Euler angle calculation is different from Wikipedia?

[de-viant]

Wikipedia shows

And in the code it is
yaw = atan2(2.0f * (q[1] * q[2] + q[0] * q[3]), q[0] * q[0] + q[1] * q[1] - q[2] * q[2] - q[3] * q[3]);

pitch = -asin(2.0f * (q[1] * q[3] - q[0] * q[2]));

roll = atan2(2.0f * (q[0] * q[1] + q[2] * q[3]), q[0] * q[0] - q[1] * q[1] - q[2] * q[2] + q[3] * q[3]);

it seems Euler angle calculation is different from the wikipedia displays. (Formulae for Yaw and Roll seem interchanged)

https://en.wikipedia.org/wiki/Conversion_between_quaternions_and_Euler_angles

[kriswiner]

Maybe they define roll and yaw opposite to the way we do? WHich one gives the correct results in your device?

…

On Sun, Oct 3, 2021 at 12:04 PM Ayush Sinha ***@***.***> wrote: Wikipedia shows [image: image] <https://user-images.githubusercontent.com/54477816/135767715-f530fb4c-98bd-433c-95cf-1956631287a2.png> And in the code it is yaw = atan2(2.0f * (q[1] * q[2] + q[0] * q[3]), q[0] * q[0] + q[1] * q[1] - q[2] * q[2] - q[3] * q[3]); pitch = -asin(2.0f * (q[1] * q[3] - q[0] * q[2])); roll = atan2(2.0f * (q[0] * q[1] + q[2] * q[3]), q[0] * q[0] - q[1] * q[1] - q[2] * q[2] + q[3] * q[3]); it seems Euler angle calculation is different from the wikipedia displays. (Formulae for Yaw and Roll seem interchanged) https://en.wikipedia.org/wiki/Conversion_between_quaternions_and_Euler_angles — You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub <#468>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/ABTDLKVGSYP6TSZDBASRSWDUFCSKLANCNFSM5FH5B7EA> . Triage notifications on the go with GitHub Mobile for iOS <https://apps.apple.com/app/apple-store/id1477376905?ct=notification-email&mt=8&pt=524675> or Android <https://play.google.com/store/apps/details?id=com.github.android&referrer=utm_campaign%3Dnotification-email%26utm_medium%3Demail%26utm_source%3Dgithub>.

[de-viant]

your convention gives better result.
In my device I have an MPU6050 and QMC5883L (Clone of HMC5883), which have their axes aligned (atleast the x, y axes not so sure about z axis) so I update as

MadgwickQuaternionUpdate(ax, ay, az, gxPI/180.0f, gyPI/180.0f, gzPI/180.0f, mx, my, mz).
instead of
MadgwickQuaternionUpdate(ax, ay, az, gxPI/180.0f, gyPI/180.0f, gzPI/180.0f, my, -mx, -mz
as in the MPU6050HMC5883AHR example sketch.

It seems to work fine, the only thing that bothers me is

The small correlation I observe of yaw with change with roll or pitch. But changing yaw doesn't change roll, pitch.
I tested by using a breadboard, rotating along x,y,z axes. I see yaw varies slightly when I change pitch or roll, but when I place the breadboard flat on the table (initial state) the yaw corrects to initial value. Is this behavior expected?