----- Original Message ----- From: "John Kasunich" <[EMAIL PROTECTED]> To: "Enhanced Machine Controller (EMC)" <emc-users@lists.sourceforge.net> Sent: Wednesday, August 15, 2007 8:59 AM Subject: Re: [Emc-users] Encoders with steppers
<snip> > PID's response to feedback falling behind command is to drive > the motor harder. With a stepper, that means step faster, which will > just result in less motor torque and more lost steps. > Instead of PID speeding up the stepper, could it be connected to feed rate override and slow the feed until the stepper caught up? For example: a commanded feed of 10ipm, a step is missed, feedrate is reduced to 9ipm, proportional error adds 0.1 ipm, output is 9.1 ipm with trajectory feedrate at 9ipm, stepper will catch up. Perhaps it could be set up so if you missed enough steps for your feed rate override to be less than 50% you would get a following error. This could another can of worms with acel/decel, etc. I think I would prefer to just stop with a following error and be able to restart. Perhaps the feed was set too high, maybe the end mill is dull, or perhaps the acel/decel rates are too high. Either way, I would prefer to have a fault than ruin my part/vise/clamps/table/cutter/etc. Roger Neal ------------------------------------------------------------------------- This SF.net email is sponsored by: Splunk Inc. Still grepping through log files to find problems? Stop. Now Search log events and configuration files using AJAX and a browser. Download your FREE copy of Splunk now >> http://get.splunk.com/ _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
