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Arduino UNO-Based Autonomous Obstacle-Avoiding Robot with Ultrasonic Sensor and Motor Control

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Circuit Documentation

Summary

This circuit is designed to control a robotic vehicle using an Arduino UNO microcontroller. The vehicle is equipped with two DC motors, a micro servo motor, and an HC-SR04 ultrasonic sensor for obstacle detection. The L298N motor driver is used to control the DC motors. The Arduino UNO reads data from the ultrasonic sensor and controls the motors and servo based on the sensor readings.

Component List

  1. Arduino UNO

    • Description: A microcontroller board based on the ATmega328P.
    • Pins: UNUSED, IOREF, Reset, 3.3V, 5V, GND, Vin, A0, A1, A2, A3, A4, A5, SCL, SDA, AREF, D13, D12, D11, D10, D9, D8, D7, D6, D5, D4, D3, D2, D1, D0

  2. Motor amarillo motorreductor hobby

    • Description: A small DC motor with a gearbox.
    • Pins: vcc, GND

  3. HC-SR04 Ultrasonic Sensor

    • Description: An ultrasonic distance sensor.
    • Pins: VCC, TRIG, ECHO, GND

  4. L298N DC motor driver

    • Description: A dual H-bridge motor driver.
    • Pins: OUT1, OUT2, 12V, GND, 5V, OUT3, OUT4, 5V-ENA-JMP-I, 5V-ENA-JMP-O, +5V-J1, +5V-J2, ENA, IN1, IN2, IN3, IN4, ENB

  5. Micro servo 9G

    • Description: A small servo motor.
    • Pins: GND, +5V, PWM

  6. 7.4v Battery

    • Description: A 7.4V battery pack.
    • Pins: +, -

Wiring Details

Arduino UNO

Motor amarillo motorreductor hobby

L298N DC motor driver

HC-SR04 Ultrasonic Sensor

Micro servo 9G

7.4v Battery

Code Documentation

#include <Servo.h>          // Servo motor library. This is standard library
#include <NewPing.h>        // Ultrasonic sensor function library. You must install this library

// our L298N control pins
const int LeftMotorForward = 2;
const int LeftMotorBackward = 3;
const int RightMotorForward = 4;
const int RightMotorBackward = 5;

// sensor pins
#define trig_pin A0 // analog input 1
#define echo_pin A1 // analog input 2

#define maximum_distance 200
boolean goesForward = false;
int distance = 100;

NewPing sonar(trig_pin, echo_pin, maximum_distance); // sensor function
Servo servo_motor; // our servo name

void setup() {
  pinMode(RightMotorForward, OUTPUT);
  pinMode(LeftMotorForward, OUTPUT);
  pinMode(LeftMotorBackward, OUTPUT);
  pinMode(RightMotorBackward, OUTPUT);
  
  servo_motor.attach(6); // our servo pin

  servo_motor.write(90);
  delay(2000);
  distance = readPing();
  delay(100);
  distance = readPing();
  delay(100);
  distance = readPing();
  delay(100);
  distance = readPing();
  delay(100);
}

void loop() {
  int distanceRight = 0;
  int distanceLeft = 0;
  delay(50);

  if (distance <= 10) {
    moveStop();
    delay(300);
    moveBackward();
    delay(400);
    moveStop();
    delay(300);
    distanceRight = lookRight();
    delay(300);
    distanceLeft = lookLeft();
    delay(300);

    if (distance >= distanceLeft) {
      turnRight();
      moveStop();
    } else {
      turnLeft();
      moveStop();
    }
  } else {
    moveForward(); 
  }
  distance = readPing();
}

int lookRight() {  
  servo_motor.write(10);
  delay(500);
  int distance = readPing();
  delay(100);
  servo_motor.write(90);
  return distance;
}

int lookLeft() {
  servo_motor.write(170);
  delay(500);
  int distance = readPing();
  delay(100);
  servo_motor.write(90);
  return distance;
  delay(100);
}

int readPing() {
  delay(70);
  int cm = sonar.ping_cm();
  if (cm == 0) {
    cm = 250;
  }
  return cm;
}

void moveStop() {
  digitalWrite(RightMotorForward, LOW);
  digitalWrite(LeftMotorForward, LOW);
  digitalWrite(RightMotorBackward, LOW);
  digitalWrite(LeftMotorBackward, LOW);
}

void moveForward() {
  if (!goesForward) {
    goesForward = true;
    digitalWrite(LeftMotorForward, HIGH);
    digitalWrite(RightMotorForward, HIGH);
    digitalWrite(LeftMotorBackward, LOW);
    digitalWrite(RightMotorBackward, LOW); 
  }
}

void moveBackward() {
  goesForward = false;
  digitalWrite(LeftMotorBackward, HIGH);
  digitalWrite(RightMotorBackward, HIGH);
  digitalWrite(LeftMotorForward, LOW);
  digitalWrite(RightMotorForward, LOW);
}

void turnRight() {
  digitalWrite(LeftMotorForward, HIGH);
  digitalWrite(RightMotorBackward, HIGH);
  digitalWrite(LeftMotorBackward, LOW);
  digitalWrite(RightMotorForward, LOW);
  delay(500);
  digitalWrite(LeftMotorForward, HIGH);
  digitalWrite(RightMotorForward, HIGH);