Driving a stepper motor smoothly?

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

Not this one.

Perhaps

As Peter said, you're barking up the wrong tree.

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.

Massimo

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.

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.

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 snipped-for-privacy@eskimo.com Googleproofaddress(account:mzenier provider:eskimo domain:com)

Mark Zenier wrote:

Cool.