JP2006277833A - Sudden disturbance estimation device and tracking controller, and sudden disturbance estimation method in tracking controller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tracking controller in which the followup performance to the track position of a disk by the sudden disturbance is not spoiled by estimating and compensating the sudden disturbance. <P>SOLUTION: In a tracking controller 1, a sudden disturbance estimation device 3 which is equipped with; a tracking error delay control means 31 which successively stores a tracking error signal and delays it; a disturbance tracking error generating means 33a which generates a tracking error on the basis of the difference between the delayed tracking error signal and a tracking error signal at the present time; a manipulated variable delay control means 32 which successively stores a manipulated variable and delays it; a disturbance manipulated variable error generating means 33b which generates a manipulated variable error on the basis of difference between the delayed manipulated variable and a manipulated variable at the present time; and a disturbance calculating means 33c which calculates the amount of sudden disturbance which compensates the sudden disturbance on the basis of the tracking error and the manipulated variable error, is added to a feedback control system 2. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a tracking control technique, and more particularly to a sudden disturbance estimation device that estimates sudden disturbance, a tracking control device that performs tracking control by estimating sudden disturbance, and a sudden disturbance estimation method in the tracking control device.

  In general, a disk recording / reproducing apparatus generally performs two operations in order to cause the light spot position of the light beam emitted from the optical head to follow the target track position on the disk at high speed and stably. Is going. One is a coarse operation in which the tracking servo is turned off and the optical head pickup is moved to the vicinity of the target track position by the linear motor. The other is the tracking servo is turned on and the voice coil motor is picked up at the target track position. It is a fine operation to follow.

Conventionally, tracking in this fine operation has been realized by feedback control that corrects an error between the track position caused by disturbances such as eccentricity and vibration of the disk and the light spot position by feeding back the light spot position.
Conventionally, in a tracking control device that controls tracking by a feedback control system, a disturbance observer (disturbance observer) is provided in the feedback control system, and there is a technique for estimating a disturbance using the disturbance observer (for example, Patent Document 1).
JP 2001-210032 A (paragraphs 0065 to 0073, FIGS. 11 and 12)

  However, the conventional tracking control device collectively estimates and compensates for disturbances (periodic disturbances and sudden disturbances) using a disturbance observer. For this reason, it is not possible to remove the periodic disturbance feature from the disturbance to separate only the component of the sudden disturbance, and if a sudden disturbance occurs, the periodic disturbance compensation will be affected. There is a problem that the performance of following the track position is degraded.

  The present invention has been made in view of the above-described problems. The sudden disturbance estimation device and method capable of estimating only the sudden disturbance from the disturbance, and the sudden disturbance are estimated and compensated. Accordingly, it is an object of the present invention to provide a tracking control device that does not impair the follow-up performance of the disk to the track position due to sudden disturbance.

  The present invention was devised to achieve the above object. First, the sudden disturbance estimation device according to claim 1 includes a track position on a disk and a light spot of a light beam emitted from an optical head. In a tracking control device having feedback control means for compensating for the amplitude and phase of a tracking error signal indicating an error from the position and generating an operation amount for correcting the light spot position, sudden disturbance inputted from outside A sudden disturbance estimation device for estimating a quantity, comprising a tracking error delay control means, a disturbance tracking error generation means, an operation amount delay control means, a disturbance operation amount error generation means, and a disturbance calculation means .

  In such a configuration, the sudden disturbance estimation device sequentially stores and delays the tracking error signal, which is an error between the track position and the light spot position, by the tracking error delay control means. Then, the sudden disturbance estimation device detects the tracking error that is the amount of change in the track position based on the difference between the tracking error signal delayed by the tracking error delay control means by the disturbance tracking error generation means and the current tracking error signal. Is generated. This tracking error is an error caused by sudden disturbance, and is a data amount used for estimating the sudden disturbance amount for correcting the operation amount.

  The sudden disturbance estimation device sequentially stores and delays the operation amount generated by the feedback control unit by the operation amount delay control unit. Then, the sudden disturbance estimation device has an operation amount error that is a change amount of the operation amount based on a difference between the operation amount delayed by the operation amount delay control unit by the disturbance operation amount error generation unit and the current operation amount. Is generated. This operation amount error is an error caused by sudden disturbance, and is a data amount used for estimating the sudden disturbance amount for correcting the operation amount.

  Then, the sudden disturbance estimation device uses the disturbance calculation unit to calculate the current operation amount based on the tracking error generated by the disturbance tracking error generation unit and the operation amount error generated by the disturbance operation amount error generation unit. Thus, a sudden disturbance amount (sudden disturbance estimation amount) for compensating for the sudden disturbance is calculated. The sudden disturbance estimated amount can be calculated based on an arithmetic expression that becomes a predetermined disturbance observer.

  Further, the sudden disturbance estimation device according to claim 2 is the sudden disturbance estimation device according to claim 1 and further includes sudden disturbance detection means.

  In such a configuration, the sudden disturbance estimation device detects a sudden disturbance by the sudden disturbance detection means, and based on the detection result, a switching signal indicating whether or not to stop storing the tracking error signal and the operation amount at the present time. And output to the tracking error delay control means and the operation amount delay control means.

As a result, the tracking error delay control means and the operation amount delay control means can be controlled so as not to store the tracking error signal and the operation amount at the time when the sudden disturbance occurs. That is, in the tracking error delay control means and the operation amount delay control means, the information subjected to delay control (tracking error signal, operation amount) is obtained by removing the influence of sudden external disturbance.
In order to detect the occurrence of sudden disturbance, a general vibration sensor can be used. For example, it can be detected by a sensor that detects physical quantities such as displacement, speed, and acceleration.

  Furthermore, the sudden disturbance estimation apparatus according to claim 3 is the sudden disturbance estimation apparatus according to claim 2, wherein the sudden disturbance detection means includes an acceleration detection means, a signal conversion means, a voltage level determination means, and a switch. And a signal generation means.

  In this configuration, the sudden disturbance estimation device detects the acceleration of the sudden disturbance as an acceleration signal by the acceleration detection means, and converts the acceleration signal detected by the acceleration detection means into a voltage signal by the signal conversion means. Then, the sudden disturbance estimation device compares the voltage signal converted by the signal conversion unit with a predetermined threshold value by the voltage level determination unit, and determines whether the voltage signal has changed across the threshold value. To do. It is possible to determine whether or not sudden disturbance has occurred by appropriately setting the predetermined threshold. This threshold is, for example, a voltage level that is larger than the normally included small random noise and can be observed as an impact, and is a voltage level at which the control system does not become unstable due to sudden disturbance.

  In the sudden disturbance estimation device, the switching signal generation unit generates a switching signal indicating whether or not to stop the storage of the tracking error signal and the operation amount at the present time based on the determination result of the voltage level determination unit. That is, when the voltage signal is larger than the threshold value (when sudden disturbance occurs), the switching signal generation unit stops storing the tracking error signal and the operation amount at the current time, and when the voltage signal is smaller than the threshold value (suddenly When the disturbance disappears, a switching signal indicating that the current tracking error signal and operation amount are stored is output to the tracking error delay control means and the operation amount delay control means.

  The sudden disturbance estimation device according to claim 4 is the sudden disturbance estimation device according to claim 1, wherein the disturbance calculation unit includes a differential value calculation unit, and the sudden disturbance estimation device further includes a switching determination unit. The configuration.

  In such a configuration, the sudden disturbance estimation device calculates the amount of change per unit time of the sudden disturbance estimation amount, that is, the differential value, as the differential value estimation amount by the differential value calculation means of the disturbance calculation means. When the current value that is the sudden disturbance estimated amount crosses the value “0” (changes between plus and minus), the amount of change may be large even if the sudden disturbance estimated amount is small. That is, the differential value estimation amount is data for determining whether or not a sudden disturbance has occurred, as with the sudden disturbance estimation amount.

  Therefore, the sudden disturbance estimation device uses the switching determination means based on the sudden disturbance estimated amount calculated by the disturbance calculating means and the differential value estimated amount calculated by the differential value calculating means and the current tracking error signal and operation. A switching signal indicating whether or not to stop the amount storage is output to the tracking error delay control means and the operation amount delay control means.

  As a result, the tracking error delay control means and the operation amount delay control means can be controlled so as not to store the tracking error signal and the operation amount at the time when the sudden disturbance occurs. That is, in the tracking error delay control means and the operation amount delay control means, the information subjected to delay control (tracking error signal, operation amount) is obtained by removing the influence of sudden external disturbance.

  Furthermore, the sudden disturbance estimation device according to claim 5 is the sudden disturbance estimation device according to claim 4, wherein the switching determination means includes a disturbance estimated amount comparison means, a differential value estimated amount comparison means, and a switching signal generation. Means.

