A methodology for multiple and simultaneous fault isolation

In this paper, a methodology is proposed to deal with the problem of multiple and simultaneous fault isolation on large systems. The goal which is pursued, is to merge already in place fault indicating signals and model-based fault indicating signals (i.e. the residuals), in order to solve the isolation problem. Behind this goal, the problem of the minimal number of residuals is addressed. This includes the answer to the question: Do we really need model-based residuals to completely solve the diagnosis problem? To handle this diagnosis problem, logical tools and formulas derived from the set theory are used to describe sets of decisions. To demonstrate the efficiency of the method, two examples are presented. The first one, of academic nature, aims at illustrating comprehensively the proposed method. The second one comes from a real system.