控制系统可诊断性的内涵与研究综述

作为表征控制系统故障诊断能力的属性, 故障可诊断性揭示了故障诊断深层次的内涵.将可诊断性分析纳入控制系统与诊断方案的设计环节, 可以从根本上提高系统对故障的诊断能力, 为研究故障诊断提供新的思路.本文分别从可诊断性的内涵、研究现状以及潜在发展趋势三个角度系统地对可诊断性进行分析.首先, 从定义、影响因素、与已有概念的关系以及应用四个方面剖析了控制系统可诊断性的内涵和研究意义.其次, 分别从可诊断性评价与设计两个方面对可诊断性的研究现状进行分析.最后, 通过对可诊断性已有成果进行总结归纳, 探讨了可诊断性研究存在的不足以及未来发展的趋势.     

航天器控制系统的自主诊断重构技术

自主诊断重构是确保航天器控制系统安全可靠自主运行的关键技术之一.本文针对航天器资源严重受限的客观情况,改变传统一味追求华丽算法与豪华配置的设计理念,从航天器的自身特性出发,深入挖掘诊断重构问题的本质,提出基于可诊断性与可重构性评价设计的研究思路.文章首先介绍了航天器自主诊断重构技术的发展现状,分析了当前技术的不足之处并探究了其深层原因;然后,提出了通过可诊断性与可重构性评价设计从根本上提高系统自主诊断重构能力的全新思路,梳理了其研究内容与研究概况;最后,对航天器控制系统自主诊断重构技术的发展趋势进行了展望.     

基于图论的深空探测航天器故障可诊断性评价

为了衡量深空探测航天器的自主故障诊断能力,提出基于图论的故障可诊断性评价方法.在对加权有向图进行介绍的基础上,给出强可推导结点、依赖于故障的可推导结点以及解析冗余结点等定义;分别提出故障可检测性和可分离性判据并给出相关证明,考虑深空探测航天器的资源约束问题,研究解析冗余关系优选方法;分析深空探测航天器的故障诊断层次,并对系统级故障诊断能力进行评价;最后,利用深空探测航天器的数学仿真数据对所提方法的有效性进行验证.     

航天器控制系统可重构性的内涵与研究综述

可重构性设计是提高航天器在轨运行质量的有效途径,可以从系统层面克服航天器控制系统固有可靠性不足、星上资源受限以及在轨故障不可维修等缺陷,目前已引起控制理论和航天器控制工程等领域的高度重视与广泛关注.本文首先结合航天器控制系统的固有特点,具体介绍可重构性的研究意义与概念内涵.然后从评价与设计两方面,详细梳理航天器控制系统可重构性的研究内容与研究现状.最后对目前可重构性研究领域中存在的一些问题以及未来可能的发展方向进行深入探讨.     

离散事件系统基于模式的安全故障诊断

基于模式的故障诊断方法能将触发系统故障的事件串诊断出来,但在诊断期间系统仍然可能执行被禁止的不安全操作.为此,提出了一种离散事件系统基于S型和T型模式的安全诊断方法.先对离散事件系统基于模式的安全可诊断性进行形式化,再通过构造非法语言识别器和安全诊断器对系统发生的故障模式实施安全诊断,最后分别得到了一个关于S型和T型模式的系统安全可诊断性的充分必要条件,实现了离散事件系统基于模式的安全故障诊断.     

含大时滞和噪声的网络化控制系统的最优故障诊断

研究含大测量时滞和噪声的网络控制系统(Networked control systems, NCS)的故障诊断问题, 提出一种新的基于无时滞转换方法的最优故障诊断器的设计方法. 该方法首先构造一个隐含故障状态的增广系统, 并利用无时滞转换方法将含有测量时滞的网络控制系统转换为无时滞系统. 然后给出了故障的可诊断性判据, 并利用对偶原理将最优故障诊断器的设计问题转换为状态反馈控制器设计问题. 最后, 通过构造一种满足二次型性能指标的最优故障诊断器, 实现了故障的实时诊断. 仿真示例验证了该方法的可行性和有效性.     

