Kineto-static Analysis of a Compact Wrist Rehabilitation Robot Including the Effect of Human Soft Tissue to Compensate for Joint Misalignment

Abstract

Developing a simple, comfortable rehabilitation robot that can carry out in-home rehabilitation has been a long-time challenge. In this paper, we present a rehabilitation robot with one degree of freedom (DOF) for wrist joint flexion-extension movement. Passive joints have been added to the exoskeleton, forming a four-bar slider crank mechanism, which can reduce unwanted forces due to joint misalignment. A concept of modeling human soft tissue as a passive prismatic joint with spring is introduced in order to achieve the compactness and comfort of the robot simultaneously. In addition, the effects of human soft tissue displacement are compared. A trade-off between robot volume and comfort is discussed. Finally, the kineto-static analysis of the proposed design is conducted to prove the feasibility of adopting this concept in robot-assisted rehabilitation.