JP2009245542A - Information processing device and method, program, and recording/reproducing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To more easily obtain an appropriate value of a control parameter of a control system for controlling an operation by directing the angle or position of a control target to a target value. <P>SOLUTION: A control parameter generation part 124 determines a temporary value of a control parameter of a phase progress delay filter from a process frequency f<SB>x</SB>of open loop frequency characteristics, sets a controller gain K<SB>p</SB>based on the open loop frequency characteristics so that a zero cross frequency matches a target f<SB>x</SB>, and causes a user to determine a gain of a low-pass booster so that condition stabilization gain margin is 12 dB, and to makes overall fine adjustment by changing a phase delay frequency so that a phase margin is 32° or more. This is applicable to, for example, a recording/reproducing device. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an information processing apparatus and method, a program, and a recording / reproducing apparatus. In particular, the present invention more easily finds an appropriate value of a control parameter of a control system that controls the operation of an angle or position of a control target toward a target value. The present invention relates to an information processing apparatus and method, a program, and a recording / reproducing apparatus.

  2. Description of the Related Art Conventionally, in an optical disc recording / reproducing apparatus that records data on an optical disc that is a recording medium or reads data recorded on an optical disc, servo control is performed for laser focusing position control of an optical pickup. Also in a magnetic disk recording / reproducing apparatus using a recording medium as a magnetic disk, servo control is performed for magnetic head position control. These servo controls are realized by subjecting an error signal detected by the optical pickup or magnetic head to a control operation by a servo controller, and using this as a drive signal to drive the position of the optical pickup or magnetic head by an electromagnetic actuator.

  FIG. 1 is a diagram showing a control model of such a conventional servo controller. As shown in FIG. 1, the servo controller has a low-frequency booster 1 and a phase advance / lag filter 2 connected in series.

The low frequency booster 1 increases the low frequency gain and suppresses position disturbances such as circumferential blurring and eccentricity. As shown in FIG. 1, the low-frequency booster 1 is represented by the following formula (1) using a constant a _s , a constant c _s , and a constant K _ps .

Low frequency booster = K _ps × (s−c _s ) / (s−a _s ) (1)

The constant a _s indicates the lower limit frequency of the emphasis characteristic of the low frequency component. The constant c _s indicates the upper limit frequency of the emphasis characteristic of the low frequency component. The constant K _ps indicates the gain of the low frequency booster 1.

Further, the phase advance / delay filter 2 controls the high frequency phase to stabilize. As shown in FIG. 1, the phase advance / delay filter 2 is expressed by the following equation (2) using a constant b _s and a constant d _s .

Phase advance / delay filter = (s−d _s ) / (s−b _s ) (2)

The constant b _s indicates a phase delay frequency at a high frequency. The constant d _s indicates the phase advance frequency at a high frequency.

For such a servo controller, for example, the control parameters are adjusted specifically in the following procedure. First, the phase lead-lag filter 2, the phase lead frequency (-d _s / 2π) is set to 1/3 times the zero-cross frequency f _x. Further, the phase lag frequency (-b _s / 2π) is, by advancing the high-frequency phase to stabilize the servo control, is set to three times the zero-crossing frequency f _x. Further, for the low-frequency booster 1, the low-frequency boost frequency (−c _s / 2π) is set high enough not to significantly affect the high-frequency phase in order to suppress the position disturbance. Then, based on the open-loop frequency characteristic, the zero-cross frequency gain K _ps is set to match the zero-cross frequency f _x to the target. Fine adjustment is performed based on these control parameters, and the final value of each control parameter is determined. At this time, as the servo band the larger the value of the zero-crossing frequency f _x is large good characteristics can be obtained.

FIG. 2 is a graph showing an example of an open loop frequency characteristic of such a servo controller. The zero cross frequency is a frequency at which the gain of the open loop frequency characteristic becomes 0 dB, as indicated by an arrow 11 in FIG. Further, double-headed arrow 12 represents the gain margin conditions stable, double-headed arrow 13 on the zero-crossing frequency f _x indicates the phase margin.

By the way, as a method for setting the control parameter of the servo controller as described above, there is, for example, a method of increasing the low-frequency gain using the controller zero as a complex number (see, for example, Patent Document 1). Conventionally, the two controller zeros determined by the low frequency boost frequency (−c _s / 2π) and the phase advance frequency (−d _s / 2π) of the phase advance / lag filter are automatically set to real numbers. In the method described in Patent Document 1, two controller zeros can be set to conjugate complex zeros, and the low-frequency gain is increased to enhance the position disturbance suppression effect.

  Further, there has been a method of calculating a controller zero, a controller pole, and a controller gain when the servo controller is realized by a digital control system by a pole arrangement method (see, for example, Patent Document 2). In this method, the dead time element included in the control system is set so as to approximate an integer multiple of the sampling frequency, and the pole placement equation is derived on that, so a more accurate pole placement is possible even with a digital controller. become. In addition, when the time delay element is not an integral multiple of the sampling frequency, there has been a method of performing pole placement by approximating the time delay element with a first-order delay element (see, for example, Patent Document 3).

Furthermore, there is a technique to easily determine the control parameters to the target controller of the secondary filter consists zero cross frequency f _x (e.g., see Patent Document 4).

These approaches, even zero crossing frequency f _x is the same, low-frequency gain is high, it is possible to realize a strong good control more disturbance, also regardless of the trial and error by the pole assignment operation the control parameter Can be calculated.

JP 2006-012284 A JP 2006-023847 A JP 2006-331030 A JP 2007-072898 A

However, in the methods described in Patent Document 2 and Patent Document 3, for example, the user first designates a closed loop pole of the control system, and then calculates a control parameter using a control parameter calculation formula based on a pole placement calculation. the case, the concept of the closed-loop poles unfamiliar generally about zero cross frequency f _x of the above, there are cases where intuitively difficult to understand. Furthermore, it is necessary to use different control parameter calculation formulas depending on the size of the time delay element, and it is necessary to measure the time delay element by some method to determine which formula is used, which requires complicated work. There was a case.

In the method described in Patent Document 4, can be easily determine the control parameters to the target controller of the secondary filter consists zero cross frequency f _x, for example, the controller having an intermediate of the low-frequency gain of the conventional control In some cases, it was not possible to cope with the situation. That is, in the method described in Patent Document 4, it is possible to obtain a control parameter that realizes the highest low-frequency gain, which is equivalent to arranging four poles by the method of performing the pole arrangement described in Patent Document 2. Although possible, for example, it may be difficult to design a control parameter in which only the low-frequency gain is reduced without changing the phase margin.

  The present invention is intended to solve such a problem, and by using an intuitively easy-to-understand control parameter, a desired low-frequency gain can be more easily realized with a common algorithm regardless of the size of the dead time element. It is something that can be done.

  One aspect of the present invention includes a low-frequency emphasis calculating unit that performs low-frequency emphasis of a control system, and a phase advance / delay calculating unit that realizes a phase advance / delay characteristic of the control system, and is connected to each other in parallel From the zero cross frequency of the open loop frequency characteristic of the control system, the control calculation means for calculating the control output for controlling the operation of the angle or position of the control target toward the target value by the area enhancement calculating means and the phase advance / delay calculating means Control parameter calculation means for calculating a zero point and a pole of the phase lead / lag characteristic as a control parameter, and the control calculation means includes a zero point of the phase lead / lag characteristic calculated as a control parameter by the control parameter calculation means and An information processing apparatus that calculates the control output using a pole.

  The control parameter calculation means can calculate the zero point of the phase advance / lag characteristic by multiplying the zero cross frequency, the phase advance frequency ratio, and a predetermined coefficient.

  The range of the value of the phase advance frequency ratio may be 0.43 to 0.48.

  The control parameter calculation means can calculate the pole of the phase lead / lag characteristic by multiplying the zero cross frequency, the phase lag frequency ratio, and a predetermined coefficient.

  The range of the value of the phase lag frequency ratio may be 3 to 16.

  The control parameter calculation means can discretize the cutoff frequency of the low-frequency emphasis calculation means and the zero point and pole of the phase advance / lag characteristic according to the sampling frequency.

