JP2007257586A - Control device and control program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control device and a control program enhanced in followability. <P>SOLUTION: Coefficient for each of sine wave functions for expressing each of components, comprising a fundamental wave and each of higher harmonic synchronized with the rotation of a rotating body for error waves in an error wave learning part 303 is obtained, from these coefficients, time variation of a phase of each of the sine wave functions is detected by a phase change detection part 305, when the time variation of the phase detected by an oscillation detection part 306 is rapid, it is decided to be in an oscillating state, and the phase is updated and corrected by a designated value in a phase adjustment part 307. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention provides a control device that controls a control target based on an error waveform that is a difference between a control target value of the control target that generates a synchronization error synchronized with the rotation of the rotating body and a control achievement value of the control target, and The present invention relates to a control program executed in a control computer for controlling a control object in which a synchronization error occurs in synchronization with rotation of a rotating body.

  In recent years, a storage device such as a magnetic disk device or an optical disk device has been requested to increase in storage capacity. Accordingly, a rotating medium such as a magnetic disk or an optical disk, which is a storage medium used in these storage devices, has been requested. The track density is also increasing. For this reason, a tracking control technique for causing the position of the head accessing the rotating body to accurately follow the track of the rotating body is important. Here, for example, a disturbance (one or a plurality of disturbances in the vicinity of a specific frequency) having a rotation frequency due to eccentricity of the rotating body and a frequency that is an integral multiple thereof may deteriorate the tracking control tracking performance. A technique using a learning control system is known as one of techniques for suppressing such disturbance.

  As one of the methods based on the learning control system, a disturbance model of a specific frequency is expressed by weighted synthesis of a sin function and a cos function, and each amplitude (gain) is sequentially learned and identified, whereby the disturbance amplitude of the target frequency and There is known a method of compensating for disturbance of a target frequency by sequentially identifying phases and feeding forward the identified results. However, when the frequency band of the target frequency becomes high, the phase delay of the feedback system including the frequency characteristic of the mechanism unit for controlling the position of the head that is the control target may not be ignored. Therefore, the amount of the phase delay is assumed in advance, phase advance compensation is performed so as to correct the phase delay, and feedforward control is performed by the learning control system to avoid the above problem. It is.

  FIG. 8 is a diagram illustrating a configuration of a conventional control device that corrects phase delay and performs feedforward control by a learning control system.

  A control device 1000 shown in FIG. 8 is a control device for performing follow-up control of the head mechanism in a certain disk device, and the controlled object 2000 is the position of the head constituting the head mechanism. The head position is controlled by controlling a track mechanism unit, a focus actuator, and the like that constitute the head mechanism. Here, the position of the head, which is the controlled object 2000, is affected by disturbance including a sine wave component (including a high-order sine wave component) synchronized with the rotation of the disk. In FIG. 8, in order to clearly indicate that the position of the head that is the control target 2000 is affected by the disturbance, the fact that the disturbance is applied to the position of the head is schematically shown in the portion indicated by the arrow A.

  The control apparatus 1000 shown in FIG. 8 includes a feedback error calculation unit 1001, an error waveform learning unit 1002, a feedforward correction unit 1003, a feedback control unit 1004, and an initial phase storage unit 1005.

  The feedback error calculation unit 1001 receives a signal representing the control target value of the controlled object 2000 in which a synchronization error is generated in synchronization with the rotation of the disk serving as the storage medium (for example, a signal representing a certain value that does not change with time). Is done. Further, the feedback error calculation unit 1001 receives a control achievement signal representing a control achievement value from the control object 2000. The feedback error calculation unit 1001 obtains an error waveform e (t) that is a time change of an error value that is a difference between a control target value and a control achievement value that are represented by the above-described signal.

  Here, the “control achievement value” refers to a value representing the actual position of the head, such as a value representing the head position measured by the head position detection sensor, for example. This control achievement value usually includes a synchronization error synchronized with the rotation of the disk, and is a value that changes with time.

  The error waveform learning unit 1002 is based on the error waveform e (t) obtained by the feedback error calculation unit 1001 and the initial phase and amplitude of each sine wave function stored in the initial phase storage unit 1005 described later. A learning waveform obtained by learning the error waveform e (t) by obtaining the coefficient of each sine wave function representing each component composed of the fundamental wave and each harmonic wave synchronized with the rotation of the disk. Y (t) is obtained.

  The feedforward correction unit 1003 corrects the error waveform e (t) obtained by the feedback error calculation unit 1001 with the learning waveform Y (t) obtained by the error waveform learning unit 1002.

  The feedback control unit 1004 controls the controlled object 2000 based on the error waveform e (t) corrected by the feedforward correction unit 1003.

The initial phase storage unit 1005 stores the initial phase φ _hi and the amplitude of each sine wave function. The initial phase φ _hi and the amplitude are determined in advance based on the amount of time delay for each fundamental wave and each harmonic of the control achievement value with respect to the control target value.

  Furthermore, it demonstrates in detail.

  A sine wave signal representing a disturbance is expressed by weighted synthesis of a sin function and a cos function.

However, the subscript _i is the amplitude f _i of the sinusoidal function represented by the subscript A _i is the subscript _i distinguishes each sinusoidal function together representing a sinusoidal signal, the sinusoidal function represented by the subscript _i frequency a _i and b _i is the coefficient φ _i of the sine wave function represented by the subscript _i , and is the phase of each sine wave signal.

The coefficients a _i and b _i of the sine function and the cosine function are obtained by sequentially integrating the following equations using an error value representing a time change constituting the error waveform e (t).

  However, k is a learning gain.

That is, the coefficients a _i and b _i are acquired with a change in time by a learning rule (or an adaptive rule) having a learning gain k. As a result, a learning waveform Y (t) shown below is output from the error waveform learning unit 1002.

  Here, it is necessary to advance the phase in the high frequency band where the phase delay affects. How much the phase can be advanced is calculated from a complementary sensitivity function. The complementary sensitivity function is a function representing the frequency characteristic of the feedback system, and has a characteristic that the phase lag is small in the low frequency range and the phase lag increases in the high frequency range.

