Yaw angle problem #284
Comments
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In addition , the quaternion code which I'm using is this: // Implementation of Sebastian Madgwick's "...efficient orientation filter #include "quaternionFilters.h" // These are the free parameters in the Mahony filter and fusion scheme, Kp static float GyroMeasError = PI * (40.0f / 180.0f); // Vector to hold integral error for Mahony method void MadgwickQuaternionUpdate(float ax, float ay, float az, float gx, float gy, float gz, float mx, float my, float mz, float deltat) // Auxiliary variables to avoid repeated arithmetic // Normalise accelerometer measurement // Normalise magnetometer measurement // Reference direction of Earth's magnetic field // Gradient decent algorithm corrective step // Compute rate of change of quaternion // Integrate to yield quaternion // Similar to Madgwick scheme but uses proportional and integral filtering on // Auxiliary variables to avoid repeated arithmetic // Normalise accelerometer measurement // Normalise magnetometer measurement // Reference direction of Earth's magnetic field // Estimated direction of gravity and magnetic field // Error is cross product between estimated direction and measured direction of gravity // Apply feedback terms // Integrate rate of change of quaternion // Normalise quaternion const float * getQ () { return q; } |
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The heading is undefined at pitch of 90 degrees.
Which direction is South when you are standing on the North Pole?
…On Fri, Jun 8, 2018 at 10:55 AM, polodealvarado ***@***.***> wrote:
Hi Kris.
First of all, thank you very much for this library, it has really helped
me.
I have a problem with my yaw angle. When the pitch or roll angle reach 90º
or -90º , the yaw angle changes taking an illogical value.
The magnetometor has been calibrated correctly, but I am not sure if the
problem comes form the filter or the yaw,pitch,roll calculation. My
coordinate system is this: (https://www.google.es/search?
q=mpu9250+coordinates&client=opera&hs=2vh&source=lnms&tbm=
isch&sa=X&ved=2ahUKEwj--fndwMTbAhWLQBQKHTZKB0MQ_
AUoAXoECAEQAw&biw=1650&bih=870#imgrc=oPcs2IW3wPfIbM:)
Thank you in advance.
/* MPU9250 Basic Example Code
by: Kris Winer
date: April 1, 2014
license: Beerware - Use this code however you'd like. If you
find it useful you can buy me a beer some time.
Modified by Brent Wilkins July 19, 2016
Demonstrate basic MPU-9250 functionality including parameterizing the
register
addresses, initializing the sensor, getting properly scaled accelerometer,
gyroscope, and magnetometer data out. Added display functions to allow
display
to on breadboard monitor. Addition of 9 DoF sensor fusion using open source
Madgwick and Mahony filter algorithms. Sketch runs on the 3.3 V 8 MHz Pro
Mini
and the Teensy 3.1.
SDA and SCL should have external pull-up resistors (to 3.3V).
10k resistors are on the EMSENSR-9250 breakout board.
