Block Diagram

The robot uses IR sensors to sense the line, an array of 8 IR LEDs< (Tx) and sensors (Rx), facing the ground has been used in this setup. The output of the sensors is an analog signal which depends on the amount of light reflected back, this analog signal is given to the comparator to produce 0s and 1s which are then fed to the µC.

Left ———— Center ————- Right

Sensor Array

Starting from the center, the sensors on the left are named L1, L2, L3, L4 and those on the right are named R1, R2, R3, R4.
Let us assume that when a sensor is on the line it reads 0 and when it is off the line it reads 1

The µC decides the next move so as to position the robot such that L1 and R1 both read 0 and the rest read 1.

Left ————– Center ————— Right

Desired State L1=R1=0, and Rest=1

Algorithm:

Line Follower ROBOT

Plermjai Inchuay, plermjai@loxinfo.co.th

Award winner from VingPeaw Competition 2543, the robot built with 2051, L293D, and four IR sensors. Simple circuit and platform, quick tracking and easy-understand program using C language.

I designed my robot, which use two motors control rear wheels and the single front wheel is free. It has 4-infrared sensors on the bottom for detect black tracking tape, when the sensors detected black color, output of comparator, LM324 is low logic and the other the output is high. Microcontroller AT89C2051 and H-Bridge driver L293D were used to control direction and speed of motor.