Abstract: A voltage-mode VCM controller is provided comprising an Infinite Impulse Response (IIR) filter that modifies a servo control voltage signal to a voltage driver in response to an adaptive compensator that configures the IIR filter in relation to an observed VCM velocity and an actual VCM velocity. An associated method is provided comprising modeling a velocity response of a VCM to a voltage input; inputting the observed velocity and an actual VCM velocity to an adaptive compensator that computes a gain and a VCM response pole frequency in relation to the VCM resistance and inductance; configuring an IIR filter in relation to the computed gain and pole frequency values; and using the IIR filter to modify a voltage command from a servo controller to a power driver.

Abstract: A method of determining and monitoring head polarity of data heads comprises performing a head polarity detection routine. The head polarity detection routine comprises the step of setting a read gate period duration to a first value. The routine also comprises searching for a good address mark signal during a first read gate period with a channel polarity set to a first polarity. The routine further comprises identifying a polarity of a data head based upon the channel polarity when the good address mark is detected.

Abstract: A method and apparatus for compensating for the asymmetrical phases of a spindle motor in a disc drive are provided. With the apparatus and method, compensation values are learned by sampling speed data during a period of operation of the disc drive where the speed is stable and only one control operation is performed per revolution of the disc. The sampled speed data is used to generate the compensation values for each of the phases of the spindle motor. The compensation values are stored in a compensation mechanism which is used by the spindle motor speed controller to provide compensation for the asymmetrical phases of the spindle motor. During Normal operation, the actual speed output of the spindle motor is measured and is subtracted from a reference speed to generate a difference speed value. Based on the corresponding electrical phase, the correct compensation value is fetched and is subtracted from the difference speed value to obtain a compensated difference speed value.

Abstract: Methods relating to compensating a pre-defined seek profile for use in a data storage device, such as a disc drive, to manage the internal temperature of the device are disclosed. One embodiment disclosed is related to determining a seek profile compensation value that can be used to compensate the pre-defined seek profile for temperature. Another embodiment is a method of using a seek profile compensation value during device operation to maintain the data storage device operating temperature below an operating temperature threshold. Yet another embodiment of the present invention may be thought of as a controller for a data storage device. The controller comprises a microprocessor having a pre-determined seek profile and a means for compensating the pre-determined seek profile based on a current operating temperature.

Abstract: A motion pattern of an actuator supporting a head is monitored during/after a disc spin-up. The monitor's signal is configured to generate a digital indication of where the head was just before the spin-up. The digital indication is optionally a single-bit indicator that is used directly as a decision of whether to continue a start-up operation.

Abstract: A method of determining and monitoring head polarity of data heads comprises performing a head polarity detection routine. The head polarity detection routine comprises the step of setting a read gate period duration to a first value. The routine also comprises searching for a good address mark signal during a first read gate period with a channel polarity set to a first polarity. The routine further comprises identifying a polarity of a data head based upon the channel polarity when the good address mark is detected.

Abstract: Track closure errors written into servo sectors of an information track of a disc of a disc drive are resolved from a position control signal generated by a servo control circuit of a data storage device by steps comprising: determining a value for the track closure error from a position error signal, establishing a track closure profile based on the value of the track closure error, and injecting the track profile into the servo control circuit as a feed forward compensation input for the position error signal to resolve the track closure error from the position control signal.

Abstract: Several readings of an actuator's location are taken with a given head while urging the actuator against a mechanical stop, which acts as a guide. These readings are useful, for example, for estimating certain offsets or for determining a nominal track range for a data surface.

Abstract: A location within a cycle is determined by reading a portion of a cyclic bit sequence, the bit sequence containing several interspersed bit-group sets that each contain a plurality of series that each consist of several consecutively-placed identical bit-groups. On a data surface in a disc drive, each bit group can be stored and accessed in unused bits of each servo sector's digital portion.

Abstract: For runout compensation in a data handling system, a servo feedback loop is configured to control a head position relative to a corresponding disc surface. Operation of the feedback loop is complicated by a repeatable error in the head position having energy at harmonics of the spindle rotation frequency. Also, the feedback loop has a gain with a frequency sensitivity in a target frequency range. A feedforward controller generates an output injected into the feedback loop based on an error-indicative input. This defines a feedforward closed-loop transfer function, between the loop output and the feedforward controller input. The feedforward controller prevents the frequency sensitivity from substantially varying the feedforward closed-loop transfer function gain and phase within the target frequency range, thus reducing computational burden.

