Movi roll motor and airborne issue

Discussion in 'MōVI M5' started by Alistair Bullock, Jul 9, 2015.

  1. Alistair Bullock

    Alistair Bullock New Member

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    Hi Guys,

    I have been in touch with the tech support at Freefly and they have been amazingly helpful and they suggested I posted my issues on here to see if you could help me. I am flying a Cinestar 8 with Movi M5 and a Panasonic GH4 w/ a Lumix 14-140mm lens.

    I am getting vibration in my video. I originally thought it was from the o-rings (blue) not given enough freedom between the movi and cinestar. I have made the gap bigger and it helped slightly. I am now having issues with my roll motor when in "airborne" mode, when in "handheld" there is no issue. The roll motor oscillates no matter how stiff I make the Roll motor. I have spoken to Chris from Freefly and he mentioned changing the Gyro Filter and Output Filter.

    As per the description on the freefly app for these filters, I need to increase as I am getting fast, small movement (like a buzzing). I have changed the stiffness and filter settings but there is still the issue. I have the camera properly balanced when the motors are off. I get no movement no matter what postion/angle I place the Movi/Camera in.

    I have attached a video showing the shake but it is password protected so the password is: pixelbuzz
    (This is my company name)


    Just to give you guys the stats of my Movi saving you time in asking.

    Autotune at 50% (It was at 75% but Freefly tech support said put it down to 50%)
    Pan Stiffness @ 140
    Roll Stiffness @ 10
    Tilt Stiffness @ 10
    Gyro filter @ 7
    Output filter @ 7

    Other points for you to know, I am using autotune and manual tuning. My props are balanced and I have now turned IS off on my lens and camera, in the video IS is on.

    The main issue I am having now is the Roll motor, I feel that sorting this, having IS off and making sure the o-rings could move properly will sort my issue. Just as more information, when I power up the Movi the Roll motor oscillates a lot then calms down to small oscillations, also when using my DX8 as a remote for the Movi, if I use the throttle stick left and right to control the roll, there will be major shake when I let go of the throttle stick.

    I think that is everything, any help would be greatly appreciated!

    Cheers

    Ali
     
  2. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Ali:
    1. Did you do the autotune with the copter resting on the ground or suspended? (Should be suspended.)
    2. If you have the copter suspended, but NOT powered up, and the MōVI powered up, do you still see the "major shakes" when you let go of the DX8 throttle stick? (I'm pondering whether there might be some interference from the copter -- pure speculation, of course.)

    Andy.
     
  3. Alistair Bullock

    Alistair Bullock New Member

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    Hi Andy, thank you for your response!
    1. I did it resting on a table, I will try suspended.
    2. I first noticed the shake when in handheld mode when it was sitting on it's stand.

    Cheers,

    Ali
     
  4. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Ali: Yeah, you will find that depending on how the MōVI is supported (one hand, two hand, in stand) you get different resonance responses and thus you might see oscillation when you change how it's supported...as I say, the physics gets complicated when it comes to three axis waggling things... (you can tell I studied physics, can't you? :rolleyes: )

    Andy.
     
  5. Gary Haynes

    Gary Haynes Administrator
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    I don't know that I saw it in roll in your video. I do see vibrations. Looks more like tilt and the IS being turned on. What focal length on the zoom? Couple of questions. Was the copter panning or was that the camera op? Hovering flight is always the worst situation since the copter is sitting in disturbed air. Consider mounting a GoPro to the back boom pointing at the back of the gimbal. Analysis might help you isolate the vibration. Try to mount it on the Cinestar boom. If it is the copter vibrating it would show up, at least most of the time. And you can hopefully see how the gimbal is behaving.
     
  6. Henry Symons Jones

    Henry Symons Jones New Member

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    Hi Andy, I seemed to have missed out on the fact the Movi should be attached to a suspended copter when tuning, I've always tuned it on the stand and then attached it copter. How to recommend suspending the copter to get the most realistic results - bungy cords? Thanks
     
  7. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Any convenient means at hand, Henry. Bungee cords, rope, or even an assistant camera operator or assistant director holding the booms of the copter. The latter idea also adds meaning to the AC's or AD's otherwise drab existence and so I believe it is quite widely used. :rolleyes:

    The idea is just to get closer to in-flight dynamics -- and the MōVI doesn't "know" whether the copter is actually airborne or not, but the MōVI is free to rotate and experience the different dynamics of not having the landing gear on the ground.

    Andy.
     
  8. Henry Symons Jones

    Henry Symons Jones New Member

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    great thanks for that Andy - I always wondered why I bring a camera op along with me, finally it all makes sense!
     
  9. Alistair Bullock

    Alistair Bullock New Member

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    Hi Guys,

    I suspended the copter and autotuned. I then placed it on the table changed some of the stiffness settings and had no issues, then once I wrote the settings the roll motor starting "buzzing" again, fast but small oscillations. Should I autotune, tune and save settings all suspended?

    Gary the roll wasn't in the video but is now a new issue. The camera op was moving the gimbal it was not pan drifting. I am getting hold of a handle bar go pro mount so I can see what the issues are. I would like to get this roll motor issue sorted before I take it for another flight to see if there is no shake now I have turned IS off.

    Cheers,

    Ali
     
  10. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    The short answer is, yes, Ali.
    You may find that you will get oscillation when the copter is then parked on the ground. The dynamics are different when the landing gear are on the ground. You can use the Chart options to see which axis is oscillating by the way.

    Andy.
     
  11. Alistair Bullock

    Alistair Bullock New Member

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    Hi Andy,

    I have autotuned, manual tuned and tested all suspended and then took for a test flight. Below is my video of that test flight plus the original video and suspended test video too.

    On the Chart, are you after a perfect flat line or just very small movements?

    The password again is: pixelbuzz
     
  12. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Ali:
    On Chart I presume you're looking at the Motors? If so, you'd expect to see small variations. If you are seeing "wallowing" (which implies that the MōVI is not responding fast enough), I would try increasing the tilt stiffness very slightly.

    By the way, you have your FPV transmitter antenna almost touching the antennae of the MōVI Receiver. Not a good thing -- that Transmitter is radiating RF power and when that close to the MōVI Receiver, it almost doesn't matter what frequency the transmitter is working on -- I'd move that FPV transmitter as far away from the MōVI Receiver as you can. The signal strength from the FPV transmitter falls of subject to the inverse square law, so if move it only a few centimeters, it will help a lot.

    Andy
     

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