佐藤 孝雄

The present paper proposes a new method for designing a weigh feeder control system. The model of a weigh feeder cannot be obtained accurately because its dynamic characteristics are time varying and its high frequency vibration modes are not easily identified. In the present paper, a weigh feeder is approximated as a first-order plus integrator system, and a self-tuning controller is designed on the basis of the approximated model to estimate its gain recursively. The purpose of this study is to design a controller to be actually employed in industry. To this end, a controller is assumed to consist of proportional gain for control error and steady state control input. As a result, the proposed controller has a simple structure and its controller parameters can be understood intuitively. Consequently, the proposed design method can be easily adopted in industry. Numerical and experimental results demonstrate its effectiveness. Copyright © 2011 Inderscience Enterprises Ltd.

This paper proposes a new design method for the positioning control system of a hard disk drive (HDD) head. To control the head in an HDD, the control input supplied to the voice coil motor is updated at a fast rate, but the sampling interval of the head position is restricted because of hardware constraints. Hence, the designed control system is a multirate system. In this study, the multirate control system designed for controlling the head in an HDD is extended, and the intersample response is improved independently of the sample response. The effectiveness of the proposed method is demonstrated by a numerical example. © 2011 Zhejiang University.

This paper proposes a new design method for controlling a head in a hard disk drive (HDD) system. In the HDD control system, the sampling interval of the head position is restricted, but the hold interval of the control input can be arbitrarily set. Hence, this study discusses a design method for a multi-rate control system, where the sampling and the hold intervals are not equal. In this study, a pole-assignment multi-rate control law is extended using newly introduced parameters such that the sample response of the plant output is maintained. Furthermore, intersample ripples in the steady state are eliminated using the new design parameters because those can be selected independently of the sample response. As a result, the intersample response can be improved independently of the sample response. The proposed method is applied to a benchmark problem of a HDD system, and its effectiveness is demonstrated. © 2011 IFAC.

In the petroleum and refinery industry, it is necessary to establish the performancedriven control strategy in order to improve productivity (where the control performance is first evaluated and then the controller is re-designed). This paper describes a design scheme of performance-driven controllers which are based on the control mechanism described above. The proposed control scheme is simulated and its performance is numerically examined. Also, the proposed method is applied to the weigh feeder and the control results are shown. © 2011 IFAC.

In the design of a weigh feeder control system, proportional and integral (PI) control is widely employed because parameter tuning is easy and the control parameter can be intuitively understood. Hence, it is desirable to achieve high control performance using PI control rather than advanced control methods. In this study, the control parameters of the PI control system are designed on the basis of generalised minimum variance control (GMVC), and the weighting parameter for the control deviation is adaptively updated according to the control performance. Because GMVC-based PI control is based on control performance, this method can be easily adopted in industry. Both the simulation and the experimental results demonstrate the effectiveness of the GMVC-based PI control. Copyright © 2011 Inderscience Enterprises Ltd.

This paper proposes a new method for designing a variable structure controller in the presence of load disturbance or plant parameter variation. In conventional methods, servo tracking is achieved by a variable structure controller designed using integral compensation. However, the proposed method employs proportional compensation as well as integral compensation, and optimal proportional and integral gain for stabilizing a closed-loop system can be obtained by solving the Riccati equation. As a result, robust servo tracking can be achieved and further, transient response is better than that of conventional methods. The proposed method is applied to an inverted pendulum system, and its effectiveness is demonstrated by both simulation and experiment.

Most weigh feeders are controlled by a PID control method, and it is desirable to achieve high performance with this PID control. The present paper discusses the application of a generalized predictive control (GPC)-based PID controller to a weigh feeder. In conventional methods, GPC-based PID controllers are designed using a step-type reference signal, but in control of a weigh feeder, a reference input to be followed by a measured signal is a ramp-type signal because the measured signal is discharged mass. Hence, control of a weigh feeder using a GPC-based PID controller is enhanced for tracking a ramp-type signal. Because GPC can be expressed by PID parameters, the proposed method can be easily adopted in various industries. Experimental results show that a weigh feeder is well controlled using the enhanced GPC-based PID controller. (C) 2009 Elsevier Ltd. All rights reserved.

