同时含有未知输入和测量干扰系统全维和降维观测器设计

针对同时含有未知输入和测量干扰的不确定系统研究了全维和降维观测器设计问题.首先,利用待定系数法给出了全维观测器的结构和存在条件.该条件完全由原系统的系统矩阵给出,易于检验.对于降维观测器,为了消除测量干扰的影响,提出了一种新的测量输出构造方法,使得新构造的测量输出不再包含干扰信号.此外,证明了全维和降维观测器存在条件的内在统一性,即全维观测器所需要满足的观测器匹配条件和强可检测条件在研究降维观测器所要讨论的新的系统中都可以得到保持.因而,在全维观测器存在条件下,也可以设计一个相应的降维观测器.最后,给出了一个数值例子验证所提方法的有效性.     

时滞Lipschitz非线性系统观测器设计

给出了满足Lipschitz条件的离散非线性时滞系统的全维、降维观测器的设计方法和误差收敛的充分条件,并分别进行了证明.全维观测器通过将带有非线性项的矩阵不等式转化为两步线性矩阵不等式解出两个增益矩阵.降维观测器则通过解线性矩阵不等式(LMI)方便地获得观测器的增益矩阵,消除了增益矩阵选取的盲目性.通过对同一模型的仿真分析,两种观测器的状态估计误差均能迅速收敛到0,表明了所提出方法的有效性.     

基于状态观测器的H∞控制系统设计

研究基于状态观测器的Ｈ∞控制器的设计原理,提出了基于观测器的Ｈ∞控制器的设计方法,并证明基于全维观测器组成的闭环系统具有与纯状态反馈的Ｈ∞控制器一样的传递函数,而在引入降维观测器时,则降低了闭环系统的Ｈ∞性能指标。最后用实例说明了理论结果和算法的有效性。     

二阶线性系统全维PI观测器的参数化设计

基于一类广义Sylvester矩阵方程的解．提出了二阶线性系统的全维PI观测器设计参数化方法．给出了该类观测器的增益矩阵和左特征向量矩阵的参数化表达式．该观测器设计的参数化方法直接基于二阶线性系统的参数矩阵,不涉及系统的变换或增广．数值例子表明了所提方法的简单有效性．     

仿射非线性系统的一种观测器设计方法

对仿射非线性系统全维观测器设计方法进行了讨论，提出了一种设计方法．该方法基于微分Riccati方程的正定解，观测器的增益矩阵通过Riccati方程的正定解给出，因而观测器增益矩阵为时变的．通过坐标变换，用李亚普诺夫方法对观测器的存在性进行了论证．对一个实际模型的仿真分析表明了该方法的实用性和正确性．     

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.     

全维观测器问题的算法研究

全维观测器就是通过两个状态反馈矩阵F和G的选取,得到这两个矩阵就可以得到全维状态观测器。对于多输入线性时不变系统,状态反馈矩阵F和G不唯一。目前,常用设计方法都没有解决F和G的优化设计,本文将矩阵遗传算法引入基于Sylvester方程的算法中,优化反馈矩阵,仿真结果表明：该算法求出的反馈矩阵F和G优于其它各种方法,对于工程实现无疑是有意义的。     

连续切换非方广义线性系统的观测器设计

针对一类连续切换非方广义线性系统,设计了广义状态观测器,并分析了状态估计误差的稳定性。首先通过矩阵的初等变换将连续切换非方广义线性系统的观测器设计问题转换为连续切换广义线性系统的观测器设计问题,之后设计第i个子系统的子观测器,可根据第i个子观测器构造这个广义切换系统的观测器。当观测器是全维观测器,且每个子系统都可检测时,状态估计误差甚至可以在任意切换下指数收敛到零。最后,通过数值实例和Matlab仿真分析说明了观测器设计方法简单可行,观测误差较其他方法的收敛速度快,证实了该方法的有效性和正确性。     

非线性系统观测器的设计:LMI方法

对满足Lipschitz条件的非线性系统给出了全维、降维观测器存在的充分条件并分别进行了证明,重点设计了新形式的降维状态观测器,观测器增益矩阵的获得完全取决于线性矩阵不等式(LMI)的解的情况,应用线性矩阵不等式工具箱使得设计更加方便,消除了增益矩阵选取的盲目性.通过对实际模型的仿真分析可知,两种观测器的状态估计误差均能渐近收敛到零,表明了该方法的有效性.     

