Fault estimation and active fault-tolerant control for a class of nonlinear systems with actuator and sensor faults based on unknown input iterative learning

In this paper, fault estimation and active fault-tolerant control are studied for a class of nonlinear systems with simultaneous actuator and sensor faults, as well as unknown external disturbances. Firstly, the state equation of a class of nonlinear systems is transformed into an augmented system state equation by extending the sensor fault as an auxiliary state. Then, a novel fault estimation observer based on iterative learning with unknown inputs is designed to estimate the system state, as well as actuator and sensor faults. Subsequently, by using the fault estimation information, a dynamic output feedback active fault-tolerant control scheme is proposed to compensate for the influence of faults on the system. Lyapunov stability theory is used to prove the stability of the closed-loop system and the convergence of the fault estimation observer. The gain matrices of the fault estimation observer and fault-tolerant controller are obtained by solving linear matrix inequalities. Furthermore, the paper avoids the use of the $$ norm in the convergence proof of the conventional iterative learning algorithm, which reduces the amount of calculation in the derivation process. Finally, the effectiveness and accuracy of the proposed method are verified through simulation of the DC motor angular velocity system.     

基于LMI双故障动态输出反馈完整性控制

针对线性系统,基于线性矩阵不等式(LMI)给出了具有完整性的动态输出反馈控制器的设计方案,所得到的结论,不仅给出分别考虑执行器和传感器两类部件发生故障的完整性设计方案,而且给出了考虑执行器或传感器任何一类部件发生故障的完整性设计方案．本文使用了比离散故障模型更具有实际意义的连续故障模型．一个数值例子说明了所提方法的有效性．     

Fault detection for output feedback control systems with actuator stuck faults: A steady‐state‐based approach

The paper studies the fault detection problem for output feedback control systems with bounded disturbances and nonzero constant reference inputs. A steady‐state‐based approach is proposed which can be used to detect small actuator stuck faults including actuator outage (the stuck value is zero). These small stuck faults, especially the outage faults, cannot be detected effectively using the existing techniques. A dynamic output feedback controller and a weighting matrix are designed simultaneously. The dynamic output feedback controller stabilizes the closed‐loop system for both fault‐free and faulty cases and attenuates the effects of disturbances. By manipulating the steady‐state values of system states with the detection weighting matrix, a residual is then generated, through which actuator stuck faults including actuator outages can be detected effectively. Simulation results are included to demonstrate our design procedure. Copyright © 2009 John Wiley & Sons, Ltd.     

A virtual actuator and sensor approach for fault tolerant control of LPV systems

In this paper, a fault tolerant control (FTC) strategy using virtual actuators and sensors for linear parameter varying (LPV) systems is proposed. The main idea of this FTC method, initially developed for LTI systems, is to reconfigure the control loop such that the nominal controller could still be used without need of retuning it. The plant with the faulty actuator/sensor is modified adding the virtual actuator/sensor block that masks the actuator/sensor fault. The suggested technique is an active FTC strategy that reconfigures the virtual actuator/sensor on-line taking into account faults and operating point changes. The stability of the reconfigured control loop is guaranteed if the faulty plant is stabilizable/detectable. The LPV virtual actuator/sensor is designed using polytopic LPV techniques and linear matrix inequalities (LMIs). A two-tank system simulator is used to assess the performance of the proposed method. In particular, it is shown that the application of the proposed technique results in an improvement, in terms of performance, with respect to the LTI counterpart.     

An optimal control method for applications using wireless sensor/actuator networks

The wireless sensor/actuator networks (WSANs) can be used for spatially distributed control systems. With smart sensors and actuators, the WSANs are able to not only sense the control system states and report measurements, but also perform control and actuation. This paper investigates WSANs on their ability of control. A centralized controller is introduced into WSANs to make up closed-loop control systems, in which control decisions are made based on global network-wide information. A model of the control and communication over WSANs is made theoretically, based on which we achieved an optimal control method. It is demonstrated by simulations that the control method proposed could stabilize the control system quickly.     

Simultaneous linear-quadratic optimal control design via static output feedback

In this paper, the problem of designing a fixed static output feedback control law which minimizes an upper bound on linear quadratic (LQ) performance measures for r distinct MIMO plants is addressed using linear matrix inequality (LMI) technique. An iterative LMI algorithm is proposed to obtain the solution. Examples are used to demonstrate its effectiveness. Copyright ©1999 John Wiley & Sons, Ltd.     

