JPH06138888A - Active vibration controller - Google Patents

Abstract

PURPOSE:To provide an active vibration controller capable of decreasing a vibration noise at an arbitrary position in a vibrating field independently of the installing position of a vibration sensor. CONSTITUTION:A reference signal (x) detected by a noise sensor 1 is inputted to an adaptive filter 32, and is outputted as an offset tone from a speaker 5. The offset tone is interfered with a vibration noise, and is inputted as an error signal Em by the vibration sensor 6. The error signal Em is inputted to a prediction circuit 34, and an error signal Ee at a point P fixed arbitrarily in a room is predicted. An LMS processing part 33 updates the filter coefficient of the adaptive filter 32 so as to minimize the vibration noise at the point P based on a predicted error signal Ee and a signal, (r) delay-compensated by a fixed filter 31. The adaptive filter 32 generates an offset signal (y) by sampling the reference signal (x) by an updated filter coefficient.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an active vibration control device, and more particularly to an active vibration control device for actively controlling and reducing vibrations generated by traveling of a vehicle and noises caused by these vibrations. .

[0002]

2. Description of the Related Art In the present invention, the term "vibration" is used to include "noise".

Among vibration control devices, there is one called an active vibration control device for reducing vibration and noise by attenuating vibration generated from a vibration source (noise source) by canceling noise.

Conventionally, as an active vibration control device of this type, as shown in FIG. 5, a noise sensor 101 for detecting noise from a noise source (vibration source) and a noise detected by the noise sensor 101 are referred to. An adaptive control circuit 102 that generates a canceling signal that is input as a signal and that has a transfer characteristic having a phase opposite to that of the noise transfer characteristic;
A speaker 103 that emits a canceling sound based on a canceling signal generated by 02 and a vibration sensor (for example, a microphone) 104 that detects an error between the canceling sound generated by the speaker 103 and the noise are mainly configured. Are known (for example, Tokuhyo 1-501344).
Issue).

In the above conventional active vibration control device,
The noise (primary noise) detected by the noise sensor 101 is sampled by the A / D converter 105 and input to the adaptive control circuit 102 as a reference signal (reference signal) X of digital data. The cancellation signal generated as described above is output from the adaptive control circuit 102, converted into an analog signal by the D / A converter 106, and the speaker 10
Canceling sound (secondary noise) is emitted from 3.

On the other hand, the vibration sensor 104 is a speaker 103.
The synthesized sound of the canceling sound and the noise is received, the canceling sound is sampled by the A / D converter 107, extracted as an error signal ε of digital data, and fed back to the adaptive control circuit 102. That is, the error signal indicates a cancellation error between the primary noise and the secondary noise, and in the active vibration control device, the noise of the noise is changed by changing the characteristic of the cancellation signal so that the error signal becomes the minimum value. It is being reduced.

In the active vibration control device disclosed in Japanese Patent Publication No. 1-501344, the adaptive control circuit 10
2 has two FIR type adaptive digital filters (ADF)
Built-in, only the specific frequencies of the fundamental frequency and its harmonics are selected and processed.

In the adaptive control circuit 102,
An LMS algorithm (LMS: Least Mean) is used as an adaptive algorithm (calculation method) for generating an optimal cancellation signal.
Square) is generally used.

[0009]

However, since the above-mentioned conventional active vibration control device controls so that the error signal detected by the vibration sensor becomes the minimum value, only the vibration noise in the vicinity of the vibration sensor can be reduced. If the vibration sensor cannot be installed near the sound field where the vibration noise is desired to be reduced, the vibration noise reduction effect of the active vibration control device cannot be enjoyed. In particular, it is known that the higher the frequency of the vibration noise, the more the vibration noise closer to the installation position of the vibration sensor can be reduced. For example, due to the road noise having a higher frequency than the vibration noise caused by the engine noise. If the vibration noise is closer to the sound field where the vibration sensor is to be installed, the desired vibration noise reduction effect cannot be obtained.

FIG. 6 (a) shows the measurement results of the vibration noise at the position of the vibration sensor with and without the active vibration control device. The curves g2 ₂ and g2 ₁ are active curves, respectively. It is the vibration noise characteristics when the vibration control device is used and when it is not used.

FIG. 6 (b) shows the measurement results of the vibration noise at the ear position with and without the active vibration control device. The curves g2 ₄ and g2 ₃ are active vibrations, respectively. These are vibration noise characteristics with and without a control device.

In FIGS. 6A and 6B, the vertical axis represents sound pressure level (relative dB) and the horizontal axis represents frequency (Hz).

