Chris Radek wrote: > On Mon, Nov 01, 2010 at 12:13:36AM -0500, Jon Elson wrote: > > >> One quirk, which I think is inherent in the way that HAL component >> encoder.c works, >> and which I copied, >> is that a dithering encoder gets the wrong velocity. >> > > When Seb K was working on the hostmot2 driver, one of the kinds of > wrongness we found (and he fixed) was > > http://timeguy.com/cradek-files/emc/encoder-velocity.png > > This plot was from a real machine with minor dithering at very low > speed. I do not think the software encoder component is quite right > near zero speed. Yup, I believe you are right. The plot certainly shows a SERIOUS defect! At least with the parameters I'm using for my testing, it doesn't look anywhere that bad, the velocity spikes are only about 2X the nominal speed if there was no dithering. > I think Seb started with that code and improved it > to get the good results we have from hostmot2 now. You might want to > browse the git history to see what he did? > > The changes 84e73cbd534 and especially fed9d8e5a58 look relevant. > I looked briefly at hostmot2/encoder.c but couldn't even tell where the timestamp/velocity code was. Maybe that was the wrong file.
Thanks, Jon ------------------------------------------------------------------------------ Nokia and AT&T present the 2010 Calling All Innovators-North America contest Create new apps & games for the Nokia N8 for consumers in U.S. and Canada $10 million total in prizes - $4M cash, 500 devices, nearly $6M in marketing Develop with Nokia Qt SDK, Web Runtime, or Java and Publish to Ovi Store http://p.sf.net/sfu/nokia-dev2dev _______________________________________________ Emc-developers mailing list Emc-developers@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-developers
