Spacelab life sciences-1 electrical diagnostics expert system

Abstract

The Spacelab Life Sciences-1 (SLS-1) Electrical Diagnostic (SLED) expert system is a continuous, real-time knowledge-based system to monitor and diagnose electrical system problems in the Spacelab. After fault isolation, the SLED system provides corrective procedures and advice to the ground-based console operator. The SLED system uses the Unit (frame) of KEE to represent the knowledge about the electrical components and uses KEE-Bit-maps to represent the electrical schematics. The diagnostic logic, stored as a set of LISP structures, mirrors that in the malfunction procedures defined in the Spacelab Flight Data File Malfunction Procedures Handbook (JSC-18927) of NASA. The SLED system utilizes downlink telemetry data as input. The system performs some initial screening of the data in order to recognize patterns representing serious problems, and updates its knowledge about the status of Spacelab every 3 seconds. Important parameters are monitored via Active-Values within KEE. The Active-Value kicks off the diagnostic analysis to determine the source of the problems if any problem has been identified. The system supports multiprocessing of malfunctions and allows multiple failures to be handled simultaneously. The user can examine each of the reported problems and receive corrective advice related to each problem. Information which is readily available via a mouse click includes: general information about the system and each component, the electrical schematics, the recovery procedures of each malfunction, and an explanation of the diagnosis. A rich set of user interfaces is provided in SLED. Various tools have been included which allow a non-programmer to define new diagnostic procedures, define and update schematics of the electrical system, and to change the SLED model by changing the graphical representation. Each tool and function has explanatory prompts to aid the user.