Uploaded image for project: 'Data Management'
  1. Data Management
  2. DM-25245

Put the Rotator into Fault State if no Track Command for a Long Time

    XMLWordPrintable

    Details

      Description

      If the rotator does not receive the track command for a long time, the rotator should be put into the Fault state. This could be 0.5 second (by Tiago) or 1 second (by Russell). At this moment, we do see this in the Simulink model by the simulation experiment, but we do not know how that is decided. In addition, we did not see this when we did the test on summit. This task needs to figure out what is the existed logic in model and how to update it.

      The following is the figure to show the simulation result (detail is at DM-25243):

      The system is at the Fault state around time equals 20.2 seconds (no new track command after time=6 seconds).

        Attachments

          Issue Links

            Activity

            Hide
            rowen Russell Owen added a comment - - edited

            Regarding your comment "There is one thing we need to consider. What should be the rotator's behavior if it does not receive a new track command in the slewing?":

            In the long run we want the controller to go into a fault state if it has to extrapolate any tracking command. This is independent of whether the controller happens to be slewing or tracking. In fact I would say it is more important if the rotator is slewing, because the rotator is moving more quickly.

            I am not sure what your current changes do. If they do not stop slewing then please file a new ticket to stop slewing if tracking commands don't arrive in time.

            Show
            rowen Russell Owen added a comment - - edited Regarding your comment "There is one thing we need to consider. What should be the rotator's behavior if it does not receive a new track command in the slewing?": In the long run we want the controller to go into a fault state if it has to extrapolate any tracking command. This is independent of whether the controller happens to be slewing or tracking. In fact I would say it is more important if the rotator is slewing, because the rotator is moving more quickly. I am not sure what your current changes do. If they do not stop slewing then please file a new ticket to stop slewing if tracking commands don't arrive in time.
            Hide
            rowen Russell Owen added a comment -

            Approved based on your description of the changes made.

            Thank you for tackling this difficult problem.

            Show
            rowen Russell Owen added a comment - Approved based on your description of the changes made. Thank you for tackling this difficult problem.
            Hide
            ttsai Te-Wei Tsai added a comment - - edited

            I think the MOOG's original idea is that if there is an interrupt of track command in the slewing, it is safer to finish the slew instead of picking up the new track command (which might be different from the initial one) in a latter time. While I am reviewing the document now, I notice this might be what LSST want originally:

            We may need to discuss the behavior we want together in a latter time. This might be related to the pointing's component behavior as well.

            Show
            ttsai Te-Wei Tsai added a comment - - edited I think the MOOG's original idea is that if there is an interrupt of track command in the slewing, it is safer to finish the slew instead of picking up the new track command (which might be different from the initial one) in a latter time. While I am reviewing the document now, I notice this might be what LSST want originally: We may need to discuss the behavior we want together in a latter time. This might be related to the pointing's component behavior as well.
            Hide
            tribeiro Tiago Ribeiro added a comment -

            Hi TeWei, 

            I don't think it is safe to finish a slew if you loose track demands, quite the opposite indeed. Specially if you consider that during a slew you are moving at higher velocity. If something out of ordinary is happening (e.g. demands disappear), the safest thing is always to stop.

            Also, I am not sure that it what the slide says. The item you highlighted seem to suggest that the rotator will stay in "slew" mode until it reaches "tracking conditions", which makes sense. The item above says the position is updated based on the command (e.g. demand) at 20Hz and the item bellow says it will update the target position based on target motion, which also makes sense.  

            Show
            tribeiro Tiago Ribeiro added a comment - Hi TeWei,  I don't think it is safe to finish a slew if you loose track demands, quite the opposite indeed. Specially if you consider that during a slew you are moving at higher velocity. If something out of ordinary is happening (e.g. demands disappear), the safest thing is always to stop. Also, I am not sure that it what the slide says. The item you highlighted seem to suggest that the rotator will stay in "slew" mode until it reaches "tracking conditions", which makes sense. The item above says the position is updated based on the command (e.g. demand) at 20Hz and the item bellow says it will update the target position based on target motion, which also makes sense.  
            Hide
            ttsai Te-Wei Tsai added a comment -

            Tiago Ribeiro If you think the powerpoint makes sense to you, the behavior of rotator is what I said. And this contradicts with your first paragraph. Thanks!

            Show
            ttsai Te-Wei Tsai added a comment - Tiago Ribeiro If you think the powerpoint makes sense to you, the behavior of rotator is what I said. And this contradicts with your first paragraph. Thanks!

              People

              Assignee:
              ttsai Te-Wei Tsai
              Reporter:
              ttsai Te-Wei Tsai
              Reviewers:
              Russell Owen
              Watchers:
              Russell Owen, Te-Wei Tsai, Tiago Ribeiro
              Votes:
              0 Vote for this issue
              Watchers:
              3 Start watching this issue

                Dates

                Created:
                Updated:
                Resolved:
                Start date:
                End date:

                  Jenkins Builds

                  No builds found.