Active noise control device and vehicle

Abstract

An active noise control device and a vehicle. The active noise control device (10) comprises: a reference signal generating unit (28X-28Z) generating a reference signal (sx-sz) corresponding to a resonance frequency (f0x-f0z) of a vibration sensor (18); a first adaptive filter (30X-30Z) generating a sensor resonance simulation signal (mx-mz) simulating a signal obtained when the vibration sensor resonates by filtering the reference signal; a calculation unit (32X-32Z) calculating a second reference signal (rx2-rz2) which is a difference between a first reference signal (rx1-rz1) obtained by the vibration sensor and the sensor resonance simulation signal; and a second adaptive filter (36X-36Z) generating a control signal (u0x-u0z) by filtering the second reference signal. Thus, noise can be reduced well.

Description

Technical Field

[0001] The present invention relates to an active noise control device and a vehicle. Background Art

[0002] Japanese Patent Publication No. 2006-335136 discloses an active vibration noise control device, which includes a sensor, a noise calculation unit, and a controller. The sensor measures the vibration of the vehicle body. The noise calculation unit calculates the noise in the vehicle cabin based on the vibration of the vehicle body. The controller controls the active unit that generates the control sound based on the noise in the vehicle cabin. Summary of the invention

[0003] However, in Japanese Patent Application Laid-Open No. 2006-335136, it is not necessarily possible to satisfactorily reduce noise when resonating with the sensor.

[0004] An object of the present invention is to provide an active noise control device and a vehicle capable of effectively reducing noise.

[0005] An active noise control device according to one embodiment of the present invention causes an actuator to output a canceling sound based on a control signal to reduce noise in a vehicle cabin. The active noise control device includes a reference signal generating unit, a first adaptive filter, a computing unit, and a second adaptive filter, wherein the reference signal generating unit generates a reference signal corresponding to a resonance frequency of a vibration sensor equipped on the vehicle; the first adaptive filter generates a sensor resonance simulation signal by filtering the reference signal, the sensor resonance simulation signal being a signal obtained by simulating a signal obtained when the vibration sensor resonates; the computing unit calculates a second reference signal, the second reference signal being a difference between a first reference signal obtained by the vibration sensor and the sensor resonance simulation signal; and the second adaptive filter generates the control signal by filtering the second reference signal differently from the filtering performed by the first adaptive filter.

[0006] A vehicle according to another aspect of the present invention includes the above-described active noise control device.

[0007] According to the present invention, an active noise control device and a vehicle capable of satisfactorily reducing noise can be provided.

[0008] The above-mentioned objects, features and advantages will be easily understood through the following description of the embodiments with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1It is a diagram showing an overview of active noise control.

[0010] Figure 2 It is a block diagram showing a part of a vehicle including the active noise control device according to the first embodiment.

[0011] Figure 3 It is a block diagram showing a part of a vehicle including an active noise control device according to a second embodiment.

[0012] Figure 4 It is a block diagram showing a part of a vehicle including an active noise control device according to a third embodiment. DETAILED DESCRIPTION

[0013] The active noise control device and the vehicle of the present invention will be described in detail below with reference to the preferred embodiments and the accompanying drawings.

[0014] [First embodiment]

[0015] use Figure 1 and Figure 2 An active noise control device and a vehicle according to a first embodiment will be described. Figure 1 It is a diagram showing an overview of active noise control.

[0016] The active noise control device 10 causes the actuator 16 to output a canceling sound for reducing noise (vibration noise) in the cabin 14 of the vehicle 12 .

[0017] The noise in the vehicle cabin 14 may include, for example, road noise, etc. The road noise is caused by the wheels vibrating due to the force from the road surface, and the vibration of the wheels is transmitted to the vehicle body through the suspension and then to the passengers in the vehicle cabin 14 .

[0018] The vehicle 12 has a vibration sensor 18 that detects vibration of the vehicle 12. A signal r1 detected by the vibration sensor 18 is provided to the active noise control device 10. That is, a signal indicating vibration is provided to the active noise control device 10.

[0019] A microphone 20 is also provided in the vehicle cabin 14. The microphone 20 detects residual noise (cancellation error noise) generated by interference between the cancelling sound output by the actuator 16 and the noise. The residual noise detected by the microphone 20 is provided to the active noise control device 10. That is, the error signal e detected by the microphone 20 is provided to the active noise control device 10.

[0020] The active noise control device 10 generates a control signal u for causing the actuator 16 to output a cancelling sound based on the signal r1 detected by the vibration sensor 18 and the error signal e detected by the microphone 20. More specifically, the active noise control device 10 generates the control signal u that minimizes the error signal e detected by the microphone 20. The actuator 16 outputs the cancelling sound based on the control signal u that minimizes the error signal e detected by the microphone 20, and thus the noise in the vehicle cabin 14 can be well canceled by the cancelling sound. In this way, the active noise control device 10 can reduce the noise transmitted to the occupants in the vehicle cabin 14.

