Adaptive Output Feedback based Output Tracking Control for a Time‐Delay System with a PFC

This output tracking control system for time‐delay systems with a parallel feedforward compensator (PFC). It has been clarified that one can design an adaptive output tracking control system for systems with almost strictly positive real (ASPR) properties. However, the robust stability for non‐ASPR time‐delay systems with a PFC introduced for making the resulting augmented system ASPR has not been analyzed. In this paper, it will be clarified that one can design a stable adaptive output tracking control system for time‐delay systems with a PFC, even if the resulting augmented system is not exactly ASPR.     

Output Feedback H∞ Control for Discrete‐time Mean‐field Stochastic Systems

This paper is to consider dynamic output feedback H_∞ control of mean‐field type for stochastic discrete‐time systems with state‐ and disturbance‐dependent noise. A stochastic bounded real lemma (SBRL) of mean‐field type is derived. Based on the SBRL, a sufficient condition with the form of coupled nonlinear matrix inequalities is derived for the existence of a stabilizing H_∞ controller. Moreover, a numerical example is given to examine the effectiveness of the theoretical results.     

Observer‐Based Adaptive Output Feedback Fault Tolerant Control for Nonlinear Hydro‐Turbine Governing System with State Delay

This paper focuses on the problem of adaptive output feedback fault tolerant control for a nonlinear hydro‐turbine governing system. A dynamic mathematical model of the system is established, which aims to investigate the dynamic performance of the model under servomotor delay and actuator faults. Then, a fault estimation adaptive observer is proposed to achieve online real‐time diagnosis of system faults. Based on the online fault estimation information, an observer‐based adaptive output feedback fault tolerant controller is designed. Furthermore, under reasonable assumptions, the results demonstrate that the closed‐loop control system can achieve global asymptotic stability by Lyapunov function. Finally, the numerical simulation results are presented to indicate the satisfaction control effectiveness of the proposed scheme.     

基于输出反馈特征结构配置的重构控制系统设计

推出了一种利用特征结构配置设计重构控制系统的新方法. 当故障后的系统满足m+r-1≥n的条件时, 通过重新设计一输出反馈增益阵, 使重构后的闭环故障系统的特征值全部恢复到故障前的位置, 特征向量也在可配置子空间中尽量接近故障前相应的闭环系统特征向量, 从而使重构后的系统性能最大程度地恢复到故障前的系统性能. 这种方法的优点是重构系统的稳定性可得到保证, 且计算输出反馈增益阵的算法相对简单. 应用实例和仿真结果说明本文方法的有效性.     

Adaptive Dynamic Output Feedback Stabilisation of Nonlinear Systems

An adaptive dynamical output feedback controller is introduced for a class of nonlinear non‐minimum phase systems. This adaptive controller achieves practical stabilisation, that means the output will asymptotically tend to a pre‐specified neighbourhood of the origin. In case of linear systems, we can even prove adaptive stabilisation.     

Robust Adaptive Output‐Feedback Dynamic Surface Control of a Class of Nonlinear Systems with Unmodeled Dynamics

This paper presents a robust adaptive output‐feedback dynamic surface control (DSC) for a class of nonlinear systems with unmodeled dynamics or/and uncertain time‐varying disturbances. Based on traditional K‐filters, the proposed adaptive DSC scheme is able to guarantee semi‐global stability of the closed‐loop system without applying any approximation techniques. The adaptive law is necessary only at the first design step, which, together with the introduction of a first‐order filter at each design step, makes the control law easy to implement. Moreover, it is shown that the tracking error can converge to an arbitrarily small residual set by adjusting only one design parameter.     

一类非线性系统的间接自适应输出反馈模糊控制

针对一类未知非线性系统,提出一种输出反馈控制方法。首先在假设系统状态已知的情况下设计状态反馈控制器,实现跟踪性能。然后在系统状态不完全可测的情况下,通过设计高增益观测器对系统的状态进行估计,实现输出反馈控制器设计。最后证明所设计的输出反馈控制器可获得状态反馈控制器所取得的最大最小问题的跟踪性能。     

鲁棒输出反馈控制系统设计

本文利用文献[10]中提出的线性系统特征结构配置结果和Hellman-Feynman定理,导出了输出反馈系统闭环极点关于开环矩阵中受扰元素灵敏度的参数表达式,并在此基础上给出了具有最小闭环极点灵敏度的输出反馈控制系统设计的一个算法.该算法简单、有效,且具有较好的"最优性".     

