Methods and devices for controlling a head position actuator of a disk drive
First Claim
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1. A method of moving a disk drive head, comprising the steps of:
- rotating a disk having servo information;
determining an intermediate state based on a seek length;
determining a first number of discrete time intervals based on the seek length, wherein the first number of discrete time intervals corresponds to a first time to reach an intermediate state from an initial state;
determining a first set of command signals for moving the disk drive head to the intermediate state, wherein the first set of command signals is a function of at least one characteristic of an actuator;
applying the first set of command signals to the actuator to move the disk drive head to the intermediate state, the disk drive head having a non-zero velocity at the intermediate state;
reading the servo information from the disk at a discrete time interval;
determining a second number of discrete time intervals, wherein the second number of discrete time intervals corresponds to a second time to reach a final state from the intermediate state;
determining a second set of command signals as a function of the servo information, further characterized by;
generating a first matrix of state vectors, each state vector representing at least one parameter selected from position, velocity, and acceleration of the disk drive head;
generating a second matrix of values corresponding to at least one characteristic of the actuator, wherein the first and second matrices form a series of equations describing actuator motion with respect to the disk; and
generating control update signals as a function of the first and second matrices, wherein the control update signals force the actuator from the intermediate state to the final state within the first number of discrete time intervals and with zero state error; and
applying the second set of command signals to the actuator to move the disk drive head from the intermediate state to the final state without stopping prior to arriving at the final state; and
wherein the actuator moves from the initial state to the intermediate state within the first number of discrete time intervals; and
wherein the actuator moves from the intermediate state to the final state within the second number of discrete time intervals.
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Abstract
A data storage apparatus includes a servo controller (160) coupled to an actuator (190). The servo controller (160) provides control command signals to the actuator (190) to move a head from an initial position to a final position at a discrete time interval. A method of moving at least one head of a disk drive is also provided. The method includes the step of moving the head from an initial track to a final track without utilizing a separate track acquisition operation to position the head over the final track.
15 Citations
30 Claims
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1. A method of moving a disk drive head, comprising the steps of:
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rotating a disk having servo information;
determining an intermediate state based on a seek length;
determining a first number of discrete time intervals based on the seek length, wherein the first number of discrete time intervals corresponds to a first time to reach an intermediate state from an initial state;
determining a first set of command signals for moving the disk drive head to the intermediate state, wherein the first set of command signals is a function of at least one characteristic of an actuator;
applying the first set of command signals to the actuator to move the disk drive head to the intermediate state, the disk drive head having a non-zero velocity at the intermediate state;
reading the servo information from the disk at a discrete time interval;
determining a second number of discrete time intervals, wherein the second number of discrete time intervals corresponds to a second time to reach a final state from the intermediate state;
determining a second set of command signals as a function of the servo information, further characterized by;
generating a first matrix of state vectors, each state vector representing at least one parameter selected from position, velocity, and acceleration of the disk drive head;
generating a second matrix of values corresponding to at least one characteristic of the actuator, wherein the first and second matrices form a series of equations describing actuator motion with respect to the disk; and
generating control update signals as a function of the first and second matrices, wherein the control update signals force the actuator from the intermediate state to the final state within the first number of discrete time intervals and with zero state error; and
applying the second set of command signals to the actuator to move the disk drive head from the intermediate state to the final state without stopping prior to arriving at the final state; and
wherein the actuator moves from the initial state to the intermediate state within the first number of discrete time intervals; and
wherein the actuator moves from the intermediate state to the final state within the second number of discrete time intervals. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A system for controlling the position of a disk drive head, comprising:
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an adapter for receiving a rotatable data storage disk having a plurality of annular data tracks for storing data;
a disk drive head;
an actuator for moving the disk drive head to a track of the rotatable data storage disk;
control circuitry, operatively coupled to the actuator, generating a first set of command signals for moving the disk drive head from an initial state to an intermediate state within a first number of discrete time intervals based on a seek length, and generating, based on a track position signal, a second set of command signals for moving the disk drive head from the intermediate state to a final state within a second number of discrete time intervals based on an order of the actuator, where the order of the actuator is the number of variables corresponding to at least one actuator parameter selected from supply voltage, actuator gain, and mechanics of the disk drive head; and
an estimator, operatively coupled to the disk drive head, for generating the track position signal as a function of the position of the disk drive head; and
wherein actuator motion is determined by a series of equations defining control update signals, the series of equations comprising;
a first matrix of state vectors, each state vector representing at least one parameter selected from position, velocity, and acceleration of the disk drive head;
a second matrix of values corresponding to at least one characteristic of the actuator, wherein the first and second matrices form a series of equations describing actuator motion with respect to the disk; and
control update signals as a function of the first and second matrices, wherein the control update signals force the actuator from the intermediate state to the final state within the second number of discrete time intervals. - View Dependent Claims (13, 14)
generate the first matrix of state vectors;
generate the second matrix of values; and
generate the control update signals.
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14. The system of claim 13 wherein the second matrix is an N×
- N matrix, where N is the order of the actuator and the order of the actuator is the number of variables in the first matrix, wherein the variables describe the actuator using at least one parameter selected from supply voltage, actuator gain, and mechanics of the disk drive head.
