Hysteresis Analysis of High Precision PZT Actuator in Dual-Stage Hard Disk Drive

Abstract

In Hard disk drive (HDD) industry, the demand for faster HDD with higher storage capacities had led to the use of a dual-stage servo system with a high precision PZT actuator. However, the PZT actuator is made of piezoelectric material which exhibits hysteresis. Hysteresis causes inaccuracies and oscillations in the system responses. In this paper, the hysteresis behavior is examined for a new high resolution (a few nanometers) PZT actuator fabricated for dual stage actuator. The new PZT actuator has the first resonance at a frequency twenty times higher than the first resonant mode of PZT actuator used at present in HDD. A generalized Prandtl-Ishlinskii (GPI) model is obtained by using curve-fitting with the examined hysteresis behavior. Then the inverse of the GPI model is extracted which can be used as the hysteresis compensator. Finally a model-free hysteresis compensator using adaptive Neural Network algorithm is being proposed for future research.