Method and system for estimating active noise control performance of vehicle

Abstract

The invention discloses a method and system for estimating active noise control performance of a vehicle. A method of estimating active noise control performance of a vehicle includes: performing active noise control by reproducing, via a speaker, an acoustic signal for reducing noise introduced into an interior of the vehicle from an exterior of the vehicle and receiving, from a microphone, a residual signal remaining after noise reduction; generating an estimation signal for a control signal for controlling an output of the speaker such that the acoustic signal is reproduced during the active noise control, generating an estimated signal for the original noise prior to the active noise control based on the residual signal and the estimated signal for the control signal, and estimating noise reduction performance based on the estimated signal for the original noise and the residual signal.

Description

Technical Field

[0001] The present disclosure relates to an active noise control system for a vehicle, and more particularly, to a method and system for estimating active noise control performance of a vehicle. Background Art

[0002] Active noise control (ANC) systems use feedforward and feedback structures to attenuate unwanted noise to adaptively remove unwanted noise within a listening environment (such as a vehicle cabin). ANC systems typically eliminate or reduce unwanted noise by generating cancellation sound waves to destructively interfere with unwanted audible noise. When canceling the interference, noise and "anti-noise" of approximately equal amplitude but opposite phase reduce the sound pressure level (SPL) at a certain location. In a vehicle cabin listening environment, potential sources of unwanted noise come from sounds radiated by the engine, the interaction between the vehicle's tires and the road surface on which the vehicle is traveling, and / or sounds caused by vibrations of other components of the vehicle. Therefore, unwanted noise varies depending on the speed of the vehicle, road conditions, and driving conditions.

[0003] An active noise control system for a vehicle is always operated in an on state after the vehicle is produced, and it is impossible to measure the noise level with the active noise control system turned off and thus estimate the noise reduction performance of the active noise control system.

[0004] Therefore, there is a need in the art for a technique for estimating noise reduction performance without turning off an active noise control system of a vehicle even when the active noise control system is in an on state. Summary of the invention

[0005] An object of the present disclosure is to estimate noise reduction performance without turning off an active noise control system of a vehicle even when the system is on.

[0006] Another object of the present invention is to provide active noise control performance in real time.

[0007] Yet another object of the present disclosure is to monitor the performance and stability degradation caused by long-term operation of an active noise control system.

[0008] Yet another object of the present disclosure is to provide information by which past operating history can be checked when maintaining an active noise control system to aid in function development, improvement, and maintenance.

[0009] The objects of the present disclosure are not limited to the above-mentioned objects, and other objects not mentioned will be clearly understood from the following description by those skilled in the art.

[0010] According to one aspect of the present disclosure, the above and other purposes can be achieved by providing a method for estimating the active noise control performance of a vehicle performed by an active noise control (ANC) system, the method comprising performing ANC through a speaker by reproducing an acoustic signal for reducing noise introduced from the outside of the vehicle into the interior of the vehicle and receiving a residual signal remaining after noise reduction from a microphone, generating an estimation signal for a control signal, the control signal being used to control the output of the speaker so that the acoustic signal is reproduced during the ANC, generating an estimation signal for the original noise before the ANC based on the residual signal and the estimation signal for the control signal, and estimating the noise reduction performance based on the estimation signal for the original noise and the residual signal.

[0011] Here, the estimation signal for the original noise may be generated by adding the residual signal to the estimation signal for the control signal.

[0012] Here, the estimation signal for the control signal may be generated by the secondary path model filter based on the output signal of the active filter.

[0013] Here, the output signal of the active filter may be generated by the active filter based on a reference signal generated by the accelerometer, the reference signal filtered by the secondary path model filter, and a residual signal remaining after noise reduction.

[0014] Here, the noise reduction performance may be estimated using a value obtained by subtracting the sound pressure level of the residual noise from the sound pressure level of the estimation signal for the original noise.

