Driving a stepper motor smoothly?

[Paul Ciszek]

First of all, what is the appropriate newsgroup for questions about
stepper motors? On with the actual question:

Is there a reasonably priced option for driving stepper motors
smoothly, i.e., not having them stop and start every 1.8 (or 0.9)
degrees? I have some 200 step/rev motors that I would like to drive
at speeds ranging from 0.1 to 4 RPM in one application and 0.4 to 16
RPM in another. I would prefer a system that has already been
designed by someone who knows what they are doing, though I would not
mind doing some kit assembly if it came to that.

 

[PeterD]

First of all, what is the appropriate newsgroup for questions about
stepper motors? On with the actual question:

Is there a reasonably priced option for driving stepper motors
smoothly, i.e., not having them stop and start every 1.8 (or 0.9)
degrees? I have some 200 step/rev motors that I would like to drive
at speeds ranging from 0.1 to 4 RPM in one application and 0.4 to 16
RPM in another. I would prefer a system that has already been
designed by someone who knows what they are doing, though I would not
mind doing some kit assembly if it came to that.

That is why they are called 'stepper' motors... If you want smooth
then use a standard motor and a gear box.

 

[JeffM]

First of all, what is the appropriate newsgroup

Not this one.
http://groups.google.com/group/sci....ready-available-solutions+The.equipment.group

for questions about stepper motors?
Perhaps
http://groups.google.com/groups/dir?lnk=srgmt&q=comp.robotics

[...]not having them stop and start every 1.8 (or 0.9) degrees?

As Peter said, you're barking up the wrong tree.
**Discrete steps** is the nature of the device.
http://www.google.com/images?q=stepper-motor+tutorial

 

[Max65]

I agree with Peter and Jeff, if you need a smooth rotation you are on
the wrong way.
Anyways, you can double or multiply by four the steps per revolution
driving the motor with the half steps technique or the half-excitation
state method.

See the link below:

http://electronicdesign.com/Articles/ArticleID/12619/Index.cfm?action=SiteMap

There, you can find a little complex schematics too (I guess it may be
done easier by a microcontroller instead).

Remember that the real problem with step motors in half and quarter
steps driving, is that the torque is hard to sustain in the gaps
between the two mechanical steps.

Have a great day.

Massimo

 

[David Wright]

I did design a stepper motor driver for a torque loading machine. The
voltage optical isolators were alread on the machine. It merely used a 555
variable duty cycle pulse generator triggered by a computer I/O line. The
mechanical loader had a gearbox and screwdrive when I inserted it into the
$100K system. It was just a small circuit board with a few wires to connect
to the unit.

 

[Anthony Fremont]

First of all, what is the appropriate newsgroup for questions about
stepper motors? On with the actual question:

Is there a reasonably priced option for driving stepper motors
smoothly, i.e., not having them stop and start every 1.8 (or 0.9)
degrees? I have some 200 step/rev motors that I would like to drive
at speeds ranging from 0.1 to 4 RPM in one application and 0.4 to 16
RPM in another. I would prefer a system that has already been
designed by someone who knows what they are doing, though I would not
mind doing some kit assembly if it came to that.

Like most said, a stepper is "jerky" by nature. OTOH, since you have very
small RPM requirements, you could probably run the stepper very fast but
using enough gear reduction so that the steps are too small to be of
concern. A worm gear on the shaft of the stepper engaging a largeish gear
would give good results IMO. Perhaps you could hack up something from an
inkjet printer.

 

[Mark Zenier]

First of all, what is the appropriate newsgroup for questions about
stepper motors? On with the actual question:

Is there a reasonably priced option for driving stepper motors
smoothly, i.e., not having them stop and start every 1.8 (or 0.9)
degrees? I have some 200 step/rev motors that I would like to drive
at speeds ranging from 0.1 to 4 RPM in one application and 0.4 to 16
RPM in another. I would prefer a system that has already been
designed by someone who knows what they are doing, though I would not
mind doing some kit assembly if it came to that.

The buzzword is "Microstepping", where you replace the binary drive
with sinusoidal currents. You can get resolution around 100 times
finer than the step size, but accuracy depends on having waveforms
that match the motor characteristics.

Mark Zenier [email protected]
Googleproofaddress(account:mzenier provider:eskimo domain:com)

 

[JeffM]

[...]driving stepper motors smoothly,
i.e., not having them stop and start every 1.8 (or 0.9) degrees?

The buzzword is "Microstepping",

Cool.
http://www.google.com/search?q=cach...ly-move+compelling.reasons+inc+*-*-*-Problems