PowerFoot One: Active Ankle-foot Prosthesis from MIT Unveiled

Yesterday at the Veterans Affairs Medical Center in Providence, R.I., a group of researchers and engineers from MIT and Brown University unveiled a novel robotic ankle that not only provides a prosthesis to stand or walk on, but also “propels users forward using tendon-like springs and an electric motor.” We have originally reported about this device in February 2005, when it was in an early prototype stage. Now, according to Reuters, the device should become commercially available in Summer 2008 through a recently formed iWalk, Inc., based in Cambridge, Mass.
From the MIT press office:

Garth Stewart, 24, who lost his left leg below the knee in an explosion in Iraq, demonstrated the new powered ankle-foot prosthesis during a ceremony at the Providence, R.I., Veterans Affairs Medical Center. Stewart walked in the device, which, unlike any other, propels users forward using tendon-like springs and an electric motor. The prototype device reduces fatigue, improves balance and provides amputees with a more fluid gait. It could become commercially available as early as the summer of 2008.
MIT Media Lab Professor Hugh Herr and his team of researchers developed the ankle-foot. Herr, NEC Career Development Professor and head of the biomechatronics research group at the Media Lab, is a VA research investigator. He is also a double amputee who tested his invention: “This design releases three times the power of a conventional prosthesis to propel you forward and, for the first time, provides amputees with a truly humanlike gait,” Herr said.
“It’s wild,” he said, “like you’re on one of those moving walkways in the airport.”
Because conventional prostheses only provide a passive spring response during walking, they force the amputee to have an unnatural gait and typically to expend some 30 percent more energy on walking than a non-amputee. The new ankle is light, flexible, and — most importantly — generates energy for walking beyond that which can be released from a spring alone.
This is accomplished through a device equipped with multiple springs and a small battery-powered motor. The energy produced from the forward motion of the person wearing the prosthesis is stored in the power-assisted spring, and then released as the foot pushes off. Additional mechanical energy is also added to help momentum.

Press release: Joint effort: Robotic ankle research gets off on the right foot …
VIDEO of the device…
iWalk…
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