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HomeAircraftHelicopterAerial Photography and Video › The roll axis - Stabilization belongs to the heli or the camera?
04-01-2009 05:05 AM  9 years agoPost 1
borneobear

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Kuala Lumpur, Malaysia.

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Fact:
1. Stabilization systems counters the roll experienced by the camera.

2. But an RC Heli will roll on the heli's axis.

Questions:
1. Is the stabilizer sensor placed on the heli's axis or the camera axis?
2. Is the roll axis on the camera mount placed on the camera lense axis or the heli roll axis?

Because the heli roll is happening on the heli's axis (and not the camera), there is a difference in the degree of roll experienced by the camera compared to the heli, unless the axis for both is exactly the same.

If the camera is placed above or below the heli's roll axis, the camera will not only experience a roll, it will also experience a 'swing'.

Based on the above, the camera mount roll axis should be designed to be adjustable so that it can be placed on the heli roll axis, not the camera lense roll axis.

Any input would be much appreciated.

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04-01-2009 06:15 PM  9 years agoPost 2
CrashTestDummy

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CA - USA

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Fact:
1. Stabilization systems counters the roll experienced by the camera.
Not quite - The stabilization system counters the roll experienced on the stabilization systems axis. I believe they're typically mounted one axis off of the axis they stabilize and thus are usually a few inches, or so, off from the lense axis.
If the camera is placed above or below the heli's roll axis, the camera will not only experience a roll, it will also experience a 'swing'.
True - The effect, however, is usually very negligible, especially when compared to all the other movement of the image.
Based on the above, the camera mount roll axis should be designed to be adjustable so that it can be placed on the heli roll axis, not the camera lense roll axis.
That would be interesting to see. There also are other ways to approach the issue, if you consider it an issue. I've not seen a mount design that takes this into consideration much. I have been conceptualizing a mount design that should inherently avoid this. Got a friend fabricator to help with the build once we get some time to put into it.

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04-02-2009 04:56 AM  9 years agoPost 3
borneobear

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Kuala Lumpur, Malaysia.

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The effect, however, is usually very negligible, especially when compared to all the other movement of the image.
I suppose negligible is relative. An AP pilot with rock steady hands will obviously have negligible 'swing' then an inexperienced video pilot.

I'm looking at a mount design that will take away as much of this unwanted movement as possible.
The stabilization system counters the roll experienced on the stabilization systems axis. I believe they're typically mounted one axis off of the axis they stabilize and thus are usually a few inches, or so, off from the lense axis.
From above, we now have 3 (!) roll axis in-the-pot; the stabilizer, the camera gimbal, and the helicopter.
If only all 3 axis were in the same line...

Cheers,
BB

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04-02-2009 05:38 PM  9 years agoPost 4
Wayne Mann

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United States of America

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The blade mount bearings and the center teeter bearings exampleRaptor rotor head) basically make up a ball bearing gymbol. Meaning the mechanics swing beneath the rotor heads central point. The only thing keeping the mechanics in plane with the rotor disk is the dampers in the rotor head. Without the dampers the mechanics would swing in a specific direction depending on which direction the wind is hitting the model from. I have done extensive tests over the years on rotor head stability for F3C stuff. I have flown severl rotor head types without dampers and no delta offset and most rotor heads behave the same way. So my point is unless you can get the camera in the same plane as the rotor disk, it is going to swing back and forth. Obviously the higher you get the camera the less swinging will be experienced. With a relatively stable model it just isn't that much of an issue.

For placement of the gyro sensor, it can go just about anywhere on the camera mount as long as it is not on the actual moving axis. It is just like the gyro sensor on the tail rotor. It can be way out in front of the main shaft or way behind it. The tail rotor sensor placement is best when you put it on the model in a place where it gets the least amount of vibration. However, the camera mount sensors work much better at the top of the mount near where the mount connects with the mechanics IF the camera mount has a lot of flex in it. That flexing will cause an oscilation if the gains are too high. By too high I mean if you have the gains high enough so that you can move the camera mount all over the place and the camera keeps pointing in the same direction with the gyros mounted up high, if you only move the sensors down low on the mount it will usually start to feed back and everything goes to crap.

I hope this helps

Wayne Mann

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