Brian wrote: > This is what I am currently doing, but it doesn't really do much for > me. I even have a bar graph of the current position error. I think > it would be a natural progression for EMC to have the option to use > feedback from a source that is subject to screw comp, or one that > isn't. > > Brian > > On Fri, Aug 6, 2010 at 1:51 PM, Andy Pugh <[email protected]> wrote: > >> >> It is in the right place if the position feedback component is the >> motor encoders. >> OK, I still don't understand the fundamental problem. My understanding was that the screw error was applied to the position feedback, so the position displayed on the screen is already corrected for error. I think Andy is confirming this above.
So, if that is true, then you are using the wrong motion component, because it is one that can't handle actual position feedback. If you want to disable the motors, move the machine and then re-enable, I think you MUST change the way you command motion, to use one of the possible schemes that look more like a servo system. EMC1 did this, with a software simulation of a step-servo. EMC2's stepgen is decidedly in the open-loop mode, and so is inappropriate for this type of use. I'm sorry that it seems like I'm plugging my hardware, but I know that I have had this capability since 2002 with my Universal Stepper Controller. I'm pretty sure the Mesa boards can do the same thing. I think this functionality has been taken out of EMC2 because it confused people. Since all the parts are there, it probably would not be that hard to put back in, there may even have been an early EMC2 step generator component that followed the old servo mode that could be resurrected. Jon ------------------------------------------------------------------------------ This SF.net email is sponsored by Make an app they can't live without Enter the BlackBerry Developer Challenge http://p.sf.net/sfu/RIM-dev2dev _______________________________________________ Emc-developers mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-developers
