Dynamic magnetic information storage or retrieval – Automatic control of a recorder mechanism – Controlling the head
Reexamination Certificate
2005-02-22
2005-02-22
Sniezek, Andrew L. (Department: 2651)
Dynamic magnetic information storage or retrieval
Automatic control of a recorder mechanism
Controlling the head
Reexamination Certificate
active
06859341
ABSTRACT:
For runout compensation in a data handling system, a servo feedback loop is configured to control a head position relative to a corresponding disc surface. Operation of the feedback loop is complicated by a repeatable error in the head position having energy at harmonics of the spindle rotation frequency. Also, the feedback loop has a gain with a frequency sensitivity in a target frequency range. A feedforward controller generates an output injected into the feedback loop based on an error-indicative input. This defines a feedforward closed-loop transfer function, between the loop output and the feedforward controller input. The feedforward controller prevents the frequency sensitivity from substantially varying the feedforward closed-loop transfer function gain and phase within the target frequency range, thus reducing computational burden.
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Ding MingZhong
Min ShuangQuan
Ooi KianKeong
Barger Derek J.
Lucenta David K.
Seagate Technology LLC
Slavitt Mitchell
Sniezek Andrew L.
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