WRES: A Novel 3 DoF WRist ExoSkeleton With Tendon-Driven Differential Transmission for Neuro-Rehabilitation and Teleoperation

In this letter, the authors proposed a new wrist exoskeleton designed to provide kinesthetic feedback to the wrist user's joints for rehabilitative, teleoperation, and virtual environment interaction purposes. The design process focused on the need to use the interface as the end-effector of a whole bimanual upper limb exoskeleton system, composed of two exoskeleton arms with 7 DoF each and two hand exoskeletons for all the fingers. The guideline of the design pointed to reach a tradeoff between high transparency and low weight. In addition, both the compactness and mass distribution have played an important role in the design process due to the need to perform bimanual task and interaction. The proposed device was designed adopting a tendon-cable transmission for all the three joints. A differential transmission solution has been adopted to actuate the flexion/extension and radial/ulnar deviation joints, which allows to achieve lower inertia and higher compactness than a serial transmission. A first prototype has been build and characterized with several experimental tests showing its suitability for both teleoperation and rehabilitative therapy. Finally, the wrist device has been integrated with both the arm and the hand exoskeleton to prove the requirement observance.