Hardware setup:
MPU9250 Breakout --------- Arduino
VDD ---------------------- 3.3V
VDDI --------------------- 3.3V
SDA ----------------------- A4
SCL ----------------------- A5
GND ---------------------- GND
*/
#include "quaternionFilters.h"
#include "MPU9250.h"
#define AHRS true // Set to false for basic data read
#define SerialDebug true // Set to true to get Serial output for debugging
uint8_t Mmode = 0x06;
MPU9250 myIMU;
void setup()
{
Wire.begin();
// TWBR = 12; // 400 kbit/sec I2C speed
Serial.begin(115200);
// Read the WHO_AM_I register, this is a good test of communication
byte c = myIMU.readByte(MPU9250_ADDRESS, WHO_AM_I_MPU9250);
Serial.print("MPU9250 "); Serial.print("I AM "); Serial.print(c, HEX);
Serial.print(" I should be "); Serial.println(0x71, HEX);
if (c == 0x71) // WHO_AM_I should always be 0x68
{
Serial.println("MPU9250 is online...");
// Start by performing self test and reporting values
myIMU.MPU9250SelfTest(myIMU.SelfTest);
Serial.print("x-axis self test: acceleration trim within : ");
Serial.print(myIMU.SelfTest[0],1); Serial.println("% of factory value");
Serial.print("y-axis self test: acceleration trim within : ");
Serial.print(myIMU.SelfTest[1],1); Serial.println("% of factory value");
Serial.print("z-axis self test: acceleration trim within : ");
Serial.print(myIMU.SelfTest[2],1); Serial.println("% of factory value");
Serial.print("x-axis self test: gyration trim within : ");
Serial.print(myIMU.SelfTest[3],1); Serial.println("% of factory value");
Serial.print("y-axis self test: gyration trim within : ");
Serial.print(myIMU.SelfTest[4],1); Serial.println("% of factory value");
Serial.print("z-axis self test: gyration trim within : ");
Serial.print(myIMU.SelfTest[5],1); Serial.println("% of factory value");
// Calibrate gyro and accelerometers, load biases in bias registers
myIMU.calibrateMPU9250(myIMU.gyroBias, myIMU.accelBias);
myIMU.initMPU9250();
// Initialize device for active mode read of acclerometer, gyroscope, and
// temperature
Serial.println("MPU9250 initialized for active data mode....");
// Read the WHO_AM_I register of the magnetometer, this is a good test of
// communication
byte d = myIMU.readByte(AK8963_ADDRESS, WHO_AM_I_AK8963);
Serial.print("AK8963 "); Serial.print("I AM "); Serial.print(d, HEX);
Serial.print(" I should be "); Serial.println(0x48, HEX);
magcalMPU9250(myIMU.magCalibration,myIMU.magbias); // Hacerlo la primera vez para calibrarlo
// Get magnetometer calibration from AK8963 ROM
myIMU.initAK8963(myIMU.magCalibration);
// Initialize device for active mode read of magnetometer
Serial.println("AK8963 initialized for active data mode....");
if (SerialDebug)
{
// Serial.println("Calibration values: ");
Serial.print("X-Axis sensitivity adjustment value ");
Serial.println(myIMU.magCalibration[0], 2);
Serial.print("Y-Axis sensitivity adjustment value ");
Serial.println(myIMU.magCalibration[1], 2);
Serial.print("Z-Axis sensitivity adjustment value ");
Serial.println(myIMU.magCalibration[2], 2);
}
} // if (c == 0x71)
else
{
Serial.print("Could not connect to MPU9250: 0x");
Serial.println(c, HEX);
while(1) ; // Loop forever if communication doesn't happen
}
}
void loop()
{
// If intPin goes high, all data registers have new data
// On interrupt, check if data ready interrupt
if (myIMU.readByte(MPU9250_ADDRESS, INT_STATUS) & 0x01)
{
myIMU.readAccelData(myIMU.accelCount); // Read the x/y/z adc values
myIMU.getAres();
// Now we'll calculate the accleration value into actual g's
// This depends on scale being set
myIMU.ax = (float)myIMU.accelCount[0]*myIMU.aRes; // - accelBias[0];
myIMU.ay = (float)myIMU.accelCount[1]*myIMU.aRes; // - accelBias[1];
myIMU.az = (float)myIMU.accelCount[2]*myIMU.aRes; // - accelBias[2];
myIMU.readGyroData(myIMU.gyroCount); // Read the x/y/z adc values
myIMU.getGres();
// Calculate the gyro value into actual degrees per second
// This depends on scale being set
myIMU.gx = (float)myIMU.gyroCount[0]*myIMU.gRes;
myIMU.gy = (float)myIMU.gyroCount[1]*myIMU.gRes;
myIMU.gz = (float)myIMU.gyroCount[2]*myIMU.gRes;
myIMU.readMagData(myIMU.magCount); // Read the x/y/z adc values
myIMU.getMres();
// User environmental x-axis correction in milliGauss, should be
// automatically calculated
myIMU.magbias[0] = +470.;
// User environmental x-axis correction in milliGauss TODO axis??
