JPH10141428A - Active vibration resistant device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve transmission characteristics of the vibration from a foundation which is installed. SOLUTION: The vibration of a vibration resistant base 31 supported by a support mechanism 32 is detected by a first vibration detection means 34 in a vibration removing base vibration feedback loop, and the vibration information obtained by amplifying by an amplifier 40 and then passing only necessary frequency band by a band-pass filter 41 is computed and processed by a feedback compensator 53 and is fed-back into an actuator 36 through a drive circuit 52. Moreover, in a floor vibration feed forward loop, the vibration of a foundation 33 which is installed is detected by a second vibration detection means 35, and the vibration information obtained by amplifying by an amplifier 46 and then passing only necessary frequency band by a band-pass filter 47 is digitalized by an A/D converter 48 and is converted into an analog signal by a D/A converter 50 as a feed forward control signal through a feed forward compensator 49 of an adaptive filter 44 so that the drive circuit 52 drives the actuator 36 by this signal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an active vibration isolator for mounting on precision equipment, such as an electron microscope or a semiconductor exposure apparatus, which greatly improves the transmission characteristics of vibration from a foundation such as a floor. It is about.

[0002]

2. Description of the Related Art As a vibration control method, there is a method in which an adaptive digital filter is constructed in which vibration information of a vibration source is used as a reference input and vibration information of an object to be vibration-isolated is input as an error, and feedforward control is performed. It is often used for control. This control method uses a digital feed-forward compensator, so even if the characteristics of the object to be isolated are unknown,
There is an advantage that the characteristic of the appropriate compensator according to the characteristic of the vibration isolation table can be automatically derived and realized. This control method is extremely effective today when discrete arithmetic devices such as a DSP (Digital Signal Processor) can be easily used, and is disclosed in Japanese Patent Application Laid-Open No. 6-235439. And devices "have been proposed.

FIG. 9 is a configuration diagram of a conventional example, in which a vibration isolating table 1 on which precision equipment is mounted is provided on an installation base 3 via a support mechanism 2. Two horizontal directions (X, Y) on the anti-vibration table 1
And first vibration detection means 4 for detecting vibration information in the vertical direction (Z), and second vibration detection means 5 for similarly detecting vibration information in three directions is provided on the installation base 3. I have. An actuator 6 for generating a vibration force in two horizontal directions and a vertical direction is provided on the vibration isolation table 1.

The outputs of the three components of the first vibration detecting means 4 are input to a parameter estimating mechanism 14 of an adaptive filter 13 via an amplifier 10, a band-pass filter 11, and an A / D converter 12, respectively. I have. On the other hand, the output of the three components of the second vibration detecting means 5 is also
5, input to the parameter estimation mechanism 14 of the adaptive filter 13 and the feed-forward compensator 18 via the band-pass filter 16 and the A / D converter 17, respectively. The three outputs of the parameter estimation mechanism 14 are connected to the actuator 6 via a feedforward compensator 18, a D / A converter 19, a combining circuit 20, and a driving circuit 21.
Further, the band-pass filter 11 of the first vibration detecting means 4
Are input to the synthesis circuit 20 via the feedback compensator 22.

The vibration of the vibration isolation table 1 is detected by the first vibration detecting means 4, amplified by the amplifier 10, and then, by the feedback compensator 22, the vibration information obtained by passing only the required frequency band by the band-pass filter 11 is calculated. After processing, the data is fed back to the actuator 6 via the synthesizing circuit 20 and the driving circuit 21. Further, the vibration of the installation base 3 is detected by the second vibration detecting means 5, amplified by the amplifier 15, and then subjected to arithmetic processing by the adaptive filter 13 on the vibration information obtained by passing only the necessary frequency band by the band-pass filter 16. The obtained operation amount is input to the drive circuit 21 to drive the actuator 6.

The vibration of the vibration isolation table 1 is detected by the vibration sensor 4,
Not only is the output signal compensated and fed back to the actuator 6 which applies a control force to the anti-vibration table 1, but also the vibration control method of appropriately compensating for the vibration of the installation base 3 and feeding forward to the actuator 6 is performed. The insulation performance of the vibration from the ground is greatly improved, and the vibration standard of the installation foundation 3 is also relaxed.

