Abstract: The present invention offers a time efficient means to determine and eliminate dynamic track squeeze error. The present invention can be used to correct imperfections in tracks written by a conventional servowriter or using self-propagating servo writing. The dynamic track squeeze is determined within a single disc revolution. The read head is positioned half way between two servo tracks. Positioning information for track following is obtained from either track as one disc revolution is completed. During the disc revolution, position measurement is simultaneously collected from both tracks. The difference between the position measurements from each track, which represents the dynamic track squeeze between the two tracks, is determined. An appropriate ZAP correction factor is determined and written to the servo sector of the desired track. The ZAP correction factor is input to the disc drive servo controller and eliminates the dynamic track squeeze.

Abstract: A method and apparatus for controlling acoustic noise generated by a seek operation in a disc drive by using a feedback control system to control the seek operation. The feedback control system is excited by a feed-forward signal during execution of the seek operation. An acoustic factor, which defines a seek operation noise level, is selected. The feed-forward signal is generated based, at least in part, upon the selected acoustic factor. The feed-forward signal has a first derivative having a maximum value. The selected acoustic factor is used to select the maximum value of the first derivative of the feed-forward signal.

Abstract: A method and system for managing the transfer of data into and out of a buffer in a disc drive is disclosed. The operation of the vectored buffer management (VBM) system is administered by a software-based control module. The control module creates and maintains a buffer table by dividing the buffer table into buffer sectors. The buffer sectors are further arranged into buffer segments, or circularly linked lists upon which the buffer table is partitioned. The control module effectuates the transfer by implementing an application module across the buffer table. Once the application module is arbitrarily positioned at an index sector by the control module, data transfer is accomplished when the application module walks through a particular buffer segment identified by the index sector. Specific control of the application module across a buffer segment is administered through host and disc address pointers, which are coupled to host and disc next pointers, respectively.

Abstract: The temperature of an actuator voice coil in a disc drive is regulated so as to prevent outgassing. In a preferred embodiment, coil temperature is calculated at the beginning of each long seek. If the temperature is determined to be at or below a predetermined “safe” level, temperature rise is not limited and power may be applied to the coil without additional limitations. If, however, coil temperature is determined to be above the “safe” level, proportional control is used to scale back power generation so as to prevent the coil temperature from exceeding the coil's specified temperature limit.

Abstract: Methods and systems in a data storage device selectively employ a seek time array and/or a seek time list to accurately predict a time required for a seek operation to move a transducer in the data storage device a given seek distance. The seek time list and/or seek time profiles are automatically compiled in the data storage device based on seek time entries located in a servo data table located in the data storage device.

Abstract: A method and apparatus for simultaneously measuring and calculating servo-related data is disclosed. The method involves measuring the servo related data for a first track of a disc drive and then measuring servo related data for a second track. The method further involves calculating servo related values for the first track, based on the measured servo related data for the first track, while servo related data is being measured for the second track. This method is applicable for processes such as zero acceleration path determination in disc drives, whereby position errors are measured for the first track and then position errors are measured for a second track while simultaneously calculating the zero acceleration path for the first track based on the position errors previously measured.

Abstract: A temperature monitoring method and apparatus is provided in which temperature values are used to optimize temperature-dependent disc drive parameters. The present invention also can be implemented as a computer-readable program storage device which tangibly embodies a program of instructions executable by a computer system to perform a temperature monitoring method.

Abstract: A method and system for providing plant variation compensation for a microactuator in a dual-stage servomechanism of a disc drive. The method includes performing indirect adaptive filtering to identify plant variation in the microactuator, and tuning a compensator for the microactuator based on the plant variation. The indirect adaptive filtering can be performed using a two-stage process, including a first stage of adaptive modeling for the dual-stage servomechanism and a second stage of generating an indirect mode-reference inverse for the microactuator. A combined process can alternatively be employed. The microactuator can be a piezoelectric microactuator which forms a PZT system. The dual-stage servomechanism also includes a coarse actuator such as a voice coil motor.

