H1 SUS RM1 and RM2 Damping Loop Open Loop Gain / Loop Suppression After Gain Drop -- Assuming Loops are SISO...

J. Kissel, O. Patane, E. Capote

After we dropped the RM damping loop gains (see LHO:84590), we remeasured the open loop gain transfer function (OLG TF, or just G) and loop suppression TF [ 1 / (1+G) ], in order to see / confirm that the frequency dependence in the 1-3 Hz region changes, and hopefully ''reducing'' it back to its 2022 response and regaining phase margin / reducing loop suppression magnitude.

The magnitude of the OLG TF decreased by the expect value.
The magntidue of the loop suppression also reduced back to virtually identical values.
While yes, the phase margins in the OLG TFs agree with the loop suppression, the frequency dependence of the phase of the OLG TF did *not* restore to original frequency dependence.
I again suspect the change in cross-coupling transfer functions -- namely the influence of P on the L loop and the influence of L on the P loop has changed because the underlying mechanical system has changed in this frequency region. 
Said differently, we only ever look at the on-diagonal OLG TFs. If we look, e.g. at the change in IN1 P / IN2 L (in the presence of L EXC), we might be able to get a better story. 

Oli's retaking the damped plant transfer functions [ P / (1+G) ], which will be the final metric to see if this gain adjust is ''good enough.''
Elenna will be taking before vs. after DC centering loop open loop gain transfer functions to also confirm if / whether this is ''good enough.''

ALS-DIFF PLL offsets for FIND_IR changed order

Mr Todd, Georgia

We've been losing lock from DRMI a lot today and we noticed that the FIND_IR state was taking a few minutes between finding the x-arm IR and y-arm IR. We checked the ALS_DIFF guardian, and found in the stored PLL offsets (alsDiffParams.dat), the offset we were ending up (around 400) was second on the list, so we reordered the list so this is the first place the PLL goes. Now it is:

{"diffOffsets": [407.0, 3242.0, 388.0]}

Hopefully this saves valuable minutes going forward...

PSL 10-Day Trends

FAMIS 31087

I touched up PMC and FSS alignments last Wednesday (alog84512), but otherwise no major events of note.

Tuesday Ops Day Shift Update.

TITLE: 05/27 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Planned Engineering
CURRENT ENVIRONMENT:
    SEI_ENV state: CALM
    Wind: 10mph Gusts, 3mph 3min avg
    Primary useism: 0.02 μm/s
    Secondary useism: 0.11 μm/s
QUICK SUMMARY:
Running the Baffle Align scripts using Camilla's alog for instructions.
Misaligned the ITMs and ETMS then ran TMS Baffle Scripts

TMSX new positions:

Using measured BPD values to center TMSX.
Old offset pitch -104.14244834736331 and yaw -109.79604786748453
New offset pitch -103.72575987167198 and yaw -110.85679978788264
Turning off the test offsets to TMSX. (should be P -33.7, Y 30.5)
TMSX dither alignment finished!

TMSY new positions:
Using measured BPD values to center TMSY.
Old offset pitch 70.15420064392093 and yaw -271.5893273344493
New offset pitch 69.75239629431661 and yaw -270.55214428728334
Turning off the test offsets to TMSY. (should be P -40.5, Y -33.6)
TMSY dither alignment finished!

Aligned ITMs and ran ITM Baffle align scripts

ITMX positions:  
Old offset pitch -101.53678089232399 and yaw 102.91810605767766
New offset pitch -101.2027177125818 and yaw 105.15047590583615
Turning off the test offsets to ITMX. (should be P -20.0, Y -14.7)
ITMX dither alignment finished!

ITMY Positions:
Using measured BPD values to center ITMY.
Old offset pitch -23.505941056968442 and yaw -20.27121873667067
New offset pitch -21.064721940378305 and yaw -19.945998085295358
ITMY dither alignment finished!

Elenna did an Initial_Alignment with out Green Camera.

Jenne D &  Camilla, Calibrated the PSL Rotation stage.

16:58 UTC Nitrogen truck Heading Down Y Arm to fill CP3

GRB-Short E572030 17:14 UTC

HAM7 ISI WD Tripped 17:14 UTC Likely due to Ken and Fil's EE work.

Locking the IFO!!!!
Manually requesting DRMI states and Pausing. So far the Highest we have reached is ENGAGE_DRMI_ASC[103]

FMCS alert : Fire pump 1 is on 17:33 UTC
FMCS alert : Fire pump 2 is on 17:44 UTC

VACUUM Alert for H1:VAC-LY_X0_PT100B_PRESS_TORR -   "That was Travis" ~ The Great Philosopher Gerardo.

2 Tours rolled through the control room and out to the overpass.

Norco N2 fill on CP1

Monthly Hanford alert test Expect Sirens at 20 UTC

H1 SUS RM1 and RM2 Damping Loop Gains Multiplied by 0.75x and 0.6x, Respectively

J. Kissel, O. Patane, S. Dwyer, E. Capote

Given the assessment of from LHO:84585, and its comment LHO:84587, I've reduced the gain of the RM1 and RM2 damping loops by a factor of 1.4x and 1.7x, by multiplying the ''gain_[DOF]'' filters by 0.75x and 0.6x, respectively. We intend to remeasure the open loop gain TFs and loop-suppressed plant measurements as the opportunity arises between lock acquisitions.

