JP2010192112A - Disk device, and device and method for controlling head position - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To add an external disturbance suppression function without deteriorating observer's control characteristics in a device for controlling a head position based on observer control having an external disturbance suppression function. <P>SOLUTION: Actuator models 34 to 44 are separated from an external disturbance model 50. The external disturbance model 50 generates state information by using an estimation gain obtained from the external disturbance model defined by a transmission function where degrees of a denominator and a numerator shaping a sensitivity function are defined by the numerator and the denominator of the same filter, and calculates an external disturbance suppression value of the actuator 1 from the state information. The external disturbance model generates state information by using estimation gains of external disturbances of a plurality of models defined by a transmission function where numerators of a plurality of shaping filters based on a plurality of external disturbance frequencies to be suppressed are set as denominators according to an estimation position error, calculates a plurality of external disturbance suppression values of the actuator from the state information, and adds the plurality of external disturbance suppression values. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a disk device, a head position control device, and a head position control method.

  In a disk device, for example, a magnetic disk device or an optical disk device, accurately positioning the head on a target track is extremely important for improving the recording density.

  In this positioning control, it is known that disturbance affects the positioning accuracy. In order to suppress such disturbance by the control system, conventionally, the control system of FIGS. 24 to 26 has been proposed. In the first prior art of FIG. 24, a position error e between the target position r and the current position y of the plant 108 is calculated by the calculation block 100 and input to the controller 102, and the controller 102 reduces the position error e. Such a control amount is calculated, and a filter 104 having an inverse characteristic form of a notch filter is added in parallel to a feedback control system that drives the plant 108 to suppress a component near a specific frequency of the position error (Patent Literature). 1).

  As shown in FIG. 25, in the second conventional technique, a filter 104 is provided in series with the controller 102 of the feedback loop of FIG. 24 to suppress a component near a specific frequency of the control amount of the controller 102 (non-patent document). 1).

  Further, as shown in FIG. 26, the third prior art is a value obtained by dividing the current position y by the transfer function P of the plant 108 in the block 110 in the feedback loop of FIG. The difference between the second-order differential value of the position error and the command current value from the calculation block 106 is taken by the calculation block 112 and fed back to the calculation block 106 through a bandpass filter (also called a Q filter) 114 (Non-Patent Document). 1).

  In order to cope with the eccentricity of the disk, which is this periodic disturbance, a method of correcting the eccentricity using an eccentricity estimation observer has been proposed (for example, Patent Document 2 or Patent Document 3).

  Such an eccentricity estimation observer uses the state estimation gains A, B, C, F, and L to calculate the control value of the actuator from the error between the actual position error and the estimated position error, and the next sample State quantity (position, speed, bias value, eccentricity).

Here, the estimated gain L includes a position estimated gain L1, a speed estimated gain L2, a bias estimated gain L3, and eccentricity estimated gains L4 and L5. L1, L2, and L3 are characteristics of the controller itself, and L4 and L5 indicate response characteristics to eccentricity that is periodic disturbance.
USP 6,487,028B1 publication RJ Bickel and M. Tomizuka, paper “Disturbance observer based hybrid impedance control” (Proceedings of the American Control Conference 1995, pp.729-733) Japanese Patent Laid-Open No. 7-50075 JP 2000-21104 A

  Using such an observer, positioning control that follows external vibrations other than the eccentric component is desired. That is, as the recording density of the disk device is increased, the influence of the external vibration on the head positioning accuracy cannot be ignored. For example, the vibration of the medium and the wind received by the head due to the rotation of the medium affect the positioning accuracy of the head. Further, with the expansion of the use of disk devices, it is mounted on mobile devices such as mobile terminals, mobile phones, and portable AV devices, and is required to adapt to a wide range of disturbance frequencies.

  In the conventional disturbance suppression described above, when adding a compensator that selectively suppresses a specific frequency range, such as eccentricity correction, if the width of the suppression range is made extremely narrow, the characteristics of the original control system will be affected. Can be implemented without giving However, in response to the recent demand for adapting to a wide range of disturbance frequencies, if the suppression range is wide or if disturbances in the high frequency range are suppressed, the characteristics of the original controller are affected, and the desired disturbance suppression is achieved. It is difficult to add functions.

  In addition, in the prior art, when a disturbance suppression function is added later after designing one observer, the characteristics of the entire control system, for example, the pole arrangement greatly deviates, and the entire observer needs to be redesigned. Become. In other words, in the past, an observer including a controller and a disturbance suppression function is designed after a disturbance model is determined. If a specific disturbance suppression function is added later, the entire system is affected and redesign is required. It is.

  Accordingly, it is an object of the present invention to provide a disk device, a head position control device, and a head position control method for adapting to various disturbance frequencies without impairing the control characteristics of the observer.

  Another object of the present invention is to provide a disk device, a head position control device, and a head position control method for preventing head vibration by adapting to a wide range of disturbance frequencies without impairing the control characteristics of the observer. It is to provide.

  Furthermore, another object of the present invention is to provide a disk device, a head position control device, and a head position control method for improving the head tracking performance by adapting to a wide range of disturbance frequencies without impairing the control characteristics of the observer. Is to provide.

  Furthermore, another object of the present invention is to provide a disk device, a head position control device, and a head position for improving the read / write characteristics of the head by adapting to a wide range of disturbance frequencies without impairing the control characteristics of the observer. It is to provide a control method.

  The disk device of the present invention includes a head for reading at least data of a disk storage medium, an actuator for positioning the head at a predetermined position of the disk storage medium, a target position of the head, and a current position obtained from the head. A position error is calculated, an estimated position is calculated by observer control, an estimated position error is calculated from the position error and the estimated position, and generated using the estimated gain of the actuator according to the calculated estimated position error A controller model that calculates the control value of the actuator from state information, and a transfer function that is added to the controller model and that uses the denominator of the shaping filter that has the same numerator order as the denominator that shapes the sensitivity function. The estimated position error calculated by the controller model. And a disturbance model for calculating a disturbance suppression value of the actuator from state information generated using an estimated gain of disturbance, and the disturbance calculated by the controller model and the disturbance model. A control unit that adds the suppression value and drives the actuator, and the disturbance model includes the numerators of the plurality of shaping filters corresponding to the plurality of disturbance frequencies to be suppressed according to the estimated position error. Using estimated disturbance gains of a plurality of models defined by a transfer function as a denominator, generating state information, calculating a plurality of disturbance suppression values of the actuator from the state information, and calculating the plurality of disturbance suppression values It is characterized by adding.

