JPH11141596A - Active vibration resistance device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an active vibration resistance device which can ensure a satisfactory vibration resisting performance in a high frequency region without generating a resonance point in a low frequency region. SOLUTION: Signals from a first sensor 16 to sense the vibrating condition of an object for vibration resistance O and a second sensor 17 to sense the vibrating condition of an intermediate mass element 13 are fed to a control device 18, whereby a signal is produced and emitted form generating a voltage change in the power input part 12 of a piezo element 11 so that a vibration to set off the vibration of object O in its working direction arise in the intermediate mass element 13.

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 suitable for removing fine vibrations of precision equipment in, for example, a semiconductor manufacturing plant or a product manufacturing plant using a laser.

[0002]

2. Description of the Related Art Conventionally, in JP-A-5-149379,
An active vibration isolator using a piezo element has been proposed. This active vibration isolator is composed of a spring mass point system having one degree of freedom using a spring means having a large compression rigidity and a low shear rigidity in which thin elastic bodies and metal plates are alternately laminated, and an actuator using a piezo element. It has a basic structure including a feedback control loop. In addition, an active vibration isolator in which an intermediate mass element is interposed in a spring mass point system has been proposed. The active vibration isolation device uses the detected value of the vibration state of the intermediate mass element as a feedback signal,
Based on this feedback signal, a feedback control loop configured to drive a piezo element directly connected to the intermediate mass element has a basic structure.

[0003]

In the case of each of the above-described active vibration isolation devices, the vibration isolation performance in the high frequency range depends on the passive vibration isolation characteristics, so that the fine vibrations of precision equipment and the like are eliminated. For example, if the frequency is 30
In the vicinity of 0 Hz, for example, vibration isolation of about −60 dB (−60 dB
In the case of trying to obtain the vibration transmission rate of B, the following disadvantages occur.

In order to achieve a vibration isolation of about -60 dB at a frequency around 300 Hz, as shown by a curve II (broken line) in FIG. 7, a resonance point of the vibration system including the active vibration isolation device and the vibration isolation target is required. Needs to be around 3 to 4 Hz. Therefore, increase the amplitude of the piezo element,
The spring constant of the spring means must be reduced.
However, since the magnitude of the amplitude of the piezo element is limited,
It is practically impossible to achieve the above resonance point in a low frequency region of 10 Hz or less by a piezo element. On the other hand, when the spring constant is reduced, a problem arises in that the amplitude of the vibration of the vibration isolation target increases.

[0005] Therefore, in the case of a single-degree-of-freedom spring mass point system,
As shown by the curve III (dashed-dotted line) in FIG. 7, the resonance point can be set at around 15 Hz at most (this value depends on the amplitude of the actuator). Can not get. In the case of a two-degree-of-freedom spring mass point system, a curve IV in FIG.
As shown by the two-dot chain line, the vibration isolation performance in the high frequency region is improved, but the above-mentioned resonance point occurs at two places. SUMMARY OF THE INVENTION The present invention has been made to solve the above-described conventional problems, and has been made in consideration of the problem that active vibration isolation can be obtained in a high frequency region without generating a resonance point in a low frequency region. It is intended to provide a vibration device.

[0006]

According to a first aspect of the present invention, a support surface is provided at one end in a working direction along a length direction which changes due to a change in a voltage or a magnetic field generated inside. A solid-state element fixed to the solid-state element, a power input unit for changing the voltage or the magnetic field in the solid-state element, and an intermediate member located between the other end of the solid-state element and the object to be isolated in the action direction. A mass element, one end fixed to the intermediate mass element, the other end fixed to the vibration isolation target, a first elastic member that exerts a spring action on the intermediate mass element and the vibration isolation target; A second elastic member fixed to the solid element and having the other end fixed to the intermediate mass element, and exerting a spring action on the solid element and the intermediate mass element;
A first sensor for detecting a vibration state of the vibration isolation target in the working direction, a second sensor for detecting a vibration state of the intermediate mass element in the working direction, and signals from the first and second sensors. A signal for causing a voltage change or a magnetic field change in the power input unit of the solid-state element so as to cause the intermediate mass element to generate vibration that cancels the vibration in the action direction of the vibration isolation target in the input direction. And an output controller.

