Abstract: In order to analyze the difference of driving force of space mechanism in different gravity environments, the single joint manipulator is used as the object to study the difference of DC motor driving force under different gravity environments. Firstly, the dynamic model of the single joint manipulator is derived based on the Lagrange equation. At the same time, in order to analyze the influence of load, friction and speed changes on the driving force of the motor under different gravity environments, a single joint driven mechanical arm test device is designed to carry out under the ground gravity environment, the ground simulated microgravity environment and the falling tower microgravity environment tests. Based on the test data, the difference of the motor drive current of the space mechanism under different gravity environments is analyzed in detail. Based on the experimental data, the friction parameters in the motor dynamics equation are identified, and the dynamic simulation model of the manipulator based on the experimental data is obtained, which provides theoretical and experimental basis for the design and applications of space mechanism dynamics.

Key words: Space mechanism, Microgravity, Motor driving force; Fall tower experiment, Friction parameter