Recording medium, microphone, and engine speed acquisition device

Abstract

The present invention provides an active sound control program that can reduce noise in a vehicle cabin regardless of the vehicle model by being installed in a device that can be easily obtained by anyone. The active sound control program is downloaded using a communication device (22) that transmits and receives data to and from a server (26), and causes a processing unit (29) to execute processing for generating a control signal, wherein the control signal is used to cause a speaker (16) disposed in the vehicle cabin to output a canceling sound to reduce noise in the cabin (14) of the vehicle (12). The active sound control program includes an adaptive notch filter (54) and a filter coefficient update unit (60), wherein the adaptive notch filter performs adaptive signal processing on a reference signal to generate a control signal; and the filter coefficient update unit successively updates the filter coefficients of the adaptive notch filter to minimize an error signal.

Description

Technical Field

[0001] The present invention relates to an active sound control program, a microphone, and an engine speed acquisition device, wherein the active sound control program is used to cause a processing unit to execute processing for generating a control signal, wherein the control signal is used to cause a speaker disposed in a vehicle cabin to output a canceling sound to reduce noise within the vehicle cabin; the microphone detects canceling error noise used when causing the processing unit to execute processing in accordance with the active sound control program; and the engine speed acquisition device detects the engine speed used when causing the processing unit to execute processing in accordance with the active sound control program. Background Art

[0002] Japanese Patent Application Laid-Open No. 2012-131244 discloses installing an active sound control program in a mobile terminal and downloading noise transfer characteristics suitable for a vehicle from a server, thereby using the mobile device as an active sound control device. Summary of the Invention

[0003] Japanese Patent Application Laid-Open No. 2012-131244 does not discuss a technique for reducing the noise in a vehicle cabin regardless of the vehicle model by installing an active sound control program in a device that anyone can easily obtain.

[0004] The present invention was developed to address the aforementioned issues, and its purpose is to provide an active sound control program that, by installing it in a device readily available to anyone, can reduce noise within the vehicle cabin, regardless of the vehicle model. Furthermore, the present invention provides a microphone that detects cancellation error noise used when a processing unit executes processing in accordance with the active sound control program, and an engine speed acquisition device that detects engine speed used when the processing unit executes processing in accordance with the active sound control program.

[0005] A first aspect of the present invention is an active sound control program that is downloaded using a communication device that transmits and receives data to and from a server, and causes a processing unit to execute processing for generating a control signal, wherein the control signal is used to cause a speaker installed in a vehicle cabin to output a canceling sound to reduce noise in the vehicle cabin. The active sound control program is characterized by comprising a reference signal generator, an adaptive notch filter, an error signal input unit, a determination unit, a reference signal generator, and a filter coefficient updater. The reference signal generator generates a reference signal corresponding to the noise generated by a noise source; the adaptive notch filter performs adaptive signal processing on the reference signal to generate the control signal; the error signal input unit inputs an error signal corresponding to the error noise canceling the canceling sound output from the speaker in response to the control signal and the noise; the determination unit determines the sound transfer characteristics in the vehicle cabin space and generates a correction value; the reference signal generator corrects the reference signal based on the correction value to generate a reference signal; and the filter coefficient updater sequentially updates the filter coefficients of the adaptive notch filter based on the error signal and the reference signal to minimize the error signal.

[0006] The second technical solution of the present invention is a microphone that detects the cancellation error noise used when the processing device executes processing according to the active sound control program described in the above-mentioned first technical solution, is connected to a device installed with the active sound control program downloaded using the communication device via a wired or wireless method, and is installed in the vehicle cabin in a detachable manner.

[0007] The third technical solution of the present invention is an engine speed acquisition device, which acquires the engine speed used when the operation processing device executes the active sound control program according to the above-mentioned first technical solution, is connected to the device via a wired or wireless method, and is installed in the vehicle cabin in a detachable manner.

[0008] According to the present invention, by installing an active sound control program in a device that anyone can easily obtain, it is possible to reduce the noise in the vehicle cabin regardless of the vehicle model. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 This is a diagram illustrating the outline of active acoustic control.

[0010] Figure 2 This is a block diagram of a smartphone and an in-vehicle system.

[0011] Figure 3A and Figure 3B 1 is a diagram showing an example of installation positions of microphones in a vehicle cabin.

[0012] Figure 4 It is a block diagram of an active sound control device.

[0013] Figure 5 It is a block diagram of an active sound control device.

[0014] Figure 6 This is a table showing the orders of components of the vibration frequency corresponding to the number of cylinders of the engine.

[0015] Figure 7 This is a table showing the values ​​of the control filter coefficients corresponding to each predetermined frequency.

[0016] Figure 8A is a flowchart showing the flow of active noise control processing.

[0017] Figure 8B This is a flowchart showing the flow of setting processing.

[0018] Figure 8C This is a flowchart showing the flow of setting processing.

[0019] Figure 8D This is a flowchart showing the flow of setting processing.

[0020] Figure 9 It is a diagram showing a smartphone.

[0021] Figure 10 It is a diagram showing a smartphone.

[0022] Figure 11 It is a diagram showing a smartphone.

[0023] Figure 12 It is a diagram showing a smartphone.

[0024] Figure 13 It is a diagram showing a smartphone.

[0025] Figure 14 It is a diagram showing a smartphone.

[0026] Figure 15 It is a diagram showing a smartphone.

[0027] Figure 16 It is a diagram showing a smartphone.

[0028] Figure 17 It is a block diagram of an active sound control device.

[0029] Figure 18 It is a block diagram of an active sound control device.

[0030] Figures 19A to 19C1 is a diagram showing an example of installation positions of microphones in a vehicle cabin.

[0031] Figure 20 Schematic diagram of active noise control.

[0032] Figure 21 This is a block diagram of a smartphone, an in-vehicle system, and a vehicle information acquisition device.

[0033] Figure 22A and Figure 22B This is a diagram showing an example of the installation position of the vehicle information acquisition device in the vehicle cabin.

[0034] Figure 23 This is a block diagram of a smartphone and an in-vehicle system.

[0035] Figure 24 It is a block diagram of an active sound control device. DETAILED DESCRIPTION

[0036] [First embodiment]

[0037] Figure 1 1 is a diagram illustrating an overview of active sound control executed in the active sound control device 10 .

[0038] The active sound control device 10 causes a speaker 16 installed in the interior 14 of a vehicle 12 to output canceling sound, thereby reducing the engine roar (hereinafter referred to as noise) transmitted to passengers in the interior 14 by the vibration of the engine 18. The active sound control device 10 generates a control signal u0 for causing the speaker 16 to output the canceling sound based on an error signal e, which corresponds to the sound collected by a microphone 20 installed in the interior 14, and the engine speed Ne detected by an engine speed sensor 19. The error signal e is a signal that cancels error noise, which is a combination of the canceling sound and noise at the position of the microphone 20. The engine 18 corresponds to the drive source of the present invention, and the engine speed sensor 19 corresponds to the engine speed acquisition device of the present invention.

[0039] Figure 2 It is a block diagram of the smartphone 22 and the in-vehicle system 24 mounted on the vehicle 12 .

[0040] The smartphone 22 downloads the active sound control program from the server 26 via the Internet 28. The downloaded active sound control program is installed in the smartphone 22. The smartphone 22 corresponds to the communication device of the present invention.

[0041] The smartphone 22 has two terminals (not shown) for connecting to external devices: an external connection terminal and an earphone / microphone terminal. The smartphone 22 is connected to the in-vehicle system 24 and the microphone 20 via a wired connection, and is wirelessly connected to the engine speed sensor 19.

[0042] Furthermore, when the smartphone 22 is connected to the engine speed sensor 19 by wire, the smartphone 22 can also be connected wirelessly to the in-vehicle system 24. Furthermore, in recent years, there are also smartphones 22 that do not have headphone / microphone terminals. In such cases, the microphone 20 can also be connected wirelessly.

[0043] The engine speed sensor 19 is connected to an OBD (On-Board Diagnostics) connector 112 installed on the vehicle 12. The OBD connector 112 is connected to the vehicle's ECU via a CAN or K-line. Vehicle information such as engine speed, water temperature, voltage, and boost pressure can be obtained from the OBD connector 112.

[0044] The engine speed sensor 19 may be connected to the vehicle-mounted system 24 via a wired method such as USB. In this case, the engine speed sensor 19 acquires information on the engine speed flowing through the CAN via the vehicle-mounted system 24.

[0045] Alternatively, the engine speed sensor 19 may not be provided, and the smartphone 22 may estimate the engine speed based on a change in a DC voltage of the vehicle 12 for charging the smartphone 22 or the like.

[0046] The microphone 20 is provided in the vehicle interior 14 so that the user can easily attach or detach the microphone 20 therefrom. Figure 3A and Figure 3B 1 is a diagram showing an example of the installation position of the microphone 20 in the vehicle cabin 14. In the case where the vehicle 12 is a right-hand drive vehicle, as shown in FIG. Figure 3A As shown, the microphone 20 is fixed to the left side surface (vehicle center side) of the headrest 15 a of the driver's seat 15 by double-sided tape or the like.

[0047] The location of the microphone 20 is not limited to Figure 3A For example, Figure 3B As shown, the microphone 20 may be fixed to the left side surface (vehicle center side) of the seat back 15b of the driver's seat 15 using double-sided tape or the like. Furthermore, if the vehicle 12 is a left-hand drive vehicle, the microphone 20 is provided on the right side surface of the headrest 15a or the seat back 15b of the driver's seat 15.

[0048] Refer again Figure 2Smartphone 22 includes a processing unit 29, a memory 30, a storage device 31, a microphone 32, a display 34, a touch screen 36, an acceleration sensor 37, a mobile communication module 38, a wireless LAN communication module 40, and a short-range wireless communication module (near-field communication module) 42. Acceleration sensor 37 corresponds to the acceleration detection unit of the present invention.

[0049] The processing unit 29 is, for example, a processor such as a central processing unit (CPU) or a microprocessor (MPU). The memory 30 is, for example, a non-transitory or temporary tangible computer-readable recording medium such as a ROM or RAM. The storage device 31 is, for example, a non-transitory tangible computer-readable recording medium such as a hard disk or a solid-state drive (SSD).

[0050] When the active sound control program is installed in the smartphone 22, the active sound control program is stored in the storage device 31. The processing unit 29 performs active sound control processing according to the active sound control program stored in the storage device 31, so that the smartphone 22 functions as the active sound control device 10.

