ARDUINO OBSTACLE AVOIDING CAR - A TUTORIAL GUIDE

I wanted to work on building a robotic car that could maneuver on its own and avoid obstacles. 
This project was an extension to the 'Smartphone Controlled RC Car' project I worked on last year during the pandemic. You can read more about that project here.

ARDUINO OBSTACLE AVOIDING CAR - A TUTORIAL GUIDE

Components Used

1. Arduino Uno
2. L298N motor driver
3. HC-SR04  distance sensor
4. Servo Motor
5. Cardboard and wheels for mounting everything

Description

For the project I attached the HC-SR04  distance sensor on top of a servo motor. The servo motor would rotate the distance sensor which could then scan the room and send data to the Arduino microcontroller. If  the sensor detected an obstacle within its proximity, the Arduino would then via the L298N - motor driver change the  RPM of either of the car's tires - effectively changing the direction.  

Here is the video I made detailing every step through the entire build of the project. :)

Arduino Source Code:

#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 = 7;

const int LeftMotorBackward = 6;

const int RightMotorForward = 4;

const int RightMotorBackward = 5;

//sensor pins

#define trig_pin A1 //analog input 1

#define echo_pin A2 //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(10); //our servo pin

  servo_motor.write(115);

  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 <= 20){

    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(50);

  delay(500);

  int distance = readPing();

  delay(100);

  servo_motor.write(115);

  return distance;

}

int lookLeft(){

  servo_motor.write(170);

  delay(500);

  int distance = readPing();

  delay(100);

  servo_motor.write(115);

  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);

  

  digitalWrite(LeftMotorBackward, LOW);

  digitalWrite(RightMotorBackward, LOW);

 

  

  

}

void turnLeft(){

  digitalWrite(LeftMotorBackward, HIGH);

  digitalWrite(RightMotorForward, HIGH);

  

  digitalWrite(LeftMotorForward, LOW);

  digitalWrite(RightMotorBackward, LOW);

  delay(500);

  

  digitalWrite(LeftMotorForward, HIGH);

  digitalWrite(RightMotorForward, HIGH);

  

  digitalWrite(LeftMotorBackward, LOW);

  digitalWrite(RightMotorBackward, LOW);

}