  The head position control device according to the present invention provides a head position control device for positioning at a predetermined position of the disk storage medium by controlling an actuator by observer control of at least a head that reads data on the disk storage medium. A position error is calculated from the position and the current position obtained from the head, an estimated position is calculated by observer control, an estimated position error is calculated from the position error and the estimated position, and according to the calculated estimated position error A controller model that calculates a control value of the actuator from state information generated using the estimated gain of the actuator, and a shaping that is added to the controller model and has the same numerator order as the denominator that shapes the sensitivity function A model defined by a transfer function with the numerator of the filter as the denominator Thus, according to the estimated position error calculated by the controller model, a disturbance model for calculating a disturbance suppression value of the actuator from state information generated using an estimated gain of disturbance, and the control calculated by the controller model And an addition block for driving the actuator by adding the disturbance suppression value calculated by the disturbance model and the disturbance model, the disturbance model according to the estimated position error, the plurality of disturbance frequencies to be suppressed The state information is generated using the estimated gains of the disturbances of the plurality of models defined by the transfer function with the numerator of the plurality of shaping filters corresponding to the denominator, and the disturbances of the actuator are suppressed from the state information. A value is calculated, and the plurality of disturbance suppression values are added.

  According to the head position control method of the present invention, a head position that is executed by a head position control device that positions a head that reads at least data on a disk storage medium at a predetermined position on the disk storage medium by controlling an actuator by observer control. In the control method, the head position control device includes a control unit and a storage unit, and a controller model executed in the control unit has a position error from a target position of the head and a current position obtained from the head. State information generated by using the estimated gain of the actuator according to the calculated estimated position error, calculating the estimated position error from the position error and the estimated position. Calculating the control value of the actuator from the controller and adding it to the controller model The estimated disturbance model is a model defined by a transfer function having the denominator of the shaping filter having the same numerator order as the denominator for shaping the sensitivity function, and the estimated position calculated by the controller model The step of calculating the disturbance suppression value of the actuator from the state information generated using the estimated gain of disturbance according to the error, and the addition block is calculated by the control value calculated by the controller model and the disturbance model Adding a disturbance suppression value and driving the actuator, the disturbance model according to the estimated position error, the numerators of the plurality of shaping filters according to the plurality of disturbance frequencies to be suppressed. The state information is generated using the estimated gains of the disturbances of a plurality of models defined by the transfer function as the denominator, and the state information Calculating a plurality of disturbance suppression values of al the actuator, for adding the plurality of disturbance suppression values, characterized in that.

  For disturbance suppression, the frequency characteristics to be introduced are defined by the shaping filter, a disturbance model having the shaping filter numerator expression in the denominator is constructed, and added to the original observer model (controller model). The state information is generated using the obtained estimated gain, and the disturbance suppression value of the actuator is calculated from the state information, so the disturbance suppression function can be used even when the suppression range is wide or the disturbance in the high frequency range is suppressed. It can be implemented without affecting the control characteristics of the original observer (controller). In addition, considering the filter shape to be shaped first, it is possible to design by adding a disturbance model to the original observer (controller), so it is constrained by the physical response characteristics of the original disturbance model It is possible to shape freely.

  In addition, it is possible to easily realize a suppression function of a plurality of different disturbance frequencies, which has been difficult in the past, and a disturbance suppression function having a wide width in a low specific band.

FIG. 1 is a configuration diagram of a disk device showing an embodiment of the present invention. FIG. 2 is an explanatory diagram of the position signal of the disk of FIG. FIG. 3 is a detailed explanatory diagram of the position signal of FIG. FIG. 4 is a block diagram of a disturbance observer control system according to an embodiment of the present invention. FIG. 5 is an explanatory diagram of an analog design procedure of the disturbance observer of FIG. FIG. 6 is an explanatory diagram of the digital design procedure of the disturbance observer of FIG. FIG. 7 is a characteristic diagram of the shaping filter of the first example of the embodiment of FIG. FIG. 8 is an open loop characteristic diagram of the first example of the embodiment of FIG. FIG. 9 is a characteristic diagram of the sensitivity function of the first example of the embodiment of FIG. FIG. 10 is an acceleration disturbance characteristic diagram of the first example of the embodiment of FIG. FIG. 11 is a characteristic diagram of the shaping filter of the second example of the embodiment of FIG. FIG. 12 is an open loop characteristic diagram of the second example of the embodiment of FIG. FIG. 13 is a characteristic diagram of the sensitivity function of the second example of the embodiment of FIG. FIG. 14 is an acceleration disturbance characteristic diagram of the second example of the embodiment of FIG. FIG. 15 is a block diagram of a disturbance observer control system according to another embodiment of the present invention. FIG. 16 is a characteristic diagram of the shaping filter of the first example of the embodiment of FIG. FIG. 17 is an open loop characteristic diagram of the first example of the embodiment of FIG. FIG. 18 is a characteristic diagram of the sensitivity function of the first example of the embodiment of FIG. FIG. 19 is an acceleration disturbance characteristic diagram of the first example of the embodiment of FIG. FIG. 20 is a characteristic diagram of the shaping filter of the second example of the embodiment of FIG. FIG. 21 is an open loop characteristic diagram of the second example of the embodiment of FIG. FIG. 22 is a characteristic diagram of the sensitivity function of the second example of the embodiment of FIG. FIG. 23 is an acceleration disturbance characteristic diagram of the second example of the embodiment of FIG. FIG. 24 is an explanatory diagram of the first prior art. FIG. 25 is an explanatory diagram of the second prior art. FIG. 26 is an explanatory diagram of the third prior art.

  Hereinafter, the embodiments of the present invention will be described with reference to the disk device, the first embodiment of the observer, the design method, the example of the first embodiment, the second embodiment, and the implementation of the second embodiment. Examples will be described in the order of other embodiments, but the present invention is not limited to this embodiment.

(Disk device)
1 is a configuration diagram of a disk device according to an embodiment of the present invention, FIG. 2 is an arrangement diagram of position signals of the magnetic disk of FIG. 1, and FIG. 3 is a diagram of position signals of the magnetic disk of FIGS. It is a block diagram.

  FIG. 1 shows a magnetic disk device as the disk device. As shown in FIG. 1, a magnetic disk 4 that is a magnetic storage medium is provided on a rotating shaft 2 of a spindle motor 5. The spindle motor 5 rotates the magnetic disk 4. The actuator (VCM) 1 includes a magnetic head 3 at the tip, and moves the magnetic head 3 in the radial direction of the magnetic disk 4.

  The actuator 1 is composed of a voice coil motor (VCM) that rotates about a rotation axis. In the figure, two magnetic disks 4 are mounted on a magnetic disk device, and four magnetic heads 3 are simultaneously driven by the same actuator 1.