[0051] Microphone 32 collects sounds around smartphone 22. Display 34 is a display device using, for example, liquid crystal or organic electroluminescence (OLED). Touchscreen 36 is a pointing device that detects the location on display 34 touched by a user's finger or the like. Acceleration sensor 37 detects the acceleration acting on smartphone 22. When smartphone 22 is inside vehicle cabin 14, the acceleration detected by acceleration sensor 37 can be considered the acceleration of vehicle 12.

[0052] The mobile communication module 38 is a module that communicates with a base station 28a connected to the Internet 28 via cellular communication. The wireless LAN communication module 40 is a module that communicates with an access point 28b connected to the Internet 28 via wireless LAN communication such as Wi-Fi (registered trademark). This allows the smartphone 22 to exchange data with the server 26 via the Internet 28. The short-range wireless communication module 42 is a module that communicates with the in-vehicle system 24 via short-range wireless communication such as Bluetooth (registered trademark).

[0053] The in-vehicle system 24 includes a processing unit 43 , a memory 44 , a sound source 45 , a display 46 , a touch screen 48 , a short-range wireless communication module 50 , and an amplifier 53 .

[0054] The processing unit 43 is, for example, a processor such as a central processing unit (CPU) or a microprocessor (MPU). The memory 44 is, for example, a non-transitory or temporary tangible computer-readable recording medium such as a ROM or RAM. The audio source 45 is, for example, a non-transitory tangible computer-readable recording medium such as a hard disk or a solid-state drive (SSD), storing information such as music and car navigation audio.

[0055] The display 46 is a display device using, for example, liquid crystal, organic electroluminescence (OLED), or the like. The touch screen 48 is a pointing device that detects the location on the display 46 touched by a user's finger or the like. The short-range wireless communication module 50 communicates with the engine speed sensor 19, smartphone 22, and the like via short-range wireless communication such as Bluetooth (registered trademark). Furthermore, wired communication such as USB may be used instead of wireless communication to communicate with the engine speed sensor 19, smartphone 22, and the like.

[0056] The in-vehicle system 24 is connected to the speaker 16 via the amplifier 53. The in-vehicle system 24 and the speaker 16 are connected by wire. In addition, the in-vehicle system 24 and the speaker 16 can also be connected wirelessly. The processing unit 43 outputs a sound source signal for causing the speaker 16 to output the music or voice stored in the sound source 45. The sound source signal is amplified in the amplifier 53 and then output to the speaker 16. The processing unit 43 sends the control signal u0 sent from the smartphone 22 (active sound control device 10) to the amplifier 53. In addition, the control signal u0 can also be sent directly from the smartphone 22 (active sound control device 10) to the amplifier 53. The control signal u0 is amplified in the amplifier 53 and output to the speaker 16. Accordingly, the music or voice of the sound source is output from the speaker 16, and a cancellation sound that cancels out the noise is output.

[0057] [Active sound control device]

[0058] Figure 4 and Figure 5This is a block diagram of the active sound control device 10. In the active sound control device 10, a SAN (Single-Frequency Adaptive Notch) filter, which is a notch filter, is used as an adaptive digital filter. The Filtered-X LMS (Least Mean Square) algorithm is used to update the coefficients of the SAN filter. The active sound control device 10 of this embodiment implements active noise control as active sound control. Before performing active noise control (hereinafter referred to as ANC processing), the active sound control device 10 of this embodiment performs a determination process to determine the sound transfer characteristic C (hereinafter referred to as secondary path transfer characteristic C) in the transmission path (hereinafter referred to as secondary path) from the speaker 16 to the microphone 20. The active noise control performed by the active sound control device 10 of this embodiment is hereinafter referred to as pre-determined active noise control. Note that the transmission path from the speaker 16 to the microphone 20 is referred to as a secondary path, whereas the transmission path from the engine 18 to the microphone 20 is referred to as a primary path hereinafter.

[0059] Figure 4 A block diagram showing the active sound control device 10 during ANC processing. Figure 5 2 is a block diagram showing the active sound control device 10 during the determination process. The active sound control device 10 switches between the ANC process and the determination process using the process switching unit 51 .

[0060] (ANC processing)

[0061] use Figure 4 The signal processing performed in the active sound control device 10 during ANC processing will now be described. The active sound control device 10 includes a reference signal generator 52, a control signal generator 54, an error signal input unit 56, a reference signal generator 58, and a control filter coefficient updater 60. The control signal generator 54 corresponds to the adaptive notch filter of the present invention, and the control filter coefficient updater 60 corresponds to the filter coefficient updater and determiner of the present invention.

[0062] The reference signal generating unit 52 generates reference signals xc and xs according to the engine speed Ne. The reference signal generating unit 52 includes a frequency detection circuit 52a, a cosine signal generator 52b, and a sine signal generator 52c.

[0063] Frequency detection circuit 52a detects the fundamental frequency, or vibration frequency f, of noise (growing) generated synchronously with the rotation of the output shaft of engine 18. The roar of engine 18 is vibration radiated sound generated by the excitation force generated by the rotation of engine 18, which is transmitted to the vehicle body. Therefore, it is a vibration noise with a distinct frequency characteristic that is synchronized with the rotational speed of engine 18. For example, if engine 18 is a four-stroke, four-cylinder engine, the torque fluctuation caused by gas combustion with each half rotation of the output shaft of engine 18 generates excitation vibration centered on engine 18. This generates noise within vehicle cabin 14.

[0064] The vibration frequency f is detected based on the engine speed Ne. The engine speed Ne can be converted into the rotation frequency fe by the following formula.

[0065] [Formula 1]

[0066] fe[Hz]=Ne[rpm] / 60[sec]

[0067] For example, when the engine speed Ne is 6000 [rpm], the rotation frequency fe is 100 [Hz].

[0068] When the engine 18 is a four-stroke engine, ignition is performed once per two revolutions in each cylinder. For example, when the engine speed Ne of the four-cylinder engine 18 is 6000 [rpm], the vibration frequency f is as follows.

[0069] [Formula 2]

[0070]

[0071] That is, the vibration frequency f of the four-cylinder engine 18 has a secondary component (double component) of the rotation frequency fe. Figure 6 This table shows the order (multiple) of the components of the vibration frequency f corresponding to the number of cylinders of the engine 18. The vibration frequency f can be obtained by multiplying the rotation frequency fe by the order corresponding to the number of cylinders of the engine 18.

[0072] The cosine signal generator 52b generates a reference signal xc (=cos(2πft)) which is a cosine signal of a vibration frequency f. The sine signal generator 52c generates a reference signal xs (=sin(2πft)) which is a sine signal of a vibration frequency f. Here, t represents time.

[0073] The control signal generator 54 generates a control signal u0 based on the reference signals xc and xs. The control signal generator 54 corresponds to the adaptive notch filter of the present invention. The control signal generator 54 includes a first control filter 54a, a second control filter 54b, and an adder 54c.

[0074] In the control signal generating unit 54 , a SAN filter is used as a control filter.

[0075] The first control filter 54a has a filter coefficient W0. The second control filter 54b has a filter coefficient W1. The filter coefficients W0 and W1 are optimized by adaptively updating in a control filter coefficient update unit 60 described later.

[0076] The reference signal xc filtered by the first control filter 54a and the reference signal xs filtered by the second control filter 54b are added together in the adder 54c to generate the control signal u0. The speaker 16 is controlled based on the control signal u0, and the speaker 16 outputs the canceling sound.

[0077] The reference signal generator 58 generates reference signals r0 and r1 based on the reference signals xc and xs. The reference signal generator 58 includes a first secondary path filter 58a, a second secondary path filter 58b, a third secondary path filter 58c, a fourth secondary path filter 58d, an adder 58e, and an adder 58f.

[0078] A notch filter is used as the secondary path filter in the reference signal generator 58. The coefficient C^ of the secondary path filter (hereinafter referred to as secondary path filter coefficient C^) is obtained in a determination process described later.

[0079] The first secondary path filter 58a has a secondary path filter coefficient C0^, which is the real part of the secondary path filter coefficient C^ (=C0^ + iC1^). The second secondary path filter 58b has a filter coefficient -C1^, which is obtained by inverting the polarity of the imaginary part of the secondary path filter coefficient C^. The third secondary path filter 58c has a filter coefficient C0^, which is the real part of the secondary path filter coefficient C^. The fourth secondary path filter 58d has a filter coefficient C1^, which is the imaginary part of the secondary path filter coefficient C^.

[0080] The reference signal xc filtered by the first secondary path filter 58a and the reference signal xs filtered by the second secondary path filter 58b are added together in an adder 58e to generate a reference signal r0. The reference signal xs filtered by the third secondary path filter 58c and the reference signal xc filtered by the fourth secondary path filter 58d are added together in an adder 58f to generate a reference signal r1.

[0081] That is, the reference signal generating unit 58 corrects the reference signals xc and xs based on the secondary path filter coefficient Ĉ as a correction value, thereby generating the reference signals r0 and r1.

[0082] The error signal input unit 56 inputs an error signal e corresponding to the cancellation error noise collected by the microphone 20. The cancellation error noise is a noise obtained by synthesizing the noise d input to the microphone 20 and the cancellation sound y input to the microphone 20. Alternatively, the error signal input unit 56 may input an error signal e corresponding to the cancellation error noise collected by the microphone 32 mounted on the smartphone 22.

[0083] The control filter coefficient updater 60 adaptively updates the filter coefficients W0 and W1 of the control signal generator 54 based on the reference signals r0 and r1 and the error signal e. The control filter coefficient updater 60 adaptively updates the filter coefficients W0 and W1 using the Filtered-X LMS algorithm. The control filter coefficient updater 60 includes a first control filter coefficient updater 60a and a second control filter coefficient updater 60b.

[0084] The first control filter coefficient updating unit 60a and the second control filter coefficient updating unit 60b update the filter coefficients W0 and W1 according to the following equations: n in the equations represents a time step (n=0, 1, 2, ...), and μ0 and μ1 represent step size parameters.

[0085] [Formula 3]

[0086] W0(n+1)=W0(n)-μ0×e(n)×{C0^(n)×xc(n)-C1^(n)×xs(n)}

[0087] W1(n+1)=W1(n)-μ1×e(n)×{C0^(n)×xs(n)+C1^(n)×xc(n)}

[0088] The control filter coefficient update unit 60 repeatedly updates the filter coefficients W0 and W1 to optimize the filter coefficients W0 and W1. In the active sound control device 10 using the SAN filter, the update formula for the filter coefficients W0 and W1 consists of four arithmetic operations and does not include convolution operations. This reduces the computational load caused by the update process of the filter coefficients W0 and W1.