myIMU.magbias[1] = +120.;
// User environmental x-axis correction in milliGauss
myIMU.magbias[2] = +125.;
// Calculate the magnetometer values in milliGauss
// Include factory calibration per data sheet and user environmental
// corrections
// Get actual magnetometer value, this depends on scale being set
myIMU.mx = (float)myIMU.magCount[0]*myIMU.mRes*myIMU.magCalibration[0] -
myIMU.magbias[0];
myIMU.my = (float)myIMU.magCount[1]*myIMU.mRes*myIMU.magCalibration[1] -
myIMU.magbias[1];
myIMU.mz = (float)myIMU.magCount[2]*myIMU.mRes*myIMU.magCalibration[2] -
myIMU.magbias[2];
} // if (readByte(MPU9250_ADDRESS, INT_STATUS) & 0x01)
// Must be called before updating quaternions!
myIMU.updateTime();
// Sensors x (y)-axis of the accelerometer is aligned with the y (x)-axis
of
// the magnetometer; the magnetometer z-axis (+ down) is opposite to z-axis
// (+ up) of accelerometer and gyro! We have to make some allowance for
this
// orientationmismatch in feeding the output to the quaternion filter. For
the
// MPU-9250, we have chosen a magnetic rotation that keeps the sensor
forward
// along the x-axis just like in the LSM9DS0 sensor. This rotation can be
// modified to allow any convenient orientation convention. This is ok by
// aircraft orientation standards! Pass gyro rate as rad/s
//MadgwickQuaternionUpdate(-myIMU.ax, myIMU.ay, myIMU.az, myIMU.gx*PI/180.0f,
-myIMU.gy*PI/180.0f, -myIMU.gz*PI/180.0f, myIMU.my, -myIMU.mx,
myIMU.mz,myIMU.deltat);
MahonyQuaternionUpdate(myIMU.ax, -myIMU.ay, -myIMU.az, myIMU.gx
*DEG_TO_RAD, -myIMU.gy*DEG_TO_RAD, -myIMU.gz*DEG_TO_RAD,
myIMU.my,-myIMU.mx, myIMU.mz, myIMU.deltat);
if (!AHRS)
{
myIMU.delt_t = millis() - myIMU.count;
if (myIMU.delt_t > 500)
{
if(SerialDebug)
{
// Print acceleration values in milligs!
Serial.print("X-acceleration: "); Serial.print(1000
*myIMU.ax); Serial.print(" mg "); Serial.print("Y-acceleration: ");
Serial.print(1000*myIMU.ay);
Serial.print(" mg ");
Serial.print("Z-acceleration: "); Serial.print(1000*myIMU.az);
Serial.println(" mg ");
// Print gyro values in degree/sec
Serial.print("X-gyro rate: "); Serial.print(myIMU.gx, 3);
Serial.print(" degrees/sec ");
Serial.print("Y-gyro rate: "); Serial.print(myIMU.gy, 3);
Serial.print(" degrees/sec ");
Serial.print("Z-gyro rate: "); Serial.print(myIMU.gz, 3);
Serial.println(" degrees/sec");
// Print mag values in degree/sec
Serial.print("X-mag field: "); Serial.print(myIMU.mx);
Serial.print(" mG ");
Serial.print("Y-mag field: "); Serial.print(myIMU.my);
Serial.print(" mG ");
Serial.print("Z-mag field: "); Serial.print(myIMU.mz);
Serial.println(" mG");
myIMU.tempCount = myIMU.readTempData(); // Read the adc values
// Temperature in degrees Centigrade
myIMU.temperature = ((float) myIMU.tempCount) / 333.87 + 21.0;
// Print temperature in degrees Centigrade
Serial.print("Temperature is "); Serial.print(myIMU.temperature, 1);
Serial.println(" degrees C");
}
myIMU.count = millis();
} // if (myIMU.delt_t > 500)
} // if (!AHRS)
else
{
// Serial print and/or display at 0.5 s rate independent of data rates
myIMU.delt_t = millis() - myIMU.count;
// update LCD once per half-second independent of read rate
if (myIMU.delt_t > 500)
{
if(SerialDebug)
{
Serial.print("ax = "); Serial.print((int)1000*myIMU.ax);
Serial.print(" ay = "); Serial.print((int)1000*myIMU.ay);
Serial.print(" az = "); Serial.print((int)1000*myIMU.az);
Serial.println(" mg");
Serial.print("gx = "); Serial.print( myIMU.gx, 2);
Serial.print(" gy = "); Serial.print( myIMU.gy, 2);
Serial.print(" gz = "); Serial.print( myIMU.gz, 2);
Serial.println(" deg/s");
Serial.print("mx = "); Serial.print( (int)myIMU.mx );
Serial.print(" my = "); Serial.print( (int)myIMU.my );
Serial.print(" mz = "); Serial.print( (int)myIMU.mz );
Serial.println(" mG");
Serial.print("q0 = "); Serial.print(*getQ());
Serial.print(" qx = "); Serial.print(*(getQ() + 1));
Serial.print(" qy = "); Serial.print(*(getQ() + 2));
Serial.print(" qz = "); Serial.println(*(getQ() + 3));
}
// Define output variables from updated quaternion---these are Tait-Bryan
// angles, commonly used in aircraft orientation. In this coordinate
system,
// the positive z-axis is down toward Earth. Yaw is the angle between
Sensor
// x-axis and Earth magnetic North (or true North if corrected for local
// declination, looking down on the sensor positive yaw is
counterclockwise.