一类模糊非线性系统的直接鲁棒自适应输出反馈控制

针对一类未知非线性系统,利用模糊逻辑系统、H^∞控制和高增益观测器,提出一种模糊直接鲁棒自适应输出反馈控制方法。证明了所设计的输出反馈控制方法不但能保证闭环控制系统稳定,而且可获得在状态反馈控制器下的性能。仿真结果进一步验证了所提出方法的有效性。     

Output Feedback Adaptive Neural Control Without Seeking SPR Condition

For output‐feedback adaptive control of affine nonlinear systems based on feedback linearization and function approximation, the observation error dynamics usually should be augmented by a low‐pass filter to satisfy a strictly positive real (SPR) condition so that output feedback can be realized. Yet, this manipulation results in filtering basis functions of approximators, which makes the order of the controller dynamics very large. This paper presents a novel output‐feedback adaptive neural control (ANC) scheme to avoid seeking the SPR condition. A saturated output‐feedback control law is introduced based on a state‐feedback indirect ANC structure. An adaptive neural network (NN) observer is applied to estimate immeasurable system state variables. The output estimation error rather than the basis functions is filtered and the filter output is employed to update NNs. Under given initial conditions and sufficient control parameter constraints, it is proved that the closed‐loop system is uniformly ultimately bounded stable in the sense that both the state estimation errors and the tracking errors converge to small neighborhoods of zero. An illustrative example is provided to demonstrate the effectiveness of this approach.     

Recursive Back‐Stepping Design of An Adaptive Fuzzy Controller for Strict Output Feedback Nonlinear Systems

In this paper, a back‐stepping adaptive fuzzy controller is proposed for strict output feedback nonlinear systems. The unknown nonlinearity and external disturbances of such systems are considered. We assume that only the output of the system is available for measurement. As a result, two filters are constructed to estimate the states of strict output feedback systems. Since fuzzy systems can uniformly approximate nonlinear continuous functions to arbitrary accuracy, the adaptive fuzzy control theory combined with a tuning function scheme is developed to derive the control laws of strict output feedback systems that possess unknown functions. Moreover, the H∞ performance condition is introduced to attenuate the effect of the modeling error and external disturbances. Finally, an example is simulated in order to confirm the applicability of the proposed method.     

基于输出反馈网络化控制系统鲁棒容错控制

研究了一类具有时延不确定性的网络化控制系统的鲁棒容错控制问题.针对以往控制器大多采用状态反馈的形式,而对功能和结构复杂的网络化控制系统全部状态往往难于测取,因而状态反馈形式的控制器在应用中会受到限制,完整性问题的结果也主要基于0-1故障模型.采用动态输出反馈控制策略,针对网络化控制系统的时延和不同步对系统产生的影响,基...     

具有未知参数的机器人-摄像机系统的自适应动态反馈跟踪控制

研究了不确定非完整移动机器人系统的跟踪问题.首先,基于视觉反馈和状态输入变换,展示了一种非完整移动机器人运动学系统的不确定链式模型.基于反步法思想和跟踪误差系统结构,给出了两个重要的新变换.然后运用李雅普诺夫直接方法和扩展巴巴拉引理设计了自适应控制律和动态反馈鲁棒控制器,以实现理想轨迹的跟踪控制.严格证明了闭环误差系统的渐近收敛性.最后,仿真结果证实了提出的控制策略有效.     

Adaptive Output Regulation of a Class of Nonlinear Output Feedback Systems With Unknown High Frequency Gain

This paper presents an output feedback design approach based on the adaptive control scheme developed for nonlinearly parameterized systems, to achieve global output regulation for a class of nonlinear systems in output feedback form. We solve the output regulation problem without the knowledge of the sign and the value of the high frequency gain a priori. It is not necessary to have both the limiting assumptions that the exogenous signal ω and the unknown parameter μ belong to a prior known compact set and the high frequency gain has a determinate lower and upper bounds. The effectiveness of the proposed algorithm is shown with the help of an example.      

