Composite nonlinear feedback control for output regulation problem of linear discrete-time systems with input saturation

Transient performance for output regulation problems of linear discrete-time systems with input saturation is addressed by using the composite nonlinear feedback（CNF） control technique. The regulator is designed to be an additive combination of a linear regulator part and a nonlinear feedback part. The linear regulator part solves the regulation problem independently which produces a quick output response but large oscillations. The nonlinear feedback part with well-tuned parameters is introduced to improve the transient performance by smoothing the oscillatory convergence. It is shown that the introduction of the nonlinear feedback part does not change the solvability conditions of the linear discrete-time output regulation problem. The effectiveness of transient improvement is illustrated by a numeric example.     

Risk-sensitive fixed-point smoothing estimation for linear discrete-time systems with multiple output delays

This paper investigates the risk-sensitive fixed-point smoothing estimation for linear discrete-time systems with multiple time-delay measurements. The problem considered can be converted into an optimization one in indefinite space. Then the risk-sensitive fixed-point smoother is obtained by solving the optimization problem via innovation analysis theory in indefinite space. Necessary and sufficient conditions guaranteeing the existence of the risk-sensitive smoother are also given when the risk-sensitive parameter is negative. Compared with the conventional approach, a significant advantage of presented approach is that it provides less computational cost.     

Robust predictive control of polytopic uncertain systems with both state and input delays

A robust model predictive control algorithm for discrete linear systems with both state and input delays subjected to constrained input control is presented,where the polytopic uncertainties exist in both state matrices and input matrices.The algorithm optimizes an upper bound with respect to a state feedback control law.The feedback control law is presented based on the construction of a parameter-dependent Lyapunov function.The above optimization problem can be formulated as a LMI-based optimization.The feasibility of the optimization problem guarantees that the algorithm is robustly stable.The simulation results verify the effectiveness of the proposed algorithm.     

Robust passive control for discrete-time T-S fuzzy systems with delays

This article deals with the robust stability analysis and passivity of uncertain discrete-time Takagi-Sugeno (T-S) fuzzy systems with time delays. The T-S fuzzy model with parametric uncertainties can approximate nonlinear uncertain systems at any precision. A sufficient condition on the existence of robust passive controller is established based on the Lyapunov stability theory. With the help of linear matrix inequality (LMI) method, robust passive controllers are designed so that the closed-loop system is robust stable and strictly passive.  urthermore, a convex optimization problem with LMI constraints is formulated to design robust passive controllers with the maximum dissipation rate. A numerical example illustrates the validity of the proposed method.     

Robust output regulation problem with prescribed performance for nonlinear strict feedback systems

This paper investigates the problem of robust output regulation control with prospected transient property for strict feedback systems. By employing the internal model principle,the robust output regulation problem with a prospected property can be transformed to a robust stabilization problem with a new output constraint. Then, by constructing the speed function and adopting barrier Lyapunov function technique, the dynamic feedback controller can be designed not only to drive error output of th...     

Robust stability and stabilization for uncertain discrete-time switched singular systems with time-varying delays

The problems of robust stability and stabilization via memoryless state feedback for a class of discrete-time switched singular systems with time-varying delays and linear fractional uncertainties are investigated. By constructing a novel switched Lyapunov–Krasovskii functional, a delay-dependent criterion for the unforced system to be regular, causal and uniformly asymptotically stable is established in terms of linear matrix inequalities (LMIs). An explicit expression for the desired memoryless state feedback stabilization controller is also given. The merits of the proposed criteria lie in their less conservativeness and relative simplicity, which are achieved by considering additionally useful terms (ignored in previous methods) when estimating the upper bound of the forward difference of the Lyapunov–Krasovskii functional and by avoiding utilizing any model augmentation transformation. Some numerical examples are provided to illustrate the validity of the proposed methods.     

