"Hi Thank you Bill, that was exactly what I needed. So, as I understood we should have this rotation matrix from other sensors or it should be a fixed orientations? Thank you Behnam"

"Hi Really thank you for this clear help and guidance. I've a basic Problem in this Theory... How can I have Direction Cosine Matrix ? is it change or it's constant ? Now I have sensor output data but I don't know exactly how should I…"