  In such a configuration, the sudden disturbance estimation device compares the magnitude of the sudden disturbance estimation amount with a predetermined threshold by the disturbance estimation amount comparison unit, and compares the magnitude of the differential value estimation amount with the differential value estimation amount comparison unit. Compare with a predetermined threshold value. That is, the magnitude (absolute value) of the sudden disturbance estimator and the magnitude (absolute value) of the differential value estimator are data for determining whether or not the sudden disturbance has occurred. Based on the result, it is possible to determine whether or not a sudden disturbance has occurred.

  Therefore, the sudden disturbance estimation device determines that the sudden disturbance has occurred when any one of the sudden disturbance estimation amount and the differential value estimation amount is larger than each threshold by the switching signal generation unit, and the tracking error signal at the present time And a switching signal indicating that the operation amount storage is to be stopped is generated and output to the tracking error delay control means and the operation amount delay control means. Each threshold is a voltage level that is larger than the normal random noise included and can be observed as an impact, and is set in advance at a voltage level at which the control system does not become unstable due to sudden disturbance.

  The tracking control apparatus according to claim 6 compensates for an amplitude and a phase of a tracking error signal indicating an error between a track position on the disk and a light spot position of a light beam emitted from the optical head, 6. A sudden disturbance estimation device according to claim 1, and a disturbance operation amount generation unit according to claim 1, wherein the tracking control device includes a feedback control unit that generates an operation amount for correcting the light spot position. It was set as the structure provided with.

  In such a configuration, the tracking control device estimates the magnitude of the sudden disturbance input from the outside as the sudden disturbance amount (sudden disturbance estimation amount) by the sudden disturbance estimation device. Then, the tracking control device adds the sudden disturbance amount estimated by the sudden disturbance estimation device and the operation amount generated by the feedback control unit by the disturbance manipulation amount generation unit, thereby correcting the sudden disturbance. A sudden disturbance operation amount is generated.

  Furthermore, the sudden disturbance estimation method according to claim 7 compensates for an amplitude and a phase of a tracking error signal indicating an error between a track position on a disk and a light spot position of a light beam emitted from an optical head, In the tracking control device including a feedback control unit that generates an operation amount for correcting the light spot position, a sudden disturbance estimation method for estimating a sudden disturbance amount for correcting the operation amount accompanying the occurrence of the sudden disturbance Thus, the procedure includes a disturbance tracking error generation step, a disturbance operation amount error generation step, and a disturbance calculation step.

  In this procedure, the sudden disturbance estimation method generates a tracking error that is a change amount of the track position based on the difference between the delayed past tracking error signal and the current tracking error signal in the disturbance tracking error generation step. To do. This tracking error is an error caused by sudden disturbance, and is a data amount used for estimating the sudden disturbance amount for correcting the operation amount.

  Further, the sudden disturbance estimation method generates an operation amount error that becomes a change amount of the operation amount based on a difference between the delayed past operation amount and the current operation amount in the disturbance operation amount error generation step. This operation amount error is an error caused by sudden disturbance, and is a data amount used for estimating the sudden disturbance amount for correcting the operation amount.

  Therefore, the sudden disturbance estimation method uses the tracking error generated in the disturbance tracking error generation step in the disturbance calculation step and the operation amount error generated in the disturbance operation amount error generation step to Thus, a sudden disturbance amount (sudden disturbance estimation amount) for compensating for the sudden disturbance is calculated.

  According to the invention described in claim 1, claim 6 or claim 7, it is possible to separate and estimate the sudden disturbance from the disturbance. By this, when a sudden disturbance occurs, a sudden disturbance amount (sudden disturbance estimation amount) that compensates only the sudden disturbance that does not affect the compensation of the periodic disturbance is added to the feedback control system in the tracking control device. Accordingly, the tracking performance of the disk in the tracking control device can be improved.

  According to the second aspect of the present invention, when a sudden disturbance occurs, it is possible to stop storing the tracking error signal and the operation amount at the present time, so that the tracking error signal output from the tracking error delay control means, The operation amount output from the operation amount delay control means is data from which sudden disturbance has been removed. As a result, the disturbance calculation means can prevent the estimation of the sudden disturbance amount from the data at the time when the sudden disturbance has occurred and the data at the time when the sudden disturbance has occurred in the past. Can be estimated.

  According to the third aspect of the present invention, it is determined whether a sudden disturbance has occurred based on the voltage signal converted from the detected acceleration and a predetermined threshold value, and based on the determination result, A switching signal for controlling the storage of the tracking error signal and the operation amount can be generated. As a result, when sudden disturbance occurs, control can be performed so as not to be affected by sudden disturbance.

  According to the fourth aspect of the present invention, since it is possible to determine whether or not the sudden disturbance has occurred only by calculation without providing an acceleration detection means such as an acceleration sensor, the scale of the entire apparatus can be reduced, and the cost can be reduced. Down can be realized.

  According to the fifth aspect of the present invention, it is determined that a sudden disturbance has occurred when either the magnitude of the sudden disturbance estimated amount or the differential value estimated amount is larger than the threshold value. Even when the estimated amount is small and the current value that is the sudden disturbance estimated amount changes between plus and minus, it is possible to reliably detect the sudden disturbance.

[First Embodiment]
In the following, first, in the tracking control device of the first embodiment, a periodic disturbance component due to eccentricity of the disk is separated from the disturbance input to the control system when performing the tracking control, and suddenly from the outside. A method for estimating only the sudden disturbance applied to the tracking control device including the sudden disturbance estimation device for estimating the sudden disturbance based on the component of the sudden disturbance extracted by the method; To do.

[Estimation of sudden disturbance]
In general, a tracking control apparatus having a feedback control system estimates a change amount (tracking error) of a track position based on a tracking error signal generated by the feedback control system. Here, the feedback control system, in a certain sampling time k, when only periodic disturbance x ^ref (k) are inputted, the correction of the tracking error (correction tracking error signal) e _t ^feedback (k) periodically Based on the tracking error x _f (k) due to external disturbance, the following equation (1) is used.

e _t ^feedback (k) = x ^ref (k) −x _f (k) (1)

  The periodic tracking error (corrected tracking error signal) shown in the equation (1) becomes an error based on the tracking control of the previous one rotation of the disk. By performing control based on this error, a more accurate period can be obtained. It is possible to determine the influence of external disturbance.

Here, with reference to FIG. 2, the input / output relationship of the light spot position correcting means (voice coil motor) which is the control target in the control system of the tracking control apparatus will be described. FIG. 2 is a schematic diagram schematically showing a control system of a general tracking control device.
As shown in FIG. 2, the control system 5 uses a light spot position correcting means (voice coil motor) at a certain sampling time point k based on the periodic disturbance x ^ref (k) and the sudden disturbance I _d (k). 51 is a model for controlling 51. Here, the light spot position x (k) output from the light spot position correcting means (voice coil motor) 51 is expressed by the tracking error x _f (k) due to periodic disturbance as shown in the following equation (2). The tracking error x _d (k) due to sudden disturbance is added.

x (k) = x _f (k) + x _d (k) (2)

Further, the tracking error signal _et (k) input to the periodic disturbance control system 52 includes a periodic disturbance x ^ref (k) and a light spot position x (k) as shown in the following equation (3). ) And the difference.

e _t (k) = x ^ref (k) −x (k) = x ^ref (k) −x _f (k) −x _d (k) (3)

Furthermore, the current (correction manipulated _variable I _cmd (k)) for compensating for the disturbance to the light spot position correcting means 51 becomes a tracking error x _d (k) due to sudden disturbance as shown in the following equation (4). Based on the current compensated by the sudden disturbance control system 53 (sudden disturbance compensation I _b (k)) and the tracking error x _f (k) due to the periodic disturbance, the current was compensated by the periodic disturbance control system 52. The current (periodic disturbance compensation I _f (k)) is added.

I _cmd (k) = I _b (k) + I _f (k) (4)

Thus, in the control system 5, the current (correction operation amount I _cmd (k)) for compensating for the disturbance input to the light spot position correcting unit 51 changes due to the influence of the disturbance, and the light spot position changes. Will do.
Here, when the transfer function of the light spot position correcting means 51 is P (z ⁻¹ ), the tracking error x _d (k) due to sudden disturbance and the tracking error x _f (k) due to periodic disturbance are respectively (5) and (6).

x _d (k) = P (z ⁻¹ ) (I _b (k) −I _d (k)) (5) Expression x _f (k) = x ^ref (k) −P (z ⁻¹ ) I _f (K) Expression (6)

The equations (5) and (6) indicate the input / output relationship of the sudden disturbance feedback control system and the periodic disturbance feedback control system in the control system 5, respectively. That is, as shown in FIG. 3, the control system 5 is divided into a sudden disturbance feedback control system 5A (FIG. 3A) and a periodic disturbance feedback control system 5B (FIG. 3B). Can be represented. FIG. 3 is an explanatory diagram for explaining a sudden disturbance feedback control system and a periodic disturbance feedback control system.
As shown in FIG. 3A, in the sudden disturbance feedback control system 5A, the current input to the light spot position correcting means 51 is the sudden disturbance and the current (I _d (k) and compensation for the sudden disturbance). I _b (k)) only, and the output is a tracking error x _d (k) due to sudden disturbance.
Further, the following expression (7) is derived from the expressions (1) and (3), and the following expression (8) is derived from the expression (4).

e _t (k) −e _t ^feedback (k)
_{^{= X ref (k) -x f}} (k) -x d (k) -x ref (k) + x f (k)
= −x _d (k) (7) Formula I _b (k) = I _cmd (k) −I _f (k) (8) Formula

As shown in (7), by using a tracking error e ^{_t? Feedback} (k), it is possible to eliminate the periodic disturbance. Further, as shown in the equation (8), by periodically subtracting the periodic disturbance compensation I _f (k) from the correction operation amount I _cmd (k) which is a current for compensating the disturbance to the light spot position correcting unit 51. The sudden disturbance compensation I _b (k) can be calculated. That is, on the basis of the equations (7) and (8), a control object (expanded plant) in which periodic disturbance is excluded from the light spot position correcting unit 51 that is the control object (plant) can be realized in a pseudo manner. it can.

