基于LMI的不确定切换系统鲁棒控制

基于线性矩阵不等式（LMI）方法和凸组合技术,研究一类带有非线性扰动的不确定切换系统的鲁棒镇定问题。在每个子系统均不能镇定的情况下,利用单李雅普诺夫函数方法和多李雅普诺夫函数方法,分别得到不确定切换系统可镇定的充分条件。针对参数不确定性的未知、时变、有界特点,设计出鲁棒状态反馈控制器及相应的切换策略。最后,通过计算机仿真验证所设计方法的正确和有效性。     

不确定变时滞系统的指数稳定

针对一类含有不确定项的时变时滞动力系统,根据李雅普诺夫第二方法,采用线性矩阵不等式(LIM)处理方法,对其指数稳定问题进行了研究。通过构造适当的李雅普诺夫函数,利用积分不等式技术,得到一个不确定时滞相关系统指数稳定的新判据,并将其转化为线性矩阵不等式的形式,从而可以很方便地利用Matlab工具箱求解得到一般动力系统指数稳定的时滞的相关最大上界,最后通过数值例子说明结果的可行性,其结果具有较小的保守性,而且在实际应用有重要意义。     

一类非线性切换时延系统的鲁棒稳定性

本文通过利用平均驻留时间方法,研究一类具有不确定性非线性切换时延系统的指数稳定性问题。给出非切换系统的候选李雅普诺夫函数的衰减估计分析,然后以线性矩阵不等式的形式给出使系统保持指数稳定及鲁棒指数稳定的充分条件,同时也给出了系统状态指数衰减的具体的估计形式。     

离散时滞切换系统的无记忆状态反馈镇定

针对一类子系统为离散时滞系统的切换系统,研究了稳定性与无记忆状态反馈镇定问题．采用多李雅普诺夫函数法,首先以线性矩阵不等式形式给出了在任意切换信号作用下离散时滞切换系统渐进稳定的一个充分性条件;然后给出了系统无记忆状态反馈镇定的控制器设计方案,并将结果推广到不确定离散时滞切换系统;最后用仿真算例验证了所提出设计方案的可行性。     

基于凸多面体方法的时滞和连续系统稳定性分析

针对一类状态向量中含有时滞和的连续系统,研究其时滞相关稳定性问题。利用凸组合方法和积分不等式并构造合适的李雅普诺夫泛函,以线性矩阵不等式形式给出了保证系统稳定的时滞相关充分条件,该线性矩阵不等式形式的系统稳定条件易于验证。由于在对李雅普诺夫泛函求导过程中使用了凸多面体方法,使得所得到的结论具有更小的保守性,仿真算例验证了结论的有效性。     

切换对称组合系统的稳定性

首次提出了切换对称组合系统的概念, 研究了此类系统在任意切换下渐近稳定的条件, 同时分别利用多李雅普诺夫函数方法和单李雅普诺夫函数方法, 给出使切换对称组合系统渐近稳定的切换律, 利用切换对称组合系统的结构特点, 使其切换律的设计条件得到简化.     

存在数据丢包的网络控制系统的控制

将存在数据丢包的网络控制系统描述为跳跃系统。基于一个李雅普诺夫泛函,只需满足4个线性矩阵不等式,便可通过带状态观测的状态反馈控制使闭环系统达到稳定。由于得到的条件不是严格的线性矩阵不等式条件,将不具有严格线性矩阵不等式条件的非凸可行解问题转化为具有严格线性不等式的非线性最小化问题,得到了求解状态反馈控制器增益和状态观测器增益的算法。数值仿真结果验证了该算法的有效性。在所设计的状态反馈控制器的校正作用下,闭环系统的响应是渐近稳定的。     

一类离散时间切换混杂系统鲁棒控制

由于切换规则的存在使得切换混杂控制系统的稳定性研究变得极为复杂,如何针对给定的系统设计适当的控制器和切换规则没有统一的方法.本文考虑一类线性不确定离散时间切换混杂系统的鲁棒二次镇定和渐近镇定问题.利用公共李雅普诺夫函数方法和多李雅普诺夫函数方法,分别设计了切换混杂系统鲁棒状态反馈控制器和鲁棒输出反馈控制器,保证了切换混杂系统的二次稳定性和渐近稳定性.仿真结果验证了所提算法的正确有效性.     

