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I am making a simple Arduino based radar project. The complete details of the project can be found on YouTube. The circuit consists of an HC SR04 sensor ,a servo motor, an arduino UNO R3 connected as shown in the schematic. However I am facing two issues:

  1. The servo motor does not run as smoothly as illustrated.
  2. It stops briefly at each degree.
  3. The sensor I am using does not pick up an objects on the display of processing.enter image description here

What can I do to remove these two problems?

PS:I am using an old servomotor and HC SR04 sensor. If that could be the cause of the problem, I can get new ones but if its some code related issue. Please let me know.

Also ignore the compim connections here. They are absent in the actual circuit and are only used for simulation. Arduino 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;
}

Processing IDE code:

    import processing.serial.*; // imports library for serial communication
import java.awt.event.KeyEvent; // imports library for reading the data from the serial port
import java.io.IOException;
Serial myPort; // defines Object Serial
// 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 (1200, 700); // ***CHANGE THIS TO YOUR SCREEN RESOLUTION***
 smooth();
 myPort = new Serial(this,"COM5", 9600); // starts the serial communication
 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("Indian Lifehacker ", width-width*0.875, height-height*0.0277);
  text("Angle: " + iAngle +" °", width-width*0.48, height-height*0.0277);
  text("Distance: ", width-width*0.26, 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(); 
}
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  • \$\begingroup\$ I suspect few people will be willing to watch the video. It might be a good idea to provide a more thorough explanation here. Also, is it sonar or radar? They are not the same thing. Don't answer in the comments. Edit your question to include the requested information. \$\endgroup\$
    – user57037
    Commented Jan 1, 2022 at 10:02
  • \$\begingroup\$ Welcome to EE.SE, but not many of us are going to watch a video for you. Instead, please edit your question to include a circuit schematic and properly formatted, indented and commented code (use the {} code formatting button). Add datasheet link for the sensor (using the link button). \$\endgroup\$
    – Transistor
    Commented Jan 1, 2022 at 10:03
  • \$\begingroup\$ I have already added all the information that i could now. \$\endgroup\$ Commented Jan 1, 2022 at 10:11
  • \$\begingroup\$ it's not radar if it does not use radio waves \$\endgroup\$
    – jsotola
    Commented Jan 1, 2022 at 20:15
  • \$\begingroup\$ It's called SONAR..... for sonic activated response. \$\endgroup\$ Commented Jan 1, 2022 at 23:24

2 Answers 2

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For the US distance sensor part, @Transistor already found the problem.

For the servo part, I see a few things :

  1. in your code, you have a "delay(30)" : you need some delay for the servo to reach it's position, but if the delay is too long, the motor will stop for the remaining time. However, as the delay is only 30ms, I think it's a bit too short to notice
  2. in adition, there is the time of executing the calculateDistance() function : this duration is variable (it depends mainly on the time you need to get the US wave back) : in normal operation, it should be a few milliseconds, up to a few tens of milliseconds.
  3. currently, you have no echo signal at all (because you inverted the pins), so you will have no pulse detected by the pulseIn function, which results in a default timeout of 1s : that might well explain the small stops
  4. once point 3 solved, you will still have the case where there is no obstacle nearby (obstacles out of range), and there is therefore no wave gooing back to the sensor : I haven't found what's the sensors behaviour : either there is no echo at all (then it's up to you to set a timeout shorter than 1s for pulseIn function), or there is a default "error pulse". According to this library implementation, I would say the first option is far more likely (nb : it is based on HC-SR04 as on your schematics, I haven't found any information about a HC SR 304 as in your text)

So if I were you, I would start correcting the pins, and see if the servo runs smoothly. Then check if when there is no obstacle in range, it is still smooth : if it is no longer, then it's probably point 4 you need to solve the issue

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  • \$\begingroup\$ I know i am quite late in my reply but the problem was in my breadboard. I never realized it but the connections in breadboard. Replacing the breadboard fixed the problem immediately. Thanks for the help though \$\endgroup\$ Commented Feb 27, 2022 at 9:24
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Your code shows:

const int trigPin = 10;
const int echoPin = 11;

Your schematic shows the opposite:

enter image description here

Note that by moving U1 up a bit you could have avoided multiple wire crossovers and made the schematic much easier to read. That would have helped you spot the problem.

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