  This expansion plant can be represented in FIG. FIG. 4 is a conceptual diagram showing a concept for realizing an expansion plant excluding periodic disturbances. As shown in FIG. 4, with respect to a plant system (actual plant system) 61 including a control target (plant) to which periodic disturbance and sudden disturbance are input, the above expressions (7) and (8) are By applying, the expansion plant 63 from which the plant system 62 excluding the periodic disturbance is extracted can be configured.

  As described above, since the expansion plant 63 shown in FIG. 4 excludes periodic disturbances, it is robust against noise and changes in track position (becomes robust). Therefore, it is possible to estimate sudden disturbance by configuring a disturbance observer (disturbance observer) for the expansion plant 63.

Hereinafter, when a disturbance observer is configured for the expansion plant 63, the following is obtained.
That is, when the light spot position correcting unit 51 is expressed by the following equation (9) as a discrete time state equation using the state variable x _p (k), the state equation and the output equation of the expansion plant 63 are as follows: (10). A, B, and C are coefficient matrices constituting the discrete time state equation of the light spot position correcting means 51.

x _p (k + 1) = Ax _p (k) + BI _b (k) + BI _d (k)
x _d (k) = Cx _p (k) (9)

When the minimum dimension observer is configured using the sudden disturbance compensation I _b (k) which is an input in the equation (10) and the tracking error x _d (k) due to the sudden disturbance which is an output, the following equation (11) is obtained. It becomes. As a general method for constructing this minimum dimension observer, there is a Gopinus design method.

  When the disturbance observer configured by the equation (11) is rewritten based on the equations (7) and (8), the following equation (12) is obtained.

The present invention makes it possible to estimate a sudden disturbance (estimate the sudden disturbance estimated amount I _d2 (k)) by using the disturbance observer shown in the equation (12). Hereinafter, a sudden disturbance estimation device indicated by the disturbance observer and a tracking control device including the sudden disturbance estimation device will be described.

[Configuration of tracking controller]
First, the configuration of the tracking control apparatus according to the present invention will be described with reference to FIG. FIG. 1 is a block diagram showing the configuration of the tracking control apparatus according to the first embodiment.
As shown in FIG. 1, a tracking control device 1 is used to set the light spot position of a light beam emitted from an optical head on a disk in a recording / reproducing apparatus for a disk medium such as an optical disk, a magneto-optical disk, or a magnetic disk. It follows the track position.

The tracking control apparatus 1 includes a tracking error signal generation unit 20, an A / D conversion unit 21, a feedback control unit 22, a disturbance operation amount generation unit (addition unit) 23, a D / A conversion as a feedback control system 2. Means 24 and light spot position correction means 25 are provided, and a sudden disturbance estimation device 3 is further added.
Here, the feedback control system 2 acts to correct an error (periodic disturbance) between the periodic track position and the light spot position accompanying the rotation of the disk and a sudden disturbance externally applied. The sudden disturbance estimation device 3 functions to predict and correct errors due to disturbance that cannot be removed by the feedback control system 2. Note that the subtracting means D in FIG. 1 is a pseudo representation of the effect of sudden disturbance on the feedback control system 2, and is not an actual configuration.

(Configuration of feedback control system)
First, the configuration of the feedback control system 2 will be described.
The tracking error signal generation means 20 detects the difference (error) between the current track position (periodic disturbance) and the corrected light spot position output from the light spot position correction means 25, and the difference amount (error) Quantity) as a tracking error signal. The tracking error signal generated here is output to the A / D conversion means 21.

The A / D conversion means 21 converts the tracking error signal, which is an analog signal generated by the tracking error signal generation means 20, into a digital signal. For example, the A / D conversion means 21 is a sampler that samples at a certain time interval. This digitalized tracking error signal _et (k) is output to the feedback control means 22, the first signal switching means SW1 of the sudden disturbance estimation device 3, and the disturbance tracking error generation means 33a.

The feedback control means (C (z ⁻¹ )) 22 is a general robust controller, but may be a classic phase advance / delay controller, so that the phase delay is corrected and the resonance frequency is not increased. Is operated as a transfer function C (s) acting on the signal, and an operation amount I _c (k) for correcting the light spot position is generated from the tracking error signal _et (k). Here, since the digital signal is handled, the transfer function C (s) is represented by C (z ⁻¹ ) which is a discrete time expression. This operation amount I _c (k) is an operation amount for correcting an error between the periodic track position accompanying the rotation of the disk and the light spot position. This manipulated variable is output to the disturbance manipulated variable generating means 23.

The disturbance operation amount generation means 23 estimates the sudden disturbance amount I _c (k) generated by the feedback control means 22 and the sudden disturbance amount generated by the disturbance calculation means 33c of the sudden disturbance estimation device 3. By adding _d2 (k), a sudden disturbance manipulated variable (sudden disturbance compensation: I _cmd (k)) for compensating sudden disturbance is generated. The sudden disturbance manipulation amount generated here is output to the disturbance manipulation amount error generation means 33b and the second signal switching means SW2 of the sudden disturbance estimation device 3 and the D / A conversion means 24.

The D / A conversion unit 24 converts the sudden disturbance operation amount I _cmd (k) that is a digital signal generated by the disturbance operation amount generation unit 23 into an analog signal. For example, the D / A conversion means 24 is a zero order hold (ZOH: Zero Order Hold) that generates an analog signal by piecewise linearizing an input signal between sampling cycle times. The sudden disturbance operation amount converted into an analog signal is output to the light spot position correcting means 25.

  The light spot position correction means (P (s)) 25 corrects the light spot position based on the sudden disturbance operation amount converted into an analog signal by the D / A conversion means 24. Here, the light spot position correcting means (P (s)) 25 is a current-driven voice coil motor of the tracking actuator, and operates as a transfer function P (s). The light spot position generated here is input to the tracking error signal generation means 20, whereby the feedback control system 2 is formed.

(Configuration of sudden disturbance estimation device)
Next, the configuration of the sudden disturbance estimation device 3 will be described. Here, the sudden disturbance estimation device 3 includes sudden disturbance detection means 30, tracking error delay control means 31, and manipulated variable delay control means 32.

  The sudden disturbance detection means 30 detects sudden disturbance, and generates a switching signal for controlling the operation of the first signal switching means SW1 and the second signal switching means SW2 according to the presence or absence of the sudden disturbance.

  Here, the configuration of the sudden disturbance detection means 30 will be described with reference to FIG. FIG. 5 is a block diagram showing the configuration of the sudden disturbance detection means. Here, the sudden disturbance detection means 30 includes an acceleration detection means 30a, a signal conversion means 30b, a voltage level determination means 30c, and a switching signal generation means 30d.

  The acceleration detection means 30a detects acceleration, and is constituted by, for example, an acceleration sensor. The acceleration (acceleration signal) detected by the acceleration detection means 30a is output to the signal conversion means 30b. In general, a mechanical disturbance is represented by a product of mass and acceleration, so that the acceleration detected by the acceleration detecting means 30a corresponds to a sudden disturbance.

  The signal converter 30b converts the acceleration signal detected by the acceleration detector 30a into a voltage signal. The voltage signal converted by the signal conversion unit 30b is output to the voltage level determination unit 30c.

The voltage level determination unit 30c compares the voltage signal input from the signal conversion unit 30b with a predetermined threshold value to determine whether there is a sudden disturbance. This predetermined threshold value (absolute value) | V _TH | is a voltage level that is larger than the normally included minute random noise and can be observed as an impact, and is a voltage level at which the control system does not become unstable due to sudden disturbance. The threshold value | V _TH | can be arbitrarily adjusted.
The voltage level determination means 30c determines that a sudden disturbance has occurred when it is determined that the voltage signal input from the signal conversion means 30b is larger than the threshold value | V _TH |, and the determination result is generated as a switching signal. Output to means 30d.
The voltage level determination unit 30c determines that no sudden disturbance has occurred when determining that the voltage signal input from the signal conversion unit 30b is smaller than the threshold value | V _TH |, and determines the determination result as a switching signal. Output to the generating means 30d.

