Microprocessor lends prosthetic legs a more natural gait

Robotic Leg Testing

Building a robotic leg that’s ready for the real world is more complicated than developing something that can walk on a treadmill. The world is full of bumps, hills and twists that require a prosthetic limb to be constantly adapting to new demands.

Michigan Technological University researchers will present a paper this month on a robotic leg they developed that can adapt to different terrains. The big improvement comes in the ankle, which is controlled by a microprocessor and can move side-to-side on top of the already common up-and-down motion.

“… In reality, we never walk in a straight line for any length of time,” Michigan Technological University mechanical engineering assistant professor Mo Rastgaar said in a release. “When you walk and reach an obstacle, you have to turn, and there’s always something in our way.”

“[The microprocessor and new motions] provide active control of the joint and improve safety and function,” Mayo Clinic Biomechanics/Motion Analysis Laboratory director Kenton Kaufman said in the release. “But the advantage of Mo’s foot is that it is biomimetic — it mimics biology — so it allows a more natural walking pattern to occur, which should result in a better gait and fewer falls.”

The leg works through a combination of pressure sensors and a microprocessor. The sensors are located on the bottom of the prosthetic foot, where they take in information about how the wearer is walking and send it to the microprocessor. The data is then used to adjust the leg to the most natural position.

The leg is driven by a cable, which runs between the ankle and a control box. The researchers situated the control box so it sits higher up on the leg. The limb then feels lighter and more comfortable.

Beginning in the summer of 2014, the Michigan team will collaborate with the Mayo Clinic on improving the design of the prosthetic leg. In the future, they hope to offer it to amputees, with a focus on veterans.

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