Harvesting energy while walking
June 23, 2011
WEST POINT, N.Y. (June 22, 2011) -- West Point’s Departments of Civil and Mechanical Engineering and Physical Education are collaborating with the U.S. Army Natick Soldier Research, Development and Engineering Center and SpringActive Inc. with testing on the Soldier Power Regeneration Kit, or SPaRK.
SPaRK is a biomechanical energy harvester, a device that is attached to a Soldier’s boots to harvest energy, while the Soldier is walking, that can be used to power batteries.
“This is still a work in progress,” Jeff Ward, a mechanical engineer at SpringActive Inc., a company specializing in research and development in biomechanics, said. “Basically, when a person takes a step, the body falls over the ankle, which is energy we can harvest while minimizing the metabolic cost to the person wearing SPaRK. In Phase I of the project, the metabolic cost at slow speeds was negligible. It wasn’t until they moved at faster speeds that the metabolic costs started to rise.”
Energy is produced while walking or running and this energy can be captured using springs to capture it as the center of mass of the body rotates over the stance. This energy is found from the heel strike to midstance of the gait cycle.
West Point is running the initial performance testing under the direction of William Brechue, Ph.D, a DPE professor, and Becky Zifchock, Ph.D, adjunct professor in CME.
“The basic premise is to see if energy can be harvested from a person in normal walking mode,” Lt. Col. Bruce Floersheim, academy professor in CME and Mechanical Engineering design group director, said. “Ideally, a working device can reduce the amount of batteries that must be carried (by a Soldier). The key for the testing is to see what affect this device has on the individual in terms of extra physical cost.”
The idea for Phase I of the SPaRK project originally began with Lt. Col. Joseph Hitt, CME assistant professor, when he began working with cadets on a capstone project creating a bionic foot, but became a team effort with Natick SRDEC and SpringActive.
“This is still a working partnership, but it began as a capstone project with faculty and cadets,” Zifchock said.
The testing of volunteers who walked with the device answered questions regarding how the device felt while walking, what the metabolic cost is to the individual and comfort.
“We are having some challenges,” Ward said. “The device weighs 1.5 kg, (a little more than 3 pounds) and we would like to get the weight down. Another challenge is to try to customize SPaRK for the individual.”
However, they are getting positive results as well.
“We can get 4 watts (per step) of energy just from walking,” he said. “We can produce 15 watts when doing knee bends. From the development standpoint, we are learning so much about metabolic cost and we have proved the concept.”
Maj. Ryan Nenaber, a DPE instructor, demonstrated SPaRK on June 16 having never worn the device before.
“It feels like you’re walking in a ski boot,” Nenaber said. “Just imagine what you can do with this if people wore them while working out on an elliptical machine at a gym.”
Nenaber said that carrying batteries in the field can become quite heavy and likes the idea of a device that will lighten the load of a Soldier in the field.