线性描述系统有限时间函数观测器设计及存在性讨论

本文针对线性描述系统研究了其有限时间函数观测器的设计方法和存在条件.首先,通过构造两个结构上完全相同的渐近收敛观测器得到了一个新的有限时间函数观测器,它可以在任意给定的时间内达到对目标函数的精确估计,且估计精度和收敛时间不依赖于原系统的初始条件.随后,对该函数观测器的存在条件进行了详细讨论,给出了函数观测器存在的充分必...     

一类非线性系统的变结构鲁棒观测器

研究了系统中不确定因素不满足匹配条件且具有外部干扰的变结构鲁棒观测器的设计问题,构造的观测器适用于标称系统是线性定常系统或可化正则型的仿射非线性系统。采用Ｌｙａｐｕｎｏｖ函数为稳定观测器的判别条件,使观测器在外有部干扰时具有一致最终有界的构造误差。     

类Lyapunov非线性系统降维观测器设计

对一般形式的非线性系统,引入了Lyapunov稳定意义下观测器存在性的概念,讨论了降维观测器的存在性.指出若相对于一特别形式的Lyapunov函数在Lyapunov稳定意义下存在全维观测器,则还存在降维观测器,并给出了降维观测器之设计方法.为说明该方法的指导意义,用该方法相对于Lipschitz非线性系统给出了降维观测器设计,并对该设计相对于一具体模型进行了仿真分析,仿真结果表明了该设计方法的正确性及实用性.     

一类不确定对象的扩张状态观测器

利用观测器形式的跟踪一微分器,对形如ｘ＾（ｎ）＝ｆ（ｘ,ｘ,．．．Ｘ＾（ｎ－１）,ｔ）＋Ｗ（ｔ）的不确定系统给出了“扩张状态观测器”。只要适当选取观测器中的非线性函数和相应参数,它能很好地跟踪一批不确定对象的扩张状态。     

一类不确定对象的变带宽状态观测器

研究了文献[1]提出的一类不确定对象扩张状态观测器的噪声抑制能力,并在此基础上提出一种利用改变带宽来改善观测器噪声抑制能力的方法,即让观测器的带宽成为信噪比的函数。仿真结果表明,改进后的状态观测器具有较好的噪声抑制能力和动态特性。     

一类非线性系统的函数观测器设计

研究单边Lipschitz非线性系统的函数观测器设计.基于线性矩阵不等式获得了函数观测器增益矩阵存在的条件,然后提出函数观测器增益矩阵的设计方法.通过一个仿真实例,验证所设计的函数观测器不仅能够估计系统的状态,而且可使观测误差快速收敛到零.     

控制输入饱和的柔性机械手容错控制

针对挠性机械手易受到建模误差和多源干扰等影响，该文提出了一种基于观测器的自适应容错控制策略。首先，构造干扰观测器（DO）和故障诊断观测器（FDO），分别对机械手的挠性附件产生的振动和执行器故障进行实时估计和抵消；其次，考虑了物理结构限制会导致执行器输入饱和情况，引入抗饱和算法，不仅降低了控制器设计难度，通过约束函数也保证了系统广义状态的稳定性；最后，通过MATLAB/Simulink仿真进一步验证了所提出方法的有效性。     

分数布朗运动干扰下广义随机系统滑模控制

本文考虑分数布朗运动干扰下时滞广义随机系统的基于观测器的滑模控制.首先设计了不受分数布朗运动干扰的状态观测器,然后给出了基于观测器的积分型滑模面函数的定义.为了研究观测器系统有限时间随机有界性,构造了带有二重积分的新型Lyapunov函数来处理分数布朗运动.利用奇异值分解原理,解决了观测器增益矩阵设计问题.利用线性矩阵不等式和Gronwall不等式得到了系统随机有界性的充分条件.同时给出了滑模面函数的有限时间可达性分析.最后的数值仿真验证了所提方法的有效性.     

基于PSO优化的船舶动力定位观测器

观测器设计是船舶动力系统至关重要的一个环节,而观测器的参数选取是否合适对动力定位系统的性能将产生很大的影响。建立了船舶非线性无源观测器,为了快速获得精确的观测器参数,提出利用粒子群算法对观测器参数进行寻优,寻优过程中利用观测器的估计偏差作为粒子群的适应度函数。文章最后对参数优化的观测器进行了仿真验证,仿真结果表明优化后的观测器具有较小的估计偏差且能改善动力定位系统的性能。     

广义线性系统的干扰解耦观测器设计

提出了广义线性系统的Luenberger函数观测器关于干扰解耦的充要条件,并进一步基于广义Sylvester矩阵方程的显式通解给出了干扰解耦观测器的参数化设计方法.这种方法首先给出了观测器增益矩阵的参数表示,然后通过结合观测器增益矩阵的参数表示和提出的干扰解耦条件,给出了设计广义线性系统干扰解耦观测器的算法.数值例子说明了本文设计方法的有效性.     

