End-effector Weak Link Upper-limb Rehabilitation Robot

Abstract

Upper-limb rehabilitation robot often link user with wearable exoskeleton or end-effector. But both of them have some inherent shortages. Facing over-constrained problem, exoskeleton pattern has strict demands for both construction design and control performance, which lead to complex controller and mechanical structure, and needs accurate measurement of user limb parameters. Single arm end-effector link pattern has a limit on the amount of DOF under control, that means the joint angle stats of upper-limb are often uncertain, so it is hard for upper-limb joints to get sufficient movements. Dual-arm end-effector link pattern is still strong link at present, robot and user fasten together. Though overcome shortages of single arm end-effector link pattern, it also has to face over-constrained problem as wearable exoskeleton. In order to overcome the shortages while hold the advantages, in this paper end-effector weak link pattern was proposed according to the pattern that physiotherapist bring patient’s limb to move hand-by-hand. A no fasten assistant arm is added based on single arm end-effector link pattern, and achieve humanoid rehabilitation training with dual arm cooperation. Through analysis, the shoulder and elbow joints of user can get sufficient rehabilitation training without over-constrained problem in this end-effector weak link pattern. Experiments with healthy subjects show that compared with single arm end-effector link pattern. End-effector weak link pattern can enlarge user’s shoulder internal/external rotation average range over 50° in this experimental rehabilitation motion, namely has more comprehensive rehabilitation training ability than single arm end-effector link pattern.