[Jamie, Lisa, Daniel, Evan]

Two WFS are added to the ALS end models, "A" and "B".

A "standard" ASC servo is added that takes the WFS I phase outputs and EPICS inputs intended to come from camera centroid finding, and puts them through an input matrix/servo filters/output matrix combo.  The outputs of the output matrices are sent to a separate servo path with the QPD outputs for ALS PZT input pointing.  The outputs of two of the WFS DOFs are intended for feedback to the arm SUS controllers, and are therefore send to the vertex global ASC model for sending to the ITMs and ETMs.

We have committed this to the SVN as revision 7127.

(Sheila, Alexa)

We aligned the green straight shot path with the TMSX and the ITMX Baffle PDS:

PD1 Yaw: -226.4, Pit: 221.6 @ 2.26V

PD4 Yaw: -288.6, Pit: 290.7 @ 2.47V

TMSX Alignement Position Yaw: -257.3,  Pit: 256.2

Yesterday morning I finished adding the final touches to the payload of ETMy, leaving only 2 face sheilds and the teflon bump stops on the optics.  SEI will only see this as a few extra pounds of weight to be tuned out later in-chamber.  We've handed off to SEI for float/balance/testing on the cartridge.

Yuta, Evan, Kiwamu

We steered the picomotors on TMSX again tonight to center the red transmitted light on the QPDs. After a couple of hours of struggling, we managed to bring both of them within their linear range. This is good enough for now as this should be able to monitor some alignment-related signals. The numbers below are the current picomotor settings:

M4 X = -12813, Y = 38475

M14 X = -12810, Y = -75268

Because of this alignment work, we lost the red trans signal and red trans camera view again. We don't have energy to realign them on ISCTEX table at the moment and therefore are leaving it as it is.

Stefan, Evan, Yuta, Kiwamu

We looked at the infrared PDH signal when the PSL frequency was stabilised by the ALS technique. 

The residual noise of the PSL frequency with respect to the arm cavity was measured to be 90 Hz in RMS, integrated from 7 kHz to 10 mHz.

Noise Meausrement:

After a smooth ALS's handoff, we shifted the COMM VCO frequency to place the infrared on top of a 00 resonance. Then we measured the PDH signal at the REFL port while maintaining the resonance only with the ALS beatnote.

Right now, the performance is limite by 80 mHz bump and acoustic-looking forest between 100 and 1000 Hz. The plot above is calibrated in Hz for a 1064 nm laser and cavity pole was removed by applying a zero at 42 Hz. The red curve is REFLAIR_RF9 divided by TRX to have a wider linear range. Because the fluctuation is bigger than the linewidth REFLAIR_RF9 without the TRX normalization underestimated the actual noise.

Linearization of the PDH:

In order to expand the linear range of the PDH signal, we did the legacy technique where the PDH signal was divided by the intracavity power. We used LSC_X_TR_A_LF for the denominator. The attached screenshot shows the waveforms with and without the division. The red curve is the one with the division. The pink curve shows the one without the division. You can see that the red curve can go to bigger numbers.

Also, there were glitches which seemed to happen roughly once in 30 seconds. The attaches shows an example screenshot of it. Typically it somehow drops the IMC transmitted light at the same time. As you can see, LSC_CARM_IN1 shows a sharp spike.

Results of my visit to LHO this week for system identification of the ETMY.

MOTIVATION:

Make better models for each particular suspension to aid control design and noise predictions.

The measured frequencies of the resonances are the most reliable data we have because they are not subject to errors in the sensors or actuators. There are also numerous resonances available for measurement, which can be used to adjust the model.

SETUP:

Resonance measurements were collected on ETMY main chain while on the test stand in the follow configuration with the following methods:
* full quad - top mass to top mass transfer functions using the OSEMs. This data was measured prior to my visit this week.
* triple hang - with the main chain top mass, reaction chain UIM and PUM masses locked on stops, spectra of the lower three main chain stages were measured with the UIM and PUM OSEMs and an optical lever on the test mass. No excitation is needed since the wind from the fans is more than enough. The process of locking the masses also misaligns the UIM and PUM OSEMs sufficiently that they are sensitive to vertical, roll, and transverse displacements of the stages. This allows us to measure more resonances with these OSEMs then we otherwise would. The optical lever isn't sensitive to any resonances the OSEMs miss, but it does add redundancy to help identify a forest of high Q pendulum resonances from spectra that include a lot of similarly shaped artifacts.
* double hang - with the main chain UIM and reaction chain PUM locked on stops, spectra of the main chain lower two stages were measured with the PUM OSEMs. In this case the optical lever would not stay in range, so the data is just the 4 PUM OSEMs.
* single hang - with the PUM on the teflon line stops, the test mass modes were measured with optically. This data was measured prior to my visit.

