Although computer-controlled artificial legs have been around for a few years now, they generally still feature an ankle joint that only allows the foot to tilt along a toe-up/toe-down axis. That's fine for walking in a straight line, but what happens when users want to turn a corner, or walk over uneven terrain? Well, in some cases, they end up falling down. That's why researchers at Michigan Technological University are now developing a microprocessor-controlled leg with an ankle that also lets the foot roll from side to side.
Created by mechanical engineer Prof. Mo Rastgaar and PhD student Evandro Ficanha, the current version of the prosthesis incorporates pressure sensors on its bottom surface. These detect the manner in which the user is walking, and relay that information to a microprocessor. It responds instantaneously by adjusting the angle of the foot via the ankle joint, to facilitate a more stable, natural gait.
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The final version of the Michigan Tech leg should also be lighter than similar products, as the microprocessor and motors won't be contained within the prosthesis itself. Instead, they'll be in a control box that will be worn higher up on the body, conceivably in something like a backpack. A housed steel cable will run from that box down to the leg, causing the ankle to move as dictated.
In order to assess the performance of the leg, the scientists built a motorized turntable, that allows a prototype prosthesis to endlessly walk in circles. So far, lab tests have shown that the leg is "able to copy the angles of a human ankle walking in a straight line and turning."
Rastgaar and Ficanha plan on refining the prosthesis next year at the Mayo Clinic, which is a partner in the project.
The leg can be seen in action in the video below.