Design and Fabrication of a Retractable Wheelchair Foot Tray

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Dystonia, Assistive, Technology, Resource, Center, WPI, MQP, Wheelchair, Accessory, ATRC


The goal of this project was to design a work surface that is both retractable and detachable from the user’s powered wheelchair and can be operated independently by the user. The client served by the device has a neurological disorder called Dystonia that has rendered her arms and hands essentially useless for functional activities and has confined her to a wheelchair. The client uses her feet to perform daily tasks including writing and typing on a computer keyboard. To accommodate such activities, the client needs a work surface at her foot level. The design team created a set of specifications, goals, and preferences to describe the functional requirements and physical limitations of the product to be designed. The next step in the design process was to develop a number of tentative foot tray designs. Using a design decision matrix, the team evaluated the tentative designs to decide which would most effectively satisfy the user’s needs. Of eight preliminary design ideas, three concepts were chosen for further development.

Physical models of these designs were created to determine their operating characteristics in all foreseeable situations. The most feasible design was selected as the final foot tray design.

The tray top offers 348 square inches of workspace. Shutters increase the work surface area by 71 percent. The tray top is constructed out of Lexan, which is a shatter resistant polycarbonate. The slides, to which the tray unit is attached, will hold up to 100 lbs of force in the vertical direction. These components have proven large and strong enough to support a variety of activities. Finally, the team suggested few improvements for the device such as: reattaching the bumpers to the C-channel, removing the small handle on the left shutter, realigning the C-channels, etc.