Feedforward Control for Track Seeking Control in Hard Disk Drive with Sampled-Data Polynomial Based on Causal First-Order Hold

Abstract

This study presents a feedforward control method that reduces the seek time of hard disk drives (HDDs) using a sampled-data polynomial based on a causal first-order hold (CFOH). The method improves the seek time of the magnetic-head positioning control system of the HDDs, primarily because the CFOH responds faster than the conventional zero-order hold (ZOH). The sampled-data polynomial enables easy and real-time calculation of the feedforward control input using polynomials, eliminating the need for memory-consuming lookup tables. The sampled-data polynomial for CFOH meets the boundary conditions, including the CFOH characteristics. Moreover, it effectively corrects the discretization error caused by the CFOH without complex calculations. Replacing the ZOH with the CFOH in the feedforward control system of the HDDs improves the performance significantly. Simulation results of the track seeking control of the HDDs confirm that the proposed method successfully reduces the seek time compared to a conventional method.