Method and apparatus for providing a variable rate oversampling digital filter for resonance compensation in disk drive servo control systems

A method for providing a variable rate oversampling digital filter for resonance compensation in a disk drive, comprising:

• receiving first position information;
• in response to said first position information, generating a first control command;
• filtering said first control command;
• outputting a first filtered control command;
• outputting a second filtered control command;
• receiving second position information, wherein a time between said first and second position information defines a first sampling period, and wherein a time between said step of outputting said first filtered control command and said step of outputting said second filtered control command does not equal one-half of said first sampling period;
• outputting a third filtered control command after said step of receiving second position information;
• and
• wherein a product of an output level of said first control command and one half said first sampling period plus a product of an output level of said second control command and one half said first sampling period equals a first amount, said method further comprising:
• proportioning one of said first and second filtered control commands, wherein said time between said step of outputting said first filtered control command and said step of outputting said second filtered control command defines a first output period, wherein a time between said step of outputting said second filtered control command and said third filtered control command defines a second output period, wherein a product of an output level of said first control command and said first output period plus a product of an output level of said first control command and said second output period is equal to said first amount.

A method for providing a variable rate oversampling digital filter for resonance compensation in a disk drive, comprising:

• receiving first position information;
• in response to said first position information, generating a first control command;
• filtering said first control command;
• outputting a first filtered control command;
• outputting a second filtered control command;
• receiving second position information, wherein a time between said first and second position information defines a first sampling period, and wherein a time between said step of outputting said first filtered control command and said step of outputting said second filtered control command does not equal one-half of said first sampling period;
• and
• proportioning an output of said first filtered control command, wherein said proportioned output of said first filtered control command y′(kT) is given by the expression y′(kT)=y(kT+T/2)+(y(kT)−y(kT+T/2))*((T/2)/T1), wherein T is equal to said first sampling period, wherein y(kT+T/2) is an output of said second filtered control command, wherein y(kT) is an output of said first filtered control command and wherein T1 is an output period of said first control command.

A method for providing a variable rate oversampling digital filter for resonance compensation in a disk drive, comprising:

• receiving first position information;
• in response to said first position information, generating a first control command;
• filtering said first control command;
• outputting a first filtered control command;
• outputting a second filtered control command;
• receiving second position information, wherein a time between said first and second position information defines a first sampling period, and wherein a time between said step of outputting said first filtered control command and said step of outputting said second filtered control command does not equal one-half of said first sampling period;
• and
• proportioning an output of said second filtered control command, wherein said proportioned output of said second filtered control command y′(kT+T1) is given by the expression y′(kT+T1)=y(kT)+(y(kT+T/2)−y(kT))*((T/2)/T2), wherein T is equal to said first sampling period, wherein y(kT) is an output of said first filtered control command, wherein y(kT+T/2) is an output of said second filtered control command and wherein T2 is an output period of said second control command.

A method for filtering control values in a hard disk drive, comprising:

• receiving a position command at a controller at a first rate, wherein said first rate defines a first period;
• for each of a plurality of position commands received at said controller, generating an unfiltered control command in said controller;
• receiving said unfiltered control command at a filter;
• generating a first filtered control command in said filter for said position command received at said controller;
• after said step of generating a first filtered control command, generating a second filtered control command in said filter for said position command received at said controller;
• outputting said first filtered control command for a first length of time;
• and
• outputting said second filtered control command for a second length of time, wherein said first length of time is not equal to said second length of time, and wherein a sum of said first length of time and said second length of time is approximately equal to said first period.

A method for providing an oversampled control output signal in a hard disk drive, comprising:

• receiving a first positioning signal, wherein a time between receiving said first positioning signal and receiving a second positioning signal defines a sampling period;
• filtering said first positioning signal, wherein said step of filtering said first positioning signal comprises:
• calculating a first control output;
• calculating a second control output;
• proportioning said first control output to obtain a proportioned first control output;
• outputting said first proportioned control output for a first time period, wherein said first time period does not equal one-half of said sampling period;
• outputting said second control output for a second time period, wherein said second time period is not equal to one-half of said sampling period, wherein a product of said first proportioned control output and said first period of time plus a product of said second control output and said second period of time is equal to a product of said first control output and one half said sampling period plus a product of said second control output and one half said sampling period.

