Newsgroups: comp.robotics
Path: cantaloupe.srv.cs.cmu.edu!rochester!udel!gatech!howland.reston.ans.net!news.sprintlink.net!noc.netcom.net!netcom.com!nagle
From: nagle@netcom.com (John Nagle)
Subject: Re: Actuator to drive periodic motion at 4 cycles/sec?
Message-ID: <nagleD7C25z.C5u@netcom.com>
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References: <3mjtlp$bos@zip.eecs.umich.edu> <3mv37h$cl3@zip.eecs.umich.edu>
Date: Thu, 20 Apr 1995 12:17:58 GMT
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baillod@quip.eecs.umich.edu (Brad Baillod) writes:
>In article <3mjtlp$bos@zip.eecs.umich.edu>,
>Brad Baillod <baillod@quip.eecs.umich.edu> wrote:
>>I'm planning a robotic implementation that will need
>>to drive a small weight up and down at a max of about 240 cycles
>>per minute (four up/down cycles per second).  Is that
>>too fast for actuators available cheaply today?  I

>An added detail: the length of motion is about 7 inches max--
>that is, 7 inches from the bottom of the down swing to the
>top of the up swing.

     How massive a load?  How much control do you need?

     The expensive answer is an Aura linear actuator, which can do the
job but will cost a few thousand.  These provide precise control,
high speed, are available for a wide range of loads, and are overly
expensive because they aren't a volume product.  Sizes up to multi-ton
loads and 1 meter strokes are available.  

     If compressed air is available, consider air cylinders.
Solenoid-actuated air valves are cheap.  True precision position
control of air cylinders is possible, but the valves and control
gear for that cost over $1000.  (Dynamic Valves, Inc, Palo Alto,CA)

     For light loads, you might consider a stepper driving a rack
and pinion or windlass.  Tear apart an old floppy drive to see
how that's done.  Consider plastic chain and toothed belts, as well.
The Berg catalog (see the FAQ) is useful for mechanical parts.

     Incidentally, for the speed and range you need, you have to get
serious about bearings and lubrication, or the thing won't last long.

					John Nagle
