Stable Peak Filtering Method to Reject High Frequency Disturbance in Hard Disk Drives

Abstract

In this paper, novel solutions are provided for designing the disturbance filter when there are significant plant dynamics within the bandwidth of the filter. The filter zero is designed appropriately so that the root loci originating from both the filter poles and the lightly damped plant poles go to the stable region under certain low gain condition. By providing compromised departure angles from filter poles and plant poles, the stability margin especially the gain margin is dramatically increased. The resulting closed-loop systems can provide large gain attenuation at the resonance frequency, and thus have more disturbance rejection capability.

Compensation of mechanical resonances by adaptive feed-forward cancellation for head positioning control system in hard disk drives

“…Diameter of the disk size is standardized as 2.5 or 3.5 inch, therefore the recording density on the disk should be increased. The recording density of the HDD is decided by track misregistration (TMR) (Abrahamson, S. and Huang, F. 2015;Hong F. and Du C. 2010). The TMR represents the misalignments between the magnetic head and the target positions on the disk.…”