Comments on: SinCos encoder support

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By: Walter

Walter — Thu, 30 Apr 2015 19:16:02 +0000

Thank you! I was hoping to use motors with sin/cos feedback.

By: jan

jan — Wed, 29 Apr 2015 07:56:00 +0000

Way cool! Can’t wait for my units to get here….

By: Tero

Tero — Tue, 28 Apr 2015 10:34:17 +0000

The sampling algorithm used tolerates very high speeds without even falling back to digital mode. In theory is designed to tolerate at least 500 kHz count rate (but probably over 1 MHz).

In my tests I could not reach the limit speed with 1024 cycle encoder and 3000 rpm motor.

Quickly calculated that this 500 kHz would equal 2.5 m/s with 20 µm cycles.

By: jan beck

jan beck — Tue, 28 Apr 2015 09:24:21 +0000

Awesome. At what rate is the position calculated and what is the maximum sin/cos frequency before we miss steps? Linear motors can go awfully fast and that renishaw scale has a cycle length of 20 um…

By: Tero

Tero — Mon, 27 Apr 2015 10:50:45 +0000

In our test there was no problem with 1 Vpp signal. No noise seen with 256X mode, but this test was done only with single motor. Multiple motors may increase EMI noise but probably not a high concern.

By: jan

jan — Sun, 26 Apr 2015 21:27:38 +0000

I have been looking forward to this as I have a linear motor with sin/cos feedback. But I have a question:
Since the sin/cos signal is only 1 v p-p do you need some sort of ungodly shielding to avoid noise? With a division of 256, we get about 4 mV steps. I know these are differential signals, but that is still an awfully small amount. Can you give some insight of how that works?