This study discusses a design method for a multirate control system, where the sampling interval of the plant output is an integer multiple of the hold interval of the control input. A closed-loop system is assumed to be stabilized by a state feedback control law with an observer, and the feedback control law is extended to improve the intersample response. One of the advantages of the proposed method is that the control law is redesigned independently of the closed-loop system. Hence, the intersample response can be improved independently of the sampled response. Numerical simulations are presented to demonstrate the effectiveness of the proposed method.

This study describes the development of a car orientation measurement system using a single camera. We have proposed the method that calculate a car's 3D distance and direction from 4 corner points of its license plate image. However, to obtain a car orientation by this method, we have to detect and track the license plate shape with high accuracy. Therefore, in this report, we considered to track the license plate outline using particle filter. The effectiveness of our approach has been verified through experiments using real car images. © 2010 SICE.

This study reports that a weigh feeder is controlled using a performance-adaptive control method in which controller parameters are recalculated only when parameter estimation deteriorates. In this method, a PI control law is based on generalized minimum variance control (GMVC). Hence, a design parameter in GMVC is adjusted such that given control specifications are satisfied, and then, PI parameters are based on a redesigned GMVC law. The objective of this study is to reduce the variance of the variation in the control input. To this end, a conventional performance-adaptive control method is modified, and its effectiveness is shown by applying to a weigh feeder. © 2010 SICE.

In design of a weigh feeder control system, most controllers employed in industry are designed using proportional and integral (PI) compensations, and it is desirable to achieve high performance by PI control. Hence, a generalized minimum variance control (GMVC)-based PI control system is designed for a weigh feeder, and the design parameters of GMVC are adjusted on the basis of control performance. Because the GMVC-based PI control is based on control performance, the proposed method can be easily adopted in industry. An experimental result demonstrates the effectiveness of the proposed design method.

This paper discusses a design method for a sample-date system, in which a continuous-time plant is controlled using a discrete-time controller. It is assumed that the sampling interval of plant output is an integer multiple of the hold interval of control input, that is, the control system is a multirate system. Using the state-space representation, a multirate control law, which stabilizes a closed-loop system, is extended independently of the sample response. In the proposed method, a multirate control is redesigned such that the steady-state intersample response is improved. Hence, the intersample response can be improved independently of the sample response.

This paper proposes a new method for designing a weigh feeder control system. The model of a weigh feeder cannot be obtained accurately because its dynamic characteristics are time varying and its high frequency vibration modes are not easily identified. In this paper, a weigh feeder is assumed to be a first-order plus integrator system, and a control law consists of a constant feed-forward control input and a feedback loop to obtain a simple control method. The objective of this study is to design a control law to be actually employed in industry. To this end, a control law is designed using proportional gain for control error and steady-state control input. However, the proportional gain must be finely tuned. Hence, it is tuned using a discrete-time extremum-seeking method. In the proposed method, the proportional gain is tuned using an iterative feedback tuning. Therefore, the proposed method has the advantage that the control performance is not deteriorated due to gain fluctuation because the proportional gain is not changed in an experiment. As a result, the proposed control law has a simple structure and its control parameters can be intuitively understood. Consequently, the proposed design method can be easily adopted in industry. Numerical and experimental results demonstrate its effectiveness.

This paper proposes a new controller for track-seeking control of a head in a Hard Disk Drive (HDD). The sampling period of the head position is restricted, but the hold period of a control input can be changed to improve HDD system, performance. Hence this paper proposes a method for designing Generalized Predictive Control (GPC) in a multirate system., where the sampling period is longer than the hold period. In design of a standard GPC, intersample behavior is not evaluated because the controller is based on the optimization of the sample behavior. However, the intersample behavior has to be evaluated in the HDD system. Therefore, the proposed controller's derivation is based on an objective function that includes intersample behavior as well as sample behavior. The proposed method is applied to a benchmark problem and its effectiveness is demonstrated.

This paper proposes a new method for designing a multirate control system, in which a sampling interval of plant output is (in integer multiple of a hold interval of a control input. To employ the effect of integral compensation in the multirate system, two-degree-of-freedom (2DOF) Generalized Predictive Control (GPC) is proposed only when there is a modeling error or disturbance. In this paper, a one-degree-of-freedom (1DOF) multirate GPC without integral compensation is first derived, and next the 1DOF multirate GPC is extended into 2DOF control using integral compensation. Numerical examples demonstrate the effectiveness of the proposed method.

