize the profits earned by managers of multiple parking lots in traffic-congested areas. We then finally confirm the effectiveness of the proposed algorithm through numerical simulations.

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Cooperative transport of quad-rotor by consensus algorithm

K Kotani, T Namerikawa

2019 12th Asian Control Conference (ASCC), 1364-1369 (2019 12th Asian Control Conference, ASCC 2019) 1364 - 1369 2019.06

Research paper (international conference proceedings), Joint Work, Accepted

© 2019 JSME. At present, UAV is common to use as a single unit, but by operating as multi-agent system, it is possible to possibly be able to carry out more sophisticated tasks. For example, it may be possible to realize long-distance transportation with heavy object which impossible by a single drone. Therefore, we propose a control method to achieve cooperative transport so that the payload follows the virtual leader. We assume the transporting problem connected payload and multiple quad-rotors with cable. In this research, we treated quad-rotor as a model regarded as a linear secondary system and used consensus algorithm to achieve the purpose. Finally we verified its usefulness by simulation.

Secure State Estimation under Measurement Attacks using Virtual State in Distributed Observer System

S Sato, T Namerikawa

2019 12th Asian Control Conference (ASCC), 1683-1688 (2019 12th Asian Control Conference, ASCC 2019) 1683 - 1688 2019.06

Research paper (international conference proceedings), Joint Work, Accepted

© 2019 JSME. In this paper, a distributed secure state estimation problem that is state estimation in distributed observer system in the presence of attacks is mainly discussed. We introduce the notion of graph-based distributed observer representation, virtual state, and a subgroup to derive a condition for the secure state estimation. By the graph-based distributed observer representation, we can consider the system's observability and communication pass connectivity as graph connectivity at once. With the notion of virtual state and the subgroup, we derive the state estimation condition which is the inequality relationship between the number of the allowable attacked observer and the graph connectivity as a theorem. Finally, a simple numerical example verifies the theorem.

Optimization of power flow and scheduling for EV charging based on distributed control

K Mizuno, T Namerilkawa

2019 12th Asian Control Conference (ASCC), 627-631 2019.06

Research paper (international conference proceedings), Joint Work, Accepted

Energy management of smart home by model predictive control based on EV state prediction

Y Ogata, T Namerikawa

2019 12th Asian Control Conference (ASCC), 410-415 (2019 12th Asian Control Conference, ASCC 2019) 410 - 415 2019.06

Research paper (international conference proceedings), Joint Work

© 2019 JSME. The purpose of this paper is to minimize the total electricity cost while considering comfort in the home. We propose home energy management (HEMS) method by model predictive control (MPC) based on EV state prediction. If charging and discharging can be planned based on electric vehicle (EV) usage prediction, it can minimize the charging with an external charging station because it can be charged in advance at home. We introduce a model considering the passage of time in order to predict the use of EV. Finally, we confirm the validity of this research through numerical simulations.

Data-Driven Mean-Field Game Approximation for a Population of Electric Vehicles

D Bauso, T Namerikawa

2019 IEEE Data Science Workshop (DSW), 285-289 (2019 IEEE Data Science Workshop, DSW 2019 - Proceedings) 285 - 289 2019.06

Research paper (international conference proceedings), Joint Work, Accepted

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A hypothesis of state covariance decorrelation effects to partial observability SLAM

H Ahmad, NA Othman, MM Saari, MS Ramli, MBM Mazlan, T Namerikawa

Indonesian Journal of Electrical Engineering and Computer Science 14 (2 … (Indonesian Journal of Electrical Engineering and Computer Science) 14 ( 2 ) 588 - 596 2019.05

Research paper (scientific journal), Joint Work, Accepted, ISSN 2502-4752

© 2019 Institute of Advanced Engineering and Science. All rights reserved. This paper analyze the performance of partial observability in simultaneous localization and mapping(SLAM) problem. The study focuses mainly on the effect of having a decorrelation technique known as Covariance Inflation to the estimation. The matrix inversion will be the main element to be investigated through two conditions with respect to some defined environment namely as unstable partially observable SLAM and partially observable SLAM via matrix norm analysis. For assessment purposes, the Extended Kalman Filter estimation is referred as the estimator to understand how the conditions can influence the results. The simulation results depicted that, the matrix norm is able to determine the efficiency of estimation and is proportional to the uncertainties of the system.

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マルチ Quad-rotor による協調搬送システムに向けた RISE による外乱補償

小谷健人，滑川徹

電気学会論文誌 C (電子・情報・システム部門誌) 139 ( 4 ) 341 - 349 2019.04

Research paper (scientific journal), Joint Work, Accepted

Formation Control Multi Quad-rotor System Corresponding to Suppression of Disturbance and Collision Avoidance Using RISE

KOTANI Kento, NAMERIKAWA Toru

Transactions of the Society of Instrument and Control Engineers (The Society of Instrument and Control Engineers) 55 ( 1 ) 68 - 77 2019.01

Research paper (scientific journal), Joint Work, Accepted, ISSN 0453-4654

In this paper, we propose a control method which combine collision avoidance method and RISE (Robust Integral of the Sign of Error) for multiple Quad-rotor formation control methods, and confirm effectiveness of this method that is resistant to disturbance by lowering the risk of collision. First, we modeled quad-rotor as a linear system. Next, we described a method to suppress nonlinear disturbance using RISE which is a type of sliding mode control. In addition, we introduced collision avoidance method, and derived the conditions to achieve accurate formation by using Lyapunov stability theory. Finally, we implemented an algorithm in the simulation, and confirmed that the proposed method is functioning correctly.

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A Novel Detection Strategy for Kidnapped Robot Problem in Monte Carlo Localization Using Corridor-Type Map

I Bukhori, ZH Ismail, T Namerikawa

Journal of Electrical And Electronics Engineering 2 (1), 7-12 2019

Joint Work

Feasibility and Performance Analysis of Model Predictive Signal Control Based on a Micro Traffic Model Including Individual Vehicle Motion

OKAMOTO Ryota, TEZUKA Yuki, MUKAI Masakazu, HATANAKA Takeshi, IINO Yutaka, NAMERIKAWA Toru

Transactions of the Society of Instrument and Control Engineers (The Society of Instrument and Control Engineers) 54 ( 12 ) 849 - 856 2018.12

Research paper (scientific journal), Last author, Accepted, ISSN 0453-4654

This paper is intended to analyze benefits of microscopic real-time optimization for traffic signal control. To this end, we first present a microscopic traffic model consisting of signals and vehicles, where each vehicle dynamics is explicitly incorporated in the form of a mixed logical dynamical system (MLDS) differently from many other related publications taking macroscopic flow models. We then formulate a model predictive control (MPC) problem and then reduce the problem to a mixed integer programming problem. Furthermore, we introduce a linear temporal logic (LTL) constraint to reduce the computation burden and to eliminate unrealistic solutions. The proposed control scheme is then applied to a real-time traffic simulator and it is confirmed that: (i) the number of waiting vehicles for traffic lights is reduced with 54.5% as compared to a fixed-time control scheme and (ii) the average computation time is reduced to about one-tenth relative to the case without the LTL constraint.

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Parking Lot Allocation and Dynamic Parking Fee Design Based on Mechanism Design

NAKANISHI Hiroaki, YOSHIHARA Miyu, NAMERIKAWA Toru

Transactions of the Society of Instrument and Control Engineers (The Society of Instrument and Control Engineers) 54 ( 10 ) 745 - 756 2018.10

Research paper (scientific journal), Joint Work, Accepted, ISSN 0453-4654

In this paper, we discuss the smart parking system in urban traffic network. In recent years, the decline in vehicle speed when searching for parking lots has been caused traffic jam in urban traffic network. Then, in this paper, we aim at shortening the searching time for parking lots, which is one of the causes of traffic jam, by allocating parking lots being available to drivers. Furthermore, we design the dynamical parking fee and redistribute parking lots to level the multiple parking manager's profit in traffic area. Finally, we confirm the effectiveness of proposed algorithm in numerical simulation.

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Passivity-Based Stability Analysis of Electricity Market Trading with Dynamic Pricing

Y Okawa, K Muto, T Namerikawa

SICE Journal of Control, Measurement, and System Integration 11 (5), 390-398 (公益社団法人計測自動制御学会) 11 ( 5 ) 390 - 398 2018.09

Research paper (scientific journal), Joint Work, Accepted, ISSN 1882-4889

This paper deals with passivity-based stability analysis of electricity market trading with dynamic pricing. In the deregulated electricity market, power consumers and generators will participate in market trading as market players. For such a new kind of the market trading system, the dynamic pricing procedure has to be taken into account of the intermittent participation of power consumers and generators. Then, this paper discusses the stability of the electricity market trading system including power flow using passivity analysis. This paper also shows that the optimal power demand, supply and electricity prices are asymptotically stable and these values are derived in a distributed manner through market trading.

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Reach Set-Based Secure State Estimation against Sensor Attacks with Interval Hull Approximation

T Shinohara, T Namerikawa

SICE Journal of Control, Measurement, and System Integration (公益社団法人計測自動制御学会) 11 ( 5 ) 399 - 408 2018.09

Research paper (scientific journal), Joint Work, Accepted, ISSN 1882-4889

This paper deals with the problem of secure state estimation in an adversarial environment with the presence of bounded noises. The problem is given as min-max optimization, that is, the system operator seeks an optimal estimate which minimizes the worst-case estimation error due to the manipulation by the attacker. To derive the optimal estimate, taking the reach set of the system into account, we first show that the feasible set of the state can be represented as a union of polytopes, and the optimal estimate is given as the Chebyshev center of the union. Then, for calculating the optimal state estimate, we provide a convex optimization problem that utilizes the vertices of the union. On the proposed estimator, the estimation error is bounded even if the adversary corrupts any subset of sensors. For the sake of reducing the calculation complexity, we further provide another estimator which resorts to the interval hull approximation of the reach set and properties of zonotopes. This approximated estimator is able to reduce the complexity without degrading the estimation accuracy sorely. Numerical comparisons and examples finally illustrate the effectiveness of the proposed esti

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Merging Control for Automated Vehicles Using Distributed Model Predictive Control

HAYASHI Yasuhiro, TOYOTA Ryo, NAMERIKAWA Toru

Transactions of the Society of Instrument and Control Engineers (The Society of Instrument and Control Engineers) 54 ( 9 ) 718 - 727 2018.09

Research paper (scientific journal), Accepted, ISSN 0453-4654

This paper deals with merging control of automated vehicles using distributed model predictive control. Firstly, we consider a road model which has two main lanes. In the distributed control algorithm, vehicles repeat sharing the planned future trajectory with other vehicles traveling in the vicinity of each vehicle by using communication and re-planning its own trajectory considering the future trajectory of other vehicles. Moreover, in order to further improve the stability of model predictive control, terminal constraints are set and feasible conditions for optimization problems under the terminal conditions are derived. At the last part of this paper, we discuss the result of numerical simulations using distributed merging control algorithm and mention the effectiveness of proposed methods and future works.

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Robust prediction and MPC-based optimal energy management for HVAC System

T Suda, T Namerikawa

IFAC-PapersOnLine 51 (25), 472-477 (IFAC-PapersOnLine) 51 ( 25 ) 662 - 667 2018.09

Research paper (international conference proceedings), Joint Work, Accepted, ISSN 2405-8963

© 2018 The purpose of this paper is to achieve a cut in peak electricity demand and lower electricity costs through the optimal management of a heating ventilation and air conditioning (HVAC) system. In addition, robust solar radiation prediction is required for optimal HVAC management. First, solar radiation prediction is applied using a clustering technique based on the k-means method, classifying all data on similar types of solar radiation. Second, an H∞ filter, which is a robust prediction method for outliers, is applied. Next, an optimal HVAC management system is considered for operating the air conditioning, such as the cooling and heating of each room. Model predictive control (MPC), which is used to predict and control the future changes in the temperature of the room and the electrical charge from solar radiation, is applied. Finally, we confirmed the validity of this research through numerical simulations.

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Optimal Control Based on Quasi-Newton Method Considering Cooperation of Constrained Distributed Energy Resources

T Sekine, T Namerikawa

2018 57th Annual Conference of the Society of Instrument and Control … (2018 57th Annual Conference of the Society of Instrument and Control Engineers of Japan, SICE 2018) 958 - 963 2018.09

Research paper (international conference proceedings), Joint Work, Accepted

© 2018 The Society of Instrument and Control Enginners - SICE. In this paper, load frequency control by optimal control algorithm using quasi-Newton method for microgrid introducing diesel generator and battery is discussed. In the proposed method, we consider microgrid model including diesel generator and battery. Also, saturation is taken into account as a constraint on the input to the model of diesel generator and battery. Then, a cost function considering the storage capacity constraint is formulated. Therefore, we propose an algorithm using the quasi-Newton method to determine inputs that minimize the formalized cost function. In addition to the quasi-Newton method, we propose an algorithm using Backward Sweep to match the terminal condition. Finally, we confirm the effectiveness of the proposed method through numerical simulations.

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Non-Cooperative Optimization of Charging Scheduling of Electric Vehicle via Stackelberg Game

M Yoshihara, T Namerikawa, Z Qu

2018 57th Annual Conference of the Society of Instrument and Control … (2018 57th Annual Conference of the Society of Instrument and Control Engineers of Japan, SICE 2018) 1658 - 1663 2018.09

Research paper (international conference proceedings), Joint Work, Accepted

© 2018 The Society of Instrument and Control Enginners - SICE. In this paper, we deal with the charging scheduling optimization problem of electric vehicle using Stackelberg game. Stackelberg game is one of game theory classified as hierarchical, repeating, and non-cooperative game. The charging station determines the price to maximize its own profit from selling energy and each EV determines the energy demand to maximize the charge benefit by competing with other EVs. At this time, we guarantee that Nash equilibrium exists within the EV group. Finally, using numerical simulation, we show that the game reaches an Stackelberg equilibrium.

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Merging of Connected and Automated Vehicles at Roundabout Using Model Predictive Control

MHBM Nor, T Namerikawa

2018 57th Annual Conference of the Society of Instrument and Control … (2018 57th Annual Conference of the Society of Instrument and Control Engineers of Japan, SICE 2018) 272 - 277 2018.09

Research paper (international conference proceedings), Joint Work, Accepted

© 2018 The Society of Instrument and Control Enginners - SICE. This paper addresses a merging problem of connected and automated vehicles at single lane with two different freeways roundabout. First, we assume that the merging vehicle already knew the environment of the roadway beforehand. After that, we formulate the optimization problem based on model predictive control framework which includes lane keeping and collision avoidance. Finally, we show in the simulation results that the proposed solution is capable of merging the vehicle at the roundabout effectively.

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Event-Triggered Formation Control of a Generalized Multi-Agent System

R Toyota, T Namerikawa

2018 57th Annual Conference of the Society of Instrument and Control … (2018 57th Annual Conference of the Society of Instrument and Control Engineers of Japan, SICE 2018) 940 - 945 2018.09

Research paper (international conference proceedings), Joint Work, Accepted

© 2018 The Society of Instrument and Control Enginners - SICE. In this paper, we propose an event-triggered formation control algorithm for a multi-agent system consists of linear discrete agents in order to reduce energy consumption due to unnecessary calculation and communication of agents. By using the event-triggered protocol, which updates the control input aperiodically only when certain triggering condition is satisfied, calculation and communication frequency are reduced. Also the multi-agent system is guaranteed an almost sure stability by determining the control input update timing by the triggering condition which is based on Lyapunov's stability theorem. Finally we verify the effectiveness of the proposed algorithm by numerical simulation.

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Passivity-Short-based Stability Analysis on Electricity Market Trading System Considering Negative Price

K Muto, T Namerikawa, Z Qu

2018 IEEE Conference on Control Technology and Applications (CCTA), 418-423 (2018 IEEE Conference on Control Technology and Applications, CCTA 2018) 418 - 423 2018.08

Research paper (international conference proceedings), Joint Work, Accepted

© 2018 IEEE. This paper deals with a distributed decision method for determining the electricity price considering the negative price in the market trading. In addition, we analyze the stability and convergence properties for the market trading system using the concept of passivity-short. At first, mathematical models of market participants' behavior which maximize their own profits are discussed. Then, we construct a trading system based on dynamic pricing considering plug and play operation that each market participant intermittently participates in market trading. As for the optimal electricity price, even if the optimal price might be negative, we indicate the stability of the system can be guaranteed by using passivity-short which is a relaxed concept of passivity. Finally, numerical simulation results illustrate that each value decided by the market trading converges to the optimal value.

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Coordinated Optimal Control of Constrained DERs

R Harvey, Z Qu, T Namerikawa

2018 IEEE Conference on Control Technology and Applications (CCTA), 224-229 (2018 IEEE Conference on Control Technology and Applications, CCTA 2018) 224 - 229 2018.08

Research paper (international conference proceedings), Joint Work, Accepted

© 2018 IEEE. In this paper, a coordinated optimal control is designed to simultaneously satisfy multiple power system objectives at the distribution network level. With high penetration of renewables, traditional generation and control may not be enough to compensate for intermittent changes in net load. Dynamic coordination of battery storage devices and demand response at aggregated distributed energy resource (DER) sites becomes necessary to maintain power system operation, however, each dynamic power component operates at different time scales. Frequency stabilization can be achieved by designing optimal controls for traditional generation, storage devices and demand response. The proposed optimal controls naturally render frequency separation of these load balancing mechanisms. Given a 24-hour net load forecast, optimal tracking control inputs are designed subject to constraints of selected system elements to ensure optimal performance of the power system. Simulation results are presented and discussed.

