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Jan 23, 2013, 04:20 PM
Registered User
One question I have about these type of controls is, what happens when the gimbal or motor stalls for some reason? There is no positional feedback to know where it is, it is all relative.

Say it starts up normally, that motor/gimbal positions are 0, or center, well call that the datum. What happens when inertia overcomes torque, when you are flying fast and stop fast, and the gimbal wants to swing causing inertia to overcome the torque and the motor "skips"? Since its a relative positioning system it would now "center" at a different position than it started.

I am assuming this is why you stress that it must be well balanced, so as to minimize these effects.

What happens when you have a cam like an SLR, where you position the lens to be coincident with the axis, but the mass is deviant?

It would not be difficult to add positional feedback via a pot and make it a full closed loop servo system.
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Jan 23, 2013, 05:13 PM
Registered User
DorianJ's Avatar
Quote:
Originally Posted by KKUSA
One question I have about these type of controls is, what happens when the gimbal or motor stalls for some reason? There is no positional feedback to know where it is, it is all relative.

Say it starts up normally, that motor/gimbal positions are 0, or center, well call that the datum. What happens when inertia overcomes torque, when you are flying fast and stop fast, and the gimbal wants to swing causing inertia to overcome the torque and the motor "skips"? Since its a relative positioning system it would now "center" at a different position than it started.

I am assuming this is why you stress that it must be well balanced, so as to minimize these effects.

What happens when you have a cam like an SLR, where you position the lens to be coincident with the axis, but the mass is deviant?

It would not be difficult to add positional feedback via a pot and make it a full closed loop servo system.
Fabulous questions.
Jan 23, 2013, 05:21 PM
AutoQuad OS developer
maximal's Avatar
Don't know about position feedback (good idea!), but of course the Zen is sold configured for specific camera and lens combos. And nothing close to SLR size.

-Max
Jan 23, 2013, 05:29 PM
OS Sponsor
kinderkram's Avatar
Another question if you look at ~1:40
How does the controller know that it's not level?

Home Made Brushless Direct Drive Gimbal (6 min 4 sec)


I guess the "trick" is to build a setup where motors can handle the inertia without skipping. And a firmware which "knows" that the motor just stalled.

I'm pretty sure there will be some teething problems when going for bigger heavier/cameras. But I'm also sure there will a lot of testing and checking going on in the next few month...

We can only get better.
Jan 23, 2013, 05:43 PM
OS Sponsor
kinderkram's Avatar
If size matters...
I find the Photohigher Hero gimbal very attractive:



Jan 23, 2013, 05:53 PM
Friend is a 4 letter word...
JussiH's Avatar
The MPU6050 fixed to camera is serving as the encoder/feedback. So in essence it is a closed loop system. But its the "Simple" version.

Of course there are other ways to do it - like Maxon motors, external optical encoders or other types of encoder that will give you resolutions and accuracies down to 1/10īs of a degree or lower. That is already beeing worked on by Autoquad team members, but it will be more complicated to build and more expensive.

If you stall the gimbal, it will go a few steps back and then try again to reach the desired angle. You wont burn motors or anything like that.
Jan 23, 2013, 05:55 PM
Registered User
Quote:
Originally Posted by kinderkram
Another question if you look at ~1:40
How does the controller know that it's not level?

https://www.youtube.com/watch?v=9_8Kb_fXRrU

I guess the "trick" is to build a setup where motors can handle the inertia without skipping. And a firmware which "knows" that the motor just stalled.

I'm pretty sure there will be some teething problems when going for bigger heavier/cameras. But I'm also sure there will a lot of testing and checking going on in the next few month...

We can only get better.
Absolutely!!!

One inexpensive, compact way to provide feedback would be a single analog hall effect sensor and magnet. It wouldnt need to be 100% accurate, nor would it need to provide absolute position, but it could tell if it is not level, or deviated from the datum. Then there could be an automatic re-centering method.

A single hall, detecting rotor magnets could even be employed, but it would be a little more difficult.

I personally think that if this is to be used on more than just a few specific cameras, some positional feedback is going to be necessary.

A simple pot could be easily implemented as well. Using a decent quality pot we could have very good positional accuracy.
Jan 23, 2013, 06:07 PM
DiaLFonZo - UAV/Drone
Dialfonzo's Avatar
Quote:
Originally Posted by kinderkram
If size matters...
I find the Photohigher Hero gimbal very attractive:



Speachless...
Jan 23, 2013, 06:14 PM
Registered User
~>Miha<~'s Avatar
Quote:
Originally Posted by Dialfonzo
Speachless...
You got it. That's what these bling-bling gimbals are made for. To make the client speechless so he will pay any rate. Would be good though if it works technically too.
Jan 23, 2013, 07:25 PM
DiaLFonZo - UAV/Drone
Dialfonzo's Avatar
Quote:
Originally Posted by ~>Miha<~
You got it. That's what these bling-bling gimbals are made for. To make the client speechless so he will pay any rate. Would be good though if it works technically too.
If i had something like that. i would just put in on a shelf and look at it.. HaHa..
(but i do see the point, i am just in love with CF)
Jan 23, 2013, 07:49 PM
Begin with end in mind...
power's Avatar
Carbon is attractive but function is more important. I believe in simplicity and things appear to be on the right track here I have no idea of the cost but IMO that carbon gimbal is for folks with a ton of "expendable" income. It will not be inexpensive....

Mike
Jan 23, 2013, 08:11 PM
Registered User
~>Miha<~'s Avatar
Quote:
Originally Posted by power
Carbon is attractive but function is more important.
Couldn't agree more: Function is everything!

But those bling-bling manufacturers don't earn their millions with us who earn money doing AP/AV. It's for those noobs who think they could earn money by just buying overpriced stuff (they'll never break even...). And for the very few pros who use it to show off and justify rates or those who get sponsored by the manufacturers.

My stuff looks like post-apocalyptic Mad Max design, but it works. Anything else is irrelevant and I won't pay for. I hope this projects goes for functionality too.
Jan 23, 2013, 08:12 PM
Registered User
apache74's Avatar
Quote:
Originally Posted by kinderkram
impatiently waiting!
Me too
Jan 23, 2013, 08:31 PM
OS Sponsor
kinderkram's Avatar
Quote:
Originally Posted by ~>Miha<~
I hope this projects goes for functionality too.
You can bet!

This project already focusses on simplicity combined with functionality.
Doesn't mean it has to be ugly like the nite...

Good thing is the poor man can get as stable footage as the rich man.
Mission accomplished.
Jan 23, 2013, 10:31 PM
Registered User
Guizmo12's Avatar
subscribe and hope to pre order the DSLR version soon.


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