Artificial Foot Reuses More Energy Every Step of The Way

At the University of Michigan, Ann Arbor engineers have developed prosthetic foot technology that can intelligently transfer what would otherwise be lost energy into powering the foot’s next step. Because more energy can be saved over currently available models, this technology should lead to smaller and lighter artificial legs.

In their energy-recycling foot, the engineers put the wasted walking energy to work enhancing the power of ankle push-off. The foot naturally captures the dissipated energy. A microcontroller tells the foot to return the energy to the system at precisely the right time.
Based on metabolic rate measurements, the test subjects spent 14 percent more energy walking in energy-recycling artificial foot than they did walking naturally. That’s a significant decrease from the 23 percent more energy they used in the conventional prosthetic foot, Kuo [Art Kuo, professor of Biomedical Engineering and Mechanical Engineering] says.
“All prosthetic feet store and return energy, but they don’t give you a choice about when and how. They just return it whenever they want,” Kuo said. “This is the first device to release the energy in the right way to supplement push-off, and to do so without an external power source.”
Other devices that boost push-off power use motors and require large batteries.
Because the energy-recycling foot takes advantage of power that would otherwise be lost, it uses less than 1 Watt of electricity through a small, portable battery.

Video of the device and relevant links after the fold: