5 июня 2014 г.

Датчик цвета из RGB-светодиода и фотоэлемента - реальная фотошоповская пипетка

(c) RoboCraft

Про самодельный датчик цвета мы уже писали, так что идея использовать RGB-светодиода (или нескольких цветных светодиодов) для поочерёдного освещения объекта и считывания на фоторезисторе напряжения с последующим выбором наилучшего отклика — не нова.
Однако, попытка сделать реальную «фотошоповскую пипетку» (Eyedropper) продолжает ждать своего воплощения :) 

real world eyedropper: color sensing for the arduino
код для Arduino:
// Define colour sensor LED pins
int ledArray[] = {2,3,4};
// boolean to know if the balance has been set
boolean balanceSet = false;
//place holders for colour detected
int red = 0;
int green = 0;
int blue = 0;
//floats to hold colour arrays
float colourArray[] = {0,0,0};
float whiteArray[] = {0,0,0};
float blackArray[] = {0,0,0};

//place holder for average
int avgRead;
void setup(){
 
  //setup the outputs for the colour sensor
  pinMode(2,OUTPUT);
  pinMode(3,OUTPUT);
  pinMode(4,OUTPUT);
 
  //begin serial communication
  Serial.begin(9600);
 }
void loop(){

    checkBalance();
    checkColour();
    printColour();
    }
void checkBalance(){
  //check if the balance has been set, if not, set it
  if(balanceSet == false){
    setBalance();
  }
}
void setBalance(){
  //set white balance
   delay(5000);                              //delay for five seconds, this gives us time to get a white sample in front of our sensor
  //scan the white sample.
  //go through each light, get a reading, set the base reading for each colour red, green, and blue to the white array
  for(int i = 0;i<=2;i++){
     digitalWrite(ledArray[i],HIGH);
     delay(100);
     getReading(5);          //number is the number of scans to take for average, this whole function is redundant, one reading works just as well.
     whiteArray[i] = avgRead;
     digitalWrite(ledArray[i],LOW);
     delay(100);
  }
  //done scanning white, now it will pulse blue to tell you that it is time for the black (or grey) sample.
   //set black balance
    delay(5000);              //wait for five seconds so we can position our black sample 
  //go ahead and scan, sets the colour values for red, green, and blue when exposed to black
  for(int i = 0;i<=2;i++){
     digitalWrite(ledArray[i],HIGH);
     delay(100);
     getReading(5);
     blackArray[i] = avgRead;
     //blackArray[i] = analogRead(2);
     digitalWrite(ledArray[i],LOW);
     delay(100);
  }
   //set boolean value so we know that balance is set
  balanceSet = true;
  //delay another 5 seconds to allow the human to catch up to what is going on
  delay(5000);
  }
void checkColour(){
    for(int i = 0;i<=2;i++){
     digitalWrite(ledArray[i],HIGH);  //turn or the LED, red, green or blue depending which iteration
     delay(100);                      //delay to allow CdS to stabalize, they are slow
     getReading(5);                  //take a reading however many times
     colourArray[i] = avgRead;        //set the current colour in the array to the average reading
     float greyDiff = whiteArray[i] - blackArray[i];                    //the highest possible return minus the lowest returns the area for values in between
     colourArray[i] = (colourArray[i] - blackArray[i])/(greyDiff)*255; //the reading returned minus the lowest value divided by the possible range multiplied by 255 will give us a value roughly between 0-255 representing the value for the current reflectivity(for the colour it is exposed to) of what is being scanned
     digitalWrite(ledArray[i],LOW);   //turn off the current LED
     delay(100);
  }
}
void getReading(int times){
  int reading;
  int tally=0;
  //take the reading however many times was requested and add them up
for(int i = 0;i < times;i++){
   reading = analogRead(0);
   tally = reading + tally;
   delay(10);
}
//calculate the average and set it
avgRead = (tally)/times;
}
//prints the colour in the colour array, in the next step, we will send this to processing to see how good the sensor works.
void printColour(){
Serial.print("R = ");
Serial.println(int(colourArray[0]));
Serial.print("G = ");
Serial.println(int(colourArray[1]));
Serial.print("B = ");
Serial.println(int(colourArray[2]));
//delay(2000);
}

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