Frequency response evaluation method for microactuators in dual-stage hard disk servo systems

Much of the interest in dual-stage microactuation for hard disk drives centers on control system design methodology, error rejection improvements, and optimal division of the control effort between the coarse and fine actuators. The authors, instead, place the emphasis on evaluating the secondary actuator mechanics from the point of view of the control system. The effective performance of the mechanical plant can be better assessed when combined with a "target" compensator than it can as a raw mechanical transfer function or frequency response function alone.