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 > Nathan Milsaps March 25, 2015 at 11:25am
      I have not tuned it to account for the weight of the filter, but I probably should. Having said that, I can't detect any difference in vibrations with or without the filters. They are very light weight after all.
  • Larry Farquhar March 12, 2015 at 11:02am

    I discovered my jitter was coming directly from the Tarot. Not always, but once and awhile, it would be jittering (shaking) as soon as powered up. Touching it "might" stop the jitters. You could definitely feel and see it.

    I adjusted the motor a little and it appears the jitter is now gone. The next test flight will reveal if this resolved my issue.

    Bottom line - it was set at the factory, but the settings needed a slight adjustment. 

  • Charles K Taylor March 9, 2015 at 6:16pm

    If you are going to be flying a GoPro the CM3000pro is an amazing gimbal. 32bit Alexmos with dual IMU and slip ring on the yaw axis all ready to go out of the box. I've been loving mine. 

    http://www.hobby-wing.com/arris-cm3000pro-gopro-hero3-3-axis-brushl...

    Just like other people have mentioned jello tends to be worse in bright light because the shutter speed is faster to compensate for the light. To help slow it down and smooth out the video I recommend running a ND filter or dual polarizer. The nice thing about a dual polarizer setup is the amount of light it cuts out is adjustable. In either solution balancing the gimbal after installing is very important. Besides helping with jello they can also help add a little motion blur to movements making the video look more natural. It also results in blurred props instead of the weird ass shapes caused by the rolling shutter of the GoPro so it is actually tolerable to see them in the video.

    • Erik Graham > Charles K Taylor March 9, 2015 at 6:54pm

      Thank you.  I'll add it to the list.  What I like about the CM300pro is that it looks like it will accommodate filters nicely.  The Tarot 2D, DYS and FT G3 all secure the camera with a ring around the lens.  To use a filter (like the ones from Blurfix I linked to above) you have to use a rubber band - and that never feels quite right to me.

      I would note that I see a bit of vibration in the GoPro 4 video on the page you linked to (http://youtu.be/d6KGNcCR2Iw).  Its not very noticeable until you go full screen.  Even then, its very tiny and could be fixed in post with Final Cut or Adobe.

      And thanks for the comments on rolling shutter. I think I lift your succinct description and use it in my final summary.

  • Erik Graham March 8, 2015 at 11:33pm
    Based on a tip from a professional UAV operator, it appears that the IMU (Inertial Measurement Unit) calibration should be pushed up toward the top of the list. These guys re-calibrate their IMUs every 12 flight hours or 2 days - whichever comes first. Of course they are pros, but at the very least we should be calibrating our IMUs "fairly regularly."

    Personally I'm just going to go ahead and adopt their 12 hours/2 day policy.

    For convenience sake, here are the two 'how-to" links previously posted in this thread:
    - http://youtu.be/8TWjZLlATIE
    - http://copter.ardupilot.com/wiki/initial-setup/configuring-hardware...
  • Todd Harper March 8, 2015 at 7:59pm

    Great subject Erik, its always a topic of discussion no matter which gimbal we use.

    All the points listed are valid and should be address thoroughly when trying get the smoothest footage possible.

    One thing to add is the use of a proper filter when flying. It can, in most instances, make or break what you are capturing. While it does not eliminate the jello effect it does help with "smoothing out" the footage.

    One thing regarding the gimbal balls is that the air temperature will effect how they react to movement. It may be beneficial when posting our results to also include the air temp while in flight. 

    ToddH.

  • Richard Kennedy March 8, 2015 at 3:49pm

    FYI jello shows up more on bright sunny days. So if your testing it's best to do so on a sunny day.

  • Erik Graham March 8, 2015 at 12:22pm
    Any one feel like providing a link or doing a write up on flight modes and how they effect vibration?

    My experience is basically limited to what I said in the original post - loiter can lead to vibration or jerkiness as Iris+ works against wind to stay in place. If I can manage it, I try to fly in alt hold. Results are smoother that way. Anyone agree? (Unfortunately in the wind I have to use loiter so that I can focus on framing the shots and not keeping the Iris+ in position).
    • SkyRover > Erik Graham March 8, 2015 at 1:25pm

      Should be easy enough to do. just do a bit of flight in each mode and then check the vibrations of each on the log file. Won't be directly the vibrations the gopros seeing, but will show what is changing and how each mode compares.

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