【作者】 许志铭；

【导师】 黄文涛；

【作者基本信息】 哈尔滨工业大学 ， 机械电子工程， 2009， 硕士

【摘要】 从包含大量矛盾、冗余、重复的设备运行状况征兆信息中进行诊断知识的获取,是整个智能故障诊断过程的核心,也是建造智能诊断系统的重点和难点。在实际的诊断知识获取过程中,常常由于所得到的知识内容不完整、结构不完备而无法获取到完备的故障诊断知识。目前故障广泛应用的各种故障诊断知识获取方法多是针对诊断信息完备的情况,导致在故障诊断的知识获取中无法充分利用不完备诊断信息,降低了故障诊断知识获取的有效性和诊断结果的正确率。本文结合故障诊断问题的特点,总结了故障诊断中不完备信息的产生原因,研究了不完备诊断信息的语义解释,并给出不完备故障诊断信息系统的定义。结合现有的不完备信息系统的扩充关系模型,建立了一种适合故障诊断不完备决策系统的关系模型,用来描述含有不完备信息的诊断知识之间的关系。在此基础上,给出完备与不完备故障诊断决策流图的定义,将不完备故障诊断决策流图中的节点定义为由征兆属性和其取值联合描述的二元组;提出将不完备故障诊断决策流图中的分支区分为有向和无向相结合的描述方式,并给出了采用流经分支的对象集合作为分支描述参数的思路,建立了计算流经各种不同分支上流量的公式。由此,建立了一种适合于包含不完备诊断信息的故障诊断知识的图形化方法。本文分析了不完备故障诊断决策流图中隐含的决策规则,并采用置信度和覆盖度的概念作为决策规则的评价指标。针对不完备故障诊断决策流图,分别进行了层次约简和节点约简。约简后得到的不完备故障诊断决策流图不损失原有的故障诊断数据信息且不含冗余的信息,以最简的方式表达了征兆属性和决策属性间的关系。故障诊断应用软件可以完成基于流图的完备或不完备的故障诊断知识获取,可视化整个知识发现过程。本文对应用软件的设计思想与开发方案进行了简要的阐述。另外,本文以船用柴油机故障诊断为例进行了研究,进一步说明了应用软件的使用方法和有效性,验证了本文研究成果的正确性。更多还原

【Abstract】 It’s a key for a intelligent fault diagnosis process to acquire effectiveknowledge from a great deal of symptomless information about equipment functionstatus. Repetitious. Most of the fault diagnosis means, which are widely used atpresent, are for the complete fault dianosis system. While incomplete informationabout fault object is usually gained because practice is restricted by objectiveenvironment and factor. So a new method aimed at incomplete fault dianosis systemis needed to make full use of the information, and to boost the validity of theknowledge acquisition for fault dianosis.Main contents of this paper are as follows:According as the character of the fault diagnosis problems, this paper hassummarized the reasons why the incomplete information exsisted in the faultdiagnosis, has investigated the explanation for the incomplete diagnodsisinformation, has definated the incomplete fault diagnosis information system.Combining with the exsisted relation former for the incomplete information, thepaper has established advanced-restricted tolerance relation. This relation is fit forthe incompleted fault diagnosis information system to describe the connectionamong the incomplete information.The paper has definated the complete and incomplete fault diagnosis decisionflow graphs, has introduced a binary-group including symptom attribute and itsvalue to definate circumscribe the notes in the incomplete fault diagnosis decisionflow graphs, has distinguished between the directing embranchments and theundirecting embranchments, has adopted the set of the objects by theembranchment to characterize a embranchment and definated the flux formula of aembranchment. On the basis of all above, a graphics method is introduced toexpress the incomplete diagnosis knowledge.The paper has analysised the connotative decision rules in incomplete faultdiagnosis decision flow graphs, and has imported the concept of certainty andcoverage factors as the judgement for decision rules. Tier reduction and notereduction are two steps for the structure reduction, the paper has explained how toreduct the tiers and notes respectively. The reducted incomplete fault diagnosisdecision-making flow graphs doesn’t lost any intrinsic diagnosis information anddoesn’t contain any redundant data, it delivers oneself of the relations between thesymptom attributes and the decision attributes. Otherwise, fault diagnosis of diesel engines for ships has been taken as an example to introduce how to use the softwareand how resultful the software is. The example has validated the production of thepaper likewise.更多还原