Agenda/Minutes of the VIS Meeting on 2019/8/2

2019/8/2 14:00 -

Zoom Meeting

Participants:

Progress report

Type-A

Past week report

* Input from YF:

• ITMY repairing work: see the klog#9732, #9765 and their thread.
  • The stepper motor was calibrated. The coefficients should be available for other suspensions.
  • Main concern (for me) is if the BF-Yaw TF is as designed or not. I will do a measurement for this kind of stuffs tomorrow early morning.
• Thanks to Kokeyama-san, the Type-A common guardian was created.
  • klog#9762 says that:
    • For ETMY it was confirmed that the guardian worked properly.
    • For ITMX/ETMX, the new guardian was installed but they are to be tested.
    • For ITMY, still old one is running.
  • About payload damping:
    • For ETMX, ETMY, the servo system suppress the angular fluctuation to about 0.1urad in RMS when there is no RM-chain mode is excited. Some of the damping loops are to be created (for ETMX), for like 2.5Hz mode in L etc.
    • It was also found that some of the ETMX/ITMX filters became unstable just after external disturbance like earthquakes. Actually the oplev signal became saturated.
      • Then I found that the photo-sensors (PSs) damped the dominant mode when the large oscillation (for the oplevs) was excited, even with the PSs of ETMX[1]. This was tested in only MN-L though.
      • PS-damping state should be added to the guardian, just for a case where a large oscillation is excited.
      • Using the oplev-loops after the system calmed down will improve this issue.
• About IP and BF controls,
  • I have started a preparation for a feed-forwarding test which uses seismometer signals for IP- or BF-LVDTs. This is just for a local control.
  • If you change the configuration of the IP or BF control filters, please report in klog.

[1] The PSs of ETMX has the most terrible noise level. (I will post a log for this.)

Plan for coming weeks

Type B

Report for the week 7/29

• I offloaded fishing rods in GAS filters and IPs in BS and SRM.
• I implemented scripts for the automatic measurement of amplitude spectral densities (ASDs) of suspension sensors (usually used for residual motion estimation).

• Highlights of recent ASD measurements can be found in entry 9726. The residual motion was measured in ALIGNED and FLOAT states.

  • In SRM and SR3 the motion in ALINED state was smaller than in FLOAT state, which is expected. See entries and respectively .

  • In SR2, the motion in pitch and yaw displacement is larger in ALIGNED state, and the longitudinal velocity is the same in both states.

  • In BS, the longitudinal displacement is the same in both states.

• Some features of the measured ASDs are the following:

  • In SRM, SR3 and SR2 in pitch there is either a large bump (SRM and SR3) or excitation (SR2) between 0.3 Hz and 1 Hz. 9756.

  • In SRM pitch the control system seems to be introducing noise in two frequency bands, before and after the bump. See 9756.

  • In SR3 pitch the control loops seems to be introducing noise between 1 Hz and 2 Hz. See 9755.

  • In SR2 pitch the control loops seems to be introducing noise between 0.380 Hz and 2 Hz. See 9752.

  • In SR2 yaw the control loops seems to be introducing noise between 0.045 Hz and 0.230 Hz. See 9752.

  • In SR2 longitudinal speed the control system seems to excite a large peak at 0.705 Hz. See 9752.

Plan for the week 8/5

• Check the BS amplitude spectral densities.
• Check the longitudinal degree of freedom in SRs.
• Aim to identify noise sources.

Type-Bp

Past week report

Plan for coming weeks

OMMT & OSTM

Past week report

Plan for coming weeks

VIS electronics

Past week report

Plan for coming weeks

Other site works

Safety

• Incidents:

Discussion

Travel Plans

• Travel (Week of 8/5):
  • Takahashi:
  • Sato:
  • Hirata:
  • Shoda:
  • Fujii:
  • Tanaka:
• Travel (Week of 8/12):
  • Takahashi:
  • Sato:
  • Hirata:
  • Shoda:
  • Fujii:
  • Tanaka:

Next meeting

On 2019/8/9(Fri)