  The magnetic head 3 includes a read element and a write element. The magnetic head 3 is configured by laminating a read element including a magnetoresistive (MR) element on a slider and laminating a write element including a write coil thereon.

  The position detection circuit 7 converts the position signal (analog signal) read by the magnetic head 3 into a digital signal. A read / write (R / W) circuit 10 controls reading and writing of the magnetic head 3. A spindle motor (SPM) drive circuit 8 drives the spindle motor 5. The voice coil motor (VCM) drive circuit 6 supplies a drive current to the voice coil motor (VCM) 1 to drive the VCM 1.

  The microcontroller (MCU) 14 detects (demodulates) the current position from the digital position signal from the position detection circuit 7 and calculates a VCM drive command value according to the error between the detected current position and the target position. That is, servo control including position demodulation and disturbance suppression described in FIG. A read only memory (ROM) 13 stores a control program of the MCU 14 and the like. A random access memory (RAM) 12 stores data for processing of the MCU 14.

  A hard disk controller (HDC) 11 determines the position within one rotation based on the sector number of the servo signal, and records / reproduces data. A buffer random access memory (RAM) 15 temporarily stores read data and write data. The HDC 11 communicates with the host through an interface IF such as USB, ATA, or SCSI. The bus 9 connects them.

  As shown in FIG. 2, on the magnetic disk 4, servo signals (position signals) 16 are arranged at equal intervals in the circumferential direction from the outer periphery to the inner periphery. Each track is composed of a plurality of sectors, and the solid line in FIG. 2 indicates the recording position of the servo signal 16. As shown in FIG. 3, the position signal is composed of a servo mark Servo Mark, a track number Gray Code, an index Index, and offset information (servo bursts) PosA, PosB, PosC, and PosD. In addition, the dotted line of FIG. 3 shows a track center.

  The position signal in FIG. 3 is read by the head 3, and the position of the magnetic head in the radial direction is detected using the track number Gray Code and the offset information PosA, PosB, PosC, PosD. Further, the position of the magnetic head in the circumferential direction is grasped based on the index signal Index.

  For example, the sector number when the index signal is detected is set to 0, and every time the servo signal is detected, the sector number is counted up to obtain the sector number of each sector of the track. The sector number of the servo signal is a reference when data is recorded / reproduced. Note that there is one index signal per cycle, and a sector number may be provided instead of the index signal.

  The MCU 14 in FIG. 1 confirms the position of the actuator 1 through the position detection circuit 7, performs servo calculation, and supplies an appropriate current to the VCM 1. That is, seek control can be moved to a target position by transitioning from coarse control, settling control, and following control. In either case, it is necessary to detect the current position of the head.

  In order to confirm such a position, a servo signal is recorded in advance on the magnetic disk as shown in FIG. That is, as shown in FIG. 3, a servo mark indicating the start position of the servo signal, a gray code indicating the track number, an index signal, and signals PosA to PosD indicating the offset are recorded. This signal is read by the magnetic head, and the servo signal is converted into a digital value by the position detection circuit 7.

(First embodiment of disturbance observer)
FIG. 4 is a block diagram of a first embodiment of a positioning control system that suppresses disturbances executed by the MCU 14 of FIG. This positioning control system is an observer control system for detecting a disturbance frequency and suppressing the disturbance by adaptive control.

  The observer shown in FIG. 4 is a current observer including bias compensation represented by the following formulas (1), (2), (3), (4), and (5).

  That is, this embodiment is an example of an adaptive control system in which the disturbance model 50 is separated from the controller model. In FIG. 4, the first calculation block 30 calculates the actual position error er [k] by subtracting the target position r from the observed position y [k] obtained by demodulating the servo information read by the head 3. . The second calculation block 32 calculates an estimated position error e [k] by subtracting the estimated position x [k] of the observer from the actual position error er [k].

  In the controller model, this estimated position error e [k] is input to the state estimation block 34, and the estimated correction value (the right side of Expression (1)) is calculated using the estimated gain La (L1, L2) of the controller. Is done. Then, the state quantity (the left side of Expression (1)) x [k], v [k] is added from the delay block 46 by the addition block 36, and the estimated position x [k], the estimated speed is added as shown in Expression (1). v [k] is obtained. In equation (1), the estimated position error e [k] is represented by (y [k] −x [k]).

  The estimated values x [k] and v [k] are multiplied by the state feedback gain (one Fa = F1, F2) in the fourth calculation block 38, and the first value of the actuator 1 is obtained as shown in Equation (2). A drive value u [k] of 1 is obtained. On the other hand, the estimated values x [k] and v [k] of the expression (1) from the addition block 36 are obtained by the fifth calculation block 42 by the estimated gain Aa (2 × 2 (1, 0 of the expression (4)). ) And the drive value u [k] of the fourth calculation block 38 is multiplied by the estimated gain Ba (value to be multiplied by u [k] of Expression (4)) in the sixth calculation block 40. It is done. Both multiplication results are added in the addition block 44 to obtain estimated state quantities x [k + 1] and v [k + 1] of the next sample of the equation (4).

  The estimated state quantity of the next sample is input to the delay block 46 as described above, and is corrected by the estimated correction value in the state estimation block 34. The estimated position x [k] is extracted from the estimated value of the expression (1) from the addition block 36 in the seventh calculation block 48 and is input to the second calculation block 32 described above.

  On the other hand, in the disturbance model 50, the estimated position error e [k] is input to the disturbance state estimation block 51, and the estimated correction value (the right side of the expression (1) is used) using the estimated gain Ld1 (L3, L4, L5). ) Is calculated. Then, the state quantity (the left side of Expression (1)) is added from the delay block 52 and the addition block 56, and as shown in Expression (1), the estimated bias value b [k], the estimated disturbance suppression value z1 [k], z2 [k] is obtained.

  The estimated values b [k], z1 [k], and z2 [k] are multiplied by the state feedback gain (Fd1 = F3, F4, F5) in the eighth operation block 58, as shown in Expression (3). Then, the disturbance suppression drive value of the actuator 1 is obtained. On the other hand, the estimated values b [k], z1 [k], and z2 [k] of the expression (1) from the addition block 56 are converted into the estimated gain Ad1 (b [ k] and 2 × 2 A matrix gain) and input to the delay block 52 to obtain estimated values b [k + 1], z1 [k + 1], and z2 [k + 1] of the next sample.

  Then, in the addition block 60, the disturbance suppression drive value is subtracted from the drive value u [k] to obtain the output drive value uout [k] of Expression (3).

  That is, the estimated gain L is separated by the controller model and the disturbance model, and the feedback gain F is separated by the controller model and the disturbance model, and the controller model and the disturbance model are separated and designed.

