Hitachi, Ltd.

Western Digital Technologies, Inc.

Hitachi Global Storage Technologies Netherlands B.v.

Hgst Netherlands, B.v.

Shinsuke Nakagawa

Hidehiko Numasato

Kiyotada Ito

Kenji Suzuki

Masahito Kobayashi

Mutsuro Ohta

Takaaki Deguchi

Takenori Atsumi

Zaifeng Chen

Toshihiko Shimizu

Fu-Ying Huang

Tetsuo Ueda

Takashi Yamaguchi

Chuanwen Ji

Kazuo Sakai

Atsushi Okuyama

Masao Iwakura

Alexander Babinski

Yosuke Hamada

Norihisa Yanagihara

Eiji Soga

Yuji Hata

Shigeyuki Kobata

Yoshio Soyama

Jiro Abe

Hengchang Guo

Iwao Oshimi

Masaki Nagashima

Hiromoto Takeda

Various illustrative aspects are directed to a data storage device, comprising one or more disks; an actuator mechanism configured to position one or more heads proximate to one or more disk surfaces of the one or more disks; and one or more processing devices, comprising an actuator mechanism control system configured for controlling the actuator mechanism. The one or more processing devices are configured to: output a multi-rate excitation to at least one multi-rate notch filter of the actuator mechanism control system; detect a frequency response of the actuator mechanism in response to the multi-rate excitation; and calibrate the at least one multi-rate notch filter of the actuator mechanism control system, based at least in part on the detected frequency response of the actuator mechanism.

Data storage device with notch filter calibration based on multi-rate excitation and error rejection

Various illustrative aspects are directed to a data storage device, comprising one or more disks; an actuator mechanism configured to position one or more heads proximate to one or more disk surfaces of the one or more disks; and one or more processing devices, comprising an actuator mechanism control system configured for controlling the actuator mechanism. The processing devices are configured to: apply coefficients for a multi-rate notch filter to a servo control loop; measure a multi-rate error rejection transfer function; determine whether a peak of the multi-rate error rejection transfer function is greater than a multi-rate error rejection transfer function threshold; and modify, responsively to determining that the peak of the multi-rate error rejection transfer function is not greater than the multi-rate error rejection transfer function threshold, the parameters of the multi-rate notch filter based at least in part on the peak of the multi-rate error rejection transfer function.

A data storage device is disclosed comprising a head actuated over the disk. A first notch filter is calibrated at a first temperature, and a second notch filter is computed for a second temperature based on the first notch filter and a first delta temperature between the first temperature and the second temperature. The second notch filter is computed by transforming a continuous-time transfer function of the first notch filter adjusted by the first delta temperature into a discrete-time transfer function of the second notch filter.

Data storage device computing notch filters for multiple temperatures

A magnetic head drive device including a suspension for supporting a magnetic head, and a main actuator that produces rotary movement of the magnetic head by applying current to a coil. The main actuator includes end arms each comprising a single micro-actuator, and an intermediate arm comprising two micro-actuators. The micro-actuators of the end arms are driven in the same direction, and the micro-actuators of the intermediate arm are driven in the opposite direction to the drive direction of the micro-actuators of said the arms.

Magnetic head drive device with micro-actuators of end arms rotating in a direction opposite micro-actuators of intermediate arms

A flexible-printed-circuit (FPC) voice-coil assembly configured for integration in a voice-coil motor. The FPC voice-coil assembly includes at least one FPC voice coil. The FPC voice coil includes a coil including at least one coil turn, and a flexible substrate. The flexible substrate is coupled to the coil to form a flexible printed circuit. The FPC voice coil is configured for integration in a voice-coil motor. A voice-coil motor and a disk drive including the FPC voice-coil assembly are also provided.

