Vibration control of a PZT actuated suspension dual-stage servo system using a PZT sensor

Structural resonance modes of the head stack and suspension assembly are one of the major limiting factors for achieving higher head-positioning servo performance in hard disk drives. This paper discusses the vibration suppression control of a PZT actuated suspension dual-stage servo system. A PZT strip on a PZT actuated suspension is utilized as a vibration sensor to control both the voice coil motor (VCM) actuator butterfly mode and the suspension sway mode. The vibration suppression controller is designed using the H_∞ control design method. Experimental results show that an attenuation of 15 dB can be achieved for both the suspension sway mode and the VCM butterfly mode, and the rms of the head off-track motion due to airflow excited vibration can be reduced by approximately 30% with the proposed vibration suppression control scheme.