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position control

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mily

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Hi,

I've found this forum with hope to start my investigation of proper position controller for my stabilized gimbal. I want to stabilize gimbal attached to the flying platform by use of direct motors and take an input from some gyro, accs.. Chosed EC45 flat version from Maxon due to its very good torque parameters and built encoder providing closed loop. There are some minature position controllers like EPOS2 but they need some CAN master on the CAN bus (EPOS P) to control it - this give too much size for the minature gimbal.
Do you have an idea how I can control such the drives. Is there any minature motion/position controller you can suggest to use and how can I control it?
 
Does the mount need to rotate freely 360 degrees? If not you could do this quiet easily using two headinglock gyro's designed for RC helicopters and a couple of heavy duty hobby servos.
 
strantor, all that will do is make it bob around like a weeble wobble, the system would be completely undamped , you could mechanically add critical dampening with spring/shocks but active gimbal correction provides superior results, and seeing as how the gimbal needs to be driven anyways active damping makes perfect sense.
 
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Active gimbals? You can do them with off the shelf components... Many people have made more sophisticated ones that will fit on model aircraft. It's not just feasible it's been done before.
 
Servos provide quite much backlash - I want to use direct EC motors with high torque - I couldn't find such a ready to use stuff in the market. There a lot of gimbals steered in 3-axis with servos but not direct motors.
Yes the gimbal must turn 360 degrees. Please look into something like this: **broken link removed** .
 
strantor, all that will do is make it bob around like a weeble wobble, the system would be completely undamped , you could mechanically add critical dampening with spring/shocks but active gimbal correction provides superior results, and seeing as how the gimbal needs to be driven anyways active damping makes perfect sense.

I'm sorry I must disagree. I work in a plant that manufactures cables. The machines that make cables (tubular stranders) consist of a long spinning tube, and inside the tube a series of gimbles that hold reels of wire. The gimbles are more or less stationary and tube rotates around them. These gmbles are steady as a rock while the machine runs, and the only thing keeping them in that position is their bottom heaviness. they do list maybe a fraction of a degree upon starting and stopping but nothing that could reasonably be referred to as weeble wobbling. here is a video example.
 
strantor, I have no idea where your thought process is coming from, this has nothing whatsoever to do with the type of gimbal that mily is talking about. The device you posted the video for is critically damped by the mechanical linkage to the ground and other structural linkages. Mily's gimbal is a free floating 2 or 3 axis gimbal that requires crtical damping in free space.

This is the type of device he's trying to build, this can not be achieved mechanically practically without extreme mechanics (such as a steady cam) which work great but... Are insanely complicated and bulky in comparison to an active correction. Active correction is however harder to get critical damping on because the control loop has to be updated incredibly fast.

A modern example of this is the Segway, which requires some pretty high speed (which is becoming cheaper) gyro sensors and close loop control.

You can't make something like that stable with a deadweight on the bottom, go ahead try it, it will oscillate all over the place because it's under damped with anything more than the lightest of movement.
 
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ooops, my bad. I didn't take the apparently expected (by OP) chunk of time out of my day to google all the obscure lingo and model numbers in post #1 so I had no idea OP was talking about specialty camera gear. All I knew or cared about was that OP wanted a stable gimble, which I deal with every day, so I figured I had valid input. I guess I should have left this post alone.
 
Strantor, specialty camera gear has nothing to do with this specifically, it's just what will be mounted in the gimbal, he was quiet clear with no obscurity or odd lingo in the original post.

I've found this forum with hope to start my investigation of proper position controller for my stabilized gimbal. I want to stabilize gimbal attached to the flying platform by use of direct motors and take an input from some gyro, accs..

You deal with a single type of application of a gimbal that is mechanical, not all types of gimbals and applications; you allowed your experience to respond before your understanding of their application of it.

If you take the time to respond do so in relation to the posters intentions not what you perceive of them. Which really doesn't take that much time often, and you can always ask questions to clarify.

I've done this myself many times and the only thing to do is say I'm sorry I was wrong and move on, don't try pass the blame along to you not having enough time because it would have taken less time to research the original posters intent than I took to respond your chastisement of my perception of the original posters goal.

We're all here to help, lets not be bitter about it ;);)
 
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Trace it back strantor =)
 
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