JP3372572B2 - Active vibration noise control device for vehicles - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle active vibration noise control system, and more particularly to a vehicle active vibration noise control system for controlling vibration noise in a vehicle compartment in which an occupant of a moving transportation system such as an automobile lives.

[0002]

2. Description of the Related Art Conventionally, a vibration detecting means for detecting a vibration from a vibration source of a vehicle, a control means for generating a canceling signal having a phase opposite to the vibration based on the vibration detected by the vibration detecting means, A canceling vibration generating unit that generates a canceling vibration according to a canceling signal, and a canceling error detecting unit that detects a canceling error between the vibration from the vibration source and the canceling signal, the control unit using an adaptive filter. There has been proposed an active vibration noise control device for a vehicle, which is provided with a control unit for controlling the offset error detected by the offset error detection unit to be minimum (for example, Japanese Patent Publication No. 1-501344).

This active vibration noise control device can be applied, for example, as a device for reducing vehicle interior vibration noise, particularly road noise generated due to unevenness of the road surface when the vehicle is running. A vibration detection pickup as a vibration detection means is directly attached to the knuckle or suspension arm of each wheel, and the vibration signal detected by this vibration detection pickup is used as a reference signal. The canceling signal is generated and the canceling vibration is generated by the speaker or the like to reduce the noise in the vehicle interior.

[0004]

However, in such a conventional active vibration noise control device for a vehicle, in order to cancel random noise (vibration noise) such as road noise in the vehicle compartment, a high coherence is applied to the vibration noise. Therefore, the vibration detection pickup must be installed on a plurality of vibration sources, for example, four wheels in the case of a four-wheeled vehicle, which not only causes an increase in the number of parts and an installation cost, but also Since signal processing is performed based on each random reference signal, there is a problem in that the processing time increases and the timing of cancellation vibration is delayed.

[0005] The present invention has been made to solve the above problems, while reducing the number of parts and installation costs, and eliminate the delay in the generation timing of the offsetting oscillation, vibration noise more effectively It is an object of the present invention to provide an active vibration noise control device for a vehicle that can be offset.

[0006]

To achieve the above object, the invention according to claim 1 is based on a vibration detecting means for detecting a vibration which is a noise source of noise, and a vibration detected by the vibration detecting means. In the active vibration noise control device for a vehicle, which comprises a control means for generating a canceling signal having a phase opposite to that of the noise, and a canceling vibration generating means for generating a canceling vibration according to the canceling signal. The vibration detecting means is provided, and the vehicle speed detecting means for detecting the vehicle speed, and the same point passing time difference between the front wheel and the rear wheel based on the vehicle speed detected by the vehicle speed detecting means is obtained as a delay time, and the vibration detecting means is provided. Delay means for delaying the vibration detected by the obtained delay time to obtain a rear wheel vibration signal, and the control means controls the front wheel vibration signal and the rear wheel vibration signal from the vibration detection means. Based and generates said cancellation signal.

According to a second aspect of the present invention, there is provided a vibration detecting means for detecting a vibration which is a noise source of noise, and a control for generating a canceling signal having a phase opposite to the noise based on the vibration detected by the vibration detecting means. Means, a canceling vibration generating means for generating a canceling vibration according to the canceling signal, and a canceling error detecting means for detecting a canceling error between the vibration from the vibration source and the canceling signal, wherein the control means is adaptive. In an active vibration noise control device for a vehicle, which controls using a filter so that a cancellation error detected by the cancellation error detecting means is minimized,
The vibration detecting means is arranged in the front wheel portion of the vehicle, and the vehicle speed detecting means for detecting the vehicle speed, and the time length of the adaptive filter is set between the front wheel and the rear wheel based on the vehicle speed detected by the vehicle speed detecting means. And a setting means for setting the time to be longer than the same point passing time difference.

[0008]

According to the structure of the first aspect of the invention, based on the vehicle speed detected by the vehicle speed detecting means, the vibration of the front wheel portion detected by the vibration detecting means is delayed to be a vibration signal of the rear wheel portion, and the front wheel portion is detected. A cancellation signal is generated based on the vibration signal and the rear wheel vibration signal.

