Unstable validation measurement

Problem

The tuning was carried out successfully, but the validation of the results (red) shows unstable behavior.

Solution

In the example above, a very high value was determined for the gain factor for the speed controller because the initial measurement did not map the frequency response sharply enough. As a result, resonance and antiresonance cannot be determined accurately enough and the simulation of the mechanics does not match the real behavior.

In this case, increase the resolution of the frequency response in the frequency range by increasing the number of "Frequency steps" in the section Bode settings.