Cascade-saturation fuzzy variable structure control for spacecraft large angle attitude maneuvers

The cascade-saturation method, which the maximum deviation for each maneuver is limited, is used to eliminate the attitude error successively for large angle attitude maneuvers of spacecraft using reaction wheels under the conditions of output torque limited and rate saturated. This method will be applied for the attitude capture and maneuvers control of the spacecraft at any time when the optimum maneuver trajectory is unknown. The design of the sliding mode control is optimized by fuzzy rules, and the structure perturbation and the boundary of the unknown external disturbances are estimated. So that the system trajectory can quickly approximate the sliding plane and the chattering is weaken. Thus the performance of the variable structure control system is improved. Simulation results show that the system is robust to model uncertainties and external disturbances, and it smoothes the system chattering phenomenon.