  According to another aspect of the present invention, the control parameter calculation unit is connected in parallel to each other, and the low frequency emphasis calculation unit that performs low frequency emphasis of the control system, and the phase that realizes the phase lead / lag characteristic of the control system The zero point and pole of the phase advance / delay characteristic of the advance / delay calculation unit are calculated from the zero cross frequency of the open loop frequency characteristic of the control system as a control parameter, and the control calculation means calculates the phase advance calculated as the control parameter. Using the zero point and pole of the delay characteristic, the low-frequency emphasis calculation unit and the phase advance / delay calculation unit connected in parallel with each other calculate a control output for controlling the operation of the angle or position of the control target toward the target value. Information processing method.

  One aspect of the present invention further includes a low-frequency emphasis calculation unit that performs low-frequency emphasis of a control system, connected in parallel to each other to process information, and a phase advance / delay characteristic of the control system. Control parameter calculation means for calculating the zero point and the pole of the phase advance / delay characteristic of the phase advance / delay calculation unit to be realized from the zero cross frequency of the open loop frequency characteristic of the control system, the control parameter calculated as the control parameter Control output for controlling the angle or position of the control target toward the target value by the low-frequency emphasis calculation unit and the phase advance / delay calculation unit connected in parallel to each other using the zero point and the pole of the phase advance / delay characteristic It is a program for functioning as a control calculation means for calculating.

  Another aspect of the present invention is a recording / reproducing element for writing / reading data to / from a disk-shaped recording medium, and driving the recording / reproducing element in a horizontal direction or a vertical direction with respect to a recording surface of the disk-shaped recording medium. Driving means for detecting the error signal, error signal detecting means for detecting an error signal proportional to the difference between the position where the recording / reproducing element should perform recording and reproduction and the actual position, and the error signal detected by the error signal detecting means. On the other hand, it includes a control calculation means for performing a control calculation using a control parameter and calculating a control output for reducing the absolute value of the error signal, the drive means, the error signal detection means, and the control calculation means A control parameter calculating means for calculating a control parameter for realizing the servo performance required for the servo control system; Control arithmetic means for performing phase advance / lag characteristics, the control arithmetic means and the control arithmetic means are connected in parallel to each other, and the control parameter calculating means is an index representing the servo performance The recording / reproducing apparatus calculates the zero point and pole of the phase advance / delay means from the zero cross frequency of the open loop frequency characteristic.

  In one aspect of the present invention, a phase advance of a low-frequency emphasis calculation unit that performs low-frequency emphasis on a control system and a phase advance / delay operation unit that realizes a phase advance / delay characteristic of the control system, connected in parallel to each other. The zero point and pole of the delay characteristic are calculated from the zero cross frequency of the open loop frequency characteristic of the control system as a control parameter, and are connected in parallel using the zero point and pole of the phase lead delay characteristic calculated as the control parameter. The low-frequency emphasis calculation unit and the phase advance / delay calculation unit calculate a control output for controlling the operation of the angle or position of the control target toward the target value.

  In another aspect of the present invention, a recording / reproducing element for writing / reading data to / from a disk-shaped recording medium, and a recording / reproducing element for driving the recording / reproducing element in a horizontal direction or a vertical direction with respect to a recording surface of the disk-shaped recording medium Drive means, error signal detection means for detecting an error signal proportional to the difference between the position at which the recording / reproducing element should perform recording and reproduction and the actual position, and control for the error signal detected by the error signal detection means Required for a servo control system including a control calculation means for performing a control calculation using parameters and calculating a control output for reducing the absolute value of the error signal, a drive means, an error signal detection means, and a control calculation means A control parameter calculating unit that calculates a control parameter for realizing the servo performance, the control calculating unit includes a control calculating unit that performs low-frequency emphasis; a phase calculating unit; Control calculation means that realizes only delay characteristics, the control calculation means and the control calculation means are connected in parallel with each other, and the zero point of the phase advance / delay means from the zero-cross frequency of the open loop frequency characteristic, which is an index representing the servo performance And poles are calculated.

  According to the present invention, it is possible to more appropriately and easily set a control parameter of a servo control system that controls the operation of an angle or position of a control target toward a target value. In particular, a desired low-frequency gain can be more easily realized with a common algorithm regardless of the size of the dead time element while using intuitively easy-to-understand control parameters.

  FIG. 3 is a block diagram showing a main configuration example of an optical disc recording / reproducing apparatus to which the present invention is applied. An optical disk recording / reproducing apparatus 100 shown in FIG. 3 is an apparatus that reads and writes information from and to an optical disk 107 mounted at a predetermined position. The optical disc recording / reproducing apparatus 100 includes a system controller 101, a spindle motor drive circuit 102, a spindle motor 103, a servo control unit 104, a data processor 105, and an optical head unit 106.

  The system controller 101 is a control unit that controls the operation of each unit in the optical disc recording / reproducing apparatus 100. A CPU (Central Processing Unit) 111 of the system controller 101 executes various processes according to a program stored in a ROM (Read Only Memory) 112 or a program loaded in a RAM (Random Access Memory) 113. The RAM 113 also appropriately stores data necessary for the CPU 111 to execute various processes.

  The spindle motor drive circuit 102 is controlled by the system controller 101 to control the rotation drive of the spindle motor 103 for rotating the optical disc 107. The servo control unit 104 is controlled by the system controller 101 to control the condensing position of the optical pickup (optical head unit 106). The data processor 105 is controlled by the system controller 101 to perform information processing for processing information read from the optical disc 107 and information written to the optical disc 107. The optical head unit 106 is controlled by the system controller 101 to irradiate the optical disk 107 with a laser beam to read and write information.

  FIG. 4 is a block diagram showing a detailed example of the configuration related to the position control of the pickup among the components of the optical disc recording / reproducing apparatus 100 of FIG. As shown in FIG. 4, the optical disc recording / reproducing apparatus 100 includes a recording / reproducing element 121, a control unit 122, an electromagnetic actuator 123 </ b> A and an electromagnetic actuator 123 </ b> B, and a control parameter generation unit 124.

  The recording / reproducing element 121 is an element that writes and reads data to and from the optical disc 107 that is a recording medium. The recording / reproducing element 121 writes or reads data by focusing laser light on each recording layer of the optical disc 107 that is rotated. Therefore, the control unit 122 controls the condensing position of the laser light output from the recording / reproducing element 121 in the vertical direction and the horizontal direction with respect to the recording surface of the optical disc 107 using the electromagnetic actuator 123A and the electromagnetic actuator 123B. .

  In the following, only the control in the direction perpendicular to the recording surface of the optical disc 107 at the condensing position (focus error control) will be described. The control in the horizontal direction (tracking error control) with respect to the recording surface of the optical disc 107 at the condensing position is basically the same as the focus error control except that the control direction is different, and the following description can be applied. Therefore, the description is omitted.

  The recording / reproducing element 121 reads and writes data by irradiating the optical disc 107 with laser light, and generates an error signal by detecting return light reflected by the recording surface of the optical disc 107, and controls this. To the unit 122. The control unit 122 controls the electromagnetic actuator 123A and the electromagnetic actuator 123B based on the error signal.

  The recording / reproducing element 121 includes a laser light source 131, a light separation unit 132, a lens unit 133, and a light receiving unit 134. The laser light source 131 emits laser light having a predetermined wavelength toward the light separation unit 132. The light separation unit 132 refracts the laser light emitted from the laser light source 131 and guides it to the optical disc 107 side (lens unit 133), and transmits the laser light reflected by the optical disc 107 to the light receiving unit 134. The lens unit 133 condenses the laser light from the light separation unit 132 to focus on each recording layer of the optical disc 107, and converts the return light from the optical disc 107 into parallel light and supplies it to the light separation unit 132. The light receiving unit 134 includes a photoelectric conversion element using, for example, a CMOS (Complementary Metal Oxide Semiconductor) sensor, a CCD (Charge Coupled Device), or the like. The light receiving unit 134 receives the return light from the optical disc 107 supplied via the light separation unit 132, photoelectrically converts it, and supplies the obtained error signal to the control unit 122.

  In FIG. 4, one laser light source 131, one light separation unit 132, one lens unit 133, and one light receiving unit 134 are shown, but a plurality of them may be provided. Moreover, the positional relationship of each part shown by FIG. 4 is an example, and may be arrange | positioned how. Of course, the shape and size of each part are also arbitrary.

