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VIS (IY)
takafumi.ushiba - 9:05 Wednesday 01 April 2020 (13922) Print this report
ITMY IP H2 coil was satulated

Around 7:15 today, H2 coil of IP of ITMY was satulated (20000 couts).
We should off-load.

http://klog.icrr.u-tokyo.ac.jp/osl/uploads/13922_20200401020516_screenshotfrom20200401090145.png

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fabian.arellano - 11:25 Wednesday 01 April 2020 (13923) Print this report

I offloaded the coil-magnet actuation onto the IP horizontal fishing rods. At the end of the work I left the suspension in TWR_DAMPED.

When the IP control system is on the amount of actuation now becomes, approximately:

  • L: 2200 cnt,
  • T: 2500 cnt,
  • Y: 3400 cnt,
  • H1: -8000 cnt,
  • H2: 6000 cnt,
  • H3: 5900 cnt.

In terms of displacement the current position in SAFE mode is

  • L: 290 um,
  • T: 462 um and
  • -720 urad.
  • Time: 02:19:00 UTC on 2020-04-01.

The set point is

  • 100 um,
  • 200 um and
  • -706 urad.

Before offloading the position of the IP in SAFE state (K1:GRD-VIS_ITMY_STATE_N = 30) was

  • L: 276 um,
  • T: 1114 um
  • Y: -831 urad
  • Time: before 00:46:00 UTC on 2020-04-01.

Note also that

  • Ramp time in the IP DAMP filter box was 60 seconds and I left it as it was.
  • By mistake I moved the top filter yaw stepper motor by 10,000 counts, but I moved back and it seems to be alright.

After the work I engaged TWR_DAMPED. The control system of the IP and of the BF look alright. The picture shows the total amount of steps required.

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lucia.trozzo - 17:21 Wednesday 01 April 2020 (13932) Print this report

The IY IP coil outputs are still to large and this means that the IP is still far from the nominal set point. To reduce the coil outputs so to have ess than 3000 counts for each one, I moved a bit more the stepping motors.
Below some detail of this work.
The IP set point is

    L: 100 um,
    T: 200 um
    Y: -706 urad.

To measure how far the IP was far from the set point I requested towe damped to guardian, I turned off the BF_Y and IP loops and I monitored the ITMY_IP_DAMP_{L,T,Y}_IN1 signal:

    L: 250 um
    T: 300 um
    Y: -25 urad

To reduce these values, I moved L and T stepping motors:

-Pic1 shows the total numbers of the step done to bring the IP close to the nominal position

Pic1 shows the IP_DAMP_{L,T,Y}_IN1 and ITMY_IP_{H1,H2,H3}_COILOUT before and after the IP position done with stepping motors.

The coil outputs are less than 2000 counts.

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