[0089] (Confirm processing)

[0090] Reference Figure 5 The signal processing performed in the determination process in the active acoustic control device 10 will be described.

[0091] In the determination process, a determination sound of a predetermined frequency fm (= f0, f1, ..., fm-1) is output from the speaker 16 to determine the secondary path transfer characteristic C at this time. As the determination sound, white noise, pink noise, or a sine sweep can be used.

[0092] In the determination process, the secondary path transfer characteristic C at each predetermined frequency fm is determined as the secondary path filter coefficient C^. The determination process is executed when the engine 18 is stopped. In the determination process, the filter coefficient of the first secondary path filter 58a is fixed to 1, the filter coefficient of the second secondary path filter 58b is fixed to 0, the filter coefficient of the third secondary path filter 58c is fixed to 1, and the filter coefficient of the fourth secondary path filter 58d is fixed to 0.

[0093] The frequency detection circuit 52a outputs a predetermined frequency fm (= f0, f1, ..., fm-1). The cosine signal generator 52b generates a reference signal xc, which is a cosine signal of the predetermined frequency fm. The sine signal generator 52c generates a reference signal xs, which is a sine signal of the predetermined frequency fm.

[0094] The reference signal xc is output as the determination signal x. The speaker 16 is controlled based on the determination signal x, and a determination sound is output from the speaker 16.

[0095] The error signal input unit 56 receives as input a noise signal xC corresponding to the specific sound collected by the microphone 20 . The noise signal xC is input to the adder 64 .

[0096] The reference signal xc filtered by the first control filter 54a and the reference signal xs filtered by the second control filter 54b are added together in an adder 54c to generate a control signal u1. The polarity of the control signal u1 is inverted by an inverter 62 and input to an adder 64. The adder 64 generates a virtual error signal e′, which is the difference between the noise signal xc and the control signal u1.

[0097] The control filter coefficient updating unit 60 performs adaptive signal processing on the filter coefficients W0 and W1 of the control signal generating unit 54 based on the reference signals r0 and r1 and the virtual error signal e′.

[0098] The first control filter coefficient updating unit 60a and the second control filter coefficient updating unit 60b update the filter coefficients W0 and W1 according to the following equations.

[0099] [Formula 4]

[0100] W0(n+1)=W0(n)-μ0×e′(n)×xc(n)

[0101] W1(n+1)=W1(n)-μ1×e′(n)×xs(n)

[0102] During the determination process, the frequency detection circuit 52a sweeps the predetermined frequency fm and controls the filter coefficient update unit 60 to adaptively update the filter coefficients W0 and W1 at a predetermined time for each predetermined frequency fm. The adaptively updated filter coefficient W0 is recorded as the filter coefficient C0^ for each predetermined frequency fm, and the adaptively updated filter coefficient W1 is recorded as the filter coefficient C1^ for each predetermined frequency fm. Figure 7 The table shows the values ​​of the filter coefficients C0^ and C1^ corresponding to the respective predetermined frequencies f0, f1, ..., fa-1. The control filter coefficient update unit 60 in the determination process corresponds to the determination unit of the present invention.

[0103] [Active Noise Control Processing in Smartphones]

[0104] Figure 8A : is a flowchart showing the flow of active noise control processing in the smartphone 22 .

[0105] When the active sound control program is installed in the smartphone 22 , the active sound control application program can be used in the smartphone 22 . Figure 9 This figure shows smartphone 22 with initial screen 34a displayed on display 34. If the active sound control program is installed on smartphone 22, an icon 35a for the active sound control application is displayed on initial screen 34a. When a user clicks icon 35a, the active sound control application starts, and processing unit 29 executes active noise control processing. The active noise control processing is repeatedly executed at a predetermined interval until the user performs the ANC OFF operation (described later).

[0106] In step S1 , the processing unit 29 displays the ANC ON operation screen 34 b on the display 34 , and then moves to step S2 . Figure 10 3 is a diagram showing the smartphone 22 with an ANC ON operation screen 34b displayed on the display 34. The ANC ON operation screen 34b includes an ANC ON button 35b, a check box 35c, and a setting button 35r.

[0107] In step S2, the processing unit 29 determines whether a setting operation has been performed by the user. If a setting operation has been performed, the process proceeds to step S3; if not, the process proceeds to step S4. When the user clicks the setting button 35r, the processing unit 29 determines that the user has performed a setting operation.

[0108] In step S3 , the processing unit 29 performs a setting process described later, and then moves to step S4 .

[0109] In step S4, the processing unit 29 determines whether the user has performed the ANC ON operation. If the ANC ON operation has been performed, the process proceeds to step S5. If the ANC ON operation has not been performed, the process returns to step S2. If the user clicks the ANC ON button 35b, the processing unit 29 determines that the user has performed the ANC ON operation.

[0110] In step S5, the processing unit 29 determines whether the skip confirmation process is selected. If the skip confirmation process is selected, the process proceeds to step S10. If the skip confirmation process is not selected, the process proceeds to step S6. Figure 10 When the user clicks and selects the check box 35c in the ANC ON operation screen 34b, and then clicks the ANC ON button 35b, the processing unit 29 determines that the skip confirmation process is selected.

[0111] In step S6 , the arithmetic processing unit 29 executes a determination process and then moves to step S7 .

[0112] In step S7 , the processing unit 29 causes the display 34 to display the confirmation processing notification screen 34 f , and the process proceeds to step S8 . Figure 11 This figure shows a smartphone 22 with a confirmation process notification screen 34f displayed on the display 34. The confirmation process notification screen 34f displays a message to inform the user that the confirmation process is in progress and that noise is being generated. This suppresses the discomfort and anxiety that the user may feel due to the noise.

[0113] In step S8, the arithmetic processing unit 29 determines whether the determination process has been completed. If the determination process has been completed, the process proceeds to step S9. If the determination process has not been completed, the process returns to step S6.

[0114] In step S9 , the processing unit 29 causes the display 34 to display the confirmation processing end notification screen 34 g , and then moves to step S10 . Figure 12 3 is a diagram showing the smartphone 22 with a confirmation processing completion notification screen 34g displayed on the display 34. The confirmation processing completion notification screen 34g displays a message for notifying the user that the confirmation processing has been completed and that the ANC processing is being executed.

[0115] In step S10 , the arithmetic processing device 29 executes the ANC process, and then moves to step S11 .

[0116] In step S11 , the processing unit 29 displays the ANC processing notification screen 34 h on the display 34 , and then moves to step S12 . Figure 1334. This figure shows the smartphone 22 displaying an ANC process notification screen 34h on the display 34. The ANC process notification screen 34h displays an image for notifying the user that the ANC process is in progress. In addition, an ANC OFF button 35q is displayed on the ANC process notification screen 34h.

[0117] In step S12, the processing unit 29 determines whether an ANC OFF operation has been performed. If an ANC OFF operation has been performed, the active noise control process ends. If an ANC OFF operation has not been performed, the process returns to step S10. When the user clicks the ANC OFF button 35q, the processing unit 29 determines that the user has performed an ANC OFF operation.

[0118] Figure 8B 、 Figure 8C and Figure 8D is a flowchart showing the flow of the setting process executed in step S3. As described above, when the user clicks Figure 10 The setting button 35r shown executes the setting process when a setting operation is performed. For example, the setting operation is performed when the active noise control application is first started after the active noise control program is installed in the smartphone 22, when the number of microphones 20 is changed, or when a new vehicle is purchased.

[0119] In step S21 , the processing unit 29 causes the display 34 to display the engine cylinder number input screen 34 c , and then the process shifts to step S22 . Figure 14 3 is a diagram showing the smartphone 22 with an engine cylinder number input screen 34c displayed on the display 34. The engine cylinder number input screen 34c includes an engine cylinder number input portion 35d, a Help button 35e, and a Next button 35f.

[0120] In step S22 , the arithmetic processing device 29 inputs 0 to the argument m and the argument n, and moves to step S23 .

[0121] In step S23, the processing unit 29 determines whether a Help operation has been performed. If a Help operation has been performed, the process proceeds to step S29. If not, the process proceeds to step S24. When the user clicks the Help button 35e, the processing unit 29 determines that a Help operation has been performed by the user.

[0122] In step S24, the processing unit 29 determines whether the user has completed inputting the number of cylinders of the engine 18 into the engine cylinder number input unit 35d. If the user has completed inputting the number of cylinders of the engine 18, the process proceeds to step S25. If not, the process proceeds to step S26.

[0123] In step S25 , the processing unit 29 increments the argument m, that is, increases the value of the argument m by 1, and then moves to step S28 .

[0124] In step S26, the processing unit 29 determines whether the user has performed a next operation. If the user has performed a next operation, the process proceeds to step S27. If the user has not performed a next operation, the process proceeds to step S28. When the user clicks the next button 35f, the processing unit 29 determines that the user has performed a next operation.

[0125] In step S27 , the arithmetic processing device 29 increments the argument n, and then moves to step S28 .

[0126] In step S28 , the processing unit 29 determines whether the product of the argument m and the argument n is 0. If the product of the argument m and the argument n is 0, the process returns to step S23 . If the product of the argument m and the argument n is not 0, the process proceeds to step S40 .

[0127] If it is determined in step S23 that the user has performed a Help operation, the processing unit 29 proceeds to step S29 where it determines whether the argument m is 0. If the argument m is 0, the processing proceeds to step S30 , and if not, the processing returns to step S23 .

[0128] In step S30 , the processing unit 29 displays the search screen 34 d on the display 34 , and then moves to step S31 . Figure 15 34 is a diagram showing the smartphone 22 with a search screen 34d displayed on the display 34. The search screen 34d includes a vehicle name input unit 35g, a level input unit 35h, and a Search button (search button) 35j.

[0129] In step S31 , the arithmetic processing device 29 inputs 0 to the argument l, the argument m, and the argument n, and then moves to step S32 .

[0130] In step S32, the processing unit 29 determines whether the user has completed inputting the vehicle name into the vehicle name input unit 35g. If the vehicle name input is completed, the process proceeds to step S33, and if the user has not completed the input, the process proceeds to step S34.

[0131] In step S33, the processing unit 29 increments the argument 1, and then moves to step S38.

[0132] In step S34, the processing unit 29 determines whether the user has completed inputting a grade into the grade input unit 35h. If the user has completed inputting a grade, the process proceeds to step S35. If the user has not completed inputting a grade, the process proceeds to step S36.

