On Wednesday 11 January 2017 11:36:18 Jon Elson wrote: > On 01/10/2017 10:45 PM, Gene Heskett wrote: > > On Tuesday 10 January 2017 23:02:28 Jon Elson wrote: > >> On 01/10/2017 08:39 PM, Gene Heskett wrote: > >>> But if I hook up the halscope, the apparent quadrature error is > >>> worthless due to the 1KHz servo-loop timing limiting the > >>> bandwidth. > >> > >> Well, that's why we use hardware encoder counters, as > >> sampling the quadrature at 1 KHz just isn't fast enough. > >> > >> Jon > > > > Plz elucidate Jon. Something has got to be better than this. See the > > pix I posted with the last reply to Peter & the list. The top, > > white trace in the halscope screen is the quadrature noise, easily > > 10x the timing wibbles I see on the hitachi's screen. > > If you are looking at the quadrature signals at a 1 KHz > sampling rate, then unless the encoder is moving quite > slowly, the sampling will be too coarse. That screen shot > is kind of small (you can take just a single window as the > screenshot, by the way) but it looks like the duty cycle of > the encoders is not 50%. That may well be aliasing, as the > quadrature signals seem to be moving much too close to 1000 > Hz. You'd get much better results below 100 Hz. Or, with > Mesa hardware, you can sample these with the base thread. > > I can't comment on the velocity output from the Mesa, as I > don't know their gear (or driver). But, the scale is 2/div, > meaning the scaled velocity output is jumping around 2 user > units up and down at a KHz rate. Clearly, not good. > > Jon > I have found some quadrature error, so I pulled the ats667 mount off and carved about 5 thou off the divider between the A & B units, jammed a brass shim into the side of the B pocket to push it toward theA unit, carved about 5 thou off the side of the divider between them, washed the oil off several times, glued the A unit in place with a brass shim pushing it snugly toward the B, jammed a piece of rubber beside the B unit to push it toward the A unit, perhaps 10 thou change in the separation, and I'm headed back out to test. Breaking the B unit loose, and filing about 3 or 4 thou off that side of the B unit so the rubber shim would shove it that much closer to together raised the minmax about 10 points on the min, and lowered the max about 25, which have be an indicator as to the mechanical directions needed.
Oh, that ground on the vfd control cable I thought might be loose, was. the diff in duty cycle, aka time up vs time down? Its about 60/40. If it was optical, I'd put a pot in series with the leds and adjust for 50% :) But I haven't a clue how to do that with these ats667's. Darn it. 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> ------------------------------------------------------------------------------ Developer Access Program for Intel Xeon Phi Processors Access to Intel Xeon Phi processor-based developer platforms. With one year of Intel Parallel Studio XE. Training and support from Colfax. Order your platform today. http://sdm.link/xeonphi _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
