Abstract: This paper presented a novel method for fault diagnosis of a proposed sequential discrete event mechatronic (SDEM) system based on Petri net. A timed series connection of sequential discrete event Petri net was defined to model the SDEM system. Time measurement of transition was considered as a statistic. A Bayes based test certification method was put forward and applied in the significant test of variance difference. The prior knowledge was well combined with the real time monitoring information based on the proposed method. It was used in fault diagnosis of an automatic material transfer system and the results illustrate the validity and the feasibility of the method.

Key words: sequential discrete event, fault diagnosis, Petri net, Bayes method