The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jun. 09, 2015
Filed:
Aug. 14, 2012
Qingwei Jia, Singapore, SG;
Shuyu Cao, Singapore, SG;
Guoxiao Guo, Irvine, CA (US);
Jie Yu, Irvine, CA (US);
Qingwei Jia, Singapore, SG;
Shuyu Cao, Singapore, SG;
Guoxiao Guo, Irvine, CA (US);
Jie Yu, Irvine, CA (US);
Western Digitial Technologies, Inc., Irvine, CA (US);
Abstract
A disk drive is disclosed comprising a disk comprising a plurality of servo tracks defined by servo sectors recorded around the circumference of the disk at a servo sampling frequency, and a servo control system operable to actuate a head over the disk by generating a control signal applied to an actuator. A first sinusoid is injected into the servo control system and a first DC component (dc1) is measured in the control signal. A second sinusoid is injected into the servo control system and a second DC component (dc2) is measured in the control signal, wherein the second sinusoid comprises a phase offset from the first sinusoid. A resonance mode of the servo control system is measured based on dc1 and dc2.