Active noise cancellation system and method for external noise reduction

Abstract

A system for vehicle exterior noise reduction, comprising: a measuring component for measuring an amplitude and a phase of an exterior noise, the exterior noise propagating at least partially in a first direction from at least one exterior noise source of a vehicle and having an acoustic transmission path, wherein the exterior noise propagates at least partially below a bottom of the vehicle; a computing component for computing an out-of-phase signal based at least in part on the measured amplitude and phase of the exterior noise; and a generating component for generating an out-of-phase sound based at least in part on the computed out-of-phase signal, the out-of-phase sound configured to cancel the exterior noise, wherein the generated out-of-phase sound propagates at least partially in the first direction of the acoustic transmission path.

Description

Technical Field

[0001] This disclosure generally relates to systems, methods, and computer programs for active noise cancellation to reduce external noise in vehicles. Background Technology

[0002] Many consider the external noise of vehicles in operation to be a characteristic sound, sometimes associated with the driver's enthusiasm. For others, such as cyclists and pedestrians, the external noise of vehicles may be important for them to perceive approaching vehicles early enough (especially from out-of-sight directions) to react accordingly and exercise caution (i.e., for road safety reasons). However, on the other hand, the presence of multiple wheeled vehicles such as trucks, cars, and motorcycles generates considerable traffic noise. Especially in densely populated urban areas, constant noise can pose a serious threat to human health. Therefore, in some scenarios, it is desirable to reduce the external noise of vehicles in operation in a way that, on the one hand, reduces noise pollution, while on the other hand, allows drivers to still enjoy the sound of vehicle engines, and allows other road users, such as cyclists and pedestrians crossing the street, to perceive approaching vehicles in a timely manner. Furthermore, in order to achieve rapid market penetration and thus reduce traffic noise for as many people as possible in markets around the world, the corresponding solutions should be cost-effective and easy to implement.

[0003] Active noise cancellation systems reduce unwanted noise by generating out-of-phase sound waves in response to the incident wave of the unwanted sound. Sound is typically a pressure wave, consisting of alternating compression and expansion cycles. The noise cancellation loudspeaker emits sound waves with the same amplitude but opposite phases towards the original sound (the unwanted sound). The combined waves cancel each other out through destructive interference.

[0004] While various developments exist for reducing vehicle-internal noise (i.e., noise inside the vehicle), no solution has been found that effectively reduces vehicle-external noise (e.g., tire external noise). In particular, using active noise cancellation systems to provide predictive methods for noise cancellation (i.e., based on numerical tire and road models) is complex to implement. For example, accurately predicting road roughness at a given time can be problematic.

[0005] For example, an example of such a prediction method is disclosed in JP 209119375A. In this document, for example, a control unit is disclosed that is characterized by predicting the noise when the tire contacts the road surface, wherein the tire is distinguished in relation to the vehicle's movement to generate a noise-canceling signal.

[0006] Furthermore, in EP 3349210A1, an active noise reduction device for a vehicle includes: a detection device configured to detect at least one reference signal indicating at least one component of noise generated at a contact area between the vehicle's wheels and the track on which the vehicle is traveling; a sound emitting device for emitting sound waves toward at least one contact area between the vehicle's wheels and the track on which the vehicle is traveling; and a control device operatively coupled to the detection device and the sound emitting device. The control device is further configured to control the sound emitting device for emitting sound waves based on the detected at least one reference signal, to reduce at least one component of the noise through active noise cancellation of the emitted sound waves. To address some noise issues that are important for road safety, the control device disclosed in EP 3349210A1 can be configured to determine at least one exempt frequency based on the detected at least one reference signal, wherein the reference signal indicates a characteristic road marking on the track on which the vehicle is traveling. The control device then controls the sound emitting device not to emit sound waves having the determined at least one exempt frequency. However, this method is inadequate in improving road safety for other road users outside the vehicle, such as cyclists and pedestrians.

[0007] As mentioned earlier, these systems are complex to implement in practice. Furthermore, these systems eliminate noise even in directions where other road users can perceive it. This can reduce overall road safety, especially for cyclists and pedestrians, especially since these roads often lack undulations. Therefore, a simple and cost-effective alternative solution is needed to reduce unwanted vehicle external noise in some directions while maintaining desired noise levels in others. Summary of the Invention

[0008] The above objectives are achieved by the system, method or computer program disclosed herein for reducing external noise of a vehicle.

