It can be (and has been) done. You probably will need to keep the encoders on the motors, unless your ballscrews and the rest of the drivetrain is very tight and backlash free. The trick is to use the motor encoders for the P and D parts of the PID loop, for stability, and use the linear scales for the I part, to correct the small and fairly slow-changing error between the screw and the scale.
Follow the link below for a blog posting about how we did exactly that on a large boring mill: http://jmkasunich.com/cgi-bin/blosxom/shoptask/wichita-trip-02-20-08.html On Tue, May 22, 2012, at 01:43 PM, erik.555.gr...@gmail.com wrote: > Are there any major dis-advantages to using glass scales as position > feedback for a servo system versus using encoders directly attached to > the > motors. I could see where backlash might be an issue but if using > precision > ground ballscrews........ > ------------------------------------------------------------------------------ > Live Security Virtual Conference > Exclusive live event will cover all the ways today's security and > threat landscape has changed and how IT managers can respond. Discussions > will include endpoint security, mobile security and the latest in malware > threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users -- John Kasunich jmkasun...@fastmail.fm ------------------------------------------------------------------------------ Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