[0021] In addition, resonance occurs in the vibration sensor 18. The signal r1 obtained by the resonant vibration sensor 18 contains resonance noise. When the above-mentioned cancellation sound is generated only based on the signal r1 containing large resonance noise, the noise in the vehicle cabin 14 may not be cancelled well by the cancellation sound. Although it is also conceivable to use a low-pass filter to remove such resonance noise, when a low-pass filter is used, since a signal delay occurs, the noise control effect is reduced. The inventor of the present application has conceived the following active noise control device 10 after intensive research.

[0022] Figure 2 1 is a block diagram showing a part of a vehicle including the active noise control device according to the present embodiment.

[0023] like Figure 2 As shown, the active noise control device 10 includes a reference signal generating unit 22 and a control signal generating unit 24 .

[0024] The reference signal generating unit 22 includes resonance frequency storage units 26X to 26Z, reference signal generating units 28X to 28Z, first adaptive filters 30X to 30Z, calculation units 32X to 32Z, and first filter coefficient updating units 34X to 34Z.

[0025] The control signal generating unit 24 includes second adaptive filters 36X, 36Y, and 36Z, acoustic characteristic filters 38X, 38Y, and 38Z, second filter coefficient updating units 40X, 40Y, and 40Z, and a computing unit 42 .

[0026] The active noise control device 10 has a computing device (computation processing device) not shown in the figure. The computing device can be composed of a processor such as a CPU (Central Processing Unit) and a DSP (Digital Signal Processor), but is not limited to this. The computing device can include a direct digital frequency synthesizer (DDS: Direct Digital Synthesizer), a digitally controlled oscillator (DCO: Digitally Controlled Oscillator), etc. In addition, the computing device can include an ASIC (Application Specific Integrated Circuit), an FPGA (Field-Programmable Gate Array, Field Programmable Gate Array), etc.

[0027] The active noise control device 10 has a storage device not shown in the figure. The storage device can be composed of a volatile memory not shown in the figure and a non-volatile memory not shown in the figure. As a volatile memory, for example, a RAM (Random Access Memory) can be cited. As a non-volatile memory, for example, a ROM (Read-Only Memory), a flash memory, etc. can be cited. Programs, tables, maps, etc. can be stored in, for example, a non-volatile memory.

[0028] The resonance frequency storage units 26X to 26Z are provided in a storage device. The reference signal generation units 28X to 28Z, the first adaptive filters 30X to 30X, the calculation units 32X to 32Z, and the first filter coefficient update units 34X to 34Z can be realized by the calculation unit executing a program stored in the storage device.

[0029] The second adaptive filters 36X, 36Y, 36Z, the acoustic characteristic filters 38X, 38Y, 38Z, the second filter coefficient updating units 40X, 40Y, 40Z, and the operation unit 42 can be realized by executing a program stored in a storage device by an operation device.

[0030] The vehicle 12 can include a vibration sensor 18, specifically, an acceleration sensor. More specifically, for example, a three-axis acceleration sensor can be used as the vibration sensor 18. The three axes are an X-axis, a Y-axis, and a Z-axis. The vibration in the X-axis direction detected by the vibration sensor 18 is provided to the active noise control device 10 as a first reference signal rx1. The vibration in the Y-axis direction detected by the vibration sensor 18 is provided to the active noise control device 10 as a first reference signal ry1. The vibration in the Z-axis direction detected by the vibration sensor 18 is provided to the active noise control device 10 as a first reference signal rz1. When describing the first reference signal as a whole, the symbol r1 is used. When describing each first reference signal, the symbols rx1, ry1, and rz1 are used.

[0031] As described above, in the carriage 14 (refer to Figure 1 ) has a microphone 20, which is used to detect the residual noise generated by the interference between the noise and the canceling sound. That is, the microphone 20 for detecting the error signal e is provided in the vehicle compartment 14.

[0032] As described above, the carriage 14 (see Figure 1 ) has an actuator 16 that outputs a canceling sound based on a control signal u. As the actuator 16, a speaker can be cited, for example.

[0033] As described above, the reference signal generating unit 22 includes resonance frequency storage units (resonance frequency storage units) 26X, 26Y, and 26Z. The resonance frequency storage units 26X, 26Y, and 26Z store resonance frequency information indicating the resonance frequencies f0x, f0y, and f0z of the vibration sensor 18. The resonance frequency storage unit 26X stores the resonance frequency f0x of the vibration sensor 18 in the X-axis direction. The resonance frequency storage unit 26Y stores the resonance frequency f0y of the vibration sensor 18 in the Y-axis direction. The resonance frequency storage unit 26Z stores the resonance frequency f0z of the vibration sensor 18 in the Z-axis direction. When describing the resonance frequency storage unit as a whole, the mark 26 is used. When describing each resonance frequency storage unit, the marks 26X, 26Y, and 26Z are used. When describing the resonance frequency as a whole, the mark f0 is used. When describing each resonance frequency, the marks f0x, f0y, and f0z are used.

