How to Make a Line Follower Robot Using Arduino – Connection & Code

As the name suggests, the line follower robot is an automated vehicle that follows a visual line embedded on the surface. This visual line is a path on which the line follower robot runs. Generally, it uses a black line on a white surface, or you can adjust it as a white line on a black surface.

Usually, beginners and students would get their first robotic experience with this type of robot. In this project-based article, we have informed about how to make a line follower robot using Arduino.

In industries, giant line follower robots are used for assisting the automated production process. They are also used in military applications, human assistance purposes, delivery services, etc.

Working of Line Follower Robot

The concept of the line follower robot is related to light. Here, we use the behaviour of light on the black and white surface. The white colour reflects all the light that falls on it, whereas the black colour absorbs the light.

In this line follower robot, we use IR transmitters and receivers (photodiodes). They are used to send and receive the lights. When IR rays fall on a white surface, it is reflected towards IR receiver, generating some voltage changes.

When IR rays fall on a black surface, it is absorbed by the black surface, and no rays are reflected; thus, the IR receiver doesn’t receive any rays.

In this project, when the IR sensor senses a white surface, an Arduino gets 1 ( HIGH ) as input, and when it senses a black line, an Arduino gets 0 ( LOW ) as input. Based on these inputs, an Arduino Uno provides the proper output to control the bot.

Components Used

• Arduino Uno
• IR sensor
• L293D motor driver
• BO motor
• Wheels
• Lithium-ion battery
• Jumper cables

Also, it requires the robot chassis to mount all the above components on it. Robot chassis is an optional component; you can make the robot chassis using cardboard also.

Arduino Uno

Arduino Uno is an 8-bit ATmega328P microcontroller. To support the microcontroller, it uses the components such as crystal oscillator, serial communication, voltage regulator, etc. It has 14 digital I/O pins( 6 pins can be used as PWM pins). It has six separate analog input pins, a USB connection, a Power barrel jack, an ICSP header, and a reset button.

This board is programmable with the Arduino IDE (Integrated Development Environment) platform via a type B USB cable. This board can be powered by a USB cable or an external voltage between 7 to 20 volts. To know more about an Arduino Uno, refer to the article, what is Arduino Uno?

Infrared Sensor

An infrared sensor emits the light to detect some surroundings. In the infrared spectrum, all the objects radiate some form of thermal radiation that is invisible to our eyes, but an IR sensor can detect these radiations.

Here, IR LED is an emitter, and the IR photodiode is a detector. An IR LED emits the IR light, and the photodiode is sensitive to this IR light. When IR light falls on the photodiode, the output voltages and the resistances will change in proportion to the magnitude of the received IR light.

The Infrared detection system uses the five essential elements: an infrared source, a transmission medium, optical component, infrared detectors, and signal processing. An infrared transmission can be done through the vacuum, atmosphere, and optical fibres. To know more about the IR sensor, refer to the article, working principle of IR sensor.

L298N Motor Driver

L298N is one of the easiest and chipset way to control DC motors. It is the two-channel motor driver that can control the speed and spinning direction of DC motors.

This L298N Motor Driver is a high-power motor driver module. It is used for driving DC and Stepper Motors. This motor driver consists of an L298N motor driver IC and a 78M05 5V voltage regulator, resistors, capacitor, power LED, 5V jumper in an integrated circuit.

When the jumper is placed, it enables the 78M05 Voltage regulator. When the power supply is less than or equal to 12V, the voltage regulator will power on the internal circuitry. When the power supply is more than 12v, then the jumper should not place and should give a separate 5v to power the internal circuitry.

Here, ENA & ENB pins are speed control pins for Motor A, and Motor B. IN1& IN2 and IN3 & IN4 are direction control pins for Motor A and Motor B.

BO Motors

BO Motor is known as Battery Operated motor. These motors are commonly used in hobby-grade projects where the user requires a small DC motor as a simple actuator.

