JP4341917B2 - Tracking control device, tracking control method, sudden disturbance estimation device, and sudden disturbance estimation method - Google Patents

Description

  The present invention relates to a tracking control technique, and more specifically, a sudden disturbance estimation device and a sudden disturbance estimation method for estimating a sudden disturbance, and a tracking control device and a tracking control method for controlling tracking by estimating a sudden disturbance. About.

  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. Furthermore, a technology that makes the light spot position follow the track position at high speed and in a stable state by adding feedforward control for predicting an error after one rotation period of the disk by a specific transfer function to this feedback control. (For example, refer to Patent Document 1 or Patent Document 2).

Here, a conventional tracking control apparatus will be described with reference to FIG. FIG. 14 is a block diagram showing a configuration of a conventional tracking control apparatus using digital control.
The tracking control apparatus 1C includes, as a feedback control system 2C, a tracking error signal generation unit 20, an A / D conversion unit 21, a feedback control unit 22, a correction operation amount generation unit (addition unit) 23, and a D / A conversion. Means 24 and light spot position correcting means 25, and as feedforward control system 3, corrected tracking error signal generating means (adding means) 30, storage control means 31, storage means 32, and feedforward control means 33 And a tracking error correction signal generating means 34.

Here, the feedback control means (C (z ⁻¹ )) 22 is a robust controller, the light spot position correction means (P (s)) 25 is a current-driven voice coil motor of the actuator, and feed forward. The control means (G _ff (z ⁻¹ )) 33 is a precompensator to which zero phase error tracking (ZPET) control is applied.
Note that the subtraction means D in FIG. 14 is a pseudo representation of the effect of sudden disturbance on the feedback control system 2C, and is not an actual configuration.

The tracking control device 1C generates a tracking error signal indicating an error between the track position on the disk and the light spot position corrected by the light spot position correcting means 25 by the tracking error signal generating means 20 in the feedback control system 2C. Then, it is converted into a digital signal by the A / D conversion means 21. Further, the tracking control device 1C compensates the amplitude and phase of the tracking error signal _et (k) converted into a digital signal by the feedback control unit 22, and manipulates the light spot position I _c (k). Is generated. Then, the tracking control device 1 </ _b > C uses the correction operation amount generation unit 23 to _calculate the operation amount I _c (k) and the operation amount error I _f (k) estimated by the feedforward control unit 33 of the feedforward control system 3. Is added to generate a corrected operation amount (correction operation amount I _cmd (k)) for operating the light spot position.

Then, the tracking control apparatus 1 </ b> C converts the correction operation amount I _cmd (k) into an analog signal by the D / A conversion unit 24. Incidentally, if the sudden disturbance from the outside (sudden disturbance I _d (t)) is generated, from the correction manipulated variable which is converted to an analog signal output from D / A converter 24, a sudden disturbance I _d (t ) Will be subtracted. Then, the tracking control device 1 </ b> C controls the light spot position by the light spot position correcting unit 25 with the correction operation amount. This light spot position is input to the tracking error signal generation means 20 to form a feedback control system 2C.

Further, the tracking control device 1C is generated by the tracking error signal e _t (k) generated by the feedback control system 2C and the tracking error correction signal generation means 34 by the correction tracking error signal generation means 30 in the feedforward control system 3. It has been to generate a corrected tracking error signal e ^{_t? feedback} obtained by adding the tracking error correction signal before at least one rotation period of the disk (k). Then, the storage control unit 31 stores the corrected tracking error signal e ^{_t? Feedback} (k) of the storage unit 32.

Furthermore, the tracking control apparatus 1C compensates the amplitude and phase of the corrected tracking error signal stored in the storage unit 32 by the feedforward control unit 33, and estimates the error in the operation amount of the light spot position. The estimated operation amount error is output to the tracking error correction signal generation unit 34 and the correction operation amount generation unit 23. In the tracking control apparatus 1C, the tracking error correction signal generating unit 34 generates a tracking error correction signal for correcting the tracking error signal _et (k). The tracking error correction signal is input to the correction tracking error signal generation unit 30, thereby forming the feedforward control system 3.

Thus, the conventional tracking control device 1C compensates for periodic disturbances due to disk eccentricity, etc., by the feedback control system 2C and the feedforward control system 3, and feeds back sudden disturbances that are suddenly applied from the outside. Compensation is performed only by the control system 2C . Conventionally, in a tracking control apparatus that performs tracking control only 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, And Patent Document 3). In this technique, periodic disturbances that are input to the feedback control system and sudden disturbances are not distinguished from each other, but are estimated as collective disturbances and compensated.
JP 2003-091841 A (paragraphs 0039-0062, FIG. 1) JP 2004-095123 A (paragraphs 0043-0072, FIG. 1) JP 2001-210032 A (paragraphs 0065 to 0073, FIGS. 11 and 12)

  However, the tracking control device comprising the conventional feedback control system and the feedforward control system compensates for periodic disturbances due to disk eccentricity, etc. by the feedback control system and the feedforward control system, and suddenly adds them from the outside. It is configured to compensate for the sudden disturbance generated by only the feedback control system. For this reason, if the sudden disturbance is compensated only by the feedback control system, the sudden disturbance cannot be predicted, and the follow-up performance to the track position of the disk decreases as the disk rotates faster.

  A tracking control device that performs tracking control only by the feedback control system estimates and compensates for disturbances (periodic disturbances and sudden disturbances) collectively 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, and estimates only the sudden disturbance and compensates for the sudden disturbance estimation device and the sudden disturbance estimation method, and estimates only the sudden disturbance and compensates for it. It is an object of the present invention to provide a tracking control device and a tracking control method that do not impair the follow-up performance to the track position of the disk.

  The present invention was devised to achieve the above object. First, the tracking control device according to claim 1 includes a track position on a disk and a light spot position of a light beam emitted from an optical head. A feedback control system that corrects the light spot position based on a tracking error signal that indicates an error with the feedback, and a feed that estimates an error correction amount that indicates a correction error in the feedback control system based on the tracking error signal. In the tracking control device that controls the light spot position by a forward control system, the feedforward control system includes a correction tracking error signal generation unit, a storage unit, a feedforward control unit, and a tracking error correction signal generation unit. The feedback control system includes a feedback And control means, has a structure and a sudden disturbance estimating means.

  According to this configuration, the tracking control device adds the tracking error signal and the tracking error correction signal at least one rotation period before the disk by the correction tracking error signal generation means in the feedforward control system, thereby correcting the tracking error. A signal is generated and stored in the storage means. Then, the tracking control device compensates the amplitude and phase of the corrected tracking error signal by the feedforward control means, and generates an error correction amount that estimates the correction error. The amplitude and phase of the corrected tracking error signal can be compensated for by executing a predetermined transfer function in the feedforward control means. Then, the tracking control device generates a tracking error correction signal to be used by the correction tracking error signal generation unit by the tracking error correction signal generation unit by a predetermined transfer function. As a result, a feedforward control system is formed.

  Further, the tracking control device generates an operation amount for correcting the light spot position by compensating the amplitude and phase of the tracking error signal by the feedback control means in the feedback control system. The tracking error signal amplitude and phase can be compensated by executing a predetermined transfer function in the feedback control system. Then, the tracking control device estimates the sudden disturbance amount input from the outside with respect to the manipulated variable based on the tracking error signal and the corrected tracking error signal by the sudden disturbance estimating means, and the sudden disturbance operation in which the manipulated variable is corrected. Generate quantity. This sudden disturbance estimation means takes the difference between the tracking error signal and the corrected tracking error signal, thereby excluding periodic disturbance from the disturbance and estimating only the sudden disturbance.

  According to a second aspect of the present invention, in the tracking control device according to the first aspect, the sudden disturbance estimation unit includes a phase adjustment unit, a disturbance tracking error generation unit, a disturbance estimation unit, and a disturbance operation. And a quantity generation means.