[0034] As described above, the reference signal generating unit 22 includes reference signal generating units 28X, 28Y, and 28Z. The reference signal generating unit 28X generates a reference signal sx corresponding to the resonance frequency f0x of the vibration sensor 18 in the X-axis direction based on the resonance frequency information stored in the resonance frequency storage unit 26X. The reference signal generating unit 28Y generates a reference signal sy corresponding to the resonance frequency f0y of the vibration sensor 18 in the Y-axis direction based on the resonance frequency information stored in the resonance frequency storage unit 26Y. The reference signal generating unit 28Z generates a reference signal sz corresponding to the resonance frequency f0z of the vibration sensor 18 in the Z-axis direction based on the resonance frequency information stored in the resonance frequency storage unit 26Z. When describing the reference signal generating unit as a whole, the mark 28 is used. When describing each reference signal generating unit, the marks 28X, 28Y, and 28Z are used. When describing the reference signal as a whole, the mark s is used. When describing each reference signal, the marks sx, sy, and sz are used. The reference signal generating unit 28 can be realized by a direct digital frequency synthesizer, a digitally controlled oscillator, etc., but is not limited thereto.

[0035] As described above, the reference signal generation unit 22 includes the first adaptive filters 30X, 30Y, and 30Z. The first adaptive filter 30X generates the sensor resonance simulation signal mx by filtering the reference signal sx, which is a signal generated by simulating a signal obtained when the vibration sensor 18 resonates in the X-axis direction. The first adaptive filter 30Y generates the sensor resonance simulation signal my by filtering the reference signal sy, which is a signal generated by simulating a signal obtained when the vibration sensor 18 resonates in the Y-axis direction. The first adaptive filter 30Z generates the sensor resonance simulation signal mz by filtering the reference signal sz, which is a signal generated by simulating a signal obtained when the vibration sensor 18 resonates in the Z-axis direction. The symbol 30 is used when describing the first adaptive filter as a whole, and the symbols 30X, 30Y, and 30Z are used when describing each of the first adaptive filters. The symbol m is used when describing the sensor resonance simulation signal as a whole. The symbols mx, my, and mz are used when describing each of the sensor resonance simulation signals. As the first adaptive filter 30, for example, a notch filter can be used. As the notch filter, for example, a SAN (Single-frequency Adaptive Notch) filter can be cited, but it is not limited thereto. The reason for using a notch filter as the first adaptive filter 30 is that, compared with a low-pass filter, the notch filter has the advantage of a short delay time. The frequency (notch frequency) blocked by the first adaptive filter 30 is the resonance frequency f0. As described later, the filter coefficients Wrx, Wry, and Wrz of the first adaptive filters 30X, 30Y, and 30Z can be updated by the first filter coefficient update unit 34X, 34Y, and 34Z. When describing the filter coefficient as a whole, the mark Wr is used. When describing each filter coefficient, the marks Wrx, Wry, and Wrz are used. When the magnitude of the component of the resonance frequency f0 in the first reference signal r1 is relatively large, the filter coefficient Wr of the first adaptive filter 30 can be set in such a way that the attenuation of the component of the resonance frequency f0 in the first adaptive filter 30 is relatively small. On the other hand, when the resonance frequency f0 component in the first reference signal r1 is relatively small, the filter coefficient Wr of the first adaptive filter 30 can be set so that the attenuation amount of the resonance frequency f0 component in the first adaptive filter 30 is relatively large.

[0036] In addition, the first adaptive filter 30 is not limited to a notch filter. The first adaptive filter 30 can also be configured by a bandpass filter or the like. When a bandpass filter is used as the first adaptive filter 30, the filter coefficient Wr of the first adaptive filter 30 can also be set in the following manner. That is, when the magnitude of the component of the resonance frequency f0 in the first reference signal r1 is relatively large, the filter coefficient Wr in the first adaptive filter 30 can be set in such a manner that the attenuation amount of the component of the resonance frequency f0 in the first adaptive filter 30 is relatively small. On the other hand, when the magnitude of the component of the resonance frequency f0 in the first reference signal r1 is relatively small, the filter coefficient Wr in the first adaptive filter 30 can be set in such a manner that the attenuation amount of the component of the resonance frequency f0 in the first adaptive filter 30 is relatively large.

