Qualitative diagnosis of condition systems for multiple subsystem failures

Condition systems are a form of Petri nets that interact with each other and the external environment through condition signals. Some of these condition signals may be unobservable. In previous work, fault diagnosis was defined in terms of observed behavior versus expected behavior of subsystem models under a single fault assumption, where the expected behavior is defined through condition system models, and approximate methods were presented for detection and diagnosis. In this paper, we present an exact diagnosis method for a system that may experience multiple subsystem faults.