How to recharge drones while airborne Friday, 21 October 2016

Scientists from Imperial College London have demonstrated a highly efficient way to wireless transfer power to a drone while it is flying, opening the way for flying drones to stay in the air indefinitely.

The wireless power transfer is via an inductive coupling mechanism. This is not a new technology, as it was first demonstrated by Nikola Tesla over a century ago. Two copper coils are tuned into one another using electronics, allowing the wireless exchange of power at a certain frequency.

While inductive coupling is nothing new, scientists have until now been unable to wirelessly power flying technology. 

The Imperial College scientists demonstrated their breakthrough by removing the battery from an off-the-shelf mini drone. They then modified the drone by altering its electronics and installing a copper foil ring, which acts as the receiving antennae, encircling the drone's casing.

On the ground, they made a transmitter device which creates a magnetic field. The drone’s electronics are tuned or calibrated at the frequency of the magnetic field. When it flies into the magnetic field an alternating current (AC) voltage is induced in the receiving antenna and the drone’s electronics convert it efficiently into a direct current (DC) voltage to power it.

Thus the team were able to power a flying drone entirely via inductive coupling. According to them, by demonstrating efficient wireless charging for a flying object, they have paved the way for wider use of the technology.

Drone of the future may need simply hover over a ground support vehicle or a charging point to recharge, allowing greater flight times and distances, with potential new industrial applications.

The technology is still in its experimental stage. The drone can only currently fly ten centimetres above the magnetic field transmission source. The team estimate they are one year away from a commercially available product.

With drones continuing to get smaller and more affordable, their potential applications continue to grow, whether for surveillance, for reconnaissance, for agricultural monitoring or search and rescue. However, the distance that a drone can travel and the duration it can stay in the air is limited by the availability of power and battery capacity and weight. Wireless power transfer technology may solve this.

Wirelessly transferring power could have also applications in other areas such as sensors, healthcare devices and further afield, on interplanetary missions. Another possibility is to use drones to transmit power to infrastructure and devices such as sensors that are located in precarious positions, eliminating the need for humans to physically access difficult-to-reach equipment to recharge them.