This paper proposes a new method for designing a digital control system, in which a plant in continuous time is controlled by updating a control input in discrete time. The controlled system is a dual-rate system in which the sampling period is restricted to be double the control period. Hence, a fast-rate control system cannot be obtained, and to obtain a single-rate control system, a designed system is a slow-rate control system, where the control input is updated at slow-rate (2Ts) and the plant output is sampled at slow-rate (2Ts). In this paper, the slow-rate single-rate system is a dual-rate system, where the control input is updated at fast-rate (T s) and the plant output is sampled at slow-rate (2Ts). Further, the dual-rate system is redesigned for improving stability margin independent of the output response of the pre-designed slow-rate single-rate system. Numerical examples demonstrate the effectiveness of the proposed method. © 2009 IEEE.

This paper proposes an effective control system for a container crane. For efficient crane operation, it is necessary to realize accurate positioning of the crane, to minimize oscillation of containers and to realize the fastest possible control time while they are being carried. The crane input is assumed to be binary, with maximum and minimum values for quick control. The entire crane system including the binary input is considered as a hybrid system. A hybrid system is a generic term for a system in which continuous and discrete dynamics exist together. We control the entire crane system using the Mixed Logical Dynamical (MLD) system, which is a representation method for a hybrid system. It is generally known that an MLD system can be controlled by Model Predictive Control (MPC). We confirm the effectiveness of the proposed technique through an experiment using a crane model. © 2009 IEEE.

This paper proposes a new control method for a weigh feeder. A weigh feeder has been widely employed in industry because it can dispense powder at a specified rate or amount. The proposed controller is mainly divided into a feed-forward and a feedback compensators. In order to obtain a simple controller, the former gives a steady-state control input designed using a nominal plant gain, and the latter consists of proportional gain and the control error between a reference input and a plant output. Because the proportional gain must be designed to stabilize a closed-loop system, it is updated using an extremum-seeking method. As a result, the control performance of the proposed method can be improved by seeking its extremum value. The effectiveness of the proposed method is demonstrated by both simulation and experimental results.

This paper proposes a new method for designing a multirate output feedback control system, where the update interval of the control input is an integer multiple of the sampling interval of the plant output. The proposed method is designed by extending a conventional multirate output feedback control using the latest information of a plant. Hence, the proposed method can improve the control performance compared with conventional methods without the latest information. Furthermore, the obtained control structure can be simpler than conventional methods. An inverted pendulum system is controlled to demonstrate the effectiveness of the proposed method.

This paper proposes a new method for designing a self-tuning PID controller. A PID controller is designed on the basis of generalised predictive control with a terminal matching condition (γGPC) to automatically tune its PID parameters. The proposed PID controller has a time-varying proportional gain to precisely achieve γGPC performance. Furthermore, a PID controller is designed on the basis of γGPC extended by using coprime factorisation to obtain stable proportional gain. Hence, γGPC can be well approximated by the proposed PID controller. A numerical example demonstrates its effectiveness. © 2009 Inderscience Enterprises Ltd.

The present paper discusses the design methods for Generalized Minimum Variance Control (GMVC)-based PID controllers in a two-degree-of-freedom (2DOF) system. The PID parameters of the PID controllers are designed art the basis of GMVC, and they are designed as self-tuning controllers. In the present paper, PID parameters are decided such that a GMVC law is approximated by a PID controller. Therefore, in design of a 2DOF PID controller based on GMVC with a feed-forward compensator (abbreviated as FF-type GMVC), because the order of the feed-forward compensator depends on a dead-time, the approximation deteriorates if the dead-time is long. In the present paper, GMVC with a pre-compensator (PC-type GMVC) is approximated by a 2DOF PID controller to obtain better approximation. Furthermore, a 2DOF PID controller having time-varying proportional gain is based on a strongly stable GMVC with a pre-compensator to improve control performance. Numerical examples are given to confirm the effectiveness of the proposed method.

