JP2000039921A - Positioning controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the positioning controller equipped with an H∞ controller which satisfies robust control performance and is not conservative for a spring- supported actuator. SOLUTION: The position controller has a carriage 101 which is supported by a spring 102, a linear encoder 104 which detects the position of the carriage 101, a weight of uncertainty which specifies robust stability and represents the uncertainty of a control system, a weight of control performance which specifies control performance as disturbance suppression effect, and the H∞ controller which has an H∞ norm, regarding a generalized plant including a mathematical model for the carriage 101, below a specific value and satisfies the robust control performance and is equipped with a positioning control controller 105 which outputs a manipulated variable based upon a target position and the position signal of the carriage 101 and a driver 106 which drives the carriage 101 with the manipulated variable, and the H∞ controller is so designed that the weight of uncertainty of the control system where the nonlinearity, etc., of the spring 102 is brought into consideration is a weight of an actual number (noncomplex number).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention mainly uses a focus following servo by a two-stage actuator for coarse movement and fine movement, and is applicable to, for example, a WTL (curved axis toroidal lens) shape measuring device, an optical disk driver, a robot, and the like. The present invention relates to a positioning control device.

[0002]

2. Description of the Related Art Conventionally, as reference technical documents related to the present invention, for example, a patent is disclosed in which an actuator of a focus servo is supported by a spring and the force of the spring is reduced by feedforward to reduce the influence of the spring force on the following performance. Japanese Unexamined Patent Publication No. Hei 8-47785, entitled "Shape Measuring Apparatus and Method" of Japanese Patent Publication No. 2638157, in which an H∞ controller is used for stabilizing a posture change of an articulated robot, limited to a focus following servo of a laser processing machine. Of Japanese Patent Application Laid-Open No. 9-223, which designs an H∞ controller limited to a vibration control device.
No. 04 discloses a "vibration suppression device".

As a reference technical document related to H∞ control, “Robust control performance and μ-synthesis” (System / Control / Information. Vol. 37, No. 2 pp. 93)
-101, 1993), and "From LGG to H∞"
(Measurement and Control, Vol. 29, No. 2, 1990, 2
Month).

[0004]

However, the prior art as described above has the following problems. In Japanese Patent No. 2638157, “Shape Measuring Apparatus and Method”, when a spring is used, the spring constant changes over time and affects feedforward, so that the control system becomes unstable. The above method cannot be used for springs that are likely and have high non-linearity. In addition, the stability and control performance of the control system are not taken into consideration when other parameters fluctuate.

Further, in the "autofocus system for laser beam machine" disclosed in Japanese Patent Application Laid-Open No. 8-47785, when the weight relating to the stability performance is considered as the weight of the uncertainty, the weight relating to the stability performance is the frequency weight. Therefore, it is the weight of a complex number considering not only the gain fluctuation but also the phase fluctuation. However, since the variation of the parameters of the real machine is mainly the variation of the real number, which is only the variation of the gain, the controller obtained by using the complex number weight may be a conservative solution. Furthermore, in the "vibration suppression device" disclosed in Japanese Patent Application Laid-Open No. 9-22304, since the frequency weight is used in the same manner as described above, there is a possibility that the controller becomes a conservative solution.

In the case of a coarse / fine actuator, H
(4) If the controller is designed as a multi-input / multi-output system model, the method of separating the coarse and fine motion bands will become an issue. Generally, it is necessary to add a frequency weight for band separation. Furthermore, in the case of designing a multi-input / multi-output system, the dimensions of the mathematical model of the generalized plant become large, and thus problems such as a decrease in the calculation accuracy of the control system CAD and a long calculation time occur. Further, there are also problems such as the inability to suppress minute vibrations generated by the spring-supported coarse motion and the inability to suppress mechanical resonance and noise at high frequencies.

The present invention has been made in view of the above, and provides a positioning control device having an H∞ controller that satisfies robust control performance in a spring-supported actuator and is not conservative. As a first object.

It is a second object of the present invention to provide a positioning control device provided with an H∞ controller in which robust control performance is further improved by improving the damping of a spring-supported actuator.

It is a third object of the present invention to provide a positioning control device which includes an H.infin. Controller which is robust against focus fluctuations and uses a focus signal.

It is a fourth object of the present invention to provide a positioning control device using a focus signal provided with an H∞ controller that satisfies the performance of following the surface shape of the object to be measured.