[0015] According to another aspect of the present disclosure, an active noise control system for a vehicle is provided, comprising: a processor configured to perform active noise control (ANC) by reproducing an acoustic signal for reducing noise introduced from the outside of the vehicle to the inside of the vehicle through a speaker, and receiving a residual signal remaining after noise reduction from a microphone; generating an estimation signal for a control signal, the control signal being used to control an output of the speaker so that the acoustic signal is reproduced during the ANC, generating an estimation signal for original noise before the ANC based on the residual signal and the estimation signal for the control signal, and estimating noise reduction performance based on the estimation signal for the original noise.

[0016] Here, the estimation signal for the original noise may be generated by adding the residual signal to the estimation signal for the control signal.

[0017] Here, the estimation signal for the control signal may be generated by the secondary path model filter based on the output signal of the active filter.

[0018] Here, the output signal of the active filter may be generated by the active filter based on a reference signal generated by the accelerometer, the reference signal filtered by the secondary path model filter, and a residual signal remaining after noise reduction.

[0019] Here, the noise reduction performance may be estimated using a value obtained by subtracting the sound pressure level of the residual noise from the sound pressure level of the estimation signal for the original noise. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The above and other objects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which:

[0021] Figure 1 is an embodiment showing a typical active noise control (ANC) system;

[0022] Figure 2 is an ANC system showing an embodiment of the present disclosure;

[0023] Figure 3 2 is an illustration of an ANC according to another embodiment of the present disclosure;

[0024] Figure 4 is an example showing active noise control performance of a vehicle that can be displayed on a display screen of an input / output interface according to an embodiment of the present disclosure;

[0025] Figure 5 is a flowchart illustrating an ANC method according to an embodiment of the present disclosure; and

[0026] Figure 6 A computer system is shown according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0027] The present disclosure will be described in detail below with reference to the accompanying drawings. Here, the repetitive description and detailed description of known functions and configurations that may unnecessarily obscure the subject matter of the present disclosure will be omitted. The embodiments of the present disclosure are provided to explain the present disclosure more comprehensively to those skilled in the art. Therefore, for a clearer explanation, the shapes and sizes of the elements in the accompanying drawings may be enlarged.

[0028] Hereinafter, preferred embodiments according to the present disclosure will be described in detail with reference to the accompanying drawings.

[0029] Figure 1 An embodiment of a typical active noise control (ANC) system is shown.

[0030] See also Figure 1 A typical ANC system includes an accelerometer 110 , a primary path filter 120 , a processor 130 , a secondary path filter 140 , a comparator 150 , and a microphone 160 .

[0031] The accelerometer 110 detects vehicle body vibration r from a road surface, generates a reference signal x, and transmits the generated reference signal x to the processor 130 .

[0032] The main path filter 120 transmits the vehicle body vibration r to the microphone 160 in the form of original noise d before control.

[0033] The processor 130 calculates an adaptive algorithm through filtered least mean square (FxLMS) based on a reference signal x generated by the accelerometer 110, outputs a signal, and performs signal processing in a digital domain, such as filtering a secondary path model.

[0034] Here, the processor 130 may be a digital signal processor (DSP).

[0035] The secondary path model filter 131 estimates the transfer function of the secondary path of the secondary path filter 140 and generates a filtering reference signal based on the reference signal x

[0036] The controller 133 receives the estimated reference signal from the secondary path model filter 131 and the residual noise received from the microphone 160 are transmitted to the active filter 135 .

[0037] The active filter 135 is based on the reference signal x received from the accelerometer 110, the filtered reference signal x generated by the secondary path model filter 131, and the reference signal x generated by the secondary path model filter 131. and the controlled residual noise e received from the microphone 160 to generate the active filter output signal u.

[0038] Here, the FxLMS filter coefficients may be updated in real time by the active filter 135 .

[0039] The secondary path filter 140 generates a speaker output control signal y based on the output signal u from the active filter 135 .

