IP-T loop check for X-arm suspensions

[YoshinoriFujii]

background

• For IP-T

• For BF-L(/T)

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Todo

• For IP-T:

  • [x] modify the loops and suppress the residual peak to the same level of IP-L loops:
  • [x] ETMX
  • [x] ITMX

• For BF-L/T:

  • [ ] modify the loops to velocity damping one and see what happens:
  • [ ] ETMX
  • [ ] ITMX
  • see https://github.com/YoshinoriFujii/Weekly-task/issues/26

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Note:

• ITMY IP residual looks larger compared t the others. https://github.com/YoshinoriFujii/Weekly-task/issues/25

[YoshinoriFujii]

log of 2019.9.22 work

• at about 10:30, ETMX-state was in ALIGNED.
• IR is not reached to EX, to be checked with commissioners.

[YoshinoriFujii]

ETMX IP-T

• Starting point:

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• legend

  • (REF): before the modification
  • w/ (REF): after the modification

• 1st modification:

  • blue to red:

• result with gain 1.0

• with gain 1.5

  • gain 1.5 case is selected here.
  • Then now,

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• Anyhow the RMS was suppressed according to the LVDT signal.
• [ ] But, the geophone signal was not much suppressed at 0.2Hz.. why?
• [ ] from 1Hz to 10Hz, noise injected level was increased. This should be okay but should be checked with simulation?
  • since thi is the most upper stage and this is T dof..

[YoshinoriFujii]

btw, the geo calibration filter has phase delay by at 0.1 Hz:

• Due to the low frequency cut-off, there is a phase delay by ~ 23deg.:
  • red: ideal one, 3.4deg at 0.1 Hz
  • blue: actually installed one: 26.25deg at 0.1Hz.
  • the difference is 22.85deg at 0.1 Hz.

• At least, the amplitude should be same as the ideal one at above 0.1Hz.

[YoshinoriFujii]

ITMX IP-T check:

• At the starting point:
  • why the OUTPUT was being held?

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• the filter was changed from blue to red colored one.

• with gain 1.5

  • there was not big differences in the spectra before/after the modification.
  • [ ] Try to check TF from ground to the stage and compare...
  • At 0.4 and 0.65 Hz peaks, there was a suppression (it seemed).
  • Here, in any case, To set same configuration for all the suspensions, I have selected red colored filter.