Rotate IMU data to obtain correct measurement data

[hoddy]

Hi

I have collected data from a IMU on a boat. Currently I am using the angular velocity measurement vector $\omega^b_{imu} = \begin{pmatrix} p\\q\\r\end{pmatrix}$ for use in kalman filter, where superscript $b$ is BODY frame. The BODY frame is given be x-axis pointing forward, y-axis pointing starboard (right), and z-axis downwards. But I noticed that the IMU's orientation is not aligned with the BODY frame. The IMU axis is pointing: x forward, y left, and z upwards. The measurement vector is therefore denoted $\omega^m_{imu} = \begin{pmatrix} p\\q\\r\end{pmatrix}$, instead of the above, where $m$ is measurement frame. Can I then rotate 180 degrees about x-axis as follows:
$\omega^b_{imu} = R_x(\phi)\omega^m_{imu} = \begin{pmatrix}1 & 0 & 0\\0 & cos(\phi) & -sin(\phi)\\0 & sin(\phi) & cos(\phi)\end{pmatrix}\begin{pmatrix}p\\q\\r\end{pmatrix} = = \begin{pmatrix}1 & 0 & 0\\0 & -1 & 0\\0 & 0 & -1\end{pmatrix}\begin{pmatrix}p\\q\\r\end{pmatrix}$
to obtain the correct measurement data?
Thanks for any replies!

 

[Paul Colby]

I assume the handedness of your coordinates isn't an issue. That would be you don't care if the axes a left or right-handed. If this is the case, why not just change the sign of Z?.

 

[Filip Larsen]

Your rotation matrix and equation looks good, but I must say I am a bit curious why you are unsure about that part but still fine with setting up a Kalman filter.