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Dual-stage actuation using a milli/microactuator is expected to be adopted in hard disk drives (HDDs) to meet the servo bandwidth requirement for higher recording density in the near future. Milli/microactuator resonance and its uncertainty deteriorate the stability of HDD dual-stage control loop and thus restrict the extension of servo bandwidth. In this paper, three resonance compensation approaches for the milli/microactuator, i.e., notch filtering, indirect adaptive compensation, and structurally parallel compensation are analyzed and compared in terms of the capability of resonance suppression, the robustness to resonance shift, and the complexity of implementation. Experimental results are scrutinized to illustrate the merits and drawbacks of each method for a better understanding of resonance compensation in HDD dual-stage actuation systems to support ultrahigh tracking accuracy.
Date of Publication: Dec. 2003