Weak Diagnosability of Discrete-Event Systems

Abstract

Abstract In this paper, we propose a weaker property for failure diagnosis called weak diagnosability. Weak diagnosability says that, after the occurrence of a fault event, for any continuation, there always exists at least one trajectory of sufficient length along which we can diagnose the occurrence of the fault event. We derive a necessary and sufficient condition for weak diagnosability and develop an algorithm to check the condition. We then extend weak diagnosability to networked discrete event systems which have packet losses and communication delays and call the extension weak network diagnosability. We adopt the transformed automaton technique to deal with packet losses and develop a method for checking weak network diagnosability with respect to packet losses. For communication delays, our results show that they do not change weak network diagnosability when delays are first-in-first-out, but may add time to diagnose the occurrences of fault events.