Partial stabilization of underactuated post-capture combination with inaccurate measurement information and unknown disturbances

This paper aims to address the attitude stabilization issue of post-capture combination with underactuated actuators, measurement inaccuracy and unknown external disturbances during on-orbit servicing. A precise and practical form of underactuated attitude dynamics is proposed for the asymmetric combination with two control torques. With the adopted partial stabilization strategy, a sliding mode controller is first proposed to achieve partial stabilization of the combination against the effect of unknown external disturbances. Through the additional consideration of the measurement inaccuracy in the inertia tensor and the mass centroid, an underactuated adaptive sliding mode controller with compensation laws is proposed in presence of uncertainties and disturbances. Numerical simulations validate the effectiveness of proposed partial attitude stabilization controllers.