An example of a feedforward compensator is an active vibration isolator including characteristics of an actuator, such as a "method of controlling ground vibration disturbance of a vibration isolation table" disclosed in Japanese Patent Application Laid-Open No. 5-263868. There is a method of measuring some characteristics and implementing a compensator. This publication discloses a method for deriving an optimal feedforward compensator characteristic from an excitation response of an anti-vibration table using an actuator of an active anti-vibration apparatus and a vibration transmissibility from an installation foundation to the anti-vibration table. ing.

[0008]

However, in the conventional vibration isolator, interference components are generated and superimposed on the horizontal and vertical vibrations depending on the mounting of the actuator 6 and the position of the center of gravity. If the convergence speed of the estimation parameter in each direction of the shaking table 1 is different for each direction,
The transition of the estimation parameter affects the parameter estimation in the other direction, and the parameter may not converge or the parameter may diverge, thereby deteriorating the vibration isolation performance.

In the conventional active vibration isolator, the horizontal two
A control force is generated by the actuator 6 so as to cancel the vibration in one direction and one direction in the vertical direction. However, depending on the mounting of the actuator 6 or the position of the center of gravity of the vibration isolator, interference occurs in other directions, and the vibration isolation performance is deteriorated. There is.

An object of the present invention is to solve the above-mentioned problems,
It is an object of the present invention to provide an active vibration isolator having significantly improved vibration transmission characteristics from a foundation installed on a floor or the like as compared with a conventional example, and having good vibration isolation performance.

[0011]

According to a first aspect of the present invention, there is provided an active vibration isolator for achieving the above object, a vibration isolator, a support mechanism for supporting the vibration isolator, and a vibration isolator. An actuator that applies a control force in two horizontal and vertical directions to the actuator, first vibration detection means for detecting horizontal and vertical vibration information of the vibration isolation table, and detection by the first vibration detection means. A feedback compensator that receives the vibration information of the anti-vibration table and generates a feedback control signal; a second vibration detection unit that detects horizontal and vertical vibrations of an installation base on which the support mechanism is installed; The vibration information of the installation base and the vibration information of the anti-vibration table detected by the second vibration detection means are input and the coefficient is sequentially updated to generate a feedforward control signal using the vibration information of the installation foundation as a reference input. A filter, an operation switching mechanism for stopping / operating the adaptive filter, a determining mechanism for controlling the switching mechanism based on information of a parameter adjustment rule, and synthesizing the feedback control signal and the feedforward control signal to drive the actuator. It is characterized by adding a signal.

An active vibration isolator according to a second aspect of the present invention includes a vibration isolator, a support mechanism for supporting the vibration isolator with vibration isolation, and an actuator for applying a control force to the vibration isolator in two horizontal and vertical directions. A first vibration detecting means for detecting vibration information in two horizontal directions and a vertical direction of the vibration isolation table, and a feedback control signal which receives the vibration information of the vibration isolation table detected by the first vibration detection means as an input. A feedback compensator that is generated, second vibration detecting means for detecting horizontal and vertical vibrations of the installation foundation on which the support mechanism is installed, and vibration of the installation foundation detected by the second vibration detection means A feedforward compensator that generates a feedforward control signal using the information as a reference input, an interference characteristic estimator that estimates the characteristics of the interference components, and a signal that is necessary to estimate the interference component characteristics. An M-sequence signal generator, a decoupling compensator that adjusts based on an estimation result of the interference characteristic estimator to generate a decoupling control signal, the feedback control signal, the feedforward control signal, and the decoupling. And a drive signal is added to the actuator.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail with reference to the embodiments shown in FIGS. FIG. 1 shows a first embodiment, in which a vibration isolating table 31 on which precision equipment is mounted is provided on an installation base 33 via a support mechanism 32. A first vibration detecting means 34 for detecting vibration information in two horizontal directions (X, Y) and a vertical direction (Z) is provided on the vibration isolating table 31, and a similar second A vibration detecting means 35 is provided. Further, an actuator 36 for generating a vibration force in two horizontal directions and a vertical direction is provided on the vibration isolation table 31.

