Design and Control of the Portable Upper-limb Elbow-forearm Exoskeleton for ADL Assistance

This paper proposes a portable Unilateral Elbow- Forearm Exoskeleton (UEFE) for assisting chronic stroke patients in the activities of daily living (ADL). UEFE provides users 2DoFs assistance: elbow flexion/extension (eF/E) and forearm pronation/supination (eR). Other than eF/E, forearm rotation is equally crucial for completing ADL tasks; however, limited exoskeletons provide eR assistance for users in ADL. Even though some existing exoskeletons are equipped with eR joints, those devices are not practical to use in ADL due to their heavy weight, insufficient assistance, and obstructing handles. In UEFE, both active joints are actuated by Series Elastic Actuators (SEA) through Bowden cables to ensure safe interactions and a lightweight solution. The design of UEFE is based on the ADL requirements, which include the range of motion (ROM) and torque. The handle-free feature also allows users to pick up objects in ADL. A pill-taking task with impedance control demonstrates the feasibility of using the UEFE in ADL assistance.