Model-based diagnosis in SOPHIE III

This paper describes the model-based diagnostician used in SOPHIE III. This diagnostician is capable of localizing faults in analog circuits such as DC power supplies. Although it presumes that the cir-cuit contains a single fault, it introduces a variety of important model-based techniques: (1) it uses models of component behaviors to perform first-principles reasoning to detect conflicts and corrobo-rations with observations, (2) it considers a compo-nent to be faulted if its removal would eliminate all conflicts yet preserve all corroborations, (3) it uses propagation of constraints with numerical ranges, (4) it uses fault mode information to eliminate com-ponents from consideration, and (5) it provides a smooth integration with rule-based diagnostic rule