Regional eigenvalue-clustering robustness analysis for singular systems with both structured and unstructured perturbations

In this paper, under assumptions that the nominal linear singular system is regular and impulse-free, and has all its finite eigenvalues lying inside certain specified regions, a sufficient condition is proposed to preserve the assumed properties when both structured (elemental) and unstructured (norm-bounded) parameter perturbations are added into the nominal singular system. No restriction is imposed on the shapes of the specified regions. The proposed method is applicable to both the continuous-time case and the discrete-time case. When all the finite eigenvalues are just required to locate in the stable region, the proposed criterion will become the stability robustness criterion. For the case that the linear singular system only subjects to structured perturbations, by an illustrated example, the presented sufficient condition is shown to be less conservative than the existing one reported recently in the literature.     

不确定广义系统的圆形区域极点配置

考虑不确定连续或离散广义系统的圆形区域极点配置问题, 目的是设计状态反 馈控制律, 使得闭环系统正则, 无脉冲(连续广义系统情形)或因果(离散广义系统情形), 且 闭环极点位于一给定的圆形区域内. 给出了所期望的状态反馈控制律存在的充分条件及其解 析表达式.     

离散广义系统的鲁棒稳定性

针对具有结构不确定性的离散广义系统,提出了一种新的鲁棒稳定性分析方法;得 到了使所考虑系统鲁棒稳定的条件,该条件保证对所有容许的结构摄动,离散广义系统正则、 因果且稳定;并进一步得到了所考虑系统具有鲁棒极点集的条件.     

Robustness of regional pole placement for uncertain continuous-timeimplicit systems

In this note, under assumptions that the nominal linear implicit system is regular, impulse-free, with all its generalized eigenvalues lying inside some specified regions, sufficient conditions are proposed to preserve the assumed properties when structured perturbations are added into the nominal system. Explicit bounds on perturbations with different structures are given in terms of the spectral radii of some nonnegative matrices     

A simple approach to robust D‐stability analysis for uncertain singular delay systems

This note presents a simple approach to analyze robust D‐stability for uncertain continuous‐time singular systems with state delay and structured uncertainties. Sufficient conditions, which are computationally simple, and need not calculate the eigenvalues of the system, are proposed to ensure that the uncertain continuous‐time singular delay system is regular, impulse free and D‐stable, that is, all its finite poles are located within a specified disk. Two numerical examples are given to demonstrate the application of the proposed method. Copyright © 2009 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society     

AN LMI APPROACH TO ROBUST STABILITY OF UNCERTAIN DISCRETE SINGULAR TIME‐DELAY SYSTEMS

The problem of robust stability analysis for uncertain discrete singular time‐delay systems is investigated in this paper. By decomposing the nominal system into slow and fast subsystems, a linear matrix inequality (LMI) condition is proposed for a discrete singular time‐delay system to be regular, causal and stable. Based on this, an LMI criterion is obtained for robust stability of an uncertain discrete singular time‐delay system. Two numerical examples are provided to demonstrate the feasibility of the proposed approach.     

Robust stability and stabilization of discrete singular systems with interval time-varying delay and linear fractional uncertainty

The robust stability and robust stabilization problems for discrete singular systems with interval time-varying delay and linear fractional uncertainty are discussed. A new delay-dependent criterion is established for the nominal discrete singular delay systems to be regular, causal and stable by employing the linear matrix inequality (LMI) approach. It is shown that the newly proposed criterion can provide less conservative results than some existing ones. Then, with this criterion, the problems of robust stability and robust stabilization for uncertain discrete singular delay systems are solved, and the delay-dependent LMI conditions are obtained. Finally, numerical examples are given to illustrate the e?ectiveness of the proposed approach.     