  FIG. 9 is a graph showing an example of the complementary sensitivity function.

  FIG. 9A shows a graph of amplitude (gain) with respect to frequency. FIG. 9B shows a graph of phase with respect to frequency.

As shown in FIG. 9A, the gain of the sine wave signal starts to attenuate when the frequency exceeds 1 KHz. Further, as shown in FIG. 9B, the phase of the sine wave signal has a phase delay from the time when it exceeds the frequency near 100 Hz, and the phase delay increases abruptly when it exceeds the frequency near 1 KHz. Therefore, an amplitude (amplitude correction value) for correcting the amplitude of the sine wave signal is obtained with reference to the graph of FIG. 9A and stored in the initial phase storage unit 1005, and also shown in FIG. 9B. A phase correction value (initial phase φ _hi ) for correcting the phase lag is obtained with reference to the graph, stored in the initial phase storage unit 1005, and stored in the initial phase storage unit 1005 by the error waveform learning unit 1002. The learning waveform Y (t) is obtained based on the amplitude correction value and the phase correction value that have been set and the error value represented by the error waveform e (t) from the feedback error calculation unit 1001. Further, the feedforward correction unit 1003 corrects the error waveform e (t) obtained by the feedback error calculation unit 1001 with the learning waveform Y (t), thereby preventing the influence of the phase delay in the high frequency band. .

  FIG. 10 is a diagram for explaining a feedforward control effect and a phase delay correction effect by learning.

  FIG. 10A shows an example of the power spectrum of the disturbance component of the sine wave signal. When only feedback control is performed without performing feedforward control by learning, the disturbance component is hardly compressed as shown in FIG. Here, as shown in FIG. 10C, the feedforward control by the learning and the correction of the phase delay are started from the error learning start time in the error waveform e (t). Then, the error waveform e (t) converges from this error learning start time, and it can be seen that the disturbance component is almost compressed as shown in FIG.

  FIG. 11 is a diagram showing an error waveform when only feedforward control by learning is performed without correcting the phase delay by the complementary sensitivity function.

As described above, if the frequency band of the target frequency becomes high, the phase delay of the feedback system including the frequency characteristic of the mechanism unit for controlling the position of the head to be controlled may not be ignored. In addition to feed-forward control by learning, phase lag correction by a complementary sensitivity function is also performed. Here, when only the feedforward control by learning is performed without correcting the phase delay by the complementary sensitivity function, the error signal represented by the error waveform e (t) is as shown in FIG. It will diverge. Japanese Patent Application Laid-Open No. H10-228707 proposes a head tracking control device that employs a technique for performing feedforward control by correcting and learning such a phase delay.
International Publication WO2003 / 009290

  Here, the amount of phase lag may deviate more than the expected value due to the case where the mechanical resonance frequency of the mechanism unit for controlling the position of the head to be controlled varies. In this case, the feedforward amount to be sequentially identified by the learning control is not fixed, and it is difficult to perform accurate feedforward control, and conversely, the follow-up performance is deteriorated. Hereinafter, a description will be given with reference to FIGS.

  FIG. 12 is a diagram showing the nominal value of the mechanical resonance frequency of the mechanism unit for controlling the position of the head to be controlled, and the relationship between the error waveform at -10% of the nominal value and the power spectrum of the disturbance component. It is. FIG. 13 is a diagram showing the relationship between the error waveform and the power spectrum of the disturbance component at + 10% of the nominal value of the resonance frequency, and the complementary sensitivity function.

  12A and 12A show an error waveform e (t) at the nominal value of the mechanical resonance frequency of the mechanism unit for controlling the position of the head to be controlled, and the power spectrum of the disturbance component. It is shown. FIGS. 12B and 12B show an error waveform e (t) and a power spectrum of disturbance components at −10% of the nominal value of the resonance frequency.

  Further, FIGS. 13A and 13A show an error waveform e (t) and a power spectrum of disturbance components at + 10% of the nominal value of the resonance frequency. 13 (b) and 13 (c) show the above three resonance frequencies (a resonance frequency of 1 KHz which is a nominal value, a resonance frequency of 0.9 KHz which is −10% of the nominal value, and its nominal value). A graph of amplitude (gain) with respect to (resonant frequency of 1.1 KHz which is + 10%) and a graph of phase with respect to these resonant frequencies are shown. Further, FIG. 13B shows a graph in which the phase portion shown in FIG. 13C is enlarged.

  Here, as shown in FIG. 13B, there is a variation in the phase difference for each sine wave signal N1, N2, N3 having each resonance frequency (resonance frequency of 1 KHz, 0.9 KHz, 1.1 KHz). The phase shift of the sine wave signal N3 having a resonance frequency of 1.1 KHz shifted to the higher side by 10% with respect to the sine wave signal N1 having a resonance frequency of 1 KHz is large. In this case, the amount of phase delay is larger than an assumed value, and an error signal represented by an error waveform e (t) diverges as shown in FIG. If the control target is controlled based on such an error signal, it is difficult to accurately follow the position of the head that accesses the rotating body serving as the storage medium on the track of the rotating body.

  In view of the above circumstances, an object of the present invention is to provide a control device and a control program with improved follow-up performance.

The control device of the present invention that achieves the above object comprises a time change of an error value that is a difference between a control target value of a controlled object in which a synchronization error synchronized with the rotation of a rotating body occurs and a control achieved value of the controlled object In a control device comprising a feedback error calculation unit for obtaining an error waveform, and a feedback control unit for controlling the control object based on the error waveform obtained by the feedback error calculation unit,
Based on the error waveform obtained by the feedback error calculation unit, by determining the coefficient of each sine wave function representing each component of the error waveform consisting of a fundamental wave and harmonics synchronized with the rotation of the rotating body An error waveform learning unit for obtaining a learning waveform obtained by learning the error waveform;
A feedforward correction unit that is arranged between the feedback error calculation unit and the feedback control unit and corrects the error waveform obtained by the feedback error calculation unit with the learning waveform obtained by the error waveform learning unit;
A phase change detection unit for detecting a time change of the phase of each sine wave function for which a coefficient has been obtained by the error waveform learning unit;
Based on the phase change detected by the phase change detection unit, an oscillation detection unit that detects whether the phase change amount of each sine wave function is in an oscillation state exceeding a predetermined threshold;
A phase adjustment unit that adjusts the phase of the sine wave function whose oscillation state is detected by the oscillation detection unit among the sine wave functions is provided.

