具有BIBO稳定的网络系统随机容错设计

研究了具有均方BIBO稳定的网络化控制系统的随机容错控制及控制器设计问题。针对网络化控制系统的传感器失效故障和执行器失效故障均具有随机性这一现象,将传感器和执行器的故障建模为相互独立的Bernoulli随机变量序列;利用Lyapunov稳定性理论,结合线性矩阵不等式技术,通过对反馈增益矩阵的分解,得到了网络控制系统存在传感器失效故障和执行器失效故障情况下的均方BIBO稳定条件;基于该稳定条件给出了系统随机容错控制器的设计。以数值实例验证了该方法的有效性。     

基于无记忆降阶观测器的网络化控制系统故障检测方法

网络化控制系统(Networked Control System,简称NCS)研究的是如何通过网络实现闭 环控制,是涉及控制科学和计算机网络等多个学科知识的跨学科研究领域.本文将网络化控制系 统视为带有时延的采样控制系统,构造了一个无记忆的降阶状态观测器,通过比较观测器输出和 系统实际输出来产生残差,从而对网络化系统的控制故障进行了检测.仿真结果表明此方法是可 行的.     

具有传感器故障的网络控制系统保性能可靠控制

基于存在时延和丢包的网络传输环境,针对具有参数不确定性的网络化控制系统,研究了其在传感器故障条件下的保性能可靠控制问题.根据Lyapunov稳定性理论和线性矩阵不等式(LMI)方法,推导出使闭环网络控制系统在传感器故障条件下渐近稳定且保证综合性能指标满足要求的充分条件,并利用LMIs提出了保性能可靠控制率的设计方法.该控制算法在提高网络化控制系统可靠性的同时有利于系统综合体性能的优化.数值仿真验证了该方法的可行性和有效性.

     

无线隧道施工监控系统瞬时故障恢复控制

隧道施工中采用无线监控技术具有减少网络布线、增加系统灵活性的优点,但是现场施工环境的复杂多变性及传感器节点软硬件不稳定性会导致监控系统瞬时故障而引发安全事故。针对瞬时故障,从保障系统功能出发,建立瞬时故障层次模型,提出了一种多层次故障恢复控制策略,对现场数据监测层、数据传输层、安全防护层、应急响应层四层瞬时故障进行处理。模拟实验表明,该恢复控制策略能提高监控系统对灾害的检测准确率和应急响应动作的执行有效率,有利于保障隧道施工人员安全。     

具有传感器故障的网络控制系统保性能可靠控制

基于存在时延和丢包的网络传输环境.针对具有参数不确定性的网络化控制系统,研究了其在传感器故障条件下的保性能可靠控制问题.根据Lyapunov稳定性理论和线性矩阵不等式(LMIs)方法,推导出使闭环网络控制系统在传感器故障条件下渐近稳定且保证综合性能指标满足要求的充分条件,并利用LMIs提出了保性能可靠控制率的设计方法.该控制算法在提高网络化控制系统可靠性的同时有利于系统综合体性能的优化.数值仿真验证了该方法的可行性和有效性.     

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.     

容错分布控制系统设计

研究设计了一种容错离散分布控制系统的网络配置结构,即将控制系统中的每个可编程控制器作为一个控制结点,结点之间通过网络进行连接构成离散分布控制系统;使系统实现容错的方法是,增加一个在Galois域进行运算的冗余控制器结点,从而使系统能够自动侦查系统中的结点（可编程控制器）是否正常工作,并能使不正常工作的结点的功能得到恢复,确保系统的容错性和可靠性;实验证明这种设计是有效可行的;容错分布控制系统具有良好的抗故障能力,有很好的实际应用价值。     

具有随机时延的网络化控制系统基于等价空间的故障诊断

随着控制系统技术的飞速发展，把网络环节引入到传统的控制系统实现迅速准确的远 距离闭环控制是人们日益关注的课题．而网络中由信息的碰撞、重发而产生的网络延迟对控 制系统本身带来的负面影响却不容忽视．本文针对网络化控制系统(Networked Control S ystem，简称NCS)的随机延时，提出了延时估计和在线获得延时数据的两种方法，建立控制 对象的数学模型．利用z变换来处理延时，由等价关系产生残差，通过参数设计解耦干扰向 量，从而对网络化系统的控制故障进行了诊断，并提供了仿真结果．     

工业以太网通信中瞬时故障处理

为有效处理工业以太网通信中的瞬时故障,提出了一种基于芯片、节点和系统的多层次瞬时故障处理机制.根据工业以太网通信中瞬时故障的特点,从多个层次对瞬时故障的致因进行了分析.在此基础上设计了相应的处理方法,芯片层利用芯片提供的硬件逻辑结合软件技术自动调整芯片工作状态;节点层运用软件看门狗以及软件冗余;系统层定义特殊的帧格式和设置定时器.实验结果表明,多层次瞬时故障处理机制能有效降低网络的丢包率,提高了系统的可靠性.     

