Robust H-infinity estimation for continuous-time polytopic uncertain systems

The design of full_order robust H_infinity estimators is investigated for continuous_time polytopic uncertain systems. The main purpose is to obtain a stable and proper linear estimator such that the estimation error system remains robustly stable with a prescribed H_infinity attenuation level. Based on a recently proposed H_infinity performance criterion which exhibits a kind of decoupling between the Lyapunov matrix and the system dynamic matrices, a sufficient condition for the existence of the robust estimator is provided in terms of linear matrix inequalities. It is shown that the proposed design strategy allows the use of parameter_dependent Lyapunov functions and hence it is less conservative than earlier results. A numerical example is employed to illustrate the feasibility and advantage of the proposed design.     

Robust H-infinity filter for a class of polytopic Delta operator systems

This study deals with the robust H-infinity filtering for a class of Delta operator systems with polytopic uncertainties. By the aid of introducing two slack matrices to eliminate the coupling between systems matrices and Lyapunov matrices, an improved version of the bounded real lemma is given via linear matrix inequality formulation, which shows a close correspondence between the continuous-and discrete-time H-infinity performance criterion. Based on it, the existence condition of the desired filter is obtained such that the corresponding filtering error system is asymptotically stable with a guaranteed performance index. A numerical example is employed to illustrate the feasibility and advantages of the proposed design.     

不确定关联时滞系统的鲁棒H∞滤波

考虑一类不确定关联时滞系统,其中的不确定性满足范数有界条件,以子系统输出作为输入,分别为每个子系统设计一个线性滤波器.通过将系统的状态向量和滤波误差向量组合成一个新的增广向量,原系统状态方程和滤波误差方程就可以组成一个新的增广系统.如果可以设计滤波器参数,使得干扰噪声到增广系统输出的增益为最小,则噪声对系统估计的影响也就降为最低,受噪声影响的状态向量就可以恢复出来.这样,原系统的滤波问题就转化为最小化增广系统增益问题.通过选择一个适当的Lyapunov函数,并基于Lyapunov稳定性定理,得到了滤波器存在的充分条件.为了简化滤波器设计过程,将上述充分条件的未知参数矩阵定义为一个新的变换矩阵,在此基础上,实施了一系列巧妙的矩阵等价变换,同时定义了几个新的矩阵变量,将原充分条件化成了一组易于求解的线性矩阵不等式(LMI).使用Matlab的LMI工具箱,可以对上述LMIs直接求解,最后的数值算例验证了所给设计方法的有效性.     

随机不确定系统的鲁棒H∞ 滤波

研究在同时具有参数和随机不确定的情况下的鲁棒H_∞ 估计问题. 假设系统的方程由It^o随机微分方程描述, 不确定的参数是范数有界的, 外部干扰是随机不确定的. 通过解一个线性矩阵不等式, 可以设计鲁棒H_∞ 滤波器, 最后给出的一个例子对理论分析进行了阐述.     

不确定脉冲系统的鲁棒H∞控制

首次提出并研究了不确定脉冲系统的鲁棒H_∞控制问题. 基于代数Riccati方程正定矩阵解的存在性, 建立了不确定脉冲闭环系统具有鲁棒H_∞特性的充分性准则, 同时给出了相应的状态反馈控制设计方法, 并用数值例子说明了所得结果的有效性.     

不确定性奇异时滞系统的鲁棒H∞控制

研究了含不确定性线性奇异滞后系统的鲁棒H_∞控制问题.其中不确定性是范数有界的.为此首先给出了相应的无控制标称系统内稳定且满足H_∞范数界的一个充分条件.然后讨论了含不确定性奇异滞后系统鲁棒H_∞控制问题有解的一个充分条件,并同时给出了控制器的设计,控制器可由线性矩阵不等式解得.最后举例说明本文方法的正确性.     

An ellipsoidal off-line MPC scheme for uncertain polytopic discrete-time systems

An off-line Model Predictive Control (MPC) method based on ellipsoidal calculus and viability theory is described in order to address control problems in the presence of state and input constraints for uncertain polytopic linear plants subject to persistent disturbances. In order to reduce the computational burdens and conservativeness of traditional polytopic MPC schemes, the present approach carries out off-line most of the computations and it makes use of closed-loop predictions to improve the control performance. This is done by recursively pre-computing suitable ellipsoidal inner approximations of the exact controllable sets and solving on-line a simple and numerically low-demanding optimization problem subject to a set-membership constraint. Comparisons with three other recent off-line MPC approaches are also provided in the final example.     

不确定多通道奇异大系统分散鲁棒H∞控制

研究不确定多通道奇异系统的鲁棒分散H_∞控制问题,假定不确定性是时不变、范数有界,且存在于系统和控制输入矩阵中．主要考虑分散H_∞输出反馈控制问题．推导出了使不确定多通道奇异系统能鲁棒稳定且满足一定的性能指标的充分必要条件,没有等式约束的非线性矩阵不等式条件,采用两步同伦法迭代来求解非线性矩阵不等式(NMI),首先,通过逐步对控制器的系数矩阵加上结构限制,计算出当确定性不存在时的标称系统的分散H_∞控制器．然后,逐步改变标称系统分散控制器的系数,计算出不确定性参数存在时的分散鲁棒控制器．在每一阶段,每一次迭代过程中,通过交替固定NMI的一个变量,使NMI转变为线性矩阵不等式(LMI)．数值例子说明了本文提出的方法的有效性．     

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.     