  In the conventional control device, the amount of the phase delay of the feedback system is assumed in advance, the phase delay is corrected, and the feedforward control by learning is performed, so that the frequency band of the target frequency is increased. However, the tracking performance of tracking control for causing the position of the head to be controlled to follow the track of the rotating body is improved. However, for example, when the amount of phase lag shifts more than the expected value due to variations in the mechanical resonance frequency of the mechanism for controlling the position of the head, the identification is sequentially performed by learning control. Since the feedforward amount is not fixed, it is difficult to perform accurate feedforward control, and it is difficult to improve the follow-up performance.

  In the error waveform learning unit, the control device of the present invention obtains coefficients of each sine wave function representing each component consisting of a fundamental wave and harmonics synchronized with the rotation of the rotating body of the error waveform, and from these coefficients, A phase change detector detects a time change of the phase of each sine wave function. Further, the oscillation detection unit determines that the oscillation is in an oscillating state when the temporal change of the detected phase is abrupt, and the phase adjustment unit updates and corrects the phase with a predetermined value. Here, since the phase obtained from the coefficient is a value between −180 ° and + 180 °, a sudden change point occurs when oscillation occurs. Therefore, using this, it is used as a judgment criterion for detecting whether or not the oscillation state in which the phase change amount of each sine wave function exceeds a predetermined threshold value. By doing so, for example, the amount of phase lag is larger than the expected value due to the case where the mechanical resonance frequency of the mechanism unit for controlling the position of the head to be controlled varies. Even in the case of deviation, the amount of phase delay can be accurately corrected. Therefore, it is possible to provide a control device with improved follow-up performance.

Here, the oscillation detection unit in the control device of the present invention is in an oscillation state in which the phase change amount of each sine wave function exceeds a predetermined threshold based on the phase change detected by the phase change detection unit. And detecting the direction of the phase change of the sine wave function in the oscillation state,
The phase adjustment unit has a phase region in which oscillation stops in accordance with the direction of the phase change of the sine wave function with respect to the phase of the sine wave function detected by the oscillation detection unit among the sine wave functions. It is preferable to increase or decrease in the direction approaching.

  In this way, the phase of the sine wave function can be adjusted efficiently.

  Further, it is also preferable that the rotating body in the control device of the present invention is a disk in which information is stored, and the control target is a position of a head that accesses the disk.

  In this way, the position of the head that accesses the magnetic disk, the optical disk or the like can accurately follow the track of the magnetic disk, the optical disk, or the like.

Furthermore, the control device of the present invention includes an initial phase storage unit that stores the initial phase of each sine wave function,
It is also preferable that the phase adjustment unit adjusts the sine wave function by increasing or decreasing the initial phase of the sine wave function in the oscillation state among the initial phases output from the initial phase storage unit. It is an aspect.

  Thus, the phase can be easily adjusted by storing the initial value and adjusting the sine function by increasing / decreasing the initial value.

  In the control device of the present invention, the initial phase stored in the initial phase storage unit is determined based on the time delay amount for each fundamental wave and each harmonic of the control achievement value with respect to the control target value. It is also preferable.

  Thus, when the initial phase is determined based on the time delay amount, the phase can be adjusted with high accuracy.

  Furthermore, in the control device of the present invention, the above sine wave functions are

However, the subscript _i is the distinguishing suffix f _i each sinusoidal function with each other, the frequency a i _'and b _i' of the sine wave function represented by the subscript _i is the coefficient of the sine wave function represented by the subscript _i.
When represented by
The error waveform learning unit obtains the learning waveform by obtaining the coefficients a _i ′ and b _i ′ of the sine wave functions.

Is what
When the phase of each sine wave signal is φ _i ′,

It is intended to determine the time variation of the phase adjusting unit _'the phase phi _{i seeking'} phase phi _i according, for sine wave function in the oscillation state, the phase phi _hi before phase adjustment predetermined phase value [Delta] [phi _hi It is also preferable to obtain a new phase by increasing or decreasing only.

Here, the phase φ _hi before phase adjustment is, for example, a phase correction value that is a nominal value calculated from a complementary sensitivity function.

In this way, the learning waveform Y (t), the time change of the phase φ _i ′, and the new phase can be obtained with a simple circuit configuration.

Further, the control program of the present invention that achieves the above object is executed in a control computer for controlling a control target in which a synchronization error synchronized with the rotation of the rotating body occurs, and the control computer is
A feedback error calculation unit for obtaining an error waveform composed of a time change of an error value composed of a difference between the control target value of the control object and a control achievement value of the control object;
A feedback control unit for controlling the control object based on the error waveform obtained by the feedback error calculation unit;
Based on the error waveform obtained by the feedback error calculation unit, by determining the coefficient of each sine wave function representing each component of the error waveform consisting of a fundamental wave and harmonics synchronized with the rotation of the rotating body An error waveform learning unit for obtaining a learning waveform obtained by learning the error waveform;
A feedforward correction unit that is arranged between the feedback error calculation unit and the feedback control unit and corrects the error waveform obtained by the feedback error calculation unit with the learning waveform obtained by the error waveform learning unit;
A phase change detection unit for detecting a time change of the phase of each sine wave function for which a coefficient has been obtained by the error waveform learning unit;
Based on the phase change detected by the phase change detection unit, an oscillation detection unit that detects whether the phase change amount of each sine wave function is in an oscillation state exceeding a predetermined threshold;
Of the above sine wave functions, the control device is operated as a control device including a phase adjustment unit that adjusts the phase of the sine wave function whose oscillation state is detected by the oscillation detection unit.

