On Tuesday 19 January 2016 06:31:10 andy pugh wrote: > On 19 January 2016 at 11:14, Lester Caine <les...@lsces.co.uk> wrote: > > The newer 'closed loop' motors are essentially using the same > > approach, but rather than simply applying the same power for longer > > I don't think that this is what the original poster was asking. I > think he was just wanting to close a position loop with linear scales > on the axes of his stepper-driven machine.
ISTR there's some discussion re that in the wiki. See: <http://wiki.linuxcnc.org/cgi-bin/wiki.pl?Steppers_With_Encoders> and <http://wiki.linuxcnc.org/cgi-bin/wiki.pl?Combining_Two_Feedback_Devices_On_One_Axis> Author unk on this last one. I thought there were some examples in the documentation on linuxcnc.org, but they do not seem to exist in the newest development version's html menu. In any event, those wiki notes could be helpful to the O.P. The second link discusses using two PID modules with an output summing function driving the step generator as one means of gaining accuracy. No mention of the summing gain for that input however. But pid gains could negate the need for other than the default gain of 1.000. I'd note that in my paranoia, I would probably run both pid.n.error outputs together thru an abs module each, and sum them to feed them back to motion to serve as an error stop of the machine if either pid's error was excessive, indicating a problem that could endanger the part or machine. The .ini and .hal files were at one time, perhaps 5 years ago, present and viewable but I can't find them now. They might also be helpfull to the O.P. if they can be relocated and made viewable. 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> ------------------------------------------------------------------------------ Site24x7 APM Insight: Get Deep Visibility into Application Performance APM + Mobile APM + RUM: Monitor 3 App instances at just $35/Month Monitor end-to-end web transactions and take corrective actions now Troubleshoot faster and improve end-user experience. Signup Now! http://pubads.g.doubleclick.net/gampad/clk?id=267308311&iu=/4140 _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
