系统级故障诊断中可诊断性的研究与发展

系统级故障诊断是保障多处理器计算机系统运行可靠性的重要手段,也是进行路由计算、容错分析的理论基础。系统级故障诊断中的可诊断性研究是为了进一步提高系统的诊断能力而进行的一系列诊断策略研究。系统级故障诊断中的可诊断性研究经历了半个世纪之后,已经发展成一个具有多种不同针对性的可诊断性理论集合,但是各个可诊断性之间的关联关系、优缺点以及适用性尚不清晰。基于此,本文在充分分析系统级故障诊断中可诊断性的国内外研究现状的基础上,明确了各个可诊断性的继承性关联关系、诊断能力以及故障的限制性条件,进而指出了可诊断性未来的发展方向。本文的研究为后续开展系统级故障诊断的可诊断性研究提供了宝贵的理论基础,具有重要的理论价值和现实意义。     

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.     

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Petri网的故障诊断研究理论的综述

故障诊断是离散事件系统中一项重要的研究内容,对于保障系统安全具有积极意义。基于Petri网的故障诊断相关研究主要分为故障可诊断性研究以及故障诊断器的构造理论研究,故障可诊断性又可以进一步分为一般可诊断性与K-可诊断性,而故障诊断器的设计方法又可以按照适用系统类型进一步分类。综述了故障诊断理论中可诊断性、K可诊断性的各类研究方法和研究结论,介绍了离散Petri网系统、连续Petri网系统和分布式Petri网系统中故障诊断器的设计方法,并对各类方法的特点进行了重点分析。最后,给出了基于Petri网的故障诊断进一步研究的方向与应用难点,其对今后研究有一定的指导意义。     

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.     

基于测试性的电子系统综合诊断与故障预测方法综述

故障诊断与预测技术是故障预测与健康管理(PHM)中的两大关键技术.依据电子系统的故障模式与机理,结合测试性设计分析理论,提出了一种基于测试性的电子系统综合诊断与故障预测方法框架.对国内外综合诊断与故障预测方法进行了分类与总结,从基于测试性的嵌入式诊断、基于信号处理的智能故障诊断、基于测试性的故障预测3个方面论述了电子系统综合诊断与故障预测方法.最后分析了制约电子系统综合诊断与故障预测的因素,并探讨了未来的发展趋势.     

考虑时间特性影响的控制系统可重构性定量评价方法研究

故障诊断时间和控制重构延时严重影响了控制系统的实际重构性能,然而目前缺乏相关研究.基于该现状,本文针对执行器快变偏差故障,重点考虑时间特性影响,结合能量与输入约束,对控制系统可重构性的定量评价问题展开了研究.首先,以基于观测器的故障诊断算法和控制重构方案为例,建立了重构系统模型;然后,以该模型为对象,通过对重构过程中关键时刻的分析,深入研究了系统故障后的动态特性,并综合考虑故障引起的状态偏差、资源浪费以及诊断误差,设计了用于描述故障系统性能下降程度的二次型性能指标;其次,利用Lyapunov稳定性理论,定量求解了性能指标关于时间的一般表达式,进而求得该指标在整个时域中的最优解;最后,基于最优性能指标,引入了可重构度的概念,实现了对控制系统可重构性的理论判定以及定量描述,并通过数值仿真验证了所提可重构性分析方法的有效性.     

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.     

有干扰的控制系统故障可诊断性量化评估

故障可诊断性的量化指标在控制系统设计过程中极为重要.为此,我们提出了一种适用于线性动态系统的故障可诊断性量化评估方法.考虑到过程和观测噪声等干扰因素对评估结果正确性的影响,我们采用等价空间方法获取系统输入/输出与故障之间的解析冗余关系,将故障可诊断性评估问题转化为概率统计中多元分布的差异度判别问题.引入巴氏系数(Bhattacharyya coefficient,BC)对多元分布之间的差异度进行量化,通过严格的数学证明得到可诊断性量化指标,并给出具体评估流程.以卫星姿态控制系统为仿真算例,将本文所提评估方法应用于该系统;仿真结果表明:该方法能够在不依赖于任何诊断算法的前提下,定量分析故障诊断的难易程度.     

