Radar com Ping e Processing

Neste post estou mostrando minha adaptação do trabalho do Luckylarry para uso com o sensor ping ao invés do SRF-05.

Ao Lado  o sensor da Seeedstudio que é uma versão do sensor ping da Parallax, este sensor funciona baseado na emissão e captação de sinais sonoros.

O pricípio de funcionamento é a relação de tempo entre a emissão e a captação do som, baseado no fato de que o som tem uma velocidade constante é possível calcular a distância quando o intervalo entre a emissão e a captação é conhecido.

A montagem do sistema utiliza as seguintes portas do arduino:

 - Digital 7 para o sensor ping
 - Digital 9 (pmw) para o servo

Os dados recebidos no arduino na porta 7 são pulsos eletrícos que são convertidos em medidas de distância por uma formula simples e enviados para a porta serial para processamento do Processing.

A fórmula de conversão é baseada no fato de que  velocidade do som é de 340 m/s ou 29 microssegundos por centímetro, logo se o sinal do sensor (pulsos em microssegundos) for dividido por 29 e depois novamente dividido por 2 ( o som é emitido e volta por isso temos que dividir por 2) teremos a distância em centimetros: microseconds / 29 / 2.









Foram necessárias poucas mudanças no código do arduino, o do processing é igual.

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Código Arduino:

/*
ARDUINO - RADAR COM PING E PROCESSING
ADAPTADO POR CLÁUDIO MIKLOS - WWW.MIKLOS.BLOG.BR - PARA USO COM SENSOR PING
CERDITOS ORIGINAIS:
luckylarry.co.uk
Radar Screen Visualisation for SRF-05
Sends sensor readings for every degree moved by the servo
values sent to serial port to be picked up by Processing
*/

#include <Servo.h>             // include the standard servo library
Servo leftRightServo;         // set a variable to map the servo
int leftRightPos = 0;         // set a variable to store the servo position
const int numReadings = 10;   // set a variable for the number of readings to take
int index = 0;                // the index of the current reading
int total = 0;                // the total of all readings
int average = 0;              // the average
int pingPin = 7;              // the PING pin
unsigned long duration = 0;  // variable for reading the pulse
unsigned long distance = 0;   // variable for storing distance
 
/* setup the pins, servo and serial port */
void setup() {
  leftRightServo.attach(9);
  Serial.begin(9600);
}
 
/* begin rotating the servo and getting sensor values */
void loop() {
  for(leftRightPos = 0; leftRightPos < 180; leftRightPos++) {  // going left to right.
    leftRightServo.write(leftRightPos);
      for (index = 0; index<=numReadings;index++) {            // take x number of readings from the sensor and average them
  pinMode(pingPin, OUTPUT);
  digitalWrite(pingPin, LOW);
  delayMicroseconds(2);
  digitalWrite(pingPin, HIGH);
  delayMicroseconds(5);
  digitalWrite(pingPin, LOW);
  pinMode(pingPin, INPUT);
  duration = pulseIn(pingPin, HIGH);
        distance = duration / 29 / 2;                            // convert to centimetres
        total = total + distance;                              // update total
        delay(10);
      }
    average = total/numReadings;                               // create average reading
 
    if (index >= numReadings)  {                               // reset the counts when at the last item of the array
      index = 0;
      total = 0;
    }
    Serial.print("X");                                         // print leading X to mark the following value as degrees
    Serial.print(leftRightPos);                                // current servo position
    Serial.print("V");                                         // preceeding character to separate values
    Serial.println(average);                                   // average of sensor readings
  }
  /*
  start going right to left after we got to 180 degrees
  same code as above
  */
  for(leftRightPos = 180; leftRightPos > 0; leftRightPos--) {  // going right to left
    leftRightServo.write(leftRightPos);
    for (index = 0; index<=numReadings;index++) {
  pinMode(pingPin, OUTPUT);
  digitalWrite(pingPin, LOW);
  delayMicroseconds(2);
  digitalWrite(pingPin, HIGH);
  delayMicroseconds(5);
  digitalWrite(pingPin, LOW);
  pinMode(pingPin, INPUT);
  duration = pulseIn(pingPin, HIGH);
        distance = duration / 29 / 2;                            // convert to centimetres
        total = total + distance;                              // update total
      delay(10);
    }
    average = total/numReadings;
    if (index >= numReadings)  {
      index = 0;
      total = 0;
    }
    Serial.print("X");
    Serial.print(leftRightPos);
    Serial.print("V");
    Serial.println(average);

