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external encoder transmission ratio
  • soul
    Hi, I successfully modified my brushless gimbal motors, added magnets and encoders.
    But I do need the hollow axis. So I am thinking about positioning the encoder next to the Motor and turn the magnets like a gear. I think in the paid firmware version I cant change gear ratio? so just 1 /1 is possible? Has anybody done such a mod?
  • Garug
    Probably better use one of those encoders that have a hole trough.

    Other than 1/1 gear rations are supported, but typically the encoder is on motor. Also if you put the encoder on the side of the motor, it is important that it always keeps the same synchronisation with the motor.
  • soul
    With same synchronisation you mean the same direction, when ratiodoesnt have to be 1/1?
    With a hole through you mean encoder and magnet do have a hole for a slip ring? That would be a good solution! Do you have a source for that?? I am hapyp with the GB Motors, so just a new encoder and magnet would be perfect! THX!
  • Garug
    See the encoder user manual for the encoder options.

    If it is on motor side it must be with a gear that does not slip so that the synchronisation remains.
  • soul
    Thinking of changing the design from single arm to standard... one side the encoded motor, the other with bearing and slipring. Thanks for your help and time Garug!
  • Garug
    Just remember it need to be fixed so that encoder positioning does not change related to the motor, during installations, adjustments etc. Better to have the encoder attached to the motor.

    AMT203 encoder has pass-throw hole
  • alexmosalexmos
    "Thinking of changing the design from single arm to standard... one side the encoded motor, the other with bearing and slipring. Thanks for your help and time Garug! "
    Garus is right - this kind of setup will not work, because it allows slightly out-of-sync between encoder and motor.

    Mounting encoder near motor (off-axis style) is possible, but it obligatory should not slip, i.e. should be linked by belt drive or gears, with minimal backlash. Different gearing ratio for motor/encoder and motor/frame are supported, but it may cause problems with the detecting of the absolute motor angle or frame angle at the startup. For the ROLL and PITCH axis information can be obtained from the 2nd IMU (angles between 1st and 2nd IMU allows to detect roughly angles in each motor), or system should be always powered up close to the normal position. But it's better to keep 1:1 ratio and avoid such ambiguity.

    Regards, Aleksey
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