JP2008139367A - Active oscillating noise control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce sound increase due to undesirable sound increase effect in the vicinity of a second frequency, e.g. 60 [Hz] in the vicinity of a first frequency generated, when adaptative noise control is performed by performing the adaptative noise control in the vicinity of the first frequency of the largest sound pressure (noise) among the low-frequency load noise e.g. 40 [Hz], for reducing noise. <P>SOLUTION: There is provided a discrete calculation processing device 202, for generating a second control signal S2 for generating cancellation sounds in a second frequency region for increasing the sound, when the sound is decreased in a first frequency region by a discrete calculation processing device 21B for generating a first control signal S1 for the cancellation sound in the first frequency region of the maximum sound pressure. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an active vibration noise control device that cancels and muffles vehicle interior noise with secondary noise (cancellation sound) having a phase opposite to that of the noise, and is, for example, vehicle interior noise generated during travel of a vehicle. The present invention relates to an active vibration noise control device that can effectively mute low frequency road noise (also referred to as drumming noise) of 150 Hz.

  The vibration of the wheel received from the road (road) while the vehicle is traveling is transmitted to the vehicle body via the suspension, and is excited by the acoustic resonance characteristics of the closed space such as the interior of the vehicle and has a peak at about 40 Hz. An active noise control device related to the invention of this application that cancels out vehicle interior noise caused by low-frequency road noise with a 150 Hz bandwidth has been proposed (Patent Document 1).

  As shown in the block diagram of FIG. 6, in the active noise control device 2 described in Patent Document 1, the vehicle interior 4 receives the vehicle interior noise and the canceling sound output from the speaker 6. The microphone 8 is provided in the belly part of the acoustic eigenmode of the passenger compartment 4. The feedback control unit (FBC) 10 includes a band-pass filter (BPF) 12 that detects low-frequency road noise, an amplitude compensation circuit 14 such as an amplifier that compensates for amplitude, and a phase compensation circuit 16 that compensates for phase. Composed.

  Then, the FBC 10 compensates the amplitude and phase of the low-frequency road noise extracted from the output of the microphone 8, generates a control signal having a phase opposite to that of the noise, and drives the speaker 6 to suppress the noise. .

  Although it is not a device that cancels low-frequency road noise, an active noise reduction device related to the invention of this application has been proposed (Patent Document 2).

  As shown in FIG. 7, the active noise reduction device 20 proposed in Patent Document 2 has an adaptive notch filter type discrete arithmetic processing device 21 and is generated from a noise source such as an engine 22 whose noise frequency changes. The frequency of the noise (the notch frequency to be silenced, hereinafter simply referred to as the notch frequency), which is a problem with the periodicity, is detected from the engine pulse through the waveform shaper 23 and generates a cosine wave signal synchronized with the notch frequency. A wave generator 26 and a sine wave generator 28 for generating a sine wave signal are provided.

  The first one-tap adaptive filter 30 to which a cosine wave signal that is an output signal from the cosine wave generator 26 is input, and the second one to which a sine wave signal that is an output signal from the sine wave generator 28 is input. 1-tap adaptive filter 32, an adder 34 for adding the output signal from first 1-tap adaptive filter 30 and the output signal from second 1-tap adaptive filter 32, and the output signal from this adder 34 Sound output means 38 that is driven by a certain control signal and generates a canceling sound.

  Further, a sound detection means 40 for detecting a residual signal due to interference between the canceling sound and the noise to be the problem as an error signal, and the cosine wave signal and the sine wave signal are input to the sound detection means from the sound output means 38. Characteristics simulating transmission characteristics up to 40 (referred to as simulated transmission characteristics (real part) Cr and simulated transmission characteristics (imaginary part) Ci). }, The simulated signal generating means 42 for outputting the simulated cosine wave signal and the simulated sine wave signal (consisting of transmission elements 49, 50, 51, 52 and adders 53, 54), and the adder 34. A signal identical to the output control signal is corrected with a characteristic obtained by simulating a transfer characteristic between the sound output means 38 and the sound detection means 40 (simulated transfer characteristics Cr and Ci described above) and a predetermined constant α. The correction signal generating means 56 (the transmission elements 59, 60, 61, 62, the adders 63, 64, the coefficient multipliers 71, 72, the adder 73, and the constant multiplier 74) that outputs the corrected signal that has been output. .).