  According to such a configuration, the tracking control apparatus adjusts the phases of the corrected tracking error signal and the tracking error signal by delaying the corrected tracking error signal by the phase adjusting unit. As a result, both signals can be in phase. Then, the tracking control device takes the difference between the tracking error signal and the tracking error signal by obtaining the difference between the corrected tracking error signal and the tracking error signal, which are adjusted to the same phase by the phase adjusting means by the disturbance tracking error generating means. Error). The change amount of the track position is a change amount excluding the periodic disturbance, that is, a change amount due to the sudden disturbance because the correction tracking error signal having the same phase is subtracted from the tracking error signal.

Therefore, the tracking control device, the disturbance estimating means, and the variation of the track position, on the basis of said sudden disturbance operation amount of the front at least one sampling disk, generating a sudden external disturbance value estimated only sudden disturbance (estimation) It becomes possible to do. The sudden disturbance operation amount is generated by adding the sudden disturbance amount and the operation amount generated by the feedback control unit by the disturbance operation amount generation unit.

  According to a third aspect of the present invention, there is provided a tracking control device according to the second aspect, further comprising a signal switching unit and a sudden disturbance detection unit.

  According to such a configuration, the tracking control device can be any one of the correction tracking error signal generated by the correction tracking error signal generation unit and the correction tracking error signal whose phase is adjusted by the phase adjustment unit by the signal switching unit. Either one is selected and output to the storage means. As a result, the tracking control device performs an operation in a normal state without sudden disturbance when the corrected tracking error signal generated by the corrected tracking error signal generating unit is selected and output to the storage unit. When the corrected tracking error signal whose phase has been adjusted by the phase adjusting means is selected and output to the storage means, the corrected tracking error signal whose phase has been adjusted by the phase adjusting means is the corrected tracking error signal stored in the storing means. Based on the signal, the influence of the sudden disturbance from the outside can be eliminated by inputting to the storage means.

  Further, the tracking control device detects the sudden disturbance by the sudden disturbance detecting means, and selects the corrected tracking error signal whose phase is adjusted by the phase adjusting means when the sudden disturbance is detected. Switch the switching means. Accordingly, when a sudden disturbance is detected, a correction tracking error signal that is not affected by the sudden disturbance is supplied to the signal output to the storage unit. Based on the correction tracking error signal stored in the storage unit, The corrected tracking error signal whose phase is adjusted by the phase adjusting means is output to the disturbance estimating means. As a result, the tracking control device can perform stable tracking control even when sudden disturbance occurs.

  The tracking control device according to claim 4 is the tracking control device according to claim 3, wherein the sudden disturbance detection means includes acceleration detection means, signal conversion means, voltage level determination means, and switching signal generation. Means.

  According to such a configuration, the tracking control device detects the acceleration of the sudden disturbance by the acceleration detection unit, and converts the acceleration signal detected by the acceleration detection unit into a voltage signal by the signal conversion unit. Then, the tracking control device compares the voltage signal converted by the signal conversion means with a predetermined threshold value by the voltage level determination means, and whether the voltage signal has changed across the threshold value. Determine if. It is possible to determine whether or not a sudden disturbance has occurred by appropriately setting the predetermined threshold value. 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.

  Further, the tracking control device is configured to select a first switching for selecting the corrected tracking error signal whose phase is adjusted by the phase adjusting means when the voltage signal is larger than the threshold value by the switching signal generating means. Generating a second switching signal for selecting the correction tracking error signal generated by the correction tracking error signal generating means when the voltage signal is smaller than the threshold value, A first or second switching signal is supplied to the signal switching means. Thus, when the voltage signal is larger than the threshold value, that is, when a sudden disturbance occurs, the first switching signal is supplied to the signal switching means, and the signal switching means adjusts the phase by the phase adjusting means. The corrected tracking error signal is output to the storage means. On the other hand, when the voltage signal is smaller than the threshold value, that is, when the sudden disturbance disappears, the second switching signal is supplied to the signal switching means, and the signal switching means is generated by the correction tracking error signal generating means. The corrected tracking error signal is output to the storage means.

Further, the tracking control device according to claim 5 corrects the light spot position based on 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. The tracking control device that controls the light spot position by performing feedback control means, sudden disturbance estimation means, and storage means , the sudden disturbance estimation means, the phase adjustment means, and disturbance tracking error generation Means, a disturbance estimation means, and a disturbance operation amount generation means, and the tracking control device further comprises a signal switching means and a sudden disturbance detection means.

According to this configuration, the tracking control device compensates the amplitude and phase of the tracking error signal by the feedback control unit, generates an operation amount for correcting the light spot position, and the sudden disturbance estimation unit performs the tracking control. Based on the error signal, a sudden disturbance amount input from the outside with respect to the manipulated variable is estimated, and a sudden disturbance manipulated variable in which the manipulated variable is corrected is generated. Then, the tracking control device stores this tracking error signal in the storage means as a correction tracking error signal. The tracking control apparatus adjusts the phases of the correction tracking error signal and the tracking error signal by delaying the correction tracking error signal stored in the storage unit by the phase adjustment unit. As a result, both signals can be in phase. Then, the tracking control device takes the difference between the tracking error signal and the tracking error signal for correction, the phase of which is adjusted by the phase adjustment unit by the disturbance tracking error generation unit, and the amount of change in the track position. (Tracking error) is generated. Since the tracking error signal having the same phase is subtracted from the correction tracking error signal, the change amount of the track position becomes a change amount excluding the periodic disturbance, that is, a change amount due to the sudden disturbance.

Therefore, the tracking control device, the disturbance estimating means, and the variation of the track position, on the basis of said sudden disturbance operation amount of the front at least one sampling disk, generating a sudden external disturbance value estimated only sudden disturbance (estimation) It becomes possible to do. The sudden disturbance operation amount is generated by adding the sudden disturbance amount and the operation amount generated by the feedback control unit by the disturbance operation amount generation unit.

  Then, the tracking control device selects either the correction tracking error signal generated by the correction tracking error signal generation unit or the correction tracking error signal whose phase is adjusted by the phase adjustment unit by the signal switching unit. And output to the storage means. Thus, when there is no sudden disturbance, the tracking control device selects the correction tracking error signal generated by the correction tracking error signal generation means and outputs it to the storage means, and performs the operation in the normal state. Further, the tracking control device detects the sudden disturbance by the sudden disturbance detecting means, and selects the corrected tracking error signal whose phase is adjusted by the phase adjusting means when the sudden disturbance is detected. Switch the switching means. As a result, the tracking control device can perform stable tracking control even when sudden disturbance occurs.

Furthermore, the sudden disturbance estimation device according to claim 6, the track position on the disc, based on the tracking error signal indicating an error between the light spot position of the light beam emitted from the optical head, the light spot position and feedback control system for generating a manipulated variable for compensation, based on the tracking error signal by the feedforward control system that estimates the error correction amount indicating an error correction in the feedback control system, the light spot position A tracking control device that controls the operation amount based on the tracking error signal and a corrected tracking error signal obtained by correcting the tracking error signal based on the error correction amount in the feedforward control system. Estimated sudden disturbance amount and correct the manipulated variable A sudden disturbance estimation device for generating a sudden disturbance operation amount, and the phase adjusting means, and disturbance tracking error generating means, and disturbance estimating means, a configuration and a disturbance manipulated variable generating means.

According to such a configuration, a sudden disturbance estimation apparatus, the phase adjusting means, by delaying the correction tracking error signal, adjusts a correction tracking error signal, the phase of the tracking error signal. As a result, both signals can be in phase. Then, the sudden disturbance estimation device obtains the amount of change in the track position by calculating the difference between the corrected tracking error signal and the tracking error signal which are adjusted to the same phase by the phase adjustment unit by the disturbance tracking error generation unit. Generate. The change amount of the track position is a change amount excluding the periodic disturbance, that is, a change amount due to the sudden disturbance because the correction tracking error signal having the same phase is subtracted from the tracking error signal.

