On Tuesday 24 October 2017 10:23:13 Peter C. Wallace wrote: > On Tue, 24 Oct 2017, John Kasunich wrote: > > Date: Tue, 24 Oct 2017 08:47:02 -0400 > > From: John Kasunich <[email protected]> > > Reply-To: "Enhanced Machine Controller (EMC)" > > <[email protected]> > > To: [email protected] > > Subject: Re: [Emc-users] One final Q re using a dc spindle motor > > > > On Tue, Oct 24, 2017, at 08:14 AM, andy pugh wrote: > >> On 24 October 2017 at 12:10, Gene Heskett <[email protected]> wrote: > >>> Correct, except encoder.nn.velocity is fed thru a last 4 edges > >>> averager to remove some of the noise in the encoders output. That > >>> unforch also affects the spindle to Z phaseing in the G33.1 > >>> backout. > >> > >> You might want to filter the velociity, but I see no point in > >> filtering the position, which is what G33.1 uses > >> > >> You could also try using the DPLL timer to take jitter out of your > >> encoder sampling. That's a pretty simple setting with the right > >> firmware (one that ends in "D" for DPLL) > > > > I'm pretty sure Gene's "4 edge average" is dealing with mechanical > > errors in his homebrew spindle encoder rather then sampling jitter. > > The 4 edges mean that it averages over a full quadrature cycle and > > thus deviations from proper 90 degree quadrature phasing are > > masked. > > > > John Kasunich > > [email protected] > > I have considered capturing a timestamp per quadrature state change (4 > timestamp registers) then the drivers velocity estimation code could > have the option of chosing time deltas from the same quadrature edge > as the previous servo thread reading, but usually find I have other > things to do...
Chuckle, that old saw about the road to hell comes to mind, Peter. If anything like me, you first have to find a round tuit, and I am still looking for the artwork to do that which is not bound up an half a dozen copyright claims. Thanks. When I get these blanket chests finished and stuffed in vehicles going west, I'll get back to that project and make you one if I don't miss roll call some morning first. 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> ------------------------------------------------------------------------------ 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
