Patent ID: 6975477

Claim:
A servo system for displacing a head relative to a disk of a hard disk drive, comprising: a dual-stage actuator system for moving the head relative to the disk in response to first and second control signals; a calibration signal generator for generating a calibration signal having at least one calibration portion; and a calibration factor generator for generating a calibration factor; whereby the servo system operates in an operating mode in which the first control signal is generated as part of a first servo loop and the second control signal is generated as part of a second servo loop, where the calibration factor is used as one of the parameters of the second servo loop; and the servo system operates in a calibration servo mode in which the first control signal is generated as part of a third servo loop, the calibration signal forms the second control signal, and the calibration factor generator generates the calibration factor based on movement of the head before any substantial response by the third servo loop to the at least one calibration portion of the calibration signal.