Patent ID: 7009804

Claim:
A method of calibrating at least one micro-actuator in a hard disk drive, comprising the steps of: notch filtering a micro-actuator control signal at a frequency to create a notch filtered micro-actuator signal; adding a sinusoidal signal at said frequency to said notch filtered micro-actuator control signal to stimulate said micro-actuator; notch filtering a voice coil control signal at said frequency to create a notch filtered voice coil control signal to stimulate said voice coil; demodulating a PES signal based upon said sinusoidal signal to create a response amplitude at said frequency; decouple filtering of said micro-actuator control signal to create a decoupling micro-actuator feedback signal; removing said PES signal and said decoupling micro-actuator feedback signal to direct control of said voice coil motor; and calculating a stroke sensitivity based upon said response amplitude; wherein said sinusoidal signal has a stimulus amplitude at said frequency; wherein said micro-actuator is coupled with a magnetic head in a head gimbal assembly following a track on a rotating disk surface; wherein said magnetic head follows said track in response to a voice coil motor through stimulation of a voice coil and in response to said micro-actuator; and wherein said PES signal is based upon said magnetic head following a track on said rotating disk surface in response to said notch filtered voice coil control signal and to said notch filtered micro-actuator control signal; wherein said frequency is outside a bandwidth of a servo system in said hard disk drive, and away from any significant excitation resonance of said servo system; wherein said servo system includes control of said voice coil motor, and of said micro-actuator through said head gimbal assembly positioning said magnetic head to follow said track and respond with said PES signal.