Brian wrote: >> He wants the displayed position to have the screw error (and backlash) >> correction applied. Even if EMC2 doesn't do this now, making the >> displayed position show the corrected value sounds like a couple hours >> of work and a new HAL component. The most difficult part is to arrange >> the code to feed the correction table values from the Linux side to the >> component's parameter input. >> >> > > This is incorrect. EMC already adds screw comp to the value > axis.N.motor-pos-fb which then becomes axis.N.joint-pos-fb. I just > want to be able to decouple these two from each other. > OK, now I think I know you are going about this all wrong. You want to have a system that maintains position reference in two modes, yet you want to completely switch from one position feedback source to another. If you want to maintain position reference, you MUST always take position feedback from one, and only one, source, at all times. You can't switch between closed-loop and open-loop without introducing a slight offset every time you switch. My advice would be to make it a truly closed-loop system, and try to tune the stepper-servo so it performs acceptably. The number of advantages here are large, and the only downside is you are trying to work around a backlash problem with a software solution. My feeling is software can NEVER fix backlash, it can only mask it and pretend it isn't there. It works OK for drilling holes, but never really works for milling.
I'm sorry to have to say it so bluntly, but that's what I'm seeing here. 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
