本文概述了故障诊断技术在国内外发展及各种故障诊断技术的理论方法,针对定性符号有向图(SDG)故障诊断技术在定量信息表达虚假解多、分辨率差等缺点,在定性SDG故障节点引入阈值的概念,将符号有向图节点偏差模糊化为定性模糊偏差,建立了基于SDG模型和模糊融合的故障诊断方法,包括SDG建模、故障源数检验和故障诊断等步骤。 This paper summarizes the development of fault diagnosis technology at home and abroad and various fault diagnosis techniques theoretical methods. In view of the drawbacks of the qualitative symbolic digraph (SDG) fault diagnosis technology in the quantitative information expression of false solutions and poor resolution, the qualitative SDG fault This paper introduces the concept of threshold into the node and fuzzifies the deviation of the node of the digraph into the qualitative fuzzy deviation. The fault diagnosis method based on SDG model and fuzzy fusion is established, including SDG modeling, fault source checking and fault diagnosis.