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Entry  Wed May 8 18:33:02 2013, Koji, Update, ASS, YARM ASS - faster and more precise convergence YARM_ASS.pngScreenshot.png
    Reply  Wed May 8 22:36:42 2013, Koji, Update, ASS, XARM ASS (YARM ASS - faster and more precise convergence) XARM_ASS.png
Message ID: 8552     Entry time: Wed May 8 18:33:02 2013     Reply to this: 8554
Author: Koji 
Type: Update 
Category: ASS 
Subject: YARM ASS - faster and more precise convergence 

Precise arm alignment is more demanded. as the PRMI locking requires good and reliable alignment of the ITMs.

I previously added the output matrix to ASS.

Now the input and output matrix as well as the gains and filters have been updated.

The current concept is

Fast loop: align the arms by the arm mirrors with regard to the given beam.

Slow loop: move the incident beam position and angle to make the spot at the center of the mirrors

This is actually opposite to Den's implementation.

In order to realize the faster alignment of the arm, I increased the corner frequency of the lockins for the arm signals from 0.5Hz to 1Hz.

With the new configuration the arm alignment converges in 10sec and the input pointing does in ~15sec.

The actuation to the input pointing TTs are done together with the feedforward actuation to the arms.
This way we can avoid too much coupling from the input pointing servos to the arm alignment servos.

The corresponding script /opt/rtcds/caltech/c1/scripts/ASS/YARM/DITHER_Arm_ON.py was also modified.

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