The switching signal generating means 30d generates a switching signal based on the determination result input from the voltage level determining means 30c, and supplies the generated switching signal to the first signal switching means SW1 and the second signal switching means SW2. It is.
The switching signal generating unit 30d, when the sudden disturbance from the voltage level determination means 30c is input to the determination result that has occurred, switches the first signal switching means SW1 to the terminal b ₁ side and the second signal A switching signal V _{sw +} is generated to control the switching means SW2 to switch to the terminal b ₂ side.
Further, the switching signal generation means 30d switches the first signal switching means SW1 to the terminal a ₁ side when the determination result that the sudden disturbance has not occurred from the voltage level determination means 30c and the second signal switching means SW1. A switching signal V _sw− for controlling the signal switching means SW2 to switch to the terminal a ₂ side is generated.
Returning to FIG. 1, the description of the configuration of the sudden disturbance estimation device 3 will be continued.

  The tracking error delay control means 31 performs delay control of the tracking error signal converted into a digital signal by the A / D conversion means 21. Here, the tracking error delay control unit 31 includes a first signal switching unit SW1, a first storage control unit 31a, a first storage unit 31b, and a first phase adjustment unit 31c.

The first signal switching means SW1 includes a terminal (common terminal) o ₁ , a terminal (always connected terminal) a ₁ and a terminal (always open terminal) b ₁ , and selects the terminal a ₁ and the terminal b ₁ as contact points. The signal output from the terminal o ₁ (the signal input to the first storage control means 31a) is connected by switching one of them to the terminal o ₁ connected to the input of the first storage control means 31a. It is to switch.
Here, the first signal switching means SW1 switches the connection terminals based on the switching signal output from the sudden disturbance detection means 30.
Here, the terminal a ₁ is connected to the output of the A / D conversion means 21 and the terminal b ₁ is connected to the output of the first phase adjustment means 31 c. Usually, the first signal switching means SW1 is switched to the terminal a ₁ side. At this time, the output signal (tracking error signal) output from the A / D conversion means 21 is input to the first storage control means 31a. . Further, when the sudden disturbance occurs, the first signal switching means SW1 is switched to the terminal b ₁ side, at this time, the output signal of the first phase adjusting means 31c is input to the first storage control unit 31a.

  The first storage control unit 31a writes the tracking error signal output from the A / D conversion unit 21 for a time corresponding to at least one rotation period of the optical disc in time series to the first storage unit 31b and is already stored. This tracking error signal is read out from the first storage means 31b and output to the first phase adjustment means 31c.

  The first storage unit 31b is configured by a general memory or the like, and stores the tracking error signal converted into a digital signal by the A / D conversion unit 21.

The first phase adjusting means 31c is for adjusting the phase of the current tracking error signal and the delayed tracking error signal. Here, the first phase adjusting means 31c is advanced second sampling output from the first storage control unit 31a tracking error signal e ^{_t? Feedback} the (k + 2), the delay means not shown, by 2 sample delay The phase with the current tracking error signal _et (k) is matched. Here delayed the tracking error signal e _t ^feedback (k) includes a first signal switching means SW1, is output to the disturbance tracking error generating means 33a sudden disturbance calculating unit 33.

  The operation amount delay control unit 32 performs delay control of the sudden disturbance operation amount generated by the disturbance operation amount generation unit 23. Here, the operation amount delay control unit 32 includes a second signal switching unit SW2, a second storage control unit 32a, a second storage unit 32b, and a second phase adjustment unit 32c.

The second signal switching means SW2 includes a terminal (common terminal) o ₂ , a terminal (always connected terminal) a ₂ and a terminal (always open terminal) b ₂ , and selects the terminal a ₂ and the terminal b ₂ as contact points. The signal output from the terminal o ₂ (the signal input to the second storage control means 32a) is connected by switching one of them to the terminal o ₂ connected to the input of the second storage control means 32a. It is to switch.
Here, the second signal switching means SW2 switches the connection terminals based on the switching signal output from the sudden disturbance detection means 30.
Here, the terminal a ₂ is connected to the output of the disturbance manipulated variable generating means 23, and the terminal b ₂ is connected to the output of the second phase adjusting means 32c. Normally, the second signal switching means SW2 is switched to the terminal a ₂ side. At this time, the output signal (sudden disturbance operation amount) output from the disturbance operation amount generation means 23 is input to the second storage control means 32a. The Further, when the sudden disturbance occurs, the second signal switching means SW2 is switched to the terminal b ₂ side, at this time, the output signal of the second phase adjusting means 32c is input to the second storage control unit 32a.

  The second storage control unit 32a writes the sudden disturbance operation amount output from the disturbance operation amount generation unit 23 for a time corresponding to at least one rotation period of the optical disc to the second storage unit 32b in time series and is already stored. The sudden disturbance operation amount is read from the second storage means 32b and output to the second phase adjustment means 32c.

  The second storage unit 32b is configured by a general memory or the like, and stores the sudden disturbance operation amount generated by the disturbance operation amount generation unit 23.

The second phase adjusting means 32c adjusts the phase of the current sudden disturbance operation amount and the delayed sudden disturbance operation amount. Here, the second phase adjusting unit 32c delays the sampling disturbance operation amount I _cmd (k + 2) advanced by 2 samples output from the second storage control unit 32a by 2 sampling delays by a delay unit (not shown). The phase with the sudden disturbance manipulated _variable I _cmd (k) is matched. The sudden disturbance operation amount I _cmd (k) delayed here is output to the second signal switching means SW 2 and the disturbance operation amount error generation means 33 b of the sudden disturbance calculation means 33.

  The sudden disturbance calculation means 33 is input from the current tracking error signal input from the A / D conversion means 21, the tracking error signal delay-controlled by the tracking error delay control means 31, and the disturbance operation amount generation means 23. Based on the sudden disturbance operation amount at the present time and the sudden disturbance operation amount that is delay-controlled by the operation amount delay control means 32, a sudden disturbance estimation amount that estimates the sudden disturbance is generated. Here, the sudden disturbance calculation means 33 includes a disturbance tracking error generation means 33a, a disturbance operation amount error generation means 33b, and a disturbance calculation means 33c.

Disturbance tracking error generating means (subtracting means) 33a comprises a tracking error signal e _t (k), by taking the difference between the delayed controlled tracking error signal e ^{_t? Feedback} (k), the change in track position by sudden disturbance A tracking error x _d (k), which is a quantity, is generated. The tracking error x _d (k) generated here corresponds to the tracking error x _d (k) due to the sudden disturbance in the equation (7). The tracking error x _d (k) due to the sudden disturbance calculated here is output to the disturbance calculating means 33c.

The disturbance operation amount error generation means (subtraction means) 33b takes the difference between the sudden disturbance operation amount I _cmd (k) and the delay-controlled sudden disturbance operation amount I _cmd (k + 2), thereby the track position due to the sudden disturbance. The operation amount error (sudden disturbance compensation) I _b (k) indicating the error of the operation amount is generated. The manipulated variable error I _b (k) generated here corresponds to the sudden disturbance compensation I _b (k) due to the sudden disturbance in the equation (8). The operation amount error I _b (k) calculated here is output to the disturbance calculation means 33c.

The disturbance calculation means 33c is based on the tracking error x _d (k) generated by the disturbance tracking error generation means 33a and the operation amount error I _b (k) generated by the disturbance operation amount error generation means 33b. The correction amount (sudden disturbance estimated amount I _d2 (k)) for the operation amount for correcting the light spot position is estimated. That is, the disturbance calculation means 33c calculates the sudden disturbance estimated amount I _d2 (k) by sequentially performing the calculation of the equation (12). The sudden disturbance estimation amount I _d2 (k) calculated here is output to the disturbance operation amount generation means 23.

  In this way, by configuring the sudden disturbance estimation device 3, it is possible to distinguish between the periodic disturbance input to the feedback control system 2 and the sudden disturbance, and to estimate only the sudden disturbance.

  As described above, the feedback control system 2 of the tracking control device 1 includes the sudden disturbance estimation device 3 that can estimate only the sudden disturbance, so that only the sudden disturbance can be separated from the disturbance and compensation can be performed. Become.

[Operation of tracking controller]
Next, the operation of the tracking control device according to the first embodiment will be described. Here, the operation of the tracking control device will be described separately for the feedback control operation and the sudden disturbance estimation operation.

(Feedback control operation)
First, the feedback control operation of the tracking control device will be described with reference to FIG. 6 (refer to FIG. 1 as appropriate). FIG. 6 is a flowchart showing the feedback control operation of the tracking control device.
First, the tracking control device 1 uses the tracking error signal generation means 20 to generate a difference between the track position and the light spot position as a tracking error signal (step S1). The tracking error signal generated here is converted into a digital signal by the A / D conversion means 21 (step S2), and is output to the feedback control means 22 and the sudden disturbance estimation device 3.

