360 degree roll

Discussion in 'Radian' started by Tim Joy, Nov 19, 2012.

  1. Tim Joy

    Tim Joy Active Member

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    For gimbals that can roll 360 degrees, will the radian handle this and stabilize upside down and/or portrait orientation?
    Will it roll multiple times?

    Same question goes for tilt, although I'm sure it would be the same answer.
     
  2. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    I don't know the answer to this off-hand. Let me see if JohnC has time to answer.

    Are you going to use slip rings for the wiring? I could imagine some wires twisting or "wrapping around the axle...."

    Andy.
     
  3. Tim Joy

    Tim Joy Active Member

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    The wiring would either feed through a large shaft and have the ability to twist a few times, or be stationary with the axis, like the pan axis on a CS360.

    Also related is how the tilt radian would react to a 360 roll in a 2-axis gimbal. (Same hierarchy as the CS)
     
  4. John Cunningham

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    The IMU in the Radian will keep working if you roll 360 degrees, but it isn't designed for this situation and the problem will be that it's internal gravity-based corrections will be working in the wrong sense if it is upside down.

    So the answer is that it should be OK if you roll right around, but don't use it to actually hold it upside down for any length of time.

    The roll axis is optimised to work to keep the axis level, which allows the tilt axis to have special algorithms to allow full stabilisation (+IMU corrections) while the axis goes down through -90 degrees.

    If you want to stabilise a camera at 90 degrees roll, the best results will be obtained if the roll Radian thinks it is stabilising to horizontal - so it should be mounted accordingly.
     
  5. Tim Joy

    Tim Joy Active Member

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    Thanks for the response, John.
    Reorienting the Roll radian for portrait orientation is not a big hurdle.
    The problem I see then is the tilt radian, which would effectively become pan.

    Since I'm not familiar with the radian, is it possible to deactivate the stabilizing/ or reduce the gain to 0 on the fly, but still maintain manual control of the axis?

    Also, will the tilt radian stabilize through 190-200 degrees of rotation? Or is it limited to 90?
     
  6. John Cunningham

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    The tilt module is limited to go through about -270 degrees if memory serves correctly, but the main issue like you say is that the sensing axis gets messed up. Plus you would have no tilt control at all.

    I think it would be infinitely easier to make an L-bracket and stand the camera on it's side.

    Maybe this kind of adapter is an idea for Freefly to offer for the Cinestar mount ...
     
  7. Tim Joy

    Tim Joy Active Member

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    I have some more questions about the Radian, maybe this can be the thread for all the weird questions. :)

    These can probably be answered by a proper spec sheet, but I have not been able to find one:

    1. Assuming I have a 100% backlash/slop free servo drivetrain, and if it were geared to produce infinite resolution (for the sake of argument), what is the maximum angular resolution the Radian can achieve and output through PWM?

    2. Is it possible to control the axis un-stabilized? (Roll) Then smoothly switch to stabilize mode?
     

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