I think you are probably right.  Running the simulation at 100x was much more 
accurate than 1000x.  Tomorrow I'll have to play with the servo thread speed 
some and see if and how much improvement I can find.  But not sure how much 
improvement will be possible in a sim config on a VM.

----- Original Message -----
From: "Stephen Dubovsky" <smdubov...@gmail.com>
To: "Enhanced Machine Controller (EMC)" <emc-users@lists.sourceforge.net>
Sent: Thursday, October 13, 2016 3:52:42 PM
Subject: Re: [Emc-users] Hacking a sim runtime mode

I think the error of this approach (using N times higher accel/vel) is
coming from the piecewise linear approximations of the curves going bad.
If you try to follow a curve N times faster, then there are N times fewer
samples along that curve for a fixed time sampling period.  That introduces
errors.  There may be others but thats at least part of it.  Its the same
problem w/ discrete time vs continuous time systems.  There is divergence
between the solutions as the sampling rate goes down.


On Thu, Oct 13, 2016 at 3:08 PM, Todd Zuercher <zuerc...@embarqmail.com>
wrote:

> I was just working at this a little bit.   The first thing I did was to
> modify time.comp, to make a new sim_time.comp.  The sim_time.comp is
> basically just the same as the regular timer component with an input pin
> added to scale the time to what ever factor you speed up the simulation
> run.  Then I made a dummy config of one of our machines with all the
> velocities and accelerations increased by 1000x, and test ran a few things,
> the results were not quite as good as I had hoped, but were way better than
> the old estimations. Is it possible that some of the inaccuracy came from
> the fact I was running it in a VM?
>
> The timer scaling pin was a really simple mod, would there be any interest
> in adding that to the regular release?
>
> ----- Original Message -----
> From: dan...@austin.rr.com
> To: "Enhanced Machine Controller (EMC)" <emc-users@lists.sourceforge.net>
> Sent: Thursday, October 13, 2016 2:24:53 PM
> Subject: Re: [Emc-users] Hacking a sim runtime mode
>
>
> ---- Chris Albertson <albertson.ch...@gmail.com> wrote:
> > On Thu, Oct 13, 2016 at 9:00 AM, Peter C. Wallace <p...@mesanet.com>
> wrote:
> > > On Thu, 13 Oct 2016, dan...@austin.rr.com wrote:
> > >
> >
> > > I just tried a real time Mesa Ethernet config with maxvel = 120000 IPM
> (2000
> > > IPS = 20 MHz step rate at present 10000 steps/In scaling) and maxaccel
> 20000
> > > IPS/S (52 Gs) with a 1 KHz servo thread, and it works fine (Peak
> following
> > > errors in the 1-2 mill region)
> >
> > The problem to be solved is getting an estimate of the time required
> > to complete a job.   Does the above do this accurately?
>
> Yeah I want to know this.  I can run a job for real vs "fast sim" and
> compare.  One prob is the cycle time only goes down to seconds AFAIK.  If
> it's 100x then that's over a minute and a half it could be wrong, but
> that's still good enough as long as it's not estimating a very short job.
>
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