[0011] In addition, by using a two-stage servo of coarse and fine movement, the control band is expanded to improve the tracking performance.
A fifth object is to provide a positioning control device using a focus signal, which includes a controller.

[0012] Further, positioning using a focus signal provided with an H∞ controller that satisfies a high-precision tracking performance with respect to the surface shape of an object to be measured and suppresses minute vibration generated by spring-supported coarse movement by fine movement. A sixth object is to provide a control device.

[0013] In addition, in order to suppress mechanical resonance and noise at high frequencies, a low pass filter is added to a frequency fishing season with high control performance to obtain an H∞ controller that suppresses the effects of high frequencies. The purpose of 7.

[0014]

According to a first aspect of the present invention, there is provided a positioning control apparatus comprising: an actuator supported by a spring; and a position detecting means for detecting a position of the actuator. , Robust stability, and uncertainty weight indicating uncertainty in the control system, control performance weight specifying control performance which is a disturbance suppression effect, and a mathematical model of the actuator. A positioning control means for outputting an operation amount based on a target position inputted in advance and a position signal from the position detection means, comprising an H∞ controller which satisfies a robust control performance with H∞ norm being equal to or less than a predetermined value; And a driving unit for driving the actuator in accordance with an operation amount from the positioning control unit. Oite the H∞ controller, the weight of uncertainty of the control system with Nonlinear etc. of the spring for supporting the actuator, in which are designed as a weight of the real is non-complex.

Further, the positioning control device according to the present invention further comprises speed detecting means for detecting the speed of the actuator from a position detection signal from the position detecting means, and a speed value detected by the speed detecting means. Is multiplied by a predetermined value, minor correction is obtained to the operation amount of the positioning control means to obtain a correction operation amount, and the correction operation amount is supplied to the driving means.

According to a third aspect of the present invention, the positioning control device further comprises a detecting means for optically detecting a distance between the actuator and the object to be measured and generating a focus signal on the actuator. , The H∞ controller calculates the weight of the uncertainty of the control system in consideration of the nonlinearity and the like of the spring supporting the actuator, and the uncertainty of the focus signal that changes depending on the inclination angle of the surface shape of the device under test. The weight is designed as a non-complex real number weight.

Further, in the positioning control device according to the fourth aspect, a weight of a frequency having a gain larger than a gain required at a predetermined frequency is set as a weight of control performance, and the weight of the control performance is determined with respect to the surface shape of the object to be measured. At a predetermined scanning speed, a tracking operation in which the position deviation is equal to or less than a predetermined value is executed.

According to a fifth aspect of the present invention, there is provided a positioning control device, comprising: a coarse movement actuator supported by a spring; a fine movement actuator having a high response frequency and a small movable range with respect to the coarse movement actuator; A fine movement position detecting means for detecting a moving amount of the fine movement actuator and outputting a fine movement position signal; a focus signal generating means for optically detecting an interval between the fine movement actuator and the object to be measured to generate a focus signal; A fine movement controller that outputs a fine movement operation amount based on the input target position and the focus signal and executes fine movement positioning control; a driving unit that drives the fine movement actuator according to the fine movement operation amount; Coarse movement controller that outputs the coarse operation amount based on And a generalization including a weight of uncertainty indicating robustness and representing uncertainty in the control system, a weight of control performance specifying control performance as a disturbance suppression effect, and a mathematical model of the actuator. In the positioning control device in which the H∞ norm relating to the plant is equal to or less than a predetermined value and the H∞ controller that satisfies the robust control performance is provided,
The coarse motion controller, a mathematical model of the coarse motion actuator, a mathematical model of the fine motion actuator,
The apparatus further includes a fine movement H を controller which is designed so that the weight of the uncertainty of the focus signal, which changes according to the inclination angle of the surface shape of the device under test, is the weight of a non-complex real number.

Further, in the positioning control device according to the sixth aspect, the fine movement H ， controller may be configured such that the object to be measured required for the fine movement has a predetermined scanning speed and a predetermined position with respect to the surface shape. A frequency weight that gives a gain larger than a gain at a predetermined frequency required to follow the deviation or less is set as a weight for the control performance of the fine movement, and the weight of the control performance for the fine movement and the coarse weight used in designing the coarse movement controller are used. The weight of the dynamic control performance is designed to be included in the generalized plant.

