weixin_39600823
weixin_39600823
2021-01-10 03:30

Why not use airspeed sp for gain scaling if airspeed disabled?

Currently we are scaling the actuators with the trim airspeed (a constant value) if airspeed is disabled in the fixed wing attitude controller https://github.com/PX4/Firmware/blob/b54ca67de9b5900c7ed11bef323c7b4e5a0339b6/src/modules/fw_att_control/FixedwingAttitudeControl.cpp#L480-L481

It seems sub optimal since the demanded airspeed can be significantly higher if the fixed wing position controller requests it due to ground speed undershoot in high winds. Is there a reason the scaling is not done using the demanded airspeed instead?

该提问来源于开源项目:PX4/Firmware

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7条回答

  • weixin_39812577 weixin_39812577 4月前

    No, I think that's just historical. I think a test with demanded airspeed would be worthwhile.

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  • weixin_39955700 weixin_39955700 4月前

    Sorry for my ignorance, but how can airspeed demand be reasonably estimated if airspeed is disabled in the controller?

    I asked a related question in this other thread: https://github.com/PX4/Firmware/issues/11677

    edit: I'm interested for a couple reasons: 1) we are starting to use both airspeed and non-airspeed modes, especially once this airspeed failsafe PR goes in: https://github.com/PX4/Firmware/pull/10733 2) we'd like any changes to fixed wing gain scaling to allow higher scaling below minimum airspeed (within reason) to allow more control authority during the immediate seconds after takeoff and before landing when airspeed could be below minimum.

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  • weixin_39600823 weixin_39600823 4月前

    how can airspeed demand be reasonably estimated if airspeed is disabled in the controller?

    For some vehicles a reasonable estimate of airspeed can be acquired from the throttle setting scaled with air density and voltage

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  • weixin_39875842 weixin_39875842 4月前

    This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

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  • weixin_39875842 weixin_39875842 4月前

    This issue has been automatically marked as stale because it has not had recent activity. Thank you for your contributions.

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  • weixin_39955700 weixin_39955700 4月前

    Still might be interesting to look into this. FYI

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  • weixin_39875842 weixin_39875842 4月前

    This issue has been automatically marked as stale because it has not had recent activity. Thank you for your contributions.

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