2-D奇异系统Roesser模型的鲁棒H∞控制

考虑具有参数不确定性的2-D奇异系统Roesser模型(简称2-D SRM)鲁棒H∞控制问题．在给出界实引理的另一等价形式的基础上,通过求解矩阵不等式,给出了不确定2-D奇异系统鲁棒H∞控制问题可解的充分条件及静态状态反馈控制律设计的代数表达式．最后通过一个仿真算例验证了方法的有效性．     

Robust stabilization for uncertain discrete singular systems with state delay

The robust stabilization problem for uncertain discrete singular time‐delay systems is addressed in this paper. In terms of strict linear matrix inequality and a finite sum inequality, a delay‐dependent criterion for the nominal systems to be admissible is obtained. Based on the criterion, a state feedback controller, which guarantees that, for all admissible uncertainties, the resulting closed‐loop system is regular, causal and stable, is constructed. An explicit expression for the desired controller is also given. The obtained results include both delay‐independent and delay‐dependent cases. Some numerical examples are introduced to show the effectiveness of the given results. Copyright © 2008 John Wiley & Sons, Ltd.     

Delay‐dependent robust H∞ controller synthesis for discrete singular delay systems

In this paper, the problems of delay‐dependent robust stability analysis, robust stabilization and robust H_∞ control are investigated for uncertain discrete‐time singular systems with state delay. First, by making use of the delay partitioning technique, a new delay‐dependent criterion is given to ensure the nominal system to be regular, causal and stable. This new criterion is further extended to singular systems with both delay and parameter uncertainties. Then, without the assumption that the considered systems being regular and causal, robust controllers are designed for discrete‐time singular time‐delay systems such that the closed‐loop systems have the characteristics of regularity, causality and asymptotic stability. Moreover, the problem of robust H_∞ control is solved following a similar line. The obtained results are dependent not only on the delay, but also on the partitioning size and the conservatism is non‐increasing with reducing partitioning size. These results are shown, via extensive numerical examples, to be much less conservative than the existing results in the literature. Copyright © 2010 John Wiley & Sons, Ltd.     

具有结构式不确定性线性系统特征根的鲁棒群聚

采用广义Ｌｙａｐｕｎｏｖ方程，讨论具有结构式不确定性线性系统的特征根在复平面上某些区域内的鲁棒群聚性，如果标称矩阵的所有特征根都在复平面上的特定区域内，本文所给出充分条件将保证当存在有结构式不确定性时矩阵的特征根也在同一区域内，所提出的判断比当前文献中的结论具有较少的保守性。     

Pole assignment in a specified circular region using a bilinear transformation onto the unit circle

An algorithm for pole assignment in a specified circular region using a bilinear transformation onto the unit circle is considered, A Lyapunov type test is developed to check that all the eigenvalues of a discrete system are within a circle in the complex plane. Pole placement in a circular region by LQ state feedback design is investigated for discrete linear systems. Perturbation bounds are derived, using bilinear transformation, for all closed-loop poles of a perturbed discrete system to remain inside a specified circular region. Illustrative examples are included     

离散广义区间动力系统的稳定性

利用范数理论,研究离散广义区间动力系统的稳定性问题,给出其区间动力系统的正则、因果且稳定的充分条件.在此基础上,进一步考虑该系统的区间极点集的配置问题,给出了使离散广义区间动力系统的极点落在预先给定园盘内的判定定理.数值算例表明了该方法的可行性.     

Robustness analysis for linear dynamical systems with linearlycorrelated parametric uncertainties

The authors propose an approach for robust pole location analysis of linear dynamical systems with parametric uncertainties. Linear control systems with characteristic polynomials whose coefficients are affine in a vector of uncertain physical parameters are considered. A design region in complex plane for system pole placement and a nominal parameter vector generating a characteristic polynomial with roots in that region are given. The proposed method allows the computation of maximal domains bounded by linear inequalities and centered at the nominal point in system parameter space, preserving system poles in the given region. The solution of this problem is shown to also solve the problem of testing robot location of a given polytope of polynomials in parameter space. It is proved that for stability problems for continuous-time systems with independent perturbations on polynomial coefficients, this method generates the four extreme Kharitonov polynomials     