A method for providing an oversampled control output signal in a hard disk drive, comprising:

• receiving a first positioning signal, wherein a time between receiving said first positioning signal and receiving a second positioning signal defines a sampling period;
• filtering said first positioning signal, wherein said step of filtering said first positioning signal comprises:
• calculating a first control output;
• calculating a second control output;
• outputting said first control output for a first time period, wherein said first time period does not equal one-half of said sampling period;
• proportioning said second control output to obtain a second proportioned control output;
• and
• outputting said second control output for a second time period, wherein said second time period is not equal to one-half of said sampling period, wherein a product of said first control output and said first period of time plus a product of said second proportioned control output and said second period of time is equal to a product of said first control output and one half said sampling period plus a product of said second control output and one half said sampling period.

A variable rate oversampling digital filter for resonance compensation in a hard disk drive apparatus, comprising:

• a controller;
• a filter;
• a first magnetic storage disk, comprising a plurality of servo sectors;
• a first actuator arm;
• an actuator for positioning said first actuator arm with respect to said first magnetic storage disk;
• a first transducer head mounted to a first end of said actuator arm;
• and
• a spindle motor for rotating said first magnetic storage disk relative to said first transducer head, wherein position data read from said plurality of servo sectors by said first transducer head is received at said controller at a first rate to define a first period, wherein a portion of said first period comprises an interrupt service routine period, wherein during said interrupt service routine period a plurality of filtered transducer arm control outputs are initiated in response to said position data contained in one of said servo sectors, wherein each of said plurality of filtered transducer arm control outputs defines a length of time, during which it is output, and when at least two of said lengths of time are not substantially equal to each other.

A variable rate oversampling digital filter for resonance compensation in a hard disk drive apparatus, comprising:

• a controller;
• a filter;
• a first magnetic storage disk, comprising a plurality of servo sectors;
• a first actuator arm;
• an actuator for positioning said first actuator arm with respect to said first magnetic storage disk;
• a first transducer head mounted to a first end of said actuator arm;
• a spindle motor for rotating said first magnetic storage disk relative to said first transducer head, wherein position data read from said plurality of servo sectors by said first transducer head is received at said controller at a first rate to define a first period, wherein a portion of said first period comprises an interrupt service routine period, wherein during said interrupt service routine period a plurality of filtered transducer arm control outputs are initiated in response to said position data contained in one of said servo sectors;
• and
• wherein an output of a first filtered control command y′(kT) is proportioned according to the expression y′(kT)=y(kT+T/2)+(y(kT)−y(kT+T/2))*(T/2)/T1), wherein T is equal to said first period, wherein y(kT+T/2) is an output of a second filtered control command, wherein y(kT) is an output of said first filtered control command prior to said step of proportioning, and wherein T1 is an output period of said first control command.

A variable rate oversampling digital filter for resonance compensation in a hard disk drive apparatus, comprising:

• a controller;
• a filter;
• a first magnetic storage disk, comprising a plurality of servo sectors;
• a first actuator arm;
• an actuator for positioning said first actuator arm with respect to said first magnetic storage disk;
• a first transducer head mounted to a first end of said actuator arm;
• a spindle motor for rotating said first magnetic storage disk relative to said first transducer head, wherein position data read from said plurality of servo sectors by said first transducer head is received at said controller at a first rate to define a first period, wherein a portion of said first period comprises an interrupt service routine period, wherein during said interrupt service routine period a plurality of filtered transducer arm control outputs are initiated in response to said position data contained in a one of said servo sectors;
• and
• wherein an output of a second filtered control command y′(kT+T1) is proportioned according to the expression y′(kT+T1)=y(kT)+(y(kT+T/2)−y(kT))*(T/2)/T2), wherein T is equal to said first period, wherein y(kT) is an output of a first filtered control command, wherein y(kT+T/2) is an output of said second filtered control command prior to said step of proportioning, and wherein T2 is an output period of said second control command.