Design of an Upper-Limb Exoskeleton for Functional Assistance of Bimanual Activities of Daily Living

Abstract

Hemiparetic loss of upper-limb function is a common occurrence following a stroke. A portion of individuals will regain substantial function through therapy and learning of adaptive behaviors, but a substantial population is left with one arm having chronic motor function loss to a degree that hinders performance of bimanual activities of daily living (ADLs). This dissertation presents a summary of the mechanical and electrical design and preliminary assessment work performed for a semi-powered hand and arm exoskeleton intended for daily assistance of tasks requiring, or benefitting from, the use of both hands. Specifically, the device is a hand exoskeleton coupled with a wrist and elbow exoskeleton to supplement position and stability while conducting bimanual ADLs. The hand portion has one control degree-of-freedom and augments the user’s grasp strength and ability to extend the affected hand into the open position. The wrist and elbow exoskeleton is comprised of a curved prismatic joint and a revolute joint that exist in a normally locked state to provide passive orientation and support to the arm. Both joints may be rapidly unlocked and the arm position reconfigured. A two-button control system was implemented to allow the user to trigger the exoskeleton state transitions used in the performance of bimanual ADLs. A preliminary assessment of the exoskeleton was performed with several subjects with varying degrees of upper-limb motor deficit resulting from stroke. For subjects with limited hand and arm functionality, the exoskeleton was found to increase grasp strength and improve the ability to perform representative bimanual tasks.