Frank Tkalcevic wrote:
>> Hm, the hm2 encoder velocity output is supposed to be really smooth. 
>> I'll double check it tonight.  Any chance you can supply a 
>> halscope trace of it looking bad on your machine?
> 
> I'm using 2.3.
> 
> Here's a trace of the commanded velocity (after going through limit3),
> encoder velocity (*60) and the lowpass output.
> 
> http://www.franksworkshop.com.au/img_bin/Velocity.png
> 
> The encoder scale is 12000; 12000 pulses representing 1 revolution.  The
> encoder velocity output is then multiplied by 60 to give rpm.  The graph
> shows acceleration to 20rpm and stop.

Wow, that looks terrible.

It looks like the command starts moving, then it takes a full 200 ms 
before the encoder responds at all, and it immediately overshoots by a 
factor of two.

This is a servo-spindle, right?  If you disable the PID and PWM, and 
turn the spindle by hand, does it look any better?  I know it's hard to 
say what the real velocity should be in that case, but this test would 
remove the PID tuning question.

I did all my encoder velocity testing using the stepgen in quadrature 
mode, and i'm pretty sure it looked much better.


-- 
Sebastian Kuzminsky
    you press what you hope is the right switch, and you
                   - jump, becoming light

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