约束不确定非线性系统的鲁棒优化镇定

针对状态和输入约束不确定非线性仿射系统,提出一种鲁棒镇定的优化控制器设计方法.基于弱鲁棒控制Lyapunov函数概念,构造一个参数可调控制器.再利用LaSalle定理和逆优化理论,验证该控制器的鲁棒镇定性和逆最优性.进一步,采用滚动优化原理在线计算控制器的可调参数,实现闭环系统的鲁棒优化镇定.最后对一个开环不稳定振荡器系统进行鲁棒优化镇定,其结果验证了文中方法的有效性.     

球形对象族的最优鲁棒镇定

本文对球形对象族系统最优鲁棒镇定问题进行了研究.利用最小范数解方法求解球形对象族的可镇定性半径.可镇定性半径是系统稳定性半径的上界,最优控制器的稳定性半径等于镇定性半径.文中给出球形对象族最优鲁棒控制器的形式,并通过示例具体说明球形对象族最优鲁棒控制器的设计方法.     

一类具有凸多面体不确定性的非线性变参数系统鲁棒H_(∞)控制EI北大核心CSCD

针对具凸多面体不确定性的非线性变参数(NPV)系统,本文研究了其非线性鲁棒H_(∞)控制问题.基于Lya-punov稳定性理论和多项式平方和(SOS)方法,对该系统设计了非线性鲁棒状态反馈镇定控制器.在此基础上,进一步考虑存在外部扰动情形,给出相应的非线性鲁棒H_(∞)控制可解性条件.该条件以状态和时变参数依赖的线性矩阵不等式形式(LMIs)给出,可借助凸优化工具进行有效检验.最后,通过数值仿真验证了所得方法的有效性和优势.     

一类具有非线性不确定性的时滞系统鲁棒控制

研究一类具有非线性不确定参数以及状态滞后线性系统的时滞依赖鲁棒稳定性判据和鲁棒镇定问题。提出了新的鲁棒可镇定判据和相应的鲁棒无记忆状态反馈控制器设计方法,导出的时滞依赖结果以线性矩阵不等式的形式给出。     

执行器失效不确定时滞系统的指定衰减度鲁棒可靠控制

针对一类含有时变时滞的不确定参数线性系统,研究了在执行器发生故障情况下的鲁棒可靠控制器设计问题.系统中的参数不确定性满足广义匹配条件,时变时滞的大小及其变化率有界,并假设故障执行器元件的输出为零.经过适当的模型变换,将原系统的鲁棒指数镇定问题转化为另一个等价系统的鲁棒镇定问题.根据Lyapunov稳定性理论和线性矩阵不等式(LMI)方法,分别给出了鲁棒可靠控制器存在的时滞无关和时滞相关充分条件.仿真结果表明了该控制器设计方法的有效性.     

时变线性系统同时强镇定控制器设计

在套代数框架下, 应用素分解的方法, 设计能同时强镇定两个时变线性系统的稳定控制器, 并给出了所有控制器的参数化. 应用该控制器参数化, 对某类同时鲁棒强镇定问题进行研究, 给出了两个时变线性系统可被同时强鲁棒镇定的充分条件. 针对所得的控制器设计结果给出了数值例子, 数值结果表明了该设计是有效和可行的.

     

不确定时滞系统鲁棒镇定的优化方法

对一类含有时滞不确定的线性系统,考虑了鲁棒镇定问题。系统中的不确定性假设满足范数有界备件,通过用改进的Razmikhin-type定理,给出了鲁棒镇定控制器存在的充分条件。通过对Lyapunov矩阵方程的完全参数化求解,得到了鲁棒镇定控制器的参数化形式,鲁棒镇定问题转化为一类优化问题。基于这一条件与参数化特征结构配置结果,得到了状态反馈镇定控制器的设计算法。数值例子说明了该方法的有效性。     

鲁棒镇定区间系统族的一个充分条件

讨论了区间系统族的鲁棒镇定问题,给出存在控制器鲁棒镇定区间系统族的一个充分条 件,并且当这个条件成立时,得到了鲁棒镇定区间系统族的控制器的参数化公式.     

不确定模糊Delta算子系统的鲁棒H∞控制

研究了一类T-S模糊Delta算子系统的鲁棒H_∞控制问题.首先利用LMI形式给出了模糊Delta算子系统鲁棒镇定的充分条件,然后构造了可使闭环系统鲁棒稳定且对可允许的参数变化满足H_∞性能的状态反馈控制律.本文结果统一了连续与离散模糊系统的鲁棒H_∞镇定设计结论,数值算例说明了方法的可行性.     

带饱和执行器的不确定时滞系统的 鲁棒控制

研究了一类具有饱和执行器约束的不确定时滞系统时滞依赖型无记忆鲁棒控制问题 .所考虑的时滞系统包括时变未知但有界的不确定参数以及状态和控制的时滞项 .文中应用了 Lyapunov定理以及线性矩阵不等式 ( LMI)方法来研究该系统的分析和综合问题 ,导出了一个新的鲁棒可镇定判据和相应的无记忆鲁棒镇定控制律设计方法 .所得的基于一组LMIs的结果是与时滞相关的     

可镇定性可以是参数鲁棒镇定问题的可解性充分条件

This paper deals with the robust stabilization problem for an interval plant family P(s, δ). It is shown that an interval plant may be robustly stabilized by a single controller C(s) if every member plant of P(s, δ) is stabilizable.     

