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Radar project uses ultrasonic sensor HC-SR04 (to measure distance objects) which is attached in servo motor SG90 that will rotate 0 to 120 degree. Result data is sent to computer by COM port and show in HMI by Visual Studio C++/CLI



Hardware need:
1. Arduino Pro Mini
2. Ultrasonic sensor HC-SR04
3. Servo motor SG90
4. Motor base
1. Arduino Pro Mini

2. Ultrasonic sensor HC-SR04

3. Servo motor SG90



Step 1. Ultrasonic sensor
This sensor use ultrasonic to measure distance to object. Distance detected range is 2cm to 400cm
At beginning startup, it needs time to warm up (about 1min) in order working well with Arduino
// Sets the trigPin on HIGH state for 10 micro seconds
    digitalWrite(trigPin, HIGH);
    delayMicroseconds(10);
    digitalWrite(trigPin, LOW);
    // Reads the echoPin, returns the sound wave travel time in microseconds
    duration = pulseIn(echoPin, HIGH, 23529); //23529us for timeout 4.0m

    // Calculating the distance
    distance= duration*0.034/2;
To measure distance, trigger pin will be ON in 10uS, then echo pin will measure the time of ultrasound feedback. Distance is easily calculated by formula: time*speed


Step 2. Servo motor:
Servo motor SG90 also an easy part, it can rotate to exact angle appointed by code:
servo.write(servoAngle);
Note that servo motor SG90 can run only from 0 to 120 degree.


Step 3. Hardware installation & circuit
Use MDF 3mm, cut out by laser cut to make base for sensor, then connect to servo motor


Step 4. Arduino code
#include <Servo.h>
 
const int servoPin = 9;
const int trigPin = 17;  //ultrasonic
const int echoPin = 16;  //ultrasonic
 
Servo servo;  
 
int servoAngle = 0;   // servo position in degrees
long duration;
int distance;
 
void setup()
{
  pinMode(trigPin, OUTPUT); // Sets the trigPin as an Output
  pinMode(echoPin, INPUT); // Sets the echoPin as an Input
  Serial.begin(9600);  
  servo.attach(servoPin);
}
 
 
void loop()
{
  // Clears the trigPin, ultrasonic
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);

  for(servoAngle = 120; servoAngle > 0; servoAngle--)  //now move back the micro servo from 120 degrees to 0 degrees
  {                                
    servo.write(servoAngle);
    delay(20);
    
    // Sets the trigPin on HIGH state for 10 micro seconds
    digitalWrite(trigPin, HIGH);
    delayMicroseconds(10);
    digitalWrite(trigPin, LOW);
    // Reads the echoPin, returns the sound wave travel time in microseconds
    duration = pulseIn(echoPin, HIGH, 23529); //23529us for timeout 4.0m

    // Calculating the distance
    distance= duration*0.034/2;
    Serial.print("servoAngle (dg): ");
    if (servoAngle <10) Serial.print("0");
    if (servoAngle <100) Serial.print("0");
    Serial.print(servoAngle);
    Serial.print(" ");
    Serial.print("Distance (cm): ");
    if (distance <10) Serial.print("0");
    if (distance <100) Serial.print("0");
    if (distance <1000) Serial.print("0");
    Serial.println(distance);
    
  }

  for(servoAngle = 0; servoAngle < 120; servoAngle++)  //now move back the micro servo from 0 degrees to 120 degrees
  {                                
    servo.write(servoAngle);
    delay(20);
    
    // Sets the trigPin on HIGH state for 10 micro seconds
    digitalWrite(trigPin, HIGH);
    delayMicroseconds(10);
    digitalWrite(trigPin, LOW);
    // Reads the echoPin, returns the sound wave travel time in microseconds
    duration = pulseIn(echoPin, HIGH, 23529); //23529us for timeout 4.0m

    // Calculating the distance
    distance= duration*0.034/2;
    Serial.print("servoAngle (dg): ");
    if (servoAngle <10) Serial.print("0");
    if (servoAngle <100) Serial.print("0");
    Serial.print(servoAngle);
    Serial.print(" ");
    Serial.print("Distance (cm): ");
    if (distance <10) Serial.print("0");
    if (distance <100) Serial.print("0");
    if (distance <1000) Serial.print("0");
    Serial.println(distance);
    
  }
}
In sort, the code will rotate sensor from 120 to 0 degree, then return. During rotating, it measure distance to object and send data to computer via COM Port

Step 5. Visual Studio code
private: System::Void Form1_Load(System::Object^  sender, System::EventArgs^  e) {
     serialPort1->Open();
     timer1->Start();
     mStr = "";
     r = 10;
     distance = gcnew array< Int32 >(360);
  }
 private: System::Void serialPort1_DataReceived(System::Object^  sender, System::IO::Ports::SerialDataReceivedEventArgs^  e) {
     try {
      mStr=serialPort1->ReadLine();
     }
     catch (IO::IOException^ e){
      //do nothing. This try-catch to prvent error 
      //when close program while receiving data from COM-port
     }
     
     if(mStr->Length >= 41)
     {
      if(mStr->Substring(0,10) == "servoAngle"){
       distance[Convert::ToInt32(mStr->Substring(17,3))+30] = Convert::ToInt32(mStr->Substring(36,4));
       current_pos = Convert::ToInt32(mStr->Substring(17,3))+30;
      }
     }
    }
 private: System::Void timer1_Tick(System::Object^  sender, System::EventArgs^  e) {
     Graphics^ g = pictureBox1->CreateGraphics();
     g->Clear(Color::WhiteSmoke);
     Pen^ redPen = gcnew Pen(Color::Red);
     redPen->Width = 2;
     Pen^ bluPen = gcnew Pen(Color::Blue);
     bluPen->Width = 5;
     Pen^ grePen = gcnew Pen(Color::Green);
     grePen->Width = 2;
     int x = 400; //x-axis of center
     int y = 50; //y-axis of center

     g->DrawLine(grePen, x-300, y, x+300, y);
     g->DrawArc(grePen, x-300, y-300, 600, 600, 0, 180);
     g->DrawArc(grePen, x-150, y-150, 300, 300, 0, 180);
     g->DrawArc(grePen, x-75, y-75, 150, 150, 0, 180);
     g->DrawArc(grePen, x-37, y-37, 75, 75, 0, 180);
       
     for (i = 30; i<150; i++)
     {
      r = distance[i];
      if (r<=0) r=300;
      if (i!=current_pos){
       g->DrawLine(redPen, x, y, x+r*Math::Cos(i*3.1416/180), y+r*Math::Sin(i*3.1416/180));
      }
      else{
       g->DrawLine(bluPen, x, y, x+r*Math::Cos(i*3.1416/180), y+r*Math::Sin(i*3.1416/180));
      }
      label5->Text="Angle: "+current_pos+" degree";
      if (distance[current_pos]>0){
       label6->Text="Distance: "+distance[current_pos]+" cm";
      }
      else{
       label6->Text="Distance: 300 cm";
      }
     } 
    }

Entire code can be found here (google share link)


Result video 


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