I´m working on a little INS project and I´m a bit confused about the reference frames. Actually: I don´t get why I have to transform from body to global frame and how to do it. Why can´t I just integrate the Acc signals and take the position from it? So far I understand that I have to calculate the attitude first from the gyro and take the results to transform from acc frame b(ody) to acc frame g(lobal). But yeah, I simply don´t geht why and how to implement it. What´s the gain? I read lots of reports and papers but they are mostly very abstract or to complex for me since my math skills are not the best. As far as I know it´s just a simple matrix multiplication but I don´t really get how to derive it. A tutorial for dummies or code snippet would help me a lot. Any ideas?