With this arrangement the direction and speed of the robot can be controlled. Suppose, the sensor in robot detects a dark line, it can slowdown the speed and change its direction or stop. If it goes in the right track in the road, it will be steering in the same direction.
In this way we can control the robot to make a correct ride on the road. The control circuit can be designed with IC 555 timer, Transistor or FET switches, Operation amplifiers and Light reflecting sensors. If you do this simple design, this enthusiasm will lead to a more sophisticated design of a robot of real time. Try it and give your valuable comments
Source : from a Net friend