   }

}

------------------------------------------------------------------------

Código Processing

/*
ARDUINO - RADAR COM PING E PROCESSING
ADAPTADO POR CLÁUDIO MIKLOS - WWW.MIKLOS.BLOG.BR - PARA USO COM SENSOR PING
CERDITOS ORIGINAIS:
luckylarry.co.uk
Radar Screen Visualisation for SRF-05
Maps out an area of what the SRF-05 sees from a top down view.
Takes and displays 2 readings, one left to right and one right to left.
Displays an average of the 2 readings
Displays motion alert if there is a large difference between the 2 values.
*/
import processing.serial.*;     // import serial library
Serial arduinoport;                  // declare a serial port
float x, y;                       // variable to store x and y co-ordinates for vertices   
int radius = 350;               // set the radius of objects
int w = 300;                    // set an arbitary width value
int degree = 0;                 // servo position in degrees
int value = 0;                  // value from sensor
int motion = 0;                 // value to store which way the servo is panning
int[] newValue = new int[181];  // create an array to store each new sensor value for each servo position
int[] oldValue = new int[181];  // create an array to store the previous values.
PFont myFont;                   // setup fonts in Processing
int radarDist = 0;              // set value to configure Radar distance labels
int firstRun = 0;               // value to ignore triggering motion on the first 2 servo sweeps

/* create background and serial buffer */
void setup(){
// setup the background size, colour and font.
size(750, 450);
background (0); // 0 = black
myFont = createFont("verdana", 12);
textFont(myFont);
// setup the serial port and buffer
arduinoport = new Serial(this, Serial.list()[0], 9600);

