Abstract: A method of writing servo information for use in head positioning control on a disk medium incorporated in a disk drive, including executing the head positioning control based on original servo information recorded on the disk medium, producing positioning correction information to correct a positioning error, and recording the positioning correction information in a correction information recording buffer.

Abstract: According to one embodiment, in a disk drive using a disk medium storing spiral servo information, a CPU generates virtual servo information having assumed virtual track centers corresponding to centers of concentric data tracks. The CPU performs control to position a head to the center of the concentric data track by using the virtual servo information.

Abstract: According to one embodiment, a servo write method for writing servo information to a disk medium used in a disk drive is disclosed. In the procedure of the servo write method, first servo information is spirally written to a disk medium in a clean room before the disk medium is incorporated into the disk drive, then, the disk medium is incorporated into the disk drive, and second servo information is concentrically written to the disk medium already incorporated in the disk drive.

Abstract: When a sub-track having burst data A and D, a sub-track having burst data A and C, a sub-track having burst data B and C, and sub-track having burst data B and D are repeatedly arranged in this order, in accordance with equations 1 and 2, a sub-track t included in a track T determines the value of a constant n within a range of 1.2 (inclusive) to 1.8 (inclusive) so as to obtain linearity between a position in a disc radial direction r and a head position P in a disc radial direction r in the sub-track t.

Abstract: A head positioning control system which is applied to a disk drive is disclosed. The system includes a feedback control system which performs head positioning control of a head and a feedforward control system. The feedforward control system detects the amplitude and phase of a disturbance based on the position error between the position of the head and a target position. The feedforward control system computes a disturbance compensation value for eliminating the disturbance to output the disturbance compensation value to the feedback control system based on each detection result of the amplitude and the phase.

Abstract: When a sub-track having burst data A and D, a sub-track having burst data A and C, a sub-track having burst data B and C, and sub-track having burst data B and D are repeatedly arranged in this order, in accordance with equations 1 and 2, a sub-track t included in a track T determines the value of a constant n within a range of 1.2 (inclusive) to 1.8 (inclusive) so as to obtain linearity between a position in a disc radial direction r and a head position P in a disc radial direction r in the sub-track t.

Abstract: A disk drive includes a head positioning system having a feed forward control system to correct a RRO component. The feed forward control system has a measuring unit which feeds back the last correction value obtained from the input value of the controller and measures a RRO component generated after the correction and an FF filter which computes a correction value to correct the RRO component.

Abstract: There is disclosed a servo information writing method of writing servo information for use in head positioning control on a disk medium incorporated in a disk drive. The present method executes a procedure having a step of executing the head positioning control based on original servo information recorded on the disk medium, a step of producing positioning correction information to correct a positioning error, and a step of recording the positioning correction information in a correction information recording buffer.

Abstract: There is disclosed a servo information writing apparatus comprising a disk drive and an examination unit. The examination unit executes examination to select an adequate servo pattern as servo information from a plurality of types of servo patterns recorded beforehand in a disk medium incorporated in the disk drive. The selection unit executes an examination to select the adequate servo pattern by use of a control and signal processing system incorporated in the disk drive.

Abstract: A head positioning control system which is applied to a disk drive is disclosed. The system includes a feedback control system which performs head positioning control of a head and a feedforward control system. The feedforward control system detects the amplitude and phase of a disturbance based on the position error between the position of the head and a target position. The feedforward control system computes a disturbance compensation value for eliminating the disturbance to output the disturbance compensation value to the feedback control system based on each detection result of the amplitude and the phase.

Abstract: A servo system is disclosed which is applied to a disk drive for detecting characteristic frequency components of a position error between a position of the head and the target position, and calculating a control correction value for correcting a control value. The servo system estimates the frequency components of target value variation from the characteristic frequency components of the position error, thereby modifying the characteristic frequency components to follow the target value variation. Thus, the servo system calculates the control correction value for suppressing the target value variation, and executes head positioning control, using a value obtained by adding the control value to the control correction value.

Abstract: There is disclosed a head positioning control system including a feedforward (FF) control system to compensate a disturbance in a disk drive. This system includes an identification unit which executes parameter identification processing to determine a transfer function of the FF controller as well as a control operation. This identification unit updates a transfer characteristic of the FF controller so as to be adapted to a disturbance fluctuation.

Abstract: A disk drive includes a head positioning system having a feed forward control system to correct a RRO component. The feed forward control system has a measuring unit which feeds back the last correction value obtained from the input value of the controller and measures a RRO component generated after the correction and an FF filter which computes a correction value to correct the RRO component.

Abstract: There is disclosed a head positioning control system in which when internal vibration including a frequency component different from a frequency of disturbance such as a higher harmonic occurs by a nonlinear element, the system effectively suppresses the internal vibration. The system has a nonlinear filter 11 to generate a higher wave as an input of an adaptive filter for performing feed forward control.

Abstract: A high-performance head positioning control system composed of a suitable combination of a multi-rate control system and a single-rate control system has been disclosed. An SM judging unit selects the multi-rate control system in a seek operation in which the head is moved to the desired track on the disk. When the head has come close to the desired track and changes from seek control to track following control, the SM judging unit switches from the multi-rate control system to the single-rate control system. The single-rate control system performs track following control whereby the head is positioned in the range of the desired track.

Abstract: There is disclosed a head positioning control system including a feedforward (FF) control system to compensate a disturbance in a disk drive. This system includes an identification unit which executes parameter identification processing to determine a transfer function of the FF controller as well as a control operation. This identification unit updates a transfer characteristic of the FF controller so as to be adapted to a disturbance fluctuation.

Abstract: Disclosed herein is a head-positioning control system designed to move a head to a target position over a disk used as a recording medium. The system causes an actuator to perform a seek operation, thus moving the disk from a prescribed start position to the target position. The system generates seek profile data representing a motion which the head makes during the seek operation. On the basis of the seek profile data, the gain of the system is estimated. A gain-adjusting value is calculated from the gain thus estimated. The gain-adjusting value is applied, adjusting the gain of the system to an appropriate gain.

Abstract: A servo system is disclosed which is applied to a disk drive for detecting characteristic frequency components of a position error between a position of the head and the target position, and calculating a control correction value for correcting a control value. The servo system estimates the frequency components of target value variation from the characteristic frequency components of the position error, thereby modifying the characteristic frequency components to follow the target value variation. Thus, the servo system calculates the control correction value for suppressing the target value variation, and executes head positioning control, using a value obtained by adding the control value to the control correction value.

Abstract: A digital position control system having a model of a plant therein is applied to a head position control system for a HDD in which a head moving unit is made to be a plant. A CPU of the HDD performs bang--bang control of the model to control movement of the head, and performs model following control to cause the head moving unit to follow the control of the model. Moreover, the CPU determines all of control input values attributable to dead beat control are smaller than an input limit value in a state of a deceleration state caused by the bang--bang control. When all of control input values are smaller than the input limit value of the plant, the CPU performs switching control to switch the bang--bang control to the dead beat control.