New technology of flying drones re-charge

Added On October 31, 2016

Developed by engineers at Imperial College London, a new technology allows flying drones to stay airborne while charging. 
The method has also opened up new potential applications in commercial, cultural, medical, transportation and military areas.
The technology uses inductive coupling, a concept initially demonstrated by the inventor Nikola Tesla over 100 years ago. 
As Professor Paul Mitcheson introduced, the application of wireless power technology has been realized in lots of areas of daily life, such as wireless recharging of smartphones, and electronic tooth brushes. 
However, Mitcheson believes that it is the first time to display how this wireless charging method can be efficiently applied to a flying drone.
SOUNDBITE (ENGLISH): PAUL MITCHESON,  Director of Wireless Power Lab of IC
"I don't know some of them you maybe familiar with the mobile phone charging technology that you place a phone onto a charging pad and then you charge your mobile phone without having to plug in. Other people might have an electronic tooth brush that you place on a little support and it will charge. Both of these systems are indeed wireless power delivery systems. But they only work over a very very small gap and what we are trying to do here is work on broadly the same technology but make it much more capable." 后面的删掉
Dr Samer Aldhaher explained two main challenges regarding the implementation of the technology. 
"So there are two main challenges. The first one is how do you develop, how do you generate this magnetic field and all the electronics behind it. And then the second challenge is how can you put all the electronic parts of the drone, make them very small compact and very light weight. Because of the drone can't lift too much weight, so you don't want to be adding all of the weight on the drone. These two challenges we managed to solve them to searching next step. So I will transmitter here, you can work very very inefficiently at very high power levels. And also as you see on the drone here, we've been clever here by using the guard around the drone at the receiving antennae. And all the electronic sound boards are very very small, such that they don't add weight to the drone. So this is what we developed and this is the challenge we overcome."
The technology is still in its experimental stage as the drone can only currently fly ten to twelve centimeters above the magnetic field transmission source. 
However, Mitcheson believes that the commercial availability is near.
SOUNDBITE (ENGLISH): PAUL MITCHESON, Director of Wireless Power Lab of IC
"With drone charging, ideally you would like to have a much wider range while you can charge the drone over and this will charge within about one coil diameter. So if you look at the size of this, you've got basically a distance between the transmit coil and the receiving coil that is about one coil diameter so after about here. There is a kind of fundamental limit as to what you can achieve in terms of distance, we think we can probably push it to around two coil diameters with improvements to the technology. So that means if you want more range you need a bigger coil. So a bigger drone will be able to go further away or bigger charging pad means you'd be able to go further away. But I think realistically what we are looking at here is a technology that is light weight enough. The drone can carry the receiving equipment. It can land on a charging pad. It can charge it can fly away again. And that massively simplifies the charging mechanism from an autonomous drone system."