网络环境下切换模糊时滞系统的非脆弱控制

针对一类控制器增益存在摄动的非线性网络切换系统,在系统同时存在随机时变时滞和不确定性的情况下,采用T-S模型建模,研究系统的稳定控制问题。利用平均驻留时间(ADT)法设计系统的切换律及非脆弱状态反馈控制器,并给出网络切换模糊时滞系统指数稳定的平均驻留时间条件。结合李雅普诺夫函数(LKF)法,推导时滞相关的网络切换模糊系统指数稳定的矩阵不等式条件,并将此条件转化为线性矩阵不等式形式。通过数值仿真对比系统在采用ADT法与传统LKF法下的状态曲线,结果表明,ADT法可以使系统收敛速度更快,性能指标更好。     

一类切换广义时滞系统的时滞相关稳定性准则

针对一类切换广义时滞系统的稳定性问题进行了研究．提出了一种新的研究切换广义时滞系统的多Lyapunov泛函,利用Lyapunov稳定性理论和线性矩阵不等式工具,通过引入适当的自由权矩阵,在设定的切换律下,得到了基于严格线性矩阵不等式表示的切换广义时滞系统的时滞相关稳定性条件．进一步通过建立一个具有线性矩阵不等式约束的凸...     

不确定状态滞后线性跳跃系统的时滞相关鲁棒非脆弱H∞控制

讨论了一类具有Markov跳跃参数的不确定混合线性时滞系统的鲁棒非脆弱控制问题.给出了使系统鲁棒随机稳定并具有给定的H∞性能的充分条件.并且通过参数变换和Schur补定理,将已得出的充分条件转化成一系列耦合的线性矩阵不等式形式以便于控制器参数的求解.仿真结果表明了本文提出的鲁棒非脆弱控制方法的有效性.     

On the Kalman–Yakubovich–Popov lemma for discrete-time positive linear systems: a novel simple proof and some related results

Theorems of alternatives on the feasibility of linear matrix inequalities (LMIs) are used in order to provide novel simple proofs for two considered versions of the Kalman–Yakubovich–Popov (KYP) lemma for discrete-time positive linear systems. Two different and novel recursive methods, to determine whether a positive matrix is or is not Schur, are obtained as an application of an existing connection between the strict inequality version of the KYP lemma for single-input single-output (SISO) discrete-time positive linear systems and a Schur matrix condition. Examples are included which provide illustration on these recursive methods.     

Gain-scheduled H∞ control via parameter-dependent Lyapunov functions

Synthesising a gain-scheduled output feedback H_∞ controller via parameter-dependent Lyapunov functions for linear parameter-varying (LPV) plant models involves solving an infinite number of linear matrix inequalities (LMIs). In practice, for affine LPV models, a finite number of LMIs can be achieved using convexifying techniques. This paper proposes an alternative approach to achieve a finite number of LMIs. By simple manipulations on the bounded real lemma inequality, a symmetric matrix polytope inequality can be formed. Hence, the LMIs need only to be evaluated at all vertices of such a symmetric matrix polytope. In addition, a construction technique of the intermediate controller variables is also proposed as an affine matrix-valued function in the polytopic coordinates of the scheduled parameters. Computational results on a numerical example using the approach were compared with those from a multi-convexity approach in order to demonstrate the impacts of the approach on parameter-dependent Lyapunov-based stability and performance analysis. Furthermore, numerical simulation results show the effectiveness of these proposed techniques.     

线性时滞系统的耗散控制

研究了一类线性时滞系统的二次耗散控制问题,基于线性矩阵不等式（LMI）方法导出了耗散控制器存在的充分条件,通过线性矩阵不等式的可行解构造出耗散态状态反馈和动态输出反馈控制律,相应的闭环系统是二次稳定和严格（Q,S,R）耗散的,本文的主要贡献是统一了线性时滞系统现有的H∞控制和无源控制结果。     

时滞耦合和非时滞耦合的奇异复杂动态网络之同步性准则

本文利用李雅普诺夫稳定性理论,对时滞耦合和非时滞耦合的奇异复杂动态网络之同步获得了一些新的充分条件.这些条件均可转化为求解一组线性矩阵不等式(LMI).在降低准则保守性的过程中,本文充分运用了矩阵函数的凸性和自由权重矩阵理论.最后给出了两个数例;与已有文献做了比较,说明本文结论的有效性,以及较低的保守性.     