  The control unit 122 includes an error signal detection circuit 141, an AD converter 142, a control arithmetic circuit 143, a DA converter 144, and an actuator drive circuit 145. The error signal detection circuit 141 generates a focus error signal by detecting an error signal generated in the light receiving unit 134 and supplies the focus error signal to the AD converter 142. The AD converter 142 performs A / D (Analog / Digital) conversion on the focus error signal generated in the error signal detection circuit 141, and performs control calculation on the digitized focus error signal (hereinafter also referred to as a digital focus error signal). This is supplied to the circuit 143. The control operation circuit 143 performs a predetermined control operation on the digital focus error signal supplied from the AD conversion unit 142, and controls the digital signal so as to reduce the focus error (hereinafter referred to as a digital control signal). Is generated. The control operation circuit 143 performs this control operation using the control parameter supplied from the control parameter generation unit 124, generates a digital control signal, and supplies it to the DA converter 144. The DA conversion unit 144 performs D / A (Digital / Analog) conversion on the digital control signal supplied from the control arithmetic circuit 143, and converts the analog control signal (hereinafter referred to as an analog control signal) to the actuator drive circuit 145. Supply. The actuator drive circuit 145 drives the electromagnetic actuator 123A and the electromagnetic actuator 123B based on the analog control signal supplied from the DA converter 144.

  The electromagnetic actuator 123 </ b> A and the electromagnetic actuator 123 </ b> B move the recording / reproducing element 121 close to and away from the recording surface of the optical disc 107 in accordance with a control signal supplied from the control unit 122. In the following, when it is not necessary to distinguish between the electromagnetic actuator 123A and the electromagnetic actuator 123B, they are collectively referred to as the electromagnetic actuator 123.

  The control parameter generation unit 124 generates control parameters necessary for the control calculation in the control unit 122. The control parameter generation unit 124 includes an input unit 151, a control parameter calculation unit 152, and a display unit 153. The input unit 151 receives input information such as parameters and control instructions from the outside of the optical disc recording / reproducing apparatus 100 such as a user, and supplies the input information to the control parameter calculation unit 152. The control parameter calculation unit 152 performs processing related to calculation of the control parameter based on input information supplied from the input unit 151. For example, the control parameter calculation unit 152 calculates the control parameter, supplies the calculated control parameter to the control arithmetic circuit 143, causes the control arithmetic circuit 143 to calculate the open loop frequency characteristic of the servo control system, The information is displayed on the part 153. The display unit 153 includes a display such as a CRT (Cathode Ray Tube) display, an LCD (Liquid Crystal Display), a PDP (Plasma Display Panel), an organic EL display (Organic ElectroLuminescence Display), or an FED (Field Emission Display). Information is displayed under the control of the control parameter calculator 152.

For example, the control parameter calculation unit 152, the control parameters used for the respective control function of the control arithmetic circuit 143, is input via the input unit 151, based on the desired zero-crossing frequency f _x in the control system open loop transfer function The calculation result is supplied to the control calculation circuit 143. By transferring this control parameter to the control arithmetic circuit 143, servo control of the recording / reproducing element 121 by the control unit 122 becomes possible.

  The recording / reproducing element 121 and the electromagnetic actuator 123 correspond to, for example, the optical head unit 106 in FIG. The control unit 122 corresponds to, for example, the servo control unit 104 in FIG. The control parameter generation unit 124 includes, for example, the system controller 101 and the data processor 105 shown in FIG.

  FIG. 5 is a block diagram for realizing the control system of the focus error control of the recording / reproducing element 121 using the electromagnetic actuator 123 by the control unit 122 shown in FIG. 4 by digital control.

  In FIG. 5, ref indicates a target position representing the position where the recording / reproducing element 121 should be. dis indicates a disturbance such as a shake of the optical disc 107 applied to the target position. Err represents a position error of the control position with respect to the target position (that is, an error in the control result). This position error err corresponds to the difference (ref + dis−y) between the target position (ref + dis) of the recording / reproducing element 121 changed according to the disturbance dis and the actual position y of the control target. That is, the position error err is calculated by the logical operation unit 161 as shown in the following expression (3).

  err = ref + dis-y (3)

  Actually, the control unit 122 cannot directly detect the disturbance dis and the actual position y applied to the recording / reproducing element 121. Therefore, the control unit 122 performs servo control by detecting the position error err corresponding to the focus error signal in the error signal detection circuit 141.

In FIG. 5, the position error err is sampled and a control calculation is performed by the controller 163 (K (z)). After this control calculation, the calculation result is output after one sampling time. Incidentally, the calculation time delay in the controller 163 is represented by a dead time element 164 (1 / z). The calculation result output from the dead time element 164 is output to the control target as the control signal u through the zero-order holder 165 (ZOH). The zero-order holder 165 corresponds to the DA converter 144 in FIG. The actuator is driven by the control signal u to determine the position y of the recording / reproducing element. A transfer function from the control signal u to the position y of the recording / reproducing element is represented by a control object 166 (P (s)). Incidentally, the control object 166 (P (s)) is represented by a quadratic integral element (G _p / s ² ) for simplicity.

First, the pole arrangement formula shown in Patent Document 2 will be described. In this case, the controller 163 is modeled by a series connection of a low-frequency booster 1 and a phase advance / lag filter 2 as shown in FIG. Therefore, the control parameters of the controller 163 include the low frequency boost cutoff discretization angular frequency a, the low frequency boost discretization angular frequency c, the phase advance discretization angular frequency d, the phase delay discretization angular frequency b, and the controller gain. it is five of K _p.

The pole placement equations for the control system of FIG. 5 are expressed by the following equations (4) to (10). Here, p ₁ , p ₂ , p ₃ , and p ₄ represent the positions of the four poles to be arranged, and q represents the position of the “pole that cannot be arranged” that is automatically determined. Further, the low frequency boost cut-off discretization angular frequency a is designated in advance from factors such as the disk rotation frequency.

ただし、
Ｃ₁＝−（ｐ₁＋ｐ₂＋ｐ₃＋ｐ₄）
Ｃ₂＝ｐ₁ｐ₂＋ｐ₁ｐ₃＋ｐ₁ｐ₄＋ｐ₂ｐ₃＋ｐ₂ｐ₄＋ｐ₃ｐ₄
Ｃ₃＝−（ｐ₁ｐ₂ｐ₃＋ｐ₁ｐ₂ｐ₄＋ｐ₁ｐ₃ｐ₄＋ｐ₂ｐ₃ｐ₄）
Ｃ₄＝ｐ₁ｐ₂ｐ₃ｐ₄

However,
C ₁ = − (p ₁ + p ₂ + p ₃ + p ₄ )
C ₂ = p ₁ p ₂ + p ₁ p ₃ + p ₁ p ₄ + p ₂ p ₃ + p ₂ p ₄ + p ₃ p ₄
C ₃ = − (p ₁ p ₂ p ₃ + p ₁ p ₂ p ₄ + p ₁ p ₃ p ₄ + p ₂ p ₃ p ₄ )
C ₄ = p ₁ p ₂ p ₃ p ₄

  As shown in FIG. 5, these equations are pole placement equations when the control system has a dead time element with a delay of 1 sampling time, but when there is a dead time element with a delay of 2 sampling times, 3 sampling times Even in the case where there is a delay time delay, the pole placement equation can be obtained in the same way. For example, the pole placement formulas when there is a delay time element of 3 sampling times are expressed by the following formulas (11) to (19).

Patent Document 2 also describes a technique for performing pole placement by approximating a dead time element with a first-order lag element when there is a dead time element between one sampling time and two sampling times. As described in Patent Document 2, a control system that is resistant to disturbances by arranging these four poles p ₁ , p ₂ , p ₃ , and p ₄ in the same position using these pole placement equations. Can be calculated.