[0037] As described above, the reference signal generating unit 22 includes the operation units 32X, 32Y, and 32Z. The operation unit 32X calculates the second reference signal rx2, which is the difference between the first reference signal rx1 acquired by the vibration sensor 18 and the sensor resonance simulation signal mx. More specifically, the operation unit (subtractor) 32X generates the second reference signal rx2 by subtracting the sensor resonance simulation signal mx from the first reference signal rx1 acquired by the vibration sensor 18. The operation unit 32Y calculates the second reference signal ry2, which is the difference between the first reference signal ry1 acquired by the vibration sensor 18 and the sensor resonance simulation signal my. More specifically, the operation unit (subtractor) 32Y generates the second reference signal ry2 by subtracting the sensor resonance simulation signal my from the first reference signal ry1 acquired by the vibration sensor 18. The operation unit 32Z calculates the second reference signal rz2, which is the difference between the first reference signal rz1 acquired by the vibration sensor 18 and the sensor resonance simulation signal mz. More specifically, the operation unit (subtractor) 32Z generates the second reference signal rz2 by subtracting the sensor resonance analog signal mz from the first reference signal rz1 acquired by the vibration sensor 18. When describing the operation unit as a whole, the symbol 32 is used. When describing each operation unit, the symbols 32X, 32Y, and 32Z are used. When describing the second reference signal as a whole, the symbol r2 is used. When describing each second reference signal, the symbols rx2, ry2, and rz2 are used.

[0038] As described above, the reference signal generating unit 22 includes the first filter coefficient updating units 34X, 34Y, and 34Z. The first filter coefficient updating unit 34X updates the filter coefficient Wrx in the first adaptive filter 30X so that the magnitude of the component of the resonance frequency fOx of the vibration sensor 18 in the X-axis direction is minimized in the second reference signal rx2. The first filter coefficient updating unit 34Y updates the filter coefficient Wry of the first adaptive filter 30Y so that the magnitude of the component of the resonance frequency fOy of the vibration sensor 18 in the Y-axis direction is minimized in the second reference signal ry2. The first filter coefficient updating unit 34Z updates the filter coefficient Wrz in the first adaptive filter 30Z so that the magnitude of the component of the resonance frequency f0z of the vibration sensor 18 in the Z-axis direction is minimized in the second reference signal rz2. The reference 34 is used to describe the first filter coefficient updating unit as a whole. The reference 34X, 34Y, and 34Z are used to describe each of the first filter coefficient updating units. When updating the filter coefficient Wr, for example, an LMS (Least Mean Square) algorithm can be used, but the invention is not limited thereto.

[0039] For example, the update of the filter coefficient Wr by the first filter coefficient update unit 34 can be performed as follows.

[0040] The following equation (1) holds true between the first reference signal r1, the second reference signal r2, and the reference signal s.

[0041] r2=r1-Wr·s…(1)

[0042] The reference signal s is a signal corresponding to the resonance frequency f0 of the vibration sensor 18 and is expressed by the following equation (2).

[0043] s=cos(2·π·f0·t)+i·sin(2·π·f0·t)…(2)

[0044] The first reference signal r1 is composed of a component having the same frequency as that of the reference signal s and a component q having a frequency different from that of the reference signal s. Therefore, the first reference signal r1 is expressed by the following equation (3).

[0045] r1=A·s+q…(3)

[0046] The first filter coefficient updating unit 34 obtains the filter coefficient Wr that minimizes the square error as follows: That is, the first filter coefficient updating unit 34 obtains the filter coefficient Wr that minimizes the square of the second reference signal r2.

[0047] |r2| 2 →min

[0048] The fact that the square of the second reference signal r2 is minimized means that the magnitude of the component of the resonance frequency f0 of the vibration sensor 18 is minimized in the second reference signal r2.

[0049] |r2| 2 It is a quadratic function of the filter coefficient Wr.

[0050] In addition, when the relationship of the following equation (4) holds, the filter coefficient Wr of the first adaptive filter 30 is set to Wreso.

[0051]

[0052] When Wr>Wreso, it is as shown in the following formula (5).

[0053]

[0054] In addition, Wreso corresponds to the amplitude of the component of the resonance frequency f0 of the vibration sensor 18 .

[0055] On the other hand, when Wr<Wreso, it is as shown in the following formula (6).

[0056]

[0057] Furthermore, let the filter coefficient of the first adaptive filter 30 before updating be Wr (n) When the filter coefficient Wr of the first adaptive filter 30 is updated (n+1) It is expressed by the following formula (7).

[0058]

[0059] α and μ are step size parameters. In addition, μ and α have the following relationship (8).

[0060] μ=2·α…(8)

[0061] Thus, in the present embodiment, the filter coefficient Wr of the first adaptive filter 30 is updated in such a manner that the magnitude of the component of the resonance frequency f0 of the vibration sensor 18 is minimized in the second reference signal r2. Therefore, according to the present embodiment, the magnitude of the component of the resonance frequency f0 of the vibration sensor 18 is sufficiently reduced in the second reference signal r2, whether when the resonance frequency f0 changes or when the magnitude of the component of the resonance frequency f0 changes. Therefore, according to the present embodiment, a good second reference signal r2 corresponding to the vibration of the vehicle 12 can be obtained.

