LINE FOLLOWING ROBOT - I

INTRODUCTION

Line following Robot is a simple autonomous system which designed to track a line drawn in the ground and follow it with minimum deviation. As in my experiences, designing a line following robot is the first task which I did with starting in robotics. Later on I thought to share what I did and what I got from design and implementation of line following robot. So here I am, 'my experiences on Line Following Robot' .

The basic line following robot is designed in order to follow a line with a contrasting background (i.e.  a black line on a white surface or white line on a black surface).Even though there are many techniques to do this here we use the Arduino technology to do this. ( ARDUINO MEGA 2560  And the motor control is based on L298 IC ).

The main principle is, receiving the IR sensors through the sensor panel and pass it to the controller. Then from the controller an output will given to the motor control system. So that the motor will operate according to the received signal.

Figure 1- The block diagram for the main principle of Line Follower

      

This line follower consist of few main components namely the sensor panel, motor circuit, Arduino controller and the basic structure. Here in my first post I will explain about the sensor panel of the line follower.

SENSOR PANEL

Sensors are the first requirement in the  process of line following.The LFR detects the black and white colors as its first task. That is done by the sensor panel. The sensor panel has few couples of IR emitters and receivers. For the basic operations two such pairs are sufficient. The below diagram shows one IR sensor couple.

Figure 2 - IR Sensor

THEORY OF IR SENSORS

Assume the whole sensor block above, is on a white surface. According to the properties of light, when light falls on a white surface a larger portion gets reflected back. When a voltage of 5V , is given to the circuit , the IR LED glows and emits IR rays.  These IR rays hit on the white surface and get reflected back . When these reflected IR rays hit on the reversed biased photo diode , reversed biased breakdown of the diode occurs and all the current flows through 1MΩ  resister will be shorted to the ground. Simply the LED acts as a conductor when it receives IR. Therefore when output is taken as shown, the output  would be 0V.

Consider the same operation for a black surface. According to the properties of light , black color absorbs IR and reflect back a very less amount. Then there is no reflected IR to cause reverse bias breakdown . Therefore when the output is taken between 1MΩ resister and diode again, the total output 5V will be shown across the diode.

 The  0V represents  the logic of zero (0),  while 5V represents the logic of one (1).

ere in this robot, there are 7 IR sensor couples in the sensor array. They are connected as below.

                       

Figure 3 – Location of IR sensors in the sensor array

Figure 4 – The final sensor array

 Hope you got a brief  idea on how the sensor panel of a line following robot works. From my next post I would like to write about the motor control system of the line following robot.

 Thank you very much for reading.