Developed by scientists from the University of Southern Denmark, the charging technology could be utilized by drones carrying out a wide variety of tasks. That said, it's intended first and foremost for use by autonomous drones performing power line inspections. After all, those copters are already going to be within easy reach of the lines at all times.

Viet Duong Hoang and colleagues started with a commercial Tarot 650 Sport carbon fiber drone frame, then added an electric quadcopter propulsion system, a 7,000-mAh lithium-polymer battery, and electronic components such as a Raspberry Pi 4 B microcomputer, a Pixhawk V6X autopilot module, plus a millimeter-wave radar unit and an RGB video camera.

Importantly, they also installed a passively actuated power-line-gripper on top of the drone. This device sits within a cable guide consisting of two widely spread inward-sloping arms.

When the drone's onboard software detects that its battery is getting low, the aircraft uses its camera and radar to spot the closest power line. The aircraft then flies straight up toward that line from underneath.

Upon reaching the power line, the drone's cable guide directs the line into the gripper. As the line goes in, it pushes down on two elastomer ribbons spanning the open space between the gripper's two rubber sides. This action causes those sides to quickly close together overtop of the power line – no electricity required.

That said, once the line has been gripped, a magnetic control circuit kicks in to power the gripper, keeping it firmly closed around the line as the drone hangs beneath. A top-located inductive charger on the drone then starts drawing current from the power line. Once the aircraft's battery is fully charged, the gripper opens and the drone can resume its line-inspecting duties.