(Don’t call it a… ) Drone adventures Pt.2

Pt.2 of my continuing adventures with aerial filming in which we discover that things are a LOT more complicated than they seem………
The video above is an example of what I have managed to achieve after weeks of tinkering and makes liberal use of warp stabiliser to smooth out continuing problems, read on to hear all about them…….

So if you’ve read Pt.1 of my post you’ll know that I had a few (ahem) problems trying to get useable video out of my quadcopter and the end of Pt.1 was a crash resulting from a QC issue.
I’m happy to report that after a few weeks of waiting my friend Pieter Franken from Safecast was able to fix the soldering issue inside the quad and after some tentative testing since then it has at least been flying……….

Am I any closer to getting useable footage from it? well…..Yes and No……..

 

The first thing I did was upgrade the props to some carbon fiber ones. They are much stiffer than the stock props and through my reading I discovered this could help with the jello problem IF the props were carefully balanced. This is by no means accepted by everyone in the RC community, but I have had significantly better results with the carbon props than the WLToys stock ones.
I also discovered that the carbon props are basically very fast spinning razor blades once the quad is flying and they do have a tendency to break! It is worth repeating again that safety is REALLY important when experimenting with these things.
The first problem I ran into was that the prop balancer I had bought was itself out of balance! (one more tick on the “you get what you pay for” list)

2014-08-23 13.59.57

Some filing, sanding of prop balancer nuts and swearing later and I was able to balance the props to my satisfaction.
What a difference!
With the balanced carbon props and stock gopro mount almost jello free! Not perfect but such a huge improvement on my previous efforts.

Time to move on to the gimbal.

Walkera G2-D plastic gimbal – with ND 4, zipties in isolation mounts and added weight to balance roll axis. (Not visible is the extra weight on the back of the GoPro to balance the weight of the ND filter)

This too, despite being sold as “balanced for a GoPro 3” needed some time and glue to get it to a balanced state with the motors off.
First tests were relatively stable in zero wind conditions when flying slowly but the jello was back.
More reading (lots more reading) and it seemed the rubber isolation mounts on the gimbal could be the problem. So zip ties were added and progressively tightened down or losened all the while testing and retesting in local parks.
The people over on the rcgroups v303 forum were very helpful and knowledgeable. Without them I would have given up and just made a nice stable video on a tripod with my C100 of the v303 being smashed to pieces and set fire to!

I was able to achieve pretty much jello free footage but was still getting some random shaking, particularly if there was any wind, when flying forwards at any kind of speed and when descending.
And lest I forget there was still the horizon roll problem when yawing (turning) the quad……..(more on that later)

I also added a 4 stop ND filter to the GoPro, a cheap ebay one – will I NEVER learn? and re balanced and tuned the gimbal to account for the extra weight whenever trying to film in bright sunlight as this is the one fix for any remaining jello that is pretty much universally agreed on across the forums.

For god sake don’t watch the whole 9 minutes of this video as it is REALLY boring, but it will at least give you some idea.
Also I have performed NO colour correction or black point corrections on this, it is completely raw from the GoPro.

Some of the shaking is due to using a 2 axis as opposed to 3 axis gimbal. Whilst in flight the flight controller makes tiny adjustments to the yaw of the quad to keep it pointing in the direction it is facing in. These tiny yaw adjustments show up greatly magnified in the footage as side to side shaking.
The rest (read most) of the shaking, I think, was still due to the isolation mounts on the gimbal.
After tightening down the zipties in the isolation mounts even further and adding prop guards to the quad (another suggestion from the interweb to help minimize some of the yaw shake) we were closer………but still no cigar.
The following video was shot on a pretty windy day, you’ll see at one point the quad struggles quiet badly in a gust and the prop guards definitely seem to make it more stable but at the expense of making it a little sluggish. The horizon roll is also clearly visible when the quad yaws :( Again don’t watch it all ( it’s dull) but it will give you an idea.

Lets deal with the horizon drift problem first, where when yawing the craft the gimbal tilts slightly (sometimes not so slightly!) and the horizon is no longer level. A problem on all but the most expensive larger gimbals as it is actually due to simple physics and the way the gimbals sensors know where it is in space. The controller board used in most commercially available gimbals is an Alexmos board and many many people have the horizon drift problem with this board.
Unfortunately I was using the walkera G2-D gimbal with the propriety walkera controller board which is basically a piece of S%$t (the interwebs words not mine-though I do agree). I tried using the ridiculous manual system of pushing a hard to reach button and turning a tiny pot (even harder to reach) on my gimbal to increase the power of the tilt motor without inducing vibration which would cause jello. A truly idiotic procedure with this gimbal! A slight improvement but because of all I had read I realized probably as good as it was going to get.

For the shakes in the yaw axis my research told me this was easy – a 3 axis gimbal.

“So just buy a 3 axis gimbal and be done with it!” I hear you say………If only it were that simple.

At the consumer level the “best” and most expensive 3 axis GoPro gimbal is considered to be the Zenmuse H3-3D by DJI. This gimbal however works best with a NAZA flight controller (the one found in the Phantom and other DJI multirotors) or additional cost for the non-phantom version. This gimbal however does not allow for manual tuning of the parameters ( known as the PID’s) and reading through the forums there are many people having issues, including but not limited to, the dreaded yaw horizon roll.

A cheaper alternative which would work without being hooked up to the flight controller on the quad and hence compatible with my current quad seemed to be the DYS SMART 3 axis GoPro gimbal. This too seems to be far from “Plug and Play” as claimed and requires extensive tuning but at this point is looking very much like my next purchase. It too is not without it’s issues but seems to be a major step up from my current walkera 2 axis P.O.S.

An exciting development in gimbal controllers also seems to be the recently released Phobotic centerpiece which whilst not cheap ($400 for the controller board alone) offers some impressive features such as auto tuning that aim to make it the best controller out there. Videos I’ve seen look very impressive as they should for a gimbal that is going to cost me at least $600 before I even put a GoPro in it and then I’m going to attach it to a $270 quad? I don’t think so.

So from all my experiments and reading the conclusion I have come to is that it is almost impossible to get any pro level footage without spending at least $500 on a quad and to be honest it would seem a much better plan would be to step up to the $850+ range and buy a hexacopter which would also carry more weight. Another $350 minimum on a gimbal and more like $600 for one that includes the Phobotic board. Throw in the cost of a GoPro at $350 and more if you wait for the soon to be released Hero 4 (?) and we are looking at $2000 give or take to get anything truly pro level – lets not even add in the cost of extra batteries, a decent charger and replacement props.

I’ll keep struggling away with my set up for now and will probably buy the DYS 3 axis gimbal. I don’t want to make 7 minute aerial videos, I just need the odd shot for projects I’m working on! So close enough and then a little warp stabiliser may well be good enough.

It’s been and continues to be a very valuable learning experience , frustrating as all hell but above all it’s still damn fun!!

I’m off to fly my little Hubasn X4 around in the little park near my house and not worry about jello and 3 axis stabilisation!

You haven’t heard (or seen) the last of my aerial adventures though I assure you!

 

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