There is not a great selection of decent 3 axis camera mounts for gopro sized cameras so I have started building my own. The first one will be a ‘nose mount’ and I may later consider a belly mount for quads etc. It will have one standard sized digital servo for roll and 2 micro sized ones. The belt drive gearing is to increase the rotation angle up to 280deg. All pivots will have deep groove ball bearings.
I hope to mould a thin carbon fibre cover for rain protection (it hasn’t stopped here for 6 months).
This will fit on the nose of the Holden UAV, which has now had many successful flights with an APM2. More of that
Comments
Great project! Will you be making the design open source?
I agree with R_Lefebvre, I would also like to add that direct mounting puts a very large load on your servos. You may consider incorporating some of the concepts used by ServoCity for their mounts. Either way please consider using a seperate power supply/battery for the gimbal while testing. I have seen a few expensive vehicles lost due to binding servos browning out the receiver/AP.
I know your design if for carbon fibre and aluminum but if you want to prototype something in ABS to prove the design feel free to send me a message.
Firefly
hard to beat these ones... micro and metal gears, digital... and price is good too...
EMAX-ES08MD
I will soon do a video of how smooth they are.
Take a look at my GoPro Hero2 simple gimbal...see the video also on the link below.
http://diydrones.com/forum/topics/h-frame-quad-for-10-weight-1kg-wi...
What would be great is if there were more choices in servos with a full metal case. This would really help make a stiff direct mounting. Something like this:
http://www.hobbyking.com/hobbyking/store/__22607__Turnigy_Integrate...
This:
http://www.hobbyking.com/hobbyking/store/__12451__Turnigy_MG959_All...
Or this in a Micro:
http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idproduct=...
My initial sketches were for a belly mount with the pan gimbal first (working from plane to camera), then roll and tilt. I incorrectly transposed the bits for a front mount. Good spot.
Direct mounting servos – yes I agree its a bit of a tempting shortcut and was intending to use a serious 2 bearing digital for that one. I usually over engineer but am forcing myself to start simple, light and small, then fix things that need fixing.
I think I will go back to my first idea and start out with a belly mount. Dont really want to hack the nose off my plane!
Any advice/opinions gratefully received.
Vince, you have really nice design skills, but I feel I should point out a few issues with your design. I have been engrossed in gimbal design for a while and have seen a lot of various successes and failures.
1) Roll is usually a child of yaw. You have it the other way. If you have the camera pointed to the side, and the airplane pitches down, you won't be able to level the image.
2)Direct mounting of roll axis to servo. This isn't great. This will result in a sloppy joint, which will allow for vibration/shaking. Ideally you should use a rigid shaft with bearings, driven by a belt or gears. Look at the Servo City Power Servo Gearbox for inspiration. At the very least, use a Servo City Servo Block here, as the bearing will be much better than that in the servo case.
3) Gearing up for yaw. This is not great. Servos jitter, and you will magnify that jitter. Normally people gear down to reduce the jitter. You should either use a 180° 1:1, or gear it down and use an external pot.
4) Direct drive of pitch. Similar problem as for the yaw, (and Roll, really). This is doable if you have VERY good servos. I've never seen a very good micro servo.
Fantastic aircraft by the way!
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