基于自适应滑模观测器的航空电连接器间歇性失效检测

针对航空电连接器系统建立数学模型,提出基于自适应滑模观测器的故障重构方法实现间歇性失效检测.针对乘性故障上界未知的情况,设计自适应律在线修正滑模观测器增益.采用Lyapunov函数作为稳定观测器的判别条件,保证跟踪状态的收敛性.引入线性变换矩阵进一步求取实现滑模运动的滑模观测器增益常数项,并验证滑模运动将在有限时间内发生.应用等价输出误差介入原理获取故障信息,实现乘性故障的检测和重构.对重构出的特征参数进行分析可以判断电连接器是否发生失效.用SIMULINK进行仿真,结果验证该方法有效.     

飞机电缆跨转接头故障建模与诊断

构建飞机电缆系统复杂的跨多转接头结构,建立了飞机电缆跨转接头断路故障数学模型及相应的仿真模型,利用时域反射法计算与分析飞机电缆跨一个和多个转接头时特性阻抗及反射系数的变换规律,仿真研究飞机电缆断路故障时窄延脉冲波形跨一个和多个转接头下波形反射及透射情况,通过工控机硬件平台及LabVIEW软件搭建飞机电缆跨转接头故障诊断系统.实验结果表明:仿真模型在飞机电缆断路故障多个跨转接头时具有可扩展性,波形辨识度高,在高采样率硬件平台中可以实现飞机电缆跨转接头故障诊断及定位.     

Fault detection and isolation for nonlinear systems via high‐order‐sliding‐mode multiple‐observer

In this paper, fault detection and isolation problems are studied for a certain class of nonlinear systems. Under some structural conditions, multiple high‐order sliding‐mode observers are proposed. The value of the equivalent output injection is used for detecting faults and the multiple‐model approach for isolating particular faults in the system. The proposed method provides fast detection and isolation of actuator and plant faults. Simulation results support the proposed approach. Copyright © 2014 John Wiley & Sons, Ltd.     

Observer‐Based Multiple Faults Diagnosis Scheme for Satellite Attitude Control System

This paper proposes a multiple fault diagnosis (MFD) scheme based on an observer method for satellite attitude control systems (ACSs) subject to nonlinearity and external disturbances of the system. The essential idea is to develop a fault diagnosis scheme and design the corresponding observers for satellite ACSs. The nonlinearity, space external disturbances, sensor uncertainties, and multiple faults problem of the satellite ACS are all taken into account. The proposed MFD scheme is developed at two different levels. First, at the system level, two nonlinear observers based on analytical redundancy are designed for the MFD of the satellite ACS; this level roughly reveals the fault source. Then, at the component level, a bank of sliding mode observers activated by the results of the previous diagnosis is designed to precisely diagnose multiple faults of actuators in the satellite ACS; this level further precisely reveals the fault source. Both the nonlinear observers and the sliding mode observers are confirmed to be asymptotically stable via Lyapunov stability theory. Finally, numerical simulations of a satellite ACS are performed to illustrate the effectiveness of the proposed MFD scheme.     

Adaptive fault detection and isolation approach for actuator stuck faults in closed-loop systems

This paper addresses the fault detection and isolation (FDI) problem for linear time-invariant (LTI) systems under feedback control. Considered all the possible actuator stuck faults, the closed-loop systems are modeled via multiple models, i.e., fault-free model and faulty models. A fault detection observer and a bank of fault isolation observers are designed by using adaptive estimation techniques. The explicit fault detectability and isolability conditions are derived for determining the class of faults that are detectable and isolable. An F-18 aircraft model is employed to illustrate the effectiveness of the proposed FDI approach.     

Sliding mode estimation schemes for incipient sensor faults

This paper proposes a new method for the analysis and design of sliding mode observers for sensor fault reconstruction. The proposed scheme addresses one of the restrictions inherent in other sliding mode estimation approaches for sensor faults in the literature (which effectively require the open-loop system to be stable). For open-loop unstable systems, examples can be found, for certain combinations of sensor faults, for which existing sliding mode and unknown input linear observer schemes cannot be employed, to reconstruct faults. The method proposed in this paper overcomes these limitations. Simulation results demonstrate the effectiveness of the design framework proposed in the paper.     

飞机操纵面损伤的自适应容错控制设计

针对飞控系统实时控制和高可靠性的要求,提出一种飞控系统多操纵面损伤的在线容错控制算法.首先建立包含各种常见故障的操纵面参数仿真模型和故障注入仿真机制,其次由于故障的随机性,设计多个并行的在线观测器,对应于每个观测器模型建立一个基于特征结构配置的控制器.最后根据多个观测器和相应的控制器可完成系统在线故障隔离与重构.应用某型飞机横侧向控制系统进行仿真,得到了预期的效果.此方法设计简单合理,适于工程应用.     

