Enhanced Kapandji test evaluation of a soft robotic thumb rehabilitation device by developing a fiber-reinforced elastomer-actuator based 5-digit assist system

Abstract The main function of human hands is to grasp and manipulate objects, to which the thumb contributes the most. Various robotic hand rehabilitation devices have been developed for providing efficient hand function training. However, there have been few studies on thumb rehabilitation devices. Previously, we proposed a soft thumb rehabilitation device which is based on a parallel-link mechanism, driven by two different types of soft actuators. In this study, the device was integrated into a 5-digit assist system, in which fiber-reinforced elastomer actuators with improved bending angles, forces, and degrees of freedom were assembled onto a forearm socket. The device was evaluated by an enhanced Kapandji-Test, which included also a pressing force measurement in addition to the reachable positions of the thumb on the opposing fingers. The results showed that with the proposed approach, thumb functions for hand rehabilitation could be realized, which paves the way towards a full hand rehabilitation package with the 5-digit soft robotic hand rehabilitation system.