Line Follower Robot

Line Follower Robot Using Arduino

If you're getting started with robotics one among the primary project that beginners make includes a line follower. it's a special toy car with property to line a line which normally is black in color and in contrast with background. Let's start .

We can divide line follower in four major blocks IR photo diode sensor, motor driver, Arduino nano/code and toy car chassis which is formed from acrylic sheet, plastic wheels and 6V DC motors.   

 

Components Used:

• IR Photodiode Sensor
• Arduino
• LM741 op-amp
• Resistor
• L293D Motor Driver
• Motors
• Connecting Wires
• Chassis Of Toy Car

Let's check out these blocks one by one. Job of IR-photodiode sensor in line follower is to detect if it's a black line underneath it IR light emitted from IR LED bounces back from surface underneath to be captured by photodiode. Current through photo diode is proportional to photons it receives and physics says that black color absorbs IR radiation. Hence if we've black line under a photodiode it receives less photons leading to lesser current, compared to if it had reflective color like white underneath it. we'll use this circuit to convert photodiode's current signal into digital voltage signal the arduino can read using digital Read command. On breadboard is poor replica of this circuit. Photodiode's current is skilled a ten KOhm resistor to make proportional drop , let's call it Vphoto. If there's white surface underneath, photodiode's current goes up and hence Vphoto. On the opposite hand for block surface both decreases. Vphoto is connected to Non-inverting terminal of LM741 opamp. during this configuration, if voltage at Non-Inverting terminal is bigger than voltage at Inverting terminal. Opamp's output is about to high and low for other way round. We carefully set voltage at Inverting pinto be in-between voltage reading for white and black colors employing a potentiometer. On doing so this circuit's output is high for white and low for black color. Which is ideal for arduino to read up. just one IR-photodiode sensor isn't enough for creating a line follower because if we had just one IR-photodiode sensor we cannot know the direction of exit of follower to catch up on using motors. Hence, I bought this sensor module containing 6 IR-photodiode sensors, 3 clusters during a set of two .

Principle Of working:

If center cluster reads black and other two read white we will keep going forward. If left cluster reads black we'd like to show follower towards left to stay it on target and same applies for right cluster. to maneuver follower i'm using 2 6V DC motors,which are controlled using L293D motor driver. If motor is connected as shown on left. Setting enable and 1A pin to HIGH along side 2A pin to LOW, moves motor in one direction. to maneuver it in other direction we'd like to exchange the state of 2A and 1A pins. we do not need bidirectional movement as follower always move forward. to show left we disable left motor while motor on right is kept running and vice-versa. 5V arduino nano running at 16 MHz decides whether follower must turn left or right. Decisions are made by watching IR photodiode sensor array readings. Let's check out arduino code which is pretty simple . Initially we declare 6 sensor and 4 motor pins. In setup we set motor pins to output as default mode is input. In Loop, first we read all sensor pins, following that's a sequence of If-else statements that decide the movement of follower. Some statements let follower to maneuver forward. Some stops it and a few allows it to travel either left or right. Finally everything was put together consistent with this schematic provided above.

Code:

//sensor pins const int IR0 = 2;

const int IR1 = 3;

const int IR2 = 4;

const int IR3 = 5;

const int IR4 = 6;

const int IR5 = 7;

//Motor control pins-

//left motor- MOT0 & MOT1

//right motor- MOT2 & MOT3

const int MOT0 = 9;

const int MOT1 = 8;

const int MOT2 = 10;

const int MOT3 = 11;

void setup() {

pinMode(MOT0,OUTPUT);

pinMode(MOT1,OUTPUT);

pinMode(MOT2,OUTPUT);

pinMode(MOT3,OUTPUT);

// initialize the serial communications:

//Serial.begin(115200);

}

void loop() {

int S0 = digitalRead(IR0);

int S1 = digitalRead(IR1);

int S2 = digitalRead(IR2);

int S3 = digitalRead(IR3);

int S4 = digitalRead(IR4);

int S5 = digitalRead(IR5);

// print the sensor values:

//Conditions to drive line folower appropriately

if (S0==0 && S1==0 && S2==0 && S3==0 && S4==0 && S5==0) {

//stop

digitalWrite(MOT0,LOW);

digitalWrite(MOT1,LOW);

digitalWrite(MOT2,LOW);

digitalWrite(MOT3,LOW);

} else if (S0==1 && S1==1 && S2==1 && S3==1 && S4==1 && S5==1) {

//stop

digitalWrite(MOT0,LOW);

digitalWrite(MOT1,LOW);

digitalWrite(MOT2,LOW);

digitalWrite(MOT3,LOW);

} else if (S2==0 && S3==0) {

//if two sensors at the middle reads 0, go straight

digitalWrite(MOT0,HIGH);

digitalWrite(MOT1,LOW);

digitalWrite(MOT2,LOW);

digitalWrite(MOT3,HIGH);

} else if (S1==0 && S2==0) {

//follower moving towads right, stop left motor

//digitalWrite(MOT0,LOW);

analogWrite(MOT0, 125);

digitalWrite(MOT1,LOW);

digitalWrite(MOT2,LOW);

digitalWrite(MOT3,HIGH);

} else if (S0==0 && S1==0) {

//follower moving towads right, stop left motor

digitalWrite(MOT0,LOW);

digitalWrite(MOT1,LOW);

digitalWrite(MOT2,LOW);

digitalWrite(MOT3,HIGH);

} else if (S3==0 && S4==0) {

//follower moving towads left, stop right motor

digitalWrite(MOT0,HIGH);

digitalWrite(MOT1,LOW);

digitalWrite(MOT2,LOW);

//digitalWrite(MOT3,LOW);

analogWrite(MOT3, 125);

} else if (S4==0 && S5==0) {

//follower moving towads left, stop right motor

digitalWrite(MOT0,HIGH);

digitalWrite(MOT1,LOW);

digitalWrite(MOT2,LOW);

digitalWrite(MOT3,LOW);

} else if ( S4==1 && S5==0) {

//follower moving towads left, stop right motor

digitalWrite(MOT0,HIGH);

digitalWrite(MOT1,LOW);

digitalWrite(MOT2,LOW);

digitalWrite(MOT3,LOW);

} else if (S0==0 && S1==1) {

//follower moving towads right, stop left motor

digitalWrite(MOT0,LOW);

digitalWrite(MOT1,LOW);

digitalWrite(MOT2,LOW);

digitalWrite(MOT3,HIGH);

} else {

//stop follower

digitalWrite(MOT0,LOW);

digitalWrite(MOT1,LOW);

digitalWrite(MOT2,LOW);

digitalWrite(MOT3,LOW);

}

}   // end of the code

 So there we've it guys, a line following toy car. If you wish this Blog. Please do not forget to share with your friends.I will be able to see you soon with another Blog, till then MAKE A LINE FOLLOWER.

Hope You Enjoyed Working On this Project!!!