Then, the tracking control device 1 uses the feedback control means 22 to generate an operation amount (I _c (k)) for correcting the light spot position from the tracking error signal (step S3).
The tracking control device 1 also includes the operation amount I _c (k) generated in step S3 by the disturbance operation amount generation unit 23 and the sudden disturbance estimation amount I generated by the disturbance calculation unit 33c of the sudden disturbance estimation device 3. By adding _d2 (k), a sudden disturbance operation amount (sudden disturbance compensation: I _cmd (k)) for compensating sudden disturbance is generated (step S4).
The tracking control apparatus 1 converts the sudden disturbance operation amount I _cmd (k) generated in step S4 into an analog signal by the D / A conversion unit 24 (step S5), and then the light spot position correction unit 25. Thus, the light spot position is corrected by the operation amount converted into an analog signal (step S6).
Then, the tracking control device 1 returns to step S1 and continues the tracking operation while the disk is rotating (while the track position is input).

(Sudden disturbance estimation operation)
Next, the operation of the sudden disturbance estimation device 3 in the tracking control device 1 will be described with reference to FIGS. Here, the operation of the sudden disturbance estimation device 3 is divided into the signal switching operation of the first signal switching means SW1 and the second signal switching means SW2 by the sudden disturbance detection means 30 and the disturbance estimation operation by the sudden disturbance calculation means 33. explain.
FIG. 7 is a flowchart showing a signal switching operation in the sudden disturbance detecting means of the sudden disturbance estimating device. FIG. 8 is a flowchart showing the disturbance estimation operation in the sudden disturbance calculation means of the sudden disturbance estimation device.

First, the signal switching operation of the first signal switching means SW1 and the second signal switching means SW2 will be described with reference to FIG. 7 (refer to FIGS. 1 and 5 as appropriate). Normally, the first signal switching means SW1 and the second signal switching means SW2 are switched to the a ₁ side and the a ₂ side, respectively.

First, the sudden disturbance estimation device 3 detects an acceleration signal corresponding to the sudden disturbance by the acceleration detection means 30a of the sudden disturbance detection means 30 (step S21).
Then, the sudden disturbance estimation device 3 converts the acceleration signal detected by the acceleration detection means 30a into the voltage signal Va by the signal conversion means 30b (step S22).
Furthermore, the sudden disturbance estimation device 3 determines whether or not the voltage signal Va is larger than the threshold by the voltage level determination unit 30c. Specifically, the absolute value | Va | of the amplitude level of the detected voltage signal (acceleration converted voltage) is detected (step S23), and this absolute value | Va | is compared with a threshold value | V _TH | It is determined whether or not | Va | is greater than | V _TH | (step S24).

If the sudden disturbance estimation device 3 determines that | Va | is not larger than | V _TH | (No in step S24), the sudden disturbance estimation device 3 returns to step S21 to detect an acceleration signal.
On the other hand, if the sudden disturbance estimation device 3 determines that | Va | is greater than | V _TH | (Yes in step S24), the switching signal generation means 30d generates the switching signal V _{sw +} (step S25). ). The switching signal V _{sw +} generated by the switching signal generating unit 30d is output to the first signal switching unit SW1 and the second signal switching unit SW2.
Then, the sudden disturbance estimation device 3 switches the contact of the first signal switching means SW1 from the terminal a ₁ side to the terminal b ₁ side and holds (latches) the state of the contact (step S26).
Further, the sudden disturbance estimation device 3 switches the contact of the second signal switching means SW2 from the terminal a ₂ side to the terminal b ₂ side, and holds (latches) the state of the contact (step S27).

Subsequently, the sudden disturbance estimation device 3 compares the absolute value | Va | of the amplitude level of the acceleration converted voltage with the threshold value | V _TH | by the voltage level determination unit 30c, and | Va | is | V _TH | Is also smaller (step S28).
Then, the sudden disturbance estimation device 3 continues the determination until | Va | becomes smaller than | V _TH |, and when it is determined that | Va | is smaller than | V _TH | (Yes in step S28), that is, sudden When the normal state without disturbance is restored, the switching signal generating means 30d generates the switching signal V _sw− (step S29). The switching signal V _sw− generated by the switching signal generating means 30d is output to the first signal switching means SW1 and the second signal switching means SW2. At this stage, the first signal switching means SW1 and the second signal switching means SW1 are output. The contact of the two-signal switching means SW2 is not affected. That is, the sudden disturbance estimation device 3 holds the contacts of the first signal switching means SW1 and the second signal switching means SW2 on the terminals b ₁ side and b ₂ side, respectively, and does not switch the contacts.

Then, the sudden disturbance estimation device 3 determines whether the number of samples stored in the first storage unit 31b and the second storage unit 32b is kN by the first storage control unit 31a and the second storage control unit 32a, respectively. (Step S30). Here, k represents a natural number, and N represents the number of samples corresponding to one rotation period of the disk delayed by the first phase adjusting unit 31c and the second phase adjusting unit 32c.
Here, when the sudden disturbance estimation device 3 determines that the number of samples is kN (Yes in step S30), the contact of the first signal switching means SW1 is switched from the terminal b ₁ side to the terminal a ₁ side (step S31). ), it switches the contact point of the second signal switching means SW2 through the terminal b ₂ side to the terminal a ₂ side (step S32), and the procedure returns to step S21.

Next, referring to FIG. 8 (refer to FIG. 1 as appropriate), the disturbance estimation operation in the sudden disturbance calculation means 33 of the sudden disturbance estimation device 3 will be described.
First, the sudden disturbance estimation device 3 includes a tracking error signal converted into a digital signal by the A / D conversion unit 21 by the disturbance tracking error generation unit 33a, and a tracking error signal subjected to delay control by the first phase adjustment unit 31c. The tracking error x _d (k) is generated by taking the difference (step S41; disturbance tracking error generation step).
Note that it is desirable to use the tracking error signal output from the first phase adjusting means 31c after executing the steps described in FIG.

Further, the sudden disturbance estimation device 3 includes the sudden disturbance operation amount generated by the disturbance operation amount generation unit 23 by the disturbance operation amount error generation unit 33b, and the sudden disturbance operation amount that is delay-controlled by the second phase adjustment unit 32c. The operation amount error I _b (k) indicating the operation amount error is generated (step S42; disturbance operation amount error generation step).
Note that it is desirable to use the sudden disturbance operation amount output from the second phase adjusting unit 32c after executing the steps described in FIG. 7 as the sudden disturbance operation amount that is delay-controlled in step S42.

Then, the sudden disturbance estimation device 3 determines the current time based on the tracking error x _d (k) generated in step S41 and the manipulated variable error I _b (k) generated in step S42 by the disturbance calculation means 33c. _Is calculated (estimated) with respect to the operation amount for correcting the light spot position (sudden disturbance estimated amount I _d2 (k)) (step S43; disturbance calculating step).
Then, the sudden disturbance estimation device 3 returns to step S41, and continues the sudden disturbance estimation operation while the disk is rotating (while the track position is input).

  Here, with reference to FIG. 9 (refer to FIG. 1 as appropriate), the timing of switching at each contact point of the first signal switching means SW1 and the second signal switching means SW2 performed in the sudden disturbance estimation device 3 will be described. FIG. 9 is a timing chart showing the switching timing of the switching signal and the first and second signal switching means.

As shown in FIG. 9A, the sudden disturbance occurs when True (1) and disappears when False (0).
As shown in FIG. 9B, the switching signal becomes V _{sw +} when the sudden disturbance shown in FIG. 9A is True (1), and becomes V _sw− when False (0). That is, the switching signal shown in (b) is switched from V _sw− to V _{sw +} when a sudden disturbance occurs. The switching signal generation unit 30d continues to output the switching signal V _{sw +} to the first signal switching unit SW1 and the second signal switching unit SW2 while the sudden disturbance continues. Then, the switching signal generating means 30d switches the switching signal from V _{sw +} to V _sw− when the sudden disturbance disappears (when it is no longer detected), and until the sudden disturbance is detected (during the normal state) ) _Continue to output the switching signal V _sw- .

Further, as shown in FIG. 9C, the contact of the first signal switching means SW1 is switched to the terminal a ₁ side in the initial state (time = 0) (always connected), and sudden disturbance has occurred. When the switching signal changes from V _sw− to V _{sw +} , the signal is switched to the terminal b ₁ side and the state is latched (held). On the other hand, when the sudden disturbance disappears, that is, when the switching signal changes from V _{sw +} to V _sw− , the contact of the first signal switching means SW1 holds the current state and is stored in the first storage means 31b. When the number of samples reaches kN, the terminal b ₁ is switched to the terminal a ₁ .

