Fuzzy Sliding Mode Control of a Spacecraft Attitude Tracking System

The main problem addressed is attitude tracking control of a rigid spacecraft with uncertain inertia matrix and external disturbances. A fuzzy sliding mode control approach is presented based on relative kinematics and dynamics equations. The advantage of using relative attitude kinematics and dynamics equations to construct control law is that it can convert tracking control problem into regulation control problem, which simplifies the design problem. The control scheme integrates the fuzzy logic and the sliding mode control, and the control discontinuity is smoothed inside a thin boundary layer using the fuzzy logic so that the chattering phenomenon in a sliding mode control system is eliminated. Numerical simulations are included to demonstrate the effectiveness of the proposed control scheme.