基于稳定传输零点补偿器的动态输出观测器反馈控制

针对被控系统不满足实现动态输出观测器反馈控制两个充分条件的情况,提出稳定传输零点补偿器的概念.将零点补偿器与被控系统串联,使得整个系统拥有稳定的传输零点.这样就保证可以实现动态输出观测器反馈控制,从而使系统具有很高的鲁棒稳定性.通过实验将基于稳定传输零点补偿器的动态输出观测器反馈控制系统与全维状态观测器反馈控制系统进行...     

一类3阶非线性系统的非奇异终端滑模控制

针对传统非奇异终端滑模控制方法不适用于3阶系统的问题,提出一类具有不确定和外干扰的3阶非线性系统的新型非奇异终端滑模控制方法.该方案首先结合backstepping控制中的动态面方法和传统2阶非奇异终端滑模控制构造非奇异3阶终端滑模面,首次提出采用高阶滑模微分器估计值代替控制器中的负指数项.采用非线性干扰观测器任意精度地估计不确定和干扰,设计控制器中的补偿项.采用终端吸引子函数做趋近律避免抖振的同时能保证有限时间趋近滑模面.基于有限时间稳定李雅普诺夫定理证明了被控状态将在有限时间内收敛到任意小的闭球内.所提出方案快于传统的递阶线性滑模控制和其他非奇异终端滑模控制.仿真中与其他滑模控制方案对比,总误差减小18%以上,超调及收敛时间也显著下降.     

Robust reduced-order sliding mode observer design

In this article, a triple state and output variable transformation-based method combined with linear matrix inequality (LMI) techniques to design a new robust reduced-order sliding mode observer for perturbed linear multiple-input and multiple-output systems is developed. The state and output variables of the original system are triple transformed into suitable canonical form coordinates to facilitate the design of a reduced-order observer. The existing transformations are summarised in this study and presented systematically. A new combined observer configuration is proposed and compared with another type of observers. Global asymptotical stability LMI and sliding mode existence conditions for the coupled observer error system are derived using Lyapunov full quadratic form. Reaching and sliding modes of motion of decoupled observer error system are discussed as well. Two numerical and simulation examples are given to illustrate the usefulness of the proposed design techniques.     

一类k阶拟Bent函数密码性质的矩阵特征

由于非线性组合函数的密码性质通常可以由函数的Walsh谱和自相关函数来刻划，因而对函数的密码性质的分析通常要计算大量的Walsh循环谱值和自相关函数值来验证，该文利用一类k阶拟Bent函数的特殊性质，把对这类函数的密码性质的研究转化为对矩阵性质的研究，如平衡性、相关免疫性、扩散性、最高代数次数等，这种转化避开了大量的计算，同时为构造密码性质好的k阶拟Bent函数提供了一种更为简洁且易于实现的方法。     

拒绝服务攻击下网络化非线性系统的采样数据控制

本文研究了在拒绝服务攻击下网络化非线性系统的采样数据输出反馈控制问题.首先,为了避免使用完整的状态信息,在存在拒绝服务攻击的情况下设计了一种新颖的切换观测器.其次,同时考虑两个采样周期和拒绝服务攻击的影响,建立了一个新的切换增广系统模型,包括系统本身和误差系统.利用该模型和分段Lyapunov-Krasovskii泛函方法推导出保证切换增广系统是指数稳定的充分条件.进一步,利用线性矩阵不等式的解给出了观测器和控制器增益的共同设计方案.最后,通过仿真验证所提出控制方法的有效性.     

