严格正实线性多变量系统的鲁棒性分析及其输出反馈控制

讨论一类线性不确定系统的鲁棒严格正实分析和控制问题，其中各不确定参数矩阵具有线性分式形式，分析了这类系统对所有容许不确定性严格正实的条件，并综合了使闭环内稳且严格正实的动态输出反馈控制器，通过适当地构造增广系统，将这类问题转化为确定系统的严格正实分析和设计，并按增广系统给出了这类不确定系统鲁棒严格正实的充分必要条件以及动态输出反馈鲁棒严格正实控制器的存在条件。     

Frequency domain conditions for strictly positive real functions

Frequency domain conditions for strictly positive real (SPR) functions which appear in literature are often only necessary or only sufficient. This point is raised in [1], [2], where necessary and sufficient conditions in thes-domain are given for a transfer function to be SPR. In this note, the points raised in [1], I2] are clarified further by giving necessary and sufficient conditions in the frequency domain for transfer functions to be SPR. These frequency-domain conditions are easier to test than those given in thes-domain or time domain [1], [2].     

Comments on “strictly positive real transfer functionsrevisited”

In the original paper, by R. Lozano-Leal and S. Joshi (lEEE Trans. Automat. Contr., vol. 35, no. 11, p. 1243-5, 1990), the distinction between weak and strong strictly positive real (SPR) functions was addressed, and the feedback interconnection of a weak SPR system and a passive one was shown to be stable. The purpose of this note is to show that the proof of this lemma is actually incorrect     

Dual approaches to strictly positive real controller synthesis with a performance using linear matrix inequalities

The synthesis of controllers that minimize a performance index subject to a strictly positive real (SPR) constraint is considered. Two controller synthesis methods are presented that are then combined into an iterative algorithm. Each method synthesizes optimal SPR controllers by posing a convex optimization problem where constraints are enforced via linear matrix inequalities. Additionally, each method fixes the controller state‐feedback gain matrix and finds an observer gain matrix such that an upper bound on the closed‐loop ‐norm is minimized and the controller is SPR. The first method retools the standard ‐optimal control problem by using a common Lyapunov matrix variable to satisfy both the criteria and the SPR constraint. The second method overcomes bilinear matrix inequality issues associated with the performance and the SPR constraint by employing a completing the square method and an overbounding technique. Both synthesis methods are used within an iterative scheme to find optimal SPR controllers in a sequential manner. Comparison of our synthesis methods to existing methods in the literature is presented. Copyright © 2012 John Wiley & Sons, Ltd.     

Robust strictly positive real synthesis for polynomial families of arbitrary order

1IntroductionTheproblemofestimatingtheparametersofmultiplesinusoidsinnoisehasre-ceivedconsiderableattentioninthepastthirtyyears,andalotofalgorithmshavebeenestablishedtosolvetheproblem.Amongallofthealgorithms,themaximumlikelihood(ML)estimatorisaprominentone[1],andseveralalgorithms,suchasANP[2]andIMP[3,4]arerelatedtoML.ThedrawbackoftheMLestimatorisitshighcomputationalcomplexity,sothealternatingprojection(AP)algorithm[5]wasdevelopedtomakeitsrealtimerealizationpossible.Butthefundamentaldefic…     

A robust model reference adaptive control without strictly positive real condition

This paper considers the model reference adaptive control problem for the system (1) with unmodelled dynamics m n dominated by a small constant k multiplied by a quantity dependent on the input, output and noise. Using bounded external excitation and randomly varying truncation techniques, we give design method of a model reference adaptive controller which is similar to that in Meyn and Brown (1992). It is shown that the closed-loop system is globally stable, the estimation error for parameter contained in the modelled part is of order k, and the closed-loop system under the model reference adaptive control law is suboptimal in the sense of lim sup 1/n n (A m (z) y i+1 - B m (z)z* i - C m (z) w i+1 ) 2 h O( k 2 ) + n 2 b 1 2 while the SPR condition usually used in other papers is replaced by a stability condition.     

Optimal stabilization of linear systems via decentralized outputfeedback

Presents an approach to the optimal stabilization of a linear time-invariant system via decentralized control. The class of controllers considered does not restrict the controller to be finite dimensional or time invariant. In fact, the controller structure proposed can be regarded as a form of time varying sampled data control. The main result of the paper presents a scheme for constructing a collection of decentralized controllers which stabilizes the system and is optimal with respect to a quadratic performance index     

Stabilization of discrete time linear systems by static outputfeedback

This note proposes a systematic approach for the static output feedback control design for discrete time linear systems. It is shown that if the open loop system satisfies some particular structural conditions, a static output feedback gain can be calculated easily, using a formula only involving the original system matrices. Among the conditions the system has to satisfy, the stronger relies on a minimum phase argument. Square and nonsquare systems are considered     

