A line follower robot, or a LFR in short, is a simple autonomous robot that optically tracks a line made on the surface of the floor. That means you have an arbitrary line drawn on the floor and the robot tracks it by moving right along it! The line is sensed using a piece of hardware called a line sensor.

A line sensor can be easily made using a low cost IR Rx/Tx pair. The IR Rx emmits IR radiation and the Rx helps in receiving the waves. See the figure below for working of line sensor.

Line Sensor Working

Working of Line Sensor

Schematic for Line Sensor.

Line Sensor Schematic

Line Sensor Schematic


IR Rx Tx Pair

Actual IR Rx Tx Pair.

Line Sensor Array.

Actually a group of such sensor units as described above is required to make a line follower robot. We generally use 3 or 5 such sensor unit to make a line sensor array. The complete steps are described below. You need small piece of veroboard (general purpose PCB).

Actual IR Rx Tx Pair.

We will fit the sensor at the castor mount of the metal chassis. So we carefully mark the location we need drilling.

Mark a hole's location

Mark drilling location.


holes marked

Mark the drilling location.

You can make the hole easily by using a pair of scissor. Just press and rotate.

make the hole

Make hole using scissor.


hole done



check it it fits

Check if it fits.


line sensor complete

Line Sensor Array Complete.


line sensor mounted

Mounted on Chassis.


line sensor mounted

Mounted on Chassis.

Professional Line Sensor Array

line sensor mounted

Line Sensor Array.

Purchase Line Sensor Array




By Avinash Gupta

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Avinash Gupta is solely focused on free and high quality tutorial to make learning embedded system fun !

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