逆变器开关管故障诊断方法综述

逆变器作为电机驱动系统的核心部分,其安全性和可靠性对电机驱动系统的正常运行甚至整个系统的运行是至关重要的。针对逆变器开关管故障,文中主要从基于解析模型、基于信号处理和基于数据驱动三个方面对现有逆变器开关管开路故障诊断方法进行了综述,具体叙述了各种逆变器故障诊断方法的原理,并从这些方法的应用系统、诊断时间、算法实现难易和可靠性等角度对各种方法进行对比,突出了各自的优缺点。最后探讨了今后逆变器开关管故障诊断方法的研究难点和方向。     

Fault tolerant steer-by-wire systems: An overview

Steer-by-Wire (SbW) is considered to be the most significant innovation among X-by-Wire technologies that will revolutionise the automotive industry. A SbW system comprises of electronic control units, steering assist motors, and sensors that can potentially replace mechanical steering column linkages in a car. Among many issues that should be resolved before the commercialisation of SbW systems, maintaining reliability and fault-tolerance in such systems are two of the most pressing issues. There are many studies reported in the literature on fault detection and isolation (FDI), but fault diagnosis and fault tolerance in SbW systems has not received extensive attention. In this paper, an overview of fault diagnosis approaches with various forms of redundancy for SbW is presented. The existing approaches to fault tolerant control are considered and classified according to different criteria, such as design methodologies and applications. In addition, a comparison of different approaches is briefly carried out to provide an overall picture of historical, current, and future developments in this fault tolerant control for SbW systems.     

连续系统故障可诊断性评价方法综述

故障可诊断性评价是故障诊断的基础, 能够为诊断算法的开发和传感器的优化配置提供依据与指导. 在梳 理可诊断性概念、评价流程与功能的基础上, 从定量模型、定性模型以及数据驱动这3 个方面对连续系统可诊断性 评价方法进行分类综述, 归纳和评析了各方法的原理与特点, 并比较了定性评价与量化评价结果的优缺点. 最后探讨了故障可诊断性评价方法未来可能的发展方向.     

Safe diagnosability for fault-tolerant supervision of discrete-event systems

The problem of achieving fault-tolerant supervision of discrete-event systems is considered from the viewpoint of safe and timely diagnosis of unobservable faults. To this end, the new property of safe diagnosability is introduced and studied. Standard definitions of diagnosability of discrete-event systems deal with the problem of detecting the occurrence of unobservable fault events using model-based inferencing from observed sequences of events. In safe diagnosability, it is required in addition that fault detection occur prior to the execution of a given set of forbidden strings in the failed mode of operation of the system. For instance, this constraint could be required to prevent local faults from developing into failures that could cause safety hazards. If the system is safe diagnosable, reconfiguration actions could be forced upon the detection of faults prior to the execution of unsafe behaviour, thus achieving the objective of fault-tolerant supervision. Necessary and sufficient conditions for safe diagnosability are derived. In addition, the problem of explicitly considering safe diagnosability in controller design, termed “active safe diagnosis problem”, is formulated and solved. A brief discussion of safe diagnosability for timed models of discrete-event systems is also provided.     

Fault diagnosis in discrete-event systems: framework and model reduction

A state-based approach for online passive fault diagnosis in systems modeled as finite-state automata is presented. In this framework, the system and the diagnoser (the fault detection system) do not have to be initialized at the same time. Furthermore, no information about the state or even the condition (failure status) of the system before the initiation of diagnosis is required. The design of the fault detection system, in the worst case, has exponential complexity. A model reduction scheme with polynomial time complexity is introduced to reduce the computational complexity of the design. Diagnosability of failures is studied, and necessary and sufficient conditions for failure diagnosability are derived.     

