IR sensor panel for line following robot

If you are a beginner for robotics this blog will help you to get some knowledge about robotics.Major part of a line following robot is sensor panel.You can make line following sensor panel using IR,LDR,photo transistors etc.

I will show you how to make a good sensor panel using IR sensors.

Specifications

• Operating voltage: 4-5.0 V
• Output format: digital I/O compatible
• Optimal sensing distance: 4 mm
• Maximum  sensing distance: 20 mm

You can buy IR sensors(which having both transmitter and the receiver).A single IR sensor will cost about $1.

Now you have to choose whether your robot must follow the line smooth or not.If you need to go smooth,then you have to put more sensors on the sensor array.greater the number of sensors will greater the line following.

I think if you have any theoretical knowledge about IR rays,it will help you to improve the performances of your robot.
go to this link http://en.wikipedia.org/wiki/Passive_infrared_sensor.

OK,If you are beginner and you know only a little about microcontrollers I will tell you some thing about microcontrolers.Robot will find the way according to the signals from the sensor panel.There are many algorithms(such as PID) we can use to drive the robot on the line if sensor panel works properly.

Microcontroller can understand only logic 1 & 0.microcontroller port voltage for logic high is 2.4V-5V(Voh) and for logic low is 0V-0.45V(Vol).White surfaces will reflect the IR light while black surfaces absorb.Using this theory we can tell the path to robot.Sensor panel produces about 4v to 5v when  IR sensor is on white surface and 0V when it is on dark surface.

Here I've used LM324 to amplify the signal from the IR sensor. Without op amp we cannot produce enough voltage to give logic high to pic,because the voltage different between when sensor is on white surface  and black surface is not more than 0.7V.Basically op amp is used to convert analogue signal to digital.

Above is a image of a part of the sensor panel.I created it using Proteus software.

By changing the RV1 value sensor panel can be tuned.When there is more sunlight,sensor panel tends to give wrong signals.To avoid that, it is better to cover the sensor panel.