Singular Perturbation Control for Vibration Rejection in HDDs with a PZT Active Suspension

In this paper, the SPT (singular perturbation theory) is applied to decompose the VCM´s (voice coil motor) and induced PZT active suspension´s dynamics into fast and slow subsystems, respectively. The control system is decomposed into fast and slow time scale for controller designs, and control effectiveness is increased to tackle more DOFs (degrees-of-freedom) via inner loop vibration suppression with measured high frequency VCM´s and PZT active suspension´s dynamics from the piezoelectric elements in the suspension. Experimental results on a commercial HDD with LDV (laser Doppler vibrometer) show effective suppression of the VCM and PZT active suspension´s flexible resonant modes as well as an improvement of 39.9% in 3sigma PES (position error signal) during track following when compared to conventional notch-based servos