This study proposes an adaptive control method of a weigh feeder. A weigh feeder dispenses material into a process at a precise rate, and it has been employed in industries, e.g., process control, cement manufactur ing plants, food industry equipment, and so on. To introduce advanced control into industries, self-tuning controllers are designed for controlling a weigh feeder. Three difference controllers are designed; one degree-of-freedom (1DOF) PID, 1DOF PD, and two degree-of-freedom (2DOF) PD controllers, and these control methods are compared through experimental results. Because discharged mass is measured by employing loss-in-weight method, a reference input followed by a plant output is ramp-type, and a type-2 control system has to be designed. Since the controlled object includes an integrator, a type-2 control system can be obtained by using 1DOF PID controller. In design of 2DOF PD control, a pre-compensator is designed to eliminate steady-state velocity error. Further, to be compared with 1DOF PID and 2DOF PD control, a 1DOF PD controller is designed.In this paper, PID and PD controllers are designed on the basis of generalized minimum variance control (GMVC) to obtain useful control methods adopted in industries. In design of the proposed control methods, GMVC can be replaced precisely with a simple PID or PD controller, and advanced control performance can be obtained. Experimental results are shown and compared, and the effectiveness of the proposed design method is shown. Copyright © 2007 International Federation of Automatic Control All Rights Reserved.

The present paper proposes a new design method for a dual-rate system, in which a plant in continuous time is controlled by updating a control input in discrete time, in which the sampling interval of the plant output differs from the update interval of the control input. A dual-rate control law that stabilizes a discrete-time closed-loop system is extended. One of the advantages of such an extension is that the dual-rate control law can be redesigned to be independent of the discrete-time closed-loop system. Consequently, the intersample response can be improved by making it independent of the sampled response using the newly introduced design parameters. The present paper proposes a design method for design parameters to improve the intersample response in the steady state. Numerical examples are presented to confirm the effectiveness of the proposed method.

This paper discusses design of Generalized Predictive Control (GPC) scheme. GPC is designed in two cases; the first is a dual-rate (DR) system, where the sampling interval of a plant output is an integer multiple of the holding interval of a control input, and the second is a fast-rate single-rate (FR-SR) system, where both the holding and sampling intervals are equal to the holding interval of the DR system. Furthermore, the relation between them is investigated, and this study gives the conditions that FR-SR and DR GPC become equivalent. To this end, a future reference trajectory of DR GPC is rewritten, and a future predictive output of the FR-SR GPC is rearranged.

This paper proposes a design method of the Generalized Predictive Control (GPC) strategy which can take account of intersample behavior as well as sampled behavior. To this end, a discrete-time equivalent plant model and cost function for a continuous-time plant incorporated with zero-order hold and discrete-time controller are derived, and the modified discrete-time GPC is designed. To verify the effectiveness of our proposed method, the controller is applied to a benchmark problem of a hard-disk drive. (c) 2007 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

This paper proposes a new design method of a pressure control system in a furnace of a thermal power plant boiler. To improve the control performance of the pressure control system in a furnace controlled by using self-tuning I-P controllers, a feed-forward compensator is introduced. Simulation results are illustrated to show the effectiveness of our proposed method.

A pendulum rod of a nonlinear system is controlled by using sliding model control. To control the angle of the pendulum rod, a new design method of the sliding model control is proposed using proportional and integral compensation. Conventional and our proposed control methods are applied into the nonlinear system, those control methods are compared through simulation and experiment. © 2007 IEEE.

This paper proposes a new design method of a GPC-Based PID controller. The proportional gain of a PID controller is time-varying, and the PID controller is designed using the future reference input. Hence, a GPC law can be approximated by the PID controller finely. Because a controller of GPC has to be stable to obtain stable proportional gain, using extended GPC using coprime factorization, the PID controller is designed.

This paper proposes a design method of Generalized Minimum Variance Control (GMVC) in sampled-data systems, where a continuous-time plant is controlled with a discrete-time controller. The proposed design method derives a discrete-time control law which minimizes a continuous-time performance function with a zero order hold. Because the proposed method evaluates not only sampling instants but. intersample, the intersample performance of the proposed method is improved better than conventional design methods in discrete-time. Finally, we illustrate numerical simulation results in order to show the effectiveness of the proposed method.

In this paper, a weigh feeder is controlled by using a self-tuning controller. To make a plant output follow a ramp-type reference input without a steady-state error, we propose a new design method for generalized minimum variance control with a pre-compensator. In order to confirm the effectiveness of the proposed method, experimental results are shown.

