| 摘要 |
PROBLEM TO BE SOLVED: To shorten the restoration time of a magnetic head from offset when the servo position information of the magnetic head cannot be read continuously from the magnetic disc, or when possibility for inclusion of an error in the detected data is high due to the change in the floating amount of the magnetic head due to vibration impact from the outside in the magnetic disc drive. SOLUTION: In a magnetic disc drive, an observer 16 estimates a position/ velocity information of a magnetic head 23 (107b). Moreover, an impact sensor 10 detects vibration impact from the external side. Depending on the magnitude of vibration impact (101), existence or no-existence of detected error of servo information of the magnetic head (103) and magnitude of estimated error (106), any one of the estimated position/velocity information (107b) of observer 16 and detected information from the magnetic head (105) is selected with a selector 15 for calculation of the control amount of an actuator (110).
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