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Message ID: 12598     Entry time: Thu Nov 3 16:30:42 2016
Author: Lydia 
Type: Configuration 
Category: SUS 
Subject: ETMX to coil matrix expanded 

[ericq, lydia]


We believe the optimal OSEM damping would use an input matrix diagonalized to the free swing modes of the optic, and an output matrix which drives the coils appropriately to damp these free swing modes. As was discovered, a free swinging optic does not necessarily have eigenmodes that match up perfectly with pitch and yaw, however in the current state the "TO_COIL"  output matrix that determines the drive signals in response to the diagonlized sensor output also controls the drive signals for the oplevs, LSC/ASC, and alignment biases. So attempts to diagonalize the output matrix to agree with the input matrix have resulted in problems elsewhere. (See previous elog). So, we want to expand the "TO_COIL" matrices to treat the OSEM sensor inputs separately from the others.


  • We modified the ETMX suspension model (c1scx) to use a modified copy of the sus_single_control block (sus_single_control_mod) that has 3 additional input columns. These are for the sensing modes determined by the input matrix, and are labeled "MODAL POS", "MODAL PIT", and "MODAL YAW." 
    • The regular POS, PIT, and YAW columns no longer include the diagonalized OSEM sensor signals for ETMX.
    • The suspension screen now out of date; it doesn't show the new columns under Output Filters and the summed values displayed for each damping loop do not incluse the OSEM damping.
  • The new matrix can be acessed at /opt/rtcds/caltech/c1/medm/c1scx/C1SUS_ETMX_TO_COIL.adl (see Attachment 1). For now, it has the naive values in the new columns so the damping behavior is the same. 
  • In trying to get a properly generated MEDM screen for the larger matrix, we discovered that the Simulink block for TO_COIL specifies in its description a custom template for the medm autogeneration. We made a new verion of that template with extra columns and new labels, which can be reused for the other suspensions. These templates are in /opt/rtcds/userapps/release/sus/c1/medm/templates, the new one is SUS_TO_COIL_MTRX_EXTRA.adl
  • I will be setting the new column values to ones that represent the diagonlized free swing modes given by the input matrix. Hopefully this will improve OSEM damping without getting in the way of anything else. If this works well, the other SUS models can be changed the same way. 
Attachment 1: 01.png  10 kB  | Hide | Hide all
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