  The control program of the present invention is executed in a control computer for controlling a control target in which a synchronization error is generated in synchronization with the rotation of the rotating body, and causes the control computer to operate as the above-described control device of the present invention. Therefore, the tracking performance of the control device can be improved.

Here, the oscillation detection unit in the control program of the present invention is in an oscillation state in which the phase change amount of each sine wave function exceeds a predetermined threshold based on the phase change detected by the phase change detection unit. And detecting the direction of the phase change of the sine wave function in the oscillation state,
The phase adjustment unit has a phase region in which oscillation stops in accordance with the direction of the phase change of the sine wave function with respect to the phase of the sine wave function detected by the oscillation detection unit among the sine wave functions. It is preferable to increase or decrease in the direction approaching.

  In this way, the phase of the sine wave function can be adjusted efficiently.

  In the control program of the present invention, it is also preferable that the rotating body is a disk storing information, and the control target is a position of a head that accesses the disk.

  In this way, the position of the head that accesses the magnetic disk, the optical disk or the like can accurately follow the track of the magnetic disk, the optical disk, or the like.

Furthermore, in the control program of the present invention, an initial phase storage unit for storing the initial phase of each sine wave function is provided,
It is also preferable that the phase adjustment unit adjusts the sine wave function by increasing or decreasing the initial phase of the sine wave function in the oscillation state among the initial phases output from the initial phase storage unit. It is an aspect.

  Thus, the phase can be easily adjusted by storing the initial value and adjusting the sine function by increasing / decreasing the initial value.

  In the control program of the present invention, the initial phase stored in the initial phase storage unit is determined based on a time delay amount for each fundamental wave and each harmonic of the control achievement value with respect to the control target value. It is also preferred that

  Thus, when the initial phase is determined based on the time delay amount, the phase can be adjusted with high accuracy.

  Furthermore, in the control program of the present invention, each sine wave function is

However, the subscript _i is the distinguishing suffix f _i each sinusoidal function with each other, the frequency a i _'and b _i' of the sine wave function represented by the subscript _i is the coefficient of the sine wave function represented by the subscript _i.
When represented by
The error waveform learning unit obtains the learning waveform by obtaining the coefficients a _i ′ and b _i ′ of the sine wave functions.

Is what
When the phase of each sine wave signal is φ _i ′,

It is intended to determine the time variation of the phase adjusting unit _'the phase phi _{i seeking'} phase phi _i according, for sine wave function in the oscillation state, the phase phi _hi before phase adjustment predetermined phase value [Delta] [phi _hi It is also preferable to obtain a new phase by increasing or decreasing only.

In this way, the learning waveform Y (t), the time change of the phase φ _i ′, and the new phase can be obtained with a simple control program.

  According to the present invention, it is possible to provide a control device and a control program with improved follow-up performance.

  Hereinafter, embodiments of the present invention will be described.

  FIG. 1 is a perspective view of a magneto-optical disk apparatus in which an embodiment of the control apparatus of the present invention is incorporated, and FIG. 2 is a cross-sectional view of the magneto-optical disk apparatus shown in FIG.

  The magneto-optical disk apparatus 1 shown in FIGS. 1 and 2 is provided with a spindle motor 10. An MO (magneto-optical) cartridge is inserted into the hub of the spindle motor 10 through an inlet door (not shown), so that the MO medium 2 in the MO cartridge (corresponding to an example of a rotating body according to the present invention). ) Is mounted on the hub of the rotating shaft of the spindle motor 10.

  Further, the magneto-optical disk device 1 is provided with a carriage 21, an objective lens 22, a fixed optical system 23, and a rising mirror 24 that constitute a head mechanism. Further, the magneto-optical disk device 1 is provided with a VCM (Voice Coil Motor) 30, a focus actuator 40, and a guide rail 50.

  The carriage 21 is provided below the MO medium 2 of the loaded MO cartridge, and is freely moved in a direction crossing the track of the MO medium 2 by the VCM 30.

  The objective lens 22 is mounted on the upper part of the carriage 21 and is controlled to move in the optical axis direction by the focus actuator 40, and the light beam is emitted in the radial direction across the track of the MO medium 2 by linear driving of the carriage 21 by the VCM 30. Moving. The objective lens 22 receives a beam from a laser diode provided in the fixed optical system 23 via a rising mirror 24 and forms an image of a beam spot on the medium surface of the MO medium 2.

  The fixed-side magnet 31 and the yoke 32 constituting the VCM 30 are provided on the carriage 21. The carriage 21 is supported by two guide rails 50 that are fixedly arranged by sliding bearings, and the VCM 30 performs seek control, which is coarse control for moving the light beam to an arbitrary track position, and the light beam at the seek track position. Movement is performed to control both tracking control, which is fine control to follow the track center.

  FIG. 3 is a block diagram of an electric circuit of the magneto-optical disk apparatus shown in FIGS.

  The magneto-optical disk apparatus 1 shown in FIG. 3 includes a ROM 101, a CPU 102, a RAM 103, a USB communication unit 104, a magneto-optical medium I / F unit 105, and a mechanism control unit 106.

  The ROM 101 stores a program for controlling the entire magneto-optical disk device 1. The ROM 101 also stores a program incorporated in the magneto-optical disk device 1 for realizing an embodiment of a control device of the present invention described later.

  The CPU 102 controls the operation of the entire magneto-optical disk device 1 according to the procedure of the program stored in the ROM 101.

  The RAM 103 is provided with a work area for the CPU 102 to execute various processes.

  The USB communication unit 104 outputs information stored in the MO medium 2 to a personal computer or the like equipped with a USB terminal via the CPU 102 and the magneto-optical medium I / F unit 105, or such a personal computer. Information from a computer or the like is stored in the MO medium 2.

