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My new octocopter frame

Posted by Peter Koch on March 13, 2011 at 2:30pm

This is the new folding frame Project I am working on.

3689393875?profile=original

Can anyone tell me if it´s possible to control the eight counter rotating motors with ACM.

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Comments

  • Denny Rowland April 13, 2011 at 2:42am
    That is true, the only benefit is from redundancy. I have run tests on a rig that prove this beyond any doubt.
  • Denny Rowland April 12, 2011 at 8:51am
    It could still work with Contra rotation on each arm. in fact probably better than conventional quad. The rudder input just alters the torque bias from the top motors to the bottom ones. To introduce a redundancy feature why not have top motors on one FC and the lower ones on the bottoms ones?
  • DaveyWaveyBunsenBurner April 12, 2011 at 6:43am

    @Peter,

     

    Do you know why it is inefficient? Is it more efficient to counter rotate? This puzzles me!

  • Peter Koch April 12, 2011 at 6:38am
    Yes that will work but it is very inefficient the better solution is the Coaxial setup.
  • DaveyWaveyBunsenBurner April 12, 2011 at 6:12am

    @ I.S Those are a little bit better than my diagram yes :)

     

  • DaveyWaveyBunsenBurner April 12, 2011 at 6:04am

    Fogive the ridiculous diagram (I have neither the time, software or patients to do a better job) but I've never understood why the yaw issue arises on an 8 motor quad. Would this not work?

     

    3692196838?profile=original

  • Peter Koch April 12, 2011 at 5:48am

    @Denny

    it is not a problem to get it working you just need a software that can control 8 motors seperatly.

     

    @I.S.

    At a normal quad configuration you have two CW and two CCW motors for example yaw left - you speed up the CW motors an slow down the CCW motors now on a X8 configuration with splitted servo signals to two ESC´s on each arm you almost have no tuning moment as the counter rotating configuration will compensate any turning moment so you definitely need a software which can control 8 motors separately. So for the example yaw left function on a X8 config you have to slow down all 4 CW motors and speed up all 4 CCW motors on each arm of the quad.

  • Denny Rowland April 12, 2011 at 3:42am

    Looks like Bros. Olson got it working OK

    http://vimeo.com/9435221



  • Peter Koch April 12, 2011 at 3:20am

    Splitting the servo signal to two ESC´s is not only inefficient its more unusable as of the counter rotating motors you have no tuning moment and therefore you will have no yaw function.

  • DaveyWaveyBunsenBurner April 12, 2011 at 2:06am

    @Robin

     

    Apparently that is a problem, but a number of quads, and Tri copters use this arrangement. The Draganfly for example. Although I've heard the prop wash is an issue, a massive number of small/toy RC helicopters use this arrangement, so I'm not so sure its a big problem as they tend to be small and need stability. Jani mentioned a while back that unless you have a copter board specifically configured for this arrangement, simply splitting the servo signal to two ESCs per arm will work but is inefficient.

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