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.     

具有执行器故障的四旋翼无人机有限时间容错控制

本文主要研究了四旋翼无人机在外部干扰、执行器存在部分失效和偏置故障并发情况下有限时间轨迹跟踪的控制问题. 通过分析四旋翼无人机动力学特性, 构建了带有外部干扰、执行器机构故障的动力学模型. 基于鲁棒全局快速终端滑模控制算法, 设计了一种有限时间容错控制器, 提高了系统对故障的响应速度. 其次, 针对常值/时变故障和干扰,在控制器设计中采用改进的连续函数进行补偿, 减少了由切换函数引起的系统抖振, 并基于Lyapunov函数对控制器的稳定性进行了分析. 最后, 通过仿真实验验证了所设计控制器的有效性和可靠性, 同时存在执行器故障和外部干扰的情况下, 无人机能够实现较好的轨迹跟踪性能.     

基于双通道事件触发机制的水面无人艇同时故障检测与控制

本文研究双通道事件触发通讯机制下水面无人艇(USV)的同时故障检测和控制(SFDC)问题.考虑执行器故障和外部扰动,建立了SFDC框架以同时实现控制和故障检测目标.为了节约有限的通信资源和系统能源,在传感器–控制器通道和控制器–执行器通道分别部署了积分型事件触发器.在事件触发的通讯机制下,提出了故障检测器和控制器的联合设计准则.最后, USV的仿真结果验证了提出的基于事件触发的SFDC方法的有效性.     

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.     

Finite‐time fault tolerant control for stochastic parameter systems with intermittent fault under stochastic communication protocol

In this article, the finite‐time fault tolerant control problem is investigated for a class of discrete‐time stochastic parameter systems subject to censored measurements. For the sake of relieving the communication burden, a stochastic communication protocol governed by a Markov chain is employed to determine which actuator has the access to the network at each transmission instant. Moreover, an improved performance index dependent on the predetermined censored threshold is constructed to evaluate the disturbance rejection level of the fault tolerant controller in the simultaneous presence of both external disturbances and censoring effects. The main aim of the addressed problem is to design a fault tolerant controller such that the closed‐loop system satisfies both the stochastically finite‐time boundedness and H_∞ performance requirements. In light of the Lyapunov theory combined with matrix inequalities, some sufficient conditions are derived skillfully, and the desired controller gains are calculated by solving a set of linear matrix inequalities. Finally, two simulation examples are utilized to demonstrate the effectiveness of the developed controller design method.     

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.     

Distributed active fault tolerant control design against actuator faults for multiple mobile robots

This paper investigates the active fault tolerant cooperative control problem for a team of wheeled mobile robots whose actuators are subjected to partial or severe faults during the team mission. The cooperative robots network only requires the interaction between local neighbors over the undirected graph and does not assume the existence of leaders in the network. We assume that the communication exists all the time during the mission. To avoid the system''s deterioration in the event of a fault, a set of extended Kalman filters (EKFs) are employed to monitor the actuators'' behavior for each robot. Then, based on the online information given by the EKFs, a reconfigurable sliding mode control is proposed to take an appropriate action to accommodate that fault. In this research study, two types of faults are considered. The first type is a partial actuator fault in which the faulty actuator responds to a partial of its control input, but still has the capability to continue the mission when the control law is reconfigured. In addition, the controllers of the remaining healthy robots are reconfigured simultaneously to move within the same capability of the faulty one. The second type is a severe actuator fault in which the faulty actuator is subjected to a large loss of its control input, and that lead the exclusion of that faulty robot from the team formation. Consequently, the remaining healthy robots update their reference trajectories and form a new formation shape to achieve the rest of the team mission.     

