Seagate Technology Incorporated

Bi Qiang

Xiong Liu

Kevin Arthur Gomez

KianKeong Ooi

MingZhong Ding

Choon Wei Ng

Kang Hai Lim

Chi Zhang

Min Shuangquan

Yuheng Wang

A multi-stage tracking control system includes at least a main actuator and a microactuator. The tracking control system is switched to a single-stage mode so that the main actuator alone provides tracking. A disturbance signal is applied to the microactuator while in the single-stage mode, and a failure condition of the microactuator is determined based on a position error generated in response to the disturbance signal.

Determining microactuator failure in a multi-stage tracking system

A method and disc drive are disclosed that write servo wedges to a plurality of tracks of a disc. A head having a read element offset from a write element reads a servo wedge on a first track as a propagation guide and writes two or more servo wedges to be used as a subsequent propagation guide on a second track, all during one instance of a sector position of the disc rotating by the head. Additionally, a one of the written servo wedges can be radially continuous from the outer to inner diameter and is used for track-following during normal operation. In this manner, all radially continuous servo wedges for each sector of a given track can be written during one revolution of the disc, thereby reducing the amount of time necessary for servowriting.

Method and disc drive for writing servo wedges

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Bi Qiang