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Entry  Tue May 24 11:04:53 2022, JC, Update, VAC, Beginning Pumpdown PUMPDOWN-2022-05-24_16-57-59.pngC1VAC_Screenshot_2022-05-24_16-59-27.png
    Reply  Wed May 25 16:38:27 2022, yuta, Update, SUS, Suspensions quick health check Screenshot_2022-05-25_16-46-13.pngOSEMcheck.JPG
       Reply  Tue Jun 7 17:26:21 2022, yuta, Update, SUS, ITMY ULCOIL mystery not solved ULCoilInductance.JPGULCoilResistance.JPGWrongSetting.JPG
          Reply  Tue Jun 7 19:13:12 2022, yuta, Update, SUS, Agreement on suspension damping loop polarity conventions NoteBeforeChanges.JPG
             Reply  Fri Jun 10 15:02:04 2022, yuta, Update, SUS, Servo gain sign flipped for MC1 WFS relief Screenshot_2022-06-10_15-04-46.png
          Reply  Tue Jun 7 19:40:45 2022, Anchal, Update, SUS, ITMY changed output matrix to disable use of UL coil ITMY_PIT_to_POS-PIT-YAW_Coupling.pdfITMY_YAW_to_POS-PIT-YAW_Coupling.pdf
          Reply  Wed Jun 8 18:16:20 2022, yuta, Update, SUS, ITMY ULCOIL mystery: Coil driver swap test Screenshot_2022-06-08_18-10-44.pngSWAP.JPG
             Reply  Thu Jun 9 23:08:39 2022, rana, Update, SUS, ITMY ULCOIL mystery: Coil driver swap test 
                Reply  Fri Jun 10 13:02:14 2022, yuta, Update, SUS, ITMY ULCOIL mystery: Coil driver swap test 
                   Reply  Fri Jun 10 15:04:23 2022, rana, Update, SUS, ITMY ULCOIL mystery: Coil driver swap test 
                      Reply  Fri Jun 10 21:10:01 2022, yuta, Update, SUS, ITMY ULCOIL mystery: Coil driver swap test 
                         Reply  Wed Jun 15 17:03:17 2022, yuta, Update, SUS, ITMY ULCOIL issue solved, loose connection in sat amp box Measured16Ohms.JPGSatAmpTerminator.JPGBAD.JPGSUCCESSFUL_KICK.png
       Reply  Wed Jun 15 15:45:37 2022, yuta, Update, SUS, LO1 LLCOIL now working, it was loose connection Measurement.JPGBAD.JPGScreenshot_2022-06-15_15-59-05.png
    Reply  Wed Jun 15 07:26:35 2022, JC, Update, VAC, Beginning Pumpdown 
Message ID: 16899     Entry time: Tue Jun 7 19:40:45 2022     In reply to: 16896
Author: Anchal 
Type: Update 
Category: SUS 
Subject: ITMY changed output matrix to disable use of UL coil 

Since UL coil actuation is lost, we modified the output matrix of ITMY to use only UR, LR and LL face coils for POS, PIT and YAW actuation. The output matrix was changed to following:

  POS PIT YAW SIDE
UL 0 0 0 0
UR 1 1 0 0
LL 1 0 1 0
LR 0 -1 -1 0
SIDE 0 0 0 1

 

 

 

 

 

After this change, the damping was still working as good as before. I took PIT to POS/PIT/YAW and YAW to POS/PIT/YAW coupling measurements by exciting C1:SUS-ITMY_ASCPIT[YAW]_EXC and seeing effect at C1:SUS-ITMY_SUS[POS/PIT/YAW]_IN1 when the damping loops were off. Attached are the results. We were able to reduce PIT to YAW and YAW to PIT coupling by 10 dB by this simple change in output matrix. More coil balancing or off-diagonal termsmight help more and should be attempted if required. The coupling to POS did not change much.

Note that attachment 1 shows transfer functions from excitation point to the DOF sensing inputs while attachment two looks at ratio of C1:SUS-ITMY_SUS[POS/PIT]_IN1 to C1:SUS-ITMY_SUSYAW_IN1 which is the actual quantity of interest. I didn't repeat the PIT measurement due to lack of time.

Also note that all such measurements are being recorded in our new measurements git repo. We'll populate this repo with diaggui template+data files as we do measurements.

Attachment 1: ITMY_PIT_to_POS-PIT-YAW_Coupling.pdf  12 kB  Uploaded Tue Jun 7 20:51:16 2022  | Show | Hide all | Show all
Attachment 2: ITMY_YAW_to_POS-PIT-YAW_Coupling.pdf  12 kB  Uploaded Tue Jun 7 20:51:32 2022  | Hide | Hide all | Show all
ITMY_YAW_to_POS-PIT-YAW_Coupling.pdf
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