This paper details the design and implementation of a fuzzy controller for the ASTREX flexible space structure model. the novel control strategy is the first attempt to apply fuzzy logic to the feedback control of a large-scale structure system. The ASTREX system at Edwards Air Force Base consists of three flexible trusses, joined to a flexible base system and culminating in as line-of-sight positioning instrument. Smart control of each truss is accomplished by three axial piezoelectric actuators on each truss, and six bending sensors. Two sensors are grouped with each actuator, in collocated and nearly collocated positions. control system design procedure is detailed. The open-loop system is simulated to determine the appropriate universes of discourse for the input fuzzy membership functions. Output magnitude of the controller is determined by the dynamic range of piezoelectric actuators. The architectural design of fuzzy logic controllers in currently an open issue. there exist many different forms of fuzzy logic controllers, and the performance characteristics of each type cannot generally be determined a prior. Results of preliminary investigations in to the type of fuzzy logic controller necessary for efficient control of flexible structures are shown using simulations involving partial models of one beam of the ASTREX flexible satellite.
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