[mod.ai] Seminar - Diagnostic Systems

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.