  The magneto-optical medium I / F unit 105 performs photoelectric conversion and magnetic conversion in exchanging information between the MO medium 2 and the CPU 102.

  The mechanism control unit 106 controls the head mechanism and the like described above.

  FIG. 4 is a diagram showing the structure of a control program for realizing an embodiment of the control device of the present invention incorporated in the magneto-optical disk device shown in FIG.

  The control program 200 shown in FIG. 4 is stored in the ROM 101 shown in FIG. 3, and this control program 200 includes a feedback error calculation routine unit 201, a feedback control routine unit 202, an error waveform learning routine unit 203, and a feedforward correction routine. Section 204, phase change detection routine section 205, oscillation detection routine section 206, and phase adjustment routine section 207. Details of each part of the control program 200 will be described together with the operation of each part of the embodiment of the control device of the present invention.

  FIG. 5 is a diagram showing the configuration of an embodiment of the control apparatus of the present invention incorporated in the magneto-optical disk apparatus shown in FIG.

  The control device 300 shown in FIG. 5 is a control device as a function configured by the hardware shown in FIG. 3 and the control program shown in FIG. 4 executed by the CPU 102 in FIG.

  Here, each block configuring the control device 300 illustrated in FIG. 5 is described as configured by a combination of the hardware illustrated in FIG. 3 and the control program illustrated in FIG. 4, but each block illustrated in FIG. The configuration of some or all of the blocks may be configured by a DSP (Digital Signal Processor).

  The control device 300 illustrated in FIG. 5 includes a feedback error calculation unit 301 and a feedback control unit 302.

  The feedback error calculation unit 301 operates under the action of the program of the feedback error calculation routine unit 201 shown in FIG. 4 and controls the control target value of the control target 60 that generates a synchronization error synchronized with the rotation of the MO medium 2 and its control. An error waveform e (t) that is a time change of an error value that is a difference from the control achievement value of the target 60 is obtained. The control target 60 here is the position of the head that accesses the MO medium 2. The control achievement value is a value representing the actual position of the head. Specifically, the control achievement value includes a synchronization error synchronized with the rotation of the MO medium 2 and changes with time.

  The feedback control unit 302 operates under the action of the program of the feedback control routine unit 202 shown in FIG. 4 and controls the control target based on the error waveform e (t) obtained by the feedback error calculation unit 301.

  Further, the control device 300 includes an error waveform learning unit 303, a feedforward correction unit 304, a phase change detection unit 305, an oscillation detection unit 306, and a phase adjustment unit 307.

  The error waveform learning unit 303 operates under the action of the program of the error waveform learning routine unit 203 shown in FIG. 4, and based on the error waveform e (t) obtained by the feedback error calculation unit 301, the error waveform e A learning waveform Y () in which the error waveform e (t) is learned by obtaining the coefficient of each sine wave function representing each component composed of the fundamental wave and each harmonic in synchronization with the rotation of the MO medium 2 in (t). t).

  The feedforward correction unit 304 is disposed between the feedback error calculation unit 301 and the feedback control unit 302, operates under the action of the program of the feedforward correction routine unit 204 shown in FIG. The error waveform e (t) obtained in 301 is corrected with the learned waveform Y (t) obtained in the error waveform learning unit 303.

  The phase change detection unit 305 operates under the action of the program of the phase change detection routine unit 205 shown in FIG. 4, and detects the time change of the phase of each sine wave function whose coefficient is obtained by the error waveform learning unit 303. .

  The oscillation detection unit 306 operates under the action of the program of the oscillation detection routine unit 206 shown in FIG. 4, and the phase change amount of each sine wave function is determined based on the phase change detected by the phase change detection unit 305. It is detected whether or not the oscillation state exceeds a predetermined threshold value. Specifically, the oscillation detection unit 306 determines whether or not the phase change amount of each sine wave function exceeds the predetermined threshold based on the phase change detected by the phase change detection unit 305. While detecting, the direction of the phase change of the sine wave function in an oscillation state is detected.

  The phase adjustment unit 307 operates under the action of the program of the phase adjustment routine unit 207 shown in FIG. 4, and among the above sine wave functions, the phase of the sine wave function whose oscillation state is detected by the oscillation detection unit 306 is obtained. adjust. Specifically, the phase adjustment unit 307 oscillates the phase of the sine wave function whose oscillation state is detected by the oscillation detection unit 306 among the sine wave functions according to the direction of the phase change of the sine wave function. Increases or decreases in the direction approaching the phase region where is stopped.

Further, the control device 300 includes an initial phase storage unit 308 that stores the initial phase φ _hi of each sine wave function, and the phase adjustment unit 307 described above receives the initial phase output from the initial phase storage unit 308. of the phase phi _hi, it adjusts its sinusoidal function by increasing or decreasing the initial phase phi _hi for sinusoidal function in the oscillation state.

Here, the initial phase φ _hi stored in the initial phase storage unit 308 is determined on the basis of the time delay amount for each fundamental wave and each harmonic of the control achievement value with respect to the control target value. is there. Furthermore, it demonstrates in detail.

  Each sine wave function is

However, the subscript _i is the distinguishing suffix f _i each sinusoidal function with each other, the frequency a i _'and b _i' of the sine wave function represented by the subscript _i is the coefficient of the sine wave function represented by the subscript _i.
When represented by
The error waveform learning unit 303 obtains the learning waveform by obtaining the coefficients a _i ′ and b _i ′ of each sine wave function.

Is what you want.

Further, the phase change detection unit 305 has a phase of each sine wave signal as φ _i ′,

_'Searching for the phase phi _i' phase phi _i according seek time variation of.

Further, the phase adjustment unit 307 obtains a new phase by increasing or decreasing the phase φ _hi before the phase adjustment by a predetermined phase value Δφ _hi for the sine wave function in the oscillation state.

  FIG. 6 is a diagram illustrating waveforms of respective units in the conventional control device and the control device of the present embodiment.

