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Entry  Tue Oct 18 04:04:27 2011, kiwamu, Update, LSC, measurement of sensing matrix : touchy SRM 
    Reply  Wed Oct 19 05:15:44 2011, kiwamu, Update, SUS, taking care of SRM f2pSRM.png
       Reply  Wed Oct 19 15:46:49 2011, kiwamu, Update, SUS, taking care of SRM SRM.png
Message ID: 5684     Entry time: Tue Oct 18 04:04:27 2011     Reply to this: 5691
Author: kiwamu 
Type: Update 
Category: LSC 
Subject: measurement of sensing matrix : touchy SRM 

I made some attempts to measure the sensing matrix of the central part.

I could measure the matrix in the PRMI configuration but wasn't able to measure the matrix in the DRMI configuration.

   => I will report the result of the PRMI sensing matrix tomorrow.

The main reason why I couldn't lock DRMI was that the suspensions were touchy and especially the SRM suspension wasn't good.

Some impacts due to the feedback during the lock acquisition completely kicks SRM away. 

The watchdogs' RMS monitor on SRM easily rang up to more than 10 counts once the acquisition started.This is quite bad.

Also the stability of the PRMI lock was strongly depending on the gains of the PRM oplevs.

I guess I have to revisit the vertex suspensions more carefully (i.e. f2a coupling, actuator output matrix, damping gains, input matrices, oplev filters)

otherwise any LSC works in the vertex will be totally in vain.

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