JPH0419439A - Active vibration isolating device - Google Patents

Abstract

PURPOSE:To wide improve vibration isolating performance by providing gain/ phase correcting circuits, which correct a gain and a phase of signals by inputting the signals selected from a group consisting of absolute acceleration signal, absolute speed signal and a relative displacement signal, and an actuator. CONSTITUTION:In outputs of obtained absolute acceleration signal, absolute speed signal, relative displacement signal, a gain and a phase of the output are respectively corrected by inputting the outputs respectively to gain/phase correcting circuits A, B, C having respectively different gains G1(S), G2(S), G3(S). Signals from the gain/phase correcting circuits A, B, C are added and synthesized in an adder 18. This synthesized signal is inverted in an inverter circuit 19 and input to a driver circuit 20. A phase of the driver circuit 20 is 0 deg. flat. A drive signal from this driver circuit 20 is inputted to an actuator 14 to drive the actuator 14. Movement of the actuator 14 is in a direction of suppressing vibration of a control object 12, and in this way, the vibration of the control object 12 is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an active vibration isolator, and particularly to an active vibration isolator that can set the natural frequency and damping arbitrarily and can significantly improve vibration isolation performance.

[Prior Art] Passive vibration isolating devices that passively control a controlled object supported by an air spring and a vibration isolating material such as a dashpot have been well known.

Recently, instead of passive vibration isolators, active or semi-active vibration isolators that actively control the controlled object are being adopted (Japanese Patent Laid-Open No. 60-1213
Publication No. 40).

This active vibration isolator uses an actuator to inject energy into the vibration isolator from the outside, and uses the theory of linear feedback control or linear feedforward control to actively improve the vibration isolation or insulation effect of the vibration isolator. It is something.

[Problems to be Solved by the Invention] There are still very few examples of active control of a controlled object supported by such a vibration isolating material, but one of the control techniques is: ■ Absolute acceleration signal ■ Absolute velocity signal ■ There is a method of vibration isolation using absolute displacement signals.

However, in this case it is extremely difficult to obtain an absolute displacement signal. Furthermore, displacement sensors that output absolute displacement signals are extremely rare and expensive. In addition, in the case of minute vibrations, extracting the absolute displacement from the speed sensor or acceleration sensor by integration is difficult due to offset, drift, S
At present, this cannot be said to be desirable due to the problem of /N ratio.

[Purpose of the Invention] The present invention was made in view of the difficulties faced by sloped surfaces.The purpose of the present invention is to use a relative displacement signal instead of an absolute displacement signal to set the natural frequency and damping arbitrarily, thereby significantly improving vibration isolation performance. The purpose of the present invention is to provide an active vibration isolator that can improve the performance.

[Means for Solving the Problems] In order to achieve this object, the vibration isolating device of the present invention is installed on a controlled object supported by a vibration isolating material, detects vibrations, and outputs a vibration signal. a displacement sensor that detects relative displacement between the control target object and the installation surface of the vibration isolating material and outputs a relative displacement signal, and an absolute acceleration obtained by separately calculating the vibration signals. an arithmetic circuit that outputs a signal and/or an absolute velocity signal, and a gain/phase correction circuit that receives a signal selected from the group consisting of the absolute acceleration signal, absolute velocity signal, and relative displacement signal and corrects its gain/phase. and an actuator that is driven by a signal from the gain/phase correction circuit and injects a control force into the object to be controlled.

[Embodiments] Hereinafter, embodiments to which the active vibration isolating device of the present invention is applied will be described with reference to the drawings.

In FIG. 1, this active vibration isolator has a vibration isolating material 11 on an installation surface 10, which is a foundation or a floor.
A vibration isolation target table or controlled object 12 supported by a vibration isolator is provided.

As the vibration isolating material 11, for example, an air spring, a spring,
Anti-vibration rubber, anti-vibration pads, etc. are used.

This active vibration isolation device includes a vibration sensor 13 that is installed on a controlled object 12 and detects vibration and outputs a vibration signal.
and a displacement sensor 13 that detects the relative displacement between the controlled object 12 and the installation surface 10 of the vibration isolator 11 and outputs a relative displacement signal.
a, an actuator 14 that is driven by the vibration signal detected by the vibration sensor 13 and the relative displacement signal detected by the displacement sensor 13a, and injects a control force into the controlled object 12.
It is equipped with

As this vibration sensor 13, for example, an acceleration sensor or a speed sensor can be adopted.

As the displacement sensor 13a, for example, an eddy current element, a differential transformer, an LED, a laser element, etc. can be employed.

