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. 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? 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
