JP2012087880A - Active vibration isolation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an active vibration isolation device, capable of reducing vibration transmitting ratio in inherent frequencies of both objects in which vibration is isolated and an active mass damper for a long period of time, when the inherent frequencies of the active mass damper is made higher than the inherent frequency of the object in which vibration is isolated.SOLUTION: An actuator (linear motor 32) is controlled such that the driving reaction force of the movable mass 33 of the active mass damper (vibration control unit 3) becomes controlling force canceling the vibration of the object in which vibration is isolated (machine D and a surface plate 1) according to the vibration condition of the object in which vibration is isolated in a basic control part 4a and the phase of a control signal to the actuator is advanced 180° in the frequency corresponding to the frequency between the inherent frequency of the object in which vibration is reduced and the inherent frequency of the vibration control unit 3 in the correcting part 4b.

Description

  The present invention belongs to a technical field relating to an active vibration isolator that adds a control force for reducing vibrations in a predetermined direction of an object to be isolated to the object to be isolated by an active mass damper attached to the object to be isolated. .

  Conventionally, as shown in Patent Document 1, for example, an active mass damper (hereinafter also referred to as AMD) is attached to a vibration isolation object, and this AMD allows a predetermined direction ( 2. Description of the Related Art An active vibration isolation device is known in which a control force that attenuates vibrations in the vertical direction and the horizontal direction is applied to the vibration isolation object.

  In the active vibration isolation device of Patent Document 1, the natural frequency of AMD is made lower than the natural frequency of the vibration isolation object, and the control of the actuator of AMD is corrected by a notch filter (phase advance compensation filter). The influence of resonance of the additional vibration system composed of the movable mass of the AMD and the spring element is eliminated. That is, the notch frequency is made to coincide with the natural frequency of AMD, thereby canceling the resonance peak of the gain characteristic in the open loop characteristic of the actuator control (feedback control) at the natural frequency of AMD. The transfer function in the open loop characteristic is obtained by multiplying the transfer function G (s) of the object to be vibration-isolated by the transfer function C (s) of the controller (including the phase advance compensation filter). .

JP 2008-303997 A

  By the way, when the natural frequency of the vibration isolation object is as low as about 5 Hz, for example, when trying to make the natural frequency of AMD lower than the natural frequency of the vibration isolation object, the spring element of AMD is made quite soft. For this reason, the problem of supportability of the movable mass arises.

  Therefore, when the natural frequency of the vibration isolation object is low, it is conceivable that the natural frequency of AMD is made higher than the natural frequency of the vibration isolation object. In this case as well, it is conceivable to eliminate the influence of resonance of the additional vibration system by using the phase lead compensation filter as in Patent Document 1. Thereby, the resonance peak of the gain characteristic can be canceled in the open loop characteristic at the natural frequency of AMD (see FIG. 8). As a result, the AMD is not present.

  However, it is necessary to set the phase (the phase difference of the output (output from the controller) to the input (external force) of the open loop characteristic) to 0 ° at the natural frequency of the vibration isolation object in the phase characteristic in the open loop characteristic. As a result, the phase does not become zero at the natural frequency of AMD. That is, the phase that has changed from 90 ° to −90 ° before and after the natural frequency of the vibration isolation object tends to change from −90 ° to −270 ° before and after the natural frequency of AMD. Since it is advanced 180 ° by the compensation filter, it remains −90 ° (see FIG. 8).

  As a result, by the actuator control of the controller, the vibration transmissibility can be reduced at the natural frequency of the vibration isolation object, but cannot be reduced at the natural frequency of AMD (see FIG. 9).

  In addition, the notch frequency of the phase lead compensation filter needs to match the natural frequency of AMD, but even if it matches immediately after the manufacture of the vibration isolator, the natural frequency of AMD is caused by the secular change of the AMD spring element. If they change, they will not match, and there is a possibility that sufficient effects will not be obtained by long-term use.

  Furthermore, the phase lead compensation filter cuts (notches) a sensor signal that matches the natural frequency of AMD so that the response of AMD does not increase. When a force is applied, the notch depth is finite, so that the sensor signal may not be cut completely. In this case as well, a sufficient effect may not be obtained.