[0009] According to a first aspect, the present invention provides a system for reducing external noise of a vehicle. The system may include components for measuring the amplitude and phase of external noise, which propagates at least partially from at least one external noise source of the vehicle in a first direction and has an acoustic transmission path, wherein the external noise can propagate at least partially below the bottom of the vehicle. The system may include components for calculating an out-of-phase signal based on the measured amplitude and phase of the external noise. Additionally, the system may include components for generating out-of-phase sound, which generates out-of-phase sound at least partially based on the calculated out-of-phase signal, the out-of-phase sound being configured to cancel external noise, wherein the generated out-of-phase sound can propagate at least partially in the first direction of the transmission path, wherein, within a plane formed by the bottom of the vehicle, the first direction is preferably perpendicular or substantially perpendicular to the vehicle's direction of travel.

[0010] Typically, out-of-phase sound waves have the same amplitude but opposite phase as the sound waves to be eliminated (e.g., unwanted external noise).

[0011] In addition, external noise can also be referred to as external noise sound, unwanted noise, or undesirable noise, among which out-of-phase sound can also be referred to as out-of-phase sound waves or destructive waves.

[0012] By generating out-of-phase sound propagating in a similar propagation direction to the external noise (e.g., a first direction of the transmission path) based on the calculated actual noise (i.e., without requiring cumbersome and potentially inaccurate predictions), this out-of-phase sound is configured to cancel the external noise along that direction. Therefore, the present invention provides an active noise cancellation system capable of efficiently responding to the amplitude and phase of measured external noise.

[0013] On the other hand, the driver's auditory experience may be unaffected by systems designed to reduce external noise from the vehicle. Furthermore, in this case, external noise from the vehicle in directions other than the primary direction is not eliminated. Therefore, on the one hand, unwanted external noise is reduced, while noise in other desired directions is maintained. This is particularly important for other road users (such as cyclists or pedestrians, especially distracted individuals, children, or people with disabilities, such as the blind) who rely on road noise to perceive approaching vehicles (especially those approaching from directions outside their line of sight).

[0014] Alternatively, the component used for measurement may include a microphone.

[0015] On the other hand, the component used for calculation may include a controller.

[0016] On the other hand, the components used to generate the product may include a speaker.

[0017] On the other hand, an external noise source could be the tires of a vehicle, which are configured to generate external noise through the interaction between the tires and the road.

[0018] This invention allows for the elimination of external noise originating from the tires of a vehicle. In particular, this invention allows for the elimination of external noise that may propagate at least partially in a first direction of the transmission path, wherein the external noise may propagate at least partially beneath the bottom of the vehicle.

[0019] According to another perspective, the component used for measurement can be located in a position along the first direction of the transmission path.

[0020] On the other hand, the measuring component can be located at the bottom of the vehicle.

[0021] According to another perspective, the component used for generation can be located at a position along the first direction of the transmission path.

[0022] Advantageously, out-of-phase sound can be generated within a distance relative to an external noise source. The external noise sound can travel along a first direction of the transmission path and pass through the generating component located along the first direction of the transmission path. Therefore, out-of-phase sound can be generated to cancel out the external noise as the external noise passes through the generating component.

[0023] On the other hand, the components used for generation can be located at the bottom of the vehicle.

[0024] Therefore, the component used for generation can be located within a distance relative to the location of the external noise source and the component used for measurement, where the external noise requires a certain time span to reach the component used for generation. This time span can be used to measure the external noise and calculate the out-of-phase signal.

[0025] Typically, the location of the measuring component combined with the location of the generating component defines a first direction of the transmission path along which external noise is measured and out-of-phase sound is generated. The ability to selectively position the measuring and / or generating components on the bottom of the vehicle provides a choice of different directions of the transmission path, along which external noise can be measured and out-of-phase sound can be generated.

[0026] Typically, a combination of multiple measurement components, multiple calculation components, and multiple generation components can be arranged to eliminate external noise from at least one external noise source of the vehicle in multiple directions, the external noise having an acoustic transmission path, wherein the external noise can propagate at least partially below the bottom of the vehicle.

