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Old Jan 25, 2013, 07:20 PM
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Originally Posted by Bricobrac View Post
Hi,

i'm glad we could move this way and want to thank Jussi and his partners for having an open mindset too

Also, the fact to kind of distribute the tasks this way helps in moving forward and focus for each one on his "speciality" , and is a first step maybe to other interesting things to work on together

Ok, time to work now, because there is a sh...t load of work to go )))
Any sponsorship from Nespresso coffee would be appreciated lol !

Fabien
Me too..

I use this to brew the "midnight oil" - best damn coffee youŽll ever get...its 01:15 here now - SebastianJ and me is working on the Gopro3 version and putting on another pot in 5 mins

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Old Jan 25, 2013, 07:22 PM
flitelab's Avatar
Canada, NS, Halifax
Joined Feb 2010
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Originally Posted by JussiH View Post
I am happy to tell you that that Viacopter, Flyduino and E-copter will work together on controllers and motors for the Alexmos gimbal systems. This means that you will get the same controller from E-copter, and that we will offer Fabiens custom motor design with the Flyduino/Viacopter gimbal.

We have taken this step to secure a common platform with a steady supply, low prices and high quality of the European version of the Alexmos systems. I am sure this will benefit all, both manuctorers, designers and community.

IŽd like to thank Fabien for an open mindset - together we will be able to make the product stronger and support the platform better and offer a wider range of solutions.

Further announcements to come...stay tuned!
Great approach guys. Should lead to an all around better end product and larger support group. Nice to see this coming together.
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Old Jan 25, 2013, 07:26 PM
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Originally Posted by jamac View Post
It might - sorry about that. But I guess most of us track both of those threads so they might get mixed up.
Can we try to avoid it?
I just raised my voice in the other thread because the mourning came up there.

Somehow reminds me of the release of the AutoQuad FC and ESC32.
Woooah! Too expensive! Gimme ze skematix my friend can do it for less!

DOH!
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Old Jan 25, 2013, 07:40 PM
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This is starting to get really exciting and it's great to see the vendor community working together to bring these new systems to market. There's obviously so much demand that partnership is the most efficient way forward.

On a technical note I think it's worth pointing out that the direct drive servomotor design turns much of the expected dynamics of gimbals on their heads.

With gearbox driven gimbal (i.e. traditional servo drive) you are fighting to "keep up" with the movements in the platform, by actively driving the camera sled in the opposite direction. The larger the camera, the larger and more powerful the drive motorshave to be.

To a large extent, and if my understanding is correct, these new designs are more akin to a Steadicam, which is inherently free and stable. You only apply torque when either you require pan, roll or tilt, OR you start seeing error that you need to correct in those axes (obviously these are 2 DoF while the Steadicam is 3 DoF, but the comparison holds).

This should also mean to a large extent that the scaling up of drives for heavier cameras is not as pronounced as in the geared case, because the heavier cameras are also more inherently stable in themselves (once balanced), only requiring more torque to perform camera rotations and counteract errors, rather than the big muscle required to keep up with platform movements.

I really can't wait to get my hands on one of these systems and try it out for myself. What a perfect time to get back into multicopters?

Martyn
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Old Jan 25, 2013, 07:45 PM
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Originally Posted by JussiH View Post
Me too..

I use this to brew the "midnight oil" - best damn coffee youŽll ever get...its 01:15 here now - SebastianJ and me is working on the Gopro3 version and putting on another pot in 5 mins

LOL ! I killed a bag of Senseo coffee doses in just one day, cracking up the second one..

Working on Skype with Dave on the Go pro 3 gimbal also, we change little things this and there and make some tries..

We might take the bet NOT to align the lens on the roll axis, because this is the frame that moves and when the gimbal is hard mounted even with dampeners, the alignment seems not to add or remove any performances, as the support of the roll anyway moves circular in the space around the mount point and CG of frame..

We made many tests on large gimbals ( standard ones) with big reflex and cameras and the lens was always completely misaligned with the roll rotation axis, and never had any troubles so far.

Yeah ok i understand myself, this would simply allow us to leave the connectors side fully accessible..

Thierry will kill us monday morning loool !

Ah.. coffee time and Dave is getting excited on Skype...

have fun guys, the first going to bed owes a beer to the other team ))
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Old Jan 25, 2013, 07:54 PM
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Originally Posted by Nicodema View Post
To a large extent, and if my understanding is correct, these new designs are more akin to a Steadicam, which is inherently free and stable. You only apply torque when either you require pan, roll or tilt, OR you start seeing error that you need to correct in those axes
If the gimbal would be perfectly balanced, the MR could indeed rotate around it and the camera wouldn't move (assuming you won't get cable mess). If the motors can let go completely. If they have some sort of holding torque permanently, they will move the gimbal when the MR rotates, even if no "correction" signal is applied and then they would need to correct permanently (as the MR also "rotates" permanently in real life).

What you said is however certainly true for the Ecilop type of gimbal (a different thread here on RCG).
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Old Jan 25, 2013, 07:56 PM
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Joined Aug 2002
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Quote:
Originally Posted by Nicodema View Post
This is starting to get really exciting and it's great to see the vendor community working together to bring these new systems to market. There's obviously so much demand that partnership is the most efficient way forward.

On a technical note I think it's worth pointing out that the direct drive servomotor design turns much of the expected dynamics of gimbals on their heads.

With gearbox driven gimbal (i.e. traditional servo drive) you are fighting to "keep up" with the movements in the platform, by actively driving the camera sled in the opposite direction. The larger the camera, the larger and more powerful the drive motorshave to be.

