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Stablity issues

Posted by Chris Malyon on November 4, 2010 at 5:02am

Hi,

   I have finally got my quadcopter fully built but i am having some random stability issues. When i take off it seems to drift in one direction, I can counter act this using the RC transmitter but after a while it seems change and will become unstable in a different direction. I have seem may video of people being able to take off nice and smoothly and just hold in one position this is not possible with min. The artificial horizon shows when on the ground everything is level...

 

any ideas?

 

Cheers

Chris

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Replies

  • emile November 5, 2010 at 10:12am
    Having your copter leveled on the ground doesn't necessary mean it is leveled in the air....
    Here is IMHO a good tutorial on how to setup the offsets correctly:
    1. Set the ready to fly frame on a leveled surface, you need to do it for couple of times, so get something that you can recreate this position (eg. floor)
    2. Calibrate youre accs. (z is 408)
    3. Set trim to 0 on the TX, and fly it in no wind condition (but no indoors!)
    4. Now trim it in the air to get it leveled. Yes Trim!
    5. Go back to the leveled surface, whit the TX on and trim from the flying you just did.
    Connect to the configurator, in Raw Sensors Data you'll see roll & pitch adjust.
    correct accs offsets to get this to 0.
    6. Set your TX trim back to 0, and you good to go

    This ensures you have the setting for a leveled quad in the air.... and no trims on the TX!

    Of course this should be done after you calibrate your ESC's.
    To calibrate plug directly your ESC's in the throttle channel of your RX, set TX to max throttle power your ESC wait for two beeps (usually) and set throttle to 0. Do this for all four. This ensures you have all motors responding at the same way.

    Hope this helps.
    Emile

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  • Developer
    Jani Hirvinen November 4, 2010 at 8:52pm
    And did you calibrate your ESC's manually ?? I doubt that it's your battery that moves.
  • Sebastian Gralla November 4, 2010 at 7:59am
    is it unstable or just drifting?
    that's a difference
    is it oszilating?
    do you fly in stable mode?
    have you adjusted the PIDs?
  • Developer
    Jani Hirvinen November 4, 2010 at 7:45am
    7.4V LiPO?? Are you using 2S liPO for your main motors too?? Ok it can work but not sure if there enough authority on motors, at least their lift will be rather minimal with 2S.
  • Peter Seddon November 4, 2010 at 7:06am
    This could be caused by many things not least drift in sensors, sensors not zero'd, badly balanced 'copter, poor calibration, or even possibly over optimism as to the likely drift. How quickly does it drift? Are you sure it is not caused by the location you fly in? Have the 'copter control loops been optimally set?

    Peter
  • 3D Robotics
    Chris Anderson November 4, 2010 at 5:58am
    It might have something to do with your platform (motors, esc, etc). What are you using?
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