Military planners are looking to drone swarms as both a threat and opportunity as the technology develops into a way to attack, defend or even deliver logistics.
But short-range, small drone swarms have a problem: flight time.
Most man-portable drones can run for less than 30 minutes before needing a recharge. That’s fine for a suicide drone not coming back to its pilot or even for a scouting drone doing a quick reconnaissance.
But when the plans call for dozens, hundreds, perhaps thousands of drones to flood the low-flying airspace, what’s a drone operator to do?
Well, Army researchers are tackling that problem with a variety of methods. One of which includes an Unmanned Ground Vehicle weaving across the land space, acting as a charging station for hordes of drones as they conduct their resupply missions.
“Imagine in the future, the Army deploying a swarm of hundreds or thousands of unmanned aerial systems,” said Mike Kweon, program manager for the Army Research Laboratory’s Versatile Tactical Power and Propulsion Essential Research Program.
And if launched at the same time, that means most could be returning at the same time, all needing a place to charge.
His team is finding ways to use better algorithms so that drones can find the optimal flight paths out to targets and back, conserving energy as the go.
For now, the recharge involves drones landing on or near the UGV and being plugged in by a soldier. The goal is first to remove the soldier from that chain of events, then allow for touch charging, much like a smartphone where the drone can land on the UGV and charge without having to be hooked up.
The long-term goal is to achieve wireless recharging so that drones could hover in clusters near the UGV and receive their charge, which would save time and space.
And wireless charging would remove the major hurdle of landing the drone in the correct location and orientation, which Kweon said presents its own set of challenges.
“You cannot just land it, it will just fall off,” Kweon said. “You’ve got to have a magnet to hold it, charge it then depart.”
“It should do this autonomously,” he said.
Researchers are in year two of a five-year program to meet the charging demands. They are targeting on-platform recharging within the next one to two years.
But at the center of all things power are the batteries themselves. Faster recharging batteries will be key to making this concept a reality, he said.
For example, the Raven drone takes two hours to charge. But even smaller-scale drones can take a while. That’s not feasible to keep them in the fight or rotating through the mission.
“We need to achieve that within six minutes,” Kweon said of smaller drone charging.
For that, program leaders are looking to industry ideas that will ramp up charging speed and find ways to achieve wireless charging, said Mark Tschopp, lead for the ARL central region.
Todd South has written about crime, courts, government and the military for multiple publications since 2004 and was named a 2014 Pulitzer finalist for a co-written project on witness intimidation. Todd is a Marine veteran of the Iraq War.