Abstract: Aiming at rehabilitation training requirement for patients with ankle injury, a novel human ankle rehabilitation robot was designed based on 2RURU/RRtype parallel mechanism. Firstly, motion output characteristic of the mechanism was analyzed and degree of freedom was computed by using the screw theory. The posture angular displacement and angular velocity equations were derived. The workspace of the mechanism was solved based on the numerical search method. Then, kinematic performances were analyzed by using the motion/force transmission index, and the performance distribution map of the mechanism was described. Optimal design of the mechanism was carried out based on the global transmission index. Finally, kinematics simulation was carried out based on ADAMS software, the physical prototype was built and rehabilitation test was performed as well. The results indicate that the rotation center of the designed ankle rehabilitation robot is adjustable, and it has uncoupled kinematic characteristics. After the optimization design, the ratio of the well transmission workspace of the mechanism is improved by 10.8%. The kinematic simulation and physical prototype experimental research show that the motion range of the rehabilitation robot can fully meet the rehabilitation training requirements of human ankle. The paper provides the key theoretical basis for the development of the parallel ankle rehabilitation robot.
Key words:  medical and health instruments; medical rehabilitation robot; mechanism; parallel mechanism; mechanism workspace; sports performance index; kinematics simulation