Therefore, sudden disturbance estimation device, the disturbance estimating means, and the variation of the track position, on the basis of said sudden disturbance operation amount of the front at least one sampling disk, generating (estimating sudden external disturbance value estimated only sudden disturbance ). The sudden disturbance operation amount is generated by adding the sudden disturbance amount and the operation amount generated by the feedback control unit by the disturbance operation amount generation unit.

  According to another aspect of the tracking control method of the present invention, the light spot position is corrected based on 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. In the tracking control method for controlling the light spot position by a feedback control system that performs the above and a feedforward control system that estimates an error correction amount indicating a correction error in the feedback control system based on the tracking error signal, The feedforward control system includes a correction tracking error signal generation step, a storage step, a feedforward control step, and a tracking error correction signal generation step, and the feedback control system includes a feedback control step and a sudden disturbance estimation step. And Characterized in that are Nde.

  According to this procedure, the tracking control method adds a tracking error signal and a tracking error correction signal at least one rotation period before the disk in the feedforward control system in the corrected tracking error signal generation step, thereby correcting the tracking error. A signal is generated, and the corrected tracking error signal is stored in the storage means in the storing step. In the tracking control method, the amplitude and phase of the corrected tracking error signal are compensated in a feedforward control step, and an error correction amount that estimates the correction error is generated. In the tracking control method, the tracking error correction signal used in the correction tracking error signal generation step is generated by a predetermined transfer function in the tracking error correction signal generation step. As a result, a feedforward control system is formed.

  In the tracking control method, in the feedback control system, the amplitude and phase of the tracking error signal are compensated in the feedback control step, and an operation amount for correcting the light spot position is generated. The tracking control method includes a sudden disturbance operation in which the sudden disturbance amount input from the outside with respect to the manipulated variable is estimated and the manipulated variable is corrected based on the tracking error signal and the corrected tracking error signal in the sudden disturbance estimation step. Generate quantity. In this sudden disturbance estimation step, the periodic disturbance is excluded from the disturbance by taking the difference between the tracking error signal and the corrected tracking error signal, and only the sudden disturbance is estimated.

Further, the sudden disturbance estimation method according to claim 8 is configured to determine the light spot position based on 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. and feedback control system for generating a manipulated variable for compensation, based on the tracking error signal by the feedforward control system that estimates the error correction amount indicating an error correction in the feedback control system, the light spot position A tracking control device that controls the operation amount based on the tracking error signal and a corrected tracking error signal obtained by correcting the tracking error signal based on the error correction amount in the feedforward control system. Estimated sudden disturbance amount and correct the manipulated variable A sudden disturbance estimation method for generating a sudden disturbance operation amount, to the phase adjusting step, the disturbance tracking error generating step, a disturbance estimation step, characterized in that it comprises a disturbance manipulated variable generating step.

According to this procedure, sudden disturbance estimation method, the phase adjustment step, the correction tracking error signal by delaying the to adjust the correction tracking error signal, the phase of the tracking error signal. As a result, both signals can be in phase. Then, in the sudden disturbance estimation method, in the disturbance tracking error generation step, the phase is adjusted in the phase adjustment step, and the difference between the tracking error signal and the corrected tracking error signal that has become the same phase is obtained. Generate. The change amount of the track position is a change amount excluding the periodic disturbance, that is, a change amount due to the sudden disturbance because the correction tracking error signal having the same phase is subtracted from the tracking error signal.

Therefore, sudden disturbance estimation method, by the disturbance estimation step, the amount of change in track position, on the basis of said sudden disturbance operation amount of the front at least one sampling disk, generating (estimating sudden external disturbance value estimated only sudden disturbance ). Furthermore, in the sudden disturbance estimation method, the sudden disturbance operation amount is generated by adding the sudden disturbance amount and the operation amount generated in the feedback control step in the disturbance operation amount generation step. The sudden disturbance operation amount is used in the disturbance estimation step.

  According to the first or seventh aspect of the invention, the disturbance is separated into the sudden disturbance and the periodic disturbance by adding a function as a disturbance observer for estimating and compensating only the sudden disturbance to the feedback control means. Can be compensated simultaneously. As a result, it is possible to prevent unnecessary information and illegal information from being recorded on a track adjacent to the track being recorded. In addition, according to the present invention, since robustness (robustness) against sudden disturbance is improved, even in a portable optical disk recording apparatus or the like in which sudden disturbance (force disturbance) is likely to occur due to camera shake or external impact. , Stable recording and reproduction of the disc becomes possible.

  According to the second aspect of the present invention, the phase adjustment means subtracts the corrected tracking error signal having the same phase from the tracking error signal, thereby changing the track position only by the sudden disturbance excluding the periodic disturbance. The amount can be determined. As a result, it is possible to estimate the disturbance only by the sudden disturbance, and in the feedback control means, the disturbance can be separated into the sudden disturbance and the periodic disturbance and compensated at the same time, thereby improving the track position tracking performance. be able to.

  According to the third aspect of the present invention, normally, the signal generated by the corrected tracking error signal generating unit is output to the storage unit, and when the sudden disturbance is detected, the signal whose phase is adjusted by the phase adjusting unit is output. It can be output to the storage means. As a result, when a sudden disturbance occurs, the circuit including the storage means is closed, and the influence of the sudden disturbance from the outside can be removed from the corrected tracking error signal stored in the storage means, so that stable tracking is possible. Control can be performed.

  According to the fourth aspect of the present invention, it is determined whether a sudden disturbance has occurred based on a voltage signal converted from the detected acceleration and a predetermined threshold value, and the signal is switched according to the determination result. A switching signal for controlling the means can be generated and supplied to the signal switching means. Thus, when sudden disturbance occurs, it is possible to perform signal switching so as not to be affected by the sudden disturbance.

  According to the fifth aspect of the invention, the track position change due to only the sudden disturbance excluding the periodic disturbance is obtained by subtracting the tracking error signal from the corrected tracking error signal having the same phase by the phase adjusting means. The amount can be determined. In addition, according to the present invention, the signal generated by the correction tracking error signal generation unit is normally output to the storage unit, and when the sudden disturbance is detected, the signal whose phase is adjusted by the phase adjustment unit is stored in the storage unit. Can be output. As a result, when a sudden disturbance occurs, the circuit including the storage means is closed, and the influence of the sudden disturbance from the outside can be removed from the corrected tracking error signal stored in the storage means, so that stable tracking is possible. Control can be performed.

  According to the invention described in claim 6 or claim 8, it is possible to extract only the sudden disturbance from the tracking error signal including the sudden disturbance and the periodic disturbance and estimate it. Thus, in the tracking control apparatus incorporating the present invention, the disturbance can be separated into the sudden disturbance and the periodic disturbance and can be compensated at the same time, and the track position tracking performance can be improved.

[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. We will describe 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. I will do it.

(About estimation of sudden disturbance)
In general, in a tracking control device (for example, FIG. 14) having a feedback control system and a feedforward control system, a change amount (tracking error) of a track position is estimated based on a tracking error signal generated by the feedback control system. ing. Here, the feedback control system, in a certain sampling time k, when only periodic disturbance x ^ref (k) is inputted, the tracking error (correction tracking error signal) e _t ^feedback (k) is due to the periodic disturbance The tracking error x _f (k) is calculated by the following equation (1).

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. The present invention estimates sudden disturbance using a tracking error associated with the influence of this periodic 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 4 uses a light spot position correcting means (voice coil motor) at a certain sampling time k based on the periodic disturbance x ^ref (k) and the sudden disturbance I _d (k). 41 is a model for controlling 41. Here, the light spot position x (k) output from the light spot position correcting means (voice coil motor) 41 is, as shown in the following equation (2), a tracking error x _f (k) due to a periodic disturbance. 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 42 includes the periodic disturbance x ^ref (k) and the 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 the disturbance to the light spot position correcting means 41 is 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 43 (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 42. The current (periodic disturbance compensation I _f (k)) is added.

