Peter C. Wallace wrote: >On Mon, 2 Feb 2009, Stephen Wille Padnos wrote: > > >>>Although EMC receives feedback in realtime it does not adjust commands to >>>the axes if the axes are getting closer to exceeding the following error >>>limits. I do not know this to be true. This is a statement from the >>>supplier of motion control hardware for EMC and Mach3. >>> >>> >>> >>> >>This is false. PID by definition changes the command output as the >>error changes (unless you explicitly set all the coefficients to 0). >>The PID in EMC2 is actually PIDFF - there are "feedforward" terms, which >>can pass changes in control input directly through. This improves >>response significantly, since no error is required to get an output. >>PID coefficients are applied to the position error, so normally there >>can be no output until some time after a command to change position has >>arrived. FF coefficients are applied to the command input, so they >>generate some output immediately. >> >> >> >Hi SWP! > > Hi Peter! :)
>I was going to answer the same but I think what is being asked is a little >different. I think what was being asked is whether EMC could lower the >feedrate based on The magnitude of the following error being > some_limit > > Oh, you may be right. EMC2 can do this, but I don't know if anyone has yet. The PID component now outputs error on a pin, and also outputs a "saturated" signal when output has been too high for a period of time. These can be used, along with adaptive feed override, to reduce the overall feed rate. - Steve ------------------------------------------------------------------------------ This SF.net email is sponsored by: SourcForge Community SourceForge wants to tell your story. http://p.sf.net/sfu/sf-spreadtheword _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
