Collaborators at the University of Illinois say they developed a robotic wheelchair that provides a novel mode of mobility to individuals with physical disabilities.

These researchers received a $1.5 million grant from the National Science Foundation (NSF) in 2020. With these funds, they aimed to develop that novel wheelchair. Today, two years in, the project produced a working prototype and a pending patent.

Their goal: penetrate the wheelchair market that hasn’t changed much since the first patent in the 1800s, according to the university website.

“Manual wheelchair users, due to this traditional design, have a lot of issues,” said Elizabeth T. Hsiao-Wecksler, professor in the Department of Mechanical Science and Engineering. “It’s difficult to fit in tight spaces, [the chair] requires both hands to propel, and 70% of manual wheelchair users will experience upper extremity overuse injuries that may lead to inability to use a manual wheelchair. Powered wheelchairs address some of these issues, but they’re generally really heavy, very large, expensive, and can be difficult to maneuver; most people who are able to would use a manual wheelchair.”

About the PURE wheelchair

The team at Illinois developed PURE – the “personalized unique rolling experience.”

This hands-free wheelchair operates similar to a Segway, according to the team, as the rider leans in the desired direction. Uniquely, PURE rolls on a ball or spherical wheel, based on the concept of a dynamically stable ball-based robot (ballbot). It uses an omniwheel system to drive and control the spherical wheel.

PURE automatically transitions between three driving behaviors: steer, spin and slide. Steer and spin offer similarities to a typical wheelchair, while slide allows the user to move laterally, like in a rolling office chair. To accommodate for the limited torso range of motion for some users, PURE uses sensors to estimate leaning and twisting motions. It amplifies these signals to control the ballbot’s direction and speed.

“The development of PURE has been guided by our immutables – that it be lightweight and maintain a small footprint,” said Adam Bleakney, head coach of Illinois’ Men’s and Women’s Wheelchair Track and Field in the Division of Disability Research and Education Services. “We want to ensure that the current independence of manual wheelchair users would in no way be limited by PURE. If we were to develop a hands-free device that was so heavy that it prevented users from easily transferring it into and out of their vehicle, or if it was so large that it wouldn’t maneuver around typical living spaces, we would have missed the mark. Any device that compromises current levels of independence just won’t be used during daily life.”

About the development

The team began its project in 2018 with a first-generation prototype at the Toyota Mobility Unlimited Challenge. They didn’t win the competition, but continued to work on the project on the way to winning their NSF grant.

The second-generation PURE prototype can support roughly 60 kg (130 lbs), move at up to 2.3 m/s, and brake in 2 seconds from 1.4 m/s. It measures only as wide as the user’s hips and stands at the height of a standard table chair. The researchers say this offers a “significantly smaller footprint than either powered or manual wheelchairs.

According to the researchers, the team designed a virtual reality simulation to test controls and train users. They also created a virtual obstacle course to help users practice. Users can also modify the sensitivity of ballbot’s controls to adjust to the system.

Last summer, 10 able-bodied people and ten manual wheelchair users tested the second-generation prototype, the researchers said. Hsiao-Wecksler called the testing a success. The team recently brought the prototype to the opening of the (dis)Ability Design Studio at the Beckman Institute for Advanced Science and Technology.

“[Assistant Dean for Advancement in the College of Applied Health Sciences] Jean Driscoll hopped into the prototype and started driving it right away. We didn’t even have it fully calibrated to her—it was still calibrated to someone who had less range of motion,” said Hsiao-Wecksler, “But, it behaved exactly as we were intending, in that you could just sit in it, feel the organic motion, and drive it with your body.”

The team now aims to improve their device. They plan to work on advanced driver assistance using a machine learning vision system. This could help with path-keeping, collision avoidance, and autonomous controlled stop. They aim for future prototypes to interpret both user input and obstacle detection to guide the user safely.

The team

The project’s multidisciplinary team includes a multitude of faculty and staff from The Grainger College of Engineering, College of Fine and Applied Arts, Carle Illinois College of Medicine, and the College of Applied Health Sciences: Hsiao-Wecksler, who is also the Interim Director of the Health Care Engineering Systems Center; Industrial Design Professor and co-PI Deana McDonagh from the School of Art+Design and Carle Illinois College of Medicine; Clinical Associate Professor and co-PI Bob Norris from the Department of Industrial and Enterprise Systems Engineering; Assistant Professor João Ramos in MechSE; Adam Bleakney, Head Coach of Men’s and Women’s Wheelchair Track and Field in the Division of Disability Research and Education Services (DRES); Dr. Jeannette Elliott, Head Physical Therapist at DRES; Dr. Pat Malik, retired Director of DRES; and numerous graduate and undergraduate students from across campus.

“The impetus for pulling this team together was to leverage the expertise on campus to increase access to spaces and experiences that daily wheelchair users like me are often marginalized from,” Bleakney said. “Standard ultra-light, manual wheelchairs are no doubt outstanding in many respects and provide an increased level of independence during daily life. At the same time, the act of pushing a manual wheelchair prevents the hands from engaging in other more meaningful activities while moving – such as holding hands with a loved one on a walk, carrying a cup of coffee, holding a toddler while moving around the house. Each of these is possible with PURE.”