Fault detection for discrete-time networked nonlinear systems with incomplete measurements

This article addresses the problem of fault detection (FD) for discrete-time networked systems with global Lipschitz nonlinearities and incomplete measurements, including time delays, packet dropouts and signal quantisation. By utilising a discrete-time homogeneous Markov chain, an improved model which considers packet dropout compensation has been proposed to describe the above network-induced phenomena. We aim to design a mode-dependent fault detection filter (FDF) such that the FD system is asymptotically mean-square stable and satisfies a prescribed attenuation level. The addressed FD problem is then converted into an auxiliary H _∞ filtering problem of Markov jump system with time-varying delay. A sufficient condition for the existence of the FDF is derived in terms of certain linear matrix inequalities (LMIs). When these LMIs are feasible, the explicit expression of the desired FDF can also be characterised. A numerical example is exploited to show the effectiveness of the results obtained.     

Robust fault detection filter design for networked control systems with delay distribution characterisation

In this article, robust fault detection (RFD) is investigated for networked control systems with delay distribution characterisation. By utilising an observer-based fault detection filter as a residual generator, the RFD of networked control systems with non-uniformly distributed network‐induced time-varying delay is formulated as an H _∞ model-matching problem. Delay-interval-dependent and delay-interval-occurrence-rate-dependent sufficient conditions are obtained by employing the Lyapunov–Krasovskii functional approach. Especially, the robust fault detection filters guarantee strong robustness from residual signal to disturbance as well as high sensitivity to faults. A numerical example is given to illustrate the effectiveness of the proposed design techniques.     

Fault detection for nonlinear networked control systems with stochastic interval delay characterisation

In this article, we are concerned with the fault detection (FD) problem for nonlinear networked control systems (NCSs) with network-induced stochastic interval delay. By employing the information of probabilistic distribution of networked-induced time-varying delay, nonlinear constraint and the FD filter, nonlinear stochastic delay system model is established. Based on the obtained nonlinear model, utilising FD filter as residual generator, FD of nonlinear NCSs is formulated as nonlinear H _∞-filtering problem. Especially, the stochastic stability and prescribed H _∞ attenuation level are achieved using the Lyapunov functional approach, the desired FD filter is constructed in terms of certain linear matrix inequalities, which depends on not only nonlinear level but also on delay-interval and delay-interval-occurrence-rate. Numerical examples are provided to illustrate the effectiveness and applicability of proposed technique.     

具有随机丢包的非线性网络化控制系统鲁棒故障检测

针对具有随机丢包的Lipschitz非线性网络化控制系统,研究了系统存在外部干扰情况下的鲁棒故障检测问题。由于带宽有限,传感器-控制器和控制器-执行器的网络通道中存在随机数据包丢失,鉴于此,设计一种基于观测器的故障检测滤波器,给出存在故障检测滤波器的充分条件,使误差系统均方指数稳定并达到鲁棒H∞干扰抑制水平,同时给出基于观测残差均方值的故障检测策略。通过仿真算例验证了所提出方法的有效性。     

非线性网络控制系统的故障检测

针对一类具有随机丢包的非线性网络控制系统,研究了系统的故障检测问题.基于T-S模糊模型将对象线性化,考虑了控制器和执行器之间、控制器和传感器之间的随机丢包现象,采用满足Bernoulli分布的二进制序列来描述数据传输的随机丢包.同时利用模糊主导子系统规则,设计了模糊观测器,给出了基于观测器闭环系统渐近稳定的充分条件,并通过数值仿真实验验证了该方法的有效性.     

Delay-distribution-dependent fault detection of networked control systems with stochastic quality of services

Network-induced delay in networked control systems (NCS) is inherent non-uniform distribution and behaves with multifractal nature. However, such network characteristics have not been well considered in the fault detection and isolation of NCS. Making use of those statistical characteristics of NCS network-induced delay, a delay-distribution-based fault detection model is proposed, which is greatly different from the existing Markov switching process model. From this model together with a tighter bounding technique for cross-product terms, a delay-distribution-dependent H _∞ fault detection filter is carried out with significantly improved results. A numerical example is given to demonstrate the effectiveness of the proposed method.     

