川口 夏樹

A new data-driven model-reference robust Proportional-Integral-Derivative (PID) control is proposed for a regulator system. In the proposed method, the PID parameters are decided such that a prescribed robust stability is achieved. Furthermore, the disturbance rejection performance is optimized. Since the proposed method is designed as a model reference problem, where the reference model and the controller parameters are optimized, trade-off design between robust stability and regulator performance is achieved by selecting the prescribed robust stability. Finally, the effectiveness of the proposed method is demonstrated through numerical examples.

A data-driven design method for a cascade control system is proposed. The cascade control system consists of inner and outer loops, where the control interval of the outer loop is an integer multiple of the inner loop; hence, the system is a dual-rate system. In the proposed method, controllers in the inner and outer loops are designed based on one-shot data. In such a dual-rate cascade system, since the controllers are designed using different data-rate signals, the lifting technique is applied to align the dual-rate data. To show its effectiveness, the proposed method is compared with a conventional single-rate cascade control method, and numerical simulations and experiments are presented to examine servo and regulation performance.

The present study discusses the design method for controlling a single-input/single-output linear time-invariant dual-rate system, where the sampling interval of the plant output is longer than the holding interval of the control input. In such a dual-rate system, the intersample output might oscillate even when the sampled output converges to the reference input in the steady state. In a conventional ripple-free method, an existing control law is extended by introducing an exogenous variable, which is independent of the discrete-time sampled response, and the exogenous variable is designed for eliminating the steady-state intersample ripples without changing the existing sampled response. In another method, since a control law is designed such that the intersample performance is optimized, the intersample ripples are eliminated in the transient as well as steady states. However, the preservation of an existing sampled response is not taken into account. The present study proposes a new design method for eliminating the intersample ripples subject to the existing sampled response. In the proposed method, the continuous-time index is optimized subject to the existing discrete-time response. As a result, the intersample ripples are eliminated in the transient as well as steady states, and the existing discrete-time sampled response is maintained. The proposed method is compared to the conventional dual-rate design methods in numerical examples, and the effectiveness of the method is demonstrated.

The present study uses linear quadratic regulator (LQR) theory to control a vibratory system modeled by a fractional-order differential equation. First, as an example of such a vibratory system, a viscoelastically damped structure is selected. Second, a fractional-order LQR is designed for a system in which fractional-order differential terms are contained in the equation of motion. An iteration-based method for solving the algebraic Riccati equation is proposed in order to obtain the feedback gains for the fractional-order LQR. Third, a fractional-order state observer is constructed in order to estimate the states originating from the fractional-order derivative term. Fourth, numerical simulations are presented using a numerical calculation method corresponding to a fractional-order state equation. Finally, the numerical simulation results demonstrate that the fractional-order LQR control can suppress vibrations occurring in the vibratory system with viscoelastic damping.

The dual-rate control system, in which the sampling interval is an integer multiple of the holding interval, is designed using the null-space of the steady-state characteristic of the controlled plant. In the proposed method, a dual-rate control law is extended independent of the steady-state discrete-time output response. As a result, the intersample ripples caused by the input oscillation are eliminated by reallocating the control input. The proposed method based on the steady-state characteristic is a simple strategy compared with conventional methods based on the dynamic characteristic. © 2021 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC.

In the design of simple adaptive control (SAC) using almost strictly positive real (ASPR), the feedback control system is stabilized by the output feedback with a high gain. Although ASPR is not, however, generally satisfied, it is achieved by introducing a parallel feedforward compensator (PFC). When SAC is designed for the augmented system which consists of an actual plant and PFC, not the actual plant output but the augmented system output converges to the reference input because of the influence of PFC. To resolve the problem, an extension method of the conventional SAC is proposed. In the proposed method, based on the null-space of an augmented plant, an exogenous input, which is independent of the augmented system output, is newly introduced. Because the exogenous input is designed so that PFC output is to be 0, the actual plant output is the same as the augmented system output in the steady state, and as a result, the actual plant output converges to the reference input. From a practical application point of view, the proposed method can easily improve the control performance of the conventional SAC with a PFC. In the proposed method, an exogenous input generated as the feedback signal of PFC output is only added to the conventional SAC control input. Therefore, the proposed method can be applied to various field in which the SAC method has been implemented, e.g., process control, mechanical systems, power systems, robotics, and others. In the present study, the effectiveness of the proposed method is also demonstrated through experiments for a motor control.

© 2020, The Author(s). A new approach to the active fault diagnosis (AFD) for input redundant plants is presented in this paper. A test signal which helps the diagnosis is injected to the plant in addition to nominal control input in the AFD typically. One feature of the proposed AFD is adaptive allocation of the test signal. The adaptive allocator which distributes the test signal and injects it to the redundant actuators is introduced in this paper. A fault-diagnosis (FD) system that estimates fault location and its magnitude from adaptive parameter of the adaptive allocator is constructed with a simple neural network (NN) model. Furthermore, a A fault-tolerant adaptive control system which includes the adaptive test signal allocator is designed based on the model reference adaptive control (MRAC) technique. The adaptive laws of the adaptive allocator and controller are derived by using a suitable Lyapunov function. By performing experiments using a two-input redundant plant, we show the effectiveness and applicability of the proposed AFD and MRAC system.

The aim of the present study is to improve the understanding of the control engineering for university students through the experience of the control experiment, and hence an experimental device is developed. The students are educated the control engineering using the device, and the educational effect is evaluated. In the present study, the students take examinations for the control engineering before and after the experiment, and the effect is evaluated objectively.

