Enhanced Vibration Suppression in Hard Disk Drives Using Instrumented Suspensions

This paper summarizes work that has been completed to evaluate the use of high-resolution thin-film strain sensors for vibration suppression in hard disk drives (HDDs). In particular, we demonstrate the viability and necessity of symmetrical sensors for cancellation of common non-off-track modes in the measurement. Thin-film ZnO strain sensors have been successfully integrated into instrumented suspension prototypes, and strain signals were extracted from operating disk drives. High-resolution strain sensing allowed us to investigate the nature of airflow excitation of the suspension structure. Experimental measurements were used to construct both ideal and realistic models. Using the ideal model that ignored non-off-track modes, multirate nominal
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control synthesis and simulation were employed to evaluate potential improvements in closed-loop vibration suppression in a multisensor framework. These simulations projected improved tracking performance using auxiliary high-resolution strain sensing with increased sample rate. However, when a robust
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damping controller was designed using a more realistic model of the available hardware, performance in simulation and experiment was limited by numerous non-off-track modes in the sensor signal.