Sliding mode observers for robust detection and reconstruction of actuator and sensor faults

This paper describes a method for designing sliding mode observers for detection and reconstruction of actuator and sensor faults, that is robust against system uncertainty. The method uses ??_∞ concepts to design the sliding motion so that an upper bound on the effect of the uncertainty on the reconstruction of the faults will be minimized. The design method is first applied to the case of actuator faults, and then by some appropriate filtering, the method is extended to the case of sensor faults. A VTOL aircraft example taken from the fault detection literature is used to demonstrate the method and its effectiveness. Copyright © 2003 John Wiley & Sons, Ltd.     

Third‐order sliding mode fault‐tolerant control for satellites based on iterative learning observer

The attitude fault‐tolerant control problem for a satellite with reaction‐wheel failures, uncertainties, and unknown external disturbances is investigated in this paper. Firstly, an iterative learning observer (ILO) is proposed to achieve fault detection, isolation, and estimation. Secondly, based on the ILO, a third‐order sliding mode controller is proposed to stabilize the satellite attitude rapidly under unknown external disturbances and reaction‐wheel faults. Thirdly, the asymptotically stability of the ILO and the third‐order sliding mode controller is proved by using the Lyapunov stability theory. Finally, simulation results demonstrate that the proposed control scheme is more effective and feasible by comparing with other fault‐tolerant control approach.     

高超声速飞行器间歇故障改进自适应容错控制

提出一种外部扰动/内部白噪声复合干扰和间歇性故障下的再入段变结构高超声速飞行器故障诊断和容错控制方法.首先给出再入姿态系统模型以及间歇故障模型.然后基于所研究的随机固定幅值故障模式对角速率系统中的周期性外部扰动进行预处理,根据处理结果,通过引入滑动时间窗设计一种残差信号.由于系统中存在白噪声,根据噪声分布特性并基于改进的残差信号提出两个假设检验,进而设计检测故障的两个阈值区间以检测间歇故障的发生和消失时间.与传统残差设计方法相比,改进的残差信号对于故障发生和消失时间的检测更准确.基于扩张系统设计一个自适应估计律用于估计故障,并使得估计误差满足$L_2$-增益干扰抑制.最后提出一个自适应容错控制算法使得系统的姿态角输出能够跟踪给定的参考信号.利用Lyapunov函数证明了系统的稳定性, Matlab仿真结果验证了所提出方法的有效性.     

航空装备连接型间歇故障诱发机理分析

航空装备连接型间歇故障是导致航空装备电子系统无故障发现和重测合格问题的主要原因之一。针对该问题，对航空装备连接型间歇故障的内涵和发生过程开展分析，指出间歇故障的发生是装备内部损伤和外部环境应力共同作用所致；然后选取航空装备电连接中的3种常见器件（电连接器、线缆、焊点）为研究对象，从内部损伤机理角度阐述了导致三者间歇故障发生的内部诱因，指出间歇故障发生的根本原因是电连接器件中存在一定的缺陷或损伤；重点分析了振动、温度、腐蚀等外部环境应力与间歇故障发生之间的关联关系，指出间歇故障的出现需要外部环境应力的激发，外部即时环境构成了航空连接型间歇故障的外部诱因。研究结果对减少航空装备在恶劣复杂环境下的无故障发现问题的出现具有参考意义。     

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.     

A sliding mode observer-based strategy for fault detection,isolation, and estimation in a class of Lipschitz nonlinear systems

This article investigates the design and application of a sliding mode observer (SMO) strategy for actuator as well as sensor fault detection, isolation, and estimation (FDIE) problem for a class of uncertain Lipschitz nonlinear systems. Actuator FDIE is addressed by regrouping the system's inputs into a structure suitable for SMO design. Similarly, by filtering the regrouped outputs, a similar system structure can be developed for sensor FDIE problem. Once in the suitable form and under certain assumptions, nonlinear SMOs are proposed for actuator and sensor FDIE. A systematic LMI-based design approach for the proposed SMO is presented. Additionally, the article addresses four problems, namely: (P1) What are the conditions for isolating single and/or multiple faults? (P2) What is the maximum number of faults that can be isolated simultaneously? (P3) How should one design SMO-based FDI approach in order to achieve multiple fault isolation using as few observers as possible? (P4) How can one estimate the shape of the faults? To solve the above problems, a new concept called fault isolation index (FIX) is proposed for actuator and sensor FDIE. It is proved that fault isolation can only be achieved if FIX?≠?0, and also that the maximum number of faults that can be isolated is equal to FIX. Using the proposed fault isolation strategy and by treating some healthy inputs or outputs as unknown inputs, a systematic FDIE design scheme using a bank of nonlinear SMOs, which provides a solution for the four problems is provided. An example is used to illustrate the proposed ideas. The simulation results show that the proposed FDIE scheme can successfully detect and isolate both slowly and fast-changing actuator faults. It is also shown that accurate estimation of actuator faults can be achieved.     

