Magnetic Disk Drive Having Dual Actuator

摘要

In a dual-stage actuator magnetic drive having a coarse actuator and a fine actuator, an amplitude level of a command signal for the fine actuator during a decoupling-path control depends on a gain of an applied fine actuator model. The fine actuator model gain depends on the amplitude level of the fine actuator command signal and needs to be calibrated to avoid performance degradation. The gain is calibrated by determining a deviation of the fine actuator model gain from the fine actuator gain during decoupling-path control. This deviation is obtained by comparing gain values of the open-loop transfer functions measured for the decoupling-path control case and the single coarse actuator control case with respect to the feedback loop of the coarse actuator at an excitation signal frequency, when the excitation signal is added to the coarse actuator.