[0062] As described above, the control signal generating unit 24 includes second adaptive filters 36X, 36Y, and 36Z. The second adaptive filter 36X generates a control signal u0x by performing a filtering process different from the filtering process performed by the first adaptive filter 30X on the second reference signal rx2. The second adaptive filter 36Y generates a control signal u0y by performing a filtering process different from the filtering process performed by the first adaptive filter 30Y on the second reference signal ry2. The second adaptive filter 36Z generates a control signal u0z by performing a filtering process different from the filtering process performed by the first adaptive filter 30Z on the second reference signal rz2. When describing the second adaptive filter as a whole, the mark 36 is used. When describing each second adaptive filter, the marks 36X, 36Y, and 36Z are used. When describing the control signal as a whole, the mark u0 is used. When describing each control signal, the marks u0x, u0y, and u0z are used. For example, a FIR (Finite Impulse Response) filter or the like can be used as the second adaptive filter 36, but it is not limited to this. As will be described later, the filter coefficients of the second adaptive filters 36X, 36Y, and 36Z are updated by second filter coefficient updaters 40X, 40Y, and 40Z. The FIR filter generates the control signal u0 by performing a convolution operation on the second reference signal r2.

[0063] As described above, the control signal generation unit 24 includes acoustic characteristic filters 38X, 38Y, and 38Z. The acoustic characteristic filter 38X corrects the second reference signal rx2 by performing a filtering process corresponding to the acoustic characteristic (transfer characteristic) from the actuator 16 to the microphone 20 on the second reference signal rx2. The acoustic characteristic filter 38Y corrects the second reference signal ry2 by performing a filtering process corresponding to the acoustic characteristic from the actuator 16 to the microphone 20 on the second reference signal ry2. The acoustic characteristic filter 38Z corrects the second reference signal rz2 by performing a filtering process corresponding to the acoustic characteristic from the actuator 16 to the microphone 20 on the second reference signal rz2. The acoustic characteristic from the actuator 16 to the microphone 20 is acquired in advance. That is, the transfer characteristic C^ from the actuator 16 to the microphone 20 is acquired in advance. When describing the entire acoustic characteristic filter, the symbol 38 is used. When describing each acoustic characteristic filter, the symbols 38X, 38Y, and 38Z are used.

[0064] As described above, the control signal generation unit 24 includes the second filter coefficient update units 40X, 40Y, and 40Z. The second filter coefficient update unit 40X updates the filter coefficient Wx of the second adaptive filter 36X in such a way that the error signal e is minimized, wherein the error signal e is obtained by detecting the residual noise generated by the interference between the noise and the cancelling sound by the microphone 20. The second filter coefficient update unit 40Y updates the filter coefficient Wy of the second adaptive filter 36Y in such a way that the error signal e is minimized, wherein the error signal e is obtained by detecting the residual noise generated by the interference between the noise and the cancelling sound by the microphone 20. The second filter coefficient update unit 40Z updates the filter coefficient Wz in the second adaptive filter 36Z in such a way that the error signal e is minimized, wherein the error signal e is obtained by detecting the residual noise generated by the interference between the noise and the cancelling sound by the microphone 20. When describing the second filter coefficient update unit as a whole, the reference 40 is used. When describing each second filter coefficient update unit, the reference 40X, 40Y, and 40Z are used. When describing the filter coefficient as a whole, the reference W is used. When describing each filter coefficient, symbols Wx, Wy, and Wz are used. When updating the filter coefficient W, for example, the Filtered-X LMS algorithm can be used, but the present invention is not limited to this.

[0065] exist Figure 2 Although one vibration sensor 18 is shown in the figure, a plurality of vibration sensors 18 may be provided in the vehicle 12. The above-mentioned components may be provided for each vibration sensor 18.

[0066] As described above, the control signal generating unit 24 further includes the computing unit 42. The control signal u0 output from each second adaptive filter 36 is input to the computing unit 42. The computing unit 42 adds the control signals u0 provided by each second adaptive filter 36. The computing unit (adder) 42 provides the control signal u generated by adding the plurality of control signals u0 to the actuator 16 via the power amplifier (POWER AMP) 15.

[0067] Thus, in the present embodiment, the second reference signal r2 is generated by the difference between the first reference signal r1 obtained by the vibration sensor 18 and the sensor resonance simulation signal m, wherein the first reference signal r1 is obtained by the vibration sensor 18, and the sensor resonance simulation signal m is a signal obtained by simulating a signal obtained when the vibration sensor 18 resonates. Since the second reference signal r2 is generated by the difference between the first reference signal r1 and the sensor resonance simulation signal m, the magnitude of the component of the resonance frequency f0 of the vibration sensor 18 becomes small in the second reference signal r2. According to the present embodiment, since the control signal u for causing the actuator 16 to output the canceling sound is generated based on such a second reference signal r2, it is possible to provide an active noise control device 10 that can well reduce noise even when the vibration sensor 18 resonates.

[0068] [Second Embodiment]

[0069] use Figure 3 An active noise control device and a vehicle according to a second embodiment will be described. Figure 3 FIG. 1 is a block diagram showing a part of a vehicle having an active noise control device according to the present embodiment. Figure 1 and Figure 2 The same components as those of the active noise control device of the first embodiment shown are denoted by the same reference numerals, and the description thereof will be omitted or simplified.

