A Low Cost Power Assist for Active Wheelchair Users

Abstract

Wheelchair power assists are devices that a wheelchair user may retrofit onto their wheelchair to increase their range, speed, and power. Users of these devices may already have the ability to propel themselves manually, but their mobility is further enhanced with these devices. This is particularly true for “active” wheelchair users, who use wheelchairs specially designed for an active, physical lifestyle. However, commercial power assists often cost thousands of dollars, which can be a significant financial barrier for wheelchair users who cannot get insurance to cover the cost. For this reason, I have partnered with a permanent wheelchair user to create and test a low cost power assist, which we call the “Tailwind,” that wheelchair users can build with minimal tools. By enabling more wheelchair users to add a power assist to their wheelchair, we intend to facilitate exercise and independence for wheelchair users who may feel otherwise restricted in range, speed, or power.

Based on the prototype, I estimate the total cost to be less than $450, which is an order of magnitude less than commercially available power assists. I estimate the range to be 11 miles on smooth terrain such as concrete and 4.3 miles on rough terrain such as grass, and I estimate the maximum speed to be 9.7 mph. As for power, I estimate that the Tailwind can climb a slope of 7.4° (13% grade) on its own power and at least 15° (27% grade) when the user is also manually pushing theirself. Additionally, the Tailwind has a lift mechanism that allows the user to lift the Tailwind’s wheel off the ground when not in use. Lifting the Tailwind eliminates its rolling resistance and is a feature that does not appear on any commercial power assists as far as I am aware.