Davide Gironi made a PID controlled line following robot:
InLinea01 is a simple PID controlled line following robot.
This is not speed oriented line follower, this is just a prototype I built to experiment with this type or machines, though it can be the first step to build a faster one.
The goal of a line following robot is follow a line that is draw on the floor, usually this line is a black on white floor line, or a white on black one.
A sensor is needed to detect the line, and mantain the robot over the line. This follower has two 200rpm @ 6v DC motors, driven by a L9110S H-bridge based controller board.
Check out the video after the break.