[0070] In the present embodiment, a resonance frequency identification unit 44X is further provided. The resonance frequency identification unit 44X identifies the resonance frequency f0x of the vibration sensor 18 in the X-axis direction by performing a frequency analysis on the first reference signal rx1. In addition, in the present embodiment, a resonance frequency identification unit 44Y is further provided. The resonance frequency identification unit 44Y identifies the resonance frequency f0y of the vibration sensor 18 in the Y-axis direction by performing a frequency analysis on the first reference signal ry1. In addition, in the present embodiment, a resonance frequency identification unit 44Z is further provided. The resonance frequency identification unit 44Z identifies the resonance frequency f0z of the vibration sensor 18 in the Z-axis direction by performing a frequency analysis on the first reference signal rz1. When describing the resonance frequency identification unit as a whole, the mark 44 is used. When describing each resonance frequency identification unit, the marks 44X, 44Y, and 44Z are used. The resonance frequency identification unit 44, for example, performs a Fourier transform on the first reference signal r1 provided by the vibration sensor 18, and analyzes the frequency spectrum obtained by the Fourier transform, thereby being able to identify the resonance frequency f0 of the vibration sensor 18. The resonance frequency identification unit 44X stores the identified resonance frequency f0x in the X-axis direction in the resonance frequency storage unit 26X. The resonance frequency identification unit 44Y stores the identified resonance frequency f0y in the Y-axis direction in the resonance frequency storage unit 26Y. The resonance frequency identification unit 44Z stores the identified resonance frequency f0z in the Z-axis direction in the resonance frequency storage unit 26Z. The identification of the resonance frequency f0 by the resonance frequency identification unit 44 can be appropriately performed. In addition, the resonance frequency information indicating the resonance frequency f0 is appropriately updated in the resonance frequency storage unit 26.

[0071] The reference signal generating unit 28X generates a reference signal sx corresponding to the resonance frequency f0x identified by the resonance frequency identifying unit 44X. More specifically, the reference signal generating unit 28X reads out the resonance frequency information indicating the resonance frequency f0x identified by the resonance frequency identifying unit 44X from the resonance frequency storage unit 26X, and generates a reference signal sx corresponding to the resonance frequency f0x based on the resonance frequency information. The reference signal generating unit 28Y generates a reference signal sy corresponding to the resonance frequency f0y identified by the resonance frequency identifying unit 44Y. More specifically, the reference signal generating unit 28Y reads out the resonance frequency information indicating the resonance frequency f0y identified by the resonance frequency identifying unit 44Y from the resonance frequency storage unit 26Y, and generates a reference signal sy corresponding to the resonance frequency f0y based on the resonance frequency information. The reference signal generating unit 28Z generates a reference signal sz corresponding to the resonance frequency f0z identified by the resonance frequency identifying unit 44Z. More specifically, the reference signal generating unit 28Z reads out the resonance frequency information indicating the resonance frequency f0z identified by the resonance frequency identifying unit 44Z from the resonance frequency storage unit 26Z, and generates the reference signal sz corresponding to the resonance frequency f0z based on the resonance frequency information.

[0072] Thus, in the present embodiment, a resonance frequency identification unit 44 is further provided, and the resonance frequency identification unit 44 identifies the resonance frequency f0 of the vibration sensor 18 by frequency analysis of the first reference signal r1. According to the present embodiment, since such a resonance frequency identification unit 44 is provided, the resonance frequency information can be accurately updated even when the resonance frequency f0 of the vibration sensor 18 changes. Therefore, according to the present embodiment, an active noise control device 10 capable of better reducing noise can be provided.

[0073] [Third Embodiment]

[0074] use Figure 4 An active noise control device and a vehicle according to a third embodiment will be described. Figure 4 FIG. 1 is a block diagram showing a part of a vehicle having an active noise control device according to the present embodiment. Figure 1 to Figure 3 The same components as those of the active noise control device of the first embodiment or the second embodiment are denoted by the same reference numerals, and the description thereof will be omitted or simplified.

[0075] In the present embodiment, the sampling rate of each component of the reference signal generating unit 22 is set to be more than twice the sampling rate of each component of the control signal generating unit 24. The sampling rate of the first adaptive filter 30X is set to be more than twice the sampling rate of the second adaptive filter 36X. In addition, the sampling rate of the first adaptive filter 30Y is set to be more than twice the sampling rate of the second adaptive filter 36Y. In addition, the sampling rate of the first adaptive filter 30Z is set to be more than twice the sampling rate of the second adaptive filter 36Z.

[0076] When the first reference signal r1 obtained by the vibration sensor 18 is sampled at a relatively low sampling rate, aliasing noise corresponding to the component of the resonance frequency f0 is mixed into the control signal u, and the noise may not be canceled well. In contrast, in the present embodiment, the process for generating the second reference signal r2 is performed at a relatively high sampling rate, so that the aliasing noise corresponding to the component of the resonance frequency f0 can be prevented from being mixed into the control signal u.