  The present invention has been made in view of such points, and an object of the present invention is to provide an object for vibration isolation when the natural frequency of the active mass damper is set higher than the natural frequency of the object for vibration isolation. Another object of the present invention is to provide an active vibration isolator capable of reducing the vibration transmissibility over a long period at the natural frequency of both the active mass damper and the active mass damper.

  In order to achieve the above object, in the present invention, a control force for reducing vibrations in a predetermined direction of the vibration isolation object is added to the vibration isolation object by an active mass damper attached to the vibration isolation object. In the state where the active mass damper is attached to the vibration isolation target for the active vibration isolation device, the natural frequency of the active mass damper in the predetermined direction is the natural frequency of the vibration isolation target in the predetermined direction. The active mass damper is configured to be higher than the vibration frequency, and the active mass damper is attached to the vibration isolation object via a spring element so as to be movable in the predetermined direction, and the active mass damper is attached to the vibration isolation object to move the movable mass damper. An actuator that drives the mass in the predetermined direction and applies a driving reaction force to the vibration isolation object, and detects a vibration state of the vibration isolation object in the predetermined direction. A vibration state detection sensor and a control force for reducing the vibration in the predetermined direction of the vibration isolation object by the driving reaction force of the movable mass according to the vibration state of the vibration isolation object detected by the vibration state detection sensor A basic control unit that controls the actuator, and a correction unit that corrects the control of the actuator by the basic control unit, wherein the correction unit changes the phase of the actuator control signal from the basic control unit. The configuration is such that the vibration isolating object is advanced by 180 ° at a frequency corresponding to the natural frequency in the predetermined direction of the object to be isolated and the natural frequency in the predetermined direction of the active mass damper. .

  With the above configuration, the phase characteristic in the open loop characteristic of the actuator control (feedback control) changes from 90 ° to −90 ° before and after the natural frequency of the vibration isolation object (the output of the output with respect to the input of the open loop characteristic). The phase difference) is a frequency corresponding to the natural frequency of the object to be isolated and the natural frequency of the active mass damper, and is advanced by 180 ° by the correction unit to 90 °. It changes from 90 ° to −90 ° with a 180 ° delay before and after. Thereby, in the open loop characteristic, the phase becomes 0 not only at the natural frequency of the object to be isolated, but also at the natural frequency of the active mass damper. As a result, the vibration transmissibility can be reduced at the natural frequencies of both the vibration isolation object and the active mass damper. Also, unlike the case where the notch frequency of the phase advance compensation filter is matched with the natural frequency of the active mass damper, even if the natural frequency of the active mass damper changes due to aging of the spring element of the active mass damper, etc. Even if a large disturbance or sudden force is applied to the vibration isolation object, the effect of reducing the vibration transmissibility does not change.

In the active vibration isolation device, the correction unit includes a notch filter, and a transfer function F (s) thereof is
F (s) = (s ² + 2ζω _n s + ω _n ² ) / s ² (1)
S in the equation (1) is a Laplace operator, and ω _n in the equation (1) is a frequency (unit: rad / unit) corresponding to the notch frequency of the notch filter. s), the natural frequency of the vibration isolation object in the predetermined direction is ωa, and the natural frequency of the active mass damper in the predetermined direction is ω,
ωa <ω _n <ω
The filling,
In the formula (1), ζ is an attenuation ratio of the notch filter, and is preferably set to a value of 0.005 or more and 0.1 or less.

This makes it easy to advance the phase of the control signal to the actuator by 180 ° at a frequency corresponding to the natural frequency of the vibration isolation object and the natural frequency of the active mass damper. Here, the value of ζ affects the frequency width necessary for the phase of the control signal to the actuator to advance by 180 °. If the value of ζ is too large, the frequency width increases and the notch frequency is changed to the active mass damper. Thus, the control band (the band lower than the notch frequency) becomes narrower, while the value of ζ approaches 0 as much as possible theoretically, ω _n = ω. Since the notch filter and the active mass damper may interfere with each other, it is preferable to set the value between 0.005 and 0.1.

  As described above, according to the active vibration isolator of the present invention, when the natural frequency of the active mass damper is made higher than the natural frequency of the vibration isolation object, both the vibration isolation object and AMD natural vibrations. The vibration transmissibility can be reduced over a long period of time, and the vibration isolation performance can be improved.

