Fault diagnosis method based on extension case-based reasoning

Extension case-based reasoning is a kind of knowledge reasoning method which is the combination of the extenics and case-based reasoning. Firstly, the representation of extension case using compound element was introduced, and the similarity computing method of fault symptom with interval value was given. Secondly, the reasoning process of extension case was analyzed; in the retrieve of extension cases, rough set method was adopted to confirm weight of fault symptom, and search strategy guided by rules was proposed; in the reuse of extension cases, conductive transformation was adopted to fulfill the reuse of extension case according to different search results; in the revise of extension cases, increasing and decreasing transform were adopted to add or delete fault symptoms of reused extension case and change their weight; in the retain of extension cases, three retain modes of revised extension case were discussed, including adding, deleting and replacing. Thirdly, the fault diagnosis process of this method was explained by an application case, and the time complexity of extension case retrieve was analyzed. By the comparison of the proposed search strategy and global search strategy, it is known that using the proposed search strategy can increase search efficiency and improve diagnosis speed.