一类不确定非线性系统的鲁棒状态观测器设计

本文研究了一类具有参数不确定性的非线性系统鲁棒状态观测器的设计问题。提出了一种新的非线性鲁棒渐近状态观测器设计方案,证明了状态观测误差的指数渐近收敛性。最后将所得结果应用于一轴盘传动系统,仿真结果表明本文提出的设计方案是有效的。     

非线性系统基于降维状态观测器的反馈稳定化设计

本文研究了一类仿射非线性控制系统的反馈稳定化问题。     

一个不确定非线性系统的鲁棒状态观测器设计

本文研究了一类具有参数不确定性的非线性系统鲁棒状态观测器的设计问题。提出了一种新的非线性鲁棒渐近状态观测器设计方案,证明状态观测误差的指数渐近收敛性。最后将所得结果应用于一轴盘传动系统,仿真结果表明本文提出的设计方案是有效的。     

非线性扩张状态观测器的一种设计方法

提出了一种非线性扩张状态观测器的“参数动态确定法”设计方法。运用该方法可以设计出任意的非线性扩张状态观测器,所设计出的非线性扩张状态观测器的动态品质只与补偿矩阵的极点位置有关,与非线性函数的形式无关,选取满足条件的不同非线性函数可以得到不同形式的非线性扩张状态观测器。最后,仿真算例表明了该设计方法的有效性。     

Lipschitz非线性系统观测器设计

运用微分方程方法,讨论了一类满足Ｌｉｐｓｃｈｉｔｚ条件的非线性系统观测器的设计,结论表明,稳定观测器的存在不仅与系统矩阵的特征值有关,而且与矩阵对距离不可观测性的大小有关,给出代数设计方法以条件数量小为目标准则,根据梯度下降法原理,用ＭＡＴＬＡＢ写代码,设计者只须提供初值,程序即自动完成观测器设计,文末咄了释例。     

不确定时滞组合系统基于状态观测器的鲁棒分散可靠控制

研究一类包含状态时滞和参数不确定性的不确定时滞组合系统基于状态观测器的鲁棒分散可靠控制问题。目的是设计分散状态观测器和基于此观测器的线见性动态输出反馈控制器，使得对于任意容许的不确定性以及在每一个子系统中预先指定执行器子集合内执行器的失效，相应的闭环系统渐近稳定。     

基于扩张状态观测器的电力系统非线性鲁棒协调控制

该文提出了一种基于扩张状态观测器的非线性鲁棒协调控制方法(Extended-State-Observer based Nonlinear Robust Coordinated Control，ENRCC）；将电力系统对象归纳为一类内环为非线性系统、外环为伪线性系统的多输入多输出对象。在此基础上，完整地阐述了ENRCC的控制原理；利用一簇低阶扩张状态观测器对内环非线性系统进行动态反馈线性化和解耦设计，利用线性鲁棒控制方法对已线性化的内环系统和外环伪线性系统进行预期动力学设计，最终可实现观测器 线性化 鲁棒协调控制三者的有机结合。实例仿真结果表明：该控制规律严谨简单，方法原理直观清晰，便于工程应用，具有很强的适应性和鲁棒性，能有效地解决一类不确定 非线性 分散性的电力系统多输入多输出(MIMO)对象的控制问题。     

基于非线性状态观测器的无刷电机故障诊断

为了对无刷直流电动机的非线性系统实现快速、精确的故障检测,采用精确的无刷电机非线性系统模型,并应用RBF神经网络,设计了一种非线性状态观测器,通过观测器的估计值与实际输出值之间的残差来判定无刷电机故障与否,并将无刷直流电动机非线性模型在某一工作点附近线性化,采用线性观测器的方法对其进行故障诊断的仿真并与非线性故障诊断方法相比较。结果表明,对于在多工作点工作的无刷直流电机,该方法能获得更精确的故障检测结果。     

