Abstract: The present invention recognizes that induced RRO is coherent, i.e., the RRO has a large degree of repeatability from track to track. The present invention is a zero acceleration profile (compensation) process that targets CRRO (Coherent RRO). A process of the present invention represents a considerable reduction in the factory calibration time compared to other compensation techniques currently used. The reduction in time is attributed to the fact that CRRO can be computed by averaging position error signals (PES) over multiple tracks as opposed to total RRO which is computed by averaging over multiple revolutions on the same track.

Abstract: Methods, systems, and media for functional simulation of an I/O bus are disclosed. More particularly, a method of simulating distortion and noise parameters of an I/O bus is disclosed. Embodiments include constraining one or more fields of a record and determining delay amounts based on the resulting parameters, where the final delay amount includes a delay buffer and a net of delay amounts associated with the parameters. Embodiments may also include determining a value of a next bit to be sent to the I/O bus and, after waiting the delay amount, driving the bit on the bus to the next bit value. Parameters may include skew, jitter, duty cycle distortion, voltage reference distortion, and drift of any of these parameters. Further embodiments may include signaling the end of a phase in response to a phase done condition being satisfied.

Abstract: Methods, systems, and media for managing functional verification of a parameterizable design are disclosed. Embodiments include a system having a testbench configuration module adapted to configure a testbench, the testbench having testbench signals and one or more instantiated components having a plurality of ports of a generic design, where the testbench signals are wired to the plurality of ports. The testbench may also have one or more instantiated special components based on chip-specific versions of the design where the special components are wired to the same ports as the generic design. The system may also include a functional verification manager that, through a component module, observes values in the testbench and automatically configure a verification environment based on the observed values, including automatic insertion of checkers at different levels of hierarchy. The testbench may be a VHDL or Verilog testbench in some embodiments.

Abstract: An apparatus and method of maintaining stability in a servo loop of a disc drive is provided. A dither signal (a single frequency sine wave or a multi-frequency signal) is injected into the servo loop. A servo loop gain error signal is obtained in response to the injected dither signal. A gain of the servo loop is adjusted as a function of the servo loop gain error signal in real-time.

Abstract: An apparatus and method for controlling a dynamic system is provided in which primary position control output signals are generated at a position measurement sampling frequency. Intermediate position control output signals are generated between the primary position control output signals as a function of the primary position control output signals.

Abstract: An NRRO compensation circuit controls a head position in a disc drive. The circuit has a first frequency circuit providing a first output corresponding to NRRO and a first characteristic sensing circuit that senses the first output and that generates a first control output that adjusts a first NRRO compensation gain. A first control circuit included in the NRRO compensation circuit receives the first control output and the first NRRO compensation gain and provides a first NRRO compensator output.

Abstract: An equalization filter for counteracting the effects of unwanted resonance modes and noise in the VCM plant. The filter comprises a transfer function derived from a function of the actual VCM plant response and an ideal response, for which the servo controller is designed. The response of the combined equalization filter and the actual VCM plant response substantially adheres to the ideal response. The disc drive includes firmware operable to generate one or more equalization filters for each of one or more heads.

Abstract: An apparatus and method of tracking repeatable runout in a disc drive servo loop is provided in which a feedforward signal having harmonic components that are updated at a sample rate that is a fraction of a servo sector sample rate is employed during track following.

Abstract: Problems inherent in guiding a sensor via a piecewise-linear lateral parametric profile are generally avoided using at least one broadly curved, generally lateral profile (494). A sensor is configured to move in a nominally longitudinal direction relative to a frame of reference (110). A position scale is defined in a generally lateral direction relative to the longitudinal motion (115). Each broadly curved lateral profile is defined in terms of its corresponding position scale, the scale(s) and the profile(s) both being part of a parametric model that is available for use in guiding the sensor (145).

