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Vibration occurs when battery is full
  • ReNNo
    My gimbal preforms very well, it is stable and precise. But I noticed that gimbal starts vibrating when I connect fully charged 3S battery.
    What is the best way to eliminate these vibrations?

    I use DIY 3Axis GoPro gimbal and 32 bit basecam board.
  • Garug
    Use compensate voltage drop an if necessary adjust power.
  • ReNNo
    Thanks Garug...
    I turned on this option and also calibrated voltage. Looks like vibrations are gone.
    But I noticed that vibration mostly occur when ambient temperature is lower...
    And there is no compensation for temperature xD, heh
    We will see tomorrow ...
  • ReNNo
    OK, I solved problem with vibrations when battery is full by turning on "compensate voltage drop" option.
    But vibrations are still present when I fly outside in lower temperatures.
    What can I do for this problem? I lowered gains but I still can notice vibrations in some situations.
  • Garug
    How cold is this, I have been flying at -15 degrees Celsius. On those temperatures the motor bearings could get stiffer because the oil in them gets stiff. also Vibration dampers get stiff. Gyro should be calibrated in cold (gyro only), after it has been long enough in cold. Maybe you should tune the PID in cold. Are you sure the vibrations during flight are because of the cold.

  • ReNNo
    It was about 7 degrees Celsius outside. My quadcopter was inside warm car and I was flying great for 1 minute. And then vibrations started. Looks like high frequency vibrations from yaw or pitch motor resulting blur image.
    Gyro is calibrated on power...

    Same thing happens when I test gimbal inside... I keep quadcopter in cold room.
    Turning gimbal on I can notice some vibrations but as gimbal heats up these vibrations disappear.

    When weather was warmer I didn't notice any vibrations... only factor than I can think of is temperature.
  • Garug
    Have you tried restarting when the vibration starts, so that the gyro get calibrated when the temperature has settled. Ok, I suppose starting in cold room and bringing it warm kind of test that.

    What axis is vibrating. Have you tried retuning or filtering? What board FW? Try lowering PID values some 20 % for the axis that vibrate. Maybe also adaptive filtering. Is this one or two IMU setup?

    The IMU is electro mechanical devise and sure temperature affects it. Should be though possible to get it tuned so that operates also on cold.

    How is the IMU attached? This is actually much possible reason for problems when temperature change. I have had some problems with two sided tape + 4 screws installation. Just two sided tape is much better, or only screws. For cold conditions maybe two sided tape would be better. The problem is that different material react differently to temperatures and this could cause pending moments etc. to the IMU.
  • ReNNo
    I tried restarting and it didn't solve vibrations.
    First I noticed that pitch is vibrating and I fixed it by lowering gains and power for pitch.
    Second test was much better, only some vibrations from yaw. I want to run yaw motor on higher power and gains so it can hold more precisely when fighting with prop wash. Lowering power makes it less precise and with higher power it starts vibrating in some situation when temperature is low.

    I played with filters earlier and managed to get rid of some vibrations, they were gone until cold weather started. And adaptive filters helped a lot.
    Now I need to retune gimbal for cold weather and that is time consuming job.

    Camera IMU is glued behind camera and Frame IMU is glued to YAW motor. They are very precisely glued. I am aware that frame IMU gets warmer as yaw motor heats up but I didn't notice any strange behave of gimbal as it heats up.
    IMU senors are sensitive to temperature, I experienced this with other project I'm working on. But also I noticed that different samples of MPU6050 can behave very different on temperature change. Some samples where drifting very noticeable on some axes and some samples were almost immune to temperature change.
    I think that I got good samples on my gimbal because I didn't notice any drift as it heats up.

    Maybe some controller components are sensitive to low temperature and resulting power to increase. I'd like to see if someone can find some proofs on this any maybe implement some temperature compensation algorithms in future.

    btw, I use latest version 2.43b6.
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