Expert diagnostic system

Abstract

The Expert Diagnostic System (EDS), an Automatic System Level Test Tool, is a hybrid knowledge based diagnostic system under development for use in diagnosing failures in Westinghouse Avionic Systems. The EDS contains both shallow and deep knowledge reasoning. Expert emperical (Shallow) Knowledge is captured and represented using rules in OPS5 [1,3] production system format. These rules are applied to the Fault Detection (FD) test result using OPS5 inferencing to localize failures to a failure class and subsequent to a failure subclass using Unit Under Test (UU'I') failure heirarchy. Once a failure subclass has been selected, control is transferred to deep reasoning inference engine. Deep reasoning loads and creates a frame based model pertaining to the failure subclass under consideration. This model describes the UUT signal flow and connectivity of the system components in relation to the failure subclass. This model is best-first searched using heuristics for best probing locations to perform more tests. This process continues until failure has been isolated to component. This paper is a description of the concepts, knowledge representations and n',ethodologies used by EDS.