Re: is freqmode alway's the smoother option?

[Jacob Kranendonk <j_kranendonk-at-yahoo.com>]

Hi Ray, Paul, list,

Ater testing I think the theory seems to be right.
Granulation of the pulsgenerator could very well be
the problem. If I increase the base_task period from
0.000010 to 0.000015 the problem becomes much worse!
Does this prove the theory as well??? And at last, if
this seems to be the case what can be done about it?
Could a faster cpu or the changing of EMC settings
solve this problem??? 

--- Ray Henry <rehenry-at-up.net> wrote:
> 
> 
> 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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