According to the configuration of the second aspect of the invention, the time length of the adaptive filter is set to be longer than the passage time difference between the front wheels and the rear wheels based on the detected vehicle speed.

[0010]

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

FIG. 1 is a block diagram showing a schematic configuration of a first embodiment of an active vibration noise control system for a vehicle according to the present invention. The present embodiment is applied to a vehicle road noise control device. It should be noted that FIG. 1 shows only the vibration noise control portion for the right side of the vehicle body of the present control device, and the left side of the vehicle body has the same structure, so the illustration thereof is omitted.

In FIG. 1, reference numeral 1 denotes a vibration detection pickup installed in a front wheel suspension (vibration source) of a vehicle (not shown). The vibration detected by the pickup 1 is output as digital data to the output side of the vibration detection pickup 1. The A / D converter 2 for converting into the reference signal x of is connected.

The reference signal x from the A / D converter 2 is
It is input to the adaptive control circuits 5 ₁ and 5 ₂ . The adaptive control circuits 5 ₁ and 5 ₂ respectively use coefficients C ₁₁ (∧) and C ₁₂ (for compensating a transmission delay time from a front speaker 9 ₁ to a front error microphone 10 ₁ and a rear error microphone 10 ₂ described later). ∧) and the FIR filter 5 _11, 5 ₂₁ with an adaptive filter 5 _12, 5 ₂₂ for generating a cancellation signal y _1, y ₂ of the same amplitude in the detecting vibration in opposite phase of the pickup 1 on the basis of the reference signal x, FIR filter 5 ₁₁ ,
52 based on the reference signal x compensated by ₂₁ and error signals e ₁ and e ₂ described later, the least mean square (Least Mean Square)
e: hereinafter referred to as “LMS”) algorithm and LMS processing units 5 ₁₃ and 5 ₂₃ that update the filter coefficients of the adaptive filters 5 ₁₂ and 5 ₂₂ .

Further, on the output side of the A / D converter 2,
A delay circuit 4 is connected, and the delay circuit 4 calculates the delay time between the front wheels and the rear wheels, that is, the time difference between the front wheels and the rear wheels passing through the same ground based on the vehicle speed detected by the vehicle speed sensor 3, and the delay time is calculated. Delay by time. The output signal x ′ indicating the delayed reference signal x from the delay circuit ₄ is input to the adaptive control circuits 5 ₃ and 5 ₄ .

Since the configurations of the adaptive control circuits 5 ₃ and 5 ₄ are similar to those of the above-mentioned adaptive control circuits 5 ₁ and 5 ₂ , detailed description thereof will be omitted.

The output sides of the control circuits 5 ₁ , 5 ₂ and 5 ₃ , 5 ₄ are connected to adders 6 ₁ , 6 ₂ , respectively, and the outputs y _{1 of the} adaptive filters 5 ₁₂ , 5 ₂₂ and 5 ₃₂ , 5 ₄₂ are connected. , Y ₂ and y ₃ , y ₄
Are added by adders 6 ₁ and 6 ₂ , respectively. Adder 6
The output sides of ₁ and 6 ₂ are connected to D / A converters 7 ₁ and 7 ₂ , and the digital signals y ₁ + y ₂ and y ₃ + y ₄ are converted into analog signals. The output sides of the D / A converters 7 ₁ and 7 ₂ are connected to the front speaker 9 ₁ and the rear speaker 9 ₂ via amplifiers 8 ₁ and 8 ₂ , respectively, and the amplified analog signal is canceled as a front speaker. 9 ₁ and the rear speaker 9 ₂ .