Here's the diff of the filter file design string, which has been now committed to the userapps svn as of the following commit rev:
    /opt/rtcds/userapps/release/sus/h1/filterfiles$ svn diff H1SUSHTTS.txt | grep DESIGN | grep -B 1 +#
    -# DESIGN   RM1_M1_DAMP_L 3 gain(0.01)gain(70)
    +# DESIGN   RM1_M1_DAMP_L 3 gain(0.01)gain(70)gain(0.75)
    --
    -# DESIGN   RM1_M1_DAMP_P 3 gain(2e-05)gain(70)
    +# DESIGN   RM1_M1_DAMP_P 3 gain(2e-05)gain(70)gain(0.75)
    --
    -# DESIGN   RM1_M1_DAMP_Y 3 gain(5e-06)gain(70)
    +# DESIGN   RM1_M1_DAMP_Y 3 gain(5e-06)gain(70)gain(0.75)
    --
    -# DESIGN   RM2_M1_DAMP_L 3 gain(0.01)gain(70)
    +# DESIGN   RM2_M1_DAMP_L 3 gain(0.01)gain(70)gain(0.6)
    --
    -# DESIGN   RM2_M1_DAMP_P 3 gain(2e-05)gain(70)
    +# DESIGN   RM2_M1_DAMP_P 3 gain(2e-05)gain(70)gain(0.6)
    --
    -# DESIGN   RM2_M1_DAMP_Y 3 gain(5e-06)gain(70)
    +# DESIGN   RM2_M1_DAMP_Y 3 gain(5e-06)gain(70)gain(0.6)
    /opt/rtcds/userapps/release/sus/h1/filterfiles$ svn commit -m "Adjusted RM damping loop gain to account for increase in plant TF magnitude after Apr-Jun 2025 vent. See LHO aLOGs 84585, 84587, and 84590." H1SUSHTTS.txt 
    Sending        H1SUSHTTS.txt
    Transmitting file data .done
    Committing transaction...
    Committed revision 31533.

I then
- turned OFF the damping loops' output switch,
- loaded the coefficients
- turned ON the damping loops' output switch.
all while the DC centering loop alignment integrator's DAC request was still in place. That DAC request was in the 100s of Euler Basis DAC counts (the outputs of the LOCK banks), and the damping loops' DAC request was in the 1s of Euler basis DAC counts (the outputs of the DAMP banks). The damping loops request a trivial amount of DAC range.

Hanford Site Call

Monthly Hanford Alert test Expect Sirens at 20 UTC (1PM local).

Monthly fire pump test

The monthly no-flow fire pump test was conducted this morning from ~10:30 to 11:00.

RM Damping Loops Stable, but Phase Margins are Smaller; More Gain Peaking and Damped Plant is Changed

J. Kissel, O. Patane

Hearing hints that ''issues'' still remain with the RM damping loops, we continue to dig in the list of actions from LHO:84462. Here, we report the current status of the damping loop open loop gain transfer functions (and corresponding loop suppression). We several things:

(0) The open loop gain transfer functions (OLG TF, or just  G) confirm that the damping loops are stable, and regardless of the individual sign quirks of the sensors and/or actuators in the current analog / digital configuration (currently the same as described in LHO:84462).

(1) The OLG TF magnitudes have larger overall scale magnitude in all DOFs for both RM1 and RM2. Could be expected, as we completely removed the OSEMs and re-centered them during the Apr - Jun 2025 vent (see LHO:84178).

(2) Around the UGFs, between 1 - 3 Hz, the OLG TF's frequency response has changed dramatically. I'm attributing this to the dramatic change in magnitude of the cross-coupling between DOFs -- see pages 4 thru 9 of RM1 and RM1 ''health check'' undamped plant transfer functions, P, from LHO:84543. Also expected because we completely removed the OSEMs and re-centered them. In hopes to investigate the magnet polarity in the actuator, we also grabbed the flag/magnet system and tried to remove those; so it's also quite possible that the also changed position / alignment of the flag/magnet changed too (even though they couldn't completely remove it), augmenting the cross-coupling.

For suspensions "so simple" we usually try our hardest to ignore that the plant is a full 3x3 matrix. Since the beginning of time, we treat the damping loop plants as a diagonal matrix such that we can treat each DOF as a SISO loop and use an independent controller for each DOF. But clearly there is MIMO action going on here, as the diagonal TFs linked from those same plots of LHO:84543.

(3) Both (1) and (2) means that (the phase margins of G) and/or (the loop suppression transfer functions [1/ (1+G)]) have changed for the worse. If you want to quantify it with gain peaking alone, both RM1 and RM2's P to P loop suppression are the worst, increasing from magnitudes of ~1.5x to 3.5x. But, don't do that. Look at the plots. 

