Intermittent high frequency vibration problems with our Movi MR

Discussion in 'MōVI MR' started by Sam Leggett, Feb 25, 2014.

  1. Sam Leggett

    Sam Leggett Member

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    TAAAABB IT'S THE WHEELS! You were quite right! After seeing Adam's slo-mo its clear that the intermittent shake of that back leg must have been causing our wobble too.

    We did 3 mins with wheels and 3 mins without and there was plenty of difference! Oh the relief! Filming nothing in particular with that quality was almost better than filming the pier at sunset!

    I am going to fashion something to utilise both bolt holes on the bottom of the movi legs - solid but with hard foam underneath for some "give" when landing.
     
  2. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Sam:
    So the mass of the wheels (or was it the aerofoil drag?) was enough to induce a "tuning fork" oscillation?

    Andy.
     
  3. Adam Etheridge

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    Hi Sam - that's fantastic news! Great its working for you, and thanks for sharing and your persistence!...

    We'll try removing the wheels too and getting to the bottom of our Pan balance issue. Hope that solves it also.

    Would be really interested to see your feet solution when you get there - the little extenders seem so 'spindly' for the weight...
     
  4. Chris Fox

    Chris Fox Active Member

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    I'm running the little extenders and they work fine as long as I land on a hard surface .... concrete, asphalt etc ... on grass I need to put down a landing pad, because the ground pressure from the provided legs is enough to make them act like spikes. I use a simple piece of rubber about 1m square ... it is almost heavy enough to stay place when coming into land ... a bit bigger would work well, or a wooden board.

    Cheers
     
  5. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    G'day Chris:

    I've been experimenting with some "pool noodles" (no idea what they'd be called in Oz -- Pommie Floaters?) on the ends of the "elf feet."
    However, I think I might move to some 5mm wet suit material folded around the ends of the elf feet. Elf wet-suit socks? It may take a couple of layers to fatten the feet up to the point where they'll soften the impact of what I loosely refer to as "a landing." :rolleyes: The way I fly it's more "controlled flight into terrain." ;)

    Andy.
     
  6. Chris Fox

    Chris Fox Active Member

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    We can understand some of the lingo, and "pool noodles" does translate across the Pacific Ocean ;)
     
  7. Sam Leggett

    Sam Leggett Member

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    Hi all,

    Sorry for my late reply, girlfriend back from Mali (she works 8 weeks away at a time).

    Andy, I think the wobble might have been caused by a combination for the mass and drag, and also that the bolt through the middle - even when tight against the wheel is still not as firm as when the 2 sides of the leg are butted up against each other, allowing a little flex and worsening the wobble.

    What are the "elf feet"? We are fortunate to have all the tools of the D and T department at the local secondary school to our disposal, so I and going to have a fiddle in the next few days.

    Hope you're on the way too Adam.

    Chris we do use carpet at the moment when flying in awkward spots, but I just like to keep the amount of paraphernalia to a minimum!

    Provided the Movi behaves our last hurdle is Waypoints... but that might be for another forum... there don't seem to be many on here doing it.
     
  8. Chris Fox

    Chris Fox Active Member

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    Waypoints work fine, have being using them for survey type work with MK, but my heavy lift copter doesn't support waypoints, it just does one thing, which is fly smoothly, and so far that is with a flight controller that doesn't support waypoints.

    There are a couple of gotchas to check with MK waypoints, but otherwise it works well, DJI waypoints ...NFI sorry
     
  9. Sam Leggett

    Sam Leggett Member

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    Ah its all MK on this site! The DJI wookong instructions only show how to get up the hardware - really want a step by step mission plan before I send all that £££ into the sky! But that's another story...
     
  10. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    She's been gone for two months and you're taking time to post on a forum? <evil grin>

    OK. Thanks for the information.

    Technically: Landing gear extenders. The curved extensions for the landing gear. I would offer to insert a URL but I cannot find them on the quadrocopter web site....weird.