Further, the front error microphone 1 for picking up vibration noise which is not removed by the canceling sound output from the front speaker 9 ₁ and the rear speaker 9 _2.
0 ₁ and a rear error microphone 10 ₂ are provided, and their output sides are A / D via amplifiers 11 ₁ and 11 ₂ , respectively.
The converters 12 ₁ and 12 ₂ are connected to the output sides thereof to the LMS processing units 5 ₁₃ , 5 ₃₃ and 5 ₂₃ , 5 ₄₃ of the adaptive control circuits 5 ₁ , 5 ₂ and 5 ₃ , 5 ₄ , respectively. . As described above, the A / D converter 1 is picked up by the front error microphone 10 ₁ and the rear error microphone 10 ₂ and amplified by the amplifiers 11 ₁ and 11 _2.
The error signals e ₁ and e ₂ digitally converted by 2 ₁ and 12 ₂ are input to LMS processing units 5 ₁₃ , 5 ₃₃ and 5 ₂₃ , 5 ₄₃ which determine the filter coefficients of the adaptive filters 5 _{1 to} 5 ₄ , respectively. .

The operation of the apparatus according to this embodiment will be described in detail below.

The detected vibration picked up by the vibration detecting pickup 1 is digitally converted by the A / D converter 2 into a reference signal x, which is branched into two.
Of these, one reference signal x is input to the adaptive control circuits 5 ₁ and 5 ₂ . Reference signal x input to the adaptive control circuit 5 _1.
Is further branched into two, one reference signal x is directly input to the adaptive filter 5 ₁₂ , and the other reference signal x is input to the front speaker 9 via the FIR filter 5 ₁₁ having the filter coefficient C ₁₁ (∧). The transfer characteristics between ₁ and the front error microphone 10 ₁ are compensated and input to the LMS processing unit 5 ₁₃ .

Furthermore, the LMS processor 5 _13, the error signal e ₁ is input, LMS processor 5 ₁₃ adaptive filter 5 based on the reference signal compensated by the error signal e ₁ and FIR filter 5 ₁₁ Update ₁₂ filter coefficients.

By using the updated filter coefficient, the adaptive filter 5 ₁₂ generates the canceling signal y ₁ based on the input reference signal x.

Similarly, the adaptive filter 5 ₂₂ also generates the cancellation signal y ₂ based on the filter coefficient from the LMS processing unit 5 ₂₃ and the input reference signal x.

As described above, the cancellation signals y ₁ and y ₂ are added by the adder 6 _1, converted into an analog signal by the D / A converter 7 ₁ , amplified by the amplifier 8 _{1 and} canceled by the front speaker 9 _1. Is output.

On the other hand, the other branched reference signal x is input to the delay circuit 4. The delay circuit 4 includes the vehicle speed sensor 3
According to the vehicle speed detected by, the same point passing time difference between the front wheels and the rear wheels is obtained, the reference signal x is delayed by the time difference, and when the vibration detecting pickup is installed on the rear wheel, it is detected by this pickup. A pseudo reference signal x'which simulates the reference signal to be generated is generated.

The reference signal x'generated in this way
Is input to the adaptive control circuits 5 ₃ and 5 ₄ and is similar to the reference signal x input to the adaptive control circuits 5 ₁ and 5 ₂ described above,
The cancellation signals y ₃ and y ₄ are generated by the adaptive filters 5 ₃₂ and 5 ₄₂ , and the cancellation sound is output via the adder 6 ₂ , the D / A converter 7 ₂ , the amplifier 8 ₂ and the rear speaker 9 ₂ .

Therefore, the canceling sound output through the front speaker 9 ₁ and the rear speaker 9 ₂ interferes with the noise vibration directly propagated from the vibration source, and the noise reduction control is performed.

The vibration which is not removed by the canceling sound is detected as analog data by the front error microphone 10 ₁ and the rear error microphone 10 ₂ and is amplified by the amplifiers 11 ₁ and 11 _{2 and then} amplified by the A / D converters 12 ₁ and 12 12. LMS processing units 5 ₁₃ , 5 ₃₃ and 5 ₂₃ , 5 are converted into digital signals e ₁ and e ₂ via ₂ respectively.
_Entered in ₄₃ .