  However, in this case, the relationship between the closed loop pole and the control system is generally unfamiliar and may be difficult to understand. Further, for example, the control parameter of the control system having a dead time element that is delayed by one sampling time can be obtained by the pole placement equations shown in the equations (4) to (10). On the other hand, the control parameters of the control system having a dead time element with a delay of three sampling times can be obtained by the pole placement equations shown in equations (11) to (19). That is, in order to obtain the control parameter, it is complicated because it is necessary to select a pole arrangement formula depending on the size of the dead time element. Similarly, even in the case of the pole placement type for the non-integer time delay used in the technique described in Patent Document 3, when the dead time element takes a value between 1 sampling time and 2 sampling time, 2 sampling When taking a value between time and three sampling times, it is necessary to select different pole arrangement formulas, which is complicated. Therefore, the present invention proposes a simple technique that can determine control parameters with the same algorithm even for systems that are intuitively easy to understand and have a clear meaning and have different dead times.

Specifically, the controller may be modeled in a parallel configuration of the low-frequency booster and a phase lead-lag filter, so that adjustment is performed by using an intuitive easy to understand control parameters such as the zero crossing frequency f _x.

Control parameter generating unit 124 determines the provisional value of the control parameter of the phase lead-lag filter from the zero cross frequency f _x in the open loop frequency characteristic, then based on the open-loop frequency characteristic, match the f _x the zero-crossing frequency the target The controller gain _Kp is set to Then, the control parameter generation unit 124 allows the user to determine the gain of the low-frequency booster so that the condition-stable gain margin is 12 dB, and further changes the phase delay frequency so that the phase margin is 32 ° or more. Make fine adjustments. By using such a method, the control parameter generation unit 124 can set servo control using control parameters that are intuitively understandable to the user. Further, by using this method, the control parameter generation unit 124 can determine the control parameters with the same algorithm even for systems with different dead times. Finally, the control parameter generation unit 124 controls a control parameter that realizes the highest low-frequency gain (hereinafter referred to as a high gain servo parameter. A controller realized by the high gain servo parameter is a high gain servo controller. It is possible to generate a control parameter having a good value equivalent to Furthermore, by using this method, the control parameter generation unit 124 can easily achieve a desired low frequency gain without greatly affecting the phase margin by reducing the gain of the low frequency booster. Gain with a high degree of freedom, such as having a low-frequency gain that is intermediate between a high gain servo controller and a general controller (hereinafter referred to as a general controller) realized with control parameters other than the high gain servo parameter Adjustments can be made.

  Hereinafter, more specific contents of this method will be described in comparison with the method described in Patent Document 2. In the following, a case will be described in which the control system shown in FIG. 4 has a dead time element between one sampling time and two sampling times.

  First, a control system model will be described. FIG. 6 is a block diagram for realizing the control system of the focus error control of the recording / reproducing element 121 using the electromagnetic actuator 123 by the control unit 122 shown in FIG. 4 by digital control. The control model shown in FIG. 6 is a model in which the control system shown in FIG. 4 has a dead time element between one sampling time and two sampling times. Incidentally, FIG. 5 is a model in which the control system shown in FIG. 4 has a dead time element of one sampling time.

  The model shown in FIG. 6 and the model shown in FIG. 5 are basically similar, but in the case of the model shown in FIG. 6, the time delay element 164, the zero-order holder 165, and the model shown in FIG. Instead of the controlled object 166 (P (s)), a dead time element 167 and a controlled object 168 (P (s)) are provided. That is, in the model shown in FIG. 6, compared to the case of FIG. 5, the zero-order holder 165 is omitted, and the functions of the dead time element and the control target P (s) are different. Specifically, the dead time element 167 is represented by the following equation (20), and the controlled object 168 is represented by the following equation (21).

Dead time factor = 0.65 / (z−0.35) (20)
^{P (s) = (T 2} /2) × {(z + 1) / (z-1) 2} × G p ··· (21)
^{_{However, G p = 5.032 × 10 9}} , T = 5 × 10 6

  Control parameters used for the function of the controller 163 (K (z)) are generated by the control parameter generator 124.

  In such a control model, when a general controller and a high gain servo controller are obtained using the method described in Patent Document 2 in which a controller is modeled by a low-frequency booster connected in series and a phase advance / lag filter. Each open loop frequency characteristic is shown in FIG. In the graph shown in FIG. 7, a curved line 171 and a curved line 181 indicated by thin solid lines indicate the open loop frequency characteristics of the general controller, and a curved line 172 and a curved line 182 indicated by thick solid lines indicate the open state of the high gain servo controller. The loop frequency characteristic is shown.

  The value of each control parameter of this general controller is that the low frequency boost cutoff frequency is 5 Hz, the low frequency boost frequency is 343 Hz, the phase advance frequency is 1085 Hz, the phase delay frequency is 35 kHz, and the zero cross frequency. Is 6 kHz. The closed-loop poles at this time are 0.9899, 0.9530, 0.8108 ± 0.1825j, and 0.1182, and there is only one pole 0.9899 with a slow response.

On the other hand, in the case of a high gain servo controller, the pole placement method is applied so that four poles are placed for the control parameters K _p , b, c, and d, and the high-frequency gain of the open loop characteristic is equal The four poles are 0.8764. As shown in FIG. 7, the high gain servo controller achieves a higher gain in a lower frequency range than the general controller. At this time, the control parameters are as follows.

K _p = 1.088
b = 0.2086
c = 0.9599 + 0.0288j
d = 0.9599-0.0288j

  As described above, when the controller is modeled by the low-frequency booster connected in series and the phase advance / lag filter, it is confirmed that the high gain servo controller has a complex zero in the control parameter.

  In contrast, the control parameter generation unit 124 generates a control parameter when the controller is modeled as shown in FIG. In FIG. 8, the controller model includes a low-frequency booster 201, a phase advance / delay filter 202, a logic operation unit 203, and a controller gain 204 connected in parallel.

Low frequency booster 201, the cutoff frequencies of very low-frequency booster 201 (hereinafter, low-frequency referred to as a cut-off frequency) using a and a low-gain K _L, represented by the following formula (22) .

Low frequency booster = K _L / (za) (22)

  The phase advance / delay filter 202 is expressed by the following equation (23) using the pole (phase delay frequency b) of the phase advance / delay filter 202 and the zero point (phase advance frequency e).

  Phase advance / delay filter = (ze) / (z−b) (23)

As shown in FIG. 8, the low-frequency booster 201 and the phase advance / lag filter 202 are arranged in parallel so that their outputs are synthesized in the logic operation unit 203, and further, the controller gain 204 (K _pp ). Connected in series.

  When a general controller is obtained with such modeling control parameters, the frequency characteristics of the low-frequency booster 201 are indicated by thin broken lines 173 and 183 in the graph of FIG. Is indicated by a thin dotted line 175 and a thin dotted line 185. Similarly, when a high gain servo controller is obtained, the frequency characteristic of the low-frequency booster 201 is indicated by a thick broken line 174 and a thick broken line 184 in the graph of FIG. 7, and the frequency characteristic of the phase advance / lag filter 202 is thick. A dotted line 176 and a thick dotted line 186 indicate.

  In FIG. 7, comparing the frequency characteristics of the conventional controller and the high gain servo controller in this case, it can be seen that the phase advance / lag filter 202 is substantially the same and the gain of the low frequency booster 201 is greatly different. That is, it can be said that a high gain servo controller in a parallel configuration is obtained by increasing the low frequency gain to such an extent that it does not vibrate while maintaining the high frequency phase characteristics. Therefore, the parameters of the high gain servo controller can be obtained by obtaining the upper limit of the low frequency gain at which the closed loop pole does not vibrate. Moreover, if the gain of the low-frequency booster of the high gain servo controller is lowered, characteristics intermediate to those of the conventional control can be easily obtained.

Next, the configuration of the control parameter calculation unit 152 that generates the control parameters of such a control model will be described. FIG. 9 is a block diagram illustrating a detailed configuration example of the control parameter calculation unit 152 in this case. As shown in FIG. 9, the control parameter calculation unit 152 includes an input receiving unit 211, e _s calculator 212, b _s calculator 213, abe calculator 214, the measurement control unit 215, K _pp determining unit 216, a gain margin A display control unit 217, a phase margin display control unit 218, and a parameter setting unit 219 are included.