// Pitch is angle between sensor x-axis and Earth ground plane, toward the
// Earth is positive, up toward the sky is negative. Roll is angle between
// sensor y-axis and Earth ground plane, y-axis up is positive roll. These
// arise from the definition of the homogeneous rotation matrix constructed
// from quaternions. Tait-Bryan angles as well as Euler angles are
// non-commutative; that is, the get the correct orientation the rotations
// must be applied in the correct order which for this configuration is
yaw,
// pitch, and then roll.
// For more see
// http://en.wikipedia.org/wiki/Conversion_between_
quaternions_and_Euler_angles
// which has additional links.
myIMU.yaw = atan2(2.0f * (*(getQ()+1) * *(getQ()+2) + *getQ() *
*(getQ()+3)), *getQ() * *getQ() + *(getQ()+1) * *(getQ()+1)
- *(getQ()+2) * *(getQ()+2) - *(getQ()+3) * *(getQ()+3));
myIMU.pitch = -asin(2.0f * (*(getQ()+1) * *(getQ()+3) - *getQ() *
*(getQ()+2)));
myIMU.roll = atan2(2.0f * (*getQ() * *(getQ()+1) + *(getQ()+2) *
*(getQ()+3)), *getQ() * *getQ() - *(getQ()+1) * *(getQ()+1)
- *(getQ()+2) * *(getQ()+2) + *(getQ()+3) * *(getQ()+3));
myIMU.pitch *= RAD_TO_DEG;
myIMU.yaw *= RAD_TO_DEG;
// Declination of SparkFun Electronics (40°05'26.6"N 105°11'05.9"W) is
// 8° 30' E ± 0° 21' (or 8.5°) on 2016-07-19
// - http://www.ngdc.noaa.gov/geomag-web/#declination
myIMU.yaw -= 1.5;
myIMU.roll *= RAD_TO_DEG;
if(SerialDebug)
{
Serial.print("Yaw, Pitch, Roll: ");
Serial.print(myIMU.yaw, 2);
Serial.print(", ");
Serial.print(myIMU.pitch, 2);
Serial.print("rate = ");
Serial.print((float)myIMU.sumCount/myIMU.sum, 2);
Serial.println(" Hz");
}
myIMU.count = millis();
myIMU.sumCount = 0;
myIMU.sum = 0;
} // if (myIMU.delt_t > 500)
} // if (AHRS)
}
void magcalMPU9250(float * dest1, float * dest2)
{
uint16_t ii = 0, sample_count = 0;
int32_t mag_bias[3] = {0, 0, 0}, mag_scale[3] = {0, 0, 0};
int16_t mag_max[3] = {32767, 32767, 32767}, mag_min[3] = {-32767, -32767,
-32767}, mag_temp[3] = {0, 0, 0};
Serial.println("Mag Calibration: Wave device in a figure eight until
done!");
delay(4000);
// shoot for ~fifteen seconds of mag data
if(Mmode == 0x02) sample_count = 128; // at 8 Hz ODR, new mag data is available every 125 ms
if(Mmode == 0x06) sample_count = 1500; // at 100 Hz ODR, new mag data is available every 10 ms
for(ii = 0; ii < sample_count; ii++) {
myIMU.readMagData(mag_temp); // Read the mag data
for (int jj = 0; jj < 3; jj++) {
if(mag_temp[jj] > mag_max[jj]) mag_max[jj] = mag_temp[jj];
if(mag_temp[jj] < mag_min[jj]) mag_min[jj] = mag_temp[jj];
}
if(Mmode == 0x02) delay(135); // at 8 Hz ODR, new mag data is available
every 125 ms
if(Mmode == 0x06) delay(12); // at 100 Hz ODR, new mag data is available
every 10 ms
}
// Serial.println("mag x min/max:"); Serial.println(mag_max[0]);
Serial.println(mag_min[0]);
// Serial.println("mag y min/max:"); Serial.println(mag_max[1]);
Serial.println(mag_min[1]);