Abstract: Method and apparatus for compensating variations in motor torque in a control system that employs a motor to accelerate a control object, such as a data transducing head in a data storage device. During acceleration of the control object, a plurality of distances successively traveled by the control object are measured, and the measured distances are combined to compensate for said variations in motor torque. Preferably, a constant control input is applied to accelerate the control object at a constant rate of acceleration less than a maximum rate of acceleration that can be obtained by the motor. A coarse adjustment routine is preferably applied to arrive at a first compensation value that compensates for said variations at a first resolution, after which a fine adjustment routine is performed using the first compensation value to arrive at the final compensation value at a second resolution greater than the first resolution.

Abstract: Methods relating to compensating a pre-defined seek profile for use in a data storage device, such as a disc drive, to manage the internal temperature of the device are disclosed. One embodiment disclosed is related to determining a seek profile compensation value that can be used to compensate the pre-defined seek profile for temperature. Another embodiment is a method of using a seek profile compensation value during device operation to maintain the data storage device operating temperature below an operating temperature threshold. Yet another embodiment of the present invention may be thought of as a controller for a data storage device. The controller comprises a microprocessor having a pre-determined seek profile and a means for compensating the pre-determined seek profile based on a current operating temperature.

Abstract: A method and apparatus for compensating for the asymmetrical phases of a spindle motor in a disc drive are provided. With the apparatus and method, compensation values are learned by sampling speed data during a period of operation of the disc drive where the speed is stable and only one control operation is performed per revolution of the disc. The sampled speed data is used to generate the compensation values for each of the phases of the spindle motor. The compensation values are stored in a compensation mechanism which is used by the spindle motor speed controller to provide compensation for the asymmetrical phases of the spindle motor. During Normal operation, the actual speed output of the spindle motor is measured and is subtracted from a reference speed to generate a difference speed value. Based on the corresponding electrical phase, the correct compensation value is fetched and is subtracted from the difference speed value to obtain a compensated difference speed value.

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 data storage device has a plurality of head/surface combinations with different data track densities on at least two surfaces. A minimum head quality is established for the data storage apparatus. Head quality is identified for each of the heads at each of a plurality of track densities. A tuned track density is selected for each surface based on the track density that corresponds to a head quality.

Abstract: A motor control circuit for controlling rotation of a motor includes parallel first and second controller paths (gears). Each path includes a proportional and integral (PI) controller and a digital to analog converter (DAC). The DACs operate over different dynamic ranges (gains). The respective PI controllers have different control parameters to provide a common frequency response. The first controller path is used to output motor control signals to control the application of drive current to the motor. The circuit switches to the second controller path once the first controller path operates within a selected tolerance of a minimum or maximum level of the first dynamic range. The final state of the first PI controller is used to configure the initial state of the second PI controller to eliminate transients. The use of different gears allows the circuit to adaptively accommodate large variations in motor current and spindle motor configurations.

Abstract: An apparatus and method for writing a product information code (PIC) to a head-disc assembly (HDA) of a disc drive data handling system to facilitate subsequent identification of the HDA. The PIC is configured as a sequence of n multi-bit encoded words. Servo data are written to a disc of the HDA as a number of p angularly spaced apart servo data fields, the servo data used by a servo control circuit to effect head positional control. The n encoded words are distributed across a subset n of the p servo data fields so that the n encoded words replace at least a portion of the servo data in the n servo data fields. Preferably, the n encoded words are written to Gray code (track address) fields of the n servo data fields and are provided with error detection and correction capabilities.

Abstract: A disc drive includes an information storage disc and an actuator assembly. A retraction voltage and a retraction time interval are calculated based on the location of a transducer over a surface of the information storage disc. The retraction voltage is applied for the retraction time interval such that the actuator assembly reaches the park position at a predetermined velocity. A brake time interval is calculated when the disc drive is operating in seek mode while power to the disc drive is interrupted. A brake is applied for the brake time interval to halt movement of the actuator assembly before the retraction voltage is applied. The values of retraction voltage, retraction time interval and brake time interval are continually updated in data tables. The values are retrieved when power to the disc drive is unexpectedly interrupted such that the actuator assembly reaches the park position at the predetermined velocity.

Abstract: A filter for attenuating a resonance mode without substantial phase margin loss. The filter comprises a transfer function having an additional pole, such that the phase of the input signal is advanced. The phase-advanced filter substantially attenuates all frequencies above a selected center frequency while avoiding substantial phase margin loss.

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.