  The input receiving unit 211 receives input of control instructions, parameter values, and the like from the outside via the input unit 151. In addition, the input receiving unit 211 supplies the received control instruction to the processing unit corresponding to the instruction. Further, the input receiving unit 211 holds the received parameters and appropriately supplies them to other processing units.

e _s calculator 212 obtains the zero-cross frequency f _x and the phase lead frequency ratio A _r of the target from the input receiving unit 211, calculates the phase lead frequency e _s using them, and supplies the abe calculator 214 . b _s calculator 213 obtains the zero-cross frequency f _x and phase lag frequency ratio B _r of the target from the input receiving unit 211, calculates the phase delay frequency b _s using them, and supplies the abe calculator 214 . abe calculation unit 214, a low band cut-off frequency a _s obtained from the input receiving unit 211, b _s phase obtained from the calculation unit 213 delays the frequency b _s, and the phase lead frequency e _s acquired from the e _s calculator 212 Is digitized, and digital control parameters a, b and e are calculated. The abe calculation unit 214 supplies the calculated digital control parameters (the low-frequency cutoff frequency a, the phase delay frequency b, and the phase advance frequency e) to the measurement control unit 215. Also, the abe calculation unit 214 supplies the calculated digital control parameters to the input reception unit 211 and holds them.

The measurement control unit 215 supplies the digital control parameters, the low-frequency gain K _L and the controller gain K _pp acquired from the input reception unit 211 to the control arithmetic circuit 143 together with the control command, and supplies them to the control unit 122. The frequency characteristics of the control system using the control parameters are measured.

K _pp determination unit 216, based on the frequency characteristics measured by the control unit 122, determines the zero crossing frequency, the controller gain K _pp to coincide with the zero cross frequency f _x to obtained from the input receiving unit 211 targets To do. The gain margin display control unit 217 causes the display unit 153 to display information related to the gain margin based on the frequency characteristic measured by the control unit 122. The phase margin display control unit 218 causes the display unit 153 to display information regarding the phase margin based on the frequency characteristics measured by the control unit 122. When the parameter setting unit 219 completes the adjustment of the control parameter, for example, when the frequency characteristic is satisfactory, the digital setting parameter (low frequency cutoff frequency a) , Phase lag frequency b, phase advance frequency e, controller gain K _pp , and low frequency gain K _L ) are supplied to the control arithmetic circuit 143 and set as formal control parameters.

  The control unit 122 performs servo control using the control parameters determined in this way.

Next, a method for determining the upper limit of the low-frequency gain that does not vibrate, that is, the control parameter for realizing the high gain servo controller will be described. When the dead time element in the control system is 1 sampling time, 2 sampling time, and 3 sampling time, control parameters K _pp , K _L , e, and b at various pole arrangements were obtained from the control parameter calculation formula. The results at this time are shown in the tables of FIGS. Also, read the zero crossing frequency f _x and phase margin at each pole position from the graph, it is summarized in the table of FIG. 13.

First, the phase lead frequency e is a zero point of the phase lead-lag filter, and will be described that the phase lead phase lead frequency ratio A _r calculated from the frequency e. The calculated e as shown in the table of FIGS. 10 to 12 mended continuous system obtains a phase lead frequency (-e _s / 2π), and displays the ratio zero-cross frequency f _x shown in the table of FIG. 13 . The horizontal axis, calculated as phase advance following equation frequency ratio A _r when the normalized zero-crossing frequency f _x normalized by the sampling frequency (24), and the results are shown in Figure 14.

A _r = (− e _s / 2π) / fx (24)

As shown in the graph of FIG. 14, is a phase-lead frequency substantially constant, a slight increase as the normalized zero-crossing frequency increases, the phase lead frequency ratio A _r takes a value of 0.43 to 0.48. Is the value of the phase lead frequency ratio A _r of the general controller larger than the 0.333, but the change is small, where the phase lead frequency ratio A _r is considered as a constant value. At this time, although the value of the phase lead frequency ratio A _r may be the value of 0.43 to 0.48 throat, here, the phase lead frequency ratio A _r = 0.47.

Next, the phase lag frequency b that is the pole of the phase lag filter and the phase lag frequency ratio _Br calculated from the phase lag frequency b will be described. Obtains a phase lag frequency (-b _s / 2 [pi) to fix the calculated b the continuous system, and calculates a phase lag frequency ratio B _r respect to the normalized zero-crossing frequency f _x as shown in the following expression (25), the The results are shown in FIG.

B _r = (− b _s / 2π) / f _x (25)

As shown in the graph of FIG. 15, when the normalized zero-crossing frequency f _x is small, the value of the phase delay frequency ratio B _r is but degree 3, the normalized zero-crossing frequency f _x becomes larger, the phase delay due to the dead time In order to recover, the phase lag frequency ratio _Br increases to about 16. Therefore, the value of the phase lag frequency b, such that the phase margin take sufficient, under the condition that the value of the phase lag frequency ratio B _r is limited to the range of 3 to 16, to be adjusted.

Note that there is no example in which the value of the phase lag frequency ratio B _r exceeds 16 even at the pole leaf position, so that a sufficient phase margin cannot be obtained even if the value of the phase lag frequency ratio B _r exceeds 16. there unreasonable considered can not be a stable electrode placement, the re-set to reduce the value of the zero-cross frequency f _x, so that re-setting the control parameters again.

  Next, the phase margin will be described. FIG. 16 shows an example of the phase margin. As shown in the graph of FIG. 16, the phase margin decreases as the normalized zero cross frequency increases, but in any case, 32 ° or more is secured. If an attempt is made to further increase the zero-cross frequency, poles that cannot be arranged go out of the unit circle and oscillate. Although it does not directly oscillate due to the phase margin, it is assumed here that 32 ° is one target, and whether or not the phase margin of 32 ° or more can be secured is used as a criterion for whether or not the control parameter is appropriate. .

  Next, the condition-stable gain margin will be described. FIG. 17 shows an example of a condition-stable gain margin. As shown in the graph of FIG. 17, the gain margin for condition stabilization gradually decreases as the zero cross frequency is increased, but is 12 dB or more in any case. Therefore, here, whether or not a gain margin of 12 dB or more can be secured is used as a criterion for whether or not the control parameter is appropriate.

  As described above, the control parameter is determined under the following conditions.

1) a phase lead frequency e from the zero-cross frequency f _x and 0.47f _x, the phase lag frequency b and 3f _x.
2) small enough low-frequency gain K _L, the controller gain K _pp is set to be a zero-cross frequency f _x of zero-crossing frequency a target.
3) Increase the low frequency gain K _L until the gain margin becomes 12 dB.
4) If the phase margin is 32 degrees or more, the value of each control parameter is determined. If it is not 32 degrees, the value of the phase delay frequency b _s is increased. If increasing from the 16 phase lag frequency b _s can not be the phase margin above 32 degrees, decreasing the value of the zero-cross frequency f _x.
5) determine the value of the controller gain K _pp so again zero crossing frequency is f _x.

After the control parameters have been determined in this way, by reducing the low-frequency gain K _L, properties intermediate of general controller and the high gain servo controller is obtained.

  Next, the flow of processing relating to the above control parameter setting will be described.

  First, an example of the flow of parameter setting processing will be described with reference to the flowchart of FIG. When an instruction from the outside such as a user is received through the input unit 151, for example, the control parameter calculation unit 152 executes a parameter calculation process as shown in FIG.

When the parameter setting process is started, the input receiving unit 211 controls the input unit 151 accepts the input of the cut-off frequency a _s in step S1, accepts an input of zero crossing frequency f _x to the target in step S2.

In step S3, e _s calculation unit 212, by, for example to get from the input receiving unit 211 the frequency ratio A _r phase advance, to determine the phase lead frequency ratio A _r, using the value of the phase lead frequency ratio A _r to calculate the phase lead frequency e _s Te. For example, e _s calculation unit 212, as described above, the value of the phase lead frequency ratio A _r to determine 0.47, formula based on the (24), the following equation phase lead frequency e _s (26) Calculate as follows.

_{e s = -2πf x · A r} ··· (26)

Incidentally, e _s calculation unit 212 may be acquired from the input receiving unit 211 to the phase lead frequency ratio A _r, may be e _s calculation unit 212 are stored in advance.

