Build a Line Following Robot

Build a Line Following Robot

A line following robot is an autonomous mobile robot designed to detect and follow a visible path, usually a black line on a white surface. This project introduces the fundamentals of robotics, sensor-based decision making, and motor control using a microcontroller.

Required Components

• Arduino Uno

• IR Line Sensor Module (2 sensors or array)

• L298N Motor Driver Module

• DC Motors with Wheels

• Robot Chassis

• Battery Pack

• Jumper Wires

• Breadboard (optional)

How It Works

The robot uses infrared (IR) sensors to detect the contrast between the line and the surface. Each sensor outputs a digital signal depending on whether it detects the line.

• When both sensors detect the line, the robot moves forward

• When the left sensor detects the line, the robot turns left

• When the right sensor detects the line, the robot turns right

• When no sensor detects the line, the robot stops or searches for the line

The Arduino processes sensor data and sends control signals to the motor driver, which drives the motors accordingly.

Circuit Connection

IR Sensors

• Left IR Sensor OUT → Arduino Digital Pin 2

• Right IR Sensor OUT → Arduino Digital Pin 3

• VCC → 5V

• GND → GND

Motor Driver (L298N)

• IN1 → Arduino Pin 8

• IN2 → Arduino Pin 9

• IN3 → Arduino Pin 10

• IN4 → Arduino Pin 11

• ENA & ENB → Jumper Enabled or PWM Pins

• Motor terminals → DC Motors

• Power input → External Battery

Application Areas

• Robotics Learning & Competitions

• Industrial Automation Concepts

• Autonomous Vehicle Basics

• Academic and Training Projects

This project can be extended using PID control, speed sensors, obstacle detection, or wireless monitoring.

Code Example

#define LEFT_SENSOR 2
#define RIGHT_SENSOR 3

#define IN1 8
#define IN2 9
#define IN3 10
#define IN4 11

void setup() {
  pinMode(LEFT_SENSOR, INPUT);
  pinMode(RIGHT_SENSOR, INPUT);

  pinMode(IN1, OUTPUT);
  pinMode(IN2, OUTPUT);
  pinMode(IN3, OUTPUT);
  pinMode(IN4, OUTPUT);
}

void loop() {
  int leftValue = digitalRead(LEFT_SENSOR);
  int rightValue = digitalRead(RIGHT_SENSOR);

  if (leftValue == LOW && rightValue == LOW) {
    moveForward();
  }
  else if (leftValue == LOW && rightValue == HIGH) {
    turnLeft();
  }
  else if (leftValue == HIGH && rightValue == LOW) {
    turnRight();
  }
  else {
    stopRobot();
  }
}

void moveForward() {
  digitalWrite(IN1, HIGH);
  digitalWrite(IN2, LOW);
  digitalWrite(IN3, HIGH);
  digitalWrite(IN4, LOW);
}

void turnLeft() {
  digitalWrite(IN1, LOW);
  digitalWrite(IN2, LOW);
  digitalWrite(IN3, HIGH);
  digitalWrite(IN4, LOW);
}

void turnRight() {
  digitalWrite(IN1, HIGH);
  digitalWrite(IN2, LOW);
  digitalWrite(IN3, LOW);
  digitalWrite(IN4, LOW);
}

void stopRobot() {
  digitalWrite(IN1, LOW);
  digitalWrite(IN2, LOW);
  digitalWrite(IN3, LOW);
  digitalWrite(IN4, LOW);
}