New delay-dependent conditions on robust stability and stabilisation for discrete-time systems with time-delay

This article is concerned with new robust stability conditions and robust stabilisation method for a discrete-time system with time-delay and time-varying structured uncertainties that come into state and input matrices. An improved approach to obtain new robust stability conditions is proposed. Our approach employs a generalised Lyapunov functional combined with the parameterised model transformation method and the generalised free weighting matrix method. These generalisations lead to generalised robust stability conditions that are given in terms of linear matrix inequalities. Moreover, based on new robust stability conditions, a robust stabilisation method for uncertain discrete-time systems with time-delay is given. Numerical examples compare our robust stability conditions with some existing conditions to show the effectiveness of our approach and also illustrate the improvement of our robust stabilisation method.     

基于矩阵测度的非线性广义时滞系统鲁棒模糊控制

研究T-S模糊广义时滞系统的鲁棒控制问题.不同于传统的寻求公共正定矩阵的方法,基于矩阵测度给出保证系统鲁棒稳定的充分条件,并将此条件进一步转化为线性矩阵不等式.通过求解线性矩阵不等式,得到状态反馈控制器和静态输出反馈控制器.最后通过算例仿真验证了方法的有效性.     

Sliding mode control of uncertain systems with distributed time-delay: parameter-dependent Lyapunov functional approach

The robust stability and robust sliding mode control problems are studied for a class of linear distributed time-delay systems with polytopic-type uncertainties by applying the parameter-dependent Lyapunov functional approach combining with a new method of introducing some relaxation matrices and tuning parameters, which can be chosen properly to lead to a less conservative result. First, a sufficient condition is proposed for robust stability of the autonomic system; next, the sufficient conditions of the robust stabilization controller and the existence condition of sliding mode are developed. The results are given in terms of linear matrix inequalities (LMIs), which can be solved via efficient interior-point algorithms. A numerical example is presented to illustrate the feasibility and advantages of the proposed design scheme.     

Sliding mode control of uncertain systems with distributed time-delay： parameter-dependent Lyapunov functional approach

The robust stability and robust sliding mode control problems are studied for a class of linear distributed time-delay systems with polytopic-type uncertainties by applying the parameter-dependent Lyapunov functional approach combining with a new method of introducing some relaxation matrices and tuning parameters, which can be chosen properly to lead to a less conservative result. First, a sufficient condition is proposed for robust stability of the autonomic system; next, the sufficient conditions of the robust stabilization controller and the existence condition of sliding mode are developed. The results are given in terms of linear matrix inequalities （LMIs）, which can be solved via efficient interior-point algorithms. A numerical example is presented to illustrate the feasibility and advantages of the proposed design scheme.     

不确定时滞离散非线性系统的鲁棒耗散滤波

研究了一类带参数不确定性和非线性动态的离散时滞系统的鲁棒耗散滤波问题.所给系统中的不确定项是时变未知且范数有界.基于Lyapunov稳定性方法,先对参数已知而带有非线性动态的时滞离散系统,给出渐近稳定判据,然后讨论鲁棒耗散滤波器的存在条件及设计方法.在此基础上进一步考虑参数不确定性情形,将鲁棒耗散滤波器问题转化为参数确定的情况.从而将鲁棒耗散滤波器的设计问题转换为线性矩阵不等式的求解问题.最后给出仿真例子验证所得结果的有效性.     

An LMI approach to robust H-infinity control for uncertain singular time-delay systems

The problem of robust H-infinity control for a class of uncertain singular time-delay systems is studied in this paper. A new approach is proposed to describe the relationship between slow and fast subsystems of singular time- delay systems, based on which, a sufficient condition is presented for a singular time-delay system to be regular, impulse free and stable with an H-infinity performance. The robust H-infinity control problem is solved and an explicit expression of the desired state-feedback control law is also given. The obtained results are formulated in terms of strict linear matrix inequalities (LMIs) involving no decomposition of system matrices. A numerical example is given to show the effectiveness of the proposed method.     

An LMI approach to robust H-infinity control for uncertain singular time-delay systems

The problem of robust H-infinity control for a class of uncertain singular time-delay systems is studied in this paper. A new approach is proposed to describe the relationship between slow and fast subsystems of singular time- delay systems, based on which, a sufficient condition is presented for a singular time-delay system to be regular, impulse free and stable with an H-infinity performance. The robust H-infinity control problem is solved and an explicit expression of the desired state-feedback control law is also given. The obtained results are formulated in terms of strict linear matrix inequalities （LMIs） involving no decomposition of system matrices. A numerical example is given to show the effectiveness of the proposed method.     

基于观测器的时滞系统鲁棒控制器的设计

研究了一类不确定时滞系统基于观测器的鲁棒镇定问题,系统的不确定性时变未知且范数有界,目的是设计状态观测器和线性无记忆观测状态反馈控制器,使其能够镇定一类状态和控制输入不确定性时滞系统。基于Lyapunov稳定性理论,采用线形矩阵不等式这一有效工具,给出了系统基于观测状态反馈鲁棒镇定的充分条件,并且利用线形矩阵不等式的解构造了使得系统鲁棒稳定的基于观测状态反馈控制器,所得结果与时滞相关,从而相对减弱了控制器设计的保守性。数值算例表明了所提出的设计方法的有效性。     

时变不确定离散时滞系统的H∞鲁棒控制

研究了一类线性不确定离散时滞系统的H_∞鲁棒控制问题,其时变不确定项是范数有界的,但无需满足匹配条件.基于线性矩阵不等式 (LMI)方法,得到了可H_∞鲁棒镇定的一个充分条件.通过求解一个特定的线性矩阵不等式,即可获得H_∞状态反馈控制器.具体算例说明了该方法的有效性.     

