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Entry  Fri Nov 18 17:52:42 2016, gautam, Update, PSL, FSS Slow control -> Python, WFS re-engaged 
    Reply  Sun Nov 20 23:53:38 2016, awade, Update, PSL, FSS Slow control -> Python, WFS re-engaged 
Message ID: 12627     Entry time: Fri Nov 18 17:52:42 2016     Reply to this: 12628
Author: gautam 
Type: Update 
Category: PSL 
Subject: FSS Slow control -> Python, WFS re-engaged 

[yinzi, craig, gautam]

Yinzi had translated the Perl PID script used to implement the discrete-time PID control, and had implemented it with Andrew at the PSL lab. Today afternoon we made some minor edits to make this suitable for the FSS Slow loop (essentially just putting the right channel names into her Python script). I then made an init file to run this script on megatron, and it looks to be working fine over the last half hour of observation or so. I am going to leave things in this state over the weekend to see how it performs.

We have been running with just the MC2 Transmission QPD for angular control of the IMC for a couple of months now because the WFS loops seemed to drag the alignment away from the optimum. We did the following to try and re-engage the WFS feedback:

  • Close the PSL shutter, turned off all the lights in the lab and ran the WFS DC offsets script : /opt/rtcds/caltech/c1/scripts/MC/WFS/WFS_DC_offsets
  • Locked the IMC, optimized alignment by hand (WFS feedback turned off) /opt/rtcds/caltech/c1/scripts/MC/WFS/WFS_DC_offsets
  • Unlocked the IMC, went to the AS table and centered the spots on the WFS
  • Ran WFS RF offsets script - this should be done with the IMC unlocked (after good alignment has been established) /opt/rtcds/caltech/c1/scripts/MC/WFS/WFS_DC_offsets
  • Re-engaged WFS servo

GV addendum 23Nov2016: The WFS have been working well over the last few days - I've had to periodically (~ once in a day) run the WFS reflief script to keep the outputs to the suspension PIT and YAW DOFs below 50cts, but the WFS aren't dragging the alignment away as we had noticed before. The only thing I did differently is to follow Rana's suggestion and set the RF offsets with the MC unlocked as opposed to locked. I've added a line to the script to remind the user to do so... Also, note that EricQ has recently cleaned up the scripts directory to remove the numerous obsolete scripts in there...


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