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Load Frequency Control for Power System Using Moving Horizon Estimation and Robust Model Predictive Control

HIRANAKA Takuto, SEKINE Tetsuya, NAMERIKAWA Toru

Transactions of the Society of Instrument and Control Engineers (The Society of Instrument and Control Engineers) 54 ( 7 ) 606 - 616 2018.07

Research paper (scientific journal), Accepted, ISSN 0453-4654

In this paper, load frequency control problem for power system is discussed. The control is conducted to retain power demand supply balance by controlling output of generators in power network. However, it becomes harder to retain the balance because of large volume injection of renewable energy whose output is uncertain. To resolve the problem, some approaches are considered in this research field. One is to use dispersion type power sources like battery in addition to conventional generators like thermal power generator and hydroelectric generator. Another is to apply new control theories and methods. The other is the load frequency control considering demand response by using a controllable load on the consumer side. Especially among them, in this paper, power system which holds large volume wind turbine generator, turbine generator and battery is focused on and new control method is proposed. Concretely, load frequency control based moving horizon estimation and robust model predictive control is proposed in order to satisfy the constraints of state and control input.

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Power Demand-supply Adjustment in Multi-area Power Grid Based on Negawatt Trading via Regret Matching and VCG Mechanism Design

NAGAMI Kentaro, MUTO Keita, NAMERIKAWA Toru

Transactions of the Society of Instrument and Control Engineers (The Society of Instrument and Control Engineers) 54 ( 7 ) 617 - 625 2018.07

Research paper (scientific journal), Joint Work, Accepted, ISSN 0453-4654

This paper deals with a power demand-supply management based on negawatt trading, and the purpose of this research is to keep demand supply balance and to minimize the social cost of negawatt trading, balancing generator, and power flow. In this research, consumer and Independent System Operator (ISO) participate in the electricity market, and each consumer acts based on Regret Matching which is one of the learning algorithms. Furthermore, as the incentive design of negawatt trading, we consider strategy-proofness and individual rationality using VCG mechanism design. Then, we propose a novel negawatt trading algorithm based on Regret Matching and VCG mechanism design. Finally, simulation results show the effectiveness of the proposed algorithm.

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Scenario-Based Robust MPC for Energy Management Systems with Renewable Generators

S Sato, T Namerikawa

2018 37th Chinese Control Conference (CCC), 2304-2309 (Chinese Control Conference, CCC) 2018-July 2304 - 2309 2018.07

Research paper (international conference proceedings), Joint Work, Accepted

© 2018 Technical Committee on Control Theory, Chinese Association of Automation. This paper addresses photovoltaics (PV) power prediction and energy storage problem which are known to be a key technology in energy management systems (EMS). Extending results of the point prediction of PV power, we first describe a prediction interval (PI) method using a copula, which can express the relation between a multivariable joint distribution and each marginal distribution. Then, resorting to the PI method, the energy storage optimization problem in a building is developed. A scenario robust (SR) optimization theorem, which calculates the robustness of the optimal solution, is applied to the proposed PI method, and hence we obtain an optimal energy storage solution taking the robustness of the solution into account. Additionally, we propose a method which combines a model predictive control (MPC) technique and SR to reduce the total electricity costs. The simulation results finally illustrate the cost reduction and robustness of the proposed method.

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Merging control for automated vehicles using decentralized model predictive control

Y Hayashi, T Namerikawa

2018 IEEE/ASME International Conference on Advanced Intelligent Mechatronics … (IEEE/ASME International Conference on Advanced Intelligent Mechatronics, AIM) 2018-July 268 - 273 2018.07

Research paper (international conference proceedings), Joint Work, Accepted

© 2018 IEEE. Ahstract-This paper deals with merging control of automated vehicles using distributed model predictive control. We consider a road model which has two main lanes. In the distributed control algorithm, vehicles repeat sharing the planned future trajectory with other vehicles traveling in the vicinity of each vehicle by using communication and replanning its own trajectory considering the future trajectory of other vehicles. Moreover, in order to further improve the stability of model predictive control, terminal constraints are set and feasible conditions for optimization problems under the terminal conditions are derived. At the last part of this paper, we confirm the effectiveness of proposed methods through simulations.

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Reach Set-based Attack Resilient State Estimation against Omniscient Adversaries

T Shinohara, T Namerikawa

2018 Annual American Control Conference (ACC), 5813-5818 (Proceedings of the American Control Conference) 2018-June 5813 - 5818 2018.06

Research paper (international conference proceedings), Joint Work, Accepted

© 2018 AACC. We consider the problem of secure state estimation in an adversarial environment with the presence of bounded noises. We assume the adversary has the knowledge of the healthy measurements and system parameters. To countervail the dangerous attacker, the problem is given as a min-max optimization, that is, the system operator seeks an estimator which minimizes the worst-case estimation error due to the manipulation by the attacker. On the proposed estimator, the estimation error is bounded at all times even if the system removing an arbitrary set of 2l sensors is not observable, where l is the number of the compromised sensors. To this end, taking the reach set of the system into account, we first show the feasible set of the state can be represented as a union of polytopes, and the optimal estimate is given as the Chebyshev center of the union. Then, for calculating the optimal state estimate, we provide a convex optimization problem that utilizes the vertices of the union. Additionally, the upper bound of the worst-case estimation error is derived theoretically, and we also show a rigorous analytical bound under a certain condition. The attacked sensor identification

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Optimal power demand management by aggregators using matching theory

H Ikegami, T Namerikawa

2018 Annual American Control Conference (ACC), 4584-4589 (Proceedings of the American Control Conference) 2018-June 4584 - 4589 2018.06

Research paper (international conference proceedings), Joint Work, Accepted

© 2018 AACC. This paper addresses optimal power demand management in the electricity market. First, we model the behavior of players, consumers, aggregators, and the market. Each consumer entity acts to maximize its own profit. The aggregator decides how much individual consumer power demand should be reduced if total power demand exceeds power generation constraints. We propose a method for an aggregator to make this decision using mechanism design and matching theory. Finally, we show that an algorithm can manage power demand and improve consumers' profits using simulation results.

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Design considerations for river floating sensors

ZH Ismail, A Omairi, T Namerikawa, AI Cahyadi

ASEAN Engineering Journal 8 (1), 1-13 (ASEAN Engineering Journal) 8 ( 1 ) 1 - 13 2018.06

Research paper (scientific journal), Joint Work

© 2018 ASEAN University Network/Southeast Asia Engineering Education Development Network. All rights reserved. In order to utilize the flow of a river to generate power, it is crucial to develop a system that is able to obtain and record the river's characteristics in various aspects. A simple but effective method has to be created to allow researchers to collect and study the parameters of a river in order to predetermine the final build of the power generation model. A floating sensor that is able to collect and give a real-time data has been developed using readily available hardware as well as custom made parts. This paper describes a design methodology for river floating sensors and results from a case study performed in the actual controlled channel are presented to demonstrate the effectiveness of the design decisions.

Optimal Demand Adjustment of Consumers with Various Appliances Using Dynamic Pricing

K Muto, Y Okawa, T Namerikawa

SICE Journal of Control, Measurement, and System Integration 11 (3), 146-153 (公益社団法人計測自動制御学会) 11 ( 3 ) 146 - 153 2018.05

Research paper (scientific journal), Joint Work, Accepted, ISSN 1882-4889

This paper deals with a demand adjustment problem of each consumer having appliances by an aggregator based on optimal pricing in a day-ahead electricity market. In this paper, we model consumers, generators, and aggregators and design a market mechanism, where they act to maximize their own profit based on the power price and decide the electricity supply and demand. The dual decomposition is applied to the market problem to maximize the social welfare, where the proposed algorithm decides an electricity price based on the exchange of information among market participants to solve each distributed problem for improving convergence. In addition, the convergence of this proposed method is proven using Lyapunov's stability theorem. Finally, simulation results show that matching of supply and demand is achieved, while satisfying constraints on the consumption amount and the use time of each appliance, and the price determined using proposed price update algorithm converges to a certain price.

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Consensus-Based Cooperative Formation Control for Multiquadcopter System With Unidirectional Network Connections

Namerikawa, Toru, Kuriki, Yasuhiro, Khalifa, Ahmed

JOURNAL OF DYNAMIC SYSTEMS MEASUREMENT AND CONTROL-TRANSACTIONS OF THE ASME (Journal of Dynamic Systems, Measurement and Control, Transactions of the ASME) 140 ( 4 ) 2018.04

Research paper (scientific journal), Single Work, ISSN 0022-0434

In this paper, we consider cooperative control issues for a multiunmanned aerial vehicle (UAV) system. We propose a cooperative formation control strategy with unidirectional network connections between UAVs. Our strategy is to apply a consensus-based algorithm to the UAVs so that they can cooperatively fly in formation. First, we show that UAV models on the horizontal plane and in the vertical direction are expressed as a fourth- and secondorder system, respectively. Then, we show that the stability discriminants of the multi-UAV system on the horizontal plane and in the vertical direction are expressed as polynomials. For a network structure composed of bidirectional or unidirectional network connections under the assumption that the network has a directed spanning tree, we provide conditions for formation control gains such that all roots of the polynomials have negative real parts in order for the UAVs to asymptotically converge to the positions for a desired formation by using the generalized Routh stability criterion. The proposed control algorithms are validated through simulations, and experiments are performed on multiple commercial small UAVs to validate the proposed cont

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Perfect Stealthy Attacks in Cyber-physical Systems

Shinohara Takumi, NAMERIKAWA Toru

Transaction of SICE (The Society of Instrument and Control Engineers) 54 ( 3 ) 309 - 319 2018.03

Research paper (scientific journal), Joint Work, Accepted, ISSN 0453-4654

Security of Cyber-Physical Systems (CPS) against cyber attacks is one of the most critical issues that should be investigated. In this paper, we deal with the vulnerabilities due to novel integrity cyber attacks named perfect stealthy attacks and the countermeasure against them in CPS which are modeled as a stochastic Linear Time-Invariant (LTI) system equipped with a Kalman filter, an LQG controller, and a χ2 failure detector. The attacks are designed by a sophisticated attacker so that the measurement residual of the compromised system coincides with the healthy one, and can ruin the system definitely. First, from an attacker's standpoint, we show an existence condition and a design procedure of the attacks using invariant subspace property. Then, on the other hand from a system supervisor's standpoint, the countermeasure against the malicious attacks using an aperiodic transmission scheme based on the Nash bargaining game is discussed. Finally, the dangerousness of the attacks and the effectiveness of the proposed detection method are verified through numerical simulations.

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Passivity-based stability analysis of dynamic electricity pricing with power flow

Okawa Y., Namerikawa T., Qu Z.

2017 IEEE 56th Annual Conference on Decision and Control, CDC 2017 (2017 IEEE 56th Annual Conference on Decision and Control, CDC 2017) 2018-January 813 - 818 2017.12

Research paper (international conference proceedings), Joint Work, Accepted

© 2017 IEEE. This paper deals with passivity-based stability analysis of dynamic electricity pricing considering power flow. In the near future electricity market, power consumers and generators will participate in electricity market trading as market players. For such a market trading system, the dynamic pricing procedure is required to consider the intermittent participation of power consumers and generators. Then, this paper discusses the stability of the electricity market trading system including power flow using passivity analysis. This paper also shows that the optimal power demand, supply and electricity prices are asymptotically stable and these values are derived in a distributed manner through market trading.

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On the Vulnerabilities Due to Manipulative Zero-Stealthy Attacks in Cyber-Physical Systems

Takumi SHINOHARA, Toru NAMERIKAWA

SICE Journal of Control, Measurement, and System Integration (The Society of Instrument and Control Engineers) 10 ( 6 ) 563 - 570 2017.11

Research paper (scientific journal), Joint Work, Accepted

In this paper, we analyze the vulnerabilities due to integrity cyber attacks named zero-stealthy attacks in cyber-physical systems, which are modeled as a stochastic linear time invariant (LTI) system equipped with a Kalman filter, an LQG controller, and a χ2 failure detector. The attacks are designed by a sophisticated attacker so that the measurement residual of the compromised system coincides with the healthy one, and thus it is impossible to detect the attacks. First, we characterize and analyze an existence condition of the attacks from an attacker's standpoint. Then, we extend the attacks into an attacker's goal: The scenario when the adversary wishes to manipulate the systems to an objective designed by him/her. Our results provide that the attacker can manipulate the compromised system to the objective without accessing the networks of real-time sensor or actuator data. Finally, we verify the dangerousness of the attacks through a simple numerical example.

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Distributed Optimal Power Management via Negawatt Trading in Real-Time Electricity Market

Okawa Yoshihiro, Namerikawa Toru

IEEE Transactions on Smart Grid (IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC) 8 ( 6 ) 3009 - 3019 2017.11

Research paper (scientific journal), Accepted, ISSN 1949-3053

This paper presents a distributed optimal power supply-demand management method by using negawatt trading in a real-time electricity market. In the negawatt trading, power consumers reduce their own power demand and receive monetary reward from the market operator. This paper discusses a power adjustment method via negawatt trading by including charge or discharge power from energy storage systems. In order to derive appropriate electricity incentive prices for consumers and to use energy storage systems in power grids efficiently, we deal with a power adjustment problem by using some future power supply information from generators. We then show a novel market algorithm to solve this problem in a distributed manner through market trading. Finally, numerical simulation results illustrate the effectiveness of our proposed method.

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Optimal Pricing of Electricity by Aggregator for Demand Adjustment of Each Consumer Having Appliances

Keita Muto, Yoshihiro Okawa, Toru Namerikawa

2017 56TH ANNUAL CONFERENCE OF THE SOCIETY OF INSTRUMENT AND CONTROL ENGINEERS OF JAPAN (SICE) (IEEE) 1246 - 1251 2017.09

Research paper (international conference proceedings), Accepted

This paper deals with demand adjustment problem of each consumer having appliances by an aggregator based on the optimal pricing problem in a day-ahead electricity market. In this paper, we model consumer, generator, aggregator and design a market mechanism and they act to maximize their own profit based on the power price and decide the electricity supply and demand. The dual decomposition is applied to market problem to maximize the social welfare and the proposed algorithm decides electricity price based on the exchange of information among market participants to solve each distributed problem for improving convergence. In addition, the convergence of this proposed method is proven using Lyapunov stability theorem. Finally, simulation results show that matching of supply and demand is sufficiently achieved.

Short-Term Wind Power Prediction for Wind Turbine via Kalman Filter Based on JIT Modeling

TOMOKI ISHIKAWA,1 TAKAAKI KOJIMA,1 and NAMERIKAWA Toru

Electrical Engineering in Japan 198 ( 3 ) 86 - 96 2017.02

Research paper (scientific journal), Joint Work, Accepted

This paper addresses wind power prediction, which is known to be a key technology in energy management systems. In this paper, a 24-h-ahead power prediction method using a filter theory is proposed for wind power generation. The prediction method is a simple algorithm. The procedure of prediction consists of two steps: the data processing and the calculation of the predicted values. In data processing, in order to obtain the correlative data from the database, we employ just-in-time modeling. In the calculation of the predicted values, we propose a regression model for wind speed and wind power, and the unknown parameters are estimated using a constrained Kalman filter. Moreover, in the procedure used to estimate the unknown parameters, reduction and convergence of the variables are also guaranteed. Finally, the advantages of the proposed method over the conventional method are shown through actual prediction evaluations.

リチウムイオンバッテリ充電率推定のための周波数応答データを用いたパラメータ初期値推定

NAMERIKAWA Toru

計測自動制御学会論文集 53 ( 1 ) 112 - 120 2017.01

Research paper (scientific journal), Joint Work, Accepted

In this paper, we propose a novel parameter initial value estimation method of Lithium-ion battery for state of charge (SOC) estimation by using Local Regression Modeling (LRM) and Vector Fitting (VF). To estimate SOC accurately using nonlinear extended Kalman filter, an adequate set of initial parameters of the battery model are required. Therefore, we apply LRM and VF method to derive the initial parameters and the battery model from database of the frequency response. In addition, we show the SOC estimation method using EKF by determined initial value and model. Finally, the effectiveness of the proposed method is shown via several experimental results.

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Optimal Power Demand Management among Consumers with Aggregator considering State and Control Constraints

Yoshihiro Okawa, Toru Namerikawa

2016 IEEE 55TH CONFERENCE ON DECISION AND CONTROL (CDC) (IEEE) 801 - 806 2016.12

Research paper (international conference proceedings), Accepted, ISSN 0743-1546

This paper presents a novel optimal power demand management method for power consumers with an aggregator considering state and control constraints. The aggregator is an organization who manages some consumers to achieve demand response efficiently. This paper proposes a power demand adjustment method for the aggregator to allocate power reduction among consumers in a distributed manner. Specifically, this method simultaneously derives the optimal power reduction of each consumer using a gradient method and determines the control inputs by solving a quadratic programming problem with state and input constraint conditions. This paper also shows the convergence of the proposed algorithm, and finally, numerical simulation results illustrate the effectiveness of the proposed method.

Multi-Period Regional Energy Management Based on Dynamic Pricing with Non-Deficit Real-Time Market Trading

Yoshihiro OKAWA,NAMERIKAWA Toru

SICE Journal of Control, Measurement, and System Integration (The Society of Instrument and Control Engineers) 9 ( 5 ) 207 - 215 2016.09

Research paper (scientific journal), Joint Work, Accepted

This paper deals with a regional demand response method based on dynamic electricity pricing in a multi-period energy market. In the proposed method, first, the power supply and demand in each area are determined considering power flow using the retail and wholesale electricity prices in a day-ahead market. Next, in a real-time market, the proposed method adjusts to power deviations caused by errors in power generation with power demand reduction by consumers and increased power supply from balancing generators. In addition, in order to guarantee the non-deficiency in the real-time market trading, the incentive and penalty price design methods are discussed in this paper. This paper also shows a distributed algorithm for obtaining the optimal values of each market player in both the day-ahead and real-time markets, and finally, numerical simulation results demonstrate the effectiveness of the proposed method.

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Dynamic Pricing Using H∞ Control with Uncertain Behavior in Electricity Market Trading

Yoshihiro OKAWA, NAMERIKAWA Toru

SICE Journal of Control, Measurement, and System Integration (The Society of Instrument and Control Engineers) 9 ( 5 ) 192 - 200 2016.09

Research paper (scientific journal), Joint Work, Accepted

This paper deals with a dynamic pricing using the H∞ control with uncertain behavior in electricity market trading. The dynamic pricing is a decision procedure of an electricity price based on power supply and demand balance in power grids. However, in a future deregulated electricity market, both power consumers and generators determine their own power demand and supply selfishly according to the price information. Moreover, uncertainties are also included in their behavior. For this problem, we propose a novel price decision method using the locational price-updating H∞ controllers. This paper shows a design process of this price-updating H∞ controller to evaluate the following performance to reduce supply-demand imbalances in power grids and the robustness against uncertainties in electricity market participants' behavior, respectively. In addition, this paper also shows the effectiveness of our proposed price decision method using the designed H∞ controller through numerical simulation results.

