Selection of PI compensator parameters for NCTF controller based on practical stability limit

This paper describes the design of a Proportional Integral (PI) compensator for a nominal characteristic trajectory following (NCTF) controller that based on practical stability limit. NCTF controller is a control system that has simple structure and easy design procedure in order to achieve good performance in both point-to-point (PTP) motion and continuous motion (CM). NCTF control system consists of a nominal characteristic trajectory (NCT) element and a PI compensator. In order to ensure the stability of the system with NCTF control, the PI compensator is designed based on practical stability limit. The practical stability limit is determined experimentally with the proposed procedure. The PI gains are selected from the stable region of the practical stability limit. In this paper, the selection of different PI compensator under the practical stability limit is discussed. A ball screw mechanism is used to clarify and examine the positioning performance of the NCTF control system with four pairs of PI compensator that under stable region and one pair of PI compensator that outside of practical stability limit. The experimental positioning results proved the high positioning performance of the ball-screw mechanism with NCTF control that using PI compensator under the stable region.