On Sat, 20 Mar 2010, Jon Elson wrote: > Date: Sat, 20 Mar 2010 21:54:58 -0500 > From: Jon Elson <el...@pico-systems.com> > Reply-To: "Enhanced Machine Controller (EMC)" > <emc-users@lists.sourceforge.net> > To: "Enhanced Machine Controller (EMC)" <emc-users@lists.sourceforge.net> > Subject: Re: [Emc-users] G52 and Fanuc conversion to EMC > > Chris Radek wrote: >> On Sat, Mar 20, 2010 at 03:57:02PM -0500, Jon Elson wrote: >> >> >>> If you look further, I think you will find there is NO tachometer in the >>> machine. The Fanuc controls synthesize this from the encoder signals. >>> >> >> The mesa hostmot2 driver has a good encoder velocity output that >> considers the time stamp of the last encoder event to give smoother >> output than d(counts)/dt. I'd just send that to a dac and see if it's >> good enough to keep the amp happy. If it is, you have a pretty >> cheap solution (just the cost of another 7i33). >> >> If that didn't just work, I'd quickly give up and fit real tachometers >> like some others have suggested, because I bet in the long run that >> is the best configuration. >> > Well, that's what I'm worried about, too. It seems like taking > something from the encoder at the servo period, using a HAL component > and then feeding out a DAC would HAVE to cause a millisecond of delay. > Also, the Mesa DAC is really a PWM generator to a smoothing filter, and > I don't know what the bandwidth of that filter is. With really old > Fanuc phase angle servos it may not matter, with newer units with more > bandwidth it could be a problem. > > Jon >
For adequate phase margin you might have to run the servo loop faster (since you are now supplying the high bandwidth velocity feedback) It should be possible to run HostMot2 hardware at 10 or more KHz if this is an issue > ------------------------------------------------------------------------------ > Download Intel® Parallel Studio Eval > Try the new software tools for yourself. Speed compiling, find bugs > proactively, and fine-tune applications for parallel performance. > See why Intel Parallel Studio got high marks during beta. > http://p.sf.net/sfu/intel-sw-dev > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users > Peter Wallace Mesa Electronics (\__/) (='.'=) This is Bunny. Copy and paste bunny into your (")_(") signature to help him gain world domination. ------------------------------------------------------------------------------ Download Intel® Parallel Studio Eval Try the new software tools for yourself. Speed compiling, find bugs proactively, and fine-tune applications for parallel performance. See why Intel Parallel Studio got high marks during beta. http://p.sf.net/sfu/intel-sw-dev _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
