Line Following CAR

Have you ever wondered how robots can follow a path without human control? A line-following robot is one of the best beginner projects in robotics and embedded systems. It uses infrared (IR) sensors to detect a black line on a white surface (or vice versa) and automatically adjusts its movement to stay on the path.

In this project, I built a simple line-following robot using an Arduino Uno, two IR sensors, an L298N motor driver, and two DC motors. This project is ideal for students learning Arduino, robotics, and automation.

Arduino Uno

L298N Motor Driver Module

2 × IR Line Tracking Sensors

2 × BO DC Motors

Robot Chassis

2 × Wheels

Caster Wheel

9V/12V Battery (or 2 × 18650 batteries)

Battery Holder

Jumper Wires

Switch

The robot uses two IR sensors:

1. Left IR Sensor
2. Right IR Sensor

The sensors continuously detect the surface beneath them.

Black Surface

The sensor outputs LOW (0).

White Surface

The sensor outputs HIGH (1).

The Arduino reads these values and controls the motors.

Left SensorRight SensorRobot Action

Black

Black

Move Forward

Black

White

Turn Left

White

Black

Turn Right

White

White

Stop/Search

IR Sensors

Left Sensor OUT → Arduino D2

Right Sensor OUT → Arduino D3

VCC → 5V

GND → GND

L298N Connections

IN1 → D8

IN2 → D9

IN3 → D10

IN4 → D11

ENA → PWM D5

ENB → PWM D6

Battery → L298N Power Input

Arduino GND → L298N GND

Fix both DC motors to the chassis.

Attach the wheels.

Mount the caster wheel.

Install the Arduino.

Fix the L298N module.

Place the IR sensors at the front.

Keep both sensors about 5–10 mm above the ground.

Connect all wires.

Upload the line-following program using the Arduino IDE.

code

// ===============================

// Line Following Robot

// Arduino UNO + L298N + 2 IR Sensors

// Black Line = LOW

// White Surface = HIGH

// ===============================

// -------- Motor Driver Pins --------

#define ENA 5

#define IN1 8

#define IN2 9

#define ENB 6

#define IN3 10

#define IN4 11

// -------- IR Sensor Pins --------

#define LEFT_SENSOR 2

#define RIGHT_SENSOR 3

// -------- Motor Speed --------

int speedA = 100;

int speedB = 100;

void setup()

{

pinMode(LEFT_SENSOR, INPUT);

pinMode(RIGHT_SENSOR, INPUT);

pinMode(ENA, OUTPUT);

pinMode(IN1, OUTPUT);

pinMode(IN2, OUTPUT);

pinMode(ENB, OUTPUT);

pinMode(IN3, OUTPUT);

pinMode(IN4, OUTPUT);

Serial.begin(9600);

}

void loop()

{

int left = digitalRead(LEFT_SENSOR);

int right = digitalRead(RIGHT_SENSOR);

Serial.print("Left: ");

Serial.print(left);

Serial.print(" Right: ");

Serial.println(right);

// ===============================

// Black Line = LOW

// White = HIGH

// ===============================

if (left == LOW && right == LOW)

{

forward();

}

else if (left == LOW && right == HIGH)

{

turnLeft();

}

else if (left == HIGH && right == LOW)

{

turnRight();

}

else

{

stopRobot();

}

}

// ===============================

// Move Forward

// ===============================

void forward()

{

analogWrite(ENA, speedA);

analogWrite(ENB, speedB);

digitalWrite(IN1, HIGH);

digitalWrite(IN2, LOW);

digitalWrite(IN3, HIGH);

digitalWrite(IN4, LOW);

}

// ===============================

// Turn Left

// ===============================

void turnLeft()

{

analogWrite(ENA, 70);

analogWrite(ENB, 110);

digitalWrite(IN1, LOW);

digitalWrite(IN2, LOW);

digitalWrite(IN3, HIGH);

digitalWrite(IN4, LOW);

}

// ===============================

// Turn Right

// ===============================

void turnRight()

{

analogWrite(ENA, 110);

analogWrite(ENB, 70);

digitalWrite(IN1, HIGH);

digitalWrite(IN2, LOW);

digitalWrite(IN3, LOW);

digitalWrite(IN4, LOW);

}

// ===============================

// Stop Robot

// ===============================

void stopRobot()

{

analogWrite(ENA, 0);

analogWrite(ENB, 0);

digitalWrite(IN1, LOW);

digitalWrite(IN2, LOW);

digitalWrite(IN3, LOW);

digitalWrite(IN4, LOW);

}

Make sure to:

1. Select the correct board.
2. Select the correct COM port.
3. Upload the code.

Create a track using black electrical tape on a white chart paper.

Power on the robot.

The robot should:

1. Move forward on the line
2. Turn left at left curves
3. Turn right at right curves
4. Continue following the path automatically

Robot moves in the wrong direction

Swap the motor wires.

Robot doesn't detect the line

Adjust the IR sensor height.

Use the onboard potentiometer to calibrate the sensor.

Robot keeps spinning

Check sensor wiring.

Verify that the left and right motors are connected correctly.

Robot stops frequently

Increase motor speed slightly in the code.

Recharge the battery.

Warehouse automation

Industrial material transport

Hospital delivery robots

Automated guided vehicles (AGVs)

Educational robotics

Robotics competitions

1. Add PID control for smoother movement.
2. Use more IR sensors for better accuracy.
3. Add Bluetooth control.
4. Integrate obstacle detection using an ultrasonic sensor.
5. Implement speed control based on turns.
6. Upgrade to ESP32 for IoT monitoring.