A switching controller for piezoelectric microactuators in dual-stage actuator hard disk drives

Dual-stage actuators (DSAs) with piezoelectric (PZT) microactuators can provide faster track seeking and more accurate track following in hard disk drives (HDDs) than conventional single-stage actuators. However, one of the control challenges of the DSA systems is the PZT actuator saturation. To avoid saturating the PZT actuator, most of the existing methods either carefully design the PZT controllers with small gains or limit the amplitudes of the reference commands. This typically leads to performance conservation because the fast dynamics of the PZT is not fully utilized. Unlike the existing methods, this paper studies a switching controller that optimizes a quadratic performance cost function involving the PZT saturation model explicitly. The controller can not only guarantee the system stability in the presence of saturation but also improve the tracking speed by efficiently allocating the control efforts. Simulation results show the effectiveness of the switching controller with faster disturbance rejection