Examples of the actuator 14 include a servo valve and a pneumatic cylinder, an electric/pneumatic proportional valve and a pneumatic cylinder, and a VCM.
(voice coil motor), LDM (linear drive motor), laminated piezoelectric element, giant magnetostrictive material, etc. are suitable.

Note that the controlled object 12 includes not only a vibration-isolated table such as a surface plate but also precision equipment such as a stepper mounted on a vibration-isolated table, and in this case, a vibration sensor 13 may be installed in such precision equipment itself. Furthermore, since the displacement sensor 13a detects the relative displacement between the controlled object 12 and the installation surface 10 of the vibration isolator 11 and outputs a relative displacement signal, it can be installed on the vibration isolator 11, for example. good.

In addition, this active vibration isolator includes a vibration sensor 13.
arithmetic circuits 15 and 16 that output absolute acceleration signals and absolute speed signals obtained by separating and calculating the vibration signals detected in , and these absolute acceleration signals, absolute speed signals, and relative displacement from the displacement sensor 13a. Gain and phase correction circuits ASB and C correct the gain and phase of a signal selected from a group of signals manually, and the signals from gain and phase correction circuits A, B and C are added and injected into the actuator 14. It is equipped with an adder 18. These gain/phase correction circuits ASBSC have different gains G 1 (S), c 2 (S),
It has G a (S).

In the illustrated example, the vibration sensor 13 is connected to gain/phase correction circuits A and B via arithmetic circuits 15 and 16 via a preamplifier Amp attached to the sensor or installed near the sensor, and The sensor 13a is connected to a gain/phase correction circuit C. Gain/phase correction circuit A,
The adder 18 that adds the signals from B and C is an inverting circuit 19
and is connected to the actuator 14 via a drive circuit 20.

In the active vibration isolation device configured as described above, the vibration of the controlled object 12 is detected by the vibration sensor 13 installed on the controlled object 12 supported by the vibration isolating material 11 on the installation surface 10, which is a foundation or floor. Detected. This detected vibration signal is amplified by a preamplifier Amp. These amplified vibration signals are separated and calculated by calculation circuits 15 and 16, respectively, and outputs of an absolute acceleration signal, an absolute velocity signal, and an absolute displacement signal are obtained.

On the other hand, the displacement sensor 13a installed on the vibration isolator 11 detects the relative displacement between the controlled object 12 and the installation surface 10 of the vibration isolator 11, and outputs a relative displacement signal.

This absolute velocity signal is obtained by integrating the absolute acceleration once when an acceleration sensor is used as the vibration sensor 13.

The outputs of the obtained absolute acceleration signal, absolute velocity signal, and relative displacement signal have different gains G1(S) and G2(
A gain/phase correction circuit A having S), G3(S)
The signals are input to SB and C, and their gains and phases are respectively corrected.

Signals from gain/phase correction circuits A, B, and C are sent to adder 1
8 and are added and synthesized. This combined signal is inverted by an inverting circuit 19 and input to a driving circuit 20. The phase of the drive circuit 20 is 0° flat. This drive circuit 2
The drive signal from 0 is injected into the actuator 14, and the actuator 14 is driven. The movement of the actuator 14 is in a direction to suppress vibration of the controlled object 12,
This reduces the vibration of the controlled object 12.

In this case, gain/phase correction circuits A and B are usually used.

Since the C1 drive circuit 20 and the like are housed as a controller in the rack of the vibration isolating device, in order to improve the S/N ratio, the signal input to this controller must be large enough to achieve this. In order to improve this S/N ratio, the preamplifier Amp is preferably attached to the vibration sensor 13 or installed near the sensor 13 as described above.

The active vibration isolation device described above can be schematically represented by a model as shown in FIG. 2, and its equation of motion is expressed by the following equation using the Laplace operator.

MS2X=K (U-X)-F =K (U-X)-G1(S)S2x -G2(S)SX+G, (S)(U-X) However, in the Kono formula, M, S, X, KSU , F are as follows.

M: Mass of the controlled object 12 S Nira plus operator (S = d/d t) : Control force of actitiator 14 Therefore, ((M+G+ (S)S2+G2 (S)S+ (K+
G3(S)))X= (K+G3 (S))UK+G3
(s) Natural frequency ω. The vibration damping coefficient ratio ζ is expressed as follows.

Here, X/U, that is, the transfer function H(S), is given by S=jω.・Gain G related to the relative displacement signal of the phase correction circuit C
As a(S) increases, the natural frequency ω increases. becomes higher, which means that the spring of the vibration affixing material 11 appears to be harder.