一类变时滞饱和不确定系统鲁棒H∞滤波器设计

研究一类不确定时变时滞饱和系统的H∞滤波器设计问题.该类系统状态方程中含有时变时滞和有界不确定项,输出方程中含有饱和项,系统的噪声信号功率有界但统计特性未知.本文给出一种线性滤波器结构,提出一种新的设计方法.该方法主要应用Lyapunov-Krasovskii稳定性理论和线性矩阵不等式,来分析和设计滤波器;它能使得时变时滞项,饱和项以及不确定项在设计中得到有效处理,且所设计的滤波器能满足H∞性能指标,滤波器参数通过求解一种线性矩阵不等式来确定.例子的分析与仿真验证了本文方法的有效性.     

具有状态和测量时滞不确定系统的鲁棒H∞状态估计

考虑一类已知状态和测量时滞且范数有界参数不确定连续时间系统的鲁棒H_∞状态估计问题. 这个问题解的充分条件由二个代数Riccati不等式给出, 它可以保证存在一个渐近稳定状态估计器使得对于所有不确定性从外界干扰到输出估计误差的传递函数满足指定的H_∞指标. 以上这些结果可以推广到一类未知状态和测量时滞且范数有界参数不确定连续系统的鲁棒H_∞状态估计问题, 对于已知状态和测量时滞系统, 所得状态估计器与参数不确定性无关, 而与时滞有关. 对于未知状态和测量时滞系统, 其状态估计器不仅与参数不确定性无关, 而且与时滞也无关.     

一类多通道不确定时滞大系统分散鲁棒H∞控制：LMI方法

研究多通道不确定时滞大系统的鲁棒分散H_∞控制问题. 假定不确定性是时不变、范数有界, 且存在于系统、时滞和输出矩阵中. 主要针对动态输出反馈控制问题. 基于Lyapunov稳定性理论, 通过设定Lyapunov矩阵为合适的块对角结构, 采用矩阵替换的方法推导出了使多通道不确定时滞大系统可鲁棒镇定, 且满足一定的扰动水平的时滞依赖充分条件即线性矩阵不等式(LMI) 有可行解, 并且给出了具有期望阶数的分散鲁棒控制器的设计方法. 数值例子说明了本文提出方法的有效性.     

Robust H-infinity control of uncertain stochastic time-delay linear repetitive processes

Repetitive processes are a distinct class of 2D systems of both theoretic and practical interest. The robust H-infinity control problem for uncertain stochastic time-delay linear continuous repetitive processes is investigated in this paper. First, sufficient conditions are proposed in terms of stochastic Lyapunov stability theory, Itˆo differential rule and linear matrix inequality technology. The corresponding controller design is then cast into a convex optimization problem. Attention is focused on constructing an admissible controller, which guarantees that the closed-loop repetitive processes are mean-square asymptotically stable and have a prespecified H-infinity performance γ with respect to all energy-bounded input signals. A numerical example illustrates the effectiveness of the proposed design scheme.     

Robust control of polytopic systems by convex optimization

Robust control synthesis of linear time-invariant SISO polytopic systems is investigated using the polynomial approach. A convex set of all stabilizing controllers for a polytopic system is given over an infinite-dimensional space. A finite-dimensional approximation of this set is obtained using the orthonormal basis functions and represented by a set of LMIs thanks to the KYP lemma. Then, an LMI based convex optimization problem for robust pole placement with sensitivity function shaping in two- and infinity-norm is proposed. The simulation results show the effectiveness of the proposed method.     

Robust H-infinity filtering on uncertain systems under sampled measurements

This paper is concerned with the problem of robust H-infinity filtering on uncertain systems under sampled measurements, both continuous disturbance and discrete disturbance are considered in the systems. The parameter uncer- tainty is assumed to be time-varying norm-bounded. The aim is to design an asymptotically stable filter, using the locally sampled measurements, which ensures both the robust asymptotic stability and a prescribed level of H-infinity performance for the filtering error dynamics for all admissible uncertainties. The derivation process is simplified by introducing auxiliary systems and the sufficient condition for the existence of such a filter is proposed. During the study, the main results were expressed as LMIs by employing various matrix techniques. Using LMI toolbox of Matlab software, it is very convenient to obtain the appropriate filter. Finally, a numerical example shows that the method is effective and feasible.     

Robust H-infinity filtering on uncertain systems under sampled measurements

1 Introduction Sampled measurements systems consist of a continuous- time plant and discrete-time plant. The systems contain sig- nals that evolve in continuous time as well as signals that evolve in discrete time. It is rather difficult to apply the stan- dard analysis results for linear continuous-time systems and discrete-time systems to the analysis of sampled measure- ments systems [1]. This fact has motivated much of the re- search on the analysis and synthesis of sampled measure- ments …     

Robust H-infinity filtering for uncertain discrete-time systems using parameter-dependent Lyapunov functions

This paper deals with H-infinity filtering of discrete-time systems with polytopic uncertainties. The un- certain parameters are supposed to reside in a polytope. By using the parameter-dependent Lyapunov function approach and introducing some slack matrix variables, a new sufficient condition for the H-infinity filter design is presented in terms of solutions to a set of linear matrix inequalities (LMIs). In contrast to the existing results for H-infinity filter design, the main advantage of the proposed design method is the reduced conservativeness. An example is provided to demonstrate the effectiveness of the proposed method.