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Jumpy Alt hold

Posted by Lior Zahavi on April 28, 2014 at 12:42pm

Hello guys,

i built a new quad (after several successful quads with Arducopter 3.x) - its a F450 with Sunnysky 2212X motors and 10x4.7 props and simonK 30A ESCs, running a 3S pack.

this quad flys great on stabilize after auto tune, nice and quiet and smooth.

but as soon as i flip ALT HOLD on, it starts jumping up and down slightly (i can hear the motors "popping" all the time).

i tried some tuning but nothing really changed it. once i go back to stabilize its stable and quiet one more time.

im attaching a log of the last flight where this is shown.

can you advise what to do?

thanks.

F450 jumping log.log

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Replies

  • Dave May 1, 2014 at 4:13pm
    What is the KV of the motors. I had that problem with my quad with my 1000kv motors and when i went to 8 inch props i got rid of that problem.
    • Lior Zahavi > Dave May 1, 2014 at 5:09pm

      Motors are 980KV and spinning 10x4.7 props.

  • Tom Mahood May 1, 2014 at 7:26am

    Yep, looks like vibration. Your RelAlt doesn't track really well with your BaroAlt and your ThrOut looks pretty ragged. Vibration issues really don't affect the craft much in Stabilize, but show up in AltHold or Loiter. Turn on your IMU logging to log your vibrations and do another flight to be sure.

    • Lior Zahavi > Tom Mahood May 25, 2014 at 1:06am

      Here is the log from Friday attached. can you have a look?

      2014-05-23 16-48-17.log

      https://storage.ning.com/topology/rest/1.0/file/get/3702493936?profile=original
    • Lior Zahavi > Tom Mahood May 1, 2014 at 7:29am

      Thank you, i will gather some more logs.

  • T3
    Richard Boyhan April 29, 2014 at 4:40am
    Sounds like vibration. Did you balance your props and mount your APM on foam or moon gel?
    • Lior Zahavi > Richard Boyhan May 1, 2014 at 4:23am

      APM is mounted on double sided think elastic foam.

      i dont think its vibration as props are balanced, and Stabilize seems 100% smooth ?

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