Fix quaternions to roll, pitch, yaw angles #45
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The series_quat2euler function computes wrong roll and pitch angles. This has been fixed by replacing the transforms3d.taitbryan.quat2euler function with the transforms3d.euler.quat2euler function called with axes='sxyz' option (1-2-3 extrinsic convention). Note that the transforms3d.taitbryan.quat2euler function is equivalent to the transforms3d.euler.quat2euler function called with axes='szyx' option (3-2-1 extrinsic convention), which is not the used convention in PX4 (3-2-1 intrinsic convention). Finally, an extrinsic convention is equivalent to an intrinsic convention but with rotations performed in reversed order (and vis versa), so that the proposed correction (1-2-3 extrinsic convention) is equivalent to the PX4 convention (3-2-1 intrinsic convention) without even the need to swap the order of outputs. To validate this correction: do some pure roll motion, then some pure pitch, then perform a 90 degrees pure yaw rotation and finally, from that new yaw orientation, do again some pure roll and pure pitch motions. You will see that the roll and pitch angles before this correction are wrong, while they are correct after.
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The
series_quat2eulerfunction computes wrong roll and pitch angles. This has been fixed by replacing thetransforms3d.taitbryan.quat2eulerfunction with the more generaltransforms3d.euler.quat2eulerfunction called withaxes='sxyz'option (1-2-3 extrinsic convention).Note that the
transforms3d.taitbryan.quat2eulerfunction is equivalent to thetransforms3d.euler.quat2eulerfunction called withaxes='szyx'option (3-2-1 extrinsic convention), which is not the used convention in PX4 (3-2-1 intrinsic convention).Finally, an extrinsic convention (fixed ground axes) is equivalent to an intrinsic convention (moving body axes) but with rotations performed in reversed order (and vis versa), so that the proposed correction (1-2-3 extrinsic convention) is equivalent to the PX4 convention (3-2-1 intrinsic convention) without even the need to swap the order of outputs.
To validate this correction: do some pure roll motion, then some pure pitch, then perform a 90 degrees pure yaw rotation and finally, from that new yaw orientation, do again some pure roll and pure pitch motions. You will see that the roll and pitch angles before this correction are wrong, while they are correct after.