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Looking for Smooth movement for camera rig

 
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bbc540



Joined: 15 Dec 2010
Posts: 3
Location: West Midlands

PostPosted: Fri Dec 17, 2010 12:22 pm    Post subject: Looking for Smooth movement for camera rig Reply with quote

This is my first post and I have to admit to being a complete electronics plank - but I'm willing to learn!

I'm looking for a drive solution for a video camera rig that will give smooth motion approaching that of a fluid head. The compact size of RC servos and low cost is attractive but in my testing I'm finding that whilst I can achieve visually smooth movement using an Arduino and cosine or quadratic curves, whilst holding the test platform (a servocity tilt mechanism) I can feel vibration.

Can OpenServo offer really smooth sweeps with an RC servo?

Since I'm a total newb in this field, I would ideally like to buy a complete servo with OS and a magnetic encoder built-in to do some testing, but I have so far been unable to locate such a combo.

The 01Mechatronics offering looks interesting and offers an Arduino library, but it appears that they use a linear accel and decel ramp rather than the OS hermite, which looks a more practical proposition for smooth camera moves.

At the present time I see that Robotfuzz has no stock of OS boards which would leave me with either the 01Mech or Sparkfun options.

Does ths Sparkfun board still use OS v2 and does v2 use the smooth hermite curves?

Any advice would be appreciated, but please keep it simple - I already feel like I've stepped out of pre-school into the degree classroom!
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jharvey
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Joined: 15 Mar 2009
Posts: 361
Location: Maine USA

PostPosted: Fri Dec 17, 2010 10:10 pm    Post subject: Reply with quote

Sounds like I should reply. I'm the fellow that made the OE. I have some OSV3's and OE's around that can be put in the MG996's I have around. I can sell you parts or assemble them. I don't typically do this, so it may be a bit expensive to purchase via me. I'm selling the parts at a much lower rate. My goal in selling he magets and such parts is that I end up with enough money to buy more parts.

I think you can get a nice smooth flow, you will need a solid supply. I don't have much time right now. I'll try to reply a bit better during the weekend.
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jharvey
co-admin


Joined: 15 Mar 2009
Posts: 361
Location: Maine USA

PostPosted: Sat Dec 18, 2010 11:46 am    Post subject: Reply with quote

I think Robotfuzz may have let the OSV3 inventory shrink because there has been work on the OSV4.

The backlash in the gears allows a small amount of jitter. It was measured at 2 to 4 bits by OE, so less than .3 degree's of backlash. When the servo holds the shaft in position, you can feel a small click when you manually rotate the shaft CW and CCW, it's not much, and I believe it shouldn't a problem for most camera mounted applications.

How many are you looking for?

What are you general skills, sounds like mechanical, so software might be a bit of a obstacle.
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bbc540



Joined: 15 Dec 2010
Posts: 3
Location: West Midlands

PostPosted: Sat Dec 18, 2010 5:36 pm    Post subject: Reply with quote

Accuracy is probably less of an issue for my application than smooth movement, so the MG996's sound fine.

At this stage I'd be happier working with building blocks rather than components, so fully working units are a better option and take some of the guesswork out of the process for me!
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