Further, in the positioning control device according to the present invention, the fine movement H∞ controller has a low-pass filter added to a frequency region having a high control performance weight.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a positioning control device according to the present invention will be described in detail with reference to the accompanying drawings.

[First Embodiment] FIG. 1 is an explanatory diagram showing the configuration of a positioning control device according to a first embodiment of the present invention. In the figure, the spring 101 is a carriage (actuator) 102 weight m ₁ which supports the carriage 101, the voice coil motor 103 for driving the carriage 101, 104 linear as a position detecting means for detecting the amount of movement of the carriage 101 An encoder 105 is a positioning controller as positioning control means for outputting an operation amount from a target position and a position detection signal from the linear encoder 104, and 106 is a positioning controller 1
The driver is a driving unit that outputs a motor driving current to the voice coil motor 103 based on the operation amount output from the control unit 05.

In the above configuration, the carriage 101 having a weight of m ₁ is supported by a spring 102 and is driven by a voice coil motor 103. At this time, the amount of movement of the carriage 101 is detected by the linear encoder 104, and a corresponding position detection signal is output from the linear encoder 104.

Next, the positioning controller 105
Outputs an operation amount to the driver 106 from the target position and the position detection signal supplied from the linear encoder 104. The driver 106 supplies a motor drive current corresponding to the operation amount given from the positioning controller 105 to the voice coil motor 103. This gives
Thrust f ₁ occurs.

Here, the motor thrust constant of the voice coil motor 103 is Kn, the motor drive current output from the driver 106 and the current value when the operation amount of the positioning controller 105 are equivalent are u ₁ , the voice coil motor The motor thrust of 103 is f ₁ and the spring constant of the spring 102 is k
₁ , the attenuation coefficient is C ₁ , the weight of the carriage 101 is m ₁ ,
When the amount of movement of the carriage 101 and x _1, nominal mathematical model of the actuator, the following (1) is represented by the formula (2).

[0026]

(Equation 1)

Further, when the above equations (1) and (2) are represented by a transfer function _{Gcn om} with an input u ₁ and an output x ₁ , the following equations are obtained.

[0028]

(Equation 2)

When the above equation is rewritten, the following equation (3) is obtained.

[0030]

(Equation 3)

Here, the following three parameters (Equation 4)
think about.

[0032]

(Equation 4)

Consider a case where the above three parameters have the following additive perturbations (parameter variations). Perturbation of attenuation term γ ₁ Perturbation of resonance frequency term γ ₂ Perturbation of proportional term γ ₃

First, a conventional design method will be described. Conventionally, uncertainty (Uncertainty) as shown in FIG. 16 is covered. The frequency weight of the uncertainty expressed as the transfer function of (Expression 5) and the frequency weight of the control performance (here, (Expression 6, Expression 7)
And a generalized plant represented in FIG. 17 from the nominal mathematical model of the actuator. Further, calculation of an H∞ controller in which the H∞ norm is equal to or less than a predetermined value in the generalized plant, complex μ-analysis, reconstruction of a model using a D scaling matrix, and calculation of the H∞ controller again Complex iterative μ design (Complex
μ-synthesis, DK iteratio
n), the H∞ norm is 1 or less, and the complex μ
The H∞ controller K _c has been designed such that the value of the structured singular value μ obtained by the analysis is 1 or less.

[0035]

(Equation 5)

[0036]

(Equation 6)

[0037]

(Equation 7)

In FIG. 17, for convenience of calculation, each frequency weight is divided into two parts, input and output (subscripts l and r). The perturbation Δ in the figure is | Δ _OO |
A complex parameter satisfying ≦ 1.

However, the H∞ controller designed by the above method is a controller that takes into account the variation in the complex number domain even though the parameter variation in the actual machine is the variation in the real number domain. There is a possibility of becoming. In other words, if there are only real number fluctuations, there is a margin of stability in comparison with the case of complex number fluctuations, and the solution may be a solution that may have improved performance.

Therefore, in the present invention, the following equation (4) including perturbation in parameters is used.

[0041]

(Equation 8)

The block diagram excluding the perturbation as shown in FIG. 2 is represented by the following determinant.