An effective design method of a proportional-integral-derivative (PID) controller is proposed. The PID parameters of the PID controller are designed on the basis of a generalized predictive control (GPC) law. The PID controller has a time-varying proportional gain, and the PID parameters are designed using the future reference trajectory of the GPC. Finally, numerical examples are shown for illustrating the effectiveness of the proposed method. (C) 2006 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

Generalized minimum variance control is designed in a multi-rate system where the sampling interval of a plant output is longer than the holding interval of a control input. Because new design parameters are introduced, intersample ripples in the multi-rate system are suppressed by weighting the variation in the control input. Furthermore, the proposed method is an extension of a conventional design method. Finally, simulation results are illustrated in order to show the effectiveness of the proposed method. (c) 2006 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

In this paper a new design method of a self-tuning PID controller is proposed. The PID controller is designed based on generalized predictive control (GPC) including a future reference trajectory. The PID controller given in this paper is based on GPC and, is I-PD type controller. It is shown that the design parameter adjusting the future reference trajectory changes only the integral time of the PID controller. In order to illustrate the effectiveness of the proposed method, numerical examples are shown.

The behavior of a pendulum rod of a mechanical system in chaotic state is controlled. The system is nonlinear with unknown parameters, and an adaptive backstepping method is applied to control the pendulum rod. A validation experiment shows that the behavior of the pendulum rod can be made to follow a reference behavior.

in this paper a new design method of a self-tuning I-PD controller is proposed. The I-PD controller is designed based on a generalized predictive control (GPC) law. By using a conventional design method of the I-PD controller based on the GPC law, it is impossible to introduce future reference trajectory into the I-PD controller. The future reference trajectory of the GPC approaches a setpoint value gradually from a present output, that is one of the features of the GPC. The proposed method can introduce the advantage of the GPC into the IPD controller exactly because the proposed method expresses the future reference trajectory suitably when the set-point value is given as a step type signal. This paper shows that the structure of a PID controller based on the GPC law becomes an I-PD type by using the proposed method and that a design parameter of the GPC which adjusts the future reference trajectory inuences only an integral time of the I-PD controller. in order to illustrate the effiectiveness of the newly proposed method, numerical examples are shown. Copyright © 2005 IFAC.

This paper proposes a new design method of a PID controller.We design the PID controller based on generalized minimum variance control (GMVC) with a steady state predictive output (GMVCS). The proposed method has better approximation than conventional design schemes since the orders of compensators of a GMVCS law do not increase even if a dead-time increases. Furthermore, in this paper it is shown that GMVCS has an advantage that it is possible to place poles of the closed-loop system at desired places. Hence, the PID controller is designed based on the pole-placement GMVCS. Finally, we illustrate numerical simulation results in order to show the effectiveness of the proposed control algorithm. Copyright © 2005 IFAC.

This paper proposes a new design method of a pressure control system in a furnace of a thermal power plant boiler. Because the plant is a non-linear system with interactions among variables, it is difficult to utilize linear control theory. Additionally the actual plant is controlled by proportional and integral compensations [6, 7]. Hence, in a conventional method, the plant has been approximated by two independent first-order plus dead-time models and then two controllers have been designed for each of the first-order plus dead-time models [6, 7]. And self-tuning I-P controllers based on GPC laws have been also used in order to approximate the plant by time-invariant linear models. Since the conventional method regards the interactions as disturbances, it is required to suppress the influence of the interactions. Therefore, in this paper, to reduce the influence of interactions among variables, a feed-forward compensator is introduced to the conventional method newly. The proposed method is especially useful when a dead-time of the plant is long. Simulation results are given to show the effectiveness of the proposed method.

Generalization minimum variance control (GMVC) has been designed in a single-rate system. In this paper, a design method of GMVC in an input multiple multirate system is proposed. Finally, to illustrate the effectiveness of the proposed method, numerical examples are shown. © 2005 SICE.

A pressure control system in a furnace of a thermal power plant boiler is controlled by using two I-P controllers and a feed-forward compensator. The two I-P controllers are designed based on generalized predictive control laws. To improve control performance, a new design method of the feed-forward compensator is proposed. A simulation result is given to show the effectiveness of the proposed method © 2005 SICE.