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Topic: Detecting "Physical" Resistance from Stepper Motor (Read 3393 times) previous topic - next topic

sbright33

Just hook a stepper motor winding thru a 10k resistor to Analog input 0.  Couldn't be simpler.  Try my code, or write your own to view that value while it's spinning.
If you fall... I'll be there for you!
-Floor

Skype Brighteyes3333
(262) 696-9619

PeterH

So you're measuring current through a winding, then? I suppose that if you average it this gives you an indication of back EMF and hence speed. I don't see how it gives you any information about torque, but if the demanded speed is constant I can see how it would give you an indication of slip, especially if you only need to differentiate between the 0% and 100% cases.
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sbright33

No, I'm measuring voltage.  The resistor is only there to protect the Uno, it works without it.  I don't know how it works.  It just does!  Try it!  It does not only measure slip.  It measures a change in TORQUE when you lightly hold or release the shaft while it is spinning at a constant speed.  It does this even before there is any slip.  It is so sensitive, with the proper code, you can just barely touch a 1" radius disc mounted on the shaft which already has a constant torque applied.  It will detect this touch.  It takes a small bit of force to detect the torque of touching a thin shaft because the radius is much smaller.  Keep in mind there is a ULN2003 driver wired up the normal way.  The timing of the measurement may also be important, see my code. 
If you fall... I'll be there for you!
-Floor

Skype Brighteyes3333
(262) 696-9619

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