CS8 HL Strange behavior: Magnet Error

Discussion in 'Cinestar 8' started by Artur Brosig, Oct 28, 2015.

  1. Artur Brosig

    Artur Brosig New Member

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    Hi everyone.
    I'm new here (and on the multirotor world to).
    We have a CS8 HL (purchased from Quadcopter.com) and we've been done some readings and researches trying to understand as much as possible before doing more long flights.
    We've done some test flights, some gone really well, some are strange.We've done 3 tests, on 3 different days, and 3 different locations.
    The first test was on an open area away from the city (https://goo.gl/TXf4SQ) , and the telemetry doesn't acuses any error. We've done some short flights, all occurred well.
    The second test was on the grass on a cinde track (is that right?) here on the University - The picture from gMaps is from the construction, now it's done: https://goo.gl/iN5Yh4. The calibrations occurred well, but after the take off the telemetry accused Magnet Error. I've tried again, same error, just take a little longer to occur. It started a spiral pattern, an we've managed to land it.
    The third test was an an open area close to the University (https://goo.gl/REGTqF). We've done some tests, the same Magnet Error (just take a longer time to occur, and only in the air) and on the last flight the same spiral pattern.
    I've did some reading from the Mikrokopter wiki, and was afraid that with the higher throttle the power cables from the motors maybe causes the interference, but i'm not sure. Thought too on the possibility of the street power lines (on the third day) and some metal structure (on the cinder track), but i'm not sure if it's an valid possibility.
    Any suggestions?

    Thanks in advance.
    Artur
     
  2. Steve Maller

    Steve Maller UAV Grief Counselor

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    Artur, can you take some photos of your copter with everything attached (batteries, etc.)? It might be that something in the way you have it set up is causing this issue. Do you have the MK External Compass?
     
  3. Gary Haynes

    Gary Haynes Administrator
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    Or you were flying at times with high geo magnetic storms. It primarily affects GPS but there have been some really strong storms over the last several weeks. Were you also using your GPS system (gps mode)?
     
  4. Artur Brosig

    Artur Brosig New Member

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    Hi Steve,
    Thank for your attention.
    I took some pictures. If you need more specific pictures just tell me.
    We don't have the external compass. We have only the NaviCtrl 2.0
    In the actual configuration it's carrying an Sony HXR-NX30N, but we intend to put an Red Epic on it. We intend to use with it an Teradek transmitter to.
    Thanks again.
    DSC_4074.jpg DSC_4076.jpg DSC_4077.jpg DSC_4079.jpg DSC_4080.jpg DSC_4081.jpg DSC_4082.jpg DSC_4083.jpg
     
  5. Artur Brosig

    Artur Brosig New Member

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    Hi Gary,
    The last flight was on this monday (26th).
    We were using the gps mode. Actually, on our configuration we checked the option that avoid the copter to fly if there was no gps fix.
    And as i remember, the solar activity was low on this monday.
    I'm using a android app called Solar Activity Kp-Index.. Do you know if its reliable?
    Thanks
     
  6. Steve Maller

    Steve Maller UAV Grief Counselor

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    Actually, I'd try this: disconnect the FPV camera you have attached to the Navi board's mount. Those things can be terribly noisy and I wonder if that could be the cause of your troubles? If so, then you could just move the camera somewhere else.
     
  7. Artur Brosig

    Artur Brosig New Member

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    On the flight tests, it was mounted on FPV camera mount from quadrocopter (http://www.quadrocopter.com/FPV-Camera-Mount_p_1241.html). I tried this after the flight trying to put the gps/navictrl away from the battery/flight ctrl. But i already noticed that it was a bad idea.
    I'll revert this change.
    You think that even with the mount it will interfere (and only during flight)?
     
  8. Artur Brosig

    Artur Brosig New Member

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    Is there a huge difference when using an external compass?
    Do you recommend me to use it?
     
  9. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    The external compass will be further away from the LiPo wires, so yes, it's a good idea to use it.

