The robot project works with two motors for driving the rear wheels while the front wheels are free.

It uses 4 infra red sensors for detecting the line that it has to follow. It can be either a black line on white background or a white line on black background.

AT89C2051 microcontroller is used in the project  for instructing the robot to move according to the sensors input. The motor driving circuit is made with L293D, which is an H-bridge IC. It can control the two motors simultaneously.

The code is written in C and is a fully functional code.

Care must be taken while choosing the motors. It should be a high torque motor so that it can take the weight of your robot. Otherwise the wheels would work fine while in the air but would not move once the robot is set down.

The sensor circuits as well as the control circuit is given below and the C code can be downloaded as a word file.

Control circuit:- 

These sensor circuits need to be attatched at the points labeled as sensors in the main figure.