According to a second aspect of the present invention, there is provided a linear motor having one end fixed in a working direction along a length direction which changes due to a change in a magnetic field on a support surface, and having a spring action. A power input unit to be changed, an intermediate mass element fixed to the other end of the linear motor in the operation direction, and one end fixed to the intermediate mass element in the operation direction, and the other end to the vibration damping target. A second elastic member that is fixed and exerts a spring action on the intermediate mass element and the vibration isolation target; a first sensor that detects a vibration state of the vibration isolation target in the operation direction; A second sensor for detecting a vibration state in the action direction, a signal input from the first sensor and the second sensor, and a vibration for canceling the vibration in the action direction of the vibration-removal target. It was composed of a control unit for outputting a signal for causing a voltage change or the magnetic field change in the power input section of the linear motor so as to cause between the mass element.

Further, the third invention provides an air actuator having a spring action, one end of which is fixed on a support surface in a working direction along a length direction which changes due to a change in air pressure, and the air actuator in this air actuator. A power input unit for changing pressure, an intermediate mass element fixed to the other end of the pneumatic actuator in the operation direction, and one end fixed to the intermediate mass element in the operation direction, and A second elastic member fixed to the object and exerting a spring action on the intermediate mass element and the vibration isolation target; a first sensor for detecting a vibration state of the vibration isolation target in the operation direction; A second sensor for detecting a vibration state in the action direction of the first sensor and the first sensor.
A voltage change or a magnetic field is applied to the power input unit of the air actuator so that a signal is input from the sensor and the second sensor and a vibration is generated in the intermediate mass element to cancel the vibration of the vibration isolation target in the operation direction. And a control device for outputting a signal for causing a change.

Further, according to a fourth aspect of the present invention, in the control device, the control device outputs a signal from the first sensor to a first control element, an adder,
Forming a main feedback system for feeding back to the power input unit via a control element; and a local feedback system for feeding back a signal from a second sensor to the power input unit via the adder and the second control element. An operating force for canceling the vibration of the intermediate mass element by the local feedback system is generated in the solid element, or the linear motor or the air actuator, and the main feedback system causes the object to be vibration-isolated in the action direction. The solid element, the linear motor, or the pneumatic actuator generates an operating force that causes the intermediate mass element to generate vibration that cancels the vibration.

In a fifth aspect of the present invention, the solid element is formed of a piezoelectric element.

In a sixth aspect of the present invention, the solid-state element is formed of a magnetostrictive material.

Further, in the seventh invention, each of the first sensor and the second sensor is an acceleration sensor.

[0013]

Next, an embodiment of the present invention will be described with reference to the drawings. Figure 1 is a diagram showing a state of applying the active anti-vibration apparatus 1A in the vibration damping subject O mass m ₁ according to the present invention. This active vibration isolator 1A
Denotes a piezoelectric element 11 which is an example of a solid-state element;
The power input portion 12, the intermediate mass element 13 of the mass m _2, the first elastic member 14 of the spring constant k _1, the second elastic member 15 of the spring constant k _2, the first sensor 16, second sensor 17 and the control unit 18 Consists of

As is well known, the piezoelectric element 11 has a characteristic that its thickness changes due to a change in voltage generated therein, and its longitudinal direction, that is, the vertical direction in FIG. In FIG. 1, the lower end is fixed to a support surface F, for example, a floor surface. The power input unit 12 applies an operation voltage to the piezoelectric element 11 based on a control signal input from the control device 18. The intermediate mass element 13 is
In the working direction, the piezoelectric element 11 is located between the other end of the piezoelectric element 11 and the vibration-removal target O.

The first elastic member 15 has one end fixed to the intermediate mass element 13 and the other end fixed to the vibration isolation target O, and exerts a spring action on the intermediate mass element 13 and the vibration isolation target O. The second elastic member 14 has one end fixed to the piezoelectric element 11 and the other end fixed to the intermediate mass element 13, and exerts a spring action on the piezoelectric element 11 and the intermediate mass element 13. The first sensor 16 is a second sensor 17 that detects a vibration state of the vibration-removal target O in the action direction, in this embodiment, acceleration.
Is a vibration state of the intermediate mass element 13 in the above-described working direction, and in this embodiment, an acceleration is detected. Control device 18
The piezoelectric element 1 receives signals from the first sensor 16 and the second sensor 17 and causes the intermediate mass element 13 to generate a vibration that cancels the vibration of the object O in the above-described working direction.
The first power input unit 12 outputs a signal causing a voltage change.

