Engineering Professor Demonstrates Robotic Ankles

Hugh Herr can phone his ankles.

An associate professor at the MIT-Harvard Div. of Heath Sciences and Technology, he can do that because, after losing his legs 28 years ago, he refused to accept the state of the art in prosthetic technology.

"Sadly, most people with disabling conditions are not well-served by technology," Herr says. "But I predict that in the twilight years of this century, disabilities will be eliminated."

During a keynote speech at the Freescale Technology Forum (FTF) yesterday, Herr rolled up his pant legs before a crowd of more than a thousand engineers and bounded up and down the stairs of the stage at the Grand Lakes Hotel in Orlando. That's an activity that might be difficult for individuals with conventional prosthetic legs, as well as for many with "normal" human legs.

But it's not hard for Herr. Using a springy robotic ankle mechanism that would make Iron Man jealous, Herr has developed an artificial joint like none that's ever existed.

"When I walk slowly, the computer knows it," Herr says, ambling across the stage. "But when I go up, I get more reflexive power because it knows I'm climbing the stairs."

His ankles are able to do that because he's endowed them with biomechatronic components — a motor, spring, lithium-ion battery, 12 different sensors and five microcontrollers from Freescale Semiconductor Inc. To reprogram the software in his ankles, he merely contacts their RF transceivers by phone. It's the ultimate in artificial limbs, in some ways better than the originals.

Herr was motivated to design the new limbs after frostbite rendered his legs useless below the knees following a mountain climbing incident in 1982. After both legs were amputated, Herr's engineering motivation went into high gear. He now looks for solutions to all manner of disabilities, from brain and spinal cord injuries to limb amputations.

"From my experience, I realize that technology has the ability to heal, to rehabilitate," he says.

Herr imagines a future where individuals wear exoskeletons. He foresees a world in which robotic carpets and furniture incorporate the ability to soften the blow when the elderly fall. He predicts amputees will don robots and then control them with neural interfaces. He even believes that robotic systems will enable commuters to run to work, while barely breaking a sweat. Studies, he says, have proven that when the force of gravity is reduced by 75 percent, the metabolic rates associated with walking and running drop by 33 and 72 percent, respectively.

"We think that in the future, people will wear robots when they walk or run," he says. "Why? To save their knees and hips."

His company, IWalk, intends to fit robotic limbs to injured soldiers returning from Afghanistan and Iraq. Herr says the robotic limbs will enable the soldiers to enjoy a freedom of movement that's remarkably close to what they had before being injured.

"I get calls from people who, through injuries, have lost capabilities," Herr says. "They ask, 'Would it benefit me to amputate my limb and use a robot?' Remarkably, the answer is more and more a 'yes.'"

Some day, Herr says, the answer will always be a resounding yes. To make that day a reality, though, he must keep working and advancing the state of the art.

"A long time ago, conventional wisdom would have said, 'Hugh, give up; accept the technology as it is,'" he recalls. "But I'm not going to accept it as it is."