Furthermore, if the gain Gl(S) related to the absolute acceleration signal of the gain/phase correction circuit A and the gain Ga(S) related to the relative displacement signal of the gain/phase correction circuit C become smaller, or the absolute When the gain G 2 (S) related to the speed signal increases, the vibration damping coefficient ratio ζ increases, which means that the resonance magnification of the natural frequency becomes extremely small.

Also, these equations are used to calculate the gains G l (S), G2 (S
), G3(S), thus the magnitude and phase of the transfer function H(S), and therefore H(jω), can be adjusted by changing the natural frequency ω7 and the vibration damping coefficient ratio ζ, and the vibration isolation effect can be adjusted. This shows that it is possible to change.

In this way, the feedback gain G, (S),
The natural frequency ω is controlled by controlling G2(S) and G3(S). and the vibration damping coefficient ratio ζ can be set arbitrarily.

Therefore, it is possible to configure an active vibration isolator that can significantly improve vibration isolation performance by using a relative displacement signal instead of an absolute displacement signal.

When the frequency characteristics of the transfer function were measured using the active vibration isolator of the present invention shown in FIG. 1, the results shown in FIG. 4 were obtained. From this frequency characteristic, the active vibration isolator of the present invention has a lower frequency characteristic than the graph of FIG. 3 showing the transfer function frequency characteristic of the conventional passive vibration isolator.
It can be seen that the vibration isolation performance has been significantly improved.

In addition, the object 1 to be controlled by this active vibration isolator
5(a) and 5(b) respectively show the vibration acceleration waveforms at the installation surface 10 of the vibration isolating material.

As is clear from this, it can be seen that the controlled object 12 is largely vibration-insulated from the installation surface 10 of the vibration isolating material.

In the above example, three signals, an absolute acceleration signal, an absolute velocity signal, and a relative displacement signal, were used as feedback control signals. Control can also be performed using one or two selected signals.

Further, in the above example, since relative displacement feedback is performed, it is also possible to control 12 levels (heights) of the object to be controlled.

Furthermore, although the above example describes the case of isolating vibrations in the vertical direction, this vibration isolation can equally be applied to a device that isolates vibrations in the horizontal direction.

[Effects of the Invention] As is clear from the above description, the active vibration isolation device of the present invention is installed on a controlled object supported by a vibration isolating material, detects vibration, and outputs a vibration signal. A vibration sensor, a displacement sensor that detects the relative displacement between the controlled object and the installation surface of the vibration isolator and outputs a relative displacement signal, and an absolute acceleration signal and/or obtained by separately calculating the vibration signals. an arithmetic circuit that outputs an absolute velocity signal, a Kane/phase correction circuit that receives a signal selected from the group consisting of an absolute acceleration signal, an absolute velocity signal, and a relative displacement signal and corrects its gain/phase; By including an actuator that is driven by a signal from a correction circuit and injects control force into the controlled object, the natural frequency and damping can be set arbitrarily using a relative displacement signal instead of an absolute displacement signal, and vibration isolation performance can be improved. can be significantly increased.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of the active vibration isolator of the present invention, Fig. 2 is an explanatory diagram showing a model of the vibration isolator of Fig. 1, and Fig. 3 is a diagram showing the transfer function frequency characteristics of the conventional passive vibration isolator. Graph, Figure 4 is a graph showing the transfer function frequency characteristics of the active vibration isolator of Figure 1, Figure 5(a)
, (b) are graphs showing vibration acceleration waveforms on the installation surface of the object to be controlled and the vibration isolating material by the active vibration isolator of FIG. 1. 12... Controlled object 13... Vibration sensor 13a... Displacement sensor 16.17... Arithmetic circuit A... Absolute acceleration signal gain・Phase correction circuit B: Absolute speed signal gain ・Phase correction circuit C: Relative displacement signal gain/phase correction circuit 14: Actuator 18: Addition vessel

Claims (1)

[Claims] A vibration sensor installed on a controlled object supported by a vibration isolating material to detect vibration and output a vibration signal, and a vibration sensor that detects relative displacement between the controlled object and the installation surface of the vibration isolating material to detect relative displacement. a displacement sensor that outputs a signal; an arithmetic circuit that outputs an absolute acceleration signal and/or an absolute speed signal obtained by separately calculating the vibration signals; a gain/phase correction circuit that receives a signal selected from the group consisting of: a gain/phase correction circuit that corrects the gain/phase; and an actuator that is driven by the signal from the gain/phase correction circuit and injects a control force into the controlled object. An active vibration isolator comprising: