KAGRA Logbook

VIS (PR2)

satoru.ikeda - 17:46 Thursday 28 January 2021 (15857)

The PR2-SF's stepper motor has stalled.

In order to investigate the control range of the PR2-SF stepper motor, I ran the stepper motor using the LVDT values as a reference for the calibration values.

First LVDT (K1:VIS-PR2_SF_LVDTINF_GAS_INMON) was -15035.

I ran the SF stepper motor to positions 5000, 10000, 15000, 20000, 50000, 300000 (about 5.85mm) and it was normal.
Next, I tried to run it up to 600000 (about 11.7mm) and maybe 500000 (about 9.76mm), then the LVDT came on.
The previous results of K-Log15823 showed that the LVDT was running to 500000, but it seems to have stalled when trying to continue.
I stopped the motor, but it was already too late, then I moved the stepper motor to position 0, but the LVDT value did not change.

At first I couldn't find the result of PR2's calibration and checked PR3's K-Log 2739 log to confirm that the LVDT range could work from -25000 to 20000[count].
It later found PR2's K-Log 3462, which had the LVDT range calibrated from -5000 to 12500.
So the LVDT at the start was outside the range at the time of calibration.

I decided to consult with him and ask him to open the lid of the PR2 chamber to remove the sticking point.

Images attached to this report

15857_20210128095003_k1vispr2sfbflvdtinfgasinmon20210128.png

Non-image files attached to this report

pr2japanese.txt

Comments to this report:

kouseki.miyo - 19:54 Thursday 28 January 2021 (15858)

I think this keystone is lifted up somewhat because temperature when the LVDT was installed is higher than today.

According to klog#3132, 3462, the LVDT of SF-GAS was calibrated in July 20 2017.

I plotted the temperature from this time.

Unfortunately, around this time, although temperature was not recorder because Ondotori had not been installed yet, the temperature might be around 24.5 degree.

On the other hand, temperature is 23.0 degree today.

So, temperature in PR2 are had been decreased by one degree since the installation.

Python script to draw the figure is in /kagra/Dropbox/Personal/Miyo/LOG/210128.

Images attached to this comment

satoru.ikeda - 18:03 Monday 01 February 2021 (15876)

I checked about the stalling of the PR2 SF stepper motor.

Unfortunately, when I opened the chamber lid, the stall condition was released.
I checked K1:VIS-PR2_SF_LVDTINF_GAS_INMON.
The LVDT was no longer sticking at the timing when I opened the lid, probably just before running the motor.

Therefore, I let the motor drive the entire range and measured the drive range of the stepper.
The drivable range of the stepper motor is currently at -50000 with a drive range of 0 to -175000.
The current position was set to (-14120), which is close to the position of the LVDT (-15035) at the initial start.

Other things I noticed.
The polarity of the motors was reversed.
The one where KeyStone is up is the negative direction of the motor (upward movement of the stepper).

Images attached to this comment

Non-image files attached to this comment

pr2japanese.txt

satoru.ikeda - 8:51 Tuesday 02 February 2021 (15880)

Added photos to K-Log#15876
Photo of PR2-SF in stacked.

Images attached to this comment

satoru.ikeda - 11:30 Tuesday 02 February 2021 (15882)

We set the software limit of PR2 SF as follows.

Drive range of Stepper Motor (upward is minus)
[Before change]
Current position: -500,000[count](-9.76mm)
Upper limit, Lower limit: No setting
Upper and lower limits: No setting Available to drive from 0[count] stack position to -1,750,000[count].

[After change] Set the current position to 0 (add +500,000)
Current position: 0[count](0mm: reference point)
Upper limit: 450,000[count](8.78mm)
(500,000[count](9.76mm):Stacked position)
Lower limit: -1,200,000[count](-23.43mm) (-1,250,000[count](-24.41mm))

Non-image files attached to this comment

japanese.txt