[0133] In step S35 , the processing unit 29 increments the argument m, and then moves to step S38 .

[0134] In step S36, the processing unit 29 determines whether the user has performed a Search operation. If a Search operation has been performed, the process proceeds to step S37. If not, the process proceeds to step S38. When the user clicks the Search button 35j, the processing unit 29 determines that the user has performed a Search operation.

[0135] In step S37 , the processing unit 29 increments the argument n, and then moves to step S38 .

[0136] In step S38, the processing unit 29 determines whether the product of the independent variable 1, the independent variable m, and the independent variable n is 0. If the product of the independent variable 1, the independent variable m, and the independent variable n is 0, the process returns to step S32. If the product of the independent variable 1, the independent variable m, and the independent variable n is not 0, the process moves to step S39.

[0137] In step S39 , the processing unit 29 receives the number of cylinders of the engine 18 corresponding to the input vehicle name and grade from the server 26 , and then moves to step S40 .

[0138] In step S40 , the processing unit 29 causes the display 34 to display the speaker number and microphone number input screen 34 e , and then moves to step S41 . Figure 16 3 is a diagram showing the smartphone 22 displaying a speaker number and microphone number input screen 34e on the display 34. The speaker number and microphone number input screen 34e includes a speaker number input section 35k, a microphone number input section 35m, a check box 35n, and an end button 35p.

[0139] In step S41 , the processing unit 29 inputs 0 to the argument l and the argument m, and then moves to step S42 .

[0140] In step S42, it is determined whether the user has completed inputting the number of speakers 16 into the speaker number input unit 35k. If the user has completed inputting the number of speakers 16, the process proceeds to step S43. If the user has not completed inputting the number of speakers 16, the process proceeds to step S44.

[0141] In step S43, the processing unit 29 increments the argument 1, and then moves to step S46.

[0142] In step S44, the processing unit 29 determines whether the user has completed inputting the number of microphones 20 into the microphone number input unit 35m. If the user has completed inputting the number of microphones 20, the process proceeds to step S45. If not, the process proceeds to step S47.

[0143] In step S45 , the processing unit 29 increments the argument m, and then moves to step S46 .

[0144] In step S46, the processing unit 29 determines whether the product of the argument 1 and the argument m is 0. If the product of the argument 1 and the argument m is 0, the process proceeds to step S50. If the product of the argument 1 and the argument m is not 0, the process proceeds to step S47.

[0145] In step S47, the processing unit 29 determines whether the user has selected the use of the microphone 32 of the smartphone 22. If the user has selected the use of the microphone 32 of the smartphone 22, the process proceeds to step S48. If the user has not selected the use of the microphone 32 of the smartphone 22, the process proceeds to step S49. If the user has clicked and selected the checkbox 35n, the processing unit 29 determines that the user has selected the use of the microphone 32.

[0146] In step S48 , the processing unit 29 determines that the active noise control process is to be performed using the microphone 32 mounted on the smartphone 22 , and then the process shifts to step S50 .

[0147] In step S49 , the processing unit 29 determines that the active noise control process is not to be performed using the microphone 32 mounted on the smartphone 22 , and then the process moves to step S50 .

[0148] In step S50, the processing unit 29 determines whether the product of the independent variable 1 and the independent variable m is 0. If the product of the independent variable 1 and the independent variable m is 0, the process returns to step S42. If the product of the independent variable 1, the independent variable m, and the independent variable n is not 0, the setting process ends.

[0149] [Active sound control device using FIR filter]

[0150] Hereinafter, an active sound control device 66 using an FIR filter will be described as a comparative example of the active sound control device 10 using the SAN filter of the present embodiment.

[0151] Figure 17This is a block diagram of an active sound control device 66 using an FIR filter. In active sound control device 66, an FIR (Finite Impulse Response) filter is used as an adaptive digital filter. The Filtered-X LMS algorithm is used to update the filter coefficients of the FIR filter.

[0152] The active acoustic control device 66 includes a reference signal generating unit 68 , a control signal generating unit 70 , a reference signal generating unit 72 , an error signal receiving unit 74 , and a control filter coefficient updating unit 76 .

[0153] The reference signal generating unit 68 generates a reference signal x based on the engine speed Ne. The reference signal generating unit 68 includes a frequency detecting circuit 68a and a cosine signal generator 68b.

[0154] The frequency detection circuit 68 a , like the frequency detection circuit 52 a of the active sound control device 10 of the present embodiment, detects the vibration frequency f of the engine 18 based on the engine speed Ne and the number of cylinders of the engine 18 .

[0155] Cosine signal generator 68b generates a cosine signal of vibration frequency f, namely, reference signal x (= cos(2π ft)). t represents time. When the number of taps of the FIR filter is N, the time series signal vector X(n) of reference signal x(n) at time step n is defined by the following equation.

[0156] [Formula 5]

[0157] X(n)=[x(n),x(n-1),x(n-2),…x(n-N+1)] T

[0158] The control signal generator 70 generates a control signal u0 based on the time series signal vector X of the reference signal x. An FIR filter, which is an adaptive filter, is used as the control filter in the control signal generator 70. The control filter coefficient W is optimized by being updated by the control filter coefficient updater 76 described later.

[0159] The control filter coefficient W(n) at time step n is expressed by the following equation.

[0160] [Formula 6]

[0161] W(n)=[w0(n),w1(n),w2(n),…w N-1 (n)] T

[0162] The control signal u0(n) at time step n is expressed as follows: In the following formula, “*” represents the convolution sum.

[0163] [Formula 7]

[0164]

[0165] In addition, the time vector U0(n) is expressed by the following equation.

[0166] [Formula 8]

[0167] U0(n)=[u0(n),u0(n-1),u0(n-2),…,u0(n-N+1)] T

[0168] The reference signal x after the filtering process is output as the control signal u0 in the control signal generating unit 70. The speaker 16 is controlled based on the control signal u0, and the canceling sound is output from the speaker 16.

[0169] The reference signal generator 72 generates a reference signal r based on the reference signal x. The reference signal generator 72 includes a secondary path filter. The value of the secondary path filter coefficient C^ is stored on the server 26 for each vehicle model and downloaded from the server 26 to the active acoustic control device 66. The secondary path filter coefficient C^(n) at time step n is expressed as follows:

[0170] [Formula 9]

[0171] C^(n)=[c0^(n), c1^(n), c2^(n),…c N-1 ^(n)] T

[0172] The reference signal r(n) at time step n is expressed by the following equation: In the following equation, “*” represents the convolution sum.

[0173] [Formula 10]

[0174]

[0175] In addition, the time vector R(n) is expressed by the following equation.

[0176] [Formula 11]

[0177] R(n)=[r(n), r(n-1), r(n-2),…, r(n-N+1)] r

[0178] The error signal receiving unit 74 receives an error signal e corresponding to the cancellation error noise collected by the microphone 20. The error signal e is a signal corresponding to the cancellation error noise obtained by combining the cancellation sound and noise at the position of the microphone 20.

[0179] The control filter coefficient updater 76 updates the control filter coefficient W of the control signal generator 70 based on the reference signal r and the error signal e. The control filter coefficient updater 76 updates the control filter coefficient W based on the Filtered-X LMS algorithm. The control filter coefficient updater 76 updates the control filter coefficient W based on the following equation.

[0180] [Formula 12]

[0181]

[0182] The control filter coefficient update unit 76 repeatedly updates the control filter coefficient W to optimize the control filter coefficient W. Since the update formula of the control filter coefficient W includes a convolution operation, the calculation load caused by the update process of the control filter coefficient W increases.

[0183] [Effects]

[0184] Active noise control that reduces noise in the vehicle cabin 14 using a device that anyone can easily obtain is desired. Therefore, it is conceivable to download an active noise control program from the server 26 to the smartphone 22 to cause the smartphone 22 to perform active noise control.

[0185] In the active sound control device 66 of the comparative example, which uses an FIR filter, the update formula for updating the control filter coefficient W in the control filter coefficient update unit 76 includes a convolution operation. Therefore, when active noise control is performed using the active sound control device 66, the computational processing load becomes very large, and memory usage also increases. Therefore, the smartphone 22 functioning as the active sound control device 66 is required to have a high-speed computational processing unit 29 and a large-capacity memory 30. In other words, it is impossible to use an inexpensive smartphone 22 as the active sound control device 66, and active noise control cannot be performed using a device that is easily available to anyone.

[0186] Furthermore, in the active sound control device 66 of the comparative example using an FIR filter, the secondary path filter coefficient C^ is downloaded from the server 26. Since the active sound control device 66 does not determine the secondary path transfer characteristic C, the computational load on the processing unit 29 and the memory 30 usage associated with the determination process can be reduced. Since the secondary path transfer characteristic C varies for each vehicle model, the server 26 stores the secondary path filter coefficient C^ corresponding to the secondary path transfer characteristic C for each vehicle model. Therefore, if the vehicle model does not have the secondary path filter coefficient C^ stored in the server 26, the active sound control device 66 cannot suppress noise within the vehicle cabin 14. In other words, users of a vehicle model for which the secondary path filter coefficient C^ is not stored in the server 26 cannot use the smartphone 22 to function as the active sound control device 66.

[0187] Therefore, in this embodiment, a smartphone 22 installed with an active sound control program functions as an active sound control device 10 using a SAN filter. In the active sound control device 10, the update formula for updating the control filter coefficient W in the control filter coefficient update unit 60 consists of four arithmetic operations and does not include convolution operations.

[0188] Therefore, when active noise control is performed using the active sound control device 10, the computational load caused by the update process of the control filter coefficient W can be reduced. Consequently, the smartphone 22 functioning as the active sound control device 10 is not required to include a processing unit 29 equipped with a processor capable of high-speed computation and a large-capacity memory 30. Consequently, even an inexpensive smartphone 22 can function as the active sound control device 10, enabling active noise control processing to be performed using a device that is easily accessible to anyone.

[0189] Furthermore, in this embodiment, the active sound control device 10 determines the secondary path transfer characteristic C in the control filter coefficient update unit 60 and generates filter coefficients C0^ and C1^ as correction values. The filter coefficients C0^ and C1^ are determined based on a plurality of specific sounds of predetermined frequencies fm. Consequently, the smartphone 22 functioning as the active sound control device 10 can determine the secondary path transfer characteristic C. Therefore, regardless of the vehicle 12 model, the smartphone 22 can function as the active sound control device 10.

