Onboard IMU Questions

[gerth2]

A few questions on how to code up the onboard IMU, mostly related to mount orientation. All of this is "my concerns prior to writing code" - if answers are unknown or trivial feel free to tell me to go away and do science :) .

There are 6 possible gravity-orthogonal mount orientations (one per face), but the OnboardIMU.MountOrietation has only three. I assume "180-inverted" options are disambiguated using gravity?

Also, what exactly is the mount orientation used to do ? I assume some transform of coordinates?

Is there a failure mode if the robot is under acceleration during boot up?

Are non-orthogonal mountings allowed? I have at least one robot with the RIO at a 45 degree angle to gravity.

Are the acceleration and gyro readings fused at all? And, if so, would that drive a requirement the SystemCore is at the center of rotation of the bot (so as not to get linear acceleration during pure robot rotations?)

[KangarooKoala]

RE non-orthogonal mountings, from wpilibsuite/allwpilib#8016 (comment), you may have to implement logic yourself to maintain a 3d angle offset, which would be a bit tricky.