Microactuator control for disk drive

The nonlinear response of a conventional actuator which depends on the ball-bearing friction is the main factor for determining the high track density of hard disk drives. We cannot get enough servo loop gain in the low-frequency region with a conventional single actuator because of its hysteresis characteristics. We have developed a new planar piezoelectric microactuator which is lightweight and applicable for a hard disk drive. Also we introduced a two-stage servo controller and realized a high servo bandwidth over 1 kHz and enough tracking-error reduction in the low-frequency region.