- 2018年04月26日15:49 来源：互联网
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Electronics has already cut the data cord. Can it now cut the power cord as well?
Jun 27th 2015 | Seattle | From the print edition
DRONES may one day transform the way parcels are delivered, crops monitored and suspects apprehended. Those who talk up these possibilities, though, often neglect to mention the drawbacks of such robot aircraft—one of which is that most cannot fly for more than a quarter of an hour before they need to find a human being to swap their batteries for them or plug them into an electrical socket.
Joshua Smith, a computer scientist at the University of Washington, in Seattle, hopes to change that. In May he started a company called Wibotic that plans to recharge drones (and also earthbound robots) without them having to establish an awkward physical connection with a plug. A ’bot whose batteries were low would simply manoeuvre itself to within half a metre or so of a recharging station to top them up. LaserMotive, another Seattle-based company, is even more ambitious. It is developing a system designed to replenish the batteries of drones that are still aloft, using lasers and photovoltaic cells.
只要有问题或者有需求就会有人想去改变，无人机用途那么广，总需要人来充电哪行?于是华盛顿大学一个哥们 JS 就搞了个公司 Wibotic，主要目的就是让无人机无需通过物理连接充电，否则那多尴尬啊，飞着飞着还得找个地方插上线充电，感觉特别low，如果能在空中无需通过物理连线就把电冲了就爽了，Wibotic 和 LaserMotive 这两家公司主要就是想实现无人机无线充电。
The idea of wireless power-transmission of this sort goes back more than a century. In 1893 Nikola Tesla (pictured), who was one of the pioneers of industrial-scale electricity, illuminated light bulbs across a room in a demonstration at the Columbian Exposition in Chicago. And that was a mere fleabite compared with his grander ambitions. He claimed to believe it possible to broadcast power around the world using a system of towers and balloons, and even convinced J.P. Morgan to back a trial.
He theorized from these experiments that if he injected electric current into the Earth at just the right frequency he could harness what he believed was the planets own electrical charge and cause it to resonate at a frequency that would be amplified in "standing waves" that could be tapped anywhere on the planet to run devices or, through modulation, carry a signal.
That failed, as most other physicists of the time predicted it would. More modest remote power-transmission is, however, now attracting attention again. The technology Tesla pioneered is already being used to charge mobile phones, and researchers are working on similarly wirelessly powered kitchen appliances, military equipment such as heads-up displays, and medical devices ranging from heart pumps to brain monitors.
Lasers aside, the principle behind most wireless power-transmission is a piece of basic physics known asinduction. In this process an alternating current passing through a coiled wire creates an oscillating magnetic field. That field then induces another alternating current in a second, nearby coil. If the transmitting and receiving coils are close together and aligned in the same direction, almost all of the power will be transmitted.
Inductively coupled systems like this thus work well for things like repowering electric toothbrushes. They would be impractical, though, for a drone trying to hover over a charging station. Wibotic’s answer is to use tuned electrical circuits in place of simple transmitting and receiving coils. When such circuits are tuned to the same resonant frequency, they exchange energy more efficiently.
For remote charging to take off metaphorically as well as literally, though, devices employing it need to be interoperable. That means establishing industry standards. Unfortunately, in a competitionreminiscent of that in the 1890s between alternating current (Tesla’s preference) and direct current (promoted by Thomas Edison), three main consumer standards have emerged.
The Tesla exception
The rise of electric cars opens yet another market for remote power-transmission. Carmakers are keen to avoid the standards war that has broken out among makers of smaller gadgets. If convenientwireless charging lets carmakers halve the size of electric-vehicle batteries, it could slashthousands of dollars from their prices. That would make a huge difference to the economics of owning and running them. Nikola Tesla failed to beam power between continents but his tricks may yet succeed in something equally dramatic: decarbonising the world’s road vehicles.
Those who talk up these possibilities, though, often neglect to mention the drawbacks of such robot aircraft—one of which is that most cannot fly for more than a quarter of an hour before they need to find a human being to swap their batteries for them or plug them into an electrical socket.
Those who talk up the benefits of X, though, often neglect to mention the drawbacks of X one of which is that...
Those who talk up the benefits of the Internet, though, often neglect to mention the drawbacks of the ubiquitous network connection one of which is that our private information is highly likely to be compromised by data breach caused by malicious hackers.
make a huge difference to：使产生很大的不同
oscillating magnetic field：震荡磁场
open a market for：打开市场
are keen to：热衷于
plug them into an electrical socket：插入电源插座
establish an awkward physical connection with a plug：和插座建立尴尬的链接