Abstract:

Aiming at the problem about high frequency chattering caused by flexible spacecraft′s sliding mode variable structure control torque, an intelligent fuzzy control algorithm of flexible spacecraft was proposed. Firstly, fuzzy control algorithm and sliding mode control algorithm were combined, and the exponential approach law parameters were fuzzy based on the size of switching function and derivative of switching function. Secondly, the continuous saturation function to replace symbolic function in sliding mode variable structure controller was used. Finally, the boundary layer thickness was adjusted by the sliding mode boundary′s degree. As a result, the boundary layer thickness was controlled, and the problem about high frequency chattering was solved. Simulation results demonstrate that the algorithm can improve high frequency chattering obviously and flexible spacecraft′s vibration suppression can be accomplished with faster convergence.

Key words: fuzzy control, sliding mode control, attitude control, boundary layer thickness, continuous saturation function, high frequency chattering, flexible spacecraft