Fuzzy fault tree analysis based on T–S model with application to INS/GPS navigation system

A novel fault tree analysis (FTA) technique based on the Takagi and Sugeno (T–S) model is proposed in this paper. In the proposed technique, referred to as the TS-FTA, the events in the conventional FTA can be expressed in terms of fuzzy possibilities, and the gates that represent the relations among the top event and the primary events are replaced by T–S fuzzy gates derived from the T–S model. The magnitudes of the faults in the system are expressed in term of fuzzy variables. Since the proposed TS-FTA is derived from fuzzy logic and the T–S model, it can readily handle fuzzy information and uncertainties in the relationships among events. Therefore, the TS-FTA is suitable for systems where exact information on the fault probabilities of the components and the failure mechanisms are not available. The proposed TS-FTA is applied to analyze the reliability of an Inertial Navigation System and Global Position System (INS/GPS) integrated navigation system.     

基于T-S模糊故障树方法的惯性导航系统可靠性评估

针对传统故障树模型在复杂系统可靠性评估中的局限性,引入T-S模糊故障树建模方法对惯性导航系统进行可靠性评估分析.在建立T-S模糊故障树的基础上,以模糊门算法表征事件之间的逻辑关系,确定了基于基本事件模糊概率和故障程度的复杂系统可靠性评估方法,并对事件进行了概率重要度和关键重要度分析.案例分析表明,T-S模糊故障树分析方...     

The Conversion of Dynamic Fault Trees to Stochastic Petri Nets, as a case of Graph Transformation

A model-to-model transformation from Dynamic Fault Trees to Stochastic Petri Nets, by means of graph transformation rules, is presented in this paper. Dynamic Fault Trees (DFT) are used for the reliability analysis of complex and large systems and represent by means of gates, how combinations or sequences of component failure events, lead to the failure of the system. DFTs need the state space solution which can be obtained by converting a DFT to a Stochastic Petri Net: this task is expressed by means of graph transformation rules, and is applied to a case of system.     

A theory of independent fuzzy probability for system reliability

Fuzzy fault trees provide a powerful and computationally efficient technique for developing fuzzy probabilities based on independent inputs. The probability of any event that can be described in terms of a sequence of independent unions, intersections, and complements may be calculated by a fuzzy fault tree. Unfortunately, fuzzy fault trees do not provide a complete theory: many events of substantial practical interest cannot be described only by independent operations. Thus, the standard fuzzy extension (based on fuzzy fault trees) is not complete since not all events are assigned a fuzzy probability. Other complete extensions have been proposed, but these extensions are not consistent with the calculations from fuzzy fault trees. We propose a new extension of crisp probability theory. Our model is based on n independent inputs, each with a fuzzy probability. The elements of our sample space describe exactly which of the n input events did and did not occur. Our extension is complete since a fuzzy probability is assigned to every subset of the sample space. Our extension is also consistent with all calculations that can be arranged as a fault tree. Our approach allows the reliability analyst to develop complete and consistent fuzzy reliability models from existing crisp reliability models. This allows a comprehensive analysis of the system. Computational algorithms are provided both to extend existing models and develop new models. The technique is demonstrated on a reliability model of a three-stage industrial process     

Qualitative temporal analysis: Towards a full implementation of the Fault Tree Handbook

The Fault Tree Handbook has become the de facto standard for fault tree analysis (FTA), defining the notation and mathematical foundation of this widely used safety analysis technique. The Handbook recognises that classical combinatorial fault trees employing only Boolean gates cannot capture the potentially critical significance of the temporal ordering of failure events in a system. Although the Handbook proposes two dynamic gates that could remedy this, a Priority-AND and an Exclusive-OR gate, these gates were never accurately defined. This paper proposes extensions to the logical foundation of fault trees that enable use of these dynamic gates in an extended and more powerful FTA. The benefits of this approach are demonstrated on a generic triple-module standby redundant system exhibiting dynamic behaviour.     

Petri网模型的FTA安全性分析

故障树分析法(FTA)用于静态分析系统失效的可能事件和状态,是分析安全苛求系统可靠性和安全性的一种有效方法。Petri网是并发系统有效的描述和分析工具,但Petri网自身的分析方法无法严格证明其模型满足模拟的系统安全性。该文提出一种用于Petri网模型的安全性分析方法,有效地结合故障树分析法和Petri网可达图分析的各自优点,并实际应用于联锁逻辑模型的安全性分析。     