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A Comparative Study of Extended Kalman Filter and H-infinity Filtering For State Estimation of Stewart Platform Manipulator

Shady A. Maged, A. A. Abouelsoud, Ahmed M. R. Fath El Bab, Toru Namerikawa

2016 55TH ANNUAL CONFERENCE OF THE SOCIETY OF INSTRUMENT AND CONTROL ENGINEERS OF JAPAN (SICE) (IEEE) 1727 - 1732 2016.09

Research paper (international conference proceedings), Accepted

This paper presents the estimation of both position and velocity of Stewart Manipulator by means of limbs potentiometer measurements and MEMS inertial sensors. The estimation used the Extended Kalman Filter (EKF) and H-infinity optimal filtering technique based on the combination of these sensors. The two types of filters are used as nonlinear state estimators to the Stewart platform which is modeled as a stochastic differential equations due to measurement noise in case of EKF and as a continuous time system model in case of H-infinity filtering technique. The results of the both filters are compared with each other on the Stewart platform DELTALAB EX800 using MATLAB SimMechanics toolbox. The simulation results show that Kalman filters are not the best choice for parallel manipulator state estimation as they bear from the hypothesis of statistical noise with zero mean as well as known noise covariance, which may reduce its performance. For these reasons, H-infinity filter may be the alternative of Kalman filter.

Robust-Formation Control of Multi-Autonomous Underwater Vehicles based on Consensus Algorithm

Vina Putranti, Zool H. Ismail, Toru Namerikawa

2016 IEEE CONFERENCE ON CONTROL APPLICATIONS (CCA) (IEEE) 2016.09

Research paper (international conference proceedings), Accepted, ISSN 1085-1992

This paper discusses a robust formation control for multi-Autonomous Underwater Vehicles (AUVs). The AUVs are disturbed by exogenous perturbation during the mission, thus, the Robust Integral Sign of Error (RISE) is adopted. For a formation control, a leader-follower structure based on consensus algorithm is adopted and the use of graph theorem named connected graph is useful to exchange the required information. An AUV called leader is determined to bring a group of information, while the others called followers, receive the information from a leader. Lyapunov analysis proves the stability as well as the error convergence of proposed controller, whilst some simulations are performed to compare between the proposed controller, RISE with consensus, and the existing robust controller, Sliding Mode Controller (SMC) which is combined with consensus algorithm. As a result, the proposed controller works better and produces smaller error.

On the Fault Tolerant Control of a Quadrotor Manipulation System via MPC and DOb Approaches

Ahmed Khalifa, Mohamed Fanni, Toru Namerikawa

2016 55TH ANNUAL CONFERENCE OF THE SOCIETY OF INSTRUMENT AND CONTROL ENGINEERS OF JAPAN (SICE) (IEEE) 700 - 705 2016.09

Research paper (international conference proceedings), Accepted

Recently, the Aerial Manipulation System becomes very attractive for a wide range of applications due to its unique features. However, control of such system is quite challenging. One of the critical challenge is that this system is very susceptible to actuators' faults. In this paper, a Passive Fault Tolerant Control System is proposed to address this issue with robust and optimal performance. The robustness is achieved using a linear Disturbance Observer (DOb) loop. Based on the linearization capability of DOb, a standard Model Predictive Control (MPC) is then used and the resulting control scheme is characterized by both a low computational load and optimal actuators' efforts with respect to conventional nonlinear robust solutions. This controller is tested to achieve the tracking of a point-to-point task space references under the effect of actuators' faults, picking/releasing a payload, changing the operating region, and measurement noise. Efficacy of the proposed technique is verified via numerical simulations.

Formation control considering disconnection of network links for a Multi-UAV system

Mori Shouhei, Namerikawa Toru

Journal of Robotics and Mechatronics (Fuji Technology Press) 28 ( 3 ) 343 - 350 2016.06

Research paper (scientific journal), Joint Work, Accepted, ISSN 0915-3942

The formation control algorithm we propose for a multi-UAV uses LMI conditions. Starting with a linearized model of UAVs such as a quadrotor, we introduce a formation control algorithm based on a consensus algorithm, a leader-follower structure, graph theory and the Lyapunov stability theorem for a liner system. We propose the control algorithm using the Lyapunov theorem and LMI conditions for intermittent communication. We demonstrate the proposed control algorithm’s stability even when network links are disconnected. Numerical simulation and experimental validation show the proposed control’s effectiveness.

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Distributed Power Supply-demand Management Based on Negawatt Trading with Energy Storage System

Yoshihiro Okawa, Toru Namerikawa

2016 EUROPEAN CONTROL CONFERENCE (ECC) (IEEE) 1812 - 1817 2016.06

Research paper (international conference proceedings), Accepted

This paper presents a distributed power supply demand management method based on negawatt trading including charge or discharge power from energy storage systems. In the negawatt trading, power consumers reduce their own power demand and receive monetary reward from the market operator. In order to derive appropriate electricity incentive prices for consumers and to use energy storage systems in power grids efficiently, we deal with a power adjustment problem using some future power supply information in this paper. We then show a novel market algorithm to solve this problem in a distributed manner through market trading among the market operator and consumers. Finally, we verify the effectiveness of our proposed method with numerical simulation results.

Fuel Consumption Optimization for a Power-Split HEV via Gain-Scheduled Model Predictive Control

Hitoshi Iyama, Takatoshi Suda, Masaaki Nishito, Hiroki Seto, Masakazu Mukai and Toru NAMERIKAWA

Transactions of the Society of Instrument and Control Engineers (IEEE) 52 ( 1 ) 1 - 10 2016.01

Research paper (scientific journal), Joint Work, Accepted, ISSN 0453-4654

In this paper, we propose a fuel consumption optimization technique for a power-split HEV via gain-scheduled model predictive control. The control algorithms for the powertrain choose the power split between engine and electric motor in order to minimize the fuel consumption. Operating conditions of the HEV change during driving in real time by road conditions and driver demand. Therefore, it is necessary to have optimal control in real time and to consider the time-varying motor condition. We model the HEV and propose a gain-scheduled model predictive control. Using the proposed technique, we succeeded in optimizing fuel consumption for a power-split HEV. Finally, the proposed approach was validated by numerical simulations.

Optimal energy management for smart grid system considering battery characteristics

Mukai Tatsuya, Igari Shunsuke, Namerikawa Toru

Electrical Engineering in Japan (English translation of Denki Gakkai Ronbunshi) (WILEY-BLACKWELL) 194 ( 1 ) 18 - 26 2016.01

Research paper (scientific journal), Joint Work, ISSN 0424-7760

This paper discusses optimal energy management considering battery characteristics for smart grid and microgrid systems. Energy storage systems are very important for energy peak shifting and peak load cutting in microgrid and smart grid systems, but optimal battery formulation and energy management in the use of expensive energy storage system and methods of taking account of battery characteristics are still in the developmental stage. First, the optimal battery placement for a smart grid system with lithium-ion batteries is considered as a means of lifetime extension. The battery choice index for this optimal battery utilization problem of optimal energy management is discussed. Second, a smart grid system with a distributed battery system for grid frequency control with consideration of distributed control and battery characteristics is discussed. Optimal controllers for distributed battery systems to reduce the battery load and to expend the battery lifetime are designed. Simulations are used to demonstrate the effectiveness of the proposed method in comparison with conventional methods.

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Detection of Replay Attack on Smart Grid with Output Including Code Signal

Takashi Irita and Toru Namerikawa

T. SICE 51 ( 12 ) 822 - 828 2015.12

Research paper (scientific journal), Joint Work, Accepted, ISSN 0453-4654

Ensuring cyber security of smart grid based on supervisory control and data acquisition using information and communications technology has been becoming a major challenge. Especially, a replay attack is a dangerous cyber attack affecting integrity and authorization. The goal of this paper is to detect replay attack that is one of cyber attacks on the sensors of a control system. We propose a detecting method adding intentional noise to sensors as code signal playing a time-stamping part. Replay attack can immediately be reflected by using fault diagnosis matrices that are composed of the estimator and observed values. Finally, we show simulation results to analyze effectiveness of the proposed method.

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Regional Demand-Supply Management based on Dynamic Pricing in Multi-period Energy Market

Yoshihiro Okawa, Toru Namerikawa

2015 54TH IEEE CONFERENCE ON DECISION AND CONTROL (CDC) (IEEE) 7201 - 7206 2015.12

Research paper (international conference proceedings), Joint Work, Accepted

This paper deals with a regional demand response method based on dynamic electricity pricing in a multi-period energy market. In the proposed method, first, the power demand and supply in each area are determined considering power flow using the retail and wholesale electricity prices in a day-ahead market. Next, to adjust for power deviations caused by errors in power generation, our proposed method solves the problem of optimal allocation between power demand reduction by consumers and increased power supply from balancing generators in a real-time market. This paper also shows a distributed algorithm for obtaining the optimal values of each market player in both the day-ahead and real-time markets, and finally, numerical simulation results demonstrate the effectiveness of the proposed method.

Load Frequency Control of a Microgrid Based on H∞ Control Considering Response Speed of Generators

Kenji Masui, Shun Takamura and Toru Namerikawa

T. SICE 51 ( 8 ) 570 - 578 2015.08

Research paper (scientific journal), Joint Work, Accepted, ISSN 0453-4654

In this paper, load frequency control problem of a microgrid is discussed. The control is conducted to retain power demand supply balance by controling output of generators in power system. However, it becomes harder to retain the balance because of large-volume injection of renewable energy. For the problem, two approaches are considered in this research field. One is to use dispersion type power sources like batteries, and the other is to apply new control theories. Therefore, we focus on a microgrid which holds a wind turbine generator, a diesel generator and a battery, and propose a technique based a static H_∞ control. In the beginning, we design the generalized plant considering the difference of the response speed of a diesel generator and a battery. Then, static H_∞ control is applied to the generalized plant. Moreover, an LMI condition to avoid control gains to cause too big control input are combined with static H_∞ control. In numerical simulation, we validate that the controller can suppress frequency deviation and deviation of residual capacity of the battery. Futhermore, we show that the approach can design controllers with lower dimensions, and avoid undesirable control gains. In experiment with a generator and a variable resistance, the effectiveness of the controller is also confirmed.

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Real-Time Pricing Mechanism for Electricity Market With Built-In Incentive for Participation

Namerikawa Toru, Okubo Norio, Sato Ryutaro, Okawa Yoshihiro, Ono Masahiro

IEEE Transactions on Smart Grid (IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC) 6 ( 6 ) 2714 - 2724 2015.07

Research paper (scientific journal), Joint Work, Accepted, ISSN 1949-3053

This paper proposes a game-theoretic approach to design a distributed real-time electricity pricing mechanism. Our approach is novel in that it guarantees individual rationality, meaning that it provides suppliers and consumers with a guaranteed incentive to participate in the real-time pricing market. Such an incentive is devised by offering a time-varying, situation-dependent subsidy that guarantees that a supplier/consumer profits by switching from a fixed-price contract to the real-time pricing contract. Although we assume that suppliers and consumers decide supply and demand quantities in a fully distributed manner to maximize their own profit, the proposed mechanism guarantees under moderate conditions that the market converges through an iterative process to a Nash equilibrium that maximizes social welfare. Furthermore, in order to guarantee safe operation of an electrical grid, our pricing mechanism increases stability of load frequency control, and at the same time, achieves supply-demand equilibrium by explicitly taking into account an equality constraint through dual decomposition method. We empirically demonstrate by simulations the individual rationality of the proposed mechanism as well as the convergence to supply-demand equilibrium.

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Formation Control with Collision Avoidance for a Multi-UAV System Using Decentralized MPC and Consensus-Based Control

Yasuhiro KURIKI and Toru NAMERIKAWA

SICE Journal of Control, Measurement, and System Integration, (IEEE) 8 ( 4 ) 285 - 294 2015.07

Research paper (scientific journal), Joint Work, Accepted, ISSN 1882-4889

In this paper, the authors propose a cooperative formation control strategy with collision-avoidance capability
for a multi-unmanned aerial vehicle (UAV) system using decentralized model predictive control (MPC) and consensus-
based control. Consensus-based control algorithms are applied for formation flying in three-dimensional space. However,
UAVs where these formation control algorithms are applied have not the ability to avoid collisions. Decentralized model
predictive control (MPC) is applied to generate control inputs for formation flying with collision-avoidance capability.
Using decentralized MPC, each UAV plans only its own action to track the trajectory specified by the formation control
algorithm within the feasible regions satisfying collision-avoidance. The authors show how the optimization problems
with coupled constraints such as collision-avoidance can be solved by each decoupled UAV in parallel with the other
UAVs so that the decisions independently taken by each UAV can ensure consistency in coupled constraints of collision-
avoidance. The computation time is also taken into account because it is a crucial factor to apply MPC to actual UAVs.
Finally, the proposed approach is validated by some simulations.

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Decentralized Fault Detection of Multiple Cyber Attacks in Power Network via Kalman Filter

Takashi Irita, Toru Namerikawa

2015 EUROPEAN CONTROL CONFERENCE (ECC) (IEEE) 3180 - 3185 2015.07

Research paper (international conference proceedings), Last author, Accepted

This paper discusses faults diagnosis method of multiple cyber attacks in networked electrical power systems. We deal with a power network of a centralized system, and then, some parameters are estimated by Kalman filter. Using a sensor network system, each of sensor nodes can exchange information by wireless communication. A fault diagnosis method is proposed by using both fault detection diagnosis matrix and fault distinction matrix. The former is composed of estimated values and observed values. On the other hand, the latter is composed of observed values and calculated values via the senor network. Finally, the effectiveness of the proposed approach is validated by a simulation experiment.

Power System Stabilization by Direct Load Control Based on Strategy-Proofness and Individual Rationality

Ryutaro Sato, Toru Namerikawa

2015 AMERICAN CONTROL CONFERENCE (ACC) (IEEE) 5913 - 5918 2015.07

Research paper (international conference proceedings), Joint Work, Last author, Accepted, ISSN 0743-1619

This paper proposes a novel direct load control method to stabilize the system frequency. The proposed method utilizes the consumers' controllable loads for load frequency control. By solving an optimization problem to maximize the social welfare function, the input required for the frequency control is allocated among the controllable loads and the load frequency control generator in an economically rational manner. To introduce the direct control program for smooth operation of the power system, preventing consumers from cheating and guaranteeing their benefits are required. Thus, strategy-proofness and individual rationality based on the Groves and Clarke mechanism were used to design the electricity charge. Each consumer bids on the utility functions truthfully to the independent system operator and gains from participating in the proposed direct load control program. The effectiveness of the proposed method was demonstrated through numerical simulations.

Dynamic Electricity Pricing via the H-infinity Control Considering Uncertainties in Market Participants' Behavior

Yoshihiro Okawa, Toru Namerikawa

2015 EUROPEAN CONTROL CONFERENCE (ECC) (IEEE) 1064 - 1069 2015.07

Research paper (international conference proceedings), Last author, Accepted

This paper deals with a dynamic pricing via the H-infinity control considering uncertainties in market participants' behavior. The dynamic pricing is a decision procedure of an electricity price based on power demand and supply information from selfish power consumers and generators. However, since market participants have uncertainties in their behavior, the price decision procedure is required to have robustness against these uncertainties for stable operation of power systems. Then, in this paper, we propose a novel price decision procedure via the H-infinity control and also show the effectiveness of our proposed price decision method in simulation results.

Distributed Dynamic Pricing with Alternating Decision Making of Market Players

Yoshihiro Okawa, Toru Namerikawa

2015 54TH ANNUAL CONFERENCE OF THE SOCIETY OF INSTRUMENT AND CONTROL ENGINEERS OF JAPAN (SICE) (IEEE) 888 - 893 2015.07

Research paper (international conference proceedings), Last author, Accepted

This paper deals with a distributed decision procedure for determining the electricity price for a future smart grid. In order to derive the optimal regional prices and improve the convergence speed of the algorithm without private information of market players, we propose a price decision algorithm with an alternating decision making of market players. In this paper, we show that the optimal regional prices derived by using our proposed algorithm maximize the social welfare of power networks which includes profits of power consumers and power suppliers with renewable energy generators. Also, we discuss the convergence property of the proposed price decision algorithm. Finally, the feasibility of our proposed dynamic pricing methodology is shown with numerical simulation results.

Distributed dynamic pricing based on demand-supply balance and voltage phase difference in power grid

Okawa Yoshihiro, Namerikawa Toru

Control Theory and Technology (South China University of Technology) 13 ( 2 ) 90 - 100 2015.05

Research paper (scientific journal), Accepted, ISSN 2095-6983

This paper discusses a distributed decision procedure for determining the electricity price for a real-time electricity marketin an energy management system. The price decision algorithm proposed in this paper derives the optimal electricity pricewhile considering the constraints of a linearized AC power grid model. The algorithm is based on the power demand-supplybalance and voltage phase differences in a power grid. In order to determine the optimal price that maximizes the social welfare distributively and to improve the convergence speed of the algorithm, the proposed algorithm updates the price through the alternating decision making of market participants. In this paper, we show the convergence of the price derived from our proposed algorithm. Furthermore, numerical simulation results show that the proposed dynamic pricing methodology is effective and that there is an improvement in the convergence speed, as compared with the conventional method.

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Optimal Pricing Algorithm in the Electricity Market with Battery and Accumulator and Demand–Supply Balancing

MIYANO YukiNAMERIKAWA Toru

Electrical Engineering in Japan 191 ( 4 ) 8 - 18 2015.04

Research paper (scientific journal), Joint Work

This paper considers the day-ahead market with batteries
and accumulators to level power generation. First, we
model consumers with batteries, generators with batteries,
and accumulators, all of whom strive to maximize their
own profit. An optimal pricing algorithm based on dual
decomposition and the steepest descent method is derived
and shown to be stable. Finally, the effectiveness of the algorithm is demonstrated by means of numerical simulations
which indicate that it achieves demand–supply balance.

