* (Work log on July 30 and 31)
[Okutomi, Fujii, Sato]
TL;DR
- F0 yaw motor ---> became available
- Stepper motors of IP H1, H2, H3, and F0 yaw: calibrated
- IP and BF LVDT polarities: confirmed
- BF LVDT vertical positions: slightly improved
- Cable tensions below the BF: slightly relaxed
- BF yaw picomotor: quickly inspected but still not working
- ITMY tower current status: IP and BF are mechanically fixed
What we did
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We found that the F0 yaw motor was actually stuck.
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This malfunction was resolved by rotating the bellows by hand so that it has the nominal expansion.
- cf. JGW-D1809225: Yaw stepper motor drive unit for Type-A and Type-B TF
- https://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/private/DocDB/ShowDocument?docid=9225
- Now the motor driving became available again.
- We added a threaded PEEK part to the motor unit of the ITMY to reduce the friction in the motor driving.
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This malfunction was resolved by rotating the bellows by hand so that it has the nominal expansion.
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We calibrated the accessible motors around the IP.
- The calibration results will be posted soon.
- It seems that the IP stepper motors have limit detectors at both ends of the slider. (Shamefully enough, WE DID'NT KNOW THAT!!)
- The limit flag is not utilized yet. We need to analize the stepper motor driver to implement the limit detection.
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The polarities of the LVDT on the IP and BF were confirmed.
- We found that the existing signs in LVDTINF are correct.
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The vertical positions of the BF LVDT secondary coils were adjusted.
- Due to the height adjustment of the ITMs in May, the primary coils (suspension side) were close to the upper end of the movable range.
- But the situation was not much improved because most of the secondary coils (frame side) were already set at the highest position.
- We'll confirm the narrowest gap between them after the TM OpLev alignment.
- The tension of the cables just below the BF was slightly relaxed by re-tying them with a PEEK tie.
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We inspected the BF yaw picomotor visually with a fiber scope.
- The motor shaft looked not rotating with the driving inputs even when the sound of motor driving could be heard clearly.
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We could not localize the cause of malfunction yet.
- But we suspect there's some mechanical problem in the motor since we could not find any problem in the electric part so far.
- We stoped here today. For further inspection, we need to open the cup of the BF which takes much time.
Next step
- Releasing IP and BF and their DC position adjustment for TM OpLev alignment
- Health check of the suspension by measuring transfer functions