Faculty Advisor

Ault, Holly K.


People who suffer from afflictions causing muscle deterioration, such as muscular dystrophy, can have the function of their upper limbs dramatically improved through the use of an elevating mobile arm support. This assistive technology minimizes the gravitational restrictions on the user's limb and allows the subject to move his or her arm in the vertical and horizontal planes with considerably less effort. Currently available elevating mobile arm supports require users to have a significant amount of strength in order to effectively control the device. The goal of this project was to redesign the elevating component of the mobile arm support so that the amount of strength required by the user is minimized. Forces created by the arm throughout its range of motion were counterbalanced using a Hoeken's straight-line linkage powered by a gas spring. The device was designed with the aid of extensive analytical modeling of both the mechanism and the human arm. Once a prototype was developed, a field test was conducted to evaluate its effectiveness. The device demonstrated an improvement in making the output force more uniform and decreasing user effort, but had reduced range of motion when compared to the existing commercial product. Recommendations were made for an improved design based on these studies.


Worcester Polytechnic Institute

Date Accepted

January 2000


Mechanical Engineering

Project Type

Major Qualifying Project


Restricted-WPI community only

Advisor Department

Mechanical Engineering