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Propagation Coefficient Estimation for Gas Concentration Prediction Problem via Kalman Filter

TOKUMOTO Shinichiro,IRITA Takashi, NAMERIKAWA Toru

計測自動制御学会論文集 51 ( 3 ) 206 - 213 2015.03

Research paper (scientific journal), Joint Work, Accepted

This paper is one of the researches to countermeasure against disaster. This paper treats the short-term future
prediction of gas concentration in a building for safer evacuation. Moreover, in order to treat disaster, such
as re, failure of sensor installed in a building is assumed. Therefore, a fault-tolerant system against sensor's
failure is designed. First, a concept of propagation coefficient is introduced, and a gas concentration model is
constructed by propagation coefficient and amount of gas generation. And, in order to estimate these values,
we apply Kalman Filter to this model. As this paper should consider sensor's failure, the fault-tolerant Kalman
Filter is proposed. Then, by using the estimated result, the short-term future of gas concentration is predicted.
Finally, we show experimental results to analyze effectiveness of the proposed method.

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Sufficient Condition for Estimation in Designing ∞ Filter-Based SLAM

Nur Aqilah Othman, Hamzah AhmadNAMERIKAWA Toru

Hindawi Publishing Corporation Mathematical Problems in Engineering (HINDAWI PUBLISHING CORP) 2015 1 - 15 2015.02

Research paper (scientific journal), Joint Work, Accepted, ISSN 1024-123X

Extended Kalman filter (EKF) is often employed in determining the position of mobile robot and landmarks in simultaneous localization and mapping (SLAM). Nonetheless, there are some disadvantages of using EKF, namely, the requirement of Gaussian distribution for the state and noises, as well as the fact that it requires the smallest possible initial state covariance. This has led researchers to find alternative ways to mitigate the aforementioned shortcomings. Therefore, this study is conducted to
propose an alternative technique by implementing ∞ filter in SLAM instead of EKF. In implementing ∞ filter in SLAM, the parameters of the filter especially need to be properly defined to prevent finite escape time problem. Hence, this study proposes a sufficient condition for the estimation purposes. Two distinct cases of initial state covariance are analysed considering an indoor environment to ensure the best solution for SLAM problem exists along with considerations of process and measurement noises
statistical behaviour. If the prescribed conditions are not satisfied, then the estimation would exhibit unbounded uncertainties and consequently results in erroneous inference about the robot and landmarks estimation. The simulation results have shown the reliability and consistency as suggested by the theoretical analysis and our previous findings.

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Short-Term Wind Power Prediction for Wind Turbine via Kalman Filter based on JIT Modeling

ISHIKAWA TOmoki, KOJIMA Takaaki, NAMERIKAWA Toru

電気学会論文誌C 135 ( 1 ) 81 - 89 2015.01

Research paper (scientific journal), Joint Work, Accepted

This paper addresses wind power prediction which is known to be a key technology in EMS(Energy Management Systems). In this paper, 24 hours ahead power prediction method using a filtering theory is proposed for wind power generation. The prediction method is a simple algorithm, the procedure of prediction consists of two steps, the data processing and the calculation of predicted values. In the data processing, in order to get the correlative data from the database, we employ JIT(Just-In-Time) Modeling. In the calculation of predicted value, we propose the regression model for wind speed and wind power, and the unknown parameters are estimated via constrained kalman filter. Moreover, in a procedure of estimation of the unknown parameters, reduction and the convergence of them are also guaranteed. Finally, the advantages of the proposed
method over the conventional method are shown through actual prediction evaluations.

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バッテリ特性を考慮したスマートグリッドの最適エネルギーマネジメント

NAMERIKAWA Toru

電気学会論文誌C 134 ( 12 ) 1862 - 1868 2014.12

Research paper (scientific journal), Joint Work, Accepted

In this paper, the optimal energy management considering battery characteristics for smart grid and micro grid systems is discussed. The energy storage system is very important for the energy peak shift and peak cut for micro
grid and smart grid system because of these backgrounds. However, optimal battery formulation and energy management
to suppress by using expensive energy storage system and considering battery characteristics are still in a
developmental stage. First, the optimal battery placement for smart grid system with Lithium-ion battery is dealt with
for lifetime extending. The battery choice index for this optimal battery determination problem to formulate optimal
energy management is discussed. Second, the smart grid system with distributed battery system for grid frequency
control considering distributed control and battery characteristics is dealt with. Optimal controllers for each distributed battery systems are designed to reduce battery load and to expend battery lifetime are designed. The effectiveness of the proposed method is shown via simulations by comparing with conventional methods.

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H∞ Filter-Based Short-Term Electric Load Prediction Considering Characteristics of Load Curve

HOSODA YasuhikoNAMERIKAWA Toru

Electronics and Communications in Japan 97 ( 12 ) 1 - 10 2014.12

Research paper (scientific journal), Joint Work

This paper deals with ∞ filter-based short-term electric load prediction taking into consideration the characteristics of the load curve. We propose a predictive
method to forecast the future electric load demand for 36
h from 12:00 PM, and evaluate the peak and bottom of the load curves on the next day. We propose a load model, estimate the unknown parameters of the model by means
of an ∞ filter using the data separated for nonworking
days and weekdays, with the same pattern of the previous
data chosen and assigned to the model parameters.
The simulation results show the effectiveness of the proposed prediction methodology.

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Hierarchical Control of Power Networks by using Overlapping Information

Tomoharu Suehiro, Toru Namerikawa

2014 14TH INTERNATIONAL CONFERENCE ON CONTROL, AUTOMATION AND SYSTEMS (ICCAS 2014) (IEEE) 1140 - 1145 2014.10

Research paper (international conference proceedings), Accepted, ISSN 2093-7121

This study deals with decentralized and hierarchical control for electric power networks by using overlapping information. The control objective is to minimize the cost function of the load frequency control problem. The control law consists of three steps. We apply the decentralized hierarchical control methodology to large-scale electrical power networks consisting of distributed power storage and generation sources such as batteries and wind power generators. Through several numerical simulation results of decentralized power networks, we verified their stability, compared the proposed and the previous decentralized methods, and showed the effectiveness of the proposed method.

Cooperative Control of Multi-Agent System with Disturbance

TACHIBANA Yoshihiro, MORI SyoheiNAMERIKAWA Toru

計測自動制御学会論文集 50 ( 9 ) 669 - 676 2014.09

Research paper (scientific journal), Joint Work, Accepted

This paper proposes a cooperative control of multi-agent system with disturbance. First, we introduce the sec-
ond order model with disturbance for agent. The network topology among agents is undirected and connected,
and information of reference is allowed to be available to at least one agent. Second, we propose the control law
consists of graph theory, consensus algorithm and RISE. Graph theory and consensus algorithm are utilized to
converge the states of agents to reference value, and RISE is utilized to suppress the disturbance. Then, we show
the proposed control law guarantees the agents achieve synchronization, and derive the condition to achieve the
control objective. Finally, simulation results show the effectiveness of the proposed control law.

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Dynamic Pricing Considering Constraints of Power Grids

Yoshihiro Okawa, Toru Namerikawa

2014 Proceedings of the SICE Annual Conference (SICE) (IEEE) 1484 - 1489 2014.09

Research paper (international conference proceedings), Joint Work, Accepted, ISSN 1550-0322

This paper deals with a model of a real-time electricity market for a smart grid, and discusses how to decide wholesale and retail prices of electricity among market participants: power consumers, power suppliers and an independent system operator. In this paper, we consider a linearized AC model of a power grid with a direct current process and show that the wholesale price for suppliers is determined as the optimal Lagrange multiplier corresponding to the nodal power balance constraints. In addition, we propose a decision procedure for the retail pricing of electricity for consumers. In order to improve the convergence speed of the algorithm, we apply the iterative gradient method with line search to a retail pricing decision procedure, in which the optimal step size is determined in each iteration step. Simulation results, finally, show the effectiveness of the proposed retail pricing decision procedure.

Actuation technology and its application in ambient intelligence

Namerikawa Toru

Journal of the Institute of Electronics, Information and Communication Engineers (The Institute of Electronics, Information and Communication Engineers) 97 ( 8 ) 679 - 683 2014.08

Single Work, Accepted, ISSN 0913-5693

アンビエントセンサネットワーク(ASN)システムでは,知的環境とノード間のネットワークを利用した情報の最適化を行うことが可能であり,単体のセンサによるセンシングと比較して省電力化,耐故障性,多次元情報の収集などの面で優れていることが知られている.最近では大規模センサネットワークに対してアクチュエーション技術(制御技術)を応用することで,エネルギー効率を考慮したシステム構築に関する研究が進んでいる.本稿では,ASNのアクチュエーション,つまり制御システムへの応用を目指し,マルチホップセンサネットワークを介して得られた情報を用いたフィードバック制御系の構成問題を扱う.

Formation Control of UAVs with a Fourth-order Flight Dynamics

Y.KURIKIT.NAMERIKAWA

SICE Journal of Control, Measurement, and System Integration 7 ( 2 ) 74 - 81 2014.03

Research paper (scientific journal), Joint Work, Accepted

In this paper, we study cooperative control problems with a multi-UAV (Unmanned Aerial Vehicle) system expressed as a fourth-order system using a consensus-based algorithm. We first show that a linearized model of UAVs like quadrotors is expressed as a fourth-order system, and then propose a formation control algorithm for the fourth-order system after formulating a problem. The proposed control law is based on a consensus algorithm, and a leader-follower
structure is also applied to the control law so that the leader can provide the quadrotors with commands such as their desired states. And then, we show that the proposed control algorithm can guarantee accurate formation keeping when fundamental assumptions about the network composed of the multiple UAVs are satisfied. Finally, the proposed approach is validated by some simulations.

SLAM Problem via H-infinity Filter with Compensation for Intermittent Observation

Yoshihiro Okawa, Toru Namerikawa

2014 IEEE 13TH INTERNATIONAL WORKSHOP ON ADVANCED MOTION CONTROL (AMC) (IEEE) 2014.03

Research paper (international conference proceedings), Accepted, ISSN 1943-6572

This paper deals with the Simultaneous Localization and Mapping (SLAM) problem via the H-infinity filter with compensations for intermittent observations. In order to estimate positions of a robot and landmarks accurately under intermittent observations, we propose the method with a novel filter which detects and compensates intermittent observations by comparing the obtained data with their estimations. This paper also shows the convergence of the estimated error covariance matrices. With simulation and experimental results, we confirm that the state of the robot and the environmental conditions are estimated accurately via the proposed filter under intermittent observations and that the derived theorems of the convergence are correct.

Diagnosis of Cyber Attacks and Faults in Power Networks by Using State Fault Diagnosis Matrix

Y.Fujita, Y.Okawa and T.Namerikawa

計測自動制御学会論文集 (計測自動制御学会) 49 ( 12 ) 1131 - 1138 2013.12

Research paper (scientific journal), Joint Work, Accepted

This paper discusses cyber attacks and faults diagnosis method for networked electrical power systems. A　power system is divided into some areas, then phase angles and angular frequencies are estimated by Kalman　filter in each area. Then we propose a diagnosis method for the power grid by using state and output fault　diagnosis matrices which are composed of the estimate value and output matrix. These diagnosis matrices can　immediately reflect an existence or non-existence of abnormal signal. Finally we show simulation results to analyze effectiveness of the proposed method.

Decentralized Hierarchical Control of Power Networks with Overlapping Information

T.Suehiro, K. Masui and T.Namerikawa

計測自動制御学会論文集 (計測自動制御学会) 49 ( 12 ) 1121 - 1130 2013.12

Research paper (scientific journal), Joint Work, Accepted

This paper deals with a decentralized hierarchical control of power networks by using overlapping information.
The control objective is to minimize the cost function of load frequency control problem. The control law is　constructed through three steps. In the 1st step, we make a hierarchical system with overlapping information. In
the 2nd step, a relationship between the original system and the hierarchical system is confirmed. In the 3rd step,
the hierarchical decentralized control for the hierarchical system is constructed and the decentralized hierarchical
control law is contracted to the original system. Then, we show the effectiveness of the load frequency control
by using the proposed control method.

Passivity and RISE based robust control for bilateral teleoperation system with communication delay

Kawai Yasunori, Namerikawa Toru

Proceedings of 2013 IEEE International Conference on Control Applications (IEEE) 270 - 275 2013.10

Research paper (international conference proceedings), Joint Work, Accepted

In this paper, a method for passivity- and robust integral of the sign of the error (RISE)-based control of a nonlinear teleoperation system with communication delays is proposed. This control strategy can accurately achieve coordinate positioning under conditions with viscous friction and unmodeled effects compensation errors, and its stability condition is independent of robot model parameter uncertainties and time delay. Using passivity-based stability analysis, the stability and tracking performance of this system are demonstrated, and experimental trials are performed to verify its effectiveness. © 2013 IEEE.

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Optimal pricing algorithm in the electricity market with battery and accumulator and demand-supply balancing

Miyano Yuki, Namerikawa Toru

IEEJ Transactions on Electronics, Information and Systems 133 ( 10 ) 1855 - 1863 2013.10

Research paper (scientific journal), Joint Work, Accepted, ISSN 0385-4221

This paper considers Day-Ahead Market with battery and accumulator to level power generation. First, we model consumer with battery, generator with battery and accumulator to maximize their own profit. Then, the optimal pricing algorithm based on dual decomposition and Steepest Descent Method and proof the stability of the algorithm is proposed. Finally, we show the effectiveness of the algorithm with some numerical simulations which indicate that the proposed algorithm achieves the demand-supply balancing. © 2013 The Institute of Electrical Engineers of Japan.

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Game Theoretic Real-Time Pricing Based on Dual Decomposition and　its Application to Load Frequency Control of Power Networks

N．Okubo, R.Sato and T.Namerikaw

計測自動制御学会論文集 (計測自動制御学会) 49 ( 10 ) 961 - 968 2013.10

Research paper (scientific journal), Joint Work, Accepted

This paper deals with game theoretic real-time pricing method based on dual decomposition and its application
to load frequency control of power networks. The proposed pricing method in this study aims to solve the　constrained optimization problem consist of each player’s utility and social welfare under selfish players. Selfish　player’s decision is a Nash equilibrium solution considering their own cost functions. We show this method can　lead their own decision to social welfare maximization.
Finally we show the effectiveness of the proposed　methodology for load frequency control by several simulation
results.

H∞ Filter-based SLAM with the Observation on an a priori Known Landmark

Yoshihiro OKAWA and Toru NAMERIKAWA

SICE Journal of Control, Measurement, and System Integration (The Society of Instrument and Control Engineers) 6 ( 5 ) 360 - 367 2013.10

Research paper (scientific journal), Joint Work, Accepted

The authors consider the simultaneous localization and mapping (SLAM) problem with an H∞ filter and with
an observation of a landmark that is known a priori. With this observation, the system satisfies observability, and the estimated error is suppressed and the determinant of its covariance matrix becomes small compared with that of the original H∞ filter. As a result, our proposed method avoids finite escape time, the divergence of the error covariance matrix that occurs in the estimation when using the original H∞ filter. We prove the convergence of the error covariance matrix. In addition, with simulations and experimental results, we confirm that finite escape time is avoided, that the derived theorems for the convergence are correct, and that we can accurately estimate the state of the robot and the environment.

Optimal Pricing Algorithm in the Electricity Market with Battery and Accumulator and Demand-Supply Balancing

宮野　雄基, 滑川徹

電気学会論文誌Ｃ (電気学会) 133 ( 10 ) 1855 - 1863 2013.10

Research paper (scientific journal), Joint Work, Accepted

This paper considers Day-Ahead Market with battery and accumulator to level power generation. First,we model consumer with battery, generator with battery and accumulator to maximize their own profit.
Then, the optimal pricing algorithm based on dual decomposition and Steepest Descent Method and proof
the stability of the algorithm is proposed. Finally, we show the effectiveness of the algorithm with some
numerical simulations which indicate that the proposed algorithm achieves the demand-supply balancing.

Control of Formation Configuration Using Leader-Follower Structure

Y. KURIKI, T. NAMERIKAWA

Journal of System Design and Dynamics (JSME) 7 ( 3 ) 254 - 264 2013.09

Research paper (scientific journal), Joint Work, Accepted, ISSN 1881-3046

In this paper, we study cooperative control problems with trajectory tracking and reconfigurable formation for a multi-vehicle system expressed as a first-order system.
Specifically, we describe a problem that cooperatively controlled vehicles keep geometric configuration among the multiple vehicles while the vehicles are moving in formation. In other words, each of the vehicles must change its position individually to keep the geometric configuration while the vehicle is moved by a cooperative control. In order to achieve this objective, we basically extend our previous result which was a control algorithm to surround a moving target by a group of vehicles cooperatively.
The algorithm was based on a consensus algorithm which was cooperative control.
In addition, we apply a leader-follower structure to our cooperative algorithm so that a leader can individually provide each of the followers with commands. Finally, the
proposed approach is validated by some simulations.

Cooperative Capturing for Multi-Agent System with Reaction Force from Target Object

Yoshihiro Tachibana, Toru Namerikawa

2013 PROCEEDINGS OF SICE ANNUAL CONFERENCE (SICE) (IEEE) 1231 - 1236 2013.09

Research paper (international conference proceedings), Joint Work, Last author, Accepted, ISSN 1550-0322

This paper proposes a cooperative control of multi-agent system to capture target object. When the agents capture the target object, they may be subjected to reaction force from it. Therefore, we have to consider the physical contact between the agent and target object. First, we introduce the second order model to consider reaction force from target object. The network topology among agents is time-varying and connected, and information of target object is allowed to be available to at least one agent. Second, we show the proposed control law guarantees the agents capture the target object. The control law consists of graph theory and consensus algorithm, and we analyze the convergence property. Finally, simulation results show the effectiveness of the proposed control law.

