Obstacle Avoiding
Robotic Car

Autonomous Smart Navigation | NextGenRoboticX

In this project, we will explain how to design and develop an Obstacle Avoiding Robotic Car using an Arduino Uno, an Adafruit Motor Shield, an Ultrasonic Sensor, DC Gear Motors, and a Servo Motor. The Obstacle Avoiding Robot is an intelligent device that can automatically sense the obstacle in front of it and steer to avoid collisions by turning left or right according to the clear path.

Obstacle Avoiding Robotic Car

Figure 1: Fully Assembled Obstacle Avoiding Robotic Car

Project Demonstration Video

Hardware Requirements

Hardware Component Integration

Figure 2: Complete Hardware Integration Layout

Core Component Deep-Dive

1. Arduino Uno Brain

The Arduino Uno is a micro-controller board based on the ATmega328. It has 14 digital input/output pins (where 6 can be used as PWM outputs), 6 analog inputs, a 16 MHz ceramic resonator, a USB connection, a power jack, an ICSP header, and a reset button. It contains everything needed to support the microcontroller; simply connect it to a computer with a USB cable or power it with an AC-to-DC adapter or battery to get started.

Arduino Uno Board

Figure 3: Arduino Uno Microcontroller

Arduino Uno Specifications

2. Adafruit Motor Shield

The Adafruit Motor Shield is a great and quick way to control DC motors, servos, or even stepper motors. It has the capability of controlling up to 2 stepper motors, 4 DC motors, and 2 hobby servos. Perfect for compiling multi-motor robotics applications on a single board.

Adafruit Motor Shield

Figure 4: Adafruit H-Bridge Motor Shield

Motor Shield Specifications

3. BO Gear Motor with Plastic Tire Wheel

A DC Geared BO (Battery Operated) motor is a simple DC motor equipped with a gearbox attached to it. It provides high torque and steady angular speed, perfect for navigating different types of terrains.

BO Geared DC Motor

Figure 5: High-torque BO Geared Motor & Wheel Assembly

Geared Motor Specifications

4. TowerPro SG-90 Servo Motor

A servo motor is an electrical device that can rotate an object with great precision. To make the motor rotate, we power it with +5V and send PWM (Pulse Width Modulation) control signals to the signal wire. By varying the on-time pulse duration from 1ms to 2ms, we can control its angle precisely from 0° to 180°.

TowerPro SG-90 Servo Motor

Figure 6: TowerPro SG-90 Servo Motor

Servo PWM Calibration Graph

Figure 7: PWM Steering Pulse Width Calibration Diagram

5. HC-SR04 Ultrasonic Sensor

Ultrasonic sensors measure distance by utilizing high-frequency sound waves. The sensor head emits an ultrasonic burst and measures the time interval until the wave reflects off a target and returns. The distance is calculated using the physical constant of sound speed: Distance L = 1/2 × T × C (where T is roundtrip time, and C is the speed of sound).

HC-SR04 Ultrasonic Sensor

Figure 8: HC-SR04 Ultrasonic Sensor Module

Ultrasonic Distance Formula Diagram

Figure 9: Distance Measurement Propagation Diagram

Circuit Architecture

The circuit utilizes the Adafruit Motor Shield mounted on top of the Arduino Uno. The DC gear motors connect directly to the terminal blocks, and the SG90 servo connects to the dedicated 5V Servo_1 pins. The HC-SR04 ultrasonic sensor is powered from the shield's 5V supply, with its trigger and echo lines routed to Analog Pins A0 and A1.

Circuit Schematic Diagram

Figure 10: Electronic Circuit Hookup Schematic

Arduino Source Code

Upload the following code to your Arduino Uno board using the Arduino IDE. Make sure you have installed the AFMotor and Servo libraries beforehand.

// Obstacle Avoiding Robotic Car using Adafruit Motor Shield - NextGenRoboticX
#include <AFMotor.h>
#include <Servo.h>

const int TrigPin = A0; // Trig pin connected to Analog A0
const int EchoPin = A1; // Echo pin connected to Analog A1

AF_DCMotor motor1(1); // Left Front Motor
AF_DCMotor motor2(2); // Left Rear Motor
AF_DCMotor motor3(3); // Right Front Motor
AF_DCMotor motor4(4); // Right Rear Motor

Servo scanServo;

void setup() {
  pinMode(TrigPin, OUTPUT);
  pinMode(EchoPin, INPUT);
  
  scanServo.attach(10); // Servo connected to Servo_1 header
  scanServo.write(90);  // Center position
  delay(500);
  
  // Set initial motor speed
  motor1.setSpeed(200);
  motor2.setSpeed(200);
  motor3.setSpeed(200);
  motor4.setSpeed(200);
}

int getDistance() {
  digitalWrite(TrigPin, LOW);
  delayMicroseconds(2);
  digitalWrite(TrigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(TrigPin, LOW);
  
  long duration = pulseIn(EchoPin, HIGH);
  return duration * 0.034 / 2; // Distance in cm
}

void loop() {
  int distance = getDistance();
  
  if (distance > 25) {
    moveForward();
  } else {
    stopRobot();
    delay(300);
    lookAroundAndSteer();
  }
  delay(50);
}

void lookAroundAndSteer() {
  scanServo.write(150); // Scan Left
  delay(500);
  int leftDistance = getDistance();
  
  scanServo.write(30);  // Scan Right
  delay(500);
  int rightDistance = getDistance();
  
  scanServo.write(90);  // Return Center
  delay(300);
  
  if (leftDistance > rightDistance && leftDistance > 25) {
    turnLeft();
    delay(600);
  } else if (rightDistance > leftDistance && rightDistance > 25) {
    turnRight();
    delay(600);
  } else {
    moveBackward();
    delay(800);
    turnRight();
    delay(600);
  }
  stopRobot();
}

void moveForward() {
  motor1.run(FORWARD);
  motor2.run(FORWARD);
  motor3.run(FORWARD);
  motor4.run(FORWARD);
}

void stopRobot() {
  motor1.run(RELEASE);
  motor2.run(RELEASE);
  motor3.run(RELEASE);
  motor4.run(RELEASE);
}

void turnLeft() {
  motor1.run(BACKWARD);
  motor2.run(BACKWARD);
  motor3.run(FORWARD);
  motor4.run(FORWARD);
}

void turnRight() {
  motor1.run(FORWARD);
  motor2.run(FORWARD);
  motor3.run(BACKWARD);
  motor4.run(BACKWARD);
}

void moveBackward() {
  motor1.run(BACKWARD);
  motor2.run(BACKWARD);
  motor3.run(BACKWARD);
  motor4.run(BACKWARD);
}

More Projects