As described above, in the present embodiment, the vibration detecting pickup is installed only in the suspension of the front wheels,
A delay circuit 4 for delaying the reference signal x detected by the pickup by a time corresponding to the same point passing time difference between the front wheels and the rear wheels according to the vehicle speed is provided, and a pseudo reference signal x'which simulates the vibration of the rear wheels is provided. Since it is generated, it is possible to perform the silencing control of the vibration noise of the rear wheels, which has a high correlation with the vibration noise of the front wheels. As a result, the rear wheel pickup parts can be omitted, and the signal of the rear wheel suspension can be obtained earlier than when the pickup is actually installed. Digital signal processor (hereinafter,
The “DSP”) can take a longer calculation time than the road noise canceling DSP by the front wheels, so a low-cost DSP that operates at a low speed will suffice. Therefore, as compared with the active noise control device in which the pickups are attached to the four wheels, it is possible to realize the active noise control device at a low cost and with substantially the same performance.

FIG. 2 is a schematic diagram showing the basic construction of the second embodiment of the active vibration control system according to the present invention.

The apparatus of FIG. 2 differs from the apparatus of FIG. 1 in that the time length of the adaptive filter 50 ₂ of the adaptive control circuit 50 is variably set according to the vehicle speed detected by the vehicle speed sensor 3. That is, in FIG. 2, the adaptive filter 50 ₂
A vehicle speed sensor 3 is connected to the vehicle speed sensor 3. Depending on the vehicle speed detected by the vehicle speed sensor 3, for example, the higher the vehicle speed, the more the adaptive filter 5
The time length of 0 ₂ , that is, the number of taps that determines the length of the impulse response is set to be smaller. In FIG. 2, the configurations and connection relationships of the elements other than those described above are the same as the corresponding elements in FIG. 1, so these elements are given the same reference numerals and detailed description thereof is omitted.

The adaptive filter 50 ₂ is, in this embodiment,
As shown in FIG. 3, n filter coefficients Wk (k =
0, 1, ..., N-1) and n-1 time delay elements z
(1) and n-1 adders, which is a transversal filter, and has an output Y (z) and an input X.
The relationship between (z) and the transfer function H (z) of the applied filter is as shown below.

Y (z) = H (z) X (z) (1) When the relationship between the output Y (z) and the input X (z) is represented in the discrete time domain,

[0033]

[Equation 1] Therefore, it can be seen that the output signal y (t) at the current time t depends on the past input signal x (t−k) (k = 0, 1, ..., N−1). The maximum number that k can take (n in this case)
The larger the number of taps, the larger the number of taps, the more the cancellation signal can be generated based on the older input signal, that is, the older reference signal, and as a result, the controllable time range can be extended. it can.

For example, if the sampling frequency fs of the detected vibration from the vibration detecting pickup 1 is 1 kHz, the sampling period T is 1 ms, and if the wheel base of the vehicle is 2.6 m and the vehicle speed is 60 km / h, the front and rear wheels will be. 0.156s /
1 ms = 156 taps. Therefore, at least 156
By using the adaptive filter having the number of taps equal to or more than the taps, it is possible to suppress the vibration noise caused by the rear wheel portion as the vibration source by using only the reference signal detected by the vibration detecting pickup installed in the front wheel portion. In this embodiment, since the number of taps is variable according to the vehicle speed, the numerical value n that governs the number of taps described in the equation (2) is made variable and n = 156 is set, whereby taps of 156 taps are set. An adaptive filter with a number can be created. For the numerical value of n that governs the number of taps, a map showing the relationship between n and the vehicle speed is used, and the value of n is read from the map by a signal from the vehicle speed sensor to determine n.

In practice, the adaptive filter is a general purpose DSP.
The number of taps is a power of 2 in correspondence with the number of memories for storing the filter coefficients. That is, the vehicle speed sensor has a vehicle speed of 20 to 40 km / h and 40 to 80 km / h.
The DSP is controlled so that the tap numbers of 512, 256, 128, and 64 are taken according to h, 80 to 150 km / h, and 150 to 200 km / h, respectively.

In this way, if the number of taps is adjusted according to the vehicle speed and the time length of the adaptive filter 50 ₂ is set to be longer than the time difference between the front wheels and the rear wheels passing through the same ground, it is possible to correlate with the vibration noise of the front wheels. It is possible to remove the vibration noise of the rear wheel, which has high property, based on the reference signal from the pickup 1 installed in the front wheel suspension.