[0040] Here, the output control signal y generated by the secondary path filter 140 is a sound wave having the same amplitude and an opposite phase as the original noise d before control, and may be a signal for reducing the original noise d before control.

[0041] The comparator 150 transmits the controlled residual noise e obtained by subtracting the speaker output control signal y from the secondary path filter 140 from the original noise d before control from the main path filter 120 to the microphone 160 .

[0042] The microphone 160 detects the controlled residual noise e and transmits the controlled residual noise e to the processor 230 .

[0043] At the same time, in Figure 1 In the ANC system shown in , only the controlled residual noise e obtained by eliminating the speaker output control signal y from the residual noise d before control can be measured, and the original noise d before control cannot be measured. However, the noise removal performance of the active noise control system can be estimated using a value obtained by subtracting the sound pressure level of the controlled residual noise e from the sound pressure level of the original noise d before control. Therefore, without knowing the original noise d before control, the noise removal performance of the active noise control system cannot be estimated.

[0044] Hereinafter, an active noise control system according to an embodiment of the present disclosure will be described, which can estimate the noise removal performance of the active noise control system by estimating the original noise d before control even in a state where the active noise control system is turned on.

[0045] Figure 2 An ANC system according to an embodiment of the present disclosure is shown.

[0046] See also Figure 2 According to the present embodiment, the ANC system includes an accelerometer 210 , a primary path filter 220 , a processor 230 , a secondary path filter 240 , an adder 250 , and a microphone 260 .

[0047] The accelerometer 210 detects a vehicle body vibration r from a road surface, generates a reference signal x, and transmits the generated reference signal x to the processor 230 .

[0048] The main path filter 220 transmits the vehicle body vibration r to the microphone 260 in the form of original noise d before control.

[0049] The processor 230 calculates an adaptive algorithm through a filtered least mean square (FxLMS) based on a reference signal x generated by the accelerometer 210, outputs a signal, and performs signal processing in a digital domain, such as filtering a secondary path model.

[0050] The first path model filter 231 estimates the transfer function of the secondary path for the secondary path filter 240 and generates a filtered reference signal based on the reference signal x.

[0051] The controller 233 receives the estimated reference signal from the first path model filter 231 and the residual noise received from the microphone 260 are transmitted to the active filter 235 .

[0052] The active filter 235 is based on the reference signal x received from the accelerometer 210, the filtered reference signal x generated by the first path model filter 231, and the reference signal x generated by the first path model filter 231. and the residual noise e after control received from microphone 260 to generate the active filter output signal u.

[0053] Here, the filtered least mean square (FxLMS) filter coefficients may be updated in real time by the active filter 235 .

[0054] The secondary path model filter 236 estimates the transfer function of the secondary path of the secondary path filter 240 and generates an estimation signal for the speaker output control signal y based on the output signal u.

[0055] Here, the second time path model filter 236 is a filter integrated with the first time path model filter 231 and may perform the functions of the first time path model filter 231 and the second time path model filter 236 at the same time.

[0056] The adder 237 adds the estimated signal of the control signal generated by the second path model filter 236 to The residual noise e after control received from the microphone 260 is added to generate an estimated signal of the original noise before control

[0057] Here, the estimated signal of the original noise before control may be estimated as a value close to the original noise before control, as shown in Mathematical Expression 1 below.

[0058] Mathematical expression 1:

[0059]

[0060] In mathematical expression 1, represents the estimated signal of the original noise before control, e represents the controlled residual noise, y represents the control signal for controlling the speaker output, and An estimate signal representing a control signal for controlling the output of a loudspeaker.

[0061] The storage unit 238 stores the estimated signal of the original noise before control Or controlled residual noise e.

[0062] Here, the storage unit 238 may be various types of volatile or nonvolatile storage media.

[0063] The secondary path filter 240 generates a speaker output control signal y based on the output signal u of the active filter 235 .

[0064] Here, the output control signal y generated by the secondary path filter 240 is a sound wave having the same amplitude and an opposite phase as the original noise d before control, and may be a signal for reducing the original noise d before control.

