Attitude Tracking Control Based on Adaptive Sliding Mode Technique with Double Closed Loop for Spacecraft Near Small Body

An adaptive sliding mode tracking control scheme with double closed loop is proposed for the spacecraft attitude tracking near the irregular small body in the presence of uncertainties and external disturbances. Firstly, the general formulation of the spacecraft equations of attitude motion near irregular small body is derived considering the irregular gravity gradient torque. Then sliding mode laws are established both in an inner control loop and an outer control loop based on Lyapunov stability theory. The unknown upper bounds of the uncertainties and external disturbances are estimated through adaptive technique. The integral switch control is employed in the outer loop to track the attitude angles and resist the disturbances, and a dynamical sliding mode control approach is proposed in the inner loop to resist the disturbances and vibration. Finally, spacecraft Maneuvers near one small body are adopted for numerical simulation, and the results demonstrate the effectiveness of the proposed scheme.