Simultaneous sensor and actuator fault estimation for continuous-time polytopic LPV system

In this paper, we study the problem of state estimation and both actuator and sensor fault detection for Linear Polytopic Parameter-Varying (LPV) system. The contribution of this work consists on the design of a novel robust adaptive observer based on polyquadratic formulations with a new set of relaxation. An optimisation problem is given in term of Linear Matrix Inequalities (LMI) in order to guarantee the stability of the system and the asymptotic convergence of faults error. A comparative study is made to prove the efficiency of the proposed polyquadratic algorithms against the quadratic ones. The performances and effectiveness of the proposed methods are illustrated in a simulation example where constant and variable actuator and sensor faults were detected.     

Nonstationary H∞ dynamic output feedback control for discrete‐time Markov jump linear systems with actuator and sensor saturations

This paper is concerned with the nonstationary dynamic output feedback control problem for a class of discrete‐time Markov jump linear systems (MJLSs) under simultaneous consideration of actuator and sensor saturations. The so‐called nonstationary controllers dominated by two other different piecewise‐stationary Markov chains are introduced, making the designed controllers not only mode‐dependent but also dependent on other variations associated with the mode transitions in the original MJLSs. The sufficient conditions formulated in terms of bilinear matrix inequalities for the H_∞ control problem are established such that the resulting closed‐loop system is stochastically stable and achieves a prescribed H_∞ noise attenuation level. A suboptimal algorithm with line search is exploited to solve for the associated controller gains. Effectiveness of the developed theoretical results is verified via a numerical example. Copyright © 2015 John Wiley & Sons, Ltd.     

线性系统区域稳定的可靠控制

针对线性系统,提出了抵御系统执行器故障和不确定性的状态反馈区域稳定可靠控制设计问题.通过对具有连续增益故障控制系统的分析,给出了区域稳定可靠控制器存在的充分条件和设计方法.所设计的区域稳定可靠控制器可以消除执行器故障对闭环系统极点配置的影响.使用线性矩阵不等式(LMI)表示的结果能够容易得到可靠控制增益的数值解.通过CH-47双旋翼直升机的实例仿真验证了该结果的可行性.通过比较区域稳定正常控制系统和可靠控制系统,进一步说明对系统进行可靠控制设计的必要性.     

不确定时延输出反馈网络化系统保性能控制

研究了一类具有不确定时延的动态输出反馈网络控制系统的保性能控制问题．针对小于等于一个采样周期的不确定时延,利用Lyapunov理论和线性矩阵不等式方法,推导出了动态输出反馈网络控制系统保性能控制律存在的条件,给出了动态输出反馈保性能控制律设计方法．利用LMI工具箱中的目标函数最小化工具,可以求得该类系统优化的保性能控制律参数和优化的性能指标,从而获得该系统的保性能控制律．给出的仿真算例说明了设计方法是有效的所得结果是可行的．     

不确定脉冲系统的动态输出反馈H∞控制

研究了不确定脉冲系统动态输出反馈H_∞控制问题. 考虑了两类脉冲形式: 一类脉冲是扰动型的, 一类脉冲是稳定型的. 对每类脉冲系统, 给出了鲁棒稳定性和具有有限L2增益的充分条件. 并在此基础上, 基于线性矩阵不等式, 得到了H_∞动态输出反馈控制器存在的充分条件. 最后, 数值例子说明了本文结果的有效性.     

基于LMI不确定离散随机系统输出反馈保性能控制

针对一类范数有界不确定离散随机系统,研究了具有输出反馈控制器的保性能控制,由此得到闭环系统的二次型性能指标上界的一般形式;然后应用LMI凸优化技术,推导出使闭环系统渐近稳定的最优保性能控制器的设计方法;最后通过仿真算例验证了所提出算法的可行性和有效性.     

