Observability and diagnosability of finite state systems: a unifying framework

Elena De Santis, Maria Domenica Di Benedetto

Published 2016-08-10Version 1

In this paper, a general framework is proposed for the analysis and characterization of observabil- ity and diagnosability of ?nite state systems. Observability corresponds to the reconstruction of the system's discrete state, while diagnosability corresponds to the possibility of determining the past occurrence of some particular states, for example faulty states. A unifying framework is proposed where observability and diag- nosability properties are de?ned with respect to a critical set, i.e. a set of discrete states representing a set of faults, or more generally a set of interest. These properties are characterized and the involved conditions provide an estimation of the delay required for the detection of a critical state, of the precision of the delay estimation and of the duration of a possible initial transient where the diagnosis is not possible or not required. Our framework makes it possible to precisely compare some of the observabllity and diagnosability notions existing in the literature with the ones introduced in our paper, and this comparison is presented.