JP2015075909A - Active vibration isolator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve vibration isolation performance of an active vibration isolator.SOLUTION: A feedforward vibration control unit 3b calculates a feedforward control reference variable Uφ in a φ direction that is a rotation direction around the x-axis corresponding to acceleration speeds z0", x0", y0" representing vibrational states of a floor, and determines a feedforward control input U2 by multiplying the feedforward control reference variable Uφ by an inverse function of a transfer function T representing characteristics of a servo valve 22a and a pneumatic spring 20a, and inverts the feedforward control input U2 to be added to an input to the servo valve 22a. Thus, vibration in the φ direction of a center of gravity of supported bodies 1, D that is formed by coupling vibrations of the z-axis, x-axis and y-axis of the floor F can be isolated.

Description

  The present invention relates to an active vibration isolator for, for example, a semiconductor manufacturing apparatus, a precision measuring apparatus, and the like that are substantially insulated from basic vibrations, and in particular, estimates transmission vibration to a supported body based on the basic vibration state. In addition, the present invention belongs to the technical field of feedforward control in which a control vibration that cancels the transmission vibration is added by an actuator.

  Conventionally, as this type of active vibration isolation device, for example, a vibration isolation table disclosed in Patent Document 1 is known. FIG. 4 is a diagram schematically showing a schematic configuration of the vibration isolation table 100 disclosed in Patent Document 1. As shown in FIG.

  This vibration isolation table 100 is composed of four diaphragm type air springs arranged on a floor 200 (foundation), and a surface plate mounted on top of these isolators 300, 300,. 400, and a device 500 that is a vibration isolation object is installed on the surface plate 400. The surface plate 400 and the device 500 are supported bodies of the isolators 300, 300,.

  Each isolator 300 is provided with an acceleration sensor and a displacement sensor for detecting the vertical acceleration z ″ of the supported bodies 400 and 500 and the vertical displacement z−z0 with respect to the foundation of the supported body. An acceleration sensor for detecting the acceleration z0 "in the vertical direction of the floor is provided. FIG. 4 does not show any sensor. Output signals from these sensors are respectively input to a controller (not shown), and the controller adjusts the air supply / discharge flow rate with respect to the air spring constituting the isolator 300.

  The active vibration isolator 100 detects the vibration state of the floor 200 with an acceleration sensor, and in response to the vibration being transmitted to the supported bodies 400 and 500, the anti-vibration device 100 has an opposite phase to cancel the transmitted vibration. Control vibration is generated by an air spring. Regarding the vertical direction, the vibration in the vertical direction of the floor, that is, the acceleration z0 "in the vertical direction of the floor 200 is detected and the vertical vibration of the supported body is suppressed by feedforward control. The horizontal vibration of the floor 200, that is, the horizontal acceleration x0 ", y0" of the floor 200 is detected, and the horizontal vibration of the supported body is suppressed by feedforward control.

Japanese Patent No. 3856676

  By the way, the active vibration isolator 100 of Patent Document 1 performs vibration isolation control on the assumption that the supported body vibrates in a certain degree of freedom direction due to vibration of the floor 200 in a certain degree of freedom direction. That is, in the active vibration isolator 100, the supported body vibrates in the vertical direction due to the vertical vibration of the floor 200 in the vertical coordinate system, for example, the vertical, front and back, and left and right, and the supported body due to the vibration in the longitudinal direction of the floor 200. The vibration isolation control is performed on the assumption that the support body vibrates in the left-right direction due to the vibration in the left-right direction of the floor 200.

  However, in actuality, as shown in FIG. 4, the floor 200 does not pass through the center of gravity G of the supported bodies 400 and 500, and so on. When the floor 200 vibrates, vibration in another direction of freedom may be excited in combination with the floor 200. Specifically, for example, when the floor 200 vibrates in FIG. 4 to generate a leftward force Fx, a clockwise moment force (= Fx × d1) in the figure is generated around the y-axis, thereby vibrating. Is excited. That is, the vibration is coupled in the θ direction around the y axis by the vibration of the floor 200 in the x direction.

  Then, the active vibration isolator 100 of Patent Document 1 cannot dampen vibrations in other degrees of freedom of the supported bodies 400 and 500 coupled by vibrations in the direction of certain degrees of freedom of the floor 200. The vibration isolation performance is insufficient.

