【作者】 杨鹏；

【导师】 邱静；

【作者基本信息】 国防科学技术大学 ， 机械工程， 2008， 博士

【摘要】 高新技术在武器装备中的广泛应用,一方面极大地改善了装备的性能,使装备功能越来越先进;另一方面显著地增加了装备的技术和结构复杂性,对装备的测试、诊断与维修提出严峻的挑战。主要表现在:测试与诊断能力差、准确性低,测试与诊断时间长、费用高、效率低。经过大量的研究和实践,人们认识到:要想从根本上解决上述问题,必须对装备开展可测性设计。诊断策略优化设计是可测性设计中的一项重要内容,对于降低测试成本,提高故障诊断能力、诊断效率和诊断精度具有十分重要的意义。基于模型的诊断策略优化设计是目前普遍采用的一种设计方法,首先对装备建立一种相关性模型,利用模型所描述的故障与测试的逻辑关系信息开展诊断策略设计与可测性评估。虽然在该技术领域已有不少的理论及应用成果,但是仍存在不少难点问题亟待解决。对此,本文在“装备可测性/机内测试分析、设计与评估技术”项目的支持下,开展理论与技术研究,重点对复杂情况(测试不可靠、存在多故障)下的诊断策略优化设计以及典型复杂结构(多模式、多回路、多层次)系统的诊断策略优化设计等难点问题开展深入研究。本文的主要研究内容与成果如下:1.研究了相关性建模与诊断策略优化设计的基本理论对相关性建模以及基于相关性模型的诊断策略优化设计的基本理论进行了系统总结;在此基础上,针对已有的诊断策略搜索算法难以在复杂情况下既快速又准确地搜索到最优解的问题,以信息启发策略为核心,将一步前向搜索和深度搜索相结合,提出了一种新的搜索算法,即准深度搜索算法,该算法可用于各种复杂情况下的诊断策略优化设计。验证结果表明:该算法可以在计算精度和计算复杂度间获得较理想的权衡,应用它可以快速找到理想的(诊断代价小、效率高)诊断策略,为后续研究奠定了基础。2.研究了复杂情况下的诊断策略优化设计技术(1)针对测试不可靠情形下的诊断策略优化设计问题,应用统计方法构造了故障-测试不确定相关性矩阵;基于该矩阵构造了一种指导诊断策略生成的启发式函数;在此基础上,结合准深度搜索算法,分别针对二值和多值不可靠测试这两种情形提出了诊断策略优化搜索算法。验证结果表明:应用该算法所得到的诊断策略不仅诊断代价小,而且诊断准确度较现有方法大大提高,有效地解决了在测试不可靠情形下的诊断策略优化设计问题。(2)针对多故障情形下的诊断策略优化设计问题,基于相关性模型建立了三类典型多故障的数学模型;在此基础上分析了现有方法发生误诊的机理,进而构造了一种基于布尔逻辑的多故障推理机;基于上述研究,分别针对冗余和非冗余系统这两种情形提出了多故障诊断策略优化搜索算法。验证结果表明:应用该算法所得到的诊断策略可以快速准确地隔离多故障,减少了漏诊或者误诊的发生,有效地解决了多故障情形下的诊断策略优化设计问题。3.研究了典型复杂结构系统的诊断策略优化设计技术(1)针对多模式系统的诊断策略优化设计问题,分析了在不同的系统模式下故障的传播特性,构建了各模式下的故障-测试相关性矩阵;进而提出了一种基于启发式函数的最佳模式顺序生成方法;在此基础上,结合准深度搜索算法,提出了一种多模式系统的诊断策略优化搜索算法。验证结果表明:应用该算法所得到的诊断策略通过模式的优化排序和转换,可以快速隔离出在单一模式下无法检测或隔离的故障,有效地解决了多模式系统的诊断策略优化设计问题。(2)针对多回路系统的诊断策略优化设计问题,根据多回路系统的结构特点,提出了一种快速搜索回路的算法以及一种基于启发式函数的最佳断点确定方法;在此基础上,结合准深度搜索算法,提出了一种多回路系统的诊断策略优化搜索算法。验证结果表明:应用该算法所得到的诊断策略可快速准确地隔离回路中的故障,且使用的断点少,有效地解决了多回路系统的诊断策略优化设计问题。(3)针对多层次系统的诊断策略优化设计问题,根据系统功能层次划分,对每个层级的可更换单元分别构建了故障-测试相关性矩阵;对现有的启发式函数进行改进,使之能根据不同的故障隔离级别要求生成相应的诊断策略;在此基础上,结合准深度搜索算法,提出了一种多层次系统的分层诊断策略优化搜索算法。验证结果表明:应用该算法可以优化生成任何期望故障隔离级的诊断策略,可以满足不同的维修性要求,有效地解决了多层次系统的诊断策略优化设计问题。4.软件开发与工程应用研究基于上述研究成果,设计和开发了计算机辅助可测性建模与诊断策略优化设计软件;以导弹系统为对象,应用该软件工具构建了系统相关性模型,优化设计了诊断策略,并进行了故障仿真注入试验。试验结果表明:本文所设计的诊断策略代价小、诊断准确度高、可准确隔离多故障,达到了可测性设计要求。更多还原

