Patent ID: 8446687
Filing Date: 2013-05-21
Classification: G11B

Abstract:
1. A magnetic disk drive comprising: a voice coil motor (VCM) actuator configured to cause coarse movement of a head; a microactuator configured to cause fine movement of the head; a detector configured to detect, as first timestamps, time intervals at which the head reads servo sync marks recorded on a disk; and a servo controller configured to control the VCM actuator and the microactuator with feedback control in order to position the head at a target position, the servo controller comprising a feedforward controller for the microactuator configured to compensate for disturbance, wherein the feedforward controller comprises a difference detector configured to detect a deviation of the first timestamps from target timestamps as a timestamp difference; and an integrator configured to convert the timestamp difference into a displacement of the microactuator by integrating the timestamp difference, wherein the feedforward controller is configured to provide a manipulating variable corresponding to the displacement, to a feedback control loop for the microactuator as a feedforward manipulating variable.