[0027] Furthermore, the combination of additional components for measurement / calculation / generation can also be arranged to eliminate external noise from additional external noise sources of the vehicle in at least one direction, the external noise having an acoustic transmission path, wherein the external noise can propagate at least partially below the bottom of the vehicle.

[0028] On the other hand, the component used for generation can be located at the edge of the wheel arch.

[0029] On the other hand, the component used for generation can be located at the mudguard.

[0030] On the other hand, the component used for generation can be located at the edge of the bumper.

[0031] Alternatively, the components used for generation can be located on the side of the vehicle.

[0032] According to another aspect, the component used for measurement can be located between the component used for generation and the external noise source, and / or the component used for measurement can be located closer to the external noise source than the component used for generation.

[0033] By arranging a measurement component between the generation component and the external noise source, the external noise sound passes through the measurement component before the generation component. Therefore, a time span is provided for the external noise measurement and out-of-phase signal calculation to generate the out-of-phase sound. As a result, the active noise cancellation system is able to generate out-of-phase sound based on the measured external noise to be canceled. In other words, the need for complex and potentially inaccurate predictive analysis is avoided. Therefore, the system can provide out-of-phase sound based on the response to external noise rather than solely on the predictive process.

[0034] According to another aspect, the system may further include (i) a second component for measuring the amplitude and phase of external noise, the external noise propagating at least partially from the at least one external noise source of the vehicle in a second direction, the external noise having the acoustic transmission path, wherein the external noise propagates at least partially below the bottom of the vehicle, wherein the component for calculating the out-of-phase signal may be configured to calculate an additional out-of-phase signal based on the measured amplitude and phase of the external noise propagating in the second direction, and / or the system may include (ii) a second component for generating an additional out-of-phase sound at least partially based on the calculated additional out-of-phase signal, the additional out-of-phase sound being configured to cancel the external noise, wherein the generated additional out-of-phase sound propagates at least partially in the second direction of the acoustic transmission path.

[0035] The use of a second component for measurement allows for the measurement of external noise that propagates at least partially in an additional direction (e.g., a second direction) compared to the first direction. Additionally, the use of a second component for generation allows for the generation of additional out-of-phase sound that propagates at least partially in the additional second direction of the acoustic transmission path, thereby eliminating noise propagating in the additional second direction.

[0036] According to another aspect, the components used for calculation can calculate the out-of-phase signal based on at least one of the incident wave, system characteristics, external acoustics of the vehicle, the position of the component used to generate the out-of-phase sound, the position of the component used for measurement, and / or the acoustic transmission path of external noise.

[0037] By using various parameters to calculate out-of-phase signals, improved active noise cancellation efficiency is achieved.

[0038] According to another approach, the calculations can be based at least in part on the external acoustics of the vehicle, calibrated for the vehicle itself.

[0039] Calibrating the vehicle's external acoustics is beneficial because noise cancellation depends not only on the relative positions of the components used for measurement and those used for generation, but also on the vehicle's own external acoustics. Specifically, for a given configuration of the components used for measurement and those used for generation, the calculation of out-of-phase sounds must also take into account the vehicle and its external acoustics. Calibration of the vehicle's external acoustics provides setup information for the components used in the calculations specific to the vehicle's noise cancellation system. However, if the vehicle or noise cancellation system configuration changes, a new calibration is required.

[0040] According to another approach, the component used for calculation can calculate the out-of-phase signal in the calculation time, which can be less than the transmission time required for external noise to reach the location of the component used for generation.

[0041] Specifically, the transmission time represents the time span required for external noise to travel the distance between the measuring component and the generating component. Providing a computation time shorter than the transmission time allows the active noise cancellation system to respond to external noise. Advantageously, if the computation time for calculating the out-of-phase signal is shorter than the transmission time, the generating component can generate out-of-phase sound when external noise (to which the out-of-phase signal is calculated) passes through the generating component. Therefore, the generated out-of-phase signal is configured to cancel the external noise as it passes through the generating component.

[0042] According to another aspect, the present invention provides a method for reducing external noise of a vehicle, the method comprising measuring the amplitude and phase of external noise that propagates at least partially from at least one external noise source of the vehicle in a first direction and has an acoustic transmission path, wherein the external noise propagates at least partially below the bottom of the vehicle. The method may include calculating an out-of-phase signal based at least on the measured amplitude and phase of the external noise. Additionally, the method may include generating out-of-phase sound at least partially based on the calculated out-of-phase signal, the out-of-phase sound being configured to cancel the external noise, wherein the generated out-of-phase sound propagates at least partially in the first direction of the transmission path.

