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  1. Data Management
  2. DM-34816

Support the Rotator Test on Summit Part 3

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    Details

    • Story Points:
      1
    • Sprint:
      TSSW Sprint - May 09 - May 23
    • Team:
      Telescope and Site
    • Urgent?:
      No

      Description

      Support the rotator test on summit. This is to support the test case by Ander to debug the rotator's movement.

      The github issue is: negativeMoveOscillations. The branch of Simulink model is issue37.

      There is one test case:
      1. Increase the preloading of the system (3% to 20 %). We will do this slowly to collect the data. Need to check the MOOG's implementation for this.

      PS. The story point here contains the effort in DM-34836.

        Attachments

        1. 20220517_125955.mp4
          16.28 MB
        2. data_moog.log
          560 kB
        3. data_moog.mat
          663 kB
        4. data_tekniker_3_negative.log
          210 kB
        5. data_tekniker_3_negative.mat
          251 kB
        6. data_tekniker_3_positive.log
          436 kB
        7. data_tekniker_3_positive.mat
          517 kB
        8. Rotator Data.pptx
          264 kB

          Issue Links

            Activity

            Hide
            ttsai Te-Wei Tsai added a comment -

            Prepared the test case.

            Show
            ttsai Te-Wei Tsai added a comment - Prepared the test case.
            Hide
            ttsai Te-Wei Tsai added a comment -

            We did the tests on summit as the attached file. Doug preferred we analyzed the data first to check the preloading value based on the currents before doing the test of different preloading data.

            Show
            ttsai Te-Wei Tsai added a comment - We did the tests on summit as the attached file. Doug preferred we analyzed the data first to check the preloading value based on the currents before doing the test of different preloading data.
            Hide
            ttsai Te-Wei Tsai added a comment -

            Bruno recorded the video in: 20220517_125955.mp4

            Show
            ttsai Te-Wei Tsai added a comment - Bruno recorded the video in: 20220517_125955.mp4
            Hide
            ttsai Te-Wei Tsai added a comment -

            Organized the comparison: Rotator Data.pptx.

            Show
            ttsai Te-Wei Tsai added a comment - Organized the comparison: Rotator Data.pptx .
            Hide
            ttsai Te-Wei Tsai added a comment -

            Please help to review the ticket. Thanks!

            Show
            ttsai Te-Wei Tsai added a comment - Please help to review the ticket. Thanks!
            Hide
            hdrass Holger Drass added a comment -

            Thanks Te-Wei! Data taken and directly analyzed. Very efficient!

            There will be a part 4...

            Show
            hdrass Holger Drass added a comment - Thanks Te-Wei! Data taken and directly analyzed. Very efficient! There will be a part 4...
            Hide
            ttsai Te-Wei Tsai added a comment -

            Doug's analysis:

            The first observation is that the original Moog software appears to be using a preload of 0.6/4 = 15%. The 0.6 is approximate average of the ± currents on the graph on page 2 left side.
            Per Austin's comment Moog had the current limit set at 3.6A. However, it appears from the Tekniker manual page 22 figure 33 that they raised this limit to 4.0A. If my understanding is correct the current limit should be reduced back to the specified 3.6A. The current limit was set to meet the requirements of limiting the torque to prevent damage to the cables and Hoses. We should probably be using the same preload.

            The plots on page 3 show negligible preload. It appears that the values are ~+/-0.05 amps or about 1%. It appears in the Tekniker manual on page 23 figure 34 that the preload was set to Tq = 0/100. Does this mean no preload or? These plots show oscillations between positive and negative torque. Whenever this happens instability is expected produced by the small gap between the gears.

            There is a reasonable chance that increasing the preload, tq, will resolve this issue. The other possibility is that we should reduce the gains. The rapid oscillations imply high gains which are unnecessary. Figure 34 appears to show a gain, Kp of 10/100 (10%?). This is a fairly small gain but we may try reducing it. We do not need a fast system. We need an accurate and stable one.

            Show
            ttsai Te-Wei Tsai added a comment - Doug's analysis: The first observation is that the original Moog software appears to be using a preload of 0.6/4 = 15%. The 0.6 is approximate average of the ± currents on the graph on page 2 left side. Per Austin's comment Moog had the current limit set at 3.6A. However, it appears from the Tekniker manual page 22 figure 33 that they raised this limit to 4.0A. If my understanding is correct the current limit should be reduced back to the specified 3.6A. The current limit was set to meet the requirements of limiting the torque to prevent damage to the cables and Hoses. We should probably be using the same preload. The plots on page 3 show negligible preload. It appears that the values are ~+/-0.05 amps or about 1%. It appears in the Tekniker manual on page 23 figure 34 that the preload was set to Tq = 0/100. Does this mean no preload or? These plots show oscillations between positive and negative torque. Whenever this happens instability is expected produced by the small gap between the gears. There is a reasonable chance that increasing the preload, tq, will resolve this issue. The other possibility is that we should reduce the gains. The rapid oscillations imply high gains which are unnecessary. Figure 34 appears to show a gain, Kp of 10/100 (10%?). This is a fairly small gain but we may try reducing it. We do not need a fast system. We need an accurate and stable one.

              People

              Assignee:
              ttsai Te-Wei Tsai
              Reporter:
              ttsai Te-Wei Tsai
              Reviewers:
              Holger Drass
              Watchers:
              Holger Drass, Te-Wei Tsai
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              0 Vote for this issue
              Watchers:
              2 Start watching this issue

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