[0190] In this embodiment, the active noise control device 10 generates reference signals xc and xs based on the number of engine cylinders and the engine speed Ne in the reference signal generating unit 52. This allows the active noise control device 10 to reduce sounds having a vibration frequency f, which is the fundamental frequency of noise in the vehicle interior 14.

[0191] Furthermore, in this embodiment, the microphone 20 is detachably mounted within the vehicle interior 14. Therefore, when a user transfers to another vehicle 12, the user can remove the microphone 20 from the original vehicle 12 and install it in the other vehicle 12. Therefore, if a user brings a smartphone 22 with the active sound control program installed into the other vehicle 12, active noise control can be performed in the other vehicle 12 using the smartphone 22.

[0192] [Second embodiment]

[0193] In the active sound control device 10 of the first embodiment, the determination process is performed while a determination sound (noise) is output from the speaker 16 before the ANC process is performed. In contrast, in the active sound control device 10 of the second embodiment, the ANC process and the determination process are performed in parallel, and the determination process is performed without using the determination sound. Hereinafter, the active noise control performed by the active sound control device 10 of this embodiment will be referred to as normal determination-type active noise control.

[0194] [Active sound control device]

[0195] Figure 18 This is a block diagram of an active sound control device 10 according to a second embodiment. The active sound control device 10 includes a reference signal generator 78, a control signal generator 80, a first estimated cancellation signal generator 82, an estimated noise signal generator 84, a reference signal generator 86, a second estimated cancellation signal generator 88, an error signal receiver 90, a primary path filter coefficient updater 92, a secondary path filter coefficient updater 94, and a control filter coefficient updater 96.

[0196] The reference signal generator 78 generates reference signals xc and xs based on the engine speed Ne. The reference signal generator 78 includes a frequency detection circuit 78a, a cosine signal generator 78b, and a sine signal generator 78c. The processing performed by the reference signal generator 78 is the same as that performed by the reference signal generator 52 of the active sound control device 10 of the first embodiment.

[0197] The control signal generator 80 generates control signals u0 and u1 based on the reference signals xc and xs. The control signal generator 80 includes a first control filter 80a, a second control filter 80b, a third control filter 80c, a fourth control filter 80d, an adder 80e, and an adder 80f.

[0198] In the control signal generation unit 80, a SAN filter is used as the control filter. The first control filter 80a has a filter coefficient W0. The second control filter 80b has a filter coefficient W1. The third control filter 80c has a filter coefficient -W0. The fourth control filter 80d has a filter coefficient W1. The control filter coefficient update unit 96, described later, updates the filter coefficients W0 and W1 to optimize the control filter.

[0199] Reference signal xc filtered by first control filter 80a and reference signal xs filtered by second control filter 80b are added together in adder 80e to generate control signal u0. Speaker 16 is controlled based on control signal u0, and canceling sound is output from speaker 16. Reference signal xs filtered by third control filter 80c and reference signal xc filtered by fourth control filter 80d are added together in adder 80f to generate control signal u1.

[0200] The first estimated cancellation signal generating unit 82 generates an estimated cancellation signal y1^ based on the control signals u0 and u1. The first estimated cancellation signal generating unit 82 includes a first secondary path filter 82a, a second secondary path filter 82b, and an adder 82c.

[0201] A SAN filter is used as the secondary path filter in the first estimated cancellation signal generation unit 82. The secondary path filter coefficient Ĉ is adaptively updated in the secondary path filter coefficient update unit 94 described later.

[0202] The first secondary path filter 82a has a filter coefficient C0^, which is the real part of the secondary path filter coefficient C^ (= C0^ + iC1^). The second secondary path filter 82b has a filter coefficient C1^, which is the imaginary part of the secondary path filter coefficient C^. The control signal u0 filtered by the first secondary path filter 82a and the control signal u1 filtered by the second secondary path filter 82b are added together in an adder 82c to generate an estimated cancellation signal y1^. The estimated cancellation signal y1^ is an estimated signal corresponding to the canceling sound y input to the microphone 20.

[0203] The estimated noise signal generator 84 generates an estimated noise signal d^ based on the reference signals xc and xs. The estimated noise signal generator 84 includes a first primary path filter 84a, a second primary path filter 84b, and an adder 84c. The estimated noise signal generator 84 uses a SAN filter as the primary path filter. The primary path filter coefficient H^ (hereinafter referred to as the primary path filter coefficient H^) is adaptively updated by the primary path filter coefficient updater 92, described later.

[0204] The first primary path filter 84a has a filter coefficient H0^, which is the real part of the primary path filter coefficient H^ (= H0^ + iH1^). The second primary path filter 84b has a filter coefficient -H1^, which is obtained by inverting the polarity of the imaginary part of the primary path filter coefficient H^. The reference signal xc filtered by the first primary path filter 84a and the reference signal xs filtered by the second primary path filter 84b are added together in an adder 84c to generate an estimated noise signal d^. The estimated noise signal d^ is an estimated signal corresponding to the noise d input to the microphone 20.

[0205] The reference signal generator 86 generates reference signals r0 and r1 based on the reference signals xc and xs. The reference signal generator 86 includes a third secondary path filter 86a, a fourth secondary path filter 86b, a fifth secondary path filter 86c, a sixth secondary path filter 86d, an adder 86e, and an adder 86f.

[0206] The SAN filter is used as the secondary path filter in the reference signal generating unit 86. The secondary path filter coefficient Ĉ is adaptively updated in the secondary path filter coefficient updating unit 94 described later.

[0207] The third secondary path filter 86a has a filter coefficient C0^, which is the real part of the secondary path filter coefficient C^ (=C0^ + iC1^). The fourth secondary path filter 86b has a filter coefficient -C1^, which is obtained by inverting the polarity of the imaginary part of the secondary path filter coefficient C^. The fifth secondary path filter 86c has a filter coefficient C0^, which is the real part of the secondary path filter coefficient C^. The sixth secondary path filter 86d has a filter coefficient C1^, which is the imaginary part of the secondary path filter coefficient C^.

[0208] Reference signal xc filtered by third-stage path filter 86a and reference signal xs filtered by fourth-stage path filter 86b are added together in adder 86e to generate reference signal r0. Reference signal xs filtered by fifth-stage path filter 86c and reference signal xc filtered by sixth-stage path filter 86d are added together in adder 86f to generate reference signal r1. Filter coefficients C0^, C1^, and -C1^ correspond to correction values ​​of the present invention.

[0209] The second estimated cancellation signal generating unit 88 generates an estimated cancellation signal y2̂ based on the reference signals r0 and r1. The second estimated cancellation signal generating unit 88 includes a fifth control filter 88a, a sixth control filter 88b, and an adder 88c.

[0210] The second estimated cancellation signal generator 88 uses a SAN filter as the control filter. The fifth control filter 88a has a filter coefficient W0. The sixth control filter 88b has a filter coefficient W1. The control filter coefficient updater 96, described later, updates the filter coefficients W0 and W1 to optimize the control filter.

[0211] Adder 88c adds reference signal r0 filtered by fifth control filter 88a and reference signal r1 filtered by sixth control filter 88b to generate estimated cancellation signal y2̂. Estimated cancellation signal y2̂ is an estimated signal corresponding to the canceling sound y input to microphone 20.

[0212] The error signal receiving unit 90 receives an error signal e corresponding to the cancellation error noise collected by the microphone 20. The error signal e is a signal corresponding to the cancellation error noise obtained by combining the cancellation sound and noise at the position of the microphone 20.

[0213] The error signal e received by the error signal receiving unit 90 is input to an adder 98. The estimated noise signal d^ generated by the estimated noise signal generating unit 84 is polarity-inverted by an inverter 100 and then input to the adder 98. The estimated cancellation signal y1^ generated by the first estimated cancellation signal generating unit 82 is polarity-inverted by an inverter 102 and then input to the adder 98. The adder 98 generates a virtual error signal e1.

[0214] The estimated noise signal d̂ generated by the estimated noise signal generating unit 84 is input to the adder 104. The estimated cancellation signal y2̂ generated by the second estimated cancellation signal generating unit 88 is input to the adder 104. The adder 104 generates a virtual error signal e2.

[0215] The primary path filter coefficient updater 92 updates the primary path filter coefficient H^ (=H^ + iH^) based on the reference signals xc and xs and the virtual error signal e1. The primary path filter coefficient updater 92 updates the primary path filter coefficient H^ using a Filtered-X LMS (Least Mean Square) algorithm. The primary path filter coefficient updater 92 includes a first primary path filter coefficient updater 92a and a second primary path filter coefficient updater 92b.

[0216] The first and second primary path filter coefficient updating units 92a and 92b update the filter coefficients H0^ and H1^ according to the following equations: n represents a time step (n=0, 1, 2, ...), and μ0 and μ1 represent step size parameters.

[0217] [Formula 13]

[0218] H0^(n+1)=H0^(n)-μ0×e1(n)×xc(n)

[0219] H1^(n+1)=H1^(n)-μ1×e1(n)×xs(n)

[0220] The primary path filter coefficient updating unit 92 repeatedly updates the primary path filter coefficient H^ to determine the primary path transfer characteristic H (hereinafter referred to as the primary path transfer characteristic H). In the active acoustic control device 10 using the SAN filter, the update formula for the primary path filter coefficient H^ is composed of four arithmetic operations and does not include convolution operations. This reduces the computational load caused by the update process of the primary path filter coefficient H^.

[0221] The secondary path filter coefficient updater 94 updates the secondary path filter coefficient C^ (=C^ + iC^) based on the control signals u0 and u1 and the virtual error signal e1. The secondary path filter coefficient updater 94 updates the secondary path filter coefficient C^ using the Filtered-X LMS algorithm. The secondary path filter coefficient updater 94 includes a first secondary path filter coefficient updater 94a and a second secondary path filter coefficient updater 94b.

[0222] The first secondary path filter coefficient updating unit 94a and the second secondary path filter coefficient updating unit 94b update the filter coefficients C0^ and C1^ according to the following equations: μ2 and μ3 in the equations represent step size parameters.

[0223] [Formula 14]

[0224] C0^(n+1)=C0^(n)-μ2×e1(n)×{W0(n)×xc(n)+W1(n)×xs(n)}

[0225] C1^(n+1)=C1^(n)-μ3×e1(n)×{-W0(n)×xs(n)+W1(n)×xc(n)}

[0226] The secondary path filter coefficient updating unit 94 repeatedly updates the secondary path filter coefficient C^ to determine the secondary path transfer characteristic C. In the active acoustic control device 10 using the SAN filter, the update formula for the secondary path filter coefficient C^ is composed of four arithmetic operations and does not include convolution operations. This reduces the computational load associated with updating the secondary path filter coefficient C^.

