Reduce vibration and jello to get smooth video.

Posted by Erik Graham on March 4, 2015 at 7:32am

I thought I would start a thread on reducing vibration and jello for those of us that use the Iris+ to shoot video.

Personally, I've found the Iris+ to be very stable since the first day.  I rarely get jello, and any vibration I get is easily removed with Final Cut X.  For the most part, if winds aren't too strong, I do not get vibration.

There is plenty of information on the world-wide-inter-webs about reducing vibration in quads, but not everything is relevant to an Iris+.  If I get enough feedback and advice here, I will put together a summary.  Again, the idea is to keep suggestions specific to the Iris+.

Some quick notes of my own to get things rolling:

Definitions:

  • Vibration is what one would expect.  Tiny little shaky movements in video footage.

  • Jello is a sort of a wavy effect that makes almost looks like you are viewing your video through a fun-house mirror. I guess its called "jello" because it looks like jello wiggling.

    Note: Vibration can be fixed in post using Final Cut X or other video editing software.  Jello can not be fixed in post.

Gimbals are a must:
A gimbal is a must for shooting smooth video.  Currently your choices are:

  • Tarot 2D.  
    Sold specifically for the Iris+ on 3DRs website.
    Its very good, but its 2 axis only and when doing slow vertical shoots, or even when just hovering in place, your video may exhibit small twitches back and forth (yaw twitches).

  • DYS 3 Axis.
    This is what I use.  It is a pain to set up and configure (though I bought mine pre-configured and programed from xproheli.com).  Based on my research it is the best option out there.

  • Feiyu-tech G3.  Some people swear by these, but I was told that they can be twitchy and so I went with the DYS.

    Note:  All 3 of these gimbals are marketed for the GoPro Hero 3, but I've used both the Tarot 2D and the DYS with a GoPro Hero 4 Black with no noticeable difference.

Common tips to reduce vibration:

  • Balance your props.
     I assume that the Iris+ props provided by 3DR are balanced right out of the box, but this seems to be the number one recommendation for reducing vibration in quads in general.  Personally I don't have the equipment to test my props for balance so I've never done it.

  • Level motors.
    On another quad I used to fly, this was important.  Make sure motors are installed correctly and level and balanced relative to one another. If you imagine your Iris+ is sitting on a level surface, and that a sheet of glass is resting on top of all 4 motors, then that sheet of glass should be completely level.  (I know what I'm trying to say, but does that make sense?).

  • Use the right compression dampeners on your gimbal. 
    I was advised NOT to use the grey dampeners that came with the DYS 3 axis.  The black Tarot dampeners (that you get with a Tarot 2D) are better.  I can confirm that in cold weather, the black Tarot dampeners are indeed better.  I have not tested in warm weather yet, but eventually I will.  I wonder how much difference atmospheric temperature makes.

  • Calibrate your ESCs.
    Its easy to do and it can make a big difference.  http://youtu.be/6kfVusza17I

  • Compass calibration.
    This is not so much about directly reducing vibration as it is about improving flight performance.  If your compass is not perfectly calibrated you might find yourself fighting the Iris+ as you try to fly it.  This can result in the occasional jerk or snap in your video, and just generally makes it harder to keep the subject in frame.    http://youtu.be/oD9Z9IR2TNU

  • IMU Calibration.
    I've never done it on an Iris+ and don't know how.  To be honest I don't even know what IMU stands for, though I've done it on other quads with great success (in terms of reducing vibration).

  • Don't fly in Loiter to much.
    If you can avoid it, try not to fly in Loiter too much.  I fly in Loiter a lot because I need to, but the Iris+ is constantly making little adjustments to keep itself in place, and that can result in shaky footage if you are not careful - especially on windy days (when I need Loiter most)


    Thats it for me.  There is a lot more to go over, but I have to run to work.  As I said above,  if I get enough feedback, I will put together a summary for other new users like myself.  Just keeps things specific to the Iris or Iris+ if you can. 

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Replies

    • Erik Graham > Michael March 4, 2015 at 1:27pm
      The distinction to me is as follows:
      Rolling shutter = Cause
      Jello = Effect.

      Other effects of rolling shutter include Skew and Smear. Actually the first link you provided adds Partial Exposure to that list. When most video editors hear rolling shutter, they immediately think "Skew". Indeed the rolling shutter adjustment built into Final Cut is really only a fix for Skew.
  • Erik Graham March 4, 2015 at 8:30am
    @ Larry:
    I would not mess with your gimbal motors until you've tried some other things first. The Tarot 2D is supposed to be pre-calibrated in the factory. Mine certainly was.

    I'm no expert, but I would try calibrating your ESCs first. It's super easy (see link in my post above). Also, I'm selfishly curious to see if that has an effect on jello, so you are the perfect test subject ;-)

    Also, if you don't mind, could you test to see if the jello your getting is any better or worse in different flight modes. Specifically, does it make a difference if you are in Loiter vs Alt Hold. And please note how windy it is. We don't need an exact wind measurement - just a ball park, ie "calm" , "windy" , "really windy" etc etc.
    • Larry Farquhar > Erik Graham March 4, 2015 at 4:58pm

      I'm game. I'll do some baseline tests in different flight modes. Then, if needed, progressively make changes from there.

      This is my 2nd Iris+, but my first gimbal. This was only the 2nd flight with the new copter and the first flight with the gimbal attached. Wind was moderate on this flight and the jello effect was terrible. Now that I know I might have a problem, I'll test better,

    • Erik Graham > Larry Farquhar March 4, 2015 at 5:09pm
      Well per Michael Burmeister's post below, it sounds like I am wrong about the Tarot 2D coming pre-tuned. But it would still be helpful if you did the testing one change at a time as you described.
  • Ruedi Schubarth March 4, 2015 at 8:26am

    Hi Erik-

    Thanks for the run-down! This is a great summary.

    What is your ~average flight time with the IRIS+ hanging the DYS 3-axis?  I'm currently getting 15 minutes with a 550-size hexacopter/DYS smart3, and I recently ordered an IRIS+, curious how it will do with the same gimbal.

    • Erik Graham > Ruedi Schubarth March 4, 2015 at 8:44am
      My record is 11 minutes and something like 45 seconds. That was in pretty cold weather (0 to 5 degrees Fahrenheit). I expect to get more flight time this spring and summer.
  • Larry Farquhar March 4, 2015 at 8:16am

    Excellent timing!

    I just installed my Tarot 2D Gimbal with Hero3+ Silver on the Iris+ and did some initial test video flights. My jello was terrible! It looked like there was an earthquake going on. I'll be calibrating the gimbal motors and will see if this helps. ANY good advice specific to the Iris+ would be GREATLY appreciated!

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