FIG. 6A shows sin coefficients a _i and cos coefficients b _{i of} a sine wave function in a conventional control device. FIG. 6B shows the phase φ _i obtained from the sin coefficient a _i and the cos coefficient b _i of the sine wave signal in the conventional control device. Further, FIG. 6C shows an error waveform e (t) in the conventional control device.

When the mechanical resonance frequency of the mechanism unit for controlling the position of the head that is the controlled object 60 varies, the amount of phase delay deviates more than the expected value, and the learning control sequentially The feedforward amount to be identified is not fixed, and the coefficients a _i and b _i of the sine wave function gradually diverge as shown in FIG. For this reason, it is difficult to perform accurate feedforward control, and an error signal represented by an error waveform e (t) diverges as shown in FIG. If the control target is controlled based on such an error signal, it is difficult to accurately follow the position of the head that accesses the rotating body serving as the storage medium on the track of the rotating body.

On the other hand, FIG. 6A shows sin coefficients a _i ′ and cos coefficients b _i ′ of the sine wave function in the present embodiment. FIG. 6B shows the phase φ _i ′ obtained from the sin coefficient a _i ′ and the cos coefficient b _i ′ of the sine wave signal in the present embodiment. Further, in FIG. 6 (C), in this embodiment, there is shown a newly obtained phase phi _hi by increasing or decreasing the phase phi _hi before phase adjustment by a predetermined phase value [Delta] [phi _hi. FIG. 6D shows an error waveform e (t) in the present embodiment.

In the present embodiment, the error waveform learning unit 303 obtains sin coefficients a _i ′ and cos coefficients b _i ′, which are coefficients of learning shown in FIG. Next, the phase change detecting unit 305 detects the time change of the phase of the sine wave signal from these coefficients a _i ′ b _i ′. Further, as shown in FIG. 6B, the oscillation detection unit 306 considers that the detected phase is in an oscillating state if the change in time is abrupt, and the phase adjustment unit 307 sets the phase to a predetermined value. Update and correct. Here, since the phase φ _i ′ obtained from the sin coefficient a _i ′ and the cos coefficient b _i ′ is a value of −180 ° to + 180 °, an abrupt change point occurs when oscillating. Therefore, using this fact, as a criterion it, initial phase correction value phi _hi: Update _(before phase adjustment phase phi _hi phase correction value is a nominal value which is calculated from the complementary sensitivity function). As a result, the phase φ _{hi obtained} by subtracting the phase φ _hi before phase adjustment by a predetermined phase value Δφ _hi shown in FIG. 6C is obtained.

It should be noted that the case where the phase φ _i ′ is largely deviated from a certain reference value may be used as a determination criterion. Here, the example of the phase φ _i ′ obtained from the coefficients a _i ′ and b _i ′ has been described, but the phase φ _i obtained from the original coefficients a _i and b _i may be used as a criterion. Further, b _i / a _i or b _i ′ / a _i ′ itself may be used as a criterion.

Further details will be described. Here, in obtaining the phase value Δφ _hi , the difference (φ _i ′ (z) −φ _i ′ (z) between the current phase value φ _i ′ (z) and the previous phase value φ _i ′ (z−1). -1)). Here, the predetermined threshold is set to less than −180 °, and the obtained phase value Δφ _{hi is set} to −50 °. Further, an initial phase correction value φ _{hi is set} to 297 °, and a phase φ _{hi of} 247 ° obtained by subtracting 50 ° from this 297 ° is obtained.

φ _hi = φ _hi −Δφ _hi = 297 ° −50 ° = 247 °
By doing so, the error signal represented by the error waveform e (t) can be converged as shown in FIG. In the present embodiment, since the control target is controlled based on such an error signal, the tracking control tracking performance can be improved. Although the example in which the predetermined threshold value is less than −180 ° has been described here, the predetermined threshold value may exceed + 180 °. In this case, the phase value Δφ _hi that is a correction value is a positive value. You can do it.

  FIG. 7 is a diagram showing the allowable range of the phase with respect to the mechanical resonance frequency of the mechanism unit for controlling the position of the head to be controlled.

  In FIG. 7, the error signal can be converged so that the point corresponding to the case where the mechanical resonance frequency of the mechanism unit for controlling the position of the head to be controlled is shifted by −10% is the center. The phase tolerance is shown.

Here, as indicated by the black circles in FIG. 7, when the mechanical resonance frequency of the mechanism for controlling the position of the head to be controlled is shifted by + 10%, the error signal is exceeded because the phase exceeds the allowable range. Cannot converge. Therefore, the error signal can be converged by correcting the phase value Δφ _hi by about −50 ° from the phase value indicated by the black circle. In addition, since there is an allowable range by learning to some extent, it is not necessary to limit to −50 °.

Further, for example, when the phase value Δφ _{hi is set} to −10 ° and the error signal does not converge at the first time, correction may be performed until the error signal converges, for example, to −10 °.

  In the present embodiment, the position of the head that accesses the MO medium 2 has been described as an example of the control target according to the present invention. However, the present invention is not limited to this, and the control target according to the present invention is a rotation target. As long as there is a possibility that a synchronization error synchronized with the rotation of the body may occur, the control achievement value referred to in the present invention is a value representing the control result of the control object, and is limited to the head position. Any value may be used as long as it includes a synchronization error synchronized with the rotation of the rotating body and changes with time.

  Hereinafter, various embodiments of the present invention will be additionally described.

(Supplementary Note 1) A feedback error calculation unit that obtains an error waveform that is a time change of an error value that is a difference between a control target value of a control target that generates a synchronization error synchronized with the rotation of the rotating body and a control achievement value of the control target And a feedback control unit that controls the control object based on the error waveform obtained by the feedback error calculation unit,
Based on the error waveform obtained by the feedback error calculation unit, by obtaining the coefficient of each sine wave function representing each component of the error waveform consisting of a fundamental wave and harmonics synchronized with the rotation of the rotating body An error waveform learning unit for obtaining a learning waveform obtained by learning the error waveform;
A feedforward correction unit that is arranged between the feedback error calculation unit and the feedback control unit and corrects an error waveform obtained by the feedback error calculation unit with a learning waveform obtained by the error waveform learning unit;
A phase change detection unit for detecting a time change of the phase of each sine wave function for which a coefficient is obtained by the error waveform learning unit;
Based on the phase change detected by the phase change detection unit, an oscillation detection unit that detects whether the phase change amount of each sine wave function is in an oscillation state exceeding a predetermined threshold;
A control apparatus comprising: a phase adjusting unit that adjusts a phase of a sine wave function whose oscillation state is detected by the oscillation detecting unit among the sine wave functions.

