Line follower is an autonomous robot which can detect a specific colored line painted on a surface of different contrast, such as white on black. In this project I used infrared transmitters and receivers to track the black strip on white surface. Due to the difference of infrared reflection on black and white surfaces, it provides two voltages which can be amplified and used as logic states.
Flow chart above explains the working of the robot. There are eight IR transmitters and receivers to detect the path and junctions. Analog values from those receivers are amplified by LM324 operational amplifier. A microcontroller is used to detect the amplified digital values and to make decisions. It provides control signals to the H-Bridge motor driver (L293). More details are explained below.