//ines (233 sloc)  9.04 KB
// Arduino Wire library is required if I2Cdev I2CDEV_ARDUINO_WIRE implementation
// is used in I2Cdev.h
#include "Wire.h"

// I2Cdev and MPU6050 must be installed as libraries, or else the .cpp/.h files
// for both classes must be in the include path of your project
#include "I2Cdev.h"
#include "MPU6050.h"

// class default I2C address is 0x68
// specific I2C addresses may be passed as a parameter here
// AD0 low = 0x68 (default for InvenSense evaluation board)
// AD0 high = 0x69
MPU6050 accelgyro;

int16_t ax, ay, az;
int16_t gx, gy, gz;
int16_t mx, my, mz;

// System constants
#define LED_PIN 13

//fusion
float deltat = 0.001f;
float lastt = 0;
float ct = 0;
float l = 0;

float gyroMeasError = 0; //3.14159265358979 * (0 / 180); 
float gyroMeasDrift = 0; 
float beta = sqrt(3.0 / 4.0) * gyroMeasError;
float zeta = sqrt(3.0 / 4.0) * gyroMeasDrift;
int b = 0;
// Global system variables 
float a_x, a_y, a_z;
float w_x, w_y, w_z;

float m_x, m_y, m_z;
float SEq_1 = 1, SEq_2 = 0, SEq_3 = 0, SEq_4 = 0; 
float b_x = 1, b_z = 0;
float w_bx = 0, w_by = 0, w_bz = 0;

// Local system variables
// end fusion
bool blinkState = false;

void setup() {
  // join I2C bus (I2Cdev library doesn't do this automatically)
  Wire.begin();

  // initialize serial communication
  // (38400 chosen because it works as well at 8MHz as it does at 16MHz, but
  // it's really up to you depending on your project)
  Serial.begin(38400);

  // initialize device
  Serial.println("Initializing I2C devices...");
  accelgyro.initialize();
        accelgyro.setFullScaleGyroRange(1); //set range to +-500°/s
        accelgyro.setFullScaleAccelRange(0); //set range to +-2g

  // verify connection
  Serial.println("Testing device connections...");
  Serial.println(accelgyro.testConnection() ? "MPU6050 connection successful" : "MPU6050 connection failed");

  // configure Arduino LED for
  pinMode(LED_PIN, OUTPUT);
}

float n2R(int n, float intercept) { // number to degrees
  float deg = ((n/32768.0) * 500.0 + intercept);
  if (abs(deg) < .3) {
    return 0;
  }
  return deg * (1/57.29578);
}

float n2g(int n) { // number to g-force // useless because we're looking at magnitude
  return n * 0.00006103515626;// 1/32768.0 * 2; 
}

double getPitch(double q0, double q1, double q2, double q3) {
  double top = 2*(q1*q3 + q0*q2);
  double bottom = sqrt(1-pow((2*q1*q3+2*q0*q2),2));
  return (-atan(top/bottom))*57.29578;
}

double getYaw(double q0, double q1, double q2, double q3) {
  double arg1 = 2*(q2*q3-q0*q1);
  double arg2 = 2*pow(q0,2) - 1 + 2*pow(q3,2);
  return atan2(arg1,arg2)*57.29578;
}

double getRoll(double q0, double q1, double q2, double q3) {
  double arg1 = 2*(q1*q2-q0*q3);
  double arg2 = 2*pow(q0,2) - 1 + 2*pow(q1,2);
  return atan2(arg1,arg2)*57.29578;
}

void loop() {
  // read raw accel/gyro measurements from device
  //if (accelgyro.testConnection()) {
    //if (b > 0) {
      accelgyro.getMotion9(&ax, &ay, &az, &gx, &gy, &gz, &mx, &my, &mz);
      ct = millis();
      deltat = (ct - lastt) * 0.001;
      Serial.print("p/y/r"); Serial.print("\t");
      Serial.print(ax); Serial.print("\t");
      Serial.print(ay); Serial.print("\t");
      Serial.print(az); Serial.print("\t");
      Serial.print("p/y/r"); Serial.print("\t");
      Serial.print(gx); Serial.print("\t");
      Serial.print(gy); Serial.print("\t");
      Serial.print(gz); Serial.print("\t");
      Serial.print("p/y/r"); Serial.print("\t");
      Serial.print(mx); Serial.print("\t");
      Serial.print(my); Serial.print("\t");
      Serial.println(mz);
      /*
      lastt = ct;
      float xR = n2R(gx, -0.926877914);
      float yR = n2R(gy, 0.758192);
      float zR = n2R(gz, 1.94250294);

      if (abs(zR) > abs(l)) {
        l = zR;
      }

      filterUpdate(xR, yR, zR, ax, ay, az, mx, my, mz);
      // if (b % 25 == 0) {
      double pitch = getPitch(SEq_1, SEq_2, SEq_3, SEq_4);
      double yaw = getYaw(SEq_1, SEq_2, SEq_3, SEq_4);
      double roll = getRoll(SEq_1, SEq_2, SEq_3, SEq_4);
      Serial.print("p/y/r"); Serial.print("\t");
      Serial.print(pitch); Serial.print("\t");
      Serial.print(yaw); Serial.print("\t");
      Serial.print(roll); Serial.print("\t");
            Serial.println(l * 180/3.14159);// Serial.print("\t");
    } else {
      lastt = millis();
    }

