Newsgroups: comp.robotics
Path: brunix!uunet!munnari.oz.au!uniwa!cujo!cc.curtin.edu.au!syawanar
From: syawanar@cc.curtin.edu.au
Subject: Re: Trouble with stepper motor
Message-ID: <1992Sep2.144538.1@cc.curtin.edu.au>
Lines: 32
Sender: news@cujo.curtin.edu.au (News Manager)
Organization: Curtin University of Technology
References: <1992Aug14.214916.4173@colorado.edu>
Date: Wed, 2 Sep 1992 05:45:38 GMT


> I've got a 4-phase stepper motor that I'm trying to control, by
> sending it the required sequence of 4-bit patterns (1001, 1010, 0110,
> 0101, repeat), and the motor runs for 2-6 seconds (hundreds of steps)
> and then it gets confused and just starts wiggling.
> 
> Has anyone else had this problem?  
> 
> The motor behaves as it would behave if it had gotten out of
> synchronization with the step commands, but I can't imagine why this
> would suddenly happen after hundreds of successful steps.
> 

It may not be the motor at all but the circuitry. After hundreds of steps,
it may have been possible for propagation delay to cause a major loss
of syncrhrocity. (You did mention that it does hundreds of steps in just
a few seconds) so this may well be the problem. Try analyzing the logic 
output when the trouble starts.

Possible solutions would be to use faster chips or simplify the circuit
to less states.

Hope this was of help.

-Naveen-

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