Aero‐Engine DCS Fault‐Tolerant Control with Markov Time Delay Based On Augmented Adaptive Sliding Mode Observer

With a focus on aero‐engine distributed control systems (DCSs) with Markov time delay, unknown input disturbance, and sensor and actuator simultaneous faults, a combined fault tolerant algorithm based on the adaptive sliding mode observer is studied. First, an uncertain augmented model of distributed control system is established under the condition of simultaneous sensor and actuator faults, which also considers the influence of the output disturbances. Second, an augmented adaptive sliding mode observer is designed and the linear matrix inequality (LMI) form stability condition of the combined closed‐loop system is deduced. Third, a robust sliding mode fault tolerant controller is designed based on fault estimation of the sliding mode observer, where the theory of predictive control is adopted to suppress the influence of random time delay on system stability. Simulation results indicate that the proposed sliding mode fault tolerant controller can be very effective despite the existence of faults and output disturbances, and is suitable for the simultaneous sensor and actuator faults condition.     

Fault-tolerant Control for Linear System Under Sensor Saturation Constraint

An observer-based fault-tolerant control method is proposed for a linear system with sensor saturation constraint. Considering the linear system with simultaneous actuator faults and sensor faults, the sensor saturation would bring the output measurement error of the system, which would result in the estimation performance degradation. Firstly, the intermediate estimator is modified to estimate the system states and fault signals at the simultaneous time, and the fault-tolerant controller is designed based on the estimation to compensate the effect of actuator faults effectively. Through Lyapunov stability analysis, the sufficient conditions are obtained to ensure the states of closed-loop system to be uniformly ultimately bounded. The effect of sensor saturation error can be suppressed by adjusting some specified parameters directly without introducing any performance index. Finally, the effectiveness and superiority of the proposed method are verified by a simulation example.

     

Robust Fault‐Tolerant Control of Launch Vehicle Via GPI Observer and Integral Sliding Mode Control

A robust fault‐tolerant attitude control scheme is proposed for a launch vehicle (LV) in the presence of unknown external disturbances, mismodeling dynamics, actuator faults, and actuator's constraints. The input‐output representation is employed to describe the rotational dynamics of LV rendering three independently decoupled second order single‐input‐single‐output (SISO) systems. In the differential algebraic framework, general proportional integral (GPI) observers are used for the estimations of the states and of the generalized disturbances, which include internal perturbations, external disturbances, and unknown actuator failures. In order to avoid the defects of the conventional sliding surface, a new nonlinear integral sliding manifold is introduced for the robust fault‐tolerant sliding mode controller design. The stability of the GPI observer and that of the closed‐loop system are guaranteed by Lyapunov's indirect and direct methods, respectively. The convincing numerical simulation results demonstrate the proposed control scheme is with high attitude tracking performance in the presence of various disturbances, actuator faults, and actuator constraints.     

Robust Actuator‐Fault‐Tolerant Control System Based on Sliding‐Mode Observer for Thrust‐Vectoring Aircrafts

In this paper, a robust actuator‐fault‐tolerant control (FTC) system is proposed for thrust‐vectoring aircraft (TVA) control. To this end, a TVA model with actuator fault dynamics, disturbances, and uncertain aerodynamic parameters is described, and a local fault detection and identification (FDI) mechanism is proposed to locate and identify faults, which utilizes an adaptive sliding‐mode observer (SMO) to detect actuator faults and two SMOs to identify and estimate their parameters. Finally, a fault‐tolerant controller is designed to compensate for these actuator faults, disturbances, and uncertain aerodynamic parameters; the approach combines back‐stepping control with fault parameters and a high‐order SMO. Furthermore, the stability of the entire control system is validated, and simulation results are given to demonstrate the effectiveness and potential for this robust FTC system.     

基于有限时间未知输入观测器的一类受扰非线性系统故障检测与估计

针对一类非线性系统同时存在执行器故障、传感器故障和扰动的问题,提出一种基于有限时间未知输入观测器的故障检测与估计方法.首先,通过线性非奇异变换将原系统解耦为两个降阶的子系统,其中一个子系统只包含扰动,另一个子系统同时包含扰动和故障;然后,通过一阶低通滤波器获得新的状态并与子系统构成增广系统,实现将原系统的传感器故障转化为增广系统的执行器故障;接着,设计未知输入观测器对增广系统故障进行检测,实现在有限时间内估计出系统的扰动和故障,并通过理论分析验证所设计观测器的有限时间收敛性;最后,基于永磁同步电机(PMSM)转速系统进行仿真研究,仿真结果验证了所提出方法的有效性.     

带有执行器故障的多水面船固定时间分布式滑模协同控制

针对未知环境干扰、未知执行器故障等多水面船协同控制问题,提出一种带有执行器故障的多水面船固定时间分布式滑模协同控制方法,可保证协同控制系统的全局固定时间的稳定性.首先,设计一种固定时间干扰观测器,用于估计集总扰动(包括未知环境扰动和未知执行器故障);其次,引入固定时间非奇异快速终端滑模面,可有效地消除系统的奇异性,改善系统的抖振;然后,提出一种基于固定时间非奇异快速终端滑模面和固定时间干扰观测器的分布式容错控制器,使得收敛时间上界与系统初始状态无关;最后,通过仿真实验验证所提出控制律的有效性.     

