New Zealand-born Daniel Wilson, a researcher at the University of Sydney’s Australian Centre for Field Robotics, has developed a method to allow UAVs to dock and recharge in mid-air, much like military jets do. He believes his team’s successful UAV docking in November last year was a world first.
Using an off-the-shelf, but highly-modified fixed-wing UAV — which generally has a battery life of around an hour — the Sydney University team spent years working on a process that would allow a UAV to dock and refuel or recharge while in flight.
The successful method works by a system of highly-coordinated GPS, inertial motion sensor and infrared technology onboard two UAVs — one leader and one follower — and a refuelling station.
The leader craft flies in a circuit pattern, Wilson said, towing the cone-shaped station or “drouge”, while broadcasting its onboard sensor data. Using that data, the follower UAV tries to fly in formation with the leader. Once it’s successfully aligned, the follower then finds and attaches its nose to the drouge for final docking and refuelling.
According to Wilson, the docking stage was the most difficult to get right — particularly as the two small aircraft and drouge were constantly being buffeted by wind and turbulence.
In the short term, he said, the system is probably of most use to the military for refuelling their larger UAVs. But Wilson’s method could also be useful anytime a UAV needed to navigate really accurately — for example, a precise landing on a moving object, like a boat.
While getting a UAV to actually recharge in mid-air is more of an engineering problem, Wilson said, his team is also looking at applying their method to the autonomous capture of UAVs in flight. Using this technology, he suggested, an operator could have one large UAV carry a number of smaller UAVs.
“You might release them, have them do some sort of task like search, and then gather them back up and keep flying,” he added. “That’s really good if you want to cover a large area quickly.”