[0227] The control filter coefficient update unit 96 updates the filter coefficients W0 and W1 based on the reference signals r0 and r1 and the virtual error signal e2. The control filter coefficient update unit 96 updates the control filter coefficient W using the Filtered-X LMS algorithm. The control filter coefficient update unit 96 includes a first control filter coefficient update unit 96a and a second control filter coefficient update unit 96b.

[0228] The first control filter coefficient updating unit 96a and the second control filter coefficient updating unit 96b update the filter coefficients W0 and W1 according to the following equations: μ4 and μ5 in the equations represent step size parameters.

[0229] [Formula 15]

[0230] W0(n+1)=W0(n)-μ4×e2(n)×{C0(n)×xc(n)-C1(n)×xs(n)}

[0231] W1(n+1)=W1(n)-μ5×e2(n)×(C0(n)×xs(n)+C1(n)×xc(n)}

[0232] The control filter coefficient update unit 96 repeatedly updates the filter coefficients W0 and W1 to optimize the control filter. In the active sound control device 10 using the SAN filter, the update formula for the filter coefficients W0 and W1 consists of four arithmetic operations and does not include convolution operations. This reduces the computational load associated with updating the filter coefficients W0 and W1.

[0233] [Active Noise Control Processing in Smartphones]

[0234] In the active sound control device 10 of this embodiment, it is not necessary to perform a determination process before the ANC process. Therefore, in the smartphone 22 of this embodiment, the active noise control process performed in the smartphone 22 of the first embodiment is not performed. Figure 8A The processing from step S5 to step S9.

[0235] In the ANC ON operation screen 34b displayed on the display 34 of the smartphone 22 in this embodiment, only the ANC ON button 35b is displayed, and the check box 35c is not displayed. The remaining processing is the same as that of the active sound control device 10 in the first embodiment.

[0236] [Effects]

[0237] In this embodiment, a smartphone 22 installed with an active sound control program functions as an active sound control device 10 using a SAN filter. In the active sound control device 10, the update equations for updating the primary path filter coefficient H^ in the primary path filter coefficient update unit 92, the update equation for updating the secondary path filter coefficient C^ in the secondary path filter coefficient update unit 94, and the update equation for updating the control filter coefficient W in the control filter coefficient update unit 96 all consist of four arithmetic operations and do not include convolution operations.

[0238] Therefore, when active noise control is performed using the active sound control device 10, the computational load caused by the update process for the primary path filter coefficient H^, the secondary path filter coefficient C^, and the control filter coefficient W can be reduced. Consequently, the smartphone 22 functioning as the active sound control device 10 is not required to have a high-speed computational processing unit 29 or a large-capacity memory 30. Consequently, even an inexpensive smartphone 22 can function as the active sound control device 10, enabling active noise control processing to be performed using a device that is easily accessible to anyone.

[0239] Furthermore, in the active sound control device 10 of this embodiment, since the determination process is performed simultaneously with the ANC process, the primary path transfer characteristic H and the secondary path transfer characteristic C can be determined even if the primary path transfer characteristic H and the secondary path transfer characteristic C change during the ANC process.

[0240] [Third embodiment]

[0241] In the first and second embodiments, the active sound control device 10 generates a control signal u0 for controlling one speaker 16 based on an error signal e input from one microphone 20. In the third embodiment, the active sound control device 10 generates a control signal u0[l] (l=0, 1, ..., l-1) for controlling l speakers 16 based on error signals e[m] (m=0, 1, ..., m-1) input from m microphones 20.

[0242] The microphone 20 is provided in the vehicle interior 14 so as to be easily attachable and detachable by a user. Figure 19A 、 Figure 19B and Figure 19C 1 is a diagram showing an example of the installation position of two microphones 20 in the vehicle cabin 14. In the case where the vehicle 12 is a right-hand drive vehicle, as shown in FIG. Figure 19AAs shown, one microphone 20 is secured to the right side (vehicle exterior) of the headrest 15a of the driver's seat 15 using double-sided tape or the like, and the other microphone 20 is secured to the left side (vehicle exterior) of the headrest 17a of the passenger seat 17 using double-sided tape or the like. Furthermore, if the vehicle 12 is a left-hand drive vehicle, one microphone 20 is provided on the left side of the headrest 15a of the driver's seat 15, and the other microphone 20 is provided on the right side of the headrest 17a of the passenger seat 17.

[0243] The setting position of the microphone 20 is not limited to Figure 19A For example, if the vehicle 12 is a right-hand drive vehicle, Figure 19B As shown, one microphone 20 may be fixed to the left side surface (vehicle center side) of the headrest 15a of the driver's seat 15 using double-sided tape or the like, and the other microphone 20 may be fixed to the left side surface of the headrest 13a at the center of the rear seat 13 using double-sided tape or the like. Furthermore, if the vehicle 12 is a left-hand drive vehicle, one microphone 20 may be provided on the right side surface of the headrest 15a of the driver's seat 15, and the other microphone 20 may be provided on the right side surface of the headrest 13a at the center of the rear seat 13.

[0244] In addition, if Figure 19C As shown, one microphone 20 may be fixed to the left side surface (the center side of the vehicle) of the headrest 15a of the driver's seat 15 using double-sided tape or the like, and the other microphone 20 may be fixed to the rear side surface of the headrest 13a in the center of the rear seat 13 using double-sided tape or the like. Furthermore, if the vehicle 12 is a left-hand drive vehicle, one microphone 20 may be provided on the right side surface of the headrest 15a of the driver's seat 15.

[0245] Figure 20 is a schematic diagram of active noise control using multiple microphones 20 and multiple speakers 16.

[0246] There are m transmission paths (primary paths) from the engine 18 to each microphone 20, and each path has a primary path transmission characteristic H (H[0] to H[m-1]). Therefore, the active sound control device 10 requires m primary path filter coefficients H^[0] to H^[m-1] corresponding to each primary path transmission characteristic H.

[0247] There are [l×m] transfer paths (secondary paths) from each speaker 16 to each microphone 20, and each path has a secondary path transfer characteristic C (C[0, 0] to C[l-1, m-1]). Therefore, the active sound control device 10 requires (l×m) secondary path filter coefficients C^[0, 0] to C^[l-1, m-1] corresponding to each secondary path transfer characteristic C.

[0248] Since there are one speaker 16, the active sound control device 10 needs to generate one control signal u0 (u0[0] to u0[1-1]) to be input to each speaker 16. Therefore, the active sound control device 10 needs one control filter coefficient W (W[0] to W[1-1]).

[0249] That is, the number of primary path filter coefficients Ĥ, secondary path filter coefficients Ĉ, and control filter coefficients W is determined according to the number of speakers 16 and the number of microphones 20 .

[0250] In the active sound control device 10 of this embodiment, each filter coefficient is updated using the MEFX (Multiple Error Filtered-X)-LMS algorithm. The following describes the update formulas for the control filter coefficient W in the a priori deterministic active noise control described in the first embodiment, and the update formulas for the primary path filter coefficient H^, the secondary path filter coefficient C^, and the control filter coefficient W in the normal deterministic active noise control described in the second embodiment.

[0251] [Filter coefficient update formula in ex ante deterministic active noise control]

[0252] The update formula for the control filter coefficients W0[j] and W1[j] used to generate the control signal u0[j] input to the j-th speaker 16 is expressed as follows. Here, let the reference signals be xc and xs, let the secondary path filter coefficients corresponding to the sound transfer characteristic C[j, k] in the transfer path from the j-th speaker 16 to the k-th microphone 20 be C[j, k]^, and let the error signal input to the k-th microphone 20 be e[k]. In the formula, n represents the time step (n = 0, 1, 2, ...), and μ0 and μ1 represent step size parameters.

[0253] [Formula 16]

[0254]

[0255]

[0256] [Usually the filter coefficient update formula in deterministic active noise control]

[0257] The update formula for the primary path filter coefficient H[k]^(=H0[k]^+iH1[k]^) corresponding to the sound transfer characteristic H[k] in the transfer path from the engine 18 to the k-th microphone 20 is expressed by the following formula. Here, the reference signals are xc and xs, and the virtual error signal of the k-th microphone 20 is e1[k]. In the formula, n represents the time step (n=0, 1, 2, ...), and μ0 and μ1 represent step size parameters.

[0258] [Formula 17]

[0259] H0[k]^(n+1)=H0[k]^(n)-μ0×e1[k](n)×xc(n)

[0260] H1[k]^(n+1)=H1[k]^(n)-μ1×e1[k](n)×xs(n)

[0261] The update formula for the secondary path filter coefficients C[j,k]^(=C0[j,k]^+iC1[j,k]^) corresponding to the sound transfer characteristic C[j,k] in the transfer path from the j-th speaker 16 to the k-th microphone 20 is expressed by the following equation. Here, let the reference signals be xc and xs, the virtual error signal from the k-th microphone 20 be e1[k], and the control filter coefficients used to generate the control signal u0[j] input to the j-th speaker 16 be W[j](=W0[j]+iW1[j]). In the equation, μ2 and μ3 represent step size parameters.

[0262] [Formula 18]

[0263] C0[j,k]^(n+1)=C0[j,k]^(n)-μ2×e1[k](n)×{W0[j](n)×xc(n)+W1[j](n)×xs(n)}

[0264] C1[j,k]^(n+1)=C1[j,k]^(n)-μ3×e1[k](n)×{-W0[j](n)×xs(n)+W1[j](n)×xc(n)}

[0265] The update formula for the control filter coefficients W0[j] and W1[j] used to generate the control signal u0[j] input to the j-th speaker 16 is expressed as follows. Here, let the reference signals be xc and xs, the secondary path filter coefficient corresponding to the sound transfer characteristic C[j, k] in the transfer path from the j-th speaker 16 to the k-th microphone 20 be C[j, k]^, and the virtual error signal of the k-th microphone 20 be e2[k]. In the formula, μ4 and μ5 represent step size parameters.

[0266] [Formula 19]

[0267]

[0268]

[0269] [Effects]

[0270] In the active sound control device 10 of this embodiment, the number of primary path filter coefficients H^, secondary path filter coefficients C^, and control filter coefficients W is determined according to the number of speakers 16 and the number of microphones 20. Thus, the active sound control device 10 of this embodiment can appropriately perform active noise control according to the number of speakers 16 and the number of microphones 20.

