JPH03228097A - Vibration controller - Google Patents

Abstract

PURPOSE:To cancel vibration received directly from a vibration source and vibration having inverse waveform by an acoustic radiation body and to reduce the vibration by supplying the vibration received directly from the vibration source and the vibration with the inverse waveform to a vibration actuator by using a digital filter. CONSTITUTION:A microphone 7 is provided closely to a speaker 2 in a sound insulation box 1 and a noise generated by the speaker 2 is detected instantaneously by the microphone 7, whose detection signal is inputted to the digital filter 8 and coefficient update algorithm 9. The noise generated by the speaker 2 reaches a sound insulation plate 5 to generate the vibration generated by the sound insulation plate 5 and the vibration with the inverse waveform forcibly by the vibration actuator 6 through the digital filter 8, and both the vibrations cancel each other to reduce the vibration of the sound insulation plate 5 as an acoustic radiation body, thereby reducing the noise of the microphone 10.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is directed to actively reducing the vibration of an object that is emitting sound due to solid propagation vibration or acoustically excitation vibration. This invention relates to a vibration control device that significantly reduces radiated sound.

11 A conventional technique for actively reducing the vibration of a nail acoustic radiator using a vibrating actuator to achieve sound and vibration isolation is disclosed in Japanese Patent Publication No. 55-29.
There is one described in Publication No. 304.

The method described in the same publication, as shown in FIG.
This prevents the signal from propagating to the third side.

Therefore, a plurality of exciters 05 are attached to the side wall 04, a microphone 06 is provided near the side wall 04 in the factory building 01, and the microphone 06 and each exciter 05 are connected to the controller 0.
It is linked by intervening 7.

The controller 07 applies a forced vibration force to the vibrator 0 that is in an opposite phase to the vibration force applied to the side wall 04 by the sound wave from the vibration wave generation source 02.
5 to the side wall 04 at the same time.

Vibration force from vibration wave generation source 02 on side wall 04 and exciter 0
The side wall 04 is in a state of no vibration or very weak vibration as the forced vibration forces of opposite phases due to the side wall 04 cancel each other out, and the noise is blocked by the side wall 04 and does not reach the house 03 without causing acoustic radiation.

” 1 In the above conventional example, if the sound waves from the vibration wave generation source 02 have periodicity, it is effective to shift the phase by the controller 07 and apply forced vibration of the opposite phase to the side wall 04. vibration can be reduced.

However, if the sound waves from the vibration wave source 02 are close to random vibrations without periodicity, it is difficult to determine the phase itself, and even if forced vibrations are applied by shifting the phase, the vibrations cannot be effectively reduced. I can't.

Actual noise is generally close to random vibration, and conventional systems have limited practical usage conditions.

The present invention has been made in view of the above, and an object of the present invention is to provide a vibration control device that can effectively reduce noise by canceling vibrations with vibration waves of opposite waveforms. At the point.

That is, the present invention provides a vibration source or noise m; a vibration detection means or noise detection means provided in contact with or in close proximity to the vibration source or noise m; a vibration actuator installed on the acoustic radiator; and the vibration detection means or noise detection means. a control means for inputting a detection signal generated by the vibration actuator and outputting a control signal to the vibration actuator, and the control means uses the detection signal from the vibration detection means or the noise detection means to generate a vibration wave opposite to that generated by the acoustic radiator. This vibration control device is a digital filter that forms and outputs a control signal that causes a vibration actuator to generate a wave-shaped vibration wave.

When the digital filter serving as the control means outputs a control signal to the vibrating actuator, the vibrating actuator generates a vibration wave with the opposite waveform to the vibration wave generated by the acoustic radiator, so both vibrations cancel each other out, significantly reducing vibration. soundproofing effect can be obtained.

Since vibrations with a reverse waveform are used, even noise close to random vibration can be effectively reduced.

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention illustrated in FIGS. 1 to 4 will be described below.

This embodiment is an apparatus configured for experimental purposes, and a configuration diagram thereof is shown in FIG.

A speaker 2 serving as a noise source is provided in a sound insulating box 1 having a cubic shape and having a negative side open, close to its bottom wall la.

A signal obtained by amplifying a random vibration wave signal transmitted from a noise generator 3 by a power amplifier 4 is input to the speaker 2 and generates noise.

The opening of the sound insulation box 1 is closed by a sound insulation plate 5, and one vibration actuator 6 is attached to the outer surface of the sound insulation plate 5 at the center.

A piezoelectric or electrodynamic actuator can be used as the vibration actuator 6.

A microphone 7 is provided in the vicinity of the speaker 2 in the sound insulation bonus 1, and the noise generated from the speaker 2 is immediately detected by the microphone 7, and the detection signal is input to a digital filter 8 and a coefficient updating algorithm 9.

