So far, the algorithms they developed have been used only in a simulation, as part of a National Science Foundation project. MIT's Han-Lim Choi, who has been working on the algorithms as part of his PhD research, presented the latest results of the project last week at the IEEE Conference on Decision Control in Cancun, Mexico. The work has attracted the interest of the U.S. Navy, and the MIT group is applying for funding to put the algorithms into practice, says How.

One of the challenges presented by the project is fuel management, says Dario Floreano, an expert in flying robotics and head of the Laboratory of Intelligent Systems at the École Polytechnique Fédérale de Lausanne, in Switzerland. The algorithms will need to be able to quickly and efficiently reroute the UAVs so that they maintain optimal coverage, he says. "This will have to take into account many variables, including energy requirements for different reallocation strategies."

Another challenge is size, says Floreano. The UAVs need to be small and safe enough to not harm humans and objects if they are deployed in large numbers. He points out, however, that subkilogram UAVs are now becoming available.

In fact, How and his colleagues are more interested in testing their algorithms on the relatively large ScanEagle UAVs from Boeing, which weigh about 18 kilograms apiece. These would be capable of flying distances in excess of 1,000 miles, even laden with sensors and communications equipment. With this sort of range, a fleet of just four could reasonably cover a good-sized area, reducing the risk of collisions with manmade objects.