EVLSERVO1 High Resolution Encoder

[Isaac1]

Hello,

I am using the EVLSERVO1 board with a differential quadrature encoder (A and B phases). The encoder has a resolution of 4096 pulses per revolution, and I am observing issues when the motor speed exceeds a few hundred RPM.

Specifically, the system becomes unstable above ~500 RPM. The motor fails to spin reliably, and the encoder appears to stop providing meaningful feedback(past 500 rpm, the encoder value stays the same about). However, when I probe the differential signal (A+ minus A−), the waveform looks clean on the scope.

Is this behavior expected due to the encoder being considered "high resolution"? Would performing the rework suggested for high-resolution encoders (replacing R81 and R82 with 330 Ω...) help resolve this issue?

I am unsure where the resolution or frequency cutoff is that necessitates this rework, and would appreciate any guidance.

Thank you!

 

[AScha.3]

Hi,

so with your high resolution set the r81/82 to 330 , then check again.

(So less load on the encoder data lines, bigger signal, better for high resol. frequencies ;)

[Isaac1]

Before I do the suggested rework, I wanted to clarify what is generally considered a high-resolution encoder? I am not sure where the cutoff is, but is 4096 pulses/rev considered high or low resolution?

Thanks!

[AScha.3 · Accepted solution]

There is no "cutoff" - its more like a "taste group".

So our new friend says:  whats low res.enc. ?

examples: Rotary encoders with 100-500 PPR or linear encoders with resolutions above 50 um.

and > 1000 PPR is then high resolution.

e.g. the encoders for speed checking have typical 16 .. 64 PPR (we use in machines rotating at 50...2000 rpm).

[Isaac1]

Thanks