Is This the Future of Robotic Legs?

Hugh Herr’s bionic limbs have already revolutionized life for amputees (including himself). Now he’s envisioning new capabilities for everyone else

(Photo-illustration by David Arky)
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These days, Herr is something of a professional juggler: In addition to his posts at BiOM and the biomechatronics lab, he teaches classes at MIT and Harvard. He travels to lecture and to consult on other bionics projects. He still climbs when he can, although in recent years, the highest-profile mountaineer in the family has been his wife, Patricia Ellis Herr, whose 2012 book, Up: A Mother and Daughter’s Peakbagging Adventure, details a family quest to summit the 48 highest mountains in New Hampshire. The Herrs’ daughters, Alex, 11, and Sage, 9, are both avid climbers. Hugh joins them on hikes when he can but spends a large part of his waking life in the lab.

Before I left MIT, I asked Herr if he was comfortable with the roles he had assumed as an outspoken advocate for bionics and a very visible bionic man himself. He paused. “We’re constantly surrounded by messages about how technology is not doing us well: pollution and nuclear weapons and so on,” he said, finally, studying his legs. “I’m an example of the opposite trend. So, yes, I’m comfortable with it. God, yes.”


This past March, Herr flew to Vancouver to deliver an address at the TED Conference, the annual summit of science and tech cognoscenti. His presentation was heavily autobiographical: He discussed his accident, his first inventions and a pair of early prosthetics that allowed him to adjust his height from 5 feet to 6 1⁄2 feet plus. (“When I was feeling badly about myself, insecure, I would jack my height up,” he joked, “but when I was feeling confident and suave, I would knock my height down a notch, just to give the competition a chance.”)

Then the lights dimmed and went up again, and Herr introduced a professional ballroom dancer named Adrianne Haslet-Davis. In 2013, Haslet-Davis had lost part of her left leg when terrorists detonated a pair of bombs at the Boston Marathon; now, as the crowd sat rapt, she and her dancing partner, Christian Lightner, performed a delicate rumba. If you hadn’t spotted the glint of the prosthesis Herr had fitted her with, you would have been hard-pressed to know Haslet-Davis had ever been injured—her footwork was dazzlingly precise, meticulous, elegant.

The performance—a video of which has been viewed more than 2.5 million times online—was a testament to the healing power of high technology. It was also a high-profile showcase for the BiOM T2, the successor to the iWalk BiOM. The T2 uses the same basic architecture and algorithms as the original device, but the battery is lighter and longer-lasting and the motor more reliable. This fall, BiOM will release an Android application that will allow users to monitor steps and battery life and maintain some control over the propulsion levels. “If you’re just sitting in the office, you might dial it down a bit,” Charles S. Carignan, BiOM’s CEO, told me. “But let’s say you want to go out and climb a few steep hills. Well, then you’d probably want some extra power.”

BiOM says it has distributed more than 900 BiOM ankle systems, with nearly half going to veterans such as William Gadsby. Paul Pasquina, a colonel in the Army Medical Corps and chief of the Integrated Department of Orthopaedics and Rehabilitation at Walter Reed Army Medical Center, calls the technology “revolutionary.” Non-powered prostheses, he said, cannot mimic the natural gait, and users try to compensate with other muscle groups. That can lead to pain, degeneration, osteoarthritis and severe musculoskeletal and cognitive stress. Bionics, Pasquina said, can, when combined with aggressive rehabilitation, better compensate for a lost limb and improve balance and function. “The more you’re able to simulate natural human motion, the better for the individual,” Pasquina said. “In that sense, I believe, the technology speaks for itself.”

But a BiOM T2 lists for about $40,000, and Herr has had trouble stirring up the same enthusiasm among civilian insurers. Last year, he and several of his patients testified in front of Congressional panels to persuade Medicare administrators to provide bionic limbs for amputees. In part, their argument centered on the preventive benefits of a BiOM. Sure, the device is expensive. But isn’t the cost justified if it saves insurers money on painkillers, osteoarthritis treatments and other measures needed to treat the side effects of traditional prostheses? Ultimately, a Medicare code was issued; a handful of workers’ compensation providers have also agreed to pay for the BiOM. Still, wider acceptance by the insurance industry remains elusive.

David Conrod, a communications professional who lost his leg decades ago in an industrial accident in Canada, was one of the patients to testify with Herr. His BiOM system is paid for by a workers’ compensation plan, but he said he expects that more health insurers will come around to the idea of bionic prosthetics. “People default to what they know, and they don’t know bionics yet,” he said. “There aren’t millions of people on these products. But I think this is such a value-add for amputees...that it will become common. Many, many people will wear legs like mine.”


