By Priya Ramachandran
We’ve all seen exoskeletons in some of the most popular science fiction, even if we didn’t know that’s they were called. Sigourney Weaver used an exoskeleton designed for cargo lifting in outer space to kill the alien queen in Aliens. Tony Stark used a more personalized and hi-tech one to save the world as Iron Man. Believe it or not, paraplegics could be using one sooner rather than later to walk again.
Introducing the personal exoskeleton — the mechanical bodysuit that could get people with spinal cord injuries back on their feet. The military already has them, rehab clinics are using them, and with costs coming down and technology improving, it looks like they’re going to be available for personal use in the near future.
Back to Walking
When a skiing accident left Amanda Boxtel a T11-12 paraplegic 18 years ago, doctors told her what they have told hundreds of thousands of people with spinal cord injuries: You’ll never walk again. Undeterred, she carved out a new life for herself. She started a nonprofit, helped create adaptive skiing programs and spoke often as a motivational speaker. Still, Boxtel missed the natural feeling of simply standing up and moving around. The closest she felt to natural body movements was when she was on horseback.
That was before she was invited to try the Ekso exoskeleton (earlier called eLegs) in 2010. The Ekso is the signature product of Ekso Bionics, one of the pioneering companies manufacturing exoskeletons. Walking with the aid of the Ekso proved even more natural than horseback riding, according to Boxtel. “I had forgotten how tall I was. How it is to look someone eye to eye,” says Boxtel, adding, “
Boxtel, 43, quickly signed on as an Ekso ambassador and now gets to use an exoskeleton whenever she’s doing demos or brand promotion. These engagements are only for a few days a month, but she can’t wait for each opportunity she gets to try out her new legs.
The exoskeleton supplements and mimics the musculoskeletal system found in the human body, which means that different parts of the exoskeleton need to carry out the various functions associated with the brain, the muscles and the sensory nerves.
“You have a pair of wearable legs that give you additional bone structure and carry the weight of your body,” says Eythor Bender, the CEO of Ekso Bionics. “A computerized control system replaces the brain.”
Exoskeletons often come with crutches or walkers to stabilize the wearer. These prosthetics may also contain embedded sensors that detect nuances from the wearer’s hand movements, which are signals of the wearer’s intent about what he or she wants to do. The control system translates these sensory inputs into signals that tell the bionic legs to move. Motors translate these signals into actual movements.
Pressure exerted on both crutches, for example, might tell the sensor that the wearer plans to get up or turn. Moving one crutch forward causes the opposite knee to flex, which results in the opposite leg moving.
Using an Exoskeleton
There is a steep learning curve associated with mastering an exoskeleton. Before learning to use the exoskeleton at Ekso headquarters, Boxtel had to learn how to walk all over again. She built up her upper body strength on the parallel bars and got into tip-top shape. In the lab, she first used the walker and then crutches with the exoskeleton, both while attached to a tether. After about 12 hours of walking time, she was ready for independent walking, off-tether.
Now, with a year of intermittent use behind her, Boxtel finds that it is a matter of minutes before she straps on her exoskeleton and is on her way. “It is like learning to ride a bicycle,” she says. “I just get in, and take off from where I left off.”
Despite all their promise, exoskeletons won’t be the best solution for everyone. “Some work better for certain situations than others,” says Dr. Arthur D. Kuo, a professor at University of Michigan who has done extensive research on human biomechanics.
Most exoskeletons weigh a considerable amount themselves, and the wearer needs to able to sustain that weight on his or her frame. This means that they are better suited for people who have upper body strength and can self-transfer in and out of wheelchairs. The Ekso exoskeleton, for example, is made of carbon fiber and steel and weighs 50 pounds. Specs available from the company website say it is for people who are between 5’2” – 6’2” in height and under 220 pounds in weight. Robust lithium ion battery packs provide four hours of continuous walking time. Bender said that the Ekso exoskeleton is ideal for people with weakness in their lower extremities and who retain the use of their arms. People who are affected by Guillain-Barré Syndrome or multiple sclerosis might also find an exoskeleton beneficial.
Bender says that the day is not far off when wheelchair users will be able to plan long hours of activity around their exoskeletons. “I can see people using them every day — to walk down the stairs, prepare their breakfast, their coffees. Maybe even take them to work or to the mall,” he says.