执行器饱和离散时间线性系统鲁棒稳定性

针对含执行器饱和离散时间线性参数依赖系统,分别采用独立的、仅参数依赖、同时参数和饱和依赖的二次李亚普诺夫函数方法去估计其不变吸引域,分别导出系统有着不变吸引椭球的以线性矩阵不等式(LMIs)表述的充分性条件。为得到保守性小的估计,分别提出了以上述LMIs作约束的相应优化算法。最后,算例显示同时参数和饱和依赖李亚普诺夫函数处理法所得结果的保守性较之其它两法要小。     

具有控制约束的不确定离散系统最优保性能控制

对一类具有范数有界时变参数不确定性和控制输入约束的离散时间线性系统,采用线性矩阵不等式处理方法,导出了保性能控制律存在的条件,证明了该条件等价于一组线性矩阵不等式的可行性问题,并用这组线性矩阵不等式的可行解给出了保性能控制律的一个参数化表示。进而,通过建立并求解一个凸优化问题,给出了具有控制约束的不确定离散系统最优保性能控制律设计方法。     

Robust H∞ output feedback controller design for uncertain discrete-time switched systems via switched Lyapunov functions

The H∞ output feedback control problem for uncertain discrete-time switched systems is reasearched. A new characterization of stability and H∞ performance for the switched system under arbitrary switching is obtained by using switched Lyapunov function.Then,based on the characterization,a linear matrix inequality (LMI)approach is developed to design a switched output feedback controller which guarantees the stability and H∞ performance of the closed-loop system.A numerical example is presented to demonstrate the application of the proposed method.     

Guaranteed cost control for discrete-time networked control systems with random Markov delays

The guaranteed cost control for a class of uncertain discrete-time networked control systems with random delays is addressed.The sensor-to-controller (S-C) and contraller-to-actuator (C-A) random network-induced delays are modeled as two Markov chains.The focus is on the design of a two-mode-dependent guaranteed cost controller,which depends on both the current S-C delay and the most recently available C-A delay.The resulting closed-loop systems are special jump linear systems.Sufficient conditions for existence of guaranteed cost controller and an upper bound of cost function are established based on stochastic Lyapunov-Krasovakii functions and linear matrix inequality (LMI) approach.A simulation example illustrates the effectiveness of the proposed method.     

T-S模糊时滞系统的鲁棒无源控制

基于Lyapunov稳定性理论,时具有参数不确定性的T-S模糊时滞系统的鲁棒稳定性和无源性进行了研究.具有参数不确定性的T-S模糊模型可以任意精度近似连续非线性不确定系统.假设系统中的参数不确定性是范数有界的.运用Lyapunov稳定性理论给出了鲁棒无源控制器存在的充分条件.通过解一组线性矩阵不等式(LMIs),可直接获得鲁棒无源控制器.所设计的鲁棒无源控制器能够保证对于T-S模糊时滞系统中所有的参数不确定性,闭环系统都是鲁棒稳定的并且是严格无源的.并且,通过求解带有约束条件的线性矩阵不等式问题,可以设计出具有最大耗散率的鲁棒无源控制器.数值例子验证了所提出设计方法的有效性.     

非线性扰动离散广义时滞系统的鲁棒H∞控制

研究了扰动是满足Lipschitz条件的一类非线性离散广义时滞系统的鲁棒H_∞控制和鲁棒H_∞保性能控制问题。目的是设计系统的鲁棒H_∞控制器和鲁棒H_∞保性能控制器。应用线性矩阵不等式方法,分别给出了系统的鲁棒H_∞控制器和鲁棒H_∞保性能控制器存在的充分条件;并在这些条件可解时,分别给出了鲁棒H_∞控制器和鲁棒H_∞保性能控制器的表达式。最后用例子说明了所给方法的应用。     

Global input-to-state stabilization with quantized feedback for discrete-time piecewise affine systems with time delays

In this paper, global input-to-state stabilization with quantized feedback for discrete-time piecewise affine systems （PWA） with time delays are considered. Both feedback with time delays and feedback without time delays are considered. Piecewise quadratic ISS-Lyapunov functions are adopted. Both Lyapunov-Razumikhin and Lyapunov-Krasovskii methods are adopted. The theorems for global input-to-state stabilization with quantized feedback of discrete PWA systems with time delays are     