Sliding Mode Control for Uncertain Switched Systems with Partial Actuator Faults

This paper considers the sliding mode control for a class of uncertain switched systems with partial actuator faults. By employing a weighted sum of the input matrices, a common integral sliding surface is designed. Moreover, the exponential stability of the sliding mode dynamics is analyzed by adopting the multiple Lyapunov function method and the average dwell time strategy. It is shown that the state trajectory can be driven onto the proposed sliding surface despite the presence of parameter uncertainties, external disturbances, and actuator faults. A numerical example is given to demonstrate the effectiveness of the proposed method.     

航天器自适应快速非奇异终端滑模容错控制

针对存在外部干扰、转动惯量矩阵不确定以及执行器故障的航天器姿态跟踪控制问题,本文提出了基于自适应快速非奇异终端滑模的有限时间收敛故障容错控制方案.通过引入能够避免奇异点,且具有有限时间收敛特性的快速非奇异终端滑模面,设计了满足多约束条件有限时间收敛的姿态跟踪容错控制律,利用参数自适应方法使控制器不依赖转动惯量和外部干扰的上界信息.Lyapunov稳定性分析表明:在存在外部干扰、转动惯量矩阵不确定以及执行器故障等约束条件下,本文设计的控制律能够保证闭环系统的快速收敛性,而且对执行器故障具有良好的容错性能.数值仿真校验了该控制律在姿态跟踪控制中的优良性能.     

基于鲁棒自适应滑模观测器的多故障重构

针对一类不确定非线性系统, 基于滑模观测器研究执行器和传感器同时故障时的鲁棒重构问题. 引入线性变换矩阵并添加后置滤波器构建增维系统, 综合??_∞ 控制将鲁棒滑模观测器增益矩阵设计方法, 转化为LMI 约束下的多目标凸优化问题. 在滑模增益中添加了自适应律, 确保状态估计误差渐近稳定, 同时滑模运动经有限时间到达滑模面, 在此基础上给出执行器和传感器故障同时重构算法. 最后通过数值算例表明了所提出方法的有效性.

     

Simultaneous Actuator and Sensor Faults Reconstruction Based on Robust Sliding Mode Observer for a Class of Nonlinear Systems

This paper proposes a new robust fault reconstruction and estimation design for a class of nonlinear system described by the Takagi‐Sugeno model with unmeasurable premise variables subject to faults affecting actuators, sensor faults, and unknown disturbances. The augmented Takagi‐Sugeno system is introduced with a new fault vector which has two origins: the first one represents actuator faults, the second one denotes faults affecting sensors. The main contribution is focused primarily to conceive a sliding mode observer with two discontinuous terms designed to compensate for fault behavior and disturbance variation from the system states estimation. In the formalism of linear matrix inequalities, we derive sufficient conditions to guarantee the state estimation error stability and to obtain the observer gains. Meanwhile, additional effort is made to achieve simultaneous faults and disturbance reconstruction. Simulation results are given to illustrate the proposed approach performances.     

四旋翼无人机不匹配扰动抗干扰控制

针对四旋翼无人机存在的不匹配干扰和执行器故障等现象,提出了一种基于有限时间观测器的飞行控制方案。从无人机的运动学模型出发,构建了受执行器故障和不匹配干扰影响的控制模型。将干扰观测器与非奇异终端滑模控制 (NTSMC) 方法相结合,以实现复合抗干扰和容错控制器设计。首先,设计了两个非线性有限时间扰动观测器来估计不匹配扰动和执行器故障,有限时间观测器使得估计误差在有限时间内收敛到零。其次,将观测器与NTSMC控制方法结合,以在有限的时间内实现跟踪,并有效地减少抖振。最后,从理论和仿真验证了控制方法的有效性和所期望的控制性能。     

一种非线性系统被控对象故障诊断方法

控制系统中的传感器、执行器和被控对象的故障检测与诊断往往是把执行器和被控对象视为一个整体来研究, 这不利于故障的决策与处理. 对此, 设计了非线性系统故障诊断的滑模观测器, 提出一种诊断被控对象故障的方法, 即对非线性系统和执行器同时进行观测, 根据两观测器残差的变化情况判断出非线性系统中传感器、执行器和被控对象故障. 最后以单输入单输出非线性系统为例进行仿真, 验证了该方法的有效性.