[0271] [Fourth embodiment]

[0272] In the first to third embodiments, the smartphone 22 installed with the active sound control program functions as the active sound control device 10. In contrast, in this embodiment, the vehicle information acquisition device 106 installed with the active sound control program functions as the active sound control device 10.

[0273] Figure 21 1 is a block diagram of the smartphone 22, the in-vehicle system 24, and the vehicle information acquisition device 106. In this embodiment, detailed descriptions of the same configurations as those in the first to third embodiments will be omitted.

[0274] The vehicle information acquisition device 106 is connected to the smartphone 22 via a wired connection. Furthermore, the vehicle information acquisition device 106 is connected to the in-vehicle system 24 via a wired connection. Alternatively, the vehicle information acquisition device 106 may be connected to the smartphone 22 and the in-vehicle system 24 wirelessly.

[0275] The active sound control program is downloaded from the server 26 to the smartphone 22 via the Internet 28, and is then sent from the smartphone 22 to the vehicle information acquisition device 106. The vehicle information acquisition device 106 installs the active sound control program sent from the smartphone 22.

[0276] Information on the ANC processing and the confirmation processing may be displayed on the display 46 of the in-vehicle system 24 or on the display 34 of the smartphone 22 .

[0277] The vehicle information acquisition device 106 includes a processing unit 107 , a memory 108 , a storage device 109 , and a short-range wireless communication module (near field communication module) 110 .

[0278] The processing unit 107 is a processor such as a central processing unit (CPU) or a microprocessor (MPU). The memory 108 is a non-transitory or temporary tangible computer-readable recording medium such as a ROM or RAM. The storage device 109 is a non-transitory tangible computer-readable recording medium such as a flash memory.

[0279] When the active sound control program is installed in the vehicle information acquisition device 106, the active sound control program is stored in the storage device 109. The processing device 107 performs active sound control processing according to the active sound control program stored in the storage device 109, and the processing device 107 functions as the active sound control device 10.

[0280] The short-range wireless communication module 110 is a module for communicating via short-range wireless communication such as Bluetooth (registered trademark). When the vehicle information acquisition device 106 is wirelessly connected to the smartphone 22 and the in-vehicle system 24, the short-range wireless communication module 110 is used to communicate with the smartphone 22 and the in-vehicle system 24.

[0281] The vehicle information acquisition device 106 is connected to an OBD (On-Board Diagnostics) connector 112 provided on the vehicle 12. The OBD connector 112 is connected to the vehicle's ECU via a CAN or K-line. Vehicle information such as engine speed, water temperature, voltage, and boost pressure can be acquired from the OBD connector 112.

[0282] The vehicle information acquisition device 106 is connected to the microphone 20 via a wired connection. The vehicle information acquisition device 106 and the microphone 20 may also be connected wirelessly.

[0283] The vehicle information acquisition device 106 is installed in the vehicle compartment 14 in a manner that is easily attachable and detachable by a user. Figure 22A and Figure 22B 14 is a diagram showing an example of the installation position of the vehicle information acquisition device 106 in the vehicle compartment 14. Figure 22A As shown, the vehicle information acquisition device 106 is fixed to the center lower cover 23 below the steering wheel 21 using double-sided tape or the like. A wiring 106a extends from the vehicle information acquisition device 106, and the vehicle information acquisition device 106 is connected to the smartphone 22 and the in-vehicle system 24 via the wiring 106a.

[0284] The setting position of the vehicle information acquisition device 106 is not limited to Figure 22A For example, Figure 22B As shown, it may be fixed to the side surface of the center console 25 by a double-sided tape or the like.

[0285] [Effects]

[0286] In this embodiment, the vehicle information acquisition device 106 is connected to the OBD connector 112. Thus, the vehicle information acquisition device 106 can acquire the engine speed Ne from the on-vehicle ECU.

[0287] Furthermore, the vehicle information acquisition device 106 is detachably mounted within the vehicle cabin 14. Therefore, when a user transfers to another vehicle 12, the user can remove the vehicle information acquisition device 106 from the original vehicle 12 and install it in the other vehicle 12. Therefore, if the vehicle information acquisition device 106 with the active sound control program installed is installed in the other vehicle 12, active noise control can be performed in the other vehicle 12 using the vehicle information acquisition device 106.

[0288] [Fifth embodiment]

[0289] In the first to third embodiments, a smartphone 22 installed with an active sound control program functions as the active sound control device 10. In contrast, in this embodiment, an in-vehicle system 24 installed with an active sound control program functions as the active sound control device 10.

[0290] Figure 23 2 is a block diagram of the smartphone 22 and the in-vehicle system 24. In this embodiment, detailed descriptions of the same configurations as those in the first to third embodiments will be omitted.

[0291] The in-vehicle system 24 is connected to the smartphone 22 via a wired connection. The in-vehicle system 24 can also be connected to the smartphone 22 wirelessly.

[0292] The active sound control program is downloaded from the server 26 to the smartphone 22 via the Internet 28, and is then transmitted from the smartphone 22 to the in-vehicle system 24. The in-vehicle system 24 installs the active sound control program transmitted from the smartphone 22.

[0293] Information on the ANC processing and the confirmation processing may be displayed on the display 46 of the in-vehicle system 24 or on the display 34 of the smartphone 22 .

[0294] The vehicle-mounted system 24 is connected to the engine speed sensor 19 and the microphone 20 via a wired manner. The vehicle-mounted system 24 can also be connected to the engine speed sensor 19 and the microphone 20 via a wireless manner.

[0295] [Effects]

[0296] In this embodiment, the active sound control program is downloaded from the server 26 via the smartphone 22 equipped with a mobile communication module 38 and a wireless LAN communication module 40. The downloaded active sound control program is then transmitted from the smartphone 22 to the in-vehicle system 24, where it is installed. This allows the active sound control program to be installed even in an in-vehicle system 24 that is not equipped with a mobile communication module or a wireless LAN communication module, allowing it to function as the active sound control device 10.

[0297] [Sixth embodiment]

[0298] In the first to fifth embodiments, the active sound control device 10 implements active noise control within the active sound control. In contrast, in this embodiment, the active sound control device 10 performs active sound effect control in addition to active noise control. In the active sound effect control, sound effects simulating engine sounds are output from the speaker 16 according to the engine speed Ne. This can, for example, provide comfort to the occupants of the vehicle 12 and enhance the sense of acceleration.

[0299] Figure 24 This is a block diagram of the active sound control device 10. The active sound control device 10 includes an active noise control unit 113 that performs active noise control and an active sound effect control unit 114 that performs active sound effect control. The structure of the active noise control unit 113 uses the structure of the active sound control device 10 according to any of the first to fourth embodiments. The active sound effect control unit 114 corresponds to the sound effect generation unit of the present invention.

[0300] The active sound effect control unit 114 includes a frequency detection circuit 116 , a harmonic signal generation unit 118 , a waveform storage unit 120 , and a control signal generation unit 122 .

[0301] Similar to frequency detection circuit 78a in the first embodiment, frequency detection circuit 116 detects vibration frequency f. Harmonic signal generator 118 generates harmonic signal fh that is four, five, or six times the vibration frequency f. Waveform storage 120 stores waveform data with different amplitudes and phases for each harmonic signal fh. Control signal generator 122 generates control signal v0 based on the waveform data corresponding to harmonic signal fh.

[0302] The control signal u0 output from the active noise control unit 113 and the control signal v0 output from the active sound effect control unit 114 are added together in the adder 124. The speaker 16 is controlled based on the control signals u0 and v0. As a result, the speaker 16 outputs a canceling sound for reducing noise and a sound effect simulating an engine sound.

[0303] [Effects]

[0304] The active sound control device 10 of this embodiment includes an active noise control unit 113 and an active sound effect control unit 114. With these, the speaker 16 can output a canceling sound for reducing noise and a sound effect simulating an engine sound.

[0305] [Modification]

[0306] In the first to sixth embodiments, the vibration frequency f is detected based on the engine speed Ne. The acceleration of the vehicle 12 and the engine speed Ne have a high correlation. Therefore, the vibration frequency f can also be detected based on the acceleration of the vehicle 12 detected by the acceleration sensor 37 of the smartphone 22 in the vehicle cabin 14.

[0307] The engine speed Ne also has a high correlation with the speed of the vehicle 12. Therefore, the integrated value of the acceleration of the vehicle 12 detected by the acceleration sensor 37 of the smartphone 22 in the vehicle cabin 14 may be used as the speed, and the vibration frequency f may be detected based on the speed.

[0308] [Regarding the term "computer" in this application]

[0309] In this application, a computer refers to a machine that automatically performs complex calculations according to a given procedure. Specifically, it refers to an electrical machine that can continuously input and output digital data, perform calculations, and transform digital data using electronic circuits, and can be used for various purposes by providing detailed processing steps described by humans.

[0310] Generally speaking, machines classified as computers include personal computers (PCs), which are general-purpose computers for individuals; servers and mainframes, which are large-scale, high-performance computers used in corporate information systems; and supercomputers, which are ultra-high-performance computers used for scientific and technological calculations. Furthermore, many electrical devices that process information and data often incorporate a computer in some form.

[0311] Therefore, in this application, various communication devices such as mobile phones, smartphones, and tablet terminals, as well as electronically controlled home appliances such as video recorders, digital televisions, digital cameras, game consoles, and vehicle control devices, industrial machines, etc. are also included in computers.

[0312] That is, the computer in this application is composed of input and output devices for exchanging data with the outside, storage devices for recording data, control devices for controlling the execution of programs and the execution status of programs and the status of each device, and computing devices for calculating and processing data.

[0313] The storage device can also be divided into a main storage device for temporary storage and an external storage device (auxiliary storage device) for permanent recording.

[0314] The control device and the computing device may be integrated into one device or semiconductor chip, which may serve as a processing device (or central processing unit, CPU, processor).

[0315] The calculation steps of a computer are recorded and provided as data (programmed in a way), which is called a computer program or simply a program.

[0316] [Regarding the term "processing device" in this application]

[0317] An arithmetic processing unit (CPU, microprocessor, MPU, or processor) is a device that integrates transistors and semiconductor elements. It is one of the main components of a computer, controlling other devices and circuits and performing data operations. An arithmetic processing unit integrates both arithmetic and control functions, and currently uses a microprocessor (MPU) integrated on a single IC chip.

[0318] The arithmetic processing unit sequentially reads (fetches) machine language programs stored in main memory (RAM) via a bus, one command at a time, interprets their contents to determine the actions to be performed (decoding), and drives internal circuits to actually execute the processing. The arithmetic processing unit internally consists of a control unit that interprets commands and instructs other circuits on their actions, an arithmetic and logic unit (ALU) that performs logical and arithmetic operations, registers that temporarily store data, and interface circuits for external communication.