一类非线性系统的自适应控制研究

首先针对滑模控制中的高频颤动问题，把模糊神经网络（Fuzzy Neural Networks)用于滑模控制，提出了模糊神经网络滑模控制器（Fuzzy Neural Neural Networks Silding Mode Control)设计方法。由于用模糊神经网络的连续输出替代了滑模控制中的控制信号硬切换，因此FNNSMC能有效地消除颤动且其鲁棒比一般的滑模控制器强，但是其动态上升时间比滑模控制器的大。为解决这个问题，利用滑模控制器（Silding Mode Contrller）具有响应快的特点，在FNNSMC的之上，提出了一种自适应控制方案。该方法由SMC和FNNSMC构成，将SMC与FNNSMC有机结合，通过平滑切换实现自适应控制。我们的边界层内用FNNSMC控制。由于在边界层外SMC不会发生高频颤动现象，而在边界层内FNNSMC能消除颤动。因此文中提出的自适应控制方案不仅能消除颤动而且其动态性能良好。理论分析和仿真结果均说明了所提方法的有效性。     

一类相似组合大系统的全息控制

研究了一类相似组合大系统的全息镇定问题,给出这种系统能用结构全息状态反馈控制分散镇定的条件,并用一个例子验证了本文所给的结果。     

Adaptive observer for a class of nonlinear systems with time‐varying delays

The adaptive observer design problems have been extensively studied in literature for both linear and nonlinear systems. Some researches have also been carried out on adaptive observer design for linear time‐delay systems, but there is no significant work on adaptive observer design for nonlinear time‐delay systems. In this work, the adaptive observer design problem for a class of nonlinear time‐delay systems is considered. The observer is designed for the nonlinear systems whose nonlinear functions satisfy Lipschitz condition. Like conventional adaptive observers for the systems without time delays, this observer also estimates both states and unknown parameters simultaneously. For this property, it will be very much useful for many real‐time systems where time delays cannot be avoided. The sufficient conditions for existence of the observer are derived using the linear matrix inequality approach. With the help of a numerical example, effectiveness of the proposed observer is demonstrated. Copyright © 2012 John Wiley & Sons, Ltd.     

Adaptive sliding mode observer design for a class of uncertain systems

State feedback method is quite popular in control engineering field. However, some popular properties of state feedback approach cannot be used while any of the system states cannot be obtained beforehand. Therefore, this paper proposes a new observer design for a class of uncertain systems through sliding mode control theory. Based on strictly positive real concept, the stability of the equivalent error system is verified. Further, by using the generalized matrix inverse approach, the proposed switching term can drive the error states to zero, and it ensures the global reaching condition of the sliding mode of the error system. Moreover, the presented sliding mode observer is proposed to possess the invariance property to the uncertainty and/or external disturbance. Furthermore, the developed sliding mode observer is extended to release the limitation of knowing the bounds of the lumped perturbations in advance. That is, not only a new sliding mode observer but also a new adaptive sliding mode observer is proposed in this paper. Finally, three examples are illustrated to demonstrate the validity of the proposed sliding mode observer and the proposed adaptive sliding mode observer. Copyright © 2014 John Wiley & Sons, Ltd.     

Adaptive output feedback regulation for a class of uncertain feedforward nonlinear systems

In this paper, we solve the problem of global output feedback regulation for uncertain feedforward nonlinear systems. The nonlinear functions, in the class of systems under consideration, are assumed to be dominated by an input‐output function multiplied by an unknown parameter and a linear unmeasured states. Contrarily to the previous works, the interval of the output's power has been expanded from to . A numerical example is provided to illustrate the effectiveness of the proposed design scheme. Copyright © 2016 John Wiley & Sons, Ltd.     

An adaptive sliding‐mode observer for a class of uncertain nonlinear systems

In this paper, the problem of simultaneous state and parameter estimation is studied for a class of uncertain nonlinear systems. A nonlinear adaptive sliding‐mode observer is proposed based on a nonlinear parameter estimation algorithm. It is shown that such a nonlinear algorithm provides a rate of convergence faster than exponential, ie, faster than the classic linear algorithm. Then, the proposed parameter estimation algorithm is included in the structure of a sliding‐mode state observer, providing an ultimate bound for the full estimation error and attenuating the effects of the external disturbances. Moreover, the synthesis of the observer is given in terms of linear matrix inequalities. The corresponding proofs of convergence are developed based on the Lyapunov function approach and input‐to‐state stability theory. Some simulation results illustrate the efficiency of the proposed adaptive sliding‐mode observer.     