[0065] The comparator 250 transmits the controlled residual noise e obtained by subtracting the speaker output control signal y from the secondary path filter 240 from the original noise d before control from the main path filter 220 to the microphone 260 .

[0066] The microphone 260 detects the controlled residual noise e and transmits it to the processor 230 .

[0067] Figure 3 An active noise control system 300 according to another embodiment of the present disclosure is shown.

[0068] refer to Figure 3 The active noise control system 300 according to this embodiment includes a processor 310 , a microphone 330 , a speaker 350 , an input / output interface 370 , and a memory 390 .

[0069] The processor 310 includes a control signal estimator 313 , a raw noise estimator 315 , and a noise reduction performance estimator 317 .

[0070] The control signal estimator 313 performs ANC by outputting an acoustic signal for reducing noise introduced into the interior from the outside of the vehicle through the speaker, and generates an estimation signal of a control signal for controlling output of the speaker so that the acoustic signal is output when ANC is performed.

[0071] Here, the estimation signal for the control signal may be generated by the secondary path model filter based on the output signal u of the active filter.

[0072] Here, the secondary path model filter may be generated by estimating a transfer function of the secondary path for the secondary path filter.

[0073] Here, the reference signal x received from the accelerometer and the filtered reference signal generated by the secondary path model filter 233 may be used. and the controlled residual noise e after the control received from the microphone to generate the output signal u of the active filter.

[0074] The original noise estimator 315 receives a residual signal remaining after noise reduction from the microphone 330, receives an estimation signal of a control signal for controlling a speaker output from the control signal estimator 313, and generates an estimation signal for original noise based on the residual signal and the estimation signal of the control signal.

[0075] Here, the estimation signal for the raw noise generated by the raw noise estimator 315 may be transmitted to the memory 390 for storage.

[0076] The noise reduction performance estimator 317 estimates the noise reduction performance based on the estimation signal for the original noise.

[0077] Here, the noise reduction performance can be used by controlling the estimated signal for the original noise before The value obtained by subtracting the sound pressure level of the controlled residual noise e from the sound pressure level of .

[0078] Here, the noise reduction performance estimator 317 transmits the noise reduction performance estimation result to the input / output interface 370 , so that the noise reduction performance estimation result can be provided to passengers inside the vehicle through the input / output interface 370 .

[0079] Furthermore, the noise reduction performance estimation result generated by the noise reduction performance estimator 317 may be transmitted to the memory 390 for storage.

[0080] At least one microphone 330 is disposed inside the vehicle to detect external noise generated due to interaction between tires of the vehicle and the road surface.

[0081] Here, the microphone 330 may be provided in, for example, a headrest of a seat, and may be provided in a roof lining of a car or various places to detect noise outside the vehicle.

[0082] Speaker 350 reproduces the anti-noise signal generated by processor 310 for the signal received by microphone 330 .

[0083] The input / output interface 370 provides the noise reduction performance estimated by the noise reduction performance estimator 317 to passengers inside the vehicle.

[0084] For example, the input / output interface 370 is configured as follows: Figure 4 The display screen shown provides noise reduction performance estimates to vehicle occupants.

[0085] The memory 390 may be different types of volatile or nonvolatile storage media. Here, the memory 390 stores at least one of an estimation signal of a control signal for controlling speaker output, an estimation signal for original noise, a noise reduction performance estimation result, or a combination thereof.

[0086] Figure 5 FIG. 1 is a flow chart showing an active noise control (ANC) method according to an embodiment of the present disclosure. The active noise control method according to this embodiment may be performed by Figure 3 Executed by processor 310.

[0087] refer to Figure 5, at S510 , the processor 310 performs active noise control (ANC) by reproducing an acoustic signal for reducing noise introduced from the outside of the vehicle to the inside through a speaker, and receives a residual signal remaining after noise reduction from a microphone.

