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Energy-harvesting backpack to lighten load for U.S. soldiers

August 16, 2016

Associate Professor Lei Zuo
Lei Zuo, associate professor and John R. Jones III Faculty Fellow of Mechanical Engineering

United States Army soldiers on 72-hour missions sometimes carry seven types of batteries weighing up to 16 pounds in order to operate night vision goggles, communications, and GPS equipment. But by using innovative technology designed by Virginia Tech researchers, soldiers will soon have a lighter, more energy-efficient load to bear.

An Army grant of more than $344,000 has been awarded to Lei Zuo, associate professor and John R. Jones III Faculty Fellow of Mechanical Engineering, to create a backpack energy harvester.

The technology, which is expected to weigh about one pound with a harvesting capacity of 5-20 watts, will lead to lighter packs for military members, decreased supply chain requirements, and fewer muscular and skeletal injuries caused by heavy packs, improving the overall health of the soldier.

“By using mechanical motion rectifier (MMR), a technology converting oscillatory vibration motion into unidirectional rotation and scaling it down, we will work to create a device that sits on the frame of a soldier’s pack and harvests energy to recharge batteries as the soldier walks,” said Zuo. “This work builds on my previous work in energy harvesting.”

In the same way that ocean waves drive the MMR as they approach and depart an ocean energy-harvesting buoy, the backpack technology works to gather power as a soldier’s pack moves up and down as the soldier walks, with the multidirectional motion of walking converted into the unidirectional rotation of a generator.

“Because the generator rotates at a steady speed with higher efficiency, it provides higher energy conversion efficiency and enhanced reliability over packs with conventional rack pinion systems,” Zuo said. “More important, the MMR motion will change the dynamics of a suspended backpack and enable it to harvest more electricity with less human metabolic cost.”

The harvester will be developed and tested at Virginia Tech during the first year of the project and integrated into the backpack for testing and demonstrations at the Army Communications-Electronics Research, Development, and Engineering Center in the second year.

Written by Rosaire Bushey

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