More specifically, the control device 18 includes a first
The signal from the sensor 16 is sent to the first control element 21 and the adder 2
2. A main feedback system M that feeds back to the power input unit 12 via the second control element 23, and a signal from the second sensor 17 is fed back to the power input unit 12 via the adder 22 and the second control element 23. And a local feedback system L. The local feedback system L causes the piezoelectric element 11 to generate an operating force u for canceling the vibration of the intermediate mass element 13. Furthermore, the main feedback system M causes the piezoelectric element 11 to generate an operating force that causes the intermediate mass element 13 to generate a vibration that cancels the vibration of the object O in the above-described working direction.

As described above, the active vibration isolator 1A positively utilizes the vibration isolation characteristics resulting from the interaction between the intermediate mass element 13 and each of the first elastic member 14 and the second elastic member 15. Thereby, the intermediate mass element 13,
The vibration of the vibration isolation target O is indirectly controlled so that the vibration of the support surface F serving as the vibration source of the vibration isolation target O is canceled by the piezoelectric element 11 which is an example of the actuator.

The design of the active vibration isolator 1A is performed in the following order. The control gain of the local feedback system L that performs active control so as to cancel the vibration of the support surface F, for example, the vibration of the intermediate mass element 13 due to the floor vibration is determined. Local feedback system L such that the control gain of local feedback system L acts as a forward element.
An adder 22 is interposed as an addition point for. The control gain of the main feedback system M is determined so that a signal for causing the piezoelectric element 11 to generate a vibration for canceling the vibration of the vibration isolation target O is input to the adder 22.

The control characteristics of each feedback system of the active vibration isolator 1A configured as described above can be expressed as follows using a transfer function. First, the second
Intermediate mass element 1 from piezoelectric element 11 via elastic member 15
3 when the operating force u acts on the intermediate mass element 1
3. The characteristics of the passive control system including the vibration isolation target O can be expressed by the following equation of motion.

(Equation 1) m ₁ : mass of the vibration damping object O m ₂ : mass of the intermediate mass element 13 x ₁ : displacement of the vibration damping object O in the above acting direction x ₂ : displacement of the intermediate mass element 13 in the above acting direction

In equation (1), damping elements included in the system are ignored for simplicity.
When the Laplace transform of the equation (1) is performed, the open loop from the operation force u on the intermediate mass element 13 as the input to the acceleration x ₁ ″ and x ₂ ″ of the intermediate mass element 13 and the vibration isolation target O as the output, Transfer functions G ₁ and G ₂ between the input and the output can be expressed as follows. Note that the same symbols are used for x ₁ ″, x ₂ ″, u, m ₁ , m ₂ , k ₁ , and k ₂ even after Laplace transform. Also, s
Is the Laplace operator.

(Equation 2)

Next, considering the input from the main feedback system M to the adder 22 described in the design procedure,
The local feedback system L can be represented as shown in FIG. Note that x ₀ represents the displacement of the support surface F in the above acting direction, and x ₀ ″ represents the acceleration as the vibration state of the support surface F. Therefore, the operating force u and the acceleration x ₂ ″ of the intermediate mass element 13. The transfer function between and can be expressed as:

(Equation 3) H ₂ : transfer characteristic of the second control element

Further, vibration of the support surface F (acceleration x ₀ ″)
And the transfer function between the intermediate mass element 13 and the acceleration x ₂ ″ can be expressed as:

(Equation 4) Considering that the operation force u and the acceleration x ₁ ″ of the object O are related by the transfer function G ₁ , the first elastic element 14 and the object O are added to the system shown in FIG. 3 can be represented as shown in Fig. 3. In addition, the operating force u in the active control system including the first elastic element 14 and the object O to be isolated.
A transfer function between the vibration isolation target O and the acceleration x ₁ ″ can be expressed as follows.

(Equation 5)

Therefore, considering that the output r from the first control element 21 is input to the adder 22 as a target value as shown in FIG. 1, the system shown in FIG. 1 is represented as shown in FIG. be able to. That is, the system shown in FIG. 1 and the system shown in FIG. 4 are equivalent. As is clear from FIG.
2 including the input of the target value r to the support surface F
The transfer function between the vibration of the acceleration x ₀ ″ and the object O to be isolated can be expressed as follows.

(Equation 6) H ₁ : transfer characteristic of the first control element 21

From the equation (7), the first and second control elements 21,
23, the transfer characteristics H ₁ and H ₂ are included only in the denominator, and a feedback gain is given to the first and second control elements 21 and 23 to transmit the vibration from the support surface F to the object O to be isolated. It can be easily understood that the rate is small. Further, the block diagram shown in FIG. 4 can be represented as shown in FIG. As described above, the first and second control elements 2
It can be seen that the transfer characteristics H ₁ and H ₂ of ₁ , 23 cooperate with each other to contribute to vibration isolation.