  Furthermore, an error signal e ′ obtained by adding an error signal e, which is an output signal from the sound detection means 40, and an output signal from the correction signal generation means 56 by an adder 76, and an output signal from the simulation signal generation means 42 (described above) Are provided with adaptive control algorithm computing units (LMS) 80 and 82.

  The active noise reduction apparatus 20 configured as described above is based on an adaptive control algorithm of the adaptive control algorithm computing unit 80, for example, a LMS (Least Mean Square) algorithm that is a kind of steepest descent method. 30 and by updating the filter coefficients A and B of the second one-tap adaptive filter 32 and the coefficients A and B (equivalent to the filter coefficients A and B) of the coefficient multipliers 71 and 72 at the position of the sound detection means 40. The noise which becomes the said subject is reduced.

JP 2000-322066 A (FIGS. 10 and 12) JP 2004-354657 A (FIGS. 7 and 8)

  By the way, a vehicle equipped with the active noise reduction device 20 shown in FIG. 6 proposed in Patent Document 1 can dramatically reduce low-frequency road noise compared to a vehicle not equipped with this device. it can. Moreover, the configuration is simple and the cost is low.

  However, the adaptability to changes in the vehicle compartment environment such as changes in circuit components constituting the speaker 6, microphone 8 and FBC 10 over time, and changes in the number of passengers is low.

  In order to solve this drawback, an active noise reduction device for reducing engine noise shown in FIG. 7 proposed in Patent Document 2 having high adaptability in response to changes in these circuit components and changes in the vehicle interior environment. 20 may be applied to a low-frequency road noise reduction device.

  FIG. 8A shows a low-frequency road noise characteristic (pre-reduction noise characteristic) 94 before reduction obtained by measuring vehicle interior noise of a vehicle at the position of the microphone 8. It can be seen that there is a significant maximum region of sound pressure [dB] in the vicinity of the frequency 40 [Hz].

  FIG. 9 is a block diagram showing the configuration of the active vibration noise control apparatus 100 that has been first devised to cancel the low-frequency road noise in the vehicle interior due to the pre-reduction noise characteristic 94 shown in FIG. 8A.

  9 is similar in that it has a discrete arithmetic processing device 21A corresponding to the adaptive notch filter type discrete arithmetic processing device 21 shown in FIG. 7, but the peak in FIG. The difference is that a reference cosine wave signal generator 90 having a frequency of about 43 [Hz] corresponding to the frequency is provided.

  The active noise reduction device 20 in FIG. 7 is a device that reduces engine noise, whereas the active vibration noise control device 100 in FIG. 9 is also a device that reduces low-frequency road noise. .

In FIG. 9, the block depicting Z ⁻ⁿ is a 90-degree phase shifter 88 that shifts the phase by 90 degrees at the frequency of the reference cosine wave signal. The output of the 90-degree phase shifter 88 is a reference. A sine wave signal is output. The other components are substantially the same except for the formal difference due to the equivalent conversion of the block diagram, so that the operation shown in FIG. 9 is similar to that shown in FIG. Corresponding components are denoted by the same reference numerals.

  FIG. 8B shows a low-frequency road noise characteristic (after reduction) after the active vibration noise control apparatus 100 of FIG. 9 is mounted on the vehicle and low-frequency road noise in the vicinity of 40 [Hz] is reduced. Noise characteristic) 96 and the pre-reduction noise characteristic 94 shown in FIG. 8A.

