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  1. Data Management
  2. DM-36869

The MT rotator can drive itself past the software limits into the direction inhibit limit swiches

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      The MT rotator can drive itself past the software position limits into a direction inhibit limit switch.

      We managed to make this happen using the following command sequence in the command-line utility rotator_commander:

      • move -90 # From -89 degrees; the CCW was not following well, so we made our way here in a series of 1-3 degree moves. This move seemed to work fine.
      • ramp -90 0 1 # This means follow a path of speed 1 deg/sec from -90 to 0 deg.
      • # observe that this did not work well (as described below), so a few seconds later:
      • stop

      When we issued the ramp command we observed the rotator move slightly in the negative direction (presumably that is when it hit a limit switch) and report demand position < -100 degrees.

      Note: as we watched, the demand position very slowly climbed from its minimum, even though nothing else was happening – the rotator was not moving and the rotator commander was not sending commands (at least not after the stop command). This is a minor problem, since the rotator was not moving. Still, I hope it can be fixed, because it is confusing and suggests additional problems in the rotator.

      The trajectory generator should never command a motion that exceeds the software position limits, nor the velocity, acceleration or jerk limits.

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            ttsai Te-Wei Tsai added a comment - - edited

            Bug of the trajectory algorithm. This is similar to the question 1 in review_AO_02282022.docx. The Ander's reply is there. Since the owner is Ismael (or Alberto ?) now, maybe he will be willing to fix this.

            ttsai Te-Wei Tsai added a comment - - edited Bug of the trajectory algorithm. This is similar to the question 1 in review_AO_02282022.docx . The Ander's reply is there. Since the owner is Ismael (or Alberto ?) now, maybe he will be willing to fix this.

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              ttsai Te-Wei Tsai
              rowen Russell Owen
              Russell Owen, Te-Wei Tsai
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