On Tuesday 08 July 2014 08:13:00 John Thornton did opine And Gene did reply: > Well the Z (torch) is an axis but what the thc component does is to > hijack the position commanded and send a corrected position to the > stepgen based on the tip voltage while lying about the actual position. > The change is not instantaneous by any stretch of the imagination. The > correction is dribbled out once per period
Which period, servo, bsse? Common sense says servo-thread period. > in the amount you set by the > correction velocity which is not named properly now that I think about > it. Would it be made more intuitive for the user carving up his own .ini file if a third category name was defined for "torch" which is an alias for linear, but which changes the syntax for MAX_VEL and MAX_ACCEL to some more sensible names? To get some standard in function, SCALE should remain a real value as we calculate now. > The only reason it could stall the stepper is if you set the > correction velocity too high to start with. IMHO the correction > velocity should be less than a step and has to be arrived at by > watching the tip voltage as you slowly increase it from some insanely > small amount. Too much in my experience causes the correction to > overshoot and the torch (Z) will bob up and down. Too little and the > tip voltage will not stay within an acceptable range. Sort of like an out of tune PID then? This is something I don't recall seeing what sort of a voltage, and the limits to it, being discussed here in any great detail. As for the velocity, one microstep per servo-thread should work, but that doesn't contain an acceleration to correction_velocity factor and would, from a dead stop, likely stall the motor. So there has to be some "ballistics" involved. > And I might add that the thc component will only work with steppers due > to the hijack/lying about position stuff. Which is unfortunate, but I can't quickly imagine a way around it either. > JT Interesting thread here John, I think I am learning something. Cheers, Gene Heskett -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) Genes Web page <http://geneslinuxbox.net:6309/gene> US V Castleman, SCOTUS, Mar 2014 is grounds for Impeaching SCOTUS ------------------------------------------------------------------------------ Open source business process management suite built on Java and Eclipse Turn processes into business applications with Bonita BPM Community Edition Quickly connect people, data, and systems into organized workflows Winner of BOSSIE, CODIE, OW2 and Gartner awards http://p.sf.net/sfu/Bonitasoft _______________________________________________ Emc-developers mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-developers