动态系统实际故障可诊断性的量化评价研究

提出了一种新颖的动态系统实际故障可诊断性量化评价方法. 该方法无需设计任何诊断算法, 仅通过解析模型即可给出动态系统故障检测和隔离的难易程度, 从而为实现在系统设计阶段提高故障诊断能力的工程目标提供理论指导和参考依据. 首先, 通过标准化模型和等价空间变换, 将状态空间描述的随机动态系统实际故障可诊断性评价问题转化为概率统计中多元分布相似度判别的数学问题; 然后, 根据严格的数学证明, 指出距离相似度判别准则在进行可诊断性量化评价中存在的不足. 进而, 为弥补该不足, 利用故障矢量的分布概率以及不同故障矢量之间的余弦相似度, 设计基于方向相似度的可诊断性量化评价新方法; 最后, 通过数学仿真验证该方法的有效性和优越性.     

离散事件系统间歇性故障的安全诊断

离散事件系统的间歇性故障诊断能够将系统中发生的间歇性故障及时诊断出来,但在诊断期间的系统可能会执行不安全操作.针对间歇性故障在诊断期间的安全性问题,提出一种基于事件的安全诊断方法.首先对发生间歇性故障的离散事件系统进行建模,并给出系统间歇性故障的安全可诊断性的形式化定义.然后通过构造非法语言识别器对系统的非法操作进行识别,并在此基础上构建一个安全验证器,由此得到一个关于系统间歇性故障安全可诊断性的充分必要条件,实现离散事件系统对间歇性故障的安全诊断.这种安全诊断既保证了间歇性故障一旦发生即能被及时诊断出来,又确保了在故障诊断期间系统不会执行任何不安全操作.     

网络化控制系统的故障诊断与容错控制

介绍了网络化控制系统几类故障诊断与容错控制方法的基本思想。故障诊断与容错控制对于控制工程实践特别是对安全性有严格要求的控制系统是十分重要的。网络化控制系统通过共享网络资源实现控制而带来了各种优越性的同时,也给传统的控制理论带来了新的挑战。因此需要发展适用于此类异步的、基于信包的控制系统的控制理论与技术。网络化控制系统基于数学模型的故障诊断问题,在建立恰当的网络化系统模型后,可转化一类特定的时延系统故障诊断问题。     

Active diagnosis of discrete-event systems

The need for accurate and timely diagnosis of system failures and the advantages of automated diagnostic systems are well appreciated. However, diagnosability considerations are often not explicitly taken into account in the system design. In particular, design of the controller and that of the diagnostic subsystem are decoupled, and this may significantly affect the diagnosability properties of a system. The authors present an integrated approach to control and diagnosis. More specifically, they present an approach for the design of diagnosable systems by appropriate design of the system controller. This problem, which they refer to as the active diagnosis problem, is studied in the framework of discrete-event systems (DESs); it is based on prior and new results on the theory of diagnosis for DESs and on existing results in supervisory control under partial observations. They formulate the active diagnosis problem as a supervisory control problem where the legal language is an “appropriate” regular sublanguage of the regular language generated by the system. They present an iterative procedure for determining the supremal controllable, observable, and diagnosable sublanguage of the legal language and for obtaining the supervisor that synthesizes this language. This procedure provides both a controller that ensures diagnosability of the closed-loop system and a diagnoser for online failure diagnosis. The procedure can be implemented using finite-state machines and is guaranteed to converge in a finite number of iterations. The authors illustrate their approach using a simple pump-valve system     

Diagnosability analysis of hybrid systems cast in a discrete-event framework

This paper addresses the problem of assessing the diagnosability of hybrid systems modeled by a hybrid automaton coupling methods from the continuous and the discrete event model-based diagnosis fields. The discrete states of the hybrid automaton represent the modes of operation of the system for which the continuous dynamics are specified. The diagnosability of the continuously-valued part of the model is first analyzed and the new concept of mode signature is shown to characterize mode diagnosability from continuous measurements. Continuous dynamics are then abstracted by defining a set of signature-events associated to mode signature changes, preserving this way mode diagnosability. The behavior of the abstract hybrid system is then modeled by a prefix-closed language over the original event alphabet enriched by these additional events. Based on this language, diagnosability analysis of the hybrid system is cast into a discrete-event framework and hybrid diagnosability conditions are provided. A case study based on the Attitude and Orbit Control System of a spacecraft illustrates the method.     

