My line follower (Programming)

Hello friends I hope you all have read my post about the sensors used in line follower..

So now it is the time to go for the logical side…..

Let us start with how actually a line is followed

According to the position of sensors we have to make a look-up table for all the possibilities….

Let us start…..

If i am using 3 sensors I can do…

LEFT SENSOR	CENTER SENSOR	RIGHT SENSOR	LEFT MOTOR	RIGHT MOTOR	comment
0	0	0	FORWARD	FORWARD	To avoid the cross…
0	0	1	STOP	FORWARD
0	1	0	FORWARD	FORWARD	Worst case!!!
0	1	1	STOP	FORWARD
1	0	0	FORWARD	STOP
1	0	1	FORWARD	FORWARD
1	1	0	FORWARD	STOP
1	1	1	REVERSE	REVERSE	Line is lost Return to line

*note that when sensor is on black surface we get 0

*and assume that we have to follow a black track in white surface…

After understanding the logic it is always easy to convert it to programming…

Here the programming I have given is for AVR 8535.

//motors are connected to PORTB

//sensors are connected to PORTA

//as the motor is too much fast we had to turn off motor for certain time..

//program of line follower with three sensors

//6/8/11

#include<avr/io.h>

#include<delay.h>

void main(void)

{

 DDRD=0xF0;     //Setting the data direction of Port-D where motors are connected

 PORTA=0XFF;

 DDRA=0X00;

 DDRC=0XFF;

 while(1)

 {

                                while((PINA & 0X07)==0X03)

                {

                                PORTD=0X20;

                                delayms(75);

                                PORTD=0x00;

                                delayms(200);

                }

                                while((PINA & 0x07)==0x00)

                {

                                PORTD=0XA0;

                                delayms(50);

                                PORTD=0x00;

                                delayms(200);  

                }

                                while((PINA & 0x07)==0x01)

                {

                                PORTD=0x20;

                                delayms(75);

                                PORTD=0x00;

                                delayms(200);

                }             

                                while((PINA & 0x07)==0x02)

                {

                                PORTD=0x50;

                                delayms(75);

                                PORTD=0x00;

                                delayms(200);

                }

                                while((PINA & 0x07)==0x04)

                {

                                PORTD=0x80;

                                delayms(75);

                                PORTD=0x00;

                                delayms(200);

                }

                                while((PINA & 0x07)==0x05)

                {

                                PORTD=0xA0;

                                delayms(75);

                                PORTD=0x00;

                                delayms(200);

                }

                                while((PINA & 0x07)==0x06)

                {

                                PORTD=0x80;

                                delayms(75);

                                PORTD=0x00;

                                delayms(200);

                }

                while((PINA & 0x07)==0x07)

                {

                                PORTD=0x50;

                                delayms(75);

                                PORTD=0x00;

                                delayms(200);

                }

                }

}

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Now let us see a video in action...

you can see all the logic being applied in video....

hope you loved it...

place any comment if you want to ask.....

We had a fun making it....

-keyur
:)