fizikai számítástechnika, arduino

A digitális giroszkóp egy 3d-s gyorsulásérzékelő chip. A Föld mágneses pólusait (Észak, Dél) érzékeli és abból számolja az elmozdulást. Ebben a példában a dölés szöget és az mozdulat sebességét tudjuk kiolvasni serial monitoron.

A tinkerkit library-t is telepíteni kel hozzá, innen:
http://tinkerkit.com/en/Tutorials/Home

Hivatkozások:

TKGyro gyro(I0,I1,TK_4X);gyro.getXAxis();
//x tengely értéke 0-1023gyro.getYAxis();
//y tengely értéke 0-1023gyro.getXAxisRate();
//x tengely fizikai helyzete: -6000°/s-tól 6000°/s-iggyro.getYAxisRate();
//y tengely fizikai helyzete: -6000°/s-tól 6000°/s-ig

TinkerKit Gyroscope 2 Axis sensitivity 1X

Bekötése:

x tengely A0

y tengely A1

+ pinek 5V-ba mindkettő

- pinek Gnd-be mindkettő

Arduino kód a hivatalos Manual-ból:

/* TinkerKit! Gyroscope [T000060-64]
 *
 * This sketch shows how to read this 2-axis gyroscope, 
 * turning in a given angular velocity and then converting it 
 * in the simplest way in an angular position (/inclination).
 *
 * Connect: the X-axis to the Analog Input Pin 0 (I0) 
 *          the Y-axis to the Analog Input Pin 1 (I1)
 * Optional: connect a servo to Analog Output Pin 9 (O2)
 *
 * created by Federico Vanzati / f.vanzati@arduino.cc
 * in September 2011
 *
 * inspired from www.arduino.cc/playground/Main/Gyro 
 * by eric barch / ericbarch.com
 */

#include <Servo.h> 

// Pin used in this example
#define SERVO 9
#define X_GYRO 0
#define Y_GYRO 1

#define ADCresolution 4.89f  // = 5000mV/1023counts: Arduino analog pins resolution expressed in mV/count
#define Sensitivity 0.67f  // [mV/dps] sensitivity of the sensor, took from datasheet (4x output mode)
// Conversion coefficient, we do here because is a constant! so we'll not do the calculation every loop
#define K ADCresolution/Sensitivity  // the constant!
#define nrSamples 6  // Number of samples that we take for each measure

Servo myservo;  // create servo object to control a servo 
// a maximum of eight servo objects can be created 

// Timing variables
unsigned long  time, sampleTime = 12; 
unsigned long printTime = 0, serialRefresh_time = 500; 
float deltaT = (float)sampleTime*nrSamples/1000;

//Gyroscope variables  
int roll_zeroVoltage, pitch_zeroVoltage;    
int roll_rawADC[nrSamples], pitch_rawADC[nrSamples];  // store 3 values...just to avverage
float roll_rate, pitch_rate;  //
float roll_angle = 0, pitch_angle = 0;
int c=0;  // just a counter to count the samples

int pos;    // variable to store the servo position

void setup() 
{ 
  delay(1000); 
  myservo.attach(SERVO);  // attaches the servo on pin 9 to the servo object 
  myservo.write(pos);

  Serial.begin(57600);
  Serial.print("TinkerKit! Gyroscope [T000062] Test Example\n\n");

  int correctionY=0, correctionX=0;

  for (int i=0; i<50; i++)
  {
    correctionY += analogRead(Y_GYRO);
    correctionX += analogRead(X_GYRO);
    delay(20);
  }
  roll_zeroVoltage = correctionY/50;
  pitch_zeroVoltage = correctionX/50;
  Serial.print(roll_zeroVoltage);
  Serial.print("    ");
  Serial.println(pitch_zeroVoltage);

  time = millis();
} 


void loop() 
{ 
  // Every 40ms take a sample from gyro
  if(millis() - time > sampleTime)
  {
    time = millis();   
    roll_rawADC[c] = analogRead(Y_GYRO);
    pitch_rawADC[c] = analogRead(X_GYRO);
    c++;
  }
  if(c==nrSamples) // Well, we have 3 samples
  {
    // Transform the raw data into an angular velocity
    roll_rate = (filterGyro(roll_rawADC) - roll_zeroVoltage) * K;
    pitch_rate = (filterGyro(pitch_rawADC) - pitch_zeroVoltage)*K;

    // Integrate the angular veloity to obtain angular position (or inclination)
    // Using the trapeziod method for numerical integration
    //                                                                 sampleTime*nrSamples
    // The variable that take mind of the integration time is deltaT = -------------------- 
    //                                                                         1000
    //  - we multiply for nrSamples because  
    //  - divide for 1000 because angular velocity is expessed in seconds,
    //    but sampleTime is expressed in milliseconds
    roll_angle += roll_rate*deltaT/2;
    pitch_angle += pitch_rate*deltaT/2;

    //Keep our angle between 0-359 degrees
    if (roll_angle < 0)
      roll_angle += 360;
    else if (roll_angle > 359)
      roll_angle -= 360;

    if (pitch_angle < 0)
      pitch_angle += 360;
    else if (pitch_angle > 359)
      pitch_angle -= 360;

    // Now we control the servo: home position is setted in the center at 90 degrees
    if(roll_angle >= 0 && roll_angle <= 90) // counterclockwise rotation of the gyro...
      pos = 90 + (int)roll_angle;           // ...produces rotation from 90 to 180 deg on servo                     
    if(roll_angle >= 270)                   // clockwike rotation of the gyro...
      pos = (int)roll_angle - 270;          // ...produces rotation from 90 to 0 deg on servo

    myservo.write(pos);  // send the position to servo

    if(millis() - printTime > serialRefresh_time)
    {
      printTime = millis();
      Serial.print("Roll speed: "); Serial.print((int)roll_rate);
      Serial.print("\t Angle: "); Serial.print((int)roll_angle);
      Serial.print("\t Pitch speed: ");Serial.print((int)pitch_rate);
      Serial.print("\t Angle: ");Serial.println((int)pitch_angle);
      Serial.print("Servo: "); Serial.println(pos);
    }
    c=0;  // reset the counter
  }
}

int filterGyro(int buffer[])
{
  int mean=0;
  for(byte i=0; i<nrSamples; i++)
    mean += buffer[i];
  mean /= nrSamples;
  return mean;
}
 

Egy példa, grafikus interfész processingben, ami a giró adatait mutatja: http://scuola.arduino.cc/en/content/realizziamo-uninterfaccia-grafica-modulo-giroscopio-tinkerkit 

forrás

http://www.tinkerkit.com/bp/reference/, http://tinkerkit.com/en/Tutorials/Home, http://sensorwiki.org/doku.php/sensors/gyroscope