// Serial.println("mag z min/max:"); Serial.println(mag_max[2]);
Serial.println(mag_min[2]);
// Get hard iron correction
mag_bias[0] = (mag_max[0] + mag_min[0])/2; // get average x mag bias in counts
mag_bias[1] = (mag_max[1] + mag_min[1])/2; // get average y mag bias in counts
mag_bias[2] = (mag_max[2] + mag_min[2])/2; // get average z mag bias in counts
dest1[0] = (float) mag_bias[0]*myIMU.mRes*myIMU.magCalibration[0]; // save mag biases in G for main program
dest1[1] = (float) mag_bias[1]*myIMU.mRes*myIMU.magCalibration[1];
dest1[2] = (float) mag_bias[2]*myIMU.mRes*myIMU.magCalibration[2];
// Get soft iron correction estimate
mag_scale[0] = (mag_max[0] - mag_min[0])/2; // get average x axis max chord length in counts
mag_scale[1] = (mag_max[1] - mag_min[1])/2; // get average y axis max chord length in counts
mag_scale[2] = (mag_max[2] - mag_min[2])/2; // get average z axis max chord length in counts
float avg_rad = mag_scale[0] + mag_scale[1] + mag_scale[2];
avg_rad /= 3.0;
dest2[0] = avg_rad/((float)mag_scale[0]);
dest2[1] = avg_rad/((float)mag_scale[1]);
dest2[2] = avg_rad/((float)mag_scale[2]);
Serial.println("Mag Calibration done!");
}
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Hi Kris, thank you for answering. Thank for answering. What do you mean that the pitch is not defined at 90º? If you are standing on the North Pole, every direction should be South? |
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Heading not defined at 90pitch because every heading is south
…On Sat, Jun 9, 2018 at 12:42 AM polodealvarado ***@***.***> wrote:
Hi Kris, thank you for answering.
Thank for answering.
What do you mean that the pitch is not defined at 90º?
If you are standing on the North Pole, every direction should be South?
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So, what should I change or add in the code? |
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Nothing, inherent limitation of all quaternion-based absolute orientation
estimation.
…On Sat, Jun 9, 2018 at 6:58 AM, polodealvarado ***@***.***> wrote:
So, what should I change or add in the code?
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And |
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" without altering the yaw axis"
alter how?
…On Sat, Jun 9, 2018 at 9:43 AM, polodealvarado ***@***.***> wrote:
And
there is no way to have 90º in the pitch without altering the yaw axis?
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If you need to operate the device at a pitch of 90 degrees you can change
the Madgwick/Mahony sensor orientations (NED) to make 90 degree pitch the
"normal position". But why are you operating at a pitch of 90 degrees?
On Sat, Jun 9, 2018 at 9:46 AM, Tlera Corporation <tleracorp@gmail.com>
wrote:
… " without altering the yaw axis"
alter how?
On Sat, Jun 9, 2018 at 9:43 AM, polodealvarado ***@***.***>
wrote:
> And
> there is no way to have 90º in the pitch without altering the yaw axis?