(Observer design method)
Next, an observer design method for separating the disturbance model will be described with reference to FIGS.

  First, the first design method will be described with reference to FIG.

  (S10) The original controller is designed by observer control. That is, a model to be controlled is set.

  (S12) Then, the filter shape to be shaped is determined. That is, the number of shaping filters and the poles and zeros of each filter are set. However, the filter shape to be shaped is a primary or secondary filter and the numerator and denominator orders must be the same.

  (S14) Next, a disturbance model having the filter numerator expression in the denominator is constructed using the zeros of the shaping filter.

  (S16) This disturbance model is added to the observer model in S10. Adding this disturbance model specifies the zero of the sensitivity function.

  (S18) Next, the poles of the entire observer control system are designated. This pole includes the pole used in the original design and the pole of the filter for shaping. That is, the pole placement of the enlarged model (overall model) including the poles of the shaping filter is performed, and the estimated gains L1 to L5 and A matrix of the observer are designed.

  (S20) The pole placement of only the control target model is performed, and the state feedback gain F is designed.

  (S22) The output gain of the disturbance model is added to the state feedback gain, and the feedback gain of the integrated model is designed. In this way, an observer including a disturbance model is designed.

  That is, in the present invention, the performance of suppressing position disturbance, external vibration, and impact is determined by the sensitivity function and acceleration disturbance characteristics. For this reason, a desired disturbance suppression function is provided by designing the shape of the sensitivity function and acceleration disturbance characteristics.

  Hereinafter, the design procedure will be described with an example. First, the observer control system when the actuator 1 is a double integral model is expressed by an analog expression of the following expression (6).

  In Equation (6), s is a Laplace operator, x is an estimated position, v is an estimated speed, y is a current position, r is a target position, L1 and L2 are position, speed estimated gain, u is a drive current, and B1 / m is a force constant of the actuator 1.

  Next, this control system has a sensitivity function of 1 / (1 + CP). For this sensitivity function, disturbance suppression is defined by the primary filter of the following equation (7), and the sensitivity is determined by this primary filter. Format the function.

  That is, the sensitivity function when this filter is applied has a shape obtained by multiplying 1 / (1 + CP) by equation (7).

  At this time, as a disturbance model, a model of a transfer function of the following formula (8) having the filter numerator of the above formula (7) as a denominator is mounted on the observer.

  On the other hand, the denominator (ω2) of the filter in Expression (7) is used for pole arrangement.

  By installing this disturbance model in the observer of Expression (6), the following Expression (9) is obtained from Expression (6).

  In the above equation (9), b is a disturbance estimated value, and here, it is indicated by a parameter of a steady bias estimated value. In order to design the estimated gains L1, L2, and L3 of the observer in Expression (9), the pole (denominator) of the shaping filter of Expression (7) together with the pole used in designing the original observer of Expression (6): Specify -ω2.

  In Equation (9), only the feedback gain (Fx, Fv) is designed. Although the disturbance model is observable but not controllable, the feedback gain of the disturbance model cannot be changed. The same disturbance model as that used for the estimated gain design of the observer is specified. In equation (9), the feedback gain (output gain) of the disturbance model is K = m / Bl.

  In this way, the original controller is designed by observer control, and the filter shape to be shaped is determined according to the disturbance frequency to be suppressed. Here, the shaping filter is a primary or secondary filter, and it is necessary that the orders of the numerator and the denominator are the same. When the numerator and denominator orders of the filter are different, for example, when the denominator order is larger than the numerator order (ω1 / (s + ω2)), the frequency characteristics of this filter decrease as the frequency increases. However, when the original sensitivity function is multiplied, the original sensitivity function (that is, the characteristics of the controller) changes significantly.

  Then, a disturbance model having the numerator of the filter is formed in the denominator and added to the observer model (Expression (9)). Adding this disturbance model designates the zero point of the sensitivity function.

  Next, as described above, the poles of the entire observer control system are designated. This pole includes the pole used in the original controller model and the filter pole (−ω2) for shaping.

  In other words, in order to suppress the disturbance, the frequency characteristic to be introduced is defined by the shaping filter, and a disturbance model having the shaping filter numerator expression in the denominator is constructed and added to the original observer model. As a result, the disturbance suppression function can be implemented without affecting the characteristics of the original controller even when the suppression range is wide or when disturbances in a high frequency range are suppressed.

  Moreover, even when a disturbance suppression function is added later after designing one observer, the characteristic deviation of the entire control system is small, and the entire observer is not required to be redesigned.

  Next, the case where the shaping filter is a secondary filter will be described. The secondary filter is defined by the following equation (10).

  As described above, the disturbance model has the numerator expression of the shaping filter in the denominator, and is expressed by the following expression (11).

  Next, three methods can be considered as a method of mounting this disturbance model in the observer (formula (6)) of the original controller.

  In the first method, the disturbance model of Expression (11) is mounted as it is as in Expression (9). That is, because of the secondary filter, when the disturbance state estimation amounts are z1 and z2 and the disturbance estimation gains are L3 and L4, they are expressed by Expression (12).

  Next, in the second method, the square term of ω1 is dispersed, and Equation (12) is transformed to obtain Equation (13).

  The third method is obtained by inverting the sign of ω1 in equation (13), and is represented by equation (14).

  Either method can be used for design. The second method and the third method are particularly effective when the above model is converted into a digital control system. That is, the two state variables z1 and z2 are balanced, and the estimated gains L3 and L4 of the observers for the two state variables can be mounted without being too far apart.

  At this time, the pole is specified by combining the pole of the shaping filter in Eq. (10) (derived from the denominator of Eq. (10) = 0) and the pole used in the design of the original observer control system. Thus, the values of the estimated gains L1, L2, L3, and L4 are designed.

  Further, an observer control system that combines the secondary filter shaping and the conventional steady-state bias estimation is expressed by the following equation (15).

  In this way, it is possible to design by adding a disturbance model to the observer after considering the filter shape to be shaped first. Therefore, it is possible to shape the shape freely without being restricted by the physical response characteristics of the original disturbance model.

  FIG. 5 was an explanation in analog design. On the other hand, to design a digital control system, the design flow shown in FIG. 6 is followed.

  In FIG. 6, the same steps as those shown in FIG. 5 are indicated by the same symbols. As shown in FIG. 6, in step S16, the disturbance model is modeled in an analog space to form an enlarged model. On the other hand, after the enlarged model is converted into a digital space (discretized) in step S30, the pole arrangement in step S18 is designated in the digital space.

  Further, when the extended model is converted into a discrete system when the characteristics of the second-order filter are provided as a disturbance model, both the two variables z1 and z2 of the disturbance model are included in the A matrix for designing the estimated gain of the observer. 1 will be affected.