Adaptive control of feedback linearizable systems: a modelling error compensation approach

An adaptive output feedback controller for single input feedback linearizable systems is proposed. The output derivatives are estimated with a state high-gain observer, and the matched uncertainties are handled using a modelling error compensation method. Compared with existing adaptive methods, this approach avoids overparameterizations yielding an (n+1)-order compensator, where n is the system dimension. Semiglobal stability is proven with the aid of existing results on the stability of controlled nonlinear systems with high-gain state observation. Copyright © 1999 John Wiley & Sons, Ltd.     

Fault estimation observer design for discrete‐time systems in finite‐frequency domain

This paper proposes a framework of fault estimation observer design in finite‐frequency domain for discrete‐time systems. First, under the multiconstrained idea, a full‐order fault estimation observer in finite‐frequency domain is designed to achieve fault estimation by using the generalized Kalman–Yakubovich–Popov lemma to reduce conservatism generated by the entire frequency domain. Then, a reduced‐order fault estimation observer is constructed, which results in a new fault estimator to realize fault estimation using current output information. Furthermore, by introducing slack variables, improved results on full‐order fault estimation observer and reduced‐order fault estimation observer design with finite‐frequency specifications are obtained such that different Lyapunov matrices can be separately designed for each constraint. Simulation results are presented to illustrate the advantages of the theoretic results obtained. Copyright © 2014 John Wiley & Sons, Ltd.     

Analysis and design of chattering‐free discrete‐time sliding mode control

In this paper, the disturbance observer–based chattering‐free discrete‐time sliding mode control (DSMC) approach is proposed for systems with external disturbances. The proposed disturbance observer, which makes full use of the state and input information at the current and last steps, improves the estimation accuracy and achieves accurate compensation for disturbances. Then, with the help of disturbance observer, a new reaching law, which contains not only a nonsmooth term with a dynamically adjusted gain parameter but also a second order difference of the disturbance, is proposed to reduce the range of the quasi‐sliding mode band and eliminate chattering. The proposed DSMC approach realizes the active disturbance rejection and strong robustness. Finally, a simulation example is presented to verify the effectiveness of the proposed method.     

Full‐Order and Reduced‐order Observer Design for a Class of Fractional‐order Nonlinear Systems

The paper is concerned with problem of the full‐order and reduced‐order observer design for a class of fractional‐order one‐sided Lipschitz nonlinear systems. By introducing a continuous frequency distributed equivalent model and using indirect Lyapunov approach, the sufficient condition for asymptotic stability of the full‐order observer error dynamic system is presented. Furthermore, the proposed design method was extended to reduced‐order observer design for fractional‐order nonlinear systems. All the stability conditions are obtained in terms of LMI, which are less conservative than some existing ones. Finally, a numerical example demonstrates the validity of this approach.     

Observer‐based control of a photovoltaic DC–DC buck converter: HDS approach

In this paper, a new observer‐based controller is proposed for a photovoltaic DC – DC buck converter; both photovoltaic (PV) voltage and current regulation are considered. In order to deal with the complex and nonlinear PV mathematical model and adapt it to the control purpose, a hybrid PV current observer model is proposed; three modes are defined and the stability of the observer is discussed using the hybrid dynamical system approach (HDS). The observer‐based controller is designed for both voltage and current regulation of the PV system; the closed loop of the full system stability is demonstrated through Lyapunov analysis. Experimental results are also presented showing the feasibility of the proposed observer‐based controller.     

New dynamical observer for a batch crystallization process based on solute concentration

In this paper a new observer is introduced to estimate the Crystal Size Distribution (CSD) only from the measurements of the solute concentration, temperature and a model of the growth rate. No model of the nucleation rate is needed. This approach is based on the use of a Kazantzis-Kravaris/Luenberger observer which exponentially estimates functionals of the CSD. Then, the full state is estimated by means of a Tikhonov regularization procedure. Numerical simulations are provided. Our approach relies on an infinite-dimensional observer, contrarily to the usual moment based observers.