(Additional remark 2) The said oscillation detection part detects whether the phase variation | change_quantity of each said sine wave function exceeds the predetermined | prescribed threshold value based on the phase change detected by the said phase change detection part. And detecting the direction of phase change of the sine wave function in the oscillation state,
The phase adjustment unit is configured to change a phase of the sine wave function whose oscillation state is detected by the oscillation detection unit among the sine wave functions to a phase region where the oscillation stops according to a phase change direction of the sine wave function. The control device according to appendix 1, wherein the control device increases or decreases in a direction approaching.

  (Supplementary note 3) The control device according to supplementary note 1, wherein the rotating body is a disk storing information, and the control target is a position of a head that accesses the disk.

(Supplementary Note 4) An initial phase storage unit that stores an initial phase of each sine wave function is provided,
The phase adjustment unit adjusts the sine wave function by increasing / decreasing an initial phase of the sine wave function in an oscillation state among the initial phases output from the initial phase storage unit. The control device according to appendix 1.

  (Additional remark 5) The initial phase memorize | stored in the said initial phase memory | storage part is determined based on the time delay amount for every said fundamental wave and each said harmonic of the said control achievement value with respect to the said control target value. The control apparatus according to supplementary note 1, wherein:

  (Supplementary Note 6) Each sine wave function is

However, the subscript _i is the distinguishing suffix f _i each sinusoidal function with each other, the frequency a i _'and b _i' of the sine wave function represented by the subscript _i is the coefficient of the sine wave function represented by the subscript _i.
When represented by
The error waveform learning unit obtains the learning waveform by obtaining coefficients a _i ′ and b _i ′ of the sine wave functions.

Is what
The phase change detection unit has a phase of each sine wave signal as φ _i ′,

Phase _'seeking the phase phi _i' phi _i is intended to determine the time variation of the phase adjustment unit in accordance with, for sine wave function in the oscillation state, the phase phi _hi before phase adjustment predetermined phase value [Delta] [phi _hi The control apparatus according to appendix 1, wherein a new phase is obtained by increasing or decreasing only.

(Supplementary Note 7) The control computer is executed in a control computer for controlling a control target in which a synchronization error occurs in synchronization with the rotation of the rotating body.
A feedback error calculation unit for obtaining an error waveform composed of a time change of an error value composed of a difference between a control target value of the control object and a control achievement value of the control object;
A feedback control unit that controls the control object based on the error waveform obtained by the feedback error calculation unit;
Based on the error waveform obtained by the feedback error calculation unit, by obtaining the coefficient of each sine wave function representing each component of the error waveform consisting of a fundamental wave and harmonics synchronized with the rotation of the rotating body An error waveform learning unit for obtaining a learning waveform obtained by learning the error waveform;
A feedforward correction unit that is arranged between the feedback error calculation unit and the feedback control unit and corrects an error waveform obtained by the feedback error calculation unit with a learning waveform obtained by the error waveform learning unit;
A phase change detection unit for detecting a time change of the phase of each sine wave function for which a coefficient is obtained by the error waveform learning unit;
Based on the phase change detected by the phase change detection unit, an oscillation detection unit that detects whether the phase change amount of each sine wave function is in an oscillation state exceeding a predetermined threshold;
A control program that operates as a control device including a phase adjustment unit that adjusts a phase of a sine wave function whose oscillation state is detected by the oscillation detection unit among the sine wave functions.

(Additional remark 8) The said oscillation detection part detects whether the phase change amount of each said sine wave function has exceeded the predetermined | prescribed threshold value based on the phase change detected by the said phase change detection part. And detecting the direction of phase change of the sine wave function in the oscillation state,
The phase adjustment unit is configured to change a phase of the sine wave function whose oscillation state is detected by the oscillation detection unit among the sine wave functions to a phase region where the oscillation stops according to a phase change direction of the sine wave function. The control program according to appendix 7, wherein the control program increases or decreases in a direction approaching.

  (Supplementary note 9) The control program according to supplementary note 7, wherein the rotating body is a disk storing information, and the control target is a position of a head that accesses the disk.

(Supplementary Note 10) An initial phase storage unit that stores an initial phase of each sine wave function is provided,
The phase adjusting unit adjusts the sine wave function by increasing / decreasing the initial phase of the sine wave function in the oscillation state among the initial phases output from the initial phase storage unit. The control program according to appendix 7, characterized by:

  (Additional remark 11) The initial phase memorize | stored in the said initial phase memory | storage part is determined based on the time delay amount for every said fundamental wave and each said harmonic of the said control achievement value with respect to the said control target value. The control program according to appendix 7, wherein

  (Supplementary note 12) Each sine wave function is

However, the subscript _i is the distinguishing suffix f _i each sinusoidal function with each other, the frequency a i _'and b _i' of the sine wave function represented by the subscript _i is the coefficient of the sine wave function represented by the subscript _i.
When represented by
The error waveform learning unit obtains the learning waveform by obtaining coefficients a _i ′ and b _i ′ of the sine wave functions.

Is what
The phase change detection unit has a phase of each sine wave signal as φ _i ′,

Phase _'seeking the phase phi _i' phi _i is intended to determine the time variation of the phase adjustment unit in accordance with, for sine wave function in the oscillation state, the phase phi _hi before phase adjustment predetermined phase value [Delta] [phi _hi The control program according to appendix 7, wherein a new phase is obtained by increasing or decreasing only.