It is a figure which shows typically schematic structure of the vibration isolator as an active vibration isolator which concerns on embodiment of this invention. It is a block diagram which shows control of the linear motor by a controller. It is a Bode diagram which shows the open loop characteristic (a gain characteristic curve and a phase characteristic curve) of an Example. It is a graph which shows the change of the vibration transmissibility by a frequency in the closed loop characteristic of an Example. In an Example, it is a graph which shows the response characteristic (input of an open loop characteristic-output of an open loop characteristic) in the natural frequency of a damping unit in a closed loop characteristic. It is a block diagram which shows a closed loop. It is a block diagram which shows an open loop. It is a Bode diagram which shows the open loop characteristic (a gain characteristic curve and a phase characteristic curve) of a comparative example. It is a graph which shows the change of the vibration transmissibility by frequency in the closed loop characteristic of a comparative example. In a comparative example, it is a graph which shows the response characteristic (input of an open loop characteristic-output of an open loop characteristic) in the natural frequency of a damping unit in a closed loop characteristic.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 shows a vibration isolation table A as an active vibration isolation device according to an embodiment of the present invention. This vibration isolation table A is a precision vibration isolation table for mounting a precise device D that is susceptible to vibration, such as semiconductor-related manufacturing equipment, test equipment, electron microscopes, laser microscopes, and other precision measurement equipment. In this case, the device D is installed in a state insulated as much as possible from the vibration of the floor.

  The vibration isolation table A elastically supports the surface plate 1 on which the device D is mounted by usually three (or four or more) air springs 2 (only two are shown in FIG. 1). The surface plate 1 and the mounted device D are vibration isolation objects. Further, the vibration isolation table A itself is a so-called passive type, and although not shown in the drawings, a pneumatic circuit for supplying or exhausting high-pressure air is connected to each air spring 2 to provide a leveling valve or the like. By operation, the height of the surface plate 1 is maintained substantially constant.

  In the present embodiment, the vibration control unit 3 is attached to the upper surface of the device D, and the device D and the surface plate 1 in a predetermined direction (in the vertical direction in the present embodiment) by the control force applied to the device D by the vibration control unit 3. The vibration isolation table A including the control unit 3 constitutes an active vibration isolation device. The vibration control unit 3 is called an active mass damper, and the movable mass 33 in the case 30 fixed to the device D is driven in the vertical direction by a linear motor 32 (actuator), and the driving reaction force is applied to the case 30. Via the device D. In this embodiment, attention is paid to the vibration in the vertical direction in order to reduce the vibration in the vertical direction of the vibration isolation object (device D and the surface plate 1). Therefore, the vibration in the vertical direction is hereinafter simply referred to as vibration. Further, the natural frequency in the vertical direction of the vibration suppression unit 3 is simply referred to as the natural frequency of the vibration suppression unit 3, and the natural frequency in the vertical direction of the vibration isolation object is simply referred to as the natural frequency of the vibration isolation object.

  Below, the structure of the vibration suppression unit 3 (active mass damper) is demonstrated. As shown in FIG. 1 (shown larger than the actual size), the damping unit 3 includes, for example, a rectangular substrate 30a attached to the base end (lower end) of the cylindrical case 30. The corner is fastened to the upper surface of the device D. On the other hand, a disc-shaped lid member 30 b is attached to the tip (upper end) of the case 30. The peripheral wall portion of the case 30 includes a proximal end side member 30c constituting a substantially half of the proximal end side, a distal end side member 30d constituting the distal end side of the remaining portions, a proximal end side member 30c, and a distal end side member 30d. It is divided into three parts with an intermediate member 30e located between them.

  The inside of the case 30 is divided into approximately three equal parts by the two partition walls 30f and 30g in the central axis J direction (vertical direction) of the case 30, and the lower partition wall 30f and the substrate 30a in the case 30 are separated from each other. The acceleration sensor 31 is accommodated in the space between. The acceleration sensor 31 is fixed to the substrate 30a and detects the acceleration z ″ due to the vibration of the device D. That is, the acceleration sensor 31 detects a vibration state of a vibration isolation object. Configure.