执行器有时滞的馈能式主动悬架的鲁棒控制

车辆用的馈能式主动悬架系统具有不确定参数,而且执行器有时滞.为了保证其稳定性、减振性和能量回收性能,我们提出了一种保成本/H∞鲁棒控制器设计方法.对车辆悬架系统性能方面的要求,用二次型加权性能指标和H∞性能指标反映.定义了一个Lyapunov函数代表这两个性能指标;根据这个Lyapunov函数,把闭环系统设计问题转化为一组线性矩阵不等式以求解控制器.根据直流电机工作原理,分析了参数摄动和执行器时滞对系统能量平衡的影响,推导出了能量平衡方程.最后对二自由度1/4车悬架模型进行了仿真;结果表明:对一定范围内的参数摄动和有界时滞,悬架系统在有效减振的同时,实现了能量的回收.     

Adaptive output-feedback control for a class of nonlinear systems with actuator failures and input quantisation

In this paper, an adaptive output feedback control technique is proposed for a class of nonlinear systems with unknown parameters, unknown nonlinear functions, quantised input and possible actuator failures up to infinity. A modified backstepping approach is proposed by the use of high-gain K-filters, hyperbolic tangent function property and bound-estimation approach to compensate for the effect of possible number of actuator failures up to infinity, input quantisation and unknown nonlinear functions. It is proved both mathematically and by simulation that with the proposed controller, all the signals of the closed-loop system are globally bounded despite of input quantisation, unknown nonlinear functions and possible number of actuator failures up to infinity.     

一类广义不确定时滞系统的鲁棒容错控制

为了保证系统的稳定性和解决系统执行器失效的问题,针对一类线性广义时滞不确定系统,研究了在有记忆状态反馈作用下和执行器失效情况下的鲁棒容错控制问题。在采用具有更广泛意义的执行器故障模型下,给出了线性不确定时滞广义系统对执行器故障保持渐近稳定并且满足给定干扰衰减指标的鲁棒控制器的存在条件和设计方法。仿真结果验证了该方法的可行性和正确性。     

Output feedback variable structure control of uncertain linear systems in the presence of actuator dynamics

A new output feedback variable structure control scheme is developed based on a novel passivity idea. This scheme may practically stabilize a class of higher‐relative‐degree uncertain linear systems, and realize output tracking and disturbance attenuation as well. The controller is composed of linear filters and a single relay, without employing real‐time exact differentiators. Under this framework, we also explain how actuator dynamics affect the closed loop behavior. A simulation example shows the simplicity and efficiency of this method. Copyright © 2009 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society     

连续不确定模糊系统的静态输出反馈控制

对于一类状态矩阵、输入矩阵和扰动输入矩阵中均含有不确定项的连续T-S模糊系统,研究其静态输出反馈控制问题.用矩阵不等式的形式给出了该模糊系统可通过静态输出反馈控制稳定的充分条件,并将矩阵不等式的条件转化为迭代线性矩阵不等式,同时给出了相应的迭代算法.最后用数值仿真例子说明了该算法的有效性和收敛性.     

一类具有非线性饱和执行器的不确定时滞系统鲁棒控制

研究一类具有非线笥饱和执行器朱确定线性时滞系统的鲁棒性镇定问题。所考虑的不确定时滞系统具有时变未知且有界的不确定参数和状态时滞。提出了新的鲁棒可镇定判据和相应的鲁棒无记忆状态反馈控制器设计方法。数值仿真例子说明了所提出方法的有效性。     

具有扇形执行器的多机电力系统气门开度的时滞无关镇定

本文研究了具有扇形执行器的多机电力系统气门开度的时滞无关分散控制器和鲁棒分散控制器的设计问题.首先利用三角变换把非线性关联函数变换为子系统状态变量的二次有界不等式形式,然后基于Lyapunov稳定性理论,推导出闭环多机电力系统及其参数不确定系统渐近稳定的线性矩阵不等式(LMI)充分条件,最后以两机无穷大母线系统为例进行了仿真分析,验证了所提方法的有效性.     

一类饱和非有理系统状态反馈设计

本文研究了一类饱和非有理系统状态反馈镇定问题.通过线性分式表示技术,这类非有理系统可以转化为带有两个非线性回路的线性时不变(linear time-invariant,LTI)系统.假设非有理函数项分别满足局部扇形区间不等式以及局部Lipschitz条件,提出了两种基于LMI条件的镇定方法.最后,举例证明了所提出方法的有效性.