Line follower

What is a line follower?

A line follower is an autonomous vehicle which follows a line path(straight or curved) that maybe of any colour.

what this statement means is that the line follower will move on its own by following the line.

I have always been fascinated by autonomous vehicles like micromouse, line follower the best thing about them is that they move without any external control.

So a line follower has the following requirements:

1. It requires a Sensory Device which would help detect the line.

2. It requires a Brain to control its motion helping to follow the line.

3. It requires Locomotion which would help it ro move along the line.

4. It requires a Mechanical Structure which would support all these devices.


The most important part of the line follower is its sensory part which detects the line.
It senses the line and produces an output in the form of potential drop.
For example, an LDR(Light Dependant Resistor) has different resistances for different intensities of light,low resistance for higher intensity and vice versa.

An IR sensor is also a good option as a sensory device it also produces a potential drop across it.

for more info on IR sensor:Link to IR Sensors

or u can also use an LED

For details for how to use LED as a sensor visit this site.

Though it is important to note that more the number of sensors employed the better the line follower becomes.But programming becomes more and more complex with increasing number of sensors

U can also use a web camera to detect the line and follow it using image processing for interpretation.
But it would increase the cost of the line follower by two folds.


Now the signal produced by the sensors of the line follower is to be interpreted by a logic circuit.
This logic circuit can be purely electronic(if u are good at hardware) or using Microcontrollers like AVR or 8051 which u can program using C. Through a suitable program u can control the motion of the line follower. Suppose if u get a signal logic 1 as an input and if you're following a black line then u would move right or left accordingly.

for example if u have two sensors on both sides of the line and if detect logic 1 one and logic 0 on the other sensor(then u have moved on the left of the line) so to counter u will have to move to the right side.

This way u will follow the line.


Now for locomotion of the line follower we require motors.We require lightweight motors which can have low torque and medium(now for controlling high rpm motors we require an H-bridge see article
for fast change of change of direction)
The motors should be d.c. motors(it is preferable not use stepper motors instead use differential mechanism for the line follower).

Mechanical Structure:

We should use a lightweight chassis as the torque of the motors is low and so they cannot support large amount of weight. The chassis can be made of lightweight plastic or wood.
And we also need a large amounts of nuts,bolts and screws to fix the motors and the electronic parts of the line follower.

Watch this great video:

It is the video of a very fast Line follower and completes three laps in very less time.
It inspires a lot.
The name of the line follower is Jet.


Jeez said...

hey, your blog was nice! but can you give me a detailed tute on how to assemble the parts? am new to robotics!
thank you

PS: Please mail to me at !

Eileen said...

Great work.

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