JPH05281983A - Vibration reduction device - Google Patents

Abstract

PURPOSE:To reduce periodic vibration by simple constitution which eliminates the need to directly detect the vibration of a vibration source as to the vibration reducing device which reduces the vibration by generating inverse vibration for the vibration to be reduced. CONSTITUTION:This vibration reducing device is provided with a speaker 18 which generates a canceling sound for a noise d(k) at a specific position, a predicting means 22 which predicts a canceling sound z(k) at the specific position due to the canceling sound generated by the speaker 18, a microphone 14 which detects the sound at the specific position, and a control means 24 which generates a control signal y(k) for driving the speaker 18 according to the difference x(k) between the sound e(k) detected by the microphone 14 and a canceling sound y'(k) predicted by the predicting means 22.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vibration reducing device for reducing a vibration by generating a reverse vibration for canceling the vibration to be reduced and superposing the reverse vibration on the vibration to be reduced, and particularly to a cycle The present invention relates to a vibration reduction device for reducing vibration.

[0002]

2. Description of the Related Art Conventionally, noise (air vibration) such as engine noise, exhaust noise, wind noise, etc., in the interior of an automobile, for example.
And vibration of the car body due to engine vibration, road surface vibration, etc.
The demand for reducing unpleasant or disturbing vibrations is in various fields.

In recent years, a so-called positive vibration reduction measure has been attracting attention in order to reduce the vibration by generating a reverse vibration for canceling the vibration to be reduced and superposing it on the vibration to be reduced.

As a conventional technique relating to such a positive anti-vibration measure, a vibration reducing device disclosed in Japanese Patent Publication No. 1-501344 is known. FIG. 5 is a control block diagram for explaining the vibration reducing device according to this conventional technique. Figure 5
As shown in FIG. 1, the vibration reduction device described in the above publication includes a vibration detection unit (microphone) 2 that detects vibration in a predetermined region, and a reverse vibration generation unit (microphone) that generates reverse vibration for reducing vibration in the predetermined region ( Speaker) 4,
Control signal y (k) for driving the reverse vibration generating means 4
(K is a parameter representing the sampling time. The same applies hereinafter).

The control signal y (k) is a vibration source (engine).
8 (or information from which vibration information of the vibration source 8 is obtained) is directly detected, and the reference signal r (k) generated based on this detection signal is used as an adaptive filter <f> in the control means 6.
(Note that in the present specification, when a vector is represented,
<> Is attached to the code. ) Is generated by passing it through. The control signal y (k) drives the reverse vibration generating means 4 to generate the reverse vibration z (k) for the vibration d (k) to be reduced which is transmitted from the vibration source 8 to the predetermined portion, whereby the vibration is generated. Overlaid on d (k).

The combined vibration of the vibration d (k) transmitted from the vibration source 8 and the vibration z (k) transmitted from the inverse vibration generating means 4 is detected by the vibration detecting means 2, and this is detected by the error signal e (k ) Is input to the control means 6. Then, the coefficient of the adaptive filter <f> is adjusted every moment so that the error signal is minimized, whereby the vibration is reduced.

As described above, the conventional vibration reduction device directly detects the vibration of the vibration source 8 to generate the reference signal r (k), and transmits the reference signal r (k) from the vibration source 8 based on the reference signal r (k). Inverse vibration z with respect to vibration d (k)
The system has a feedforward control system that generates (k).

As the adaptive algorithm for adjusting the coefficient of the adaptive filter <f>, there are LMS method (Least Mean Square Method) and simplex (Simpl).
ex) method, Powell method, etc. are known, and the one shown in FIG. 5 is based on the LMS method. In the LMS method, in order to adjust the coefficient of the adaptive filter <f> in consideration of the transfer function <h> between the inverse vibration generating means 4 and the vibration detecting means 2, the transfer function <h> is adjusted by the filter 10 The transfer function model <h °> modeled by is used, and the spatial distance between the inverse vibration generating means 4 and the vibration detecting means 2 is, as it were, interpolated.

Further, in FIG. 5, the number of adaptive filters, the inverse vibration generating means 4 and the vibration detecting means 2 are shown for convenience of explanation.
Although the number of each of these and the like is one, in reality, a plurality of these are often provided. Further, in FIG. 5, the transfer characteristic between the vibration source 8 and the vibration detection means 2 is represented by a transfer function.
Shown as <g>.

