Multiple Faults Diagnosability Criteria in Hybrid Control Systems

Lots of diagnosis approaches proposed in the literature are based in the assumption of single faults. This assumption may result to erroneous diagnosis statement in case where multiple faults occurs. Thus multiple fault diagnosis is a challenging field particularly in the control of large scale complex systems that can be viewed as hybrid systems. The main reason is that multiple faults are hard to detect because their consequences can mask or compensate to each other. The goal is to detect multiple faults as early as possible and provide a timely warning. A key issue is to prevent local faults to be developed into system failures that may cause safety hazards, stop temporarily the production and possible detrimental environment impact. In this paper we discuss the notion of multiple faults diagnosability of Hybrid Systems in the framework of Hybrid Input Output Automata (HIOA). We present a methodology for multiple faults diagnosis imposing the conditions for a Hybrid System to be diagnosable. The proposed approach can be applied to a wide rage of systems since Hybrid Systems involve both continuous and discrete dynamics. The proposed method is tested on a two tank system.