Further, a microphone 10 is arranged outside the sound insulation box 1 at a position facing the sound insulation plate 5, and the purpose is to reduce noise at the same position.

This detection signal from the microphone 10 is input to the coefficient updating algorithm 9 and is used for control.

The coefficient update algorithm 9 inputs the signal from the microphone 710 and updates the filter coefficient (
In other words, the characteristics) are constantly updated to optimize them.

The digital filter 8 processes the input signal from the microphone 7 based on the filter coefficients determined by the coefficient update algorithm 9 and outputs a control signal for driving the vibration actuator 6. This control signal is sent to the amplifier 11.
The voltage is amplified to a voltage sufficient to drive the vibration actuator 6 and is applied to the vibration actuator 6.

A multi-channel digital filter is a digital filter with multiple inputs (including single input) and multiple outputs (including single output), and the coefficient update algorithm is designed to minimize the root mean square error of each signal input as an error signal. It functions to update the coefficients so that

[Basically, the digital filter 8 causes the noise generated from the speaker 2 to reach the sound insulation plate 5 and force the vibrating actuator 6 to generate vibrations with a waveform opposite to the vibration generated on the sound insulation plate 5. are canceled out by each other, thereby reducing the vibration of the sound insulating plate 5, which is a sound radiating object, and reducing the noise in the microphone 10.

Since the vibration of the sound insulating plate 5 is reduced by the vibration of the reverse waveform in this way, it is effective not only for periodic vibrations but also for wide-band random vibrations, and the range of application is greatly expanded.

In the case of the conventional soundproofing device, as shown in FIG. 21, the microphone 06 is placed close to the side wall 04, and the vibration waves of the vibration wave generation source 02 are detected near the microphone 06, and the phase of the detected signal is shifted and the vibration exciter is activated. Since the vibration of the side wall 04 is reduced by the system that drives the 05, it is applicable only to the circumference p, )' 1 vibration, and is of no use to the random vibration 22. The system detects the vibration of the microphone 7 near the speaker 2 and applies the vibration of the opposite waveform to the sound insulating plate 5 at an appropriate timing in advance of the vibration wave directly reaching the sound insulating plate 5 from the speaker 2. This effective system, which is different from the conventional one, works effectively against not only periodic vibrations but also all kinds of random vibrations, making it possible to significantly reduce noise.

The experimental results of this example are shown in FIGS. 3 and 4.

FIG. 3 is a graph showing the sound pressure spectrum versus vibration frequency, where the broken line is when the device is not controlled and the solid line is when it is under control.

When not controlled, the sound pressure varies by 50 dB up and down with a width of 10 dB or more, and the maximum sound pressure is 80 dBO near 200 Hz.

On the other hand, when control is performed, the sound pressure changes within a width of about 5 dB or less above and below 50 dB, and the sound pressure clearly decreases.

FIG. 4 shows the output voltage of the microphone 10,
Again, the broken line shows the non-control time, and the solid line shows the control time.

During control, the output voltage has significantly decreased, indicating that the noise at the microphone 10 position has been drastically reduced.

Next, as a second embodiment, instead of the microphone 10, an acceleration pickup 15 is installed on the sound insulating plate 5 as shown in FIG.
It is also possible to provide a configuration in which the output of the acceleration pickup 15 is input to the coefficient updating algorithm 9.

With this configuration as well, the adaptive algorithm worked to minimize plate vibration, and almost the same results as those shown in FIGS. 3 and 4, which are the effects of the invention in the case of the first embodiment, were obtained.

In addition, in the second embodiment, an adaptive digital filter is used, which can effectively reduce vibrations even when there are changes over time in the characteristics of microphones and sound insulating plates. If the change is small enough, it is possible to replace it with a normal time-invariant digital filter.

This eliminates the need for the microphone 10 in Figure 1 and the acceleration pick amplifier 15 in Figure 5.
Furthermore, the digital filter circuit can be small-scale, and the entire system can be simplified.

Furthermore, in the first and second embodiments, one piezoelectric element actuator 6 was attached to the center of the sound insulating plate 5 (see FIG. 2).
The number of vibration actuators 6 is appropriate depending on the purpose of use.
Size, shape and location must be selected.

Next, a third embodiment will be explained based on FIGS. 6 to 11.

This embodiment is an example applied to an automobile 20, and the engine 2
This is intended to reduce the noise of 1 inside the vehicle compartment 22 separated by the dash board 23.

FIG. 6 is a plan view of the automobile 20 (roof and window omitted) showing the arrangement of the vibration control device, and FIG. 7 is a side view of the same.

A piezoelectric acceleration pickup 24 is fixed to the cylinder head of the engine 21, and the acceleration pickup 24 is directly connected to the engine 21.
A piezoelectric acceleration big amplifier 2 is also installed under the spring of each wheel to detect vibrations from the wheels.
5 is fixed.

