Preliminary design and development of an active suspension gravity compensation system for ground verification

A new active suspension gravity compensation system (ASGCS) is developed to offload the gravity of spacecraft or satellites for ground verification. The ASGCS is of six degrees of freedom (6-DOF), including a compensation stage of 3-DOF translation and a gimbal of 3-DOF rotation. A buffer-assisted pinion-rack mechanism is developed to substitute the traditional cable suspension unit, which enables the proportion of gravity compensation is tunable. A new 3-DOF gimbal that is suitable for objects of various sizes and arbitrary shape is developed. Hence, the test object attached to the ASGCS can be free-floating as it is in the outer space. Furthermore, a prototype of the ASGCS is developed, and the dynamic model and kinematic model are derived. Experiments are conducted with the aid of a 6-DOF hybrid coordinate manipulator. The results demonstrate that the ASGCS successfully tracks 6-DOF trajectories of a typical docking task and compensates for 95% of the gravity.