In the above embodiment, the device using the piezoelectric element 11 as a solid element is shown. However, the present invention is not limited to this, and a magnetostrictive element may be used instead of the piezoelectric element 11. In this case, the magnetostrictive element that changes the strength of the magnetic field due to the change in the current is vibrated by the power input unit. In FIG. 1, as indicated by the two-dot chain line,
An elastic member 24 may be provided between the support surface F and the intermediate mass element 13 in parallel with the piezoelectric element 11 and the second elastic member 15. Also in this case, as described above, the transfer characteristics H ₁ and H ₂ of the first and second control elements 21 and 23 cooperate with each other to contribute to vibration isolation. In FIG. 7, a curve I (solid line) indicates the vibration isolation characteristics of the active vibration isolation device according to the above-described embodiment, where no resonance point exists in the low frequency region, and the vibration isolation performance is improved in the high frequency region. ing.

FIG. 6 shows a state in which another active vibration isolator 1B according to the present invention is applied to a vibration isolation target O having a mass m _1. The active vibration isolator 1A shown in FIG. The other components are substantially the same except that an air actuator or a linear motor 31 is used instead of the element 11 and the second elastic member 15. As shown in FIG. 6, the pneumatic actuator or the linear motor 31 is functionally composed of a driving unit 32 that vibrates the intermediate mass element 13 and an elastic element 33 that exerts a spring action on the intermediate mass element 13. Has become. This will be active anti-vibration apparatus 1B, true description of Formulas described above by the spring constant of the elastic element 33 and k _2.

Although the damping element included in the system has been neglected as described above, the equation becomes complicated when the term of the damping action is added to the above equation even when this damping element is considered. By giving a feedback gain to the second control elements 21 and 23, the transmission rate is still reduced. Although the above-described embodiment is a two-degree-of-freedom system, a plurality of active vibration isolation devices 1 according to the present invention may be arranged on one vibration isolation target O. For example, the active vibration isolation device may be arranged in each of three X, Y, and Z directions orthogonal to each other, and a 12-degree-of-freedom system including two rigid bodies (the vibration isolation target O and the intermediate mass element 13). It is also extensible.

In this case, the first sensor 16 and the second sensor 1
7 and the piezoelectric element 11 do not necessarily have to have a one-to-one relationship. For example, three first sensors 16 and three second sensors 17 may be provided at different positions and directions, and five piezoelectric elements 11 may be provided at different positions and directions. In this case, signals from one first sensor 16 and one second sensor 17 are not necessarily used only for controlling one piezoelectric element 11, and are also used for controlling another piezoelectric element 11. You may. Further, a plurality of intermediate mass elements 13 are provided for one vibration isolation target O, and the first sensor 16, the second sensor 17, An anti-vibration control system of the active anti-vibration device including the piezoelectric element 11 may be configured. The above points are the same when a magnetostrictive element, an air actuator, or a linear motor is used. Furthermore, a speed detector may be used as the first sensor 16 and the second sensor 17, and the present invention also includes an active vibration isolator including these components.

[0029]

As is apparent from the above description, according to the present invention, signals are input from the first sensor for detecting the vibration state of the object to be damped and the second sensor for detecting the vibration state of the intermediate mass element. The control device is used to cause a voltage change or a magnetic field change in the power input unit such as the solid-state element so as to cause the intermediate mass element to generate a vibration that cancels the vibration in the working direction of the vibration isolation target. Is formed so as to output a signal. For this reason, an object of the present invention is to provide an active vibration isolation device that can obtain sufficient vibration isolation performance in a high frequency region without generating a resonance point in a low frequency region. There is an effect that a vibration transmissibility of about −60 dB can be achieved at around 300 Hz without generating a resonance point.

[Brief description of the drawings]

FIG. 1 is a diagram schematically illustrating a state in which an active vibration isolation device according to the present invention is applied to a vibration isolation target.

FIG. 2 is a control block diagram of a passive control system including an intermediate mass element and an object to be isolated.

FIG. 3 is a control block diagram of a system in which a first elastic element and a vibration damping target are added to the system shown in FIG. 2;

FIG. 4 is a control block diagram of the system shown in FIG. 1;

FIG. 5 is a control block diagram equivalent to the control block diagram shown in FIG. 4;

FIG. 6 is a diagram schematically illustrating a state in which another active vibration isolation device according to the present invention is applied to a vibration isolation target.

