Apparatus and method for detecting and compensating for resonance frequency in data storage system

An apparatus to detect a resonance frequency in a disk drive, comprising:

• an excitation unit exciting a head stack assembly by increasing a gain of a predetermined frequency band of a driving signal input to a voice coil motor actuator;
• a resonance frequency detector frequency-transforming a response signal generated by the voice coil motor actuator in response to the driving signal input from the excitation unit and detecting the resonance frequency in a predetermined frequency domain;
• an excitation signal generator separately generating a first excitation signal with the resonance frequency detected by the resonance frequency detector, and a second excitation signal with a frequency obtained by subtracting the resonance frequency from a sampling frequency selected for frequency transformation;
• a mixer combining one of the first excitation signal or the second excitation signal with a driving signal that does not pass through the excitation unit, and inputting a result of combination to the voice coil motor actuator;
• a resonance determination unit determining whether resonance occurs in the system using a response signal generated by the voice coil motor actuator in response to a signal output from the mixer;
• and
• a system controller determining a frequency of one of the first excitation signal or the second excitation signal input when resonance occurs in the system, as the resonance frequency.

An apparatus to compensate for a resonance frequency in a disk drive, comprising:

• a voice coil actuator moving a transducer in response to an actuator driving signal and generating a servo control signal;
• a servo controller generating a servo-driving signal to control the voice coil motor, using the servo control signal;
• a switching unit receiving the servo-driving signal and switching the servo-driving signal to be output to one of a mixer, a boosting filter, or a notch filter in response to a switching control signal;
• the boosting filter increasing a gain of an output of the switching unit within a predetermined frequency band;
• the notch filter filtering a resonance frequency component from the output of the switching unit;
• the mixer mixing an output of one of the group consisting of the switching unit, the boosting filter, and the notch filter, and one of a first excitation signal or a second excitation signal generated by an excitation unit under a predetermined condition, and generating a result of mixture as an actuator driving signal;
• a resonance frequency detector frequency-transforming a response signal output from the voice coil motor actuator in a first period in which the output of the boosting filter is input from the mixer, and detecting a resonance frequency in a predetermined frequency domain;
• a frequency operation unit subtracting the resonance frequency detected by the resonance frequency detector from a sampling frequency selected for frequency transformation by the resonance frequency detector;
• the excitation signal generator separately generating the first excitation signal with the resonance frequency detected by the resonance frequency detector, and the second excitation signal with a frequency that is a result of subtraction performed by the frequency operation unit;
• a resonance determination unit determining whether resonance occurs in the response signal generated by the voice coil motor actuator, in a second period in which one of the first excitation signal or the second excitation signal is generated by the excitation signal generator;
• a system controller generating the switching control signal to control a switching operation of the switching unit according to a predetermined switching sequence, and determining a frequency of one of the first excitation signal or the second excitation signal input when resonance occurs, as the resonance frequency;
• and
• a notch filter coefficient generator determining coefficients of the notch filter such that the notch filter removes a frequency component with the resonance frequency determined by the system controller.

A method of detecting a resonance frequency in a system, comprising:

• boosting on a predetermined frequency band of a driving signal input to the system;
• frequency-transforming a response signal output from the system and detecting a resonance frequency in a predetermined frequency domain;
• separately generating a first excitation signal with the resonance frequency detected, and a second excitation signal with a frequency obtained by subtracting the resonance frequency detected from a sampling frequency for frequency transformation;
• boosting of the predetermined frequency band of the driving signal input to the system, mixing the driving signal and one of the first excitation signal or the second excitation signal, and inputting a result of mixture to the system;
• determining whether resonance occurs in a response signal generated by the system in response to one of the first excitation signal or the second excitation signal;
• and
• determining a frequency of one of the first excitation signal or the second excitation signal input when resonance occurs, as the resonance frequency.

A method of detecting a resonance frequency in a disk drive, comprising:

• boosting on a predetermined frequency band of a driving signal input to a voice coil motor actuator to excite a head stack assembly;
• frequency-transforming a response signal output from the voice coil motor actuator and detecting a resonance frequency in a frequency domain;
• separately generating a first excitation signal with the resonance frequency detected, and a second excitation signal with a frequency obtained by subtracting the resonance frequency detected from a sampling frequency for frequency transformation;
• boosting of the predetermined frequency band of the driving signal input to the voice coil motor actuator, combining the driving signal and one of the first excitation signal or the second excitation signal, and inputting a result of combination to the voice coil motor actuator;
• determining whether resonance occurs in a response signal generated by the voice coil motor actuator in response to one of the first excitation signal or the second excitation signal;
• and
• determining a frequency of one of the first excitation signal or the second excitation signal input when resonance occurs, as the resonance frequency.

A method of compensating for a resonance frequency in a disk drive, comprising:

• boosting on a predetermined frequency band of a driving signal input to a voice coil motor actuator so as to excite a head stack assembly;
• frequency-transforming a response signal output from the voice coil motor actuator and detecting a resonance frequency in a frequency domain;
• separately generating a first excitation signal with the resonance frequency detected, and a second excitation signal with a frequency obtained by subtracting the resonance frequency detected from a sampling frequency for frequency transformation;
• boosting of the predetermined frequency band of the driving signal input to the voice coil motor actuator, mixing the driving signal and one of the first excitation signal or the second excitation signal, and inputting a result of mixture to the voice coil motor actuator;
• determining whether resonance occurs in a response signal generated by the voice coil motor actuator in response to one of the first excitation signal or the second excitation signal;
• determining a frequency of one of the first excitation signal or the second excitation signal input when resonance occurs, as the resonance frequency;
• and
• determining coefficients of a filter that filters the driving signal to remove a frequency component with the resonance frequency determined.

A resonance frequency minimizing system, comprising:

• a controller;
• an input signal adaptation unit coupled to receive control signals from the controller;
• and
• a resonance compensating unit coupled to receive, separately, an unboosted signal, a boosted signal and a notch-filtered signal from the input signal adaptation unit and to detect and compensate for a mechanical resonance frequency in the system.

A computer-readable medium containing computer-readable instructions of a resonance frequency minimizing method for performing:

• implementing a control program that provides control instructions to an input signal adaptation program and a resonance compensating program and that determines whether resonance occurs in the system;
• controlling the input signal adaptation program to selectively output an unboosted signal, a boosted signal and a notch-filtered signal;
• and
• controlling a resonance compensating program that, when resonance occurs, provides information to the input signal adaptation program to facilitate generation of notch filter coefficients to remove a mechanical resonance.