Kinematic Analysis and Gait Planning of a Three-branch Relative Robot for On-orbit Assembly

Automatic assembly of modular structures by space robots is an effective way to realize on-orbit construction of super-large spacecraft. In this paper, a three-branch relative robot for on-orbit assembly of discrete module structure in a structured environment is proposed. Unlike a robot working in an unstructured environment, the robot utilizes a specific structured assembly environment to achieve simple structure and control. At the same time, in order to improve the motion function of the robot and the transportation and assembly efficiency of the discrete module structure, the robot is designed to be composed of three symmetrical manipulators with three degrees of freedom for each manipulator. Firstly, the kinematics model is established according to the structural characteristics of the three-branch robot, and the inverse kinematics solution method is given. Secondly, the three-branch relative robot gait is defined, and the corresponding gait planning algorithm is designed. Finally, some gait planning algorithms are verified by simulation and experiment.