On Sun, 2011-06-05 at 13:13 -0400, Dave wrote: > > On 6/5/2011 10:58 AM, dave wrote: > > Hi all, > > IRC seems pretty dead this morning so I'll try here. > > > > I seem to remember cradek doing a velocity to dac signal to emulate a > > tach. However I cannot seem to find documentation. > > Board is a 5I20 running hm2 so the velocity signal should be there. > > I just need the hal commands to get started. > > > > I've been using a Keling 750 W servo motor with a 2:1 and a 10 mm pitch > > ballscrew to drive the Z on my Cinci contourmaster. In torque mode I > > have stability problems; I finally ended up getting the following error > > down to about .002 ... pretty bad .. and that is after about 8 hours of > > tuning! This is usable for some things but doesn't do well for > > contours. > > > > Plan 1. go to velocity mode and add a tach. The tach is low output. > > only about 2.5 V/1000 rpm. For some reason I can't get the system > > stable. When enabled it oscillates for a few seconds and faults. > > That is with the analog input at zero (shorted). > > I've moved the tach gain all over the place with no luck so far. > > > > > > Plan 2. add the synthetic tach as per cradek. > > > > Plan 3. install a SEM servo motor with a known tach output. > > The X axis of this machine already has an SEM so I know it will > > work. :-) > > > > I'm open to ideas and opinions. > > > > Dave > > > > Forgetting about EMC2 for a moment; > > With the drive in velocity mode, if you short the analog to input the > Servo drive you should be able to adjust the zero offset and gain so the > motor is somewhere between dead still to creeping. No oscillating.
Exactly! So back to the drawing board. ;-) > > If you can't do that you have a drive/motor/encoder and that will not be > resolvable with EMC2 tuning. > > How many encoder counts do you have per rev? 2500 cpr or 10K in quadrature. At Peter's suggestion I checked the servo cycle. servo cycle was set at 250000. I think I tried faster setting when I was originally tuning but got errors. dave > > Dave > > ------------------------------------------------------------------------------ > Simplify data backup and recovery for your virtual environment with vRanger. > Installation's a snap, and flexible recovery options mean your data is safe, > secure and there when you need it. Discover what all the cheering's about. > Get your free trial download today. > http://p.sf.net/sfu/quest-dev2dev2 > _______________________________________________ > Emc-users mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/emc-users ------------------------------------------------------------------------------ Simplify data backup and recovery for your virtual environment with vRanger. Installation's a snap, and flexible recovery options mean your data is safe, secure and there when you need it. Discover what all the cheering's about. Get your free trial download today. http://p.sf.net/sfu/quest-dev2dev2 _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
