I’m trying to work through the math for trapezoidal motion-profile generation, and I could use some pointers on this subject.
Reading through the EMC documentation, at <http://wiki.linuxcnc.org/cgi-bin/emcinfo.pl?Simple_Tp_Notes#simple_tp_math>, I saw written, “This is the math for the continuous time case. In the actual code there are correction terms which are required due to the discrete time sampling... these should be described here.” Looking at the code (src/emc/kinematics/tc.c, …/tc.h, …/tp.c, & …/tp.h) did not at all enlighten me as the the algorithm used. (Am I even looking in the right place?) I tried the Google search [motion profile discrete time velocity acceleration limit], and found <http://www.kuka.com/usa/en/products/software/educational_framework/arm_tutorials/PS_Content_Arm1.htm>, where they write, “However, in practice [the various time constants] usually won’t match exactly an integer multiple of [the time step] h. To avoid inaccuracies some corrections have to be made[…]. The implementation of these adjustments is left for the user as an exercise.” For my job, I need to understand how adjustments are made to (what I’m calling) velocity–ramp-up/-down–time, and constant-velocity–coast–time in order to ensure that these are integer multiples of the time step. If you can explain the code to me (cradek, perhaps), or the algorithm, or even know a good reference for this, please let me know (on- or off-list, as seems appropriate). Thanks, —Joel ------------------------------------------------------------------------- This SF.Net email is sponsored by the Moblin Your Move Developer's challenge Build the coolest Linux based applications with Moblin SDK & win great prizes Grand prize is a trip for two to an Open Source event anywhere in the world http://moblin-contest.org/redirect.php?banner_id=100&url=/ _______________________________________________ Emc-developers mailing list Emc-developers@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-developers
