How to make an obstacle avoiding robot using Arduino & Ultrasonic sensor

How to make an obstacle avoiding robot using arduino & ultrasonic sensor

Hello, welcome back. In this tutorial, we will learn how to make a cute obstacle avoiding robot using the Arduino. This project is mainly based on the Ultrasonic sensor. We have also created an obstacle avoiding robot in a few previous tutorials and if you want you can study them by following the links below.

Also, you can do this project using cardboard or foam board as it costs less.

The process of this robot

When powering up this robot will move forward. Also, the ultrasonic sensor calculates the distance to the front obstacle. In this case, if the front distance is less than or equal to 10cm, the robot will stop. Then, the servo motor is turned left side and right side and the ultrasonic sensor receive the distance on both sides. Afterwards, the Arduino board calculates the side of the longest distance. Then, the robot turns to that side and moves forward. Also, this process is continuous.

OK, let’s do this robot project step by step. The required components are given below.

Disclosure: These Amazon links are Affiliate links. As an Amazon Associate, I earn from qualifying purchases.

Step 1

Firstly, identify these components.

UNO board
Battery holder
Jumper wires

Step 2

Secondly, cut a piece of foam board as follows.

How to make an obstacle avoiding robot using arduino & ultrasonic sensor

Step 3

Next, glue the gear motors.

Step 4

Then, glue the Arduino UNO board and L298N motor driver board to the robot chassis.

Step 5

OK, next connect the robot wheels for the gear motors.

How to make an obstacle avoiding robot using arduino & ultrasonic sensor

Step 6

Then, glue the Ultrasonic sensor and servo motor as follows.

Step 7

Now, connect these components. To do this, use the circuit diagram below.

How to make an obstacle avoiding robot using arduino & ultrasonic sensor

Step 8

Next, attach the rotating wheel to the robot chassis using a piece of foam board.

Step 9

After, glue the Li-ion battery holder and connect it to the motor driver board.

Step 10

Next, create the robot head and attach it. Afterwards, connect this robot to the computer.

Step 11

So, let’s creates the program for this project. It is as follows.

  • The complete program of this project – download
/*Obstacle avoiding robot
 * https://srituhobby.com
 */
 
#include <Servo.h>
Servo myservo;
byte servostart = 105;
int distanceleft = 0;
int distanceright = 0;
long t, cm;

//Motor one
#define ENA 9
#define IN1 2
#define IN2 3

//Motor two
#define IN3 4
#define IN4 5
#define ENB 10

//Sensor
#define Trig 6
#define Echo 7

#define Speed 255

void setup() {
  myservo.attach(11);
  //Motor one
  pinMode(ENA, OUTPUT);
  pinMode(IN1, OUTPUT);
  pinMode(IN2, OUTPUT);
  //Motor two
  pinMode(ENB, OUTPUT);
  pinMode(IN3, OUTPUT);
  pinMode(IN4, OUTPUT);

  //Sensor
  pinMode(Trig, OUTPUT);
  pinMode(Echo, INPUT);
  Serial.begin(9600);
  start();
}
void loop() {
  getdistance();
  Serial.println(cm);
  int leftdistance = 0;
  int rightdistance = 0;

  if (cm <= 20) {
    Stop();
    delay(200);
    leftdistance = leftsee();
    rightdistance = rightsee();

    if (leftdistance >= rightdistance) {
      turnleft();
      delay(200);
      Stop();
    } else {
      turnright();
      delay(200);
      Stop();
    }
  } else {
    forward();
    Serial.println("forward");
  }
}

void forward() {
  analogWrite(ENA, Speed);
  analogWrite(ENB, Speed);
  digitalWrite(IN1, LOW);
  digitalWrite(IN2, HIGH);
  digitalWrite(IN3, HIGH);
  digitalWrite(IN4, LOW);
}

void turnright() {
  analogWrite(ENA, Speed);
  analogWrite(ENB, Speed);
  digitalWrite(IN1, HIGH);
  digitalWrite(IN2, LOW);
  digitalWrite(IN3, HIGH);
  digitalWrite(IN4, LOW);
}
void turnleft() {
  analogWrite(ENA, Speed);
  analogWrite(ENB, Speed);
  digitalWrite(IN1, LOW);
  digitalWrite(IN2, HIGH);
  digitalWrite(IN3, LOW);
  digitalWrite(IN4, HIGH);
}
void Stop() {
  analogWrite(ENA, 0);
  analogWrite(ENB, 0);
  digitalWrite(IN1, LOW);
  digitalWrite(IN2, LOW);
  digitalWrite(IN3, LOW);
  digitalWrite(IN4, LOW);
}

void start() {
  delay(3000);
  for (int a = 0; a < 4; a++) {
    myservo.write(servostart);
    delay(50);
    myservo.write(40);
    delay(50);
    myservo.write(90);
    delay(50);
    myservo.write(servostart);
  }
}

int leftsee() {
  myservo.write(servostart);
  delay(1000);
  myservo.write(175);
  delay(1000);
  distanceleft = getdistance();
  myservo.write(servostart);
  return distanceleft;
}
int rightsee() {
  myservo.write(servostart);
  delay(1000);
  myservo.write(5);
  delay(1000);
  distanceright = getdistance();
  myservo.write(servostart);
  return distanceright;
}
int getdistance() {
  digitalWrite(Trig, LOW);
  delayMicroseconds(4);
  digitalWrite(Trig, HIGH);
  delayMicroseconds(10);
  digitalWrite(Trig, LOW);
  t = pulseIn(Echo, HIGH);
  cm = t / 29 / 2;
  return cm;
}

Code explanation

Firstly, the servo motor library is included.

