Uncontrolled Yaw

Discussion in 'Electronics' started by Anthony Shorten, Apr 13, 2014.

  1. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    If you suspect it's the compass (and there's no evidence that I can see in the GPX file that it is), then use MK Tool to set the Compass Effect to zero and see if that changes the problem. See http://www.mikrokopter.de/ucwiki/en/MK-Parameter/Misc

    Also please confirm you see the number 3 at the bottom of the screen to the right of the red triangle.

    Did you also calibrate the ACC (accelerometers) with the FC board absolutely level -- you only need to do this one -- it's not like calibrating the gyros which you do before each flight.

    Thanks
    Andy.
     
  2. Steve Maller

    Steve Maller UAV Grief Counselor

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    [i just wrote this on your post on the MK forum, too]

    Something is seriously wrong with your motor alignment or configuration. Your average current draws are way out of whack...your odd motors are pulling THREE TIMES the current of your even motors. Do not fly it again until you figure out why. Do you have all your props on properly? Do you have all your motors spinning in the right directions?
     
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  3. Gary Haynes

    Gary Haynes Administrator
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    What Steve said. Looking at your photo the props look like they are on in the correct orientation. Check that the motors are all rotating in the correct direction. Check the props, use a marker on the hubs to number them and take them off. Then use MKTool to run each motor individually without the props. I take a strip of paper and punch a hole through so that it spins with the prop. Sometimes hard to see the actual motor motor direction otherwise.

    Check for motor alignment. With the props on do the tips when brought together on adjacent motors align? If not then your motors are not vertical.
     
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  4. Adam Paugh

    Adam Paugh Distributor

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    Hello Anthony,

    Okto2b is a mixer file we had MK develop for the CineStar-8 variant Oktokopter.

    Greetings,
    Adam
     
  5. Dave King

    Dave King Well-Known Member

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    Anthony looking at your GPX file it looks like it was responding correctly up until about datapoint 33 where i see you giving it left and right yaw and the copters heading doesn't change. At datapoint 36-37 you are giving it a left yaw command and the copter isn't responding either. Usually if the motor alignment is off you will get uncommanded yaw but I have seen some strange things happen.

    When you set the ACC(Left stick upper left) before the flight is there anyway the copter was yawing while you were calibrating? That terrain you were flying in looks pretety rough and I bet you were scared out of your mind (not that you would be less scared anywhere else). Have you tried recalibrating the ACC (left stick upper right)while making sure the flight control board is level? Just wondering if something flaky happened when you calibrated it like some unwanted movement.
     
  6. Anthony Shorten

    Anthony Shorten New Member

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    Thanks Dave, I aligned the motors on the cinestar without the mount on, and the acc calibration (upper right) was done at home on a perfectly level surface. This is the third random time in a year that it has happened. I just picked up a new FC board today and external compass and I will try it tomorrow and see if that makes a difference.

    Thank for the advice

    Anthony
     
  7. Dave King

    Dave King Well-Known Member

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    I don't think the external compass will help as you are seeing this issue with GPS off. IF the problem is hardware I would think its the flight control board. I can understand why you want to switch it out and not take a chance.
     
  8. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Anthony: I know this sounds like I'm being a bit anal (I am!), but when you say, "on a perfectly level surface" was the actual flight controller board level measured at the FC board itself? I take the gimbal off, lay the copter on the table, and then use a spirit level laid across the top of some nylon standoffs that I've put on all four FC posts to make sure the FC itself is absolutely level. I use partial pads of Post-It notes to shim the boom arms to adjust it until the FC is level in both axes.

    Hope this helps.

    Andy.
     

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