Active vibration and noise control device

Abstract

To accurately determine the presence of disturbance even when a periodic noise component is small, and to stably reduce noise.SOLUTION: A noise control device 100 includes: speakers 12a-12d for outputting canceling sounds to cancel noise; error microphones 13a-13d for generating error signals e from the noise and the canceling sounds; and a control filter for generating canceling sounds y from a reference signal r corresponding to the noise. The noise control device 100 further includes a disturbance determination unit for determining the presence or absence of disturbance using the error signal e. The disturbance determination unit calculates an overall correlation by summing correlation functions between each of the plurality of input reference signals r and the error signal e, and determines the presence or absence of disturbance on the basis of the overall correlation.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an active vibration noise control device. [Background technology]

[0002] A conventional active vibration noise control device includes a noise cancellation output device that outputs a noise cancellation sound to cancel out the noise, a noise signal generation device that generates a noise signal based on the noise, and a control device that controls the noise cancellation output device based on the noise signal. The control device acquires buffer data in which noise signals are accumulated in a time series, divides the buffer data to generate a plurality of divided data, calculates a correlation value of the buffer data based on the plurality of divided data, detects the presence or absence of a disturbance mixed in the buffer data based on the correlation value, and switches control of the noise canceling device depending on the presence or absence of a disturbance mixed in the buffer data (see, for example, patent document). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2023-144502 Summary of the Invention [Problem to be solved by the invention]

[0004] Incidentally, there are cases where the periodic noise component is small (for example, when an electric vehicle or hybrid vehicle is in electric driving mode and there is no engine noise). In such cases, road noise and aerodynamic noise are dominant and the interior noise is a highly random sound, so the autocorrelation is inevitably small. For this reason, even if an attempt is made to determine the presence of disturbances based on a decrease in the correlation value, as in the conventional active vibration noise control system, accurate determination cannot be made. Therefore, with conventional systems, it has been difficult to control the on / off or increase / decrease of noise reduction to reduce interior noise depending on the presence or absence of external disturbances. Furthermore, there is a risk of amplifying the noise, making the noise reduction effect unstable. Therefore, further improvements are needed. The present invention aims to provide an active vibration noise control device that can accurately determine the presence of disturbances and stably reduce noise even when the periodic noise component is small. [Means for solving the problem]

[0005] To solve the above problems, the active vibration noise control device of the present invention includes a speaker that outputs a canceling sound to cancel out the noise, and an error microphone that generates an error signal from the noise and the canceling sound.The active vibration noise control device also includes a control filter that generates the canceling sound from a reference signal corresponding to the noise, and a disturbance determination unit that determines the presence or absence of a disturbance using the error signal.The disturbance determination unit adds up the correlation functions of each of a plurality of input reference signals and the error signal to calculate an overall correlation, and determines the presence or absence of a disturbance based on the overall correlation. [Effects of the Invention]

[0006] According to the present invention, an active vibration noise control device is provided that can accurately determine the presence of a disturbance and stably reduce noise even when the periodic noise component is small. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a schematic side view illustrating the configuration of a vehicle to which an active vibration noise control device according to a first embodiment is applied. [Figure 2] 1 is a schematic plan view of a vehicle to which an active vibration noise control device according to a first embodiment is applied. [Figure 3] FIG. 2 is a block diagram illustrating the function of the active vibration noise control device of the first embodiment using one error microphone. [Figure 4] FIG. 2 is a block diagram showing a configuration in which a plurality of error microphones are used in the active vibration noise control device of the first embodiment. [Figure 5] 5 is a flowchart illustrating control by a disturbance determination unit according to the first embodiment. [Figure 6] 10 is a flowchart illustrating the control by the disturbance determination unit using the air volume of the air conditioner. [Figure 7] 10 is a flowchart illustrating a control process performed by a disturbance determination unit using the open / closed state of a window. [Figure 8] FIG. 10 is a block diagram showing a configuration in which a reference microphone is added to an active vibration noise control device of a second embodiment. [Figure 9] 10 is a flowchart showing how a result of determining whether or not a disturbance is present is used to control a control filter in the active vibration noise control device of the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0008] The following describes embodiments of the present invention with reference to the drawings as appropriate. Identical components are given the same reference numerals, and duplicate explanations will be omitted. In this specification, the "^" (hat) next to various reference numerals indicates an identified value or an estimated value. In the drawings, the "^" is placed above the various reference numerals, but in the main text, it is placed after the various reference numerals. [First embodiment] FIG. 1 shows a vehicle 1 to which an active vibration noise control device (hereinafter also abbreviated as "noise control device" or "ANC-ECU") 100 according to a first embodiment is applied. In the description of the vehicle 1, identical elements are given the same numbers, and duplicate descriptions will be omitted. Furthermore, when describing directions, the descriptions will be based on front, back, left, right, up, and down (x, y, z) as seen by the driver of the vehicle 1. Note that the vehicle width direction and left and right direction are synonymous.

[0009] The noise control device 100 is an ANC (Active Noise Control Device) for reducing noise d generated in the passenger compartment 2 of the vehicle 1. More specifically, the noise control device 100 generates a canceling sound y that is in the opposite phase to the noise d, and causes the generated canceling sound y to interfere with the noise d. In this way, the noise control device 100 can reduce the noise d that is the target for reduction.

[0010] For example, the noise d to be reduced by the noise control device 100 is road noise caused by wheel vibration due to force from the road surface. Note that the noise d to be reduced by the noise control device 100 may be noise other than road noise (for example, drivetrain noise or wind noise caused by vibration of a drive source such as an internal combustion engine or an electric motor).

[0011] 1 includes a plurality of speakers 12a-12d that output a cancellation sound y to cancel out a noise d. The noise control device 100 also includes a plurality of error microphones 13a-13d that generate an error signal e from the noise d and the cancellation sound y.