[0088] For example, the processor 310 generates a sound wave having the same amplitude and opposite phase as the noise outside the vehicle to be transmitted to the passengers inside the vehicle, and reproduces the sound wave through the speaker 250 to reduce the noise outside the vehicle.

[0089] Here, the processor 310 may use the actual sub-path S (multiple sub-paths S) as the electrical and acoustic paths between the speaker 350 and the microphone 330 and use the sub-path model as a digital filter obtained by measuring the actual sub-path by the DSP and modeling it into a transfer function. The sub-path model algorithm is used to reduce the noise outside the vehicle.

[0090] Furthermore, at S520 , the processor 310 generates an estimation signal of a control signal for controlling an output of the speaker so that the acoustic signal is reproduced during the ANC.

[0091] Here, the estimation signal for the control signal may be generated by the secondary path model filter based on the output signal of the active filter.

[0092] Here, the output signal of the active filter may be generated by the active filter based on a reference signal generated by the accelerometer, the reference signal filtered by the secondary path model filter, and a residual signal remaining after noise reduction.

[0093] Furthermore, at S530 , the processor 310 generates an estimation signal for original noise before ANC based on the residual signal and the estimation signal for the control signal.

[0094] Here, the estimation signal for the original noise may be generated by adding the residual signal to the estimation signal for the control signal.

[0095] Furthermore, at S540 , the processor 310 estimates noise reduction performance based on the estimation signal for the original noise.

[0096] Here, we can use the estimated signal from the original noise before control The noise reduction performance is estimated by subtracting the sound pressure level of the controlled residual noise e from the sound pressure level of the sound pressure level.

[0097] Furthermore, at S550 , the processor 310 provides the noise reduction performance estimation result to the occupants inside the vehicle.

[0098] Here, the processor 310 transmits the noise reduction performance estimation result to the input / output interface 370 , and can provide the noise reduction performance estimation result to passengers inside the vehicle through the input / output interface 370 .

[0099] Figure 6 A computer system according to an embodiment of the present disclosure is shown.

[0100] refer to Figure 6 , the embodiments of the present disclosure may be implemented in a computer system such as a computer readable recording medium. Figure 6 As shown in , the computer system 600 includes a processor 610 , an input / output interface 630 , and a memory 650 .

[0101] The processor 610 implements the active noise control performance estimation method for a vehicle proposed in this specification. Specifically, the processor 610 implements all operations of the processor 310 in the active noise control system 300 described in the embodiment of the present disclosure and executes the following operations: Figure 5 All operations of the active noise control performance estimation method.

[0102] For example, the processor 610 performs ANC by reproducing an acoustic signal for reducing noise introduced from the outside of the vehicle to the inside via a speaker, receiving a residual signal remaining after noise reduction from a microphone, generating an estimation signal for a control signal, the control signal being used to control the output of the speaker so that the acoustic signal is reproduced during the ANC, generating an estimation signal for the original noise before ANC based on the residual signal and the estimation signal for the control signal, and estimating the noise reduction performance based on the estimation signal for the original noise.

[0103] Here, the estimation signal for the original noise may be generated by adding the residual signal to the estimation signal for the control signal.

[0104] Here, the estimation signal for the control signal may be generated by the secondary path model filter based on the output signal of the active filter.

[0105] Here, the output signal of the active filter may be generated by the active filter based on a reference signal generated by the accelerometer, the reference signal filtered by the secondary path model filter, and a residual signal remaining after noise reduction.

[0106] Here, the noise reduction performance may be estimated using a value obtained by subtracting the sound pressure level of the residual noise from the sound pressure level of the estimation signal for the original noise.

[0107] The input / output interface 630 is connected to the processor 610 and directly obtains information or provides information to a user. For example, the input / output interface 630 provides the noise reduction performance estimation result to the occupants in the vehicle.

