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Setting screenshots and sample video: what to do to improve stability
  • sasa74
    Hi everyone,

    My configuration is next:
    X8,
    RCtimer ASP gimbal 3axis,
    Sony NEX 5n, 16 2.8,
    Tattu 6s 16000.

    I`m really tired with trying and missing :-) to adjust gimbal for video. So there are setting screenshots and a video that i got with this settings. Wind was around 10km/h from south- Please give me advice and suggestion how to smooth gimbal for video.

    http://postimg.org/image/p8x61lswh/

    http://postimg.org/image/spz84kryp/

    http://postimg.org/image/k8zptnn9t/

    http://postimg.org/image/ae8knfjbl/

    http://postimg.org/image/z8s2hi45t/

    Video:


    Thank you in advance
  • Garug
    PID are rather low, activate adaptive PID after everything is ok on normal flying, Yaw follow speed is really high, voltage is high, max voltage should be 25. It could be ok, but can also break something.
    You should get rid of all I2C errors.

    Video is private, so I can not tell anything about the result.
  • sasa74
    hi, thank you for your answer. Voltage was not right, it is 22,89 now. I have put follow speed to 100. Try to check video now....
  • Garug
    There is serious problems on that gimbal, the stabilization is not good at all. One reason might be the dampening, is the gimbal swinging a lot? it looks like it is and because of the low PID the gimbal can not correct fast enough, but could be something else too.

    Would be good to see some pictures of the hole gimbal installation, especially vibration dampening and camera installation.

    I looked the gimbal on google, not really solid construction, I would not expect a great performance from it, but should do much better than on the video.

    You should make sure that there is no free play, based on the result there probably is. Removing the free-play probably requires some modifications to motors, at least adjusting them.

    Making the gimbal as compact as possible, maintaining the balance will improve the performance too, first improve the mechanics and then retune.

    Try auto tuning. First disable adaptive PID and follow. The autotune one axis at the time, starting from pitch. use good stability settings first, and experiment how changing that effects.
  • sasa74
    Thank you, I will try to do things one by one (except adjusting motors) :-). Here are pics:

    http://postimg.org/gallery/1p9d8e6r4/
  • Garug
    I would:

    1. Modify the gimbal so that you get camera as close to pitch motor as possible (i.e. change the finger screw to normal screw. )

    2. shorten the arm between roll and yaw motor as much as possible.

    3. rebalance the gimbal

    4. Tie cables better and make sure that no circuit boards etc. are hanging free. no loos mass on the gimbal!

    5. run IMU cable separately from other cables and make it as short as possible.

    6. make sure camera is well attached, improve the attachment if needed.

    7. make sure that IMU is well attached.

    8. make sure all motor screws are well attached (but be careful not to use too long screws.) at least pitch motor is missing screws.

    9. The battery tray standoffs are really long. are they strong enough? they could cause bad shakes.

    10. make sure that motors rotate freely and have no free play.

    11. the battery installation would give good opportunity to balance the gimbal around vibration dampers. i.e. attach the battery directly above yaw motor and change dampers to stiffer to cary also the battery load. This is quite advanced, but could provide great improvement. http://www.rcgroups.com/forums/showpost.php?p=30057919&postcount=3

    Is the yaw well balanced? looks back heavy.

  • sasa74
    Hi Gaurg,

    i did auto PID separately and it works great and smooth, no vibration. But :-), yaw is not going in center, after first turn (left or right) it stays in this position...here are new settings

    http://postimg.org/image/4md8s08nf/
  • Garug
    How are you turning the yaw? is the yaw well balanced?

    The Pitch PID looks really low compared to other axis, maybe bad camera installation? did you move the camera close pitch motor and rebalance. Making the gimbal more compact will improve it.
  • sasa74
    Hi Garug....so all axis ate doing great, follow also. Only problem are small contiunous vibrations. I will try secraft anti vibration and then let you know. :-)
  • sasa74
    Here is last video with secraft mounted...still small vibrations

  • Garug
    There is a serious problem with horizon. pay attention to gyro calibration. if it is performed each time gimbal is started, the gimbal must be steady during that time.(from the power on until the gimbal starts working.)

    Also pay atention to pitch and yaw control/follow settings.

    The remaining vibrations look like turbulence related. does the propeller downwash hit the gimbal. Listen the sound , it sounds like constant air-blow over the camera.

    Also could be that PIDs are stil low and the gimbal is not fast enough to react to sudden movements when descending etc.
  • sasa74
    Hi Gaurg, if its prop downwash, how to remove it?
  • Garug
    removing the gimbal from the downwash, probably requires longer arms for the multirotor.

    If you look the multicopter from top and imagine the circle that the propellers rotate, is any part of gimbal/camera below it. If it is or very near, then it potentially is propeller downwash.

    I have one small GoPro encoder gimbal with strong motors that works exceptionally well despite it is clearly under propeller downwash http://www.levitezer.com/styled-2/blog-2/index.html (11/07/15 post) But it is small and very fast and strong gimbal...

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