  A linear motor 32 is accommodated in a space between the two partition walls 30f and 30g in the case 30. The upper surface of the case of the linear motor 32 is fixed to the upper partition wall 30g, and the rod of the linear motor 32 is inserted through a through hole formed in the partition wall 30g and extends upward on the central axis J of the case 30. It protrudes into the space between the partition wall 30g and the lid member 30b in the case 30.

  A movable mass 33 is accommodated in the space from which the rod of the linear motor 32 protrudes, and this movable mass 33 is held by two leaf springs 34 so as to be movable in the direction of the central axis J with respect to the case 30. ing. The movable mass 33 includes a substantially cylindrical main body portion 33a and a shaft portion 33b penetrating the main body portion 33a in the vertical direction. The upper and lower ends of the shaft portion 33b are the central portions of the two leaf springs 34, respectively. The lower end of the shaft portion 33 b is connected to the tip of the rod of the linear motor 32.

  Although not shown in detail, the leaf spring 34 has a disk shape and is formed with a plurality of through grooves in a radial intermediate portion excluding a predetermined range of the central portion and the outer peripheral portion. The outer peripheral portion of the upper leaf spring 34 is sandwiched between the distal end side member 30d and the intermediate member 30e, and the lower leaf spring 34 is sandwiched between the proximal end side member 30c and the intermediate member 30e and coupled to the case 30. As described above, a central hole is formed in the center portion of both leaf springs 34 to fix the shaft portion 33b of the movable mass 33 in a penetrating state.

  In the present embodiment, in a state where the vibration control unit 3 is attached to the device D, the natural frequency of the vibration control unit 3 is set higher than the natural frequency of the vibration isolation object (the device D and the surface plate 1). ing. The natural frequency of the vibration isolation object is as low as 4 to 6 Hz, for example, in terms of frequency. However, it is not limited to such a low value. The natural frequency of the damping unit 3 is preferably higher by 5 Hz or more than the natural frequency of the vibration isolation object.

  Next, the control of the vibration suppression unit 3 will be specifically described. In the present embodiment, the operation of the damping unit 3, that is, the driving of the movable mass 33 by the control of the linear motor 32 is performed by the controller 4. As shown in FIG. 1, the controller 4 includes a basic control unit 4a and a correction unit 4b. The basic control unit 4 a performs feedback control of the linear motor 32 based on a signal from the acceleration sensor 31 of the vibration suppression unit 3. That is, the basic control unit 4a inputs a signal from the acceleration sensor 31 and determines the movable mass 33 according to the vibration state of the vibration isolation object (device D and the surface plate 1) detected by the acceleration sensor 31. The linear motor 32 is controlled so that the driving reaction force becomes a control force that attenuates the vibration of the vibration isolation object. The correction unit 4 b corrects the control of the linear motor 32 by the basic control unit 4 a (linear motor control signal output from the basic control unit 4 a), and outputs the corrected linear motor control signal as an output signal from the controller 4. To the linear motor 32.

  As shown in FIG. 2, the basic control unit 4a multiplies the displacement z obtained by integrating twice the signal from the acceleration sensor 31, that is, the acceleration z ″ of the vibration isolation object, by a gain B1, The speed z ′ obtained by integrating the acceleration z ″ once is multiplied by the gain B2, and the acceleration z ″ is multiplied by the gain B3. This operation amount u1 is for generating a control force that reduces the vibration of the object to be isolated as a driving reaction force of the movable mass 33.

  In the above control calculation, feedback control of the speed z ′ is fundamental, which means that the damping unit 3 adds damping to the main vibration system composed of the device D, the surface plate 1 and the air spring 2. . By adding the vibration damping unit 3, the vibration isolation table A becomes a vibration system with two degrees of freedom, but damping is added by the feedback control of the speed z ', and the resonance magnification is lowered, so that the resonance of the main vibration system is suppressed. be able to. In addition, the high frequency side performance can be improved by feedback control of the acceleration z ″, and the low frequency side performance can be improved by feedback control of the displacement z. Note that the feedback control of the acceleration z ″ and the displacement z. And only the feedback control of the speed z ′ may be performed.

  The correction unit 4b advances the phase of the linear motor control signal from the basic control unit 4a by 180 ° at a frequency corresponding to the natural frequency of the vibration isolation object and the natural frequency of the vibration control unit 3. It is configured to let you.