FIG. 4 is a timing chart showing the timing of vibration noise, reference signal, canceling sound and error signal.

In the figure, (a) shows vibration noise propagated to an occupant in the passenger compartment, and vibrations a and b are front wheels,
Vibration noise from the rear wheels is shown. (B) shows the reference signal detected by the vibration detection pickup 1. (C) is
The first canceling sound emitted from the speaker when the active vibration control device is used for the first time and control is started is shown. At this time,
Since the noise and vibration information from the rear wheels is not fed back to the LMS processing unit 50 ₃ , only the canceling sound for the vibration noise from the front wheels is generated.

FIG. 4D shows an error signal detected by the error microphone 10. Here, the signal C is
The canceling sound of FIG. 4C interferes with the noise vibration of the front wheel of FIG. 4A, and as a result, an error signal having a vibration component that is not removed is shown. The signal D corresponds to the vibration noise of the rear wheel as described above. Since the cancellation signal is not generated, the vibration noise is shown as an error signal as it is.

FIG. 4 (e) shows the canceling sound output from the speaker 9 after a lapse of some time from the start of the control. Signals “e” and “f” indicate canceling sounds for removing vibration noise (a and b in FIG. 4A) from the front and rear wheels, respectively.

FIG. 4F shows an error signal detected by the error microphone 10 when the vibration noise of FIG. 4A is interfered by the canceling sound of FIG. 4E. Signals T and J indicate vibration components that are not removed by the canceling sounds E and F, respectively.

As described above, the tap length (number) is set to be longer than the time difference between the front wheel and the rear wheel passing through the same ground, so that the vibration noise of not only the front wheel but also the rear wheel is removed from the speaker 9. Cancellation sound will be generated.

FIG. 5 is a block diagram showing a configuration example in which this embodiment is actually applied to a vehicle road noise control device.

[0044] Figure 5 is a right speaker 9 _'1 and the left speaker 9' ₂ on the right and left sides of the vehicle compartment front to generate canceling sound, the left and right seats the right error microphone 10 _'1 and left error microphone 10' ₂ was placed on top ceiling, four adaptive control circuit 5 _{'1-5' 4,} left and right front wheels of the vibration detecting pickup installed respectively Sasupeshon 1 _1, 1 _2, it is constituted by a vehicle speed sensor 3.

Since this application example is the same in operation and effect as the second embodiment described above, detailed description thereof will be omitted.

As described above, according to the second embodiment,
A pickup is installed only on the front wheel side, and the tap length of the adaptive filter is variably set longer than the same point transit time difference between the front and rear wheels according to the vehicle speed so that the vibration noise of the rear wheels that correlates with the front wheel vibration noise can be controlled by, omitting the vibration detecting pickup for installing the rear wheel side, thereby enabling reduction of the number of parts and installation costs.

In the present embodiment, the LMS algorithm is used as the method of updating the filter coefficient of the adaptive filter, but the present invention is not limited to this, and other algorithms such as the maximum likelihood method may be used.

Further, as a means for changing the control time length, there is a method other than the present embodiment in which the sampling frequency is changed to make the control time length variable.

[0049]

As described above, according to the first aspect of the invention, the vibration detecting means for detecting the vibration, which is the noise source of the noise, and the noise opposite to the noise are detected based on the vibration detected by the vibration detecting means. In a vehicle active vibration noise control device comprising a control means for generating a phase cancellation signal and a cancellation vibration generation means for generating a cancellation vibration according to the cancellation signal, the vibration detection means is arranged at a front wheel portion of the vehicle. The vehicle speed detection means for detecting the vehicle speed, and the same point passing time difference between the front wheels and the rear wheels based on the vehicle speed detected by the vehicle speed detection means as the delay time, and the vibration detected by the vibration detection means. Delaying means for delaying the obtained delay time to obtain a rear wheel vibration signal, and the control means cancels the cancellation based on the front wheel vibration signal and the rear wheel vibration signal from the vibration detecting means. Since generating a No., also claim 2
The described invention is a vibration detecting means for detecting a vibration that is a noise source of noise, a control means for generating a canceling signal having a phase opposite to the noise based on the vibration detected by the vibration detecting means, and the canceling signal. And a canceling error detecting means for detecting a canceling error between the vibration from the vibration source and the canceling signal, and the control means cancels the canceling using an adaptive filter. In a vehicle active vibration noise control device for controlling so that the offsetting error detected by the error detecting means is minimized, the vibration detecting means is provided in the front wheel portion of the vehicle, and a vehicle speed detecting means for detecting the vehicle speed, Since there is a setting means for setting the time length of the adaptive filter so as to be longer than the same point passing time difference between the front wheels and the rear wheels based on the vehicle speed detected by the vehicle speed detecting means, It is possible to omit the vibration detection means that should be disposed in the section, reduce the number of parts for the vibration pickup, reduce the cost for mounting the vibration pickup, and reduce the DSP cost. It has become possible to realize an active vibration noise control system for a vehicle, which has almost the same performance as the one with all vibration detection means attached.

