Stepper motor pulse width question

Building a controller to output pulses to steppermotor driver. What is
the recommended pulse width output? Is there a standard ( one length
fix all) or is there other factors I need to consider? Such as the
driver itself or what is specified in the motor datasheet? I see in
the motor datasheet headings Resistance, Inductance. Is this something
I need to consider?
I'd appreciate any advice or opinions on this or where I might find
info on this..
Thanks bill Start a New Thread

There are many factors to consider. There is a maximum pulses/second
mentioned somewhere on the data sheet and of course, that should not
be exceeded. There is an acceleration and deceleration curve than
also needs to be calculated. There is a rated torque associated
with the stepper that needs to be taken into account. Exceeding
the torque rating of the stepper while the stepper is accelerating
(or decelerating the mechanical load associated with it could
cause the stepper to miss a step, rendering the accuracy of you
stepper useless.

Since this is the pic board, I'm assuming that you will be using a
pic for your controller (I did). Might I suggest that you include
in your design a method of using the data eeprom in the pic (if
your chosen pic has one) for the setting variables in them through
some means (like rs232) to adjust parameters.

Most commercial stepper controllers (at least the little stepper
controllers) have some sort of velocity profile, usually a
trapizoidal one for their operation. The step rate ramps up from
0 in a linear fashion until a limit of pulses/second has been
reached, then the pulses/second remains constant until near the
end of travel has been reached where a deceleration (decrease) in
the number of pulses/second occurs, landing the stepper at it's
target number of steps with zero pulses/second, again in a linear
fashion.

There is a very interesting web site concerning stepper motors
and their designs at:

http://www.cs.uiowa.edu/~jones/step/

I am in no way affiliated with him or the THE UNIVERSITY OF IOWA
just ran across his site while researching bipolar stepper motors.

In that link you will find hints on the electrical design goals
to determine the voltage current relationship to the coils of
the stepper that you are dealing with.

Further, you might want to consider looking at some of the
commercial stepper controllers on the internet. Go to one of the
bigger electronics parts houses and look at their boards ( on the
internet) for stepper controller boards. Nowadays with the internet
many times they will include the data sheets for the devices right
there for downloading. Talk about a free gift! A review of a
couple of these boards will be a great guide for developing your own.

Hope these ideas prove usefull and I wish you the very best with
your efforts!

Cheers,

Rich S.

--- In p..., "wdavis364" wrote:
>
> Building a controller to output pulses to steppermotor driver. What is
> the recommended pulse width output? Is there a standard ( one length
> fix all) or is there other factors I need to consider? Such as the
> driver itself or what is specified in the motor datasheet? I see in
> the motor datasheet headings Resistance, Inductance. Is this something
> I need to consider?
> I'd appreciate any advice or opinions on this or where I might find
> info on this..
> Thanks bill
> Start a New Thread

Thanks Rich, great response. I'll check the web site and others and see how it goes.
thanks
bill

----- Original Message -----
From: rj_satterlee
To: p...
Sent: Wednesday, January 24, 2007 9:58 AM
Subject: [piclist] Re: Stepper motor pulse width question
There are many factors to consider. There is a maximum pulses/second
mentioned somewhere on the data sheet and of course, that should not
be exceeded. There is an acceleration and deceleration curve than
also needs to be calculated. There is a rated torque associated
with the stepper that needs to be taken into account. Exceeding
the torque rating of the stepper while the stepper is accelerating
(or decelerating the mechanical load associated with it could
cause the stepper to miss a step, rendering the accuracy of you
stepper useless.

Since this is the pic board, I'm assuming that you will be using a
pic for your controller (I did). Might I suggest that you include
in your design a method of using the data eeprom in the pic (if
your chosen pic has one) for the setting variables in them through
some means (like rs232) to adjust parameters.

Most commercial stepper controllers (at least the little stepper
controllers) have some sort of velocity profile, usually a
trapizoidal one for their operation. The step rate ramps up from
0 in a linear fashion until a limit of pulses/second has been
reached, then the pulses/second remains constant until near the
end of travel has been reached where a deceleration (decrease) in
the number of pulses/second occurs, landing the stepper at it's
target number of steps with zero pulses/second, again in a linear
fashion.

There is a very interesting web site concerning stepper motors
and their designs at:

http://www.cs.uiowa.edu/~jones/step/

I am in no way affiliated with him or the THE UNIVERSITY OF IOWA
just ran across his site while researching bipolar stepper motors.

In that link you will find hints on the electrical design goals
to determine the voltage current relationship to the coils of
the stepper that you are dealing with.

Further, you might want to consider looking at some of the
commercial stepper controllers on the internet. Go to one of the
bigger electronics parts houses and look at their boards ( on the
internet) for stepper controller boards. Nowadays with the internet
many times they will include the data sheets for the devices right
there for downloading. Talk about a free gift! A review of a
couple of these boards will be a great guide for developing your own.

Hope these ideas prove usefull and I wish you the very best with
your efforts!

Cheers,

Rich S.

--- In p..., "wdavis364" wrote:
>
> Building a controller to output pulses to steppermotor driver. What is
> the recommended pulse width output? Is there a standard ( one length
> fix all) or is there other factors I need to consider? Such as the
> driver itself or what is specified in the motor datasheet? I see in
> the motor datasheet headings Resistance, Inductance. Is this something
> I need to consider?
> I'd appreciate any advice or opinions on this or where I might find
> info on this..
> Thanks bill
> Start a New Thread