Track-Following Control with Active Vibration Damping and Compensation of a Dual-Stage Servo System

This paper proposes a vibration control scheme for an actuated slider dual-stage servo system. The control scheme consists of three components: a basic track-following servo control loop, a feedback vibration damping loop of the voice coil motor (VCM) assembly and a plug-in feedforward vibration compensation loop for the microactuator (MA). A strain sensor located on the surface of the suspension, detects airflow-excited structural vibrations and its signal is fed to the feedback damping and feedforward compensation loops simultaneously. Because the strain sensor signal is analog, higher sampling control rates can be achieved for both the feedback damping and feedforward compensation controllers, than for the track-following servo loop, which is limited by the maximum attainable sampling rate of the position error signal (PES). Simulation results show that the track-misregistration (TMR) resulting from structural vibrations can be greatly attenuated using both the active feedback damping controller around the VCM and the feedforward vibration compensation controller on the MA, achieving and a total reduction of 43% in TMR over the conventional dual-stage actuation. This result implies that the proposed control scheme is suited for use in increasingly high track density, high performance hard disk drives.