Because the frequency response of G and [1/(1+G)] has changed ''just'' changing the overall loop gain won't return the frequency response to the expected value. It'll likely be ''good enough'' for the RM damping loops, but ...

(4) ... given that the damping loop's loop-suppression is dramatically different in the 1-3 Hz region, that also means that frequency response of the loop-suppressed plan, P/(1+G) -- which serves as the plant, P', for any *other* loops wrapped around it -- has changed. *That* could very well be the ''issues'' with the REFL WFS detector's DC centering loops -- which may have UGFs in the 1-3 Hz region.

More to come!

Table of OLG TF scale factor changes (measured at 3 Hz):
                2022-06-21     2025-05-27      Ratio (2025/2022)

    RM1   L     0.0874721       0.121968          1.3944
  
          P     0.173183        0.242202          1.3985

          Y     0.11679         0.153077          1.3107


    RM2   L     0.0659664       0.111818          1.6951
     
          P     0.112373        0.205585          1.8295

          Y     0.0873937       0.142127          1.6263

Looking at the 0.1 Hz values of the RM1 and RM2 plant measurements from LHO:84543, the ratio of undamped plant magnitudes are similar
                   2022-06-21         2025-05-27          Ratio (2025/2022)
                [m/N] or [rad/N.m]  [m/N] or [rad/N.m]
    RM1   L        0.088                 0.106               1.2045
  
          P      144.8                 184.1                 1.2714

          Y      136.5                 171.3                 1.2549


    RM2   L       0.068                  0.104               1.5294
     
          P      95.1                  162.2                 1.7056
 
          Y     101.1                  161.4                 1.5964


So, we'll likely drop the RM1 gain by 1.4x, and drop the RM2 gain by 1.7x.
i.e. multiply the current damping loop gain filters by 0.75x and 0.60x.

PSL Rotation Stage Re-calibrated

Jenne, Camilla

After Ryan re-calibrated the PSL rotation stage in 84553, we still weren't getting the correct IMC_IN power. This morning Jenne and I checked this and it seemed that our original powers were too low and the bootstrapping brought it too high.  We re-calibrated, results attached. SDFs accepted.

After testing the power seems to be a lot better, we expect that it wa just far off enough when Ryan initially calibrated that it needed a second iteration.

We tested going to 2W and 10W from powers below and above and see a little hysteritis in the measured power. However, as we normally are increasing powers by increasing angle, this hysteresis shouldn't be an issue as this is the direction we calibrate in.

Mid station chiller plants started

The chiller systems at the mid stations were started this morning for the season. 

Tue CP1 Fill

Tue May 27 10:09:04 2025 INFO: Fill completed in 9min 0secs

 

Delay Measurements of REFL/POP RF Detectors

Attached is the analysis of the TDR and delay measurements for the REFL and POP RF sensors.

The 2 columns labeled "phase TDR" and "correction phase" are the calculated phase shifts from the TDR and phase measurements, respectively. A longer cable between the RF sensor and the demodulator will make this phase shift more negative (modulo 360°).

If I got the signs correct, this number needs to be subtracted from the current phase shift values. This is indicate in the highlighted column labeled "new Phase". If not, one can try the column "wrong Phase".

ALSX and ALSY green arm powers on ISCT1 <2mW

Matt, Camilla, Sheila

Once the X and Y green arms were locked, Matt and I measured their powers on ISCT1, straight after the prism.  Sheila took H1:ALS-{X,Y}_REFL_LOCK_TRANSPDNORMTHRESH from 0.8 to 0 so that we the arms would stay locked while we blocked the beams. Measured:

• 1.25mW on ALSX
• 1.75mW on ALSY

Tuesday Ops Day Shift.

TITLE: 05/27 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Planned Engineering
OUTGOING OPERATOR: Tony
CURRENT ENVIRONMENT:
    SEI_ENV state: CALM
    Wind: 6mph Gusts, 4mph 3min avg
    Primary useism: 0.01 μm/s
    Secondary useism: 0.10 μm/s
QUICK SUMMARY:
The goal is to start locking and follow the steps outlined in the commissioning document https://docs.google.com/document/d/1P6JXVV_bhdN2M5k2PLoa0tu-AmY-PiC98zZ0nzBIJ2I/edit?tab=t.0
H1 Is currently going through a manual Initial alignment " Without Green Cameras".

 

 

Restarted IOCs on opslogin0 following reboot

We are down to two temporary EPICS IOCs running on opslogin0 which need to be restarted following reboot of opslogin0:

digivideo_dummy_ioc: We moved some critical cameras to the new server, but found that they needed image masking so they were returned to h1digivideo2, but the DAQ is expecting the new server's channels. This IOC provides the missing channels.

vac_ham1_pressure_converter_ioc: The Beckhoff calibration for HAM1 pressure is off by two orders of magnitude, this IOC creates a H1 HAM1 Torr channel, calculating the pressure from the gauge's raw voltage reading.

Workstations updated

Workstations updated and rebooted.  This was an OS packages update.  Conda packages were not updated.

Mon CP1 Fill

Mon May 26 10:11:15 2025 INFO: Fill completed in 11min 11secs