Walking may not seem like a feat of agility, balance, strength and brainpower. But lose a leg, as
Taking on the challenge, a team of software and biomedical engineers, neuroscientists, surgeons and prosthetists has designed a prosthetic limb that can reproduce a full repertoire of ambulatory tricks by communicating seamlessly with Vawter's brain.
A report published Wednesday in the
For the roughly 1 million Americans who have lost a leg or part of one because of injury or disease, Vawter and his robotic leg offer hope that future prosthetics might return the feel of a natural gait, kicking a soccer ball or climbing into a car without hoisting an inert artificial limb.
Vawter's prosthetic is a marvel of 21st century engineering. But it is Vawter's ability to control the prosthetic with his thoughts that makes the case remarkable. If he wants his artificial toes to curl toward him, or his artificial ankle to shift so he can walk down a ramp, all he has to do is imagine such movements.
The work was done at the Rehabilitation Institute of
"We want to restore full capabilities" to people who have lost a lower limb, said
Weighing just over 10 pounds, the leg has two independent engines powering movement in the ankle and knee. And it bristles with sensors, including an accelerometer and gyroscope, each capable of detecting and measuring movement in three dimensions.
"With this leg, it just flows," said Vawter, a 32-year-old software engineer, who spends most of his days using a typical prosthetic and travels to
Before Vawter could strap on the bionic limb, engineers in
At the institute's
Using pattern-recognition software, engineers discerned, distilled and digitized those electrical signals to catalog a repertoire of movements. The prosthetic could thus be programmed to recognize the subtlest muscle contraction in Vawter's thigh as a specific motor command.
Within a few months of the amputation, those nerves had recovered from the shock of the injury and begun to regenerate and carry electrical impulses. When Vawter thought about flexing his right foot in a particular way, the rerouted nerve endings would consistently cause a distinctive contraction in his hamstring. When he pondered how he would position his foot on a stair step and ready it for the weight of his body, the muscle contraction would be elsewhere - but equally consistent.
Vawter said he had "fallen down a whole bunch of times" while wearing his everyday prosthetic, but not once on his bionic leg.
He said he could move a lot faster too - which would be helpful for keeping up with his 5-year-old son and 3-year-old daughter. But first, Vawter added, he needs to persuade Hargrove's team to let him wear it home.