SUMMARY:

The data encompasses 56 resonance frequencies: 22 free quad, 16 triple hang, 12 double hang, and 6 single hang. See the attached plots and the summary of parameter changes below. In the attachment the black curves are the measured data, the blue the original model, and the red the new model. Pages 1-6 of the attachement show the diagonal top mass to top mass transfer functions. Pages 7-8 show L-P coupling and 9-10 T-R coupling. 11-13 are the frequencies of the triple, double, and single hangs respectively. 14 plots the mode frequency percent errors before the fit and 15 shows the same after the fit. The final page shows the convergence of the total error, where the error is calculated as

                  sum( [(measure mode - modeled mode)/(measured mode)]^2 ) 

The algorithm for fitting the data is Gauss-Newton, an approximation of Newton's method. The fitting code is on the svn at .../sus/trunk/QUAD/Common/MatlabTools/QuadModel_Fit/QuadPend_QuassNewton_fit_v2_H1ETMY.m.

Change in parameters from original model with the estimated convergence errors:
---------------------------------------
Inx (top mass roll inertia)                       : -1.0926 +- 2.6994 %
Iny (top mass pitch inertia)                    : 3.1636 +- 3.4396 %
Inz (top mass yaw inertia)                      : -0.86123 +- 0.65824 %
I1x (UIM roll inertia)                               : 3.9571 +- 0.77982 %
I1y (UIM pitch inertia)                             : 12.2729 +- 2.5078 %
I1z (UIM yaw inertia)                               : -0.10972 +- 0.55984 %
I2x (PUM roll inertia)                               : -2.9587 +- 0.85205 %
I2y (PUM pitch inertia)                            : 8.4597 +- 0.6904 %
I2z (PUM yaw inertia)                             : 0.011768 +- 0.3983 %
I3x (test mass roll inertia)                      : 2.2009 +- 0.77109 %
I3y (test mass pitch inertia)                    : -8.8738 +- 0.79819 %
I3z (test mass yaw inertia)                     : 0.44122 +- 0.5629 %
l2 (PUM wire loop length)                      : 8.6866 +- 1.1464 mm
l3 (fiber length)                                     : 22.1269 +- 2.6176 mm
kcn (top stage spring stiffness)              : 1.0719 +- 2.166 %
kc1 (top mass spring stiffness)              : 1.0935 +- 0.68178 %
kc2 (UIM spring stiffness)                      : 2.2795 +- 0.39067 %
kw3 (fiber bounce stiffness)                  : 9.4286 +- 0.4488 %
dn (top mass blade tip height)              : -0.20928 +- 0.303 mm
d1 (UIM blade tip height)                      : 1.8131 +- 0.56431 mm
d4 (effective fiber flexure at test mass): -4.8356 +- 0.23685 mm
---------------------------------------


DISCUSSION:

The fit of the original model was fairly descent already, except for pitch. The fit of the new model to this data is even better, especially for pitch. The worst mode frequency error decreases from 8.2% to 1.3%. Interestingly, even though only resonance frequencies were included in the fit, the shapes of the transfer functions (including zeros) all match well also. This goes for the cross coupling measurements as well. Note, the length to pitch measurement does not match the pitch to length. These should in theory be identical. Mismatches indicate measurement problems. Length to pitch has some low frequency notches that don't exist in pitch to length. Judging by the models (both before and after), I think it is likely that pitch to length is the more accurate measurement up to 4 Hz. I don't think we can believe either beyond 4 Hz. After the fit, the worst error in mode frequency corresponds to the first roll mode for both the free quad case and the triple hang case.

The inclusion of the extra resonance frequencies made a huge difference in the ability of the model to converge. In this case, a total of 21 parameters were floated. Normally, only a few at a time can be floated using just top mass data.