And yet to spend any time with Hugh Herr is to understand that he is already thinking beyond a world where bionics are used only to enable wounded people and toward a future where bionics are an integral part of everyday life. In less than 20 years, he told me, “it will be common to step outside and see someone wearing a robot, meaning a bionic of some kind.”

One afternoon at the biomechatronics lab, I watched a group of Herr’s doctoral students test an exoskeletal leg brace on the treadmill. The device, constructed from fiberglass struts, is intended to supplement the wearer’s capability—a construction worker might don one to lift a heavy load, or a Marine might wear one to walk an extra 50 miles with a pack on her back. Lately, the lab has become a veritable factory of similarly high-end bionics, from robotic limbs that can “read” the ground ahead and adjust power input and angle accordingly, to the pieces of a fully autonomous exoskeleton—an invention Herr and his team unveiled earlier this year to much fanfare in the Journal of NeuroEngineering and Rehabilitation.

“When you view the human being in terms of its locomotory function, some aspects are quite impressive,” Herr said. “Our limbs are very versatile: We can go over very rough terrain, we can dance, we can stand still. But...our muscles, when they do positive work, 75 percent is thrown out as heat and only a quarter is mechanical work. So we’re pretty inefficient, we’re pretty slow and we’re not terribly strong. These are weaknesses we can fix.”

The next frontier for bionics, Herr believes, is neurally controlled devices. For now, the BiOM works independently from the brain, with an algorithm and a processor governing the prosthetic’s movement. But Herr is working on sensors that can tap into the body’s nervous system—eventually we could see a prosthetic controlled by the brain, muscles and nerves.

Of course, as Herr is quick to acknowledge, it is impossible to think of the mating of flesh and robotics without thinking of the dystopian fiction of Philip K. Dick or movies like the Transformers series, where machines have eclipsed humanity. “The fear is that the mating will be such that the human, however that’s defined, is no longer in control,” he allowed. Herr recently presided over the founding of the Center for Extreme Bionics at MIT, which will explore more experimental forms of robotic engineering. As part of the center’s activity, he hopes to convene a group of lawyers, scientists and philosophers to help guide “policy around augmentation.”

“We’re going to advance technologies in this century that just fundamentally change human capability,” he told me. “And there’s real beauty in that—there’s real advantage to humanity in that you can eradicate disability. There’s also real risk, so we need to develop policy commensurate with these new technologies. And in my view the drivers of policy around augmentation technology should focus on enhancing human diversity.”

Eventually, he suggested, prosthetics could become a lifestyle choice, like a nose piercing or a tattoo—“where our bodies are an art form and we can just create any type of body. Then we see a death of normalcy, a death of standard views of human beauty. Then you walk down the street 50 years from now and it’s like the cantina scene in Star Wars. That’s what I want.”


On a humid day this summer, I met William Gadsby at a restaurant in Northern Virginia, where he now lives with his wife, Tatiana, who is a computer programmer, and their 5-year-old son. Four years ago, after much lobbying, Gadsby received approval from the Veterans Administration to join an early BiOM testing program for above-the-knee, or transfemoral, amputees. (The device had been used for below-the-knee amputees because the diminished gait of transfemoral amputees is significantly more difficult to compensate for.) Running a hand through his close-cropped blond hair, Gadsby recalled reporting to his prosthetist’s office for the fitting—a lengthy process where the BiOM’s firmware is synced to the user’s gait.

“I don’t think most ‘organic’ people, as I refer to them, understand the energy return they get from their feet,” Gadsby said. “But when you’re on that carbon-fiber’re using upwards of 100 percent more energy just to get around, and man, it hurts. It does. With the BiOM, it felt like I was going from using a bicycle to a Ferrari. I was getting energy return. I was getting propulsion. It felt real.”

I followed him out to the parking lot. Gadsby fished his carbon-fiber foot out of his backpack for me to hold. It was light, but when he told me to smack the sole against my palm, I saw what he meant—there wasn’t much give. “Now watch this,” he said, and took off across the pavement at an impressive clip, the BiOM pistoning away underneath him. He returned grinning.

“Now I can hike,” he said. “I can drive all the way to Florida. I can cart a bunch of heavy suitcases when we go on vacation. I can throw my son on my shoulders and walk around with him. I can be a dad. The bottom line is that I’ve always tried to make sure my wounds aren’t my family’s wounds. The BiOM allows me to do that.”


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