This video demonstrates an optical line-tracking robot I made for school. The robot also features a remote control (RC) mode using the receiver/transmitter set from a miniature indoor RC helicopter. Everything is controlled with a PIC24F microcontroller development board mounted on top of the platform.
The autonomous line-tracking mode uses a set of infrared emitter and detector pairs. When any of the infrared emitters is over the line, much less infrared light is detected by the paired detector. The pairs are arranged as follows:
This simple configuration along with a simple control loop allows the robot to follow the line at a fairly brisk pace.