Robust reliable H∞ control for discrete-time Markov jump linear systems with actuator failures

The robust reliable H∞ control problem for discrete-time Markovian jump systems with actuator failures is studied. A more practical model of actuator failures than outage is considered. Based on the state feedback method, the resulting closed-loop systems are reliable in that they remain robust stochastically stable and satisfy a certain level of H∞ disturbance attenuation not only when all actuators are operational, but also in case of some actuator failures, The solvability condition of controllers can be equivalent to a feasibility problem of coupled linear matrix inequalities （LMIs）. A numerical example is also given to illustrate the design procedures and their effectiveness.     

不确定模糊时滞系统的鲁棒H∞滤波

研究了一类带有时滞的不确定离散时间模糊系统的鲁棒H∞滤波问题。模糊H∞滤波器的设计建立在T-S模糊模型上并能确保滤波误差系统的渐近稳定和给定的H∞性能指标。考虑了时滞的存在使得滤波器有更小的保守性,由线性矩阵不等式（LMI）给出滤波器存在的充分条件。最后,仿真算例验证了给出方法的有效性。     

线性不确定多时滞系统的稳定性新判据

针对线性不确定多时滞系统,建立了一个新的时滞无关稳定性充分条件的结果。根据谱半径相关理论,通过频域法,在只要求系统矩阵A为Hurwitz矩阵的条件下,得到了线性不确定多时滞系统的稳定性新判据。最后,通过两个数值示例与已有文献中的结果进行比较,说明了该结果的有效性。     

Robust stability analysis of uncertain discrete-time systems with state delay

The sufficient conditions of stability for uncertain discrete-time systems with state delay have been proposed by some researchers in the past few years, yet these results may be conservative in application. The stability analysis of these systems is discussed, and the necessary and sufficient condition of stability is derived by method other than constructing Lyapunov function and solving Riccati inequality. The root locations of system characteristic polynomial, which is obtained by augmentation approach and Laplace expansion, determine the stability of uncertain discrete-time systems with state delay, the system is stable if and only if all roots lie within the unit circle. In order to analyze robust stability of system characteristic polynomial effectively, Kharitonov theorem and edge theorem are applied. Example shows the practicability of these methods.     

离散饱和线性反馈系统的分析设计

研究了状态反馈控制饱和单输入离散系统和动态输出反馈单输出饱和离散系统的稳定性，给出了这两类系统是全局渐近稳定还是区域渐近稳定的充分性条件，且对区域渐近稳定的情况计算其不变吸引椭球，对控制饱和系统，运用Ricatti方程迭代法设计控制器以使所得椭球尽量大；最后用算例说明方法的有效性．     

Robust H∞ filtering for discrete-time systems with Markovian switching and time-delays

The robust H∞ filtering problem for uncertain discrete-time Markovian jump linear systems with modedependent time-delays is investigated. Attention is focused on designing a Markovian jump linear filter that ensures robust stochastic stability while achieving a prescribed H∞ performance level of the resulting filtering error system, for all admissible uncertainties. The key features of the approach include the introduction of a new type of stochastic Lyapunov functional and some free weighting matrix variables. Sufficient conditions for the solvability of this problem are obtained in terms of a set of linear matrix inequalities. Numerical examples are provided to demonstrate the reduced conservatism of the proposed approach.     

Sufficient conditions for stability of linear time-delay systems with dependent delays

According to the delay property, linear time-delay （LTD） systems can be classified as LTD systems with depen- dent delays （LTD_DD） and LTD systems with independent delays （LTD_ID）. This paper reveals that the stability condition for LTD_ID systems can be applied to LTD_DD systems, a sufficient stability condition for LTD_DD systems is derived from it, while only fewer of the LTD_DD systems can satisfy the stability condition due to the very strict limitation for the delays of the LTD_DD systems. To solve the problem, based on two-dimensional （2-D） hybrid polynomials, some sufficient conditions for stability of LTD_DD systems are pro- posed. Examples show that the proposed stability test algorithms are simple and valid.