工业无线传感器网络节点通信中的瞬时故障恢复

无线传感器网络在工业领域应用广泛,由于电磁干扰、电源突然中断、软件突发错误等瞬时故障导致系统失效,影响系统安全,其控制和恢复在涉及安全的领域越发得到重视。考虑到瞬时故障在网络的多个层次可能都有发生,提出了一种三层故障处理机制,在芯片级采用硬件逻辑调整、在节点级采用重传和跳频、在系统级采用冗余路由等措施进行故障控制和恢复。实验结果表明,采用三层故障处理机制后,网络的丢包率和端对端的时延有效降低,节点通信的可靠性和安全性得到有效的提高。     

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.     

Transient fault tolerance in digital systems

It is hard to shield systems effectively from transient faults (fault avoidance techniques). So some other means must be employed to assure appropriate levels of transient fault tolerance (insensitivity to transient faults). They are based on fault-masking and fault recovery ideas. Having analyzed this problem, the author identifies critical design points and outlines some practical solutions that refer to efficient on-line detectors (detecting errors during the system operation) and error handling procedures. This framework provides a basis for understanding transient fault problems in digital systems. It can be helpful in selecting optimum techniques to mask or eliminate transient fault effects in developed systems     

Fault tolerance in supervisory control systems: a knowledge-based approach

Fault tolerance in computerized systems involved in production has become an ever more important requirement. Existing fault tolerance approaches, wherever used, deal mainly with hardware faults. Nevertheless, the vast majority of contemporary system failures are software related. This paper introduces a knowledge-based approach to handling software related faults occurring in supervisory control systems. These systems are event driven and use data, stored in complex databases, to react to events coming from different kinds of devices by identifying, scheduling, initiating and monitoring operations. Failure of part of the supervisory control system's software to behave rationally when unexpected events occur is called an application fault. The approach introduced in this paper is based on a supervisory control system reference model which reveals the set of all possible application faults together with the major functions of the recovery processes associated with each fault, and leads to a high-level knowledge-based system architecture capable of handling every fault-related condition. This system is called PROFIT (Intelligent PROduction systems Fault Tolerance) and consists of three main components: the fault diagnosis module, the instant fault correction module and the learning module, co-ordinated by a PROFIT meta-level module. The prototype version of PROFIT is analysed and the development as well as the run-time environment that prove the applicability and effectiveness of the system are presented.     

Active fault tolerant control using state-space self-tuning control approach

This paper presents a new fault tolerant control scheme for unknown multivariable stochastic systems by modifying the conventional state-space self-tuning control approach. For the detection of faults, a quantitative criterion is developed by comparing the innovation process errors occurring in the Kalman filter estimation algorithm, which, for faulty system recovery, a weighting matrix resetting technique is developed by adjusting and resetting the covariance matrices of the parameter estimate obtained in the Kalman filter estimation algorithm to improve the parameter estimation of the faulty systems. The proposed method can effectively cope with partially abrupt and/or gradual system faults and/or input failures with fault detection. The modified state-space self-tuning control scheme can be applied to the multivariable stochastic faulty system without requiring prior knowledge of system parameters and noise properties.     

无线传感器网络故障诊断与容错控制研究进展

可靠性和可持续性是无线传感器网络(WSNs)研究的重要问题。从拓扑、能量、监测和安全等角度对WSNs故障诊断和容错控制方法进行详细的归纳和总结。对WSNs故障类型进行了划分,主要分为节点故障和网络故障,根据WSNs体系结构,介绍了节点自诊断、网络诊断和基站诊断3种故障诊断方法,阐述了相关的容错控制技术,包括冗余机制、多路由设计、动态拓扑控制、传输协议优化、数据融合和智能方法。对WSNs容错控制技术目前存在的问题与未来发展趋势进行了探讨。     

Adaptive neural model-based fault tolerant control for multi-variable processes

An adaptive neural network model-based fault tolerant control approach for unknown non-linear multi-variable dynamic systems is proposed. A multi-layer Perceptron network is used as the process model and is adapted on-line using the extended Kalman filter to learn changes in process dynamics. In this way, the adaptive model will learn the post-fault dynamics caused by actuator or component faults. Then, the inversion of the neural model is used as a controller to maintain the system stability and control performance after fault occurrence. The convergence of the model inversion control is proved using Lyapunov method. The proposed method is applied to the simulation of a two-input two-output continuous-stirred tank reactor to demonstrate the effectiveness of the approach. Several actuator and component faults are simulated on the continuously stirred tank reactor process when the system is under the proposed fault tolerant control. The results have shown a fast recovery of tracking performance and the maintained stability.     

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。     

Measurement and analysis of workload effects on fault latency inreal-time systems

The authors demonstrate the need to address fault latency in highly reliable real-time control computer systems. It is noted that the effectiveness of all known recovery mechanisms is greatly reduced in the presence of multiple latent faults. The presence of multiple latent faults increases the possibility of multiple errors, which could result in coverage failure. The authors present experimental evidence indicating that the duration of fault latency is dependent on workload. A synthetic work generator is used to vary the workload, and a hardware fault injector is applied to inject transient faults of varying durations. This method makes it possible to derive the distribution of fault latency duration. Experimental results obtained from the fault-tolerant multiprocessor at the NASA Airlab are presented and discussed