[0012] The noise control device 100 of the first embodiment also includes a plurality of acceleration sensors 14a to 14d. In the first embodiment, a total of four acceleration sensors 14a to 14d are provided, one for each of the four wheels on the front, rear, left, and right of the vehicle 1. Each acceleration sensor 14a to 14d is configured to detect acceleration in three axial directions, i.e., front, rear, left, right, up, and down (x, y, z), and generate, as reference signals r1 to rN, vibrations transmitted to the vehicle body due to contact between the wheels and the road surface, which is a source of road noise. The reference signals r1 to rN obtained by the acceleration sensors 14a to 14d each have as their main components the vibrations in the x, y, and z directions applied to the vehicle body from each wheel, and do not include components of disturbance factors such as the wind noise of the air conditioner installed in the vehicle 1 or the wind noise entering the passenger compartment 2 when the windows are open.

[0013] 2, the noise control device 100 includes a control filter unit 10 that generates a canceling sound from a reference signal, a disturbance determination unit 130, and a control operation setting unit 140. Reference signals r1 to rN generated by the acceleration sensors 14a to 14d are sent to the control filter unit 10 and the disturbance determination unit 130, respectively. As shown in FIG. 3, the control filter unit 10 of the first embodiment includes N (N=12) control filters 10a to 10n for each channel of the acceleration sensors 14a to 14d.

[0014] Here, the description will be given using one control filter 10a that constitutes the control filter unit 10 of the present invention. The description of the other control filters 10b to 10n is omitted because they are similar to the control filter 10a. 3, the control filter 10a has a noise control section 110 and a sound field learning section 120. The noise control section 110 and the sound field learning section 120 are configured by, for example, a computer having an arithmetic processing device (a processor such as a CPU (Central Processing Unit) or an MPU (Micro Processing Unit)) and a storage device (memory such as a ROM (Read Only Memory) or RAM (Random Access Memory)). In addition, the noise control device 100 may be configured such that the components other than the speakers 12a-12d, the error microphones 13a-13d, and the acceleration sensors 14a-14d, namely the noise control unit 110, the sound field learning unit 120, and the disturbance determination unit 130 or the control operation setting unit 140 described later, are configured as, for example, a single piece of hardware, or may be configured as a unit consisting of multiple pieces of hardware.

[0015] The noise control unit 110 is mainly configured to include a first filter 111 , a secondary path filter unit 112 , and a control update unit 113 . The noise control unit 110 receives reference signals r1 to rN corresponding to the noise d sent from the acceleration sensors 14a to 14d. The reference signals r1 to r12 generated by the acceleration sensors 14a to 14d in the first embodiment are mainly composed of vibration components applied to the vehicle body from the four wheels, and the reference signals r1 to r12 contain almost no disturbance components such as the sound of the air conditioner or the sound of wind entering the vehicle interior 2 when the windows are open.

[0016] The first filter 111 of the first embodiment generates control signals u1 to uN from these reference signals r1 to rN. The first filter 111 of the first embodiment corresponds to, for example, an FIR (Finite Impulse Response) filter. An FIR filter is a type of digital filter, and is a filter whose impulse response has a finite duration. In other words, an FIR filter is a filter whose output signal (impulse response) converges within a finite time when an impulse signal is input. The first filter 111 sends control signals u1 to uN to the speakers 12a to 12d, respectively. Each of the speakers 12a to 12d outputs a canceling sound y using the control signals u1 to uN.

[0017] The secondary path filter unit 112 is configured by a secondary path filter having a filter characteristic C^. The secondary path filter is a filter corresponding to an estimated value of the transfer characteristic C of the cancellation sound y from the speakers 12a-12d to the error microphones 13a-13d. The secondary path filter may be an FIR filter or a SAN (Single Frequency Adaptive Notch) filter, which is a single-tap adaptive filter specialized for periodic noise.

[0018] Furthermore, the control update unit 113 adaptively updates the filter characteristic W of the first filter 111 using an adaptive algorithm such as the LMS algorithm (Least Mean Square Algorithm). Control update unit 113 receives reference signal r obtained by filtering reference signals r1 to rN from acceleration sensors 14a-14d through secondary path filter unit 112, and error signals e1 to eN generated by error microphones 13a-13d. Then, the control update unit 113 adaptively updates the filter characteristics W1 to WN of the first filter 111 using the error signal e so that the reference signal r is minimized.

[0019] As a result, the first filter 111 of each noise control unit 110 filters the respective reference signals r1 to rN using the adaptively updated filter characteristics W1 to WN, and each first filter 111 generates a control signal u that controls the output of the speakers 12a to 12d. Furthermore, the sound field learning unit 120 of the noise control device 100 receives the reference signals r1 to rN sent from the acceleration sensors 14a to 14d. Each sound field learning unit 120 includes a primary path filter unit 121 having a filter characteristic H^ provided for each channel, and a primary path update unit 122. Reference signals r1 to rN are input to the primary path filter unit 121 and the primary path update unit 122 of each sound field learning unit 120, respectively.

[0020] The sound field learning unit 120 also includes a secondary path filter unit 123 having a filter characteristic C^, and a secondary path update unit 124. The control signals u1 to uN generated by the first filter 111 are input to the secondary path filter unit 123 and the secondary path update unit 124 of each sound field learning unit 120.

[0021] The sound field learning unit 120 is also provided with a first polarity inversion unit 125, a second polarity inversion unit 126, and an adder 127. The first polarity inversion unit 125 inverts the polarities of the noise signals d^1 to d^N generated by the primary path filter unit 121 and sends them to the adder 127.

[0022] Furthermore, the second polarity inversion unit 126 inverts the polarities of the cancellation signals y^1 to y^N generated by the secondary path filter unit 123 and sends them to the adder 127. The adder 127 adds the noise signal d^ with the polarity inverted, the cancellation signal y^ with the polarity inverted, and the error signal e generated by the error microphones 13a-13d to generate error signals e1-eN, respectively. The error signals e1-eN are sent to the corresponding primary path update unit 122 and secondary path update unit 124 and used for adaptive updating of the primary path filter unit 121 and secondary path filter unit 123.

