A Portable and Spring-guided Hand Exoskeleton for Exercising Flexion/Extension of the Fingers

Abstract

In this paper, we developed a portable and spring-guided hand exoskeleton system for exercising flexion/extension of the fingers. The exoskeleton was designed with a simple structure to aid finger motion with one degree of freedom (DOF). The desired joint trajectory of the exoskeleton was determined based on the user joint ROM and general finger motion obtained by the hand flexion/extension experiments. The design of the linkage structure was optimized to maximally satisfy the desired trajectory. A spring attached to the structure generates the force to guide the fingers toward the desired posture when they deviate from the desired position. We used a finite element method (FEM) to analyze the transmitted moments for MCP and PIP joints. A prototype of the device was fabricated, and the performance of the system was experimentally verified. The experimental results of the finger motion indicated that the proposed system provided good guidance for flexion/extension of the fingers. Furthermore, the results of the force distribution experiment verified that the joint moments by the system are matched to the expected moments by FEM analysis. Thus, the CPM device successfully guided the users fingers along the desired trajectory and distributed the expected moments to the joints.