JPH02159439A - Vibration suppression method - Google Patents

Abstract

PURPOSE:To secure antiphase relation between the vibration of a foundation and the output of an actuator by transporting the vibration wave form of a foundation to a step wave form by an wave form transformercircuit, driving the actuator with an antiphase signal to which the step wave form is transported by an antiphase amplifier circuit, and applying the output to the vibration suppression bench on the foundation. CONSTITUTION:When vibration data of a foundation 2 detected by a sensor 4 are single frequency only and their wave form at an output point P1 are sine wave as V1, and a sine wave as V2 is given at an output point P2 of a vibrometer 5, the wave form V2 is transformed into a step wave form S1 at an output point P3 by an wave form transformer circuit 6 and the wave form at the output point P4 is transformed into the antiphase of the step wave form S2 by an antiphase amplifier circuit 7. When the wave form S2 is applied to an actuator 8, braking force F opposite in phase substantially and correctly to the vibration wave form V1 of the foundation 2 is generated. Also, braking force F opposite in phase substantially and correctly can be obtained by using the above method for transforming to the step wave form for various vibrations with different frequencies.

Description

Detailed Description of the Invention - No. 1 The present invention relates to a method of suppressing vibrations, particularly on a floor or stand (hereinafter referred to as a vibration suppressing stand) on which equipment for ultra-high precision machining on the order of microns or submicrons is installed in VLSI manufacturing factories and other places. ) and other vibration suppression methods for the purpose of preventing vibration disturbances. According to the vibration suppression method of the present invention, ultra-fine vibrations are detected by detecting the vibrations of the foundation that supports the vibration damping table, and applying braking force corresponding to the vibration to the vibration damping table in real time to actively cancel the vibrations. Can create a small vibration environment.

Referring to FIG. 1, a vibration damping table 1 used for installing precision equipment, etc. is mounted on a foundation 2 by a support member 3 made of a spring material, a rubber material, or the like. The foundation 2 may be a floor structure of a building. The vibration of the foundation 2 is detected by the sensor 4 and the vibration meter 5, and a control signal having a phase opposite to the output of the vibration meter 5 is generated by an appropriate control device (not shown), and the control signal is used to drive an actuator 8 such as a linear motor. There is a known vibration suppression method that prevents the vibration damping table 1 from vibrating even when vibration occurs in the foundation 2 by driving the vibration damping table 1 and applying a braking force F to the vibration damping table 1 to cancel out the foundation vibration. There is. Here"
"Opposite phase" refers to equal magnitude and opposite direction or polarity, and corresponds to a phase difference of 180 degrees in a sine wave.

However, the actuator 8 is connected to the movable piece 1 by the coil 9.
0, and the current flowing through the coil 9 has a phase difference between it and the control signal due to the inductance L inherent in the coil 9. Even if the control signal is in opposite phase to the vibration of the foundation 2. However, a phase difference occurs between the braking force F, which is in phase with the coil's flow, and the control signal. For this reason, the conventional vibration suppression method has a problem in that it is difficult to generate a braking force F that is in opposite phase to the fundamental vibration and cancels it.

This problem can be solved by using an actuator without inductance L, but the actuator element 1, which produces displacement without time delay in response to changes in input voltage. For example, the piezoelectric material is large enough to cancel the vibration of the base 2 mentioned above. It is not suitable for suppressing the vibration of the vibration damping table 1 because it cannot give a displacement of .

Therefore, an object of the present invention is to provide a vibration suppression method that ensures an antiphase relationship between the vibration of the foundation and the output of the actuator.

. Referring to the embodiment shown in FIG. 1, the vibration suppression method of the present invention converts the vibration waveform of the foundation 2 into a stepped waveform in the waveform conversion circuit 6, and converts the waveform of the foundation vibration into a pulsed waveform. The actuator 8 is driven by a signal whose phase is reversed in the reverse phase amplifier circuit 7, and the braking force F, which is the output of the actuator 8, is applied to the damping table on the foundation 2. 1
A configuration in addition to the supported body is used.

January First, I will explain the reason for converting the basic vibration waveform into a step-like waveform. The vibration of the foundation 2 detected by the sensor 4 and the vibration meter 5 in FIG. 1 consists of only a single frequency f, V. sin
(2πft).

In this case, an input signal S = -3osin (2πft) with a phase opposite to that of the vibration of the foundation 2 is applied to the actuator 8, and a braking force F = -Vosin (2πf
t) is generated and applied to a supported object such as the vibration damping table 1, the vibration of the supported object can be suppressed. However, an actual actuator has an inductance L, and its apparent impedance is Z=R+j 2πfL, so a phase lag occurs in the actuator current with respect to the input signal. Here, R is the apparent resistance of the actuator. Therefore, the actuator output is F = -Vo
sin(2πft-θ), and a phase difference of Q=jan-(2πfL/R) occurs between the vibration and the fundamental vibration, making it impossible to effectively suppress vibration.

