Mechatronics of electrostatic microactuators for computer disk drive dual-stage servo systems

A decoupled control design structure and discrete time pole placement design method are proposed for MEMS-based dual-stage servo control design in magnetic disk drives. Dual-stage track following controllers are designed using a decoupled three-step design process: the voice coil motor (VCM) loop design, the microactuator (MA) inner loop design, and the MA outer loop design. Both MIMO (when the MA relative position sensing is available) and SIMO (when the MA relative position sensing is not available) designs are considered. The effect of MA resonance mode variations on the stability and performance of the controllers are analyzed. Self-tuning control and online identification of the MA model are developed to compensate for the variations in the MA's resonance mode.