基于观测器的非线性网络控制系统容错控制

研究了一类基于观测器的非线性连续网络控制系统容错控制器设计问题.针对传感器采用时间驱动方式,控制器和执行器均采用事件驱动方式的网络控制系统,设计了观测器,建立了基于状态观测器的增广闭环系统模型.利用线性矩阵不等式和自由权矩阵的方法,推导出闭环系统渐近稳定的充分条件,给出了观测器和容错控制器协同设计的方法.实例仿真证明了所用方法的有效性.     

Robust fault detection for Markovian jump systems with unreliable communication links

This article addresses the problem of robust fault detection for Markovian jump linear systems with unreliable communication links. In the network communication channel, the effects of signal quantisation and measurement missing, which appears typically in a network environment, are taken into consideration simultaneously. A stochastic variable satisfying the Bernoulli random binary distribution is utilised to model the phenomenon of the measurements missing. The aim is to design a fault detection filter such that, for all unknown input and incomplete measurements, the error between the residual and weighted faults is made as small as possible. A sufficient condition for the existence of the desired fault detection filter is established in terms of a set of linear matrix inequalities. A simulation example is provided to illustrate the effectiveness and applicability of the proposed techniques.     

具有快变时延和丢包的网络控制系统镇定

对一类网络控制系统,研究了变时延和数据丢包对闭环系统稳定性的影响.基于Lyapunov-Krasovskii方法,给出了闭环系统的稳定条件,该条件不依赖于时延变化率的上界.通过求解一个适当的线性矩阵不等式(LMI)得到控制增益矩阵,求解时不需要对矩阵的结构进行限制,也不必使用重复迭代.最后,给出了一个数值例子以说明方法的有效性.     

Robust fuzzy tracking control for nonlinear networked control systems with integral quadratic constraints

This paper investigates the robust tracking control problem for a class of nonlinear networked control systems (NCSs) using the Takagi-Sugeno (T-S) fuzzy model approach. Based on a time-varying delay system transformed from the NCSs, an augmented Lyapunov function containing more useful information is constructed. A less conservative sufficient condition is established such that the closed-loop systems stability and time-domain integral quadratic constraints (IQCs) are satisfied while both time-varying network-induced delays and packet losses are taken into account. The fuzzy tracking controllers design scheme is derived in terms of linear matrix inequalities (LMIs) and parallel distributed compensation (PDC). Furthermore, robust stabilization criterion for nonlinear NCSs is given as an extension of the tracking control result. Finally, numerical simulations are provided to illustrate the effectiveness and merits of the proposed method.     

Robust fast adaptive fault estimation and tolerant control for T-S fuzzy systems with interval time-varying delay

This paper studies the problem of fault estimation (FE) and the active fault tolerant control (FTC) for Takagi–Sugeno (T-S) fuzzy systems with interval time-varying delay and norm-bounded external disturbance. Based on the fast adaptive fault estimation (FAFE) algorithm, our attention focuses on designing an adaptive observer-based controller to guarantee the filtering error system to be asymptotically stable and satisfy theH_∞ performance index. By constructing a new Lyapunov–Krasovskii functional including the information of the lower and upper delay bounds, the sufficient delay-dependent conditions have been established to guarantee the existence of adaptive observer-based controller in terms of linear matrix inequalities (LMIs). Compared with the constant delay and time-varying delay, the interval time-varying delay is the less conservative form. Furthermore, we make full use of the information of the delay and no terms are ignored when the stability of the system is analysed. In addition, the results for the systems with time-varying structured uncertainties are established. The results of the active FTC are showed in terms of LMIs. Finally, two examples are given to verify the effectiveness of the proposed method.     

网络化控制系统故障检测技术的最新进展

伴随着控制系统的日益复杂化以及网络技术的飞速发展, 网络化控制系统受到了人们越来越多的关注. 而作为提高系统安全性和可靠性的一项重要技术, 故障检测逐渐成为控制领域的研究热点之一. 本文针对网络化控制系统中存在的各种典型问题, 综述了相应故障检测技术的最新进展.     

