How should I design a filter

[xylitol]

HI,i come back
i see the our quadcopter used the IIR filter,i also want to design a low filter,but i donn't have any experience in this.I used matlab transform the data (used FFT),i have some questions ,the ACC data have three axis,did i convert all?And how to design a filter can work under three axis?Give me some informations or links,Thank you ?memeda

[tobias]

This document from cypress is pretty good at explaining it.