A team of engineering students is working to improve the design of walkers to keep seniors on their feet and injury free.

By Melanie Bush

Personal and professional motivations have brought together a team of Cornell engineering students and a psychiatrist affiliated with Weill Cornell Medical College in an unusual project that could improve the lives of millions of elderly people.

The students are designing and building an electrically assisted walker. The project, funded by a gift from alumni John and Michelle Slapp, Class of ’69, began in September 2006.

The team is focusing on making the walker’s braking system electronic, and they hope ultimately to create a walker that is safer and easier to use, encouraging elders to maintain an active lifestyle; inactivity is a leading cause of weakened motor skills, which can lead to injury.

The electrically assisted walker project is unusual in several ways. To begin with, it has an unusual genesis: It stems from a patent held by a psychiatrist in New York City.

Dr. Eli Einbinder, who is affiliated with Weill Cornell Medical Center, was a tennis player and skier before 1993, when he injured his back. “So I’m sitting there in my office looking for another hobby,” recalls Einbinder, “and all of a sudden I start noticing people with walkers—how difficult they are, how non–user-friendly. I’m also an inventor, so I decide to design a mechanical walker that works better. I soon realize that an electrical model with a button for braking is much simpler, and I patented that in 1998, only to realize that batteries and motors do not exist that are small or efficient enough to operate it.”

“Last May,” continues Einbinder, “I e-mailed David Lipson [senior lecturer in Cornell’s Department of Biomedical Engineering] to ask if batteries and motors had improved, and to my surprise, instead of ‘Yes’ or ‘No’ he said, ‘How would you like to help organize and sponsor a project with my students?’”

Students on the assisted walker team are (from left) Phillip Wang, Homer Chiang, team leader Sheryl Lau, and Suneth Attygalle. Lindsay France/University Photography

Einbinder says he only realized then that his interest in walkers actually dates from much earlier. He had encephalitis as a child, a disease that strikes one of every 30,000 people who catch chickenpox, and was for a time unable to walk. “Now, for me, this whole story makes sense, because I would have been mobile several weeks earlier with the help of the walkers I’ve now designed,” he says.

Einbinder has been a consultant to the project since its inception, working with the team at least weekly via conference calls and e-mail, as well as having frequent communication with Lipson.

The project is personal to the students, too. As biological engineering senior Suneth Attygalle writes in his project proposal: “For 94 years, my grandmother in Sri Lanka has lived a long, independent life in the comfort of her own home. Although she has remained healthy throughout this time, age has naturally weakened her motor skills. ... For example, now, when walking long distances, she requires someone’s sturdy hand to support her, as well as to protect her in case she trips. Such situations are common among the aged. There is a clear need for safe, assisted walking devices for the elderly or disabled. The traditional ‘walker’ relies entirely on the user for control, making it unusable for those with weakened strength or response time. Thus, I seek to design a novel, electronically and mechanically assisted walking device with a team of three other students.”

Those three are Sheryl Lau, the team leader, and Phillip Wang, both graduate students in the master of engineering program in biomedical engineering; and Homer Chiang, a junior in mechanical engineering. Lau worked in a rehabilitation hospital in Chicago and believes the project is important because “there are a lot of people in the U.S. getting older and they’re going to need support.”

“Initially we thought we’d come up with a whole new walker, but it needed too much machining, so we decided to start with walkers already out there,” she says. “We tried three-wheelers and four-wheelers—each costs around $100 at Wal-Mart—and found that the three-wheeler had a perfect place for us to add electronics. Now we’re developing both models with the same technology. I think people will like it—they have electric wheelchairs, so why not?”

“It’s simple, but not simple,” says Lipson, the group’s research adviser. “That’s what’s lovely about this project. There’s no model of an augmented walker; it’s a blank slate. It’s a very constrained, challenging design problem.”

David Lipson

Lipson goes on to explain that the Department of Biomedical Engineering itself is only three years old. “Mike Shuler [BME chair] is building this department with three goals: first, to grow the department into the top 10 among peer institutions; second, to integrate biomedical engineering education across scales—molecular, cellular, organ and tissue; and lastly, to develop whole body solutions where students learn to develop practical applications. That’s where I come in,” he says. “I try to teach them that their ultimate teachers are not professors, but practitioners—doctors, nurses, physical therapists. Coming straight out of Cornell with the ability to engage with practitioners and clinicians about their needs will really distinguish them.”

To get input from potential users of the assisted walker, students consulted with faculty at the other major educational institution in town, Ithaca College, which has a well respected physical therapy department, as well as the Ithaca College Gerontology Institute. The group met with Katherine Beissner, a professor of physical therapy who specializes in geriatrics. Beissner is also president of the board of directors of Ithacare, the agency that runs Longview, a senior living facility associated with Ithaca College. The walker team accompanied Beissner to Longview last October and interviewed walker users there about exactly what they would like to see changed.

The elders’ complaints included the observations that walkers are hard to fold, are heavy, don’t fit in the car, have too-small seats, and are difficult to maneuver through doors and hallways and in small spaces such as bathrooms. The Cornell team observed several other problems, such as the walkers’ brake cords getting tangled and their wheels getting misaligned if struck from the side. Walkers appeared to either work well or fold well, but not both. The group spoke with a 103-year-old walker user who agreed to be videoed. Back in their lab in Kimball Hall, they watched her walking over a threshold forward and backward, as well as walking down a hall.