    Waypoints? Brave soul.....Do your friends at the CAA let you use Waypoints?

    Cheers
    Andy.
     
  11. Sam Leggett

    Sam Leggett Member

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    Ha! Andy the business is the only way to keep her in the things she likes :) We are house hunting and the sooner this machine starts paying for itself the better!

    I will keep an eye out for elf feet! And might try making what I am picturing in my mind!

    I think waypoints will be brilliant if we get on property make over shows... as you can take the exact same shot 6 months on to show before and afters and things like that. Also for dull but precise grid flying if we get survey work. Provided we do a Waypoints flight assessment the CAA is more than happy to let us fly on waypoints... provided we stick to 500m and 400feet. There is also an option to do a EVLOS flight test (extended visual line of sight) which means you have extra people along the aircrafts flight path spotting for the pilot. I think you can legally fly to 2km or so on that here. We aren't going for that though!
     
  12. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    I hear ya. Your priorities are, IMHO, correct! :)

    Check out the image here: https://www.quadrocopter.com/MoVI-MR-Upgrade-Kit_p_1112.html
    Magnify the contents of the small plastic bag at the top righthand corner.....them's be elf feet. :)

    https://www.quadrocopter.com/MoVI-MR-Upgrade-Kit_p_1112.html
    Let's hope the tragic disappearance of MH370 doesn't get waypoint flying a bad name!

    Andy.
     
  13. Sam Leggett

    Sam Leggett Member

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    Ah I see 'em, they appear to be just extensions =- still with no real give to them. We will have a bit of a fiddle over the weekend and see what we can come up with.

    Waypoint does give me the willys a bit... but the whole thing is all complex electronics... its just an extra leap of faith! At least we have the black box to see where it went wrong...!
     
  14. Adam Etheridge

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    Hi Guys

    Sorry for the long delay - we've been busy dodging rain and hail and all sorts of other fine British weather.

    We're made some progress, but still not quite there :/

    Taking those wheels off has DEFINITELY made a massive difference. No more crazy tuning fork oscillations - and it has allowed us to raise our stiffness settings to: Pan 100, Roll 52, Tilt 38.

    Would love to get you guys' opinion on the footage below (approx 1 min, 1080p), as we're really struggling to diagnose the problem???... there are 5 different shots / camera moves in the clip. The "Static Hover" is almost there. Weirdly the "Tracking Left" shot looks pretty good to me, whereas flying forward and right are both completely unusable.

    http://exchange.aspectfilmandvideo.co.uk//Judder-Tests.mp4

    Thanks in advance.

    Adam
     
  15. Adam Etheridge

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    PS: we also changed our pan tube for a longer piece of CF... we're now pretty perfectly balance in Pan
     
  16. Sam Leggett

    Sam Leggett Member

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    Hi Adam, Sorry to hear you are still having problems, couldn't get the link to work... refreshed a few times but no joy...
     
  17. Adam Etheridge

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  18. Sam Leggett

    Sam Leggett Member

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    Sorry Adam, no joy... might be this laptop but it just loads for ages and gets a blank page.
     
  19. Adam Etheridge

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  20. Sam Leggett

    Sam Leggett Member

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    Hi Adam, I got it working that time... but the issue is a bit mystifying! Climbing and descending obv have different motor rpms that can cause vibration one way and not the other but tracking left then tracking right is very strange. Your hover looks just a bit fidgety - like ours looked when we were having the problems with the wheels. I'm not too sure what to suggest. We went over everything with an allen key and it did feel noticeably firmer. Your pan is now a bit higher than ours and tilt lower, I don't know if playing with each axis in turn might help? You have already mentioned all the props being balanced and that was really my last thought. We went up and down at intervals of 10 until the picture was obviously sloppy at one extreme and vibrating at the other.
    That's all I can think of I'm afraid, perhaps some more experienced blokes will be able to suggest more.
     

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