  The present invention has been made in view of this point, and an object thereof is to improve the vibration isolation performance of the active vibration isolation device.

  In order to achieve the above object, the present invention isolates vibrations in the other direction of freedom of the supported body coupled by vibrations in a certain degree of freedom of the foundation by feedforward control.

  Specifically, the present invention provides an elastic body that elastically supports a supported body with respect to a foundation, a foundation-side vibration sensor that detects a vibration state of the foundation, and a vibration state that is detected by the foundation-side vibration sensor. And a control means for controlling the actuator based on the control and applying a control vibration having an opposite phase to the vibration transmitted from the foundation to the supported body. A solution was taken.

  That is, in the first invention, the control means attenuates the coupled vibration of the supported body that appears in another direction of freedom coupled to the vibration in a certain direction among the directions of freedom of the foundation. Therefore, based on the vibration state in the certain direction detected by the fundamental vibration sensor and the transfer function of the force transmitted from the vibration in the certain direction to the six-degree-of-freedom direction of the supported body, feed forward to the actuator is performed. Obtaining an operation reference amount, multiplying the feedforward operation reference amount by an inverse function of the transfer function of the actuator to obtain a feedforward operation amount to the actuator, and controlling the actuator based on the feedforward operation amount; The control vibration is added to the supported body.

  According to the first invention, the actuator is provided so that a control force can be applied to each of the six degrees of freedom with respect to the supported body. Then, the control means includes an actuator based on a vibration state in a certain direction among the directions of freedom of the foundation detected by the vibration sensor and a transfer function of a force transmitted from the certain direction to the six degrees of freedom direction of the supported body. Calculate the feedforward operation reference amount to. Here, if the actuator is controlled based on this feedforward operation reference amount, the feedforward operation reference amount changes due to the influence of the transfer function unique to the actuator, and appropriate control vibration cannot be applied to the supported body. Therefore, the feedforward operation amount is obtained by multiplying the feedforward operation reference amount by the reciprocal of the transfer function of the actuator, and the actuator is controlled based on the feedforward operation amount. Then, the control vibration having the opposite phase to the vibration in the 6-degree-of-freedom direction of the supported body coupled by the vibration in the 6-degree-of-freedom direction of the foundation can be added to the supported body. In this way, vibrations in each direction of freedom of the supported body coupled by vibrations in each direction of freedom of the foundation can be isolated, thus improving the vibration isolation performance of the active vibration isolation device. Can do.

  A second invention further comprises a supported-body-side vibration sensor for detecting a vibration state of the supported body in the first invention, and the control means is based on the vibration state detected by the supported-body-side vibration sensor. The actuator is feedback-controlled so that the vibration of the supported body is reduced.

  According to the second invention, the actuator can be operated so as to suppress this vibration in accordance with the actual vibration state of the supported body.

  According to a third invention, in the first or second invention, the basic vibration sensor is an acceleration sensor or an absolute velocity sensor.

  According to the third invention, since the acceleration sensor or the absolute speed sensor is used as means for detecting the vibration state of the foundation, the vibration state of the foundation can be detected with high accuracy. Therefore, since feedforward control can be performed while accurately detecting the vibration state of the foundation, an appropriate control force can be applied to the supported body so as to reduce the vibration.

  According to a fourth invention, in the second invention, the supported-body vibration sensor is an acceleration sensor or an absolute velocity sensor.

  According to the fourth invention, since the acceleration sensor or the absolute velocity sensor is used as the means for detecting the vibration state of the supported body, the vibration state of the supported body can be detected with high accuracy. Therefore, since feedback control can be performed while accurately detecting the vibration state of the supported body, an appropriate control force can be applied to the supported body so as to reduce the vibration.

  A fifth invention according to any one of the first to fourth inventions further comprises a displacement sensor for detecting a displacement of the supported body with respect to the foundation, and the control means is adapted to detect the displacement detected by the displacement sensor. Based on the above, the actuator is feedback-controlled so that the displacement becomes substantially constant.

  According to the fifth aspect, since the relative displacement of the supported body with respect to the foundation is substantially constant, the position of the supported body with respect to the foundation is maintained.

  According to a sixth invention, in any one of the first to fifth inventions, the foundation-side vibration sensor includes three sensors that detect vibrations in the vertical direction, the front-rear direction, and the left-right direction of the foundation. It is characterized by that.

