On 8 July 2013 05:21, John Morris <j...@zultron.com> wrote: > Also, > spindle acceleration and reversal control is not as precise as other > motion components. Nothing we can do about the uncontrollable!
My feeling is that spindle reversal is very nearly a zero-jerk motion, so isn't a problem. The jerk is at spindle start and when the spindle changes from constant speed to begin the deceleration phase, and the transition from acceleration to constant-speed. Given that finite-jerk is a "nice to have" and that (nearly) every LinuxCNC installation in the field is running happily with unbounded jerk, I think it makes sense not to try to limit jerk in coordinated moves. I have tried writing a finite-jerk motion planner for a laser raster system, and it is hard to even hit a known destination position without calculating ahead in time. As spindle-coordinated motion in inherently a reactive rather than predictive mode the choice is between following the required path or limiting the jerk. (noting that following the correct path does not necessarily exceed jerk limits). -- atp If you can't fix it, you don't own it. http://www.ifixit.com/Manifesto ------------------------------------------------------------------------------ This SF.net email is sponsored by Windows: Build for Windows Store. http://p.sf.net/sfu/windows-dev2dev _______________________________________________ Emc-developers mailing list Emc-developers@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-developers
