The aim of diagnosis is to detect and isolate faults according to the observable traces generated by the system. This article concerns multi-steps diagnosis of discrete event systems modelled with ordinary Petri nets. The main contribution is to decide which sets of places must be considered for r-steps diagnosis of some fault transitions or groups of fault transitions. Conditions and algorithms are proposed that lead to sensor selection in order to design diagnosers in a systematic way without expanding the reachability graph of the Petri net models.
Keywords: fault diagnosis, discrete event systems, DES, Petri nets, sensor selection, modelling