System identification of modal parameters in dual-stage Hard Disk Drives

To shorten the development and production time of hard disk drives (HDDs), an integrated servo-mechanical design procedure combining mechanical structure prototyping and fast servo evaluation is essential. In this paper, a system identification procedure is developed for estimation of residues, damping ratios, and natural frequencies of resonant modes for the actuators in a dual-stage HDD. The coefficients and residues of the transfer function model are optimized via two subsequent least squares (LS) error optimization criterions in modal summation form. The proposed methodology is verified with experimental frequency responses measured from a commercial dual-stage HDD using the laser Doppler vibrometer (LDV). Our results show the effectiveness of the proposed system identification algorithm in estimating the modal parameters of flexible mechanical actuators.