Small Unmanned Aerial Vehicles(UAVs) are fun to build, watch, and operate. Innovations with the current design of mini-UAVs may have them charging electronic devices soon. Researchers at University of Nebraska-Lincoln's NIMBUS labs have used a quad rotor helicopter to charge electronic devices wirelessly.
The method used for wireless transmission of energy is called strongly coupled magnetic resonances. It works using two coils of wire, one attached to the UAV and one attached to the electronic device to be charged. While the UAV is in flight current flows through the attached coil. Consequently, an oscillating magnetic field is created which radiates from the coil on the quadcopter. If this oscillating magnetic field enters a region close enough to another coil of wire, the second coil will start to resonate thus inducing a voltage. The voltage can be used to charge whatever device to which it is attached.
The research team has been working on ways to optimize the power output using algorithms. So far they have found that the optimal distance to transmit power wirelessly is around 20cm which transfers 5.5 watts of power with 35% efficiency. An algorithm using sensors would work better to keep the UAV in a stable hover over the target. In addition, the UAV has to be near perfectly perpendicular to the surface in which the coil is resting for an optimal power transfer rate.
The whole idea could work great for small sensors and electronics located in hard to reach places. Researchers stated that possible applications can include, “highway messaging systems, ecological sensors located in forests, or sensors shallowly embedded underground or in concrete.” Maybe one day iRobot or Google will have a fleet of these things to deploy for our services. Or maybe one day we can have our own personal one for convenience and recreational purposes.