For this reason, the timing at which the contact of the first signal switching means SW1 is switched to the terminal a ₁ side is a disc rotation break. In addition, since the sudden disturbance estimation device 3 holds data for one rotation of the disk in the first storage unit 31b in advance, when a sudden disturbance has occurred, the disk is rotated one rotation before the sudden disturbance occurs. Is sent again from the first phase adjusting means 31c to the first storage control means 31a. Thus, when a sudden disturbance occurs, as a tracking error signal e ^{_t? Feedback} to the first phase adjusting means 31c outputs (k-N), so that the signal is repeatedly generated without the sudden disturbance component.

Further, as shown in FIG. 9D, the contact of the second signal switching means SW2 is switched to the terminal a ₂ side in the initial state (time = 0) (always connected), and sudden disturbance has occurred. When the switching signal changes from V _sw− to V _{sw +} , the signal is switched to the terminal b ₂ side and the state is latched (held). On the other hand, when the sudden disturbance disappears, that is, when the switching signal changes from V _{sw +} to V _sw− , the contact of the second signal switching means SW2 holds the current state and is stored in the second storage means 32b. When the number of samples reaches kN, the terminal b ₂ is switched to the terminal a ₂ .

Therefore, the timing of contact of the second signal switching means SW2 is switched to the terminal a ₂ side, the separator disk rotation. In addition, since the sudden disturbance estimation device 3 holds data for one rotation of the disk in the second storage unit 32b in advance, when a sudden disturbance occurs, the disk rotation before one rotation when the sudden disturbance occurs is detected. Is sent again from the second phase adjustment means 32c to the second storage control means 32a. As a result, when a sudden disturbance occurs, a signal that does not include a sudden disturbance component is repeatedly generated as the sudden disturbance operation amount I _cmd (k−N) output from the second phase adjusting unit 32c.

Thus, a tracking error signal e _t ^feedback (k-N) outputted from the first phase adjusting means 31c, disturbance tracking error generating means 33a for calculating a difference between the tracking error signal e _t (k) is sudden in the past The tracking error x _d (k) without the influence of disturbance can be output to the disturbance calculating means 33c.
Further, the disturbance operation amount error generation unit 33b that takes the difference between the sudden disturbance operation amount I _cmd (k−N) output from the second phase adjustment unit 32c and the sudden disturbance operation amount I _cmd (k) The manipulated variable error I _b (k) without the influence of sudden disturbance can be output to the disturbance calculation means 33c.

As a result, even when the sudden disturbance continues for a long time, the control operation in the sudden disturbance estimation device 3 is stably performed, and the tracking control device 1 can perform stable tracking control resistant to the disturbance.
With the above operation, the tracking control apparatus 1 can estimate and compensate only for sudden disturbance by separating only sudden disturbance from disturbance (periodic disturbance and sudden disturbance).

(Evaluation of tracking controller)
Here, with reference to FIG. 10, the evaluation result of the tracking control apparatus in 1st Embodiment is demonstrated. FIG. 10 is a graph showing the evaluation results of the tracking control device, where (a) shows the input signal of sudden disturbance, and (b) shows the tracking in the tracking control device 1 (FIG. 1) of the first embodiment. An error waveform (tracking error signal) is shown. For reference, FIG. 1C shows a tracking error waveform (tracking error signal) when the switching operation by the switching signal is not performed in the tracking control apparatus 1 (FIG. 1) of the first embodiment. ). In (a), the horizontal axis indicates time [sec], and the vertical axis indicates the current value [A] that is the sudden disturbance I _d . In both (b) and (c), the horizontal axis represents time [sec], and the vertical axis represents the tracking error signal _et [m].

In the tracking control device 1 of the first embodiment, as shown in FIG. 10A, when a large sudden disturbance exceeding −1.2 [A] at 0.38 [sec] is given. However, as shown in FIG. 10B, the tracking error signal is suppressed to about 1.4 × 10 ⁻⁷ [m] at the maximum, and it can be confirmed that the tracking operation is performed with high accuracy.

For reference, in FIG. 10C, in the tracking control device 1 of the first embodiment (FIG. 1), when the switching operation by the switching signal is not performed, that is, the contact of the first signal switching means SW1 is The tracking response (tracking error signal) when the contact of the terminal a ₁ and the contact point of the second signal switching means SW2 is always held on the terminal a ₂ side is shown.
In FIG. 10C, a tracking error signal of about 2.0 × 10 ⁻⁷ [m] is generated for the same sudden disturbance (a) as in FIG. That is, it can be confirmed that the switching operation by the switching signal is effective in the tracking control device 1.

[Second Embodiment]
Next, the second embodiment will be described. Here, first, a method for estimating only a sudden disturbance performed in the second embodiment will be described, and tracking including a sudden disturbance estimation device that estimates a sudden disturbance based on a component of the sudden disturbance extracted by the method. The control devices will be described sequentially.

[Estimation of sudden disturbance]
Here, in order to improve the determination accuracy of the sudden disturbance in the first embodiment, the disturbance observer is configured in consideration of not only the constant disturbance (step disturbance) but also the ramp-like disturbance.
In general, sudden disturbances are often applied mainly in vibration, and therefore sudden disturbances often cross the value “0” as their current values. For this reason, the presence or absence of the sudden disturbance cannot be accurately determined only by comparing the sudden disturbance with the threshold value. Therefore, here, when the current value of the sudden disturbance crosses “0”, the fact that the amount of change becomes large is used, and the presence / absence of the sudden disturbance is determined by using the differential value of the sudden disturbance. did.

That is, by configuring the disturbance observer in consideration of the ramp-like disturbance, it is possible to simultaneously estimate the sudden disturbance I _d (k) and its differential value I _ddot (k) at a certain sampling time point k. Become. Therefore, here, the sudden disturbance I _d (k) and its differential value I _ddot (k) are estimated, and the input of the disturbance is determined based on their magnitude (absolute value).
First, a disturbance observer taking into account a ramp-like disturbance will be described.
Here, the following equation (13) is assumed as the ramp-shaped disturbance, and the disturbance observer is designed. That is, a disturbance is assumed in which the value of the second derivative of the sudden disturbance I _d (k) is “0”.

  For this reason, the state equation and output equation of the expansion plant 63 described with reference to FIG. 4 increase linearly and become the following equation (14). A, B, and C are coefficient matrices constituting a discrete time state equation of the light spot position correcting means 51 (FIG. 4), and T is a sampling period [sec].

When the minimum dimension observer is configured using the sudden disturbance compensation I _b (k) which is an input in the equation (14) and the tracking error x _d (k) due to the sudden disturbance which is an output, the following equation (15) is obtained. It becomes.

In the equation (15), “n” indicates the number of memories of the tracking error signal for one rotation of the disk in the previous round at the present time. Specifically, n = 60 / (N × T) [N: Disk rotation speed [rpm], T: Sampling cycle [sec]].
In the second embodiment, sudden disturbance is estimated by using the disturbance observer shown in the equation (15).

[Configuration of tracking controller]
Next, the configuration of the tracking control apparatus according to the second embodiment will be described with reference to FIG. FIG. 11 is a block diagram showing the configuration of the tracking control apparatus according to the second embodiment.

  As illustrated in FIG. 11, the tracking control device 1B changes the configuration of the sudden disturbance estimation device 3 of the tracking control device 1 (see FIG. 1) to be a sudden disturbance estimation device 3B. That is, the sudden disturbance estimation device 3B of the tracking control device 1B omits the sudden disturbance detection unit 30 from the sudden disturbance estimation device 3 and newly includes a switching determination unit 40. Moreover, the disturbance calculation means 33B of the sudden disturbance calculation means 33 is replaced with a disturbance calculation means 33Bc whose function is changed, thereby constituting a sudden disturbance calculation means 33B. About another structure, since it is the same structure as the tracking control apparatus 1 (refer FIG. 1), the same code | symbol is attached | subjected and description is abbreviate | omitted.

The disturbance calculation unit 33Bc is based on the tracking error x _d (k) generated by the disturbance tracking error generation unit 33a and the operation amount error I _b (k) generated by the disturbance operation amount error generation unit 33b. _Is estimated with _{respect to the manipulated} variable for correcting the light spot position (sudden disturbance estimated amount I _d2 (k)), and a differential value estimated amount I _d2dot which is a differential value of the sudden disturbance estimated amount I _d2 (k). (K) is estimated. That is, the disturbance calculation means 33Bc calculates (estimates) the sudden disturbance estimated amount I _d2 (k) and the differential value estimated amount I _d2dot (k) by sequentially performing the calculation of the equation (15). The sudden disturbance estimated amount I _d2 (k) estimated here is output to the disturbance manipulated variable generating means 23. The sudden disturbance estimated amount I _d2 (k) and the differential value estimated amount I _d2dot (k) are output to the switching determination means 40.
The disturbance calculation means 33Bc includes differential value calculation means (not shown), and the differential value calculation means calculates the differential value estimation amount I _d2dot (k).