  In the post-reduction noise characteristic 96 of FIG. 8B, the noise near 40 [Hz] is certainly greatly reduced to about −8 [dB] in sound pressure, but the sound pressure is conversely near 53 [Hz]. It has increased by about 10 [dB]. As a result, the reduced noise characteristic 96 has a peak value reduced by about 3 [dB] compared to the pre-reduction noise characteristic 94, and although it has a certain reduction effect, it is found that the noise reduction effect is still insufficient. It was.

  FIG. 8C is a sensitivity function of the active vibration noise control apparatus 100 of FIG. 9, and the active vibration noise control apparatus 100 of FIG. 9 includes the reference cosine wave signal generated by the reference cosine wave signal generator 90. It is understood that the noise reduction effect is the highest at about -8 [dB] at a frequency of about 43 [Hz], but on the contrary, the frequency is increased by about +10 [dB] at a frequency of about 53 [Hz].

  The present invention has been made in consideration of the above-described problems, and reduces noise by performing adaptive noise control in the vicinity of the first frequency with the highest noise, for example, the above-described frequency of 43 [Hz], in the vehicle interior noise. At the same time, the sound increase due to the undesirable sound increase effect in the vicinity of the second frequency near the first frequency, for example, in the vicinity of the above-mentioned frequency 53 [Hz], which is generated when this adaptive noise control is performed, is also effectively reduced. It is an object of the present invention to provide an active vibration and noise control device that can be used.

  The active vibration noise control device according to the present invention includes a sound detection means for detecting a mixed sound of a canceling sound of the vehicle interior noise output from the sound output means based on the control signal and the vehicle interior noise, and the sound detection means. In the active vibration noise control apparatus comprising the control signal generation means for generating the control signal when the output signal is input, the control signal generation means includes a first portion including a maximum portion of sound pressure in the vehicle interior noise. A first control signal generating means for generating a first control signal in the frequency domain; and a second control signal generating means for generating a second control signal, wherein the second control signal generating means is generated one sample before The added control signal of the generated first control signal and the second control signal generated one sample before is input, and when the sound is reduced in the first frequency domain by the updated first control signal, the sound is increased Second frequency range The updated second control signal for outputting the canceling sound of the second control signal is generated from the sound output means, and the addition control signal of the updated first control signal and the updated second control signal is used as the control signal. It outputs to a sound output means, It is characterized by the above-mentioned.

  According to this invention, when noise is reduced in the first frequency range by the first control signal generating means for generating the first control signal in the first frequency range including the maximum portion of the sound pressure in the vehicle interior noise. A second control signal for outputting a canceling sound from the sound output means is generated by the second control signal generation means in the second frequency region where the sound is increased, and the first control signal and the second control signal are added. Since the control signal is output to the sound output means, the noise is reduced by adaptive noise control in the vicinity of the first frequency region where the noise is the highest, and is generated when this adaptive noise control is performed. Sound increase due to an undesirable sound increase effect in the second frequency region in the vicinity of the first frequency can also be reduced.

  In this case, the first control signal generation means is any one of an adaptive notch filter type control signal generation means, a feedback control type control signal generation means, or an adaptive FIR filter type control signal generation means that operates in the first frequency domain. It can be one. Further, the second control signal generation means receives the first control signal generated one sample before and the addition control signal of the second control signal generated one sample before as the error signal, An adaptive notch filter type control signal generating means operating in the frequency domain can be provided.

  Here, the second control signal generation unit further includes a constant multiplication unit, and a correction signal obtained by multiplying the second control signal generated one sample before by the constant multiplication unit is generated one sample before. The signal added to the addition control signal of the first control signal and the second control signal generated one sample before is input as the error signal, so that the correction amount in the second frequency region is optimized. Can be

  According to the present invention, adaptive noise control is performed in the vicinity of the first frequency region where the vehicle interior noise is greatest to reduce the noise, and the first noise in the vicinity of the first frequency generated when this adaptive noise control is performed. Sound increase due to an undesirable sound increase effect in two frequency regions can also be reduced (sound reduction).

