Not sure how you are applying this, this is posted in the Camsoft forum, are you integrating this in Camsoft or?
If requiring servo control, then you need at least one form of feedback, but when a linear scale is used, it is recommended that an encoder on the motor as well as a linear scale is used, especially if backlash is present.
See the Galil site that has a video that explains the PID tuning for this type of control using dual feedback.
I have used a scale alone on some simple systems using a rolling ring type drive, this possesses virtually no backlash, so it was inherently very stable.
Al.
CNC, Mechatronics Integration and Custom Machine Design
“Logic will get you from A to B. Imagination will take you everywhere.”
Albert E.