Flexible-printed-circuit voice-coil assembly configured for integration in a voice-coil motor

In a dual-stage actuator magnetic drive having a coarse actuator and a fine actuator, an amplitude level of a command signal for the fine actuator during a decoupling-path control depends on a gain of an applied fine actuator model. The fine actuator model gain depends on the amplitude level of the fine actuator command signal and needs to be calibrated to avoid performance degradation. The gain is calibrated by determining a deviation of the fine actuator model gain from the fine actuator gain during decoupling-path control. This deviation is obtained by comparing gain values of the open-loop transfer functions measured for the decoupling-path control case and the single coarse actuator control case with respect to the feedback loop of the coarse actuator at an excitation signal frequency, when the excitation signal is added to the coarse actuator.

Magnetic disk drive having dual actuator

In a magnetic disk device, oscillation occurring at a frequency higher than Nyquist frequency is suppressed. In one embodiment, a multi-late filter having a resonance point at a frequency higher than the intended Nyquist frequency is introduced in a previous stage of a controlled object. At that time, since a resonance characteristic of the multi-rate filter is aliased by a sampler, the multi-rate filter is designed such that the resonance point after the aliasing is stabilized in phase by a following compensator.

Magnetic disk device with positioning control

In one embodiment, a magnetic disk apparatus comprises a magnetic disk for recording information; a magnetic head that reads information from, or writes information to, the magnetic disk; an actuator device that drives the magnetic head; and a control system that controls the driving of the actuator device. The actuator device is configured by a dual stage actuator comprising a fine actuator that drives the head and a coarse actuator that drives the magnetic head together with the fine actuator. The control system includes a fine controller that generates an operational value for driving the fine actuator and a coarse controller that generates an operational amount for driving the coarse actuator. The control system includes a mechanism for smoothly changing the operational amount generated by the fine controller immediately before saturation resulting from an applied voltage limit of the fine actuator or at the time the fine actuator returns to a control range from the saturation.

Magnetic disk apparatus with dual stage actuator

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.

Magnetic disk device

In a positioning control apparatus, a distance between an actual position at which absolute values of N and Q head positioning signals whose amplitudes vary cyclically in accordance with a position of a magnetic head and whose phases are different from each other by 90 degrees are equal to each other and an optimum position at which the absolute values of N and Q head positioning signals should be equal to each other is calculated from a deviation of an actual position of the magnetic head with respect to a target value of zero which deviation is obtained when controlling the magnetic head to be positioned at a boundary between ranges in which the N and Q head positioning signals have respective linearities so that the absolute values of N and Q head positioning signals become equal to each other.

Positioning control device

A positioning control apparatus for a magnetic disk apparatus. Internal models and a trajectory generation section are constructed in a control program. Based on generated position trajectory and velocity trajectory and an internal model position and velocity, a model control section outputs a first operation signal Umf for a fixed sample time Tu and then outputs a second operation signal Ums for Tu. The model control section calculates Umf and Ums so as to cause a position Pm and a velocity Vm output by an internal model 2Tu seconds later to coincide with the generated position trajectory and velocity trajectory. When a detector has detected a voice coil saturation current for head movement, a signal obtained by subtracting a position feedback signal Uh from a detected voice coil current is used as an internal model input to thereby cause the model to track a control subject.

Positioning control apparatus

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.

Positioning control method

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. Furthermore, a switching judger is provided to start its judging operation after the position deviation signal reaches a predetermine position deviation and to perform switching operation from the speed controller to the position controller when the position deviation signal is not larger than a value corresponding to a proportional multiple of a speed signal.

Disk storage device and head positioning method

A load torque imposed on a take-up reel motor is estimated from the current in a take-up reel motor and the rotational speed of the take-up reel. The current value supplied to the take-up reel motor is adjusted on the basis of the estimated load torque. A tape feed rate detected is compared with a reference signal produced from a target tape speed signal. On the basis of the comparison result, the torque of the take-up reel motor is controlled in such a manner that the tape feed rate assumes a predetermined value. The gain of a speed control system for controlling the rotational speed of the take-up reel is adjusted on the basis of a detected period of tape speed.

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Ibaraki, Japan

Shinsuke Nakagawa