The outputs of the three components of the first vibration detecting means 34 are passed through an amplifier 40, a band-pass filter 41, an A / D converter 42, and an operation switching mechanism 43, respectively. 45 has been entered. On the other hand, the outputs of the three components of the second vibration detecting means 35 are similarly output from the amplifier 46, the band-pass filter 47,
The signal is input to the parameter estimating mechanism 45 of the adaptive filter 44 via the A / D converter 48 and the operation switching mechanism 43.
The three outputs of the parameter estimation mechanism 45 are connected to the actuator 36 via a feedforward compensator 49, a D / A converter 50, a combining circuit 51, and a driving circuit 52.

The output of the band-pass filter 41 of the first vibration detecting means 34 is input to the synthesizing circuit 51 via the feedback compensator 53, and the second vibration detecting means 35
The output of the A / D converter 48 is connected to a feedforward compensator 49 of the adaptive filter 44. Further, the output of the parameter estimating mechanism 45 drives the operation switching mechanism 43 via the judging mechanism 54.

This active vibration isolation device focuses on vibration of the vibration isolation table 31 and performs vibration control. The vibration isolation control apparatus focuses on vibration transmission from the installation base 33 to the vibration isolation table 31. Doing floor vibration consists of a feed forward loop.

In the vibration isolation table vibration feedback loop, the vibration of the vibration isolation table 31 supported by the vibration isolator by the support mechanism 32 is detected by the first vibration detecting means 34 such as an acceleration sensor, and is amplified by the amplifier 40. Vibration information passed through only the necessary frequency band by the band-pass filter 41 is subjected to arithmetic processing by the feedback compensator 53 and fed back to the actuator 36 via the drive circuit 52.

In the floor vibration feed forward loop, the vibration of the installation foundation 33 is detected by the second vibration detecting means 3.
The vibration information, which is detected by 5 and amplified by an amplifier 46 and then passed through only a necessary frequency band by a band pass filter 47, is digitized by an A / D converter 48 and passed through a feed forward compensator 49 of the adaptive filter 44. The signal is converted into an analog signal by the D / A converter 50 and output as a feedforward control signal. The drive circuit 52 drives the actuator 36 based on this signal.

Although an acceleration sensor can be used as the second vibration detecting means 35, the second vibration detecting means 3
Reference numeral 5 denotes, for example, a signal equivalent to an acceleration signal of the installation base 33, which is obtained from a signal of a first vibration detecting means 34 and a displacement sensor for detecting a relative displacement between the installation base 33 and the vibration isolation table 31. Is also good.

The feed forward compensator 49 converts the vibration information of the vibration isolation table 31 detected by the first vibration detecting means 34 and the vibration information of the installation base 33 detected by the second vibration detecting means 35. It is successively adjusted by the parameter estimation mechanism 45 as an input.

The operation switching mechanism 43 controls the stop / operation of the feedforward compensator 49 by the determining mechanism 54. The determining mechanism 54 monitors the transition of the estimated parameter, and the estimated parameter in a predetermined direction converges. When it is determined, the operation switching mechanism 43 is started to estimate the parameter in the next direction. For example, initially, estimation starts only in the X direction, and estimation in the Y and Z directions is not performed. When the determination mechanism 54 determines that the estimation parameters in the X direction have converged, the estimation in the Y direction is started. Further, when the estimation parameters in the Y direction converge, the estimation in the Z direction is started. Note that the order in which the estimation is started is not limited to the above order, and can be arbitrarily selected.

Note that precision equipment and the like are mounted on the vibration isolation table 31, so that the mounting of the precision equipment and the like is not affected.
An actuator may be incorporated in the support mechanism 32. In this case, the output of the drive circuit 52 is connected to the actuator of the support mechanism 32 as shown in FIG.

If the convergence time of the parameter in each direction is known in advance, the operation switching mechanism 43 may be switched by a timer 55 instead of the determination mechanism 54 as shown in FIG.

When the vibration of the installation base 33 such as a floor becomes small, the input to the parameter estimating mechanism 45 naturally becomes small. For this reason, the noise component becomes dominant, and the parameter estimation value deviates from the optimum value, which may deteriorate the vibration isolation performance. Therefore, as shown in FIG. 4, the vibration of the installation base 33 is input to the determination mechanism 54, and when it is determined that the vibration of the installation foundation 33 has decreased, a command is issued to the operation switching mechanism 43 to stop the estimation of the parameters. You can also.

