System and method for controlling an actuator motor during retract
AssigneeTexas Instruments Incorporated
InventorsMehedi Hassan, Joao Carlos Brito, John K. Rote
Life of this patent
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Abstract
A system and method are provided for controlling operation of an actuator for retracting a read/write head of a hard disk drive system. One aspect of the system and method relates to controlling the actuator in response to a retract request command by first decelerating the actuator for a time period and then braking of the actuator for another time period. Another aspect of the system and method relates to controlling operation of the actuator during retract based on a sensed back EMF relative to a target back EMF, which may be selected by a user.
Claims39
A disk drive read/write head retract system comprising:
- a controller having at least two operating modes in response to a receiving a retract request signal, the controller, when in a first operating mode, being operable to provide a deceleration control signal for decelerating a motor in a selected direction for a first time period, the controller operating in a second operating mode after the first operating mode to provide a brake control signal for braking the motor for a second time period,
- wherein, when in the second operating mode, the brake control signal results in input terminals of the motor being shorted together at a selected voltage level.
A disk drive read/write head retract system comprising:
- a controller having at least two operating modes in response to a receiving a retract request signal, the controller, when in a first operating mode, being operable to provide a deceleration control signal for decelerating a motor in a selected direction for a first time period, the controller operating in a second operating mode after the first operating mode to provide a brake control signal for braking the motor for a second time period,
- back electromotive force (“EMF”) sensor, the back EMF sensor sensing back EMF of the motor and providing a back EMF sensor signal indicative thereof, the controller having a third operating mode after the second operating mode for controlling the motor based on the sensed back EMF relative to a target back EMF.
A disk drive read/write head retract system comprising:
- a controller for controlling energization of a motor;
- a back electromotive force (“EMF”) sensor, the back EMF sensor sensing back EMF of the motor;
- wherein, in response to a retract request signal, the controller is operable to control the motor based on the sensed back EMF relative to a target back EMF value
- a comparator operable to compare the sensed back EMF with the target back EMF value and provide an error signal indicative thereof, the controller controlling the motor based on the error signal;
- and
- a counter operative to Increment or decrement a counter value based on the error signal, the controller controlling the motor based on an adjusted error signal, the adjusted error signal having a value functionally related to the error value and the counter value.
A method for controlling a motor for retracting a read/write head in a disk drive system, the method comprising the steps of:
- decelerating the motor in a first direction for a first time period in response to retract request signal;
- and
- braking the motor for a second time period,
- wherein step of braking is accomplished by electrically shorting together input terminals of the motor to a selected voltage level.
A method for controlling a motor for retracting a read/write head in a disk drive system, the method comprising the steps of:
- decelerating the motor in a first direction for a first time period in response to retract request signal;
- and
- braking the motor for a second time period,
- sensing back electromotive force (“EMF”) of the motor and providing a back EMF sensor signal indicative thereof, after the step of braking, the motor being controller based on the sensed back EMF relative to a target back EMF.
A method for controlling a motor for retracting a read/write head in a disk drive system, the method comprising the steps of:
- sensing back electromotive force (“EMF”) of the motor:
- controlling energization of the motor based on the sensed back EMF relative to a selected target back EMF;
- comparing the sensed back EMF with the target back EMF value and providing an error signal indicative thereof, the motor being controlled based on the error signal;
- and
- incrementing or decrementing a counter value based on the error signal and mathematically adjusting the error signal by an amount functionally related to the counter value to provide an adjusted error signal, the motor being controlled based on the adjusted error signal.
Dependencies are inferred from the claim text.