分数阶奇异系统容许性的充分必要条件

探讨了阶数在（0,1）区间的分数阶奇异系统的容许性条件. 文中首先给出了正则性,无脉冲性和容许性的定义,然后给出了分数阶奇异系统容许性的充分必要条件,最后通过数值仿真的例子来说明我们给出的容许性条件.     

“分数阶广义系统容许性的充分必要条件”一文评论

《自动化学报》39卷12期的"分数阶奇异系统容许性的充分必要条件"得到了基于线性矩阵不等式的分数阶广义系统容许性充分必要条件.本文给出一个数值反例表明文献[1]中定理1的充分条件结论并不成立, 必要条件也不准确.最后, 给出了修改正确的分数阶广义系统容许性充分必要条件.相比于文献[1]的定理1, 改进后充要条件没有保守性并去除了原文中分数阶广义系统正则性的限制要求.     

Robust admissibility of uncertain switched singular systems

This article investigates the robust admissibility of uncertain discrete-time switched singular systems. First, the admissibility is introduced, by using the switched Lyapunov function, for singular systems. Sufficient conditions for robust admissibility of uncertain switched singular systems are presented in strict linear matrix inequalities formulation. Robust admissibility condition designs for both state feedback and static output control feedback are then derived. Numerical examples are provided to illustrate our approach.     

Robust admissibility of time-varying singular systems with commensurate time delays

This paper addresses the problem of admissibility of time-varying singular systems with commensurate time delays. By introducing a new method to study the convergence of the fast sub-system, an admissibility condition is obtained in terms of linear matrix inequalities, which guarantees the considered time-varying singular delay system to be regular, impulse free and stable. Furthermore, a robust admissibility condition is proposed for the case when the time-varying system matrices admit the usual constant-plus-norm-bounded structure. It is theoretically established that the proposed robust admissibility condition is less conservative than the existing one in the literature. One of the important features of the results is that the inferred admissibility condition coincides with the usual stability condition for state-space delay systems. Moreover, the results are also applicable to the multiple rational delay case.     

Admissibility analysis of linear singular systems via a delta operator method

In this paper, the problem of admissibility analysis is investigated for linear singular systems through a delta operator method. The delta operator model of a linear singular continuous system is set up first for a special case and then generalised to the common case. It is shown that when the sampling period tends to zero, the delta operator model tends to the corresponding singular continuous system. In order to obtain the above delta operator model, we adopt a linear singular discrete model which contains the sampling period instead of the standard discrete one which contains no sampling period in the modeling process. The relation between the admissibility of the two singular discrete models is analysed and it is proved that the admissibility of one singular discrete model is equivalent to that of the other discrete model. Moreover, based on the relation between the discrete and delta operator models, some admissibility conditions are derived for linear singular delta operator systems. A numerical example is also provided to demonstrate the theoretical results in this paper.     

比例导数输出反馈控制器的设计

在研究广义系统的容许性问题时,不难发现脉冲能导致系统状态在初始时间的无限跳跃,这可能摧毁系统,而导数反馈所发挥的作用主要体现在消除脉冲行为的能力更加有效。基于线性矩阵不等式和控制理论,针对带有比例导数项的输出反馈消除广义系统的脉冲行为,研究广义系统的容许性问题。并给出比例导数输出反馈控制器的设计方法。最后用一个数值算例说明该方法的有效性。     

An improved approach to delay-dependent robust stabilization for uncertain singular time-delay systems

In this paper, delay-dependent stability analysis and robust stabilization for uncertain singular time-delay systems are addressed. By using Jensen integral inequality, an improved delay-dependent criterion of admissibility for singular time-delay systems is proposed in terms of linear matrix inequality (LMI). Our new proposed criterion is less conservative and the numerical complexity is smaller than the existing ones. Based on this criterion, a state feedback controller is designed to ensure that the uncertain singular time-delay system is admissible. Finally, three numerical examples are employed to illustrate the effectiveness of the proposed method.     

离散奇异时滞系统时滞依赖稳定性分析与镇定

分别研究了离散奇异时滞系统时滞依赖稳定性分析与镇定问题. 首先给出了一个新的离散奇异时滞系统时滞依赖容许性充分条件. 经过证明, 所提出的方法与现有结论相比, 具有一定的优势. 然后, 运用矩阵理论技巧,设计出状态反馈控制器保证闭环离散奇异时滞系统是容许的. 最后,两个数值例子说明了所用方法的有效性.     

LMI-based robust admissible control for uncertain singular delta operator systems

This paper investigates the problem of state feedback robust admissible control for singular delta operator systems with norm-bounded coefficient matrix uncertainties. A necessary and sufficient condition is derived to ensure the admissibility of the closed-loop singular delta operator system for all allowable uncertainties. Then, by specifying the structure of some matrix variables, the existence condition and explicit expression of a robust admissible controller are obtained in terms of strict linear matrix inequalities. Moreover, from the relation between singular discrete systems and singular delta operator systems, the corresponding results are also presented for uncertain singular discrete systems. Finally, some numerical examples are provided to demonstrate the effectiveness of the results in this paper.     