1 is a perspective view of a magneto-optical disk device in which an embodiment of a control device of the present invention is incorporated. FIG. It is sectional drawing of the magneto-optical disc apparatus shown in FIG. FIG. 3 is a block diagram of an electric circuit of the magneto-optical disk apparatus shown in FIGS. 1 and 2. It is a figure which shows the structure of the control program for implement | achieving one Embodiment of the control apparatus of this invention incorporated in the magneto-optical disk apparatus shown in FIG. It is a figure which shows the structure of one Embodiment of the control apparatus of this invention incorporated in the magneto-optical disk apparatus shown in FIG. It is a figure which shows the waveform of each part in the conventional control apparatus and the control apparatus of this embodiment. It is a figure which shows the allowable range of the phase with respect to the mechanical resonance frequency of the mechanism part for controlling the position of the head which is a control object. It is a figure which shows the structure of the conventional control apparatus which correct | amends phase delay and performs feedforward control by a learning control system. It is a graph which shows an example of a complementary sensitivity function. It is a figure for demonstrating the feedforward control effect and the correction effect of a phase delay by learning. It is a figure which shows an error waveform at the time of performing only feedforward control by learning, without correcting the phase delay by a complementary sensitivity function. It is a figure which shows the relationship between the error waveform in -10% of the nominal value of the mechanical resonance frequency of the mechanism part for controlling the position of the head which is a control object, and the nominal value, and the power spectrum of a disturbance component. It is a figure which shows the relationship between the error waveform in + 10% of the nominal value of a resonant frequency, and the power spectrum of a disturbance component, and a complementary sensitivity function.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Magneto-optical disk apparatus 2 MO medium 10 Spindle motor 21 Carriage 22 Objective lens 23 Fixed optical system 24 Rising mirror 30 VCM
40 Focus actuator 50 Guide rail 60 Control target 101 ROM
102 CPU
103 RAM
104 USB communication unit 105 Magneto-optical medium I / F unit 106 Mechanism control unit 200 Control program 201 Feedback error calculation routine unit 202 Feedback control routine unit 203 Error waveform learning routine unit 204 Feed forward correction routine unit 205 Phase change detection routine unit 206 Oscillation Detection routine unit 207 Phase adjustment routine unit 300 Control device 301 Feedback error calculation unit 302 Feedback control unit 303 Error waveform learning unit 304 Feedforward correction unit 305 Phase change detection unit 306 Oscillation detection unit 307 Phase adjustment unit 308 Initial phase storage unit

Claims (5)

A feedback error calculation unit for obtaining an error waveform composed of a time change of an error value consisting of a difference between a control target value of a controlled object in which a synchronization error synchronized with the rotation of the rotating body occurs and a control achievement value of the controlled object; and the feedback In a control device including a feedback control unit that controls the control target based on an error waveform obtained by an error calculation unit,
Based on the error waveform obtained by the feedback error calculation unit, by obtaining the coefficient of each sine wave function representing each component of the error waveform consisting of a fundamental wave and harmonics synchronized with the rotation of the rotating body An error waveform learning unit for obtaining a learning waveform obtained by learning the error waveform;
A feedforward correction unit that is arranged between the feedback error calculation unit and the feedback control unit and corrects an error waveform obtained by the feedback error calculation unit with a learning waveform obtained by the error waveform learning unit;
A phase change detection unit for detecting a time change of the phase of each sine wave function for which a coefficient is obtained by the error waveform learning unit;
Based on the phase change detected by the phase change detection unit, an oscillation detection unit that detects whether the phase change amount of each sine wave function is in an oscillation state exceeding a predetermined threshold;
A control apparatus comprising: a phase adjusting unit that adjusts a phase of a sine wave function whose oscillation state is detected by the oscillation detecting unit among the sine wave functions. The oscillation detection unit detects whether the phase change amount of each sine wave function is in an oscillation state exceeding a predetermined threshold based on the phase change detected by the phase change detection unit, and oscillates. Detecting the direction of phase change of a sinusoidal function in a state,
The phase adjustment unit is configured to change a phase of the sine wave function whose oscillation state is detected by the oscillation detection unit among the sine wave functions to a phase region where the oscillation stops according to a phase change direction of the sine wave function. The control device according to claim 1, wherein the control device increases or decreases in a direction approaching.   The control apparatus according to claim 1, wherein the rotating body is a disk storing information, and the control target is a position of a head that accesses the disk. An initial phase storage unit for storing an initial phase of each sine wave function;
The phase adjustment unit adjusts the sine wave function by increasing / decreasing an initial phase of the sine wave function in an oscillation state among the initial phases output from the initial phase storage unit. The control device according to claim 1. The control computer is executed in a control computer for controlling a control target in which a synchronization error is generated in synchronization with the rotation of the rotating body.
A feedback error calculation unit for obtaining an error waveform composed of a time change of an error value composed of a difference between a control target value of the control object and a control achievement value of the control object;
A feedback control unit that controls the control object based on the error waveform obtained by the feedback error calculation unit;
Based on the error waveform obtained by the feedback error calculation unit, by obtaining the coefficient of each sine wave function representing each component of the error waveform consisting of a fundamental wave and harmonics synchronized with the rotation of the rotating body An error waveform learning unit for obtaining a learning waveform obtained by learning the error waveform;
A feedforward correction unit that is arranged between the feedback error calculation unit and the feedback control unit and corrects an error waveform obtained by the feedback error calculation unit with a learning waveform obtained by the error waveform learning unit;
A phase change detection unit for detecting a time change of the phase of each sine wave function for which a coefficient is obtained by the error waveform learning unit;
Based on the phase change detected by the phase change detection unit, an oscillation detection unit that detects whether the phase change amount of each sine wave function is in an oscillation state exceeding a predetermined threshold;
A control program that operates as a control device including a phase adjustment unit that adjusts a phase of a sine wave function whose oscillation state is detected by the oscillation detection unit among the sine wave functions.

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