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--Trying to figure out how to use a large-ish worm-drive windshield wiper motor behave like a servo; i.e. input a signal from a Stamp and have it turn the output shaft only so far. Anyone got a clue?
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SF Bay Area
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Re: Making big-ass servos??
Mon, November 21, 2005 - 12:29 PMThe first thing that comes to mind is to add an optical encoder to it.
At it's simplest this can be a wheel with holes in in and a light source on one side and a sensor on the other. Each time it hits a hole you count one, and in this way you can have the chip keep track of how far it has rotated. -
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Re: Making big-ass servos??
Wed, November 23, 2005 - 12:31 PM--Yeah I guess. I'm just kinda unsure how one deals with overrun or backlash.. -
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Re: Making big-ass servos??
Wed, November 23, 2005 - 8:46 PMTo prevent overrun, you use limit switches at the ends.
To prevent backlash, you provide feedback at the proper place.
BTW, another feddback device besides optical encoders uses potentiometers. You can make any motor into a servio by providing one of these types of feedback. -
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Re: Making big-ass servos??
Mon, November 28, 2005 - 10:12 PMWow, my spelling was poor on that one! Sorry....
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Re: Making big-ass servos??
Tue, December 6, 2005 - 1:33 PMQuite true RE potentiometers, in the meantime since my first response I discovered the wonders of pic chips and the sheer joy that is the POT command, I think that would now be my first solution for this issue. . .
At least until I learn something new and cool to replace it in my ferretlike attention span :) -
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Re: Making big-ass servos??
Wed, December 7, 2005 - 3:54 PM--Re Pics: what books do you recommend for an utter newbie? Is there anything like the Parallax curriculum out there? -
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Re: Making big-ass servos??
Mon, December 12, 2005 - 10:30 AMI learned all I know from the electronics for artists class at the crucible in Oakland, but my teacher mentioned a few books (which I need to go shopping for as well)
www.amazon.com/gp/product...408-3155308
and
www.amazon.com/gp/product...408-3155308
both come recommended and look likely. -
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Re: Making big-ass servos??
Mon, December 12, 2005 - 9:17 PM--Thanks; I'll take a closer look at those. IIRC they're in stock at HSC so whoever wants can flip thru the pages... -
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Re: Making big-ass servos??
Tue, April 3, 2007 - 12:43 PMvantec.com/products.htm
RBSA R/C Bully Servo Amplifier,The electronics package to build your own very high power servo from your mechanics
i have wanted to buy this for ever just have never had the cash to do so.
i did end up with a few seiko 27 Ft/Lb servo (very cool)
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This is the maximum depth. Additional responses will not be threaded.
Re: Making big-ass servos??
Wed, April 4, 2007 - 10:32 PM--Niiiice! But I didn't see a price; any idea what they're asking for it? -
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Re: Making big-ass servos??
Wed, April 4, 2007 - 11:01 PMi think around $450 to $500. not sure, call them, there very nice.
you can drive a REALLY big servo with those..
you can take a standard servo and mount its parts (pot,and board) to a larger motor using a basic power amp.
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Re: Making big-ass servos??
Tue, April 24, 2007 - 6:06 PMHi Steamboat Ed H,
Noticing the original post date, you may have forgotten about it by now?
Most servos are controllablbe both in direction, speed and degree of rotation.
RC servos are simply DC motors which are pulse-width-modulated with current. Located on the shaft of the motor is a small potentiometer which provides control-loop-feedback.
Currently there is an OpenServo group which offers schematics, source code and even will sell you either a fully functional servo or parts there of. These particular servos may be tailored to one's needs and they provide OUTPUT data for external sensoring of a servo's position which is useful in robotic applications.
www.openservo.org/
Good luck.
walt
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Making big-ass servos??
Sat, November 19, 2005 - 5:45 PM
by Steamboat Ed H
--Trying to figure out how to use a large-ish worm-drive windshield wiper motor behave like a servo; i.e. input a signal from a Stamp and have it turn the output shaft only so far. Anyone got a clue? -
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Re: Making big-ass servos??
