'S T U F F'
Concerning the etheriality of 'stuff'
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Brushless Gimbal Build
So! You've put together a blinding quad, checked everything out, got it trimmed nicely, and having fun under the sun with your favourite fpv goggles on. What's next? Well, if you're anything like me, you get more than a little annoyed at all the wobbling and rippling of the images that your expensive GoPro H3 Black is spewing out, and need something a little better, then don your best wizard's cloak and sharpen your pencil, for it's a fettlin' we will go...
I already have a little experience with gimbals, and have settled on the DJI H3-2D gimbal for my CX4 camera-ship, which I have to say, is a blinding product. There are many 'experts' out there when it comes to gimbals, and I'm certainly not one! But I do know enough of the basics to get me through a simple build.
I've ordered a basic controller board from ebay, which I fully expect to be the 'Martinez' clone type, likely loaded with a 'nulled' or cracked version of the Alexmos 'Simple Brushless Gimbal' organisation. I've had one before, and as long as you don't need the latest firmware with all the follow me stuff onboard, then it's fine. Mine worked out of the box, all I had to do was a quick calibration, and you can even configure a hard wired button to do this trick if you want, or configure it to calibrate on boot, if that turns you on!
If you want a perfectly level horizon, then you'll likely need to do the more extensive 5 point callib, which will involve removing the sensor (IMU) from the gimbal and attaching it to a cube on a level table for best results. I really can't be bothered with all that, I want a simple life, and just need a stable feed/footage that doesn't give me a migrane!
My second order, this time from HK, are two brushless gimbal motors, which I hope will do the job! It says they are suitable for cameras such as GP's and up to 200 gms, so sounds great. :-)
My plan (well I don't actually have a plan as such) is to mount the roll motor to the bulkhead, then form an aluminium arm to mount the pitch motor/camera mount to, really simple actually, and I think, as long as the camera balances statically (i.e not under power) then it will work fine.
Again, I'm not looking to beat DJI at their game, I simply couldn't come anywhere near the mighty H3-2D/H3-3D, but as long as it's a definite improvement to what I have now (an aweful 1 axis servo), that will do. All I think I can improve on with the standard Chinese clone gimbals is the camera mount itself. If only GoPro factored a 1/4-20 UNC screwthread in their designs, the wheel would not need reinventing. I hate using their waterproof casings, they add so much weight, and look awful, they also don't fit in an H3-2D! So I plan to fabricate a small lightweight aluminium case that the GP will slide into, using aluminium angle which I have strewn about my loft room in abundance from the scooter project
Well here she is. It's exactly as I thought it would be, except last time I bought one it cost about £30!! Oh well, we live & learn. I wasted no time in hooking it up to my Mac, although I had to boot it into good old Windows to run the SBG GUI. It looks like a SIlabs chip onboard, so it will auto install the necessary drivers to communicate with the PC. Please read the article at the link further down the page, which describes the ins and outs of these things better than I ever could!
Here I am checking out the sensors. It worked out of the box, but I always like to calibrate the gyro & accelerometer for good measure. Later GUI's have introduced a 5 point calibration, which should get the horizon nice and level, but again, I'm mainly after stable footage from my setup, not commercial perfection, so it's really not necessary to go that far.
This is all you need.
On the left we have the bits so far, including the cheap (£5) 'frame' that should keep the camera firmly attached to the gimbal. Just awaiting the arrival of the motors, then battle will commence!
Here's a link to a great resource site, evrything you ever want to know about these boards is here:
The motors have arrived, they look very nice, but unfortunately I notice on closer inspection that one motor has a loose winding that was poking through between the two halves of the motor!
Oh well, that's the downside to ordering stuff from the other side of the world.
3 holes should be enough!
I have some countersunk m2 x 4 mm hex bolts on the way from boltbase.
This is a cheap £4 'frame' BTW, not the posh GoPro one that costs c. £35! But it's tough, and should do the job.
I dremeled off the mounting pieces, as they will not be used. I find that it holds the camera in without any kind of fixings.
I'm liking these cheap 'Frame's'...
I'm quite enjoying this little challenge, doing a bit as and when the parts arrive.
Hobby King have accepted the faulty motor and have assured me another is being sent out. Oh well, seems to be the theme at the moment, I'm getting all the Friday afternoon bits!
It could be a couple of weeks before it's here, but no matter, I can finish the gimbal, and I expect the motor will work, but wouldn't want it shorting in mid air a mile away, no siree.
At this stage, I'll show you the front of my Xugong-10 quad, and the modification I made to the front bulkhead. It was always a little tight, and made it very cramped for the Naza/ESC wires, so I cut a little of the material away.
Then I spent ages looking for my old faithful drawing set (which I'd had from school days) had no luck, so I went on to the good old interenet and printed myself one! Needs must as they say, This was all I neded to mark out the anti vibe ball spacings (60degs) on the G10 plate.
THat accomplished, I then cut out the two parts of the gimbal backplate/anti-vibe mechanism
I messed up the first backplate (so absorbed was I in my new cheapo hand router) so I modified the next one with two holes each side for the cable ties.
This actually works really well, and the whole unit appears to do the job in terms of vibration absorbtion.
I could have ommited the vibe balls all together I guess, seeings as the quad already has a anti vibe design with the 'clean' & 'dirty' sections, but as I was getting some vibes coming in on the original gimbal at higher speeds, I thought it would be best to adopt this design.
The camera is now really 'out front', so should produce less images of the props, and more of the intended panorama! I haven't measured the difference yet, but I'm guessing it's probably 25mm ahead of the original gimbal position.
Here you can see I added a coin for some counterbalance weight. Despite my best efforts at working out the balance point, a small adjustment was necessary.
Here's a little demo of the gimbal in action. I hadn't remembered to reset the focus on my fpv camera, so I just had to make do with a minute or so of line of sight flying, so I could evaluate the efficiency of the gimbal.
All in all I was very pleased, although I have now removed the dampening plate I spent ages making! It was introducing some wobbles of its own, so I have now just hard mounted it to a G10 plate, which is in turn cable tied to the main frame.
Here's a little demo of how this simple gimbal shapes up. I filmed it on a recent trip to Suffolk, making good use of an early start (05:00). Judge for yourself...
Of course, I now have to solve the issue of where to mount the fpv cam, It's awful in its current location, 20% of the lower half of the screen is taken up by the gimbal & GoPro bobbling about, as much as I'm chuffed with its performance, I don't really want to see it in flight!