Design and Kinematic Performance Evaluation of Parallel Ankle Rehabilitation Robot

Abstract

The ankle rehabilitation exoskeleton is a critical equipment for foot drop and talipes valgus patients requiring extensive and repetitive rehabilitation training to make up deficiencies of the manual rehabilitation training and reduce the workload of rehabilitation physicians. According to the anatomical structure and motion characteristics of the ankle, an ankle rehabilitation robot with 2-UPS/RRR configuration has been proposed and developed which can realize the approximate coincidence between the centers of the ankle and the rehabilitation robot. Meanwhile, a force/torque information collection platform is constructed to improve the interactivity among the robot, patients and physicians. The kinematic model of this rehabilitation robot is established. The corresponding theoretical workspace is obtained through solving inverse kinematics. The physiological range of activity of the ankle is accurately measured in the whole movement area with the help of the 3-degree-of-freedom of the prototype. According to the autonomous motion of the prototype, the effective workspace is recorded and obtained. The effective workspace of the robot is less than the theoretical workspace. Furthermore, the results show that the percent of contact area in the effective workspace and the physiological range can reach 95% and the rehabilitation robot can provide enough space for the injured ankle. Finally, based on the velocity Jacobian matrix of the robot, the kinematic performance such as the maneuverability and dexterity is acquired. The results show that this rehabilitation robot has no singular position and processes good kinematic performance in the effective workspace.