[0043]

(Equation 9)

Therefore, the block diagram of the actuator including the additive perturbation is as shown in FIG. Also,
The H∞ controller K _c 402 whose structured singular value obtained by the above-mentioned complex μ design is not less than 1 is connected to the generalized plant 402 of FIG. 4 and the perturbation is mixed μ analysis (Mixed μ -Analysis).
Then, the complex μ design and the mixed μ analysis are repeatedly executed to obtain an H∞ controller that makes the structured singular value μ of the mixed μ analysis equal to or less than 1. By using these techniques, a positioning control device that satisfies the robust control performance can be provided.

[Second Embodiment] The basic configuration of the positioning control device and the design method of the controller according to the second embodiment are the same as those of the first embodiment described above.
Here, an example in which a speed detection function is provided and the detected speed is used will be described.

FIG. 5 is an explanatory diagram showing the configuration of a positioning control device according to Embodiment 2 of the present invention. In contrast to the configuration of FIG. 1 described above, a speed detecting section 501 as speed detecting means is provided.
And a multiplier 502 are added.

In the positioning control device shown in FIG. 5, the position detection signal of the carriage 101 detected by the linear encoder 104 is input to the speed control unit 501 in parallel with the feedback to the positioning control controller 105, where the speed is detected. A signal is detected.

[0048] The detected speed signal, any gain K _v is multiplication, it is a minor back to which is the output manipulated variable of the positioning controller 105. Then, the feedback amount is subtracted from the operation amount, the value is supplied to the driver 106, and the driver 106 drives the voice coil motor 103 by supplying a motor drive current corresponding to the value, whereby the carriage 101 is driven. You.

The mathematical model of the carriage 101 in this case is represented by the following transfer function (5).

[0050]

(Equation 10)

As can be seen from the above equation (5), since K _v is included in the attenuation term, the attenuation can be changed by selecting this K _v . Therefore, by using the mathematical model of the carriage of the above formula (5) as a nominal model in the positioning control device of the first embodiment, it is possible to improve the response of the actuator having poor damping. A robust positioning control device can be provided.

[Embodiment 3] FIG. 6 is an explanatory view showing a configuration of a positioning control apparatus according to Embodiment 3 of the present invention. In contrast to the configuration of FIG.
An optical stylus 601 is added as a detection unit having a focus signal generation function of optically detecting a distance between the carriage 02 and the carriage 101 and generating a focus signal.

In the positioning control device shown in FIG. 6, the focus signal from the optical stylus 601 is used as a position signal, and the position signal from the focus signal and the amount of focus deviation are designated. 1
05 is input. Here, the positioning controller 105 outputs the operation amount. The driver 106 supplies a motor drive current corresponding to the operation amount to the voice coil motor 103.
To drive the carriage 101.

At this time, the distance between the optical stylus and the work 602 is optically detected by the optical stylus 601. The carriage 101 keeps the distance between the optical stylus 601 and the work 602 constant (just focus), and follows the surface shape of the work 602 so that the focus shift becomes _xf = 0.

Embodiment 1 or Embodiment 2 described above
In the above, the uncertainties were set as the damping term, the resonance frequency term, and the proportional term of the mathematical model of the actuator.
Now, consider the uncertainty of the focus signal in addition to the three uncertainties.

The focus signal fluctuates depending on the inclination angle of the workpiece surface shape. The fluctuation range is defined as focus uncertainty. The uncertainty in the complex μ design is designed as a frequency weight (Equation 5) including the uncertainty of the spring-supported actuator and the aforementioned focus uncertainty.

It is assumed that the uncertainty of the focus in the mixed μ analysis is an additive perturbation in the real number region. Focus gain Normally set to 1 Focus perturbation γ ₄

In addition to the perturbation described in the first embodiment, the focus signal is represented by the following determinant (Equation 11).

[0059]

[Equation 11]

In this case, the block diagram of FIG. 3 in the first embodiment is represented by FIG. 7, and the generalized plant of FIG. 4 is represented by FIG. Therefore, in the generalized plant of FIG. 8, by providing a controller by repeating complex μ design and mixed μ analysis similarly to the first embodiment, a positioning control device using a focus signal satisfying robust control performance is provided. can do.

[Fourth Embodiment] In the fourth embodiment,
A method of determining the weight of control performance in the above-described positioning control device according to the third embodiment will be described.

Depending on the workpiece surface shape and the scanning speed,
The frequency and magnitude to follow are determined. Here, the following (Equation 12) is used.

[0063]

(Equation 12)

Further, the allowable position deviation at the time of following is given by the following (Equation 1).
Assuming 3), the gain required at the frequency (Equation 14) is given by the following equation (6), from which the closed loop gain of the control system required for following is obtained.

