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Best servo controller to use?
Billy from United States  [26 posts]
10 years
I'm looking at building a robot using RoboRelam.  The platform is based on the iRobot create, and RR will be running on a mini-itx system onboard.  it will have have a 5 DoF arm.  I'm looking at varius servo controllers and would like to know what you all think would be the best and most stable with RR.  I would prefer to use a USB device as the mini-itx board will have 6 USB interfaces.  Also, which camera do you all think is better? The Creative Live motion or the Logitech Orbit?

Thanks, Billy
Anonymous from United Kingdom  [99 posts] 10 years
If you aren't going to roll your own servo controller, the pololu SSC is great.  8 channels, and control is already written in RoboRealm.  If you need USB,I haven't tried it but I would bet that it would work with any decent USB to Serial converter.  I bought a couple different ones and some work better then  others.  Here is a link to a quick page on my experiences with them:
http://profmason.com/?p=312

If you want to roll your own, a $4 picaxe14M or Arduino can control 5 servos.  
Here is a link to the Arduino servo project I just did:
http://profmason.com/?p=543

good luck!
Anonymous from United Kingdom  [99 posts] 10 years
I didn't answer both questions!

The Quickcam orbit was pretty disappointing as a pan and tilt platform, (Not much pan or tilt!)  I haven't tried the Creative Camera. As long as you are using all those servos, use two more and use a servo based pan and tilt platform.  You will get much better range of motion and more accurate positioning.  A servo pan platform is easy to build, (wire tie camera to servo)  I am working on tilt right now, but kits are available from lynxmotion and budget robotics.

have fun
Anonymous 10 years
Billy,

To our knowledge all of the servo controllers that RR communicates with work reasonably well (this is excluding hash environments, old equipment, dogs that like to eat wires, etc). So you're probably best of using number of servos, USB capabilities and cost as factors to consider.

If you're building an arm perhaps you can get one already assembled? I know that lynxmotion has some nice ones.

FYI, we prefer the new Logitech Orbit AF just cause it is new and has mechanical focus built into it ... but it is a little more pricey that its older counterpart or the Creative Live.

STeven.
Anonymous 10 years
I'm looking into the Parallax PSC-USB unit.. It looks to be able to Drive servos @ 7.2v unlike the rest which only go up to 6v.  I'll have a servo which will need to run @ 7.2v for the extra torque.  However, look at the RR modules.. I'm curious, why do they all look so different?  the PSC-USB looks to support speed, but the RR module doesn't have it...  As for the Web Cam, I was looking at the newer Logitech..  Any of you that has that one.. can you tell me how the 9" extension works? Does it have wires in it or something?  I'm assuming the base is what does the panning..

Thanks, Billy
Anonymous 10 years
Billy,

Yes, the modules will look a little different as some will support better control capabilities than others. For the most part the modules are just used to control basic movement without too much concern about the rate or ramp up speed for each of the servos. It is also possible that vendors improve the control system without our knowledge and thus the module (while still working) may not support the latest protocol extensions. If you do see this issue just let us know as it is easy to bring the interface up to speed.

We will update the PSC module to include Servo Rate and Pause.

The 9" extension on the Logitech is a static solid bar that simply raises the camera up to about face height when seated. It has a connection in the middle of its core that connects the top of the camera with the bottom control signals. The pan/tilt happen at the TOP of the camera in the ball type area. The base does not move.

STeven.

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