}

/* draw the screen */
void draw(){
fill(0);                              // set the following shapes to be black
noStroke();                           // set the following shapes to have no outline
ellipse(radius, radius, 750, 750);    // draw a circle with a width/ height = 750 with its center position (x and y) set by the radius
rectMode(CENTER);                     // set the following rectangle to be drawn around its center
rect(350,402,800,100);                // draw rectangle (x, y, width, height)
if (degree >= 179) {                  // if at the far right then set motion = 1/ true we're about to go right to left
motion = 1;                         // this changes the animation to run right to left
}
if (degree <= 1) {                    // if servo at 0 degrees then we're about to go left to right
motion = 0;                         // this sets the animation to run left to right
}
/* setup the radar sweep */
/* 
We use trigonmetry to create points around a circle.
So the radius plus the cosine of the servo position converted to radians
Since radians 0 start at 90 degrees we add 180 to make it start from the left
Adding +1 (i) each time through the loops to move 1 degree matching the one degree of servo movement
cos is for the x left to right value and sin calculates the y value
since its a circle we plot our lines and vertices around the start point for everything will always be the center.
*/
strokeWeight(7);                      // set the thickness of the lines
if (motion == 0) {                    // if going left to right
for (int i = 0; i <= 20; i++) {     // draw 20 lines with fading colour each 1 degree further round than the last
stroke(0, (10*i), 0);             // set the stroke colour (Red, Green, Blue) base it on the the value of i
line(radius, radius, radius + cos(radians(degree+(180+i)))*w, radius + sin(radians(degree+(180+i)))*w); // line(start x, start y, end x, end y)
}
} else {                              // if going right to left
for (int i = 20; i >= 0; i--) {     // draw 20 lines with fading colour
stroke(0,200-(10*i), 0);          // using standard RGB values, each between 0 and 255
line(radius, radius, radius + cos(radians(degree+(180+i)))*w, radius + sin(radians(degree+(180+i)))*w);
}
}
/* Setup the shapes made from the sensor values */
noStroke();                           // no outline
/* first sweep */
fill(0,50,0);                         // set the fill colour of the shape (Red, Green, Blue)
beginShape();                         // start drawing shape
for (int i = 0; i < 180; i++) {     // for each degree in the array
x = radius + cos(radians((180+i)))*((oldValue[i])); // create x coordinate
y = radius + sin(radians((180+i)))*((oldValue[i])); // create y coordinate
vertex(x, y);                     // plot vertices
}
endShape();                           // end shape
/* second sweep */
fill(0,110,0);
beginShape();
for (int i = 0; i < 180; i++) {
x = radius + cos(radians((180+i)))*(newValue[i]);
y = radius + sin(radians((180+i)))*(newValue[i]);
vertex(x, y);
}
endShape();
/* average */
fill(0,170,0);
beginShape();
for (int i = 0; i < 180; i++) {
x = radius + cos(radians((180+i)))*((newValue[i]+oldValue[i])/2); // create average
y = radius + sin(radians((180+i)))*((newValue[i]+oldValue[i])/2);
vertex(x, y);
}
endShape();
/* if after first 2 sweeps, highlight motion with red circle*/
if (firstRun >= 360) {
stroke(150,0,0);
strokeWeight(1);
noFill();
for (int i = 0; i < 180; i++) {
if (oldValue[i] - newValue[i] > 35 || newValue[i] - oldValue[i] > 35) {
x = radius + cos(radians((180+i)))*(newValue[i]);
y = radius + sin(radians((180+i)))*(newValue[i]);
ellipse(x, y, 10, 10); 
}
}
}
/* set the radar distance rings and out put their values, 50, 100, 150 etc.. */
for (int i = 0; i <=6; i++){
noFill();
strokeWeight(1);
stroke(0, 255-(30*i), 0);
ellipse(radius, radius, (100*i), (100*i)); 
fill(0, 100, 0);
noStroke();
text(Integer.toString(radarDist+50), 380, (305-radarDist), 50, 50);
radarDist+=50;
}
radarDist = 0;
/* draw the grid lines on the radar every 30 degrees and write their values 180, 210, 240 etc.. */
for (int i = 0; i <= 6; i++) {
strokeWeight(1);
stroke(0, 55, 0);
line(radius, radius, radius + cos(radians(180+(30*i)))*w, radius + sin(radians(180+(30*i)))*w);
fill(0, 55, 0);
noStroke();
if (180+(30*i) >= 300) {
text(Integer.toString(180+(30*i)), (radius+10) + cos(radians(180+(30*i)))*(w+10), (radius+10) + sin(radians(180+(30*i)))*(w+10), 25,50);
} else {
text(Integer.toString(180+(30*i)), radius + cos(radians(180+(30*i)))*w, radius + sin(radians(180+(30*i)))*w, 60,40);
}
}
/* Write information text and values. */
noStroke();
fill(0);
rect(350,402,800,100);
fill(0, 100, 0);
text("Degrees: "+Integer.toString(degree), 100, 380, 100, 50);         // use Integet.toString to convert numeric to string as text() only outputs strings
text("Distance: "+Integer.toString(value), 100, 400, 100, 50);         // text(string, x, y, width, height)
text("Radar screen code at luckylarry.co.uk", 540, 380, 250, 50);
fill(0);
rect(70,60,150,100);
fill(0, 100, 0); 
text("Screen Key:", 100, 50, 150, 50);
fill(0,50,0);
rect(30,53,10,10);
text("First sweep", 115, 70, 150, 50);
fill(0,110,0);
rect(30,73,10,10);
text("Second sweep", 115, 90, 150, 50);
fill(0,170,0);
rect(30,93,10,10);
text("Average", 115, 110, 150, 50);
noFill();
stroke(150,0,0);
strokeWeight(1);
ellipse(29, 113, 10, 10); 
fill(150,0,0);
text("Motion", 115, 130, 150, 50);
}

/* get values from serial port */
void serialEvent (Serial arduinoport) {
String xString = arduinoport.readStringUntil('\n');  // read the serial port until a new line
if (xString != null) {  // if theres data in between the new lines
xString = trim(xString); // get rid of any whitespace just in case
String getX = xString.substring(1, xString.indexOf("V")); // get the value of the servo position
String getV = xString.substring(xString.indexOf("V")+1, xString.length()); // get the value of the sensor reading
degree = Integer.parseInt(getX); // set the values to variables
value = Integer.parseInt(getV);
oldValue[degree] = newValue[degree]; // store the values in the arrays.
newValue[degree] = value;  
/* sets a counter to allow for the first 2 sweeps of the servo */
firstRun++;
if (firstRun > 360) {
firstRun = 360; // keep the value at 360 
}
}
}