Human Body Spare Parts: the Robotic Ankle


A new prototype robotic ankle is now being tested on several people and could eventually be used to replace lost limbs for US soldiers who suffered injuries in the Iraq war. The new prosthesis is an artificial extension than could go almost unnoticed due to its strong resemblance to the human ankle and its locomotion.

Most prostheses are just artificial extensions that replace a missing body part. They are applications typically used to replace parts lost by injury (traumatic) or missing from birth (congenital) or to supplement defective body parts.

Not all of them succeed in replacing more than just the visual aspect of the body and some of them are just too stiff and ready to wear, becoming more of an aesthetic appendix instead of a functional substitute for the leg or arm.

A joint effort of MIT Media Lab, done by Professor Hugh Herr and researchers in the lab's biomechatronics research group, created a new robotic ankle that really does more than acting as balance aid.

The new powered ankle-foot prosthesis was tested on Garth Stewart, 24, who lost his left leg below the knee in an explosion in Iraq, and it was a complete success, thanks to the fact that the veteran is continuously propelled forward by the prosthesis, which uses tendon-like springs and an electric motor.

Thus, the person feels less fatigue while experiencing improved balance and a more fluid gait. Professor Herr is also a double amputee and wanted to try his invention on himself: "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." That's 30% more energy spared by the person wearing the new robotic ankle, which could mean more time spent outdoors, or just the ability to get out for a walk, despite the harsh fate.

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