Roger Holmquist wrote: > Thanks for your responses. > It seems I have to give LinuxCNC a closer look. > > There is a low cost commercial alternative in MACH 3. > I guess you have an opinions on that system too? > I know it's based on Windows with some kind of realtime extension who > doesn't sound too good in ears. > My impression is that it doesn't look professional after a brief > examination. > It also seems to be mainly focused on stepper motor systems who I > believe is off topic in heavy duty systems. > > Right, Mach is designed primarily with step/direction control in mind, and cartesian machines. > My assumption about Tarjectory planning was based on Anders Wallins > message as he mentioned some problem with limited look-ahead, > I suppose this affects the shape of the calculated path in some cases? > No, it only affects speed. The optimal lookahead would be able to run at commanded velocity in cases where long strings of short linear and arc moves are coded, being able to see many lines ahead that there is no deviation large enough to require slowing down to stay below the maximum acceleration set for the machine.
The current trajectory planning does not look that far ahead, and so will never allow you to go so fast that it can't stop after the next move. So, at some level, it is just one block look ahead. This looks easy to fix in the narrow sense, but when a program could have any possible mixture of linear and arc moves on a multi-axis machine, it starts to get complicated. You do have a choice of how much blending of move corners to allow in your program, via G61 and G64 commands. Jon ------------------------------------------------------------------------------ This SF email is sponsosred by: Try Windows Azure free for 90 days Click Here http://p.sf.net/sfu/sfd2d-msazure _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
