Diagnosability Analysis of Real Time Hybrid Systems

A method of analyzing fault diagnosability has been proposed for real time hybrid system (RTHS) models. The RTHS modeling formalism is presented and the properties of such models under measurement limitation is discussed. A definition of diagnosability of these models is adopted from the literature on discrete event systems (DES). Based on the measurement limited model, an algorithm for construction of a diagnoser is presented. It is then argued that the diagnosability condition of the diagnoser which has been shown to be necessary and sufficient for DES diagnosability fails to hold for many systems, of which hybrid system is an example. This is because the abstraction employed in formulating the DES models from hybrid systems obliterates an important property of the transitions namely, their fairness. Incorporating this property the diagnosability condition over the diagnoser is suitably modified.