Garnet Hertz: Control and Communication in the Animal and the Machine
: "How does the cockroach move the robot?
The cockroach is placed on top of a modified trackball - a computer-mouse-type device - that is hooked up to some electronics. The cockroach is held gently in place above the ball so that when the cockroach moves it makes the ball spin: a little bit like a two-dimensional treadmill. The electronics (optical encoders) within the trackball send out small electrical pulses to some electronics that make the motors move in a similar direction to where the cockroach is moving on the ball.
What do the lights do?
The lights encircle the front of the insect, and are designed to help the cockroach navigate the object away from obstacles. In theory, cockroaches don't like light: as you may know, cockroaches scuttle quickly underneath the refrigerator if the light is turned on when you catch them in your kitchen at night. The lights around the front of the cockroach control center are each hooked up to a distance sensor. As the robot approaches a wall, for example, the distance sensor will detect that something is close, and will send electricity to the light. The light will turn on, and will alert the cockroach before it crashes into the wall. The idea is that the cockroach will want to scuttle into a 'dark' under-the-fridge-type region, and therefore steer the robot into a clear space."