In step S4, the input accepting unit 211 accepts an input of the phase lag frequency ratio B _r. In step S5, b _s calculation unit 213, as in Equation (25) the following equation on the basis of (27), calculates a phase lag frequency b _s zero-crossing frequency f _x and phase lag frequency ratio B _r of the target To do.

_{b s = -2πf x · B r} ··· (27)

  Note that the value of the phase delay frequency ratio Br is limited to a predetermined range (for example, 3 to 16).

In step S6, the abe calculation unit 214 calculates the digital control parameters a, b, e using the processing results of step S1, step S3, and step S5. In step S7, the input receiving unit 211 receives the controller gain K _pp and the low frequency gain K _L. In step S8, the measurement control unit 215 starts a frequency characteristic measurement control process that causes the control unit 122 to measure the frequency characteristic.

  When the frequency characteristic measurement control process is started, the measurement control unit 215 ends the parameter setting process.

  Next, an example of the flow of frequency characteristic measurement control processing will be described with reference to the flowchart of FIG.

  When the frequency characteristic measurement control process is started, the measurement control unit 215 supplies the parameter calculated by the parameter setting process to the control arithmetic circuit 143 in step S21. In step S22, the measurement control unit 215 controls the control arithmetic circuit 143 to apply the servo and measure the open loop frequency characteristic.

When the measurement is finished, K _pp determination unit 216, at step S23, determines the controller gain K _pp realizing the zero-cross frequency f _x to the target. In step S24, the gain margin display control unit 217 to display information about the condition stable gain margin to the display unit 153 prompts the setting of the low gain K _L user. In step S25, the gain margin display control unit 217 determines whether or not the low frequency gain K _L is determined. If it is determined that the low frequency gain K _L is determined, the process proceeds to step S26.

  In step S26, the phase margin display control unit 218 causes the display unit 153 to display information regarding the phase margin, and in step S27, the phase margin adjustment process is started. When the phase margin adjustment process is started, the phase margin display control unit 218 ends the frequency characteristic measurement control process.

Further, in step S25, if it is determined that it has not reached yet to the determination of low-frequency gain K _L, the gain margin display control unit 217 causes the process to proceed to step S28. In step S28, the input receiving unit 211 receives the low-frequency gain K _L, the process returns to step S21, and executes the processing thereof and thereafter.

Next, an example of the flow of phase margin adjustment processing will be described with reference to the flowchart of FIG. When the phase margin adjustment process is started, the parameter setting unit 219 determines whether or not the phase margin is determined to be sufficient in step S41. If it is determined that it is not sufficient, the process proceeds to step S42. In step S42, the parameter setting unit 219 determines whether or not the updated phase delay frequency ratio _Br is within a predetermined range (for example, any one of 3 to 16). If it is determined that the value is within the range, the process proceeds to step S43. In step S43, the parameter setting unit 219, from where the accept the phase lag frequency ratio B _r, i.e., the step S4, to initiate a parameter setting process in FIG. 18. When the parameter setting process is started, the parameter setting unit 219 ends the phase margin adjustment process.

If it is determined in step S42 that the updated phase delay frequency ratio _Br is outside the predetermined range, the process proceeds to step S44. In step S44, the parameter setting unit 219, from where the accept the zero cross frequency f _x to the target, i.e., the step S2, starts a parameter setting process in FIG. 18. When the parameter setting process is started, the parameter setting unit 219 ends the phase margin adjustment process.

  Furthermore, when it is determined in step S41 that the phase margin is sufficient, the process proceeds to step S45. In step S45, the parameter setting unit 219 determines each parameter as a current value. When the process of step S45 is completed, the parameter setting unit 219 ends the phase margin adjustment process.

That is, the control parameter calculation unit 152 adjusts the controller gain K _pp so that the zero cross frequency matches the target value (target zero cross frequency f _x ) in the frequency characteristics of the measurement result, and further, the condition stable gain margin The user adjusts the low-frequency gain K _L so that becomes 12 dB. When conditions become stable gain margin and 12dB, the control parameter calculation unit 152, the phase margin (make larger value) is adjusting the phase lag frequency ratio B _r to the user to a predetermined value (e.g., 32 °) or . When the phase lag frequency ratio B _r can not be sufficiently ensured phase margin even reached the upper limit (e.g., 16) in a predetermined range (32 ° not more than), because of the force to the value of the zero-cross frequency f _x to the target , the control parameter calculation unit 152 decreases the value of the zero-cross frequency f _x to its target. The control parameter calculation unit 152 performs the processing related to the adjustment as described above until the condition stable gain margin and the phase margin are sufficiently secured.

As described above, in the present invention, the model of the controller 122, by realizing a parallel arrangement of the low-frequency booster 201 and the phase lead-lag filter 202, the user, the intuitive control parameter intuitive like zero-cross frequency f _x Can be used to make adjustments. Specifically, it determines the provisional value of the control parameter of the phase lead-lag filter from the zero cross frequency f _x in the open loop frequency characteristic, so that the zero-cross frequency matches the f _x to a target to then look at the open-loop frequency characteristic A controller gain K _pp is set. Further conditions stable gain margin is determined low gain K _L so as to be 12dB, finally it changes the phase lag frequency so that the phase margin is 32 ° or more, the overall fine-tuning of place. In this way, the user can intuitively understand each control parameter, and can further determine the control parameter with the same algorithm even for systems with different dead times. A good control parameter equivalent to the high gain servo parameter determined using the method of Patent Document 2 can be obtained. Furthermore, when it is desired to have a low-frequency gain intermediate to that of the general controller, the user can easily achieve the desired low-frequency gain without greatly affecting the phase margin by reducing the gain of the low-frequency booster 201. Can do.

  In the above, the gain margin display control unit 217 and the phase margin display control unit 218 cause the user to adjust the control parameters according to a predetermined algorithm by causing the display unit 153 to display information on the gain margin and the phase margin. As described above, at this time, information such as a guidance message prompting the user to adjust the control parameter according to a predetermined algorithm may be displayed on the display unit 153 together with information on the gain margin and the phase margin.

  Further, instead of the user, the control parameter calculation unit 152 may adjust the control parameter based on the gain margin and the phase margin which are measurement results.

  FIG. 21 is a block diagram illustrating a configuration example of the control parameter calculation unit 152 in that case. As shown in FIG. 21, the control parameter calculation unit 152 in this case has basically the same configuration as that in FIG. 9, but the gain margin display control unit 217 and the phase margin display control unit 218 in FIG. Instead, a gain margin adjustment unit 317 and a phase margin adjustment unit 318 are provided.

Gain margin adjusting unit 317, according to the algorithm described above, the measured frequency characteristic in the control unit 122, according to the value of the condition stable gain margin, to adjust the low-frequency gain K _L. Specifically, the gain margin adjusting unit 317, the condition stabilized gain margin adjust the low gain K _L to a predetermined value (for example 12dB). More specifically, the gain margin adjusting unit 317, if the condition stable gain margin is greater than 12dB, and increase the low frequency gain K _L, condition stable gain margin if 12dB less, to reduce the low-frequency gain K _L .

The phase margin adjustment unit 318 adjusts the phase lag frequency ratio _Br according to the phase margin value of the frequency characteristic measured by the control unit 122 according to the algorithm described above. Specifically, the phase lag frequency ratio _Br is increased until the phase margin becomes sufficiently large (until a predetermined threshold value or higher). More specifically, when the phase margin is not sufficiently large, the phase margin adjustment unit 318 resets the phase lag frequency ratio _Br so that the value is increased by a predetermined amount, and resets various control parameters based thereon. Then, the frequency characteristic is measured again.

As described above, in the algorithm described above, the value of the phase delay frequency ratio _Br is limited to a predetermined range (for example, 3 or more and 16 or less). Therefore, when the value of the phase lag frequency ratio _Br becomes larger than the upper limit (for example, 16) of the range, the phase margin adjustment unit 318 resets the target zero-cross frequency fx so that the value is reduced by a predetermined amount. Then, after resetting various control parameters based thereon, the frequency characteristics are measured again.

  Then, when the conditions of the condition stable gain margin and the phase margin are satisfied, the parameter setting unit 219 sets each control parameter to the value at that time.

