roll shake

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

  1. JY Air

    JY Air New Member

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    What is the roll / tilt pulley gear ratio?
    f360-0866 servo and the radian is in use.

    5d mark 3 using roll shake a little of but I can not do it and I want to solve.

    radian Roll gain 115-150
    radian and servo, ar8000 - Voltage 6V

    Feel the lack of speed ingeo:
    How about lowering the gear ratio a little worried.


    http://youtu.be/tMxZb02ZAJw
     
  2. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Were you able to balance the camera in the roll axis -- that is, remove the roll belt, and position the camera in roll at any angle and no have it either roll over to one side or the other (in which case the camera's center of gravity is above the roll axis), or swing like a pendulum back to the center (in which case the camera's center of gravity is below the roll axis)?

    The center of gravity of the 5D Mark III is quite high, so to get it to balance I had to purchase the Epic tilt bars so that I could lower the front transverse boom and camera plate by about 8mm. Then I had to use longer bolts for the camera plate so that I could use washers to raise the camera plate up 4mm. You also need to make sure that the side booms are tilted up at the front, to get the camera center of gravity right on the roll axis.

    I described exactly what I did to balance the 5D Mark II in this thread.

    Other things to check:

    When you're on the ground, if you tap the gimbal to make it roll, does it vibrate at all? I'm just wondering how close to oscillating it might be? (In which case the gain is just slightly too high.)​

    Also, can you check the tightness of the roll belt -- if it gets slack you can see wobble like this. If you press with your finger on the mid-point between the small and large pulley, you should see only about 2mm of deflection.​

    As you know, the 5D Mk III is a fairly heavy camera, so if there is any mechanical slack in the gimbal, the weight of the camera will make it worse.

    Hope this helps.
    Andy.
     
  3. JY Air

    JY Air New Member

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    Answer a lot of late.
    Above, as we did many tests.
    Exactly align the center of gravity,
    It was good timing belt tension.

    I do not, but it does not solve any

    radian change reporting,
    Reporting, and replace it with a fast gear ratio
    radian to 5v
    FF servo 6v
    We did also voltage regulation.

    Nothing more try now.
     
  4. Josh Lambeth

    Josh Lambeth Well-Known Member

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    One thing I noticed and will be confirming tomorrow is if there is ANY vibrations coming through to the gimbal from the frame it will cause you all sorts of headaches!!! Mine looked terrible and after screwing around with balancing, rebalancing, and balancing again all the props and motors... i realized that the gyro and ACC settings of the FC were causing the issues. I have only done one flight after adjusting the ACC setting on the copter and it's a night and day difference! I will post footage tonight for you to see the difference.

    Check and see if you are getting smooth footage with the RADIAN system OFF! If your footage is bouncy there then you will never get it stable with the RADIAN on. If your footage looks smooth with the system off then it's an issue with the RADIAN settings.

    Josh
     
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  5. Matt Kearney

    Matt Kearney Member

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    Hi Josh,

    If you don't mind sharing, what are you running your Gyro and Acc settings at??

    Thanks

    Matt
     
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  6. Josh Lambeth

    Josh Lambeth Well-Known Member

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    Currently
    Gyro P: 85
    Gyro I: 110
    Gyro D:10
    ACC/Gyro Comp: 40
    Gyro Stability: 6

    Ill post the new final settings tomorrow after some testing.

    Josh
     
  7. Matt Kearney

    Matt Kearney Member

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    Thanks for the reply Josh.

    I guess i should have also asked which frame etc your running?
     
  8. Josh Lambeth

    Josh Lambeth Well-Known Member

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    CS8 heavylift. Look at my build thread in the CS8 section.
     
  9. JY Air

    JY Air New Member

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    Thank you for your answers.
    I am currently 'WooKong-M' is in use.

    Changes in the movement for the MK setting above figures, so I'll know.
    And, let's test as the tip of your.
     
  10. MIke Magee

    MIke Magee Active Member

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    Josh, I'm VERY interested in your results. I'm Hoping that the top end is trying to compensate for increasing/oscillating vibration and wagging the gimbal around. I'm having a very similar issue. Always had it all along I guess, I just never noticed it because I used the 5D for stills, the 760V for most video. The 760 shows it subtly, but the lens absorbed most of it.

    I have a terrible lateral vibration on the gimbal, and have been working for weeks to resolve it. I'd like ANY AND ALL opinions
    Overview:
    • Low time CS8/360 (4 month old)
    • Gimbal reasonably well balanced, and rebalanced for the 5DMKII w/24IS.
    • All motors OK, just replaced 2 suspect ones w/ brand new ones.
    • NEW set of blades, very well balanced with my du-bro
    • Wire-tie on the vibration dampeners hack installed.
    • Every fastener tightened until my Hitachi got blisters
    • 200MM booms for the camera plate.
    • Radians - Roll-155, Pan-70, Tilt-130 - looks ~OK on the bench and suspended.
    I notice a horizontal movement, left to right that appears stabilization or not, and need to know what I can try to eliminate it. MAYBE some will say t go back and re-balance, and I will, but I'm open to suggestions.