[0319] Furthermore, in order to compensate for the significant speed and capacity differences between registers and main memory, a cache memory having a speed and capacity intermediate between the two is usually built in.

[0320] [Regarding the term "main storage device" in this application]

[0321] Main storage is also known as "main memory," "memory," or "RAM." It is directly connected to the central processing unit (CPU) via wiring on the circuit board. It can be read and written immediately by the CPU, storing information such as the program code currently being executed and data required for the current process. Main storage has a higher read and write speed than external storage devices, and the speed difference between the two is significant. However, due to the higher unit price of main storage, the capacity that can be installed in a device is generally several digits smaller.

[0322] In modern computers, DRAM (Dynamic RAM), a type of RAM (Random Access Memory) in semiconductor memory devices (semiconductor memory), is almost always used as main storage. This type of RAM loses its stored contents when the device's power is turned off, for example. Therefore, the basic operation is to use a storage device to permanently store data and programs, and when the computer boots up, it reads the required program from the main memory and executes it. In addition, most modern CPUs have internal storage circuits called "cache memories" that are faster than DRAM, but these only serve as temporary storage to increase the speed of data exchange with DRAM, and their operation cannot be explicitly controlled by the program.

[0323] [Regarding the term storage device in this application]

[0324] Storage devices are also called "external storage devices," "external storage units," or "auxiliary storage devices." Storage devices are one of the main components of a computer and are used to permanently store data. Examples of storage devices include magnetic disks (such as hard disks), optical disks (such as CDs, DVDs, and Blu-ray Discs), flash memory devices (such as USB memories, memory cards, and SSDs), and magnetic tapes.

[0325] Storage devices generally refer to storage devices that maintain their stored contents even when power is off. They are used to store programs and data used by computers over long periods of time. Computers also have a built-in main storage device (main memory, memory) that stores data using semiconductor devices and other components. When a user runs a program to process data, the necessary data is transferred from storage to memory for use.

[0326] When comparing devices mounted on the same computer, storage devices have storage capacities several digits (tens to thousands of times) larger than memories and cost several digits less per unit capacity, but require several digits more time for reading and writing.

[0327] [Technical ideas obtained from implementation methods]

[0328] The following describes technical ideas that can be grasped from the above-mentioned embodiments.

[0329] An active sound control program is downloaded using a communication device (22) for transmitting and receiving data with a server (26), and causes a processing unit (29) to execute processing for generating a control signal, wherein the control signal is used to cause a speaker (16) provided in the vehicle compartment to output a canceling sound to reduce noise in a vehicle compartment (14) of the vehicle (12). The active sound control program includes a reference signal generating unit (52), an adaptive notch filter (54), an error signal input unit (56), a determining unit (60), a reference signal generating unit (58), and a filter coefficient updating unit (60), wherein the reference signal generating unit generates a reference signal that is equal to the noise generated by a noise source. corresponding reference signal; the adaptive notch filter performs adaptive signal processing on the reference signal and generates the control signal; the error signal input unit inputs an error signal, which is equivalent to the cancellation error noise of the cancellation sound and the noise output from the speaker according to the control signal; the determination unit determines the transfer characteristics of the sound in the space inside the vehicle cabin and generates a correction value; the reference signal generation unit corrects the reference signal according to the correction value and generates a reference signal; the filter coefficient updating unit successively updates the filter coefficient of the adaptive notch filter according to the error signal and the reference signal to minimize the error signal.

[0330] In the above-mentioned active sound control program, the device in which the active sound control program downloaded by the communication device is installed may have a microphone (32) that detects the cancellation error noise, and the determination unit determines the transfer characteristics of the sound of the frequency of the reference signal in the transmission path from the speaker to the microphone to generate the correction value.

[0331] In the above-mentioned active sound control program, the device installed with the active sound control program downloaded using the communication device can be connected to the microphone (20), which detects the cancellation error noise, and the determination unit determines the transfer characteristics of the sound of the frequency of the reference signal in the transmission path from the speaker to the microphone to generate the correction value.

[0332] In the above-mentioned active sound control program, the device installed with the active sound control program downloaded by the communication device can have an engine cylinder number input unit (35d) for receiving input of engine cylinder number information, and is connected to an engine speed acquisition unit (19) for detecting the engine speed, and the reference signal generation unit generates the reference signal based on the engine cylinder number and the engine speed.

[0333] In the above-mentioned active sound control program, the device installed with the active sound control program downloaded using the communication device may have a speaker number input unit (35k) and a microphone number input unit (35m), wherein the speaker number input unit receives input of information on the number of speakers; the microphone number input unit receives input of information on the number of microphones, and the number of correction values ​​and the number of filter coefficients are determined based on the number of speakers and the number of microphones.

[0334] In the above-mentioned active sound control program, the device installed with the active sound control program downloaded by the communication device may have an engine cylinder number input unit and an acceleration detection unit (37), wherein the engine cylinder number input unit receives input of information on the number of engine cylinders; the acceleration detection unit detects acceleration, and the reference signal generation unit generates the reference signal based on the engine cylinder number and the acceleration.

[0335] The active sound control program may further include a sound effect generating unit (114) for generating a second control signal for causing the speaker to output a sound effect according to the engine speed.

[0336] In the active sound control program, the processing unit may be caused to function as a sound effect generating unit that generates a second control signal for causing the speaker to output a sound effect based on the acceleration or the speed of the vehicle.

[0337] A microphone detects the cancellation error noise used when causing the processing unit to execute processing according to the active sound control program, is connected via a wired or wireless method to a device installed with the active sound control program downloaded using the communication device, and is detachably installed in the vehicle cabin.

[0338] An engine speed acquisition device (106) acquires the engine speed used when the operation processing device executes processing according to the active sound control program, is connected to the device via a wired or wireless method, and is installed in the vehicle compartment in a detachable manner.

[0339] [Explanation of Reference Numerals]

[0340] 12: Vehicle; 14: Carriage; 16: Speaker; 20, 32: Microphone; 18: Engine (noise source); 19: Engine speed sensor (engine speed acquisition device); 22: Smartphone (communication device); 26: Server; 29: Processing unit; 35d: Engine cylinder number input unit; 35k: Speaker number input unit; 35m: Microphone number input unit; 37: Acceleration sensor (acceleration detection unit); 52: Reference signal generation unit; 54: Control signal generation unit (adaptive notch filter); 56: Error signal input unit; 58: Reference signal generation unit; 60: Control filter coefficient update unit (filter coefficient update unit, determination unit); 106: Vehicle information acquisition device (engine speed acquisition device); 114: Active sound effect control unit (sound effect generation unit).

Claims

1. A non-transitory tangible computer-readable recording medium storing an active sound control program, wherein the active sound control program is downloaded using a communication device (22) for transmitting and receiving data with a server (26), and causes an arithmetic processing unit (29) to execute processing for generating a control signal, wherein: The control signal is used to cause a speaker (16) provided in a vehicle compartment (14) to output a canceling sound to reduce noise in the vehicle compartment (12), and the recording medium is characterized in that: The active sound control program includes a reference signal generating unit (52), an adaptive notch filter (54), an error signal input unit (56), a determining unit (60), a reference signal generating unit (58), and a filter coefficient updating unit (60), wherein: The reference signal generating unit generates a reference signal corresponding to the noise generated by the noise source; The adaptive notch filter performs adaptive signal processing on the reference signal to generate the control signal; The error signal input unit inputs an error signal corresponding to error noise canceling the canceling sound and the noise output from the speaker in response to the control signal; The determination unit determines the sound transfer characteristics in the vehicle interior space and generates a correction value; The reference signal generating unit corrects the reference signal according to the correction value to generate a reference signal; The filter coefficient updating unit updates the filter coefficients of the adaptive notch filter in succession based on the error signal and the reference signal so as to minimize the error signal. The device in which the active sound control program downloaded by the communication device is installed has a microphone (32). The microphone detects the cancellation error noise, The determination unit generates the correction value by determining a transfer characteristic of sound at the frequency of the reference signal in a transmission path from the speaker to the microphone.

2. The non-transitory tangible computer-readable recording medium storing the active sound control program according to claim 1, wherein: The device installed with the active sound control program downloaded by the communication device has an engine cylinder number input unit (35d) for receiving input of engine cylinder number information, and is connected to an engine speed acquisition device for detecting the engine speed. The reference signal generating unit generates the reference signal based on the number of engine cylinders and the engine speed.

3. The non-transitory tangible computer-readable recording medium storing the active sound control program according to claim 1, wherein: The device in which the active sound control program downloaded by the communication device is installed has a speaker number input unit (35k) and a microphone number input unit (35m), wherein: The speaker number input unit receives input of information on the number of speakers. The microphone number input unit receives input of information on the number of microphones. The number of the correction values ​​and the number of the filter coefficients are determined according to the number of the speakers and the number of the microphones.

4. The non-transitory tangible computer-readable recording medium storing the active sound control program according to claim 1, wherein: The device in which the active sound control program downloaded by the communication device is installed has an engine cylinder number input unit and an acceleration detection unit (37), wherein: The engine cylinder number input unit receives input of information on the number of engine cylinders; The acceleration detection unit detects acceleration, The reference signal generating unit generates the reference signal based on the number of engine cylinders and the acceleration.

5. The non-transitory tangible computer-readable recording medium storing the active sound control program according to claim 2, wherein: The active sound control program includes a sound effect generating unit (114) that generates a second control signal for causing the speaker to output a sound effect according to the engine speed.

6. The non-transitory tangible computer-readable recording medium storing the active sound control program according to claim 4, wherein: The arithmetic processing device is caused to function as a sound effect generating unit that generates a second control signal for causing the speaker to output a sound effect based on the acceleration or the speed of the vehicle.

7. A microphone for detecting the cancellation error noise used when causing the arithmetic processing device to execute processing according to the active sound control program according to claim 1 and stored in a non-transitory tangible computer-readable recording medium, characterized in that: The active sound control device is connected to a device installed with the active sound control program downloaded by the communication device via a wired or wireless method, and is detachably installed in the vehicle compartment.

8. An engine speed acquisition device for acquiring the engine speed used when causing the arithmetic processing device to execute processing according to the active sound control program stored in a non-transitory tangible computer-readable recording medium according to claim 2, characterized in that: The device is connected to the apparatus via a wired or wireless method and is installed in the vehicle compartment in a detachable manner.

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