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

As described above, in the control system 4, the current (correction operation amount I _cmd (k)) for compensating for the disturbance input to the light spot position correcting unit 41 changes due to the influence of the disturbance, and the light spot position changes. Will do.
Here, assuming that the transfer function of the light spot position correcting means 41 is P (z ⁻¹ ), the tracking error x _d (k) due to sudden disturbance can be expressed by the following equation (5), which is due to periodic disturbance. The tracking error x _f (k) (= P (z ⁻¹ ) I _f (k)) satisfies the relationship of equation ( 6).

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

The equations (5) and (6) represent the input / output relationship of the sudden disturbance feedback control system and the periodic disturbance feedback control system in the control system 4, respectively. That is, as shown in FIG. 3, the control system 4 is divided into a sudden disturbance feedback control system 4A (FIG. 3 (a)) and a periodic disturbance feedback control system 4B (FIG. 3 (b)). 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. 3 (a), in the sudden disturbance feedback control system 4A, the current input to the light spot position correcting means 41 is a sudden disturbance and a 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 41. The sudden disturbance compensation I _b (k) can be calculated. That is, on the basis of the equations (7) and (8), a control object (enlarged plant) excluding periodic disturbances from the light spot position correcting means 41 that is a 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) 51 including a control target (plant) to which periodic disturbance and sudden disturbance are input, the expressions (7) and (8) are By applying, the expansion plant 53 which extracted the plant system 52 which excluded the periodic disturbance can be comprised.

  As described above, since the expansion plant 53 shown in FIG. 4 excludes periodic disturbances, it is robust against noise and changes in track position (becomes robust). Therefore, a sudden disturbance can be estimated by configuring a disturbance observer (disturbance observation device) for the expansion plant 53.

Hereinafter, when a disturbance observer is configured for the expansion plant 53, the following is obtained.
That is, when the light spot position correcting unit 41 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 53 are as follows: (10). A, B, and C are coefficient matrices constituting the discrete time state equation of the light spot position correcting means 41.

_{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.

  In the present invention, sudden disturbance can be estimated 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 control device)
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 correction operation amount generation unit (addition unit) 23, a D / A as a feedback control system 2. A conversion means 24, a light spot position correction means 25, and a sudden disturbance estimation means (sudden disturbance estimation device) 26 are provided. As the feedforward control system 3, a correction tracking error signal generation means (addition means) 30 and storage control are provided. Means 31, storage means 32, feedforward control means 33, and tracking error correction signal generation means 34 are provided.

  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 feedforward control system 3 functions to predict and correct errors due to disturbances that cannot be removed by the feedback control system 2 by increasing the frequency of disk rotation. 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.

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. The digitalized tracking error signal _et (k) is output to the feedback control means 22, the sudden disturbance estimation means 26, and the corrected tracking error signal generation means 30 of the feedforward control system 3.

The feedback control means (C (z ⁻¹ )) 22 is a general robust controller, but may be a controller based on a classical phase advance or delay, and does not correct the phase delay or increase the resonance frequency. It operates as a transfer function C (s) acting as described above, and generates an operation amount I _c (k) for correcting the light spot position 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 26d of the sudden disturbance estimating means 26.

The corrected manipulated variable generating means 23 is a disc that is estimated by the sudden disturbance manipulated variable (sudden disturbance compensation I _b (k)) generated by the disturbance manipulated variable generating means 26 d and the feedforward control means 33 of the feedforward control system 3. And an error correction amount (periodic disturbance compensation I _f (k)) for correcting an error due to disturbance such as decentration. The correction operation amount I _cmd (k) generated here is output to the D / A conversion means 24.

The D / A conversion unit 24 converts the correction operation amount I _cmd (k) that is a digital signal generated by the correction 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 correction operation amount converted into an analog signal is output to the light spot position correction means 25.

  The light spot position correction means (P (s)) 25 corrects the light spot position based on the correction 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.

Sudden disturbance estimating means (sudden disturbance estimation device) 26, a tracking error signal e _t (k), the feedforward control system 3 of the correction tracking correction error signal generated by the generation means 30 the tracking error signal e _t ^feedback (k + 2) Then, based on the operation amount I _c (k) generated by the feedback control means 22, a sudden disturbance operation amount that estimates the sudden disturbance is generated. Here, the sudden disturbance estimation unit 26 includes a phase adjustment unit 26a, a disturbance tracking error generation unit 26b, a disturbance estimation unit 26c, and a disturbance operation amount generation unit 26d.

The phase adjusting means 26a is for adjusting the phase of the tracking error signal and the corrected tracking error signal. Here, the phase adjusting means 26a is advanced second sampling output from the memory control unit 31 corrects the tracking error signal e ^{_t? Feedback} the (k + 2), the delay means not shown, by 2 sample delay, the tracking error The phase with the signal _et (k) is matched. Here delayed correction tracking error signal e _t ^feedback (k) is output to the disturbance tracking error generation means 26b.

Disturbance tracking error generating means (subtracting means) 26b includes a tracking error signal e _t (k), by taking the difference between the corrected tracking error signal e ^{_t? Feedback} (k), is a variation of the track position by sudden disturbance A tracking error x _d (k) 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 estimating means 26c.

The disturbance estimation unit 26c is based on the tracking error x _d (k) generated by the disturbance tracking error generation unit 26b and the sudden disturbance operation amount I _b (k) for which the sudden disturbance is compensated. A correction amount (sudden disturbance amount I _d ′ (k)) with respect to an operation amount for correcting the spot position is estimated. That is, the disturbance estimation unit 26c estimates the sudden disturbance amount I _d ′ (k) by sequentially performing the calculation of the equation (12). The sudden disturbance amount I _d ′ (k) estimated here is output to the disturbance manipulated variable generation means 26d.

The disturbance operation amount generation unit 26d adds the operation amount I _c (k) generated by the feedback control unit 22 and the sudden disturbance amount I _d ′ (k) estimated by the disturbance estimation unit 26c, thereby generating the sudden operation. A sudden disturbance manipulated variable (sudden disturbance compensation: I _b (k)) for compensating the disturbance is generated. The sudden disturbance operation amount generated here is output to the disturbance estimation means 26 c and the correction operation amount generation means 23.
Thus, by configuring the sudden disturbance estimation means (sudden disturbance estimation device) 26, only the sudden disturbance can be estimated and compensated.

Next, the configuration of the feedforward control system 3 will be described.
The correction tracking error signal generation unit 30 adds a tracking error signal converted into a digital signal by the A / D conversion unit 21 and a tracking error correction signal generated by a tracking error correction signal generation unit 34, which will be described later, to perform correction. A tracking error signal is generated. The corrected tracking error signal generated here is stored in the storage unit 32 via the storage control unit 31.

  The storage control means 31 writes the correction tracking error signal generated by the correction tracking error signal generation means 30 for a time corresponding to at least one rotation period of the optical disc in the storage means 32 in time series, and already stored corrections. The tracking error signal is read from the storage means 32 and output to the feedforward control means 33 and the sudden disturbance estimation means 26.

  The storage means 32 is composed of a general memory or the like, and stores the correction tracking error signal generated by the correction tracking error signal generation means 30.

A feedforward control means (G _ff (z ⁻¹ )) 33 is a precompensator to which zero phase error tracking (ZPET) control is applied, and a corrected tracking error output from the storage control means 31. Based on the signal, an error correction amount (periodic disturbance compensation _If (k)) for correcting the light spot position is generated.
The error correction amount generated here is output to the tracking error correction signal generation unit 34 and the correction operation amount generation unit 23 of the feedback control system 2.

Here, the transfer function G _ff (z ⁻¹ ) of the feedforward control means 33 will be described with reference to FIG. FIG. 5 is a configuration diagram showing a configuration of a general control system in which feedforward control is applied to the feedback control system. The control system 5 includes a feedback controller FB, a D / A converter DAC, a control target TA, an A / D converter ADC, a closed loop system CL including a subtractor DE, and a feedforward controller FF. It is configured.

