Two degree-of-freedom controllers for hard disk drives with novel reference signal generation

Considers the determination of reference trajectories for use with a two-degree-of-freedom (2-DOF) controller for the head positioning of hard disk drives (HDDs). The reference trajectories are designed in two stages-off-line simulation and online reference generation. The HDD model used for the design includes the back e.m.f. of the voice coil motor. In the second stage, the idea of SMART (Structural vibration Minimized AcceleRation Trajectory) is utilized to adjust the errors at the end of the trajectories. 2-DOF control with the proposed reference trajectory is compared to conventional mode switching control, and its effectiveness is verified. To minimize performance degradation due to disturbances and uncertainties, the use of adaptive robust control (ARC) is suggested.