[0043] By generating out-of-phase sound that propagates in the same direction as external noise, this out-of-phase sound is configured to cancel the external noise in that direction. The present invention provides an active noise cancellation method capable of responding to measured external noise by generating out-of-phase sound based on external noise measurements and out-of-phase signal calculations.

[0044] According to another aspect, the calculation of out-of-phase signals can also be based on at least one of the following: incident wave, system characteristics, external acoustics of the vehicle, the position of the component used to generate out-of-phase sound, the position of the component used to measure the amplitude and phase of external noise, and / or the acoustic transmission path of external noise.

[0045] According to another approach, the calculations can be performed at least in part based on the external acoustics of the vehicle, which can be calibrated for the vehicle.

[0046] Further calculations were performed using the vehicle's external acoustics after calibration, which enabled improved active noise cancellation efficiency.

[0047] On the other hand, calculating out-of-phase signals may require less computation time than the time it takes for external noise to travel to the location where the out-of-phase sound is generated.

[0048] Specifically, the transmission time represents the time span required for external noise to travel the distance between the location of the out-of-phase sound and the location where the out-of-phase sound was generated.

[0049] Advantageously, if the computation time for calculating the out-of-phase signal is less than the transmission time, the out-of-phase signal can be provided before the external noise passes the location where the out-of-phase sound is generated. Therefore, out-of-phase sound can be generated simultaneously with the external noise passing the location where the out-of-phase sound is generated.

[0050] According to another aspect, the present invention provides a computer program including instructions that, when executed by a computer, cause the computer to perform a method for active noise cancellation according to any of the foregoing aspects.

[0051] Other benefits and advantages of the invention will become apparent after a careful reading of the detailed description with appropriate reference to the accompanying drawings. Attached Figure Description

[0052] Figure 1 This example illustrates a typical pass-by-noise tire noise spectrum.

[0053] Figure 2 Two lateral transmission paths for external noise of a vehicle are illustrated according to embodiments of the present invention.

[0054] Figure 3 An example of an active noise cancellation system according to an embodiment of the present invention is shown.

[0055] Figure 4 An example of an active noise cancellation system according to an embodiment of the present invention is shown.

[0056] Figure 5 This example illustrates a typical finite element method (FEM) simulation model of an acoustic tire and vehicle.

[0057] Figure 6 The results of the acoustic simulation are shown.

[0058] Figure 7 A flowchart illustrating a method for reducing external noise of a vehicle according to an embodiment of the present disclosure is shown. Detailed Implementation

[0059] This disclosure provides systems, methods, and computer programs for reducing external noise of vehicles. The systems and methods according to this disclosure offer numerous advantages. The invention allows for the elimination of external noise (e.g., tire noise contribution) by generating out-of-phase sounds relative to sounds generated by external noise sources. In particular, the invention provides systems, methods, and computer programs configured to eliminate external noise on the opposite side of the vehicle relative to an external noise source.

[0060] Figure 1 This example illustrates a typical pass-by-noise (PbN) tire noise spectrum. External tire noise is generated during rolling through the interaction between the tire and the road, and propagates through the air towards the outside of the vehicle. External noise levels have a significant impact on the environment and are quantified using standard testing methods such as the PbN test. Therefore, to characterize the overall acoustic features of a vehicle, measurements are taken while the vehicle is in motion via a fixed microphone. In a typical PbN test, the tire noise spectrum exhibits high energy content in the frequency range of 500 to 2000 Hz, which is correlated with specific noise mechanisms (mode noise, tube resonance, stick-slip) within this band.

[0061] Figure 2 Two lateral transmission paths for external noise of a vehicle according to embodiments of the present invention are illustrated. Typically, tires emit noise in all directions, where the amplitude of the noise depends on its directionality.

