MechSE, IntelliWheels collaboration propels geared wheel technology
IntelliWheels, Inc. led by co-founder and CEO Scott Daigle (BSME ’09, MSME ’11), received a Phase II Small Business Innovation Research grant from the National Institutes of Health to advance the development of ultra-lightweight, multi-geared wheels for manual wheelchairs that would allow for easier navigation of hills and rough terrain and reduce the risk of arm injuries that often result from overuse.
Since Daigle was a graduate student in MechSE Professor Elizabeth Hsiao-Wecksler’s Human Dynamics and Controls Lab, IntelliWheels has had ongoing collaborations with her and, for this project, with scientists at the University of Wisconsin-Milwaukee to conduct research on geared wheelchair technology.
Hsiao-Wecksler and graduate student Alan Gaglio are developing an instrumented hand rim which can be added to the geared wheels. The instrumented hand rim can record the forces and torques that the user’s hand applies to the rim. Using inverse dynamics, a process utilized often in biomechanics, they aim to use these measurements to estimate the loads in the user’s wrist, elbow, and shoulder joints during propulsion. Theirs is the first instrumented geared wheelchair wheel to try to quantify these dynamic forces.
“This information is important to us because long-term manual wheelchair users have upper extremity joint pain, particularly in the shoulder, as well as other conditions like carpel tunnel in the wrist,” said Gaglio. “There are commercially available wheels that allow you to measure the forces being applied to the hand rim, but those wheels are direct drive. We want to know what the forces are when using a geared system, so we could demonstrate that the forces being generated by the muscles are reduced as a consequence of lowering the gear ratio.”
Hsiao-Wecksler said the wheels are designed to be easily installed on the axles of an existing manual wheelchair, and the use of gears is similar to those on a bike. If riding a bike uphill, for instance, the rider would shift to a lower gear. A direct drive wheelchair wheel is like using a single speed bicycle to get around; few adults ride single speed bicycles due to the greater effort needed when going uphill or through rough terrain.
“With the geared wheel, you’re pushing a little faster but with less force,” she said. “You wouldn’t be using as much muscle strength. Similar to riding a bicycle, you might have to peddle more frequently in order to go the same distance, but the peddling is a lot easier.”
According to the 2010 U.S. census, there are 3.6 million people wheelchair users over the age of 15, and it’s estimated that more than half of them use manual wheelchairs.
“I would argue that every manual wheelchair user could benefit from geared wheel technology,” Gaglio said. “And for some powered wheelchair users who still have functional control of their upper extremities, geared wheels may allow them to move back into a manual chair by reducing the demand on their upper extremities during propulsion.”
After Gaglio and the rest of Hsiao-Wecksler’s team complete development of the hand rim, the wheels will be sent to the team in Milwaukee to capture data and conduct the inverse dynamics and biomechanics research. Through the rest of the fall semester, the Milwaukee team will work with 15 veterans with spinal cord injuries to test the mechanics of the hand rim as hypothesized. The project is also employing design and product testing expertise of TiLite, a manufacturer of ultralite wheelchairs.
“The end goal of our work is to provide a biomechanically-based argument to encourage manual wheelchair users to consider using geared wheels instead of standard direct drive wheels. Hopefully we can also inspire even more studies on manual wheelchair technologies,” Gaglio said.