Exo-Wrist: A Soft Tendon-Driven Wrist-Wearable Robot With Active Anchor for Dart-Throwing Motion in Hemiplegic Patients

Constraint-induced movement therapy (CIMT) is an effective recovery protocol for patients with stroke. However, not all the stroke patients can participate in CIMT. Devices that assist the movement of the affected side could help increase the number of stroke patients who can participate in CIMT like protocol. In this letter, a soft cable-driven wrist-wearable robot called Exo-Wrist, which assists the wrist of a paretic arm in performing the dart-throwing motion (DTM) with an active forearm anchor, is proposed. To increase the force transmission efficiency while preventing medical issues due to long-term pressure, a corset active anchor, which compresses the body only when anchoring is needed, is developed. A moving pulley mechanism and a three-layered structure increase the functionality of the anchor. Considering the natural movement of wrist extension and the frequently-used wrist motions in daily life, the wrist is assisted along the DTM direction, and the method to find a personal DTM is introduced. A 3D-printed custom wrist armlet is developed to hold the tendon path and exert a torque along the DTM direction. Together with a hand assistive device, Exo-Wrist could be used as a tool to help stroke patients with difficulty in wrist extension to participate in task-oriented rehabilitation protocols such as CIMT.