>
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Okey Kris, I understood it. Thank you so much. I am making my own Head-tracking system with the MPU9250, and when I put the IMU in vertical ( 90º pitch), the yaw angle went crazy. I would like to find a way to maintain it, do you know some way? |
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Nope
…On Sat, Jun 9, 2018 at 11:07 AM, polodealvarado ***@***.***> wrote:
Okey Kris, I understood it. Thank you so much.
I am making my own Head-tracking system with the MPU9250, and when I put
the IMU in vertical ( 90º pitch), the yaw angle went crazy.
I would like to find a way to maintain it, do you know some way?
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Perfect! Thank so much for your help! |
Hi Kris.
First of all, thank you very much for this library, it has really helped me.
I have a problem with my yaw angle. When the pitch or roll angle reach 90º or -90º , the yaw angle changes taking an illogical value.
The magnetometor has been calibrated correctly, but I am not sure if the problem comes form the filter or the yaw,pitch,roll calculation. My coordinate system is this: (https://www.google.es/search?q=mpu9250+coordinates&client=opera&hs=2vh&source=lnms&tbm=isch&sa=X&ved=2ahUKEwj--fndwMTbAhWLQBQKHTZKB0MQ_AUoAXoECAEQAw&biw=1650&bih=870#imgrc=oPcs2IW3wPfIbM:)
Thank you in advance.
/* MPU9250 Basic Example Code
by: Kris Winer
date: April 1, 2014
license: Beerware - Use this code however you'd like. If you
find it useful you can buy me a beer some time.
Modified by Brent Wilkins July 19, 2016
Demonstrate basic MPU-9250 functionality including parameterizing the register
addresses, initializing the sensor, getting properly scaled accelerometer,
gyroscope, and magnetometer data out. Added display functions to allow display
to on breadboard monitor. Addition of 9 DoF sensor fusion using open source
Madgwick and Mahony filter algorithms. Sketch runs on the 3.3 V 8 MHz Pro Mini
and the Teensy 3.1.
SDA and SCL should have external pull-up resistors (to 3.3V).
10k resistors are on the EMSENSR-9250 breakout board.
Hardware setup:
MPU9250 Breakout --------- Arduino
VDD ---------------------- 3.3V
VDDI --------------------- 3.3V
SDA ----------------------- A4
SCL ----------------------- A5
GND ---------------------- GND
*/
#include "quaternionFilters.h"
#include "MPU9250.h"
#define AHRS true // Set to false for basic data read
#define SerialDebug true // Set to true to get Serial output for debugging
uint8_t Mmode = 0x06;
MPU9250 myIMU;
void setup()
{
Wire.begin();
// TWBR = 12; // 400 kbit/sec I2C speed
Serial.begin(115200);
// Read the WHO_AM_I register, this is a good test of communication
byte c = myIMU.readByte(MPU9250_ADDRESS, WHO_AM_I_MPU9250);
Serial.print("MPU9250 "); Serial.print("I AM "); Serial.print(c, HEX);
Serial.print(" I should be "); Serial.println(0x71, HEX);
if (c == 0x71) // WHO_AM_I should always be 0x68
{
Serial.println("MPU9250 is online...");
} // if (c == 0x71)
else
{
Serial.print("Could not connect to MPU9250: 0x");
Serial.println(c, HEX);
while(1) ; // Loop forever if communication doesn't happen
}
}
void loop()
{
// If intPin goes high, all data registers have new data
// On interrupt, check if data ready interrupt
if (myIMU.readByte(MPU9250_ADDRESS, INT_STATUS) & 0x01)
{
myIMU.readAccelData(myIMU.accelCount); // Read the x/y/z adc values
myIMU.getAres();
} // if (readByte(MPU9250_ADDRESS, INT_STATUS) & 0x01)
// Must be called before updating quaternions!
