Development of an elbow-forearm interlock joint mechanism toward an exoskeleton for patients with essential tremor

An essential tremor (ET) is a disorder that causes involuntary oscillations. ET patients face serious difficulties in performing such daily living activities as eating, drinking, and writing. We have been developing an exoskeleton to suppress tremors and support the eating movements of ET patients. The objective of this study is to propose a passive mechanism that prevents the appearance of the compensatory shoulder movement without using an actuator. The basic concept of this study is developing the mechanism to coordinate two DoF movement of elbow joint. Two DoF movement of elbow joint is constrained to passive one DoF by our wearable robot. The mechanism of our robot and constrain mechanism is optimally designed to reduce the compensatory movement during eating movement. To develop such mechanism, we first analysed the eating movement to derive the required specification of the mechanism. Then, we proposed a prototype based on the requirement. Finally, we evaluate the effect of the prototype to reduce the compensatory movement. It is confirmed that the proposed prototype had great effect on the reduction. As a future work, we will optimize the structure and the material of the mechanism to reduce the weight of the mechanism.