To a large extent, and if my understanding is correct, these new designs are more akin to a Steadicam, which is inherently free and stable. You only apply torque when either you require pan, roll or tilt, OR you start seeing error that you need to correct in those axes (obviously these are 2 DoF while the Steadicam is 3 DoF, but the comparison holds).

This should also mean to a large extent that the scaling up of drives for heavier cameras is not as pronounced as in the geared case, because the heavier cameras are also more inherently stable in themselves (once balanced), only requiring more torque to perform camera rotations and counteract errors, rather than the big muscle required to keep up with platform movements.

I really can't wait to get my hands on one of these systems and try it out for myself. What a perfect time to get back into multicopters?

Martyn
Hi,

in a perfect world, we would have a system like steadycam tube support, and stabilised by FC, onboard of the multi rotor at the exact CG of the frames ( height included). This way the support for the 2 or 3 axis gimbal linked up to that steady shaft would remain perfectly vertical all time and we would not have any big changes in the picture " field" when performing fast stops, big circles or simply fast " cyclic" moves.

We would use then 2 +2 or 2 + 3 axis .

Now in reality from what we tested, the roll axis is not needed to be aligned with the lens of the camera because simply the camera has to remained leveled only, it can not keep horizontal or vertical absolute position when the frames are moving forward / backward and sideways, because the position of the roll axis is way under the frames in most cases, and is moving as a lever when cyclic changes are applied, so it will move the entire picture " field" , even if it's perfectly aligned.

It's very easy to demonstrate but harder to explain, let's say you take your gimbal in hands with your arm sraight down. If you move your wrestle only, camera gimbal can compensate and you don't see noticeable field change in height. But if you move your entire arm forward and keep your wrestle straight also, you will see field height changes. This is because your shoulder acts as a lever and any suspended actual gimbal without an additional steady system acts this way..

We are trying anyway the tilt motor on the other side and just make good cg to make a test, as we are almost sure 99% this son't have any effect on the quality and will only make the plugs and cable stuffs easier..

Congrats if you understood half of what i tried to explain as i have an headache just trying to re read myself lol !

Baaah attached is a picture of what we would need, gravity/ dampened or compensated, to get it really levelled all time including picture field lol

Best regards
Fabien
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Old Jan 25, 2013, 09:51 PM
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how scalable is the system? is there a theoretical maximum payload? there must be a point where the inertia of the camera plus the weight of the motors is just too great for a multi? (ie, law of diminishing returns)
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Old Jan 26, 2013, 12:16 AM
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Originally Posted by chris24g View Post
how scalable is the system? is there a theoretical maximum payload? there must be a point where the inertia of the camera plus the weight of the motors is just too great for a multi? (ie, law of diminishing returns)
From what I've seen, it's not about weight. Scalability is more about motor/prop (efficiency) combination than anything. Yes you want to keep your weight down to a minimum. But power to weight ratio + efficiency is what to shoot for.
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Old Jan 26, 2013, 02:08 AM
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sorry if i wasnt clear. i was referring to the weight of the gimbal motors and the camera. my intuition tells me that trying to stabilize a camera that weighs several pounds or more would require some pretty torquey (and heavy) motors
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Old Jan 26, 2013, 10:59 AM
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JussiH's Avatar
3rd stone from the sun
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Originally Posted by chris24g View Post
sorry if i wasnt clear. i was referring to the weight of the gimbal motors and the camera. my intuition tells me that trying to stabilize a camera that weighs several pounds or more would require some pretty torquey (and heavy) motors
The honest answer is that we dont know the upper limit. But big gimbals with DSLRs have been shown based on this technology and they look to be working just fine.

If the camera is balanced out, the motors only have to overcome inertia, so it would be my guess that up to 1kg cams should be well within reasonable limits.

We are working on a DSLR and Camcorder version. I am gonna try to make it swing a Nikon D300, which is about a kilo with a short lens.
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Old Jan 26, 2013, 11:01 AM
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Originally Posted by Bricobrac View Post
We might take the bet NOT to align the lens on the roll axis, because this is the frame that moves and when the gimbal is hard mounted even with dampeners, the alignment seems not to add or remove any performances, as the support of the roll anyway moves circular in the space around the mount point and CG of frame..

We made many tests on large gimbals ( standard ones) with big reflex and cameras and the lens was always completely misaligned with the roll rotation axis, and never had any troubles so far.
I'm happy that gimbal is being designed by someone who understands basic physics.... I'm glad you confirmed what I said in the other thread - it does not matter if the lens is NOT exactly on roll axis. As you say - its the copter which moves and not the lens/camera.. therefore this is not that important.
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Old Jan 26, 2013, 11:02 AM
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Biggest issue with some larger cameras and even the smaller mirrorless ones like NEX might be the larger lens, which will be harder to balance.

Wonder if you could make a counterweight boom with a sliding weight to allow for different lens perhaps?
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Old Jan 26, 2013, 11:13 AM
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Very good ,Great design!
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Old Jan 26, 2013, 11:16 AM
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I think it is quite important to be able to balance a camera, as with Steadicam, the CG alone is not all, the dynamic CG can be very tricky. And you will never have a perfect balance once for all, as you will need to add or remove neutral density filters to get needed exposure and not get that strobe effect. Good glass is heavy, and a lens change often needed. When designing a gimbal, the gimbal itself should be as compact as possible and as close to the CG of the whole UAV (again out of Steadicam experience). Why does it seem as if the third axis (pan) is not so much considered ( panning with the copter is unexceptable for a camera movement). Rolling axis must not go through the optical axis, but in case you want to use it for an other application, it absolutely needs to, so ideally pan, tilt and roll should go through the focal point.. :-)
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