基于Vague故障树的航空电子系统可靠性分析

由于航空电子系统工作时存在失常态,且其失效行为具有不确定性,因此基于概率论的故障树分析(FTA)模型不适用于分析其可靠性。该文引入Vague集描述底事件的失效行为,并构造了基于三角形Vague集算术运算的与/或门模糊算子,提出一种Vague故障树分析(VFTA)模型。对某直流系统进行可靠性分析表明,VFTA模型比其它模糊FTA模型更灵活、更有效。     

基于故障配置的故障树生成

故障树分析是提高系统安全性和可靠性的有效方法。传统的人工故障树生成方式难以解决当前系统的庞大规模与复杂性的问题,且容易出错。为此,提出基于故障配置的故障树生成方法,引入软件产品线的可变性管理,用于系统故障建模与形式化分析。首先,定义故障特征图模型用于刻画系统故障间的约束关系,基于Kripke结构定义故障标记迁移系统来描述系统的行为;然后,基于模型的语义建立通过模型检测生成故障树的过程;最后,通过时序逻辑描述系统安全属性,利用模型检测工具SNIP验证安全属性进而生成故障树。案例研究验证了该方法的有效性。     

基于模糊故障树的地铁综合监控系统可靠性分析

近年城市交通问题凸显,地铁作为解决城市交通问题的重要方式,其安全稳定运行显得尤为重要。地铁综合监控系统是整个地铁系统安全可靠运行的重要保障,对其可靠性进行有效的评估有着重要的价值。介绍了地铁综合监控系统和模糊故障树理论,运用模糊故障树对地铁综合监控系统可靠性进行分析,并对车站级监控系统的故障进行了定性和定量的可靠性分析,拓展了模糊故障树的使用领域。     

Coverage Modeling and Reliability Analysis Using Multi-state Function

Fault tree analysis is an effective method for predicting the reliability of a system.It gives a pictorial representation and logical framework for analyzing the reliability.Also,it has been used for a long time as an effective method for the quantitative and qualitative analysis of the failure modes of critical systems.In this paper,we propose a new general coverage model (GCM) based on hardware independent faults.Using this model,an effective software tool can be constructed to detect,locate and recover fault from the faulty system.This model can be applied to identify the key component that can cause the failure of the system using failure mode effect analysis (FMEA).     

基于FMEA和FTA的ZPW-2000A轨道电路可靠性分析

针对ZPW-2000A型无绝缘移频轨道电路系统的可靠性问题,提出采用故障模式影响分析（FMEA）和故障树分析（FTA）相结合的方法,对系统进行可靠性研究和分析。通过对系统分析和定义,建立故障模式影响分析表,找出所有可能的故障模式、故障后果、故障检测方法和补救措施等,在此基础上建立系统故障树,求取最小割集,进行定性和定量分析。定性分析判定系统的薄弱环节,定量分析计算顶事件的故障概率、各最小割集的重要度及系统的可靠性指标,通过与相关技术规定比较,验证了该可靠性分析方法的有效性。     

一种新的故障树定性分析方法

提出基于割序集的分析方法以研究故障树顶事件发生时基本事件的动态行为。利用顺序失效符表示事件的顺序失效关系,并将静态门和动态门转化为顺序失效表达式来描述故障树中各种门的动态行为,利用顺序失效表达式构建故障树的割序集。结合实例阐述故障树割序集生成算法的流程。该算法将失效行为表示为长度小于系统中部件个数的有序部件序列,为研究故障树提供了一种新的定性分析方法。     

基于蛛状网拓扑智能变电站“三层一网”通信系统研究

在110kV及以下电压等级变电站中,“三层一网”架构虽然简化了二次系统接线,但实时性和可靠性难以保证。针对传统拓扑结构下的实时性和可靠性无法同时达到最优效果的问题,本文采用“三层一网”架构下蛛状网拓扑结构,仿真结果表明该结构下的通信系统实时性最佳,解决了传统拓扑结构实时性差的问题,并结合算例验证了其可行性;运用故障树分析法定量分析不同结构的可靠性,结果表明蛛状网结构的可靠性更好。为解决研究复杂的通信系统可靠性时传统故障树方法有一定的局限性的问题,本文引入T-S模糊故障理论,建立T-S故障树模型,计算结果表明蛛状网结构下通信系统可靠性最好。根据本文研究可以得到蛛状网拓扑结构能同时提高通信系统实时性和可靠性的结论。     

