Compensation of Defect by Friction Force in Magnetic Head Servo System

Abstract

In order to increase magnetic recording density, track width and head-medium spacing have been decreasing. A contact head system is newly under developing for obtaining the smallest lest spacing. Friction force may bring same fatal problems in this case such that friction would deteriorate servo accuracy and stability. Linear control system is fundamentally not able to compensate friction force so that a quasistatic position error would remain due to the nonlinear dynamics. A dither signal is injected to manipulating signal for linearizing the nonlinearity. The dither signal design and modification of manipulating signal for magnetic bead servo system were studied by a computer simulation. The quasi-static position error was tremendously reduced by using the optimized dither signal.