myIMU.updateTime();
// Sensors x (y)-axis of the accelerometer is aligned with the y (x)-axis of
// the magnetometer; the magnetometer z-axis (+ down) is opposite to z-axis
// (+ up) of accelerometer and gyro! We have to make some allowance for this
// orientationmismatch in feeding the output to the quaternion filter. For the
// MPU-9250, we have chosen a magnetic rotation that keeps the sensor forward
// along the x-axis just like in the LSM9DS0 sensor. This rotation can be
// modified to allow any convenient orientation convention. This is ok by
// aircraft orientation standards! Pass gyro rate as rad/s
//MadgwickQuaternionUpdate(-myIMU.ax, myIMU.ay, myIMU.az, myIMU.gxPI/180.0f, -myIMU.gyPI/180.0f, -myIMU.gz*PI/180.0f, myIMU.my, -myIMU.mx, myIMU.mz,myIMU.deltat);
MahonyQuaternionUpdate(myIMU.ax, -myIMU.ay, -myIMU.az, myIMU.gxDEG_TO_RAD,
-myIMU.gyDEG_TO_RAD, -myIMU.gz*DEG_TO_RAD, myIMU.my,-myIMU.mx, myIMU.mz, myIMU.deltat);
if (!AHRS)
{
myIMU.delt_t = millis() - myIMU.count;
if (myIMU.delt_t > 500)
{
if(SerialDebug)
{
// Print acceleration values in milligs!
Serial.print("X-acceleration: "); Serial.print(1000myIMU.ax);
Serial.print(" mg ");
Serial.print("Y-acceleration: "); Serial.print(1000myIMU.ay);
Serial.print(" mg ");
Serial.print("Z-acceleration: "); Serial.print(1000*myIMU.az);
Serial.println(" mg ");
} // if (!AHRS)
else
{
// Serial print and/or display at 0.5 s rate independent of data rates
myIMU.delt_t = millis() - myIMU.count;
// Define output variables from updated quaternion---these are Tait-Bryan
// angles, commonly used in aircraft orientation. In this coordinate system,
// the positive z-axis is down toward Earth. Yaw is the angle between Sensor
// x-axis and Earth magnetic North (or true North if corrected for local
// declination, looking down on the sensor positive yaw is counterclockwise.
// Pitch is angle between sensor x-axis and Earth ground plane, toward the
// Earth is positive, up toward the sky is negative. Roll is angle between
// sensor y-axis and Earth ground plane, y-axis up is positive roll. These
// arise from the definition of the homogeneous rotation matrix constructed
// from quaternions. Tait-Bryan angles as well as Euler angles are
// non-commutative; that is, the get the correct orientation the rotations
// must be applied in the correct order which for this configuration is yaw,
// pitch, and then roll.
// For more see
// http://en.wikipedia.org/wiki/Conversion_between_quaternions_and_Euler_angles
// which has additional links.
myIMU.yaw = atan2(2.0f * (*(getQ()+1) * *(getQ()+2) + *getQ() *
*(getQ()+3)), *getQ() * *getQ() + *(getQ()+1) * *(getQ()+1)
- *(getQ()+2) * *(getQ()+2) - *(getQ()+3) * *(getQ()+3));
} // if (AHRS)
}
void magcalMPU9250(float * dest1, float * dest2)
{
uint16_t ii = 0, sample_count = 0;
int32_t mag_bias[3] = {0, 0, 0}, mag_scale[3] = {0, 0, 0};
int16_t mag_max[3] = {32767, 32767, 32767}, mag_min[3] = {-32767, -32767, -32767}, mag_temp[3] = {0, 0, 0};
Serial.println("Mag Calibration: Wave device in a figure eight until done!");
delay(4000);
for(ii = 0; ii < sample_count; ii++) {
myIMU.readMagData(mag_temp); // Read the mag data
for (int jj = 0; jj < 3; jj++) {
if(mag_temp[jj] > mag_max[jj]) mag_max[jj] = mag_temp[jj];
if(mag_temp[jj] < mag_min[jj]) mag_min[jj] = mag_temp[jj];
}
if(Mmode == 0x02) delay(135); // at 8 Hz ODR, new mag data is available every 125 ms
if(Mmode == 0x06) delay(12); // at 100 Hz ODR, new mag data is available every 10 ms
}
// Serial.println("mag x min/max:"); Serial.println(mag_max[0]); Serial.println(mag_min[0]);
// Serial.println("mag y min/max:"); Serial.println(mag_max[1]); Serial.println(mag_min[1]);
// Serial.println("mag z min/max:"); Serial.println(mag_max[2]); Serial.println(mag_min[2]);
Serial.println("Mag Calibration done!");
}
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