[0010]

As described above, in the conventional vibration reducing apparatus, the reference signal generated by directly detecting the vibration of the vibration source is used to generate the reverse vibration. However, in order to generate the reference signal, a dedicated sensor for directly detecting the vibration of the vibration source, a circuit for shaping the waveform of the detected signal, and the like are required, so the configuration of the device becomes complicated, In addition, the cost becomes high.

Further, in the conventional vibration reducing device, the reverse vibration for canceling the vibration transmitted from the vibration source to the predetermined portion is generated based on the reference signal generated by directly detecting the vibration of the vibration source. In order to sufficiently obtain the vibration reducing effect in the predetermined portion, it is necessary that there is a high correlation between the reference signal and the vibration to be reduced in the predetermined portion. However, the vibration generated from the vibration source may be saturated during the transmission to the above-mentioned predetermined site, and unnecessary components may be mixed in the vibration, or different vibrations may be mixed from other vibration sources. However, it is often subjected to nonlinear deformation, and thus it becomes difficult to obtain a high correlation between the reference signal and the vibration to be reduced. If a reference signal having such a high correlation cannot be generated, there is a problem that the conventional vibration reducing device cannot obtain a sufficient vibration reducing effect.

In view of the above problems, it is an object of the present invention to provide a vibration reducing device that can obtain a sufficient vibration reducing effect with a simple structure that does not need to directly detect the vibration of a vibration source and generate a reference signal. It is what

[0013]

In order to solve the above-mentioned problems, a vibration reducing device according to the present invention is a vibration reducing device for reducing periodic vibration, and generates reverse vibration for reducing vibration at a predetermined portion. Reverse vibration generating means, predicting means for predicting vibration in the predetermined part due to reverse vibration generated by the reverse vibration generating means, vibration detecting means for detecting vibration in the predetermined part, and detection by the vibration detecting means Control means for generating control vibration for driving the reverse vibration generating means based on a difference between the vibration in the predetermined portion and the vibration in the predetermined portion predicted by the predicting means. It is what

[0014]

The operation and effect of the vibration reducing device according to the present invention is as follows.
The reverse vibration for reducing the vibration at the predetermined portion is generated by the reverse vibration generating means, while the vibration at the predetermined portion caused by the reverse vibration generated by the reverse vibration generating means is predicted by the predicting means, and the predetermined portion is also generated. The vibration in the above is detected by the detecting means, and the control means generates the control signal for driving the reverse vibration generating means based on the difference between the vibration detected by the detecting means and the vibration predicted by the predicting means. By doing so, the periodic vibration in the predetermined portion is reduced.

Vibrations to be reduced at a predetermined portion, such as vibrations caused by driving an automobile engine, are often periodic vibrations having periodicity. Therefore, it can be said that if the periodic vibration in the predetermined portion is reduced, even if the non-periodic vibration remains, the vibration reducing effect is high.

In order to reduce the periodic vibration in the predetermined portion, it is sufficient to superimpose the periodic vibration on the periodic vibration in a phase opposite to the periodic vibration. By the way, since the vibration of each cycle of the periodic vibration has a very strong correlation, the reverse vibration having the antiphase relationship with the vibration of the certain cycle of the periodic vibration has a cycle delay that is out of phase with the above cycle. This can be canceled by superimposing it on the vibration.

That is, if a reverse vibration that cancels this vibration is generated on the basis of the vibration of a certain cycle of the periodic vibration actually detected by the vibration detecting means at a predetermined portion, this reverse vibration is a vibration delayed by the cycle of the periodic vibration. It is possible to cancel the vibration delayed by the cycle, and by repeating this operation, it is possible to cancel the cyclic vibration at the predetermined portion. However, since the vibration detecting means detects the combined vibration of the periodic vibration desired to be reduced at the predetermined portion and the reverse vibration from the reverse vibration generating means, in order to generate the next reverse vibration. Must remove the reverse vibration from the reverse vibration generating means from the detected combined vibration.

Therefore, in the vibration reducing apparatus according to the present invention, a predicting means for predicting the vibration at a predetermined portion due to the reverse vibration generated by the reverse vibration generating means is provided, and the vibration detecting means detects the vibration predicted by the predicting means. I try to exclude it from vibration. By doing so, the vibration reduction device according to the present invention has a system configuration based on feedback control in which reverse vibration is generated based on vibration actually detected at a predetermined portion.

As described above, according to the vibration reducing apparatus of the present invention, it is not necessary to directly detect the vibration of the vibration source to generate the reference signal as in the prior art. Therefore, the structure is simplified and the cost is reduced. Can be achieved. Further, without using the reference signal, reverse vibration is generated based on the periodic vibration actually detected by the vibration detecting means, and the vibration is canceled by superimposing this on the vibration with the highly delayed cycle delay, so it is effective. Periodic vibrations can be reduced, and a sufficient vibration reduction effect can be achieved.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of a vibration reducing device according to the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a schematic view of a vibration reducing device according to an embodiment of the present invention.