Simultaneous Localization and Mapping Problem via the H-infinity Filter with a Known Landmark

Yoshihiro Okawa, Toru Namerikawa

2013 PROCEEDINGS OF SICE ANNUAL CONFERENCE (SICE) (IEEE) 1939 - 1944 2013.09

Research paper (international conference proceedings), Joint Work, Accepted, ISSN 1550-0322

This paper deals with the simultaneous localization and mapping (SLAM) problem via the H-infinity filter with a known landmark. By adding the observation of a known landmark to those of unknown landmarks, the linearized SLAM model satisfies its observability, and its estimation accuracy is improved. To prove the improvement theoretically, this paper shows that the determinant of the estimated error covariance matrix with the observation of a known landmark becomes small compared with that of the conventional H-infinity filter. The convergence of the error covariance matrix is also proven in this paper. With simulations and experimental results, we confirm that the derived theorems for the convergence are correct and that we can accurately estimate the state of the robot and the environment.

Multi-Robot SLAM for Large Scale Map Building using Relative Information of Local Maps

Takaaki Kojima, Yoshihiro Okawa, Toru Namerikawa

2013 PROCEEDINGS OF SICE ANNUAL CONFERENCE (SICE) (IEEE) 164 - 169 2013.09

Research paper (international conference proceedings), Joint Work, Last author, Accepted, ISSN 1550-0322

This paper deals with Multi-Robot SLAM for large scale map building. Specifically, each robot estimates a local map using EKF, and we merge these local maps into a global map. In this paper, we provide a new RLS based algorithm for map merging. First, we transform local maps into relative information which is considered as measurements for the global map. Then, we update the state estimate by RLS considering the weighting of measurements, which is determined by error propagation from the EKF SLAM. We prove the convergence of the error covariance matrix in this algorithm. In experimental results, we confirm the validity of the proposed algorithm and correctness of derived theorems for the convergence.

Cyber Attack Detection and Faults Diagnosis in Power Networks by Using State Fault Diagnosis Matrix

Yuki Fujita, Toru Namerikawa, Kenko Uchida

2013 EUROPEAN CONTROL CONFERENCE (ECC) (IEEE) 398 - 403 2013.07

Research paper (international conference proceedings), Joint Work, Accepted

This paper discusses cyber attacks and faults diagnosis method for networked electrical power systems. In this paper, a power system is divided into some areas, and then, some parameters are estimated by Kalman filter in each area. Then we propose a diagnosis method by using called state and output fault diagnosis matrices which are composed of the estimated values, output matrix and so on. These diagnosis matrices can immediately judge which nodes of which area is attacked. Finally, some simulation results are shown to validate the proposed approach.

Distributed Control for Load Frequency of Power Networks based on Iterative Gradient Methods with Line Search

Taichiro Kato , Yu Haraikawa , Toru Namerikawa

計測自動制御学会論文集 (The Society of Instrument and Control Engineers) 49 ( 2 ) 222 - 228 2013.02

Research paper (scientific journal), Joint Work, Accepted

本論文では分散型電源を導入した電力ネットワークに対して, 直線探索付き反復勾配法に基づく系統周波数制御を提案する.
まず, ネットワーク構造を有する大規模システムを各サブシステムの結合系として状態遷移式で表現し, 状態と制御入力を考慮した評価関数を最小化する制御問題を定式化する.
そしてこの制御問題に対して最適制御を計算する際に, 直線探索を付加した反復勾配法に基づく系統周波数制御を提案する. また, エネルギー/情報結合構造の変化に対してもフレキシブルに適応する事が可能である. 直線探索を行う際のステップ幅はArmijoとWolfe の規準の両方を満足しているため, 収束性を保証する事ができる.
最後に分散型電源を導入した電力ネットワークの負荷周波数制御(Lに対して提案制御則を適用する. そして提案制御則を用いることで, 従来制御則に対し評価関数の低減化や周波数変動の抑制など制御性能の向上が達成されていることをシミュレーションで示す.

Covariance Bounds Analysis during Intermittent Measurement for EKF-based SLAM

A.Hamzah,T.NAMERIKAWA

International Journal of Integrated Engineering 4 ( 3 ) 19 - 25 2012.12

Research paper (scientific journal), Joint Work

This paper deals with Extended Kalman Filter(EKF)-based　SLAM estimation considering intermittent measurement. The study proposes a method to ensure that a designer is able to secure the state covariance or system uncertainties even though the mobile robot sometimes losses its measurement data during its observations. EKF which is based on Bayesian, is chosen in this work for estimation purposes in determining mobile robot position and the environment conditions. In addition, as most of estimation techniques uses Bayesian method, our propose results is expected to provide a general estimation guidelines especially on the filter statistical behavior. The analysis started from the review of theoretical studies of EKF including the expected condition occurred when mobile robot do not received information from its sensors. Simulation results have consistently supports our theoretical analysis which determines that a designer can determine the state error covariance explicitly whenever measurement data is not available.

Improving Tracking Performance of Passivity Based PID-Type Teleoperation Systems with Communication Delay

Y. Kawai, T. Namerikawa

SICE Journal of Control, Measurement, and System Integration (The Society of Instrument and Control Engineers) 5 ( 6 ) 335 - 341 2012.10

Research paper (scientific journal), Joint Work, Accepted

The goal of this paper is to improve tracking performance of a bilateral teleoperation system with communication
time delay. The proposed method is a passivity-based PID-type controller. First, using feedback passivation control,
we make the master and slave robots passive with respect to the new output including position and velocity signals. Secondly,
we design the PI controller for the new output. In the proposed method, position coordination is achieved even with
the viscous friction error situation. The stability of the proposed PID teleoperation system and tracking performance are
shown via passivity based stability analysis. Finally, several experimental results show the effectiveness of the proposed
control methodology for teleoperation systems.
Key Words : teleoperation system, communication delay, PID-type controller, tracking performance.

故障評価行列と観測値欠落補償に基づく耐故障性を考慮したセンサネットワークの構成

小杉和也, 滑川徹

計測自動制御学会論文集 (The Society of Instrument and Control Engineers) 48 ( 10 ) 649 - 656 2012.10

Research paper (scientific journal), Joint Work, Accepted

本稿ではまずセンサの観測値にバイアスがかかるような故障に関して観測誤差共分散を用いた故障検出を行う．そしてこの結果と文献の観測値欠落を考慮したを組み合わせて故障の発生に対して状態推定精度を高感度化することにより故障信号の付加により信頼性の低下した観測値の状態推定結果への反映を抑制した推定手法を提案する．次に現時刻の観測データを含む状態推定値の欠落に対し観測値の推定値を用いた補償を行うことで推定精度を向上させる手法を提案し最後にこれらの提案制御則の有効性をシミュレーションにより検証する．次章以降ではまずはじめに問題設定としてセンサノードと制御対象であるプラントのモデル本稿で扱う種類の耐故障問題に関しての定義について述べる．次に設定した評価関数の特性について述べこの性質を利用した近傍比較戦略を提示する．最後に数値シミュレーションと制御実験により提案手法の有効性を検証した結果を示す．

逃避時間回避を考慮したH∞フィルタによる移動ロボットの自己位置推定と環境認識

大川佳寛, 滑川徹

計測自動制御学会論文集 (The Society of Instrument and Control Engineers) 48 ( 10 ) 674 - 682 2012.10

Research paper (scientific journal), Joint Work, Accepted

This paper deals with the Simultaneous Localization and Mapping problem via H1 filter considering finite
escape time. The estimation via H1 filter occurs finite escape time depending on the value of the parameter γ
and then the estimation fails or deteriorates. In order to avoid it, we propose a novel algorithm of the update
equation of the filter gain. The convergence of the error covariance matrices are proven. In simulation and
experimental results, the avoidance of the finite escape time and the correctness of derived theorems for the
convergence are confirmed and then we can show robot’s state and environment information can be estimated.

H∞ Filter－Based Short－term Electric Load Prediction considering Characteristics of Load Curve

T. Namerikawa,　Y. Hosoda

電気学会論文誌C (電気学会) 132 ( 9 ) 1446 - 1453 2012.09

Research paper (scientific journal), Joint Work, Accepted, ISSN 0385-4221

This paper deals with H∞ filter－based short－term electric load prediction considering characteristics of load curve. We propose a predictive method to forecast a future electric load demand for 36 hours from 0 PM,and then evaluate the peak and bottom of load curves in the next day. We propose a load model, estimates
unknown parameters of model via H∞ filter using the separated data from holiday and weekday, a same pattern of the previous data have been chosen and assigned to parameters for the model. The simulation
results show the effectiveness of the proposed prediction methodology.

磁気支持応用技術と環境調和

森下明平, 滑川徹

電気学会技術報告D (電気学会) ( 1247 ) 1 - 54,裏表紙 2012.04

Research paper (scientific journal), Joint Work, ISSN 0919-9195

Distributed and Predictive Control for Smart Grids

Toru Namerikawa

Journal of The Society of Instrument and Control Engineers (The Society of Instrument and Control Engineers) 51 ( 1 ) 62-68 2012.01

Research paper (scientific journal), Single Work

太陽光発電などの分散型電源が大量に電力系統に連係されようとしている。分散型再生可能エネルギーを本格的に導入するためには,大規模複雑化していくシステムをどのような形態で接続すべきかという電力ネットワークトポロジーの視点から,電力システムの安定性,最適性,経済性を再考する必要がある。本稿では,太陽光発電などの直接制御不可能な再生可能エネルギーと,火力,原子力などの多種多様な発電(供給)システムを有し,消費(需要)システムとしては工場,ビル,一般家庭,電気自動車などが結合している大規模複雑系のスマートグリッドを対象とした。情報結合構造を有するシステムとして表現した分散電力システムに対して,反復勾配法を用いた分散制御を適用した結果と,線形確率システムに予測制御を適用した結果について報告し,分散制御/予測制御のアプローチについて,世界の研究の潮流と著者らの研究成果の一端を紹介した。

H∞ filter-based short-term electric load prediction considering characteristics of load curve

Namerikawa Toru, Hosoda Yasuhiko

IEEJ Transactions on Electronics, Information and Systems 132 ( 9 ) 2012

Research paper (scientific journal), Accepted, ISSN 0385-4221

This paper deals with H∞ filter-based short-term electric load prediction considering characteristics of load curve. We propose a predictive method to forecast a future electric load demand for 36 hours from 0 PM, and then evaluate the peak and bottom of load curves in the next day. We propose a load model, estimates unknown parameters of model via H∞ filter using the separated data from holiday and weekday, a same pattern of the previous data have been chosen and assigned to parameters for the model. The simulation results show the effectiveness of the proposed prediction methodology. © 2012 The Institute of Electrical Engineers of Japan.

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Decentralized Control of Smart Grid by using Overlapping Information

Tomoharu Suehiro, Toru Namerikawa

2012 PROCEEDINGS OF SICE ANNUAL CONFERENCE (SICE) (SOC INSTRUMENT CONTROL ENGINEERS JAPAN) 125 - 130 2012

Accepted

This paper deals with a decentralized control of smart grid by using overlapping information for load frequency of power networks introducing distributed power generations. The control objective is to minimize the cost function of load frequency control problem. We expand the state space of the system of power networks and propose a decentralized state feedback control of subsystems for the expanded system. Then we contract the decentralized feedback law to match the original system. Finally, we show the effectiveness of the load frequency control by using the proposed decentralized control method through the simulation result of decentralized large scale power network systems.

Short-term Photovoltaic Prediction by using H-infinity Filtering and Clustering

Yasuhiko Hosoda, Toru Namerikawa

2012 PROCEEDINGS OF SICE ANNUAL CONFERENCE (SICE) (SOC INSTRUMENT CONTROL ENGINEERS JAPAN) 119 - 124 2012

Accepted

This paper deals with prediction algorithm applying for photovoltaic (PV) systems in smart grid. This prediction is aim to predict the amount of the next day of generation using the previous data and the weather forecast which get from Japan Meteorological Agency. The procedure of prediction consists of two steps, the data processing and the unknown parameters estimation. In the data processing, our proposed method considers the characteristics of PV generation using cluster ensemble. We propose the cluster ensemble based on k-means to choose the groups with a correlation with previous data. In the unknown parameters estimation, we provide the regression model for PV generation and the unknown parameters are estimated via H-infinity filtering. The effectiveness of the proposed prediction method is demonstrated through numerical simulations.

Robot Localization and Mapping problem with Bounded Noise Uncertainties

Hamzah Ahmad, Toru Namerikawa

2012 IEEE SYMPOSIUM ON INDUSTRIAL ELECTRONICS AND APPLICATIONS (ISIEA 2012) (IEEE) 2012

Accepted

This paper deals with H-infinity Filter based SLAM which is also known as minimax filter to estimate robot and landmarks location whose able to stand for non-gaussian noise characteristics. Based on our findings, by selecting appropriate gamma and initial state covariance matrix in H-infinity Filter, the estimation results can show better performance in comparison to the Kalman Filter approach. From the analysis of convergence properties of H-infinity Filter, it is found that the filter is capable to provide a reliable estimation. Besides, from the simulation results, H-infinity Filter produces better outcome than the Kalman Filter in the nonlinear case estimation. These condition subsequently provides alternative estimation techniques with the capability to ensure and improve estimation in the robotic mapping problem especially in SLAM.

Fault-tolerant Sensor Network based on Fault Evaluation Matrix and Compensation for Intermittent Observation

Kazuya Kosugi, Shinichiro Tokumoto, Toru Namerikawa

2012 IEEE 51ST ANNUAL CONFERENCE ON DECISION AND CONTROL (CDC) (IEEE) 1834 - 1839 2012

Accepted, ISSN 0743-1546

This paper deals with a fault-tolerant sensor network configuration problem for a target navigation.
A sensor network system consists of many sensor nodes and its network connections. Each sensor node can exchange information by wireless communication. A disadvantage of this system's property is that if there is an inaccurate information from a faulty sensor, this information has possibilities to be diffused to other sensors. Therefore, it is important to reduce effects of the inaccurate information by detecting a faulty sensor as possible as we can. And moreover, in feedback control system for navigation, we have to consider a lack of control inputs which happens depending on each sensor's intermittent observation. We propose two estimation methods for constructing a fault tolerant system. Specifically, we propose a fault-evaluation matrix for the fault detection, and we define a novel switching rule for shutting off inaccurate measurement data. Then we also propose a compensation algorithm for the problem of intermittent observation by using an estimated observation value.

On Predictive Control for Systems with Information Structured Constraints

Toru Namerikawa , Takeshi Hatanaka and Masayuki Fujita

SICE Journal of Control, Measurement, and System Integration (The Society of Instrument and Control Engineers) 4 ( 6 ) 452 - 459 2011.11

Research paper (scientific journal), Joint Work, Accepted, ISSN 1882-4889

In this paper, we investigate a predictive control problem with information structured constraints motivated
by control of micro grid. A system with information structures is defined as a system in which each subsystem collects
spatio-temporally different information. For the system, we consider a predictive control law and the finite time constrained
optimization problem to be solved online is reduced to a deterministic convex programming problem. Then, we
reduce a control problem for a simple micro grid system to the framework and the effectiveness of the proposed control
and estimation law is demonstrated through a numerical simulation.

10911940390420110430155646PDF1.pdf

A Scheduling Strategy based on Neighbor Search for Heterogeneous Sensor Networks

Hamzah Ahmad and Toru Namerikawa

Trans. of the Society of Instrument and Control Engineers (The Society of Instrument and Control Engineers) 47 ( 8 ) 329-336 - 336 2011.08

Research paper (scientific journal), Joint Work

This paper deals with a sensor scheduling problem which considers state dependent noise and processing delay.
A networked sensor system usually consists of a large number of sensors, which can be constructed with some
different types of sensors. We propose a sensor scheduling algorithm based on the neighbor search algorithm
nearby nodes for discrete time heterogeneous systems by minimization problem of assessment function. Finally
experimental results show effectiveness of the proposed method.

10911940391720110430163312PDF1.pdf

Intermittent Measurement in Robotic Localization and Mapping with FIM Statistical Bounds

Hamzah Ahmad and Toru Namerikawa

IEEJ Transactions on Electronics, Information and Systems (The Institute of Electrical Engineering of Japan) 131 ( 6 ) 2011.06

Research paper (scientific journal), Joint Work

10911940391720110430163312PDF1.pdf

Multiple Cooperative Bilateral Teleoperation with Time-Varying Delay

Nam Duc Do, Yusuke Yamashina, and Toru Namerikawa

SICE Journal of Control, Measurement, and System Integration (The Society of Instrument and Control Engineers) 4 ( 2 ) 89-96 - 96 2011.05

Research paper (scientific journal), Single Work, Accepted, ISSN 1882-4889

10911940390420110430155646PDF1.pdf

Robotic Mapping and Localization Considering Unknown Noise Statistics

Hamzah Ahmad and Toru Namerikawa

Journal of System Design and Dynamics (The Japan Society of Mechanical Engineers) 5 ( 1 ) 70-82 - 82 2011.01

Research paper (scientific journal), Single Work, Accepted, ISSN 1881-3046

This paper presents an analysis of H∞ Filter(HF) for Robotics Mapping and Localization with unknown noise statistics. HF which is also known as the minimax filter is proposed in this paper to estimate the robot and landmarks location while robot moves through an unknown environment. Some of the conditions are proposed to ensure that the state covariance in HF is converging to a steady state value. Furthermore, the analysis of HF convergence for a robot observing landmarks are presented to examine its behavior through the observations. From the experimental results, HF gives a sufficient estimation about the environment. Subsequently, such a result can provide other available estimation methods with the capability to ensure and improved estimation in robotic mapping and localization problem.

