Discussions

Altitude is not stable during autonomous modes

Posted by Valentin Brossard on May 20, 2014 at 2:31am
Hi everyone,
Altitude had a strange behaviour during my last flight, it changes during flight when the IRIS is not in manual mode. That occured on the following mode :
  • LOITER,
  • AUTO (mission),
  • GUIDED (follow me).

The altitude variation were more important when the wind is stronger. Altitude can change on several meters.

The following parameters were changed to try to reduce this effect, but without success:

  • INAV_TC_Z => Vertical time constant
  • THR_ALT_P => Altitude controler P gain
  • THR_ALT_I => Altitude controler I gain

Do you have any ideas ? I'll try to give log files during the week.

Software version:
Arducopter: ArduCopter-3.1.0

Hardware:
Drone: IRIS quadcopter with pixhawk board

Detection context:
It appears that the altitude is not constant during flight tests in autonomous modes.

Environnement condition:
On windy weather, the problem is bigger

Tips

I meet some other pixhawk users who said that the sensors (like barometer) are too sensitive and added cotton on sensors would increase the altitude control.

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Tags: altitude, autonomomus, iris, modes, pixhawk
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Replies

  • T3
    Richard Boyhan May 20, 2014 at 12:12pm
    The APM, PX4, and PixHawk are all sensitive to wind and bright light. The cases that come with the APM and PixHawk have foam to protect the barometers. The PX4 does not have a case option, so I use cotton.
    • Valentin Brossard > Richard Boyhan May 30, 2014 at 12:23am

      I tried the cotton on PixHawk and the altitude was much stable (But there was no wind).

      I'll try it again on windy weather.

      • Justin H. > Valentin Brossard September 7, 2014 at 6:13pm

        Any news to report on this one, Valentin?

        • Valentin Brossard > Justin H. September 15, 2014 at 1:55am

          It's clearly better with cotton.

          But nothing more to say.

          Cheers

    • Valentin Brossard > Richard Boyhan May 21, 2014 at 12:19am

      Thanks for your answer !

      I opened the PixHawk and I didn't see any foam on barometers...

      I will try cotton and tell you if it fixes the problem.

      Thanks again.

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