Where does the calculations from Design Tip DT0060 Step 1 come from?

[SNago.1]

Hello everyone,

currently I am working on a E-Compass and I totally understand the calculations for the tilt compensation. So i wanted a higher accuracy and looked into DT0060 and everything works fine, but I don't understand where those calculations in Step 1 come from and after asking STM support they told me to ask in the community.

I hope someone is nice enough to tell me or give me a hint. It doesn't seem to come from rotation matrices, because both solutions from multiplying the rotation matrices from a rotation around the x axis and around the y axis (only phi and theta is used, so I assume the z-axis rotation matrix isn't necessary) are very different from the matrix used to calculate the derivatives.

Have a nice day!

[niccolò]

Hi @SNago.1​ ,

the Step 1 is based on the calculation for the derivation of the roll/pitch/yaw derivatives in 3D.

The full demonstration is pretty complicated and I think it can be found in advanced calculus/physics books.

Do you need a full explanation?

[SNago.1]

Hi @niccolo.ruffini​,

complicated is no problem for me, I am studying mechatronics in Germany :D

So I really would like a full explanation, but before that: I was already contacted from another ST Employee via E-Mail who connected me to Ms. Vitali, the author from DT0060, and she told me she gives me an answer, but right now she isn't able to do it, but next week. This case isn't time relevant, so I can wait :D She also gave me a hint, like you, and this weekend, when I have time I wanted to look into it myself, one more time.

Thanks and greetings!

[niccolò]

that's great, surely Ms. Vitali will be able to help you more than i could, being that she was the one that wrote it =)

Good luck with your machatronics studies, I hope to be hearing from you soon for new projects!