The switching determination unit 40 detects a sudden disturbance based on the sudden disturbance estimated amount I _d2 (k) and the differential value estimated amount I _d2dot (k) calculated (estimated) by the disturbance calculating unit 33Bc, and the sudden disturbance is detected. A switching signal for controlling the operation of the first signal switching means SW1 and the second signal switching means SW2 is generated according to the presence or absence.

Here, the configuration of the switching determination means 40 will be described with reference to FIG. FIG. 12 is a block diagram showing the configuration of the switching determination means. Here, the switching determination means 40 includes an absolute quantity generation means 41 (41 ₁ , 41 ₂ ), a reference signal generation means 42 (42 ₁ , 42 ₂ ), and a comparison means 43 (43 ₁ , 43 ₂ ). And a signal generation means 44.

The absolute amount generation means 41 outputs an amount (absolute value) indicating the magnitude of the input signal. Here, the absolute amount generation means 41 ₁ receives the sudden disturbance estimated amount I _d2 (k) estimated by the disturbance calculation means 33Bc, and outputs the magnitude as an absolute value | I _d2 (k) |. The absolute amount generation unit 41 ₂ receives the disturbance calculating unit 33Bc at the estimated differential value estimator _I d2dot (k), the size of the absolute value | outputs as | _I d2dot (k).

The reference signal generator 42 generates a reference signal having a predetermined magnitude (threshold value). Here, the reference signal generating means 42 _1, the reference signal for the sudden disturbance estimator _{I d2 (k) | TH id} | shall generate a reference signal generating means 42 _2, the differential value estimator _I d2dot (k) It is _{assumed that} a reference signal | TH _iddot |

The comparison unit 43 compares the absolute value generated by the absolute amount generation unit 41 with the reference signal (threshold value) generated by the reference signal generation unit 42, and outputs a determination signal for determining the presence or absence of sudden disturbance. To do. Here, the comparison means (disturbance estimation amount comparison means) 43 ₁ generates the absolute value | I _d2 (k) | of the sudden disturbance estimation amount generated by the absolute amount generation means 41 ₁ and the reference signal generation means 42 ₁ . Is compared with the reference signal | TH _id |, and when the absolute value | I _d2 (k) | of the sudden disturbance estimation amount is equal to or larger than the reference signal | TH _id |, the determination signal (SW−I _d2 ) is turned on ( ON), otherwise, the determination signal (SW- _Id2 ) is turned off. The comparison unit (differential value estimation amount comparison unit) 43 ₂ generates the absolute value | I _d2dot (k) | of the differential value estimation amount generated by the absolute amount generation unit 41 ₂ and the reference signal generation unit 42 ₂ . _Is compared with the reference signal | TH _iddot |, and when the absolute value | I _d2dot (k) | of the differential value estimation amount is equal to or greater than the reference signal | TH _iddot |, the determination signal (SW−I _d2dot ) is turned on. In other cases, the determination signal (SW-I _d2dot ) is turned off.

The switching signal generation means 44 determines whether or not sudden disturbance has occurred based on the determination signal output from the comparison means 43 (43 ₁ , 43 ₂ ), and the first signal switching means SW1 and the second signal switching means SW2 The switching signal to be output to is generated. Here, the switching signal generating means 44, the determination signal output from the comparison means 43 ₁ (SW-I _d2), is one of the determination signal outputted from the comparator _{43 2} (SW-I d2dot) When ON, a sudden disturbance determination signal (SW-d) indicating that a sudden disturbance has occurred is generated. The sudden disturbance determination signal (SW-d) is output to the first signal switching unit SW1 and the second signal switching unit SW2 as the switching signal V _sw .

Here, with reference to FIGS. 13 to 15 (refer to FIG. 12 as appropriate), a determination example in the switching determination means 40 will be described. FIG. 13 is a graph showing an example of determination of the occurrence of disturbance by the sudden disturbance estimation amount, where (a) is a disturbance determination signal (SW-I _d2 ), (b) is a sudden disturbance estimation amount, and (c) is The absolute value of the sudden disturbance estimator is shown. FIG. 14 is a graph showing an example of determination of the occurrence of disturbance by the differential value estimation amount, where (a) is a determination signal (SW−I _d2dot ), (b) is a differential value estimation amount, and (c) is It shows the absolute value of the differential value estimator. FIG. 15 is a graph showing an example of generating a sudden disturbance determination signal indicating whether or not a sudden disturbance has occurred based on the determination signal determined by the sudden disturbance estimation amount and the differential value estimation amount. a) the disturbance judgment signal due to sudden disturbance estimator _{(SW-I d2), (} b) the disturbance of the determination signal by the differential value estimator _{(SW-I d2dot), (} c) the sudden disturbance determination signal (SW- d). In FIG. 13 to FIG. 15, the horizontal axis indicates time [sec], the positive logic value (ON) in each determination signal is “−1”, and the negative logic value (OFF) is “0”. Moreover, the vertical axis | shaft of FIG.13 (b) shows the relative value (-50-50) of sudden disturbance estimated amount, and the vertical axis | shaft of FIG.13 (c), FIG.14 (b) and FIG.14 (c) is Relative values based on the sudden disturbance estimator are shown.

That is, when the sudden disturbance estimated amount I _d2 (k) as shown in FIG. 13B is input to the switching determination means 40, the absolute quantity generation means 41 ₁ causes the sudden disturbance as shown in FIG. A signal indicating the absolute value | I _d2 (k) | of the disturbance estimation amount I _d2 (k) is generated. In FIG. 13C, a signal whose absolute value | I _d2 (k) | is equal to or higher than the level of the reference signal is determined as a sudden disturbance.
Then, as shown in FIG. 13A, the comparison means 43 ₁ turns on (“−1”) when the absolute value | I _d2 (k) | A determination signal (SW-I _d2 ) that is turned off (“0”) below the level is generated.

Further, and FIG. 14 (b) in shown derivative value estimator _I d2dot (k) is inputted to the switching determination unit 40, the absolute amount generation unit 41 _2, as shown in FIG. 14 (c) differential A signal indicating the absolute value | I _d2dot (k) | of the value estimation amount I _d2dot (k) is generated. In FIG. 14C, a signal whose absolute value | I _d2dot (k) | is equal to or higher than the level of the reference signal is determined as a sudden disturbance.
As shown in FIG. 14 (a), the comparing unit 43 _2, the absolute value of a differential value estimate _| I d2dot (k) | is turned on or the level of the reference signal ( "-1"), the reference signal A determination signal (SW-I _d2dot ) that is turned off (“0”) below the level is generated.

The switching signal generation unit 44 of the switching determination unit 40, as shown in FIG. 15 (a), the determination signal output from the comparison means 43 ₁ (SW-I _d2), as shown in FIG. 15 (b) The sudden disturbance judgment signal (SW-d) as shown in FIG. 15C is generated by _{performing a} logical OR operation on the judgment signal (SW-I _d2dot ) output from the comparison means 43 ₂ . Output as a switching signal (V _sw ).
As described above, by configuring the tracking control device 1 (sudden disturbance estimation device 3), it becomes possible to detect the occurrence of a ramp-like disturbance and to perform tracking control with high accuracy and stability. It becomes possible.

[Operation of tracking controller]
Next, the operation of the tracking control device according to the second embodiment will be described. Since the basic tracking control operation is the same as the operation described with reference to FIG. 6, the description thereof will be omitted, and only the switching determination operation in the switching determination means 40 will be described.

(Switching judgment operation)
Here, the switching determination operation will be described with reference to FIG. 16 (refer to FIGS. 11 and 12 as appropriate). FIG. 16 is a flowchart showing the switching determination operation in the switching determination means.

First, the switching determination unit 40 acquires the sudden disturbance estimation amount I _d2 (k) and the differential value estimation amount I _d2dot (k) from the sudden disturbance calculation unit 33B (step S61).
Then, the switching determination unit 40, the absolute amount generation unit 41 _1, the absolute value of the sudden disturbance estimator _{I d2 (k) | I d2} (k) | generate, by an absolute amount generation unit 41 _2, the differential value estimated An absolute value | I _d2dot (k) | of the quantity I _d2dot (k) is generated (step S62).

Then, the switching determination unit 40 uses the absolute value | I _d2 (k) | generated by the comparison unit 43 ₁ in step S62 and the reference signal | TH output from the reference signal generation unit 42 _{1. id} | is compared (step S63).
Here, the absolute value | I _d2 (k) | is the reference signal | TH _id | is less than (Yes in step S63), comparison means 43 ₁ determines that sudden disturbance has not occurred, the determination signal SW -I _d2 is turned off (step S64). On the other hand, the absolute value | I _d2 (k) | is the reference signal | TH _id | is greater than or equal (No at step S63), comparison means 43 ₁ determines that sudden disturbance has occurred, the determination signal SW- I _d2 is turned on (ON) (step S65).