    b++;
    blinkState = !blinkState;
    digitalWrite(LED_PIN, blinkState);
  }
  else {
    Serial.println("MPU6050 connection failed");
  }*/
}

void filterUpdate(float w_x, float w_y, float w_z, float a_x, float a_y, float a_z, float m_x, float m_y, float m_z) {
  // local system variables
  float norm; // vector norm
  float SEqDot_omega_1, SEqDot_omega_2, SEqDot_omega_3, SEqDot_omega_4; // quaternion rate from gyroscopes elements // objective function elements
  float f_1, f_2, f_3, f_4, f_5, f_6; // objective function elements
  float J_11or24, J_12or23, J_13or22, J_14or21, J_32, J_33, 
  J_41, J_42, J_43, J_44, J_51, J_52, J_53, J_54, J_61, J_62, J_63, J_64; // objective function Jacobian elements
  float SEqHatDot_1, SEqHatDot_2, SEqHatDot_3, SEqHatDot_4;
  float w_err_x, w_err_y, w_err_z;
  float h_x, h_y, h_z;
  
  // axulirary variables to avoid repeated calculations
  float halfSEq_1 = 0.5f * SEq_1;
  float halfSEq_2 = 0.5f * SEq_2;
  float halfSEq_3 = 0.5f * SEq_3;
  float halfSEq_4 = 0.5f * SEq_4;
  float twoSEq_1 = 2.0f * SEq_1;
  float twoSEq_2 = 2.0f * SEq_2;
  float twoSEq_3 = 2.0f * SEq_3;
  float twoSEq_4 = 2.0f * SEq_4;
  float twob_x = 2.0f * b_x;
  float twob_z = 2.0f * b_z;

  float twob_xSEq_1 = 2.0f * b_x * SEq_1;
  float twob_xSEq_2 = 2.0f * b_x * SEq_2;
  float twob_xSEq_3 = 2.0f * b_x * SEq_3;
  float twob_xSEq_4 = 2.0f * b_x * SEq_4;
  float twob_zSEq_1 = 2.0f * b_z * SEq_1;
  float twob_zSEq_2 = 2.0f * b_z * SEq_2;
  float twob_zSEq_3 = 2.0f * b_z * SEq_3;
  float twob_zSEq_4 = 2.0f * b_z * SEq_4;

  float SEq_1SEq_2;
  float SEq_1SEq_3 = SEq_1 * SEq_3;
  float SEq_1SEq_4;
  float SEq_2SEq_3;
  float SEq_2SEq_4 = SEq_2 * SEq_4;
  float SEq_3SEq_4;
  float twom_x = 2.0f * m_x;
  float twom_y = 2.0f * m_y;
  float twom_z = 2.0f * m_z;

  norm = sqrt(a_x * a_x + a_y * a_y + a_z * a_z);
  a_x /= norm;
  a_y /= norm;
  a_z /= norm;

  // normalise the magnetometer measurement 
  norm = sqrt(m_x * m_x + m_y * m_y + m_z * m_z);
  m_x /= norm;
  m_y /= norm;
  m_z /= norm;

  // compute the objective function and Jacobian
  f_1 = twoSEq_2 * SEq_4 - twoSEq_1 * SEq_3 - a_x;
  f_2 = twoSEq_1 * SEq_2 + twoSEq_3 * SEq_4 - a_y;
  f_3 = 1.0f - twoSEq_2 * SEq_2 - twoSEq_3 * SEq_3 - a_z;
  f_4 = twob_x * (0.5f - SEq_3 * SEq_3 - SEq_4 * SEq_4) + twob_z * (SEq_2SEq_4 - SEq_1SEq_3) - m_x;
  f_5 = twob_x * (SEq_2 * SEq_3 - SEq_1 * SEq_4) + twob_z * (SEq_1 * SEq_2 + SEq_3 * SEq_4) - m_y;
  f_6 = twob_x * (SEq_1SEq_3 + SEq_2SEq_4) + twob_z * (0.5f - SEq_2 * SEq_2 - SEq_3 * SEq_3) - m_z;

  J_11or24 = twoSEq_3;
  J_12or23 = 2.0f * SEq_4;
  J_13or22 = twoSEq_1;

  J_14or21 = twoSEq_2;
  J_32 = 2.0f * J_14or21;
  J_33 = 2.0f * J_11or24;
  J_41 = twob_zSEq_3;
  J_42 = twob_zSEq_4;
  J_43 = 2.0f * twob_xSEq_3 + twob_zSEq_1;
  J_44 = 2.0f * twob_xSEq_4 - twob_zSEq_2;
  J_51 = twob_xSEq_4 - twob_zSEq_2;
  J_52 = twob_xSEq_3 + twob_zSEq_1;
  J_53 = twob_xSEq_2 + twob_zSEq_4;
  J_54 = twob_xSEq_1 - twob_zSEq_3;
  J_61 = twob_xSEq_3;
  J_62 = twob_xSEq_4 - 2.0f * twob_zSEq_2;
  J_63 = twob_xSEq_1 - 2.0f * twob_zSEq_3;
  J_64 = twob_xSEq_2;