Adaptive sliding mode observers for sector-bounded nonlinear systems

This article introduces a novel sliding mode observer design for sector bounded nonlinear systems. The proposed observer can simultaneously estimate both states and unknown parameters in the presence of disturbances and measurement noise. The observer is developed by using a time-averaged Lyapunov (TAL) functional to analyze the effect of noise (Gaussian) and to adequately reduce its effect on the system. The TAL averages the Lyapunov analysis over a small finite time interval, allowing for intuitive analysis of noises and disturbances acting on the system. The TAL is shown to satisfy all the requirements of a Lyapunov candidate function. The article focuses on the observer design for sector bounded nonlinear systems since several nonlinearities can be modeled using a sector bound. An optimization approach is also developed to provide a tight bound on the effect of the uncertainty on the estimated parameters. The conditions for the existence of the observer are presented in the form of linear matrix inequality (LMI), which can be explicitly solved offline using commercial LMI solvers. Furthermore, the LMI design is also extended to a specific case of a dissipative nonlinear system. The observer design has also been extended to the case where the input disturbance is correlated with the sensor noise.     

Adaptive observer for nonlinear fractional‐order systems

In this paper, an adaptive observer is proposed for the joint estimation of states and parameters of a fractional nonlinear system with external perturbations. The convergence of the proposed observer is derived in terms of linear matrix inequalities (LMIs) by using an indirect Lyapunov method.The proposed adaptive observer is also robust against Lipschitz additive nonlinear uncertainty. The performance of the observer is illustrated through some examples including the chaotic Lorenz and Lü's systems. Copyright © 2016 John Wiley & Sons, Ltd.     

Sliding mode control for a class of uncertain nonlinear system based on disturbance observer

In this paper, a sliding mode control (SMC) scheme is proposed for a class of nonlinear systems based on disturbance observers. For a nonlinear system, the disturbance that cannot be directly measured is estimated using a nonlinear disturbance observer. By choosing an appropriate nonlinear gain function, the disturbance observer can well approximate the unknown disturbance. Based on the output of the disturbance observer, an SMC scheme is presented for the nonlinear system, and the stability of the closed‐loop system is established using Lyapunov method. Finally, two simulation examples are presented to illustrate the features and the effectiveness of the proposed disturbance‐observer‐based SMC scheme. Copyright © 2009 John Wiley & Sons, Ltd.     

一类时变互联不确定大系统的鲁棒分散自适应控制

研究了一类时变不确定大系统的分散镇定问题,其不确定性是范数有界不确定性和不确定性的界未知,且不满足匹配条件。基于Lyapunov稳定性理论,设计了两类分散自适应无记忆状态反馈控制,给出了系统状态渐近稳定的充分条件。通过数值例子验证了所提方法的有效性。     

Adaptive neural prescribed performance output feedback control of pure feedback nonlinear systems using disturbance observer

In this study, an adaptive output feedback control with prescribed performance is proposed for unknown pure feedback nonlinear systems with external disturbances and unmeasured states. A novel prescribed performance function is developed and incorporated into an output error transformation to achieve tracking control with prescribed performance. To handle the unknown non-affine nonlinearities and avoid the algebraic loop problem, the radial basis function neural network (RBFNN) is adopted to approximate the unknown non-affine nonlinearities with the help of Butterworth low-pass filter. Based on the output of the RBFNN, the coupled design between sate observer and disturbance observer is presented to estimate the unmeasured states and compounded disturbances. Then, the adaptive output feedback control scheme is proposed for unknown pure feedback nonlinear systems, where a first-order filter is introduced to tackle with the issue of “explosion of complexity” in the traditional back-stepping approach. The boundedness and convergence of the closed-loop system are proved rigorously by utilizing the Lyapunov stability theorem. Finally, simulation studies are worked out to demonstrate the effectiveness of the proposed scheme.     

Composite adaptive disturbance observer‐based control for a class of nonlinear systems with multisource disturbance

Antidisturbance control and estimation problem are introduced for a class of nonlinear system subject to multisource disturbances. The uncertain multisource disturbances consist of not only a single harmonic or constant disturbance but also another unexpected nonlinear signal described as a nonlinear function. The composite adaptive disturbance observers are constructed separately from the controller design to estimate the disturbance with partial known information. By integrating disturbance observer‐based controller with robust adaptive control, a novel type of composite adaptive disturbance observer‐based control scheme is presented for a class of nonlinear system with multisource disturbances. Simulations for a flight control system are given to demonstrate the effectiveness of the results compared with the previous schemes. Copyright © 2012 John Wiley & Sons, Ltd.