The switching decision unit 40, the comparing unit 43 _2, the absolute value of the generated differential value estimate in step S62 | and the reference signal outputted from the reference signal generating means _{42 2 | | I d2dot (k} ) TH _iddot | is compared (step S66).
Here, the absolute value _| I d2dot (k) | is the reference signal _| TH iddot | is less than (Yes in step S66), comparison means 43 ₂ determines that sudden disturbance has not occurred, the determination signal ( SW- _Id2dot ) is turned off (step S67). On the other hand, the absolute value _| I d2dot (k) | is the reference signal _| TH iddot | is greater than or equal (No at step S66), comparison means 43 ₂ determines that sudden disturbance has occurred, the determination signal (SW -I _d2dot ) is turned on (step S68).

Then, the switching determination means 40 performs a logical OR operation between the determination signal (SW−I _d2 ) and the determination signal (SW−I _d2dot ) by the switching signal generation means 44 to generate the sudden disturbance determination signal (SW−d). Generate (step S69). Note that the switching signal generation unit 44 maintains the state of the sudden disturbance determination signal (SW-d) for one cycle of disk rotation (step S70).
Then, the switching determination means 40 returns to step S61 and continues the switching determination operation while the disk is rotating (while the track position is input).
With the above operation, the tracking control device 1B can detect the occurrence of ramp disturbance, and can control tracking with high accuracy and stability.

The tracking control device according to the present invention can be used for tracking control in a device including an optical disc device, for example, a camera-integrated recorder equipped with an optical disc, an in-vehicle optical disc device, or a portable optical disc device.
The tracking control apparatus according to the present invention is not only used for tracking control of an optical disk recording apparatus, but can be widely used for tracking control in disk apparatuses such as a magneto-optical disk apparatus and a magnetic disk apparatus.

It is the block diagram which showed the structure of the tracking control apparatus which concerns on 1st Embodiment. It is the schematic diagram which showed typically the control system of the general tracking control apparatus. It is explanatory drawing for demonstrating the feedback control system of a sudden disturbance, and the feedback control system of a periodic disturbance, (a) shows the feedback control system of a sudden disturbance, (b) shows the feedback control system of a periodic disturbance, Yes. It is a conceptual diagram which shows the concept which implement | achieves the expansion plant which excluded the periodic disturbance. It is a block diagram which shows the structure of a sudden disturbance detection means. It is a flowchart which shows the feedback control operation | movement of the tracking control apparatus which concerns on 1st Embodiment. It is a flowchart which shows the signal switching operation | movement in the sudden disturbance detection means of the sudden disturbance estimation apparatus. It is a flowchart which shows the disturbance estimation operation | movement in the sudden disturbance calculating means of a sudden disturbance estimation apparatus. It is a timing chart which shows the switching timing of a switching signal and a 1st and 2nd signal switching means. It is a graph which shows the evaluation result of a tracking control apparatus. It is the block diagram which showed the structure of the tracking control apparatus which concerns on 2nd Embodiment. It is a block diagram which shows the structure of a switching determination means. It is a graph which shows the example of determination of the disturbance generation by sudden disturbance estimated amount. It is a graph which shows the example of determination of disturbance generation by a differential value estimation amount. It is a graph which shows the example which produces | generates the sudden disturbance determination signal which shows the presence or absence of generation | occurrence | production of the sudden disturbance based on the determination signal determined by the differential value estimation amount and the differential value estimation amount. It is a flowchart which shows the operation | movement of the switching determination in a switching determination means.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 1B Tracking control apparatus 2 Feedback control system 20 Tracking error signal generation means 21 A / D conversion means 22 Feedback control means 23 Disturbance operation amount generation means 24 D / A conversion means 25 Light spot position correction means 3 Sudden disturbance estimation apparatus 30 Sudden disturbance detection means 30a Acceleration detection means 30b Signal conversion means 30c Voltage level determination means 30d Switching signal generation means 31 Tracking error delay control means 31a First storage control means 31b First storage means 31c First phase adjustment means 32 Operation amount delay control 32 Means 32a Second storage control means 32b Second storage means 32c Second phase adjustment means 33, 33B Sudden disturbance calculation means 33a Disturbance tracking error generation means 33b Disturbance manipulated variable error generation means 33c, 33Bc Disturbance calculation means (differential value calculation means)
40 switching determination means 41 absolute amount generation means 42 reference signal generation means 43 comparison means (disturbance estimation amount comparison means, differential value estimation amount comparison means)
44 switching signal generating means SW1 first signal switching means SW2 second signal switching means

Claims (7)

Compensation of the amplitude and phase of the tracking error signal indicating an error between the track position on the disk and the light spot position of the light beam emitted from the optical head, and an operation amount for correcting the light spot position is generated. In the tracking control device provided with the feedback control means, a sudden disturbance estimation device for estimating a sudden disturbance amount input from the outside,
Tracking error delay control means for sequentially storing and delaying the tracking error signal; and
Disturbance tracking error generation means for generating a tracking error that is the amount of change in the track position based on the difference between the tracking error signal delayed by the tracking error delay control means and the tracking error signal at the present time;
The operation amount delay control means for sequentially storing the operation amount and delaying the operation amount;
Disturbance manipulated variable error generating means for generating an manipulated variable error that is the amount of change in the manipulated variable based on the difference between the manipulated variable delayed by the manipulated variable delay control means and the manipulated variable at the present time;
The sudden disturbance that compensates for the sudden disturbance with respect to the current operation amount based on the tracking error generated by the disturbance tracking error generation unit and the operation amount error generated by the disturbance operation amount error generation unit Disturbance calculation means for calculating the amount as an unexpected disturbance estimation amount;
A sudden disturbance estimation device characterized by comprising:   Based on the detection result, the sudden disturbance is detected, and a switching signal indicating whether to stop storing the tracking error signal and the operation amount at the present time is used as the switching error delay control means and the operation amount delay control. The sudden disturbance estimation device according to claim 1, further comprising sudden disturbance detection means for outputting to the means. The sudden disturbance detection means includes
Acceleration detecting means for detecting the acceleration of the sudden disturbance as an acceleration signal;
Signal conversion means for converting the acceleration signal detected by the acceleration detection means into a voltage signal;
A voltage level determination unit that compares the voltage signal converted by the signal conversion unit with a predetermined threshold value to determine whether or not sudden disturbance has occurred,
Based on the determination result of the voltage level determination means, switching signal generating means for generating the switching signal,
The sudden disturbance estimation device according to claim 2, comprising: The disturbance calculating means includes a differential value calculating means for calculating a change amount per unit time of the sudden disturbance estimated quantity as a differential value estimated quantity,
Whether to stop storing the tracking error signal and the manipulated variable at the present time based on the sudden disturbance estimated amount calculated by the disturbance calculating unit and the differential value estimated amount calculated by the differential value calculating unit 2. The sudden disturbance estimation device according to claim 1, further comprising a switching determination unit that outputs a switching signal indicating whether or not to the tracking error delay control unit and the operation amount delay control unit. The switching determination means is
Disturbance estimated amount comparison means for comparing the magnitude of the sudden disturbance estimated amount with a predetermined threshold;
Differential value estimation amount comparison means for comparing the magnitude of the differential value estimation amount with a predetermined threshold;
Based on the comparison results of the disturbance estimation amount comparison means and the differential value estimation amount comparison means, when either one of the sudden disturbance estimation amount or the differential value estimation amount is larger than the threshold value, the sudden disturbance is Switching signal generating means for determining that it has occurred and generating the switching signal;
The sudden disturbance estimation device according to claim 4, comprising: Compensation of the amplitude and phase of a tracking error signal indicating an error between the track position on the disk and the light spot position of the light beam emitted from the optical head, and an operation amount for correcting the light spot position is generated. In the tracking control device provided with the feedback control means,
The sudden disturbance estimation device according to any one of claims 1 to 5, wherein the sudden disturbance amount input from the outside is estimated;
Disturbance operation for generating a sudden disturbance manipulated variable that is an manipulated variable that compensates for the sudden disturbance by adding the sudden disturbed amount estimated by the sudden disturbance estimating device and the manipulated variable generated by the feedback control means A quantity generating means;
A tracking control device comprising: Compensation of the amplitude and phase of the tracking error signal indicating an error between the track position on the disk and the light spot position of the light beam emitted from the optical head, and an operation amount for correcting the light spot position is generated. In the tracking control device provided with the feedback control means, a sudden disturbance estimation method for estimating a sudden disturbance amount for correcting the operation amount accompanying the occurrence of the sudden disturbance,
A disturbance tracking error generation step for generating a tracking error that is a change amount of the track position based on a difference between a tracking error signal at the present time and a delayed past tracking error signal;
A disturbance operation amount error generating step for generating an operation amount error that is a change amount of the operation amount based on a difference between the operation amount at the present time and the delayed past operation amount;
The sudden disturbance amount that compensates for the sudden disturbance with respect to the current operation amount based on the tracking error generated in the disturbance tracking error generation step and the operation amount error generated in the disturbance operation amount error generation step A disturbance calculation step for calculating as a sudden disturbance estimation amount,
The sudden disturbance estimation method in the tracking control apparatus characterized by including this.

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