Modeling and Mitigating Silent Faults in Coupled Discrete Event Systems

Coupled discrete event system have subsystems that share a common transition are subject to model deviation due to wear and tear of subsystem physical components. A fault due to model deviation can result in a fault in a corresponding physical system. Silent faults are faults that can propagate from one subsystem to another due to faults that are modeled as unobservable events. In this work, we investigate the problem of modeling silent faults in coupled discrete event systems with model deviations. Our goal is to introduce properties for subsystem to prevent the propagation of a silent fault. First, we provide a formal definition of deviation for coupled discrete event systems. Then, we provide the sufficient properties for deviation safety of the coupled discrete event system. Finally, using a case study, we show how using these properties can help a designer mitigate the occurrence of silent faults in cyber physical systems.