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VIS (BS)
fabian.arellano - 18:25 Tuesday 04 October 2022 (22336) Print this report
IP LVDT sensor diagonalization

With Lucia.

We modified the LVDTALIGN matrix in order to reduce sensor diaginalization in the IP LVDTs.

The concept is as follows

  • Actuated in L, and minimized the amplitude of the resonance peak in L, that appeared in T and Y transfer functions.
  • Actuated in T, and minimized the amplitude of the resonance peak in T, that appeared in L and Y transfer functions.
  • Actuated in Y, and minimized the amplitude of the resonance peak in Y, that appeared in L and T transfer functions.

The matrix LVDTALIGN was calculated with the Matlab script BS_IP_SENS_ALIGN.m, which is in /kagra/Dropbox/Subsystems/VIS/vis_commissioning/bs/IP_diag/BS_new/ . This script uses data exported from the DTT files at /kagra/Dropbox/Subsystems/VIS/vis_commissioning/bs/IP_diag/20221004/. The files with the name *02.xml and *03.xml refer to measurement before and after diagonalization.

 The new value of the matrix is

    0.7523   -0.2235   -0.2108
    0.2654    0.9126    0.0014
    0.6232   -0.2964    0.8169

We accepted the new values in the SDF while the suspension was in TWR_FLOAT (table file name "isolated").

The plots show the transfer functions after diagonalization. More quantitative information will follow in a future entry.

Images attached to this report
Comments to this report:
fabian.arellano - 18:39 Wednesday 05 October 2022 (22361) Print this report

With Lucia.

  • We revisited the calculation of the digonalization (a.k.a. sensing) matrix of the LVDTs because there was a mistake in the Matlab script. Nevertheless, the change was not dramatic.
  • Then we calculated again the actuation matrix as briefly described in klog 22337.
  • We updated the SDF with the new values of the matrices when the suspension was in lock_acquisition state.

More information will follow in a future klog.

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