直升机执行器故障的双时标容错控制系统设计

针对直升机的执行器故障,本文提出了一种基于双时标模型的自适应容错控制方法.根据直升机的不同状态变量响应时间不同的特点和时标分离理论,将直升机模型划分为快速(姿态动力学)和慢速(平移动力学)两种时标模型.反步控制方法和逆动力学控制方法分别被用于进行快慢两种模型控制器的设计,并在控制过程中采用了不同的控制周期.在双时标模型中,引入了执行器效率因子(actuator effectiveness factors,AEFs)用于表示执行器的健康情况.利用无色卡尔曼滤波(unscented Kalman filter,UKF)对AEFs进行了在线估计,估计结果用于快速和慢速模型控制器的自适应重构.仿真结果表明,该自适应容错控制方法,能够有效的消除执行器故障(包括常值和时变故障)对直升机飞行性能的影响,并取得良好的控制效果.     

Results and perspectives on fault tolerant control for a class of hybrid systems

This article addresses the fault tolerant control (FTC) issue for a class of hybrid systems (HS) modelled by hybrid automata. Two kinds of faults are considered: continuous fault that affects each continuous system mode; discrete fault that affects the switching conditions. In these two faulty cases, the FTC design has two main objectives: (1) maintain the continuous performances including various stabilities of the origin and the output tracking/regulation behaviours along the trajectories of HS; (2) maintain the discrete specifications that have to be followed by HS, e.g. a desired switching sequence. The following three FTC methodologies are considered: FTC for HS with continuous stability goal; FTC for HS with discrete specifications; supervisory FTC design via hybrid control techniques. Some perspectives are also provided. This article provides the readers a survey on the main techniques that can be used to achieve these FTC goals of HS.     

Adaptive fault‐tolerant formation control for quadrotors with actuator faults

In this paper, we investigate the fault‐tolerant formation control of a group of quadrotor aircrafts with a leader. Continuous fault‐tolerant formation control protocol is constructed by using adaptive updating mechanism and boundary layer theory to compensate actuator fault. Results show that the desired formation pattern and trajectory under actuator fault can be achieved using the proposed fault‐tolerant formation control. A simulation is conducted to illustrate the effectiveness of the method.     

Robust adaptive fault tolerant control for a process with actuator faults

This paper studies design and implementation of an enhanced multivariable adaptive control scheme for an uncertain nonlinear process exposed to actuator faults. For adaptive fault compensation, a model reference adaptive control (MRAC) strategy is utilized as main controller. A new adaptation algorithm making possible to improve transient performance of adaptive control is integrated to the controller. With the help of further modifications, some restrictive conditions on multivariable adaptive design are relaxed so that the system requires less plant information. The resulting controller has a simpler structure than the other matrix factorization based controllers. At the final stage of design, a robust adaptive control scheme is obtained with consideration of practical implementation problems such as sensor noises, external disturbances and unmodeled​ system dynamics. It is proved that the controller guarantees closed-loop signal boundedness and asymptotic output tracking. Real-time experiment results acquired from quadruple tank benchmark system are presented in order to exhibit the effectiveness of the proposed scheme.     

Robust adaptive fault estimation and fault tolerant control for quadrotor attitude systems

ABSTRACT

This paper addresses the problem of fault estimation and fault tolerant control for quadrotor unmanned aerial vehicle. Firstly, a robust adaptive fault estimation observer (AFEO) is proposed to achieve fault estimation of quadrotor with actuator fault in the presence of external disturbances and parameter uncertainties. Furthermore, based on the estimation of fault, a dynamic output feedback fault tolerant controller (DOFFTC) is designed to stabilise the closed-loop system with faults and uncertainties. Sufficient conditions for the existence of both AFEO and DOFFTC are given in terms of linear matrix inequalities. Finally, simulation results are presented to illustrate the effectiveness of the proposed strategy.     

航天器执行机构部分失效故障的鲁棒容错控制

针对航天器在轨运行时受到外部干扰以及存在执行机构部分失效故障的问题,提出一种基于白适应滑模控制的鲁棒容错控制方法．该方法利用自适应算法估计执行机构故障的最小值,并通过设计滑模变结构控制器来实现对故障的容错控制以及对干扰的抑制控制,无需精确获得执行机构故障值,从而使得设计的控制器对于故障具有一定的鲁棒性．仿真结果表明了该...     

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.     