[0065]

(Equation 13)

[0066]

[Equation 14]

[0067]

(Equation 15)

At the frequency (Equation 14), the second-order gain tolerance frequency that becomes the following (Equation 16) is expressed by the following equation (7).

[0069]

(Equation 16)

[0070]

[Equation 17]

Therefore, near the frequency ω _s ,
The frequency weight of the control performance is designed to cover the gain of 8).

[0072]

(Equation 18)

The frequency weight of the control performance (Equation 19) is designed as described above (see FIG. 9), and the H∞ controller is designed by the method of the third embodiment, so that the focus signal satisfying the robust control performance is obtained. Can be provided.

[0074]

[Equation 19]

[Fifth Embodiment] FIG. 10 is an explanatory diagram showing the configuration of a positioning control device according to a fifth embodiment of the present invention. In the figure, a coarse actuator 1001 is supported in the direction of gravity by a spring 1003. In addition, gravity is compensated, and the air slider 1005 is restrained. The coarse movement actuator 1001 is configured to be driven by a voice coil motor 1008.

On the coarse movement actuator 1001, a fine movement actuator 1002 driven by a piezoelectric element and a capacitance sensor 1009 for detecting the position of the fine movement actuator 1002 with respect to the coarse movement actuator 1002 are mounted.

On the fine movement actuator 1002, an optical stylus 1004, which is a non-contact sensor for optically detecting the distance from the work 1007, is mounted. The fine actuator 1002 is driven in accordance with the focus signal from the optical stylus 1004 so that the distance between the optical stylus 1004 and the workpiece 1007 becomes a predetermined value, and the relative position between the fine actuator 1002 and the coarse actuator 1001 is determined. Thus, a two-stage servo autofocus mechanism for driving the coarse movement actuator 1001 in accordance with the position signal of the capacitance sensor 1009 so as to have the value of?

In this apparatus, the surface shape is scanned by the scanning actuator 1006 in the state where the focus control is performed, and the copying operation is performed based on the workpiece surface shape to measure the workpiece surface shape.

FIG. 11 is an explanatory diagram modeling the positioning control device configured as shown in FIG. In the figure,
The coarse actuator 1100 is supported by a spring 1101, a fine actuator 1102 is mounted on the coarse actuator 1100, and the fine actuator 1100 is further mounted.
An optical stylus 1103 is mounted on 102.

Further, reference numeral 1104 denotes a coarse actuator 11
00, a piezo actuator for driving the fine actuator 1102, 1106, a linear encoder for detecting the amount of movement of the coarse actuator 1100, 1107, the relative position between the coarse actuator 1100 and the fine actuator 1101. A capacitive sensor 1108 for detecting the speed of the coarse actuator 1100;
Is a multiplier for multiplying a predetermined gain K _V , 1110 is a coarse motion controller described later, 1111 is a fine motion controller described later, 1112 is a coarse motion driver described later, 1113 is a piezo driver for driving a piezo actuator 1005, and 1114 is a work. is there.

In the model configuration shown in FIG. 11, first, a focus signal from the optical stylus 1103 is input to the fine movement controller 1111 as a position signal. The fine movement controller 1111 compares the focus signal with a target position (here, 0), and determines that the focus signal is a predetermined value (just).
The manipulated variable is output so as to be focused. This operation amount is input to the piezo driver 1113, and the piezo actuator 1005 is driven based on the operation amount.

A position signal of the capacitance sensor 1107 for detecting the relative position between the coarse actuator 1100 and the fine actuator 1101 is input to the coarse controller 1110, and the relative position between the coarse actuator 1100 and the fine actuator 1101 is determined. The manipulated variable is output to be a value.

At this time, the moving amount of the coarse movement actuator 1100 is detected by the linear encoder 1106, and the speed detection unit 1108 detects the movement amount of the coarse movement actuator 1100.
The speed 100 is detected, multiplied by a predetermined gain K _V , and minor feedback is provided to the output of the coarse motion controller 1110. This minor feedback improves the response of the coarse actuator 1100 with poor damping.

The value obtained by subtracting the feedback amount from the operation amount is input to coarse movement driver 1112. Therefore, the coarse movement driver 1112 supplies a motor drive current to the voice coil motor 1104 to drive the coarse movement actuator 1100. As described above, by adopting the two-stage actuator, the control band can be widened, so that the control performance is improved.

