Industrial actuator benchmark for fault detection and isolation

Feedback control systems are vulnerable to faults within the control loop, because feedback actions may cause abrupt responses and process damage when faults occur. Such faults can be detected by model-based methods for fault detection and isolation (FDI) but research results have not been widely accepted in industry. One reason has been a scarcity of realistic examples for testing FDI methods against industrial systems. These special section papers focus on a common benchmark example, an electro-mechanical position servo, used in speed control of large diesel engines. The result is a platform for comparison of FDI methods and a gathering together of design experience on a simple, yet very realistic, industrial example. This paper introduces the benchmark problem, overviews the FDI methods used within the papers and discusses the results.     

Residual generator for sensor and actuator fault detection and isolation: a frequency domain approach

We consider the class of linear time invariant systems with m inputs (m actuators) and p outputs (p sensors). Our aim is to design a residual generator for detection and isolation of (m + p) failures, each of them occurring for a distinct actuator or sensor. We assume that only one fault is present at a time, and we restrict our attention to residual generators of a given structure. This allows us to associate particularly simple coding sets with the fault detection and isolation (FDI) system. Necessary and sufficient conditions for the existence of a solution to the problem are derived. Furthermore, the class of all residual generators of the required structure is parametrized.     

基于神经网络观测器的卫星姿态控制系统陀螺故障诊断

针对基于解析模型的卫星姿态控制系统陀螺故障诊断方法存在设计复杂、参数求解困难的问题,提出一种基于神经网络观测器的陀螺故障诊断方法。由系统内的冗余关系导出故障诊断逻辑,实现对陀螺故障的检测和隔离;同时利用先验模型知识和神经网络的非线性建模特性对陀螺故障进行估计。仿真结果表明,该方法能够实现对陀螺故障的检测、隔离和估计。     

Dynamic surface active fault tolerant control design for the attitude control systems of UAV with actuator fault

In this paper, an active fault tolerant control (FTC) approach based on transient performance index is proposed for the attitude control systems of unmanned aerial vehicle (UAV) with actuator fault. The nonlinear attitude control system model for UAV with actuator faults is given, which represents the dynamic characteristics of UAV. A fault diagnosis component is used for fault detection and estimation. According to the fault estimation information obtained during the fault diagnosis, the fault tolerant control scheme is developed by adopting the adaptive dynamic surface control technique, which guarantees the asymptotic output tracking and ultimate uniform boundedness of the closed-loop attitude control systems of UAV in actuator faulty case. Further, a prescribed transient performance of the FTC attitude control systems is considered which characterizes the convergence rate and maximum overshoot of the attitude tracking error. Finally, simulation results are shown that the attitude control system states remain bounded and the output tracking errors converge to a neighborhood of zero.     

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...     

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.     

基于鲁棒自适应观测器的飞控系统传感器故障隔离与重构

考虑到飞行控制系统闭环反馈及实时的特性,设计了多个鲁棒自适应观测器用于传感器的故障隔离与重构.这样有效的抑制了噪声和模型不确定性,以及闭环传感器输出之间的相互影响.同时对残差进行时序概率比检验,避免了故障误报和漏报.应用某型战斗机地形跟随控制系统进行仿真验证,在保证闭环反馈系统稳定的前提下,实现了传感器的在线故障隔离与重构,达到了预期的效果.     

挠性卫星的变结构姿态控制

将输入输出线性化控制与自适应模糊滑模控制相结合,并将其应用于挠性卫星姿态机动控制中.给出了卫星姿态控制器的基本形式.用自适应模糊控制逼近滑模控制中非线性控制分量,并推导了模糊规则参数调整的自适应律.在线调节自适应模糊控制器的参数以克服挠性卫星的不确定性,具有较强的鲁棒性.仿真结果表明该方法实现了较高精度的卫星姿态控制.     

Observer-based fault detection and isolation filter design for linear time-invariant systems

In this paper we consider a model-based fault detection and isolation problem for linear time-invariant dynamic systems subject to faults and disturbances. We use a state observer scheme that cancels the system dynamics and defines a residual vector signal that is sensitive only to faults and disturbances. We then design a stable fault detection and isolation filter such that the ?_∞-norm of the transfer matrix function from disturbances to the residual is minimised (for fault detection) subject to the constraint that the transfer matrix function from faults to residual is equal to a pre-assigned diagonal transfer matrix (for isolation of possibly simultaneous occurring faults). Our solution is given in the form of linear matrix inequalities using state-space techniques, as well as a model matching problem using matrix factorisation techniques. A numerical example is given to illustrate the efficiency of the fault detection and isolation filter.     

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.     

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.     

Simultaneous fault detection and control for switched systems with actuator faults

This paper is concerned with the fault detection and control problem for discrete-time switched systems. The actuator faults, especially ‘outage cases’, are considered. The detector/controller is designed simultaneously such that the closed-loop system switches under an average dwell time, and when a fault is detected, an alarm is generated and then the controller is switched to allow the norm of the states of the subsystem to increase within the acceptable limits. Thus, a switching strategy which combines average dwell time switching with event-driven switching is proposed. Under this switching strategy, the attention is focused on designing the detector/controller such that estimation errors between residual signals and faults are minimised for the fulfillment of fault detection objectives; simultaneously, the closed-loop system becomes asymptotically stable for the fulfillment of control objectives. A two-step procedure is adopted to obtain the solutions through satisfying a set of linear matrix inequalities. An example comprising of three cases is considered. Through these cases, it is demonstrated that the fault detection and control for switched systems using a two-stage switching strategy and asynchronous switching are feasible.     