Stabilization of minimum phase nonlinear systems by dynamic outputfeedback

In this paper, the stabilization problem of minimum phase nonlinear systems by dynamic output feedback is investigated. It is shown that if the zero dynamics of an affine nonlinear system is asymptotically stable according to the kth approximation, then the system is stabilizable by dynamic output feedback. The proof is constructive, which provides a method to design the stabilizer. The result is applied to investigating the stabilization problem of the rotating stall in axial flow compressors     

An adaptive actuator failure compensation controller using outputfeedback

An adaptive control scheme using output feedback for output tracking is developed for systems with unknown actuator failures. Such actuator failures are characterized by some unknown inputs stuck at some unknown fixed values at unknown time instants. An effective output feedback controller structure is proposed for actuator failure compensation. When implemented with true matching parameters, the controller achieves desired plant-model output matching. When implemented with adaptive parameter estimates, the controller achieves asymptotic output tracking. A stable adaptive law is derived for parameter adaptation in the presence of parameter uncertainties. Closed-loop signal boundedness and asymptotic output tracking, despite the uncertainties in actuator failures and plant parameters, are ensured analytically and verified by simulation results     

基于LM I 的广义系统正实反馈控制

建立连续情形广义系统新的正实引理，通过对线性矩阵不等式(LMI)的求解和系统的等价变换，给出了正实状态反馈控制的充分必要条件，构造了保持系统稳定性的正实控制器设计方法，数值实例表明，该求解控制器的方法简单方便，具有实际意义。     

Pole assignment for linear periodic systems by memoryless outputfeedback

We consider linear periodic discrete-time systems. We are interested in the problem of placing the poles of the monodromy map by means of periodic output feedback of the same or multiple period. It is well known that, in general, the poles of time-invariant systems cannot be assigned by constant output feedback. This is in contrast with what can be obtained in the context of time-variant systems. The main contribution of this paper is that periodic output feedback suffices for pole placement of periodic systems     

Singular perturbation of strictly positive realness

The robustness of the strictly positive real (SPR) condition of linear time-invariant multi-input, multi-output (LTI-MIMO) singularly perturbed systems is examined. A necessary and sufficient condition under which the full system is SPR, is proved. This robustness result is an extension of the analysis for the Popov-Kalman-Yakubovich lemma by V.R. Saksena and P.V. Kokotovic [7].     

Finite frequency positive real control for singularly perturbed systems

In this paper, strictly positive real control for singularly perturbed systems in (semi)finite frequency ranges is studied. For the general linear systems, necessary and sufficient conditions for the existence of a stabilizing state feedback controller are given based on the generalized KYP lemma, and use the results to study singularly perturbed systems, a composite state feedback controller is constructed, which preserves the stability and positive real property.     

离散广义系统的鲁棒严格正实控制

研究确定的以及具有范数有界不确定性的离散广义系统的严格正实分析和控制问题,首先给出了确定离散广义系统状态反馈扩展严格正实控制器的存在条件和设计方法;然后利用线性矩阵不等式分析了不确定离散广义系统广义二次稳定且扩展严格正实的条件,讨论了状态反馈使闭环系统广义二次稳定且扩展严格正实问题,给出了状态反馈鲁棒扩展严格正实控制器的综合方法;最后通过数值算例说明了所提出方法的有效性．     

Low frequency positive real control for delta operator systems

A strictly positive real control problem for delta operator systems in a low frequency range is presented by using the generalized Kalman–Yakubovic?–Popov lemma. The objective of the strictly positive real control problem is to design a controller such that the transfer function is strictly positive real and the resulting closed-loop system is stable. Sufficient conditions for the low frequency strictly positive real controller of the closed-loop delta operator systems are presented in terms of solutions to a set of linear matrix inequalities. A numerical example is given to illustrate the effectiveness and potential for the developed techniques.     

Consensus of positive real systems cascaded with a single integrator

We study output consensus in a network of interconnected non‐identical positive real systems cascaded with a single integrator. Assuming undirected, diffusive interconnections, sufficient conditions are provided to ensure output consensus for two cases: (i) the individual systems are weakly strictly positive real systems cascaded with a single integrator, and (ii) the individual systems are positive real systems cascaded with a single integrator. We illustrate our results with the example of a load frequency control network of synchronous generators. Copyright © 2013 John Wiley & Sons, Ltd.     

Non-fragile positive real control for uncertain linear neutral delay systems

This paper is concerned with the problem of non-fragile positive real control for uncertain neutral delay systems with time-invariant norm-bounded parameter uncertainty. Time delays are assumed to appear in both the state and the controlled output equations. The state feedback gains are with norm-bounded controller uncertainties. For both the cases with additive and multiplicative controller uncertainties, we address the problem of designing memoryless state feedback controllers such that, for all admissible uncertainties, the resulting closed-loop system is stable and the closed-loop transfer function is extended strictly positive real. Sufficient conditions for the existence of desired controllers are given in terms of linear matrix inequalities (LMIs). When these LMIs are feasible, the expected memoryless state feedback controller can be easily constructed via convex optimization. An illustrative example is given to demonstrate the validity and applicability of the proposed approach.