But even when personal exoskeletons hit the consumer market, using them will probably not be as simple as taking a box home and putting on a pair of pants. Users will probably need to use them under medical supervision initially until they get comfortable with using them on their own.
The Exoskeleton Landscape
Exoskeletons have come a long way since the 1960s, when General Electric and the United States Army co-developed one of the first models — the Hardiman exoskeleton. The aim of the technology then was to help soldiers carry additional weight. The Hardiman project was abandoned because the exoskeleton itself weighed close to 1500 pounds, making it impractical and unwieldy to use.
Fifty years later, the government is still working on building exoskeletons to aid soldiers. Ekso Bionics has licensed a version of its exoskeleton nicknamed HULC (Human Universal Load Carrier) to Lockheed Martin Corporation for military development.
Paraplegics and soldiers are not the only group that might benefit from exoskeletons. They are also being tested for their ability to hasten rehabilitation. Heidi Gilbert, a clinical instructor for California State University, Sacramento, and a physical therapist, says exoskeletons can come in handy in short- and long-term rehabilitation, especially for stroke survivors or people with paralysis.
“In the short term, a physical therapist would prefer the person to work against the paralysis because this is the critical period when the brain begins the alternate mapping process. If the brain is not challenged, or if it perceives an ‘out’ it will take it,” says Gilbert. Exoskeletons, she surmises, may aid rehab by keeping the connections alive.
There are several companies and university research teams involved in exoskeleton development. Israel-based Argo Medical Technologies has a product called ReWalk which is similar to the Ekso exoskeleton. Rex Bionics from New Zealand has a joystick controlled, crutch- and walker-free exoskeleton. Cyberdyne Corporation in Japan has a gait trainer robotic exoskeleton called HAL5. HAL5 is probably the most ambitious project of all — it is a robot with a complete body armor suit that allows for hand movements as well. And at the Berkeley campus of the University of California, researchers are at work on building an affordable prototype named Austin.
Test Driving an Exoskeleton
If you liked everything you’ve read so far about exoskeletons, you’re probably wondering how you can get your hands on one.
Currently exoskeletons are only available through rehabilitation centers around the world. HAL5 units are available for rental or lease to medical facilities in Japan. Rex Bionics’ exoskeletons are available through their website. A version of ReWalk is presently being tested at MossRehab, a rehab center based in Philadelphia, and at the James J. Peters Veterans Affairs Medical Center in Bronx, N.Y. Ekso’s institutional line is presently in production and will ship out to ten rehab centers around the country. The Austin is still in prototype stages.
If getting on a rehab center’s tester list or moving to Japan is out of question, waiting for the Ekso or the Austin to hit the market by late 2012 or early 2013 might be your next best bet.
Austin Whitney, a paraplegic who works with the Berkeley team in testing the Austin exoskeleton (named after him), says, “I would just advise people to be patient. There are people hard at work around the world to bring these products to market.”
Austin Whitney walks accross UC Berkeley’s graduation stage toward Homayoon Kazerooni, the professor who developed the Ekso Bionics exoskeleton.
Kuo says time will tell how valuable exoskeletons are. “The videos are fantastic,” he says. “The products look interesting. But I would like to see some real tests [around exoskeletons] that can be peer reviewed.”
Cost is another area of concern to prospective users. Says Whitney, “Exoskeletons that are available to rehab centers cost close to a hundred thousand dollars … An ordinary person can’t afford that much. Our aim is to bring a product to market that is between $10,000 and $15,000 and is covered by insurance.”
Bender does not give any numbers but says the pricing of a personal exoskeleton will probably be on par with high-end prosthetic devices or even an expensive car. Every effort is being made to ensure that the cost of the device can be covered by insurance, he adds. He says that once the personal product is out, Ekso will focus on building exoskeletons for children as well as sleeker exoskeletons that can be worn under the clothes.
Boxtel’s words help put the excitement around exoskeletons in perspective. “Wheelchairs were invented about five hundred years ago,” says Boxtel. “For the first time in two thousand years, people with disabilities have another mobility option … It is a milestone in the history of movement.”