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a block diagram showing a configuration of an active vibration noise control apparatus 200 according to an embodiment of the present invention. In the active vibration and noise control apparatus 200 shown in FIG. 1, the same reference numerals are assigned to the components corresponding to those shown in FIGS. 7 and 9, and the detailed description thereof is omitted.

  The active vibration noise control device 200 shown in FIG. 1 includes a discrete arithmetic processing device 21B having the same configuration as the discrete arithmetic processing device 21A shown in FIG. 9, and generates a first control signal S1. In the discrete arithmetic processing device 21B, the reference cosine wave signal generator 90 having a frequency of 43 [Hz] in the discrete arithmetic processing device 21A is used as the first reference cosine wave signal generator 91, and the filter coefficients A and B are filter coefficients. A1 and B1 are set, and the constant α is set to the constant α1. That is, the discrete arithmetic processing device 21B is a first adaptive notch filter type control signal generating unit that generates the first control signal S1.

  The active vibration noise control device 200 shown in FIG. 1 further includes a discrete arithmetic processing device 202 as second control signal generating means for generating the second control signal S2 and the addition control signal S1 + S2, and this discrete arithmetic processing device. In 202, an addition control signal S1 + S2 of the first control signal S1 and the second control signal S2 generated by itself is input as an error signal e, and the first control signal S1 has a first frequency centered at 43 [Hz]. Sound output means in a second frequency region centered on a frequency of 53 [Hz] that is increased when the sound is reduced in the frequency region (in the vehicle interior noise, for example, the region where the sound pressure is maximum in low-frequency road noise) A second control signal S2 for outputting a canceling sound is generated from the (e.g. microphone) 38, and an addition control signal (control signal) obtained by adding the first control signal S1 and the second control signal S2 by the adder 290. ) And outputs the S1 + S2 to the sound output unit (speaker etc.) 38.

  In this case, the discrete arithmetic processing device 202 is configured as second adaptive notch filter type control signal generating means that operates in the second frequency region of the second control signal S2 in the error signal e2 (e2 = S1 + S2).

  The discrete arithmetic processing device 202 basically has a frequency of 53 [Hz] that is increased when the discrete control processing device 21B reduces the sound in the first frequency region near the frequency 43 [Hz] in the addition control signal S1 + S2. The second reference cosine wave that generates the second reference cosine wave signal (cos) having a frequency of 53 [Hz] is generated because the control signal S2 that generates the canceling sound to be reduced in the second frequency region in the vicinity is generated. A signal generator 92 is provided.

In the discrete arithmetic processing unit 202, a block drawn as Z ^−m is a 90-degree phase shifter 89 that shifts a cosine wave having a frequency of 53 [Hz] by 90 degrees, and the output of the 90-degree phase shifter 89 includes A second reference sine wave signal (sin) is output.

  In addition, in order to facilitate understanding, in the discrete arithmetic processing device 202, compared to the discrete arithmetic processing device 21B, the sound output means 38 to the sound detection means 40 which are constituent elements of the discrete arithmetic processing device 21B. It should be noted that the transfer elements 49, 50, 51, and 52 having characteristics {simulated transfer characteristics (real part) Cr and simulated transfer characteristics (imaginary part) Ci} simulating the transfer characteristics up to the above are unnecessary. The transfer elements 49, 50, 51, 52 include a delay element, which is used to instantaneously minimize the frequency 53 [Hz] component of the second reference signal included in the control signal S1. This is because it is unnecessary.

  FIG. 2 shows a constant α2 by an equivalent transformation of the block diagram in consideration of the fact that the output signals of the adder 277 and the adder 273 are the same second control signal S2 in the discrete arithmetic processing unit 202 in FIG. 3 is a block diagram showing a configuration of a discrete arithmetic processing device 202 that is simplified by connecting an input point of a constant multiplier 274, which is a multiplier of, to an addition point of an adder 277. FIG.

