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YAW
  • garetsix
    I wonder HOW the system can recognize the angle between HANDLE and CAMERA.

    I am tryng to set the yaw to follow OR angle based movement (with joy).
    The system can recognize the ROLL and PICTH angles using IMUs, but the angle between handles and camera CANT be recognized by IMUs (when i turn the handle on the Y axe only handles move, the rest of camera and two IMU stay stopped)

    I cant understand HOW system recognize how many degrees we have between the new position of handles and the camera on Y axe.


    Is there any video or tutorial about How to SET up YAW?

    Thx in advance, L.
  • Garug
    You are right, the yaw do not have the ACC as absolute reference, but is still have the rate gyro and the angles can be estimated from motor if that is activated. Yaw startup position however is difficult to get right every time if starting at follow mode.

    For that reason I always start in non follow mode, set the yaw as needed and then activate follow mode.

    The system does not need to recognise how many degrees the handles have been moved, it just tries to keep the camera in place based on the gyro and ACC (+ estimate angles from motors).

    Normally you do not need to worry about this stuff. Just tune the yaw and activate the Follow Yaw and tune it to your liking.

    Ps. There is also way to have absolute yaw reference like described in here http://www.rcgroups.com/forums/showthread.php?t=2243241

    and also the encoders provide that http://www.basecamelectronics.com/encoders/
  • garetsix
    ok, great (and thx).

    But.. if YAW are not referenced by IMUs and no others sensors. IF (or better: WHEN) i loose the "zero" of the yawn (e.g. the follow still works but not at the proper degree) how can we "reset" it?

    I can calibrate again IMUs for PITCH and ROLL, how can i re-zero YAW?

    This looks like a BIG system failure, NO SENSORS for an axe!

    How can we reset YAW position without PC connected?
  • Garug
    But there is references for yaw:

    1. Rate gyro on Camera IMU
    2. estimate angles from motors, if used
    3. Rate gyro on frame IMU, if used
    4. on encoder gimbals there is absolute reference to frame. Kind of same as estimate angles from motors, but much more reliable. The Yaw potentiometer also does the same thing.
  • garetsix
  • Garug
    IMU is involved on Yaw for the gyro part. that is also the part you can calibrate in IMU for yaw. If not calibrated, the yaw will drift.

    For yaw follow I do not know the algorithms involwed, but I suppose it much depends is one or two IMUs used and where the frame IMU is installed. Probably and quite likely the motor is used to detect the deviation from handle. and most likely yaw encoders are used for this purpose if they are installed, and for sure yaw potentiometer is used for this purpose if installed.

    But I fail to see is this a theoretical question, or is there some actual problem you have with the gimbal functionality?

    If you want to "Zero" the yaw to centre after bad disturbance certainly, you need a gimbal with encoders or Yaw potentiometer. With two IMUs it works quite good also without them, but not always.
  • garetsix
    Garug, my problem is that yaw follow WORKS, but sometimes the "centre" angle change and i can't reset it to the center (means frame have same angle that handles)

    now, pls, imagine:

    watch the gimball from above.. we have an initial position expressed in degree, imagine exactly NOTH (for example).
    All, camera, frame and handle are facing north

    follow is like that:
    1) i rotate HANDLES 30 degrees on right.
    2) Frame (and camera) are still facing NORTH
    3) slowly camera start rotating
    4) nowcamera reach the new (30 degrees south) handle position

    man.. the point (2) means that both IMUs (frame and camera) are still north at the beginning of the job
    this means that when i rotate HANDLES nothing at all happens to IMUs
    this means that IMUs are NOT involved in YAW movement..

    this must be CLEAR

    the only things that happens is the ROTATION of the yaw motor
    but..

    we have no encoders
    no potentiometer..

    NO WAY to reset yaw angle positioning.. or not?
  • Garug
    You can try Home, but probably will not help much. You could set it manually, but better with joystick.

    The gimbal know nothing about North or South, the indicator on GUI is misleading on this regard. ( and though those indicators are useful they are not always that understandable.)

    I do not understand what must be clear. Of course IMUs are involved in yaw movement. they stabilise it all the time. Also if frame IMU is above Yaw it can detect the direction changes of handle, and camera IMU can follow it, I do not know though if it is done like this on the BaseCam board.

    As mentioned earlier, if you want to have the yaw centring reliable, you need to have potentiometer installed or encoders. (or maybe frame IMU above yaw, but I have not tried that, in theory it could work .)
  • garetsix
    ok, i'll try again :)

    connect the GUI, power OFF motors then go in the MONITORING page.

    now: move manually camera pitching down or up, youl'see ACC and Gyro variated value
    move manually camera rolling, value change.
    now move HANDLE on the vertical axys. NO value change. The reason is: when you move ONLY handle on vertival AXE everithing is under the yaw motor silmply don't move.

    it WILL move only if follow yaw motor start moving it to reach the new handle position.

    it means that for the IMUs (both Acc and Gyro) if you move on left or right is exactly the same..
    the IMUs are NOT involved in yaw following. they simply CAN'T sense the rotation of the HANDLE..

    this should be clear, but you tell that IMUs are involved in yaw..
    i REALLY can't understand HOW, cuz of the fact that when we move HANDLES camer is NOT moving by itself.
  • garetsix
    example 1: moving the handles pitching:

    [url=http://s14.postimg.org/f0juhegyp/esempio1.jpg][/url]


    example 2: move handles on vertical axes

    [url=http://s15.postimg.org/u3605uhaj/esempio2.jpg.jpg][/url]


    in FACT, when we move handles on vertical axys the rest of the system dont move, it means that for IMUs nothing is happened.

    It means IMUs are NOT and NOT at ALL involved in YAW Follow.



    Right?
  • garetsix
    i FINALLY solved this problem!!

    i'm so happy you can't believe :D
  • Garug
    I am still a bit confused what was the problem, but good it is solved :).
  • aeropix
    Please, tell us what solution you have found.

    Thanks
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