Many of the parameter changes produced by the fitting code seem quite reasonable. Some that are beyond what you would expect are the lengths of the fibers and the PUM wire loop. These changed by 22 mm and almost 9 mm respectively. Since the mass values are known, the only way to fit all 10 measured longitudinal modes is to adjust the wire lengths. This was achievable by floating both these wire/fiber lengths. I noticed that the default value in the original model for the PUM wire loop has the following comment: "% wire hang value - Mark Barton, 11/22/2011". I wonder if the entered value is no longer correct since the quad is not in the 'wire hang' configuration anymore. Regarding the fibers, the effective flexure length is rather complicated due to the geometry of the fibers. Perhaps some other error, like in fiber radius can mimic this. Note, the bounce mode stiffness moved by 9%.

The d4 change is also large. It is very likely this value is not physical because this parameter has significant degeneracy with both d3 and d2. Thus, the decrease of 5 mm could be spread out between all 3. d2 also has twice the sensitivity, so a small shift there can take up a fair bit of this 5 mm on its own. These degeneracies prevent the fitting code from floating these parameters simultaneously, so you simple have to pick one. d2 is sort of awkward because it is degenerate enough that it is difficult to float with either d3 or d4, but different enough that floating it instead of d3 or d4 yields different results.

DISCLAIMER:
As usual, the choice of parameters to float was made by experience and intuition. These parameter changes are not necessarily representative of reality. Though, with a fit that matches all 56 measurements to the 1% level, you might start to think that this thing is converging within some distance of reality.

COMPARISON WITH FUTURE MEASUREMENTS:
We should see how this new model holds up against L-P measurements at other stages and between stages.


NOTES:
The high frequency vertical and bounce modes were visible on the single hang and double hang measurements, but not the triple and free quad. If they were visible in all there would be 60 measured resonances. However, these modes are virtually the same from double hang to triple hang to free quad because they involve primarily displacement between the bottom two masses. Thus, the loss of information is negligible. In fact, we might be better off not including these extra bounce modes in case they emphasize bottom mass parameters over the upper masses since the same information would essentially be repeated 3 times.

J. Kissel

Given that this morning's ETM motion provided for difficult arm cavity locking and CARM hand-offing again, I've continued to pursue the long-term stability of the X ARM ISI Performance, by studying the ISI performance at 3 different times.

Here's what we learned (or re-learned) from the study today:
(1) Today (2014-02-13 17:00 UTC) was a really high-wind day. Yesterday (2013-02-13 04:39 UTC) was a medium-wind day. Two days ago (2014-02-12 01:00 UTC) was a low-wind day. The green team really liked two days ago, they were marginally happy with yesterday, and could not get anything done today.

(2) From Robert: "At the X-end, wind, which comes primarily from the Northwest and West and beats against the side of the building, tilting the building, slab, and ground. This motion is seen as increased signal in ground seismometers between 0.02 and 0.1 [Hz]. The corner station, being a shorter, squat building is much less sensitive to wind."

(3) In the current configuration, with Level 3 controllers and TCrappy blends, The longitudinal motion of the ETM suspension point is dominated by RY motion between 0.2 and 2 [Hz].

(4) The Level 3 controllers and TCrappy blends attempt to get awesome performance between 0.2 and 2 [Hz], because -- during low-wind days -- the QUAD pitch motion at the test mass between 0.3 and 0.7 [Hz] dominates to cavity motion. When larger than ~80-100 [nrad/rtHz] @ ~0.5 [Hz], the 0.3-0.7 [Hz] angular fluctuations make holding the optical gain constant difficult, and due to the poor quality of the coatings in green the cavity is more likely to fall out of lock.

(5) The wind / slab tilt does not obviously increase the ground seismometer signal between 0.3-0.7[Hz] band.

(6) During high-wind days, 0.02-0.1 [Hz] pitch motion of the ETM supersedes the 0.3-0.7 [Hz] motion, increasing the RMS motion so much so that the green VCO regularly saturates, kicking the cavity out of lock, again above ~100 [nrad] RMS.

(7) The TCrappy displacement sensor blend filter has a broad, factor-of-three-ish gain-peaking amplification hump between 0.01-0.07[Hz]. The filters were pretty good copies of L1's blend filters, where wind and 0.02-0.1 [Hz] motion is regularly pretty darn small. It's merely unfortunate that our ground motion is so volatile and different at these frequencies that we won't be able to use the exact same blend filters between the two IFOs.

