"Physical Negation" Integrating Fault Models into the General Diagnostic Engine

Abstract

The General Diagnostic Engine (GDE) provides an elegant and general framework for model-based diagnosis. However, like many other diagnostic systems, GDE's device models capture only the correct, or intended, behavior of its components. It is lacking an important part of diagnostic reasoning: knowledge about how components may behave when they are faulty. This fact can limit the performance of GDE considerably. We present a solution for integrating the use of fault models into GDE in a very homogeneous way, a system called GDE +. Unlike the basic GDE, it can not only exploit contradictions between the assumed correct behavior of components and the observations, but also analyze whether the faultiness of components would really explain the observations. Based on an extended version of the ATMS, GDE + is able to prove the correctness of components and to rule out implausible diagnostic hypotheses.