[0077] A downsampling unit 46X is provided between the first adaptive filter 30X and the second adaptive filter 36X. The second reference signal rx2 output from the operation unit 32X is input to the downsampling unit 46X. Then, the second reference signal rx2 downsampled by the downsampling unit 46X is input to the second adaptive filter 36X and the acoustic characteristic filter 38X.

[0078] In addition, a down-sampling unit 46Y is provided between the first adaptive filter 30Y and the second adaptive filter 36Y. The second reference signal ry2 output from the operation unit 32Y is input to the down-sampling unit 46Y. Then, the second reference signal ry2 down-sampled by the down-sampling unit 46Y is input to the second adaptive filter 36Y and the acoustic characteristic filter 38Y.

[0079] In addition, a downsampling unit 46Z is further provided between the first adaptive filter 30Z and the second adaptive filter 36Z. The second reference signal rz2 output from the operation unit 32Z is ​​input to the downsampling unit 46Z. Then, the second reference signal rz2 downsampled by the downsampling unit 46Z is input to the second adaptive filter 36Z and the acoustic characteristic filter 38Z. When describing the downsampling unit as a whole, the reference 46 is used, and when describing each downsampling unit, the reference 46X, 46Y, and 46Z are used.

[0080] In this way, the sampling rate in the first adaptive filter 30 may be set to be more than twice the sampling rate in the second adaptive filter 36, and a downsampling unit 46 may be provided between the first adaptive filter 30 and the second adaptive filter 36. According to the present embodiment, since the filtering process for generating the second reference signal r2 is performed at a relatively high sampling rate, it is possible to effectively prevent the aliasing noise corresponding to the component of the resonance frequency f0 from being mixed into the control signal u. Therefore, according to the present embodiment, it is possible to provide an active noise control device 10 that can better reduce noise.

[0081] As mentioned above, although the preferred embodiment of the present invention was described, the present invention is not limited to the above-mentioned embodiment, and various changes can be made without departing from the scope of the present invention.

[0082] The above-mentioned embodiments can be summarized as follows.

[0083] An active noise control device (10) causes an actuator (16) to output a cancelling sound based on a control signal (u) to reduce noise in a cabin (14) of a vehicle (12). The active noise control device (10) comprises a reference signal generating unit (28X, 28Y, 28Z), a first adaptive filter (30X, 30Y, 30Z), a computing unit (32X, 32Y, 32Z) and a second adaptive filter (36X, 36Y, 36Z), wherein the reference signal generating unit (28X, 28Y, 28Z) generates a reference signal (sx, sy, sz) corresponding to a resonance frequency (f0x, f0y, f0z) of a vibration sensor (18) equipped in the vehicle; the first adaptive filter (30X, 30Y, 30Z) generates a reference signal (sx, sy, sz) corresponding to a resonance frequency (f0x, f0y, f0z) of a vibration sensor (18) equipped in the vehicle; and the first adaptive filter (30X, 30Y, 30Z) generates a reference signal (sx, sy, sz) corresponding to a resonance frequency (f0x, f0y, f0z) of a vibration sensor (18) equipped in the vehicle. The reference signal is filtered to generate a sensor resonance simulation signal (mx, my, mz), which is a signal obtained by simulating a signal obtained when the vibration sensor resonates; the operation unit (32X, 32Y, 32Z) calculates a second reference signal (rx2, ry2, rz2), which is a difference between a first reference signal (rx1, ry1, rz1) obtained by the vibration sensor and the sensor resonance simulation signal; and the second adaptive filter (36X, 36Y, 36Z) generates the control signal by performing a filtering process different from the filtering process performed by the first adaptive filter on the second reference signal. According to such a structure, the second reference signal is generated using the difference between the first reference signal obtained by the vibration sensor and the sensor resonance simulation signal simulating a signal obtained when the vibration sensor resonates. Since the second reference signal is generated using the difference between the first reference signal and the sensor resonance simulation signal, the magnitude of the component of the resonance frequency of the vibration sensor becomes smaller in the second reference signal. According to such a configuration, a control signal for causing the actuator to output a canceling sound is generated based on such a second reference signal. Therefore, an active noise control device can be provided that can effectively reduce noise even when the vibration sensor resonates.

[0084] A first filter coefficient updating unit (34X, 34Y, 34Z) may also be provided, which updates the filter coefficients (Wrx, Wry, Wrz) of the first adaptive filter in such a way that the magnitude of the component of the resonance frequency of the vibration sensor is minimized in the second reference signal. According to this structure, the magnitude of the component of the resonance frequency of the vibration sensor can be sufficiently reduced in the second reference signal, whether when the resonance frequency changes or when the magnitude of the component of the resonance frequency changes. Therefore, according to such a structure, an active noise control device can be provided, which can obtain a better second reference signal corresponding to the vehicle vibration and can better reduce noise even when the vibration sensor resonates.