【Abstract】 The performance of weapon equipments has been greatly improved with the widely application of high technology. On the other hand, the complexity of technology and structure of equipments increasing significantly raise challenges in equipment testing, diagnosis and maintenance which include poor testing and diagnosis, low accuracy, low efficiency and high consumption on time and cost. Extensive researches and practices make us recognize that Design for Testability (DFT) must be carried out concurrently with functional design of weapon equipments in order to fundamentally solve these problems.Diagnostic strategy design, as an important aspect in DFT, is crucial for reducing test cost and improving diagnostic accuracy and efficiency. A model-based method of diagnostic strategy design is widely used recently, in which the strategy design and testability evaluation are made following the construction of equipments dependency model.Although there have been numbers of theoretical findings, many complex problems still exist in this area.Supported by the advanced project "Equipments Testability/BIT Analysis, Design and Evaluation Technology", this dissertation makes the further studies on diagnostic strategy design methods mainly aiming at the currently existing key problems in the area, such as design in some typical complex situations (unreliable test, multiple faults) and design for systems with typical complex structure (multiple modes, multiple loops, multiple levels). The main contents and productions of the dissertation are as follows.1. Study on the theories of dependency modeling and optimization designs of diagnostic strategy.In order to accomplish the quickly optimal searching for diagnostic strategy under complex situations, a new searching algorithm, referred to as Quasi-Depth First Search (QDFS) algorithm, is presented by combining existing one-step look-ahead search algorithms with multi-step one. With information gain heuristic strategy as its core, the new algorithm and can be applied in complex situations. Experimental results show that the algorithm can reach an ideal trade-off between accuracy and computational complexity as well as produce optimal/near-optimal diagnostic strategies being of low cost and high efficiency.2. Study on the optimization design technologies for diagnostic strategy in typical complex situations.(1) In the situation of unreliable tests (two-valued and multi-valued respectively). Firstly a fault-test uncertainty dependency matrix is built using statistical method. Based on it, a new heuristic function used to guide the generation of diagnostic strategy is then presented. With the use of QDFS, an optimization algorithm is presented, as well as the construction of several prediction functions which are applied to evaluate diagnostic accuracy. Experimental results show the diagnostic strategies that follows from the proposed algorithm are lower costly and more accurate compared to the existing ones.(2) In the situation of multiple faults (in systems with and without redundancy respectively). First, based on the symptoms analysis of concurrent multiple faults with dependency model, three typical multiple faults mathematical models are constructed. Then a multiple fault inference engine based on Boolean logic is presented following the mechanism analysis of misdiagnosis caused by existing single fault inference engine. Based on the inference engine, an optimization algorithm is presented. Experimental results show the diagnosis of multiple faults is quick and missed or false diagnosis can be avoided.3. Study on the optimization design technologies for diagnostic strategy for the systems with complex structure.(1) In multi-mode systems. First, a series of fault-test dependency matrices for various system modes are constructed by analyzing fault propagation features of each mode. An optimization method of generating optimal mode sequences based on a heuristic function follows and then an optimization algorithm is presented. Experimental results show that the proposed algorithm carries out quick isolation of those faults that cannot be detected or isolated with any single mode.(2) In multi-loop systems. A loop-searching algorithm is presented firstly by the analysis of dependency model of multi-loop systems. There follows an optimization method of generating optimal feedback loop-breaking points based on a heuristic function. Then an optimization algorithm is drawn up. Experimental results show the diagnosis of multiple faults in the feedback loops is quick and with fewer breakpoints applied.(3) In multi-level systems. Firstly fault-test dependency matrixes of each replaceable unit at each level of system are constructed respectively according to the system hierarchy analysis. Then, existing heuristic function is improved in order to generate optimal diagnostic strategies which satisfying various fault isolation requirements. Based on QDFS and the new heuristic function, an optimization algorithm is presented finally. Experimental results show that the proposed algorithm can isolate the faults to any desired level and satisfy different maintainability requirements.4. Study on the software platform developing and the practical application of the methods mentioned above. Based on the researches mentioned above, a CAD software tool is developed for dependency modeling and diagnostic strategy optimizing.The application in a missile system validates the efficiency of the presented methods and software. Following the construction of dependency mode of the system, an efficient diagnostic strategy is derived with the aid of the tool. Then, the results of fault injection experiments and their evaluation show that the proposed strategies make the diagnosis of single fault or multiple faults accurate, quick and low costly, therefore satisfy the testability requirements.更多还原