>
> I have been playing with it for a bit now and am wondering about a few
> things...
>
> Could there be a e-offset error? (difference between where the axis is and
> the o-ffset input)
>
> Can the e-offset ratio be disabled or changed from within linuxcnc? I
> don't see an ini. hal pin for it. The reason is - for doing some of the
> fancy spindle synced motion stuff I need to apply most of the acc/vel to
> e-offset. This makes for very slow normal motion. In this situation - I
> only need the high ratio during polygon motion
>
> Is this making sense?
>
I was thinking the same when I did my tests. The problem I see with the
error tracking is that there are two factors to consider. First there is
the phase displacement error between the e-offset input and the actual
offsetted axis position. And second there's an amplitude attenuation
whenever the axis can't keep up with the desired e-offset. I guess
the error should be splitted in to X and Y coordinates but I'm not sure. I
mean this is not like a normal f-error like the one experimented with a
normal axis where position magnitude is a considered a scalar (I mean the
commanded and actual position of an axis).
I don't know if there is an easy way to compute a near exact error but
that's what I was trying to figure out to better tune my camshafts for lobe
turning. In reality what I need is simple, I just need to detect the phase
displacement as the spindle revs. I can't do anything about the amplitude
loss, and since my test was to rough cut the cams I can live with a little
bit of lift (amplitude) loss. For me, this is harder than what it looks
like and the best way I found to solve this is to really overkill the speed
and acceleration of the axis to be e-offsetted. Off course I'm far from
being a LCNC/maths/programmer expert but that's roughly what I see.
Thanks for sharing your progress Sam.
El lun., 5 oct. 2020 a las 18:52, Rod Webster () escribió:
> Sam, the pins are listed here
> http://linuxcnc.org/docs/2.8/html/motion/external-offsets.html
> If your offset motion is mutually exclusive to normal motion, you can trick
> the system by doubling the axis and velocity and acceleration and use a
> ratio of 0.5. This gives you full velocity and acceleration to eoffsets and
> how we manage the Z axis with Plasma as normal Z axis motion is not used at
> all when eoffsets are active.
>
> Rod Webster
> *1300 896 832*
> +61 435 765 611
> VMN®
> www.vmn.com.au
>
>
>
> On Tue, 6 Oct 2020 at 03:08, Sam Sokolik wrote:
>
> > I have been playing with it for a bit now and am wondering about a few
> > things...
> >
> > Could there be a e-offset error? (difference between where the axis is
> and
> > the o-ffset input)
> >
> > Can the e-offset ratio be disabled or changed from within linuxcnc? I
> > don't see an ini. hal pin for it. The reason is - for doing some of the
> > fancy spindle synced motion stuff I need to apply most of the acc/vel to
> > e-offset. This makes for very slow normal motion. In this situation - I
> > only need the high ratio during polygon motion
> >
> > Is this making sense?
> >
> > thanks!
> > sam
> >
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> >
>
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