I'm sure everyone who is into aerial videgography with the wonderful GoPros have struggled with getting Jello Free (rolling shutter) video footage from multicopters. I have tried them all. Using ND filters to lower the shutter speed of the GoPro (worked somewhat but ruined image quality), shot in 720p @60fps but would have preferred shooting in full HD. Tried all sorts of foam and vibration absorption materials, ear plugs, rubber foam mounts, hours balancing my propellers and laser mirror and phone seismograph app to iron out any vibrations to no avail. Despite the GoPro Hero 3 B.E. shooting at full HD @ 60fps, I still get some rolling shutter.
Recently I saw this video by Matt Hall who's Tcopter design GoPro video footage is devoid of any rolling shutter effect. I followed the hardware specs recommendations, using 1400kv SunnySky motors and Simon K'd F30a ESCs. I took his frame design and modified it a little and used a cradled motor yaw mechanism inspired by this design. And this is the result, below is a conceptual design I created in Blender 3D to test out the yaw mechanism and also to get the dimensions.
Here is the Actual Craft built last Friday.
And here's the video. I believe the wooden frame, small high speed manually balanced GWS style HK propellers (8x4) combined with the high KV rating of the motors (1400) helped to generate very high vibration frequencies that is not noticeable on the GoPro Hero 3 B.E. CMOS sensor. All my previous multicopters motors are rated at 750kv and below spinning 11 inch props. Balancing them, especially the 11x47 Gemfans are a nightmare, so it was very difficult for me to get perfectly balanced setup and that resulted in rolling shutter. So the key I discovered is, use high KV motors rated 1K and above and also high speed smaller props. There is a catch however, flight times are reduced as this setup is not as efficient as the lower KV motors, but I think this is a small trade off for the footage I'm able to get. Right now on a 2200mah 4S Nanotech LiPo, I get around 7minutes flight time. All up weight with Camera and Battery is 1.3kg or nearly 3 pounds.
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My latest flight. Brought down the stick scaling of the KK2 board for a smoother flight.
@Kal,
Heh heh, I have to give credit where credit's due. Matt Hall (Hallstudio) is the one who discovered this and though I have read before that higher KV motors and faster props does improve the video footage I was not completely convinced, until I say Matt's Tcopter videos.
Yes you are right about more options out there and I have pretty much tried them all, but in terms of simplicity and effectiveness, you can't get better results than this :-). I mean my GoPro Hero 3 does not even have any foam mount beneath it when I shot the Park video.
@Oliver, this footage was shot at 60fps and at Full HD 1080, so the waviness is subtle but there. I guess the twitchiness is due to the strong winds that was buffeting the craft. For this Tricopter I was flying it using the KK2 flight controller and it is based on RCexplorer's Tricopter setup but using carbon fiber arms. There is one method of isolating the camera from vibrations that I have not tried yet which is using wire suspension. I have seen footage which seems to show very good results.
Wow, I'm not sure what you're calling Jello there - I see an awful lot of quick short-roll twitchiness which is going to induce, I think, some motion blurring just like a fast pan would, but when I've had jello trouble it has always manifested in wavy distortion especially noticeable on verticals. Your lamposts, for example are nice and straight (except at edges from lens distortion of course). With the Jello I used to get they would look like a crazy"S". If I was getting results like you are I would be looking for why the camera is rolling so much. It looks from the bit of prop visible at the left edge like you have no stabilization for the camera itself, it's just following the airframe. I don't know your aircraft of course so have no idea if it can be mellowed via the stabilize PIDS but that's where I would start. I now wonder if your better result with the less efficient setup you talk about is simply due to the aircraft being correspondingly less twitchy rather than vibrating less... just thinking out loud and I'm no expert on any of this. You might also try and see what result you get with the aircraft nailed to the ground - vibration Jello should still be there, while flight movement is of course absent. (Just be real certain that whatever you use to hold it down is 100% secure and stay well clear, avoid blowing debris around, prevent the neighbor's cat from attacking, etc.... ).
@Oliver, yes it is possible to get jello free video if you satisfy a lot of the conditions like balanced props and motors. That is one area I struggled with. The Gemfans props I previously used are very difficult to get balanced and although I managed to eliminate some jello vision it never completely goes away. I thought that once I got the 60fps FullHD GoPro Hero 3 Black Edition, the problem will go away, it did not - as seen here
I have shot on the 1st Gen GoPro at 720p @60fps and that seem to work very well, but I like the clarity of full HD video that is why this setup is the best for me.
You wrote. "I'm sure everyone who is into aerial videgography with the wonderful GoPros have struggled with getting Jello Free (rolling shutter) video footage from multicopters." Well, no, I've had no Jello at all with either my Black H3 (at any rez/rate) or with my H2, flying them on a DJI Hex and the H2 before that on a Gaui.
In both instances the props were high-end (Graupners, currently) and balanced. (And I do know all about the frustrations of Jello, having fought and fought with it on trad helis up to 600 size.) Also this is without any elaborate dampening etc. of the camera mount. On the DJI I have two pads of the rigid-type Velcro between the airframe bottom-plate and the top-plate of the combination landing-gear/camera mount. Then the camera mount itself is hanging from the landing gear frame rods via four simple rubber grommets. Finally, in the current setup I am using a GoPro mounting pad kust before the camera, so I guess the adhesive pad on that also maybe absorbs some vibes (but this wasn't present before and I had no Jello then).
Also, I am flying the GoPros in their housings, not bare. Maybe the mass helps.
If you have good stiff balanced props and motors that are also not much out of balance, maybe it would help to look at the overall rigidity of your airframe and especially of course the arms. Just thinking out loud here, but I think that any multicopter airframe is going to be potentially subject to some harmonic sort of effects as the different motors run up and down through different speeds. It seems to me that even with everything well balanced, if the overall structure isn't sufficiently rigid it's going to vibrate and there comes the Jello..
@Mark Colwell,
The cable wraps will probably fail or wiggle out after many hours of flying, but so far I haven't experienced it on my other Tricopters and they are based on Rcexplorer's (David Windestål) design. Besides they are designed to break in a crash and I have crashed a few times on my other Tricopters and the cable ties breaking saved the motors. For peace of mind, I used heavy duty double-sided tape on the base of the motor mounts.
@ Emery c. Chandler
I was flying at a local park in Singapore. The "river" you see is actually created out from a canal and before that, it was a real river. The cover lens is smudged a bit with my finger print, must remind myself to clean the camera case lens before flying.
@ Jack Crossfire
Exactly! I am so surprised by the Tcopter layout performance and the benefits it offers. I know it can certainly fly without the landing gear, but it looks so cool with it! It does help a bit with orientation and it felt somewhat like flying a helicopter.
About time the T frame started catching on. Funny how people always install landing gear, even when it can clearly take off without it, just because you're supposed to have landing gear.
where were you flying at?
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