非线性动态系统的容错控制

首先概要介绍了非线性动态系统容错控制技术的发展现状;然后分类介绍了几种非线性系统的容错控制技术,重点分析了基于人工智能和参数估计的主动容错控制方法和基于Hamilton-Jacobi方程的非线性被动容错控制设计方法。对于其它的方法,则简要讨论了它们的适用范围和优缺点;并探讨了该领域的难点问题和可能的研究方向。     

非线性奇异系统的故障诊断与容错控制

本文针对一类非线性奇异系统进行了故障诊断与容错控制研究。首先通过设计观测器来观测系统的状态和故障,然后通过矩阵运算来消除故障,实现系统的容错控制。     

一类非线性系统的主动容错控制方法

对非线性系统发生多故障时的主动容错控制来说,控制性能的好坏主要取决于故障诊断机构的实时性和精确性;因此利用基于平衡学习的CMAC神经网络非线性辩识算法作为在线故障诊断的手段,在线估计故障函数;并用滑模控制算法进行容错控制律的在线重构,实现容错控制;最后以一三槽水位控制的实际应用为例进行仿真,其结果表明了所提方法的有效性.     

风能转换系统执行器故障主动容错控制

提出了一种新颖的风能转换系统滑模主动容错控制策略.针对风能转换系统执行器故障,运用预测控制思想和迭代算法,设计了一种故障观测器.在设定的优化时域长度内,利用实际系统与故障观测器的输出差值,通过反复迭代运算,不断地对虚拟故障信号进行调整,使其能有效地拟合实际系统执行器故障,并根据故障观测值实时调整滑模容错控制器结构.未发生故障时,故障观测值为零,系统在滑模控制器控制下稳定运行;执行器发生故障时,运用故障观测值实时调整滑模容错控制项,并用双曲正切函数代替符号函数,消除抖动.仿真实验结果表明,滑模容错控制器下的系统具有良好的容错能力,提高了风能转换系统最大风能捕获效率.     

一种非线性系统容错控制的混合方法

针对连续搅拌箱式反映器,提出一种闭环非线性系统容错控制的混合方法。即利用“等价偏差”的新概念建立传感器的故障模型,然后基于一种伪偏差分离估计算法,在线得到系统状态和“等价偏差”的估计值。数值仿真结果验证了该方法不仅具有很强的关于传感器故障的容错能力,而且还可检测、分离和估计出相应的故障。     

基于多模型切换的智能主动容错控制方法研究

针对某些具有可能故障先验知识的非线性系统,采用主动容错控制方法,基于神经网络对系统正常及各种先验故障情形建模,并采用基于神经网络的PID控制方法离线整定出各种故障模式下的控制律,由此建立模型库;在系统实时运行时,依据系统性能容忍度指标和模型失配度指标的计算分析,判断系统所处运行模式,切换与该模式匹配的控制律,从而达到系统主动容错控制的目的.最后将所提出的主动容错控制方法应用于某一非线性系统和线性系统,仿真结果表明了方法的有效性.     

非线性系统的主动容错控制

对一般的非线性系统提出了一种新的主动容错控制方法.系统正常工作时,采用基于迭代学习观测器的输出反馈控制策略,控制器为迭代学习观测器的状态和调节参数的函数,此输出反馈控制器能良好地镇定该非线性系统.当系统发生故障后,进行控制器重组,在调节参数的自适应调节律中引入了故障估计的信息,使得系统发生故障后包含故障估计信息的重组控制器仍然能使系统稳定,实现了非线性系统的主动容错控制.计算机模拟显示所提出算法的有效性.     

