Design and control of a position servo system in the zero gravity simulation of space manipulators

For the zero-gravity simulation of space manipulator, a position servo system is designed in this paper. The position servo system is composed of five servo platforms, which are used to track the joints of space manipulator, to ensure the slings keep vertical when the space manipulator is moving. Each servo platform consists of two CCD cameras, two servo motors, two orthogonal linear motion systems and a control computer. Using CCD cameras, the relative distance between manipulator joint and servo platform can be measured with no contact. Based on the measured distance information, platforms are controlled using PD controller to track the joints of space manipulator. In order to verify the tracking accuracy of servo platform with certain measurement error, numerical simulations are implemented. Simulation results show that the designed servo system can satisfy the zero-gravity simulation requirements of space manipulator.