Adaptive resonant mode compensation for hard disk drives

This paper is concerned with a mechanical resonant mode compensation problem for hard disk drives. Conventional notch filters must have deep and wide enough frequency characteristics in order to accommodate all possible resonant mode characteristic perturbations, which result in deterioration in positioning accuracy and residual vibration after seeking. This paper proposes an easy-to-implement adaptive notch filter of which the center frequency follows the resonant frequency change. The basic idea of this adaptive filter is to balance two kinds of frequency weighted variances of the control input signal.