Non-fragile robust optimal guaranteed cost control of uncertain 2-D discrete state-delayed systems

This paper is concerned with the problem of non-fragile robust optimal guaranteed cost control for a class of uncertain two-dimensional (2-D) discrete state-delayed systems described by the general model with norm-bounded uncertainties. Our attention is focused on the design of non-fragile state feedback controllers such that the resulting closed-loop system is asymptotically stable and the closed-loop cost function value is not more than a specified upper bound for all admissible parameter uncertainties and controller gain variations. A sufficient condition for the existence of such controllers is established under the linear matrix inequality framework. Moreover, a convex optimisation problem is proposed to select a non-fragile robust optimal guaranteed cost controller stabilising the 2-D discrete state-delayed system as well as achieving the least guaranteed cost for the resulting closed-loop system. The proposed method is compared with the previously reported criterion. Finally, illustrative examples are given to show the potential of the proposed technique.     

Time response bounds for linear parametric uncertain systems

Parametric uncertainties in linear time-invariant state-space models introduce perturbations in the eigenvalues and eigenvectors (eigenstructure), which modify the properties of a nominal system. Besides stability by the perturbed eigenvalues, controllability, observability, transient and steady-state values, etc., are some basic properties of a linear system significantly influenced by the perturbed eigenvectors. In this paper, time response analysis of parametric uncertain systems is considered. First the bounds on eigenvectors and parametric uncertainties are established for the perturbed eigenvalues to reside in a set of distinct circular regions. Secondly, analysis of such parametric uncertain systems is discussed by presenting bounds on the perturbed state variables in time coordinate. These bounds are then investigated for norm-bounded and structured uncertainty classifications. Input-output analysis of uncertain systems is illustrated using the initial conditions and input functions.     

具有多输入时滞的不确定广义系统的时滞相关鲁棒镇定

研究具有多输入时滞及参数不确定性的广义系统的时滞相关鲁棒镇定问题. 首先利用LMI给出相应的标称系统的时滞相关镇定准则. 然后, 基于这个准则, 设计状态反馈控制器, 使得对任何允许的不确定参数相应的闭环系统是正则, 稳定, 无脉冲的. 最后的数值算例表明所提方法是有效的.     

Robust sliding mode control for uncertain discrete singular systems with time-varying delays

This paper investigates robust sliding mode control (SMC) for discrete singular systems which include time-varying delays, parameter uncertainties and nonlinear perturbations. An appropriate discrete sliding surface function is constructed such that the corresponding sliding mode dynamics are gained. By using some free-weighting matrices, a linear matrix inequality constraint is established to make sure that the closed-loop system is regular, causal and stable. Furthermore, in consideration of the improved discrete reaching condition, an SMC law is synthesised for reaching motion and the chattering can be weakened, while few existing papers focus on how to employ it to study the SMC problem for the discrete singular systems with time-varying delays. At last, the designed law is tested through an example.     

不确定2-D 奇异系统Roesser 模型 鲁棒能稳的矩阵不等式方法

考虑具有参数不确定性的2-D奇异系统Roesser模型(简称2-D SRM)鲁棒能稳问题．通过静态状态反馈控制律，使得对所有容许的不确定参数，闭环系统容许、稳定、无跳跃模．通过求解矩阵不等式，给出了不确定2-D奇异系统鲁棒能稳问题可解的充分条件及静态状态反馈控制律设计的代数表达式．最后通过算例验证了方法的有效性．     

Parameter bounds for root clustering of uncertain matrices

This paper deals with robust root-clustering in a region of order one or two of the complex plane. We consider continuous or discrete linear state-space models with unstructured and structured perturbations. Some bounds on allowable perturbations that maintain the eigenvalues of a system matrix in a desired region are derived. These bounds are shown to be less conservative than existing ones.