Project report on:

Line Follower Robot

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Prepared By:

Joshi Chintan A. (08BEC157)

Gareta Pravin (08BEC156)

For:

Micro Controller Lab

[2EC314]

Guided by:

Prof. Dhaval Shah

Institute Of Technology

Sarkhej-Gandhinagar Highway,

Ahmedabad-382481

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» A line follower is an autonomous line follower that can follow a specific coloured line painted on a surface of different contrast, such as white on black.

» To start with first of all I will be discussing a small concept of light. I believe you all know that the light that strikes any platform is reflected.

» The reflection and absorption coefficient of light depend upon material, color of platform and other factors. In simple words the black surface absorbs the light and the white surface reflects it, this is the basic concept behind making a line follower.

» So the line follower has an emitter and a reflector. The reflector receives the light and generates a voltage proportional to the intensity of the light, if this voltage is above a threshold it means SIGNAL=1 (logic one) else SIGNAL= 0 (logic zero).

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Line Follower Robot

» Let’s take up an example where we have to move our line follower on black surface having white line. Suppose I have two Infra Red (IR) sensor pairs that are on different halves of a line follower with respect to geometrical central axis of the line follower.

» The sensors are placed in such a way that the white line lies in between both the sensors when the line follower is placed on the white track painted on black surface to move.

» Now if the white line is between both the sensors while moving forward both the sensors will be on black surface and the detectors/receivers will receive less amount of light since black absorbs light and hence signal provided by both the infra-red receivers will be low.

» Now if the heading/direction of the white line changes one of the sensors will move in the region of white line and will start giving output signal as high.

» This information can be used to ‘turn’ the line follower and orient itself in the right direction.

» For example in the above figure if the line follower is located in position 1, then line follower will move forward and if the line follower is in position 2 it will have to turn left .

Components

Power Supply :5V/12V DC

Micro controller :Atmel AT89S52

Inverter IC

Proximity metal sensor.

DC motors(12V DC)

DC motor driver (L293D)

IR transmitter and IR receiver.

Switch

Line follower is made-up of following components:

1.) Chassis of robot

2.) Electronics/Hardware Designing

3.) Programming/Software Designing

CHASSIS OF ROBOT

1.) Base of robot: The base or the material of the platform of robot can be made with any easily available material like switch board, wood, acrylic sheet or steel sheet. As our robot will be very light, you don’t have to think a lot on strength and other such factors. We will just recommend you to make a small size and light weight line follower. Here we are using, steel base:

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2.) Motors and Driving Mechanism:

» We will need a set of two motors that have same rpm (revolution per minute).» We will be using differential drive for maneuvering our line follower i.e. we will have

three wheels for our line follower, the front two will be powered and the rear will be free wheel.

» When the line follower is moving straight both the motors should have equal speed. » For turning, one of the motor is switched off. If we switch off the left motor, the line

follower will turn left and vice versa.

3.) Coupling wheels & clamping motors: -» For clamping the motors you can use pipe clamps or make right angled clamps. The right

angle clamps ensure more rigidness. » To couple the motor ensure that the shaft of motor and hole of wheel have equal diameter

(if you can’t find one check the tutorial on wheels).

Op-Amplifier (LM324):

If the rays received by the IR- LED receiver are above a particular threshold then an amplified signal is generated by the amplifier (LM324). Note that the sensors cannot directly send a signal to the microcontroller as the signal voltage generated by them is too low and even when sensors are on white surface signal generated by them will interpreted low by the microcontroller.

Microcontroller (AT89S52)

The microcontroller receives the signal and responds accordingly. It takes the decision based on input signal received by both the receiver LEDs. It will give command to motors through H-bridge to move forward, or take a left turn or a right turn.

H-bridge (L293B)

The microcontroller sends a signal to the H-bride that acts as a switch. If the signal received by the H-bridge is high it will rotate the motor or else it won’t do so. Note that microcontroller only sends a signal to a switch which gives the voltage required by the motor to rotate. Here we are using L293B which can be used to control two motors.

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Circuit Diagram :

Program:

#include<reg51.h>

sbit ip1=P1^0;sbit ip2=P1^1;sbit op1=P2^0;sbit op2=P2^1;

void main(void){ while(1) { if(ip1) {

op1=1;

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if(ip2) {

op2=1;}

else {

op2=0;}

}

else { op1=0;

if(ip2) {

op2=1;}

else {

op2=0;}

} }}

Conclusion:

From this project we have studied how to interface micro controller with other devices. We also acknowledged about how to dump program in the controller. Our soldering skill is also improved. We learn many things from this project.

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