Exponential stability of switched stochastic delay systems with non-linear uncertainties

This article considers the robust exponential stability of uncertain switched stochastic systems with time-delay. Both almost sure (sample) stability and stability in mean square are investigated. Based on Lyapunov functional methods and linear matrix inequality techniques, new criteria for exponential robust stability of switched stochastic delay systems with non-linear uncertainties are derived in terms of linear matrix inequalities and average dwell-time conditions. Numerical examples are also given to illustrate the results.     

H∞ control of parameter-dependent state-delayed systems using polynomial parameter-dependent quadratic functions

This paper presents the issue of robust disturbance attenuation and robust asymptotic stability problem for finite-dimensional linear parameter-dependent state-delayed systems. The use of polynomial parameter-dependent quadratic Lyapunov functions and linear matrix inequalities (LMIs) formulations for robust H _∞ control are considered. It is shown that the state feedback control can be determined to guarantee the stability of the closed-loop system independently of the time-delay. We present an illustrative example to demonstrate the applicability of the proposed design approach.     

Delay-dependent robust stability criteria for singular time-delay systems by delay-partitioning approach

In this paper, the problem of delay-dependent robust stability for singular time-delay systems is investigated. The parametric uncertainties are assumed to be norm bounded. Based on the idea of delay partitioning, A new Lyapunov–Krasovskii functional is proposed to develop new delay-dependent criteria, that ensures the considered system to be regular, impulse free and stable in terms of linear matrix inequalities. Furthermore, the Wirtinger-based integral inequality approach has been employed to derive less conservative results. Finally, some numerical examples are provided to demonstrate the effectiveness of the obtained results and for comparison with previous works.     

模糊时滞系统的输出反馈控制及其稳定性分析

利用模糊T－S模型对一类不确定非线性时滞系统进行建模，在此基础上，提出了模糊不确定时滞系统的状态反馈控制及其输出反馈控制的设计，并给出了模糊闭环系统渐近稳定的充分条件，基于李亚普诺夫函数和线性矩阵不等式方法，证明了模糊系统的渐近稳定性。     

一类不确定时滞系统的时滞依赖型鲁棒控制器设计

本文研究了一类状态和控制同时存在滞后的不确定线性系统时滞依赖型鲁棒镇定２，针对所有容许的时变未知但有界的不确定性，得到了一种新的确保系统可鲁棒镇定的充分条件和相应的鲁棒镇定控制器设计方法，所得到的结果与时滞相关的，并且以线性矩阵不等式（ＬＭＩ）形式给出。     

一类不确定时滞系统的自适应控制

设计基于观测器的自适应控制器,利用Lyapunov稳定性理论分析系统的稳定性,得到利用线性矩阵不等式表示的闭环系统稳定的充分条件,观测增益矩阵和反馈增益矩阵可以通过求解线性矩阵不等式得到。通过一个实例验证所给结论的有效性。     

Delay-dependent criteria for robust stability of linear neutral systems with time-varying delay and nonlinear perturbations

This article investigates the robust stability of linear neutral systems with time-varying delay and nonlinear perturbations. Using a new Lyapunov–Krasovskii functional and employing some free weighting matrices, less conservative delay-dependent robust stability conditions for such systems in terms of linear matrix inequalities are derived. Numerical examples are given to indicate significant improvements over some existing results.     

On robust stabilization of Markovian jump systems with uncertain switching probabilities

This brief paper is concerned with the robust stabilization problem for a class of Markovian jump linear systems with uncertain switching probabilities. The uncertain Markovian jump system under consideration involves parameter uncertainties both in the system matrices and in the mode transition rate matrix. First, a new criterion for testing the robust stability of such systems is established in terms of linear matrix inequalities. Then, a sufficient condition is proposed for the design of robust state-feedback controllers. A globally convergent algorithm involving convex optimization is also presented to help construct such controllers effectively. Finally, a numerical simulation is used to illustrate the developed theory.     

基于时滞状态反馈的鲁棒容错控制

研究了一类线性不确定时滞系统的鲁棒容错控制问题。针对具有状态滞后,且假定状态和控制输入的不确定项均是范数有界的线性系统,基于Lyapunov稳定性理论和线性矩阵不等式方法,通过引入状态反馈和带时滞的状态反馈,得出了一个此类系统在对执行器失效或传感器失效两种情况下具有鲁棒容错性能的充分条件,并通过求解线性矩阵不等式组得到容错控制器设计结果。数值算例验证了这种控制器的设计方法的有效性和可行性。     

Design of robust gain-scheduled PI controllers for nonlinear processes

Gain-scheduling has proven to be a successful design methodology in many engineering applications. However, in the absence of a sound theoretical analysis, these designs come with no guarantees of robust stability, performance or even nominal stability of the overall gain-scheduled deign.This paper presents such an analysis for one type of nonlinear gain-scheduled control system based on the process input for nonlinear chemical processes. A methodology is also proposed for the design and optimization of the robust gain-scheduled PI controller. Conditions which guarantee robust stability and performance are formulated as a finite set of linear matrix inequalities (LMIs) and hence, the resulting problem is numerically tractable. Issues of modeling error and input-saturation are explicitly incorporated into the analysis. A simulation study of a nonlinear continuous stirred tank reactor (CSTR) process indicates that this approach can produce efficient sub-optimal robust gain-scheduled controllers.