Building the device

• First I made a cardboard stand for connecting the Ultrasonic sensor to the Servo motor. I folded it like it’s shown on the picture below, glued it and secured to the servo motor using a screw like this.

• Also I attached a pin header on which I soldered 4 jumper wires for connecting the sensor.

• Finally I secured the servo motor to the Arduino Board using an elastic band.

Circuit Schematics

I connected the Ultrasonic Sensor HC-SR04 to the pins number 10 and 11 and the servo motor to the pin number 12 on the Arduino Board.

Source codes

Now we need to make a code and upload it to the Arduino Board that will enable the interaction between the Arduino and the Processing IDE. For understanding how the connection works click here to visit my Arduino and Processing Tutorial.

Here’s the Arduino Source Code with description of each line of the code:

// Includes the Servo library
#include <Servo.h>.
// Defines Tirg and Echo pins of the Ultrasonic Sensor
const int trigPin = 10;
const int echoPin = 11;
// Variables for the duration and the distance
long duration;
int distance;
Servo myServo; // Creates a servo object for controlling the servo motor
void setup() {
pinMode(trigPin, OUTPUT); // Sets the trigPin as an Output
pinMode(echoPin, INPUT); // Sets the echoPin as an Input
Serial.begin(9600);
myServo.attach(12); // Defines on which pin is the servo motor attached
}
void loop() {
// rotates the servo motor from 15 to 165 degrees
for(int i=15;i<=165;i++){
myServo.write(i);
delay(30);
distance = calculateDistance();// Calls a function for calculating the distance measured by the Ultrasonic sensor for each degree
Serial.print(i); // Sends the current degree into the Serial Port
Serial.print(","); // Sends addition character right next to the previous value needed later in the Processing IDE for indexing
Serial.print(distance); // Sends the distance value into the Serial Port
Serial.print("."); // Sends addition character right next to the previous value needed later in the Processing IDE for indexing
}
// Repeats the previous lines from 165 to 15 degrees
for(int i=165;i>15;i--){
myServo.write(i);
delay(30);
distance = calculateDistance();
Serial.print(i);
Serial.print(",");
Serial.print(distance);
Serial.print(".");
}
}
// Function for calculating the distance measured by the Ultrasonic sensor
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); // Reads the echoPin, returns the sound wave travel time in microseconds
distance= duration*0.034/2;
return distance;
}

Now we will receive the values for the angle and the distance measured by the sensor from the Arduino Board into the Processing IDE using the SerialEvent() function which reads the data from the Serial Port and we will put the values of the angle and the distance into the variables iAngle and iDistance. These variable will be used for drawing the radar, the lines, the detected objects and some of the text.

For drawing the radar I made this function drawRadar() which consist of arc() and line() functions.

void drawRadar() {
pushMatrix();
translate(960,1000); // moves the starting coordinats to new location
noFill();
strokeWeight(2);
stroke(98,245,31);
// draws the arc lines
arc(0,0,1800,1800,PI,TWO_PI);
arc(0,0,1400,1400,PI,TWO_PI);
arc(0,0,1000,1000,PI,TWO_PI);
arc(0,0,600,600,PI,TWO_PI);
// draws the angle lines
line(-960,0,960,0);
line(0,0,-960*cos(radians(30)),-960*sin(radians(30)));
line(0,0,-960*cos(radians(60)),-960*sin(radians(60)));
line(0,0,-960*cos(radians(90)),-960*sin(radians(90)));
line(0,0,-960*cos(radians(120)),-960*sin(radians(120)));
line(0,0,-960*cos(radians(150)),-960*sin(radians(150)));
line(-960*cos(radians(30)),0,960,0);
popMatrix();
}

For drawing the line that is moving along the radar I made this function drawLine(). Its center of rotation is set with the translate()...

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