    But, in the interim, can you confirm that you have the main Lipo wires from the power distribution board held together (either by cable ties or heat shrink). They are not clearly visible in the images.

    if you can tie the wires together along their entire length, the magnetic fields that they create because of the heavy electrical currents will be largely canceled out.

    Andy
     
  10. Artur Brosig

    Artur Brosig New Member

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    Hi Andy,
    They're not tied together in all the length.
    Connected they look like this:
    coĢpia de DSC_4094.jpg

    [edit]The leads to the motors aren't tied together neither (inside of the copter frame). Should i tie then together?[/edit]

    I should tie it on all it extension (inclusively the battery side) or only the copter size?

    About the external compass: were should i put it? I've seen some pictures of it on top of the GPS shield (with an extension support).. I wouldn't make it closer to the LiPo? (at the sam level at last). It isn't a bad thing?

    Thanks again
    Artur
     
  11. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Definitely tie as much of the LiPo wires together as you can -- a cable tie every three or four centimeters. Do that on both the wires from the EC5 connector to the power distribution board and on the EC5 connector to the battery -- wires that are separated generate magnetic fields way stronger than the Earth's magnetic field.

    EDITED TO COMPENSATE FOR BRAIN FADE: Right now the compass is on the Flight Navigation Control Board which is right under the LiPo. It was the folks at Quadrocopter who figured out that having it out on the GPS/Navigation Control board is considerably further away from the LiPo wires. Fortunately, magnetism follows the inverse square law....double the distance, quarter the strength... :)

    Andy.
     
  12. Steve Maller

    Steve Maller UAV Grief Counselor

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    Andy, isn't the inbuilt MK compass on the Navigation Board? I don't think it's on the Flight Control Board.
     
  13. Artur Brosig

    Artur Brosig New Member

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    Oh, i see.
    I thought that the compass was on the Navigation Control board.
    I'll order an external compass and tie the cables together.
    As the external compass may take a long time to arrive, i'll do the cable part and do some test.
    It's better to leave the FPV camera disabled?

    About external interference, like power cables from the street, do you think it's possible that they're interfering with the compass, or it's more an internal problem?
    Thanks again.
    Artur
     
  14. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Oy. Brain frat. Sorry....what was I thinking. You're right. It's on the Navigation Control Board. The FC has the accelerometers and the solid state gyros. Duh.

    Andy.
     
  15. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Artur: As Steve has pointed out the compass *is* on the Navigation Control Board. But of course it's still susceptible to electromagnetic interference. The power cables across the street are not so much likely to be causing electromagnetic interference, but anything that has a high current going through it and is close by will do.

    Andy.
     
  16. Jason Smoker

    Jason Smoker Active Member

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    I also cable tie all my motor wires together just for piece of mind!:rolleyes:

    You could also try moving your fpv receiver from laying under to facing top with antenna facing the air sometimes it only takes one thing moved to solve it.
     
  17. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Also, if you connect up via MK Tool to either the Flight Controller or the Navigation Controller (if you connect to the FC you can "talk through" to the NC) you can read out the compass values in real time using their "scope" mode -- then you can see whether or not what you're doing is improving things or making matters worse.

    Andy.
     
  18. Artur Brosig

    Artur Brosig New Member

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    Hum,
    I'll try all your suggestions today (cable tie the motor wirres and LiPo wires, change the position of the FPV transmitter and read the compass values under MKTool).

    About the external compass: as the internal compass is on the Navigation control, it is a bit away from the higher interference (power distribution, LiPo, Fligh Ctrl board) will make a big difference install an external compass? It is so more precise and less susceptible to interferences? And where should i put it? On top of the GPS?

    Artur
     
  19. Dave King

    Dave King Well-Known Member

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  20. Artur Brosig

    Artur Brosig New Member

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    Hi Dave,
    The version 2.12 isn't in beta?
    I thought that because through the MKTool update it isn't listed...
     

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