Here, when the input to the closed loop system CL is r (k) and the output is x (k), the transfer function G _closed (z ⁻¹ ) from r (k) to x (k) is expressed by the following (13 The output x (k) can be expressed by the following expression (14). Further, when the input of the feedforward controller FF is x ^ref (k), the output r (k) can be expressed by the following equation (15).

x (k) = G _closed (z ⁻¹ ) r (k) (14) Formula r (k) = G _ff (z ⁻¹ ) x ^ref (k) (15)

The following equation (16) is calculated from the equations (14) and (15), and in order to match x (k) and x ^ref (k), the following equations (16) and (17) are used. Satisfy it. That is, the transfer function G _ff (z ⁻¹ ) can be expressed by the following equation (18).

x (k) = G _closed (z ^-1 ) G _ff (z ^-1 ) x ^ref (k) (16) Equation G _closed (z ^-1 ) G _ff (z ^-1 ) = 1 (17)

In the zero phase error tracking (ZPET) method, as shown in the following equation (19), B _c (z ⁻¹ ) is represented by an unstable zero (B ⁻ _c (z ⁻¹ )) and a stable zero (B ⁺ _c (z ⁻¹ )), the transfer function G _ff (z ⁻¹ ) is expressed by the following equation (20).
^{_{B c (z -1) = B}} - c (z -1) B + c (z -1) ... (19) equation

Returning to FIG. 1, the description will be continued.
The feedforward control means 33 has the transfer function G _ff (z ⁻¹ ) of the above equation (20), and this transfer function includes z ^d in the numerator. That is, the output at time k on a certain time axis depends on the input at time k + d. Therefore, in the feedforward control means 33, the transfer function C (s) of the feedback control means 22 is expressed by the following expression (21), and the transfer function P (s) of the light spot position correcting means 25 is expressed by the following expression (22). doing, the estimated number sampling and 2, a tracking error signal of second sampling future correction tracking error signal e ^{_t? feedback} the (k + 2), obtained from the storage control unit 31, the error correction amount (I _f (k)) Make predictions. Here, a ₀ , a ₁ , b ₀ , c _{0 to} c ₄ , and d _{0 to} d ₄ are constants.

  Note that the predicted sampling number also varies depending on the order of the controller and model and the design method of the precompensator. For example, it becomes 1 when ZPET is changed to the stable pole zero cancellation method.

The tracking error correction signal generating unit 34 generates a tracking error correction signal for correcting the tracking error signal. The tracking error correction signal generation unit 34 performs an operation of P (z ⁻¹ ) / (1 + C (z ⁻¹ ) P (z ⁻¹ )) on the error correction amount generated by the feedforward control unit 33. In this way, a tracking error correction signal is generated. The tracking error correction signal generated here is input to the corrected tracking error signal generation means 30, thereby forming the feedforward control system 3.

  As described above, the feedback control system 2 of the tracking control device 1 includes the sudden disturbance estimation means 26 that can estimate only the sudden disturbance, so that only the sudden disturbance can be separated from the disturbance and compensated.

(Operation of tracking controller)
Next, the operation of the tracking control apparatus according to the first embodiment will be described with reference to FIG. FIG. 6 is a flowchart showing the operation of the tracking control device.
First, in the feedback control system 2, 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 and input to the feedback control means 22, the sudden disturbance estimation means 26, and the feedforward control system 3.

  Then, the tracking control device 1 adds the tracking error signal and the tracking error correction signal generated by the tracking error correction signal generation unit 34 by the correction tracking error signal generation unit 30 in the feedforward control system 3 and corrects them. A tracking error signal is generated (step S2: corrected tracking error signal generation step) and stored in the storage means 32 via the storage control means 31 (step S3: storage step).

  Then, the tracking control device 1 generates an error correction amount for correcting the light spot position by the feedforward control means 33 (step S4: feedforward control step). The error correction amount generated here is output to the tracking error correction signal generating means 34 and also output to the feedback control system 2.

Further, the tracking control device 1 generates a tracking error correction signal for correcting the tracking error signal from the error correction amount by the tracking error correction signal generation means 34 (step S5: tracking error correction signal generation step). The tracking error correction signal generated here is used in step S2.
The operation from step S2 to step S5 described above corresponds to the operation of the feedforward control system 3.

On the other hand, the tracking control device 1 corrects the light spot position by the feedback control unit 22 from the tracking error signal generated in step S1 and converted into a digital signal by the A / D conversion unit 21 in the feedback control system 2. An operation amount (I _c (k)) is generated (step S6: feedback control step).

In the tracking control device 1, in the sudden disturbance estimation unit 26, the phase adjustment unit 26a acquires the corrected tracking error signal stored in the storage unit 32 in step S3 via the storage control unit 31 (step S7). Then, the phase is adjusted (step S8: phase adjustment step). Specifically, the phase adjustment unit 26a delays the correction tracking error signal by a delay unit (not shown). Then, the tracking control device 1 generates the tracking error x _d (k) due to the sudden disturbance by subtracting the corrected tracking error signal from the tracking error signal by the disturbance tracking error generation means 26b (step S9: disturbance tracking error). Generation step).

Then, the tracking control device 1 uses the disturbance estimation unit 26c to calculate the amount of sudden disturbance (suddenly) based on the tracking error x _d (k) and the sudden disturbance operation amount I _b (k) for which the sudden disturbance has been compensated. The disturbance amount I _d ′ (k)) is estimated (step S10: disturbance estimation step).

The tracking control device 1 adds the sudden disturbance amount I _d ′ (k) estimated in step S10 to the operation amount I _c (k) generated in step S6 by the disturbance operation amount generation unit 26d. A sudden disturbance manipulated variable I _b (k) that compensates for sudden disturbance is generated (step S11: disturbance manipulated variable generating step).
The operations from step S7 to step S11 described above correspond to the operation of the sudden disturbance estimation means 26 (sudden disturbance estimation step).

Furthermore, the tracking control device 1 adds the error correction amount generated in step S4 and the sudden disturbance operation amount generated in step S11 by the correction operation amount generation unit 23, and calculates the correction operation amount I _cmd (k). Generate (step S12).

The tracking control device 1 converts the correction operation amount I _cmd (k) generated in step S12 into an analog signal by the D / A conversion unit 24, and then converts it into an analog signal by the light spot position correction unit 25. The light spot position is corrected by the corrected operation amount (step S13).
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).

The above-described step S1 and the operations from step S6 to step S13 correspond to the operation of the feedback control system 2.
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. 7, the evaluation result of the tracking control apparatus in 1st Embodiment is demonstrated. FIG. 7 is a graph showing the evaluation results of the tracking control device, where (a) is a graph showing the tracking response (tracking error signal) in the conventional tracking control device 1C (FIG. 14), and (b). These are the graphs which showed the tracking response (tracking error signal) in the tracking control apparatus 1 (FIG. 1) which concerns on 1st Embodiment. In both (a) and (b), a tracking response signal is shown in the upper stage, and an input signal of sudden disturbance is shown in the lower stage. In the upper stage, the horizontal axis represents time [sec], and the vertical axis represents the tracking error signal _et [m]. In the lower stage, the horizontal axis represents time [sec], and the vertical axis represents the current value [sudden disturbance I _d [ A].

As shown in FIG. 7, in the past, a tracking error signal of about 1.5 × 10 ⁻⁷ [m] against a large sudden disturbance exceeding −0.4 [A] at 0.38 [sec]. However, in the tracking control device 1 according to the first embodiment, the tracking error signal is within ± 0.03 × 10 ⁻⁷ [m] even when a sudden disturbance occurs, and is high. It was confirmed that the tracking operation was performed accurately. As described above, the tracking control device 1 according to the first embodiment can accurately perform tracking control even when a sudden disturbance occurs during high-speed rotation of the disk.