The provision of another judgment criterion not only reduces the influence of interference from other directions, but also prevents deterioration of the vibration isolation performance of the adaptive filter 44 when the vibration of the installation base 33 is reduced. be able to.

FIG. 5 shows a second embodiment. The structure of the vibration isolating table 31, the support mechanism 32, the actuator 36, the first vibration detecting means 34, and the second vibration detecting means 35 in the second embodiment. Are the same as in the first embodiment.

The output of the first vibration detecting means 34 is
0, which is connected to a feedback compensator 53 and an interference characteristic estimating mechanism 61 via a band pass filter 41.
The output of the second vibration detecting means 35 is connected to a feedforward compensator 62 via an amplifier 46 and a bandpass filter 47. The output of the interference characteristic estimation mechanism 61 is connected to the decoupling compensator 63, and the interference characteristic estimation mechanism 6
1. The output of the M-sequence signal generator 64 is connected to the decoupling compensator 63. The output of the non-interference compensator 11 is combined with the output of the feedback compensator 53, the output of the feedforward compensator 62, and the output of the M-sequence signal generator 64 in the combining circuit 51, and is connected to the actuator 36 via the driving circuit 52. Have been. A part of the output of the combining circuit 51 is fed back to the decoupling compensator 63.

This active anti-vibration apparatus performs vibration control by paying attention to the vibration of the vibration isolation table 31 and vibration transmission from the installation base 33 to the vibration isolation table 31 for performing vibration control. It consists of a floor vibration feedforward loop to be performed and a decoupling loop for canceling the influence of interference between directions.

In the vibration isolation table vibration feedback loop, the vibration of the vibration isolation table 31 which is supported by the vibration isolation mechanism 31 by the support mechanism 32 is detected by the first vibration detection means 34, amplified by the amplifier 40, and then amplified by the band-pass filter 41. Vibration information that has passed only the necessary frequency band is subjected to arithmetic processing by the feedback compensator 53 and fed back to the actuator 36 via the synthesizing circuit 51 and the driving circuit 52.

In the floor vibration feed-forward loop, the vibration of the installation base 33 is detected by the second vibration detecting means 35, and is amplified by the amplifier 46.
7, the vibration information passed through only the necessary frequency band is processed by the feedforward compensator 62, and the obtained operation amount is input to the drive circuit 52 via the synthesis circuit 51.
The actuator 36 is driven.

The decoupling loop calculates the drive signal of the actuator 36 by the decoupling compensator 63 and drives the actuator in the other direction. FIG. 6 shows a configuration of a non-interference loop for canceling interference transmitted from the X direction to the Y direction. The drive signal of the X-direction actuator 36x is processed by the decoupling compensator 63, and the obtained operation amount is converted to a drive circuit. 52y to drive the Y-direction actuator 36y.

The characteristics of the decoupling compensator 63 for canceling the interference transmitted from the X direction to the Y direction can be obtained by the following procedure.

As a procedure 1, as shown in FIG. 7, the Y-direction actuator 36y is driven by the M-sequence signal generator 64, and the characteristic Gyy from the drive signal to the Y-direction platen vibration is obtained.
Is estimated by the interference characteristic estimating mechanism 61 based on the following equation, where Gy is the Y-direction base body characteristic and Uy is the Y-direction actuator characteristic. Gyy = Gy · Uy (1)

As a procedure 2, as shown in FIG. 8, the actuator 36x in the X direction is driven by the M-sequence signal generator 64, and the characteristic Gxy from the drive signal to the vibration of the surface plate in the Y direction is obtained.
Is estimated by the following equation by the interference characteristic estimating mechanism 61 using Txy as an interference characteristic in the X → Y direction and Ux as an X-direction actuator characteristic. Gxy = Gy · Txy · Ux (2)

The non-interference compensation characteristic Hxy to be obtained may be obtained by the following equation: Txy · Ux = Hxy · Uy (3) And the inverse function of the characteristic obtained in procedure 1 is multiplied by the following equation. Hxy = Txy · Ux / Uy = Gy · Txy · Ux / (Gy · Uy) = Gxy / Gyy (4) The above procedure may be repeated for each interference.

