Do you use all the rubber ring dampeners with Radians?

Discussion in 'Radian' started by Chris Newman, Oct 10, 2012.

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Do you use all the ring dampers with the radian?

  1. Yes- Stiff as possible

    88.2%
  2. No- Loosey goosey is how I choosey

    11.8%
  1. Shaun Stanton

    Shaun Stanton Active Member

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    I don't have too much of an issue with the roll axis most of our problem seemed to be with our panning movement. I will try Joes method and update my firmware and give it a shot. I flew it down Rio Grande today, we had it too stiff this time. Our panning jitter was fixed but we had the engine vibration it the footage. Also I must note that for testing I am using a cheap Canon vixia handy cam that I bought on craigslist, so my camera is significantly lighter than the 5D or other DSLR types. I don't know if this is factor.
     
  2. Josh Lambeth

    Josh Lambeth Well-Known Member

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  3. Colin Snow

    Colin Snow Active Member

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    I was getting some "bounce" as well. I tried this with two sets of o-rings. It's window screen spline. It fits in there easily and it's hollow so it can "squish". As best I can tell the gimbal rests the orings and only engages the spline when there is travel. So far, so good.

    DSC01267b-web.jpg DSC01272b-web.jpg
     
  4. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    That's clever, Colin. Where do you go to get that stuff?

    Andy.
     
  5. Colin Snow

    Colin Snow Active Member

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    Any hardware store or Home Depot / Lowes should have it. Look in window screen repair for "splinning". It's the rubber that goes in the groove of the frame and holds the screen to the frame.

    Cheers, Colin
     
  6. Pavlos Antoniou

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    guys i see my gimbal that is 3060 gr all included and when take the cs 8 on hand the dampers use 25% of the travel that they can do.. they seem to be very tight..! How are yours when you take the cs on your hand??

    Tommorow i will do the Maiden :)
     
  7. Shaun Stanton

    Shaun Stanton Active Member

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    I am going to try joes method and see if that works. Next I am thinking about wrapping the standoffs where the gimbal attaches with some soft packing foam to add some dampening, I will post my results.
     
  8. Jon Fredericks

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    So in trouble-shooting the un-wanted wobble that most folks are experiencing, we're run through quite a number of test scenarios. Our latest mod was removing the o-rings and inner struts completely and replacing them by sandwiching layers of soft foam and then compressing them by tighening down the 'star' screws. This made for a significantly more rigid suspension system that still isolated all motor/prop vibrations (no camera jello). Our results were essentially the same as the stock suspension system. We still have unacceptable roll wobble at all gain settings. I think we've come to the conclusion (at least for us) that the issue lies with the gimbal itself - no matter how tight we get the suspension, there is still a substantial amount of movement in the gimbal itself. There are so many levers (Fe = Fl dl / de ) in the system and with the weight of the camera it generates a great amount of pendular movement. That is where we believe that the majority of our wobble is coming from and may be the same for others. Thoughts anyone? Any success stories thus far with a B.O.S.S.-less camera?
     
  9. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Jon: Do you think the issue is that vertically, the vibrations are isolated, but laterally, the isolator "bottoms out" against the lower hub plate and that is why the issue is more noticeable in roll?

    Also, I wonder, for those use the CX760/730 (with BOSS) whether BOSS actually removes roll as well as it does pan and tilt?

    Andy.
     
  10. Jon Fredericks

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    Hi Andy - I'm sure the CX760 will take care of the wobble that we are experiencing, but unfortunately we can't be limited to just one camera.

    We're not seeing any bottoming out on the lower hub plate. It appears to be the pendular movement of the gimbal that the radian is fighting - not the actual roll axis, but the entire gimbal as a pendular lever, with the fulcrum being the attachment point to the copter. Even a soft tap of the finger will create a 'flexy' pendular motion of the entire gimbal without the roll axis moving. We're trying another mod right now by adding an additional layer of foam for even more stiffness, just so we can comepletely rule out the suspension as the culprit. I'll try to post some pics of our most current mods.
     
  11. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    I hear ya. I've certainly seen the "clunk" in the video when the vibration isolations move laterally and hit the hub plate -- mind you, that's taught me I need to fly more gently....

    But you're right -- I think any mass suspended with a flexible fulcrum will act as a pendulum unless it's actively damped. (It's a long time since I studied the physics of masses in motion....my brain hurts...)

    The natural frequency of the gimbal seems to be around 2-4 Hz. Is that what you're seeing?

    I had inferred (perhaps erroneously) that the Radian sensors and servo would null out that -- effectively providing the damping. I wonder therefore whether there is an "unhappy valley" where the gain is low enough to avoid oscillation, but not high enough to allow damping.

    Andy.
     
    caju likes this.
  12. Jon Fredericks

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    Here's some pics of our current mod.

    Kinda hard to see, but that's a piece of bungee cord rubber above the lower ring, and a couple layers of pipe insulation below the lower ring. It is very stiff. If something along these lines works, we'll make a permanent installation with silicone blocks.


    [​IMG]
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  13. Kari Ylitalo

    Kari Ylitalo Member

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    Hello,

    I did this kind of mod and i get better results. But, i have to agree with Jon F, no matter how stiff vib nampening is, there's still some amount of flex and softness in gimbal itself which allows bouncing and feedback loop in higher gains.

    [​IMG]
    [​IMG]
     

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