3.2 on Pixhawk,poor altitude hold PLEASE help !

Due to taking my quad for a swim, I replaced my beloved APM with a Pixhawk.

I'm finding alt hold terrible, constantly drifting up and down. Also quad doesnt know when its landed (altitude wise)

A list of questions, before I downgrade back to APM(which worked solid, and has done for over 12 months.)

  1. The pixhawk didn't have foam on the barometer, so i installed it. made no difference. Shoud the pixhawk have foam on it?
  2. Does the pixhawk use GPS aswell as barometer to get accurate altitude. I was flying with poor GPS at the time. Also altitude hold wasnt working well indoors., with no GPS. But APM always worked solid indoors. So if i waited longer, would it of flown better ( when i was outside)
  3. Vibrations look ok.
  4. CTUN: Alt, Rel alt look odd? With barometer changing.
  5. Barometer reading is slowly ramping up when copter is not flying, is this normal? thermal related?
  6. Could this be just a mid point setting?

I've enclosed my logs. the Pixhawk is mounted on foam pads on a standard vibration mount with blue rubber shocks.

My previous APM was tuned perfectly, and in ALT hold would be like it was glued in the sky. Vibrations similar, slightly better.

I would really appreciate any help.



2015-01-28 13-39-21.bin

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  • Moved back to APM, flies like a dream, out the box ! further updates to follow
  • I also was forced to go back to APM,
    Ok, I have PX4 but is was really sensitive and difficult in many ways (small connectors, firmware loading difficulties, PPM clitching etc), adding some lead to weigh it helped little bit (brutal, I know). I 3d printed frame with "earfoam" dampeners, vibrations little bit less.

    Maybe I give it (PX4) another try in the weekend after a year break, promised a lot of snow, so softer crashes ;-)

  • Don't limit yourself to check the propeller. If the vibration remain high think about an anti vibration mount for your autopilot.

    And this is right if the problem is really about the vibration.

  • I will check te props, and get back
  • Thanks. Have you seen my log? I thought they looked really good? Although i get a imu mismatch!
    • yes, the vibrations were bigger than expected.

      And your problem description fits this kind of problem perfectly.

  • Fix your vibrations.
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