Document Type

Other

Publication Date

1-1999

Keywords

WPI, MQP, Assistive, Technology, Resource, Center, ATRC, Powered, Arm, Muscular Dystrophy

Abstract

The goal of this MQP was to design a body-mounted powered arm orthosis that would provide powered flexion and extension of the shoulder, abduction and adduction of the arm, flexion and extension of the elbow, and humeral rotation. Individuals with Duchenne Muscular Dystrophy have slowly diminishing muscle control and strength in their arms, but maintain both strength and mobility in their hands. They are unable to perform daily tasks such as grooming and eating, so there is the need for an orthotic device that individuals with decreased arm strength can use to perform these tasks. Current products allow the individual to perform certain specialized motions, but do not restore an individual’s freedom of motion. The objectives of this project were to develop a device that would provide sufficient power to move the device itself, as well as the user’s arm, and would produce forces and velocities comparable to those of a fully functional arm since high forces and speeds can pose safety risks. Prior MQPs resulted in prototypes that involved electric motors and hydraulics, both of which were wheelchair mounted. A device that would transfer power from an external mechanism, but utilize the passive motion of the joints for alignment would provide enhanced integration of the dev ice with the joints of the arm and shoulder. The MQP group considered a kinematic analysis of a human arm, the daily activities that an individual performs, and the required range of motion of the device in order to develop a prototype of the orthosis. The final design concept was determined by testing prototypes of the components. The outer radius of the upper elbow joint cuff accommodates passive humeral rotations of 180°. A pin connects the upper portion of the elbow joint to the lower portion of the elbow joint to allow for flexion and extension. Analysis of the device indicated that the powered arm orthosis provides four degrees of freedom and allows for the passive self-alignment of the joints, while still providing the appropriate motions at the shoulder and elbow joints.

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