Abstract: A system and method of verifying data transferred along a data path from one buffer, such as a user buffer in the host system to a second buffer, such as a disc drive buffer on a disc drive system by using the receiving device to test the information and provide a confirmation or error signal to the sending device. The system and method appends non-abstract identification tags to the abstract data in the first buffer, i.e., the data to be stored to and/or read from the storage device. The tags are transmitted along with the abstract data and provide unique information that is used by either the disc drive device or the host system to validate data received from the other. The validation is based on a comparison of the tag values to a predetermined control value that may be received prior to receiving the abstract data.

Abstract: According to one embodiment of the present invention a disc controller in a disc drive includes a cache memory and a control circuit. The control circuit is configured to identify an operating system of a host computer coupled to the disc drive, select a segmentation level for the cache memory based on the identified operating system, and store information in the cache memory according to the segmentation level. According to another embodiment of the present invention a cache memory in a disc drive is operated by identifying an operating system of a host computer coupled to the disc drive, selecting a segmentation level for the cache memory based on the identified operating system, and storing information in the cache memory according to the segmentation level. The operating system is identified by reading a partition type from a master boot record stored in a disc in the disc drive.

Abstract: A system and method of verifying data transferred along a data path from one buffer, such as a user buffer in the host system to a second buffer, such as a disc drive buffer on a disc drive system by using the receiving device to test the information and provide a confirmation or error signal to the sending device. The system and method appends non-abstract identification tags to the abstract data in the first buffer, i.e., the data to be stored to and/or read from the storage device. The tags are transmitted along with the abstract data and provide unique information that is used by either the disc drive device or the host system to validate data received from the other. The validation is based on a comparison of the tag values to a predetermined control value that may be received prior to receiving the abstract data.

Abstract: A method of implementing an automatic acoustic management feature for a disc drive includes receiving an acoustic/performance compromising factor from a host, tuning disc drive performance by applying the factor to a control parameter to generate a modified control parameter, and executing a loop for controlling a disc drive operation using the modified control parameter. In another embodiment, a disc drive has a base, a rotatable disc, an actuator assembly with an arm for carrying a head in transducing relation to the disc in response to a control signal, a receiver for receiving an acoustic/performance compromising factor, and a controller that monitors the position of the arm and generates the control signal. The controller executes a seeking control loop having a control parameter modified by applying a compromising factor to the parameter to tune the acoustic performance of the drive.

Abstract: Monitoring the decay of the magnetic domains and refreshing the magnetic domains when the amount of decay has passed an established threshold allows a means to compensate for the superparamagnetic effect and increase the amount of data stored on a recording media. A high frequency reference signal and a low frequency reference signal can be written onto the magnetic media. The low frequency reference signal corresponds to large magnetic bits on the storage media surface, whereas the high frequency reference signal corresponds to small magnetic bits. Because of the large difference in decay rates between the high frequency and low frequency reference signals, any change in the difference of the two signals over time actually reflects the level of signal degradation that has occurred in the high frequency reference signal.

Abstract: A method of handling multiple resonance frequencies in a disc drive includes monitoring a position error signal (PES) for an actuator arm, generating a plurality of feedforward compensation signals from the PES using a plurality of bandpass filters, and applying the compensation signals to a servo control signal. Each filter has a center frequency that is set to a problematic resonance frequency. The method may also include identifying the problematic frequencies by, for example, commanding a movement of the actuator arm, collecting data points for the PES that are associated with the movement, and performing a digital fourier transform of the data points to identify resonant frequencies. Other methods of identifying problematic frequencies include analyzing PES zero-crossing data, or using principal component analysis.

