Design of a hard disk drive control system in a multirate system for improvement in the steady-state intersample response

This paper proposes a new design method for the positioning control system of a hard disk drive (HDD) head. To control the head in an HDD, the control input supplied to the voice coil motor is updated at a fast rate, but the sampling interval of the head position is restricted because of hardware constraints. Hence, the designed control system is a multirate system. In this study, the multirate control system designed for controlling the head in an HDD is extended, and the intersample response is improved independently of the sample response. The effectiveness of the proposed method is demonstrated by a numerical example.