[0036]

As described above, according to the active vibration isolator according to the first aspect of the present invention, even when there is interference between the two horizontal directions and the vertical direction, the estimated parameters are not changed from the other directions. It converges quickly to the optimum value without receiving interference, and sufficient vibration isolation performance can be obtained.

According to the active vibration isolator according to the second aspect of the present invention, even when interference occurs between each of the two horizontal directions and the vertical direction, a new vibrating device and a new sensor are not used.
A non-interference loop for canceling interference can be simply configured, and sufficient anti-vibration performance can be obtained.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a first embodiment.

FIG. 2 is a configuration diagram of a first modified example.

FIG. 3 is a configuration diagram of a second modified example.

FIG. 4 is a configuration diagram of a third modified example.

FIG. 5 is a configuration diagram of a second embodiment.

FIG. 6 is a configuration diagram of a decoupling loop that cancels interference from the X direction to the Y direction.

FIG. 7 is an explanatory diagram of a procedure 1 for obtaining a decoupling compensation characteristic.

FIG. 8 is an explanatory diagram of a procedure 2 for obtaining a decoupling compensation characteristic.

FIG. 9 is a configuration diagram of a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 31 Vibration isolation table 32 Support mechanism 33 Installation base 34 First vibration detection means 35 Second vibration detection means 36 Actuator 43 Switching mechanism 44 Adaptive filter 45 Parameter estimation mechanism 49, 62 Feed forward compensator 52 Drive circuit 53 Feedback compensator 54 determination mechanism 55 timer 61 interference characteristic estimation mechanism 63 decoupling compensator 64 M-sequence signal generator

Claims (5)

[Claims] 1. An anti-vibration table, a support mechanism for supporting the anti-vibration table in an anti-vibration manner, an actuator for applying a control force to the anti-vibration table in two horizontal directions and a vertical direction, and two horizontal directions of the anti-vibration table First vibration detecting means for detecting vibration information in the vertical direction, a feedback compensator for generating a feedback control signal by receiving vibration information of the vibration isolation table detected by the first vibration detecting means, Second vibration detecting means for detecting horizontal and vertical vibrations of an installation foundation on which a mechanism is installed, vibration information of the installation foundation detected by the second vibration detection means, and vibration information of the vibration isolation table , An adaptive filter for sequentially updating the coefficient and generating a feedforward control signal using the vibration information of the installation foundation as a reference input, an operation switching mechanism for stopping / operating the adaptive filter, and a parameter An active anti-vibration device, comprising: a determination mechanism that controls the switching mechanism based on information of an adjustment rule; and combining the feedback control signal and the feedforward control signal and applying a drive signal to the actuator. 2. The active vibration isolator according to claim 1, wherein at least one of said first vibration detecting means and said second vibration detecting means is an acceleration sensor. 3. The active vibration isolation device according to claim 1, wherein the operation switching mechanism stops / operates the parameter estimation mechanism by the determination mechanism. 4. An anti-vibration table, a support mechanism for supporting the anti-vibration table in an anti-vibration manner, an actuator for applying a control force to the anti-vibration table in two horizontal directions and a vertical direction, and two horizontal directions of the anti-vibration table First vibration detecting means for detecting vibration information in the vertical direction, a feedback compensator for generating a feedback control signal by receiving vibration information of the vibration isolation table detected by the first vibration detecting means, The second to detect the horizontal and vertical vibrations of the installation foundation on which the mechanism is installed
, A feedforward compensator for generating a feedforward control signal using the vibration information of the installation foundation detected by the second vibration detection means as a reference input, and an interference characteristic estimator for estimating characteristics of an interference component An M-sequence signal generator that generates a signal necessary for estimating an interference component characteristic, a decoupling compensator that adjusts based on an estimation result of the interference characteristic estimator and generates a decoupling control signal, An active vibration isolator that combines the feedback control signal, the feedforward control signal, and the decoupling control signal, and applies a drive signal to the actuator. 5. The active vibration isolator according to claim 4, wherein at least one of said first vibration detecting means and said second vibration detecting means is an acceleration sensor.