Specifically, in the present embodiment, the correction unit 4b includes a notch filter (phase advance compensation filter), and the transfer function F (s) is
F (s) = (s ² + 2ζω _n s + ω _n ² ) / s ² (1)
It is represented by.

In the equation (1), s is a Laplace operator, ω _n is a frequency (unit: rad / s) corresponding to the notch frequency of the notch filter, and the natural frequency of the vibration isolation object. Is ωa, and the natural frequency of the damping unit 3 is ω,
ωa <ω _n <ω
Meet.

  In the equation (1), ζ is an attenuation ratio of the notch filter, and is set to a value between 0.005 and 0.1.

Here, the value of ζ affects the frequency width necessary for the phase of the linear motor control signal from the basic control unit 4a to advance by 180 °. If the value of ζ is too large, the frequency width increases. The notch frequency cannot be brought close to the natural frequency of the active mass damper, and as a result, the control band (band lower than the notch frequency) is narrowed. If ω has already been determined (usually this is the case), it is preferable to make ω _n closer to (increase) the value of ω from the viewpoint of widening the control band (band lower than the notch frequency). Therefore, in order to reduce the frequency width and make ω _n approach the value of ω, it is preferable to set ζ small. However, when approaching as much as 0, theoretically, ω _n = ω, and notch filter And the vibration control unit 3 may interfere with each other. Therefore, it is preferable to set ζ to 0.005 or more and 0.1 or less. More preferably, ζ is set to a value between 0.007 and 0.05.

  The correction unit 4b receives the operation amount u1 (linear motor control signal) from the basic control unit 4a, multiplies it by F (s) to obtain the corrected operation amount u2, and further obtains the fourth operation high pass. After passing through the filter, it is output to the linear motor 32 via the power amplifier. The reason why the manipulated variable u2 passes through the fourth-order high-pass filter is that the notch filter has a high gain at a low frequency. The high-pass filter is not essential and may be omitted.

Here, a vibration isolation table (hereinafter referred to as an example) similar to the vibration isolation table A described above was produced. However, in this embodiment, since it is simple, the natural frequency ωa of the vibration isolation object is relatively high at 25 Hz in terms of frequency. The natural frequency ω of the vibration control unit 3 was 81 Hz in terms of frequency. Furthermore, as only a feedback control of the speed z ', the gain B1 and B3 is set to 0, B2 was 10 ^5. Further, the cut-off frequencies of the integrator, the notch filter, and the high-pass filter were 0.1 Hz, 0.1 Hz, and 1.0 Hz, respectively. The attenuation ratio ζ was 0.01, and the notch frequency ω _n was 50 Hz in terms of frequency.

Meanwhile, for comparison, the notch frequency omega _n to match the omega and 81Hz, others were produced in the same manner the anti-vibration table and examples.

  FIG. 3 shows open loop characteristics in the linear motor control (feedback control) of the above embodiment, and FIG. 4 shows closed loop characteristics in the linear motor control. Here, as shown in FIG. 6, the closed-loop characteristic is the same characteristic as the feedback control, and the control force is set to have an opposite phase to the input in order to cancel the input (external force) to the vibration isolation object. This is a characteristic when -1 is multiplied by -1 and added to the input. The input in the closed loop characteristic is an external force input to the vibration isolation object, and the output in the closed loop characteristic is an output from the vibration isolation object (detected by the acceleration sensor 31). FIG. 4 shows the change in vibration transmissibility, which is the ratio of the output magnitude to the input magnitude, with frequency in the closed-loop characteristic. The transfer function of the vibration isolation object is G (s), and the transfer function of the controller 4 (including both the basic control unit 4a and the correction unit 4b) is C (s).

