Design of Spiral-Cable Forearm Exoskeleton to Assist Supination for Hemiparetic Stroke Subjects

TL;DR

This paper introduces a novel cable-based passive forearm exoskeleton designed to assist supination in hemiparetic stroke patients, combining mechanical innovation with preliminary testing to enhance rehabilitation.

Contribution

The study presents a unique spiral-tendon routing mechanism integrated into a passive exoskeleton for stroke rehabilitation, enabling manual supination support and potential future actuation.

Findings

Benchtop testing confirms torque capability.

Preliminary assessment shows potential for aiding stroke patients.

Device can be integrated with existing orthoses.

Abstract

We present the development of a cable-based passive forearm exoskeleton that is designed to assist supination for hemiparetic stroke survivors. Our device uniquely provides torque sufficient for counteracting spasticity within a below-elbow apparatus. The mechanism consists of a spiral single-tendon routing embedded in a rigid forearm brace and terminated at the hand and upper-forearm. A spool with an internal releasable-ratchet mechanism allows the user to manually retract the tendon and rotate the hand to counteract involuntary pronation synergies due to stroke. We characterize the mechanism with benchtop testing and five healthy subjects, and perform a preliminary assessment of the exoskeleton with a single chronic stroke subject having minimal supination ability. The mechanism can be integrated into an existing active hand-opening orthosis to enable supination support during grasping tasks, and also allows for a future actuated supination strategy.