  According to the sixth aspect of the invention, in order to perform vibration isolation control in consideration of vibrations in the rotation direction of the foundation, it is necessary to attach at least six vibration sensors to the foundation. Since the vibration in the direction is very small, it is often sufficient to configure the foundation-side vibration sensor with three sensors that detect vibrations in the vertical direction, the front-rear direction, and the left-right direction of the foundation. Thereby, vibration isolation control becomes simple and the number of parts can be suppressed.

  As described above, according to the present invention, the actuator is provided so that a control force can be applied to each of the six degrees of freedom with respect to the supported body. Then, the control means includes an actuator based on a vibration state in a certain direction among the directions of freedom of the foundation detected by the vibration sensor and a transfer function of a force transmitted from the certain direction to the six degrees of freedom direction of the supported body. Calculate the feedforward operation reference amount to. Here, if the actuator is controlled based on this feedforward operation reference amount, the feedforward operation reference amount changes due to the influence of the transfer function unique to the actuator, and appropriate control vibration cannot be applied to the supported body. Therefore, the feedforward operation amount is obtained by multiplying the feedforward operation reference amount by the reciprocal of the transfer function of the actuator, and the actuator is controlled based on the feedforward operation amount. Then, the control vibration having the opposite phase to the vibration in the 6-degree-of-freedom direction of the supported body coupled by the vibration in the 6-degree-of-freedom direction of the foundation can be added to the supported body. In this way, vibrations in each direction of freedom of the supported body coupled by vibrations in each direction of freedom of the foundation can be isolated, thus improving the vibration isolation performance of the active vibration isolation device. Can do.

It is a figure which shows typically the system configuration | structure of the vibration isolator which concerns on embodiment of this invention. It is the perspective view of the vibration isolator which showed the 6 degrees of freedom direction of the motion of a to-be-supported body. It is a block diagram of control about the φ direction. It is a figure which shows typically schematic structure of the conventional vibration isolator.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, the following description of preferable embodiment is only an illustration essentially, and is not intending restrict | limiting this invention, its application thing, or its use.

−Configuration of vibration isolation table−
1 and 2 show the overall configuration of a vibration isolation table A that embodies an active vibration isolation device according to the present invention. This vibration isolation table A is equipped with a precision device D that is susceptible to vibration, such as a semiconductor-related manufacturing apparatus or an electron microscope, on the surface plate 1 so as to be insulated from floor vibration as much as possible. Further, it is elastically supported by a plurality of isolators 2, 2,... (Elastic body). That is, in the vibration isolation table A, the surface plate 1 and the device D are supported bodies, and are also simply referred to as supported bodies 1 and D below.

  As an example, as shown in FIG. 2, in this embodiment, four isolators 2, 2,... Are arranged at the four corners of the surface plate 1, respectively, but any number of three or more may be used. As shown schematically in FIG. 1, each isolator 2 includes an air spring 20 a that supports a load in the vertical direction on the upper part of the inner case 20 disposed on the floor F (foundation). This is formed by inserting a piston in an airtight manner in an opening at the upper end of the inner case 20 via a diaphragm or the like, and defining an air chamber in the inner case 20.

  In the illustrated example, an outer case 21 that opens downward is disposed so as to cover the upper half of the inner case 20 from above, and the top plate is placed on the piston of the air spring 20a. Yes. On the other hand, there is a predetermined gap between the side plate of the outer case 21 and the side plate of the inner case 20. In this gap, a pair of air springs 20b, 20b having a configuration substantially similar to that of the air spring 20a is disposed so as to face each other with the inner case 20 interposed therebetween. These air springs 20b and 20b generate a horizontal force.

  In other words, the isolator 2 supports the shared load of the supported bodies 1 and D by the vertical air spring 20a, and increases and decreases the internal pressure of the vertical air spring 20a and the horizontal air springs 20b and 20b. By controlling, it is possible to add a control force that attenuates the vibration to the supported bodies 1 and D.

  More specifically, if the surface plate 1 that is a supported body and the device D thereon are regarded as an integral rigid body, and as shown in FIG. 2, three orthogonal axes x, y, and z passing through the center of gravity G of the rigid body are set. The degrees of freedom of motion in this Cartesian coordinate system are the three translational directions of the x-axis, y-axis, and z-axis and the three rotational directions φ, θ, and ψ around these axes. Therefore, the upper and lower and horizontal air springs 20a, 20b,... Of the four isolators 2, 2,.

