A low-cost microgravity simulating system for motion control study of space robot

The simulation of space microgravity environment is indispensable during the development of space robot since its performances should be examined and enhanced before sent into space. However, the existing methods, such as air flotation method, hanging wire method and buoyancy method, etc., are very expensive and complex. A low-cost microgravity simulating system is proposed in this paper. In this system, a horizontal adjusting mechanism is proposed to keep the robot moving in a horizontal plane; a gravity compensation mechanism is proposed to compensate the force and torque of gravity during the movement; furthermore, several flexible chains and climbing rods are designed to simulate astronauts' climbing outside space station freely, but the robot is very likely to vibrate during the movement, so a new hybrid force/position controller based on the joint servo-drive characteristics model is proposed to diminish this vibration. Experiment has been done on this system with a humanoid space robot and experimental results show that this system is very suitable for motion control study of space robot in microgravity condition and the proposed hybrid force/position controller is easy and valid.