    Here is an interesting side by side that shows the 5D on the gimbal from a gopro on a boom. We see what the gopro sees as well as the 5D shot. Each view is labeled. It's a short annotated clip. I shot 720 6p from the old gopro and at the end I slowed down a section of the analysis to show the issue. Any and all advice appreciated.

     
  11. Josh Lambeth

    Josh Lambeth Well-Known Member

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    Well guys.... That didn't fix it...


    Just spent 2 hours of taking off, landing, making adjustments, taking off, landing, making adjustments, taking... you get the point...

    AND I still have the vibrations.... Tabb suggested it could be the PWM converter causing the issues by pulsing the motors. All the motors sound normal and I don't hear any odd pulsing noises. I am really at a loss right now.... I will try and get some slow motion footage of the gimbal today.

    Josh
     
  12. Pavlos Antoniou

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    THe gimbal is balanced by its own?? have you hand it to balance it?!
     
  13. Josh Lambeth

    Josh Lambeth Well-Known Member

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    The gimbal is balanced by hand and is pretty much perfect.

    Josh
     
  14. Tim Joy

    Tim Joy Active Member

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    Have you checked the pan bearings? It looks like it's loose at that point.
    It might be worth it to do a closer shot with the gopro that shows from the pan bearings up to the vibration isolators so you can see where it's coming from.
    I've had a prop be perfectly balanced but still cause bad vibrations. Maybe you have a motor or a prop that happens to setup a resonance in the gimbal. Ever had a tip-over or hit a prop on something? Motor might be putting out vibes.
    There's a thread about checking vibes with an iphone app. Worth a look.
     
  15. Pavlos Antoniou

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    Might the problem be to the Vibration plates?? do you think that if we put 2 vibration plates will be better???

    this one http://www.quadrocopter.com/CineStar-8-Gimbal-Vibration-Plate_p_460.html

    Also can you record the same video but this time put the gopro near the center in order to see the dampers better..!

    Another good mod is to put a silicone tube (inner 6mm and outer 10mm diameter) or a foam tube to the spacers of the dampeners in order not to have play..! SOmeone that can find this special tubes to try it??
     
  16. Sedric "Zellevision" Sari

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    What FW do you guys run on the radians? I have 1.03 atm and have problems on the roll too. B4 with the 1.02 it was perfect!
     
  17. MIke Magee

    MIke Magee Active Member

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    Tim, I was hopeful, but a vigorous hand check of the pan bearings showed that they were perfect.

    I will look for that iphone app thread and check it out thanks. !
    -m
     
  18. MIke Magee

    MIke Magee Active Member

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    I do have an update on this lateral vibration issue that I would request opinions on. It appears that I may be able to eliminate it - at least on my platform.

    This weekend, some merciful deity tossed me a bone and subliminally suggested that I use a rubber grommet (similar to http://www.vibrationmounts.com/RFQ/VMV12R30M.htm) in the frame hole that the 3mm screws fasten the gimbal to the vibration isolators. This allows vertical movement as intended, but substantially eliminates lateral movements. (maybe this is similar to what Pavlos suggest last night?)

    Of course on Sunday at noon, I could not get my hands on any. The same patient deity reminded me that I had a short length of rubber tubing that had an ID of EXACTLY the hex female post, and an OD that was EXACTLY (well, minus about .025 MM) of the hole in the frame. I arbitrarily cut some 7-8mm lengths and slid them over the female hex post and reattached the gimbal.

    It seemed to work, except that it's length interfered with the natural vertical movement and prevented compression. This created sharp vertical vibrations

    So I'm going to order some up and try again. This should re-enable the vertical compression/expansion again.

    However, it seems that the question of WHY there is such sharp vibration from the top end. Could someone explain how I might interpret the fields in the GPX file so that I might be able to find out WHAT the machine was thinking, so that I might be able to determine HOW to prevent it from vibrating so?

    I've printed out the MikroCopter.de Wiki sheet of the field usage, and will review them with the gpxtool, but this is still just data, not yet information. Could someone lend pointers on what might be important to think about and why?
     
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  19. Pavlos Antoniou

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    Its exactly what i suggest.. :) :)
     
  20. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Mike: Try MK_GPXTOOL (the wiki page is here and there's a link to download it just below the top screen capture images at the top of that page) to look at the GPX file data -- it's plain text but encoded as a Markup Language which is not really fit for human consumption -- just for programmers like what I is. <evil grin>

    That said, I'm a bit doubtful that the data in the GPX file will do you an awful lot of good. I'm not sure it will have the sensitivity to tell you what you need to know when it comes to vibrations.

    I was originally thinking that the ring around the hex standoff would just need to be long enough to cover the typical travel of the standoff through the hole in the carbon fiber. Did you try just that? Or did you have to cut off the tubing to regain vertical damping?

    Andy.
     

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