 “Every time you add something to a person, it presents environmental hazards,” says Beissner. “With walkers, there are lots of issues. The walker can ‘get away’ on an incline. The brakes can be hard to grip if you have arthritis, and brakes are very important for stability when going from standing to sitting or vice versa. Some models’ wheels are so small they get stuck on things, like the edge of a rug. Or they turn when you back up and then won’t go forward.”

Beissner feels that elders will be receptive to better technology. “People I know are very interested in maintaining their mobility. I find them much more open to change than any stereotype suggests,” she says.

The Cornell group took its walkers to Longview to get feedback from a group of current walker users. Lindsay France/University Photography

As braking is consistently cited as a major problem, the team is tackling that first. According to Attygalle’s project proposal, “the most rudimentary walker has four rigid posts, and the user lifts and plants the walker in front of them and walks towards it in an unnatural movement. ... Adding wheels to all four posts results in a walker that can match a person’s gait; however, [this] makes the walker more difficult to control, since the walker can now move with its own momentum. Current four-wheeled walkers with brakes rely on the user to apply the brakes properly, using levers similar to bicycle brake levers.”

The braking system the team is devising couldn’t be more different from bicycle brakes. Instead of stiff, hard-to-grip levers, their walker has a single highly sensitive button. The button is a touch sensor that runs to a microprocessor (the system’s brain), that sends information to a linear actuator (the system’s muscle), that in turn pulls on a mechanical brake to make the wheels come to a complete stop. A mere touch is effective; this walker will brake safely for users with low strength or impairment in their hands.

Other design constraints include weight, cost, size, and battery life. Rolling walkers with brakes typically weigh between 8 and 20 pounds, and the team’s goal is that the electronically enhanced model will not exceed that. Traditional (non-rolling) aluminum walkers weigh only about 3 to 5 pounds. The team’s survey of residents at Longview suggests that people use the traditional walker for traveling because they can lift it into their cars, but prefer the enhanced mobility of the rolling walker when lifting is not necessary.

Rolling walkers typically cost between $100 and $250. Private insurance will generally pay two-thirds of the cost of a rolling walker. The team is working to keep the cost of the assisted walker below $400.

Affordability is a significant issue. Many people with mobility problems rely on Medicare, which currently covers 80 percent (typically about $50) of the cost of a non-rolling walker. Initially the market for an electrically assisted walker may be limited to those who can afford it out of pocket. Eventually, however, the walker may be included in a new Medicare category covering powered wheelchairs, which has higher spending limits.

In terms of size, the assisted walker will be narrower than a standard door frame and will collapse to fit in a car trunk or back seat. In terms of power, because a walker is typically used throughout the day, it should run at least one day on a single charge.  

The team is aware of the importance this project might have in improving the lives of the elderly, a population that, by the middle of the 21st century, will approach 80 million people in the United States. “This is not a small market,” says Attygalle. According to the group’s research, medical costs resulting from falls by the elderly are expected to approach $32.4 billion by the year 2020.

Brakes are important for stability but can be hard to grip. Lindsay France/University Photography

In March, with the guidance of Beissner, the Cornell group took its walkers to Longview to get feedback from a group of current walker users.

Attygalle reports a thoroughly mixed reaction from those who tried out the walkers. “There was a huge range of opinion, from people who thought our walker was great to those who wanted to stick with the old one,” he says. “It was definitely a lot different than when we use them. For starters, some of the elders had smaller hands, and they didn’t like the grips or where the braking button was. We definitely saw more clearly the need for controlled, gradual braking—our system is all-stop or all-go. We realized we may need to incorporate two separate braking modes, one to slow down and one to stop completely.”

 “I definitely think that in the future walkers will be electrical,” says Wang. “Baby boomers will be seeking more sophisticated machines that give better user mobility.”

Wang adds that the project has been a great way to prepare for working in the biomedical industry. “The biggest challenge for me was figuring out where everybody else fits in, understanding what each person could contribute to the project,” he says. “This is the first time we’re really out of the classroom; there’s so much creative freedom.”

 “The best part of this project for me,” says Attygalle, “is that we as students get to define what the parameters are. All the decisions were made entirely by us. Also, I like that the scope of the project is something that will extend beyond the campus.”

Although most of the team will graduate this spring, the project will continue. “We’ll make up a suggestion list for next year’s team,” says Lau. “There’s so much more we want to do—add better sensing, maybe ultrasound. If the wheels were motorized, they could mimic more exactly a natural walk. Basically, this project could go on indefinitely, adding or exchanging parts to suit a user’s need.”

More immediate goals must be addressed first, however. “Once we determine that the brakes are optimized, we can move on—when they are as reliable as possible and fit the widest range of user needs and constraints,” says Chiang, the group’s mechanical engineer. “For me, it’s exciting to see the physical manifestation of our ideas; it’s exciting to say, ‘I made this with my hands.’ And if it makes somebody’s life easier, I’ll be proud.”