风能转换系统的LPV主动容错控制

随着对风力机效率和可靠性要求的提高,现代风力机不再如传统风力机那样一味追求高的产能。本文针对桨距执行器故障的风能转换系统具有非线性性和参数严重不确定性,提出了基于LPV增益调度的风能转换系统的主动容错控制方法,降低故障对机组动态特性的影响。基于LPV凸分解方法,将风能转化系统非线性模型化为具有凸多面体结构LPV模型,利用LMI技术对凸多面体各个顶点分别设计满足性能要求的控制器,再利用各顶点设计的反馈控制器得到具有凸多面体结构LPV容错控制器。仿真结果表明,LPV增益调度技术可以成功地应用于风能转换系统的容错控制,在有故障的情况下,仍能保持系统的稳定和良好的动态性能。     

离散时间系统的主动容错控制及飞控应用

针对处理一类线性不确定离散时间系统多重的、同时发生的、突变的舵机故障问题,提出了一种新的故障估计方案。该方案考虑了两种舵机故障模型:舵机卡死和舵机失效。所提出的舵机故障估计方案适用于为战机设计一个H∞容错飞行控制器,用于以零横向加速度跟踪飞机转弯角和俯仰率指令。仿真结果表明,采用H∞容错飞行控制器能够取得较好的控制效果。     

未知仿射非线性系统的执行器容错控制设计

针对一类多输入单输出未知仿射非线性系统研究了在执行器发生故障情况下的容错控制问题,基于反步设计和自适应模糊逼近理论给出了控制方案使闭环系统能够同时容忍执行器的卡死和失效故障。在每一步设计中采用一个模糊逼近器来逼近未知函数,其中包括系统函数和由故障引起的未知动态。然后基于Lyapunov稳定性理论设计自适应律在线调节逼近器的参数,使其可以自动补偿故障对系统的影响。最终得到的控制器能够在执行器发生卡死和失效故障的情况下利用未卡死执行器的有效部分保证闭环系统是稳定的,并且输出能够以指定的精度跟踪给定参考信号。仿真算例证实了该方法的可行性和有效性。     

航空发动机容错控制系统设计

航空发动机是一个结构复杂、非线性强的多变量控制对象.控制系统的高可靠性是最重要的技术指标之一.而容错控制为提高系统的可靠性、可维护性和有效性开辟了一条新途径.文中介绍了基于航空发动机容错控制的基本原理和方法,研究了控制系统在反馈信号故障情况下的容错控制问题,该系统可以对失效的检测数据做出实时估计并反馈信号,从而达到对故障容错的目的.     

运行控制系统集中式容错控制方法

本文针对运行控制系统,建立了运行优化控制过程的双层结构模型.在此基础上,通过建立相应的自适应故障诊断算法,提出了保证在系统有故障和干扰时仍能渐近优化指标的集中式容错控制方法,利用李雅普诺夫稳定性理论分析了自适应故障诊断算法的构建.已证明:该方法通过调整已优化的设定值来保证在回路控制层出现故障时整个运行控制仍可收敛到其原有的优化控制效果.该方法属于非完备容错控制,仿真结果验证了所提方法的有效性.     

Active fault tolerant control for switched positive linear systems

The main aim of this paper is to design an active fault tolerant controller for switched positive linear systems. A theorem is proved for fault and state estimation of switched positive linear systems in terms of matrix inequality by considering average dwell‐time approach. By utilizing the theorem results, not only a fast and exact estimation of fault and state is obtained but also the positivity of state estimation is ensured. The feasibility problem is solved by formulating it into a special sequential optimization problem subject to LMI constraints. Based on the fault estimation information, an observer‐based fault tolerant control guaranties the stability and positivity of the closed‐loop system. Finally, a practical example including a data communication network is presented to illustrate the efficiency of the proposed method.     

高速动车组多模型切换主动容错预测控制

高速动车组持续高速运行,对控制系统的可靠性和抗干扰能力提出了更高要求.结合高速动车组非线性动力学特点和系统运行数据,应用减法聚类和模式分类算法建立高速动车组多模型集;为适应对象和扰动特性的变化建立高速动车组自适应模型;采用基于累计误差最小的切换策略在线选择最优控制模型,据此设计主动容错预测控制算法来实现高速动车组安全高效运行.最后,仿真实例验证了该方法的有效性.     

