A general algorithm for pattern diagnosability of distributed discrete event systems

International audienceDiagnosability is an important system property that determines at design stage how accurate any diagnostic reasoning can be on a partially observed system. A fault in a system is diagnosable iff its occurrence can always be deduced from enough observations. The centralized diagnosability approaches lead to state explosion since they assume the existence of a monolithic model of the system. This is why very recently the distributed approaches for diagnosability began to be investigated, relying on local objects. On the other hand, diagnosis objectives are generalized from fault event to fault pattern that can represent multiple faults, repeating fault, sequences of significant events, etc. For pattern case, most existing approaches are centralized. In this paper, we propose a new distributed framework for pattern diagnosability. We first show how to recognize patterns by incrementally constructing local pattern recognizers. Then we propose a structure called regional pattern verifier constructed from the subsystem where the pattern is completely recognized before showing how to abstract the necessary and sufficient diagnosability information to further save the search space. Then the global consistency checking is based on another local structure called abstracted local twin checker to analyze pattern diagnosability. The correctness of our distributed algorithm is theoretically proved and its efficiency experimentally demonstrated by the results of the implementation