[0023] Further, the disturbance determination unit 130 receives the reference signals r1 to rN sent from the acceleration sensors 14a to 14d and the error signal e sent from each of the error microphones 13a to 13d. For example, in the first embodiment, as shown in FIG. 4, noise control devices 100a, 100b... configured similarly to the noise control device 100 shown in FIG. 3 are provided corresponding to the plurality of error microphones 13a, 13b... Each of the noise control devices 100a and 100b is connected to each of the acceleration sensors 14a-14d, a disturbance determination unit 130, and a control operation setting unit 140. Furthermore, each of the noise control devices 100a and 100b is connected to the corresponding speaker 12a or 12b. Note that the error microphones 13c and 13d and the noise control devices corresponding to the error microphones 13c and 13d are not shown in Fig. 4. Similar to the noise control devices 100a and 100b, these noise control devices are connected to the acceleration sensors 14a-14d, the disturbance determination unit 130, the control operation setting unit 140, and the speakers 12c-12d (see Fig. 1).

[0024] For example, in electric vehicles or hybrid vehicles, the noise inside the vehicle compartment 2 is dominated by road noise or aerodynamic noise that has a strong random nature. On the other hand, external disturbance sounds such as the sound of the wind from the air conditioner installed in the vehicle 1 and the sound of the wind entering the passenger compartment 2 when the window is open are also highly random. Even in such a case, the disturbance determination unit 130 needs to distinguish the sound of the disturbance from the noise inside the vehicle compartment 2 and determine whether or not there is a disturbance.

[0025] For this reason, the disturbance determination unit 130 obtains correlation functions (Vc1 to VcN) between each of the multiple input reference signals r1 to rN and the error signal e. Furthermore, the disturbance determination unit 130 adds up the obtained correlation functions (Vc1 to VcN) to calculate the overall correlation (Vcall: also referred to as a correlation value). The disturbance determination unit 130 is configured to determine the presence or absence of a disturbance based on the overall correlation. 4, when there are noise control devices 100a, 100b... corresponding to a plurality of error microphones 13a, 13b..., it is possible to determine whether or not there is a disturbance in the error microphone signal of each noise control device 100a, 100b.... Therefore, it is possible to identify the noise control device (error microphone) containing a disturbance and appropriately stop the output of the noise control device.

[0026] Furthermore, the disturbance determination unit 130 determines the presence or absence of a disturbance based on the overall correlation of the error signals e generated by each of the error microphones 13a, 13b.... At this time, the correlation values ​​of at least one pair of the reference signals r1 to rN can be used as a common correlation value. In this way, when determining whether a disturbance exists using the error signals e generated by each of the error microphones 13a, 13b..., the amount of calculation can be reduced by calculating the correlation of the reference signals using a common value.

[0027] The cross-correlation function is calculated using the convolution operation of two signals as follows: First, we will explain calculation method (A), which is one of the calculation methods performed by the disturbance determination unit 130. In calculation method (A), the disturbance determination unit 130 calculates a cross-correlation function (Vci(t)) between each of the reference signals r1, r2, ... rN and the error signal e using the following equation (1): [Formula 1] JPEG2025154963000002.jpg12123 Here, t is discrete time, n is the current time, N is the size of the signal buffer, and τ is the time difference. The time difference γ is set in advance as a control parameter in consideration of the propagation time of the noise d into the vehicle interior 2.

[0028] Next, the disturbance determination unit 130 adds up the absolute values ​​of the correlation functions (Vc1, Vc2 to VcN) between each of the reference signals r1 to rN obtained by equation (1) and the error signal e, as shown in the following equation (2), to calculate the overall correlation value Vcall(t). [Formula 2] JPEG2025154963000003.jpg16123 As a result, the disturbance determination section 130 obtains the overall correlation value Vcall used to determine whether or not a disturbance exists.

[0029] Next, we will explain the calculation method (B) performed by the disturbance determination unit 130. In the calculation method (A), when there is a correlation between the reference signals, the overall correlation value Vcall may overestimate the correlation between the reference signal r and the error signal e. For this reason, the disturbance determination unit 130 determines the correlation value VcriJ of at least one pair of reference signals among the multiple input reference signals r1 to rN. Then, the disturbance determination unit 130 performs a calculation to remove the correlation value Vcrij of the determined reference signal from the overall correlation. In this way, the overall correlation value is determined so as not to become too large. In calculation method (B), equation (3) is used to perform calculation to remove at least one pair of sum values ​​of the correlation values ​​Vcrij(τ) of the reference signal from the overall correlation value Vcall(t) calculated by equation (2). [Formula 3] JPEG2025154963000004.jpg15123 Here, since the same time difference τ is set for the two signals, τ=0 can be set. For example, if the same vibration input is transmitted to the body of a vehicle 1 from all four wheels, noise d may be generated in the passenger compartment 2 due to the vibration. For example, when vibrations are applied to the left and right wheels in the same vertical (z) direction, the correlation between the reference signals r1, r2 or r3, r4 of the paired acceleration sensors 14a, 14b or 14c, 14d and the noise d inside the vehicle cabin 2 becomes 1 (when the cross-correlation is normalized). At this time, the correlation between the paired reference signals r, for example, the acceleration sensors 14a and 14b or 14c and 14d of the paired left and right wheels, also becomes 1. Therefore, the disturbance determination unit 130 calculates the correlation value Vc(τ) according to the following equation (4). [Formula 4] JPEG2025154963000005.jpg10119 Therefore, as expected, it can be seen that the reference signal r and the error signal e are perfectly correlated signals. Therefore, even if the correlation value Vcall used for determination is calculated by removing the correlation value Vcrij(t) of the reference signal from the overall correlation value Vcall(t), it does not differ significantly and an effective determination of disturbance can be made.

[0030] Next, calculation method (C) will be described. Calculation method (C) can reduce the amount of calculation compared to calculation method (B). In the calculation method (C), the disturbance determination unit 130 calculates the cross-correlation function Vci(t) between each of the reference signals r1, r2, . . . rN and the error signal e using the following equation (5). [Formula 5] JPEG2025154963000006.jpg12119 Here, the channel number of the reference signal for calculating the correlation is specified as a control parameter in the disturbance determination unit 130. For example, the channel number of at least one of the reference signals r1, r2, ... rN having a high correlation with the error signal e indicating the indoor sound may be set in advance.

