On Tue, 7 Nov 2017 09:55:28 -0800 (PST) "Peter C. Wallace" <[email protected]> wrote:
> On Tue, 7 Nov 2017, Nicklas Karlsson wrote: > > > Date: Tue, 7 Nov 2017 18:48:24 +0100 > > From: Nicklas Karlsson <[email protected]> > > Reply-To: "Enhanced Machine Controller (EMC)" > > <[email protected]> > > To: "Enhanced Machine Controller (EMC)" <[email protected]> > > Subject: Re: [Emc-users] PID refresher for Gene? > > > > On Tue, 7 Nov 2017 12:28:31 -0500 > > Gene Heskett <[email protected]> wrote: > > > >> On Tuesday 07 November 2017 10:08:33 Peter C. Wallace wrote: > >> > >>> On Tue, 7 Nov 2017, Gene Heskett wrote: > >>>> I fail to see why a 2 or 3 percent error in duty cycle and or > >>>> quadrature results in so much noise. There simply is no way in hell > >>>> that spindle can be moving at 200 rpms on one servo-thread sample, > >>>> and 600 rpms on the next sample one millisecond later while its > >>>> filtered display on a pyvcp tach dial says 400 rpms. > > > > Mean value = (200rpms + 600rpms)/2 = 800rpms/2 = 400 rpms. > > > > 2 pulses each millisecond, add some noise and sometimes it is 1 pulse while > > other times 3 pulses each millisecond. Multiply by 200 => 200*(1 2 3) = > > (200, 400, 600). > > > > How many pulses each time value is calculated? > > > Not relevent, velocity estimation on Hostmot2 firmware calculates velocity > based on the number of counts divided by the time between the counts (the > sample time is not used in this calculation) Yes it is. 200 = x/(dt = 1/1000 seconds) = x*1000*seconds <=> x = 200/1000 = 0.2 so velocity = 0.2/dt*(number of counts) I once visited a seminar with an old man from Analog Devices and had not find a single case then ohms law did not work. Regards Nicklas Karlsson ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
