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Disturbance modeling and control design for self-servo track writing

The major disturbances in self-servo track writing are identified and modeled. Based on the disturbance models, an H/sub 2/ controller together with a feedforward compensator is designed via linear matrix inequality approach to minimize the propagation tracking error from one track to the next. Furthermore, the error propagation containment effectiveness of the optimal H/sub 2/ control is compared with that of proportional-integral-derivative (PID) and proportional-derivative (PD) feedback controls with the feedforward compensators. Our results show that the propagation tracking error is improved by 27% with the H/sub 2/ control compared with that by PID control.