Andy Pugh wrote: > 2009/10/1 Jon Elson <el...@pico-systems.com>: > > >> Somebody posted a pastebin that showed large jumps in "some" variable. >> I was never real clear >> what that column in the file was showing, >> > > > If you mean http://www.pastebin.ca/1583502 then that was me. > The columns (which are messed up, but tab-delimited) show timestamp > (once every servo thread),the measured spindle speed > (encoder.0.velocity * 60), the encoder channels (Z then A) , the > output of encoder.0.position-interpolated and then a column calculated > in Excel which is the difference in position-interpolated > sample-by-sample. > I am not sure what it all means. > > OK, if that last column with the large relative variations from sample to sample worked out to be +/- one encoder count, then it doesn't matter, that is the nature of a sampled system. If that variation turned out to be equivalent to many encoder counts, then that is the cause of any jumpiness in following that encoder. > > As an extra datapoint have a zoomed-in Halscope of my encoder > positions at http://imagebin.ca/view/ud8Tect.html which I think shows > that my printed-paper encoder isn't as obviously hopeless as has been > assumed (including by me) > Not clear what the white and blue traces are. The white one looks fine, appears to have a steady count and the intervals between counts are pretty uniform. The blue one seems to be a rounded count down of the white trace, with a ratio of about 6.5 I'm curious as to what that signal is. The scaled count should not be rounded, you want to preserve all the resolution as a floating point value.
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