[0062] This invention focuses on two lateral transmission paths of particular concern for external noise cancellation (e.g., for pedestrians), namely, the air path from the tire source to the external noise receiver should be considered. Figure 2 An exemplary transmission path from an external noise source 231 (e.g., tire surface) to an external receiver 202 (e.g., external microphone) of the vehicle 200 is shown, corresponding to direct path 220. In direct path 220, external receiver 202 and external noise source 231 are on the same side of vehicle 200. Since it is impossible to place any measurement components (e.g., sensors, microphones) / computation components (e.g., controllers) / generation components (e.g., speakers) system between external noise source 231 and external receiver 202, this contribution can hardly be reduced by active cancellation techniques.

[0063] The advantage of this method is a significant reduction in noise levels on the lateral side of the vehicle. On the other hand, the driver's auditory experience is unaffected by the system used to reduce external noise from the vehicle. Furthermore, it does not eliminate external noise from the vehicle in directions other than the lateral direction. Therefore, it reduces unwanted external noise while maintaining noise in other desired directions. This is particularly important for other road users, such as cyclists or pedestrians (especially distracted individuals, children, or people with disabilities, such as the blind), who rely on road noise to perceive approaching vehicles (especially those approaching from out of sight).

[0064] In particular, Figure 2 The diagram illustrates the transmission path from an external noise source 231 (e.g., a tire) to an external receiver 201 on the opposite side of the vehicle 200, corresponding to the opposite side path 210. For example, external noise generated by the right front tire propagates towards the left side of the vehicle. The external noise passes under the vehicle, where it can be attenuated using sound cancellation techniques. Typically, the contribution of the opposite side tire may be related to the overall external noise of the vehicle.

[0065] Note that although Figure 2 shows the transmission path for external receivers on the lateral opposite sides of the vehicle, the same principle applies if noise is considered (and intended to be eliminated) in the longitudinal direction of the vehicle. For example, external noise generated by the right front tire propagates toward the rear of the vehicle. The external noise passes under the vehicle, where it can be attenuated using the described sound cancellation techniques. Active noise cancellation in different directions can be controlled based on different traffic scenarios (e.g., at least in part based on vehicle speed or GPS data). For example, at low speeds, noise cancellation in front of and behind the vehicle can be disabled (to improve road safety for cyclists and pedestrians), while at high speeds, noise cancellation in front of and behind the vehicle can be enabled (e.g., on congested highways in urban areas).

[0066] Figure 3 An example of an active noise cancellation system according to an embodiment of the present invention is shown.

[0067] In some embodiments, the active noise cancellation system 300 can reduce unwanted external noise 301 by generating out-of-phase sound 302 against the incident wave of external noise 301. Additionally, the active noise cancellation system 300 may include a component 320 for measuring the external noise 301 and a component 330 for calculating the out-of-phase signal. Then, the generation component 340 uses the out-of-phase signal to generate out-of-phase sound to cancel the external noise 301.

[0068] External noise 301 originates from at least one external noise source 310, at least partially, in a first direction ( Figure 3 The external noise 301 propagates at least partially from at least one external noise source 310 in the first direction 311. The measuring component 320 measures the amplitude and phase of the external noise 301, which propagates at least partially from at least one external noise source 310 in the first direction 311. The calculating component 330 then uses the measured amplitude and phase of the external noise 301 to calculate an out-of-phase signal. The calculated out-of-phase signal is used by the generating component 340 to generate an out-of-phase sound 302, which propagates at least partially from the external noise source in the first direction 311. In the plane formed by the bottom of the vehicle, the first direction may be perpendicular or substantially perpendicular to the vehicle's direction of travel. Therefore, the generated out-of-phase sound 302 is configured to cancel the external noise 301 by interference.

[0069] exist Figure 3 In this configuration, the component 340 used for generating the noise is located between the external receiver 350 and the external noise source 310. As a result, the external receiver 350 does not perceive, or at least perceives, a significantly reduced amount of external noise. Figure 3The illustrated embodiment provides an active noise cancellation system 300 that generates out-of-phase sounds based on a response to measured external noise.

[0070] In another embodiment, the generated out-of-phase sound depends not only on the measured external noise but also on additional parameters. Specifically, the components used for calculation can calculate the out-of-phase signal based on at least one of the following: incident wave, system characteristics, vehicle external acoustics, the location of the component used to generate the out-of-phase sound, the location of the component used for measurement, and / or the acoustic transmission path of the external noise.

