Track-follow Control for High-density Probe-based Storage Devices

Probe-based data-storage devices are being considered as ultra-high-density, smallform-factor and low-power alternatives to conventional data storage. Ultra-high storage densities of up to 1 Tb/in or more can be achieved by using atomic force microscopy (AFM) techniques to write, read back, and erase data in very thin polymer films. High data rates are achieved by parallel operation of large arrays with thousands of micro/nanomechanical cantilevers. MEMSbased x/y micro-scanners are used to navigate the AFM probes over the storage medium. The ultra-high storage densities that probe-storage devices can realize pose a significant challenge to the control design for positioning and navigation. This paper focuses on the track-follow control of a MEMS-based micro-scanner for a high-density probe-based storage device. The positioning requirements are described, and controllers designed for tracking performance as well as controllers using sensor fusion are presented. Experimental results of information recorded at high densities and read back without errors validate the control performance.