Automatic mass balancing of a spacecraft simulator based on non-orthogonal structure

In order to simulate a micro-gravity environment for a three-axis air-bearing spacecraft simulator, an automatic mass balancing subsystem is developed. A non-orthogonal slider distribution scheme is proposed to avoid the intrinsic center-of-gravity shift involved in the mass balancing process. The simulator kinematics and dynamics are analyzed, and the relationship between the attitude change and the disturbance torque caused by the center-of-gravity shift is deduced. The recursive least square method is adopted for the centroid deviation estimation. The centroid deviation is then decomposed to the displacements of the sliders. As a result, the simulator could be auto-balanced by controlling the sliders' motions. The proposed mass-balancing algorithm is implemented, and the effectiveness is validated by experiments, which could achieve the final centroid deviation within the range of 5 pm.