In FIG. 6A, since the vibration noise is measured at the position of the vibration sensor, the effect of reducing the vibration noise is exhibited over all frequencies, while the vibration noise is detected at the position of the ear. In the measured FIG. 6B, only the vibration noise in the low frequency region is reduced. That is, although the vibration noise is silenced near the vibration sensor, the person still feels the vibration noise.

On the other hand, the place where the vibration noise is desired to be reduced in the vehicle interior is a position where there is a vibration sensation organ of the human body represented by the ear, and as described above, the higher the frequency of the vibration noise, the mounting position of the vibration sensor. It is necessary to bring the sensor closer to the human body, but due to constraints such as the layout required as the living space of the vehicle, the sensor mounting position is naturally limited.

Therefore, the vibration sensor must be mounted at a position spaced a certain distance from the ear position in the vehicle interior.
In the conventional vibration noise control device, even if the vibration noise is reduced at the position where the vibration sensor is installed, the desired vibration noise reduction effect may not be obtained at the ear position. Especially, when the frequency band of noise is high, There is a strong tendency.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide an active vibration control device capable of reducing vibration noise at an arbitrary position in a vibration field regardless of the installation position of the vibration sensor. To aim.

[0017]

In order to achieve the above-mentioned object, the present invention inputs a signal highly related to vibration from a vibration source as a reference signal and reverses the vibration transfer characteristic from the vibration source. Control means for generating a canceling signal having a phase transfer characteristic, canceling vibration generating means for generating canceling vibration based on the canceling signal generated by the controlling means, canceling vibration generated by the canceling vibration generating means, and An error signal detection unit that detects an error signal that is a cancellation error with the vibration from the vibration source, and the control unit has a prediction unit that predicts vibration at at least one or more predetermined positions in the vibration field, The transfer characteristic of the cancellation signal is controlled so that the vibration at the predetermined position predicted by the predicting means becomes a minimum value.

Preferably, the error signal detecting means has a propagation time of vibration noise propagating from the vibration source to the error signal detecting means shorter than or equal to a propagation time from the vibration source to the predetermined position. The offset signal and the error signal are input to the prediction means.

[0019]

According to the above construction, the predicting means predicts the vibration noise at the predetermined position in the vibrating sound field, and based on the predicted noise vibration, the canceling signal of the canceling signal is set so as to minimize the vibration noise at the predetermined position. The characteristics are controlled.

Preferably, the error signal detecting means is installed at a position such that the propagation time of the vibration noise from the vibration source to the error signal detecting means is shorter or equal to the predetermined position from the vibration source.

Further, the vibration at the predetermined position is predicted based on the cancellation signal and the error signal.

[0022]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing the schematic construction of an embodiment of the active vibration control system according to the present invention.

In the figure, the active vibration control system comprises a noise sensor 1 installed in a noise source such as an automobile engine or a suspension, and an A / D converter for converting a noise signal from the noise sensor 1 into a digital signal x. 2, an adaptive control circuit 3 that receives the error signal Em by using the digital signal x as a reference signal and generates a cancellation signal y, a D / A converter 4 that converts the cancellation signal y into an analog signal, and a D / A converter An amplifier 5 that amplifies the output of No. 4 and a speaker 6 that converts the output of the amplifier 5 into a canceling sound, and is installed in, for example, the ceiling in the vehicle compartment, and noise inside the vehicle (primary noise) and canceling noise (secondary noise) The vibration sensor 7 detects a cancellation error of the vibration sensor 7, an amplifier 8 that amplifies the output of the vibration sensor 7, and an A / D converter 9 that converts the output of the amplifier 8 into a digital signal.

Further, the adaptive control circuit 3 includes an FIR type fixed filter 3 ₁ (whose filter coefficient is Ce) for compensating the transmission delay time from the speaker 6 to an arbitrary fixed point P in the vehicle compartment, and the like. An adaptive filter (hereinafter referred to as “ADF”) 3 ₂ that outputs a cancellation signal y based on a reference signal x and a signal from an LMS _{3 3} described later, a reference signal r compensated by a fixed filter 3 ₁ and a predicted signal described below. ADF3 ₂ by the LMS algorithm based on the error signal Ee
The LMS processing unit 3 ₃ for updating the filter coefficient of ₃ and the prediction circuit 3 ₄ for predicting the error signal Ee at the point P (for example, ear position) based on the cancellation signal y and the error signal Em. There is.

Transfer functions He and Hm represent transfer delay characteristics from a vibration source (not shown) to point P and a vibration source to vibration sensor 7, respectively, and transfer functions Ce and Cm are from speaker 6 to point P and speaker, respectively. 6
To the vibration sensor 7 are shown. These transfer functions He, Hm, Ce and Cm are measured in advance by experiments or the like and stored in storage means (not shown) as unique data of He / Hm, Ce and Cm.