Fault tolerant control for a class of nonlinear system with actuator faults

In this work, a fault tolerant control scheme is proposed for a class of nonlinear system with actuator faults. In this fault tolerant control strategy, an estimator is designed to estimate both the system states and the fault signal simultaneously. Based on these estimations, the control law is constructed to achieve the fault tolerant control for the nonlinear system considered. It is shown that the estimation error and the system state can be guaranteed to be bounded. The obtained theoretic results have been verified through the simulation examples on the three‐tank system.     

双电机同步驱动伺服系统故障诊断与容错控制

本文针对双电机同步驱动伺服系统中执行器失效会导致系统性能下降甚至失稳的情况,提出了一种基于自适应滑模的故障诊断和容错控制策略.该方法通过设计各电机转速的自适应滑模状态观测器,在线估计各执行器的失效因子:当单个执行器部分失效时,通过自适应的方法调整控制器增益;当单个执行器全部失效时,重构系统的控制律.对于系统中存在非匹配不确定项的情况,提出在期望虚拟信号中引入基于扩张状态观测器的补偿项抑制方案;利用Lyapunov理论证明了闭环系统在正常和故障状况下的稳定性以及观测器的收敛性;仿真结果表明,所设计的控制策略能保证系统稳定跟踪指令信号,在单个执行器失效的情况下系统跟踪性能基本不下降.     

Active fault‐tolerant consensus control of Lipschitz nonlinear multiagent systems

This article investigates the active fault‐tolerant consensus problem for Lipschitz nonlinear multiagent systems under detailed balanced directed graph and actuator faults. First, a fault detection filter for each agent is designed, and all agents can be divided into two categories: healthy agents and possibly faulty agents. Second, fully distributed adaptive fault‐tolerant consensus protocols for healthy and possibly faulty agents are proposed to achieve state consensus. Third, based on the fault detection method and fault‐tolerant consensus protocols, active fault‐tolerant consensus algorithms are given. Simulation examples are presented to verify the effectiveness of the proposed active fault‐tolerant algorithms.     

Prescribed performance adaptive fault tolerant control approach for nonlinear large-scale systems with time delay interconnection and dead zone input

In this study, a prescribed performance adaptive fault tolerant tracking control scheme is presented for a class of nonlinear large-scale systems with time delay interconnection, dead zone input, and actuator fault. The radial basis function neural networks are used to approximate unknown nonlinear functions. Different from the barrier Lyapunov functions used to achieve the symmetrical prescribed performance, a new error transformation is introduced in this study to achieve the desired asymmetrical prescribed performance. In addition, Nussbaum function is introduced to solve the difficulties caused by dead zone input and actuator fault. Based on the appropriate Lyapunov–Krasovskii functions, the effect of time delay interconnection could be compensated. By using backstepping procedures, an adaptive fault tolerant tracking control approach is developed for the considered large-scale systems, and the stability of the closed-loop systems is analyzed by Lyapunov theory. Meanwhile, the prescribed performance of the tracking error could be guaranteed. Finally, the effectiveness of the proposed control approach is illustrated by two simulation examples.     

Passive actuator fault tolerant control for a class of MIMO nonlinear systems with uncertainties

Fault tolerant control of affine class of multi-input multi-output (MIMO) nonlinear systems has not received considerable attention of researchers compared to other class of nonlinear systems. Therefore, this paper proposes an adaptive passive fault tolerant control method for actuator faults of affine class of MIMO nonlinear systems with uncertainties using sliding mode control . The actuator fault is represented by a multiplicative factor of the control signal which reflects the loss of actuator effectiveness. The design of the controller is based on the assumption that the maximum loss level of the actuator effectiveness is known. Furthermore, since the proposed controller is adaptive, it does not require any a-priori knowledge of the uncertainty bounds. The closed-loop stability conditions of the controller are derived based on Lyapunov theory. The effectiveness of the proposed controller is demonstrated considering two examples: a two degree of freedom helicopter and a two-link robot manipulator and has been found to be satisfactory.