Online Fault Diagnosis of Discrete Event Systems Modeled by Labeled Petri Nets Using Labeled Priority Petri Nets*

The problem of fault diagnosis of discrete event systems (DESs) concerns the capacity to detect the occurrence of fault events. In this work, we present a new fault diagnoser that uses labeled priority and λ-free diagnoser Petri nets to diagnose the fault occurrences of DESs modeled by Petri nets, which may be bounded or unbounded. By analyzing the diagnoser Petri net possible states reached after firing transitions labeled by the observable events, the diagnoser can infer about the fault occurrence. In order to allow the diagnoser to analyze the possible reachable states of the λ-free diagnoser Petri net and diagnose the fault occurrence, we propose a new approach for the state estimation of λ-free Petri nets. For a class of Petri nets, including some unbounded Petri nets, the diagnoser proposed here has a structure that does not grow indefinitely due to event observations, making the diagnoser able to perform the online diagnosis of a class of Petri nets that previous works are only able to diagnose with structures that are likely to grow indefinitely for specific sequences of event observations.