In the case of an automobile, the entire body is a sound radiator, and the vibration actuator 26 is arranged in the body around the passenger compartment 22.

That is, three vibration actuators 26 are attached to the dance board 23, one to each door panel, one to the roof panel, three to the rear seat hack panel, and one to the rear shelf panel.

In addition, a transparent polymer piezoelectric material 27 is attached to the front, rear, left and right windows 28.
FIG. 8 shows a cross section of the window 28, in which a polymeric piezoelectric material 27 is integrally molded in a layer within the glass of the window 28.

On the other hand, in the vehicle interior 22, microphones 30 are provided in each of the front and rear seats.

The control circuit in this embodiment consists of a multi-channel digital filter 31 and a coefficient update algorithm 32, as shown in FIG. A vibration detection signal is inputted from the acceleration pick 7, 2425, and a drive signal is outputted to each vibration actuator 26 and polymer piezoelectric body 27 via each amplifier 33.

The coefficient update algorithm 32 inputs the signal from the acceleration pink amplifier 24.25 as well as the signal from each microphone 30 of the front, rear, left and right seats as an error signal, calculates the update value of the filter coefficient based on both signals, and sequentially updates the filter coefficient. will be updated.

The multi-channel digital filter 31 performs arithmetic processing according to the successively updated filter coefficients and outputs a drive signal to the vibration actuator 26 and the polymer piezoelectric body 27.

Through such control, optimal vibrations are applied to the vibration actuator 26 and the polymer piezoelectric material 27 disposed at predetermined locations around the vehicle compartment 22, and the solid propagation vibrations and acoustic vibrations directly received from the engine 21 are converted into vibrations of opposite waveforms. This cancels out the vibrations of the body around the vehicle interior 22, and the output voltage of the microphones 30 and 31 decreases.

In other words, it is possible to reduce the noise that reaches the ears of people in the front and rear seats.

10 and 11 show the sound pressure spectrum and the output of the microphone 30 in the right front seat in this embodiment.

In both figures, the broken line is the result when no control is applied, and the solid line is the result when control is applied, and it can be seen that both the amplitude of sound pressure and the output voltage are significantly reduced during control.

Similar to the second embodiment shown in FIG.
A similar noise reduction effect can also be obtained by attaching an acceleration pickup 35 adjacent to each vibration actuator 26 of each panel and inputting these to the coefficient updating algorithm 32 as in the fourth embodiment shown in FIG. It was possible.

In the third and fourth embodiments as well, after the coefficient update algorithm converged and became stable, the noise reduction effect remained unchanged even if the coefficient update was stopped. It is also possible to simplify the system by replacing it with a digital filter.

The above experimental results were almost the same in the case of the rear seat.

Next, a fifth embodiment will be explained based on FIGS. 15 to 17.

The same side is an example of application to a partition wall in a residence.

Two rooms 41 and 42 are defined by a thin panel 40, and a vibration actuator 43 is attached to the panel 40.

A speaker 44 is placed in one room 41 as a source of pseudo-image vibration, and a microphone 45 is placed near it.

In the other room 42, a microphone 46 is installed at a position aimed at reducing noise.

Multi-channel digital filter 4 which is a control circuit
7 and the coefficient update algorithm 48 include the speaker 44
Detection signals from nearby microphones 45 are input, and the coefficient update algorithm 410 further inputs signals from microphones 46 in 42 rooms as error signals.

As in the previous embodiment, the coefficient update algorithm 48 sequentially updates the filter coefficients, and based on the filter coefficients, the multi-channel digital filter 47 outputs a control signal to drive the vibration actuator 43 via the amplifier 49 to vibrate the panel 40. let

Similar to the embodiment described above, the vibrations that the panel 40 receives due to the sound pressure generated by the speakers 44 are suppressed by vibrations having an opposite waveform, thereby reducing noise.

FIGS. 16 and 17 show the sound pressure spectrum and output voltage at the microphone 46, and as in the previous embodiment, both the amplitude of the sound pressure and the output voltage are significantly reduced.

In this fifth embodiment, the same noise reduction effect can be obtained by providing an acceleration pickup 55 fixed to the pallets 2 and 40 instead of the microphone 46 as in the sixth embodiment shown in FIG. It was possible.

Next, a seventh embodiment will be explained based on the 191st embodiment.

The same side is an example in which a vibration actuator 62 is attached to the outer wall 61 of a prefabricated house 60. Inside the house 60, vibrations 863 and 64 such as two motors are arranged, and each vibration source 6364 has a vibration sensor 65. .66 is fixed, and microphones 67 are placed outside the prefabricated house 60 at two positions for the purpose of reducing noise.