[Second Embodiment]
The tracking control device 1 according to the first embodiment can perform high-speed and high-precision control at a time when there is no sudden disturbance such as vibration or impact. Further, even if the sudden disturbance occurred, immediately after this, so far the stored in the storage unit 32 corrects the tracking error signal e _t ^feedback (k) is the signal without the influence of sudden disturbances. Therefore, the tracking error x _d (k) due to the sudden disturbance generated by the disturbance tracking error generation unit 26b is an ideal value in the disturbance estimation unit 26c. As a result, stable tracking control can be performed. But then, taking the correction tracking error signal e ^{_t? Feedback} such as those containing components (k) in the memory means 32 of the sudden disturbance (its effect on tracking by sudden disturbance error x _d (k) is taken) possibility considered It is done. Even in such a case, a tracking control device capable of exhibiting the effect of sudden disturbance suppression by the disturbance estimation means 26c will be described as a second embodiment with reference to FIG . 8 to FIG .

(Configuration of tracking control device)
With reference to FIG. 8, the configuration of the tracking control apparatus according to the second embodiment will be described. FIG. 8 is a block diagram showing the configuration of the tracking control apparatus of the second embodiment. As shown in FIG. 8, the tracking control device 1 </ b> A has the same configuration as the tracking control device 1 shown in FIG. 1 except that it includes a signal switching unit SW <b> 1 and a sudden disturbance detection unit 40. In the tracking control device 1A, the same components as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

The signal switching means SW1 is provided between the correction tracking error signal generating means 30 and the storage control means 31 of the feedforward control system 3a. The signal switching means SW1 includes a common terminal o, a constantly connected terminal a, and a normally open terminal b, and selectively switches between the terminal a and the terminal b as a contact point, and either one is used as an input to the storage control means 31. By connecting to the connected terminal o, the signal output from the terminal o (signal input to the storage control means 31) is switched.
The terminal a is connected to the output of the correction tracking error signal generation means 30, and the terminal b is connected to the output of the phase adjustment means 26 a of the sudden disturbance estimation means 26. Normally, the signal switching means SW1 is switched to the terminal a side. At this time, the output signal of the correction tracking error signal generating means 30 is input to the storage control means 31. When a sudden disturbance occurs, the signal switching means SW1 is switched to the terminal b side. At this time, the output signal of the phase adjusting means 26a is input to the storage control means 31.

The sudden disturbance detection means 40 detects sudden disturbance, and generates a switching signal for controlling the operation of the signal switching means SW1 according to the presence or absence of the sudden disturbance. FIG. 9 is a block diagram showing details of the sudden disturbance detection means. As shown in FIG. 9, the sudden disturbance detection means 40 includes an acceleration detection means 41, a signal conversion means 42, a voltage level determination means 43, and a switching signal generation means 44.
The acceleration detection means 41 is composed of, for example, an acceleration sensor and detects acceleration, and outputs the detected acceleration signal to the signal conversion means 42. In general, a mechanical disturbance is represented by a product of mass and acceleration, so that the acceleration detected by the acceleration detecting means 41 corresponds to a sudden disturbance.
The signal conversion unit 42 converts the acceleration signal detected by the acceleration detection unit 41 into a voltage signal, and outputs the converted voltage signal to the voltage level determination unit 43.

The voltage level determination unit 43 compares the voltage signal input from the signal conversion unit 42 with a predetermined threshold value to determine whether there is a sudden disturbance. The 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. . This threshold value | V _TH | can be arbitrarily adjusted in level.
The voltage level determination means 43 determines that a sudden disturbance has occurred when determining that the voltage signal input from the signal conversion means 42 is greater than the threshold value | V _TH |, and generates a switching signal as a result of the determination. It outputs to the means 44.
The voltage level determination means 43 determines that no sudden disturbance has occurred when determining that the voltage signal input from the signal conversion means 42 is smaller than the threshold value | V _TH |, and generates a switching signal as a result of the determination. It outputs to the means 44.

The switching signal generating unit 44 generates a switching signal according to the determination result input from the voltage level determining unit 43, and supplies the generated switching signal to the signal switching unit SW1.
Switching signal generating means 44, when the inputted judgment result of the sudden disturbance is generated from the voltage level determination means 43, the signal switching means SW1 terminal b V switching signal for controlling to switch to the side _{sw +} ( 1st switching signal) is generated.
Further, the switching signal generating means 44 controls the switching of the signal switching means SW1 to the terminal a side when the judgment result that the sudden disturbance has not occurred is inputted from the voltage level judging means 43. _sw- (second switching signal) is generated.

(Operation of tracking controller)
Next, referring to FIG. 10 (refer to FIGS. 8 and 9 as appropriate), the operation of the tracking control apparatus according to the second embodiment will be described. FIG. 10 is a flowchart showing the operation of the tracking control device when a sudden disturbance occurs.
The tracking control device 1A normally operates as shown in the flowchart of FIG. At this time, the signal switching means SW1 is switched to the a side. Here, if a sudden disturbance such as vibration or impact occurs, the tracking control device 1A operates as shown in the flowchart of FIG.

In the sudden disturbance detection unit 40, the tracking control apparatus 1A detects an acceleration signal corresponding to the sudden disturbance by the acceleration detection unit 41 (step S31).
Then, the tracking control device 1A converts the acceleration signal detected by the acceleration detection means 41 into the voltage signal Va by the signal conversion means 42 (step S32).
In the tracking control device 1A, the voltage level determination unit 43 determines whether the detected voltage signal is larger than the threshold value. Specifically, the absolute value | Va | of the amplitude level of the detected voltage signal (acceleration converted voltage) is detected, and | Va | is compared with a threshold value | V _TH |, and | Va | It is determined whether it is larger than | V _TH | (step S33).

If the tracking control device 1A determines that | Va | is not larger than | V _TH |, the tracking control device 1A returns to step S31 to detect an acceleration signal.
If the tracking control device 1A determines that | Va | is greater than | V _TH |, the switching signal generating means 44 generates the switching signal V _{sw +} (step S34). The switching signal V _{sw +} generated by the switching signal generating unit 44 is supplied to the signal switching unit SW1. As a result, the tracking control device 1A switches the contact of the signal switching means SW1 from the terminal a side to the terminal b side (step S35). Then, the tracking control device 1A holds (latches) the state of the contact point switched to the terminal b side in step S35 (step S36).

Subsequently, the tracking control apparatus 1A compares the absolute value | Va | of the amplitude level of the acceleration conversion voltage with the threshold value | V _TH | by the voltage level determination unit 43, and | Va | is | V _TH | Or less (step S37).
The tracking control device 1A continues the determination until | Va | becomes smaller than | V _TH |, and when it is determined that | Va | is smaller than | V _TH |, that is, returns to a normal state without sudden disturbance. In this case, the switching signal generating means 44 generates the switching signal V _sw− (step S38). The switching signal V _sw− generated by the switching signal generating means 44 is supplied to the signal switching means SW1, but does not affect the contact of the signal switching means SW1. At this time, the tracking control device 1A holds the contact of the signal switching means SW1 on the terminal b side, and the contact cannot be switched.

The tracking control device 1A determines whether or not the number of samples stored in the storage unit 32 is kN by the storage control unit 31 (step S39). Here, k is a natural number, and N is the number of samples corresponding to one rotation period of the disk delayed by the phase adjusting means 26a.
When the tracking control apparatus 1A determines that the number of samples stored in the storage means 32 is kN (step S39: Yes), the contact of the signal switching means SW1 is switched from the terminal b side to the terminal a side (step S40). ), The process returns to step S31.
In the tracking control device 1A, sudden disturbance (acceleration signal or voltage signal) is constantly observed by the sudden disturbance detection means 40, and sudden disturbance suppression is always performed by the sudden disturbance estimation means 26 in any disturbance situation. The effect can be demonstrated.

