Comparing diagnosability in CS and DES

Abstract

This chapter is concerned with diagnosability analysis, which proves a requisite for several tasks during a system's life cycle. The Model-Based Diagnosis (MBD) community has developed specific approaches for Continuous Systems (CS) and for Discrete Event Systems (DES) in two distinct and parallel tracks. In this chapter, the correspondences between the concepts used in CS and DES approaches are clarified and it is shown that the diagnosability problem can be brought back to the same formulation using the concept of signatures. The main point is the way observations are defined, in a static way in the CS approach and as partially ordered sets (sequences) in the DES approach. In one hand, when temporal information is necessary to discriminate faults, the DES approach gives better results. In another hand, it requires to wait for a certain amount of time, before having the result. These results bridge CS and DES diagnosability and open perspectives for hybrid model based diagnosis.