The vibration reducing apparatus according to the present embodiment shown in the drawing is
Among the vibrations in the interior of an automobile, the object is to reduce annoying periodic air vibrations, that is, periodic noises, which are felt at a position where an occupant is seated. As shown in FIG. 1, this vibration reduction device includes a plurality of microphones 14 as vibration detection means attached to the position of the headrest 12 of each seat, and a detection made by converting noise detected by each microphone 14. Controller that receives signal 16
And the headrest driven by the controller 16
It is provided with a plurality of capers 18 as a reverse vibration generating means for generating a sound for reducing noise at 12 positions.

The microphones 14 are arranged at positions substantially corresponding to the positions of both ears of each occupant, so that a detection signal corresponding to the sound actually heard by each occupant is input to the controller 16. Will be done. Further, each of the speakers 18 is a general audio speaker that converts a sound signal from a CD, a magnetic tape, a tuner, or the like into a sound and outputs the sound. Such a sound and a noise canceling sound are simultaneously or, Only one is output.

Further, a switch 19 is provided near the instrument panel in the driver's seat for appropriately turning on / off the device or switching the type of noise to be canceled by the occupant.

This device outputs a canceling sound for canceling the cyclic noise from the speaker 18 based on the cyclic noise actually detected by the microphone 14, and superimposes the canceling sound on the noise delayed by the cycle of the periodic noise. It is intended to reduce the periodic noise, and the noise reduction control is executed by the control system shown in FIG.

FIG. 2 is a control block diagram schematically showing the configuration of the control system of the vibration reducing apparatus according to this embodiment.

As shown in FIG. 2, in the microphone 14, a canceling sound z (k) at the position of the microphone 14 caused by the canceling sound output from the speaker 18 (k is a parameter representing the sample time. The same applies hereinafter). Vibration sources such as engine
A synthesized sound with the noise d (k) transmitted from 20 to the position of the microphone 14 is detected, and the synthesized sound is input to the controller 16 by the microphone 14 as an error signal e (k) every moment. That is, the error signal e (k) can be expressed as e (k) = d (k) + z (k) (1).

Further, the speaker 18 is driven by a control signal <y> (k) output from the controller 16 (note that when a vector is represented in the present specification, a symbol <> is attached). .. Therefore, the cancellation sound z (k)
This control signal <y> (k), speaker 18, microphone
By convolving the transfer function between 14 and <h>, it can be expressed as the following equation.

Z (k) = <y> (k) * <h> (2) where <y> (k) is the accumulated past data for each sampling period from time k, and > (k) = [y (k), y (k-1), y (k-2), ...].

On the other hand, the controller 16 controls the control signal <y
The filter 22 is provided as a prediction means for predicting the cancellation sound z (k) based on> (k). The filter 22 has a transfer function model <h °> that models the transfer function <h> between the speaker 18 and the microphone 14, and the control signal <y>
By passing (k) through the filter 22, the predicted signal y ′ (k) of the canceling sound z (k) is obtained.
That is, the predicted signal y ′ (k) can be expressed by the following equation by convolving the control signal <y> (k) and the transfer function model <h °>.

[0031]

[Equation 1]

Further, the controller 16 controls the error signal
The control means 24 is provided for generating the control signal <y> (k) based on the difference between e (k) and the predicted signal y ′ (k). That is, the control signal <y> (k) is the error signal e (k) and the prediction signal y ′.
The basic signal x (k) (= e (k) −y ′) obtained by the difference with (k)
(k)) is obtained by passing the adaptive filter <f> included in the control means 24. And this adaptive filter <f
The coefficient of> is adjusted every moment so that the error signal e (k) is minimized, whereby noise at the position of the microphone 14 is reduced.

That is, the above transfer function model <h °> is
Since the transfer function <h> between the speaker 18 and the microphone 14 is modeled,

[0034]

[Equation 2]

And therefore,

[0036]

[Equation 3]

[0037] From these relationships, the above is the basic signal
x (k) is

[0038]

[Equation 4]

It becomes

Here, d (k) is a periodic noise, and if its period is T,

[0041]

[Equation 5]

Since the basic signal x (k) is adaptively signal-processed to adjust the canceling sound z (k), the canceling sound is delayed by a noise d (K-nT) which is a periodic delay of the periodic noise. The error signal e (k) → 0 can be changed by superimposing it on the above, and thus the periodic noise can be reduced.

