Fly-O-Rama!

Dickinson recently moved his lab to the California Institute of Technology in Pasadena, where he and his students are continuing to develop machines to study insect flight, such as the Rock-and-Roll Fly Arena, a flight simulator for fruit flies. The arena is a hollow cylinder 6 inches in diameter; 12,000 light-emitting diodes line its inner wall. Dickinson's team glues a fly to the tip of a steel rod at the center of the arena, leaving its wings unhampered. The wall surrounding the fly lights up in a shifting pattern of bars and boxes that tricks the fly into believing it is flying freely in an arena.



As the fly tries to turn, a camera detects the changes in wing motion and feeds that information to a computer, which quickly alters the lights on the wall. The fly "thinks" that it's really turning, to steer clear of an obstruction. The "Rock-and-Roll" part of the arena's name comes from the way the entire simulator can pitch and yaw, letting Dickinson and his students study how flies use their gyroscopes to steer.




The arena has helped Dickinson's team develop a set of rules that they think govern how flies maneuver. As a fly moves toward an object, the object grows larger in its eyes. If it grows bigger in one eye than another, the fly turns to avoid it; if it expands directly in front, the fly stretches out its legs to land. To test that theory, Dickinson and his students have built a machine called Flyball (think eyeball).




Flyball consists of a video camera mounted on a system of tracks. It travels around an arena decorated with a random collection of white and black squares, sending what it sees to a computer. The computer uses Dickinson's rules to choose where to go next. Dickinson hopes that it will make decisions to turn the way flies do. "It's fine to make a diagram, but to actually build something you really have to put your money where your mouth is." If he's right, the camera will take the same flight path as a real fly. If not, it may crash into a wall.