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Driving a stepper motor smoothly?

Discussion in 'Electronic Equipment' started by Paul Ciszek, Dec 13, 2007.

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  1. Paul Ciszek

    Paul Ciszek Guest

    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.
  2. PeterD

    PeterD Guest

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

    JeffM Guest

    Not this one.
    As Peter said, you're barking up the wrong tree.
    **Discrete steps** is the nature of the device.
  4. Max65

    Max65 Guest

    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:

    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.

  5. David Wright

    David Wright Guest

    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.
  6. 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.
  7. Mark Zenier

    Mark Zenier Guest

    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
    Googleproofaddress(account:mzenier provider:eskimo domain:com)
  8. JeffM

    JeffM Guest

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