基于SKPCA的卫星整流罩空调系统传感器故障检测研究

针对卫星整流罩空调系统对传感器故障检测的高可靠性的要求,在分析常见故障模式的基础上,采用了基于统计量核主元分析（ SKPCA）的故障检测方法,建立整流罩空调系统传感器故障检测模型,对整流罩空调系统传感器容易出现的偏置故障进行了验证实验。实验结果验证了SKPCA方法在整流罩空调系统传感器故障检测中的正确性和有效性。     

Survey and application of sensor fault detection and isolation schemes

Model-based sensor fault detection, isolation and accommodation (SFDIA) is a direction of development in particular with UAVs where sensor redundancy may not be an option due to weight, cost and space implications. SFDIA via neural networks (NNs) have been proposed over the years due to their nonlinear structures and online learning capabilities. The majority of papers tend to consider single sensor faults. While useful, this assumption can limit application to real systems where sensor faults can occur simultaneously or consecutively. In this paper we consider the latter scenario, where it is assumed that a 1 s time gap is present between consecutive faults. Furthermore few applications have considered fixed-wing UAVs where full autonomy is most needed. In this paper an EMRAN RBF NN is chosen for modelling purposes due to its ability to adapt well to nonlinear environments while maintaining high computational speeds. A nonlinear UAV model is used for demonstration, where decoupled longitudinal motion is considered. System and measurement noise is also included in the UAV model as wind gust disturbances on the angle of attack and sensor noise, respectively. The UAV is assumed to operate at an initial trimmed condition of speed, 32 m/s and altitude, 1000 m. After 30 separate SFDIA tests implemented on a 1.6 GHz Pentium processor, the NN-SFDIA scheme detected all but 2 faults and the NN processing time was 97% lower than the flight data sampling time.     

Active fault tolerant control for nonlinear systems with simultaneous actuator and sensor faults

The goal of this paper is to describe a novel fault tolerant tracking control (FTTC) strategy based on robust fault estimation and compensation of simultaneous actuator and sensor faults. Within the framework of fault tolerant control (FTC) the challenge is to develop an FTTC design strategy for nonlinear systems to tolerate simultaneous actuator and sensor faults that have bounded first time derivatives. The main contribution of this paper is the proposal of a new architecture based on a combination of actuator and sensor Takagi-Sugeno (T-S) proportional state estimators augmented with proportional and integral feedback (PPI) fault estimators together with a T-S dynamic output feedback control (TSDOFC) capable of time-varying reference tracking. Within this architecture the design freedom for each of the T-S estimators and the control system are available separately with an important consequence on robust L ₂ norm fault estimation and robust L ₂ norm closed-loop tracking performance. The FTTC strategy is illustrated using a nonlinear inverted pendulum example with time-varying tracking of a moving linear position reference.     

Determination of principal component analysis models for sensor fault detection and isolation

In this paper, a new method for determining the Principal Component Analysis (PCA) model structure for system diagnosis is proposed. This method, based on the variables reconstruction principle, determines the PCA model optimizing detection and isolation of single or multiple faults affecting redundant or non redundant variables of a system. This new method has been validated by a simulation example.     

Structural analysis for the sensor location problem in fault detection and isolation

In this paper we tackle the sensor location problem for fault detection and isolation based on structural analysis for linear systems with faults. We deal with this problem when the system under consideration is structured, that is, the entries of the system matrices are either fixed zeros or free parameters. With such structured systems one can associate a graph. A dedicated residual set is designed using a bank of observers for solving the problem. A major tool in this analysis is the notion of input separator in the associated graph, these separators form a lattice structure. The main contribution of this paper is the formulation of necessary and sufficient solvability conditions for the problem in terms of number of additional sensors measuring variables between faults and input separators in the associated graph.     

Robust sliding mode observer-based actuator fault detection and isolation for a class of nonlinear systems

In this article, an actuator fault detection and isolation scheme for a class of nonlinear systems with uncertainty is considered. The uncertainty is allowed to have a nonlinear bound which is a general function of the state variables. A sliding mode observer is first established based on a constrained Lyapunov equation. Then, the equivalent output error injection is employed to reconstruct the fault signal using the characteristics of the sliding mode observer and the structure of the uncertainty. The reconstructed signal can approximate the system fault signal to any accuracy even in the presence of a class of uncertainty. Finally, a simulation study on a nonlinear aircraft system is presented to show the effectiveness of the scheme.     

具有自适应调节律的非线性系统执行器故障检测和隔离方法

针对受到外部干扰的非线性系统,讨论了基于观测器的执行器故障检测和隔离方法.首先,通过引入一个对Lipschitz非线性项Lipschitz常数自适应调节的微分调节项,使得观测器具有自适应性,从而使观测器设计具有无须知道Lipschitz常数大小的优点;然后,通过一滑模控制项来抑制干扰,使观测器具有鲁棒性,并在此基础上,结合多观测器故障隔离的思想,提出了执行器故障检测和隔离方法;最后,通过对一个七阶飞行器实际模型的仿真,表明了该方法的实用性.