Control System Synthesis Problem Research Articles

H∞ Control Synthesis for Lurie Networked Control Systems with Multiple Delays Based on the Non‐Uniform Characteristic

AbstractThis paper investigates the H ∞ control synthesis problem for Lurie networked control systems (NCSs) with multiple time‐varying delays. With the consideration of both network‐induced delays and data packet dropout, Lurie NCSs discussed in this work can effectively be transformed into Lurie control systems with multiple time‐varying delays. In addition, with the non‐uniform distribution characteristics of network delays, based on the delay probability distribution, the stable controller design, and H ∞ synthesis, approaches are derived in the form of linear matrix inequalities (LMIs). Finally, a set of numerical examples are studied, and the results demonstrate the applicability and effectiveness of the suggested approaches.

Analysis of Uncertain Discrete-Time Linear Periodic Systems based on System Lifting and LMIs

In this article, we propose novel linear matrix inequality (LMI) conditions for the stability and l 2 gain performance analysis of discrete-time linear periodically time-varying (LPTV) systems. These LMIs are convex with respect to all of the coefficient matrices of the LPTV systems and this property is promising when we deal with several control system analysis and synthesis problems. For example, we can apply those LMIs straightforwardly to robust performance analysis problems of LPTV systems that are affected by polytopic-type uncertainties. Even though our approach for robust performance analysis is conservative in general, we can reduce the conservatism gradually by artificially regarding the original N-periodic system as pN-periodic and increasing p. In addition, thanks to the simple structure of the LMI conditions, we can readily derive a viable test to verify the exactness of the computation results.

Design of stochastic fault tolerant control for H2 performance

AbstractIn this paper, the controller synthesis problem for fault tolerant control systems (FTCS) with stochastic stability and H2 performance is studied. System faults of random nature are modelled by a Markov chain. Because the real system fault modes are not directly accessible in the context of FTCS, the controller is reconfigured based on the output of a fault detection and identification (FDI) process, which is modelled by another Markov chain. Then state feedback and output feedback control are developed to achieve the mean square stability (MSS) and the H2 performance for both continuous‐time and discrete‐time systems with model uncertainties. Copyright © 2006 John Wiley & Sons, Ltd.

Robust Speed Control of Ultrasonic Motors via Gain-Scheduled H∞ Control on Stator Vibration Amplitude

This paper deals with a controller synthesis problem for precise speed control systems of ultrasonic motors (USMs) considering nonlinear characteristics of USMs. For this problem, we firstly propose a parameter varying plant model which represents the nonlinear characteristics by using information of amplitude of stator vibration as a model parameters. Secondly, to provide higher performance for the systems, we design a parameter varying controller in a systematic way by applying gain-scheduled H∞ control technique for the parameter varying plant model. In addition, control experiments show the validity of the proposed method.

Optimization as a tool for design/control integration

There is a long tradition of the use of optimization techniques to help solve process synthesis and design problems. Advances in optimization algorithms to handle problems involving integer variables, and problems involving dynamic systems with path constraints have recently been exploited to help address issues in the integration of process design and control. Methods, based on optimization, to assess controllability, to select control structures for a given process (the control system synthesis problem) and to develop integrated designs of process and control system for cases where dynamic performance is critical are presented in this paper.

Optimization as a tool for design/control integration

There is a long tradition of the use of optimization techniques to help solve process synthesis and design problems. Advances in optimization algorithms to handle problems involving integer variables, and problems involving dynamic systems with path constraints have recently been exploited to help address issues in the integration of process design and control. Methods, based on optimization, to assess controllability, to select control structures for a given process (the control system synthesis problem) and to develop integrated designs of process and control system for cases where dynamic performance is critical are presented in this paper.

Synthesis of control systems for chemical plants A challenge for creativity

Synthesis of control systems for chemical plants is that step during process design and process engineering where the chemical engineer selects the control objectives; measured outputs and manipulated inputs; the control structure connecting measurements and manipulations as well as the control laws between them. This paper reviews the problem, its characteristics, previous works on the subject and finally attempts a broad outline of future developments. First, it presents the scope of its content and then proceeds to discuss the various facets of process control system synthesis. The review of the previous works provides a critical panorama of earlier problem formulations, solutions and methodologies, outlining their assumptions, extent of applicability, advantages and shortcomings. A series of specific examples demonstrates the multitude of control system synthesis problems and sets the stage for an in depth examination of its proper formulation and characteristics. It is pointed out that the synthesis of a process control system is only a part of the general system which oversees the operation of a plant. Consequently, questions related to safety, performance monitoring, detection of faults, etc., are also discussed. Since the operability of a chemical process is closely related to its design, the paper explores the effect that process design has on the synthesis of a control system and vice versa. Furthermore, the paper attempts to organize all the above issues in a coherent system which can guide the control designer towards the synthesis of effective control systems. Finally, the need for a change in the process control curricula is examined and some new provocative questions for future research are raised.

Application of Sliding Modes to Induction Motor Control

The results of the research concerned with the problem of induction motor control system synthesis using variable structure systems theory is presented. The procedure of control systems synthesis for the control of position speed and torque is given, as well as basic experimental results and problems related to realization of the proposed control algorithms.

A direct method for synthesis of optimum distributed systems

The present paper is concerned with the numerical solution of the synthesis problem for optimal linear distributed control systems, via a specific direct method. For this method the control function is represented by a finite number of conveniently chosen functions. In this work an example of a linear diffusion system with boundary control is considered, which is worked out entirely, including numerical results. Proper proof are given for the consistency, stability, and convergence of the numerical solution by that direct method. Also, a procedure is indicated for estimating the approximation error in the computed optimal control.

On the inverse describing function problem

With the exception of a passing reference in an early note by Zadeh1, little or no attention appears to have been paid to the inverse describing function (IDF) problem. In essence this problem is concerned with extracting a description of a non-linear element given only its describing function. The problem is important as the final link in the nonlinear synthesis problem for automatic control systems, for various experimental determinations, and finally for itself. In this paper an analytic solution to the problem which results in expressions in the form of Volterra integral equations is provided. The conditions under which the representation for the non-linear element is unique are discussed and additional requirements for the unique definition of non-single-valued non-linear elements are given. As might be anticipated the describing function of a memory-type non-linear element is not sufficient to obtain a unique representation for the element. Practical computational techniques are mentioned for the machine solution of the IDF and several examples are given.