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Using F.C. inputs on a three axis gimbal.
  • avendlerdp
    Hello all-

    I have a board with a third axis expansion and it works well but I would like to improve it's performance by connecting it to the camera outputs on my Naza M flight controler. Can this work on a 3 axis setup? Seems like as the camera moves in the yaw axis there would be no way for the alexmos board to know where the frame has rotated to and make use of the F.C. info.
  • gtranquilla
    Very good question..... I have been wondering about that as well since most FCs do not output gimbal yaw control via pwm...... perhaps s.bus would carry all the data including magnetometer data for horizon position..... but not yet likely.
  • Garug
    The problem with yaw is that there is no other reference than gyro and gyros do drift.

    On Roll and Pitch there is also acceleration and on steady platform that is good, but when flying it gets confusing as the acceleration is not steady 1g directly pointing to the centre of earth, but the aircraft movements cause accelerations too. The FC gets the remote controller inputs and at least in theory has the best knowledge of the aircraft attitude (Pitch and Roll). This is why the FC connection could be useful.

    Now some FCs have compass and GPS connected so they also know where the North is and to what direction the nose is pointing. This could be useful but not very accurate information to provide to the gimbal controller. and the gimbal gyro still drifts.

    However I think it would be more useful to have the gimbal accurately referenced to airframe and to do that a potentiometer measuring the gimbal yaw angle and FW support for it would be useful.
  • gtranquilla
    I full featured IMU will have 9 to 12 DOF, 3 accel, 3 gyros, 3 magnetometers., etc....and they are larger and more expensive. So IMHO is is not quite appropriate to call these sensors for the BaseCAM BGC, IMUs.
    FC pitch and roll data access can help to a small degree in other ways but s.bus connection to the FC will potentially be the only way to get the FC magnetometer data needed to enable horizon corrections. S.Bus could also provide digital compass data....
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