离散事件系统部分可诊断性分析

针对离散事件系统部分可诊断性问题,提出一种量化评价与分析方法。该方法以树状结构的故障模型为基础,引入可诊断度与可诊断深度指标,能够从可诊断故障覆盖程度与精确程度两个方面对系统可诊断性进行评价,其优点是评价结果量化表示,能为部分可诊断系统的进一步评价、分析与对比提供参考。此外,还讨论了故障模型对系统可诊断度与可诊断深度两个评价指标的影响,并给出了故障模型构造的一般原则。实例分析与讨论结果表明,所提出的可诊断度与可诊断深度指标能够准确反映系统在特定故障模型下的部分可诊断状态。所提出的部分可诊断性评价方法能为基于离散事件模型的复杂系统设计与评价提供依据,并能够进一步为智能、自适应和自愈系统的设计提供参考。     

A review of the diagnosability of control systems with applications to spacecraft

To achieve the safe, reliable autonomous operation of spacecraft, research on the fault diagnosis of control systems has attracted the attention of engineers and academicians throughout the aerospace field. Diagnosability can characterize the fault diagnosis capability of control systems. Connecting diagnosability analysis to the design of a spacecraft control system’s structure and diagnosis method can fundamentally improve the system’s fault diagnosis capability, improving the safety and reliability of autonomous spacecraft operation. In this paper, the diagnosability of spacecraft control systems is systematically studied from five perspectives: necessity, the current research status, the connotation, a novel index system and current development trends of diagnosability. First, the current status of spacecraft reliability analysis and reliability-based design is briefly reviewed, and existing problems are described, highlighting the advantages and importance of diagnosability research. Furthermore, the basic concepts of diagnosability are briefly introduced. By analyzing the current status of existing research on the diagnosability of both general and spacecraft control systems, the application scope of the diagnosability of spacecraft control systems is summarized. Moreover, the definition and influencing factors of the diagnosability of spacecraft control systems are presented to refine existing concepts, and a universal evaluation index system is proposed for the diagnosability of spacecraft control systems to further enhance the applicability of diagnosability evaluation and diagnosability-based design to spacecraft. Finally, the existing shortcomings and future development trends of diagnosability research for spacecraft control systems are discussed.     

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.     

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.     

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.     

Local diagnosability of generic star-pyramid graph

The problem of fault diagnosis in network has been discussed widely. In this paper, we study the local diagnosability of a generic star-pyramid graph. We prove that under the PMC model the local diagnosability of each vertex in a generic star-pyramid graph is equal to its degree and the generic star-pyramid has the strong local diagnosability property. Then we study the local diagnosability of a faulty graph. After showing some properties of the graph, we prove that a generic star-pyramid graph keeps the strong property no matter how many edges are faulty under the condition that each vertex is incident with at least four fault-free edges.     

基于比较模型的交换超立方网络的(t,k)诊断度研究

故障诊断问题已经被广泛讨论,许多互连网络的诊断度已被深入研究。(t,k)-诊断为最重要的系统级故障诊断策略之一,在故障节点不大于t的前提条件下,每次迭代均可以识别最少故障节点个数为k。针对如何提高交换超立方网络的诊断度的问题,进行了一个基于比较模型的(t,k)-诊断算法研究,根据连通图的特性对交换超立方网络进行连通分子的划分,并计算交换超立方连通图中连接边与节点间的量化关系,从而证明了交换超立方网络是(t,k)-可诊断的。最终表明,本算法下的诊断度,优于其传统精确诊断s 1。     

Diagnosability Analysis of Intermittent Faults in Discrete Event Systems Using a Twin-plant Structure

Most research in fault diagnosis of discrete event systems has been focused on permanent failures. However, experience with monitoring of dynamic systems shows that intermittent faults are predominant, and that their diagnosis constitutes one of the most challenging tasks for surveillance activities. Among the main existing approaches to deal with permanent faults, two were widely investigated while considering different settings: the Diagnoser based approach, and the Twin-plant based approach. The latter was developed to cope with some complexity limitations of the former. In the present paper, we propose a twin-plant based approach to deal with diagnosability of intermittent faults. Firstly, we discuss various notions of diagnosability, while considering the occurrence of faults, their recovery, and the identification of the system status. Then, we establish the necessary and sufficient conditions for each notion, and develop on-the-fly algorithms to check these properties. The discussed approach is implemented in a prototype tool that is used to conduct experiments on a railway control benchmark.