IoT project of Sonar system using Ultrasonic Sensor HC-SR04 and Arduino device

Let's build an IoT project of sonar system using Ultrasonic HC-SR04 device and Arduino (Arduino UNO). The sonar system detects the objects that come within its range (angle and distance) and display its appearance on Laptop (Monitor) screen. Sonar uses the echo principle of sound waves through an object.

Hardware requirements

Arduino UNO board
USB cable connector for Arduino UNO
Ultra Sonic HC-SR04
Jumper wires male to female
Micro Server SG90

Software requirements

Arduino software
Processing software

The working principle of the Sonar system

The Ultra Sonic HC-SR04 emits ultrasound at 40,000Hz that travels in the air. If there is an object or obstacle comes in its path, then the sound wave collides with the object and bounces back to the Ultra Sonic module. The object's angle and distance have displayed over the screen (Monitor).

In this project, we use the processing app to display the sonar range.

Before writing a program for Sonar system, first go through Ultrasonic Sensor HC-SR04 and Arduino to distance calculationwhere we provide the working principle of Ultrasonic device.

Write an Arduino program to measure distance using Ultra Sonic HC-SR04 and rotate servo motor.

#include <Servo.h>
const int trigPin = 8;
const int echoPin = 9;
long duration; //declare time duration
int distance;  //declare distance
Servo myServo; // Object servo

void setup() {
  pinMode(trigPin, OUTPUT); // trigPin as an output
  pinMode(echoPin, INPUT); // echoPin as an input
  Serial.begin(9600);
  myServo.attach(10); // pin connected to Servo
}

void loop() {
  // rotating servo i++ depicts increment of one degree
  for(int i=0;i<=180;i++){  
  myServo.write(i);
  delay(30);
  distance = calculateDistance();
  Serial.print(i); 
  Serial.print(","); 
  Serial.print(distance); 
  Serial.print(".");
  }
  // Repeats the previous lines from 180 to 0 degrees
  for(int i=180;i>0;i--){  
  myServo.write(i);
  delay(30);
  distance = calculateDistance();
  Serial.print(i);
  Serial.print(",");
  Serial.print(distance);
  Serial.print(".");
  }
}

int calculateDistance(){ 
  digitalWrite(trigPin, LOW); 
  delayMicroseconds(2);
  // Sets the trigPin on HIGH state for 10 micro seconds
  digitalWrite(trigPin, HIGH); 
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);
  duration = pulseIn(echoPin, HIGH); 
  distance= duration*0.034/2;
  return distance;
}

Compile your code.

IoT project of Sonar system using Ultrasonic Sensor HC-SR04 and Arduino device

Now, connect the Arduino device with your personal computer using an Arduino USB connector and upload the program.

Digital circuit diagram

Ultrasonic Sensor HC-SR04 Arduino UNO
VCC --------------------------------> 5v
Trig --------------------------------> Pin 8
Echo --------------------------------> Pin 9
GND --------------------------------> GND

Micro Servo Motor SG90 Arduino UNO
Orange wire ----------------------> Pin 10
Red wire ----------------------> 3.3v
Brown wire ----------------------> GND

Now, place the bigger part of a fan over servo motor's rotating wheel. Place your Ultrasonic device over the servo motor to make it rotating (you may use double sided sticky tape).

Test the following code in the Processing IDE and run it. The Processing IDE displays the angle distance of an object when it comes in the range of Ultrasonic device.