  On the other hand, as shown in FIG. 7, the open loop characteristic is a characteristic when the closed loop is cut halfway in order to prevent the output from the controller 4 from being added to the input to the vibration isolation object in the closed loop characteristic. . The input in the open loop characteristic is an external force input to the vibration isolation object, and the output in the open loop characteristic is an output from the controller. The transfer function of the open loop characteristic is G (s) × C (s). FIG. 3 shows the change in the ratio of the output magnitude to the input magnitude (gain characteristic curve) according to the frequency and the change in the phase difference of the output relative to the input (phase characteristic curve) due to the frequency in the open loop characteristics. Show. If the input and output in the open loop characteristic are in phase (phase difference is 0 °), the output is reduced compared to the input in the closed loop characteristic (vibration transmissibility is reduced), while the input and output in the open loop characteristic are reduced. Are in reverse phase (phase difference is 180 °), the output is amplified more than the input with a closed loop characteristic (vibration transmission rate increases). FIG. 5 shows response characteristics (input of open loop characteristics−output of open loop characteristics) at the natural frequency ω (81 Hz) of the damping unit in the closed loop characteristics in the embodiment.

  Further, in the comparative example, the open loop characteristic (gain characteristic curve and phase characteristic curve) is shown in FIG. 8, the closed loop characteristic is shown in FIG. 9, and the response at the natural frequency ω (81 Hz) of the damping unit in the closed loop characteristic is shown. FIG. 10 shows the characteristics (input of open loop characteristics−output of open loop characteristics).

  In the comparative example, as shown in the phase characteristic curve of FIG. 8, the phase (the phase difference of the output with respect to the input) changes from 90 ° to −90 ° before and after the natural frequency ωa of the vibration isolation object. The natural frequency ωa of the object to be shaken is 0 °. As a result, as shown in FIG. 9, the vibration transmissibility is reduced at the natural frequency ωa of the vibration isolation object as compared with the case of no control (passive).

  Further, in the comparative example, as shown in the phase characteristic curve of FIG. 8, it tries to change from −90 ° to −270 ° before and after the natural frequency ω of the damping unit, but is advanced by 180 ° by the notch filter. Therefore, it remains at −90 °. Then, as shown in the gain characteristic curve of FIG. 8, the resonance peak of the open loop characteristic is canceled at the natural frequency ω of the vibration suppression unit, and the vibration suppression unit does not exist. However, since the phase is −90 °, the response characteristic at the natural frequency ω of the vibration suppression unit in the closed loop characteristic is as shown in FIG. 10, and the natural frequency of the vibration suppression unit as shown in FIG. In ω, the vibration transmissibility cannot be reduced.

  On the other hand, in the embodiment, as shown in the phase characteristic curve of FIG. 3, the phase is 0 ° in both the natural frequency ωa of the vibration isolation object and the natural frequency ω of the vibration suppression unit. That is, the phase characteristics in the open loop characteristics, the phase changing from 90 ° to −90 ° before and after the natural frequency of the vibration isolation object, are the natural frequency ωa of the vibration isolation object and the natural frequency of the damping unit. At a frequency equivalent to ω (notch frequency (50 Hz)), it is advanced by 180 ° by the notch filter to 90 °. Then, it changes from 90 ° to −90 ° with a delay of 180 ° before and after the natural frequency ω of the damping unit, and becomes 0 ° at the natural frequency ω of the damping unit. As a result, the response characteristic at the natural frequency ω of the damping unit in the closed loop characteristic is as shown in FIG. Therefore, as shown in FIG. 4, not only the natural frequency ω of the damping unit but also the natural frequency ω of the damping unit can reduce the vibration transmissibility compared to the case without control.

  As described above, in the present embodiment, the natural frequency ω of the vibration suppression unit 3 is set higher than the natural frequency ωa of the vibration isolation object, and the vibration isolation detected by the acceleration sensor 31 in the basic control unit 4a. In accordance with the vibration state of the object, the linear motor 32 is controlled so that the driving reaction force of the movable mass 33 of the vibration suppression unit 3 becomes a control force that attenuates the vibration of the vibration isolation object, and the correction unit 4b. (Notch filter) advances the phase of the linear motor control signal by 180 ° at a frequency (notch frequency) corresponding to the natural frequency ωa of the vibration isolation object and the natural frequency ω of the damping unit 3. Therefore, the vibration transmissibility can be reduced at the natural frequencies of both the vibration isolation object and the vibration suppression unit 3. Further, unlike the case where the notch frequency of the notch filter is matched with the natural frequency of the damping unit 3, even if the natural frequency of the damping unit 3 changes due to the secular change of the leaf spring 34 of the damping unit 3, etc. Even if a large disturbance or sudden force is applied to the vibration isolation object, the effect of reducing the vibration transmissibility does not change.

