Loosing Altitude Help

Posted by Pmarche on September 29, 2015 at 8:26am

Hi, has anyone been able to solve the problem related to the loss of altitude while flying forward?.

 

I tried setting EKF ( enabling it) and it did not help.

 

It is also a problem only when it flies forward.

 

I have not tried autotune; could this be a problem related to Pitch-Roll Rates?.

 

This is really a pain when flying Auto Missions, since I can not try to take pictures for photogrammetry, because it looses altitude when it starts flying forward.

 

 

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Replies

  • Rodney Johnson September 30, 2015 at 5:24am
    I have 2 pixhawks mounted out in open air and have had no issues with loosing altitude. As Ian had suggested, , get some logs to look at. Logs will tell the story.
    You did start from a fresh setup and have no mixes involved, I'm sure there isn't but just asking.
    • Cala > Rodney Johnson October 1, 2015 at 1:55pm

      Rodney, what motor/props combination you have?

  • ian Molesworth September 29, 2015 at 10:20am

    I suspect its an aerodynamic problem not a control one. As your vehicle flies forward a very small low pressure zone is forming around the controller and the baro sensor, just enough for the algorithms to see what they think is a slight increase in barometric altitude. It compensates by trying to lose a bit of height.

    Try moving any shell you have over the flight controller and see if that changes anything significantly.

    Could you publish a log with barometric pressure, groundspeed etc?

     

    • Pmarche > ian Molesworth September 29, 2015 at 10:51am

      Yes. I will post it in a few minutes.

    • Pmarche > Pmarche September 29, 2015 at 10:55am

      Here it is.

      53.BIN

      https://storage.ning.com/topology/rest/1.0/file/get/3691245716?profile=original
  • Rodney Johnson September 29, 2015 at 9:03am
    How much altitude are you losing?
    If you were to keep flying forward would it fly itself into the ground?
    • Pmarche > Rodney Johnson September 29, 2015 at 9:42am

      Not really, while flying low, It losses about 4 meter, and It starts recovering. Non of this happens when flying sidewise, or backwards.

       

      I changed the battery from a 14.4v to a 22.2v, and it helps; once with the 14.4 it lost all the altitude and bounced back.

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