Design And Optimization Of Three-axis Stabilized Satellite Attitude Control System Using Zero-momentum Reaction Wheels

It was necessary for modern satellites to improve the precision and dependabilityof their control system. The zero-momentum reaction wheel system was always used asthe actuating mechanism of satellites running at steady-state, because it’s simple, trustyand perfect in control accuracy. Based on the attitude control system (ACS) ofthree-axis stabilized satellite running at steady-state, the control algorithms of ACSwere studied, and the application of the multi-objective optimization based on geneticalgorithm in the selection of the torque allocation for flywheel was researched for thepurpose of improving the efficiency and performance of the control system to theutmost, constrained by the control ability of the actual load. The main results achievedin this dissertation were summarized as follows:(1) The simulation model of three-axis stabilized satellite was established. On thebase of the coordinates defined in this paper, the attitude dynamic models andkinematics equations were derived, and then simplified. The mathematic models of theenvironmental torques, such as gravity gradient torque, air torque, sun pressure torqueand residual magnetic moment were deduced.(2) Three control algorithms were studied and proposed. At the beginning of thispart, PID control and its parameter tuning were discussed, then a presentation of fuzzycontroller was given, when it’s used to regulate the PID parameter, it came to a newcontrol method-fuzzy adaptive PID control. At the end of this part, PID control based ongenetic algorithms was designed and applied in the model of the satellite, then theresults of the controller were contrasted with the results of PID control, the simulationproved that it’s feasible and advantaged of PID control based on genetic algorithms.(3) The torque allocation strategy for zero-momentum reaction wheels was studiedand designed. Based on the best installation structure of the wheels and establishedangles in gradient installation structure with uniformly distributed wheels, theapplication of the multi-objective optimization with genetic algorithms in the selectionof the torque allocation for flywheel was studied. The feasibility of the algorithms wasvalidated by simulation, and all the performance indexes were satisfied.It’s significant to the research in control theory of three-axis stabilized satellites.The theory was studied and developed in the dissertation. The engineering constraintswere taken into account in the theories and algorithms researched in the dissertation,and it’s valuable in engineering application.