Engineers Develop Tripod Prosthesis and Prosthetic Emulator

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Mechanical engineers at Stanford University have designed a prosthetic foot that responds to rough terrain by actively shifting pressure between three contact points. The design is a tripod with a rear-facing heel and two forward-facing toes. Equipped with position sensors and motors, the foot can adjust its orientation to respond to varying terrain, similar to the way in which someone with an intact foot can move their toes and flex their ankles to compensate while walking over rough ground.

In the process of designing the device, the engineers also developed a tool to test the prototypes more quickly. Rather than first building a prosthesis for real-world testing, the researchers built a basic version, then hooked it up to off-board motors and computer systems that control how the foot responds as a user moves over varying terrain.

"Prosthetic emulators allow us to try lots of different designs without the overhead of new hardware," said Steven Collins, PhD, an associate professor of mechanical engineering and a member of Stanford Bio-X, the university's interdisciplinary biosciences institute. "Basically, we can try any kind of crazy design ideas we might have and see how people respond to them," he said.

The research team has reported results from one tester, a man with a transtibial amputation, and say the early results are promising.

The device construction and first tests of the prosthetic emulator are described in a paper published in April's IEEE Transactions on Biomedical Engineering.

Editor's note: This story was adapted from materials provided by Stanford University.