[0031] Next, the disturbance determination unit 130 adds up the results obtained by equation (5) as shown in the following equation (6) to calculate a correlation value Vcall(τ) that numerically indicates the overall correlation. [Formula 6] JPEG2025154963000007.jpg13119 As a result, in calculation method (C), it is possible to omit the calculation of subtracting the correlation between reference signals from the overall correlation value obtained by adding up the results. In this case, the tendency for the correlation value to decrease due to the inclusion of disturbances remains unchanged. Therefore, the disturbance determination unit 130 can make an effective determination using the overall correlation value Vcalc calculated by equation (6).

[0032] The control operation setting unit 140 receives the presence or absence of a disturbance determined by the disturbance determining unit 130 . The disturbance determination unit 130 uses the presence or absence of the disturbance to set the operation of each of the control filters 10a to 10n. As shown in FIG. 4, in the noise control device 100 of the first embodiment, a plurality of error microphones 13a-13d are distributed and arranged on pairs of headrests (see FIG. 2) on the left and right sides of the front and rear seats in the vehicle interior 2, respectively. The disturbance determination unit 130 calculates the correlation of the error signal e sent from each of the error microphones 13 a-13 d using calculation methods (A) to (C). The disturbance determination unit 130 calculates the overall correlation value by adding up the correlation functions of each of the multiple input reference signals rN and the error signal e. Then, the disturbance determining section 130 determines whether or not there is a disturbance based on the calculated overall correlation value.

[0033] When the disturbance determination unit 130 calculates the overall correlation by adding up the correlation functions of each of the multiple input reference signals r1, etc. and the error signal e, if the reference signal r1, etc. and the error signal e have the same sign, the correlation function can be set to -1. This simplifies the calculation performed by the disturbance determination unit 130 when calculating the overall correlation value Vcall, which is the sum of the correlation functions between each of the multiple input reference signals r1 to rn and the error signal e. Therefore, when performing such a calculation, the disturbance determination unit 130 can determine the overall correlation value Vcall with a small amount of calculation.

[0034] The noise control device 100 of the first embodiment configured in this manner can accurately determine the presence of disturbances even when the periodic noise component is small, and can prevent noise amplification due to control divergence caused by disturbances, thereby reducing noise more stably. Specifically, a plurality of reference signals r1 to rN are input to the respective noise control units 110. If any of the reference signals r1 to rN contains a component indicating a disturbance, the correlation values ​​(Vc1 to VcN) of the correlation functions between these reference signals r1 to rN and the corresponding error signals e1 to eN decrease. The correlation functions thus obtained are then summed to calculate the overall correlation value Vcall. At this time, the overall correlation value Vcall obtained by adding up multiple correlation functions decreases significantly if disturbances are present.

[0035] The first filter 111 can generate a control signal u for controlling the outputs of the speakers 12a-12d based on the overall correlation value Vcall using the adaptively updated filter characteristics W1 to WN. Therefore, when the first filter 111 outputs the generated control signal u to the speakers 12a-12d, each speaker 12a-12d generates a canceling sound y in accordance with the control signal u, thereby effectively reducing the noise d inside the vehicle cabin 2.

[0036] In the noise control device 100 of the first embodiment, the disturbance determination unit 130 receives reference signals r1 to rN sent from the acceleration sensors 14a to 14d and an error signal e sent from each of the error microphones 13a to 13d. The disturbance determination unit 130 calculates correlation values ​​(Vc1 to VcN) using a correlation function between each of the multiple input reference signals r1 to rN and the error signal e. The disturbance determination unit 130 then adds up the calculated correlation values ​​(Vc1 to VcN) to calculate an overall correlation value Vcall. The disturbance determination unit 130 then determines whether or not a disturbance exists based on the overall correlation value Vcall.

[0037] In the flowchart of disturbance determination shown in FIG. 5, in step S10, if the disturbance determination unit 130 determines that the value Vc(t) based on the overall correlation is smaller than a preset first threshold Lt1 and the difference Vc(t)-Vc(t-△) of the values ​​based on the overall correlation is greater than a preset second threshold Lt2 (Yes in step S10), the process proceeds to step S11 and determines that a disturbance has been present. Here, Lt1 is a preset first threshold for the cross-correlation value. Lt2 is a preset second threshold that indicates the rate at which the cross-correlation value increases or decreases. Furthermore, t indicates discrete time, and △ indicates a time interval. Note that the second threshold Lt2 may also be a threshold that indicates the rate at which the cross-correlation value decreases.

[0038] Then, if at least one of the following conditions is met: the value Vc(t) based on the overall correlation value is not smaller than a predetermined first threshold Lt1, or the difference Vc(t)-Vc(t-△) of the values ​​based on the overall correlation is not larger than a predetermined second threshold Lt2 (No in step S10), the disturbance determination unit 130 proceeds to step S12 and determines that no disturbance has been present.

[0039] In this way, in the disturbance determination flowchart shown in FIG. 5, it is determined that a disturbance has been present not only when the overall correlation value is smaller than the first threshold value Lt1, but also when the overall correlation value is increasing or decreasing at a pace equal to or greater than the second threshold value Lt2, or when the overall correlation value is decreasing at a pace equal to or greater than the second threshold value Lt2. This makes it possible to more accurately determine whether or not a disturbance is present, even in cases where the reference periodic noise component is small and the decrease in correlation is originally small, such as in electric vehicles or hybrid vehicles, by using the rapid change in correlation for the judgment. Furthermore, the noise control device 100 of the first embodiment uses reference signals r1 to rN generated by acceleration sensors 14a to 14d. Because the reference signals r1 to rN are vehicle body vibration signals, they do not contain components that could be disturbance factors, such as the sound of air conditioning or the sound of wind entering the vehicle interior 2 when a window is open. Therefore, the disturbance determination unit 130 can accurately determine whether or not the microphone signal is contaminated with disturbance by utilizing the correlation between the reference signals r1 to rN, which are less likely to be contaminated with disturbance due to wind, and the microphone signal, which is more likely to be contaminated with disturbance due to wind.

[0040] The results of the determination of whether or not disturbance has been introduced in steps S11 and S12 can be used together with or alone from the microphone signal, which is the reference signal rN, in the flowchart showing the filter control of the second embodiment shown in Figure 9 to determine whether or not disturbance has been introduced in step S40.