  In the example shown in the figure, the two isolators 2, 2 on the right front side and the left back side (not shown) respectively increase or decrease the internal pressures of the horizontal pair of air springs 20b, 20b in opposite phases to each other in the x direction. In order to generate a control force Fx (hereinafter also simply referred to as the left-right direction), the two isolators 2 and 2 on the left front side and the right rear side each have a control force Fy in the y-direction (hereinafter also simply referred to as the front-rear direction). Are arranged to occur. With these four isolators 2, 2,..., A control force around the z-axis, that is, in the ψ direction can be applied to the supported bodies 1 and D.

  Further, the control force Fz in the z direction, which is the vertical direction, is generated by the upper and lower air springs 20a of each of the four isolators 2, 2,..., And the distribution of the force Fz generated by each of them. Is appropriately set according to the distance from the center of gravity G, it is possible to apply only the control force in the vertical direction to the supported bodies 1 and D. On the other hand, due to the distribution of the force Fz generated by the upper and lower air springs 20a of each of the four isolators 2, 2,..., The rotational directions around the x and y axes with respect to the supported bodies 1, D, that is, φ, θ Directional control force can be added. As described above, the air springs 20a and 20b included in each of the four isolators 2, 2,... Are provided so that a control force can be applied to the supported bodies 1 and D in directions of six degrees of freedom. Yes.

  In order to generate the required control force in this way, in this embodiment, as shown schematically in FIG. 1, the upper and lower and horizontal air springs 20a, 20b, 20b of each isolator 2 are not shown in the figure. A pipe for supplying compressed air from an air pressure source is connected. Then, the air supply / exhaust amount to the air springs 20a, 20b, 20b is adjusted by the servo valves 22a, 22b interposed in these pipes (note that only the right isolator 2 is shown in FIG. The air pressure control system is shown). In this embodiment, these air springs 20a and 20b constitute an actuator that applies a force to the supported bodies 1 and D.

  Each isolator 2 includes acceleration sensors 23a and 23b (supported side vibrations) that detect acceleration in the vertical and horizontal directions (that is, provided with a horizontal air spring 20b) of the surface plate 1 in the vicinity of the support position. Sensor). Signals from these acceleration sensors 23a and 23b are input to the controller 3 (control means). The accelerations of the supported bodies 1 and D detected by the acceleration sensors 23a and 23b are determined by the controller 3 to vibrate x ", y", z ", and φ" with 6 degrees of freedom of the center of gravity G of the supported bodies 1 and D. , Θ ″, ψ ″.

  Further, similarly to the acceleration sensors 23a and 23b, displacement sensors 24a and 24b for detecting vertical and horizontal displacements of the surface plate 1 in the vicinity of the support position are provided in each isolator 2, respectively. Further, an acceleration sensor 25 (basic vibration sensor) for detecting acceleration in the lower portion of the inner case 20, that is, floor vibration is also provided. This acceleration sensor 25 is arranged in three of the four isolators 2, 2,..., Two of which detect horizontal vibrations (ie, x and y directions) and the remaining One detects floor vibrations in the vertical direction. Signals from the displacement sensors 24 a and 24 b and the acceleration sensor 25 are also input to the controller 3. The displacements of the supported bodies 1 and D detected by the displacement sensors 24a and 24b are the displacements x-x0, y-y0, and z-z0 of 6 degrees of freedom of the center of gravity G of the supported bodies 1 and D by the controller 3. , Φ−φ0, θ−θ0, and φ−φ0. Here, x0, y0, z0, φ0, θ0, and ψ0 are displacements of the floor F in the respective degrees of freedom.

  The contents of control of the servo valves 22a and 22b by the controller 3 are substantially as shown in the block diagram of FIG. 3, and can be broadly divided into vibration isolation controls for canceling transmission vibration from the floor F to the supported bodies 1 and D. And vibration suppression control for canceling vibration generated by the device D and the like. That is, for the control inputs to the servo valves 22a and 22b, feedback control is performed by the feedback vibration control unit 3a based on signals from the acceleration sensors 23a and 23b as shown on the right side of the figure, and floor vibration is also controlled. Based on a signal from the acceleration sensor 25 to be detected, feedforward control is performed by the feedforward vibration control unit 3b.