[0071] Figure 4 An active noise cancellation system according to an embodiment of the present invention is described. Specifically, Figure 4 An example of a system for actively eliminating external tire noise is shown, where the contribution of the left front tire 410 is considered the sole noise source. This concept can also be extended to contributions from other tire sources.

[0072] according to Figure 4 A system for reducing external noise of a vehicle includes a component 420 for measuring the amplitude and phase of external noise, which propagates at least partially from at least one external noise source 410 of the vehicle 400 in a first direction (indicated by arrow 411 in the figure) and has an acoustic transmission path, wherein the external noise 401 propagates at least partially below the bottom of the vehicle 400. The system also includes a component for calculating out-of-phase signals (based on the measured amplitude and phase of the external noise 401) at least partially. Figure 4 The components (not explicitly shown in the text) and components 440 for generating out-of-phase sound 402 based at least in part on the calculated out-of-phase signal, the out-of-phase sound being configured to eliminate external noise 401, wherein the generated out-of-phase sound 402 propagates at least in part in the first direction 411 of the transmission path.

[0073] like Figure 4 As shown, external noise 401 propagates at least partially to the opposite side of the vehicle 400 by passing through the bottom of the vehicle. In this particular embodiment, the generated out-of-phase sound 402 propagates at least partially in the first direction 411 of the transmission path and at least partially below the bottom of the vehicle.

[0074] like Figure 4 As shown, external noise propagates from external noise source 410 to external receiver 450, wherein external receiver 450 is located on the opposite side of the vehicle compared to the side with external noise source 410. Therefore, the configuration of the components for measurement, calculation, and generation can be arranged to eliminate external noise at the location of the external receiver.

[0075] According to another embodiment, the component 420 for measurement may include a microphone.

[0076] According to another embodiment, the component used for calculation may include a controller.

[0077] According to another embodiment, the component 440 used for generation may include a speaker.

[0078] exist Figure 4 In this configuration, the measuring component 420 is located at the bottom of the vehicle along a first direction 411 of the transmission path. Furthermore, the measuring component 420 is positioned close to the tire 410 (e.g., wheel arch) and intercepts tire noise to measure amplitude and phase.

[0079] exist Figure 4 In this process, the component 440 used for generation is located at a position along the first direction 411 of the transmission path and is located on the bottom of the vehicle 400.

[0080] According to another embodiment, the component used for generation can be located on the edge of the wheel arch, fender, bumper edge, or side of the vehicle. Typically, the location of the component used for generation depends on the direction from which the out-of-phase sound should be primarily transmitted, while ensuring a safe location on the vehicle (e.g., a location to prevent damage from external sources).

[0081] Typically, one or more components for generation can be used for active noise cancellation. Using multiple components for generation allows for more complex sound directionality patterns, including more than one preferred direction (e.g., using dipoles or quadrupoles with monopoles). In particular, the location and / or number of components used for generation, or in other words, the layout formed by the components used to generate out-of-phase sound, can be the result of an optimization / calibration process, where different layouts are evaluated to minimize noise at the location of the external receiver. Layout optimization can be aided by numerical simulations. In particular, depending on the complexity of the sound field, more components (e.g., loudspeakers) may be needed for generation. The sound field depends on frequency, where the complexity of the sound field increases with frequency.

[0082] In some embodiments, the measuring component 420 may be located between the generating component 440 and the external noise source 410. Thus, an active noise cancellation system configured to respond to certain noises rather than merely predicting corresponding out-of-phase sounds is provided.

[0083] exist Figure 4 In the specific embodiment shown, the component 440 for generating the noise is positioned between the source 410 (e.g., a tire) and the receiver 450 (i.e., the exterior of the vehicle). This configuration allows for the elimination of reactive noise on the “opposite side” of the vehicle, where external noise must at least partially propagate beneath the bottom of the vehicle.

[0084] According to some embodiments, the components used for calculation can receive the measured signal and calculate the out-of-phase signal by taking into account the incident wave, the speaker position, and the acoustic transmission path under the vehicle.

