摘要:
A direct access storage device and a method of operation thereof where the output of the circuit which controls energy to the position actuator for the head may be changed at times between receipt of sequential position error signals from the medium. Instead of waiting for the next position error signal, a computation is done based on at least the current position and the desired position of the head as to when the head velocity will be equal to a desired velocity. The optimum time to switch is estimated, the energy required to achieve a predetermined velocity and a predetermined offset with respect to the desired position are computed, and operation is conducted accordingly. The amount of energy may again be changed at a time subsequent to the estimated time. The predetermined velocity and the predetermined offset may be zero or may have values other than zero in accordance with the requirements of the track following controller.
摘要:
A method for predicting and avoiding data errors by predicting disk drive read-write inhibit requirements in response to at least two parameters including a head position error and velocity with respect to the track centerline. A write or read inhibit signal is generated in response to selected combinations of these parameters to minimize soft read errors arising from track misregistration and to avoid hard errors arising from overwriting data recorded in an adjacent track. The read and write inhibit strategy is described as a pair of linguistic control rules suitable for implementation in a Fuzzy Logic Controller.
摘要:
A disk drive system, includes a head, a controller for controlling an operation of the head, at least one feedback filter coupled in relation to the controller, and a mechanism for keeping a function of the at least one of the feedback filter active during any of an absence of a valid position error signal (PES) and a position error signal being unavailable due to a defect during an operation of the head.
摘要:
In a direct access storage device including a rotating disk, a head positioned for interaction with said disk, an actuator for carrying said head and a servo system for operating said actuator so as to follow a substantially circular track on said disk by responding to a position error signal, a method for reducing response of the servo system to radial runout of the circular tracks, comprising the steps of obtaining radial runout data; filtering the data; storing the filtered data; subtracting the filtered data from the position error signal to obtain a corrected position error signal; and using the corrected position error signal to control the servo system. A direct access storage device in accordance with the invention includes means for obtaining radial runout data; means for filtering the data; means for storing the filtered data; means for subtracting the filtered data from the position error signal to obtain a corrected position error signal; and means for controlling the servo system using the corrected position error signal.
摘要:
In an idle state, servo information from all sectors is not used, but the servo information from every other sector or from every three or more sectors is used so that head positioning can be performed with only a minimum amount of servo information. The power to the electric circuitry of a write or read system and a servo system, which is not needed in the idle state, is interrupted, from the arrival of the selected servo information to the arrival of the next selected servo information, by a power control signal generated in accordance with the timing of the sectors. The power consumption can be reduced by the amount corresponding to turning off the circuitry not needed, plus the amount needed for computing for position control.
摘要:
Methods and systems for detecting and correcting for undesirable vibrations impacting the servo systems in data storage devices. A detection technique is provided wherein a detection filter is configured to scan a position signal of the servo system across a range of frequencies, and, at each respective scanned frequency, record an amplitude associated therewith. The recorded amplitudes are examined to determine whether any exceed a threshold, thereby locating a peak frequency of the vibration. Using the detected peak frequency of the vibration, a corrective filter is configured to operate about the peak frequency of vibration, thereby reducing its impact on the position signal in the servo system. Optimum detection and correction filter structures are disclosed, as are techniques for addressing filter state vectors as initial conditions as the corrective filters are repeatedly engaged during successive settle-out and track follow cycles (between seeks), as are continuous adaptation techniques for changing vibration environments.
摘要:
A method and system for reducing positioning noise in a data storage system are provided. An access device is positioned over a data storage medium using a stream of bursts stored on the medium. The bursts are sensed at a frequency determined by the rate at which the medium is moved relative to a sensing device. Output positioning values are provided to position the access device at a frequency higher than the frequency at which the positioning bursts are sensed, and/or at random times. The random times may be calculated as random advances or delays from time points occurring at a fixed frequency.
摘要:
A method and apparatus, in a direct access storage device including a head positioned for interaction with a data storage medium mounted on a rotating spindle, an actuator for positioning the head, and a servo control loop for positioning the actuator. The improvement comprises: a narrow band gain enhancing filter for connection in the servo control loop. The filter has a response frequency related to the rotational frequency of the spindle. The filter has programmable initial states. Also provided is a switch for switching in the narrow band filter as the head approaches a target position on the data storage medium. Initial states of the filter are determined and supplied to program the filter. At least one additional filter having a peak response frequency at a harmonic of the frequency of rotation of the spindle, may be provided. Initial states of the additional filters are determined and supplied to program the additional filter. The filter may include successive delay circuits for inputs to the filter, which circuits provide delayed outputs; multipliers for multiplying selected delayed outputs by a constant; and a summer for summing the delay outputs after the delayed outputs are multiplied by the multipliers. The initial states may be stored as phase, frequency and amplitude of a sine function.
摘要:
A disk drive with reduced seek acoustic noise and a method for implementation, without any additional hardware or mechanical modifications to the actuator includes a filter such that servo-loop stability is unaffected. The filter is inserted outside the existing servo loop to reshape the existing velocity profile in real time and to facilitate the suppression of forcing components that produce seek acoustics. A weighting factor may be used to provide a weighted average of the filtered and unfiltered velocity reference signal to the servo loop so that at the end of a track seek operation, the unfiltered reference signal is applied to the velocity servo, and there is almost no change in settle-out performance when the target track is reached. It is not necessary to store large volumes of velocity profile data to deal with different seek lengths.
摘要:
In a direct access storage device having a head for interaction with a storage medium and a moving actuator on which the head is mounted, the improvement comprises a compound bearing system for the actuator, the bearing system including a first bearing of low friction for small movements of the actuator; and a second bearing of higher friction for coarse movements of the actuator. The storage medium is preferably a rotating magnetic disk having a series of concentric circular tracks. A single servo system drives the actuator so that the head follows a selected track with motion of the first bearing, and movement of the head to a new track causes motion of the second bearing. Preferably the first bearing is a flex bearing and the second bearing is a ball bearing.