Here, the switching timing of the contacts of the signal switching means SW1 will be described with reference to FIG. FIG. 11 is a timing chart of the switching signal and the signal switching means.
As shown in FIG. 11, the sudden disturbance shown in (a) occurs when True (1) and disappears when False (0).
The switching signal shown in (b) becomes V _{sw +} when the sudden disturbance shown in (a) is True (1), and becomes V _sw− when False (0). That is, the switching signal shown in (b) switches from V _sw− to V _{sw +} when a sudden disturbance occurs. The switching signal generation unit 44 continues to output the switching signal V _{sw +} to the signal switching unit SW1 while the sudden disturbance continues. Then, the switching signal generation means 44 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- .

The contact of the signal switching means SW1 shown in FIG. 11C is switched to the terminal a side in the initial state (time = 0) (always connected), and when a sudden disturbance occurs, that is, the switching signal is When it changes from V _sw− to V _{sw +} , it is switched to the terminal b side and the state is latched. 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 signal switching means SW1 holds the current state, and the number of samples stored in the storage means 32 is kN. At this point, the terminal b is switched to the terminal a.

For this reason, in a state where the contact of the signal switching means SW1 is switched to the terminal a side, it becomes a disc rotation break. Since the tracking control device 1A holds data for one rotation of the disk in the storage means 32 in advance, when a sudden disturbance occurs, the data at the time of disk rotation one rotation before the sudden disturbance occurs is the phase. The data is sent again from the adjustment means 26a to the storage control means 31. Thus, when a sudden disturbance occurs, as a correction tracking error signal e ^{_t? Feedback} phase adjusting means 26a outputs (k-N), a signal that does not include sudden disturbance component occurs repeatedly.

Therefore, the disturbance tracking error generation means 26b for obtaining a difference of the correction tracking error signal e ^{_t? Feedback} from the phase adjusting means 26a and (k-N) and the tracking error signal e _t (k) is not affected by sudden disturbance tracking error x _d (k) can be output to the disturbance estimating means 26c. As a result, even when the sudden disturbance continues for a long time, the control operation by the sudden disturbance estimation means 26 is stably performed, and stable tracking control resistant to the disturbance can be performed.

(Evaluation of tracking controller)
Here, with reference to FIG. 12, the evaluation result of the tracking control apparatus 1A of the second embodiment will be described. FIG. 12 is a graph showing the evaluation results of the tracking control device, where (a) is a graph showing the tracking response (tracking error signal) in the tracking control device 1 (FIG. 1) of the first embodiment. (B) is the graph which showed the tracking response (tracking error signal) in the tracking control apparatus 1A (FIG. 8) of 2nd Embodiment. (C) has shown the input signal of sudden disturbance.
In both (a) and (b), the horizontal axis indicates time [sec], the vertical axis indicates the tracking error signal _et [m], and in (c), the horizontal axis indicates time [sec] and the vertical axis suddenly appears. current value is a disturbance I _d shows a [a].

In the tracking control device 1 of the first embodiment, as shown in FIG. 12 (c), when a large sudden disturbance that exceeds −1.2 [A] at 0.38 [sec] is given, As shown in FIG. 12A, a tracking error signal of about 2.1 × 10 ⁻⁷ [m] is generated. On the other hand, when the sudden disturbance is the same condition, the tracking control device 1A of the second embodiment has a tracking error of about 1.8 × 10 ⁻⁷ [m] as shown in FIG. A signal is generated.
Therefore, the tracking control device 1A of the second embodiment performs a tracking operation with high accuracy for reducing the tracking error signal, which is a disturbance suppression response, to about 85%, as compared with the tracking control device 1 of the first embodiment. I was able to confirm it.
According to the second embodiment, tracking control can be stably performed even when vibrations or shocks occur suddenly.

(Third embodiment)
The present invention is not limited to the first and second embodiments, and the same effect can be achieved even when a feedforward control system is not provided or when a focus control system is provided. . For example, a tracking control device having a configuration not including a feedforward control system will be described as a third embodiment with reference to FIG. FIG. 13 is a block diagram illustrating a configuration of the tracking control apparatus according to the third embodiment. As shown in the figure, the tracking control apparatus 1B does not include a correction tracking error signal generation unit 30, a feedforward control unit 33, and a tracking error correction signal generation unit 34 (so-called feedforward control system). However, the storage control means 31 and the storage means 32 are provided. Further, the feedback control system 2B has the same configuration as the feedback control system 2 of the second embodiment, except that the correction operation amount generation means 23 is not provided. The description is omitted. This embodiment includes sudden disturbance estimation means 26 which is the main part of the present invention, and this can be covered even if a feedforward control system is not provided.

The storage means 32 stores the tracking error signal _et (k) as a correction tracking error signal _et2 ^feedback (k).
In this tracking control device 1B, sudden disturbance detection means 40 constantly observes sudden disturbance, performs contact switching of signal switching means SW1 according to sudden disturbance, and sudden disturbance estimation means 26 suppresses sudden disturbance suppression. Demonstrate the effect. In other words, the tracking control device 1B causes the phase adjustment unit 26a to delay the correction tracking error signal stored in the storage unit 32 so as to match the phase with the tracking error signal. Then, the correction tracking error signal _{et 2} ^feedback ( ^kN ) whose phase is adjusted by the disturbance tracking error generating means 26b (N indicates the number of samples corresponding to one rotation period of the disk delayed by the phase adjusting means 26a). Then, a tracking error x _d2 (k) due to sudden disturbance is generated by subtracting the tracking error signal _et (k) and taking the difference. The tracking error x _d2 (k) generated by the sudden disturbance generated here is output to the disturbance estimating means 26c. Thereby, the disturbance estimation means 26c can exhibit the effect of sudden disturbance suppression.

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 the block diagram which showed the structure of the general control system which applied feedforward control to the feedback control system. It is a flowchart which shows operation | movement of the tracking control apparatus which concerns on 1st Embodiment. It is a graph which shows the evaluation result of a tracking control apparatus, (a) is a tracking response (tracking error signal) in the conventional tracking control apparatus, (b) is a tracking response (tracking) in the tracking control apparatus according to the present invention. Error signal). 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 detail of a sudden disturbance detection means. It is a flowchart which shows operation | movement of the tracking control apparatus which concerns on 2nd Embodiment. It is a timing chart of a switching signal and a signal switching means. It is a graph which shows the evaluation result of a tracking control apparatus, Comprising: (a) is a tracking response (tracking error signal) in the tracking control apparatus of 1st Embodiment, (b) is tracking control of 2nd Embodiment. A tracking response (tracking error signal) and (c) in the apparatus show an input signal of sudden disturbance. It is the block diagram which showed the structure of the tracking control apparatus of 3rd Embodiment. It is the block diagram which showed the structure of the conventional tracking control apparatus.

Explanation of symbols

1, 1A, 1B, 1C Tracking control device 2, 2B, 2C Feedback control system 20 Tracking error signal generation means 21 A / D conversion means 22 Feedback control means 23 Correction operation amount generation means 24 D / A conversion means 25 Light spot position Correction means 26 Sudden disturbance estimation means (sudden disturbance estimation device)
26a Phase adjustment means 26b Disturbance tracking error generation means 26c Disturbance estimation means 26d Disturbance manipulated variable generation means 3, 3A Feedforward control system 30 Correction tracking error signal generation means 31 Storage control means 32 Storage means 33 Feedforward control means 34 Tracking error correction Signal generation means 40 Sudden disturbance detection means SW1 Signal switching means

Claims (8)

