<title>Troubleshooting based on a functional device representation: diagnosing faults in the external active thermal control system of Space Station Freedom</title>

Abstract

This report describes an ongoing effort to apply the functional modeling (FM) approach to the representation of and reasoning about engineered artifacts. The application domain is the external active thermal control system (EATCS) of the FREEDOM space station. The intuitions behind FM are threefold. First, knowing the purposes of a device allows organization of the causal understanding of how a device works. Second, in FM, causality is represented in modular chunks which are indexed by the purposes of the device and its interrelated subsystems. Finally, the global behavior of a device in a given situation can be understood by composition of the relevant causal net fragments. These starting intuitions provide a framework for organizing calculations about a device and for performing a limited type of simulation with the organized ensemble.© (1993) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.