FIG. 7 is a diagram showing a frequency characteristic of a vibration transmissibility of a spring mass point system.

[Explanation of symbols]

1A, 1B Active anti-vibration device 11 Piezoelectric element 12 Power input unit 13 Intermediate mass element 14 First elastic element 15 Second elastic element 16 First sensor 17 Second sensor 18 Control device 21 First control element 22 Adder 23 Second control element 31 the air actuator or linear motor 32 driving unit 33 elastomeric element F supporting surface O object to be vibration-isolated M main feedback system L local feedback system m _1, m ₂ weight k _1, k ₂ spring constant u operating force H _1, H ₂ transfer characteristics

Claims (7)

[Claims] 1. A solid state element having one end fixed to a support surface in a working direction along a length direction which changes due to a change in a voltage or a magnetic field generated therein, and the voltage or the magnetic field in the solid state element. A power input unit that changes the mass direction, an intermediate mass element positioned between the other end of the solid state element and the vibration isolation target in the action direction, one end fixed to the intermediate mass element, and the other end A first elastic member fixed to the vibration isolation target and exerting a spring action on the intermediate mass element and the vibration isolation target; one end fixed to the solid state element and the other end fixed to the intermediate mass element; A second elastic member that exerts a spring action on the solid element and the intermediate mass element; a first sensor that detects a vibration state of the vibration damping object in the operation direction; and a vibration state of the intermediate mass element in the action direction. Detect A second sensor that emits a signal from the first sensor and the second sensor, and the solid-state element is configured to generate, in the intermediate mass element, vibration that cancels vibration of the object to be isolated in the operation direction. An active vibration isolator comprising: a controller for outputting a signal for causing a voltage change or a magnetic field change to the power input unit. 2. A linear motor having one end fixed in a working direction along a direction of a length that changes due to a change in a magnetic field on a support surface and having a spring action, and a power input unit for changing the magnetic field in the linear motor. An intermediate mass element fixed to the other end of the linear motor in the operation direction; one end is fixed to the intermediate mass element and the other end is fixed to the vibration isolation target in the operation direction. A second elastic member that exerts a spring action on the mass element and the vibration removing target; a first sensor that detects a vibration state of the vibration removing target in the working direction; and a vibration state of the intermediate mass element in the working direction. And a signal that is input from the first sensor and the second sensor to detect the vibration in the action direction of the object to be removed in the intermediate mass element. An active vibration isolator which outputs a signal for causing a voltage change or a magnetic field change to be generated at the power input portion of the linear motor so as to cause the change. 3. An air actuator having a spring action, one end of which is fixed on a support surface in a working direction along a length direction which changes according to a change in air pressure, and a power for changing the air pressure in the air actuator. An input unit, an intermediate mass element fixed to the other end of the pneumatic actuator in the action direction; A second elastic member that exerts a spring action on the intermediate mass element and the vibration isolation target; a first sensor that detects a vibration state of the vibration isolation target in the operation direction; A signal is input from the second sensor for detecting a vibration state, the first sensor, and the second sensor, and the vibration of the vibration-removal target in the action direction is canceled. An active vibration isolator comprising: a controller that outputs a signal for causing a voltage change or a magnetic field change at the power input portion of the air actuator so as to cause vibration in the intermediate mass element. 4. A main feedback system wherein the control device feeds back a signal from the first sensor to the power input unit via a first control element, an adder, and a second control element. The signal is added to the adder, the second
A local feedback system for feeding back to the power input unit via a control element, wherein the operating force for canceling the vibration of the intermediate mass element by the local feedback system is applied to the solid element, or the linear motor or the air. Actuating force is applied to the solid element, or the linear motor or the pneumatic actuator, which causes the actuator to generate an operation force in the intermediate mass element to cause the intermediate mass element to vibrate in the action direction of the object to be isolated by the main feedback system. 4. The active vibration isolator according to claim 1, wherein the active vibration isolator is generated. 5. The active vibration isolator according to claim 1, wherein the solid element is formed by a piezoelectric element. 6. The active vibration isolator according to claim 1, wherein the solid element is formed of a magnetostrictive material. 7. Each of the first sensor and the second sensor,
7. The active vibration isolator according to claim 1, wherein the active vibration isolator is an acceleration sensor.