  In addition to the feedback control and feedforward control described above, feedback control is performed by the feedback displacement control unit 3c based on the outputs from the displacement sensors 24a and 24b, as shown on the lower left side of the figure. In the vibration isolation table A of this embodiment, it is ideal that the surface plate 1 is always stationary, and the target value is constant without being changed, and is set to zero (0) here. Such feedback vibration control and feedforward vibration control are realized by a predetermined program being executed by the CPU of the controller 3, and are provided in the form of software.

  As a result of such various corrections, the operation amount in each direction with 6 degrees of freedom is determined, and the operation amount is distributed to the servo valves 22a and 22b according to the positions of the air springs 20a and 20b. The control outputs to the valves 22a and 22b are made, and the air springs 20a and 20b are operated as actuators by adjusting the air pressure of the air springs 20a and 20b by the operation of the servo valves 22a and 22b receiving the output signals. Thus, control vibration is applied to the supported bodies 1 and D.

  Hereinafter, each control will be described in detail. In the figure, for the sake of convenience, only the control in the φ direction, which is the rotation direction around the x axis, is shown, but the same control is performed in the vertical direction (z direction) and the horizontal direction (x direction and y direction). In addition, the rotation is also performed around the y-axis and the z-axis (θ direction, ψ direction).

-Control of vibration isolation table-
(Feedback vibration control)
First, the control by the feedback vibration control unit 3a will be described. This is the vibration state of the vibration isolation objects 1 and D detected by the acceleration sensor 23a and obtained from the arrangement of the acceleration sensor 23a, that is, the acceleration φ of the surface plate 1. The control force for reducing the vibration is generated by the air spring 20a on the basis of "". That is, the feedback gain corresponding to the detected acceleration .phi. "Is Gc, and the differential of this acceleration .phi." The feedback gain is set to Gm, and the feedback gain corresponding to the integral of the acceleration φ ″ is set to Gk. The feedback manipulated variable U1 is added to the feedback manipulated variable U1 to reverse the manipulated variable to the servo valve 22a. decide.

  By changing the opening degree of the servo valve 22a corresponding to the feedback operation amount U1, compressed air is supplied to or exhausted from the air spring 20a, and the internal pressure changes to change the object 1 for vibration isolation. A control force is added to D, which reduces the vibration. The vibration state (acceleration φ ″) of the vibration isolation objects 1 and D thus attenuated is detected again by the acceleration sensor 23a and fed back.

  When the air spring 20a is used as an actuator as in this embodiment, it is the opening degree of the servo valve 22a that is proportional to the feedback operation amount U1, and the internal pressure of the air spring 20a is proportional to the integral of the feedback operation amount U1. Therefore, if feedback is obtained by multiplying the acceleration φ ″ by the control gain Gc as described above, the control amount corresponding to this is integrated in the air system, resulting in a change in air pressure proportional to the absolute speed. The effect of a so-called skyhook damper can be obtained.

(Feed forward vibration isolation control)
Next, the control by the feedforward vibration control unit 3b will be described. This is because the acceleration sensor 25 detects the vertical acceleration z0 ″ and the horizontal acceleration x0 ″, y0 ″ of the vibration state of the floor F, and this vibration is detected. Corresponding to the transmission to the supported bodies 1 and D, the control vibrations in the opposite phase that cancel the transmission vibrations are generated by the air springs 20a and 20b. That is, the detected value z0 ″ of the acceleration sensor 25. , X0 ″, y0 ″, the feedforward manipulated variable U2 is calculated using, for example, a digital filter (or an analog filter), and the feedforward manipulated variable U2 is subtracted from the manipulated variable.

  Here, the feedforward operation amount U2 is obtained by the feedforward operation reference amount Uφ. This feedforward operation reference amount Uφ is generated as an output signal from the accelerations z0 ″, x0 ″, y0 ″ of the floor F detected by the acceleration sensor 25 by inputting them into the digital filter. In the embodiment, the feedforward operation reference amount Uφ is from the accelerations z0 ″, x0 ″, y0 ″ of the floor F and the accelerations z0 ″, x0 ″, y0 ″ of the floor F to the force in the φ direction of the supported bodies 1 and D. And is expressed as follows.