  An example of the flow of such parameter calculation processing will be described with reference to the flowcharts of FIGS. The algorithm of this parameter calculation process is the same as that of each process described with reference to the flowcharts of FIGS. Therefore, this parameter calculation process is basically performed in the same manner as in the case of each process described with reference to the flowcharts of FIGS.

The parameter calculation process is started, the input receiving unit 211 controls the input unit 151 accepts the input of the cut-off frequency a _s in step S101 of FIG. 22, the input of the zero-crossing frequency f _x to the target in step S102 Accept. In step S103, e _s calculation unit 212 determines the phase lead frequency ratio A _r, calculates a phase lead frequency e _s using the value of the phase lead frequency ratio A _r.

In step S104, the input accepting unit 211 accepts an input of the phase lag frequency ratio B _r. In step S105, b _s calculation unit 213 calculates a phase lag frequency b _s using a zero-crossing frequency f _x and phase lag frequency ratio B _r a target. In step S106, the abe calculation unit 214 calculates the digital control parameters a, b, e using the processing results of step S101, step S103, and step S105. In step S107, the input reception unit 211 receives the controller gain K _pp and the low frequency gain K _L and advances the process to step S121 in FIG.

In step S121 of FIG. 23, the measurement control unit 215 controls various digital control parameters such as a cut-off frequency a, a phase delay frequency b, a phase advance frequency e, a controller gain K _pp , and a low frequency gain K _L as a control arithmetic circuit. Forward to 143. In step S122, the measurement control unit 215 controls the control arithmetic circuit 143 to apply servo and measure the open loop frequency characteristic.

When the measurement is finished, K _pp determination unit 216, at step S123, determines the controller gain K _pp realizing the zero-cross frequency f _x to the target. In step S124, the gain margin adjustment unit 317 calculates the condition stable gain margin of the frequency characteristic obtained by the measurement. In step S125, the gain margin adjustment unit 317 determines whether or not the calculated conditional stability gain margin is a predetermined value (for example, 12 dB). If it is determined that the gain is not a predetermined value, the process proceeds to step S126. .

In step S126, the gain margin adjustment unit 317 determines whether or not the calculated conditional stability gain margin is larger than a predetermined value (for example, 12 dB). When it is determined that the condition stable gain margin is greater than the predetermined value, the gain margin adjustment unit 317 increases the value of the low-frequency gain K _L , repeats the processing after step S121, and measures the open loop frequency characteristics again. Let

If it is determined in step S126 that the condition stable gain margin is smaller than the predetermined value, the gain margin adjustment unit 317 decreases the value of the low-frequency gain K _L , repeats the processing from step S121 onward, and opens it. The loop frequency characteristic is measured again.

  If it is determined in step S125 that the conditional stability gain margin is a predetermined value, the gain margin adjustment unit 317 advances the processing to step S141 in FIG.

  In step S141 in FIG. 24, the phase margin adjustment unit 318 calculates the phase margin of the frequency characteristic obtained by the measurement. In step S142, the phase margin adjustment unit 318 compares the calculated phase margin with a predetermined value (for example, 32 °) and determines whether or not the phase margin is sufficiently large. When it determines with it being large enough, the phase margin adjustment part 318 advances a process to step S143. In step S143, the parameter setting unit 219 determines the value of each control parameter as the current value, and ends the parameter calculation process.

If it is determined in step S142 that the phase margin is not sufficiently large, the phase margin adjustment unit 318 advances the process to step S144. In step S144, the phase margin adjustment unit 318 increases the phase lag frequency ratio _Br by a predetermined amount. Phase margin adjustment section 318 determines in step S145, the value of the phase delay frequency ratio B _r is whether it is within a predetermined range (e.g. 3 to 16).

In step S145, if the value of the phase delay frequency ratio B _r is determined to be within a predetermined range (e.g. 3 to 16), the phase margin adjustment section 318 returns the process to step S105 of FIG. 22, the subsequent Execute the process. That is, the phase margin adjustment unit 318 updates the phase lag frequency b (b _s ) using the updated phase lag frequency ratio _Br , and measures the open loop frequency characteristic again.

Further, the phase margin adjustment section 318, in step S145 of FIG. 24, the range value of the phase lag frequency ratio B _r is a predetermined (e.g., 3 to 16) outside, i.e., greater than the upper limit (e.g., 16) of the range determination If so, the process proceeds to step S146. In step S146, the phase margin adjustment section 318 to reduce the predetermined amount the value of the zero-cross frequency f _x to the target. When the process of step S146 is completed, the phase margin adjustment unit 318 returns the process to step S103 of FIG. 22 to execute the subsequent processes. That is, the phase margin adjustment unit 318, updated, using the zero-crossing frequency f _x to the target phase lead frequency e (e _s) and the phase lag frequency b (b _s) also is updated again, the open-loop frequency characteristic Let me measure.

That is, the control parameter calculation unit 152 adjusts the controller gain K _pp so that the zero cross frequency matches the target value (target zero cross frequency f _x ) in the frequency characteristics of the measurement result, and further, the condition stable gain margin The low-frequency gain K _L is adjusted so that becomes 12 dB. When the conditional stability gain margin becomes 12 dB, the control parameter calculation unit 152 adjusts the phase delay frequency ratio _Br so that the phase margin becomes a predetermined value (for example, 32 °) or more (increases the value). When the phase lag frequency ratio B _r is not sufficiently secured the phase margin even reached the upper limit (e.g., 16) in a predetermined range (32 ° not more than), the control parameter calculation unit 152, zero-cross the target frequency f _x because there is unreasonable value, decreasing the value of the zero-cross frequency f _x to its target. The control parameter calculation unit 152 performs the processing related to the adjustment as described above until the condition stable gain margin and the phase margin are sufficiently secured.

  As described above, the control parameter calculation unit 152 in this case appropriately calculates the control parameter for realizing the model of the controller 122 by the parallel configuration of the low-frequency booster 201 and the phase advance / lag filter 202 according to a predetermined algorithm. Can do. By doing in this way, the user can set each control parameter appropriately more easily. For example, it is possible to obtain a good control parameter equivalent to a high gain servo parameter determined using the method of Patent Document 2, and to easily achieve a desired low-frequency gain without greatly affecting the phase margin. You can also

  In the above, the case where the present invention is applied to the focus error control in which the recording / reproducing element is controlled in the direction perpendicular to the recording surface of the optical disc has been described. However, the present invention can also be applied to tracking error control that controls the horizontal direction.

  In the above description, the optical disk recording / reproducing apparatus is described as an apparatus to which the present invention is applied. However, the present invention is not limited to this, and the present invention is not limited to this. It may be an optical disk reproducing apparatus that reads and reproduces recorded data and does not write data to the optical disk, or an optical disk recording apparatus that writes data to the optical disk and does not read it. The recording medium may be other than an optical disk such as a magnetic disk or a magneto-optical disk.

  Furthermore, the present invention can be applied to any servo control that is equivalent to the focus error control described above, that is, any device that uses a control system that controls the angle or position of a control target toward a target value. The present invention can also be applied to an apparatus (control system), and the controlled object may be other than a recording / reproducing element (including a reproduction-only element and a recording-only element). Further, the control target may be a separate body. For example, in the example of FIG. 4, the control unit 122 and the control parameter generation unit 124 control the recording / reproducing element 121 (electromagnetic actuator 123) that is an external control target. The device 125 may be used. Of course, the electromagnetic actuator 123 may be included in the control device 125.

  Furthermore, the control parameter generation unit 124 may be a single device (control parameter generation device) that generates control parameters used in the external control unit 122.

  The series of processes described above can be executed by hardware or can be executed by software. In this case, for example, a personal computer as shown in FIG. 25 may be configured.

  In FIG. 25, the CPU 401 of the personal computer 400 executes various processes according to a program stored in the ROM 402 or a program loaded from the storage unit 413 to the RAM 403. The RAM 403 also appropriately stores data necessary for the CPU 401 to execute various processes.

  The CPU 401, ROM 402, and RAM 403 are connected to each other via a bus 404. An input / output interface 410 is also connected to the bus 404.

  The input / output interface 410 includes an input unit 411 including a keyboard and a mouse, a display including a CRT display and an LCD, an output unit 412 including a speaker, a storage unit 413 including a hard disk, a modem, and the like. A communication unit 414 is connected. The communication unit 414 performs communication processing via a network including the Internet.

