Karl, Have you worked with the KURT package? I am in Wichita, Heaven(Kansas). Not much of a drive. If you are in Wichita - stop by and see what we are doing.
On Thu, Oct 9, 2008 at 3:10 PM, Karl Schmidt <[EMAIL PROTECTED]> wrote: > Stuart Stevenson wrote: >> Can I effectively bypass the SCR tuning by increasing the gain a >> lot (much past what the motor can handle) and using the tuning in EMC >> to control the motor. Could this turn the SCR into a dumb amp. >> thanks >> Stuart > > What is the source of the feedback? Is it the motor shaft or table encoder? Feedback is two fold. Tach from motor to amp and encoder from motor to EMC2. > > From my readings on this subject, it is best for the motor to have it's own > loop - and then if you > add a table feed back, it would be done as a outer PID loop - using only the > 'I' of PID. I've also > thought that the right way to do this would be to update the backlash every > time the motion reverses > so as the ball-screws warm up, the backlash numbers stay up to date. Then the > net motion would be > fed to the nested loop. This is done. Just as you described. On a machine here. A G&L with linear scales. For testing it has worked very good. Have not cut parts with it yet. > > To take this to the extreme, you could also feed in the force (calculated > from the motor current) > and have different backlash numbers depending on how hard the motor is > pushing. The ball screws on the cinci are double nuts with a spacer in between to take up the backlash. I want to build hydraulic bladders to take up the slack. This would allow variable preload and zero backlash. Using pressure inversely proportional to the speed would allow fast motion and accurate positioning. > > I haven't done any of this yet, but from what I've read, it should be > possible to have EMC2 do all > of the control work - nested PID loops - backlash correction. I haven't seen > where anyone has an > actual system doing this? > > One point of view is that the controller should be as simple as possible and > EMC2 would just tell > the controller where to go (KISS). The other take on this is that Linux is > stable enough that there > shouldn't be any problem with it running the whole show - and if it is doing > everything, extreme > tweaking is possible. On Windoze, (or a boxes with nasty routines in the BIOS > that interrupt > realtime activities) it is best to go with KISS. On the other hand, Linux is > quite stable, tweaking > is fun, and moving the smarts to EMC should further reduce the cost of the > electronics. > > My only concern is that most folks are running Ubuntu, which is rather > bleeding edge for a motion > control platform - I would rather see this on a Debian-stable distribution, > where things don't > change as often. I don't know about everyone else but Ubuntu and trunk have served me well. > > -------------------------------------------------------------------------------- > Karl Schmidt EMail [EMAIL PROTECTED] > Transtronics, Inc. WEB http://xtronics.com > 3209 West 9th Street Ph (785) 841-3089 > Lawrence, KS 66049 FAX (785) 841-0434 > > Experience is something I never get, > until just after I needed it. > > -------------------------------------------------------------------------------- > > ------------------------------------------------------------------------- > 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 > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users > > ------------------------------------------------------------------------- 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 Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
