A flying platform from ETH Zurich is made up of autonomous wheeled vehicle that lock together to share the task of controlled and autonomous flight. The robot, dubbed the "Distributed Flight Array," was presented by Raymond Oung, Raffaello D'Andrea, and others at this year's IEEE International Conference on Robotics and Automation (ICRA) and was a finalist for best conference paper.

Each wheeled vehicle has its own power, motor, propeller, flight control system, sensors, and wireless communication. The researchers write on their website:

Joined together, however, these relatively simple modules evolve into a sophisticated multi-propeller system capable of coordinated flight.

The individual robots dock together at random, bound by magnets. But the robots doesn't simply fly in a locked positions with the others. They form a network, exchanging sensor information so that each robot can figure out how much thrust is needed (based on its place in the system) for the whole array to take off.

Once the system is hovering, the robotic modules can correct for disturbances, based on their place in the configuration and the system's overall motion. When the robot is done flying, it breaks apart and each robot falls harmless to the ground. See it in action in a 2009 video below.

Interesting stuff--this could be useful for situation of surveillance or search and rescue, where you might have to figure out on the fly what size and shape robot you need. Also, a robot made of many identical modules like this is likely to be more robust--if one parts breaks, it can reconfigure or substitute in a different one.