Adaptive regulation of the flying height in hard disk drives

The increase in data storage density in hard disk drives is critically dependent on maintaining a small flying height of the read/write head above the disk surface. Disk and suspension vibrations as well as disk surface microwaviness make it difficult to maintain a desired flying height during normal disk operation. It is proposed in this paper to use an adaptive regulation approach to maintain the flying height at its desired value, despite the unknown vibrations and the unknown microwaviness in the disk surface profile. The performance of the proposed approach is analyzed and simulation results are presented to illustrate the capability of the proposed adaptive regulation approach to achieve and maintain the desired flying height