Re: is freqmode alway's the smoother option?

[Ray Henry <rehenry-at-up.net>]

Jacob

I wonder if what you are seeing at high speed is the granularity of the 
frequency generator.  If your commanded speed was very near the maximum 
possible with freqmod, it would hop between max velocity and the next step 
down which is half frequency, I think.

You could test this theory by setting motor velocity up into the rough speeds 
and then varying it using small changes in feedrate override.  You should 
find some speeds where the motor will be quieter than at other speeds. 

Ray



On Thursday 20 June 2002 09:25, Jacob wrote:
> Hi list,
>
> I use high resolution steppermotors 600 step/rev.
> combined with 1/8 microstepping(total 4800step/rev.
> Therefore I have VERY smooth motion in steppermode,
> low and high speed. In freqmode however, I have smooth
> motion at low speeds and very rough motion at high
> speeds(+/- 10-20Khz). I changed quite intensly PID,
> FF, output_scale and servo calculations cycle_time
> settings after reading the latest manual, but motion
> stay’s rough at high speeds! Only if put P to 0 motion
> becomes smooth at high speeds, however I couldn’t get
> EMC to work correctly at all this way. Could it be
> possible that in my case (high resolution
> steppermotors combined with microstepping and high
> steprates) freqmode isn’t the smoothest option???
>
> PS test have been done with a 1.1Ghz cpu with freqmode
> base task period of 0.000010
>
> Thanks in advance, Jacob
>
>
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