[0041] 6 to 8 shown below are examples of determining the presence or absence of disturbance in the first embodiment, but the results of determining the presence or absence of these disturbances may also be used to control the control filters 10a to 10n in the second embodiment shown in FIG. 9. In the disturbance determination flowchart shown in FIG. 6, in addition to the conditions in the flowchart shown in FIG. 5, the air volume of the air conditioner is also used to determine whether or not a disturbance has been introduced. The first filter 111 determines that a disturbance has occurred when the value Vc(t) based on the overall correlation is smaller than a predetermined first threshold Lt1' and the value of the air conditioner's airflow obtained from the air conditioner blower voltage is larger than a predetermined third threshold Lt3.

[0042] That is, in step S20, if the disturbance determination unit 130 determines that the correlation value Vc(t) based on the overall correlation is smaller than the preset first threshold Lt1 and the difference Vc(t)-Vc(t-△) of the correlation values ​​based on the overall correlation is greater than the preset second threshold Lt2, and in addition, if the air conditioner blower voltage is greater than the preset third threshold Lt3 and the air conditioner is operating (Yes in step S20), the process proceeds to step S21 and determines that a disturbance has occurred.

[0043] Furthermore, even if the disturbance determination unit 130 determines that the correlation value Vc(t) based on the overall correlation is smaller than a preset first threshold Lt1 and the difference Vc(t)-Vc(t-△) of the correlation values ​​based on the overall correlation is greater than a preset second threshold Lt2, if the air conditioner blower voltage is not greater than a preset third threshold Lt3, it determines that the air conditioner is not operating (No in step S20) and proceeds to step S22, determining that no disturbance has occurred. The results of the determination of whether or not disturbance has been introduced in steps S21 and S22 can be used together with or alone from the microphone signal, which is the reference signal rN, in the flowchart showing the filter control of the second embodiment shown in Figure 9 to determine whether or not disturbance has been introduced in step S40.

[0044] Furthermore, in the disturbance determination flowchart shown in FIG. 7, in addition to the conditions in the flowchart shown in FIG. 5, the open / closed state of the window is also used to determine whether or not a disturbance has occurred. The disturbance determination unit 130 uses a window control signal that controls the opening and closing of the window to determine whether there is a disturbance, and determines that there is a disturbance when it detects from the window control signal that the value based on the overall correlation is less than or equal to a predetermined first threshold Lt1' and that the window is in an open state.

[0045] That is, in step S30, if the disturbance determination unit 130 determines that the correlation value Vc(t) based on the overall correlation is below a predetermined first threshold Lt1 and the difference Vc(t)-Vc(t-△) of the correlation values ​​based on the overall correlation is above a predetermined second threshold Lt2, and if the window opening / closing state is "open" (Yes in step S30), the process proceeds to step S31 and determines that a disturbance has been present.

[0046] Furthermore, even if the disturbance determination unit 130 determines that the correlation value Vc(t) based on the overall correlation is below a predetermined first threshold Lt1 and the difference Vc(t)-Vc(t-△) of the correlation values ​​based on the overall correlation is above a predetermined second threshold Lt2, if the window is not "open" but "closed" (No in step S30), the process proceeds to step S32 and determines that no disturbance is present. The results of the determination of whether or not disturbance has been introduced in steps S31 and S32 can be used together with the microphone signal, which is the reference signal rN, or alone to determine whether or not disturbance has been introduced in step S40 in the flowchart showing the filter control of the second embodiment shown in Figure 9. In this way, the disturbance determining section 130 can determine the presence or absence of a disturbance more accurately by calculating the overall correlation value Vcall and then adding a condition that indicates that a disturbance is definitely present. The control operation setting unit 140 of the first embodiment switches the operation of each of the control filters 10a to 10n based on the accurate presence or absence of a disturbance determined by the disturbance determination unit 130, and the first filter 111 can stably reduce noise.

[0047] [Second embodiment] 8 shows an active vibration noise control device (noise control device) 200 of the second embodiment. In the following description, the same reference numerals will be used to designate the same or equivalent parts as those in the first embodiment. The noise control device 200 includes a reference microphone 13e in addition to the configuration of the noise control device 100 of the first embodiment. The reference microphone 13e is provided in the same vehicle interior 2 as the error microphones 13a-13d. The reference microphone 13e is connected to the disturbance determination unit 130 and each of the control filters 10a-10n of the control filter unit 10. In addition, the reference microphone 13e sends a reference signal rN generated from noise inside the vehicle compartment 2 to the disturbance determination unit 130 and each of the control filters 10a-10n. The control filters 10a-10n receive reference signals r1 to rN sent from the acceleration sensors 14a-14d, as well as one reference signal rN, which is the reference signal N of the reference microphone 13e. As a result, the control filters 10a-10n generate a canceling sound y. The control operation setting unit 240 of the second embodiment is configured to instruct the control update unit 113 whether to apply and update the filter characteristics W, C^, and H^ or to stop applying and updating them, depending on the presence or absence of a disturbance determined by the disturbance determination unit 130.

[0048] FIG. 9 is a flowchart showing an example of an operation in which the result of determining whether or not there is a disturbance is used for the control of the control filter unit 10 and reflected in noise control. First, in step S40, a correlation value is calculated using the microphone signal, which is the reference signal rN, or the reference signal r from the acceleration sensor 14a or the like. Next, in step S41, the disturbance determination unit 130 determines whether or not a disturbance has been present. If a disturbance has been present (Yes in step S41), the process proceeds to step S42. If no disturbance has been present (No in step S41), the process proceeds to step S45, where the filter characteristics W, C^, and H^ are updated and the control update unit 113 outputs the adaptive update.

[0049] In step S45, if no disturbance is present in any microphone, the filter characteristics W, MC^, and H^ are updated normally, and a control output is generated using the updated values. As a result, both the application update and the control output of the control channel are performed using the reference signal only when no disturbance component is present. Specifically, when no disturbance is present in any of the microphones, the control operation setting unit 240 generates a control output using the updated values ​​while causing the control update unit 113 to normally update the filter characteristics W, C^, and H^. In this way, when the application update and the control ch are output, a cancellation sound y that does not include disturbance components can be generated, and the noise d inside the vehicle interior 2 is effectively reduced.