Uφ = ΣLny × (Cnz · s + Knz) × z0 ″ / s ² + ΣLnz × (Cny · s + Kny) × y0 ″ / s ² (Formula 2)
Here, Lny and Lnz in (Expression 2) are the coordinates in the y and z directions of the nth isolator 2 with the center of gravity G of the supported bodies 1 and D as the origin, and Knz and Kny are the nth isolator 2 respectively. The z-direction and y-direction spring constants Cnz and Cny are the damping coefficients of the n-th isolator 2 in the Z-direction and y-direction, respectively. The above transfer function can also be obtained by measurement.

  In other words, the filter coefficient of the digital filter of the feedforward vibration control unit 3b is set so as to be equivalent to the above (Equation 2). Setting can be easily performed by applying a conventionally known Z conversion method. Even when the feedforward vibration control unit 3b is configured by an analog circuit, the same setting can be easily performed by changing the capacitance of elements constituting the circuit.

On the other hand, the transfer function T of the force with respect to the inputs of the actuator, that is, the air spring 20a and the servo valve 22a, is
T = Kv · Am / (1 + Tv · s) (Formula 3)
It is represented by Here, Am is a pressure receiving area of the air spring 20a, Tv is an actuator time constant determined by the air spring 20a and the servo valve 22a, and Kv is an actuator gain determined by the air spring 20a and the servo valve 22a.

Therefore, the feedforward operation amount U2 is obtained by multiplying the feedforward operation reference amount Uφ by the inverse function of the actuator transfer function T. That is,
U2 = Uφ · T ⁻¹
= (1 + Tv · s) / (Kv · Am) × Uφ (Formula 4)
It is expressed.

  Therefore, the feedforward operation reference amount Uφ corresponding to the accelerations z0 ″, x0 ″, y0 ″ of the floor F is calculated according to the above (Expression 2), and the transfer function T indicating the characteristics of the actuator is calculated as the feedforward operation reference amount Uφ. Multiply the inverse function to determine the feedforward manipulated variable U2, reverse it and add it to the input to the servo valve 22a, thereby coupling from the vibrations of the floor F in the z-axis, x-axis, and y-axis directions. The control vibration having the opposite phase to the coupled vibration is added by the isolator 2 to the vibration in the φ direction of the center of gravity G of the supported bodies 1 and D, and the φ direction of the center of gravity G of the supported bodies 1 and D is added. Can be effectively isolated.

(Feedback displacement control)
Finally, the outline of the feedback displacement control unit 3c will be described. This is the displacement of the surface plate 1 detected by the displacement sensor 24a in the φ direction (rotation direction around the x axis) (relative displacement relative to the base side) φ−φ0. Based on the above, the internal pressure of the air spring 20a is adjusted so that this displacement becomes small. That is, as shown in the figure, after the detected relative displacement φ−φ0 is subtracted from the position control target value, that is, zero (0), the feedback manipulated variable U3 is obtained according to the PID control law.

  Note that φ−φ0 is an output of the displacement sensors 24a and 24b, and is adjusted such that 0 is output when the positions of the supported bodies 1 and D are at the reference position.

  When the opening degree of the servo valve 22a is changed corresponding to the feedback operation amount U3, the compressed air is supplied to or exhausted from the air spring 20a, and the internal pressure changes to change the φ direction of the supported bodies 1 and D. Is changed so that the deviation from the reference position in the φ direction becomes small, that is, the initial set position. The position in the φ direction of the supported bodies 1 and D thus changed is detected again by the displacement sensor 24a and fed back.

-Effects of the embodiment of the invention-
According to the above-described embodiment, the actuator is provided so that a control force can be applied in each of the six degrees of freedom with respect to the center of gravity G of the supported bodies 1 and D. The controller 3 then detects vibrations in the z-axis, x-axis, and y-axis directions of the floor F detected by the acceleration sensors 23a and 23b, that is, accelerations z0 ″, x0 ″, and y0 ″ of the floor F in these three directions. Then, the feedforward operation reference amount Uφ to the actuator is obtained from the transfer function of the force transmitted in the φ direction of the center of gravity G of the supported bodies 1 and D from the vibrations in the three directions. If the actuator is controlled based on the above, the feedforward operation reference amount Uφ is changed by the transfer function T unique to the actuator, and appropriate control vibration cannot be applied to the supported bodies 1 and D. Therefore, the feedforward operation is performed. A feedforward operation amount U2 obtained by multiplying the reference amount Uφ by the reciprocal of the transfer function T of the actuator is obtained, and based on this, the actuator Then, the controlled vibration having the opposite phase to the vibration in the φ direction of the center of gravity G of the supported bodies 1 and D coupled by the vibration in the three directions of the x axis, the y axis and the z axis of the floor F is supported. Since the vibration in the φ direction of the supported bodies 1 and D coupled by the vibration of the floor F can be isolated in this way, the vibration isolation of the vibration isolation table A can be performed. The performance can be improved as compared with the prior art.

