US 12,254,909 B2
VCM PWM to linear mode transition offset optimization to improve PES
Jaesoo Byoun, Irvine, CA (US); Brian Johnson, Laguna Hills, CA (US); Hideaki Ito, Fujisawa (JP); Gaku Ikedo, Fujisawa (JP); and Naoyuki Kagami, Fujisawa (JP)
Assigned to Western Digital Technologies, Inc., San Joes, CA (US)
Filed by Western Digital Technologies, Inc., San Jose, CA (US)
Filed on Aug. 9, 2023, as Appl. No. 18/446,612.
Application 18/446,612 is a division of application No. 17/742,082, filed on May 11, 2022, granted, now 11,763,843.
Prior Publication US 2023/0386512 A1, Nov. 30, 2023
Int. Cl. G11B 5/55 (2006.01)
CPC G11B 5/5547 (2013.01) [G11B 5/5543 (2013.01)] 20 Claims
OG exemplary drawing
 
1. A data storage device comprising:
one or more disks;
an actuator arm assembly comprising one or more disk heads and a voice coil motor (VCM), the VCM configured to operate in a first mode and a second mode, the first mode and the second mode each comprising one of a pulse width modulation (PWM) mode and a linear or current control loop (CCL) mode, the first mode being different from the second mode; and
one or more processing devices or components, configured, individually or in combination, to:
perform a calibration routine, wherein performing the calibration routine comprises:
identifying a mapping between offset compensation values and a track arrival position error signal (PES), wherein each offset compensation value translates to a current offset applied to the VCM in the first mode or the second mode;
and wherein the mapping is identified by one or more of:
measuring the track arrival PES for one or more of different seek lengths and different directions, the directions selected from a group consisting of an inner diameter (ID) to an outer diameter (OD) direction and an OD to ID direction;
measuring the track arrival PES for different offset compensation values after seek completion; and
incrementally reducing a linear mode time and measuring a corresponding track arrival PES.