In FIG. 2, the transfer characteristic between the vibration source 20 and the microphone 14 is shown as a transfer function <g>.

In the present embodiment, the adaptive algorithm for adjusting the coefficient of the adaptive filter <f> is used.
Although the LMS method is used as 26, the simplex method or the Poel method may be used instead. Further, there may be a plurality of vibration sources instead of one.

As described above, according to the vibration reducing apparatus of this embodiment, since it is not necessary to directly detect the vibration of the vibration source, the structure is simplified and the cost can be reduced. Further, since a canceling sound is directly generated based on the periodic vibration detected by the microphone 14, and the canceling sound is canceled by superimposing the noise with a period delay having a high correlation,
The periodic noise can be effectively reduced.

Although one embodiment of the vibration reducing apparatus according to the present invention has been described above, the vibration reducing apparatus according to the present invention is not limited to this mode, and various modifications can be made.

For example, in the above-mentioned embodiment, in order to reduce the periodic noise in the interior of the automobile, the speaker produces a canceling noise. However, the periodic noise to be reduced is generated by a certain solid (for example, a vehicle body of an engine). When it is caused by the periodic vibration of the mount portion), it is also possible to reduce the periodic noise by directly reducing the periodic vibration.

An outline of such a vibration reducing device is shown in FIG. FIG. 3 is a schematic view of a vibration reducing device according to another embodiment of the present invention.

The vibration reducing apparatus according to the present embodiment shown in FIG. 3 is different from the apparatus according to the above-described embodiment in that the reverse vibration generating means for generating the reverse vibration for reducing the periodic noise generated from the engine E is a speaker. Rather, the actuator 30 is attached to the mount portion M of the engine E on the body frame 28. That is, in this device,
A detection signal of the periodic noise detected by each microphone 14 provided in the vehicle compartment is input to the controller 16, and the controller 16 mounts the engine E that causes the periodic noise at the position of the microphone 14 based on the input signal. In order to cancel the periodic vibration of the body frame 28 in the portion M, its inverse vibration is generated by the actuator 30, and this inverse vibration is superimposed on the oscillation of the synchronous vibration which is delayed by the period, thereby reducing the periodic noise in the vehicle interior. Is planned. Note that the configuration of the controller 16 is the same as that of the above-described embodiment, and the description will be omitted.

Further, the vibration reducing device according to the present invention can be applied not only for reducing the periodic noise in the vehicle interior but also for reducing the periodic vibration itself of the vehicle body. An outline of such a vibration reduction device is shown in FIG. FIG. 4 is a schematic view of a vibration reducing device according to another embodiment of the present invention.

In the vibration reducing device according to this embodiment shown in FIG. 4, the vibration detecting means is not the microphone 14,
Since the acceleration sensor 32 is provided in the vicinity of the mount portion M of the engine E on the body frame 28, the acceleration sensor 32 is different from the previous embodiment, and other configurations are basically the same.
Detailed description thereof will be omitted.

It is needless to say that the vibration reducing device according to the present invention is applicable not only to the reduction of the periodic vibration in the automobile but also to the reduction of the periodic vibration in other various fields.

[Brief description of drawings]

FIG. 1 is a diagram showing an outline of a vibration reduction device according to an embodiment of the present invention.

FIG. 2 is a control block diagram schematically showing a configuration of a control system of the vibration reduction device.

FIG. 3 is a diagram schematically showing a vibration reducing device according to another embodiment of the present invention.

FIG. 4 is a schematic view of a vibration reducing device according to another embodiment of the present invention.

FIG. 5 is a control block diagram for explaining a vibration reduction device according to a conventional technique.

[Explanation of symbols]

 2,14 Microphone (vibration detection means) 4,18 Speaker (reverse vibration generation means) 6,24 Control means 8,20 Vibration source 22 Prediction means y (k) Control signal r (k) Reference signal

Claims (1)

[Claims] 1. A vibration reduction device for reducing periodic vibrations, comprising: reverse vibration generating means for generating reverse vibration for reducing vibration at a predetermined portion; and reverse vibration generated by the reverse vibration generating means. Prediction means for predicting vibration in the predetermined part, vibration detection means for detecting vibration in the predetermined part, vibration in the predetermined part detected by the vibration detection means and vibration in the predetermined part predicted by the prediction means And a control unit configured to generate a control vibration for driving the reverse vibration generation unit based on the difference of the above.