one more thing - maximum velocity slider doesn't seem to be obeyed. some of the time it is - but take the 3dchips and have the feedrate set very high. now run the maximum velocity slider to say 10 ipm. when it gets to sections of short line segments - it take off and goes at a much higher feedrate..
sam On Wed, 26 Mar 2014 15:03:50 -0500 sam sokolik <sa...@empirescreen.com> wrote: > here is 50% (1750mm/min) > > http://imagebin.org/301967 > > sam > > > On 03/26/2014 02:49 PM, Robert Ellenberg wrote: > >> One thing I noticed... Lets say we are running that profile at 3500mm/s > >> and it is dipping like this http://imagebin.org/301375 if you slow the > >> feedrate down - the dips get scaled also. I would think at 3200mm/min > >> it would flatten out. :) (probably another nit-pick) > > > > That's a good point, it shouldn't scale proportionally at lower feeds. Does > > that keep happening at slower feeds like 3000 or 2500? If so, it might mean > > that something's being limited that doesn't need to be. > > > > -Rob > > > > > >> sam > >> > >> On 3/26/2014 1:27 PM, Robert Ellenberg wrote: > >>> Hi Sam, > >>> > >>> This acceleration limitation is by design, so that the TP can deal with > >>> tangential and normal acceleration separately. On a circular arc segment, > >>> the acceleration along the path is limited to 0.5 * a_max. Using the > >>> pythagorean theorem, the maximum normal acceleration is: > >>> > >>> sqrt( a_max^2 - (1/2*a_max) ^2 ) = sqrt(3/2) * a_max ~= .866 * a_max > >>> > >>> So, if your maximum axis acceleration is 30 in/sec^2, then the TP only > >>> moves fast enough around the arc to create 25.98 in/sec^2 of normal > >>> acceleration. This way, if you have to speed up or slow down during an > >> arc > >>> move, the total acceleration it won't exceed the machine maximum. > >>> > >>> A good analogy is high-speed cornering with a car on a twisty road. > >> There's > >>> a maximum speed you can go around the corner before the tires slip. > >>> However, if you actually drive at that speed and have to hit the brakes, > >>> you're in trouble :). So, to be safe, you go a little slower so that you > >>> can slow down if need be. > >>> > >>> The good news is, this particular limit on tangential vs. cornering > >>> acceleration gets you pretty close to top speed. For example, on a 0.1" > >>> radius, a max normal acceleration of 26 in/sec^2 gives you a max speed of > >>> sqrt( 26 in/sec^2 * 0.1 in) ~= 1.61 in/sec. Compare that to 30 in/sec^2, > >>> which gives you sqrt( 30 in/sec^2 * 0.1 in) ~= 1.73 in/sec (about 7% > >>> difference). > >>> > >>> I just hard-coded this because it seemed to give me the best speed on my > >>> test runs. Maybe it could be an INI parameter? You could potentially get > >> a > >>> little performance from a program with lots of circular arcs by reducing > >>> the tangential acceleration in favor of normal acceleration. Conversely, > >>> making tangential and normal acceleration both sqrt(2) * a_max might move > >>> more quickly in programs with a lot of detail like stellabee1.ngc. > >>> > >>> -Rob > >>> > >>> On Mon, Mar 24, 2014 at 2:47 PM, sam sokolik <sa...@empirescreen.com> > >> wrote: > >>>> I have a question about the acceleration limits. (and I might be > >>>> nit-picking here) But I have been goofing around with the > >>>> trochoidal.ngc file from http://www.vagrearg.org/gcmc/trochoidal.ngc.gz > >>>> > >>>> I see when I push the velocity up to 3500mm/min - the peak velocity > >>>> starts to dip (this is with 30in/s^2 acc) > >>>> > >>>> http://imagebin.org/301375 > >>>> > >>>> but you can see that the acc doesn't get to 30in/s^2 - it seems to peak > >>>> at about 26 or so. I did play around with the gap freq in the ini file > >>>> (setting it to my servo period of 1000) and it may have helped just a > >>>> little bit. > >>>> > >>>> http://imagebin.org/301376 (acc peaks just a little higher) > >>>> > >>>> is this just a limitation of the whole system? It it still way way > >>>> better than the current tp - but was wondering what was causing this. > >>>> > >>>> sam > >>>> > >>>> > >> ------------------------------------------------------------------------------ > >>> Learn Graph Databases - Download FREE O'Reilly Book > >>> "Graph Databases" is the definitive new guide to graph databases and > >> their > >>> applications. Written by three acclaimed leaders in the field, > >>> this first edition is now available. Download your free book today! > >>> http://p.sf.net/sfu/13534_NeoTech > >>> _______________________________________________ > >>> Emc-developers mailing list > >>> Emc-developers@lists.sourceforge.net > >>> https://lists.sourceforge.net/lists/listinfo/emc-developers > >>> > >>> > >> > >> > >> ------------------------------------------------------------------------------ > >> Learn Graph Databases - Download FREE O'Reilly Book > >> "Graph Databases" is the definitive new guide to graph databases and their > >> applications. Written by three acclaimed leaders in the field, > >> this first edition is now available. Download your free book today! > >> http://p.sf.net/sfu/13534_NeoTech > >> _______________________________________________ > >> Emc-developers mailing list > >> Emc-developers@lists.sourceforge.net > >> https://lists.sourceforge.net/lists/listinfo/emc-developers > >> > > ------------------------------------------------------------------------------ > > Learn Graph Databases - Download FREE O'Reilly Book > > "Graph Databases" is the definitive new guide to graph databases and their > > applications. Written by three acclaimed leaders in the field, > > this first edition is now available. Download your free book today! > > http://p.sf.net/sfu/13534_NeoTech > > _______________________________________________ > > Emc-developers mailing list > > Emc-developers@lists.sourceforge.net > > https://lists.sourceforge.net/lists/listinfo/emc-developers > > > > > ------------------------------------------------------------------------------ > Learn Graph Databases - Download FREE O'Reilly Book > "Graph Databases" is the definitive new guide to graph databases and their > applications. Written by three acclaimed leaders in the field, > this first edition is now available. Download your free book today! > http://p.sf.net/sfu/13534_NeoTech > _______________________________________________ > Emc-developers mailing list > Emc-developers@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-developers ------------------------------------------------------------------------------ _______________________________________________ Emc-developers mailing list Emc-developers@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-developers