  SEqHatDot_1 = J_14or21 * f_2 - J_11or24 * f_1 -J_41 * f_4 - J_51 * f_5 + J_61 * f_6;
  SEqHatDot_2 = J_12or23 * f_1 + J_13or22 * f_2 -J_32 * f_3 + J_42 * f_4 + J_52 * f_5 + J_62 * f_6;
  SEqHatDot_3 = J_12or23 * f_2 - J_33 * f_3 - J_13or22 * f_1 - J_43 * f_4 + J_53 * f_5 + J_63 * f_6;
  SEqHatDot_4 = J_14or21 * f_1 + J_11or24 * f_2 - J_44 * f_4 - J_54 * f_5 + J_64 * f_6;

  // normalise the gradient to estimate direction of the gyroscope error
  norm = sqrt(SEqHatDot_1 * SEqHatDot_1 + SEqHatDot_2 * SEqHatDot_2 + SEqHatDot_3 * SEqHatDot_3 + SEqHatDot_4 * SEqHatDot_4);

  SEqHatDot_1 = SEqHatDot_1 / norm;
  SEqHatDot_2 = SEqHatDot_2 / norm;
  SEqHatDot_3 = SEqHatDot_3 / norm;
  SEqHatDot_4 = SEqHatDot_4 / norm;

  w_err_x = twoSEq_1 * SEqHatDot_2 - twoSEq_2 * SEqHatDot_1 - twoSEq_3 * SEqHatDot_4 + twoSEq_4 * SEqHatDot_3;
  w_err_y = twoSEq_1 * SEqHatDot_3 + twoSEq_2 * SEqHatDot_4 - twoSEq_3 * SEqHatDot_1 - twoSEq_4 * SEqHatDot_2;
  w_err_z = twoSEq_1 * SEqHatDot_4 - twoSEq_2 * SEqHatDot_3 + twoSEq_3 * SEqHatDot_2 - twoSEq_4 * SEqHatDot_1;

  w_bx += w_err_x * deltat * zeta;
  w_by += w_err_y * deltat * zeta;
  w_bz += w_err_z * deltat * zeta;
  w_x -= w_bx;
  w_y -= w_by;
  w_z -= w_bz;

  SEqDot_omega_1 = -halfSEq_2 * w_x - halfSEq_3 * w_y - halfSEq_4 * w_z;
  SEqDot_omega_2 = halfSEq_1 * w_x + halfSEq_3 * w_z - halfSEq_4 * w_y;
  SEqDot_omega_3 = halfSEq_1 * w_y - halfSEq_2 * w_z + halfSEq_4 * w_x;
  SEqDot_omega_4 = halfSEq_1 * w_z + halfSEq_2 * w_y - halfSEq_3 * w_x;

  SEq_1 += (SEqDot_omega_1 - (beta *SEqHatDot_1)) * deltat;
  SEq_2 += (SEqDot_omega_2 - (beta *SEqHatDot_2)) * deltat;
  SEq_3 += (SEqDot_omega_3 - (beta *SEqHatDot_3)) * deltat;
  SEq_4 += (SEqDot_omega_4 - (beta *SEqHatDot_4)) * deltat;

  norm = sqrt(SEq_1 * SEq_1 + SEq_2 * SEq_2 + SEq_3 * SEq_3 + SEq_4 * SEq_4);
  SEq_1 /= norm;
  SEq_2 /= norm;
  SEq_3 /= norm;
  SEq_4 /= norm;

  // compute flux in the earth frame 
  SEq_1SEq_2 = SEq_1 * SEq_2;
  SEq_1SEq_3 = SEq_1 * SEq_3;
  SEq_1SEq_4 = SEq_1 * SEq_4;
  SEq_3SEq_4 = SEq_3 * SEq_4;
  SEq_2SEq_3 = SEq_2 * SEq_3;
  SEq_2SEq_4 = SEq_2 * SEq_4;

  h_x = twom_x * (0.5f - SEq_3 * SEq_3 - SEq_4 * SEq_4) + twom_y * (SEq_2SEq_3 - SEq_1SEq_4) + twom_z * (SEq_2SEq_4 + SEq_1SEq_3);
  h_y = twom_x * (SEq_2SEq_3 + SEq_1SEq_4) + twom_y * (0.5f - SEq_2 * SEq_2 - SEq_4 * SEq_4) + twom_z * (SEq_3SEq_4 - SEq_1SEq_2);
  h_z = twom_x * (SEq_2SEq_4 - SEq_1SEq_3) + twom_y * (SEq_3SEq_4 + SEq_1SEq_2) + twom_z * (0.5f - SEq_2 * SEq_2 - SEq_3 * SEq_3);
  
  // normalise the flux vector to have only components in the x and z 
  b_x = sqrt((h_x * h_x) + (h_y * h_y));
  b_z = h_z;
}