In the active vibration control system thus constructed, the noise detected by the noise sensor 1 is A /
It is converted into a digital signal by the D converter 2 and input to the adaptive control circuit 3 as a reference signal x. Further, the output signal of the vibration sensor 7 is input to the adaptive control circuit 3 as an error signal Em via the amplifier 8 and the A / D converter 9, and the vehicle interior vibration noise is reduced based on the error signal Em and the reference signal x. The cancellation signal y that decreases is output. The canceling signal y is converted into an analog signal by the D / A converter 4 and the amplifier 5 and then amplified, and is output to the vehicle interior by the speaker 6 as a canceling sound.

FIG. 2 shows an equivalent circuit of the block diagram of FIG. 1. In FIG. 2, the elements corresponding to those of FIG. 1 are designated by the same reference numerals, and the description thereof will be omitted. Also, A / D
Converters 2, 9, D / A converter 4, amplifiers 5, 8
The speaker 6 is omitted from the figure.

The control operation of this embodiment will be described in detail below with reference to FIG.

The noise X ₀ is delayed by the transfer function Hm and then branched into two, one of which directly reaches the vibration sensor 7 and the other of which is delayed by the transfer function He / Hm and reaches the point P. That is, the noise X ₀ is the transfer function He (= Hm · H
e / Hm) to reach point P after a delay. Further, the reference signal x is the ADF3 ₂ having the filter coefficient Wi.
Is filtered to be a cancellation signal y, which is delayed by the transfer functions Cm and Ce and reaches the vibration sensor 7 and the point P, respectively.

In the vibration sensor 7, Hm · X ₀ and Cm · y
Error signal Em is added, and at point P, He · X
_The error signal Ee is obtained by adding ₀ and Ce · y. In the prediction circuit 3 _4, said error signal Ee is predicted using the error signal Em and the cancellation signal y by the following equation (1).

Ee = (Em−Cm · y) He / Hm + Ce · y (1) That is, since Em = Hm · X ₀ + Cm · y as described above, this Em is substituted into the mathematical expression (1). And organize
The following formula (2) is obtained.

Ee = He · X ₀ + Ce · y (2) Equation (2) represents the addition result of the noise and the cancellation signal at the point P, that is, the error signal at the point P. Therefore, the error signal Ee at the point P is predicted by the calculation of Expression (1).

Based on the error signal Ee predicted by the prediction circuit 3 ₄ and the signal r delay-compensated by the fixed filter 3 ₁ , the LMS processing unit 3 ₃ uses the following formula (3) to filter the ADF 3 ₂ . Update the coefficient.

W (n + 1) = W (n) + μ · Ee · r (3) Here, μ is a step size parameter (parameter for controlling the magnitude of the correction amount in each repetition). Note that the filter coefficient Wi is updated by the mathematical expression (3) so that the error signal Ee expressed by the mathematical expression (2) becomes 0. Therefore, the filter coefficient Wi finally becomes (-He / Ce). ). Therefore, the transfer function from the noise sensor 1 to the point P via the speaker 6 is −He / Ce · Ce = −He (4) as shown in the following mathematical expression (4), The transfer function He up to the point P is canceled and the vibration noise at the position of the point P is removed.

[0036] As described above, the prediction circuit 3 ₄ to predict the error signal Ee of the point P, the point P (e.g., ear position) it is possible to reduce the vibration noise in the vicinity.

FIG. 3 is a diagram showing an application example in which the present invention is applied to vibration noise control in the passenger compartment of an automobile.

In the figure, elements corresponding to those in FIG. 1 are assigned the same reference numerals and detailed explanations thereof are omitted, and only the main parts of the active vibration control device of FIG. 1 are described.

A person 12 is in a passenger compartment 11 of an automobile 10, a noise sensor 1 is installed in an engine 13, and a passenger compartment 11 is installed in the passenger compartment 11.
A vibration sensor (microphone) 7 is installed on the ceiling, a speaker 6 is installed on the dashboard, and an adaptive control circuit 3 is installed under the floor.

Further, as described above, the propagation characteristics (transfer functions) in which the vibration noise propagates directly from the noise source such as the engine 13 to the ear of the person 12 and the vibration sensor 7 are He and Hm, respectively. Transfer functions to the ear and the vibration sensor 7 are Ce and Cm, respectively.
Then, these four transfer functions He, Hm, Ce, Cm
And the offset signal y and the error signal Em.
The error signal Ee of the position of the ear is estimated using the equation (1). Therefore, as described above, the vibration sensor 7
Even if the person is separated from the ear of the person 12, the vibration noise near the ear can be removed.

[0041] FIG. 4 (a) shows the measurement result of the noise and vibration of the position of the vibration sensor when not used to using the active vibration control apparatus of the present embodiment, the curve g1 _2,
g1 ₁ is the vibration noise characteristics when the active vibration control device of this embodiment is used and when it is not used.

