On Monday 17 December 2012 07:54:03 andy pugh did opine: > On 17 December 2012 02:59, Gene Heskett <[email protected]> wrote: > > The math I was able to find seems complex, some of it might even have > > had a very time consuming power series. I don't think we have, in a > > millisecond time frame of the servo-thread, enough time to fool > > around doing even a lookup table method of doing the nominally 2.5 > > power multiplier, > > Lookup tables are fast. We evaluate 4000 of them at a time in the > engine calibration, typically multiplying all the answers together. > Those are 2D too.
I agree. Basically you quantize the input number to fit the table size, look up that number and multiply the raw input by it to get the output. and this is a case where a 20 number table would be adequate. But developing that table easily would require a bit of magic, specially when stopping LinuxCNC on this machine often results in a non-recoverable crash. I was running it last night, looking at things with 6 or so copies of halmeter running, it crashed again after doing all the exit cleanup, and in 7 hours has not rebooted to where I can ssh -Y into it again. I think the psu is duff, but their web site now has a D2700MUD board in that shoebox & the shoebox claims a 300 watt psu. 90 watts would be a great plenty. It may not like that light a load, that motherboard w/2gigs & a 250Gb HD. > It is quite likely that an arbitrary-order polynomial could be handled > without too much difficulty too. But a lookup can do anything that a > polynomial can do, and more (can be discontinuous) Which may be, at the end of the day, whats needed here. But we'll try this lashup with live motors first, it may be sufficient. One question re optimizing hal: Is the servo-thread execution sequence the same as the addf statements order? Thanks Andy Cheers, Gene -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) My web page: <http://coyoteden.dyndns-free.com:85/gene> is up! A little experience often upsets a lot of theory. I was taught to respect my elders, but its getting harder and harder to find any... ------------------------------------------------------------------------------ LogMeIn Rescue: Anywhere, Anytime Remote support for IT. Free Trial Remotely access PCs and mobile devices and provide instant support Improve your efficiency, and focus on delivering more value-add services Discover what IT Professionals Know. Rescue delivers http://p.sf.net/sfu/logmein_12329d2d _______________________________________________ Emc-developers mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-developers
