Obstacle Avoiding Robot

Obstacle Avoiding Robots are autonomous robots capable of detecting obstacles in their path and changing direction automatically to avoid collisions. This project uses an Arduino Uno, an HC-SR04 ultrasonic sensor, an L298N motor driver, and two DC motors to create a simple obstacle avoidance robot.

Arduino Uno

HC-SR04 Ultrasonic Sensor

L298N Motor Driver Module

2 DC Geared Motors

Robot Chassis

Caster Wheel

Battery Pack (7.4V–12V)

Jumper Wires

Software - Arduino IDE

The HC-SR04 ultrasonic sensor emits ultrasonic waves and measures the time taken for the echo to return.

Distance is calculated using:

Distance = (Speed of Sound × Time)/2

When the measured distance becomes smaller than the threshold value (for example, 20 cm):

1. Robot stops.
2. Robot moves backward briefly.
3. Robot turns left or right.
4. Robot continues moving forward.

This process repeats continuously.

HC-SR04 to Arduino

VCC - 5V

GND - GND

TRIG - D9

ECHO - D10

L298N to Arduino

IN1 - D2

IN2 - D3

IN3 - D4

IN4 - D5

Motors

1. Left Motor → OUT1 and OUT2
2. Right Motor → OUT3 and OUT4

Power

1. Battery → L298N Power Input
2. Arduino powered through battery

1. Fix the motors to the chassis.
2. Mount the caster wheel at the front or rear.
3. Secure the Arduino Uno on the chassis.
4. Fix the L298N motor driver.
5. Mount the ultrasonic sensor facing forward.
6. Connect all wiring according to the circuit diagram.
7. Connect the battery pack.

#define trigPin 9

#define echoPin 10

#define IN1 2

#define IN2 3

#define IN3 4

#define IN4 5

void setup() {

pinMode(trigPin, OUTPUT);

pinMode(echoPin, INPUT);

pinMode(IN1, OUTPUT);

pinMode(IN2, OUTPUT);

pinMode(IN3, OUTPUT);

pinMode(IN4, OUTPUT);

Serial.begin(9600);

}

long getDistance() {

digitalWrite(trigPin, LOW);

delayMicroseconds(2);

digitalWrite(trigPin, HIGH);

delayMicroseconds(10);

digitalWrite(trigPin, LOW);

long duration = pulseIn(echoPin, HIGH);

long distance = duration * 0.034 / 2;

return distance;

}

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 turnRight() {

digitalWrite(IN1, HIGH);

digitalWrite(IN2, LOW);

digitalWrite(IN3, LOW);

digitalWrite(IN4, HIGH);

}

void stopRobot() {

digitalWrite(IN1, LOW);

digitalWrite(IN2, LOW);

digitalWrite(IN3, LOW);

digitalWrite(IN4, LOW);

}

void loop() {

long distance = getDistance()

Serial.println(distance)

if (distance > 20) {

moveForward();

}

else {

stopRobot();

delay(300)

moveBackward();

delay(500)

turnRight();

delay(500);

}

}

1. Power ON the robot.
2. Place it on a flat surface.
3. Observe the robot moving forward.
4. Place an obstacle in front of it.
5. The robot should stop, reverse, turn, and continue moving.

The robot successfully detects obstacles using the ultrasonic sensor and avoids collisions by changing its direction automatically. The system demonstrates the basics of autonomous navigation using simple sensors and control logic.

1. Servo-mounted ultrasonic sensor for scanning left and right
2. Bluetooth control mode
3. IR sensors for line following
4. Speed control using PWM
5. AI-based object recognition using a camera
6. Battery monitoring system

This Arduino-based Obstacle Avoiding Robot is an excellent beginner robotics project that introduces autonomous navigation, ultrasonic sensing, motor control, and embedded programming. It can serve as a foundation for more advanced robotic systems and smart vehicle applications.

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