Robust adaptive fault‐tolerant control of uncertain linear systems via sliding‐mode output feedback

This paper is concerned with the robust adaptive fault‐tolerant compensation control problem via sliding‐mode output feedback for uncertain linear systems with actuator faults and exogenous disturbances. Mismatched disturbance attenuation is performed via H_∞ norm minimization. By incorporating the matrix full‐rank factorization technique with sliding surface design successfully, the total failure of certain actuators can be coped with, under the assumption that redundancy is available in the system. Without the need for a fault detection and isolation mechanism, an adaptive sliding mode controller, where the gain of the nonlinear unit vector term is updated automatically to compensate the effects of actuator faults, is designed to guarantee the asymptotic stability and adaptive H_∞ performance of closed‐loop systems. The effectiveness of the proposed design method is illustrated via a B747‐100/200 aircraft model. Copyright © 2014 John Wiley & Sons, Ltd.     

Sliding mode observers for a class of linear parameter varying systems

In this paper, a new framework for the synthesis of a class of sliding mode observers for affine linear parameter varying (LPV) systems is proposed. The sliding mode observer is synthesized by selecting the design freedom via linear matrix inequalities ( LMIs ). Posing the problem from a small gain perspective allows existing numerical techniques from the literature to be used for the purpose of synthesizing the observer gains. In particular, the framework allows affine parameter‐dependent Lyapunov functions to be considered for analyzing the stability of the state estimation error dynamics, to help reduce design conservatism. Initially a variable structure observer formulation is proposed, but by imposing further constraints on the LMIs, a stable sliding mode is introduced, which can force and maintain the output estimation error to be zero in finite time. The efficacy of the scheme is demonstrated using an LPV model of the short period dynamics of an aircraft and demonstrates simultaneous asymptotic estimation of the states and disturbances.     

Nonlinear sliding mode high-gain observers for fault estimation

A robust high gain observer for state and unknown inputs/faults estimations for a special class of nonlinear systems is developed in this article. Ensuring the observability of the faults/unknown inputs with respect to the outputs, the faults can be estimated from the sliding surface. Under a Lipschitz condition for the nonlinear part, the high gain observers are designed under some regularity assumptions. In the sliding mode, the convergence of the estimation error dynamics is proven similar to the analysis of high-gain observers.     

Actuator fault‐tolerant control (FTC) design with post‐fault transient improvement for application to aircraft control

A robust fault‐tolerant control scheme is proposed for uncertain nonlinear systems with zero dynamics, affected by actuator faults and lock‐in‐place and float failures. The proposed controller utilizes an adaptive second‐order sliding mode strategy integrated with the backstepping procedure, retaining the benefits of both the methodologies. A Lyapunov stability analysis has been conducted, which unfolds the advantages offered by the proposed methodology in the presence of inherent modeling errors and strong eventualities of faults and failures. Two modified adaptive laws have been formulated, to approximate the bounds of uncertainties due to modeling and to estimate the fault‐induced parametric uncertainties. The proposed scheme ensures robustness towards linearly parameterized mismatched uncertainties, in addition to parametric and nonparametric matched perturbations. The proposed controller has been shown to yield an improved post‐fault transient performance without any additional expense in the control energy spent. The proposed scheme is applied to the pitch control problem of a nonlinear longitudinal model of Boeing 747‐100/200 aircraft. Simulation results support theoretical propositions and confirm that the proposed controller produces superior post‐fault transient performance compared with already existing approaches designed for similar applications. Besides, the asymptotic stability of the overall controlled system is also established in the event of such faults and failures. Copyright © 2015 John Wiley & Sons, Ltd.     

Robust sliding-mode observer-based multiple-fault diagnosis scheme

In this study, we simultaneously evaluate the multiple-fault diagnosis problem of a class of Lipschitz nonlinear systems with actuator and sensor faults and unknown input disturbances. A nonsingular system transformation is used to transform the original system into two subsystems for multiple-fault diagnosis: subsystems 1 and 2. At the system level, two robust sliding-mode observers (RSMOs) are proposed. An RSMO is designed for subsystem 1 to detect actuator faults subjected to unknown input disturbances, and another RSMO is designed for subsystem 2 to detect sensor faults subjected to actuator faults. At the component level, a bank of RSMOs is proposed to detect and isolate actuators (sensors) with faults using a dedicated observer scheme. The reachability of RSMOs is comprehensively investigated in the estimation error space. Accordingly, the proposed observer parameters are designed as an optimization problem and solved using the linear matrix inequality (LMI) optimization technique. The effectiveness of the proposed multiple-fault diagnosis scheme was validated through simulations of a modified seventh-order aircraft system.     

一种滑模观测器的多故障诊断方法

针对非线性系统的执行器故障及传感器故障,提出一种鲁棒多故障检测方法．首先,对可能发生的每种执行器故障分别构造模型,并设计相应的滑模观测器用于残差生成,从而实现执行器故障检测．然后,设计一种算法,利用简单滤波器将传感器故障转换为执行器故障,从而直接利用执行器故障检测的方法实现传感器故障的检测,将执行器故障的检测方法推广到执行器、传感器故障同时存在的情况．最后,通过在单关节机械手中的仿真应用验证了所提方法的有效性．