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 ------------------------------------------------------------------------------ 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