  Hereinafter, the configuration and operation of the active vibration noise control apparatus 200 will be described with reference to FIG.

For ease of understanding, first, it is assumed that the discrete arithmetic processing device 202 is not operating and the value of the control signal S2 supplied from the adder 277 to one input of the adder 290 is a zero value. (S2 = 0)
In this case, in the discrete arithmetic processing device 21 </ b> B, the control signal S <b> 1 for outputting the canceling sound of the vehicle interior noise having the frequency 43 [Hz] of the first reference cosine wave signal is generated at the output of the adder 77.

  That is, in the discrete arithmetic processing unit 21B, multipliers of characteristics {simulated transmission characteristics (real part) Cr and simulated transmission characteristics (imaginary part) Ci} that simulate the transmission characteristics between the sound output means 38 and the sound detection means 40. Only the cosine wave signal having a frequency of 43 [Hz] is temporarily output as sound from the sound output means 38 by the simulation signal generating means 42 composed of the transfer elements 49, 50, 51, 52 and the adders 53, 54. A simulated cosine wave signal Rc simulating the case where only this sound is received by the sound detection means 40 is generated on the output side of the adder 53, and only a sine wave signal having a frequency of 43 [Hz] is temporarily output. A simulated sine wave signal Rs simulating the case where only this sound is received by the sound detection means 40 is generated on the output side of the adder 54.

  Here, for ease of understanding, first, assuming that the constant α1 set in the constant multiplier 74 is α1 = 0 (e = e ′), the adaptive control algorithm computing unit 80 has a simulated cosine wave. Based on the signal Rc and the error signal e, the filter coefficient A1 of the 1-tap adaptive filter 30 is updated so that the error signal e (the square) is minimized by the simulated cosine wave signal Rc (frequency thereof) (A1 = A1). -Μ · e · Rc: μ is the step size parameter, the filter coefficient A1 on the right side of the equal sign is the filter coefficient calculated one sample before, and the filter coefficient A1 on the left side of the equal sign is the updated filter coefficient is there.). At the same time, the adaptive control algorithm computing unit 82 performs one tap based on the simulated sine wave signal Rs and the error signal e so that the error signal e (the square) of the simulated sine wave signal Rs (frequency) is minimized. The filter coefficient B1 of the adaptive filter 32 is updated (B1 = B1−μ · e · Rs: μ is a step size parameter. Similarly, the filter coefficient B1 on the right side of the equal sign is a filter coefficient calculated one sample before. The filter coefficient B1 on the left side of the equal sign is an updated filter coefficient.) As a result, an updated control signal S1 is generated on the output side of the adder 77.

  In this way, the control signal S1 for generating a canceling sound in the vicinity of the frequency 43 [Hz] of the first reference cosine wave signal is generated. When the control signal S1 is generated, the control signal S1 is generated by the constant multiplier 74. The control signal S1 is optimized by setting the constant α1 to be set to an appropriate value instead of a zero value.

  That is, since the simulation signal Ss = A1 · Rc + B1 · Rs is generated on the input side of the constant multiplier 74 (output side of the adder 73), the constant α1 (α1: 0 <α1 <1) is generated in the simulation signal Ss. ) Multiplied by the correction signal α1 · Ss is added to the error signal e to optimize (stabilize) the canceling sound near the frequency 43 [Hz] by the corrected error signal e ′ (e ′ = e + α1 · Ss). Can be achieved. Finally, it is necessary to adjust and optimize a constant α2 (to be described later) in the discrete arithmetic processing device 202 which is a compensation means in the vicinity of the frequency 53 [Hz].

  Therefore, next, the discrete arithmetic processing devices that are subordinately connected to the discrete arithmetic processing device 21B so that the detected sound at the position of the sound detecting means 40 is minimized, in other words, the error signal e is minimized. 202 is also operated simultaneously (S2 ≠ 0).

