μ Synthesis Method for Robust Control of Uncertain Nonlinear Systems

μ synthesis method for robust control of uncertain nonlinear systems is propored, which is based on feedback linearization. First, nonlinear systems are linearized as controllable linear systems by I/O linearization,such that uncertain nonlinear systems are expressed as the linear fractional transformations (LFTs) on the generalized linearized plants and uncertainty.Then,linear robust controllers are obtained for the LFTs usingμsynthesis method based on H∞ optimization.Finally,the nonlinear robust controllers are constructed by combining the linear robust controllers and the nonlinear feedback.An example is given to illustrate the design.     

Fault-Tolerant Control for a Class of Uncertain Systems with Actuator Faults

The problem of fault-tolerant controller design for a class of polytopic uncertain systems with actuator faults is studied in this paper. The actuator faults are presented as a more general and practical continuous fault model. Based on the affine quadratic stability (AQS), the stability of the polytopic uncertain system is replaced by the stability at all corners of the polytope. For a wide range of problems including H∞ and mixed H 2 /H∞ controller design, sufficient conditions are derived to guarantee the robust stability and performance of the closed-loop system in both normal and fault cases. In the framework of the linear matrix inequality (LMI) method, an iterative algorithm is developed to reduce conservativeness of the design procedure. The effectiveness of the proposed design is shown through a flight control example.     

H∞ Filter Design for Linear Systems with Delays

This paper focuses on the problem of H∞ filter design for linear delayed systems.A new approach of filter design is proposed by using Lyapunov stability theory together with linear matrix inequality(LMI) approach.Some sufficient conditions for the existence of H∞ filter are established based on the solutions of a set of LMIs.Finally,two examples are given to demonstrate the effectiveness of the proposed method.     

Robust H_∞ Control of Uncertain Linear Systems with Multiple State Delays—LMI Approach

This paper deals with the problem of robust H∞ control for uncertain systems with multiple state delays. The parameter uncertainties are unknown but norm - bounded. An LMI based method is developed for robust H∞ stabilization for a class of uncertain systems with multiple state delays via linear memoryless state feedback control. The resuits depend on the size of the delays and are given in terms of linear matrix inequalities, so they are less con. servative than those of delay - independent.     

Robust H∞ Control of Hamiltonian System with Uncertainty

This paper investigates the robust H∞ problem for a class of generalized forced Hamiltonian systems with uncertainties. The robust L2-gain was proved for the Hamiltonian with a sufficient condition for stable control of multimachine power systems expressed as a matrix algebraic inequality. A similar sufficient condition was then extended to the robust H∞ control of Hamiltonian systems to construct the state feedback H∞ control law. A numerical example is given to verify the validity of the proposed control scheme, which shows the effectiveness and promising application of the method.     

Robust H∞ Filter Design for a Class of Uncertain Linear Systems with Time—delayed Measurement

A robust H∞ approach to filtering for a class of uncertain linear systems with time-delayed measurement is investigated.The parameter uncertainties are described by real time-varying norm-bounded form.A methodology is developed for designing linear filters such that the filtering process remains robustly stable and the transfer function from the disturbance inputs to error state outputs meets the prescribed H∞-bound constraints.The filter can be obtained and parameterized by solving two Riccati equations based on the lemma of robust stability for control system with delay.Simulation example proves the method to be effective and feasible.     

Robust control for uncertain singular systems with time-varying delay

We study the problem of L2-L∞, control for a class of uncertain singular systems with time-delay and norm-bounded parameter uncer- tainties in this paper. A new delay-dependent robust stability criterion is obtained in terms of linear matrix inequalities （LMIs）. Based on this criterion, a state feedback controller is designed to guarantee that the closed-loop system is regular, impulse free and stable with a prescribed L2-L∞ performance satisfied for all admissible parameter uncertainties. A simulation example is included to illustrate the effectiveness of the proposed method.     

Robust Adaptive Neural Control of a Class of MIMO Nonlinear Systems

In this paper we present a robust adaptive control for a class of uncertain continuous time multiple input multiple output (MIMO) nonlinear systems. Multiple multi-layer neural networks are employed to approximate the uncertainty of the nonlinear functions, and robustifying control terms are used to compensate for approximation errors. All parameter adaptive laws and robustifying control terms are derived based on Lyapunov stability analysis so that, under appropriate assumptions, semi-global stability of the closed-loop system is guaranteed, and the tracking error asymptotically converges to zero. Simulations performed on a two-link robot manipulator illustrate the approach and its performance.     

Quantum feedback networks and control: A brief survey

The purpose of this paper is to provide a brief review of some recent developments in quantum feedback networks and control.A quantum feedback network (QFN) is an interconnected system consisting of open quantum systems linked by free fields and/or direct physical couplings.Basic network constructs,including series connections as well as feedback loops,are discussed.The quantum feedback network theory provides a natural framework for analysis and design.Basic properties such as dissipation,stability,passivity and gain of open quantum systems are discussed.Control system design is also discussed,primarily in the context of open linear quantum stochastic systems.The issue of physical realizability is discussed,and explicit criteria for stability,positive real lemma,and bounded real lemma are presented.Finally for linear quantum systems,coherent H∞ and LQG control are described.     