Thu, April 26, 2007 - 11:39 AM--Thanks; been there, done that. Much good info there and will probably use it first. Have moved on, stuck making money to afford the fun stuff. Current need is for a pile of solenoid valves but that's another tale, heh. -
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Re: Making big-ass servos??
Sun, April 29, 2007 - 10:42 PMHey,
<<pile of solenoid valves>>
You mean like mini-matics or Miniariks? 12Vdc @30 ma pneumatics? If so, I've seen these with manifolds for sale, (~$7 each) at the Black-Hole. Beyond that, why buy used? New ones are less than metal-gear RC servos. I just bought 32 of these servos for a hexa-pod robot (spyder) I'm building right now. Was a BASIC-Micro BASIC Atom, but its a stinky little processor which doesn't work very well, in my opinion. Have done a fair amount of PIC development both professionally and as gadgeteer. AM thinking about moving up to ARM processors, fast, embeddable and lots kewl peripherals + has ability to access outside memory busses and, well not too expensive. How about you?
walt
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Thu, April 26, 2007 - 11:39 AM
Re: Making big-ass servos??
--Thanks; been there, done that. Much good info there and will probably use it first. Have moved on, stuck making money to afford the fun stuff. Current need is for a C but that's another tale, heh. -
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Re: Making big-ass servos??
Fri, May 4, 2007 - 11:55 AM-Have heard of the Black Hole; where is it? Does it have a phone number? I'm working on a Stamp-controlled flame calliope, desktop-sized, with miniature steam whistles. Have a way to go yet but would love to get some solenoid valves that won't puke when passing propane. Heh. -
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Re: Making big-ass servos??
Sat, May 5, 2007 - 6:48 AMSteamboat,
Black Hole:
members.aol.com/blkholela/home/
www.wps.com/about-WPS/pe...le/index.html
Propane? The mini-valves should handle that? Give the vendor a call and ask them if their solenoid valves can control that gas.
What is a "calliope"?
walt
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Fri, May 4, 2007 - 11:55 AM
Re: Making big-ass servos??
-Have heard of the Black Hole; where is it? Does it have a phone number? I'm working on a Stamp-controlled flame calliope, desktop-sized, with miniature steam whistles. Have a way to go yet but would love to get some solenoid valves that won't puke when passing propane. Heh. -
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Re: Making big-ass servos??
Sat, May 5, 2007 - 2:01 PM--Aha! Neat place! They don't have what I need it seems but I've definitely added 'em to my "sources" list. Thanks! Yah, it's beginning to look more and more like what I really need is a grant or a deep-pockets pal to fund my whims, heh.
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Re: Making big-ass servos??
Sat, May 5, 2007 - 2:08 PMRe: what's a calliope? Here are some links for ya:
www.sideshowworld.com/CPipes.gif
www.steamboats.org/gal-bol-calliope.jpg
www.ragtimewest.com/d42r.jpg
www.cincinnati.com/tallstac...e_600.jpg
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Re: Making big-ass servos??
Fri, June 15, 2007 - 7:48 AMIgnoring the probability that $$ is an issue: Wouldn't stepper motors be way better? -
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Re: Making big-ass servos??
Fri, June 15, 2007 - 9:46 PM--Hmmm. Steppers do fun things but they wouldn't be as fast as pneumatics for the original project although I'm tending towards the idea that what I'll have to do, in the end, is videotape the robot in action, then edit it to run at double speed before I can get it to keep up with a fast-tempo tune. As for the second project, the calliope, well I've got to use gasses anyway so I might as well keep it simple and activate whistles with those same gasses. -
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Re: Making big-ass servos??
Mon, June 18, 2007 - 12:47 PMPneumatics have inertia issues. The piston is carrying energy. You have to cancel it or compensate.
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