On the stabilizability condition in indirect adaptive control

Many recent studies on overall stability of adaptive control systems require, among other conditions, that the identified model be stabilizable, at least asymptotically. In fact, the usual identification methods do not guarantee this property, in the passive approach (without exciting extra signals), or if the model order is subject to over-estimation. In order to solve this problem, it is shown in this paper that certain classical identification algorithms can be easily modified in order to ensure the above stabilizability condition, without affecting the other properties.     

Quadratic Stabilizability for Polytopic Uncertain Switched Linear Systems via Switched Observer

In this paper, we study a quadratic stabilizability problem via switched observer for uncertain continuous‐time switched linear systems in the sense that the subsystem's matrices are represented as a polytopic linear combination of vertex matrices. Firstly, sufficient conditions for polytopic uncertain continuous‐time switched linear systems to be quadratically stabilizable via state feedback are summarized. Next, sufficient conditions for polytopic uncertain switched linear systems to be quadratically stabilizable via switched observer are given under the assumption that output matrices of subsystems have no uncertainties. Further, a numerical example is also investigated.     

Infinite horizon optimal control of linear discrete time systems with stochastic parameters

The infinite horizon optimal control problem is considered in the general case of linear discrete time systems and quadratic criteria, both with stochastic parameters which are independent with respect to time. A stronger stabilizability property and a weaker observability property than usual for deterministic systems are introduced. It is shown that the infinite horizon problem has a solution if the system has the first property. If in addition the problem has the second property the solution is unique and the control system is stable in the mean square sense. A simple necessary and sufficient condition, explicit in the system matrices, is given for the system to have the stronger stabilizability property. This condition also holds for deterministic systems to be stabilizable in the usual sense. The stronger stabilizability and weaker observability properties coincide with the usual ones if the parameters are deterministic.     

A generalization of Vidyasagar's theorem on stabilizability using state detection

In this paper we generalize the Vidyasagar's well known theorem on the local stabilizability problem of nonlinear systems using state detection [11]. Our purpose is to prove that if a system is weakly detectable and stabilizable by means of a continuous state feedback u = γ(x), for which no differentiability assumption is imposed, then the system is also stabilized by the law u = γ(z), where z is the output of a weak detector for the state x. The result above is applicable to several cases not covered by other works.     

On Asymptotic Stabilizability of Linear Systems With Delayed Input

This paper examines the asymptotic stabilizability of linear systems with delayed input. By explicit construction of stabilizing feedback laws, it is shown that a stabilizable and detectable linear system with an arbitrarily large delay in the input can be asymptotically stabilized by either linear state or output feedback as long as the open-loop system is not exponentially unstable (i.e., all the open-loop poles are on the closed left-half plane). A simple example shows that such results would not be true if the open-loop system is exponentially unstable. It is further shown that such systems, when subject to actuator saturation, are semiglobally asymptotically stabilizable by linear state or output feedback.     

A lattice approach to analysis and synthesis problems

Within a lattice approach, the purpose of this paper is to give general necessary and sufficient conditions for internal stabilizability and for the existence of (weakly) left-/right-/doubly coprime factorizations of multi input multi output linear systems. These results extend the ones recently obtained in [24] for single input single output systems. In particular, combining these results with the one obtained in [3, 13], we prove that every internally stabilizable multidimensional system admits doubly coprime factorizations, solving Lin's conjecture [17, 18].     

A topological result on strong stabilization problem

This note studies the robustness of nonstrong stabilizability. We consider single-input-single-output (SISO) continuous time linear systems under graph topology. A key contribution of this note is to show that there are two classes of nonstrongly stabilizable systems: One which contains plants that can be rendered strongly stabilizable by an arbitrary small perturbation, and the other which contains plants that are inherently nonstrongly stabilizable, even if perturbed. An easily implemented test referred to as weak parity interlacing property, is developed to check in which class a given model lies.     

Nonlinear versus linear control in the robust stabilizability oflinear uncertain systems via fixed-order output feedback

This paper considers the problem of robustly stabilizing an uncertain system via fixed-order output feedback control. This problem is considered by defining a notion of robust stabilizability with a quadratic storage function. This notion is closely related to the notion of quadratic stabilizability. The main result of the paper shows that if an uncertain system is robustly stabilizable with a quadratic storage function via a nonlinear time-varying controller, then it will also be robustly stabilizable with a quadratic storage function via a linear time-invariant controller of the same order     

Robust Stabilizability Verification of Polynomially Uncertain LTI Systems

This paper investigates the stabilizability of uncertain linear time-invariant (LTI) systems via structurally constrained controllers. First, an LTI uncertain system is considered whose state-space matrices depend polynomially on the uncertainty vector, defined over some region. It is shown that if the system is stabilizable by a structurally constrained controller in one point belonging to the region, then it is stabilizable by a controller with the same structure in all points belonging to the region, except for those located on an algebraic variety. Thus, if a system is stabilizable via a constrained controller at the nominal point, then it is almost always stabilizable at any operating point around the nominal model. It is also shown how this algebraic variety (or the dominant subvariety of it) can be computed efficiently. The results obtained in this paper encompass a broad range of the existing results in the literature on robust stability of the LTI systems, in addition to new ones.