分布式追踪技术综述

随着分布式软件系统在各个行业的广泛应用,如何提升系统运维效率,保障其服务的可靠与稳定,得到了学术界与工业界的关注.分布式软件系统其规模庞大、结构复杂、持续更新且大量服务请求并发执行的特点,给分布式软件系统的运维任务带来了严峻的挑战.传统的以组件/节点/进程/线程为中心的系统监控与追踪方法难以支持分布式软件的故障诊断、性能调优、系统理解等运维任务.分布式追踪技术识别并提取出分布式软件系统因处理单个服务请求所产生的因果相关的事件,以服务请求为中心对分布式软件系统的行为进行精准、细粒度地刻画,对提高分布式软件系统的运维效率有重要意义.对分布式追踪技术的研究与应用进行了综述,从追踪数据获取、请求事件提取、因果关系判断及请求路径表示这四个方面总结了分布式追踪技术的现状;同时以基于请求执行路径的故障诊断和性能分析为例,讨论了学术界对分布式追踪技术的应用研究;最后,对分布式追踪技术的数据读写依赖问题、通用性问题和评价问题进行了探讨并对未来的研究方向进行了展望.     

Diagnosability of fuzzy discrete event systems

In this paper, discrete event systems (DESs) are reformulated as fuzzy discrete event systems (FDESs) and fuzzy discrete event dynamical systems (FDEDSs). These frameworks include fuzzy states, events and IF-THEN rules. In these frameworks, all events occur at the same time with different membership degrees. Fuzzy states and events have been introduced to describe uncertainties that occur often in practical problems, such as fault diagnosis applications. To measure a diagnoser’s fault discrimination ability, a fuzzy diagnosability degree is proposed. If the diagnosability of the degree of the system yields one a diagnoser can be implemented to identify all possible fault types related to a system. For any degree less than one, researchers should not devote their time to distinguish all possible fault types correctly. Thus, two different diagnosability definitions FDEDS and FDES are introduced. Due to the specialized fuzzy rule-base embedded in the FDEDS, it is capable of representing a class of non-linear dynamic system. Computationally speaking, the framework of diagnosability of the FDEDS is structurally similar to the framework of diagnosability of a non-linear system. The crisp DES diagnosability has been turned into the term fuzzy diagnosability for the FDES. The newly proposed diagnosability definition allows us to define a degree of diagnosability in a class of non-linear systems. In addition, a simple fuzzy diagnosability checking method is introduced and some numerical examples are provided to illustrate this theoretical development. Finally, the potential applications of the proposed method are discussed.     

信息融合与多Agent技术在航天器能源管理系统在轨故障诊断中的应用

航天器能源系统的可靠运行对于航天器在轨安全有重要意义,其中能源管理是决定能源系统可靠性的关键因素;目前我国在航天器能源系统在轨故障诊断方面研究较少,绍了国内外故障诊断技术的现状以及相关技术在国外航天器中的实际应用,介绍了航天器能源管理系统的故障种类、检测原理以及解决方法,提出了一种引入信息融合和多Agent技术的新型航天器能源管理系统故障诊断方法;结合实际工程需求,探讨了该方法在航天器能源管理系统中应用的可行性,最后简要介绍了该技术在能源管理系统故障处理中的实现方案。     

航天发射系统运行安全性评估研究进展与挑战

航天发射作为人类太空活动最为基础和最为重要的环节之一,是评判一个国家综合国力的重要指标,而航天发射系统运行安全性评估作为现代航天发射控制指挥与决策系统的核心,是保证航天发射安全运行的基础.首先,本文概述了现代航天发射系统,简要回顾了系统安全性研究发展历程,阐述了航天发射系统运行安全性评估的内涵.其次,通过综述航天发射系统运行故障检测与诊断、异常运行工况识别、运行过程安全分析与预测、安全性动态评估技术等方面的研究现状的基础上,总结出了航天发射系统运行安全性评估面临着系统极度复杂、决策风险性极大、先验信息少以及评估结果要求高准确性与实时性等方面的挑战.最后,本文对航天发射系统运行安全性评估有待研究的基础前沿问题进行了思考.