#include <Servo.h>
Servo myservo;

Next, the motor PINs and sensor PINs are defined.

//Motor one
#define ENA 9
#define IN1 2
#define IN2 3

//Motor two
#define IN3 4
#define IN4 5
#define ENB 10

//Sensor
#define Trig 6
#define Echo 7

In the setup function,

void setup() {
  myservo.attach(11);//Includes servo motor PIN
  //The motor pins are set as output pins
  pinMode(ENA, OUTPUT);
  pinMode(IN1, OUTPUT);
  pinMode(IN2, OUTPUT);
  //Motor two
  pinMode(ENB, OUTPUT);
  pinMode(IN3, OUTPUT);
  pinMode(IN4, OUTPUT);

  //The ultrasonic sensor trig pin set as output pin and the echo pin set as an input pin.
  pinMode(Trig, OUTPUT);
  pinMode(Echo, INPUT);
//The serial monitor begin
  Serial.begin(9600);
//The robot start function is called. It is described below.
  start();
}

In the loop function,

void loop() {
//Gets the distance values
  getdistance();
  Serial.println(cm);
  int leftdistance = 0;
  int rightdistance = 0;
// These values are checked using the IF condition. If the values are less than or equal to 20, the robot stops.
  if (cm <= 20) {
    Stop();
    delay(200);
//The servo motor rotates to the left and takes the distance using the ultrasonic sensor
    leftdistance = leftsee();
//The servo motor rotates to the right and takes the distance using the ultrasonic sensor
    rightdistance = rightsee();
//If the distance to the left is greater than the distance to the right, the robot turns left
    if (leftdistance >= rightdistance) {
      turnleft();
      delay(200);
      Stop();
//If the distance to the right is greater than the distance to the left, the robot turns right
    } else {
      turnright();
      delay(200);
      Stop();
    }
//Otherwise, the robot moves forward
  } else {
    forward();
    Serial.println("forward");
  }
}

Motor rotation functions,

void forward() {
  analogWrite(ENA, Speed);
  analogWrite(ENB, Speed);
  digitalWrite(IN1, LOW);
  digitalWrite(IN2, HIGH);
  digitalWrite(IN3, HIGH);
  digitalWrite(IN4, LOW);
}

void turnright() {
  analogWrite(ENA, Speed);
  analogWrite(ENB, Speed);
  digitalWrite(IN1, HIGH);
  digitalWrite(IN2, LOW);
  digitalWrite(IN3, HIGH);
  digitalWrite(IN4, LOW);
}
void turnleft() {
  analogWrite(ENA, Speed);
  analogWrite(ENB, Speed);
  digitalWrite(IN1, LOW);
  digitalWrite(IN2, HIGH);
  digitalWrite(IN3, LOW);
  digitalWrite(IN4, HIGH);
}
void Stop() {
  analogWrite(ENA, 0);
  analogWrite(ENB, 0);
  digitalWrite(IN1, LOW);
  digitalWrite(IN2, LOW);
  digitalWrite(IN3, LOW);
  digitalWrite(IN4, LOW);
}

The robot start function,

void start() {
  delay(3000);
  for (int a = 0; a < 4; a++) {
    myservo.write(servostart);
    delay(50);
    myservo.write(40);
    delay(50);
    myservo.write(90);
    delay(50);
    myservo.write(servostart);
  }
}

The servo motor turn left function,

int leftsee() {
  myservo.write(servostart);
  delay(1000);
  myservo.write(175);
  delay(1000);
  distanceleft = getdistance();
  myservo.write(servostart);
  return distanceleft;
}

The servo motor turn right function,

int rightsee() {
  myservo.write(servostart);
  delay(1000);
  myservo.write(5);
  delay(1000);
  distanceright = getdistance();
  myservo.write(servostart);
  return distanceright;
}

The ultrasonic sensor function,

int getdistance() {
  digitalWrite(Trig, LOW);
  delayMicroseconds(4);
  digitalWrite(Trig, HIGH);
  delayMicroseconds(10);
  digitalWrite(Trig, LOW);
  t = pulseIn(Echo, HIGH);
  cm = t / 29 / 2;
  return cm;
}

Step 12

Now, select board and port. After, upload this code to the Arduino board.

Step 13

Lastly, put the batteries into the battery holder and switch ON this robot. OK, now enjoy this project. The full video guide is given below. So, we will meet in the next tutorial.

How to make an obstacle avoiding robot using arduino & ultrasonic sensor

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