The dream of the flying car could come down to earth soon as several start-ups like Chinese EHANG and Uber are developing so-called "passenger drones(无人机)"—self-flying drones big enough to ferry individual commuters around town—which could shrink commute(上下班往返) times from hours to minutes.
At first glance, human-carrying drones sound no more realistic than flying cars. Until recently inventors had never been able to marry automobiles and aircraft in a practical way. Yet a few companies have kept at it: Woburn, for example, has since 2006 been developing Transition, a "roadable aircraft" that resembles a small airplane that can fold its wings and drive on roads. A personal flying car in every garage has proved to be a tough sell, however, as there are serious safety concerns about asking the average commuter to train for a pilot's license and take to the skies.
Passenger drones, by contrast, would operate autonomously and leave the "roadable" part behind in favor of larger versions of aircraft that already exist. Passenger drone designs favor "distributed electric propulsion(推进)," meaning instead of one large rotor powered by a large engine they have multiple propellers each powered by its own, smaller motor. This sacrifices lifting power and flight performance in exchange for mechanical simplicity and lighter weight—factors that could make them cheaper to operate. Quieter electric power would make the noise tolerable to city residents, although it remains to be seen how much weight such a vehicle could lift, and for how long.
With any of these vehicles, safety is the biggest concern and extends to both the aircraft and the automated systems flying them. Advanced artificial intelligence is needed to fly large numbers of autonomous aircraft without crashing them into one another or, say, the local news channel's traffic helicopter. Carrying people from points A to B seems simple enough, but even the best AI struggles with surprises: What, for example, would a drone do if a landing area suddenly became unavailable? asks Sanjiv Singh, a Carnegie Mellon University robotics researcher. Instead of leaping to fully automated passenger drones, he suggests first testing the necessary AI in unmanned cargo(货物)runs, and adopting a "mixed mode" approach in early passenger services where pilots are assisted by AI co-pilots.
Technical challenges aside, start-ups promoting the technology will have to find a way to convince the public to give their drones a whirl, something that requires a much bigger leap of faith than getting into the backseat of a self-driving car. Passenger drone makers are "obviously still in the incubation(孵化) stages of technology development and improving the basics," says Mike Hirschberg, executive director of the American Helicopter Society International. "But 20 or 30 years from now life may be a little like The Jetsons where you take advantage of the third dimension and have much more mobility, especially in urban close quarters where ground transportation is gridlocked."
The passenger drone progress may follow a sloping takeoff rather than vertical leap. Carnegie Mellon's Singh sees a long road ahead filled with lots of testing, analysis, regulation and efforts to win the public's trust before the technology becomes a viable transportation option. "There is the danger of someone moving too fast and then having a problem that sets the industry back for some time," he says.
