Fuzzy reaching law sliding mode controller for spacecraft attitude control

Aiming at attitude control of spacecraft, the method of fuzzy reaching law sliding mode is introduced. Firstly, the spacecraft dynamics equation based on angular velocity and kinematic equation based on error quaternion are introduced. Then according to the mathematical model of the satellite attitude control system, the sliding mode controller is designed while the stability of the system is proven by Lyapunov method. To get a better control performance than conventional controllers, a fuzzy reaching law sliding mode controller is designed in which the control law is tuned according fuzzy rules. The fuzzy rules adopt switching sliding surface function as fuzzy control input and control gains as output. Finally the simulation result shows that the proposed scheme can effectively achieve the control target when disturbance exits. Besides, it can weaken the chattering and keep good robustness.