  The present invention is not limited to the above-described embodiment, and can be substituted without departing from the scope of the claims.

  For example, in the above-described embodiment, the vibration damping mechanism is housed in the case 30 together with the acceleration sensor 31 to constitute the integral vibration damping unit 3. However, the present invention is not limited to this, and the acceleration sensor 31 and the linear motor 32 are respectively connected to the device. It can also be arranged directly on D. Instead of the acceleration sensor 31, for example, a speed sensor or a displacement sensor can be used. In addition to the linear motor 32, for example, an actuator such as an air spring or a piezoelectric element that controls the internal pressure with a servo valve can be used.

  Further, in the damping unit 3, instead of the leaf spring 34 connecting the movable mass 33 to the case 30, for example, a metal or resin annular member and an annular rubber member are alternately laminated in the radial direction. A laminated elastic body can be used, and a magnetic bearing, an air bearing, or the like can be used.

  In the embodiment, the movable mass 33 is driven in the vertical direction by the linear motor 32 in order to reduce the vertical vibration of the vibration isolation object (the device D and the surface plate 1). The vibration in the oblique direction with respect to the horizontal direction or the horizontal direction or the vertical direction of the object may be attenuated, and the center axis J of the case 30 extends in the direction of attenuation, and the movable mass 33 is extended in that direction. May be driven.

  Furthermore, in the said embodiment, although the vibration isolator A which supported the surface plate 1 with the air spring 2 was illustrated, it replaces with the air spring 2, and uses the gas spring which enclosed gas other than air. It is also possible to use a spring element other than a gas spring, such as a coil spring.

  INDUSTRIAL APPLICABILITY The present invention is useful for an active vibration isolation device that adds a control force that attenuates vibrations in a predetermined direction of an object to be vibration-isolated to the object to be vibration-isolated by an active mass damper attached to the object to be vibration-isolated.

A Vibration isolation table (active vibration isolation device)
D equipment (objects for vibration isolation)
1 Surface plate (object for vibration isolation)
3 Vibration control unit (active mass damper)
4 Controller 4a Basic control unit 4b Correction unit 31 Acceleration sensor (vibration state detection sensor)
32 Linear motor (actuator)
33 Moving mass

Claims (2)

An active vibration isolator that adds to the vibration isolation object a control force that attenuates vibration in a predetermined direction of the vibration isolation object by an active mass damper attached to the vibration isolation object,
With the active mass damper attached to the vibration isolation object, the natural frequency of the active mass damper in the predetermined direction is set higher than the natural frequency of the vibration isolation object in the predetermined direction,
The active mass damper is attached to the vibration isolation object so as to be movable in the predetermined direction via a spring element, and is attached to the vibration isolation object to drive the movable mass in the predetermined direction. And an actuator that causes the drive reaction force to act on the vibration isolation object,
A vibration state detection sensor for detecting a vibration state in the predetermined direction of the vibration isolation object;
In accordance with the vibration state of the vibration isolation object detected by the vibration state detection sensor, the driving reaction force of the movable mass becomes a control force that attenuates vibration in a predetermined direction of the vibration isolation object. A basic control unit for controlling the actuator;
A correction unit that corrects the control of the actuator by the basic control unit,
The correction unit corresponds to the phase of the actuator control signal from the basic control unit between the natural frequency in the predetermined direction of the vibration isolation object and the natural frequency in the predetermined direction of the active mass damper. An active vibration isolation device configured to advance 180 ° at a frequency. The active vibration isolator according to claim 1.
The correction unit includes a notch filter, and the transfer function F (s) is
F (s) = (s ² + 2ζω _n s + ω _n ² ) / s ² (1)
Is represented by
In the formula (1), s is a Laplace operator,
Ω _n in the equation (1) is a frequency (unit: rad / s) corresponding to the notch frequency of the notch filter, and the natural frequency in the predetermined direction of the vibration isolation object is ωa, The natural frequency in the predetermined direction of the active mass damper is ω,
ωa <ω _n <ω
The filling,
In the equation (1), ζ is an attenuation ratio of the notch filter, and is set to a value not less than 0.005 and not more than 0.1.

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