Enhanced disturbance suppression in sampled-data systems and its application to high density data storage servos

Abstract

Precise servo control systems require strong disturbance rejection capabilities for accurate positioning in the nanometer scale world today. In this paper, we propose an add-on DDO (disturbance decoupling observer) and DDOS (DO with extraneous sensor) for stronger disturbance suppression. Our proposed control methodology uses a nominal plant model and its inverse to reject input and output disturbances simultaneously in sampled-data systems. The plant inverse controller is approximated by tuning a single parameter. Experimental results on a PZT actuated servo system with air flow of mean speed of 50 m/s corresponding to 15,000 rpm in today's high end hard disk drives show an improvement of 69.2% of 3σ PES (position error signal) during track-following. © 2006 Springer-Verlag.