Yes, time-stamping the pulses works, if you have an accurate counter that can be snap shotted by the pulse. A modern microcontroller or FPGA can do that. But as the pulses get faster you have to transition back to counting pulses not "ticks" or you have the same quantization noise problem. I think you have to run both algorithms and then decide which number is most reliable in real-time. I've tried to do this a few times
On Wed, Jul 21, 2021 at 10:05 PM dave engvall <dengv...@charter.net> wrote: > > > "The solution is to either add more counts per revolution or use a ten > timesmore complex control algorithm." > > IIUC then the real problem here is statistical. That is the sample size is > too small to be significant. Maybe an over-simplification of the issue but: > > I think there are a couple of ways to approach this. (1) time stamp the > index pulse. > (2) use a high count encoder and scale as necessary. This > is clearly limited by the response of the optics for the disc. > 100 - 200 KHz for the inexpensive stuff. > I don't think there is a one size fits all solution. In electronic terms > lathe spindles are pretty slow and have a lot of angular momentum. Most > lathe spindle > rpm range is not a lot over 5-6 binary bits. > I've actually considered putting a disc brake on the spindle. Not > exactly joking. > > Just late evening rattling the cage. > > Dave > > > > > > > > > > >>>> Could you solve the noise issue with a phase-locked loop? > >>> Yes, this would be a far better solution. But I didn't want to > >>> re-write the encoder counter from scratch. > >>> > >>> Ideally you would use two PLLs, one for the pulses and one for the > >>> index, to predict the pulse gap and extrapolate through it. > >>> > >>> -- > >>> atp > >>> "A motorcycle is a bicycle with a pandemonium attachment and is > >>> designed for the especial use of mechanical geniuses, daredevils and > >>> lunatics." > >>> � George Fitch, Atlanta Constitution Newspaper, 1912 > >>> > >>> _______________________________________________Emc-users mailing list > >>> Emc-users@lists.sourceforge.net > >>> https://lists.sourceforge.net/lists/listinfo/emc-users > >> > >> > >> _______________________________________________ > >> Emc-users mailing list > >> Emc-users@lists.sourceforge.net > >> https://lists.sourceforge.net/lists/listinfo/emc-users > >> > > > > > > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users > -- Chris Albertson Redondo Beach, California _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