[0085] According to another embodiment, the calculations can be performed at least in part based on the external acoustics of the vehicle 400, calibrated for the vehicle 400. Calibrating the external acoustics of the vehicle is advantageous because noise cancellation depends not only on the relative positions of the microphone 420 / speaker 440 but also on the external acoustics of the vehicle 400 itself. In particular, for a given configuration of the components used for measurement and the components used for generation, the calculation of out-of-phase sounds must also take into account the vehicle and its external acoustics. Calibrating the external acoustics of the vehicle provides setup information for the components used in the calculations to a specific vehicle noise cancellation system. However, if the configuration of the vehicle or noise cancellation system changes, a new calibration is required.

[0086] According to another embodiment, the component used for calculation can calculate the out-of-phase signal within a calculation time, which can be less than the transmission time required for external noise to reach the location of the component 440 used for generation. Calculation time is critical for the calculation because the out-of-phase signal should be calculated before the external noise sound wave reaches the speaker location 440 (i.e., the calculation time is less than the microphone-speaker-distance / speed of sound). For example, considering a distance of 0.5m from the microphone to the speaker, the calculation time should be less than 1.5ms.

[0087] Figure 5 This diagram illustrates a typical finite element method (FEM) acoustic simulation model of a tire and vehicle. Specifically, the simulation aims to reproduce the sound field generated by the tire (in terms of amplitude / phase and directionality). The sound field is calculated starting with the complex vibrational field of the tire (a dedicated tire FEM simulation including all patterned structural features), which thus represents the boundary conditions of the simulation itself. The interaction with the vehicle, and the propagation of noise in space, are then considered. Specific FEM acoustic techniques can be used (e.g., using a perfectly matching layer or equivalent in a way that only a thin layer of air needs to be modeled). The ground is modeled as a perfectly reflective plane, such as the external surface of the vehicle (but some impedance characteristics can also be given). This simulation will allow visualization of the sound field propagating beneath the vehicle and quantification of the effectiveness of noise cancellation devices. Figure 5 In this model, an exemplary simulated active control system can be illustrated by simulating tire noise 510 propagating to an external receiver 550 and by simulating out-of-phase sounds generated by a component 540 for generation.

[0088] Figure 6The results of the acoustic simulation are shown. The solid line represents the spectrum of the external receiver 550 (e.g., the target microphone) due to tire noise 510. The dashed line illustrates the spectrum of the external receiver 550 considering both tire noise and heterodyne noise from the component 540 used for generation. In this case, the component 540 used for generation has been simulated as a single-pole source located at the bottom of the vehicle, generating noise with equal amplitude and opposite phase relative to the tire noise 510.

[0089] Figure 700 shows a flowchart illustrating a method for reducing external noise of a vehicle according to an embodiment of the present disclosure.

[0090] Figure 7 The method shown is for illustrative purposes only. In step 710, the amplitude and phase of external noise are measured, which propagates at least partially from at least one external noise source of the vehicle in a first direction and has an acoustic transmission path, wherein the external noise propagates at least partially below the bottom of the vehicle.

[0091] In a further step 720, the out-of-phase signal is calculated at least in part based on the measured amplitude and phase of the external noise. In some embodiments, the calculation of the out-of-phase signal may also be based at least on one of the following: incident wave, system characteristics, vehicle external acoustics, the location of the component generating the out-of-phase sound, the location of the component measuring the amplitude and phase of the external noise, and / or the acoustic transmission path of the external noise. In some additional embodiments, the calculation may be based at least in part on vehicle external acoustics calibrated for the vehicle. In some other embodiments, the calculation of the out-of-phase signal may need to be less than the calculation time required for the external noise to reach the location generating the out-of-phase sound.

[0092] In another step 730, out-of-phase sound is generated at least in part based on the calculated out-of-phase signal, which is configured to eliminate external noise, wherein the generated out-of-phase sound propagates at least in part in a first direction of the transmission path.

[0093] List of reference numerals used in the attached figures

[0094] 200, 400: Vehicles

[0095] 201, 202, 350, 450, 550: External receivers

[0096] 210: Opposite side path

[0097] 220: Direct Path

[0098] 231, 310, 410, 510: External noise sources / tire noise

[0099] 301, 401: External noise

[0100] 302, 402: Abnormal sound

[0101] 311, 411: First direction

[0102] 320, 420: Components used for measurement

[0103] 330, 430: Components used for calculation

[0104] 340, 440, 540: Components used for generation

Claims

1. A system for reducing external noise of a vehicle, comprising: A measuring component for measuring the amplitude and phase of external noise that propagates at least partially from at least one external noise source of the vehicle in a first direction and has an acoustic transmission path, wherein the external noise propagates at least partially below the bottom of the vehicle; A computing component for calculating out-of-phase signals based at least in part on the amplitude and phase of the measured external noise; as well as A generation component is used to generate out-of-phase sound based at least in part on a calculated out-of-phase signal, the out-of-phase sound being configured to eliminate external noise. The generated out-of-phase sound propagates at least partially in the first direction of the acoustic transmission path, and Wherein, in the plane formed by the bottom of the vehicle, the first direction is perpendicular to or substantially perpendicular to the direction of travel of the vehicle.