  The discrete arithmetic processing device 202 is a second reference cosine wave signal generator 92 that generates a reference cosine wave signal (cos) having a frequency of 53 [Hz], and an output signal from the second reference cosine wave signal generator 92. The first one-tap adaptive filter 230 to which the second reference cosine wave signal is input and the second first sine wave signal (sin) which is also the output signal from the 90-degree phase shifter 89 are input. The tap adaptive filter 232, an adder 277 that adds the output signal from the first one-tap adaptive filter 230 and the output signal from the second one-tap adaptive filter 232, and the output signal from the adder 277 An adder 290 that generates an addition control signal S1 + S2 of the second control signal S2 and the first control signal S1, and a second control signal S2 generated one sample before is multiplied by a constant α2 to A constant multiplier 274 for generating a positive signal α2 · S2 and an error signal e2 ′ = S1 + S2 + α2 · S2 = S1 + (1 + α2) S2 obtained by adding the addition control signal S1 + S2 generated one sample before and the correction signal α2 · S2 And an adaptive control algorithm calculator (LMS) 280 and 282 to which the error signal e2 ′ and the second reference cosine wave signal or the second reference sine wave signal are input.

  The discrete arithmetic processing device 202 configured as described above has filter coefficients A2 of the first one-tap adaptive filter 230 and the second one-tap adaptive filter 232 based on the adaptive control algorithms of the adaptive control algorithm calculators 280 and 282, By updating B2, it operates to minimize the error signal e2 ′ = S1 + (1 + α2) S2 (the square).

  Also in this case, the value of the constant α2 (0 <α2 <1) is gradually increased from the zero value to optimize the canceling sound (addition control signal S1 + S2) at the frequency 53 [Hz] of the second reference cosine wave signal. Can be achieved.

  The reason for the optimization can be roughly explained qualitatively. The control signal S1 supplied to one input of the adder 290 includes a canceling sound signal component (silenced signal component) of 43 [Hz] and 53 [Hz]. Hz] is included, but the control signal S2 supplied to the other input of the adder 290 includes only the cancellation sound signal component (silence signal component) of 53 [Hz]. At that time, by adjusting the constant α2, it is possible to optimize (stabilize) the canceling sound near 53 [Hz] included in the addition control signal S1 + S2.

  In this way, by adjusting (tuning) the constant α1 of the constant multiplier 74 and the constant α2 of the constant multiplier 274, the sound pressure near the frequency 43 [Hz] is reduced and the frequency near the frequency 53 [Hz] is reduced. The optimum addition control signal (updated addition control signal) S1 + S2 that suppresses the increase in sound pressure is determined. Of course, even if the constant α2 = 0, the sound pressure in the vicinity of the frequency 53 [Hz] can be reduced by a certain amount.

  FIG. 3A shows low frequency road noise in the vicinity of a frequency of 43 [Hz] by the active vibration noise control apparatus 200 shown in FIG. 1 or FIG. 2 as a result of adjusting the constant α1 and the constant α2 in this manner, and the low frequency. When the road noise is reduced, a post-reduction noise characteristic 96A in which a sound increase (noise) in the vicinity of 53 [Hz] appearing in the vicinity thereof is reduced (sound reduction), and a pre-reduction noise characteristic 94 shown in FIG. 8A. Both are shown. FIG. 3B shows a sensitivity function 98A by the active vibration noise control apparatus 200 in this case.

  In this reduced noise characteristic 96A, the noise near the frequency 43 [Hz] is reduced by about 7 [dB] in sound pressure, and the noise near the frequency 53 [Hz] is increased by several [dB]. Compared with the reduced noise characteristic 96 shown in FIG. 1, the noise in the vicinity of the frequency 53 [Hz] is greatly reduced to about 8 dB. As a result, it can be seen that the peak of the sound pressure is reduced by about 8 [dB] in the post-reduction noise characteristic 96A as a whole. Due to the sound pressure reduction effect (reduced noise characteristic 96A) in a wide frequency range with respect to the low frequency road noise (pre-reduction noise characteristic 94), a very effective silencing effect can be obtained at the occupant's ear position.

