az encoder jumps oct19


Other links
azimuth encoder failures


     Azimuth encoder 1 (dome side) is used to position the azimuth arm. Azimuth encoder 2 (ch side) is used to measure the bending of the azimuth arm  (enc1-enc2)


Azimuth motions on day of bending failure (16oct19)

The plot shows the azimuth arm motions on the morning of 16oct19 (prior to the bending failure) (.ps) (.pdf)

When did the jumps occur

    When an azimuth encoder jumps a tooth (.02 deg), the azimuth encoder difference will also jump.
The daily average of the azimuth encoder difference (computed every 1 deg in azimuth) can show the days when things jumped
(since after the jump, the next daily average will still show the step).

The az  encoder difference daily average is over plotted for 01oct19-07nov19 (.ps)   (.pdf)

The following plots show days when jumps occurred.

   az encoder 2 jumps on 09oct19 (.ps)  (.pdf)

  az encoder 2 jumps on 10oct19 (.ps)  (.pdf)

Correcting the jumps

    Willie and Osvaldo went to check the encoders after the azimuth bending stopped the motion on 16oct19 around 08:30

Pictures showing the azimuth pointer after the encoder jumps were corrected.

After correcting the encoders a CW and CCW spin was done to measure the azimuth encoder difference. (.ps) (.pdf)

The pointing errors.

    The 1 tooth jump in encoder 1 should have given a pointing error of 0 to 20Asec when going from za 0 to 20deg.
I looked through the azencoder difference and did not find an encoder 1 jump.
I also looked at the x102 pointing errors

We corrected an enc1 jump on 16oct19, but we did not see any trace of this in the x102 data.


processing: x101/191016/,,,,

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