Newsgroups: comp.robotics
Path: cantaloupe.srv.cs.cmu.edu!rochester!udel!gatech!howland.reston.ans.net!ix.netcom.com!netcom.com!nagle
From: nagle@netcom.com (John Nagle)
Subject: Re: microstepping (?)
Message-ID: <nagleD2sLAL.F1q@netcom.com>
Organization: NETCOM On-line Communication Services (408 261-4700 guest)
References: <3f5d8u$duo@news.tuwien.ac.at> <3fknjk$91d@knot.queensu.ca> <D2qpK1.Bo4@serval.net.wsu.edu>
Date: Sun, 22 Jan 1995 05:44:45 GMT
Lines: 29

a0014246@unicorn.it.wsu.edu (mark fuller) writes:
>Steve Gillen (steve@phy-server) wrote:
>: Bernhard Greissing (berni@nugat) wrote:
>: : Hi there!
>: : There's a method for controling stepper-motors called 'microstepping'.
>: : Is there anybody who can tell me how this works and 
>: : about the benefits of this method.

>: Yes... Microstepping does involve varying the current in two adjacent 
><deleted>
>:   My only worry about using a stepper motor (and maybe even syncros)
>: at low speed or stopped is the shape of the poles on the windings and
>: armature.  I suspect (ok... Guess) that the angular position is not linear

      If you want that kind of precise position control, you may as well
go with servomotors, rather than steppers.  Steppers are open-loop,
remember, and when microstepping, you're really controlling force, not
position.  Microstepping is great for disk head positioning, where the
frictional forces are very, very low, but not really appropriate for
many robotics applications.

      For simple position control applications, you might just gear down
the stepper until you don't need microstepping.  Ordinary stepper
control is really simple.  

      Somebody should write a FAQ item on low-cost servomotor control.
It's not that hard, but you need to know which chips to buy.

					John Nagle