(8) In order to reduce the cavity motion below the saturation limit of the VCO, one could try to just offload the bulk of the control authority to HEPI along the IPC tidal path up to, say a little past the microseism (but before the QUAD suspension resonances to keep the loop design simple). BUT the ISI's TCrappy filters blend at ~0.06 [Hz], with a *ton* of loop gain from the Level 3 isolation controllers, so any motion injected into HEPI will get ignored / suppressed by the ISI's inertial sensors above the blend frequency.

(9) The TCrappy blend filters we used in the design of the Level 3 controllers, and those particular blend filters are only "psuedo" complementary. Though this hasn't been thoroughly tested or confirmed, the belief that this means that TCrappy blends can *only* be used with the Level 3 controllers, and vice versa. The ISI had tripped one or two times while switching from this blend configuration to another, but there's not yet direct evidence that this marginal in-complementarity was cause.

(10) The ITM is consistently performing better than the ETM, as measured by the optical lever -- but remember, it's unclear whether we can trust the short-armed ETM lever to be measuring pure pitch below ~0.5 [Hz].

(11) The ITM optical lever's signal consistently has some high-frequency fuzz on it, above 0.5 [Hz] that's clearly visible in the SUM. Stefan suggests we should investigate / replace the laser head to make sure this isn't mode hopping of an old dying diode.

(12) One can monitor the blend filter status by watching the H1:ISI-ETMX_ST*_BLND_*_*_CUR_SWSTAT channels. At least in this case where we are using all TCrappy filters in FM5 of the filter banks, with the input, output, offset, and decimation buttons on, the bit-word is 7184.

In conclusion, 
- We need to pay attention to tilt, not just the translational direction of the ISI.
- Our performance is volatile, depending on the weather, so need to consider having windy-day vs. calm-day blend filters that we regularly are able to switch between without trouble.
- We still have work to do on the ISIs. Sensor correction, which has not been commissioned on either X ARM platforms can perhaps help, but maybe not if we are blending so low. We should most certainly investigate a set of blends with less gain peak in the wind band.

Sheila, Alexa, Stefan

In the afternoon we were fighting higher than usual winds, which troubled us in two ways: excess ETMX pitch motion at its pitch frequency, and ISI blend filter excess noise around 0.05Hz X direction, leading to a saturation of the PDH error signal. We implemented two patches:

1) We re-engaged the ETMX oplev damping. This did a good job at suppressing the ETMX pitch eigenmode.
2) We realized that increasing the tidal feed-back to HPI won't help us with the ISI-induced motion at 0.05Hz - the blend filters will by design start isolating the test mass, limiting our tidal UGF. Thus we switched back to ETMX top mass feed-back, and added a broad resonant gain (see snapshot) around 0.05Hz. This seemed to get us about a factor of two in range for the green PDH lock - just enough to prevent saturation.
3) Right after implementing this, the winds also started to come down.

With this we started looking at the COMM_handoff script that Sheila and Alexa had put together:
1) We realized that we only had 11deg phase margin. This was due to the bleed-off to the penultimate mass (M1), which effectively acts as a boost filter. Jeff had set it to 7Hz, with a M2_LOCK_L gain of 0.1. I lowered it by 3dB to gain back phase.
2) To gain back more phase margin during the turn-on, we set the the CARM gain initially to 160 (was set at 80). This brings to the x-over UGF to 25Hz, and lots of phase.
3) After the hand-off the CARM gain is again lowered to 100 (x-over UGF of 17Hz) to allow turning on the roll and bounce mode notches in MC2.
4) Finally the script now also turns on the CM BOOS (compensation) filter and the end.
5) I also uncommented the initial ezcaservo, the read statement, and the gain stepping. For the latter I also increased the step-wait time to 0.3sec because unmatched electronic offsets in the gain steps tend to ring the mode cleaner for a little bit.


Attached are
1) A snapshot of the filter settings for the ETMX pitch OL filter and the tidal feed-back loop.
2) The ALS-COMM x-over OLG measurement - the inal setting is four dB lower than the measurement (see cursor).
3) ETM optical lever and green PDH control signals (uncalibrated). 