     

Fault tolerant sliding mode control for T-S fuzzy stochastic time-delay system via a novel sliding mode observer approach

In this paper, a fault estimation and fault-tolerant control problem for a class of T-S fuzzy stochastic time-delay systems with actuator and sensor faults is investigated. A novel sliding mode observer is proposed, which can simultaneously estimate the system states, actuator and sensor faults with good accuracy. Based on the state and actuator fault estimation, a new sliding mode control scheme is developed, which can effectively eliminate the influence of actuator fault. Sufficient conditions for the existence of the proposed observer and fault-tolerant sliding mode controller are provided in terms of linear matrix inequality, and moreover, the reachability of the sliding mode surface can be guaranteed under the proposed control scheme. The propose sliding mode observer and fault-tolerant sliding mode controller can overcome the restrictive assumption that the input matrix of all local modes is the same. Finally, a numerical example is provided to verify the effectiveness of the proposed sliding mode observer and fault-tolerant sliding mode control technique.     

Back-stepping Fault-tolerant Control for Morphing Aircraft Based on Fixed-time Observer

In this paper, the problem of the back-stepping fault-tolerant control (FTC) based on fixed-time observer is addressed for the morphing aircraft with model uncertainties, external disturbances, and actuator faults. First, the longitudinal dynamics for the morphing process are presented, and the control-oriented models subject to undesired malfunctions are established. Second, the fixed-time observer is designed for offering estimations of compound disturbances, including system uncertainties, disturbance, and malfunction information. Especially, the observer errors could converge to zero by the proposed observer within a settling time, which is independent of the system’s initial conditions. Then, a back-stepping FTC strategy based on the observations is proposed for the altitude and velocity subsystem, and the stability of the close loop system would be guaranteed by the proposed controller despite the actuator failures. Furthermore, to eliminate the effects of the “explosion of complexity” of the back-stepping method, a modified dynamic surface is applied to compute derivatives of virtual laws. Finally, the numerical simulations verify the effectiveness of the proposed control approach.

     

基于super-twisting算法的多航天器姿态有限时间分布式协同控制

针对受外界干扰和执行器故障影响的多航天器姿态协同控制问题,本文设计了一种基于干扰观测器的分布式协同supper-twisting滑模控制器.首先,将各航天器的外界干扰和执行器故障看作一个集总干扰,设计自适应滑模干扰观测器对其进行估计.其次,将supper-twisting算法和积分滑模面相结合,设计一种基于多航天器姿态一致性误差的分布式协同控制器,并由Lyapunov稳定性理论证明了所设计的多航天器姿态可以在有限时间内收敛到平衡点附近的邻域内.最后的仿真研究及比较结果表明,所设计的控制器可以加快系统的收敛速度,并提高系统的控制精度.     

An adaptive integral sliding mode FTC scheme for dissimilar redundant actuation system of civil aircraft

ABSTRACT

This paper proposed a new adaptive integral sliding mode FTC scheme to deal with the actuator faults and failure. The scheme combines integral sliding mode control, control allocation scheme and adaptive strategy. The unknown actuator faults are handled by adaptive modulation gain of nonlinear ISMC law. To cope with complete failure, control allocation scheme is integrated with the baseline controller to provide tolerance. The proposed strategy relies on the estimate of actuator effectiveness. Therefore, an adaptive sliding mode observer based fault reconstruction scheme is proposed in this paper. The proposed scheme is implemented on dissimilar redundant actuation system driven by hydraulic and electro-hydraulic actuators. In nominal and faulty conditions, both actuators are contributing to achieving the desired control surface deflection. However, when the actuator failure occurs, the control signals are reallocated to the redundant actuator. The problem of dynamics mismatch is addressed using fractional order controller designed in an inner loop. The comparison with the existing literature is also conducted in the simulation to validate the dominant performance.     

Observer‐based fault‐tolerant control of hypersonic scramjet vehicles in the presence of actuator faults and saturation

An adaptive sliding mode observer (SMO)–based fault‐tolerant control method taking into consideration of actuator saturation is proposed for a hypersonic scramjet vehicle (HSV) under a class of time‐varying actuator faults. The SMO is designed to robustly estimate the HSV states and reconstruct the fault signals. The adaptive technique is integrated into the SMO to approximate the unknown bounds of system uncertainties, actuator faults, and estimation errors. The robust SMO synthesis condition, which can be formulated as a set of linear matrix inequalities, is improved by relaxing structure constraints to the Lyapunov matrix. An anti‐windup feedback control law, which utilizes the estimated HSV states and the fault signals, is designed to counteract the negative effects of actuator saturation induced by actuator faults. Simulation results demonstrate that the proposed approach can guarantee stability and maintain performance of the closed‐loop system in the presence of HSV actuator faults and saturation.     

带执行器饱和的N 连杆机械臂输出反馈动态面控制

针对带执行器饱和的多关节刚性机械臂系统,提出一种基于RBF神经网络补偿的输出反馈动态面控制.通过观测器实现角速度的观测,采用RBF网络实现执行器饱和的补偿;通过Lyapunov方法证明闭环系统的稳定性,实现高精度的角度和角速度跟踪.仿真结果表明,所提出的方法能够有效补偿系统存在的执行器饱和,显著减小跟踪误差,并且对于外界干扰具有一定的鲁棒性.