FIG. 4 (b) shows the results of measurement of the vibration noise at the position of the ear with and without the active vibration control device of this embodiment. The curves g1 ₄ and g1 ₃ are ,
These are vibration noise characteristics when the active vibration control device of the present embodiment is used and when it is not used.

In FIGS. 4A and 4B, the vertical axis represents sound pressure level (relative dB) and the horizontal axis represents frequency (Hz).

In FIG. 4A, since the vibration noise is measured at the position of the vibration sensor, the vibration noise in the low frequency region is only reduced, but the vibration noise is measured at the position of the ear. 4 (b) shows the effect of reducing vibration noise over all frequencies. That is, although the vibration noise is not suppressed near the vibration sensor, the person does not feel the vibration noise.

In the case of removing random vibration noise, the propagation time of the vibration noise propagating from the vibration source to the vibration sensor at the installation position of the vibration sensor is more than the propagation time from the vibration source to the point P. By setting the position so that it is also short or equal in time, it is possible to perform control with good followability to the vibration noise.

[0046]

As described above, according to the present invention,
Control means for inputting a signal highly related to vibration from the vibration source as a reference signal, and for generating a canceling signal having a transfer characteristic opposite in phase to the vibration transfer characteristic from the vibration source, and the control means. Canceling vibration generating means for generating canceling vibration based on the generated canceling signal, and error signal detection for detecting an error signal which is a canceling error between the canceling vibration generated by the canceling vibration generating means and the vibration from the vibration source. Means, the control means has a predicting means for predicting vibration at at least one or more predetermined positions in the vibration field, and the vibration at the predetermined position predicted by the predicting means becomes a minimum value. Since the transfer characteristic of the canceling signal is controlled, it is possible to reduce the vibration noise at the position without the error signal detecting means provided at the position where the vibration noise is desired to be reduced. Achieve the. In addition, when the error signal detection means is installed at a plurality of positions to perform multipoint control, the number of the error signal detection means installed can be reduced, and accordingly, the cost can be reduced. Play.

According to the invention of claim 2, the error signal detecting means has a propagation time of vibration noise propagating from the vibration source to the error signal detecting means from the vibration source to the predetermined position. Since it is installed at a position where the propagation time is shorter than or equal to the propagation time, it is possible to perform control with good followability even when controlling random vibration noise.

Further, according to the third aspect of the invention, since the canceling signal and the error signal are inputted to the predicting means, the vibration at the predetermined position can be minimized by a simple calculation program. Has the effect of enabling.

[Brief description of drawings]

FIG. 1 is a block diagram showing a schematic configuration of an embodiment of the present invention.

FIG. 2 is a diagram showing an equivalent circuit of the block diagram of FIG.

FIG. 3 is a diagram showing an application example in which the present invention is applied to vibration noise control in a passenger compartment of an automobile.

FIG. 4 is a diagram showing the frequency of vibration noise of the present invention and its silencing effect.

FIG. 5 is a block diagram showing a schematic configuration of a conventional active vibration control device.

FIG. 6 is a diagram showing a vibration noise frequency and a noise reduction effect thereof according to a conventional technique.

[Explanation of symbols]

1 Noise Sensor 3 Adaptive Control Circuit (Control Means) 3 ₄ Prediction Circuit (Prediction Means) 6 Speaker (Offset Vibration Generation Means) 7 Vibration Sensor (Error Signal Detection Means)

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Makoto Namegawa 1-8 Nishigotanda, Shinagawa-ku, Tokyo Alpine Electronics Co., Ltd.

Claims (3)

[Claims] 1. A control means for inputting a signal highly related to vibration from a vibration source as a reference signal, and for generating a canceling signal having a transfer characteristic opposite in phase to the vibration transfer characteristic from the vibration source. A canceling vibration generating unit that generates a canceling vibration based on the canceling signal generated by the control unit, and an error signal that is a canceling error between the canceling vibration generated by the canceling vibration generating unit and the vibration from the vibration source. Error signal detection means for detecting, the control means has a prediction means for predicting vibration at at least one or more predetermined positions in the vibration field, and the vibration at the predetermined position predicted by the prediction means is minimum. An active vibration control device, characterized in that the transfer characteristic of the cancellation signal is controlled so as to have a value. 2. The error signal detecting means is configured such that a propagation time of vibration noise propagating from the vibration source to the error signal detecting means is shorter than or equal to a propagation time from the vibration source to the predetermined position. The active vibration control device according to claim 1, wherein the active vibration control device is installed at the following position. 3. The active vibration control device according to claim 1, wherein the canceling signal and the error signal are input to the predicting means.