  Moreover, according to the said embodiment, according to the actual vibration state of the to-be-supported bodies 1 and D, the air spring 20a can be operated so that this vibration may be suppressed by the feedback vibration control part 3a.

  Furthermore, according to the above embodiment, the acceleration sensors 23a and 23b and the acceleration sensor 25 are used as means for detecting the vibration state of the surface plate 1 and the vibration state of the floor F, respectively. The vibration state can be detected with high accuracy. Therefore, since the feedback vibration control unit 3a and the feedforward vibration control unit 3b can control the vibration state of the surface plate 1 and the floor F with high accuracy, the vibrations of the supported bodies 1 and D are reduced. Appropriate control force can be added.

  Furthermore, according to the above-described embodiment, the feedback displacement control unit 3c reduces the deviation of the supported bodies 1 and D from the position in the φ direction serving as a reference with respect to the floor F of the supported bodies 1 and D. The directional position is maintained.

In the above-described embodiment, a mode is described in which vibrations in the φ direction of the supported bodies 1 and D coupled by vibrations in the x-axis, y-axis, and z-direction of the floor F, that is, three translational directions are described. However, the present invention is not limited to this. For example, the vibration in the z direction of the center of gravity G of the supported bodies 1 and D coupled by the vibration in the three translational directions of the floor F is caused by the feedforward vibration control unit 3b of the above embodiment. Vibration may be controlled by control. At that time, the feedforward operation reference amount Uz in the z direction obtained by the feedforward vibration control unit 3b is
Uz = Σ (Cnz · s + Knz) × z0 ″ / s ² (Formula 5)
It is represented by Here, Cnz is an attenuation coefficient in the z direction of the nth isolator 2, and Knz is a spring constant in the z direction of the nth isolator 2.

Similarly, when the vibration in the x direction of the center of gravity G of the supported bodies 1 and D coupled by the vibration in the three translational directions of the floor F is isolated by the feedforward vibration control, it is obtained by the feedforward vibration control unit 3b. The feedforward operation reference amount Ux in the x direction is
Ux = Σ (Cnx · s + Knx) × x0 ″ / s ² (Formula 6)
It is represented by Here, Cnx is an attenuation coefficient in the x direction of the nth isolator 2, and Knx is a spring constant of the nth isolator 2 in the x direction.

Similarly, when the vibration in the y direction of the center of gravity G of the supported bodies 1 and D coupled by the vibration in the three translational directions of the floor F is isolated by the feedforward vibration control, the feedforward vibration control unit 3b obtains the vibration. The feed-forward operation reference amount Uy in the y direction is
Uy = Σ (Cny · s + Kny) × y0 ″ / s ² (Expression 7)
It is represented by Here, Cny is a damping coefficient in the y direction of the nth isolator 2, and Kny is a spring constant in the y direction of the nth isolator 2.

Furthermore, the rotational directions of the center of gravity G of the supported bodies 1 and D coupled by the vibration in the three translational directions of the floor F, that is, the θ direction (the rotational direction around the y axis) and the ψ direction (the rotational direction around the z axis). Feedforward operation reference amounts Uθ and Uψ obtained by the feedforward vibration control unit 3b when the vibrations of
Uθ = −ΣLnx × (Cnz · s + Knz) × z0 ″ / s ² −ΣLnz × (Cnx · s + Knx) × x0 ″ / s ² (Equation 8)
Uψ = −ΣLny × (Cnx · s + Knx) × x0 ″ / s ² + ΣLnx × (Cny · s + Kny) × y0 ″ / s ² (Equation 9)
It is represented by Here, Lnx, Lny, and Lnz are coordinates in the x, y, and z directions of the nth isolator 2 with the center of gravity G of the supported bodies 1 and D as the origin.