A feedback control system for correcting the light spot position based on 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 based on the tracking error signal In the tracking control apparatus that controls the light spot position by a feedforward control system that estimates an error correction amount indicating a correction error in the feedback control system,
The feedforward control system is
A correction tracking error signal generating means for generating a corrected tracking error signal by adding the tracking error signal and a tracking error correction signal for correcting the tracking error signal;
Storage means for storing the corrected tracking error signal generated by the corrected tracking error signal generating means;
Feedforward control means for compensating for the amplitude and phase of the correction tracking error signal stored in the storage means and generating the error correction amount;
Tracking error correction signal generation means for generating the tracking error correction signal based on the error correction amount generated by the feedforward control means,
The feedback control system is
Feedback control means for compensating for the amplitude and phase of the tracking error signal and generating an operation amount for correcting the light spot position;
Based on the tracking error signal and the corrected tracking error signal, the sudden disturbance amount input from the outside with respect to the manipulated variable is estimated, and the sudden disturbance estimation unit that generates the sudden disturbance manipulated variable by correcting the manipulated variable; ,
A tracking control device comprising: The sudden disturbance estimation means is
A phase adjusting means for adjusting the phase of the corrected tracking error signal and the tracking error signal by delaying the corrected tracking error signal;
Disturbance tracking error generating means for generating a change amount of the track position based on a difference between the correction tracking error signal whose phase is adjusted by the phase adjusting means and the tracking error signal;
Disturbance estimation means for estimating the amount of sudden disturbance based on the amount of change in track position generated by the disturbance tracking error generation means and the amount of sudden disturbance operation before at least one sampling of the disk;
Based on the sudden disturbance amount estimated by the disturbance estimation unit and the operation amount generated by the feedback control unit, a disturbance operation amount generation unit that generates the sudden disturbance operation amount that compensates for the sudden disturbance,
The tracking control device according to claim 1, further comprising: A signal switching unit that selects one of the correction tracking error signal generated by the correction tracking error signal generation unit and the correction tracking error signal whose phase is adjusted by the phase adjustment unit and outputs the selected signal to the storage unit; ,
A sudden disturbance detecting unit that detects the sudden disturbance and switches the signal switching unit so as to select the correction tracking error signal whose phase is adjusted by the phase adjusting unit when the sudden disturbance is detected;
The tracking control device according to claim 2, further comprising: The sudden disturbance detection means includes
Acceleration detecting means for detecting acceleration of sudden disturbance;
Signal conversion means for converting the acceleration signal detected by the acceleration detection means into a voltage signal;
Voltage level determination means for comparing the voltage signal converted by the signal conversion means and a predetermined threshold value to determine the presence or absence of sudden disturbance,
When the voltage signal is larger than the threshold value, a first switching signal for selecting a corrected tracking error signal whose phase is adjusted by the phase adjusting means is generated, and the voltage signal is the threshold value. The second switching signal for selecting the corrected tracking error signal generated by the corrected tracking error signal generating means is generated, and the generated first or second switching signal is used as the signal switching means. Switching signal generating means for supplying to
The tracking control device according to claim 3, further comprising: Tracking for controlling the light spot position by correcting the light spot position based on 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. In the control device,
Feedback control means for compensating for the amplitude and phase of the tracking error signal and generating an operation amount for correcting the light spot position;
Based on the tracking error signal, a sudden disturbance amount input from the outside with respect to the manipulated variable is estimated, and a sudden disturbance manipulation unit that corrects the manipulated variable to generate a sudden disturbance manipulated variable, and
Storage means for storing the tracking error signal as a correction tracking error signal,
The sudden disturbance estimation means includes
A phase adjustment unit that adjusts the phase of the tracking error signal for correction and the tracking error signal by delaying the tracking error signal for correction stored in the storage unit;
Disturbance tracking error generating means for generating a change amount of the track position based on a difference between the tracking error signal for correction whose phase is adjusted by the phase adjusting means and the tracking error signal;
Based on the amount of change in the track position generated by the disturbance tracking error generation means and the sudden disturbance operation amount before at least one sampling of the disk, an external input for the operation amount generated by the feedback control means is input. Disturbance estimation means for estimating the sudden disturbance amount;
A disturbance operation amount generating means for generating the sudden disturbance operation amount for compensating for the sudden disturbance based on the sudden disturbance amount estimated by the disturbance estimation means and the operation amount generated by the feedback control means; And
The tracking control device further includes:
A signal switching means for selecting one of the tracking error signal and the correction tracking error signal whose phase is adjusted by the phase adjusting means and outputting the selected signal to the storage means;
A sudden disturbance detecting unit that detects the sudden disturbance and switches the signal switching unit so as to select a correction tracking error signal whose phase is adjusted by the phase adjusting unit when the sudden disturbance is detected;
A tracking control device comprising: The track position on the disc, based on the tracking error signal indicating an error between the light spot position of the light beam emitted from the optical head, a feedback control system for generating a manipulated variable for compensation of the light spot position and The tracking error signal is controlled by the feedforward control system that estimates an error correction amount indicating a correction error in the feedback control system based on the tracking error signal. Based on a corrected tracking error signal obtained by correcting the tracking error signal based on the error correction amount in the feedforward control system, an unexpected disturbance amount input from the outside with respect to the operation amount is estimated, and the operation amount is corrected. Sudden Disturbance Estimator that Generates Sudden Disturbance Manipulation There,
A phase adjusting means for adjusting the phase of the corrected tracking error signal and the tracking error signal by delaying the corrected tracking error signal;
Disturbance tracking error generating means for generating a change amount of the track position based on a difference between the correction tracking error signal whose phase is adjusted by the phase adjusting means and the tracking error signal;
Disturbance estimation means for estimating the amount of sudden disturbance based on the amount of change in track position generated by the disturbance tracking error generation means and the amount of sudden disturbance operation before at least one sampling of the disk;
Based on the sudden disturbance amount estimated by the disturbance estimation unit and the operation amount generated by the feedback control unit, a disturbance operation amount generation unit that generates the sudden disturbance operation amount that compensates for the sudden disturbance,
A sudden disturbance estimation device characterized by comprising: A feedback control system for correcting the light spot position based on 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 based on the tracking error signal In the tracking control method for controlling the light spot position by a feedforward control system that estimates an error correction amount indicating a correction error in the feedback control system,
The feedforward control system is
A correction tracking error signal generation step of generating a correction tracking error signal by adding the tracking error signal and a tracking error correction signal for correcting the tracking error signal;
A storage step of storing the correction tracking error signal generated in the correction tracking error signal generation step in a storage unit;
A feedforward control step of compensating the amplitude and phase of the correction tracking error signal stored in the storage means and generating the error correction amount;
A tracking error correction signal generating step for generating the tracking error correction signal based on the error correction amount generated in the feedforward control step,
The feedback control system is
A feedback control step of compensating for the amplitude and phase of the tracking error signal and generating an operation amount for correcting the light spot position;
Based on the tracking error signal and the corrected tracking error signal, an unexpected disturbance amount input from the outside with respect to the operation amount is generated, and an unexpected disturbance estimation step for generating an unexpected disturbance operation amount in which the operation amount is corrected; ,
The tracking control method characterized by including. The track position on the disc, based on the tracking error signal indicating an error between the light spot position of the light beam emitted from the optical head, a feedback control system for generating a manipulated variable for compensation of the light spot position and The tracking error signal is controlled by the feedforward control system that estimates an error correction amount indicating a correction error in the feedback control system based on the tracking error signal. Based on a corrected tracking error signal obtained by correcting the tracking error signal based on the error correction amount in the feedforward control system, an unexpected disturbance amount input from the outside with respect to the operation amount is estimated, and the operation amount is corrected. Sudden Disturbance Estimation Method that Generates a Sudden Disturbance Manipulation Variable There,
A phase adjustment step for adjusting the phase of the corrected tracking error signal and the tracking error signal by delaying the corrected tracking error signal;
A disturbance tracking error generation step for generating a change amount of the track position based on a difference between the correction tracking error signal whose phase is adjusted in the phase adjustment step and the tracking error signal,
A disturbance estimation step for estimating the sudden disturbance amount based on the change amount of the track position generated in the disturbance tracking error generation step and the sudden disturbance operation amount before at least one sampling of the disk;
A disturbance operation amount generating step for generating the sudden disturbance operation amount for compensating for the sudden disturbance based on the sudden disturbance amount estimated in the disturbance estimation step and the operation amount generated in the feedback control step;
The sudden disturbance estimation method characterized by including.

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