[0050] Even when there is a disturbance, it is determined in step S42 whether to use the reference signal as a reference signal. Specifically, the flag indicating whether to use the reference signal of the reference microphone 13e is a control parameter that is set in advance. If it is not to be used as a reference signal (No in step S42), proceed to step S44. If it is to be used as a reference signal (Yes in step S42), the process proceeds to the next step S43, where the update of the filter characteristics W, C^, and H^ is stopped and the output of the corresponding control channel is stopped.

[0051] First, in step S44, if one or more microphones are affected by disturbances, the filter cannot be adaptively updated correctly if the microphones with disturbances are used only as error signals for updating the filter, and therefore the learning of the filter characteristics W, C^, and H^ is stopped. On the other hand, since there is no disturbance in the reference signals r1 to rN for generating the control output, the filter value immediately before the disturbance determination may be switched to a fixed filter to continue outputting the canceling sound.

[0052] Specifically, the control operation setting unit 240 stops updating the filter characteristics W, C^, and H^ and continues outputting using the fixed filter (or the control filter unit 10 having the previous filter characteristic W^). Therefore, in step S44, if a disturbance is present in one or more microphones, and the microphone with the disturbance is used only as an error signal for filter updating, even if adaptive updating of the filter is stopped, output generation can be continued by using the values ​​of the filter characteristics W, C^, H^, etc. immediately before the disturbance determination as a fixed filter.

[0053] In step S43, if there is a disturbance in the reference microphone, both the adaptive update and the control output cannot be controlled correctly, so both the adaptive update and the control output are stopped. Specifically, if a disturbance is included in the detection value of the reference microphone 13e, the control output of the control channel is also stopped along with the output of the adaptive update by the control update unit 113. As a result, in a state where the adaptive update and the control channel output cannot be performed accurately due to a disturbance, both the adaptive update and the control channel output are not performed, and it is possible to avoid inaccurate adaptive update and control channel output that include disturbance components.

[0054] In the noise control device 200 of the second embodiment configured as described above, when a disturbance occurs, learning of the filter characteristics W, C^, and H^ is stopped. On the other hand, since the reference signals r1 to rN sent from the acceleration sensors 14a to 14d are vibration signals of the vehicle body, they are less likely to be mixed with disturbances and are less affected by disturbances. Furthermore, by filtering the reference signal that does not contain any disturbances, the output of the canceling sound can be continued. This makes it possible to prevent the volume of the canceling sound y from being suddenly increased or decreased due to an extreme change in control. Therefore, the noise control device 200 of the second embodiment can reduce noise more stably and improve the quality of noise control.

[0055] The other configurations and effects are the same as those of the first embodiment, so the description will be omitted.

[0056] As described above, the active vibration noise control device of the present invention includes speakers 12a-12d that output a cancellation sound y to cancel out noise, and error microphones 13a-13d that generate an error signal e from the noise d and the cancellation sound y. The active vibration noise control device also includes a first filter 111 that generates a cancellation sound y from a reference signal r that corresponds to the noise d, and a disturbance determination unit 130 that determines the presence or absence of a disturbance using the error signal e. The disturbance determination unit 130 calculates an overall correlation value Vcall by adding together the correlation functions (Vc1 to VcN) of each of the multiple input reference signals r1 to rN and the error signal e, and determines the presence or absence of a disturbance based on the overall correlation value Vcall.

[0057] An active vibration noise control device configured in this manner can accurately determine the presence of a disturbance even when the periodic noise component is small, and can prevent noise amplification due to control divergence caused by the disturbance, thereby reducing noise more stably. Specifically, if each of the multiple input reference signals r1 to rN contains a component indicating a disturbance, the overall correlation value Vcall, which is the sum of multiple correlation functions (Vc1 to VcN) between each of the reference signals r1 to rN and the error signal e, decreases significantly. Therefore, the disturbance determining section 130 can accurately determine the presence or absence of a disturbance by calculating the overall correlation value Vcall.

[0058] Furthermore, for example, as in the noise control device 100 of the first embodiment, multiple acceleration sensors 14a to 14d that detect acceleration in three axes (x, y, and z directions) can be used to obtain reference signals r1 to rN corresponding to the noise d. The reference signals r1 to rN generated by the acceleration sensors 14a to 14d do not contain components of disturbance factors. This allows for more accurate determination of the presence or absence of a disturbance. Furthermore, the noise control device 100 of the first embodiment is provided with a total of four three-axis acceleration sensors 14a to 14d, one on each of the front, rear, left, and right wheels. This allows a total of 12 channels of reference signals r1 to rN (N=12) to be generated, further improving the accuracy of determining the presence or absence of a disturbance.

[0059] Furthermore, the disturbance determination unit 130 finds a correlation value Vcrij of at least one pair of reference signals among the multiple input reference signals r1 to rN, and removes the correlation (correlation value Vcrij) of the found reference signals r1, etc. from the overall correlation value Vcall. That is, if there is a correlation between paired reference signals r1, r2, etc., the overall correlation coefficient (correlation value Vcrij) obtained by adding together the correlation functions (Vc1 to VcN) between reference signals r1 to rN and the error signal becomes large. Therefore, by removing the influence of the correlation between paired reference signals r1, r2, etc., it is possible to prevent the overall correlation from being overestimated.

[0060] For example, in the vehicle 1 of the first embodiment, when vibrations are applied to the left and right wheels in the same vertical (z) direction, the correlation between the reference signals r1, r2 or r3, r4 of the paired acceleration sensors 14a, 14b or 14c, 14d and the noise signal inside the passenger compartment 2 becomes 1 (when the cross-correlation is normalized). In this case, the correlation between a pair of reference signals r, for example, the correlation between acceleration sensors 14a and 14b or 14c and 14d of a pair of left and right wheels, also becomes 1. Therefore, by removing the influence of the correlation between paired reference signals r1, r2, etc., the evaluation of the overall correlation value Vcall can be made more stable.