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Intermittent measurement in robotic localization and mapping with FIM statistical bounds

Ahmad Hamzah, Namerikawa Toru

IEEJ Transactions on Electronics, Information and Systems 131 ( 6 ) 1223 - 1232 2011

Research paper (scientific journal), Joint Work, Accepted, ISSN 0385-4221

The focus of study is to review the FIM statistical behavior in each EKF update and determine its potential in providing sufficient information about Robotic Localization and Mapping problem with intermittent measurements. We provide theoretical analysis and prove that the FIM can successfully describe both upper and lower bounds for the state covariance matrix whenever measurement data is not arrived during robot observations. This approach can give a better picture on how information are processed in EKF when measurement data is partially unavailable. Some simulation evaluations are also included to verify our results and consistently demonstrate the expected outcome. © 2011 The Institute of Electrical Engineers of Japan.

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Cooperative Control Based on Force-Reflection with Four-channel Teleoperation System

Nam Duc Do, Toru Namerikawa

2011 50TH IEEE CONFERENCE ON DECISION AND CONTROL AND EUROPEAN CONTROL CONFERENCE (CDC-ECC) (IEEE) 4879 - 4884 2011

Accepted

This paper focuses on a new Force-Reflection (FR) algorithm based on input-to-state stability (ISS) small gain theorem in cooperative work of Single Master-Multiple Slave (SMMS) teleoperation system with time varying communication delay. In this work, we propose a new position tracking control for object grasping and a new FR algorithm based on a PD control to transfer the positions, velocities and force information between both sides of teleoperation. The goals of these methods are to achieve the secure grasping by multiple slave robots and improve the tracking performance of the cooperation SMMS teleoperation system. To analyze stability of the system, the ISS small gain approach is used to show the overall force-reflecting teleoperation to be input-to-state stable. Several experimental results show the effectiveness of our proposed method.

Distributed Load Frequency Control of Electrical Power Networks via Iterative Gradient Methods

Toru Namerikawa, Taichiro Kato

2011 50TH IEEE CONFERENCE ON DECISION AND CONTROL AND EUROPEAN CONTROL CONFERENCE (CDC-ECC) (IEEE) 7723 - 7728 2011

Accepted

This paper discusses a distributed control for load frequency of electrical power networks based on iterative gradient methods. The control objective is to minimize the quadratic cost function of load frequency control problem, and we apply the distributed control methodology by using iterative gradient methods to complicated large scale electrical power networks. Iterative gradient methods have good flexibility and they are effective for complicated and time-varying distributed power networks. Several numerical simulation results of distributed power network systems including distributed generations, batteries, and renewable energies in order to show the effectiveness of the load frequency control compared with conventional decentralized control and centralized control.

Predictive Control and Estimation for Systems with Information Structured Constraints

Toru Namerikawa, Takeshi Hatanaka, Masayuki Fujita

2011 11TH INTERNATIONAL CONFERENCE ON CONTROL, AUTOMATION AND SYSTEMS (ICCAS) (IEEE) Vol. 4 ( No. 6 ) 538 - 543 2011

Accepted

This paper deals with a predictive control and estimation problem with information structured constraints in a constrained finite-time optimal control framework. A large-scale system with information structures is defined as a system in which each subsystem collects spatio-temporally different information, and in general it is necessary to collect and process information in a distributed fashion. We propose a novel predictive control scheme and an estimation law with local information that each distributed subsystem obtains. The effectiveness of the proposed control and estimation law is evaluated through numerical simulations of a simplified micro grid.

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Control Theory for Energy and Environment Problems

Toru Namerikawa

2010 IEEE Multi-conference on Systems and Control (The Institute of Electrical and Electronics Engineers (IEEE)) 2010.09

Four-channel force-reflecting teleoperation with impedance control

Do Nam Duc, Namerikawa Toru

International Journal of Advanced Mechatronic Systems 2 ( 5-6 ) 318 - 329 2010

Research paper (scientific journal), Joint Work, ISSN 1756-8412

This paper focuses on a bilateral control of teleoperation system with four-channel force-reflection (FR) algorithm and communication time delays. In this method, we propose a new system input of impedance control that relates to FR scheme of teleoperation. The goal of this paper is to improve the tracking performance and transparency, the control-based force-reflecting teleoperation uses a force feed forward channel in comparison with a conventional method to transfer the position, velocity and human force information from the master side to the slave side. Hence, we receive a four-channel architecture of the teleoperation system. Using variable damping values, the contact stability is achieved at the time when the slave robot contacts with the environment. To analyse stability of the system, one method based on Lyapunov technique is concerned, the input-to-state stability (ISS) small gain approach is used to show the overall force-reflecting teleoperation to be input-to-state stable. Several experimental results show the effectiveness of our proposed algorithm. © 2010 Inderscience Enterprises Ltd.

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Bilateral Teleoperation of Multiple Cooperative Robots with Time-Varying Delay

Nam Duc Do, Yusuke Yamashina, Toru Namerikawa

2010 IEEE INTERNATIONAL CONFERENCE ON CONTROL APPLICATIONS (IEEE) 2053 - 2058 2010

Accepted, ISSN 1085-1992

This paper deals with a passive-decomposition based control of bilateral teleoperation between a single master robot and multiple cooperative slave robots under time varying delay in the communication line. At first, we decompose the dynamics of multiple slave robots into two decoupled dynamics: the Shape-System describing dynamics of the cooperative works, and the Locked-System representing overall behavior of the multiple slave robots. Second, we propose a PD control method for bilateral teleoperation to guarantee the asymptotical stability of the system for time varying delay. Finally, experimental results show the effectiveness of our proposed teleoperation.

Sensor Network Scheduling Algorithm Considering Estimation Error Variance and Communication Energy

Takashi Takeda, Toru Namerikawa

2010 IEEE INTERNATIONAL CONFERENCE ON CONTROL APPLICATIONS (IEEE) 434 - 439 2010

Accepted, ISSN 1085-1992

This paper deals with a sensor scheduling algrithm considering estimation error variance and communication energy in sensor networked feedback systems. We propose a novel decentralized estimation algorithm with unknown inputs in each sensor node. Most existing works deal with the sensor network systems as sensing systems and it is difficult to apply them to the real physical feedback control systems Then some local estimates are merged and the merged estimates can be optimized in the proposed method and the estimation error covariance has a unique positive definite solution under some assumptions. Next, we propose a novel sensor scheduling algorithm in which each sensor node transmits information. A sensor node uses energy by communication between other sensor node or the plant. The proposed algorithm achieves a sub-optimal network topology with minimum energy and a desired variance. Experimental results show an effectiveness of the proposed method.

Robot Localization and Mapping Problem with Unknown Noise Characteristics

Hamzah Ahmad, Toru Namerikawa

2010 IEEE INTERNATIONAL CONFERENCE ON CONTROL APPLICATIONS (IEEE) 1275 - 1280 2010

Accepted, ISSN 1085-1992

In this paper, we examine the H-infinity Filter-based SLAM especially about its convergence properties. In contrast to Kalman Filter approach that considers zero mean gaussian noise, H-infinity Filter is more robust and may provide sufficient solutions for SLAM in an environment with unknown statistical behavior. Due to this advantage, H-infinity Filter is proposed in this paper, to efficiently estimate the robot and landmarks location under worst case situations. H-infinity Filter requires the designer to appropriately choose the noise's covariance with respect to gamma to obtain a desired outcome. We show some of the conditions to be satisfy in order to achieve better estimation results than Kalman Filter. From the experimental results, H-infinity Filter performs better than Kalman Filter for a case of bigger robot initial uncertainties. Subsequently, this proved that H-infinity Filter can provide another available estimation method for especially in SLAM.

Bilateral Teleoperation of Wheeled Mobile Robot with Time Delay using Virtual Image Robot.

Yasunori Kawai, Toru Namerikawa, Masayuki Fujita

Proceedings of the IEEE International Conference on Control Applications, CCA 2010, Yokohama, Japan, September 8-10, 2010 (IEEE) 77 - 82 2010

Accepted

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Network-Topology Independent Cooperative Target-enclosing Behavior by Swarms of Vehicles

KAWAKAMI Hiroki and Namerikawa Toru

Transactions of the Society of Instrument and Control Engineers (The Society of Instrument and Control Engineers) 45 ( 12 ) 688-695 2009.12

Research paper (conference, symposium, etc.), Joint Work, Accepted

This paper deals with cooperative target-enclosing problem for swarms of vehicles with dynamic network-topology.
First, we introduce a dynamic network topology that depends on relative distance between the vehicles.
Secondly, we propose the target-enclosing strategy based on consensus seeking with dynamic network-topology.
In proposed strategy, at least one vehicle has to acquire the states of target-object. Furthermore, we prove that
convergence speed of each vehicle is independent of network-topology. To analyze the convergence of target-enclosing
behavior under dynamic network topology, algebraic graph theory and matrix theory are utilized.
Finally, numerical simulation results and experimental results are provided that demonstrate the effectiveness of
the proposed method.

Consensus Problem for Multi-Agent Systems and Cooperative Capturing Behavior

Toru Namerikawa

Systems, Control and Information (The Institute of Systems, Control and Information Engineers) 53 ( 10 ) 443-448 - 448 2009.10

Research paper (scientific journal), Single Work

複数の対象が協調して作業を行うマルチエージェントに関しては，これまでにも議論されているが，近年グラフ理論とシステム制御理論の融合からのアプローチが注目を集めています．
本稿では，マルチエージェントの合意問題に対し，意制御則の設計法と情報結合構造について解説し，更にビークルフォーメーションとビークル群による協調取り囲み行動などの応用について紹介する．

Delay-Independent Stabilization of Teleoperation Systems with Time-Varying Delay

Hiroyuki FUJITAand Toru Namerikawa

SICE Journal of Control, Measurement, and System Integration (The Society of Instrument and Control Engineers) 2 ( 3 ) 177–183 - 183 2009.05

Research paper (conference, symposium, etc.), Joint Work, Accepted, ISSN 1882-4889

This paper deals with stability of nonlinear teleoperation systems with time-varying communication delays.
The proposed method is the use of passivity-based controllers with time-varying gains which depend on the rate of
change of time-varying delay. In our proposed method, the stability condition is independent of the magnitude of the
communication delay and the damping of the system. The delay-independent stability is shown via Lyapunov stability
methods. Several experimental results show the effectiveness of our proposed teleoperation structure.

Robust stabilization of running self-sustaining two-wheeled vehicle with varying speed and mass variations

Satoh Hiroshi, Namerikawa Toru

Nihon Kikai Gakkai Ronbunshu, C Hen/Transactions of the Japan Society of Mechanical Engineers, Part C (Japan Society of Mechanical Engineers) 75 ( 752 ) 882 - 889 2009.04

Research paper (scientific journal), Accepted, ISSN 0387-5024

This paper deals with robust stabilization of running self-sustaining two-wheeled vehicle with varying running speed and mass variations. Recently, there have been a lot of research results about stabilization of two-wheeled vehicle. These researches have achieved the stable running only by the steering control. However, an actual two-wheeled vehicle is stabilized by not only the steering control, but the control of a vehicle's center of gravity. We have proposed the stabilization control method of two-wheeled vehicle in the state of stillness, and have shown the effectiveness of proposed approach. In this research, we construct the control system for the running stabilization of two-wheeled vehicle. H^∞ control problem is used to design the controller to achieve running stability even if the running speed and the mass of two-wheeled vehicle would change. The experimental results show effectiveness of proposed approach for robustness.

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速度と質量の変動に対する自立走行二輪車のロバスト安定化

佐藤拓史, 滑川徹

日本機械学会論文集, C編 (日本機械学会) 75 ( 752 ) 882-889 2009.04

Research paper (scientific journal), Joint Work

本研究では静止状態において安定化させる目的で開発した自立走行二輪車に対して，走行安定化を目的とした制御系を構成する．走行を考慮したモデリングを行い，導出した数学モデルが静止時の場合の拡張となっていることを確認した．二輪車の走行速度と質量の変動を考慮した制御系をH∞制御系設計問題を用いて設計し，実際に走行速度を変動した場合と，付加質量を搭載した場合においても安定化が実現できた．これにより，速度変動や質量変動に対して提案するロバスト姿勢制御系の有効性が確認された．

Bilateral Control of Nonlinear Teleoperation with Time Varying Delays

Hisanosuke Kawada and Toru Namerikawa

Transactions of the Society of Instrument and Control Engineers (Society of Instrument and Control Engineers) 45 ( 1 ) 18-26 2009.01

Research paper (conference, symposium, etc.), Joint Work, Accepted

This paper addresses the bilateral control of nonlinear teleoperation with time varying delays. The proposed
control strategies are two types of simple PD-type controllers which directly connect the master and slave robots by position and velocity signals over the delayed communication. For the velocity control, the first controller has a time varying D-gains which depend on the rate of change of delays and the second one has a constant
D-gains which are designed under stability condition. Moreover the both controllers have explicit position feedback/feedforward control. Using Lyapunov-Krasovskii function, the delay-depend stability of the origin is shown
for the range of the gains. Furthermore the proposed framework enforces master-slave position coordination
and static force reflection. Several simulation and experimental results show the effectiveness of our proposed
framework.

10911937617020100411175258PDF1.pdf

GIMC structure based Anti-Windup control considering L2 performance

Nakashima Yusuke, Namerikawa Toru

Proceedings of the IEEE International Conference on Control Applications (IEEE = Institute of Electrical and Electronics Engineers) ( 5281047 ) 956 - 961 2009.01

ISSN 1085-1992

This paper deals with GIMC (Generalized Internal Model Control) structure based Anti-Windup (AW) control system design. First, we setup a L2 performance criterion based on GIMC structure for Anti-Windup control problems. The design problem is formulated as an optimization problem with a parameter Q. Then we calculate the optimization problem and find an optimal Q. Finally, the effectiveness of proposed method is shown by experimental results for a magnetic suspension system. © 2009 IEEE.

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2008 American Control Conference -ACC 2008-

NAMERIKAWA Toru

システム/制御/情報 53 ( 1 ) 48 2009.01

Bilateral Control with Constant Feedback Gains for Teleoperation with Time Varying Delay

Toru Namerikawa

PROCEEDINGS OF THE 48TH IEEE CONFERENCE ON DECISION AND CONTROL, 2009 HELD JOINTLY WITH THE 2009 28TH CHINESE CONTROL CONFERENCE (CDC/CCC 2009) (IEEE) 7527 - 7532 2009

Accepted, ISSN 0743-1546

This paper describes a bilateral control of nonlinear teleoperation with time varying communication delay.
The proposed method are simple PD-type controllers which are independent of the rate of time delay change and depend on the upper bound of round-trip delay. The proposed control strategy is independent of parameter uncertainties of the model of the robots and the operator and remote environment. The delay-dependent stability of the origin is shown via Lyapunov stability theorem. Furthermore the proposed strategy also achieves master-slave position coordination and bilateral static force reflection.
Several experimental results with wireless communication and the Internet show the effectiveness of our proposed strategy.

Stability and Tracking Properties in Predictive Control with Adaptation for Bilateral Teleoperation

Kouei Yoshida, Toru Namerikawa

2009 AMERICAN CONTROL CONFERENCE, VOLS 1-9 (IEEE) 1323 - 1328 2009

Accepted, ISSN 0743-1619

This paper deals with an environment estimation based predictive control for teleoperation with communication time delay. In this predictive control framework, the delayed position tracking and non-delayed force reflection are attempted. The goal of this paper is to propose a new control method which guarantees the stability, the convergence of position tracking error to zero and the small force tracking error theoretically. Proposed control structure is the 3ch architecture with environment estimation based force prediction. In this proposed method, the master controller implements force control with environmental force prediction while the slave controller implements position and force control. The theoretical analysis shows the stability, the convergence of position error to zero and the small force tracking error. Experimental results show the effectiveness of the proposed method.

通信遅延を有する異構造バイラテラルテレオペレーションの同調制御

河田久之輔, 吉田航瑛, 滑川徹

計測自動制御学会論文集 (計測自動制御学会) 44 ( 10 ) 802-808 - 808 2008.10

Research paper (scientific journal), Joint Work, ISSN 0453-4654

本稿では通信遅延を有する異構造テレオペレーションに対して安定性を保証した制御手法を提案する．まずマスタ及びスレーブロボットに対してフィードバック受動化を行い，次に通信遅延とスケーリング要素を有する同調制御則を提案する．リアプノフの安定法を用いることで, 提案テレオペレーションの位置誤差が遅延とスケーリング要素に対して独立に漸近安定となることを示す. 最後に構造とスケールの異なる2台の2自由度アームを用いた実験により提案手法の有効性を示す.

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GIMC 構造による故障検出とその磁気浮上システムへの応用

中曽裕次郎, 滑川徹

システム制御情報学会論文集 (システム制御情報学会) 21 ( 9 ) 277-284 2008.09

Research paper (scientific journal), Joint Work

本稿ではGIMC 構造によって得られる推定誤差信号によるオンライン故障検出法の提案と, それを用いた耐故障制御系の構築をおこなう. 故障検出フィルタに関して外乱による影響の最小化問題を新たに定式化し, それに対する最適な故障検出フィルタを導出することで, 外乱と故障の影響を区別する. また磁気浮上系に対し外乱および故障信号を含めたモデルを導出し, 最適故障検出フィルタの設計を行う. 最後に検証実験を行い, 設計した故障検出フィルタの有効性を確認する.

