Development of ground experiment system for space end-effector capturing the floating target in 3-dimensional space

The purpose of this paper is to develop a set of ground experiment system to verify the basic functions of space effector and the capturing reliability of space end-effector for the free-floating target payload in the three-dimensional space. The development of ground experiment system for space end-effector is essential and significant, because it costs too much to launch a space robot or other spacecraft and carry out operation tasks in space. Owing to the negligible gravity in space, which is different from that in the ground environment, ground experiment system for space end-effector should have the capability of verifying the basic functions of space effector and the reliability of space end-effector in capturing the free-floating target payload in space.

The ground experiment system for space end-effector mainly adopts the hybrid simulation method, which includes the real hardware experiment and software simulation. To emulate the micro-gravity environment, the contact dynamics simulator is applied to emulating the motion state of the free-floating target payload, while the admittance control is used to realize the “soft” capturing of space end-effector to simulate the real situation in space.

With the gravity compensation, the influence of gravity is almost eliminated and the results meet the requirements of the experiment. In the ground experiment, the admittance control is effective and the actual motion state of space end-effector capturing the target in space can be simulated. The experiment results show that space end-effector can capture the free-floating target payload successfully and hopefully have the ability to capture a free-floating target in space.

The system can verify space end-effector capturing the free-floating target payload in three-dimensional space and imitate the motion of space end-effector capturing the free-floating target in space. The system can also be modified and improved for application in the verification of space robot capturing and docking the target, which is valuable for the ground verification of space applications.