2. The system according to claim 1, wherein, The external noise source is the tires of the vehicle, which are configured to generate external noise through the interaction between the tires and the road.

3. The system according to claim 1 or 2, wherein, The measuring component is located at the bottom of the vehicle and / or at a location along the first direction of the acoustic transmission path.

4. The system according to claim 1 or 2, wherein, The generating component is located at the bottom of the vehicle, or at the first direction along the acoustic transmission path, or at the edge of the wheel arch, or at the fender, or at the edge of the bumper, or at the side of the vehicle.

5. The system according to claim 1 or 2, wherein, The measuring component is located between the generating component and the external noise source, and / or the measuring component is located closer to the external noise source than the generating component.

6. The system according to claim 1 or 2, wherein, The system also includes: (i) A second measuring component for measuring the amplitude and phase of external noise that propagates at least partially from at least one external noise source of the vehicle in a second direction and has the acoustic transmission path thereunder, wherein the external noise propagates at least partially below the bottom of the vehicle. The calculation unit for calculating the out-of-phase signal is configured to calculate an additional out-of-phase signal based at least in part on the measured amplitude and phase of external noise propagating in the second direction; and (ii) A second generating unit for generating additional out-of-phase sound based at least in part on a calculated additional out-of-phase signal, said additional out-of-phase sound being configured to eliminate external noise. The additional out-of-phase sound generated propagates at least partially in the second direction of the acoustic transmission path.

7. The system according to claim 1 or 2, wherein, The computing component also calculates the out-of-phase signal based on at least one of the following: incident wave, system characteristics, external acoustics of the vehicle, the position of the generating component for generating the out-of-phase sound, the position of the measuring component, and / or the acoustic transmission path of the external noise.

8. The system according to claim 1 or 2, wherein, The calculations are performed, at least in part, based on the vehicle's external acoustics calibrated for the vehicle.

9. The system according to claim 1 or 2, wherein, The computing unit calculates the out-of-phase signal during a computing time that is less than the transmission time required for the external noise to reach the location of the generating unit.

10. The system according to claim 1 or 2, wherein, The measuring component includes a microphone, and / or the computing component includes a controller, and / or the generating component includes a speaker.

11. A method for reducing external noise of a vehicle, comprising: The amplitude and phase of external noise are measured, which propagates at least partially from at least one external noise source of the vehicle in a first direction and has an acoustic transmission path, wherein the external noise propagates at least partially below the bottom of the vehicle. The out-of-phase signal is calculated at least in part based on the amplitude and phase of the measured external noise; as well as Out-of-phase sound is generated at least in part based on the calculated out-of-phase signal, which is configured to eliminate external noise. The generated out-of-phase sound propagates at least partially in the first direction of the acoustic transmission path, and Wherein, in the plane formed by the bottom of the vehicle, the first direction is perpendicular to or substantially perpendicular to the direction of travel of the vehicle.

12. The method according to claim 11, wherein, The calculation of the out-of-phase signal is also based on at least one of the following: incident wave, system characteristics, external acoustics of the vehicle, the position of the component used to generate the out-of-phase sound, the position of the component used to measure the amplitude and phase of the external noise, and / or the acoustic transmission path of the external noise.

13. The method according to claim 11 or 12, wherein, The calculations are performed, at least in part, based on the vehicle's external acoustics calibrated for the vehicle.

14. The method according to claim 11 or 12, wherein, The calculation of the out-of-phase signal requires calculation time, which is less than the transmission time required for the external noise to reach the generation location of the out-of-phase sound.

15. A computer program product comprising a computer program that, when executed by a processor, causes the processor to perform the method according to any one of claims 11 to 14.

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