The controller is designed using the same method as in the first embodiment. The mathematical model of the coarse motion actuator 1100 is the above-described equation (5). The mathematical model of the fine movement actuator 1101 is expressed by the following equation (8).

[0086]

(Equation 20)

In the complex μ design, the uncertainty of the fine movement actuator 1101 is represented by a multiplicative perturbation as only the focus uncertainty, and is defined as a frequency weight (Equation 21). Further, the control performance is the same as the frequency weight (equation 22) equivalent to the control performance of the coarse motion actuator 1100 (equation 19 obtained in the fourth embodiment), and the frequency weight (equation 22) having a higher response band than the coarse motion actuator 1100. 23).

[0088]

(Equation 21)

[0089]

(Equation 22)

[0090]

(Equation 23)

The frequency weights, the mathematical model of the fine actuator 1101 in the above equation (8), the mathematical model of the coarse actuator 1100 in the above equation (5), and the coarse controller K _C obtained in advance are shown in FIG. A generalized plant 1200 as shown in FIG.

In the generalized plant 1200 shown in FIG. 12, for the sake of calculation, the frequency weight is divided into two of input and output (subscripts l and r). In the generalized plant, a complex μ design is performed to design an H∞ controller K _f 1201.

Next, a mixed μ analysis of the control system designed by the above method is performed. Variations of each parameter and focus of the coarse actuator 1100 are regarded as variations in the real number region (see Embodiments 1 and 3), and a generalized plant is represented by a block diagram shown in FIG.

[0094] Generally plant M (s) shown in FIG. 13 combines the fine motion controller 1111K _f determined at the design coarse controller K _C and the complex mu, performing a mixed mu analysis to analyze the uncertainty in real area . Complex μ design and mixed μ
The analysis is repeatedly executed, and an H∞ controller for fine movement in which the structured singular value μ of the mixed μ analysis is 1 or less is designed.

Therefore, the positioning control apparatus which satisfies the robust control performance and uses the high-performance focus signal can be provided by the fine movement H∞ controller designed by the above method.

[Sixth Embodiment] In the sixth embodiment,
A gain (Equation 26) necessary for tracking is calculated from the workpiece surface shape (see Equation 24) and the allowable position deviation (Equation 25) in the same manner as in the above-described fourth embodiment, and the frequency (Equation 27) is used to calculate (Equation 27). 28) is obtained.

[0097]

(Equation 24)

[0098]

(Equation 25)

[0099]

(Equation 26)

[0100]

[Equation 27]

[0101]

[Equation 28]

Here, assuming that the required closed loop gain is (Equation 29) below, the frequency weight (Equation 23) of the control performance that covers the band near the band to be controlled is obtained.

[0103]

(Equation 29)

The frequency weight (Equation 23) is used in the method of the fifth embodiment to design an H∞ controller for fine movement. This makes it possible to provide a positioning control device that satisfies the robust control performance and uses a high-performance focus signal.

[Embodiment 7] In the above-described Embodiment 6, in order to suppress the effects of high-frequency mechanical resonance and noise, generally, the frequency with a high uncertainty weight is increased. In addition, a frequency weight (equation 23) of the control performance in the form of adding a low-pass filter for suppressing the frequency having a high control performance and a high frequency weight is designed (see FIG. 14).

For example, as shown in the following (Equation 30), a low-pass filter having a cutoff frequency ω _LPF is added.

[0107]

[Equation 30]

Generally, the H∞ controller has a gain larger than the frequency weight of the given control performance. Therefore, the sensitivity at a high frequency can be suppressed by positively lowering the frequency region where the frequency weight of the control performance is high.

[0109]

As described above, according to the positioning control apparatus (claim 1) of the present invention, in the spring-supported actuator, the complex μ design is performed by considering the parameter variation of the spring model as a variation in the real number domain.・ Since the mixed μ analysis is repeatedly executed, it is possible to provide a positioning control device which satisfies the robust control performance and has a non-conservative H∞ controller.

According to the positioning control device of the present invention (claim 2), in addition to the effect of claim 1, the moving speed of the actuator is detected, and the speed is multiplied by a predetermined value to output the output of the controller. The actuator is used as an actuator mathematical model including minor feedback, so that the damping performance of an actuator with poor damping can be improved.

