First, a fruit fly is tethered to a rod with a cylindrical LED display around it. The display shows geometric patterns that are known to make a fruit fly move left or right - a kind of virtual reality simulator for flies. Since the fly is tethered, it can't actually move, but it tries to anyway. "The fly's pretty dumb," says roboticist Brad Nelson, who created the "flyborg" with colleagues at the Swiss Federal Institute of Technology Zurich.
The patterns on the display are triggered by images transmitted from a camera mounted on a miniature robotic car. If the car approaches an obstacle, the display shows the appropriate pattern and the fly reacts accordingly. As it does so, another camera detects minute changes in the movements of its wings. "We measure the lift force and kinematics in real time," says Nelson.
The goal is to figure out how the fly makes decisions about movement so that those decisions can be replicated by a computer.