[0061] A plurality of error microphones 13a-13d are provided, and the disturbance determination unit 130 determines the presence or absence of a disturbance based on the overall correlation from the error signals e generated by each of the error microphones 13a-13d. The disturbance determination unit 130 uses a pair of correlation values ​​Vcrij from the reference signals r1-rN as a common correlation value when making determinations for each of the error microphones 13a-13d. As a result, when the disturbance determination unit 130 determines whether a disturbance has occurred using the error signals e generated by the error microphones 13a-13d, the amount of calculation can be reduced by calculating the correlation between the reference signals r1 to rN using a common value.

[0062] Then, the disturbance determination unit 130 determines that a disturbance is present when the value based on the overall correlation is smaller than a preset first threshold Lt1 and the difference between the values ​​based on the overall correlation is larger than a preset second threshold Lt2. As a result, it is determined that a disturbance has been present not only when the correlation is smaller than the first threshold Lt1 but also when the correlation increases or decreases at a rate greater than a constant (second threshold Lt2).This makes it possible to more accurately determine a disturbance by using the rapid change in correlation for the determination, even when the periodic noise component is small and the decrease in the reference correlation is small.

[0063] The disturbance determination unit 130 also uses an air conditioner blower voltage that controls the air volume of the air conditioner to determine whether a disturbance has occurred. The first filter 111 determines that a disturbance has occurred when the value based on the overall correlation is smaller than a predetermined first threshold Lt1 and the air volume value of the air conditioner obtained from the air conditioner blower voltage is larger than a predetermined third threshold Lt3.

[0064] For example, the disturbance determination unit 130 obtains the value of the airflow rate of the air conditioner from the air conditioner blower voltage, so that erroneous detection of disturbance can be prevented even if the threshold value of the determination condition based on correlation is set loosely.

[0065] Furthermore, the disturbance determination unit 130 uses a window control signal that controls the opening and closing of the window to determine whether there is a disturbance, and determines that there is a disturbance when it detects from the window control signal that the value based on the overall correlation is smaller than a predetermined first threshold Lt1 and that the window is open. By using the fact that the window is open in this way for the judgment, it is possible to prevent erroneous detection of disturbance even if the threshold value of the judgment condition based on correlation is set loosely.

[0066] The active vibration noise control device also includes a control operation setting unit 140 that sets the operation of the control filter unit 10 depending on the presence or absence of a disturbance determined by the disturbance determination unit 130, and a reference microphone 13e that is provided in the same vehicle compartment 2 as the error microphones 13a-13d. The control filter unit 10 can generate the canceling sound y using the detection value of the reference microphone 13e as a reference signal rN. Furthermore, when the disturbance determination unit 130 determines that there is a disturbance, the control operation setting unit 140 stops generating the canceling sound y using the detection value of the reference microphone 13e. As a result, if there is a disturbance in the space of the vehicle interior 2, the generation of the canceling sound y can be stopped because the detected value of the reference microphone 13e may also include the disturbance, thereby preventing the unpleasant canceling sound y from being output. Also, for example, if there is a possibility that the detection value of the reference microphone 13e may also contain disturbances, the detection value of the reference microphone 13e may not be used as the reference signal rN, but may be used as one of the error signals that are determined to be free of disturbances.

[0067] When the disturbance determination unit 130 determines that there is a disturbance, the control operation setting unit 140 stops learning by the control filter unit 10 and switches to the control filter unit 10 before learning was stopped or to a fixed filter unrelated to learning, thereby continuing to output the cancellation sound, and also switches the reference signal from the detection value of the reference microphone to the detection value of the acceleration sensor. In other words, when the reference microphone 13e is not used, the reference signal rN including the reference signals r1 to rN sent from the acceleration sensors 14a to 14d is not affected much by external disturbances. Therefore, when an external disturbance occurs, the learning of the control filter unit 10 is stopped. Then, the control filter unit 10 before the learning was stopped, a fixed filter unrelated to the learning, or reference signals r1 to rN sent from the acceleration sensors 14a to 14d is switched to continue outputting the canceling sound. This makes it possible to prevent sudden increases or decreases in volume due to extreme control changes, thereby maintaining the noise reduction effect with improved noise control quality.

[0068] Furthermore, in the embodiment, the correlation function indicating the correlation is set to 1 when the reference signal and the error signal have the same sign, and when the reference signal and the error signal do not have the same sign, the correlation function is set to -1 in the embodiment, and the correlation functions between each of the multiple input reference signals and the error signal are added together to obtain the overall correlation. By simplifying the calculation of the entire correlation function in this way, the amount of calculation can be reduced. Specifically, when the reference signal r and the error signal e have the same sign, the correlation function is set to a predetermined value, for example, 1 in this embodiment. When the reference signal r and the error signal e do not have the same sign, the correlation function is set to a value with the same absolute value as the predetermined value but with an opposite sign, for example, the correlation coefficient is set to -1 in this embodiment. The disturbance determination unit 130 then simply obtains the correlation function by adding together the correlation functions of the multiple input reference signals rN and the error signal e. This makes it possible to determine the presence or absence of a disturbance with a small amount of calculation, either in addition to or instead of a convolution operation. This simplifies the calculation compared to when the entire correlation function is calculated using only convolution operations, reducing the amount of calculation required, making it suitable for use in active vibration noise control that requires quick response, such as in a moving vehicle 1. In this way, the active vibration noise control device of the present invention exhibits practically beneficial effects, such as being able to accurately determine the presence of disturbances and stably reduce noise even when the periodic noise component is small.

[0069] The present invention is not limited to the above-described embodiments, and various modifications are possible. The above-described embodiments are provided as examples to facilitate understanding of the present invention, and are not necessarily limited to those including all of the configurations described. Furthermore, it is possible to replace part of the configuration of one embodiment with the configuration of another embodiment, or to add the configuration of another embodiment to the configuration of one embodiment. Furthermore, it is possible to delete part of the configuration of each embodiment, or to add or replace other configurations. Possible modifications of the above-described embodiments include, for example, the following.

