Abstract: A disk apparatus control device including an A/D converting section that samples an analog current amount signal indicating a current amount for a drive current of a motor that moves a head for accessing a storage disk of a disk apparatus, and converts the analog current amount signal into a digital current amount signal indicating the current amount. The device can further include a control signal generating section that, according to digital control, generates a digital control signal corresponding to a manipulation amount of the drive current, based on a difference between the current amount indicated by the digital current amount signal and a target value for the current amount of the drive current. Additionally, the device can include a D/A converting section that converts the digital control signal into an analog control signal, and outputs the analog control signal to a drive current generating section that generates the drive current.

Abstract: Methods, systems, and computer program products for compensating unstable linear time-invariant due to input nonlinearities are described. In one implementation, compensating a controlled device may include controlling the controlled device using feedforward control. In another implementation, compensating the controlled device may include controlling the controlled device using feedback control.

Abstract: In some implementations, a method includes receiving rotational speed information corresponding to a rotational speed of a spindle motor having a plurality of poles, down sampling the rotational speed information to obtain speed-related information associated with the spindle motor, and adjusting the rotational speed of the spindle motor based on the speed-related information.

Abstract: In some implementations, a recording medium includes a plurality of data areas, a plurality of data area separating sections, and one or more blank zones. Each data area is configured to store data. Each data area separating section is disposed between the data areas and extends in parallel with respect to the data areas. Each data area separating section is configured to prevent data from being written into the data area separating section. Each blank zone extends in a direction perpendicular to the data areas and is configured to record written data.

Abstract: Systems, methods and computer program products for removing speed adjustment errors attributed by pole asymmetry are described. In some implementations, the spindle motor speed can be down sampled. Down sampling the spindle motor speed can include determining the spindle motor speed every two (or multiple of two) electrical cycles. Determining the spindle motor speed every two electrical cycles can lead to an accurate determination of the actual spindle motor speed, as the timing and position differences between two adjacent poles can be equalized (e.g., timing and position errors associated with the second pole can be used to cancel out the timing and position characteristics errors with the first pole).

Abstract: A system includes a speed control module, a repeatable component measuring module, and a repeatable component correcting module. The speed control module controls a speed of a motor based on an error signal generated based on a desired speed and back electromotive force. The error signal includes a repeatable component of noise. The repeatable component measuring module measures the repeatable component. The repeatable component correcting module corrects the repeatable component based on transfer characteristics of the speed control module and the motor and generates a corrected repeatable component.

Abstract: Methods, systems and computer program products for measuring a distance between a write head and a read head are described. The measured distance allows the position of the write head (e.g., during writing) and read head (e.g., during reading) to be compensated. The compensation further allows a hard disk drive to accurately position the read head over a desired sector without displacing the write head from the sector.

Abstract: A system including an error signal generating module to generate an error signal based on (i) back electromotive force sensed from a motor and (ii) a predetermined speed of the motor. The error signal includes noise due to mismatched poles of the motor. A noise elimination module eliminates components of the noise having frequencies N times a frequency of rotation of the motor from the error signal and generates a corrected error signal, where N is an integer greater than or equal to zero. A control module generates a first control signal based on components of the corrected error signal, generates a second control signal based on components of the error signal, and rotates the motor at the predetermined speed based on (i) the first control signal and (ii) the second control signal. The components of the corrected error signal have higher frequencies than the components of the error signal.

Abstract: A system including a self-servo-write, a position measuring module, and a compensation module. The self-servo-write module is configured to position a head of a hard disk drive to write a first set of servo wedges on a magnetic medium of the hard disk drive. The position measuring module is configured to measure a first position of the head when the head writes the first set of servo wedges on the magnetic medium. The compensation module is configured to generate first data to compensate a repeatable error based on the first position of the head measured by the position measuring module. The first data to compensate the repeatable error is written on the magnetic medium along with the first set of servo wedges.

Abstract: An evaluation apparatus for evaluating a transfer characteristic of a controlled object of a controller is disclosed. The evaluation apparatus includes a response detection section that detects an input/output response of a control system, based on a signal detected in the control system. The control system includes the controller and the controlled object. The evaluation apparatus further includes a transfer characteristic calculating section that calculates the transfer characteristic of the controlled object, based at least on the input/output response.

Abstract: A system includes a control module configured to generate a first signal to control a speed of an actuator arm of a rotating storage device. An estimating module includes a first filter configured to generate a first filtered output based on the first signal. A second filter is configured to generate a second filtered output based on the speed of the actuator arm. The estimating module is configured to estimate a force to move the actuator arm based on (i) the first filtered output and (ii) the second filtered output. The first filter and the second filter include infinite impulse response (IIR) filters of Pth order, where P is an integer greater than 1.

