Modeling method of fuzzy fault Petri nets and its application

In order to overcome the shortcomings of simulating fault spreading, diagnosis and reasoning in fuzzy Petri nets and fault Petri nets, the concept and modeling method of fuzzy fault Petri nets ware put forward. The transition rules and consequences were defined from four types, i.e, one cause and one effect, one cause and several effects, several causes and one effect, competition pattern, to simulate the dynamic running process and reflect the inherent characteristics of the fault spreading. By applying the modeling method of fuzzy fault Petri nets in fault reasoning and diagnosis, the thought of combining the forward reasoning and backward reasoning was proposed, and corresponding algorithm was given. This method was verified by the example of insufficient pressure of hydraulic system. The results show that the forward reasoning can simulate the process of fault spreading, and backward reasoning can carry out fuzzy reasoning perfectly, and so the method is practical.