  Moreover, in the said embodiment, although the vibration of the to-be-supported body 1 and D coupled from the vibration of the translation F of 3 directions of the floor F is isolated by feedforward vibration control, only the vibration of the translation 3 direction of the floor F is carried out. Instead, the vibrations of the supported bodies 1 and D coupled from the vibrations in the three rotation directions (φ direction, θ direction, and ψ direction) may be isolated by feedforward vibration control. In that case, a total of six acceleration sensors in the z direction and the x direction or the z direction and the y direction are provided on the three legs of the four isolators 2 so that the three translational directions and the respective rotation directions of the floor F can be detected in each isolator 2. 25 and the output of these acceleration sensors 25 is input to the controller 3.

  However, since the vibration in the rotational direction of the floor F is very small, the supported bodies 1 and D may be isolated based only on the vibration in the three directions of the floor F as in the above embodiment. Therefore, as shown in the above embodiment, the acceleration sensor 25 may be configured by three sensors that detect vibrations of the floor F in the vertical direction, the front-rear direction, and the left-right direction. Thereby, vibration isolation control is simplified and the number of parts can be suppressed.

  Moreover, in the said embodiment, although air spring 20a, 20b is used as an actuator, it is not limited to this, For example, you may use a linear motor, a piezoelectric element, etc.

  Furthermore, in the said embodiment, although acceleration sensor 23a, 23b, 25 is an acceleration sensor, it is not limited to this, For example, an absolute speed sensor may be sufficient.

  As described above, the active vibration isolator according to the present invention is applied to a use for isolating vibrations in other degrees of freedom of the supported body coupled by vibrations in a certain degree of freedom direction of the foundation. Can do.

1 Surface plate (supported body)
2 Isolator (elastic body)
3 Controller (control means)
20a, 20b Air spring (actuator)
23a, 23b Acceleration sensor (supported body side vibration sensor)
24a, 24b Displacement sensor 25 Acceleration sensor (basic vibration sensor)
A Vibration isolation table (active vibration isolation device)
D equipment (supported body)
F floor (basic)

Claims (6)

An elastic body for supporting the supported body with respect to the foundation;
A foundation side vibration sensor for detecting the vibration state of the foundation;
And a control means for controlling the actuator based on the vibration state detected by the foundation-side vibration sensor and adding a control vibration having an opposite phase to the vibration transmitted from the foundation to the supported body. A vibration device,
The actuator is provided such that a control force can be applied to each of the six degrees of freedom with respect to the supported body,
The control means is configured to reduce the coupled vibrations of the supported body that are coupled to vibrations in one direction among the directions of freedom of the foundation and appear in other directions of freedom. Based on the vibration state detected in the certain direction and the transfer function of the force transmitted from the vibration in the certain direction in the direction of 6 degrees of freedom of the supported body, a feedforward operation reference amount to the actuator is obtained, and the feed The feed forward operation amount to the actuator is obtained by multiplying the forward operation reference amount by the inverse function of the transfer function of the actuator, the actuator is controlled based on the feed forward operation amount, and the controlled vibration is applied to the supported body. The active vibration isolator characterized by adding. The active vibration isolator according to claim 1.
A supported body side vibration sensor for detecting a vibration state of the supported body;
An active vibration isolation device, wherein the control means feedback-controls the actuator based on a vibration state detected by the supported-body vibration sensor so that the vibration of the supported body is reduced. In the active vibration isolator according to claim 1 or 2,
The active vibration isolation device, wherein the basic vibration sensor is an acceleration sensor or an absolute velocity sensor. In the active vibration isolator according to claim 2,
The active vibration isolator according to claim 1, wherein the supported-body vibration sensor is an acceleration sensor or an absolute velocity sensor. The active vibration isolator according to any one of claims 1 to 4,
A displacement sensor for detecting the displacement of the supported body with respect to the foundation;
An active vibration isolation device, wherein the control means feedback-controls the actuator so that the displacement becomes substantially constant based on a displacement detected by the displacement sensor. The active vibration isolator according to any one of claims 1 to 5,
The base vibration sensor is composed of three sensors for detecting vibrations in the front-rear direction, the left-right direction, and the vertical direction of the foundation.

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