[0085] It may also include a resonance frequency storage unit (26X, 26Y, 26Z), which stores resonance frequency information representing the resonance frequency of the vibration sensor, and the reference signal generating unit generates the reference signal corresponding to the resonance frequency of the vibration sensor based on the resonance frequency information stored in the resonance frequency storage unit.

[0086] The present invention may further include a resonance frequency identification unit (44X, 44Y, 44Z) that identifies the resonance frequency of the vibration sensor by performing frequency analysis on the first reference signal, and the reference signal generation unit generates the reference signal corresponding to the resonance frequency identified by the resonance frequency identification unit. According to this structure, even when the resonance frequency of the vibration sensor changes, the resonance frequency information can be accurately updated. Therefore, according to this structure, an active noise control device that can better reduce noise can be provided.

[0087] The sampling rate in the first adaptive filter may be more than twice the sampling rate in the second adaptive filter, and a downsampling unit (46X, 46Y, 46Z) may be further provided, and the downsampling unit (46X, 46Y, 46Z) may be located between the first adaptive filter and the second adaptive filter. According to such a structure, since the filtering process for generating the second reference signal is performed at a relatively high sampling rate, it is possible to effectively prevent the aliasing noise corresponding to the component of the resonant frequency from being mixed into the control signal. Therefore, according to such a structure, it is possible to provide an active noise control device that can better reduce noise.

[0088] The invention may further include a second filter coefficient updating unit (40X, 40Y, 40Z) for updating the filter coefficients (Wx, Wy, Wz) of the second adaptive filter in such a manner that an error signal (e) is minimized, wherein the error signal (e) is obtained by detecting residual noise by a microphone (20), and the residual noise is generated due to interference between the noise and the canceling sound. According to such a structure, the filter coefficients of the second adaptive filter are well updated, so that an active noise control device capable of better reducing noise can be provided.

[0089] The vehicle includes the active noise control device as described above.

Claims

1. An active noise control device (10) causing an actuator (16) to output a cancelling sound based on a control signal (u) to reduce noise in a cabin (14) of a vehicle (12), It is characterized in that A reference signal generating unit (28X, 28Y, 28Z), a first adaptive filter (30X, 30Y, 30Z), a computing unit (32X, 32Y, 32Z) and a second adaptive filter (36X, 36Y, 36Z), wherein: The reference signal generating unit (28X, 28Y, 28Z) generates a reference signal (sx, sy, sz) corresponding to a resonance frequency (f0x, f0y, f0z) of a vibration sensor (18) equipped in the vehicle; The first adaptive filter (30X, 30Y, 30Z) generates a sensor resonance simulation signal (mx, my, mz) by filtering the reference signal, wherein the sensor resonance simulation signal (mx, my, mz) is a signal obtained by simulating a signal obtained when the vibration sensor resonates; The operation unit (32X, 32Y, 32Z) calculates a second reference signal (rx2, ry2, rz2), which is a difference between a first reference signal (rx1, ry1, rz1) obtained by the vibration sensor and the sensor resonance simulation signal; The second adaptive filter (36X, 36Y, 36Z) generates the control signal by performing a filtering process on the second reference signal that is different from the filtering process performed by the first adaptive filter.

2. The active noise control device according to claim 1, characterized in that: It also has a first filter coefficient updating unit (34X, 34Y, 34Z), which updates the filter coefficients (Wrx, Wry, Wrz) of the first adaptive filter in a manner that minimizes the size of the component of the resonant frequency of the vibration sensor in the second reference signal.

3. The active noise control device according to claim 1, characterized in that: A resonance frequency storage unit (26X, 26Y, 26Z) is further provided, wherein the resonance frequency storage unit (26X, 26Y, 26Z) stores resonance frequency information indicating the resonance frequency of the vibration sensor. The reference signal generating unit generates the reference signal corresponding to the resonance frequency of the vibration sensor based on the resonance frequency information stored in the resonance frequency storage unit.

4. The active noise control device according to claim 1, characterized in that: It also has a resonance frequency identification unit (44X, 44Y, 44Z), which identifies the resonance frequency of the vibration sensor by performing frequency analysis on the first reference signal. The reference signal generation unit generates the reference signal corresponding to the resonance frequency identified by the resonance frequency identification unit.

5. The active noise control device according to claim 1, characterized in that: The sampling rate in the first adaptive filter is more than twice the sampling rate in the second adaptive filter, It also has a down-sampling unit (46X, 46Y, 46Z), which is located between the first adaptive filter and the second adaptive filter.

6. The active noise control device according to claim 1, characterized in that: It also has a second filter coefficient updating unit (40X, 40Y, 40Z), which updates the filter coefficients (Wx, Wy, Wz) of the second adaptive filter in a manner that minimizes an error signal (e), wherein the error signal (e) refers to a signal obtained by detecting residual noise generated by interference between the noise and the canceling sound by a microphone (20).

7. A vehicle, characterized in that: An active noise control device according to any one of claims 1 to 6.

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