import processing.serial.*;
import java.awt.event.KeyEvent;
import java.io.IOException;
Serial myPort;// defubes variables
String angle="";
String distance="";
String data="";
String noObject;
float pixsDistance;
int iAngle, iDistance;
int index1=0;
int index2=0;
PFont orcFont;
void setup() {
  size (1366, 768);
  smooth();
  myPort = new Serial(this,"COM3", 9600); // change this accordingly
  myPort.bufferUntil('.'); // reads the data from the serial port up to the character ?.?. So actually it reads this: angle,distance.
}
void draw() {
  fill(98,245,31);
  // simulating motion blur and slow fade of the moving line
  noStroke();
  fill(0,4);
  rect(0, 0, width, height-height*0.065);
  fill(98,245,31); // green color
  // calls the functions for drawing the radar
  drawRadar();
  drawLine();
  drawObject();
  drawText();
}
void serialEvent (Serial myPort) { // starts reading data from the Serial Port
// reads the data from the Serial Port up to the character ?.? and puts it into the String variable ?data?.
  data = myPort.readStringUntil('.');
  data = data.substring(0,data.length()-1);
  index1 = data.indexOf(","); // find the character ?,? and puts it into the variable ?index1?
  angle= data.substring(0, index1); // read the data from position ?0? to position of the variable index1 or thats the value of the angle the Arduino Board sent into the Serial Port
  distance= data.substring(index1+1, data.length()); // read the data from position ?index1? to the end of the data pr thats the value of the distance
  // converts the String variables into Integer
  iAngle = int(angle);
  iDistance = int(distance);
}
void drawRadar() {
  pushMatrix();
  translate(width/2,height-height*0.074); // moves the starting coordinats to new location
  noFill();
  strokeWeight(2);
  stroke(98,245,31);
  // draws the arc lines
  arc(0,0,(width-width*0.0625),(width-width*0.0625),PI,TWO_PI);
  arc(0,0,(width-width*0.27),(width-width*0.27),PI,TWO_PI);
  arc(0,0,(width-width*0.479),(width-width*0.479),PI,TWO_PI);
  arc(0,0,(width-width*0.687),(width-width*0.687),PI,TWO_PI);
  // draws the angle lines
  line(-width/2,0,width/2,0);
  line(0,0,(-width/2)*cos(radians(30)),(-width/2)*sin(radians(30)));
  line(0,0,(-width/2)*cos(radians(60)),(-width/2)*sin(radians(60)));
  line(0,0,(-width/2)*cos(radians(90)),(-width/2)*sin(radians(90)));
  line(0,0,(-width/2)*cos(radians(120)),(-width/2)*sin(radians(120)));
  line(0,0,(-width/2)*cos(radians(150)),(-width/2)*sin(radians(150)));
  line((-width/2)*cos(radians(30)),0,width/2,0);
  popMatrix();
}
void drawObject() {
  pushMatrix();
  translate(width/2,height-height*0.074); // moves the starting coordinats to new location
  strokeWeight(9);
  stroke(255,10,10); // red color
  pixsDistance = iDistance*((height-height*0.1666)*0.025); // covers the distance from the sensor from cm to pixels
  // limiting the range to 40 cms
  if(iDistance<40){
    // draws the object according to the angle and the distance
    line(pixsDistance*cos(radians(iAngle)),-pixsDistance*sin(radians(iAngle)),(width-width*0.505)*cos(radians(iAngle)),-(width-width*0.505)*sin(radians(iAngle)));
  }
  popMatrix();
}
void drawLine() {
  pushMatrix();
  strokeWeight(9);
  stroke(30,250,60);
  translate(width/2,height-height*0.074); // moves the starting coordinats to new location
  line(0,0,(height-height*0.12)*cos(radians(iAngle)),-(height-height*0.12)*sin(radians(iAngle))); // draws the line according to the angle
  popMatrix();
}
void drawText() { // draws the texts on the screen
  pushMatrix();
  if(iDistance>40) {
    noObject = "Out of Range";
  }
  else {
    noObject = "In Range";
  }
  fill(0,0,0);
  noStroke();
  rect(0, height-height*0.0648, width, height);
  fill(98,245,31);
  textSize(25);
  text("10cm",width-width*0.3854,height-height*0.0833);
  text("20cm",width-width*0.281,height-height*0.0833);
  text("30cm",width-width*0.177,height-height*0.0833);
  text("40cm",width-width*0.0729,height-height*0.0833);
  textSize(40);
  text("Angle: " + iAngle +" ?", width-width*0.78, height-height*0.0277);
  text("Distance: ", width-width*0.36, height-height*0.0277);
  if(iDistance<40) {
    text(" " + iDistance +" cm", width-width*0.225, height-height*0.0277);
  }
  textSize(25);
  fill(98,245,60);
  translate((width-width*0.4994)+width/2*cos(radians(30)),(height-height*0.0907)-width/2*sin(radians(30)));
  rotate(-radians(-60));
  text("30?",0,0);
  resetMatrix();
  translate((width-width*0.503)+width/2*cos(radians(60)),(height-height*0.0888)-width/2*sin(radians(60)));
  rotate(-radians(-30));
  text("60?",0,0);
  resetMatrix();
  translate((width-width*0.507)+width/2*cos(radians(90)),(height-height*0.0833)-width/2*sin(radians(90)));
  rotate(radians(0));
  text("90?",0,0);
  resetMatrix();
  translate(width-width*0.513+width/2*cos(radians(120)),(height-height*0.07129)-width/2*sin(radians(120)));
  rotate(radians(-30));
  text("120?",0,0);
  resetMatrix();
  translate((width-width*0.5104)+width/2*cos(radians(150)),(height-height*0.0574)-width/2*sin(radians(150)));
  rotate(radians(-60));
  text("150?",0,0);
  popMatrix();
}

Now, run your processing application and place an object (pen) in front of Ultrasonic device. When the servo motor rotates and objects come in the range of Ultrasonic device then the appearance of an object appears on display screen. The presence of an object is marked with the red mark and if there is no any object in the range of Ultrasonic device processing application display green marks.