Modeling and design of controlled flying proximity sliders for head-media spacing variation suppression in ultra-low flying air bearings

In this paper, a novel controlled flying proximity (CFP) slider is presented. A new 3-DOF analytic model is proposed to describe the dynamics of the piezoelectric actuated slider. The air bearing parameters, such as stiffness and damping, are identified by a modal analysis method. Then, an observer-based nonlinear sliding mode controller is designed to compensate the short-range attractive forces and to suppress the FHM of ultra-low flying height air-bearing sliders in proximity, in which the magnetic signal is used for real-time FHM measurement. The attractive forces are included in the model as a highly nonlinear term and the effect of disk morphology is modeled as unknown but bounded disturbances. Numerical simulations investigate the performance of the controller.