Below is a copy of the current COMM_handoff script - it is ready for a Guardian now:
#!/bin/bash

ezcaservo -t 10 -s 0 -g -1 -f 0.1 -r H1:ALS-C_COMM_PLL_CTRLMON H1:IMC-VCO_TUNEOFS &
sleep 2
#COMM PLL boost OFF
caput H1:ALS-C_COMM_PLL_BOOST 0

#prepare CARM
ezcaswitch H1:LSC-CARM FMALL OFF FM8 FM1 ON
#caput H1:LSC-CARM_GAIN 80
# initally to 160 for extra stability during power increase (Stefan 20140213)
caput H1:LSC-CARM_GAIN 160

#prepare AO path
caput H1:IMC-REFL_SERVO_IN2POL 0
caput H1:IMC-REFL_SERVO_IN2GAIN 16
caput H1:IMC-REFL_SERVO_IN2EN 1

#prepare refl board
caput H1:LSC-REFL_SERVO_IN1GAIN -32 
caput H1:LSC-REFL_SERVO_IN1EN 1
caput H1:LSC-REFL_SERVO_FASTGAIN 6

#prepare MC2
caput H1:SUS-MC2_M3_LOCK_L_LIMIT 6400000
caput H1:LSC-MC_TRAMP 2
ezcaswitch H1:SUS-MC2_M3_ISCINF_L FM6 FM7 OFF
sleep 2

#turn down MCL DC gain
ezcaswitch H1:LSC-MC FM1 ON
#echo "Press enter to continue"
#read
#turn up COMM gain
# Reduced to 0.3sec steps - IMC was ringing a bit (Stefan 20140213)
ezcastep -s 0.3 H1:LSC-REFL_SERVO_IN1GAIN +1,41
#used to be 32 steps

#low frequency boost
ezcaswitch H1:LSC-CARM FM5 ON 
# CARM gain to 100 - middle of phase bubble (Stefan 20140213)
caput H1:LSC-CARM_GAIN 100
sleep 2
# turn the MCL feedback off
caput H1:LSC-MC_GAIN 0
# make the CARM boost up
ezcaswitch H1:LSC-CARM FM4 ON


ezcaswitch H1:SUS-MC2_M3_ISCINF_L FM6 FM7 ON
ezcaswitch H1:SUS-MC2_M3_LOCK_L FM3 OFF
#COMM PLL boost 
caput H1:ALS-C_COMM_PLL_BOOST 1

# CM board BOOST (compensation) ON  (Stefan 20140213)
caput H1:LSC-REFL_SERVO_COMCOMP 1

aligning the red trans path.

HAM4-ISI was getting mechanically preped by Hugh, Jim and Mitch today.

Meanwhile I installed all the IN/OUT filters, loaded the coordinate transform matrices, all the generic HAM-ISI blend filters, the generic damping loops and the Lv1 Isolation loops. All work properly, but the Isolation loops are unstable. I suppose something may be mis-wired as we went very fast.

Transfer functions are running overnight on HAM4-ISI, we will know for sure tomorrow.

Hugo has BS

ITMY is Isolating at Lvl3.  Stage1 blend is T250son rot dofs, T40NO.44 on X & Y, & T100NO44 on Z.  Stage2 has Lvl3 with 750 blends except on X & Y which have 250s.

Stefan has the Xarm and isn't complaining.  ITMX is Lvl3 TCrappy. ETMX is at Lvl3 on Stage1 & Lvl2 on Stage2 w/ TCrappys--normal logged state.

17:44 DAQ restart. supporting new h1asc, h1ascimc, h1lsc models. This has fixed the IPC errors ASC was experiencing.

Mitchell, Justin & Hugh--we got the bulk of the payload in position by 11am per D1001132, no real issues there except no 2.5kg mass exists.

Justin and I tagged out and Jim & Mitchell did final floating & balancing and required locker adjustments.  We could be testing generic controls or running transfer functions tonight.  HEPI Actuator attachment has been pushed back to allow Guardian testing.

EE (Phil & Aaron) fed cables and I attached most of them to the TS Mock Feedthrus.  Still need to connect the Coil cables once names are verified.  All the In-vac cables are connected to the feed thru.  Still need to position & connect up the CPS satellite rack.  Also need to dress up the T240 cable from Stage1 to Stage0 and other misc cable securing.