leff%smu@RELAY.CS.NET (11/12/86)
Dr. William P. C. Ho Department of Computer Science and Engineering Southern Methodist University IEEE Computer Society Meeting, October 23, 1986 Diagnosis is the process of determining the cause (set of one or more physical component faults - "hypothesis" give the effect (set of one or more behavior deviations - "signature"), for a given mechanism. Ambiguity in interpreting fault signatures is the diagnosis problem. I am developing an approach for functional diagnosis of multiple component faults in mechanisms based on the "constraint satisfaction" paradigm (as opposed to "heuristic search" of "hypothesize and test"). Component faults and behavior deviations are both represented qualitatively by a set of 5 possible state values. Diagnostic reasoning is performed with these representations based on an effect calculus which combines more than one single fault effect into one single multiple fault effect quickly, without simulation. Diagnostic reasoning, encapsulated in a set of logical inference rules, is used to generate constraints, as implications of observed effects, which prune away subspaces of inconsistent hypotheses. The result is a complete set of consistent hypotheses which can explain all of the observed effects.