A Soft High Force Hand Exoskeleton for Rehabilitation and Assistance of Spinal Cord Injury and Stroke Individuals

TL;DR

This paper introduces a novel cable-driven finger orthosis inspired by fin-ray structures, capable of generating high fingertip forces for rehabilitation, while maintaining comfort and portability for individuals with SCI and stroke.

Contribution

It presents a new design that balances high force output with ergonomic comfort, overcoming limitations of existing exoskeletons.

Findings

Achieved a 2:1 force transmission ratio in tests.

Maximum fingertip force of 22 N demonstrated.

Design offers lightweight and conformal fit for users.

Abstract

Individuals with spinal cord injury (SCI) and stroke who is lack of manipulation capability have a particular need for robotic hand exoskeletons. Among assistive and rehabilitative medical exoskeletons, there exists a sharp trade-off between device power on the one hand and ergonomics and portability on other, devices that provide stronger grasping assistance do so at the cost of patient comfort. This paper proposes using fin-ray inspired, cable-driven finger orthoses to generate high fingertip forces without the painful compressive and shear stresses commonly associated with conventional cable-drive exoskeletons. With combination cable-driven transmission and segmented-finger orthoses, the exoskeleton transmitted larger forces and applied torques discretely to the fingers, leading to strong fingertip forces. A prototype of the finger orthoses and associated cable transmission was fabricated, and force transmission tests of the prototype in the finger flexion mode demonstrated a 2:1 input-output ratio between cable tension and fingertip force, with a maximum fingertip force of 22 N. Moreover, the proposed design provides a comfortable experience for wearers thanks to its lightweight and conformal properties to the hands.