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Old 02-04-06, 10:25 PM   #1
phantomcow2
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What makes a servo motor difficult to drive?

This really puzzles me. What is it that makes servo motor drivers so difficult to make? So complicated?
I would think a stepper is more complicated, as you have multiple wires, phases, etc.
But when i look at prices of Servo drivers, I get the impression they are more difficult to produce. But doesn't a typical servo have just 3 motors? -, +, and the one for PWM?
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Old 02-04-06, 10:30 PM   #2
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1 motor, 3 wires usually
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Old 02-04-06, 10:36 PM   #3
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Originally Posted by phantomcow2
This really puzzles me. What is it that makes servo motor drivers so difficult to make? So complicated?
I would think a stepper is more complicated, as you have multiple wires, phases, etc.
But when i look at prices of Servo drivers, I get the impression they are more difficult to produce. But doesn't a typical servo have just 3 motors? -, +, and the one for PWM?
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Old 02-04-06, 10:38 PM   #4
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Oh yea, one motor 3 wires.
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Old 02-04-06, 10:50 PM   #5
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depends on the servo, R/C servos can be pricey considering their size, but they are limited production items

case, gearbox, small circuit, motor--slightly more to them than a stepper motor
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Old 02-04-06, 10:57 PM   #6
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This would be a servo with an encoder, controlled by the PC
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Old 02-04-06, 11:16 PM   #7
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well, its a specialty item

not sure what your asking here? drivers as in software or what? what exactly are you puzzled about?
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Old 02-04-06, 11:27 PM   #8
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Drivers, what is necessary to make a driver. Or well, why are the drivers so complicated compared to stepper drivers>
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Old 02-04-06, 11:31 PM   #9
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most servos can be controlled with greater precision, due to feedback. It's a more complicated mechanism, for obvious reasons.
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Old 02-04-06, 11:38 PM   #10
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Drivers, what is necessary to make a driver. Or well, why are the drivers so complicated compared to stepper drivers>
hardware or software? need more specifics here, what exactly are you trying to do, cant read minds.

do you want to run a servo from a PC and have the PC do all the work with software drivers or what? and if so, your gonna need to know exactly what interface and what kind of a connection youve got.

best way would probably do most of it with a small oscillating circuit and have the PC just modulate the signal, serial connection would be fine.......this what your trying to do?
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Old 02-04-06, 11:44 PM   #11
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I mean driver for the motor, hardware. Like with a stepper system you have the PC that connects to the stepper drivers via Parallel cable. And then stepper motors to the drivers.
THis is for a motion control application

I have software that will driver a servo motor, called EMC. As long as I could use that software to control the servos, i would be happy. I just keep thinking I need an external driver for the servo if I want to go that route.
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Old 02-05-06, 12:08 AM   #12
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Well your terms are getting me confused but I think I understand what you want, well yes you do need a small circuit between the PC connection and the servo. It will provide a signal to the servo so it maintains its position then moves when you modulate the signal thru software. Gonna need the specs of the servo and the software if you wanna do this, been like 10 years since ive done this, but that is the short version.

The circuit itself is small and fairly simple, shouldnt be too hard to find a schematic for one to wire up, but w/o knowing what the software is going to want in advance this wont get far.
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Old 02-05-06, 12:14 AM   #13
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It would be for a CNC application. A lot of folks use Gecko drives for this.
But I am not interested in paying $350 for the drivers, when i can just as easily use stepper motors for much less of a cost.
Software is EMC

I have a 28VDC 14A power supply also...
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Old 02-05-06, 12:22 AM   #14
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Well, Ive never heard of EMC or gecko drives but I suppose I can look it up, but Id imagine CNC will use stepper motors and/or servos not just servos, dont know unless Ive got the specs for all this in front of me. With 28v and 14A you will need either transistors or mosfets to drive the motors too, TTL wont do it thats for sure.

You really should take this to an electonics forum and be prepared to have a whole lot more info or all your gonna get is dumb looks and stupid questions honestly unless you run into someone that has actually worked with this EXACT equipment before, which I havent. Ive done this with R/C servos and other PC interfaces, all of it homebrew stuff. Isnt real complicated, but it isnt just plug and play either.
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Old 02-05-06, 12:30 AM   #15
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A lot of CNC applications use servos. Just with a decent belt reduction so you get torque and high speed torque.

I've always had good luck with this forum, and i dont like signing up for others because it clutters my inbox
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