  Therefore, correction is made so that only one variable of the disturbance model affects the actuator 1, specifically, only the same variable as in the analog design affects the actuator 1. That is, after the discretization, the enlarged model is corrected in step S32.

  More specifically, when the analog model in the form of Expression (13) using a secondary filter is discretized (so-called z conversion and converted into SI units), the form of the following Expression (16) is obtained.

  In Expression (16), z is a Z converter, and T is a sampling period. Here, attention should be paid to A13, A14, A23, and A24 which are A matrices. Neither A14 nor A24 becomes “0” only by discretization. That is, in the A matrix for designing the estimated gain of the observer, both of the two variables z1 and z2 of the disturbance model affect the actuator 1.

  Therefore, after discretizing the analog model, the state variables z1 and z2 of the disturbance model in the A matrix replace the coefficients that affect the actuator 1.

  In the example of Expression (16), the A matrix is corrected as shown in Expression (17) below.

In the digital control system, the distance unit is a track, the current value is normalized to a maximum current of 1, and the speed and acceleration must be normalized not by the second but by the sample frequency.
Similarly, when the observer in the analog form of Expression (15) is converted into the form of the current observer, Expression (18) is obtained.

  In this way, when the disturbance model is designed to be separable, Equation (18) can be implemented by separating the disturbance model as shown in FIG.

  That is, when comparing the equation (18) with the equations (1) to (5), in the equation (18), the independent models of the controllers are the equations (2) and (4), and the disturbance model 50 is The separated formulas are formulas (3) and (5).

(Example of the first embodiment)
7 and 10 are explanatory diagrams of the first example of the first embodiment of the present invention. FIG. 7 is a characteristic diagram of the shaping filter, FIG. 8 is an open loop characteristic diagram, and FIG. FIG. 10 is a graph of acceleration disturbance characteristics.

  7 to 10 are examples in which 1600 Hz is suppressed in a notch shape. The necessity to suppress such a high frequency is when the high frequency is applied as a disturbance due to the vibration of the disk medium or the vibration of the head suspension. In particular, when the rotational speed of the disk medium is increased, the influence of such high frequency disturbances is significant in an apparatus having a high track density.

  In such a high range, even if the reverse characteristic of the notch filter is inserted in series into the controller, it is difficult to realize. Further, as apparent from the phase characteristic, trial and error are required for adjusting the filter coefficient in order to realize the characteristic of raising after being lowered.

In the present embodiment, as shown in FIG. 7, a shaping filter that suppresses only a specific frequency is designed. This shaping filter is designed by the secondary filter shown by Formula (10). In Expression (10), ω1 = 2π * 1600, ω2 = ω1, ζ1 = 0.025, and ζ2 = 0.05.

  As for the frequency characteristics of this shaping filter, as shown in the frequency vs. gain characteristics in the upper part of FIG. 7 and the frequency vs. phase characteristics in the lower part, the gain is suppressed around 1600 Hz, and the phase temporarily decreases around 1600 Hz, It is a characteristic that rises thereafter.

  The above-described observer is configured using the shaping filter designed in this way. As for the open loop characteristics of the control system composed of observers at this time, the gain is lowered at 1600 Hz and the phase is around 1600 Hz as shown in the frequency vs. gain characteristics in the upper part of FIG. 8 and the frequency vs. phase characteristics in the lower part. Perform the operation to raise.

  For this reason, with respect to the sensitivity function of the control system, the gain is suppressed in the vicinity of 1600 Hz as shown in the frequency versus gain characteristic of FIG. As for the acceleration disturbance characteristic of the control system, the gain is suppressed in the vicinity of 1600 Hz as shown in the frequency versus gain characteristic of FIG.

  11 and 14 are explanatory diagrams of a second example of the first embodiment of the present invention. FIG. 11 is a characteristic diagram of the shaping filter, FIG. 12 is an open loop characteristic diagram, and FIG. FIG. 14 is a graph showing acceleration disturbance characteristics.

  11 to 14 are examples in which the low frequency is uniformly suppressed. The necessity to uniformly suppress such a low frequency band is when it is desired to widen the suppression range of external vibrations in addition to the eccentricity of the disk medium. In particular, there are many low-frequency external vibration components, and the influence is remarkable. Widening such a low-frequency suppression range is difficult to achieve with a conventional observer.

In the present embodiment, as shown in FIG. 11, a shaping filter that suppresses a low frequency over a wide range is designed. This shaping filter is designed by the secondary filter shown by Formula (10). In equation (10), ω1 = 2π * 200, ω2 = 2π * 400, ζ1 = 0.5, and ζ2 = 0.5.

  As for the frequency characteristics of this shaping filter, as shown in the upper part of FIG. 11 in the frequency versus gain characteristic and the lower part in the frequency versus phase characteristic, the gain gradually increases when the lower limit (100 Hz) of the low band is exceeded. It becomes substantially constant at the upper limit of the band (here, near 500 Hz), and the phase is a characteristic that forms a peak between the lower limit of the low band (100 Hz) and the upper limit of the low band (here, near 500 Hz).

  The above-described observer is configured using the shaping filter designed in this way. As for the open loop characteristics of the control system composed of observers at this time, the gain is increased in the low frequency range as shown in the thick line of the frequency vs. gain characteristic in the upper part of FIG. Increase the value near the low range.

  For this reason, with respect to the sensitivity function of the control system, the gain is suppressed in the vicinity of the low band as shown by the thick line of the frequency vs. gain characteristic in FIG. As for the acceleration disturbance characteristic of the control system, the gain is suppressed in a low band as shown by the thick line of the frequency versus gain characteristic in FIG.

  As in this embodiment, it is possible to easily realize high-frequency suppression and low-frequency wide-range disturbance suppression observers that have been difficult in the past.

(Second embodiment of the observer)
FIG. 15 is a block diagram of a second embodiment of the positioning control system that suppresses the disturbance executed by the MCU 14 of FIG.

  This positioning control system is an observer control system for detecting a disturbance frequency and suppressing the disturbance by adaptive control, and is an adaptive control system in which a plurality of disturbance models shown in FIG. 4 are separated and mounted.

  15, the same components as those shown in FIG. 4 are indicated by the same symbols, and each of the disturbance models 50-1,..., 50-N is the disturbance adaptive control model shown in FIG. It is composed of blocks 51, 52, 54, 56 and 58.

  Each disturbance model 50-1, ..., 50-N is provided for each disturbance frequency that needs to be tracked. The outputs of the disturbance models 50-1,..., 50-N are added by the addition block 62 and then output to the calculation block 60. The operation of this model is the same as in FIG.

