Hysteresis compensation of piezoelectric actuators in dual-stage Hard Disk Drives

In the magnetic disk drive industry, the demand for faster Hard Disk Drive (HDD) with higher storage capacities had led to the use of a dual-stage servo system with a piggyback microactuator. However, the microactuator is a piezoelectric device and hysteresis is an inherent characteristics of piezoelectric devices. Hysteresis behavior, reduces the accuracy of the actuator and thus limits the level of performance that can be achieved by the microactuator. In this paper, hysteresis compensation is included in the control of a Lead Zirconate Titanate (PZT) microactuator from the dual-stage actuation system of a commercial HDD. A Generalized Prandtl-Ishlinskii (GPI) model is used to model its hysteresis behavior and the inverse of the GPI model is used as the hysteresis compensator. The hysteresis compensator is included into a simple feedback control structure and the effect of the hysteresis compensator on the performance of the feedback control structure is demonstrated.