ON-ORBIT SUPERVISOR FOR CONTROLLING SPACE SYSTEMS

MODERN SPACECRAFT CONSIST OF SEVERAL COMPLEX SUBSYSTEMS, SUCH AS THE STRUCTURE SUBSYSTEM, THERMAL MANAGEMENT SUBSYSTEM, ATTITUDE CONTROL SUBSYSTEM, ETC. INCREASING THE OPERATIONAL LIFE INVOLVES IMPROVING THE RELIABILITY OF EACH COMPONENT AS WELL AS PROVIDING FAULT DETECTION, ISOLATION AND RECOVERY (FIR) SYSTEMS. AN INNOVATIVE APPROACH USING A HIERARCHICAL EXPERT SYSTEM IS PROPOSED THAT WILL PROVIDE INTELLIGENT FDIR AT BOTH THE SUBSYSTEM AND SYSTEM LEVELS. THE PROPOSED SYSTEM WILL CONSIST OF TWO LEVELS. EACH SUBSYSTEM WILL BE MONITORED BY ITS OWN EXPERT SYSTEM. A SYSTEM LEVEL MONITOR WILL THEN PROVIDE HIGH-LEVEL FDIR CAPABILITIES. TO THE EXTENT POSSIBLE, THE LOCAL (SUBSYSTEM) MONITORS WILL PROVIDE THE REQUIRED FAULT-TOLERANCE. ONLY FAILURES THAT CANNOT BE COMPENSATED FOR WILL BE COMMUNICATED TO THE SYSTEM LEVEL SUPERVISOR. DISTRIBUTED PROCESSING WILL THEN BE POSSIBLE, AND THE SMALL LOCAL KNOWLEDGE BASES WILL ENSURE REAL-TIME RESPONSE. MEMORY AND INTERFACE REQUIREMENTS WILL ALSO BE SIMPLIFIED. THE SUPERVISOR WILL BE DESIGNED WITH A CLEAR SEPARATION BETWEEN THE KNOWLEDGE BASE AND THE INFERENCE MECHANISM, THUS MAKING IT EASILY ADAPTABLE TO OTHER APPLICATIONS. THE COMMERCIAL APPLICATIONS FORESEEN INCLUDE MONITORS FOR FLY-BY-WIRE AIRCRAFT SYSTEMS, MISSILE SYSTEMS, AND INDUSTRIAL PROCESS CONTROL.