A novel fault diagnosis approach based on environmental stress level evaluation

Misjudging intermittent faults as permanent faults is the major cause of the problems of false alarms, Cannot Duplication and No Fault Found in aircraft avionics. To address this problem, we propose an approach for diagnosis of PFs and IFs in the context of discrete event systems models. Since fault events are usually unobservable, it is difficult to discriminate PF from IF events captured in succeeding sensors. Thereafter, the environmental stresses are treated as fault events and a stress level evaluation algorithm based on interval grey relational degree is given to identify the fault events by evaluating the level of the correlative environmental stresses. Finally, an example of aeronautic gyroscope is presented to demonstrate the proposed approach, and the analysis results show the approach is effective and feasible. It is a novel and effective way to discriminate both PFs and IFs of discrete event systems without the assumption of knowing the fault types (permanent faults and intermittent faults) a priori.