基于观测器的非线性不确定系统鲁棒故障检测新方法

针对非线性不确定系统的鲁棒故障检测问题,提出了一种采用统计理论的新方法.通过设计全阶故障观测器产生残差信号,将鲁棒故障检测观测器设计问题转化为H∞优化问题;利用H∞范数描述故障检测的鲁棒性,保证系统的抗干扰能力,同时引入H_范数,确保对故障信号的灵敏度;应用线性矩阵不等式技术给出了该设计问题解存在的条件和求解方法.将统计理论用于故障检测阈值的确定,充分考虑了残差信号的随机特性,使故障决策更加准确和可靠.最后通过仿真实例验证了本文方法的有效性.     

Robust nonlinear variable selective control for networked systems

This paper is concerned with the networked control of a class of uncertain nonlinear systems. In this way, Takagi–Sugeno (T-S) fuzzy modelling is used to extend the previously proposed variable selective control (VSC) methodology to nonlinear systems. This extension is based upon the decomposition of the nonlinear system to a set of fuzzy-blended locally linearised subsystems and further application of the VSC methodology to each subsystem. To increase the applicability of the T-S approach for uncertain nonlinear networked control systems, this study considers the asynchronous premise variables in the plant and the controller, and then introduces a robust stability analysis and control synthesis. The resulting optimal switching-fuzzy controller provides a minimum guaranteed cost on an H₂ performance index. Simulation studies on three nonlinear benchmark problems demonstrate the effectiveness of the proposed method.     

时延网络控制系统的稳定性

针对网络控制系统中存在的不确定时延 ,首先讨论了系统的建模问题 .系统中传感器采用时间驱动 ,执行器与控制器采用事件驱动 ,传感器的数据采用单包传输 .假设传输时延小于采样周期 ,网络控制系统可以建模为一类具有不确定性的线性离散时延系统 .利用Lyapunov方法 ,给出了闭环系统渐近稳定的充分条件 ,基于相应的线性矩阵不等式可行解 ,可以求解状态反馈控制律 .最后 ,用仿真例子验证了该方法的有效性     

Fault detection for networked control systems subject to quantisation and packet dropout

This article addresses the stochastic fault detection (SFD) problem in finite-frequency domain for a class of networked control systems (NCSs) with respect to signal quantisation and data packet dropout. Considering a logarithmic quantiser and Markovian packet dropout, the NCS is modelled as a Markov jump linear system (MJLS) with quantisation error. Further, a new definition of finite-frequency stochastic H _? index is given, which gives a measurement of sensitivity. Subsequently, sufficient conditions are derived to guarantee that the MJLS can achieve such a performance. By virtue of the obtained conditions, the fault detection filters (FDFs) are designed in finite-frequency domain, which are valid in characterising the disturbance attenuation performance and finite-frequency fault sensitivity performance. Finally, a simulation example is given to illustrate the method and its effectiveness.     

具有丢包、通讯约束的非线性时滞网络化控制系统鲁棒故障检测

针对具有Lipschitz非线性时滞的网络化控制系统,研究系统具有丢包和通讯约束的故障检测问题.利用线性矩阵不等式设计故障检测滤波器,提出一种新的阈值计算方法,使得当系统在外部干扰情况下发生故障时残差评价函数能够迅速超出所设定的阈值,从而检测出执行器故障并使残差误差最小.最后通过仿真研究验证了所提出的方法能够更快速地检测出故障.     

带有随机时延的非线性网络控制系统的输出反馈镇定

考虑了一类非线性网络控制系统的输出反馈镇定问题.通过齐次马尔可夫链来描述采样器-控制器和控制器.执行器的时延,将网络控制系统建模为带跳非线性系统.利用Lyapunov方法和线性矩阵小等式技巧,得到了闭环系统随机稳定的充分条件,并给出了镇定控制器的设计方法.     

基于自由权矩阵法的网络控制系统稳定性研究

研究了包含随机、有界传输时延和丢包的网络控制系统的稳定。将网络控制系统建模为具有时变输入时延的离散时间模型,利用Lyapunov-Krasovskii定理和自由权矩阵法,推导得出基于线性矩阵不等式形式的渐近稳定充分条件。数值仿真验证了方法的有效性。