Abstract: A system and method for correcting repeatable runout errors during manufacture of a disc drive. The system includes a Kalman filter having a recursive learning gain input and includes a recursive learning Again-setting circuit coupled to the recursive learning gain input. The recursive learning gain is initially set based on an estimate of a ratio of non-repeatable run out error to an estimate of the repeatable run out error. On subsequent recursions, the recursive learning gain-setting is reduced.

Abstract: Problems inherent in guiding a sensor via a piecewise-linear lateral parametric profile are generally avoided using at least one broadly curved, generally lateral profile (494). A sensor is configured to move in a nominally longitudinal direction relative to a frame of reference (110). A position scale is defined in a generally lateral direction relative to the longitudinal motion (115). Each broadly curved lateral profile is defined in terms of its corresponding position scale, the scale(s) and the profile(s) both being part of a parametric model that is available for use in guiding the sensor (145).

Abstract: An apparatus and method of maintaining stability in a servo loop of a disc drive is provided. A dither signal (a single frequency sine wave or a multi-frequency signal) is injected into the servo loop. A servo loop gain error signal is obtained in response to the injected dither signal. A gain of the servo loop is adjusted as a function of the servo loop gain error signal in real-time.

Abstract: A method and apparatus for compensating for repeatable run-out errors in a disc drive is disclosed. The compensation is created by determining transfer function values for a servo loop in the drive as well as a sequence of repeatable run-out values for a portion of a disc. The repeatable run-out values are divided by respective transfer function values to produce compensation values that are inverse transformed to produce time-domain compensation values. These time-domain compensation values are injected into the servo loop to compensate for repeatable run-out errors.

Abstract: An NRRO compensation circuit controls a head position in a disc drive. The circuit has a first frequency circuit providing a first output corresponding to NRRO and a first characteristic sensing circuit that senses the first output and that generates a first control output that adjusts a first NRRO compensation gain. A first control circuit included in the NRRO compensation circuit receives the first control output and the first NRRO compensation gain and provides a first NRRO compensator output.

Abstract: A system and method for correcting repeatable runout errors during manufacture of a disc drive. The system includes a Kalman filter having a recursive learning gain input and includes a recursive learning gain-setting circuit coupled to the recursive learning gain input. The recursive learning gain is initially set based on an estimate of a ratio of non-repeatable run out error to an estimate of the repeatable run out error. On subsequent recursions, the recursive learning gain-setting is reduced.

Abstract: The present invention recognizes that induced RRO is coherent, i.e., the RRO has a large degree of repeatability from track to track. The present invention is a zero acceleration profile (compensation) process that targets CRRO (Coherent RRO). A process of the present invention represents a considerable reduction in the factory calibration time compared to other compensation techniques currently used. The reduction in time is attributed to the fact that CRRO can be computed by averaging position error signals (PES) over multiple tracks as opposed to total RRO which is computed by averaging over multiple revolutions on the same track.

Abstract: An equalization filter for counteracting the effects of unwanted resonance modes and noise in the VCM plant. The filter comprises a transfer function derived from a function of the actual VCM plant response and an ideal response, for which the servo controller is designed. The response of the combined equalization filter and the actual VCM plant response substantially adheres to the ideal response. The disc drive includes firmware operable to generate one or more equalization filters for each of one or more heads.

Abstract: Piezoelectric elements or similar microactuators perform fine positioning in a system including at least two masses bendably coupled to a larger body. A servo controller receives a position signal from a sensor on the first mass, from which it generates a signal to control microactuators coupling other masses to the body. The movement of the other masses thereby exerts a controlled reactive force upon the body and upon the first mass. Examples include disc drive systems in which the reactive forces are used to counteract one or more unwanted excitations in an actuator body or actuator arm.

Abstract: A method and apparatus for compensating for repeatable run-out errors in a disc drive is disclosed. The compensation is created by determining transfer function values for a servo loop in the drive as well as a sequence of repeatable run-out values for a portion of a disc. The repeatable run-out values are divided by respective transfer function values to produce compensation values that are inverse transformed to produce time-domain compensation values. These time-domain compensation values are injected into the servo loop to compensate for repeatable run-out errors.