基于模糊理论动车制动系统故障树可靠性分析

动车组制动系统在可靠性分析过程中存在故障数据的不确定性问题,主要表现为数据的来源不同和事件语义表述不同等,导致很难获取系统事件发生概率的精确数值。因此传统的故障树分析方法对于这类问题的处理不能得到符合现实条件的准确数据结果,故提出运用模糊数学理论将事件的发生概率进行模糊化处理,并结合专家信心指数法通过故障树分析模型计算得出制动系统底事件的模糊概率重要度,并根据各底事件在不同故障状态情况下的模糊概率重要度的大小,找出影响系统可靠性的薄弱环节。通过对兰新客专上运行的动车组制动系统进行分析,结果与动车组制动系统实际运行情况相符合,验证了算法的可行性和有效性。为根据该线路故障的特点制定相应的检修和维护策略给出了理论依据。     

T-S模糊故障树分析方法

提出一种新的T-S模糊故障树分析方法,该方法将模糊逻辑和T-S模糊模型引入到故障树分析中,使故障树具有处理模糊信息的能力.T-S模糊故障树分析中不需要精确了解部件的故障概率,也不需要精确了解故障的机理,从而解决了系统的事件和故障机理的不确定性问题.最后给出了INS/GPS组合导航系统可靠性分析实例.     

A verified realization of a Dempster–Shafer based fault tree analysis

Fault tree analysis is a method to determine the likelihood of a system attaining an undesirable state based on the information about its lower level parts. However, conventional approaches cannot process imprecise or incomplete data. There are a number of ways to solve this problem. In this paper, we will consider the one that is based on the Dempster–Shafer theory. The major advantage of the techniques proposed here is the use of verified methods (in particular, interval analysis) to handle Dempster–Shafer structures in an efficient and consistent way. First, we concentrate on DSI (Dempster–Shafer with intervals), a recently developed tool. It is written in MATLAB and serves as a basis for a new add-on for Dempster–Shafer based fault tree analysis. This new add-on will be described in detail in the second part of our paper. Here, we propagate experts’ statements with uncertainties through fault trees, using mixing based on arithmetic averaging. Furthermore, we introduce an implementation of the interval scale based algorithm for estimating system reliability, extended by new input distributions.     

Fault tree based diagnostics using fuzzy logic

Fuzzy set theory is investigated as a tool for the diagnostics of systems described by means of a fault tree. The objective is to diagnose component failures from the observation of fuzzy symptoms using the information contained in a fault tree. A two-step procedure is used to solve the problem. In this first step, causal reasoning is used to diagnose failure modes, consisting of minimal cut-sets of basic events, from the observation of triggered gates treated as symptoms. In the second step, the authors identify the particular components which have failed based on the diagnosed failure modes. To perform this second step, the solution of a fuzzy relational equation a=∧(S ^T αx) connecting failure mode a to basic events x is derived. With this method, the diagnostics equations can be symmetrically generated and solved in terms of the tree's basic events. The systematic nature with which a diagnosis can be generated from a fault tree lends this method to potential application of object-based programming techniques     

Fuzzy Bayesian reliability and availability analysis of production systems

To have effective production planning and control, it is necessary to calculate the reliability and availability of a production system as a whole. Considering only machine reliability in the calculations would most likely result unmet due dates. In this study, a new modelling approach for determining the reliability and availability of a production system is proposed by considering all the components of the system and their hierarchy in the system structure. Components of a production system are defined as production processes; components of the processes are defined as sub-processes. In this hierarchical structure we could model all kinds of failures such as material and supply, management and personnel, and machine and equipment. In the analysis, a fuzzy Bayesian method is used to quantify the uncertainties in the production environment. The suggested modelling approach is illustrated on an example. In the example, also a separate reliability and availability analysis is conducted which only considered machine failures, and the results of both analyses are compared.     

知识存储与诊断专家系统在低温系统中的应用

为实现EAST低温系统的智能故障诊断,提出一种基于故障树的低温系统知识存储与诊断专家系统。根据故障树模型的结构,设计知识在关系型数据库中的分级存储方式。应用故障树分析法进行故障建模与诊断推理,结合可靠性因子辅助不确定性推理,并以实例说明推理算法。模拟诊断结果表明,该系统具有友好的人机接口,运行稳定且诊断结果及时可靠。     

The reliability of general vague fault-tree analysis on weapon systems fault diagnosis

An algorithm of vague fault-tree analysis is proposed in this paper to calculate fault interval of system components from integrating expert's knowledge and experience in terms of providing the possibility of failure of bottom events. We also modify Tanaka et al's definition and extend the new usage on vague fault-tree analysis in terms of finding most important basic system component for managerial decision-making. In numerical verification, the fault of automatic gun is presented as a numerical example. For advanced experiment, a fault tree for the reactor protective system is adopted as simulation example and we compare the results with other methods. This paper also develops vague fault tree decision support systems (VFTDSS) to generate fault-tree, fault-tree nodes, then directly compute the vague fault-tree interval, traditional reliability, and vague reliability interval.