Below you will find some useful resources for tuning a direct drive system.
Note all ACS related links require an account on the ACS website.
ACS “Very Basic Control System Theory” – awesome @17:41
Understand bandwidth
How to add a manual notch filter on resonance – @12:46
Understand gain crossover and phase cross over:
Useful basics on a FRF (awesome):
https://community.sw.siemens.com/s/article/what-is-a-frequency-response-function-frf