Abstract: A system includes a control module configured to generate a first signal to control a speed of an actuator arm of a rotating storage device. An estimating module includes a first filter configured to generate a first filtered output based on the first signal. A second filter is configured to generate a second filtered output based on the speed of the actuator arm. The estimating module is configured to estimate a force to move the actuator arm based on (i) the first filtered output and (ii) the second filtered output. The first filter and the second filter include infinite impulse response (IIR) filters of Pth order, where P is an integer greater than 1.

Abstract: A system includes a control module and an estimating module. The control module controls a speed of an actuator arm when the actuator arm moves from a parked position to an edge of a rotating storage medium and generates an arm control signal. The estimating module estimates a force to move the actuator arm based on the arm control signal and the speed, and generates an estimated force signal that adjusts the arm control signal.

Abstract: A system includes a servo writing module, a position measuring module, and a compensation module. The servo writing module writes a first set of servo wedges on a magnetic medium of a hard disk drive (HDD) using a head of the HDD. The position measuring module measures a position of the head when the head writes the first set of servo wedges and generates a first measured head position. The compensation module generates first compensation data based on the first measured head position to compensate a repeatable error component of the first measured head position. The servo writing module writes the first compensation data on the magnetic medium when writing the first set of servo wedges and writes second compensation data generated based on the first set and the first compensation data read from the magnetic medium when writing a second set of servo wedges on the magnetic medium.

Abstract: A system includes a control module and an estimating module. The control module controls a speed of an actuator arm when the actuator arm moves from a parked position to an edge of a rotating storage medium and generates an arm control signal. The estimating module estimates a force to move the actuator arm based on the arm control signal and the speed, and generates an estimated force signal that adjusts the arm control signal.

Abstract: The position error signal (PES), representing relative position regarding position information (RRO) previously recorded on a magnetic disk and the magnetic head, is averaged in each servo sector by an averaging unit, and a control input is obtained based on the PES by a phase compensator and the control input undergoes an averaging process in each servo sector by another averaging unit. Convolution integration with respect to the signal data processed by those averaging units is carried out by using a transfer characteristic formed by adding 1 to an open-loop transfer characteristic, which is determined by a magnetic head actuator model and a servo control circuit, to obtain a synchronous vibration estimate. This estimate undergoes a high-pass filtering process of a zero phase error characteristic by the filter unit to remove the vibration component of low frequency band and to thereby obtain a synchronous vibration learned value with high precision.

Abstract: A positioning control method of a magnetic disc apparatus is provided which can permit fast and stable settling to a target position without overshoot or undershoot in connection with a moving distance of one track seek to about 16-track seek for which positioning must be determined within a moving time corresponding to a resonance frequency of a mechanical system. Such a method can also generate a position/velocity orbit for reducing power at a specified frequency, provide acceleration feed-forward compensation which can permit a head to accurately reach the target position even when the feedback system does not function under a condition that external disturbance does not act and generate a position orbit corrected by a controlled object model accurately modeling resonance oscillation up to a moving frequency band are used in combination.

Abstract: Settling response characteristics after change-over from a speed controller to a position controller is attained. Fluctuations in a time taken until change-over is made from the speed controller to the position controller are reduced to stabilize a moving time and to shorten an access time. To this end, a position controller generates a drive signal of a linear or primary function of time in such a manner that a position deviation signal responds to it with a ternary-order function of time which becomes zero in a desired finite settling time. Further, a feedforward signal generator is provided to reduce a follow-up error to a target position signal as an output of a target position signal generator.

Abstract: The position error signal (PES), representing relative position regarding position information (RRO) previously recorded on a magnetic disk and the magnetic head, is averaged in each servo sector by an averaging unit, and a control input is obtained based on the PES by a phase compensator and the control input undergoes an averaging process in each servo sector by another averaging unit. Convolution integration with respect to the signal data processed by those averaging units is carried out by using a transfer characteristic formed by adding 1 to an open-loop transfer characteristic, which is determined by a magnetic head actuator model and a servo control circuit, to obtain a synchronous vibration estimate. This estimate undergoes a high-pass filtering process of a zero phase error characteristic by the filter unit to remove the vibration component of low frequency band and to thereby obtain a synchronous vibration learned value with high precision.

Abstract: There is provided a positioning control method of magnetic disc apparatus which can permit fast and stable settling to a target position without overshoot or undershoot in connection with a moving distance of one track seek to about 16-track seek for which positioning must be determined within a moving time corresponding to a resonance frequency of a mechanical system. (1) a method of generating a position/velocity orbit for reducing power at a specified frequency, (2) a method of generating acceleration feed-forward compensation which can permit a head to accurately reach the target position even when the feedback system does not function under a condition that external disturbance does not act and (3) a method of generating a position orbit corrected by a controlled object model accurately modeling resonance oscillation up to a moving frequency band are used in combination.