A novel attachment to the soldier’s assault pack might someday reduce the number of batteries carried to power night-vision devices, radios and other equipment, as well as help make dismounted patrols less fatiguing.
Courtney Webster, a biomedical engineer with the Army Research Laboratory, or ARL, is in the middle of testing with her team the prototype “Energy Harvesting Backpack” at the Soldier Performance and Equipment Advanced Research facility at Aberdeen Proving Ground, Maryland, according to a recent Army press release.
A frame-mounted to the standard-issue assault pack contains a two-spring, rack-and-pinion suspension system that allows it to gently glide up and down as the soldier is walking or running, Webster said. As the assault pack moves, the mechanical energy produced by the motion recharges the soldier’s battery, she said.
The other thing that happens is that the up-and-down motion is gradual and controlled. Without the attachment, this is not the case, she said, providing a comparison to a backpack full of school books that “bounces and slams your shoulders when running,” the release states.
For a control test, the assault pack minus the Energy Harvesting Backpack attachment is used, with the same amount of weight, she said. Test subjects spend a total of 10 minutes on the treadmill, walking or running at different speeds, different loads, different inclines, and, with the assault pack and with the assault pack plus the attachment.
Another device measures VO2, or maximal oxygen uptake. It’s used to calculate fatigue, she said. Put simply, the more oxygen subjects take in, the more fatigued they’ll become over time.
Finally, the charge of the battery is measured to determine how effective the attachment is in generating power, she said.
Thus far, 12 Army civilians and contractors have been tested, Webster said, noting that there are not that many soldiers on Aberdeen to test, and that soldier testing will definitely take place, but only once the system matures passed the preliminary research phase.
Perhaps the biggest limitation of the device, Webster said, is that it weighs 15 pounds. That’s not insignificant because soldiers are already heavily loaded down.
The weight offset would be fewer batteries to carry, and each battery is about the size of a paperback novel – not the tiny batteries found in stores, according to the release.
The other offset would be creating a lighter device. But that would be in the future, Webster said. For now, testing for weight wasn’t a goal, “we’re just trying to determine the energy output we get. We need that knowledge first before proceeding.”
The immediate goal is to get a total of 20 people tested, Webster said. At that point, all of the data will be aggregated and results will be published sometime next spring, according to the release.
All of that data will also be fed to the U.S. Army Communications-Electronics Research, Development and Engineering Center, or CERDEC, the organization that requested ARL do the testing, she said.