Repetitive controller design for track following of hard disk drive servo system

Recently repetitive controller has been applied in servo systems of hard disk drives (HDD) to remove the repeatable errors caused by rotating mechanism of spindle motors. However, most results of published articles are too complex to be implemented in industrial applications. In this paper, we present an improved design strategy for repetitive control of HDD by minimizing the power spectral density (PSD) of PES. An analytic solution is given with tolerable computation requirements and can be evaluated by software, even assembly languages. Simulations of track following of HDD servo are carried out based upon the theoretical derivations. The result shows that compared to single PID control, the proposed controller improves the performance of steady state response.