  The observer when the disturbance models 50-1 and 50-2 are two is obtained by expanding the expressions (1) to (5) by two models and the following expressions (19) to (23).

  Here, the estimated position (variable) of the disturbance model 50-1 is z1, z2, the estimated gain is L3, L4, L5, the output gain is F3, F4, F5, and the position of the disturbance model 50-2. The estimated amount (variable) of speed is z3, z4, the estimated gain is L6, L7, and the output gain is F6, F7.

  Also in this example, as shown in FIG. 6, each disturbance model is designed with a shaping filter, and similarly, an enlarged model is designed. In such a configuration, a plurality of specific frequencies can be suppressed as described in the following embodiments.

(Example of the second embodiment)
16 and 19 are explanatory diagrams of the first example of the second embodiment of the present invention. FIG. 16 is a characteristic diagram of the shaping filter, FIG. 17 is an open loop characteristic diagram, and FIG. FIG. 19 is a graph of acceleration disturbance characteristics.

  16 to 19 are examples of NRRO (Non Repeatable Rotation) filters that suppress three frequencies in a notch shape. The necessity of suppressing such a plurality of frequencies is effective in terms of widening the suppression width in response to various disturbances.

  In order to suppress such a plurality of frequencies, it is necessary to insert the inverse characteristics of the notch filter into the controller in multiple stages, and adjustment thereof is difficult.

  In the present embodiment, as shown in FIG. 16, a shaping filter that suppresses three specific frequencies (1000 Hz, 1100 Hz, 1600 Hz) is designed. For this shaping filter, three secondary filters shown in Expression (10) are designed. In Expression (10), the first filter is ω1 = 2π * 1020, ω2 = 2π * 1000, ζ1 = 0.025, ζ2 = 0.05, and the second filter is ω1 = 2π * 1090, ω2. = 2π * 1210, ζ1 = 0.025, ζ2 = 0.05, and the third filter is in series with ω1 = 2π * 1600, ω2 = 2π * 1600, ζ1 = 0.025, ζ2 = 0.05. It is connected. That is, three disturbance models shown in FIG. 15 are designed.

  With respect to the frequency characteristics of this shaping filter, as shown in the upper part of FIG. 16 for frequency vs. gain characteristics and the lower part of FIG. 16 for frequency vs. phase characteristics, the gain is suppressed at three places near 1000 Hz, 1100 Hz, and 1600 Hz. Is a complex characteristic that decreases once near 1000 Hz, then increases, decreases near 1100 Hz, increases near 1600 Hz, and then decreases.

  The above-described observer is configured using the shaping filter designed in this way. As for the open loop characteristics of the control system composed of the observers at this time, the gains are 1000 Hz, 1100 Hz, and 1600 Hz as shown by the thick lines of the frequency vs. gain characteristics in the upper part of FIG. Lower the phase at 1000 Hz, and perform an operation that peaks at around 1100 Hz and 1600 Hz.

  For this reason, with respect to the sensitivity function of the control system, as indicated by the thick line of the frequency vs. gain characteristic in FIG. 18, the gain is suppressed near 1000 Hz and 1100 Hz, and near 1600 Hz. As for the acceleration disturbance characteristic of the control system, as indicated by the thick line of the frequency vs. gain characteristic in FIG. 19, the gain is suppressed near 1000 Hz and 1100 Hz, and near 1600 Hz.

  20 and 23 are explanatory diagrams of a second example of the second embodiment of the present invention. FIG. 20 is a characteristic diagram of the shaping filter, FIG. 21 is an open loop characteristic diagram, and FIG. FIG. 23 is a graph of acceleration disturbance characteristics.

  FIGS. 20 to 23 are examples of band stops that uniformly suppress a specific low bandwidth, and suppress the peak of acceleration disturbance characteristics. The necessity of uniformly suppressing such a specific low-bandwidth is a case where it is desired to widen the suppression width with respect to external vibration and increase the follow-up performance of acceleration disturbance. In particular, there are many low-frequency external vibration components, and the influence is remarkable. Widening such a low-frequency suppression range is difficult to achieve with a conventional observer.

  In the present embodiment, as shown in FIG. 20, a shaping filter that suppresses a low specific frequency band over a wide range is designed. This shaping filter is designed with two secondary filters represented by Expression (10). In Expression (10), the first filter is ω1 = 2π * 200, ω2 = 2π * 150, ζ1 = 0.15, ζ2 = 0.3, and the second filter is ω1 = 2π * 300, ω2. = 2π * 350, ζ1 = 0.15, ζ2 = 0.3, and connected in series.

  As for the frequency characteristics of this shaping filter, as shown in the frequency vs. gain characteristics in the upper part of FIG. 20 and the frequency vs. phase characteristics in the lower part, the gain decreases when the lower limit (150 Hz) of the low band is exceeded, and is 200 to 300 Hz. Then, it becomes constant and rises toward the upper limit of the low band (here, around 500 Hz), and then becomes almost constant. , In the vicinity of 350 Hz).

  The above-described observer including the two disturbance models in FIG. 15 is configured using the shaping filter designed in this way. As for the open loop characteristics of the control system composed of observers at this time, the gain is increased in the vicinity of 150 Hz to 500 Hz as shown by the thick line of the frequency vs. gain characteristic in the upper part of FIG. 21 and the frequency vs. phase characteristic in the lower part. The phase is increased in the vicinity of the lower limit (150 Hz) of the low band, and the upper limit of the low band (here, near 350 Hz) is decreased.

  For this reason, as for the sensitivity function of the control system, the gain is suppressed with a width in the vicinity of the low band (150 Hz to 500 Hz) as shown by the thick line of the frequency vs. gain characteristic in FIG. As for the acceleration disturbance characteristic of the control system, as shown by the thick line of the frequency vs. gain characteristic in FIG. 23, the gain is improved with a width in the vicinity of the low band (150 Hz to 500 Hz). That is, the gain of the acceleration disturbance characteristic increases with a specific frequency width, and the peak of the acceleration disturbance characteristic can be suppressed.

  As in this embodiment, it is possible to easily realize the suppression of a plurality of different disturbance frequencies, which has been difficult in the past, and the disturbance suppression observer having a wide low bandwidth in a specific band.

(Other embodiments)
In the above-described embodiment, the disturbance observer control has been described with reference to the application example of the head positioning device of the magnetic disk device. However, the disturbance observer control can also be applied to other disk devices such as an optical disk device. In addition, the number of disturbance frequencies can be appropriately adopted as necessary, and the number of disturbance models can be appropriately adopted accordingly. Furthermore, although the embodiment has been described with a secondary filter, a primary filter or a combination of a primary filter and a secondary filter can be used according to a required suppression frequency.

