On Mon, Nov 17, 2008 at 10:50:32PM +0800, Howard Chan wrote: > http://myweb.polyu.edu.hk/~icwfchan/P1.png
This graph does not show measured noise in the DAC output. To measure that you would have to hook a scope or other diagnostic equipment to the physical DAC output pin on the mesa servo daugher card. This graph shows DAC output commanded by emc2, which is presumably the output of the pid algorithm mentioned by seb. He is correct that it's a tuning issue. In addition to the P, I, D, and FF parameters you may wish to adjust deadband. deadband can be used to get a PID output of exactly 0 when within a specified range of the commanded position. (However, if there is an uncompensated voltage offset in the DAC or amplifier, this may not fix the problem entirely) Jeff ------------------------------------------------------------------------- This SF.Net email is sponsored by the Moblin Your Move Developer's challenge Build the coolest Linux based applications with Moblin SDK & win great prizes Grand prize is a trip for two to an Open Source event anywhere in the world http://moblin-contest.org/redirect.php?banner_id=100&url=/ _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