Dissipative interval observer design for discrete‐time nonlinear systems

This paper studies the problem of designing interval observers for a family of discrete‐time nonlinear systems subject to parametric uncertainties and external disturbances. The design approach states that the interval observers are constituted by a couple of preserving order observers, one providing an upper estimation of the state while the other provides a lower one. The design aim is to apply the cooperative and dissipative properties to the discrete‐time estimation error dynamics in order to guarantee that the upper and lower estimations are always above and below the true state trajectory for all times, while both estimations asymptotically converge towards a neighborhood of the true state values. The approach represents an extension to the original method proposed by the authors, which focuses on the continuous‐time nonlinear systems. In some situations, the design conditions can be formulated as bilinear matrix inequalities (BMIs) and/or linear matrix inequalities (LMIs). Two simulation examples are provided to show the effectiveness of the design approach.     

Distributed finite‐time formation control for multiple quadrotors via local communications

This paper investigates finite‐time formation tracking control problem for multiple quadrotors with external disturbance. The states of the virtual leader are not available to all the followers and the network topology is described by a directed graph. The model of each quadrotor is divided into position subsystem and attitude subsystem. Firstly, novel distributed finite‐time state observers are designed to estimate the relative state errors between followers and the virtual leader. Secondly, the values of these observers are used to design controllers that achieve finite‐time robust coordinated tracking in the position subsystem. Thirdly, the terminal sliding mode disturbance observers and finite‐time attitude tracking controllers are proposed, respectively, in the attitude subsystem to estimate the external disturbance and achieve attitude tracking control. The finite‐time stability analysis of the control algorithms is carried out using the Lyapunov theory and the homogeneous technique. Finally, the efficiency of the proposed algorithm is illustrated by numerical simulations.     

On state observers for nonlinear systems

For linear systems, it is known that there exists a state observer if and only if the system is detectable, or in other words, asymptotically stabilizable by output injection. In this paper, it is shown that asymptotic stabilizability by output injections is neither necessary nor sufficient for the construction of a nonlinear observer which may not have an exponential error decay rate. The concept of uniform observers is introduced and necessary conditions and sufficient conditions are given for the construction of uniform observers.     

Closed loop observers bundle for uncertain biotechnological models

We propose nonlinear observers for a class of biotechnological processes. These observers are an extension of the open loop asymptotic observers (observers with unknown inputs) devoted to biotechnological systems for which some parts of the model are unknown. We take benefit of the additional outputs which are (nonlinear) functions of the state to design a closed loop observer. The global convergence of these nonlinear observers is proven. We use these observers to design interval based observers which predict guaranteed intervals in which the state is lying. We run simultaneously a broad set of interval observers and we select the best ones. The method is illustrated with a model describing the bioconversion of a substrate using micro-organisms in a bioreactor.     

Partial state observers for linear systems with unknown inputs

We consider the problem of constructing partial state observers for discrete-time linear systems with unknown inputs. Specifically, for any given system, we develop a design procedure that characterizes the set of all linear functionals of the system state that can be reconstructed through a linear observer with a given delay. By treating the delay as a design parameter, we allow greater flexibility in estimating state functionals, and are able to obtain a procedure that directly produces the corresponding observer parameters. Our technique is also applicable to continuous-time systems by replacing delayed outputs with differentiated outputs.     

A robust estimation approach for uncertain systems with perturbed measurements

This paper deals with state estimation problem for uncertain continuous‐time systems. A numerical treatment is proposed for designing interval observers that ensures guaranteed upper and lower bounds on the estimated states. In order to take into account possible perturbations on the system and its outputs, a new type of interval observers is introduced. Such interval observers consist of two coupled general Luenberger‐type observers that involve dilatation functions. In addition, we provide an optimality criterion in order to find optimal interval observers that lead to tight interval error estimation. The proposed existence and optimality conditions are expressed in terms of linear programming. Also, some illustrative examples are given. Copyright © 2015 John Wiley & Sons, Ltd.     

Design and sensitivity analysis of a reduced-order rotor flux optimal observer for induction motor control

This paper aims to give simple and effective design criteria of rotor flux reduced-order observers for motion control systems with induction motors. While the observer is optimized for rotor and stator resistance variations, a sensitivity analysis is carried out in the presence of variations of all the motor parameters by means of either transfer function from true to observed rotor flux or simulation in a MATLAB-SIMULINK environment, assuming the voltages supplying the motor to be different from those supplying the observer. The sensitivity analysis makes it possible to establish design criteria for the observer in question. The behaviour of the proposed reduced order observer is compared with current model and voltage model observers. Experimental results are also given, with the dual aim of confirming the validity of this design method and showing that the observer can be implemented on microprocessor-based devices.