时滞不确定随机系统基于参数依赖Lyapunov函数的稳定条件

针对一类具有凸多面体参数不确定性的时滞随机系统, 研究了其鲁棒稳定性问题. 通过引入适当的加权矩阵变量来寻找Leibniz-Newton公式各项之间的关系, 从而直接地处理系统中的时滞状态项, 避免了常规的应用Leibniz-Newton公式来进行模型变换的间接方法所带来的较大保守性. 采用参数依赖Lyapunov函数方法, 推导了此类系统鲁棒稳定的时滞相关的充分条件. 本文所得条件为线性矩阵不等式形式, 便于借助于内点算法进行求解. 仿真实例证明了本文所提出的稳定条件具有较低的保守性.     

Further Improvement of Free-Weighting Matrices Technique for Systems With Time-Varying Delay

A novel method is proposed in this note for stability analysis of systems with a time-varying delay. Appropriate Lyapunov functional and augmented Lyapunov functional are introduced to establish some improved delay-dependent stability criteria. Less conservative results are obtained by considering the additional useful terms (which are ignored in previous methods) when estimating the upper bound of the derivative of Lyapunov functionals and introducing the new free-weighting matrices. The resulting criteria are extended to the stability analysis for uncertain systems with time-varying structured uncertainties and polytopic-type uncertainties. Numerical examples are given to demonstrate the effectiveness and the benefits of the proposed method     

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.     

不确定离散多时滞系统的时滞相关鲁棒镇定

研究了多面体不确定离散多重时滞系统的稳定性分析和镇定问题.通过定义新的 Lyapunov函数,提出了一个时滞相关稳定判据.并将de Oliveira的参数依赖思想引入该判据． 得到了适用于多面体不确定系统的参数依赖型时滞相关稳定条件.在此基础上,研究了鲁棒镇 定状态反馈控制器的设计方法．采用El Ghaoui提出的锥补线性化思想将控制器的设计转化为 一个受线性矩阵不等式约束的非线性规划问题.     

凸多面体不确定随机时滞系统的参数依赖状态反馈控制

考虑了凸多面体不确定随机时滞系统的参数依赖状态反馈控制问题.把参数相关的Lyapunov-Krasovskii泛函方法和自由权矩阵方法相结合,得到了基于线性矩阵不等式(LMI)的时滞相关及参数相关的鲁棒镇定的充分条件.由于在引入自由权矩阵时,减少了所用的自由矩阵数目,使得给出的参数依赖的控制器更易于实现.最后用例子说明了结果的有效性.     

A less conservative robust stability test for linear uncertain time-delay systems

This note concerns with the robust stability of linear uncertain systems with state-delay. The uncertainty is assumed to be of polytopic type. A less conservative delay-dependent linear matrix inequality (LMI) method is presented based on a new Lyapunov-Krasovskii functional. The present method incorporates a relaxed parameter-dependent technique combined with a recently proposed idea of introducing free-weighting matrices. When confined to delay-free case, the present result is also less conservative than existing stability tests using parameter-dependent methods. Numerical examples are given to show the less conservativeness of the results.     

Robust stability functionals of state delayed systems with polytopic type uncertainties via parameterdependent Lyapunov functions

This paper considers the problem of robust stability for linear systems with a constant time-delay in the state and subject to real convex polytopic uncertainty. Both delay-independent and delay-dependent stability conditions are characterized by linear matrix inequalities which allow the use of parameter-dependent Lyapunov functionals to analyse the system stability against parameter perturbations, and therefore improve the conservativeness resulting from the single Lyapunov functional. In order to determine the maximum of time-delay within which the system remains stable, the problem can be cast into a generalized eigenvalue problem and solved by standard LMI solvers. Two examples are included to illustrate the proposed method.     

Peak-to-peak filtering for periodic piecewise linear polytopic systems

In this paper, the robust peak-to-peak filtering problem for periodic piecewise systems with polytopic uncertainties is investigated. Attention is focused on designing of robust peak-to-peak filters that guarantee the robust asymptotic stability of periodic piecewise filtering error system and satisfy a prescribed peak-to-peak disturbance attenuation level for all admissible uncertainties. A sufficient condition is proposed for robust stability and peak-to-peak performance by employing the constructed time-varying Lyapunov function. Two design approaches based on the Lyapunov function with parameter-dependent matrices and parameter-independent matrices are utilised to solve this problem. An algorithm is proposed to compute the periodic filter parameters governed by non-convex feasibility conditions. Two numerical examples are presented to demonstrate the effectiveness of the proposed techniques.     

一类不确定切换奇异时滞系统的时滞依赖鲁棒镇定

针对一类不确定切换奇异时滞系统,对其鲁棒镇定问题进行了研究.首先利用多李亚普诺夫泛函方法和线性矩阵不等式工具,通过引入适当的自由权矩阵,在适当的切换律下,给出了基于严格线性矩阵不等式表示的标称自治切换奇异系统正则、无脉冲且渐近稳定的时滞依赖条件;然后基于此条件,通过设计相应的状态反馈子控制器,得到了保证闭环系统对所有允许的不确定性是正则、无脉冲且渐近稳定的时滞依赖条件,同时给出了子控制器的显示表达式.数值算例表明该方法的有效性.     

