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Wed Jan 14 19:27:09 2015, ericq, Update, LSC, UGF servo now linear again
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Thu Jan 15 03:18:11 2015, diego, Update, LSC, UGF servo now linear again
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Fri Jan 16 04:14:05 2015, diego, Update, LSC, UGF servo now linear again
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Fri Jan 16 20:37:52 2015, diego, Update, LSC, UGF servo now linear again
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Message ID: 10911
Entry time: Fri Jan 16 04:14:05 2015
In reply to: 10902
Reply to this: 10916
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Author: |
diego |
Type: |
Update |
Category: |
LSC |
Subject: |
UGF servo now linear again |
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UGF Servos' commissioning still going on, updates of today:
- on Rana's suggestion, we don't use anymore the Q-signal rejection at the level of Phase 1 and Phase 2; instead, a proper complex division is made between those two signals (with a check in case of zero); then the resulting signal is demodulated with a new Phase 3, which is the one used to select the I signal while zeroing the Q one; changes to the model and the screens have been made;
- a new evaluation of all the parameters for the four servos has been made; aside for the new phase, and the zeroing of the other phases (because they are not used anymore for the selection), the parameters are not dissimilar from the prevoius ones
- the PRCL and MICH servos seem sufficiently stable;
- CARM and DARM are stable only for a short amount of time; what usually happens is that one of the two starts drifting in one random direction, and usually the other one follows shortly after; it is not clear if there is a relation or if they stop being stable after a similar amount of time; I still noticed a few lowest limits appearing in the input signal, which should be avoided; I'll check the model again tomorrow;
- the weird thing about CARM and DARM is that at the same time when one of them starts drifting, its I and Q signals begin to be comparable; when the servo is shut off, they resume their normal state;
- an increase in the excitation gain improves the separation of I and Q and also reduces their variations, but a high peak in the loop due to this might not be a good idea.
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