[0108] The memory 650 may be different types of volatile or nonvolatile storage media. Here, the memory 650 stores at least one of an estimation signal of a control signal for controlling speaker output, an estimation signal for original noise, a noise reduction performance estimation result, or a combination thereof.

[0109] According to the above-described embodiments of the present disclosure, even when the system is in an on state, it is possible to estimate the noise reduction performance in real time and store the performance history without turning off the active noise control system and affecting the usability.

[0110] Furthermore, the target value can be used to provide customers with the effect of the active noise control function.

[0111] Furthermore, the performance and stability degradation caused by long-term operation of the active noise control system can be monitored.

[0112] In addition, information on past operating history can be checked when maintaining the active noise control system to assist in function development, improvement, and maintenance.

[0113] The present disclosure can be implemented as computer readable code on a program recording medium. Computer readable media include all types of recording devices that store data that can be read by a computer system. Embodiments of computer readable media include hard disk drives (HDDs), solid state drives (SSDs), silicon disk drives (SDDs), ROMs, RAMs, CD-ROMs, magnetic tapes, floppy disks, optical data storage devices, etc.

[0114] Therefore, the above detailed description should not be interpreted as limiting in all aspects, but should be regarded as illustrative. The scope of the present disclosure should be determined by reasonable interpretation of the appended claims, and all changes within the equivalent range of the present disclosure are included in the scope of the present disclosure.

Claims

1. A method for estimating active noise control performance of a vehicle performed by an active noise control system, the method comprising: performing active noise control by a processor by reproducing an acoustic signal through a speaker and receiving a residual signal remaining after noise reduction from a microphone, wherein the acoustic signal is used to reduce noise introduced from an exterior of the vehicle into an interior of the vehicle; generating an estimation signal for a control signal, wherein the control signal is used to control an output of the loudspeaker so that the acoustic signal is reproduced during active noise control; generating an estimation signal of original noise before the active noise control based on the residual signal and the estimation signal for the control signal; and A noise reduction performance is estimated based on the estimation signal for the original noise and the residual signal.

2. The method according to claim 1, wherein: The estimated signal for the original noise is generated by adding the residual signal to the estimated signal for the control signal.

3. The method according to claim 1, wherein: The estimation signal for the control signal is generated by a secondary path model filter based on an output signal of an active filter.

4. The method according to claim 3, wherein: The output signal of the active filter is generated by the active filter based on a reference signal generated by an accelerometer, the reference signal filtered by the secondary path model filter, and a residual signal remaining after noise reduction.

5. The method according to claim 1, wherein: The noise reduction performance is estimated using a value obtained by subtracting the sound pressure level of the residual noise from the sound pressure level of the estimation signal for the original noise.

6. An active noise control system for a vehicle, comprising a processor, the processor being configured to: Active noise control is performed by reproducing an acoustic signal via a speaker, and receiving a residual signal remaining after noise reduction from a microphone, wherein The acoustic signal is used to reduce noise introduced into the interior of the vehicle from the exterior of the vehicle; generating an estimation signal for a control signal, wherein the control signal is used to control an output of the loudspeaker so that the acoustic signal is reproduced during active noise control; generating an estimation signal of original noise before the active noise control based on the residual signal and the estimation signal for the control signal; and A noise reduction performance is estimated based on the estimation signal for the original noise.

7. The active noise control system according to claim 6, wherein: The estimated signal for the original noise is generated by adding the residual signal to the estimated signal for the control signal.

8. The active noise control system according to claim 6, wherein: The estimation signal for the control signal is generated by a secondary path model filter based on an output signal of an active filter.

9. The active noise control system according to claim 8, wherein: The output signal of the active filter is generated by the active filter based on a reference signal generated by an accelerometer, the reference signal filtered by the secondary path model filter, and a residual signal remaining after noise reduction.

10. The active noise control system according to claim 6, wherein: The noise reduction performance is estimated using a value obtained by subtracting the sound pressure level of the residual noise from the sound pressure level of the estimation signal for the original noise.

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