Arduino - MPU 6050 - Library Orientation

[ThePoshTux]

For my application of the sensor, a VR headset, I need the axes to be redefined to Yaw about the x-axis, Pitch about the y-axis and roll about the z-axis. Looking at example code and at the MPU6050_9Axis_MotionApps41.h library, I found that to redefine the axes the library must be modified. Shown below I have modified dmpGetYawPitchRoll (from the same library) to use the different axes so that the yaw and pitch now work correctly. However, the roll does not work correctly.

Modified code:
uint8_t MPU6050::dmpGetYawPitchRoll(float *data, Quaternion *q, VectorFloat *gravity) { // yaw: (about x axis) data[0] = atan2(2*q -> y*q -> z - 2*q -> w*q -> x, 2*q -> w*q -> w + 2*q -> y*q -> y - 1); // pitch: (nose up/down, about y axis) data[1] = atan(gravity -> y / sqrt(gravity -> z*gravity -> z + gravity -> x*gravity -> x)); // roll: (tilt left/right, about z axis) data[2] = atan(gravity -> z / sqrt(gravity -> y*gravity -> y + gravity -> x*gravity -> x)); return 0; }

original:
uint8_t MPU6050::dmpGetYawPitchRoll(float *data, Quaternion *q, VectorFloat *gravity) { // yaw: (about Z axis) data[0] = atan2(2*q -> x*q -> y - 2*q -> w*q -> z, 2*q -> w*q -> w + 2*q -> x*q -> x - 1); // pitch: (nose up/down, about Y axis) data[1] = atan(gravity -> x / sqrt(gravity -> y*gravity -> y + gravity -> z*gravity -> z)); // roll: (tilt left/right, about X axis) data[2] = atan(gravity -> y / sqrt(gravity -> x*gravity -> x + gravity -> z*gravity -> z)); return 0; }

When facing forward the roll works correctly, changing my yaw by +/- 90 degrees disables all roll and turning 180(from forwards) causing the roll to become inverted.
I believe my issue may stem from not modifying quaternation or gravity to the new axis but I am lost when trying to modify those sections of the code.

What would be the correct changes I would have to make to the library as to modify the orientation?

Looking at the Issues page I have seen people posting about issues that they think are of calibration but share symptoms of incorrect axes mapping I have experienced.

Regardless, thank you for the great work.

[ThePoshTux]

#64