マルチエージェントシステムの合意問題とそのフォーメーション制御への応用

吉岡愛, 滑川徹

計測自動制御学会論文集 (計測自動制御学会) 44 ( 8 ) 663-669 2008.08

Research paper (scientific journal), Joint Work

本稿では線形システムとして表現される複数の同一のダイナミクスをもつエージェントの合意問題に対し，新規の合意制御則の設計法を提案する．この設計法はLyapunovの安定定理に基づき，従来法に比べ設計の見通しが良い．つぎに状態推定を含む出力合意問題に対して，情報交換を行うエージェントの数に依存しない状態推定方法を用いた合意制御則を提案し，更に積分器を加えた合意制御則を提案する．最後に提案制御則をフォーメーション制御に応用し，制御実験により提案法の有効性を検証する．

Observer-based Consensus Control Strategy for Multi-Agent System with Communication Time Delay

Chika Yoshioka, Toru Namerikawa

2008 IEEE INTERNATIONAL CONFERENCE ON CONTROL APPLICATIONS, VOLS 1 AND 2 (IEEE) 859 - 864 2008

Accepted, ISSN 1085-1992

補償器の初期状態を考慮したＨ∞ＤＩＡ制御と磁気軸受による過渡特性の検証

瀬戸洋紀, 滑川徹

日本AEM学会誌 (日本AEM学会) 15 ( 4 ) 422-428 - 428 2007.12

Research paper (scientific journal), Joint Work, ISSN 0919-4452

本論文では補償器の初期状態を考慮したH∞ DIA 制御を磁気軸受に適用して過渡応答特性を検証する．まず磁気軸受の数学モデルの導出と補償器の初期状態を考慮したH∞ DIA制御系設計について述べる．次にこの補償器の初期状態を考慮したH∞ DIA補償器を異なる初期状態の不確かさに対する重みＮを持つ補償器を設計する．その補償器を用いて，初期値応答と外乱応答を計測し，Nの大きさと時間応答の変化を検証する．

ミニ特集協調とフォーメーションの制御理論編集後記

NAMERIKAWA Toru

計測と制御 46 ( 11 ) 884 2007.11

分散型複雑ネットワーク化制御システムに対する協調・フォーメーション制御問題が近年盛んに研究されている．グラフ理論とシステム制御理論が融合した新しい理論が急速に展開・発展し，更にこの理論は実際にセンサーネットワーク，ロボットの協調制御，宇宙衛星等へ応用され始めている．このような背景を受けて，本ミニ特集は最新の協調とフォーメーションの制御理論とその基盤となる理論の過去と最近の発展の紹介と，今後の方向性の展望を示すことを目的として企画した．

周期的外乱を考慮したＨ∞ＤＩＡ制御と磁気軸受による回転性能の検証

瀬戸洋紀, 滑川徹

日本AEM学会誌 (日本AEM学会) 15 ( 3 ) 333-340 2007.09

Research paper (scientific journal), Joint Work

本論文では磁気軸受のロータ回転時に発生する不釣合い振動を，回転速度に同期した周波数を持つ周期的外乱とみなし，その周期的外乱を抑制するために，H∞ DIA制御問題における一般化プラントに周波数重み関数を導入することで，任意の回転速度における周波数でコントローラ上にピークゲインを付加した．切替え制御による性能検証では，2 種類のコントローラを設計し，切替えることで良好な不釣合い振動の減衰効果と切替え時の過渡応答特性を有することを確認した．

GIMC structure considering communication delay and its application to mechatronic system

Toru Namerikawa, Junichi Miyakawa

2007 AMERICAN CONTROL CONFERENCE, VOLS 1-13 (IEEE) 2874 - 2879 2007

Accepted, ISSN 0743-1619

This paper deals with a new GIMC structure considering a communication delay by using the Smith Predictor and its application to a mechatronic system. First, we stabilize the unstable mechatronic system by a PD controller and define the stabilized system as a new augmented plant. We design the proposed GIMC structure using the Smith Predictor based on H-infinity controllers for the new stabilized augmented plant. Finally, the proposed structure is evaluated experimentally and the effectiveness of the proposed approach is proven. In addition, we apply the proposed structure to a virtual networked control mechatronic system.

Synchronized control for teleoperation with different configurations and communication delay

Hisanosuke Kawada, Kouei Yoshida, Toru Namerikawa

PROCEEDINGS OF THE 46TH IEEE CONFERENCE ON DECISION AND CONTROL, VOLS 1-14 (IEEE) 1610 - 1615 2007

Accepted, ISSN 0743-1546

This paper deals with a control for teleoperation with different configurations and communication delays. We propose a synchronized control with individual gains and power scaling in the task space. In this method, the end-effector motion and force relationship between the master and slave robots can be specified freely in the task space and the control gains can be independently selected appropriately for the master and slave robots. The delay-independent asymptotic stability of the origin of the position and velocity errors is proven by using passivity of the systems and Lyapunov stability methods. The proposed control law achieves synchronization with power scaling. Several experimental results show the effectiveness of our proposed method.

GIMC構造を用いた磁気浮上システムの高性能ロバスト制御

滑川徹, 丸山英人

計測自動制御学会論文集 (計測自動制御学会) 42 ( 11 ) 1181-1187 - 1187 2006.11

Research paper (scientific journal), Joint Work, ISSN 0453-4654

本研究ではGIMC構造を不安定なメカトロニクスシステムである磁気浮上システムに応用し，制御実験による有効性の検証を行う．更にGIMC構造における切替制御の具体的な設計指針と実装方法を提案する.まずGIMC構造に基づく制御系設計の原理と設計手順を述べ，その切替の実装方法について提案を行う．次にH∞混合感度問題を用いて2つの補償器を設計し，それらを基にGIMC構造制御系を構成する．最後に提案法が制御性能とロバスト性を両立していることを実験的に示す．

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Robust H∞ DIA Control of Levitated Steel Plates

T. Namerikawa, D. Mizutani and K. Kuroki

Trans. IEE of Japan (IEE of Japan) 126-D ( 10 ) 1319-1324 - 1324 2006.10

Research paper (scientific journal), Joint Work, ISSN 0913-6339

本稿ではH∞DIA制御を鋼板磁気浮上系に応用し, モデル変動に対するロバスト性を制御実験により評価することを目的とする．制御系設計では, 外乱や不確かさに対する重みを設計し, システムの状態方程式と組み合わせることで一般化プラントを構成し, これに対してコントローラを設計する．提案法であるH∞DIA制御が十分なモデル変動に対するロバスト性を有することを制御実験により明らかにした.

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環境の不確かさと通信遅延を考慮したマスタ・スレーブシステムのロバスト制御

滑川徹, 林鋭渠, 伊藤智, 河田久之輔

日本機械学会論文集, C編 (日本機械学会) 72 ( 721 ) 2821-2828 2006.09

Research paper (scientific journal), Joint Work

本研究では多自由度マニピュレータを用いて環境及びオペレータ特性の不確かさと通信遅延に対するロバスト性能を統合的に保証した制御系設計を行なう．まず2 台のマニピュレータに対してインピーダンス整形により非干渉・線形化を行い，環境及びオペレータの動特性をインピーダンスモデルとして表現し，これらを統合化した一般化プラントを構成する．次に不確かさを考慮したμ-Synthesisに基づく制御系設計法を提案する．最後に制御実験により提案法の有効性を示す．

静止時における自立走行二輪車のモデリングとロバスト姿勢制御

佐藤拓史, 滑川徹

日本機械学会論文集, C編 (日本機械学会) 72 ( 719 ) 2130-2136 2006.07

Research paper (scientific journal), Joint Work

本研究では二輪車を静止状態に限定し，この状態で安定化できる自立走行二輪車を提案する．ライダの重心移動に相当する台車系とハンドル操作系を備えた小型の二輪車を構成する．制御系設計に必要なモデルの運動方程式は，Lagrange 法により導出する．得られた線形モデルに対する安定化制御器をH∞ループ整形設計手法を用いて設計し，姿勢制御実験を行うことにより提案する自立走行二輪車のモデリングとロバスト姿勢制御系について検証を行なう．

Robust H _∞, DIA control of levitated steel plates

Namerikawa Toru, Mizutani Daisuke, Kuroki Shintaro

IEEJ Transactions on Industry Applications 126 ( 10 ) 2006

Research paper (scientific journal), Joint Work, ISSN 0913-6339

This paper deals with an application of 74, DIA control to the magnetically levitated steel plates. Our goal in this research is to suspend two thin steel plates stably by using four electromagnets without any physical contacts. We apply the robust H _∞, DIA control approach to the magnetically levitated steel plates. The H _∞, DIA control problem treats a mixed Disturbance and an Initial state uncertainty Attenuation and it is expected to provide a good transient property to a control system. Experimental results show that the proposed robust control approach is effective for suppressing an elasticity vibration of steel plates.

A passivity-based approach to wide area stabilization of magnetic suspension systems

Toru Namerikawa, Hiroto Kawano

2006 AMERICAN CONTROL CONFERENCE, VOLS 1-12 (IEEE) 1-12 4576 - + 2006

Accepted, ISSN 0743-1619

This paper deals with a passivity-based approach to wide area stabilization of magnetic suspension systems. It is well known that the magnetic suspension systems have strong nonlinearity. In order to realize wide area stabilization of magnetic suspension systems, we design the passivity-based feedback controller considering a nonlinear dynamics of the magnetic suspension systems and a leakage inductance of the electromagnet especially. The systems can be decomposed two subsystems; an electrical subsystem and a mechanical subsystem. We design nonlinear passivity-based controllers for both two subsystems. Steady-state and transient time responses results for some operating points show the effectiveness of the proposed controller experimentally.

Robust H ∞, DIA control of levitated steel plates

Namerikawa Toru, Mizutani Daisuke, Kuroki Shintaro

IEEJ Transactions on Industry Applications 126 ( 10 ) 2006

ISSN 0913-6339

This paper deals with an application of 74, DIA control to the magnetically levitated steel plates. Our goal in this research is to suspend two thin steel plates stably by using four electromagnets without any physical contacts. We apply the robust H ∞, DIA control approach to the magnetically levitated steel plates. The H ∞, DIA control problem treats a mixed Disturbance and an Initial state uncertainty Attenuation and it is expected to provide a good transient property to a control system. Experimental results show that the proposed robust control approach is effective for suppressing an elasticity vibration of steel plates.

Passivity-based synchronized control of teleoperation with power scaling

Hisanosuke Kawada, Toru Namerikawa

2006 SICE-ICASE INTERNATIONAL JOINT CONFERENCE, VOLS 1-13 (IEEE) 4750 - + 2006

Accepted

This paper deals with the passivity-based synchronized control of teleoperation considering position tracking and power scaling. In the proposed method, the motion and the force relation between the master and slave robots can be specified freely. Using a passivity of the systems and Lyapunov stability methods, the asymptotic stability of teleoperation with communication delay and power scaling is proven. Several experimental results show the effectiveness of our proposed method.

High performance robust control of magnetic suspension systems using GIMC structure

Toru Namerikawa, Hideto Maruyama

2006 AMERICAN CONTROL CONFERENCE, VOLS 1-12 (IEEE) 1-12 4582 - + 2006

Accepted, ISSN 0743-1619

This paper deals with a high performance and robust control scheme based on Generalized Internal Model Control(GIMC) Structure. We apply the GIMC structure to the unstable magnetic suspension system and construct a high performance and robust control system. GIMC structure can switch two controllers which have high performance and high robustness respectively. The two controllers using in GIMC structure are designed via H-infinity mixed sensitivity problem. The experimental results show the effectiveness of GIMC structure.

μ-シンセシスを用いた磁気浮上システムのH∞ DIA制御

滑川徹, 瀬戸洋紀

日本機械学会論文集, C編 (日本機械学会) 71 ( 708 ) 2509-2516 - 86 2005.08

Research paper (scientific journal), Joint Work, ISSN 0387-5024

本研究では初期状態の不確かさのもとで良好な過渡応答特性とロバスト制御性能を達成するために，H∞DIA制御にロバスト制御性
能を付加するμ-シンセシスの適用を提案する．具体的にはD-KイテレーションにH∞DIA制御を適用したμ-シンセシスを構築することにより所望の性能を有する制御系の設計が期待できる．従来法と比較することにより提案手法が良好な過渡応答特性とロバスト制御性能を示すことを制御実験により確認する．

An H(infinity) DIA control system design of a magnetic bearing considering periodic disturbance

H Seto, T Namerikawa

2005 IEEE INTERNATIONAL CONFERENCE ON CONTROL APPLICATIONS (CCA), VOLS 1AND 2 (IEEE) 227 - 232 2005

Accepted, ISSN 1085-1992

This paper deals with an H(infinity) DIA control system design of a magnetic bearing considering periodic disturbance. R. control problem which treats a mixed Disturbance and an Initial state uncertainty Attenuation (DIA) control is expected to provide a good transient property, and we confirmed that DIA control has a good rotational performance by some experiments.
On the other hand, active magnetic bearings allow contact free suspension of rotors and they are used for various industrial purposes. We derive a mathematical model of the magnetic bearing which has complicated rotor dynamics and nonlinear magnetic property.
In this paper, we propose a modified control system design of R DIA control in order to consider the periodic disturbance for the magnetic bearings. In fact, we get a controller taken a peak at specified frequency by adding a frequency weighting function in generalized plant. Experimental results show that the proposed robust control approach is effective for improving rotational performance.

Robust control of master-slave robot system considering environmental uncertainties

R Lin, T Namerikawa

2005 IEEE/ASME INTERNATIONAL CONFERENCE ON ADVANCED INTELLIGENT MECHATRONICS, VOLS 1 AND 2 (IEEE) 1299 - 1304 2005

Accepted, ISSN 2159-6255

This paper deals with robust control of a master-slave teleoperation robotic system considering environmental uncertainties.
We construct a master-slave system by using two 2-DOF Direct Drive robot manipulators and design a robust control system via impedance shaping and mu-Synthesis considering various uncertainties; e.g., environment and operator dynamics, perturbation of impedance model and time delay in telecommunications.
The proposed control methodology can guarantee the robust stability and the robust performance for all these uncertainties of the master-slave robotic system. Several experimental results show the effectiveness of our proposed approach for various environmental uncertainties.

On the H∞ Control System Design Attenuating Initial State Uncertainties

T. Namerikawa, M. Fujita, R. S. Smith and K. Uchida

Trans. of the Society of Instrument and Control Engineers (The Society of Instrument and Control Engineers) 40 ( 3 ) 307-314 2004.03

Research paper (scientific journal), Joint Work

本稿では従来の結果から直交条件を外して，外乱と初期状態の不確かさの混合減衰無限時間区間H∞制御問題を定式化し，解の存在のための必要十分条件を導出する．さらに，可解条件だけでなく，補償器の1つの厳密な構成法も導出する．また提案手法を実際に磁気浮上システムに適用し，制御系の設計，および数値シミュレーションを行った．結果を従来法と比較することにより，過渡応答特性に関する提案手法の有用性を示した．

磁気浮上系のロバスト制御 (解説)

藤田政之, 滑川徹

機械の研究 46 ( 3 ) 339-347 2003.12

本稿は磁気浮上システムのμ-設計法に関して平易に解説している．まずシステムの数理モデルを導出する際に，公称モデルだけではなく，異なる構造を持つモデルと許容し得るモデルパラメータの摂動の大きさを用いて非構造的な加法的不確かさを導出する方法について述べる．つぎに公称モデルと加法的不確かさから構成されるモデル集合に基づき，ロバスト性能問題を設定し，D-K反復法を用いて制御仕様を達成するロバストコントローラを設計する方法について解説する．最後に制御実験の結果を紹介する．

H∞ Control System Design of the Magnetic Suspension System Considering Initial State Uncertainties

T. Namerikawa and M. Fujita

Trans. IEE of Japan (IEE of Japan) 123-C ( 6 ) 1094-1100 - 1100 2003.06

Research paper (scientific journal), Joint Work, ISSN 1348-8155

This paper deals with H∞ control attenuating initial-state uncertainties, and its application to a magnetic suspension system. H∞ control problem, which treats as a mixed attenuation of disturbance and initial-state uncertainty for linear time-invariant systems in the infinite-horizon case, is examined. The mixed attenuation supplies H∞ controls with good transients and assures H∞ controls of robustness against initial-state uncertainty. We apply this method to a magnetic suspension system, and evaluate attenuation property of the proposed disturbance and initial-state uncertainty via simulations and experiments. © 2003, The Institute of Electrical Engineers of Japan. All rights reserved.

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A generalized H-infinity control system design attenuating initial state uncertainties

T Namerikawa, M Fujita, RS Smith, K Uchida

PROCEEDINGS OF THE 2002 AMERICAN CONTROL CONFERENCE, VOLS 1-6 (IEEE) 1-6 2204 - 2209 2002

Accepted, ISSN 0743-1619

This paper deals With a generalized H-infinity control attenuating initial-state uncertainties. An H-infinity control problem, which treats a mixed attenuation of disturbance and initial-state uncertainty for linear time-invariant systems in the infinite-horizon case, is examined. The mixed attenuation supplies H-infinity controls with good-transients and assures H-infinity controls of robustness against initial-state uncertainty. We derive a necessary and sufficient condition of the generalized mixed attenuation problem. Furthermore we apply this proposed method to a magnetic suspension system, and evaluate attenuation property of the proposed generalized H (infinity) control approach.

Robust Performance Analysis of Magnetic Bearings

T. Namerikawa and M. Fujita

Trans. IEE of Japan (IEE of Japan) 121-D ( 10 ) 1061-1067 - 1067 2001.10

Research paper (scientific journal), Joint Work, ISSN 0913-6339

This paper deals with uncertain model structures, model validation and robust performance analysis of active magnetic bearings. The dynamics of active magnetic bearing systems are characterized by their instability and complex dynamics of rotor and electromagnets. The feedback control is indispensable to stabilize the system, further the closed-loop systems of magnetic bearings should have robustness for stability and performance against model uncertainties. First we derive a nominal mathematical model of AMBs as a linear state-space model under some assumption and idealization, then we consider the discrepancy between the real physical systems and the obtained nominal design model. This discrepancy can be expressed as the structured uncertainties by Linear Fractional Transformation. These uncertainties include linearization error, parametric uncertainties, unmodeled dynamics, and gyroscopic effect. Then we set the interconnection structure which contains the above structurally represented uncertainties. Next we design a robust controller which achieves robust performance condition. Finally, we validate the interconnection structure with the nominal model and uncertainties, and analyze the robustness of stability and performance of the closed-loop system via the mixed structured singular value.

