Document Type

Other

Publication Date

4-30-2009

Keywords

atrc, assistive, technology, resource, center, wheelchair, wheel, chair, one, arm, drive, manual, mobility, accessory

Abstract

Traditional manual wheelchairs require considerable use and control of both arms for operation, thus adaptations are required for individuals with asymmetrical use of their arms. Building upon previous projects, the goal of this project was to create an accessory, to be installed on a standard wheelchair, which would allow full control of the wheelchair with only one arm/hand while addressing areas lacking in commercial products and previous designs, such as manufacturability, attendant control, user comfort and ergonomics. After preliminary testing and analysis of three one-arm propulsion designs (Meyra lever-operated chair, Quickie dual-pushrim chair, and the 2005-06 MQP’s prototype), the project team developed a design for a removable, lever-operated accessory which could be adapted to fit a range of the most popular standard wheelchair models. The propulsion system, connected to the main lever by a coupler link, consists of a dual gear-pawl assembly in which the desired direction of motion is chosen by moving a shifter to engage one of the two gears press-fit around clutches, each of which allows motion in only one direction, either forward or reverse. By including a neutral pawl position in which neither clutch is engaged, this design allows an attendant to propel and control the chair. Disc brakes mounted to each of the two wheels are operated via a brake lever attached to the handle of the main propulsion lever. The steering design consists of a cable wrapped around two pulleys. One pulley, attached to the main lever handle, transmits the user’s input to the second pulley at the caster wheel, causing the caster to turn. Careful attention was paid to minimizing the number of specialized parts and hardware used in the design in order to improve its manufacturability and ease of installation, and to minimize the need for maintenance. During final testing, the team’s prototype was compared to the Meyra lever-operated wheelchair and the prototype from the 2005-06 MQP by Cassidy, et al. The 2008-09 wheelchair showed considerable improvement over the prior MQP in the areas of size, required propulsion force, and user comfort. The 2008-09 MQP was also successful in greatly reducing operational noise and safety hazards due to sharp edges and moving parts. Deficiencies in the 2008-09 design included mechanical disadvantage in the steering system, excessive weight, and failure due to stress concentrations in the accessory mounting spokes.

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