Every self-respecting sci-fi movie featuring an urban area has a sky crammed with hovering drones. Ever wondered what purpose these Unmanned Aerial Vehicles serve? Well, if they’re quadcopters they may well be mobile power stations.

Computer scientists Brent Griffin and Carrick Detweiler of the Nebraska-Lincoln University have turned a quadcopter into a flying wireless energy delivery system. The aim of the research is to provide sensors in remote locations with electricity. But we all know that once the system is up and running city dwellers will want one too.

As a carrier the scientists use a Hummingbird quadrotor helicopter made by Ascending Technologies. They added equipment weighing a total of 127 grams (4.5 oz). With this payload the flight time is between 15 to 20 minutes and the maximum speed 50km/h (31mph).

To transfer power wirelessly the scientists use what is called strongly coupled magnetic resonances. For this process two coils of wire are used, one on the quadcopter and one on the ground based device that needs charging. The two coils have the same resonant frequency. Powered by an onboard battery the copter’s coil generates an alternating magnetic field. If the ground based receiving coil is near enough it can pick up the energy and charge its battery.

In a manual test flight the UAV hovered over a receiver for 30 seconds at a distance of 25 cm. In that time 5W of power was transferred which is sufficient to recharge an average sensor.

Griffin and Detweiler continue to work on their creation. They want to improve the amount of power transferred and enable the UAV to navigate autonomously.

If you’re interested in a full scientific description read the paper by Griffin and Detweiler: Resonant Wireless Power Transfer to Ground Sensors from a UAV [PDF].



Photo: Ascending Technologies: Hummingbird quadrotor helicopter

Via: Spectrum.ieee.org