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osilications with extreme angles
  • danallen
    I have the 8-bit 3-axis AlexMos board with a custom 3-axis gimbal. Once you go 40 degrees on the tilt it will start to oscillate both tilt and yaw. Roll is surprisingly stable past 45 degrees.

    Are there any ways to solve it? I will try to retune the tilt from the start with high power.
  • Garug
    Are you already using the 'estimate angles from motors' (only available in FW 2.4)
  • Ecopter
    Hi, make sure of 2 things, first is that the gimbal glance AND geometry is PERFECT ( many gimbals have a very bad geometry, arm lengths differences, alignment..) ... Then Balance is the most delicate thing at extreme angles.
    The basic test to make also as sometimes some IMU PCB's have the IMU chip itself misplaced, is to lock the roll arms on anything and slowly move the pitch manually ( turn motor off in the gui). If Roll and Pan move also, you need to review the IMU location and position, do not hesitate to rotate it a bit until the pan and roll do not move anymore or only very, very small amount ( look at the blue arrow on the angles indicators in the GUi for this).
    Make sure also to have the right motors poles count + direction ( you can use the AUTO function for the direction correction but magnets auto detection function is not working very well in some cases, especially big motors).
    Best regards,
    Fabien
  • danallen
    Fabien thanks very much.
    - I tore apart my gimbal to rebalance, align, and bring the axes closer to CG. This helped a lot.
    - The IMU was correctly aligned in the GUI, but it was vertical. So I tried relocating the IMU closer to CG and also mounted it horizontal. That also helped.
    - I never had luck with the auto function, luckily I know they are 14 pole motors.

    So as of yesterday, I could roll the gimbal to the physical limit. And the tilt motor can go about 50 degrees! Big improvement thanks!
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