Hi everyone,
I've been learning a lot from reading on the forum but this is my first post here. Seems I'm the only person over-thinking Gimbal setups, not a lot of posts in here.
So my friend and I have built our first UAV (3DR Pixhawk/DJI flamewheel+esc+motor mix) but stumbling on the camera side. Trying to choose gimbal+camera, seeing a lot of options but it all comes down to the pricing really, trying to get the best quality & features for the best value. Don't want to cheap it out and 'get what I paid for', but the funding is limited.
I've noted there are 3-axis gimbals (already worked out 3-axis required) that also allow you to manually control all three axes. So in my mind if you're flying along a path, the camera can manouever independently without the UAV having to turn to point at the target.
So, 1st question: How much of a big deal is it and what are the important factors for this decision? Is there a difference in battery consumption? Smoothness of camera operation? Anything else?
2nd question, is that 'manual control' the same gimbal feature required for the computer to control the gimbal as well for computer vision tracking applications like with the odroid or percepto or otherwise? Or would it just use its inherent stabilizing ability to handle that?
Would appreciate any advice and insight you can give, thanks much.
Replies
Gimbals are a tricky subject in general. Starting with a 3 axis gimbal is a challenging task but doable. Some of the major factors that you have to look into are:
Gimbal weight:
- How much additional weight can your frame carry?
- The larger the camera the larger the gimbal
Camera Selection:
- Simple gimbals designed for GOPRO's are usually only mounted on one side of the camera without a tray (no bearing opposite camera) since the GOPRO does not generally weight much. Keep in mind while this is a simple design it has its drawbacks.
- Additional weight
- Zoom lenses above 10X are incredibly difficult to achieve stable video with. Not impossible, but keep in mind you are adding to your difficulty starting out
Gimbal Design:
A well balanced gimbal is essential to it functioning properly. Depending on the camera you want a gimbal with adjustment points on the pitch / roll and yaw axis. UNLESS it is designed exactly for the camera / lens you intend to use (Rare outside of gopro's)
Gimbal Use:
- Some gimbals can interface with the flight computer to maintain its focus on a single point as you fly around
- Some gimbals use through hole motors to have tidy wiring. A benifit of this is usually a 360 degree yaw capability. (With limits on wire entanglement.)
Other:
Your ESC / motor mix will play heavily into how well the final video product looks. Vibrations from the motors and a flexing frame (like the flamewheel series) can limit your quality drastically. Bad tuning on your frame will induce excessive motion in the gimbal and will also turn up in your video footage.
Bad props can ruin footage
Top Mounted (Inverted) gimbals are a pain
a shifted COG due to gimbal placement on the frame can make flying difficult.
Above are some basic things to consider while selecting a gimbal. without knowing your intended application / camera there isn't much I can specifically give guidance for.
Homemade gimbals are also an option with enough research and selection in order to keep associated costs down. But intend to spend a significant amount of time tuning to achieve your desired performance.
Hey Maury,
Really appreciate the insight you've provided. It's a pity you didn't see my post earlier :-(
I ended up going with a DYS 3-axis which holds a gopro. It's been a real pain - easily the most challenging thing I've had to deal with so far. It's not a bad gimbal but perfecting the setup is the problem. Why can't they just come standard with proper setup. While flying sometimes it randomly yaws (eg. 180deg) or rolls (eg. 40deg), so I'm wondering if I need to raise the power and again tweak PID settings etc. Also couldn't find an adapter to mount it so had to get carbon fiber arms from helipal and hang it from its rods so its really tall. Because of the gimbal being heavy+gopro+helipal mounting kit the weight has also gone up so now I'm fighting with flight time.
Starting to believe if I had spent the money and gone with a H3-3D I would have made a better choice.
Personally I absolutely hate zenmuse gimbals. They work great until they don't and then you are stuck with something that'll never work again. The DIY in me just cannot ever use them. For example, I have several friends who use them with their phantoms and once their roll is offset it always stays offset, no help no support.
With regards to the DYS gimbal I have one of those as well.
Large uncommanded yaw can be caused from:
-ESC's / magnetic interference influencing the onboard magnetometer. Try moving power wires / ESC's away from the gimbal control board where the mag resides.
-Vibrations saturating the control board.
- Using an 8 bit board where the camera deflection angle is greater than ~30 degree's. 8 bit boards have problems telling the difference between roll / pitch and yaw at extreme angles. If it is only happening at steep angles that is usually the problem.
A second IMU usually removes the majority of the above mentioned problems. If a second IMU is not available setting up your FC to provide input to the gimbal will also significantly help.
For help with mounting options find somebody with a 3d printer. Or order a part online from a 3d printing store. If you are still looking for parts let me know. I know a few great ways to acquire them.