Details
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Type:
Story
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Status: Done
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Resolution: Done
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Fix Version/s: None
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Component/s: ts_main_telescope
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Story Points:3
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Sprint:TSSW Sprint - Jun 8 - Jun 22
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Team:Telescope and Site
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Urgent?:No
Description
The path generator will continuously update the demand position even if there is no new track command received in the SlewAndTrack sub-state. The initial suspect is that this comes from the non-zero target velocity in the final received track command. This will continue to update the position command. The initial idea to fix this is to reset the velocity command to be zero if no new track command received.
The following figure (x-axis: time in seconds, y-axis: value such as position in degree) shows this problem. There are two targets (positions = 1.2 degree and 3 degree. velocity = 0.01 deg/sec and -0.01 deg/sec). The track command does not continue after the time equals 6 seconds. We could see the rotator position is at 3 degree when time is at 8 seconds but the demand position is decreasing after time=8 seconds (rotator's position keeps the same) because of the second target has the velocity of -0.01 deg/sec.
Attachments
Issue Links
- relates to
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DM-25245 Put the Rotator into Fault State if no Track Command for a Long Time
- Done
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DM-25249 Track the Multiple Targets
- Done
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DM-25441 Remove the History of Trajectory after the Stop Command in the Tracking
- Done
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DM-25795 Fix the Bugs of Transition of Tracking
- Done
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DM-25045 Review the Control Algorithm of Rotator in Phase 2
- Done
If the controller's path generator interpolates between (position, velocity, time) track commands then it probably should not extrapolate at all. I certainly hope that is how the path generator works, as I find it hard to believe it can produce a nice motion profile otherwise.
As per
DM-25245I hope that the low-level controller will go into FAULT state if track commands do not come often enough. I don't know how that relates to this ticket, but I think it crucial that rotator never stop if a track command is late, then start moving again when the track command arrives. That would lead to a silently unacceptable motion profile.I added more comments on
DM-25245