  As described above, according to the embodiment described above, the control signal generation means (21B, 202) of the active vibration noise control apparatus 200 has the first frequency 43 [Hz including the maximum portion of the sound pressure in the vehicle interior noise. ] In the area including the discrete arithmetic processing device 21B (first control signal generating means) for generating the first control signal S1 and the discrete arithmetic processing device 202 (second control signal generating means) for generating the second control signal S2. The discrete arithmetic processing unit 202 receives the updated first control signal S1 + S2 generated by inputting the first control signal S1 generated one sample before and the second control signal S2 generated one sample before. Updated to output from the sound output means 38 the canceling sound in the region including the second frequency 53 [Hz] that is increased when the sound is reduced in the region including the first frequency 43 [Hz] by the control signal S1. Second control Generates issue S2, are configured to output a sum control signal S1 + S2 and then updated to the sound output unit 38 as a control signal.

  According to this configuration, the first frequency 43 [Hz] is generated by the discrete arithmetic processing device 21 </ b> B that generates the first control signal S <b> 1 in a region including the first frequency 43 [Hz] including the maximum portion of the sound pressure in the vehicle interior noise. In the region including the second frequency 53 [Hz] that is increased when the sound is reduced in the region including the sound, the canceling sound is output from the sound output unit 38 by the discrete arithmetic processing device 202 that is subordinately connected to the discrete arithmetic processing device 21B. Is generated, and the first control signal S1 and the second control signal S2 are added to output the control signal S1 + S2 to the sound output means 38. Noise can be reduced by adaptive noise control in the vicinity of the first frequency region, and the undesirable sound increase effect in the second frequency region in the vicinity of the first frequency that occurs when the adaptive noise control is performed. The sound can also be effectively reduced.

  In the above-described embodiment, the discrete arithmetic processing device 21B serving as the generation unit of the first control signal S1 has an adaptive notch filter type configuration. However, as another embodiment, the discrete arithmetic processing device 21B is configured as shown in FIG. A certain silencing effect can also be achieved with the configuration of the active vibration noise control device 204 shown in FIG. 4 in place of the feedback control unit (FBC) 10 described with reference to FIG.

  As still another embodiment, the active vibration noise is obtained by replacing the discrete arithmetic processing device 21B, which is the generation unit of the first control signal S1, with an adaptive FIR filter type discrete arithmetic processing unit 21C as shown in FIG. A certain silencing effect can also be achieved with the configuration of the control device 206.

  In the case of the active vibration noise control device 206 of FIG. 5 example, the discrete arithmetic processing unit 21C that generates the first control signal S1 simulates the transfer characteristic between the sound output means 38 and the sound detection means 40 { A transfer element 210 having the above-mentioned simulated transfer characteristic} C ^, an adaptive filter (ADF) 214 which is an adaptive FIR filter, and an adaptive control algorithm calculator (LMS) 212 are provided.

  The input side of the transfer element 210 and the adaptive filter 214 is connected to the output side of the microphone 93 provided in the vehicle interior, particularly at a position where low-frequency road noise in the vicinity of a frequency of 40 [Hz] can be noticeably picked up. The microphone 93 is replaced with a first reference cosine wave signal generator 91 that constitutes the discrete arithmetic processing device 21B.

  In addition, the position in the vehicle where the low frequency road noise near the frequency of 40 [Hz] can be noticeably picked up is described in, for example, Patent Document 1 (Japanese Patent Laid-Open No. 2000-322066) described above. This is a belly portion of the acoustic eigenmode in the front-rear direction of the passenger compartment, for example, near the feet of the front seat, near the center of the roof, and in the trunk room.

