How to Build an Obstacle-Avoiding Car Using Arduino

In this project, we will build an obstacle-avoiding car using an Arduino Uno and an ultrasonic sensor (HC-SR04). The car will detect obstacles in its path and automatically steer away from them.

Supplies

To build this project, you will need:

Arduino Uno

L298N Motor Driver Module

Sensor Shield for Arduino (optional but helps in wiring)

HC-SR04 Ultrasonic Sensor

Jumper Wires

Additional Wires for power and motor connections

4x AA Battery Holder (for powering the motors)

Switch (to turn the car on/off)

2 BO Motors (DC gear motors)

2 BO Wheels

Wiring the Components

To ensure the car functions correctly, wire all components as shown in the circuit diagram. Follow these connections:

Ultrasonic Sensor (HC-SR04) to Arduino

HC-SR04 Pin Arduino Pin

VCC 5V

GND GND

TRIG D9

ECHO D10

L298N Motor Driver to Arduino and Motors

L298N Pin Connection

12V Battery Positive (AA Battery Pack)

GND Battery Negative & Arduino GND

5V Arduino 5V

IN1 D6

IN2 D7

IN3 D8

IN4 D9

OUT1

& OUT2 Left Motor

OUT3

& OUT4 Right Motor

Powering the System

The Arduino is powered via the sensor shield or through the L298N’s 5V output.

The motors are powered by the AA battery pack connected to the L298N module.

A switch is added between the battery pack and L298N to control power.

Once everything is wired correctly, double-check the connections to avoid short circuits.

Uploading the Code

Now, upload the following Arduino code to control the car's movement:

Download the Code or copy and paste the following code into the Arduino IDE and upload it:

#define trigPin 9

#define echoPin 10

// Motor driver input pins

#define IN1 7

#define IN2 8

#define IN3 11

#define IN4 12

void setup() {

pinMode(trigPin, OUTPUT);

pinMode(echoPin, INPUT);

pinMode(IN1, OUTPUT);

pinMode(IN2, OUTPUT);

pinMode(IN3, OUTPUT);

pinMode(IN4, OUTPUT);

Serial.begin(9600);

}

// Function to measure distance using the HC-SR04 ultrasonic sensor

long getDistance() {

digitalWrite(trigPin, LOW);

delayMicroseconds(2);

digitalWrite(trigPin, HIGH);

delayMicroseconds(10);

digitalWrite(trigPin, LOW);

long duration = pulseIn(echoPin, HIGH);

// Calculate distance in centimeters: (duration in microseconds * speed of sound (0.034 cm/us)) / 2

return duration * 0.034 / 2;

}

void moveForward() {

digitalWrite(IN1, HIGH);

digitalWrite(IN2, LOW);

digitalWrite(IN3, HIGH);

digitalWrite(IN4, LOW);

}

void moveBackward() {

digitalWrite(IN1, LOW);

digitalWrite(IN2, HIGH);

digitalWrite(IN3, LOW);

digitalWrite(IN4, HIGH);

}

void turnLeft() {

digitalWrite(IN1, LOW);

digitalWrite(IN2, HIGH);

digitalWrite(IN3, HIGH);

digitalWrite(IN4, LOW);

}

void turnRight() {

digitalWrite(IN1, HIGH);

digitalWrite(IN2, LOW);

digitalWrite(IN3, LOW);

digitalWrite(IN4, HIGH);

}

void stopCar() {

digitalWrite(IN1, LOW);

digitalWrite(IN2, LOW);

digitalWrite(IN3, LOW);

digitalWrite(IN4, LOW);

}

void loop() {

long distance = getDistance();

Serial.println(distance);

// If no obstacle is close (distance greater than 20cm), move forward

if (distance > 20) {

moveForward();

} else {

// Obstacle detected: stop, then reverse, stop, and turn left

stopCar();

delay(500);

moveBackward();

delay(500);

stopCar();

delay(500);

turnLeft();

delay(500);

}

After uploading, place your robot on the ground and turn it on. It should start moving forward and avoid obstacles automatically!

Downloads

obstacle_avoiding_robot_correct.ino

Watch the Demo Video

For a detailed demonstration of the obstacle-avoiding car in action, check out my YouTube video:

Watch on YouTube – HProjectJunction

https://youtu.be/GDjiNtp25cM?si=X4cjqJ9lnwCj0ns1

Conclusion

You have successfully built an Arduino-based obstacle-avoiding robot! This project is great for learning about sensor integration, motor control, and automation using Arduino.

If you have any questions or improvements, drop a comment below! Happy building!

Let me know if you want any changes or additional explanations!