Stephen Wille Padnos wrote: > > What it could be is Intel power management turning off parts of the chip > or changing the clock speed (even though I disabled that, I think). > > OOOHhh! Nasty stuff. Once it powers down, who knows how long it takes to power up again? But, maybe it is something totally different - it could be the idle task does some totally stupid thing that messes up the cache on the busy CPU. Something like a memory parity scrub that constantly overwrites entries in the cache that should be keeping the other CPU happily cranking code efficiently. Just a guess. >>In a remotely related vein, I played around yesterday with >>upping the servo rate to 5 KHz on my minimill, and was surprised >>at how little of the tuning changed. I did have to pull down I >>and D a bit, and the 1/2 F problem was probably worse, as one >>would expect by reducing the encoder sampling interval by a >>factor of 5. There was a VERY strong 2.5 KHz tome when the >>motors were moving at certain speeds, and the PID output had a >>clear 2.5 KHz component. I am going to have to experiment with >>a simple filter to remove the highest frequency components from >>that and see how it works. I think even just averaging the last >>two samples will help. >> >> > > Interesting. I wonder if a two-tap filter in HAL would fix that. It's > a trivial comp to write (if it's not there already). Pete Vavaroutsos put in a biquad IIR filter (components/biquad.comp), with some code to precompute the coefficients. It looks like maybe there's a way to load your own coefficient matrix as well. I'll have to spend some time figuring out how to set it up and put it in the output of the PID and see what it does.
Jon ------------------------------------------------------------------------- This SF.net email is sponsored by: Splunk Inc. Still grepping through log files to find problems? Stop. Now Search log events and configuration files using AJAX and a browser. Download your FREE copy of Splunk now >> http://get.splunk.com/ _______________________________________________ Emc-developers mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-developers
