Qualitative observer and its application to fault detection and isolation systems

Abstract

Qualitative simulation is one of the main techniques in qualitative reasoning. It has the great potential to solve engineering problems, if only the difficulty of ambiguity can be overcome. On the other hand, in many applications measurements are often available. In this paper a qualitative observer is proposed, which is based on qualitative simulation and applied using a novel technique: observation filtering. This provides a framework in which the measured information can be utilized to reduce accumulated ambiguity and to avoid spurious solutions. Simulated results of qualitative simulation and qualitative observer are compared to show the effect of the new approach. As an application to fault detection and isolation, qualitative extensions of the dedicated observer scheme and the generalized observer scheme are presented.