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15. A method of moving a head of a disk drive to a selected track of a disk comprising the steps of:
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determining a first number of discrete time intervals based on a seek length, wherein the first number of discrete time intervals corresponds to a first time to reach a selected state from a first state;
determining a second number of discrete time intervals, wherein the second number of discrete time intervals corresponds to a second time to reach a final state from the selected state;
determining a series of equations defining control update signals, the series of equations comprising;
a first matrix of state vectors, each state vector representing at least one parameter selected from position, velocity, and acceleration of the disk drive head;
a second matrix of values corresponding to at least one characteristic of the actuator, wherein the first and second matrices form a series of equations describing actuator motion with respect to the disk; and
control update signals as a function of the first and second matrices, wherein the control update signals force the actuator from the selected state to the final state within the second number of discrete time intervals;
moving the head from a first state to the selected state based on the control update signals; and
moving the head from the selected state to the final state based on the control update signals, the final state being at a discrete time interval, the head of the disk drive having a non-zero velocity at the selected state. - View Dependent Claims (16, 17, 18, 19)
generating the first matrix of state vectors;
generating the second matrix of values;
generating the control update signals.
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17. The method of claim 15 wherein the discrete time interval comprises one of a sample time and a control update time.
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18. The method of claim 15 wherein the head is moved from the selected state to the final state with maximum control commands.
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19. The method of claim 15 further comprising the step of accelerating the head for a first time period, and decelerating the head for a second time period to reach the final state, wherein the first and second time periods are approximately equal.
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20. A data storage apparatus comprising:
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an actuator for moving a head; and
a servo controller coupled to the actuator, the servo controller providing control command signals to the actuator to move the head from an initial position to an intermediate position within a first number of discrete time intervals based on a seek length, and to move the head from the intermediate position to a final position within a second number of discrete time intervals, the head having a non-zero velocity at all times while moving from the initial position to the final position;
wherein a series of equations defines the control command signals, the series of equations comprising;
a first matrix of state vectors, each state vector representing at least one parameter selected from position, velocity, and acceleration of the disk drive head;
a second matrix of values corresponding to at least one characteristic of the actuator, wherein the first and second matrices form a series of equations describing actuator motion with respect to the disk; and
control command signals as a function of the first and second matrices, wherein the control command signals force the actuator from the intermediate position to the final position within the second number of discrete time intervals.
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21. A method for performing a seek to move a disk drive head from an initial state to a final state comprising the steps of:
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determining the length of the seek;
determining an intermediate state based on the length of the seek;
determining a series of equations defining control update signals, the series of equations comprising;
a first matrix of state vectors, each state vector representing at least one parameter selected from position, velocity, and acceleration of the disk drive head;
a second matrix of values corresponding to at least one characteristic of the actuator, wherein the first and second matrices form a series of equations describing actuator motion with respect to the disk; and
control update signals as a function of the first and second matrices, wherein the control update signals force the actuator from the intermediate state to the final state within a second number of discrete time intervals;
generating a first set of actuator signals to move the head from the initial state to the intermediate state within a first number of discrete time intervals based on seek length; and
generating a second set of actuator signals to move the head from the intermediate state to a final state within a second number of discrete time intervals, the head having a non-zero velocity while traversing from the initial state to the final state. - View Dependent Claims (22, 23, 24, 25, 26, 27, 28, 29)
generating the first matrix of state vectors;
generating the second matrix of values;
generating the control update signals.
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25. The method of claim 24 wherein the second matrix is an N×
- N matrix, where N is the order of the actuator, wherein the order of the actuator is the number of variables in the first matrix and wherein the variables describe the actuator using at least one parameter selected from supply voltage, actuator gain, and mechanics of the disk drive head.
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26. The method of claim 21 further comprising the steps of:
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varying at least one actuator parameter selected from supply voltage, actuator gain, and mechanics of the disk drive head;
analyzing variations in the second matrix in response to the step of varying at least one actuator parameter; and
determining critical parameter variations of the actuator, wherein critical parameter variations prevent the actuator from reaching the final state with zero state error.
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27. The method of claim 25 further comprising the step of:
updating the second matrix to reflect the critical parameter variations of the actuator.
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28. The method of claim 25 wherein the steps of generating the first and second sets of actuator signals are further characterized by:
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generating a first and second set of control signals; and
amplifying the first and second set of control signals using a signal amplifier.
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29. The method of claim 28 wherein the step of generating a second matrix of values corresponding to at least one parameter of an actuator is further characterized by:
generating the second matrix values corresponding to at least one parameter of the signal amplifier.
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30. A method of moving a head of a disk drive, comprising the steps of:
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determining a first number of discrete time intervals based on a seek length, wherein the first number of discrete time intervals corresponds to a first time to reach an intermediate track from an initial track;
determining a second number of discrete time intervals based on an order of the actuator, wherein the order of the actuator is the number of variables to describe the actuator using at least one parameter selected from supply voltage, actuator gain, and mechanics of the disk drive head, wherein the second number of discrete time intervals corresponds to a second time to reach a final track from the intermediate track; and
moving the head from the initial track to the final track without utilizing a separate track acquisition operation to position the head over the final track, the head having a non-zero velocity during the time period of traversing from the initial track to the final track.
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Specification