Method for attenuating mechanical resonances using a multirate low-pass filter

In this paper, a digital filter with multirate technique to handle frequency variation of resonance modes in servo-mechanical systems is proposed. Instead of using many notch filters, one low-pass filter will handle multiple mechanical resonance modes. The proposed digital filter will have robust resonance cancellation capability with comparable or even lower phase loss than using notch filters. The proposed scheme can well handle the high frequency mechanical resonances in the sense of robustness to variations of resonance frequencies and simplicity to implement in practice. The effectiveness of the proposed method is verified by application to a hard disk drive servo system.