Agenda/Minutes of the VIS Meeting on 2019/6/14

2019/6/14 13:30 - 14:53

Zoom Meeting

Participants: Terrence, Takahashi, Hirata, Shoda, Ishizaki, Sato, Aso Tanaka, Mark, Fujii

Progress report

Type-A (Takahashi)

Past week report

• Just health check of ITMY suspension, mainly for the payload.
  • The background is:
    • [1] TM/MN oplev signals much coupled.
    • [2] BF-Yaw TF was weird.
  • For [1], MN, TM was steered by motor and coils successfully. There was coupling though. Sinusoidal oscillation was observed. The electrical circuits like coil drivers was sane. (A bit weird stuff was found though it did not look the main reason.) We start to give up for this investigation. If the BF-TF becomes okay, we will ignore this issue, it seems.
  • For [2], being investigated. Pulling up/down the BF, the payload did not solve [1]. Impact to [2] is being investigated. Steering IP in about 400um did not improve the situation. Steering IP with larger distance is to be tested.
• damping/dc filters are being installed to ITMX.
  • MNY_oplev damps 0.35Hz(Y), 1.69Hz mode(Y). For 1.14Hz mode(Y), this worked though the decay time is still not so short.
  • MNP_oplev damps 0.74Hz(P), 0.85Hz mode(P), 0.97Hz(P) . This was not so effective to 0.63Hz mode(L), not tested for 7.75Hz mode(P).
  • TML2MNL(at P09) is for 1.47Hz mode(Y)
• TMP2MNP-dc control was installed to the suspensions except for ITMX.
• Some of the loops are updated by Terrence, it seems.
• Guardian for ETMX was installed and it is working finely, thanks to Shoda-san.
  • This guardian takes care just safe/undamped/tower-damped now.
  • Some modification (at least one) is necessary around the shutting down procedure though.
  • After this modification, this guardian will be installed to other suspensions.
• TM/IM/MN coil balancing is now finishing except for ITMY suspension, thanks to Yamada-kun.

Plan for coming weeks

• Modify the RT-model for type-A, add the loops like TM->MN etc again. They were removed in a couple of weeks ago.

• Tidy up the damping/dc filters.

Type B (Mark)

Report for the week 6/10

BS

• Type B inertial damping. This means geophone diagonalization, blending filter optimizing, etc.

• Optimization gives an odd looking blending filter that blends at ~120 Hz, but works fine in IP L. 9184

• During PRMI lock, BS residual motion was too high that misaligned the beam too much from time to time, making the lock unstable. 9199

• To fix this, I improved OL windshield so I can study the residual motion of the BS. Then I copied IP L blending filter to IP T and IP Y and cranked up the IP damping and TM damping gain. This suppressed the residual motion so the requirements are met. After this, the BS was not causing any problem to the lock anymore. 92199235

Guardian

• Upon request from the commissioning team, we changed the guardian so the aligned state engages OL DC IM2TM control and the setpoint will be taken to be a reference channel that is created by Nakano-san to record to OL good position. While in the misaligned state, we use a large OPTIC ALIGN offset to the optic very far away (hence the OL will not be useful). 9196

Plan for coming weeks

• Still commissioning.
• Design lock filters to lock the IPs to the ground for the ground motion common-mode reject study? (In discussion)

Remainder from last week:

• SR3 Inertial damping, windshield.
• Better VIS monitor.
• Type B operation manual

Type-Bp (Shoda)

Past week report

• Updated the guardian script so that each guardian script refer one master script, TypeBp.py.

• Tested the auto-offload script for PR GAS filters.
  • It will actuate the stepping motor by 20,000 counts if the position is 200 um away from the target during undamped, or the DC output is over 2,000 counts when controlled. It will repeat the actuation till the keystone comes in the range.
  • It can be used for IP as well. We need to test it.

Plan for coming weeks

OMMT & OSTM (Takahashi)

Past week report

• Designed the OSEM holder and the pillar for the OSTM suspension.
• Prepared a temporal support to replace the pillars.
• Checking the layout in the OMC chamber.

Plan for coming weeks

VIS electronics (Tanaka)

Past week report

Plan for coming weeks

Other site works

Safety

• Incidents:
• Foreseen risks
  • Type-A:
  • Type-B:

Discussion

• Ground motion common-mode rejection.
  • Just locking the IP to the ground may introduce too much noise at high frequencies.
  • Make a higher frequency blending filter ?
  • Common mode rejection may be degraded by the difference between the suspension chain responses.
• DAQ channel reduction
  • We agree to Lucia's suggestion to record IP_DAMP_*_IN
  • We also agree to all the suggestions by Mark
  • Shoda-san will update the document according to the above.
  • Recording all the VIS channels with 256Hz will be difficult from the available resource
    • We still have 16Hz EPICS records.
• Watchdog implementation
  • Simply putting too much actuation to the TM causes the entire suspension to trip. Then it takes a long time to recover the suspension control, making the commissioning work slow.
  • We can separate the watchdog of the payload part and the tower part with modifications to the real time model.
  • We also need to modify Guardian to recognize "Payload only tripped" state.

Travel Plans

• Travel (Week of 6/17):
  • Takahashi: 6/18-19
  • Sato:
  • Mark:
  • Hirata:
  • Shoda:
  • Fujii: 18-21
  • Tanioka:
  • Tanaka:
  • Terrence:
• Travel (Week of 6/24):
  • Takahashi:
  • Sato:
  • Mark:
  • Hirata:
  • Shoda:
  • Fujii: 24-28
  • Tanioka:
  • Tanaka:
  • Terrence:

Next meeting

On 2019/6/21(Fri)