New characterization of positive realness and control of a class of uncertain polytopic discrete-time systems

This paper deals with the problems of positive real analysis and control synthesis for a class of discrete-time polytopic systems with uncertainties. The systems under consideration are modelled in a polytopic form with linear fractional uncertainties in its vertices. A new linear matrix inequality (LMI) characterization of positive realness for this class of systems is given. It enables one to check the positive realness by using parameter-dependent Lyapunov function. This new characterization exhibits a kind of decoupling between the Lyapunov matrix and the system matrices, which is subsequently exploited for control design. Based on the new result, sufficient conditions with reduced conservatism are obtained. A numerical example is also included to demonstrate the applicability of the proposed results.     

Delay‐dependent robust stability analysis for switched time‐delay systems with polytopic uncertainties

In this paper, sufficient conditions are provided for the stability of switched retarded and neutral time‐delay systems with polytopic‐type uncertainties. It is assumed that the delay in the system dynamics is time‐varying and bounded. Parameter‐dependent Lyapunov functionals are employed to obtain criteria for the exponential stability of the system in the form of linear matrix inequality (LMI). Free‐weighting matrices are then provided to express the relationship between the system variables and the terms in the Leibniz–Newton formula. Numerical examples are presented to show the effectiveness of the results. Copyright © 2014 John Wiley & Sons, Ltd.     

A less conservative robust stability criteria for uncertain neutral systems with mixed delays

This paper is concerned with the problem of the delay-dependent robust stability of neutral systems with mixed delays and time-varying structured uncertainties. By considering the cross-terms with additional design parameters, a complete form of Lyapunov–Krasovskii functional is constructed. Then some free weighting matrices are introduced, and a sufficient stability condition is obtained in terms of linear matrix inequalities. The obtained criterion is dependent on the sizes of neutral delay and discrete delay and are less conservative than those produced by previous approaches. Numerical examples are given to illustrate both the improvement the proposed method provides over some existing ones and the relationship between the neutral- and discrete-delay.     

A new discrete-time robust stability condition

A new robust stability condition for uncertain discrete-time systems with convex polytopic uncertainty is given. It enables to check stability using parameter-dependent Lyapunov functions which are derived from LMI conditions. It is shown that this new condition provides better results than the classical quadratic stability. Besides the use of a parameter-dependent Lyapunov function, this condition exhibits a kind of decoupling between the Lyapunov and the system matrices which may be explored for control synthesis purposes. A numerical example illustrates the results.     

随机不确定时滞系统的鲁棒H∞控制

本文研究了随机不确定时滞系统的鲁棒稳定性与鲁棒H∞控制问题,系统的不确性具有凸多面体形式.利用线性矩阵不等式方法,通过依赖于参数的Lyapunov函数,得到了此类系统鲁棒随机镇定的充分条件.在此基础上,又给出了H∞状态反馈控制器的设计.     

Delay-dependent criteria for robust stability of time-varying delay systems

This paper deals with the problem of delay-dependent robust stability for systems with time-varying structured uncertainties and time-varying delays. Some new delay-dependent stability criteria are devised by taking the relationship between the terms in the Leibniz-Newton formula into account. Since free weighting matrices are used to express this relationship and since appropriate ones are selected by means of linear matrix inequalities, the new criteria are less conservative than existing ones. Numerical examples suggest that the proposed criteria are effective and are an improvement over previous ones.     

离散多时滞系统的时滞相关鲁棒稳定性分析

研究了具有凸多面体不确定性的离散多时滞系统鲁棒稳定性问题．通过引入一种新的二次型的有限和不等式,采用参数依赖型Lyapunov泛函,导出了适用于具有凸多面体不确定性离散时滞系统的一个新的时滞相关稳定性条件．该方法不需要进行系统模型变换即可得到时滞相关的结果,和已有文献相比,所得结果具有更小的保守性．数值例子说明了该方法的有效性．     

A delay-dependent passivity criterion of linear neutral delay systems

The problem of delay-dependent stability and passivity for linear neutral systems is discussed. By constructing a novel type Lyapunov-krasovskii functional, a new delay-dependent passivity criterion is presented in terms of linear matrix inequalities （LMIs）. Model transformation, bounding for cross terms and selecting free weighting matrices [12-14] are not required in the arguments. Numerical examples show that the proposed criteria are available and less conservative than existing results .     

New delay-dependent absolute stability criteria for Lur'e systems with time-varying delay

In this article, the absolute stability problem is investigated for Lur'e systems with time-varying delay and sector-bounded nonlinearity. By employing the delay fractioning idea, the new augmented Lyapunov functional is first constructed. Then, by introducing some slack matrices and by reserving the useful term when estimating the upper bound of the derivative of Lyapunov functional, the new delay-dependent absolute stability criteria are derived in terms of linear matrix inequalities. Several numerical examples are presented to show the effectiveness and the less conservativeness of the proposed method.