motor as encoder

A project log for anaQuad!

Reliably increase your quadrature-encoder's resolution using an ADC (or a bunch of comparators?)

eric-hertzEric Hertz 09/14/2018 at 03:411 Comment


#Motor as Encoder 

Use a BLDC motor as an encoder. Almost *Exactly* as I'd imagined. Combine this with anaQuad, and yer all set!

Note that anaQuad *also* works with two sources that are 120 degrees out of phase, so only two windings of the three in a typical BLDC should be necessary. Also, his technique could probably also be applied to stepper motors.

I dunno how i never seem to come up with this simple concept, myself...

"how can I measure capacitance? Drive with an AC signal, measure phase/magnitude..."

Had to learn this one by example... Simple capacitive touch switches charge the cap, then measure the time it takes to discharge...

Friggin' simple method to apply multiple pushbuttons on a single pin is exactly the same, tie them to different resistor values, charge a cap, measure the discharge time, simple ADC. Bam. I even have a well-developed project based on that (anaButtons, as I recall).

No phase/mag necessary. So, why, then, couldn't I come up with the same for inductors? Duh.

Nice goin' @besenyeim!

I'mma linking this one here so's I can come back to it when the time is right-er.


besenyeim wrote 09/14/2018 at 14:01 point

I'm glad you like it.

I think you're right, but the higher resolution is not so straightforward as it seems. This ( ) shows that it is possible. But it is not sinusoidal and, as I show in today's log entry, EMF must be considered.

Stepper motors? Theoretically yes, in practice... I guess it's hard. I think the mentioned EMF has stronger effect.

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