BO series linear motor provides good torque and rpm at lower operating voltages. The BO motors are available in single Shaft, Dual Shaft, and DC Plastic Gear BO. These motors consume low current. In this project, we have used four single shaft BO motors.

Lithium-ion Battery

A lithium-ion battery is a rechargeable battery. It is commonly used in portable devices such as mobiles, laptops, electronics, and electric vehicles. Also, they are growing in popularity for military and aerospace applications.

Lithium-ion battery provides 3.7V at storage mode and 4.2V at full charge mode. In this project, we have connected two lithium-ion batteries in series so that the total battery voltage will be 8.4V at full charge. To know more about the lithium-ion battery, refer to the article, working of lithium-ion battery.

Connection Diagram

Here, we have used four BO motors. Motors 1 & 2 are connected to the first channel of L298N, whereas motors 3 & 4 are connected to the second channel of the motor driver.

IN1, IN2, IN3, and IN4 pins are connected to pin 9, 6, 5, 3 of Arduino Uno. Here, we have used the jumper between +5V and enables pins (EN1 &EN2). You can remove it and make the external connection, as shown in the below image.

Software & Programming Code

Download the Arduino IDE Software from the below link and upload the code into your board.

• Arduino IDE 1.8.13

int mot1=9;
int mot2=6;
int mot3=5;
int mot4=3;

int left=13;
int right=12;

int Left=0;
int Right=0;

void LEFT (void);
void RIGHT (void);
void STOP (void);

void setup()
{
  pinMode(mot1,OUTPUT);
  pinMode(mot2,OUTPUT);
  pinMode(mot3,OUTPUT);
  pinMode(mot4,OUTPUT);

  pinMode(left,INPUT);
  pinMode(right,INPUT);

  digitalWrite(left,HIGH);
  digitalWrite(right,HIGH);
  
  
}

void loop() 
{
 
analogWrite(mot1,255);
analogWrite(mot2,0);
analogWrite(mot3,255);
analogWrite(mot4,0);

while(1)
{
  Left=digitalRead(left);
  Right=digitalRead(right);
  
  if((Left==0 && Right==1)==1)
  LEFT();
  else if((Right==0 && Left==1)==1)
  RIGHT();
}
}

void LEFT (void)
{
   analogWrite(mot3,0);
   analogWrite(mot4,30);
   
   
   while(Left==0)
   {
    Left=digitalRead(left);
    Right=digitalRead(right);
    if(Right==0)
    {
      int lprev=Left;
      int rprev=Right;
      STOP();
      while(((lprev==Left)&&(rprev==Right))==1)
      {
         Left=digitalRead(left);
         Right=digitalRead(right);
      }
    }
    analogWrite(mot1,255);
    analogWrite(mot2,0); 
   }
   analogWrite(mot3,255);
   analogWrite(mot4,0);
}

void RIGHT (void)
{
   analogWrite(mot1,0);
   analogWrite(mot2,30);

   while(Right==0)
   {
    Left=digitalRead(left);
    Right=digitalRead(right);
    if(Left==0)
    {
      int lprev=Left;
      int rprev=Right;
     STOP();
      while(((lprev==Left)&&(rprev==Right))==1)
      {
         Left=digitalRead(left);
         Right=digitalRead(right);
      }
    }
    analogWrite(mot3,255);
    analogWrite(mot4,0);
    }
   analogWrite(mot1,255);
   analogWrite(mot2,0);
}
void STOP (void)
{
analogWrite(mot1,0);
analogWrite(mot2,0);
analogWrite(mot3,0);
analogWrite(mot4,0);
  
}

Final Output

After uploading the code, if your bot is not running in the right direction, then change the wiring of BO motors. Also, calibrate both IR sensors by varying their potentiometer.

Below GIF shows the working of the line follower robot. Here, we have drawn the path on a white-coloured surface with black colour tape.

Final words

I hope this article helps you to understand how to make a line follower robot. The hobbyist people can make this for fun projects as well as science projects.