  A drive 415 is connected to the input / output interface 410 as necessary, and a removable medium 421 such as a magnetic disk, an optical disk, a magneto-optical disk, or a semiconductor memory is appropriately mounted, and a computer program read from them is It is installed in the storage unit 413 as necessary.

  When the above-described series of processing is executed by software, a program constituting the software is installed from a network or a recording medium.

  For example, as shown in FIG. 25, this recording medium is distributed to distribute a program to a user separately from the apparatus main body, and includes a magnetic disk (including a flexible disk) on which a program is recorded, an optical disk ( It is only composed of removable media 421 consisting of CD-ROM (compact disc-read only memory), DVD (including digital versatile disc), magneto-optical disc (including MD (mini disc)), or semiconductor memory. Rather, it is composed of a ROM 402 on which a program is recorded and a hard disk included in the storage unit 413, which is distributed to the user in a state of being incorporated in the apparatus main body in advance.

  In the present specification, the step of describing the program recorded on the recording medium is not limited to the processing performed in chronological order according to the described order, but is not necessarily performed in chronological order. It also includes processes that are executed individually.

  Further, in this specification, the system represents the entire apparatus constituted by a plurality of devices (apparatuses).

  In the above, the configuration described as one device may be divided and configured as a plurality of devices. Conversely, the configurations described above as a plurality of devices may be combined into a single device. Of course, configurations other than those described above may be added to the configuration of each device. Furthermore, if the configuration and operation of the entire system are substantially the same, a part of the configuration of a certain device may be included in the configuration of another device. That is, the embodiment of the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the gist of the present invention.

It is a figure which shows the example of the model of a controller. It is a figure which shows the example of an open loop frequency characteristic. It is a block diagram which shows the structural example of the optical disk recording / reproducing apparatus to which this invention is applied. It is a block diagram which shows the detailed example of the structure regarding control of a pickup. It is a block diagram which shows the example of the digital control model which shows the control system of FIG. It is a block diagram which shows the other example of the digital control model which shows the control system of FIG. It is a figure which shows the example of an open loop frequency characteristic. It is a figure which shows the example of the model of the controller to which this invention is applied. FIG. 5 is a block diagram illustrating a detailed configuration example of a control parameter calculation unit in FIG. 4. It is a figure which shows the example of the calculation result of the control parameter for every pole position. It is a figure which shows the other example of the calculation result of the control parameter for every pole position. It is a figure which shows the further another example of the calculation result of the control parameter for every pole position. It is a figure which shows the example of the calculation result of the zero cross frequency for every pole position, and a phase margin. It is a graph which shows the example of the relationship between the normalized zero cross frequency and a phase advance frequency ratio. It is a graph which shows the example of the relationship between the normalized zero cross frequency and a phase lag frequency ratio. It is a graph which shows the example of the relationship between the normalization zero cross frequency and a phase margin. It is a graph which shows the example of the relationship between a standardized zero cross frequency and a condition stable gain margin. It is a flowchart explaining the example of the flow of a parameter setting process. It is a flowchart explaining the example of the flow of a frequency characteristic measurement control process. It is a flowchart explaining the example of the flow of a phase margin adjustment process. FIG. 5 is a block diagram illustrating another detailed configuration example of the control parameter calculation unit in FIG. 4. It is a flowchart explaining the example of the flow of a parameter calculation process. FIG. 23 is a flowchart following FIG. 22 for explaining an example of the flow of parameter calculation processing. 24 is a flowchart following FIG. 23 for explaining an example of the flow of parameter calculation processing. It is a block diagram which shows the structural example of the personal computer to which this invention is applied.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 100 Optical disk recording / reproducing apparatus, 101 System controller, 104 Servo control part, 106 Optical head part, 107 Optical disk, 121 Recording / reproducing element, 122 Control part, 123 Electromagnetic actuator, 124 Control parameter production | generation part, 143 Control arithmetic circuit, 152 Control parameter Calculation unit, 201 low frequency booster, 202 phase advance / delay filter, 204 controller gain, 211 input reception unit, 212 es calculation unit, 213 bs calculation unit, 214 abe calculation unit, 215 measurement control unit, 216 Kpp determination unit, 217 Gain margin display control unit, 218 Phase margin display control unit, 219 Parameter setting unit, 317 Gain margin adjustment unit, 318 Phase margin adjustment unit

Claims (9)

The low-frequency emphasis calculating means for performing low-frequency emphasis of the control system, and the phase advance / delay arithmetic means for realizing the phase advance / delay characteristics of the control system, and the low-frequency emphasis calculating means and the phase connected in parallel to each other Control calculation means for calculating a control output for controlling the operation of the angle or position of the control target toward the target value by the advance / delay calculation means;
Control parameter calculation means for calculating, as control parameters, the zero point and pole of the phase advance / lag characteristic from the zero cross frequency of the open loop frequency characteristic of the control system,
The information processing apparatus that calculates the control output using the zero point and pole of the phase advance / lag characteristic calculated as the control parameter by the control parameter calculation unit. The information processing apparatus according to claim 1, wherein the control parameter calculation unit calculates the zero point of the phase advance / lag characteristic by multiplying the zero cross frequency, the phase advance frequency ratio, and a predetermined coefficient. The information processing apparatus according to claim 2, wherein a range of a value of the phase advance frequency ratio is 0.43 to 0.48. The information processing apparatus according to claim 1, wherein the control parameter calculation unit calculates the pole of the phase lead / lag characteristic by multiplying the zero cross frequency, the phase lag frequency ratio, and a predetermined coefficient. The information processing apparatus according to claim 4, wherein a range of the value of the phase delay frequency ratio is 3 to 16. 6. The information processing apparatus according to claim 1, wherein the control parameter calculation unit discretizes a cutoff frequency of the low-frequency emphasis calculation unit and a zero point and a pole of the phase advance / lag characteristic according to a sampling frequency. The phase advance of the low-frequency emphasis calculation unit that performs low-frequency emphasis of the control system, and the phase advance / delay calculation unit that realizes the phase advance / delay characteristic of the control system, which are connected in parallel with each other, The zero point and pole of the delay characteristic are calculated as control parameters from the zero cross frequency of the open loop frequency characteristic of the control system,
The control calculation means uses the zero point and pole of the phase advance / delay characteristic calculated as a control parameter, and the low frequency emphasis calculation unit and the phase advance / delay calculation unit connected in parallel with each other An information processing method for calculating a control output for controlling the movement of a position toward a target value. Computer to process information,
A zero point and a pole of the phase advance / delay characteristics of a low range emphasis calculation unit that performs low frequency emphasis of the control system and a phase advance / delay calculation unit that realizes the phase advance / delay characteristic of the control system, connected in parallel to each other Control parameter calculation means for calculating from the zero cross frequency of the open loop frequency characteristics of the control system as a control parameter,
Using the zero point and pole of the phase advance / delay characteristic calculated as a control parameter, the low-frequency emphasis calculation unit and the phase advance / delay calculation unit connected in parallel to each other change the angle or position of the control target to the target value. A program for functioning as a control calculation means for calculating a control output for controlling the operation. A recording / reproducing element for writing / reading data to / from a disk-shaped recording medium;
Driving means for driving the recording / reproducing element in a horizontal direction or a vertical direction with respect to a recording surface of the disc-shaped recording medium;
An error signal detecting means for detecting an error signal proportional to a difference between a position where the recording / reproducing element should perform recording / reproducing and an actual position;
Control calculation means for performing a control calculation on the error signal detected by the error signal detection means using a control parameter and calculating a control output for reducing the absolute value of the error signal;
Control parameter calculation means for calculating a control parameter for realizing servo performance required for a servo control system including the drive means, the error signal detection means, and the control calculation means;
The control calculation means is
Control arithmetic means for performing low frequency emphasis;
Control arithmetic means for realizing phase advance / delay characteristics, and the control arithmetic means and the control arithmetic means are connected in parallel to each other,
The control parameter calculation means calculates a zero point and a pole of the phase advance / lag means from a zero cross frequency of an open loop frequency characteristic which is an index representing the servo performance.

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