Alberto recentered the beam on WFS, I tweaked the alignment of the cavity, and WFS still didn't work (this time its running off in YAW).

I remeasured the sensing matrix, which didn't change much from what Daniel measured:

 WFSAPIT = 0.047*POS -5.66*ANG

 WFSBPIT = 0.906*POS - 3.760*ANG

 WFSAYAW = 0.086*POS + 2.379*ANG

 WFSBYAW = -0.293*POS + 3.302*ANG

Note that the coherence for WFSA against POS injection was poor both for PIT and YAW, but everything else had an excellent coherence.

Inverting these, PIT input matrix is [-0.759, 1.143; -0.183, 0.009]

YAW input matrix is [3.366, -2.425; 0.299, 0.088]

But of course it still didn't work, everything was running off in YAW.

Since, unsurprisingly, POS YAW feedback was the bad guy, I enabled POS_PIT, ANG_PIT and ANG_YAW, centered the wfs using picos, lowered the gain for POS_YAW, enabled all four DOFs, disabled the input, recentered, enabled, recentered, and at some point it stopped running away. I set the gain of POS_YAW to the same value as ANG_YAW and it still worked.

UGF of all DOFs are supposedly 50mHz with the filter gain of -5. I think we can go higher, but sadly the cavity power is hashier with WFS enabled, even with this low gain. But at low frequency it is certainly doing its job (I can push TMs and WFS automatically brings them back).

I leave it with WFS on for tonight.

Note:  At some point I started isolating ISIs and tripped HEPI and ISI, and put ISI back to damped without isolation.

Note2: To make it easier for people to look at angle data later, WFS sensing matrix data also contains the TFs from POS and ANG excitation to ETM and ITM oplev.  See the snapshot to find the location of the file in the title bar.

Note3: The reason why I seem to have done this at 0.04736b4 Hz is because of DTT quirk. I told dtt to make a sweep from 0.1Hz to 0.09Hz with one data point, and somehow dtt decided to do it at 0.047something, or maybe it did measure at 0.1Hz but displayed as if everything was done at that frequency.