一类MISO 最小相位系统的执行器故障自适应容错控制

针对一类具有执行器卡死或/和变执行器故障的多输入单输出(MISO)非线性最小相位系统,提出一种自适应容错跟踪控制方案.采用自适应算法估计系统的不确定性,利用神经网络逼近执行器未知故障函数,以完成执行器组合故障状态下的跟踪控制.所设计的控制律不仅保证了闭环系统稳定,而且所有状态均有界,跟踪误差一致最终有界.仿真结果表明了所提出方法的有效性.     

Robust adaptive fault‐tolerant tracking control of multiple time‐delays systems with mismatched parameter uncertainties and actuator failures

This study deals with the problem of robust adaptive fault‐tolerant tracking for uncertain systems with multiple delayed state perturbations, mismatched parameter uncertainties, external disturbances, and actuator faults including loss of effectiveness, outage, and stuck. It is assumed that the upper bounds of the delayed state perturbations, the external disturbances and the unparameterizable time‐varying stuck faults are unknown. Then, by estimating online such unknown bounds and on the basis of the updated values of these unknown bounds from the adaptive mechanism, a class of memoryless state feedback fault‐tolerant controller with switching signal function is constructed for robust tracking of dynamical signals. Furthermore, by making use of the proposed adaptive robust tracking controller, the tracking error can be guaranteed to be asymptotically zero in spite of multiple delayed state perturbations, mismatched parameter uncertainties, external disturbances, and actuator faults. In addition, it is also proved that the solutions with tracking error of resulting adaptive closed‐loop system are uniformly bounded. Finally, a simulation example for B747‐100/200 aircraft system is provided to illustrate the efficiency of the proposed fault‐tolerant design approach. Copyright © 2014 John Wiley & Sons, Ltd.     

非线性系统主动容错控制综述

以故障发生部位为分类视角,分别从传感器故障、执行器故障及其他部件故障3个方面,较为详细地对近5年非线性系统主动容错控制的研究进展情况进行了归纳和总结,重点讨论了执行器故障的容错控制问题,并对所存在的问题与未来的发展趋势进行了探讨。     

基于积分滑模的航天器有限时间姿态容错控制

针对存在执行机构故障和外部干扰的刚体航天器姿态稳定系统,本文提出了基于积分滑模的容错控制策略,实现了姿态有限时间稳定.首先,利用齐次系统相关理论,设计了一类饱和有界的基础控制律,保证了不存在执行机构故障和干扰情况下的姿态有限时间稳定.在此基础上,利用积分滑模和自适应技术设计了一种有限时间姿态鲁棒容错控制方案,对执行机构故障和干扰进行有效的补偿;该方案能够快速地实现姿态高精度稳定,并抑制系统抖振现象.最后,将本文提出的姿态容错控制方案进行数值仿真与对比,验证了方案的有效性与优越性.     

Fault estimation and fault tolerant control for linear stochastic uncertain systems

This article investigates the fault estimation and fault tolerant control (FTC) problems for linear stochastic uncertain systems. By introducing the fictitious noise, the fault is augmented as part of the systems state, and then a robust estimator is proposed to simultaneously obtain the state and fault estimation. Based on the estimated information, the active FTC is presented to eliminate the impact of the fault. Finally, a simulation example is conducted to demonstrate the effectiveness of our main method.     

Fault‐tolerant control of singularly perturbed systems with actuator faults and disturbances

The article proposes several fault‐tolerant control (FTC) laws for singularly perturbed systems (SPS) with actuator faults and disturbances. One of the main challenges in this context is that the fast‐slow decomposition is not available for actuator faults and disturbances. In view of this, some conditions for the asymptotic stability of the closed‐loop dynamics are investigated by amending the composite Lyapunov approach. On top of this, a closed‐form expression of the upper bound of singular perturbation parameter (SPP) is provided. Moreover, we design several SPP‐independent composite FTC laws, which can be applied when this parameter is unknown. Finally, the chattering phenomenon is eliminated by using the continuous approximation technique. We also emphasize that, for linear SPSs, the FTC design can be formulated as a set of linear matrix inequalities, while the SPP upper bound can be obtained by solving a convex optimization problem. Two numerical examples are given to illustrate the effectiveness of the proposed methodology.