定常非线性系统稳定性条件的研究

We present here a stability condition and its verification methodfor the time-invariant nonlinear system. This stability condition is based on the small gain theorem in regard to L\-2 gain, and its verification method is described by the Nyquist criterion and the modified M-circle set(alike to Popov's criterion). In order to verify the above system stability, we assume the system nonlinear part as a non-linear subsystem with a free parameter q≥0, and focus on the change of some peak value of the relative position between the vector locus of the open loop frequency response characteristic and the modified M-circle set, which may be available for stability analysis and robust design of the control system.     

一类n阶区间系统的鲁棒输出反馈镇定

给出一类n阶区间系统输出反馈控制器的设计方法：首先利用适当选择的正交变换，将一类n阶区高系统的稳定性检验问题转化为较低阶的问题，并给出这类n阶区间系统稳定性判别准则，进一步地将稳定性分析结果应用于这类系统的鲁棒输出反馈控制器的设计。最后通过示例说明本文所给出的方法的有效性和实用性。     

具有短时延和丢包的网络控制系统鲁棒H∞控制

研究了一类具有网络诱导时延和数据包丢失的不确定网络控制系统的鲁棒H∞控制问题.通过增广系统状态,将反馈通道和前向通道均存在短时延和丢包的网络控制系统建模为包含4个子系统的切换系统,基于增广系统模型提出新形式的静态输出反馈控制律.结合时窗丢包率概念与平均驻留时间方法,得到保证闭环网络控制系统鲁棒渐近稳定且满足鲁棒加权H∞性能指标的充分条件.基于线性矩阵不等式处理技巧与锥补线性化算法,给出双通道丢包依赖的变增益输出反馈鲁棒H∞控制器设计步骤.设计实例验证了所提控制方法的有效性.     

离散型模糊鲁棒H∞输出反馈控制器设计

研究了离散系统的模糊鲁棒H∞控制问题.利用分段光滑的李雅普诺夫函数的线性矩阵不等式的可行解给出了静态输出反馈控制器的设计,使得相应的闭环系统内稳定并使从干扰输入到受控输出的L2增益不大于已知给定的指标值.     

广义离散不确定线性系统动态输出反馈鲁棒H_∞控制分析

研究一类具有范数有界参数不确定性广义离散线性系统的鲁棒H∞控制问题.基于线性矩阵不等式和一个线性矩阵等式约束,导出动态输出反馈鲁棒H∞控制器存在的一个充分条件,并指出所需要动态输出反馈鲁棒H∞控制器的过程设计.     

采用反馈的鲁棒系统设计方法

基于多变量系统鲁棒理论和反馈可以减小对象参数变化对输出影响的思想，本提出一种鲁棒系统设计方法和设计内反馈增益矩阵的算法。用该方法对一实际工业对象设计了鲁棒控制系统，结果令人满意。理论分析和实际系统设计结果表明，该方法设计的系统比串联补偿鲁棒设计的系统具有更好的鲁棒稳定性和鲁棒性能。     

基于LMI非线性不确定时变时滞系统鲁棒H∞控制器设计

应用线形矩阵不等式（LMI）方法给出了一类非线性不确定时变时滞系统的鲁棒H∞控制器设计方法。应用Lyapunov稳定性理论得到相应的LM I,通过对其求解得到既能使闭环系统鲁棒稳定又能保证闭环系统鲁棒H∞性能的控制器。     

Delay-dependent robust H∞ control for a class of uncertain switched systems with time delay

For linear switched system with both parameter uncertainties and time delay, a delay-dependent sufficient condition for the existence of a new robust H infinity feedback controller was formulated in nonlinear matrix inequalities solvable by an LMI-based iterative algorithm. Compared with the conventional state-feedback controller, the proposed controller can achieve better robust control performance since the delayed state is utilized as additional feedback information and the parameters of the proposed controllers are changed synchronously with the dynamical characteristic of the system. This design method was also extended to the case where only delayed state is available for the controller. The example of balancing an inverted pendulum on a cart demonstrates the effectiveness and applicability of the proposed design methods.     

静态输出反馈的鲁棒H_∞控制的一种代数方法

对于一类线性连续不确定性系统,基于线性代数的方法,研究了静态输出反馈控制的鲁棒H_∞问题.结果显示:静态输出反馈控制的鲁棒问题的可解性等价于两个修正Riccati的不等式有正定解,并且给出了符合设计要求的允许控制器的解析表达式.     

线性离散系统的非脆弱混合H2/H∞动态输出反馈控制

基于不等式技术研究了线性离散系统的非脆弱混合H2/H∞控制器设计问题.所考虑的控制器具有乘性控制器增益不确定性.设计的动态输出反馈控制器能够保证闭环系统具有渐近稳定性,同时满足混合H2/H∞性能.针对凸多面体结构的不确定线性系统,其结果可推广到鲁棒非脆弱混合H2/H∞控制器的设计当中.最后,通过仿真算例证实了文中所给设计方法的有效性.     

时变采样周期网络控制系统混合H2/H∞动态输出反馈控制

针对网络化控制系统中出现的时变采样周期和时延现象,讨论混合鲁棒H2/H∞控制性能约束下的控制问题。先通过矩阵Jordan变换,将时变采样周期和时延的不确定性转变为系统参数的不确定性,建立离散时间凸多面体不确定系统模型;然后以线性矩阵不等式的形式,构建参数依赖Lyapunov函数,给出保证系统渐近稳定并满足混合鲁棒H2/H∞性能的动态输出反馈控制器存在的充分条件和控制器的具体参数。数值仿真结果表明所设计的控制器能够保持系统渐近稳定。