Replies to This Discussion

Permalink Reply by Artem Grigoryev on November 23, 2012 at 9:06am

I just verified my values again on a tilt platform with a digital protractor.  My unit tracks angles (both pitch and roll) within a degree of the protractor.  So it is something in your setup, software or possibly even hardware.  Make sure you tilt along main axes (not diagonally), make sure your unit initializes flat when you turn the power on and it is perfectly stationary while the LEDs are flashing.

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Permalink Reply by Dave Whittington on November 23, 2012 at 11:02am

Artem,

     I just wanted to confirm that the two simple changes (GRAVITY=8192 and the two gain changes) are all that is required for you an ArduIMU 1.9.8 (neglecting YAW improvements - I don't use a GPS). I will retest my measurements - do you go all the way near 90 deg or just to maybe 45 deg.

    Do you have any expectations of whether it will drift much as long as the rotation rates are low?

     I appreciate your expertise in this - don't you think that whoever is responsible for the code should make your changes and release it.

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Permalink Reply by Artem Grigoryev on November 23, 2012 at 4:47pm

Those are the only two changes I made as far as pitch and roll go.  Today I tested it again to 60 degrees both pitch and roll but previously I went all the way to 90.

At rest pitch and roll should not drift at all.  Accelerometer takes care of that.  If it still doesn't work look at the raw output of the gyro and accelerometer.

I posted the bug report about this issue at the ArduIMU development page on June 28th.  It is still sitting there in new issue category among a couple dozen other issues.  I don't think this "project"  has an owner.  Somebody wrote the original code a long time ago and since then moved on.  Later on somebody tried re-write the code for the new hardware and botched it.  The reason Sparkfun and 3D Robotics get away with that is because it is just an "example" code.  You are buying hardware and you are free to do whatever you want with it.

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Permalink Reply by Pete Birley on April 11, 2013 at 4:09am

Dave,

Did you ever get this working? I'm experiencing the exact same symptoms as you are with the scaling of roll and pitch values.

Cheers

Pete

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Permalink Reply by Bhaumik on March 25, 2013 at 9:44pm

Hey,
I am not using DCM algo for arduIMU v3 cause it is not giving me correct anglular orientation.
I have used only MPU6000 for orientation calculation.
The function for used for calculation gyro angle is as below:

void Get_Gyro_Rates(unsigned long dt)
{
  byte_H = MPU6000_SPI_read(MPUREG_GYRO_XOUT_H);
  byte_L = MPU6000_SPI_read(MPUREG_GYRO_XOUT_L);
  gyroXRaw = ((byte_H8)| byte_L) - GYRO_XOUT_OFFSET;
  // Read GyroY
  byte_H = MPU6000_SPI_read(MPUREG_GYRO_YOUT_H);
  byte_L = MPU6000_SPI_read(MPUREG_GYRO_YOUT_L);
  gyroYRaw = ((byte_H8)| byte_L) - GYRO_YOUT_OFFSET;
  // Read GyroZ
  byte_H = MPU6000_SPI_read(MPUREG_GYRO_ZOUT_H);
  byte_L = MPU6000_SPI_read(MPUREG_GYRO_ZOUT_L);
  gyroZRaw = ((byte_H8)| byte_L) - GYRO_ZOUT_OFFSET;
 
 
  gyroXRate = (float)gyroXRaw/gyro_xsensitivity*dt*0.001;
  gyroYRate = (float)gyroYRaw/gyro_ysensitivity*dt*0.001;
  gyroZRate = (float)gyroZRaw/gyro_zsensitivity*dt*0.001;
  //if(abs(gyroXRaw)>1)
    GYRO_XANGLE += gyroXRate;
  //if(abs(gyroYRaw)>1)  
    GYRO_YANGLE += gyroYRate;
//  if(abs(gyroZRaw)>1)  
    GYRO_ZANGLE += gyroZRate;
  Serial.print(GYRO_XANGLE);
  Serial.print(" ");
  Serial.println(GYRO_ZANGLE);
}

here, I am am continuously getting increments or decrements in each angle..
If you can help please suggest me the best way to use arduIMU v3..?

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Permalink Reply by ahmad on April 11, 2013 at 6:37pm

the tan,sin,cos are multiplied by 1.9--- delete this 1.9 so in the last part in DCM
void Euler_angles(void)
{
#if (OUTPUTMODE==2) // Only accelerometer info (debugging purposes)
roll = atan2(Accel_Vector[1],Accel_Vector[2]); // atan2(acc_y,acc_z)
pitch = asin((Accel_Vector[0])/(double)GRAVITY); // asin(acc_x)
yaw = 0;
#else
pitch = asin(DCM_Matrix[2][0]);
roll = atan2(DCM_Matrix[2][1],DCM_Matrix[2][2]);
yaw = atan2(DCM_Matrix[1][0],DCM_Matrix[0][0]);
#endif
}

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Permalink Reply by Himanshu Agrawal on April 11, 2013 at 9:22pm

turning off the magnetometer will solve the issue !!!

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