<snip-snap> > All: > > I am a total ignoramus when it comes to the trajectory planning and > motion control aspects of LinuxCNC. From my seat in the peanut gallery, > it seems there is a divide between those who believe we have a proper > set of algorithms properly implemented that have been tested > successfully and those who believe this reported behavior must mean > either the implementation is deficient or the algorithms imperfect (or > both!). So far, the two groups of discussants seem to have been talking > past each other, both in the 2011 exchanges and now. > > The following questions are simply my noodling and not any attempt to > state a personal position: > > Do Daniel's two files constitute a valid test? That is to say, should > one expect substantially the same behavior when each is executed? > > If the answer is yes, then why isn't it the behavior the same? If the > answer is no, then why should it not be the same behavior? > > Once the dust has settled I hope the subject can be explained more fully > in the LinuxCNC documentation. > > For some time we have advertised "constant velocity control" as a > feature of EMC/LinuxCNC (usually in an "About..." section) but try > searching on "constant velocity". Two technically meaningful pages on > the Wiki respond to this search term: > http://wiki.linuxcnc.org/emcinfo.pl%3FTrapezoidal_Velocity_Profile_Trajectory_Planner > > and http://wiki.linuxcnc.org/emcinfo.pl%3FSimple_Tp_Notes. Pardon me, > but if this is such an important topic why is it buried? > > The rest of the docs don't waste many words, as my grandmother used to > say, about feed or speed. > > Just my 2cents worth. > > Regards, > Kent Ah! Back to the future! TP has been endlessly cussed and discussed but it is a non-trivial problem. If it was easy it would have been fixed a long time ago. G64 p was an improvement. So much of this stems from an early in the design process decision that linuxcnc must be able to stop the machine at the end of each block. Les Watts tried something in conjunction with NIST years ago but it never quite worked. I keep hoping someone will have an epiphany that will push tp forward. (npi).
Catting short segments into an arc can make a real difference. I suppose if one needs to avoid line to arc transitions then lines could be specified as arcs with a very large radius. No panacea anywhere in sight. Dave ------------------------------------------------------------------------------ Precog is a next-generation analytics platform capable of advanced analytics on semi-structured data. The platform includes APIs for building apps and a phenomenal toolset for data science. Developers can use our toolset for easy data analysis & visualization. Get a free account! http://www2.precog.com/precogplatform/slashdotnewsletter _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
