Positioning control of an X-Y table based on practical NCTF control

Abstract

This paper describes a practical control method for high positioning performance of a XY table motion system. The controller with the characteristics of ease of design, adjustment and without plant identification are paramount important especially in industry, in order to achieve the end objectives of high positioning motion control. For this aim, a practical controller, namely nominal characteristic trajectory following (NCTF) controller has been studied to satisfy the desired performance. Two NCTF control systems have been designed and investigated to realize high performance and ease of application of point-to-point (PTP) positioning and tracking motions. The NCTF controller is comprehensive, comprising of nominal characteristic trajectory (NCT) and PI compensator, which is free from exact modeling and parameter identification. The NCT works as the reference motion of control system and is determined from experimental open-loop time responses of the mechanism. While, the PI compensator makes the motion of the controlled object to follow NCT and ends at origin. The controller parameters can be determined easily, without any given model parameters. In this paper, the experimental comparative performances of the conventional and Continuous Motion (CM) NCTF controllers have been proposed and validated for the XY table in positioning and tracking control performance. Only the result of the one-axis of the table is examined in this paper. Sufficient continuous motion control performances are presented with the CM NCTF controller as compared to the conventional one