Possibility theory in “Fault mode effect analyses”. A satellite fault diagnosis application

Matra Marconi Space (MMS) has been developing spacecraft diagnostic support systems for eight years. Keeping in mind the operational constraints of scale and efficiency that guided the design of the first systems, the reasoning paradigms are now refined, in order to improve the solutions. The FMECA, Fault Mode Effects and Criticality Analyses, form a very important category of knowledge compiled during the design phase of a satellite, and used also for diagnosis activities. This paper proposes their extension, allowing a finer representation of the available knowledge, at approximately the same cost, through the introduction of an appropriate representation of uncertainty and incompleteness based on possibility theory. Efficient discriminization techniques exploiting uncertain observations are introduced, and an example illustrates the mechanisms involved in this approach