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Topic: Can I use a Step Motor as a Servo ? (Read 1 time) previous topic - next topic

weldsmith


Robin,

I was not thinking in terms of powering it down. However an incremental encoder with a Z channel could perform similarly. Use the Z channel to reference the motor and then move to your desired position.  If you had just A and B channels a hard stop would work as well. Use the hard stop as the reference.

Dave

David Smith

Robin2

This is all a bit pointless as we seem to have lost the OP.

Just out of curiosity what is "an incremental encoder with a Z channel"? Do you have a link to a typical datasheet?

...R
Two or three hours spent thinking and reading documentation solves most programming problems.

weldsmith



This is generic, This Quadrature incremental encoder is the same as most that you will see. I use this type because you can use the Z channel to reference a motors angle. US digital is one of the cheaper US made encoders. However, I try to buy new surplus. I have found 10 of them for 15.00 each.


Dave.



http://ww1.microchip.com/downloads/en/DeviceDoc/70208C.pdf

David Smith

Robin2

As far as I can see the encoder in that datasheet has an extra slot once per revolution that can be use to re-establish the position. But that does not function at all in the same way as the position potentiometer in a hobby servo.

Unless the encoder is rotated far enough (in the worst case, almost 360 degrees) the extra slot won't produce a pulse.

...R
Two or three hours spent thinking and reading documentation solves most programming problems.

weldsmith

#19
Jul 02, 2017, 04:58 pm Last Edit: Jul 02, 2017, 05:00 pm by weldsmith


That is correct.

I did mention that a stepper can be programmed similarly to a hobby servo. In one of my applications I position the reference channel in a convenient location so the motor is where I want it after it references. (maybe like 90 deg. on a servo) When it finds its reference I now know where it is. Now I can tell it to go to the angle I want it to.

Dave

David Smith

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