On Mon, Dec 16, 2013 at 11:47 AM, Charles Steinkuehler < char...@steinkuehler.net> wrote:
> Hmm...I dug into this a bit, and it turns out the Arduino Marlin > firmware doesn't really support true jerk limiting. What they call jerk > is actually the maximum instantaneous allowable change in combined XY > velocity (ie: going around corners). I'm pretty sure the "jerk" setting > in Marlin can be approximated (likely with better overall results) using > G64 with a tolerance. > > Descriptions of Arduino/Marlin "jerk" limiting: > > http://forums.reprap.org/read.php?146,190628,191971#msg-191971 > > https://github.com/ErikZalm/Marlin/issues/305#issuecomment-10318472 > That's an interesting use of the term "jerk", certainly. The circular-arc blend method limits cornering acceleration as well, so you don't need a separate spec for that. If they're using a trapezoidal velocity profile, there will still be large kinematic jerks, though. Whether you need jerk-limiting will probably depend on how stiff your machine is relative to the max acceleration, and how much damping your structure and joints provide. It would certainly be useful feedback for me if you tried out the circular arc branch (linked below if you're curious). https://github.com/robEllenberg/linuxcnc-mirror/tree/circular-blend-arc-alpha One issue I can see with running a 3D printer is that A-axis moves have to fall back to stock blends (i.e. parabolic). It's something I'd like to address in a future release, though there's more work to be done on that front. -Rob ------------------------------------------------------------------------------ Rapidly troubleshoot problems before they affect your business. Most IT organizations don't have a clear picture of how application performance affects their revenue. With AppDynamics, you get 100% visibility into your Java,.NET, & PHP application. Start your 15-day FREE TRIAL of AppDynamics Pro! http://pubads.g.doubleclick.net/gampad/clk?id=84349831&iu=/4140/ostg.clktrk _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
