Continuation of 11457. The resonance in the transfer functions posted here pose a problem. I attempted to notch the control signal at these frequencies by having the control signal coming from the slow controller that goes to the piezo go through a filter that looks like 104D4209-24EA-4949-9A9C-90D8223B8CB6.png. I then take the transfer function with this filter in place and get 7DCB0A48-8C53-4E50-9BE5-8BD7991CC780.png. For some reason this notch is not successfully getting rid of this garbage at ~4kHz. 

Further investigation needed.