System Identification for control

Just in case you are still working on this, you might be interested to look at external offsets. There is a simulation configuration called 'Dynamic External Offsets' under /configs/sim/axis/external_offsets that uses a sinus generation on the z axis.
Maybe this could be adapted to your needs.

Hello,

i don't think that trying this within linuxcnc will lead to an usable result...

Event with using an 2khz Servo thread, the resolution for getting an good result would be to low.

but you told that you are using ethercat, this drives are all from the "newer days"... all drives i know have internal functions to draw and record an bode plott.
Everytime we have done this, the controller runs on an 65us cycle time....