According to the positioning control device of the present invention (claim 3), in addition to the effects of claim 1 or claim 2, the distance between the actuator and the object to be measured is optically detected and the focus is adjusted. Since a means for generating a signal is provided, a focus signal is used as a position signal, and a target system is controlled to follow a surface shape of an object to be measured by using a target position as a predetermined value. In order to design an H∞ controller using the weight of the uncertainty of the above and the weight of the uncertainty of the focus signal that changes according to the inclination angle of the surface shape of the device under test as the weight of a real number that is a non-complex number, the fluctuation of the focus signal Also, it is possible to provide a positioning control device using a focus signal that satisfies the robust control performance.

According to the positioning control device of the present invention (claim 4), in addition to the effect of claim 3, the weight of the frequency at which the gain becomes larger than the gain required at the predetermined frequency is determined by the control performance. An H∞ controller that satisfies the performance of following the surface shape of the object to be measured is used to execute the following operation in which the positional deviation is equal to or less than a predetermined value at a predetermined scanning speed with respect to the surface shape of the object to be measured. A positioning control device using a focus signal can be provided.

According to the positioning control device of the present invention (claim 5), in addition to the effect of claim 3, a two-stage servo structure of coarse movement and fine movement is provided, so that the control band is widened and the tracking is performed. It is possible to provide a positioning control device using a focus signal provided with an H∞ controller with improved performance, and to design a classical coarse and fine motion controller separately for the design of the H∞ controller. , Means for separating the bands can be provided.

According to the positioning control device of the present invention (claim 6), in addition to the effect of claim 5, a fine movement H∞ controller can be used for the surface shape of the object to be measured required for fine movement. A frequency weight having a gain larger than a gain at a predetermined frequency required for following at a predetermined scanning speed and a predetermined position deviation or less is set as the weight of the fine movement control performance; Since the weight of the coarse motion control performance used in the design of the coarse motion controller is included in the generalized plant and designed, the high-precision follow-up performance to the surface shape of the DUT is satisfied, and the spring-supported coarse motion The present invention can provide a positioning control device using a focus signal including an H {H} controller that suppresses minute vibrations caused by fine movement.

According to the positioning control device of the present invention (claim 7), in addition to the effect of claim 6, in order to suppress mechanical resonance and noise at high frequencies, a frequency region with a high control performance weight is required. By developing an H∞ controller that suppresses the effects of high frequencies by adding a low-pass filter, a positioning controller that is resistant to noise and high-order resonance can be provided.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram illustrating a configuration of a positioning control device according to a first embodiment of the present invention.

FIG. 2 is a block diagram in which a perturbation is taken out of the positioning control device in FIG. 1;

FIG. 3 is a block diagram of an actuator including an additive perturbation of the positioning control device according to the first embodiment of the present invention.

FIG. 4 is a block diagram showing a generalized plant of the positioning control device according to the first embodiment of the present invention.

FIG. 5 is an explanatory diagram showing a configuration of a positioning control device according to Embodiment 2 of the present invention.

FIG. 6 is an explanatory diagram showing a configuration of a positioning control device according to Embodiment 3 of the present invention.

FIG. 7 is a block diagram of an actuator including an additive perturbation of a positioning control device according to Embodiment 3 of the present invention.

FIG. 8 is a block diagram showing a generalized plant of a positioning control device according to Embodiment 3 of the present invention.

FIG. 9 is a graph showing an example of determining a control performance weight of a positioning control device according to Embodiment 4 of the present invention.

FIG. 10 is an explanatory diagram showing a configuration of a positioning control device according to Embodiment 5 of the present invention.

FIG. 11 is an explanatory diagram showing a model of the positioning control device of FIG. 10;

FIG. 12 is a block diagram showing a generalized plant of a positioning control device according to Embodiment 5 of the present invention.

FIG. 13 is a block diagram according to a fifth embodiment of the present invention.

FIG. 14 is a block diagram showing a generalized plant of a positioning control device according to Embodiment 5 of the present invention.

FIG. 15 is a graph showing an example in which a low-pass filter is added to the positioning control device according to Embodiment 7 of the present invention to determine control performance weights.

FIG. 16 is a graph showing an example of determining a control performance weight of a conventional positioning control device.

FIG. 17 is a block diagram showing a generalized plant of a conventional positioning control device.

