I have tried plotting the result for 600 samples, as in the graph below:
xacc is acceleration on x axis from HIGHRES_IMU message, and gpsxacc is acceleration converted from velocity(vx) from GLOBAL_POSITION_INT. In the graph, at some periods of time, the both data are contrast together. Is this because of noise? or is it relate to the coordination of both messages as I understand so far both are the same local NED. and Is there any possible solution for the discrete derivative of the velocity estimate with less noise than the simple one I'm using now.
Sorry for asking you so many questions, I'm not engineering, I still have some trouble to find and understand maths myself. Thank you for your kindly help.