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Pixhawk Auto Mode elevator / throttle glitch

Posted by SlipstreamFPV on February 27, 2016 at 9:29pm

The pitch servo and throttle are constantly pulsing very quickly in auto modes:

3691278920?profile=original

I've done a fresh flash whipping all old settings and re-tuned my plane with the same result. Does anyone know what can cause this issue? I'm worried it might be a bug and with enough pulsing the pitch servo or ESC might give up!

There is a log here:

https://www.dropbox.com/s/sfbm41ro714iq8d/4.BIN?dl=0

I'd be very grateful if anyone who can read the logs better than me could have a look and see if anything sticks out. In comparison roll has no issues and is a very clean graph between desired and actual roll. The plane was flown on a relatively calm morning.

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Replies

  • Corrie Venter February 29, 2016 at 10:12am

    Take a read at this post, sounds very similar . . .

    http://diydrones.com/forum/topics/fbwa-servo-jitter-when-gps-has-no...

    • SlipstreamFPV > Corrie Venter February 29, 2016 at 5:58pm
      Interesting. Certainly the graph on the ground looks similar. I have 2 GPSs on the plane. I wonder if that has an effect. The linked threads in that link still don't have the exact same features and there doesn't seem to be a particular fix either. I think THR_MIN is on 0 in this case to allow the autopilot to glide.
  • Moderator
    Graham Dyer February 27, 2016 at 11:36pm

    What are your pitch PID's set to?

    • SlipstreamFPV > Graham Dyer February 29, 2016 at 3:42am
      P 0.65
      I 0.04
      D 0.02

      Roll is the same and behaves well. I did an auto tune and it originally had P a bit higher but I turned it down by .15 to see if that was causing the oscillation or noise on the pitch output.

      Thanks for looking into this!
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