This embodiment also uses a multi-channel digital filter 68 and a coefficient update algorithm 69.
Detection signals from the vibration sensors 65 and 66 are branched and input to a multi-channel full digital filter 68 and a coefficient update algorithm 69, and a detection signal from the microphone 67 is input to a coefficient update algorithm 69.

A drive signal is output from the multi-channel digital filter 68 to the vibration actuator 62 via the amplifier 70.

This embodiment is configured as described above, and two vibration #
63.64, the signals detected from both vibrations hq63.64 are respectively subjected to a multi-channel digital filter 68 to minimize the error signal. f
By forming the fD signal and using it as a drive signal for the vibrating actuator 2 via the amplifier 70, vibration of the side wall 61 is suppressed, and the noise in the 22 devices 6 feet is significantly reduced.

In other words, noise reduction can be achieved in a space with a certain degree of expanse.

Also in this seventh embodiment, instead of the output of the microphone 67 input to the coefficient update algorithm 69 as in the eighth embodiment shown in FIG.
It was also possible to obtain a similar noise reduction effect by fixing it to the outer wall 61 and applying the output manually.

Note that even when three or more vibration sources are provided, the same noise reduction effect can be obtained with the same configuration, and a wide range of application can be ensured.

Further, in any of the above embodiments, an electrodynamic inertial mass actuator can be used as the vibration actuator.

The present invention uses a digital filter to apply vibrations with an opposite waveform to the vibrations received directly from the vibration source to an excitation actuator, canceling out both in the acoustic radiator, reducing vibrations, and significantly reducing noise. Therefore, it is possible to deal with not only periodic vibrations but also all kinds of random vibrations, and it is also possible to deal with vibrations regardless of whether they are acoustically excited vibrations or solid-propagated vibrations, so the range of application is extremely wide.

[Brief explanation of drawings]

Fig. 1 is a configuration diagram of a vibration control device according to a first embodiment of the present invention, Fig. 2 is a layout diagram of a vibration actuator of the same embodiment, and Figs. 3 and 4 are experimental results in the same embodiment. , FIG. 5 is a configuration diagram of the vibration control device of the second embodiment, FIGS. 6 and 7 are layout diagrams of the vibration control device of the third embodiment, which is used in automobiles, and FIG. 8 is a diagram showing the configuration of the vibration control device of the third embodiment. FIG. 9 is a block diagram of the control system of the example. FIGS. 10 and 11 are diagrams showing the experimental results of the example. FIGS. 12 and 13 are the fourth example. Fig. 14 is a control system block diagram of the same embodiment, Fig. 15 is a configuration diagram of the vibration control device of the fifth embodiment, and Figs. 16 and 17 are the same. Diagrams showing experimental results in Examples, FIG. 18 is a configuration diagram of a vibration control device of a sixth embodiment, FIG. 19 is a configuration diagram of a vibration control device of a seventh embodiment,
FIG. 20 is a configuration diagram of the vibration control device of the eighth embodiment, and FIG.
The figure is a configuration diagram of a conventional vibration control device. DESCRIPTION OF SYMBOLS 1...Sound isolation box, 2...Speaker, 3...Noise shelter, 4...Power amplifier, 5...Sound isolation plate, 6...Vibration actuator, 7...Microphone, ...Digital filter, 9...Coefficient update algorithm, 10...Microphone, 11...
Amplifier, 15... Acceleration pickup, 20... Car, 21... Engine, 22... Vehicle interior, 23... Danshu board, 24. 25... Acceleration pink up, 26... Acceleration Vibration actuator, 27
...Polymer piezoelectric material, 28...Window, 30...Microphone, 31...Multi chain 2
32... Coefficient update algorithm, 33... Amplifier, 35... Acceleration pickup, 40... Bar ♀, 41.42... Room, 43
... Vibration actuator 44 ... Speaker, 45
．． 46...Microphone, 47...Multi-channel input filter, 48...Coefficient update algorithm, 49...Amplifier, 55...Acceleration pickup, 60...Prefabricated house, 61...Exterior wall , 62...
Vibration actuator, 63.64... Vibration source, 65.
66... Vibration sensor, 67... Microphone, 6
8...Multi-channel digital filter, 69.
...Coefficient update algorithm, 70...Amplifier, 75...Acceleration pickup.

Claims (1)

[Claims] A vibration detecting means or a noise detecting means provided in contact with or close to a vibration source or a noise source, a vibration actuator installed on an acoustic radiator, and a detection signal from the vibration detecting means or noise detecting means are inputted. and a control means for outputting a control signal to the vibration actuator, the control means applying a vibration wave having a waveform opposite to the vibration wave generated by the acoustic radiator using the detection signal from the vibration detection means or the noise detection means. A vibration control device characterized in that it is a digital filter that forms and outputs a control signal that is generated by a vibration actuator.