【作者】 贺耀文；

【导师】 胡于进；

【作者基本信息】 华中科技大学 ， 机械设计及理论， 2004， 硕士

【摘要】 本文以知识工程的理论为基础,运用面向对象的设计方法建造了一个基于ESP(Expert System Platform)平台的液压系统故障诊断专家系统。本文依次讨论了叉车液压故障诊断专家系统的可行性分析、设计要求、知识获取、知识库设计以及实现过程。在专家知识库设计过程中,我们对知识采用了层次化的表达方式,分为陈述型知识、过程型知识和控制型的知识。对知识的层次化分解有助于加深我们对整个知识系统的理解,加深对关键部件的理解,提高知识的可重用性。在对知识分层次的基础上,我们采用了模块化的设计方法来构造知识库。在本系统的设计中,我们把一些典型的元件或诊断回路作为一个单元体,可以添加到任何一个高一级的系统的诊断体中,通过模块化的设计,提高了效率。在规则集属性的提取过程中,我们采用了绘制故障图的方法,通过顶事件、中间事件、底事件及其相互关系的描述,我们可以清楚的看出事件之间的因果关系,故障图的运用使得规则的提取更加容易。在类库设计过程中,我们运用了软件工程的有关思想,用ER图来表示类及类之间的关系。最后我们从专家系统所做建议的质量、推理技术的正确性、人机对话质量、效率和成本核算五个方面完成了对该专家系统的评价。更多还原

【Abstract】 With our understanding in knowledge engineering and the use of object-oriented design method, we construct a fault diagnose expert system for hydraulic system based on the Expert System Platform (ESP).Orderly we discuss the feasibility of developing a fault diagnose ES for a fork-lift truck, objective to achieve, knowledge acquisition, knowledge base construction and implementation.During the process of knowledge base design, we represent our acquired knowledge in a hierarchical manner and classify them into three subdivisions: description knowledge, processing knowledge and control knowledge. This kind of classification helps improve our comprehension with the whole knowledge base and key component. It also enhances the reusibility of the knowledge base.Based on the knowledge classification mentioned above, we use the method of modularization to construct our knowledge base. Following our design principle, we view the typical component and circuit as an independent module and implement it separately. When we construct a larger system, the well-designed module can be added into it. With the use of this method, we can improve our work efficiency greatly. During the process of production rule extraction, we use a special method to implement it. We use trouble diagram to represent the relation between all kinds of events, which include top events, intermediate events and bottom events. In this way, we can recognize the cause and effect between all the relevant events. The introduction of the trouble diagram makes the production rule extraction much more easy and precise.We adopt the theory of software engineering to design our classes, in the end we figure out our classes and its relations with E-R diagram. Finally we complete our evaluation of our system in five aspects, which includes the quality of the advice proposed by the system, the correctness of reasoning, the quality of the interactivity, efficiency and cost.更多还原