Nearly three million people living in the United States use wheelchairs. These individuals must adapt to the world around them in order to maintain normal, active lifestyles. A wheelchair tray is an assistive device that helps facilitate a normal lifestyle, but commercially available trays are bulky, non-adjustable, are unable to be stored on the wheelchair, and, in general, do not meet the needs of the user. An interdisciplinary team consisting of five undergraduate engineering students and one graduate occupational therapy student designed a new wheelchair tray to address these problems as a part of ME 565, a senior capstone design course, during the 2008 academic year. The ME 565 wheelchair tray design did not live up to the team’s expectations and failed to meet many of the original product specifications. As a result, the purpose of this thesis is to design, construct, and test a new wheelchair tray to address the issue that a wheelchair tray still does not exist that meets the needs of the user or improves their independence.
The target population for this tray was determined to be adults who use rigid wheelchairs. However, in order to fully benefit from the design, the wheelchair tray users would need to minimally retain elbow flexion and extension and wrist extension. Next, user needs were determined from focus groups consisting of occupational therapists, paraplegics, and quadriplegics. These user needs were translated to quantifiable product specifications using a house of quality, and the ME 565 wheelchair tray was analyzed to help assign values to the product specifications. Next, product concepts were generated and then evaluated to determine a final concept choice. The final concept choice gave a clear direction towards the final prototype, but was continuously improved throughout the rest of the design process, as certain functions of the tray are discovered to be infeasible or to not meet the final specification target values. A wheelchair tray based on the final concept choice was modeled, analyzed, and constructed.
The wheelchair tray produced in this project improves upon the design flaws from the ME 565 tray while adding new functionality such as vertical adjustment and support for the weight of the user. The tray attaches a wheelchair, is controllable by the user, and does not interfere with the normal operation of the wheelchair. It allows users to have a full size surface to perform daily activities such as writing, reading, or eating. The tray travels with the wheelchair, and can be utilized at any time.
Lastly, representative users, their caregivers, and a physical therapist were asked to evaluate the new tray using a product survey. Allowing representative users to test the tray gave insight into which aspects of the tray needed to be improved. Some of this feedback was incorporated into a redesign of the tray, such as making it easier to deploy, adding a visual aid, and changing the deployment geometry.
Overall, the new tray design addresses the needs of the users and has the potential to improve their independence.