[Brief description of drawings]

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

FIG. 2 is a block diagram showing a basic configuration of a second embodiment of the present invention.

FIG. 3 is a circuit configuration diagram of an applied digital filter used in a second embodiment of the present invention.

FIG. 4 is a timing chart showing the timing of each signal in the second embodiment.

FIG. 5 is a block diagram showing a schematic configuration of an application example of a second embodiment of the present invention.

[Explanation of symbols]

1, 1 ₁ , 1 ₂ Vibration detection pickup (vibration detection means) 3 Vehicle speed sensor (vehicle speed detection means) 4 Delay circuit (delay means) 5 _{1 to} 5 ₄ Digital signal processor (control means) 9 ₁ , 9 ₂ , 9 ′ ₁ , 9 ′ ₂ speaker (cancellation signal generating means) 10 ₁ , 10 ₂ , 10 ′ ₁ , 10 ′ ₂ error microphone (error vibration detecting means) 50 ₂ , 5 ′ ₁₂ , 5 ′ ₂₂ , 5 ′ ₃₂ , 5 ′ ₄₂ Applicable digital filter (setting means)

Continuation of front page (56) Reference JP-A-3-203496 (JP, A) JP-A-3-203792 (JP, A) JP-A-2-296520 (JP, A) JP-A-5-80779 (JP , A) (58) Fields investigated (Int.Cl. ⁷ , DB name) G10K 11/178 B60R 11/02 F01N 1/00 F01N 1/06 F16F 15/02

Claims (2)

(57) [Claims] 1. A vibration detecting means for detecting a vibration which is a noise source of noise, a control means for generating a canceling signal having a phase opposite to the noise based on the vibration detected by the vibration detecting means, and the canceling signal. In an active vibration noise control device for a vehicle, comprising: a canceling vibration generating means for generating a canceling vibration according to the above, in the front wheel portion of the vehicle, the vibration detecting means is arranged, and a vehicle speed detecting means for detecting a vehicle speed, Based on the vehicle speed detected by the vehicle speed detecting means, a difference in passing time between the front wheel and the rear wheel at the same point is obtained as a delay time, and the vibration detected by the vibration detecting means is delayed by the obtained delay time to cause a rear wheel vibration. A delay means for obtaining a signal is provided, and the control means generates the canceling signal based on the front wheel vibration signal and the rear wheel vibration signal from the vibration detection means. Noise control device. 2. A vibration detecting means for detecting a vibration which is a noise source of noise, a control means for generating a canceling signal having a phase opposite to that of the noise based on the vibration detected by the vibration detecting means, and the canceling signal. And a canceling error detecting means for detecting a canceling error between the vibration from the vibration source and the canceling signal, and the control means cancels the canceling using an adaptive filter. In an active vibration noise control device for a vehicle that controls so that the offsetting error detected by the error detection means is minimized, the vibration detection means is provided in the front wheel portion of the vehicle, and a vehicle speed detection means for detecting the vehicle speed, A setting means for setting the time length of the adaptive filter so as to be longer than the same point passing time difference between the front wheels and the rear wheels based on the vehicle speed detected by the vehicle speed detecting means. Vehicular active vibration noise control apparatus according to.