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Uncertainty Structure and μ- Synthesis of a Magnetic Suspension System

T. Namerikawa and M. Fujita

Trans. IEE of Japan (IEE of Japan) 121-C ( 6 ) 1080-1087 - 1087 2001.06

Research paper (scientific journal), Joint Work, ISSN 0385-4221

H-infinity control system design attenuating initial state uncertainties: Evaluation by a magnetic suspension system

T Namerikawa, M Fujita, RS Smith

PROCEEDINGS OF THE 40TH IEEE CONFERENCE ON DECISION AND CONTROL, VOLS 1-5 (IEEE) 87 - 92 2001

Accepted, ISSN 0191-2216

This paper deals with an H-infinity control attenuating initial-state uncertainties, and its application to a magnetic suspension system. An H-infinity control problem, which treats a mixed attenuation of disturbance and initial-state uncertainty for linear time-invariant systems in the infinite-horizon case, is examined. The mixed attenuation supplies H-infinity controls with good transients or assures H-infinity controls of robustness against initial-state uncertainty. We apply this method to a magnetic suspension system, and evaluate attenuation property of the proposed disturbance and initial-state uncertainty via simulations and experiments.

H∞ Control of a Nonlinear Magnetic Suspension System with Feedback Linearization: An Experimental Study of Robustness and Fragility

R. Suzuki, T. Namerikawa and M. Fujita

Trans. IEE of Japan (IEE of Japan) 120C ( 8/9 ) 1195-1200 - 1200 2000.08

Research paper (scientific journal), Joint Work, ISSN 0385-4221

本論文はフォードバック線形化を用いた非線形磁気浮上系のH∞制御のロバスト性と脆弱性に関して議論している．モデリング検証のため，まず２つの仮定に基づいて２つの非線形モデルを導出し，それぞれにフィードバック線形化H∞コントローラを設計した．つぎにこれらのコントローラを用いてステップ状の力外乱が浮上体に加わった場合の浮上体の位置情報を計測し，ロバスト性，さらにモデル構造に起因する脆弱性に関して検証と考察を行った．

Robust performance analysis of uncertain magnetic bearings

Toru Namerikawa, Masayuki Fujlta

Proceedings of the ASME Turbo Expo (American Society of Mechanical Engineers (ASME)) 4 ( 10 ) 1061-1067 2000

This paper deals with uncertain model structures, model validation and robust performance analysis of active magnetic bearing systems. The dynamics of active magnetic bearing systems are characterized by their instability and complex dynamics of rotor and electromagnets. One of the most critical problems of AMBs is a description of a complex behavior of the dynamics of electromagnets and their forces. The exact description of them is almost hopeless, some approximations and assumptions must be employed, and consequently a discrepancy between the real physical system and the nominal design model cannot be avoided. This discrepancy of the magnetic bearing systems is a serious problem of stability and performance. Hence feedback control is indispensable to stabilize the system, further the closed-loop systems of AMBs should have robustness for stability and performance against model uncertainties. First we derive a nominal mathematical model of AMBs as a linear state-space model under some assumption and idealization, then we consider the discrepancy between the real physical systems and the obtained nominal design model. This discrepancy can be expressed as the structured uncertainties by Linear Fractional Transformation. These uncertainties include linearization error, parametric uncertainties, unmodeled dynamics, and gyroscopic effect. Then we set the interconnection structure which contains the above structurally represented uncertainties. Next we design a robust controller which achieves robust performance condition. Finally, we validate the interconnection structure with the nominal model and uncertainties, and analyze the robustness of stability and performance of the closed-loop system via the mixed structured singular value.

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Wide area stabilization of a magnetic bearing using exact linearization

Matsumura Fumio, Namerikawa Toru, Murata Noriyuki

Electrical Engineering in Japan (English translation of Denki Gakkai Ronbunshi) (TECHNOMIC PUBL CO INC) 128 ( 2 ) 53 - 62 1999.07

Accepted, ISSN 0424-7760

An active magnetic bearing (AMB) is a bearing used to suspend a rotor by magnetic forces without any contact. Feedback control is indispensable for a magnetic bearing, because it is essentially an unstable system. To design a feedback control system, a linear mathematical model of the plant is convenient; however, the force of the electromagnet is highly nonlinear. Thus, usually a linear approximation around the operating point is employed, but the obtained linearized model cannot express the exact behavior of the system at any other operating points. In this paper, we discuss the wide area stabilization of magnetic bearings using the exact linearization approach. First, we derive a nonlinear mathematical model for a magnetic bearing, then we show that this nonlinear system belongs to a class of exactly linearizable nonlinear systems. Next, by using the exact linearization method, we transfer the nonlinear model of a magnetic bearing to a linear time-invariant state model in spite of change of the operating point and the rotational speed of the rotor. Then we construct the state feedback control system by the conventional LQ method. Finally, we evaluate the validity of our proposed method by experiments.

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磁気軸受の不確かなモデルとロバスト制御 (解説)

滑川徹, 藤田政之

計測と制御 38 ( 2 ) 87-91 1999.02

磁気軸受は常電導電磁石の吸引力を用いて，回転体の回転方向以外の自由度を拘束し，回転体を完全に非接触で空中に支持する複雑なエレクトロメカニカルシステムと捉えることが出来る．本稿では，まず最近国内外で発表された当該分野の研究論文を中心にモデルとロバスト制御の観点から磁気軸受制御の現状について報告している．さらに著者らの最近の研究結果である，磁気軸受システムの不確かさを考慮したLFT表現についても紹介している．

厳密な線形化による磁気軸受の広域安定化

松村文夫, 滑川徹, 村田徳之

電気学会論文誌D (電気学会) 118D ( 3 ) 410-416 - 410 1998.03

Research paper (scientific journal), Joint Work

本論文では厳密な線形化を用いて磁気軸受の広域安定化を行った．まず磁気軸受に対して非線形モデルを導出し，その非線形モデルが非線形な座標変換と入力変換により厳密線形化可能であることを証明した．そして厳密線形化手法を用いて非線形情報を保存した線形モデルを導出し，線形モデルに対して最適制御により状態フィードバックを設計した．最後に制御実験により，動作点移動，ロータの回転速度変化に対する制御性能・安定性の有効性検証を行った．

磁気浮上系の不確かさの記述と μ-設計 (解説)

滑川徹, 藤田政之

電気学会論文誌C (電気学会) 118C ( 3 ) 289-292 1998.03

実システムを制御する際には，一般には対象となるシステムのモデルを導出し，そのモデルに対して補償器の設計を行い，得られた補償器を実システムに適用する．しかしモデルを導出する際には実システムとモデルにギャップが生じることは避けられない．本稿では，ロバスト制御理論の中核をなすμ-設計法とそれに密接に関わるLFT(Linear Fractional Transformation)を用いた不確かなシステムの表現法に焦点を絞り，不安定系である磁気浮上系への適用例を詳しく紹介している．

Uncertainty structure and mu-design of a magnetic suspension system

T Namerikawa, M Fujita, F Matsumura

PROCEEDINGS OF THE SIXTH INTERNATIONAL SYMPOSIUM ON MAGNETIC BEARINGS (TECHNOMIC PUBL CO INC) 439 - 448 1998

Accepted

This paper deals with modeling, structured uncertainties, mu-analysis and synthesis of a magnetic suspension system. First we derive a nominal model of the plant and consider its structured uncertainties e.g., linearization error, parametric uncertainties, and neglected dynamics. Then we set the interconnection structure which includes the above structurally represented uncertainties. Next we design a robust mu controller which achieves robust performance condition using the structured singular value mu. Finally we evaluate the proposed interconnection structure and verify robustness and performance of the designed mu controller by experiments.

State of the Art of Magnetic Bearings -Overview of Magnetic Bearing Research and Applications – (解説)

F. Matsumura Y. Okada, M. Fujita and T. Namerikawa

JSME Int. Journal, Ser. C (JAPAN SOC MECHANICAL ENGINEERS) 40 ( 4 ) 553-560 - 560 1997.12

Joint Work, ISSN 1340-8062

Magnetic bearings levitate, suspend and guide rotors by magnetic forces without physical contact. The non-contact support offers many advantages and opportunities for a wide variety of applications, Since the First International Symposium on Magnetic Bearings was held in Zurich in 1988, this field of research has expanded, and competition in research and development has been very keen, This review presents the recent trends in applications, control methodologies, sensorless controls, bearingless motors, unbalance control, problems of flexible rotors, eddy current properties and power amplifiers.

Experimental Verification on Gain Scheduled H∞ Robust Control of a Magnetic Bearing

T. Namerikawa, M. Fujita and F. Matsumura

JSME Int. Journal, Ser. C (JSME) 40 ( 4 ) 561-569 - 569 1997.12

Research paper (scientific journal), Joint Work, ISSN 1340-8062

This paper deals with the problem of gyroscopic effect and unbalance vibration of the Magnetic Bearing system. Using a gain scheduled Hm control with a free parameter phi, we design a control system which attenuates the unbalance vibration, and guarantees the stability against the gyroscopic effect in specified rotational speed. Further we implement the controller and evaluate the effectiveness of the proposed approach by experiments. First, our experimental setup is explained, a mathematical model of the magnetic bearing is derived. Then, we introduce the gain scheduled H infinity control with free parameters to a magnetic bearing control, in order to reject the disturbances caused by unbalance of the rotor, and guarantee the stability against gyroscopic effect, even if rotational speed of the rotor changes. At last, several experimental results show the effectiveness of this proposed method.

Experimental Verification on Gain Scheduled H∞ Robust Control of a Magnetic Bearing

Namerikawa Toru, Fujita Masayuki, Matsumura Fumio

JSME International Journal, Series C: Mechanical Systems, Machine Elements and Manufacturing (JSME) 40 ( 4 ) 561 - 569 1997.12

ISSN 1344-7653

This paper deals with the problem of gyroscopic effect and unbalance vibration of the Magnetic Bearing system. Using a gain scheduled H∞ control with a free parameter Φ, we design a control system which attenuates the unbalance vibration, and guarantees the stability against the gyroscopic effect in specified rotational speed. Further we implement the controller and evaluate the effectiveness of the proposed approach by experiments. First, our experimental setup is explained, a mathematical model of the magnetic bearing is derived. Then, we introduce the gain scheduled H∞ control with free parameters to a magnetic bearing control, in order to reject the disturbances caused by unbalance of the rotor, and guarantee the stability against gyroscopic effect, even if rotational speed of the rotor changes. At last, several experimental results show the effectiveness of this proposed method.

磁気浮上系におけるセンサ支持板の共振と制御剛性

原外満, 滑川徹, 松村文夫

日本AEM学会誌 (日本AEM学会) 5 ( 3 ) 34-40 1997.09

Research paper (scientific journal), Joint Work

本論文は磁気浮上系・磁気軸受における変位センサ支持板の共振と制御剛性に関して検討している．本稿ではセンサ支持板の変位を考慮した状態方程式を導出した．この式を基にセンサ支持板の共振周波数とフィードバックゲイン，およびロータ質量に関する不安定条件を導出し，これらのパラメータ空間上で不安定領域を明らかにした．またこの領域を避けることにより良好な実験結果が得られた．

H-infinity control of a robot manipulator using a linear parameter varying representation

T Namerikawa, M Fujita, F Matsumura

PROCEEDINGS OF THE 1997 AMERICAN CONTROL CONFERENCE, VOLS 1-6 (I E E E) 111 - 112 1997

Accepted, ISSN 0743-1619

Modeling and robustness analysis of a magnetic suspension system considering structured uncertainties

T Namerikawa, M Fujita

PROCEEDINGS OF THE 36TH IEEE CONFERENCE ON DECISION AND CONTROL, VOLS 1-5 (IEEE) 2559 - 2560 1997

Accepted, ISSN 0191-2216

This paper deals with modeling, uncertainty description and robustness analysis of a magnetic suspension system. First we derive a nominal model of the plant and consider its uncertainties e.g., linearization error, parametric uncertainties, and neglected dynamics. Then we set the interconnection structure which includes the above structurally represented uncertainties. Next the analysis of robust stability/performance for the obtained interconnection structure with three-types controllers by mixed structured singular value (mixed mu). Finally we evaluate the robustness of the proposed models and analytic results by experiments.

3点法による真円度測定における高次成分算出の試行

原外満, 滑川徹, 松村文夫

日本機械学会論文集（C編） (日本機械学会) 62 ( 604 ) 172-178 - 4596 1996.12

Research paper (scientific journal), Joint Work

本論文では３点法における高次成分の良好な再現方法について議論している．計算不可能な設定角の領域を明確にし，この角度を避けて真円度を測定することにより，目標次数までのすべてのフーリエ成分を求めることが出来ることを示した．また設定角の測定誤差を小さくするためには，３台のセンサの出力信号波形の合同性が重要であることを明らかにし，合同性を容易に検査する手法の一例を示した．

Application of Gain Scheduled H∞ Robust Controllers to a Magnetic Bearing

F. Matsumura,T. Namerikawa, K. Hagiwara and M. Fujita

IEEE Trans. on Control Systems Technology (IEEE) 4 ( 5 ) 484-493 - 493 1996.09

Research paper (scientific journal), Joint Work, ISSN 1063-6536

This paper deals with the problem of an unbalance vibration zof the magnetic bearing system, We design a control system achieving the elimination of the unbalance vibration, using a loop shaping design procedure (LSDP), After the introduction of our experimental setup, a mathematical model of the magnetic bearing is shown, Then, the gain scheduled H-infinity robust controllers with free parameters are designed, based on the LSDP, so as to asymptotically reject the disturbances caused by unbalance on the rotor, even if the rotational speed of the rotor varies, Finally, several simulation results and experimental results show the effectiveness of this proposed methodology.

磁束密度負帰還による磁気軸受電磁石の応答速度改善に関する検討

原外満, 滑川徹, 松村文夫

日本AEM学会誌 (日本AEM学会) 4 ( 3 ) 54-59 - 59 1996.09

Research paper (scientific journal), Joint Work, ISSN 0919-4452

本論文では磁気軸受の高剛性化を目的として，磁束密度フィードバックによる磁気軸受電磁石の応答速度改善に関して議論した．電流―電磁力伝達特性は，渦電流が無視出来ない高周波領域ではゲインが低下し，位相が遅れる．この問題を解決するために本稿では渦電流の作用を考慮した磁束密度フィードバック法を提案した．これにより電磁石の応答速度が改善し，磁気軸受を安定浮上回転させる際にロータの１次曲げモード共振周波数の減衰・消滅を達成した．

平行リンクロボットマニピュレータのロバストH∞制御

滑川徹, 藤田政之, 松村文夫

電気学会論文誌D (電気学会) 116D ( 2 ) 207 - 215 1996.02

Research paper (scientific journal), Joint Work

本論文ではH∞制御理論に基づくロバスト制御系設計法をロボットマニピュレータに適用した．リンク間の干渉とマニピュレータの重力項を構造的な不確かさとして取り扱い，その不確かさに対しても安定性と制御性能を保持する制御系の設計を行った．ロバスト安定性を保持するためにスモールゲイン定理に基づくH∞制御を用い，制御系解析の保守性を軽減するために定数スケーリング行列を導入した．最後に制御実験を行い，提案法の有効性を検証した．

A linear parameter varying approach to a gain scheduled flexible joint robot

T Namerikawa, M Fujita, F Matsumura

AMC '96-MIE - 1996 4TH INTERNATIONAL WORKSHOP ON ADVANCED MOTION CONTROL, PROCEEDINGS, VOLS 1 AND 2 (I E E E) 653 - 656 1996

Accepted

リニア直流モータを用いたパンタグラフ基礎実験システムの H∞制御

滑川徹, 磯部真一, 松村文夫

電気学会論文誌D (電気学会) 115-D ( 11 ) 1412-1419 - 1419 1995.11

Research paper (scientific journal), Joint Work

本稿ではリニア直流モータをアクチュエータとして用いるパンタグラフ基礎実験装置において, 種々の力外乱に対しても架線-パンタグラフ間の接触圧を一定にするレギュレータ問題を扱った．本研究では時間応答に対する制御性能を考慮したH∞制御系設計を行い，特に被制御量に重みをかけることにより，時間領域でのレギュレーションと応答特性の改善を図った．パンタグラフ基礎実験装置での力制御実験を行い，有効性を確認した.

μ-synthesis of an electromagnetic suspension system

Fujita Masayuki, Namerikawa Toru, Matsumura Fumio, Uchida Kenko

IEEE Transactions on Automatic Control 40 ( 3 ) 530 - 536 1995.03

ISSN 0018-9286

This paper deals with μ-synthesis of an electromagnetic suspension system. First, an issue of modeling a real physical electromagnetic suspension system is discussed. We derive a nominal model as well as a set of models in which the real system is assumed to reside. Different model structures and possible model parameter values are fully employed to determine unstructured additive plant perturbations, which directly yield uncertainty frequency weighting function. Second, based on the set of plant models, we setup robust performance control objectives. Third, we make use of the D-K iteration approach for the controller design. Finally, implementing the controller with a digital signal processor, experiments are carried out. With these experimental results, we show robust performance of the designed control system.

Access to Document (DOI)

DIGITAL IMPLEMENTATION OF ROBUST MU-CONTROL FOR A ROBOT MANIPULATOR

M FUJITA, T NAMERIKAWA, K UCHIDA

PROCEEDINGS OF THE 1994 AMERICAN CONTROL CONFERENCE, VOLS 1-3 (I E E E) 2450 - 2454 1994

Accepted

Robust control of a robot manipulator using a linear parameter varying representation

T Namerikawa, F Matsumura, M Fujita

PROCEEDINGS OF THE IEEE INTERNATIONAL CONFERENCE ON INDUSTRIAL TECHNOLOGY (ICIT'96) (I E E E) 489 - 492 1994

Accepted

In this paper, we present a robust control for a flexible-joint robot manipulator using linear parameter varying representation. The robot manipulator dynamics can be brought to a quasi linear parameter varying (LPV) form by a state transformation. An LPV system is defined as a linear system whose dynamics depend on an exogenous variable which can be measured upon system operation. In this case, the scheduling variables are the joint angles q. which are state variables. Using a quasi-LPV form, we design a robust controller by mu-synthesis to achieve robust performance specification.

MU-SYNTHESIS OF AN ELECTROMAGNETIC SUSPENSION SYSTEM

M FUJITA, T NAMERIKAWA, F MATSUMURA, K UCHIDA

PROCEEDINGS OF THE 31ST IEEE CONFERENCE ON DECISION AND CONTROL, VOLS 1-4 (I E E E) 2574 - 2579 1992

Accepted

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