Step 1: Prepare the Chassis
Step 2: Install the Arduino and Motor Driver Shield
Step 3: Wiring the Motors
Step 4: Mount the Ultrasonic Sensor and Servo
Step 5: Connect the Ultrasonic Sensor and Servo to Arduino
Step 6: Power Connections
Step 7: Plug the USB cable into the Arduino (car
Step 8: Upload the code

Published February 17, 2025 © LGPL

Obstacle-Avoiding 2-Wheel Car

Using ultrasonic sensors and Arduino, it navigates smoothly around obstacles, perfect for any enviro

BeginnerFull instructions provided218

Things used in this project

Hardware components

Arduino UNO

Texas Instruments Dual H-Bridge motor drivers L293D

SparkFun Ultrasonic Sensor - HC-SR04

9V battery (generic)

SG90 Micro-servo motor

DC Motor, 12 V

Software apps and online services

Arduino IDE

Hand tools and fabrication machines

Servo Motor, Premium Male/Male Jumper Wires

Solder Wire, Lead Free

10 Pc. Jumper Wire Kit, 5 cm Long

Story

This project taught me the fundamentals of robotics: motor control, sensor integration, and decision-making algorithms. I'm excited to share this project so you can build your own obstacle avoiding robot and perhaps even expand on it with your unique ideas!

Step 1: Prepare the Chassis

Mount the DC Motors: Attach the two DC motors to the sides of your chassis using screws or adhesive.
Attach the Wheels: Secure the wheels onto the motor shafts.
Add Support: Attach a caster wheel or sliding support at the front or back for stability.

Step 2: Install the Arduino and Motor Driver Shield

Stack the Shield: Plug the L293D Motor Driver Shield onto the Arduino microcontroller.
Position on Chassis: Place the Arduino and shield onto the chassis, ensuring easy access to the USB port for programming.

Step 3: Wiring the Motors

Connect Motors to Shield:

Motor 1 (Left Motor):

Connect one wire to one of the M1 terminals.
Connect the other wire to the other M1 terminal.

Motor 2 (Right Motor):

Connect one wire to one of the M4 terminals.
Connect the other wire to the other M4 terminal.

Step 4: Mount the Ultrasonic Sensor and Servo

Attach Sensor to Servo:

Use adhesive or a custom bracket to fix the ultrasonic sensor onto the mini servo motor's horn.

Mount Assembly on Chassis:

Secure the servo motor at the front center of the chassis.
Ensure the servo can rotate freely without obstruction.

Step 5: Connect the Ultrasonic Sensor and Servo to Arduino

Ultrasonic Sensor:

VCC to 5V on Arduino.
GND to GND on Arduino.
Trig to digital pin A1.
Echo to digital pin A2.

Servo Motor:

Locate the Servo Pin: Find the servo motor pins ( SER1 or SER2) on the L293D motor shield.
Attach the Servo Motor: Connect the control signal (yellow/orange) to the servo pin, power (red) to 5V, and ground (brown/black) to GND on the shield.

Step 6: Power Connections

Power Supply:

Connect the combined batteries (1.5V x 4 = 6V) to the motor power terminals on the shield.

Step 7: Plug the USB cable into the Arduino (car)

Plug the USB cable: Connect one end of the USB cable to the Arduino board on your car.
Connect to PC or Laptop: Insert the other end of the USB cable into a USB port on your PC or laptop.

Step 8: Upload the code

Upload the code: Open the Arduino IDE on your computer, select the correct COM port, and click the upload button to transfer your code to the Arduino.

Code

Code

#include <AFMotor.h>
#include <Servo.h>
#include <NewPing.h>

// Define pins for ultrasonic sensor
const int trigPin = A1;
const int echoPin = A2;
const int maxDistance = 40; // cm
NewPing sonar(trigPin, echoPin, maxDistance);

// Define motor control pins
AF_DCMotor leftMotor(1);
AF_DCMotor rightMotor(2);

// Attach servo motor to motor shield's servo pin
Servo servoMotor;

void setup() {
  // Set motor speeds
  leftMotor.setSpeed(200); // Set speed values from 0-255
  rightMotor.setSpeed(200);
  
  // Attach servo motor to motor shield's servo pin
  servoMotor.attach(10); // Assuming pin 10 on the shield is the servo pin
  servoMotor.write(115); // Center the servo motor
  delay(2000); // Wait for servo to center
}

void loop() {
  // Get distance from ultrasonic sensor
  int distance = sonar.ping_cm();
  
  if (distance <= 20) {
    moveStop(); // Stop the robot
    delay(300);
    moveBackward(); // Move backwards
    delay(400);
    moveStop();
    delay(300);
    
    // Check distances to the right and left
    int distanceRight = lookRight();
    delay(300);
    int distanceLeft = lookLeft();
    delay(300);
    
    // Turn towards the direction with more space
    if (distanceRight >= distanceLeft) {
      turnRight();
    } else {
      turnLeft();
    }
  } else {
    moveForward(); // Move forward
  }
}

void moveStop() {
  leftMotor.run(RELEASE);
  rightMotor.run(RELEASE);
}

void moveForward() {
  leftMotor.run(FORWARD);
  rightMotor.run(FORWARD);
}

void moveBackward() {
  leftMotor.run(BACKWARD);
  rightMotor.run(BACKWARD);
}

void turnRight() {
  moveStop();
  delay(300);
  leftMotor.run(FORWARD);
  rightMotor.run(BACKWARD);
  delay(500);
  moveStop();
}

void turnLeft() {
  moveStop();
  delay(300);
  rightMotor.run(FORWARD);
  leftMotor.run(BACKWARD);
  delay(500);
  moveStop();
}

int lookRight() {
  servoMotor.write(50);
  delay(500);
  int distance = sonar.ping_cm();
  servoMotor.write(115);
  return distance;
}

int lookLeft() {
  servoMotor.write(170);
  delay(500);
  int distance = sonar.ping_cm();
  servoMotor.write(115);
  return distance;
}

Credits

pat

13 projects • 4 followers

AI Convergence Engineering, Software Engineering, ML, deep learning, image processing, computer vision, circuit design, and Edge AI devices.

Obstacle-Avoiding 2-Wheel Car