双线性系统的静态分散输出控制

研究了一类T-S双线关联系统的静态输出控制反馈问题。应用分散控制理论,得到了闭环关联大系统Lyapunov稳定的充分条件。相应的分散模糊控制器可由线性矩阵不等式(LMD的解得到。最后,由数例仿真验证了所提方法的有效性。     

Adaptive Control of Piecewise Linear Systems with State Feedback for Output Tracking

A piecewise linear system consists of a set of linear time‐invariant (LTI) subsystems, with a switching sequence specifying an active subsystem at each time instant. This paper studies the adaptive control problem of single‐input, single‐output (SISO) piecewise linear systems. By employing the knowledge of the time instant indicator functions of system parameter switches, a new controller structure parametrization is proposed for the development of a stable adaptive control scheme with reduced modeling error in the estimation error signal used for parameter adaptive laws. This key feature is achieved by the new control scheme's ability to avoid a major parameter swapping term in the error model, with the help of indicator functions whose knowledge is available in many applications. A direct state feedback model reference adaptive control (MRAC) scheme is presented for such systems to achieve closed‐loop signal boundedness and small output tracking error in the mean square sense, under the usual slow system parameter switching condition. Simulation results on linearized NASA GTM models are presented to demonstrate the effectiveness of the proposed scheme.     

非线性系统的自适应实用输出跟踪控制

研究了一类具有不可控不稳定线性化和线性化参数的非线性系统的全局自适应实用输出跟踪控制问题,这类系统既不具有反馈线性化性质,对输入也没有仿射特性.因为这类系统的线性化系统具有不可控模式且该模式在右半平面内有根,所以全局渐近输出跟踪是不可能的(甚至是局部的).应用修正的自适应增加幂积分方法,设计了一种光滑状态反馈控制器,保证闭环系统所有信号全局一致最终有界,且使跟踪误差进入零的小邻域内.仿真结果表明该控制器是可行的并且是有效的.     

Dynamic Output Feedback Control for Systems Subject to Actuator Saturation via Event‐Triggered Scheme

In this paper, the event‐triggered dynamic output feedback control problem for linear systems with actuator saturation is investigated. Event‐triggered scheme only transmits the corresponding signal when the event‐triggered condition is violated. Due to its advantage of saving communication resources, it is utilized to design the dynamic output feedback controller. A criterion is established to guarantee the stability of the closed‐loop system by introducing an exponential term for the Lyapunov function, which corresponds to the exponential term in the event‐triggered condition. The explicit design of the coefficient matrices of the controller is presented. Furthermore, a lower bound of the inter‐event time is calculated to avoid Zeno behavior. An optimization algorithm is then formulated to maximize the estimation of the domain of attraction. Finally, a numerical example is given to illustrate the effectiveness of our methods and to show the trade‐off between the size of the domain of attraction and communication resources saving.     

基于故障诊断观测器的输出反馈容错控制设计

针对自适应故障诊断观测器需要误差系统满足苛刻的严格正实条件(Strictly positive real, SPR)和难于处理输出存在扰动的不确定性系统等问题, 提出了一种新型的增广故障诊断观测器的设计方法, 不仅显著地拓宽了自适应故障诊断观测器的适用范围, 而且其具有处理系统扰动的良好性能. 在故障估计的基础上, 提出了动态输出反馈容错控制的设计方法, 避免了基于观测器的状态反馈容错控制的设计难点. 同时, 故障诊断观测器和输出反馈容错控制是分开设计的, 并且又考虑了各自的性能, 简化了设计过程. 最后, 通过仿真实验验证了所提方法的有效性.     

Mixed Event/Time‐Triggered Static Output Feedback L2‐Gain Control for Networked Control Systems

This paper considers the design of mixed event/time‐triggered controllers for networked control systems (NCSs) under transmission delay and possible packet dropout. Assuming that a conventional delayed static output feedback L₂‐gain controller exists, we propose an output‐based mixed event/time‐triggered communication scheme for reducing the network traffic in a NCS. Moreover, we show that a conventional delayed static output feedback L₂‐gain controller can be obtained by solving a linear matrix inequality with a matrix equality constraint. A numerical example is proposed for demonstrating the theoretical results.