Abstract: Aiming at the existent of repeatability and indetermination factor in the fault diagnosis, a fault diagnosis improved method based on fuzzy relations is proposed. It integrates the fuzzy theories to the fault diagnosis, comprehensively considers both sides of the minimal cut set of the fault tree and basic component unit, designs the diagnostic process of the fault tree, improves the faults which repeat diagnosis in fault diagnosis of the former and the system diagnosis is optimized. By comparing with the other methods on the subsystem of airplane hydraulic pressure, this method can demonstrate the correctness of the result and save the diagnosis time.

Key words: fault diagnosis, event sequence, basic component unit, fuzzy diagnosis

摘要： 针对故障诊断中存在的重复诊断问题和不确定性因素，提出了一种基于故障树的模糊故障诊断改进方法。该方法将模糊理论融入到故障诊断中，综合考虑了系统故障树的最小割集和基本组成单元两方面的因素，重点设计了故障树的诊断流程，改进了以往故障诊断中出现的重复诊断的缺陷，优化了诊断过程。以飞机液压子系统为平台，与其他方法进行比较，得出该方法可以保证结果的正确性，并能节省诊断时间。

关键词: 故障诊断, 事件序列, 基本组成单元, 模糊诊断