[0070] For example, in the first embodiment, the noise control devices may be configured with only the noise control devices 100a and 100b, and may be connected only to the speakers 12a and 12b, as shown in Fig. 4. In other words, the present invention is not particularly limited in the number of noise control devices 100, speakers 12a, and error microphones 13a.

[0071] The first filter 111 may determine that a disturbance has occurred when the value based on the overall correlation is smaller than a predetermined first threshold Lt1 and the airflow rate value of the air conditioner is larger than a predetermined third threshold Lt3. That is, whether or not the difference between the values ​​based on the overall correlation is larger than a predetermined second threshold Lt2 does not have to be used to determine whether or not a disturbance has occurred in step S20 of the flowchart shown in Fig. 6. Furthermore, in the flowchart shown in Fig. 7, whether or not the difference between the values ​​based on the overall correlation is larger than a predetermined second threshold Lt2 does not have to be used to determine whether or not a disturbance has occurred in step S30.

[0072] In addition, the first embodiment has been described with reference to the results of determining whether or not there is a disturbance shown in FIGS. 6 to 8 being used to control the control filter of the second embodiment shown in FIG. 9, but the present invention is not limited to this. For example, the results of determining whether or not there is a disturbance shown in FIGS. 6 to 8 in the first embodiment may be used to control another control filter that does not use the reference microphone 13e.

[0073] Furthermore, in the second embodiment, the control filter is controlled mainly using the determination results of the presence or absence of disturbance shown in Fig. 6 to Fig. 8, but the present invention is not limited to this. For example, a determination result obtained by a determination method other than the method of determining the presence or absence of disturbance in the first embodiment may be used. That is, the second embodiment may be configured to stop the generation of the canceling sound based on the detection value of the reference microphone 13e when it is determined that there is a disturbance by a disturbance determination unit having another configuration.

[0074] Furthermore, the disturbance determination unit that determines the presence or absence of a disturbance using the error signal does not have to use the reference signals r1 to rN corresponding to the noise signals sent from the acceleration sensors 14a to 14d as in the first and second embodiments. For example, various sensors such as stroke sensors and pressure sensors that detect suspension behavior may be used, and any sensor other than the acceleration sensors 14a to 14d may be used as long as it can generate a reference signal corresponding to noise. In other words, it is sufficient if the disturbance determination unit can determine whether or not a disturbance is present using the reference signal corresponding to the noise generated by these, and there are no particular limitations on the number and shape of the components that generate the reference signal and the method for generating the reference signal. [Explanation of symbols]

[0075] 10 Control filter section 10a-10N control filter 12a-12d Speakers 13a-13d Error microphone 130 Disturbance judgment unit

Claims

1. a speaker that outputs a canceling sound to cancel out noise; an error microphone for generating an error signal from the noise and the cancellation sound; a control filter that generates the cancellation sound from a reference signal corresponding to the noise; a disturbance determination unit that determines whether or not a disturbance exists using the error signal, the disturbance determination unit calculates an overall correlation by adding together correlation functions of the plurality of input reference signals and the error signal; An active vibration noise control device characterized in that it determines whether or not there is a disturbance based on the overall correlation.

2. the disturbance determination unit determines a correlation between at least one pair of the reference signals among the plurality of reference signals input; 2. The active vibration noise control system according to claim 1, wherein the correlation of the reference signal determined from the overall correlation is removed.

3. A plurality of the error microphones are provided, the disturbance determination unit determines the presence or absence of a disturbance based on the overall correlation from the error signals generated by the error microphones, 3. The active vibration noise control system according to claim 2, wherein a pair of correlation values ​​of said reference signals are used as a common correlation value when determining each of said error microphones.

4. 2. The active vibration noise control device according to claim 1, wherein the disturbance determination unit determines that a disturbance is present when the value based on the overall correlation is smaller than a predetermined first threshold value and the difference between the values ​​based on the overall correlation is larger than a predetermined second threshold value.

5. The disturbance determination unit uses an air conditioner blower voltage that controls an air volume of an air conditioner to determine whether a disturbance has occurred, and 2. The active vibration noise control device according to claim 1, wherein the control filter determines that a disturbance has occurred when the value based on the overall correlation is smaller than a predetermined first threshold value and the value of the airflow rate of the air conditioner obtained from the air conditioner blower voltage is larger than a predetermined third threshold value.

6. The disturbance determination unit uses a window control signal that controls opening and closing of a window to determine whether a disturbance has occurred, and 2. The active vibration noise control device according to claim 1, wherein when the value based on the overall correlation is smaller than a predetermined first threshold value and the window control signal detects that the window is open, it is determined that a disturbance has occurred.

7. a control operation setting unit that sets the operation of the control filter depending on the presence or absence of a disturbance determined by the disturbance determination unit; a reference microphone provided in the same vehicle cabin as the error microphone; the control filter is capable of generating the cancellation sound using a detection value of the reference microphone as the reference signal; 2. The active vibration noise control device according to claim 1, wherein the control operation setting unit stops generating the canceling sound based on the detection value of the reference microphone when the disturbance determination unit determines that a disturbance exists.

8. 8. The active vibration noise control device according to claim 7, wherein, when the disturbance determination unit determines that a disturbance exists, the control operation setting unit stops learning by the control filter and switches to the control filter before the learning was stopped or to a fixed filter unrelated to learning, thereby continuing to output the canceling sound, and switches the reference signal from the detection value of a reference microphone to the detection value of an acceleration sensor.

9. a speaker that outputs a canceling sound to cancel out noise; an error microphone for generating an error signal from the noise and the cancellation sound; a control filter that generates the cancellation sound from a reference signal corresponding to the noise; a disturbance determination unit that determines whether or not a disturbance exists using the error signal, the disturbance determination unit, when calculating an overall correlation by adding up correlation functions between each of the plurality of input reference signals and the error signal, sets the correlation function to a predetermined numerical value if the reference signal and the error signal have the same sign, and sets the correlation function to a value with the same absolute value as the predetermined numerical value but with an opposite sign if the reference signal and the error signal do not have the same sign, and determines the presence or absence of a disturbance based on the overall correlation function obtained by adding up correlation functions between each of the plurality of input reference signals and the error signal.

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