  As mentioned above, although this invention was demonstrated by embodiment, this invention can be variously deformed within the range of the meaning, and this is not excluded from the scope of the present invention.

  (Supplementary Note 1) In a head positioning control method for controlling positioning of a head at a predetermined position of a disk storage medium by an actuator, a step of calculating a position error from a target position of the head and a current position obtained from the head; According to the estimated position error between the error and the estimated position of the observer, using the estimated gain of the actuator, generating state information, calculating the actuator control value from the state information, and according to the estimated position error, Using the estimated gain obtained from the disturbance model defined by the transfer function with the denominator as the denominator and the denominator for shaping the sensitivity function, the state information is generated, and the actuator is obtained from the state information. And calculating the disturbance suppression value of the current value, adding the control value and the disturbance suppression value, Head positioning control method characterized by comprising the step of driving the actuator.

  (Supplementary Note 2) In the disturbance suppression value calculation step, state information is obtained by using an estimated gain obtained from a disturbance model having a zero of the numerator of the filter that shapes the sensitivity function according to a desired disturbance frequency. The head positioning control method according to supplementary note 1, comprising the step of generating and calculating a disturbance suppression value of the actuator from the state information.

  (Supplementary note 3) The disturbance suppression value calculation step uses an estimated gain obtained from a disturbance model having a denominator of the numerator of the primary or secondary filter that shapes the sensitivity function according to a desired disturbance frequency, The head positioning control method according to supplementary note 1, comprising the steps of generating state information and calculating a disturbance suppression value of the actuator from the state information.

  (Supplementary Note 4) The disturbance suppression value calculation step includes a plurality of disturbance models defined by transfer functions having a denominator of the numerator of the plurality of filters according to the plurality of disturbance frequencies to be suppressed according to the estimated position error. Using the estimated gain obtained from the step, generating state information, calculating a plurality of disturbance suppression values of the actuator from the state information, and adding the plurality of disturbance suppression values. The head positioning control method according to appendix 1.

  (Supplementary Note 5) A position error is calculated from a head that reads at least data on a disk storage medium, an actuator that positions the head at a predetermined position on the disk storage medium, a target position of the head, and a current position obtained from the head. A control unit for calculating state information using the estimated gain of the actuator according to the estimated position error between the position error and the estimated position of the observer, and calculating a control value of the actuator from the state information; And the control unit uses an estimated gain obtained from a disturbance model defined by a transfer function having the denominator of the filter having the same denominator as the denominator for shaping the sensitivity function according to the estimated position error. State information is generated, a disturbance suppression value of the actuator is calculated from the state information, and the control value By adding the disturbance suppression value, the disk apparatus characterized by driving the actuator.

  (Appendix 6) The control unit generates state information using an estimated gain obtained from a disturbance model having a zero of the numerator of the filter that shapes the sensitivity function according to a desired disturbance frequency, and The disk device according to appendix 5, wherein a disturbance suppression value of the actuator is calculated from the state information.

  (Additional remark 7) The said control unit uses a presumed gain calculated | required from the disturbance model which used the said numerator of the primary or secondary filter which shapes a sensitivity function according to a desired disturbance frequency as a denominator. The disk device according to appendix 5, wherein the disturbance suppression value of the actuator is calculated from the state information.

  (Additional remark 8) The said control unit calculated | required from the several disturbance model defined by the transfer function which used the said numerator of the said some filter according to the said estimated position error as a denominator according to the several disturbance frequency which should be suppressed. The disk device according to appendix 5, wherein state information is generated using the estimated gain, a plurality of disturbance suppression values of the actuator are calculated from the state information, and the plurality of disturbance suppression values are added.

  (Supplementary Note 9) The control unit is obtained from a disturbance model defined by a transfer function having the denominator as the denominator of the primary filter that performs steady bias compensation and the secondary filter that suppresses the vicinity of a specific frequency like a notch filter. The disk device according to appendix 5, wherein state information is generated using the estimated gain, and a disturbance suppression value of the actuator is calculated from the state information.

  (Additional remark 10) The said control unit is the estimation calculated | required from the disturbance model defined by the transfer function which made the said numerator the denominator of the primary filter which performs steady bias compensation, and the secondary filter which suppresses below a specific frequency uniformly The disk device according to appendix 5, wherein state information is generated using a gain, and a disturbance suppression value of the actuator is calculated from the state information.

  (Additional remark 11) The said control unit is the estimated gain calculated | required from the disturbance model defined by the transfer function which used the said numerator as the denominator of the secondary filter which suppresses the said specific frequency vicinity of a comparatively high region to a notch filter shape. The disk device according to appendix 9, wherein state information is generated and a disturbance suppression value of the actuator is calculated from the state information.

  (Additional remark 12) The said control unit is the estimated gain calculated | required from the several disturbance model defined by the transfer function which used the said numerator as the denominator of the several secondary filter which suppresses the some said specific frequency vicinity in notch filter form The disk device according to appendix 9, wherein the state information is generated using and the disturbance suppression value of the actuator is calculated from the state information.

  (Additional remark 13) The said control unit uses the estimation gain calculated | required from the disturbance model defined by the transfer function which used the said numerator as the denominator of the secondary filter which suppresses below the said specific frequency of a comparatively low region uniformly. The disk device according to appendix 10, wherein state information is generated and a disturbance suppression value of the actuator is calculated from the state information.

  (Supplementary note 14) In a head position control device for positioning a head for reading at least data on a disk storage medium at a predetermined position on the disk storage medium by controlling an actuator, a target position of the head and a current position obtained from the head The estimated position error is calculated from the estimated position error between the position error and the estimated position of the observer, using the estimated gain of the actuator, the state information is generated, and the control value of the actuator is calculated from the state information. Using the estimated gain obtained from the disturbance model defined by the transfer function with the numerator as the denominator of the filter with the same denominator as the denominator for shaping the sensitivity function and the denominator according to the estimated position error A disturbance observer that generates information and calculates a disturbance suppression value of the actuator from the state information Bar and, by adding the disturbance suppression value and the control value, head position control device and having an addition block for driving the actuator.

  (Supplementary Note 15) The disturbance observer generates state information using an estimated gain obtained from a disturbance model having a zero of the numerator of the filter that shapes the sensitivity function according to a desired disturbance frequency, The head position control device according to appendix 14, wherein a disturbance suppression value of the actuator is calculated from the state information.

  (Supplementary Note 16) The disturbance observer uses the estimated gain obtained from the disturbance model with the numerator of the first-order or second-order filter shaping the sensitivity function according to a desired disturbance frequency as the state information. The head position control device according to appendix 14, characterized by generating and calculating a disturbance suppression value of the actuator from the state information.