Exponential stability and exponential stabilization of singularly perturbed stochastic systems with time‐varying delay

In this paper, the problems of exponential stability and exponential stabilization for linear singularly perturbed stochastic systems with time‐varying delay are investigated. First, an appropriate Lyapunov functional is introduced to establish an improved delay‐dependent stability criterion. By applying free‐weighting matrix technique and by equivalently eliminating time‐varying delay through the idea of convex combination, a less conservative sufficient condition for exponential stability in mean square is obtained in terms of ε‐dependent linear matrix inequalities (LMIs). It is shown that if this set of LMIs for ε=0 are feasible then the system is exponentially stable in mean square for sufficiently small ε?0. Furthermore, it is shown that if a certain matrix variable in this set of LMIs is chosen to be a special form and the resulting LMIs are feasible for ε=0, then the system is ε‐uniformly exponentially stable for all sufficiently small ε?0. Based on the stability criteria, an ε‐independent state‐feedback controller that stabilizes the system for sufficiently small ε?0 is derived. Finally, numerical examples are presented, which show our results are effective and useful. Copyright © 2010 John Wiley & Sons, Ltd.     

随机时滞系统的时滞相关无源控制

研究随机时滞系统的时滞相关无源性分析和控制问题. 利用Lyapunov-Krasovskii方法和松弛矩阵方法, 得到时滞相关的无源性条件. 基于该条件设计时滞相关的随机无源控制器. 文中的结果以线性矩阵不等式(Linear matrix inequalities, LMIs)表示, 可以利用标准的凸优化算法进行有效求解. 通过一个数值例子说明本文方法的有效性.     

Delay-dependent Stabilization Conditions of Controlled Positive Continuous-time Systems

The stabilization problem for a class of linear continuous-time systems with time-varying non differentiable delay is solved while imposing positivity in closed-loop. In particular, the synthesis of state-feedback controllers is studied by giving sufficient conditions in terms of linear matrix inequalities(LMIs). The obtained results are then extended to systems with non positive delay matrix by applying a memory controller. The effectiveness of the proposed method is shown by using numerical examples.     

Performance‐oriented quasi‐LPV modeling of nonlinear systems

Polytopic quasi–linear parameter‐varying (quasi‐LPV) models of nonlinear processes allow the usage linear matrix inequalities (LMIs) to guarantee some performance goal on them (in most cases, locally, over a so‐called modeling region). In order to get a finite number of LMIs, nonlinearities are embedded on the convex hull of a finite set of linear models. However, for a given system, the quasi‐LPV representations are not unique, yielding different performance bounds depending on the model choice. To avoid such drawback, earlier literature on the topic used annihilator‐based approaches, which require gridding on the modeling region, and nonconvex BMI conditions for controller synthesis; optimal performance bounds are obtained, but with a huge computational burden. This paper proposes building a model by minimizing the projection of the nonlinearities onto directions, which are deleterious for performance. For a small modeling region, these directions are obtained from LMIs with the linearized model. Additionally, these directions will guide the selection of the polytopic embedding's vertices. The procedure allows gridding‐free LMI controller synthesis, as in standard LPV setups, with a very reduced performance loss with respect to the aforementioned BMI+gridding approaches, at a fraction of the computational cost.     

线性对象的正实控制问题

在时域中考虑线性对象的正实控制(PRC)问题.对于一般的广义对象,在状态空间 中提出了一个基于线性矩阵不等式(LMI)的统一处理PRC问题的方法,指出’PRC问题可解 的充分必要条件是与系统的实现有关的三个LMI可解,并可利用LMI的解构造出所有的正 则PR控制器.此外还提出了降价PR控制器的存在条件并讨论了可行的综合方法.