<p>In this paper, we propose a null-space compensation control for linear first-order systems with redundant two input channels. In the input redundant systems, control input vector generally has null-space component of the plant parameter vector. The null-space component does not contribute to the generation of the control force which drives the plant state. If a control input that does not include the null-space component can be generated, efficient control is achieved from the viewpoint of minimizing the norm of the control input. In the proposed method, an adaptive control method is used to design a control system that compensates for the null-space component, even if the plant parameter vector is unknown. The effectiveness is shown by numerical examples.</p>

© 2013 IEEE. The present study discusses the consensus control of dual-rate multi-agent systems, where the sampling/communication interval of quantized data is an integer multiple of the control interval. A conventional multi-agent system uses a dynamic quantizer which is designed in a single-rate system where the intervals are equal, i.e., the control interval length is the same as the communication interval length. However, a dynamic quantizer designed in a dual-rate system is expected to have improved control performance. In the present study, an objective function is divided into a quantization term, which is related to the quantization error, and the remaining term. The proposed dual-rate dynamic quantizer is designed such that the quantization term is minimized. Finally, in numerical examples, the proposed dual-rate method is quantitatively evaluated by comparing with the conventional single-rate method, and the effectiveness of the proposed method is demonstrated.

The present paper discusses a design method for a single-input single-output linear time-invariant dual-rate sampled-data control system, where the sampling interval of a plant output is longer than the holding interval of a control input. In such a control system, intersample output oscillation, called ripple, can occur even if the sampled output converges to the reference input. In order to resolve this problem, two design methods have been proposed such that the existing sampled output response is maintained: an open-loop system design method and a closed-loop system design method. However, the open-loop design method cannot be applied to systems for which the gain matrix of the control input is full rank. On the other hand, the closed-loop design method can be used for such systems, but the sampled output response is maintained only in the steady state. The present study proposes a new closed-loop design method in which ripples are eliminated and both the transient and steady-state responses are maintained. The effectiveness of the proposed method is demonstrated through numerical examples. (C) 2019 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

&lt;p&gt;In this paper, we propose a design of the fault tolerant adaptive control system for the input redundant linear plants which has &lt;i&gt;m &lt;/i&gt;input channels with model reference adaptive control scheme. A feature of the proposed control system is to introduce the adaptive allocator which distributes and injects external signals into the plant. We derive adaptive law which ensures stability of output of the plant which has up to (&lt;i&gt;m−&lt;/i&gt;1) faults, using a suitable Lyapunov function. Through a numerical simulation, we show the stability and fault-tolerance of the designed MRAC.&lt;/p&gt;

&lt;p&gt;In this paper, we propose an active fault detection scheme with input redundancy of the plant. The proposed active fault detection scheme aims at quickly detecting of the occurrence of actuator sticking under steady state. In addition, a new fault tolerant control (FTC) design is developed to implement the active fault detection scheme for input redundant 2-input 1-output plant. Finally, the effectiveness of the proposed FTC and the applicability of the proposed active fault detection scheme are verified through several experiments.&lt;/p&gt;

<p>This paper discusses a design method for an input multiple single-input single-output dual-rate control system, where the sampling interval of the plant output is an integer multiple of the hold interval of the control input. A dual-rate control law that stabilizes a closed-loop system is extended using null-space. In the extended control system, a redundant input that is designed independently of the closed-loop system, is obtained. Because the redundant input is designed so that the control input is constant in the steady-state, the intersample ripples are eliminated without changing the reference response from the reference input to the plant output. Finally, the effectiveness of the proposed method is demonstrated through numerical examples.</p>

This paper reports a project-based learning (PBL) program for graduate students to develop science communication skills. To achieve this, the program made graduate students majoring in control engineering designed about an educational experiment system to understand the concept of control technique for elementary and junior high school pupils. As a result, they designed an educational program using a single-degree-of-freedom helicopter model. This program was carried out in the &amp;ldquo;youngsters&amp;rsquo; science festival&amp;rdquo; which is regional science festival. In addition, they summarized the details of the system and the responses of participants and presented at a conference on control, measurement and system integration. Through this PBL program, the students could develop their science communication skills by themselves.

© 2016 This study discusses an education method aimed at increasing student depth of understanding of control theory via an education system based on the flight control system of a model helicopter. Using this system, undergraduate students use different methods to vary the altitude of the helicopter, and, in the process, directly experience dynamics, linearity, and nonlinearity, as well as the control requirements and differences between manual and automatic control. The results of this study show that student understanding of control theory can be effectively increased using our education system.

In this study, we design a Fault-Tolerant Control (FTC) system based on estimation of fault signals, using a discrete linear multi-input multi-output (MIMO) system model. The FTC system can maintain nominal performance if a fault occurs in one of its components. The existing FTC method has the following 3 steps: Fault-Diagnosis, Estimation of fault magnitude, and Generation a new control law to compensate for the fault effect. The existing FTC method assumes that actuator and sensor faults correspond to a loss of actuator effectiveness or fault sensor measurements. Therefore, it cannot maintain nominal tracking control performance when an actuator has a failure that suggests complete breakdown of function. In this paper, we present a new FTC method that is extended to deal with the failure of an actuator. We confirm the feasibility of the presented FTC method by FTC simulation by comparison with the existing method. © 2014 ISSN 1881-803X.