Adaptive regulation of the flying height for a 2-DOF tripad slider in hard disk drives

Maintaining a small flying height of the read/write head above the disk surface is essential to the development of ultra high storage density hard disk drives. This paper proposes 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. First, a parameterized set of stabilizing controllers for the system is constructed, where each controller is expressed as a function of a stable mapping, or parameter, Q. The online controller tuning is then performed by adjusting the Q parameter in the expression of stabilizing controllers to asymptotically yield the controller needed to achieve regulation. Simulation results are presented to illustrate the capability of the proposed adaptive regulation approach to yield the controller needed to maintain the desired flying height.