Wrist Exoskeleton Design for Pronation and Supination using Mirrored Movement Control

Wrist exoskeleton designs are being developed and tailored to support at-home rehabilitation for patients suffering upper extremity impairments. However, wrist exoskeleton design is challenged by the inherent complexity of the human wrist movement. In this work we propose a new portable exoskeleton mechanism for supporting pronation and supination, which is controlled by the opposing arm in a mirrored fashion. We make use of a gear-based mechanism and soft wearable to translate the motor's torque onto the subject's forearm to provide wrist rotation. In this paper, we analyze the exoskeleton's range of motion and accuracy of mechanical movement through posture detection and tracking. Our results show a consistent range of motion from 0° to 171.16°, surpassing the minimum required range of motion for activities of daily living (between 40° and 140°). Finally, we measure muscle activity through sEMG as an indication of assistance to the wearer. The sEMG activity recorded under different conditions shows the assistive property of the device with an average reduction in muscular activity of 20.8% for the Pronator Teres muscle and of 51.7% for the Supinator muscle.