PID control loops are math function implementations that assume no discontinuities or delays in the feedback path, which includes the mechanical parts. Backlash causes discontinuity and will cause the PID to over-respond during the backlash interval. This can be tamed somewhat by reducing gain, but if there is significant backlash, the system will slam back and forth across the backlash and beat the machine to death.
Steve Stallings > -----Original Message----- > From: erik.555.gr...@gmail.com [mailto:erik.555.gr...@gmail.com] > Sent: Tuesday, May 22, 2012 8:44 AM > To: emc-users@lists.sourceforge.net > Subject: [Emc-users] Servo system and glass encoder scales > for positionfeedback > > 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 > ------------------------------------------------------------------------------ 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
