Applying model-based diagnostics to space power distribution

摘要

Abstract: When engineers diagnose system failures, they often usemodels to confirm system operation. This concept hasproduced a class of advanced expert systems whichperform model-based diagnosis. A model-based diagnosticexpert system for a Space Station Freedom electricalpower distribution testbed is currently being developedat the NASA Lewis Research Center. The objective ofthis expert system is to autonomously detect andisolate electrical fault conditions. Marple, a softwarepackage developed at TRW, provides a model-basedenvironment utilizing constraint suspension.Originally, constraint suspension techniques weredeveloped for digital systems. However, Marple providesthe mechanisms for applying this approach to analogsystems, such as the testbed, as well. The expertsystem was developed using Marple and Lucid Common Lisprunning on Sun Sparc-2 workstation. The Marple modelingenvironment has proved to be a useful tool forinvestigating the various aspects of model- baseddiagnostics. This paper describes work completed todate and lessons learned while employing model-baseddiagnostics using constraint suspension within ananalog system. !7