roll shake

Discussion in 'Radian' started by JY Air, Oct 17, 2012.

  1. MIke Magee

    MIke Magee Active Member

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    I'm going to play with GPXTOOL. Looks good.
    What I need to do is synchronize a 2 camera shot with the data.

    AFA making the tube shorter - it may not be good, cause if it moves down and laterally, it may get caught under the plate returning up, considering that there are 8 at play at any moment. That's why I'm going to try a grommet approach. But I'll try shortening them tomorrow. Raining today.
    Thanks.
    -m
     
  2. Brad McGiveron

    Brad McGiveron Active Member

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    I am using similar rubber grommets which I shortened... but really the problem I found was the vibration plate is way too flexible with heavier cameras. It needs to be absolutely solid so that the dampers do their work. I have seen a few folks who put two vibration plates together but the shape of the plate itself is not limiting to how much flex there is in the non X directions. Something more square with two layers doesn't flex in random directions nearly as much.
    I added a square of thin 7"x7" 1/16 inch thick beach plywood to the vibration plate with epoxy. The pan shaft is solid and now the gimbal doesn't start bouncing or swinging because the vibration plate is solid as well. If you fly single rotors you'll understand the issues with swinging gimbals and big payloads.

    I was using a 5D3 and 16-35 here so its reasonably heavy. Some small jitters and some more Radian tweaking needed as its not perfect but with an IS lens like the 24 2.8 IS it would be pretty darn close for me. You can see me switch the pan slew on and off in a few spots as its jerks subtly.

    With a light camera like the GH2/3 or similar, you are going to introduce more vibes with something like this for sure. I found that out this weekend... but still I think more rigid mounting is the way, and specially with 8-10 lbs cameras.

     
  3. Pavlos Antoniou

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    can you show us your mod...!!
     
  4. Benjamin Rowland

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    Brad, I'd say you've got it really dialed in there.
     
  5. Brad McGiveron

    Brad McGiveron Active Member

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    Ill post pictures of the mod later tonight when I get home:)
     
  6. Pavlos Antoniou

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    also you have all the red dampeners ON??

    I am like you but some times i have some movements on th egibmal.. i think i have to raise the gains..!

    What are your gains?
     
  7. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Do you by chance have an image of the piece of plywood that you could post, Brad? It looks like an interesting approach...

    Thanks
    Andy
     
  8. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Hi Mike:
    One of the things that MK_GPXTOOL can do is sync a video with the data and an on screen display. You'd probably need to combine the two videos you have into one (split screen) and then sync the data to that.

    Keep us posted as to what you find with the grommet approach. (Every Brit reading this is likely to be thinking, "Cracking toast, Gromit!")

    Andy.
     
  9. Brad McGiveron

    Brad McGiveron Active Member

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    yes all the red ones.

    I think I was using 80 pan, 140 roll and 100 tilt.
    I could easily go higher on the roll and tilt without issues. Some of the twitches are coming from the multirotor itself which I think for this weight ( 5D3 and heavy lens plus 360 gimbal and extras ) on standard MK electronics is on the edge of ideal. Even though it will lift it fine, the way it fly's with something like the GH3 is totally different.

    Just in case you want to try.. I use some different MK gyro settings.

    Gyro D: 20-23
    acc/comp: 100+
    Stability: 8-10
     
  10. Pavlos Antoniou

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    and what the OVERALL weight of the machine??

    Also what props you have??
     
  11. Brad McGiveron

    Brad McGiveron Active Member

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    Andy: yes I will post the pictures in a few hours:)



    Pavlos: I think that day its was probably around 6000 grams. Give or take if I did my math correct hehe.

    Using the 14X 4.7 SF apc's for this setup. I tried many others which some I use on my heavy lift, but just find with medium weight cameras like the 5D, on this setup the apc's work great. Too bad there wasn't a SF 14 X 6 or something.
     
  12. Pavlos Antoniou

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    6kg?? No way.. :( :( 7 kg for sure. .:)

    Have you tried Xoar props?
     
  13. Brad McGiveron

    Brad McGiveron Active Member

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    ahh math hehe

    Yes I used them for awhile but didn't like them on the stock MK Cinestar. I use the 15x5's on my heavy lift and they work great.
     
  14. Pavlos Antoniou

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    OK thx.. i am w8ing for the mod photo :)
     
  15. Tabb Firchau

    Tabb Firchau Administrator
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    Hi Mike, after watching your video the oscillation looks to me like it is caused by the flight control on the copter being tuned too tightly and / or getting some kind of vibration to the FC that is causing the airframe to oscillate. When I watch your video I can hear the motors pulsing much more then I think they should. Can you share your tuning settings on the MK board?

    Thanks!

    Tabb
     
  16. Tabb Firchau

    Tabb Firchau Administrator
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    Brad, Nice work that video looks great!

    We have a thicker mounting plate in the works that will increase the stiffness considerably. The stiffness was not such a big deal before the Radian as even if things flexed a little bit it was OK. But now with the Radian the stiffness is paramount as the sensor placed on the camera mount can create a feedback oscillation that is exacerbated by any flexing in the camera mounting plate.

    -Tabb
     
  17. Brad McGiveron

    Brad McGiveron Active Member

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    Thanks Tabb

    Ya for sure... I noticed the swinging pretty quickly when I hooked up the Radians. Its the same thing that was a real pain with front mounts on single rotors. Good to hear there is a stiffer option coming. I think it should be less of an X shape though if you haven't already looked into this.


    Anyways for anybody who asked or cares I said I would post pics of my mod. Ideally it would be CF and two layers but I didn't want to waste a few sheets if it didn't work. I countersunk where the metal standoffs go into the wood so that the vibration rings would compress more when snugged up and as well I could use the same screws to attach it to the brackets. Basically the square being epoxied just makes the piece absolutely rigid. Its hard to see there but the rubber grommets stop the standoffs from moving around laterally.
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  18. Pavlos Antoniou

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    NIce you have done the two mods i post....
    And you think that both help right?
    Also where did you find these grommets?? Also with the way you put them these will prevent the laterall play but also you use them like dampeners..! THats good only for very heavy cams..!
     
  19. Brad McGiveron

    Brad McGiveron Active Member

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    Ya they both helped me for sure. As well I used it with a brand new GH3 on the weekend and there was some jello with an ultralight pancake lens. Heavier lenses there was none. For a 5D3 and FS-700 it worked like a charm.

    I used these http://www.amazon.ca/Gardner-Bender-GHG-1525-4-Inch-Grommets/dp/B000BO9DSA
     
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  20. Pavlos Antoniou

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    If you have problems remove two Orings and you will be great...!

    Also check my mod pls and tell me what you think..
     

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