Agenda/Minutes of the VIS Meeting on 2019/8/2
2019/8/2 14:00 -
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.
- klog#9762 says that:
- 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
- clarify the task assignments for Type-A team again. (To be honest, *I* would like to be away from the VIS duty a bit more..)
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)