Abstract: A method and system for determining data sector splits across servo bursts in a disc drive having a data disc with an embedded servo configuration. The disc drive includes a data transducer selectively positionable over the data disc for transferring data to and from the data disc, and the data disc includes a plurality of zones of predefined tracks. The method includes locating one or more frame table parameters based on a new zone position, creating a plurality of new frame table entries, while the disc drive is in operation, based on the frame table parameters, and moving the data transducer from a past zone position to the new zone position. The disc drive includes parameter memory and frame table memory. The parameter memory contains a plurality of zone records, with the zone records containing a plurality of zone table parameters. The frame table memory is utilized to store a frame table.

Abstract: A method and apparatus for normalizing the acceleration constant used by a servo control system in a disc drive are disclosed. The method and apparatus involve performing a test seek and summing the position error measured at sample periods during the deceleration phase of the test seek. A correction factor applied to the acceleration constant is adjusted if the sum of the position errors differs from the sum of position errors measured from a nominal seek. Adjusting the correction factor to cause a position error sum that is close or equal to the sum from the nominal seek provides a relatively symmetrical seek arrival without additional correction factor offsets or gain variances.

Abstract: An information handling system, such as a disc drive, includes a base, a disc stack rotatably attached to the base, and an actuator assembly movably attached to the base, with multiple movable mill-actuator arms mounted on one portion of the actuator assembly. Attached to an end of the actuator is a voice coil which forms a portion of a voice coil motor. Magnets attached to the base form the other portion of the voice coil motor. A current driver for the voice coil delivers an amount of current to the voice coil to move the actuator assembly. Attached to another end of the actuator assembly is one or more transducers. In order to minimize the disturbance of a seeking milli-actuator, the operation to be executed is to cause the first milli-actuator to return slowly to its rest or zero position. A rate of return control circuit is implemented to drive a milli-actuator such that a milli-actuator at a non-zero or non-rest position will be returned to a rest position at a rate slower than a seeking milli-actuator.

Abstract: The present invention is a method of correcting radial position error signal (PES) values by utilizing predetermined error correction values located at predetermined locations in advance of their associated servo fields. Calculated correction values are written to zero-acceleration path (ZAP) fields on the disc during the manufacture process. ZAP fields are positioned before the servo fields whose PES they are designed to correct. The ZAP field is comprised of two or more correction data elements to correct subsequent PES values. As the read/write head flies along a track, it reads a ZAP field, and stores the PES correction data in local random access memory (RAM). Subsequently, the corresponding servo field is read and the stored PES correction data is used to correct the PES. Two types of ZAP fields are written on the disc—one type for read operations, another type for write operations.

Abstract: A method of producing a modified control signal to an actuator arm assembly of a disc drive to reduce RRO includes the step of generating a correction signal corresponding to a position error signal of a current track. Then to determine a high pass filter transfer function of a high pass filter to decrease a gain of an unwanted frequency generated when increasing a learning gain of the correction signal to achieve a faster convergence without any loss of performance in the disc drive. Then to determine filter parameters from the high pass filter transfer function, and to filter the correction signal by passing the correction signal through the high pass filter to generate a modified control signal to the actuator arm assembly of the disc drive using the filtered correction signal to remove the RRO on a next track.

Abstract: Method and apparatus for identifying a resonance by changing a spindle speed, which has the effect of changing a corresponding sampling rate and Nyquist frequency. The invention discriminates (1) between plausible frequencies of true resonance and/or (2) aliased resonance from non-aliased resonances. This is accomplished by monitoring whether and/or how a resonance shifts during this speed change. Methods of the present invention monitor resonances by deriving a resonance indicator such as an apparent frequency (below the Nyquist frequency), a gain or error magnitude (compared to a derived threshold at a calculated frequency of interest), or similar criteria tested by values conventionally illustrated on a Bode plot. The present invention further includes steps or structural features for configuring a controller to attenuate or similarly limit an unwanted frequency component of an actuator control signal. In this way, resonances in the actuator can be reduced, and servo speed and accuracy thereby enhanced.