  The present invention is not limited to the above-described embodiment, and various modifications can be made based on the description of the specification and the drawings.

It is a block diagram which shows the structure of the active vibration noise control apparatus which concerns on one Embodiment of this invention. It is a block diagram which shows the structure of the active vibration noise control apparatus simplified by applying the equivalent conversion of a block diagram with respect to the block diagram of the active vibration noise control apparatus of the example of FIG. FIG. 3A is a characteristic diagram of low-frequency noise in the vehicle compartment before and after application of the active vibration noise control apparatus according to one embodiment of the present invention. FIG. 3B is an explanatory diagram of a sensitivity function of the active vibration noise control apparatus according to the embodiment of the present invention. It is a block diagram which shows the structure of the active vibration noise control apparatus which concerns on other embodiment of this invention. It is a block diagram which shows the structure of the active vibration noise control apparatus which concerns on further another embodiment of this invention. It is a block diagram which shows the structure of the active vibration noise control apparatus which reduces the low frequency road noise based on a prior art. It is a block diagram which shows the structure of the active noise reduction control apparatus which reduces the engine noise based on a prior art. FIG. 8A is a characteristic diagram of low-frequency rose noise in the passenger compartment. FIG. 8B is a characteristic diagram of low-frequency road noise in the vehicle interior after noise reduction by the active vibration noise control device first devised by the inventors. FIG. 8C is an explanatory diagram showing a sensitivity function of the active vibration noise control device devised first. It is a block diagram which shows the structure of the active vibration noise control apparatus which the inventor first devised.

Explanation of symbols

DESCRIPTION OF SYMBOLS 6 ... Speaker 8, 93 ... Microphone 10 ... Feedback control part (FBC) 20 ... Active noise reduction apparatus 21, 21A, 21B, 202 ... Discrete arithmetic processing unit 38 ... Sound output means 42 ... Simulated signal generation means 74, 274 ... Constant multipliers 80, 82 ... adaptive control algorithm computing unit 88, 89 ... 90 degree phase shifter 91 ... first reference cosine wave signal generator 92 ... second reference cosine wave generator 100, 200, 204, 206 ... active vibration Noise control device

Claims (3)

Based on the control signal, sound detection means for detecting a mixed sound of the vehicle interior noise canceling sound and the vehicle interior noise output from the sound output means, and the output signal of the sound detection means is input to generate the control signal In an active vibration noise control device comprising a control signal generating means for
The control signal generating means
A first control signal generating means for generating a first control signal in a first frequency region including the maximum portion of the sound pressure in the vehicle interior noise;
Second control signal generating means for generating a second control signal,
The second control signal generating means includes
An addition control signal of the first control signal generated one sample before and the second control signal generated one sample before is input, and sound is reduced in the first frequency region by the updated first control signal. The updated second control signal for outputting the canceling sound in the second frequency region that increases when the sound is output from the sound output means is generated, and the updated second control signal and the updated second control signal are generated. An active vibration noise control apparatus, wherein a signal addition control signal is output as the control signal to the sound output means. The active vibration noise control apparatus according to claim 1,
The first control signal generating means includes
Any one of adaptive notch filter type control signal generating means, feedback control type control signal generating means, or adaptive FIR filter type control signal generating means operating in the first frequency domain,
The second control signal generating means includes
An adaptive notch filter type control signal that operates in the second frequency domain by inputting the addition control signal of the first control signal generated one sample before and the second control signal generated one sample before as an error signal. An active vibration noise control device characterized by being a generating means. The active vibration noise control device according to claim 2,
The second control signal generating means includes
Furthermore, a constant multiplying unit is provided, and a correction signal obtained by multiplying the second control signal generated one sample before by the constant multiplying unit by a constant is generated one sample before the first control signal generated one sample ago. A signal obtained by adding the addition control signal of the second control signal to the error signal is input as the error signal.

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