In order to prevent the above-mentioned phase delay in the braking force F that is the output of the actuator 8, it is conceivable to adjust the phase of the input signal S in advance. However, the vibration of the foundation 2 due to actual earthquakes does not consist of a single frequency but a complex waveform, and it is currently impossible to predict the frequency distribution, so the magnitude of the phase adjustment that should be done in advance is It is difficult to calculate the

The present inventors made the input signal S of the actuator 8 a discontinuous step-like waveform, and by making the current of the actuator 8 a collection of pulse currents with a transient rise, the phase in the steady current We succeeded in eliminating the delay. Although there is a delay due to the inductance L of the actuator in the transient rise of the current, it has been experimentally confirmed that this delay does not pose a practical problem.

That is, the vibration of the foundation 2 detected by the sensor 4 has only a single frequency, and the waveform at the output point p1 is a sine waveform like vl shown in FIG. When a sinusoidal waveform such as v2 in FIG. 5 is given, the waveform conversion circuit 6 converts the waveform v2 into the stepped waveform S1 in FIG. 5 at its output point p3 (FIG. 1). Furthermore, when the waveform at the output point p4 is made to have an inverse phase as shown in the stepped waveform S2 in FIG. 6 by the inverse phase amplifier circuit 7, and this is applied to the actuator 8,
It was possible to generate the braking force F shown in FIG. 6, which is substantially exactly in opposite phase to the vibration waveform v1 of the foundation 2.

In addition, the present inventors have experimentally demonstrated that the braking force F, which is substantially exactly in opposite phase, can be obtained by using the step-like waveform conversion method for various vibrations with different frequencies. confirmed.

Thus, the object of the present invention has been achieved, namely to provide a vibration suppression method that ensures an anti-phase relationship between the vibration of the foundation and the output of the actuator.

Mitate 1 Fig. 2 is a plan view of an embodiment in which the vibration suppressing device of Fig. 1 according to the method of the present invention is provided in three axial directions of orthogonal coordinate axes x, y, and z, and Fig. 3 is an elevational view thereof. be. A sensor (not shown) similar to sensor 4 in FIG. 1 mounted on foundation 2 and wall 11
Vibration in the three axial directions of X, y, and Z is detected and the output is applied to the three axial vibration meters 5x, 5y, and 5z, respectively. The output of the X-axis vibration meter 5x is processed by a waveform conversion circuit 6 (not shown) and an anti-phase amplifier circuit 7 (not shown) similar to those shown in FIG. Added.

X direction actuator M! However, the X-axis vibration meter is 5! It is based on the principle of the present invention explained above with reference to FIG. 1 that a braking force that is substantially in opposite phase to the output of it is obvious. Similarly, the y-direction actuator My and the two-direction actuator Mz are connected to the X-direction vibration meter 5! A braking force that is substantially in opposite phase to the output of the x-axis vibration meter 52 is generated and applied to the vibration damping table 1 to suppress vibrations in the x-axis direction and the x-axis direction, respectively.

Therefore, the embodiments shown in FIGS. 2 and 3 detect vibrations acting on a supported object such as the vibration damping table 1 by decomposing them into components in the three axial directions of x, y, and z, and The vibration suppression effect is performed independently in each of the three axial directions. The effects in the three axes are combined, so if we consider the direction of increase and decrease in each axis, we get 6
Vibration suppression or vibration control can be performed with a degree of freedom.

As explained in detail above, the vibration suppression method according to the present invention converts the vibration waveform of the foundation into a step-like waveform, and converts the vibration waveform of the foundation into a step-like waveform using an actuator driven by a signal with an opposite phase of the step-like waveform. Since a structure in which a braking force is applied to the upper supported body is used, the following effects are achieved.

(a) Vibration can be suppressed by applying a braking force with a waveform substantially in opposite phase to the vibration waveform detected by the sensor to the supported body.

(b) It is possible to detect vibrations by decomposing them into components in the directions of the three coordinate axes of x, y, and z, and easily realize vibration suppression with six degrees of freedom in consideration of the direction of increase/decrease in each axis direction.

[Brief explanation of the drawing]

FIG. 1 is a detailed explanatory diagram of the present invention, FIGS. 2 and 3 are a plan view and an elevation view of an embodiment of the present invention, and FIGS. 4 to 6 are waveforms of various signals and braking force. This is a graph showing. 1... Vibration control table, 2... Foundation, 3... Support member, 4... Sensor, 5... Vibration meter,
6... Waveform conversion circuit, 7... Anti-phase amplifier circuit,
8...Actuator, 9...Coil,
10... Movable piece, 11... Wall, F... Braking force,
Sl...step waveform, S2...actuator input waveform, Vl...sensor output, v2...vibration meter output.

Claims (1)

[Claims] A vibration suppression method comprising converting the vibration waveform of the foundation into a stepped waveform and applying a braking force to the supported body on the foundation using an actuator driven by a signal with the stepped waveform having an opposite phase.