基于干扰观测器的一类奇异系统H∞控制

提出了一种基于干扰观测器的奇异系统鲁棒H_∞控制方法.外部干扰广泛存在于奇异系统中,为了降低其对系统的影响,设计了一种奇异系统干扰观测器以估计系统干扰.然后给出闭环系统相容的条件,设计一种基于干扰观测器的鲁棒控制器,并基于李雅普诺夫稳定性理论证明了闭环系统的渐近稳定性,通过设计指标函数得到闭环系统具有鲁棒性能的条件.相对于传统鲁棒控制方法,基于干扰观测器的方法降低了系统设计的保守性.最后,通过仿真实验验证了所提出方法的正确性和有效性.     

A new admissibility condition of discrete-time singular systems with time-varying delays

This paper gives a novel delay-dependent admissibility condition of discrete-time singular systems with time-varying delays. For convenience, the time-varying delay is assumed to be the sum of delay lower bound and the integral multiples of a constant delay. Specially, if the constant delay is of unit length, the delay is an interval-like time-varying delay. The proposed admissibility condition is presented and expressed in terms of linear matrix inequality (LMI) by Lyapunov approach. Generally, the uncertainty of time-varying delay would lead to conservatism. In this paper, this critical issue is tackled by accurately estimating the time-varying delay. Consequently, the proposed admissibility condition is less conservative than the existing results, which is demonstrated by a numerical example.     

A Bounded Real Lemma for Discrete‐Time Markovian Jump Singular Systems

This paper presents a bounded real lemma for discrete‐time Markovian jump singular systems. First, a new necessary and sufficient condition is proposed in terms of a strict linear matrix inequality, which guarantees the stochastic admissibility of the unforced Markovian jump singular systems. Then, a bounded real lemma for discrete‐time Markovian jump singular systems is derived. It is also proven that the bounded real lemma can be described by a strict matrix inequality. Finally, a numerical example is provided to illustrate the effectiveness of the proposed theory. The results are more tractable and reliable in numerical computations than existing conditions.     

Robust H∞ sliding mode control for uncertain discrete singular T-S fuzzy Markov jump systems

This paper mainly explored the problem of stability in terms of discrete singular T-S fuzzy Markov jump systems with uncertainties and external disturbances. A new sliding mode controller is proposed for this type of system. Firstly, a common sliding surface that can be shared by all subsystems of discrete singular systems is designed, so the jumping effects could be weakened. Secondly, the proof of stochastic admissibility of the closed-loop dynamic system is provided by deriving the linear matrix inequality (LMI) technique. Thirdly, an appropriate sliding mode control (SMC) law is designed to satisfy the discrete reaching condition. And, finally, a simulation is offered to illustrate the effectiveness of the derived results.     

线性广义系统的鲁棒严格耗散控制

利用线性矩阵不等式(LMI)方法,给出线性广义系统容许且严格耗散的充分必要条件,由此得到状态反馈和动态输出反馈严格耗散控制器的存在条件及设计方法.考虑除E外所有系数矩阵均具有范数有界时变不确定性的广义系统的鲁棒严格耗散控制问题,给出了系统广义二次稳定且严格耗散的充分条件,以及状态反馈和动态输出反馈鲁棒严格耗散控制器的存在条件及构造方法.     

一般广义时变系统的容许性和二次容许性

针对一般广义时变系统, 采用广义Lyapunov 不等式和受限等价变换的分析方法, 提出了一般广义时变系统容许性和二次容许性的概念, 建立了一般广义时变系统的Lyapunov 不等式. 将一般广义时变系统容许性问题转化为求解Lyapunov 不等式问题, 获得了该类系统容许和二次容许的充要条件, 所得结论是广义系统容许性研究成果向一般广义时变系统的自然推广. 最后, 通过数值算例验证了所得结论的有效性.     

广义马氏跳变系统在一般转移速率下的控制器设计

针对转移概率不能精确获得并且部分未知的广义马氏跳变系统, 分别讨论在模态依赖控制器和模态独立控制器条件下的系统镇定问题. 与现有结果相比, 所提研究方法具有较小的保守性, 能够有效地解决实际问题. 首先, 运用自由权矩阵方法, 得到了广义马氏跳变系统在转移速率满足上述一般条件时系统随机容许的充分条件. 在此基础上, 以线性矩阵不等式(Linear matrix inequality, LMI)的形式分别给出了模态依赖和模态独立控制器的求解条件. 最后, 通过数值算例验证设计方法的有效性和优越性.     

Exponential stability of stochastic singular delay systems with general Markovian switchings

In recent years, Markovian jump systems have received much attention. However, there are very few results on the stability of stochastic singular systems with Markovian switching. In this paper, the discussed system is the stochastic singular delay system with general transition rate matrix in terms of uncertain and partially unknown transition rate matrix. The aim is to answer the question whether there are conditions guaranteeing the underlying system having a unique solution and being exponentially admissible simultaneously. The proposed results show that all the features of the underlying system such as time delay, diffusion, and general Markovian switchings play important roles in the system analysis of exponential admissibility. A numerical example is used to demonstrate the effectiveness of the proposed methods. Copyright © 2014 John Wiley & Sons, Ltd.