[Explanation of symbols]

 101 Carriage 102, 1003, 1101 Spring 103, 1008, 1104 Voice coil motor 104, 1106 Linear encoder 105 Positioning controller 106 Driver 401 Generalized plant 402 H１ ， controller 501, 1108 Speed detector 601, 1004, 1103 Optical stylus 602 , 1007, 1114 Work 1001, 1100 Coarse motion actuator 1002, 1102 Fine motion actuator 1006 Scanning actuator 1009, 1107 Capacitance sensor 1110 Coarse motion controller 1111 Fine motion controller 1112 Coarse motion driver 1113 Piezo driver

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G05B 13/02 G05B 13/02 C 13/04 13/04

Claims (7)

[Claims] 1. An actuator supported by a spring, position detecting means for detecting the position of the actuator, a weight of uncertainty indicating robustness and representing uncertainty in a control system, and a disturbance suppression effect. An H∞ controller for a generalized plant including a control performance weight designating the control performance and a mathematical model of the actuator is not more than a predetermined value, and has an H∞ controller satisfying the robust control performance, and is input in advance. Positioning control comprising: positioning control means for outputting an operation amount based on a target position and a position signal from the position detection means; and driving means for driving the actuator in accordance with the operation amount from the positioning control means. In the apparatus, the H
(4) The positioning control device, wherein the controller is designed such that the weight of the uncertainty of the control system in consideration of the non-linearity of the spring supporting the actuator is set as the weight of a real number which is a non-complex number. 2. The apparatus according to claim 1, further comprising speed detecting means for detecting a speed of said actuator from a position detection signal from said position detecting means, multiplying a speed value by said speed detecting means by a predetermined value, and operating said positioning control means. 2. The positioning control device according to claim 1, wherein the correction operation amount is obtained by performing minor feedback on the amount, and the correction operation amount is supplied to the driving unit. And a detecting means for optically detecting an interval between the actuator and the object to be measured and generating a focus signal, wherein the H∞ controller supports the actuator. The weight of the uncertainty of the control system in consideration of the non-linearity of the spring, etc., and the weight of the uncertainty of the focus signal that changes depending on the inclination angle of the surface shape of the device under test are designed as real weights that are non-complex numbers. The positioning control device according to claim 1 or 2, wherein: 4. A weight of a frequency having a gain larger than a gain required at a predetermined frequency is set as a weight of control performance,
4. The positioning control device according to claim 3, wherein a tracking operation is performed at a predetermined scanning speed with respect to the surface shape of the object to be measured so that the positional deviation is equal to or less than a predetermined value. 5. A coarse movement actuator supported by a spring, a fine movement actuator having a high response frequency with respect to the coarse movement actuator and a small movable range, and detecting a movement amount of the fine movement actuator to generate a fine movement position signal. A fine movement position detecting means for outputting, a focus signal generating means for optically detecting an interval between the fine movement actuator and the object to be measured, and generating a focus signal; and a focus signal based on a previously input target position and the focus signal. A fine movement controller that outputs a fine movement operation amount and performs positioning control of the fine movement; a driving unit that drives the fine movement actuator in accordance with the fine movement amount; and a coarse movement operation amount that is output based on the fine movement position signal. A coarse movement controller that executes positioning control of the robot, specifies robust stability, and H∞ norm for a generalized plant including the uncertainty weight representing the uncertainty, the control performance weight for designating the control performance as the disturbance suppression effect, and the mathematical model of the actuator is less than or equal to a predetermined value, and is robust. In a positioning controller designed with an H∞ controller that satisfies the control performance,
The coarse motion controller, a mathematical model of the coarse motion actuator, a mathematical model of the fine motion actuator,
A positioning control device, comprising: a fine movement H∞ controller designed so that the weight of the uncertainty of the focus signal, which changes according to the inclination angle of the surface shape of the device under test, is a weight of a non-complex real number. 6. The fine movement H∞ controller has a predetermined frequency required to follow the surface shape of the object to be measured required for the fine movement at a predetermined scanning speed and at a predetermined position deviation or less. A frequency weight having a gain larger than the gain is set as the weight of the control performance of the fine movement, and the weight of the control performance of the fine movement and the weight of the control performance of the coarse movement used in designing the coarse movement controller are included in the generalized plant. The positioning control device according to claim 5, wherein the positioning control device is designed by: 7. The positioning control device according to claim 6, wherein the fine movement H∞ controller is provided with a low-pass filter in a frequency region having a high control performance weight.