  (Supplementary Note 17) The disturbance observer is obtained from a plurality of disturbance models defined by a transfer function having a denominator of the numerator of the plurality of filters according to the plurality of disturbance frequencies to be suppressed according to the estimated position error. The head position control device according to appendix 14, wherein state information is generated using an estimated gain, a plurality of disturbance suppression values of the actuator are calculated from the state information, and the plurality of disturbance suppression values are added.

  (Supplementary Note 18) The disturbance observer is obtained from a disturbance model defined by a transfer function having the numerator as a denominator of a primary filter that performs steady-state bias compensation and a secondary filter that suppresses the vicinity of a specific frequency like a notch filter. The head position control device according to appendix 14, wherein state information is generated using the estimated gain, and a disturbance suppression value of the actuator is calculated from the state information.

  (Supplementary Note 19) The disturbance observer is an estimation obtained from a disturbance model defined by a transfer function having the numerator as a denominator of a primary filter that performs steady-state bias compensation and a secondary filter that uniformly suppresses a specific frequency or less. The head position control device according to appendix 14, wherein state information is generated using a gain, and a disturbance suppression value of the actuator is calculated from the state information.

  (Supplementary note 20) The disturbance observer calculates an estimated gain obtained from a disturbance model defined by a transfer function having the numerator as a denominator of a second-order filter that suppresses the vicinity of the specific frequency in a relatively high band in a notch filter shape. The head position control device according to appendix 18, wherein state information is generated and a disturbance suppression value of the actuator is calculated from the state information.

  In order to suppress disturbances, the frequency characteristics to be introduced are defined by the shaping filter, a disturbance model having the numerator formula of the shaping filter as the denominator is constructed, added to the original observer model, and the estimated gain obtained from this disturbance model Is used to generate the state information, and the disturbance suppression value of the actuator is calculated from the state information.Therefore, even if the disturbance suppression function has a wide suppression range or suppresses disturbance in a high frequency range, the original observer is used. Can be implemented without affecting the control characteristics of the (controller).

DESCRIPTION OF SYMBOLS 1 Actuator 2 Spindle motor rotating shaft 3 Head 4 Disc 5 Spindle motor 6 Actuator VCM drive circuit 7 Position demodulation circuit 8 Spindle motor drive circuit 9 Bus 10 Data recording / reproducing circuit 11 Hard disk controller 12 MCU RAM
13 MCU ROM
14 Microcontroller unit 15 Hard disk controller RAM
16 Position signal 50 Disturbance model

Claims (5)

A head that at least reads data on a disk storage medium;
An actuator for positioning the head at a predetermined position of the disk storage medium;
A position error is calculated from the target position of the head and the current position obtained from the head, an estimated position is calculated by observer control, an estimated position error is calculated from the position error and the estimated position, and the calculated In accordance with the estimated position error, the controller model that calculates the actuator control value from the state information generated using the estimated gain of the actuator is added to the controller model, and the denominator and the numerator order for shaping the sensitivity function are the same. A model defined by a transfer function having the numerator of a certain shaping filter as a denominator, and the disturbance of the actuator from the state information generated using the estimated gain of disturbance according to the estimated position error calculated by the controller model A disturbance model for calculating a suppression value, and the control calculated by the controller model. A control unit for driving the actuator by adding the said disturbance suppression value calculated values and in the disturbance model,
With
The disturbance model uses estimated gains of disturbances of a plurality of models defined by transfer functions having a denominator of the numerators of the shaping filters corresponding to the disturbance frequencies to be suppressed according to the estimated position error. Generating state information, calculating a plurality of disturbance suppression values of the actuator from the state information, and adding the plurality of disturbance suppression values;
A disk device characterized by the above. The control unit generates state information using an estimated gain of the disturbance model with the numerator of a first-order or second-order filter that shapes a sensitivity function according to a desired disturbance frequency, and the state The disk device according to claim 1, wherein a disturbance suppression value of the actuator is calculated from information. The control unit generates state information using an estimated gain of the disturbance model having a zero of the numerator of the filter that shapes the sensitivity function according to a desired disturbance frequency, and from the state information, the state information The disk device according to claim 1, wherein a disturbance suppression value of the actuator is calculated. In a head position control device for positioning a head for reading at least data on a disk storage medium at a predetermined position of the disk storage medium by controlling an actuator by observer control,
A position error is calculated from the target position of the head and the current position obtained from the head, an estimated position is calculated by observer control, an estimated position error is calculated from the position error and the estimated position, and the calculated A controller model for calculating a control value of the actuator from state information generated using an estimated gain of the actuator according to an estimated position error;
A model that is added to the controller model and defined by a transfer function with the denominator of the shaping filter that has the same denominator as the denominator that shapes the sensitivity function, and is calculated by the controller model According to the estimated position error, a disturbance model for calculating a disturbance suppression value of the actuator from state information generated using an estimated gain of disturbance,
An addition block for driving the actuator by adding the control value calculated by the controller model and the disturbance suppression value calculated by the disturbance model;
Have
The disturbance model uses estimated gains of disturbances of a plurality of models defined by transfer functions having a denominator of the numerators of the shaping filters corresponding to the disturbance frequencies to be suppressed according to the estimated position error. Generating state information, calculating a plurality of disturbance suppression values of the actuator from the state information, and adding the plurality of disturbance suppression values;
A head position control device. A head position control method executed by a head position control device that positions at least a head for reading data of a disk storage medium at a predetermined position of the disk storage medium by controlling an actuator by observer control,
The head position control device includes a control unit and a storage unit, and is executed in the control unit.
The controller model calculates a position error from the target position of the head and the current position obtained from the head, calculates an estimated position by observer control, calculates an estimated position error from the position error and the estimated position, In accordance with the calculated estimated position error, calculating a control value of the actuator from state information generated using the estimated gain of the actuator;
The disturbance model added to the controller model is a model defined by a transfer function having the denominator of the shaping filter having the same numerator order as the denominator for shaping the sensitivity function, and is calculated by the controller model. Calculating a disturbance suppression value of the actuator from state information generated using an estimated gain of disturbance according to the estimated position error,
An addition block adding the control value calculated by the controller model and the disturbance suppression value calculated by the disturbance model to drive the actuator;
Including
The disturbance model uses estimated gains of disturbances of a plurality of models defined by a transfer function having a denominator of the numerators of the shaping filters corresponding to the plurality of disturbance frequencies to be suppressed according to the estimated position error. Generating state information, calculating a plurality of disturbance suppression values of the actuator from the state information, and adding the plurality of disturbance suppression values;
A head position control method.

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