Adaptive control method for perceived rolling noise in a motor vehicle passenger compartment

Abstract

Title: Adaptive method for controlling perceived rolling noise in a motor vehicle cabin. This method for controlling perceived rolling noise in a motor vehicle cabin during driving conditions includes determining a sound correction to be applied in the vehicle, limited such that the difference between a sound correction sound pressure level and a predefined reference sound pressure level is less than or equal to a limit threshold for sound pressure level difference. Abstract figure: No figure

Description

Title of the invention: Method for adaptive control of rolling noise perceived in a motor vehicle passenger compartment

[0001] The invention relates to a method for adaptively controlling the rolling noise perceived in a motor vehicle passenger compartment, in particular of a vehicle while it is moving. The invention also relates to a system for adaptively controlling the rolling noise of a vehicle. The invention also relates to a vehicle comprising such a system.

[0002] When a vehicle moves on a road, users present in the passenger compartment can conventionally perceive a rolling noise, corresponding to the noise emitted and transmitted through the structure of the vehicle by the tires in contact with the roadway.

[0003] In order to optimize user comfort, it is known to equip the vehicle with an active road noise control system, also known as RNC systems for "Road Noise Control" or "Road Noise Cancellation". Such systems are capable of reducing the road noise perceived by users by active road noise control, or R-ANC for "Road Noise Active Control" by emitting, via speakers arranged in the passenger compartment, a counter-noise in phase opposition with the road noise perceived at a given moment.

[0004] A disadvantage of the known systems and their operation lies in the fact that the gains vary from single to double depending on the type of road surface traveled due to the search, by the active control systems, for the implementation of an optimal sound correction, that is to say allowing a maximum reduction of the rolling noise. As a result, users can perceive such a variation when the vehicle travels successively on portions of road with different surfaces, particularly in urban or peri-urban areas.

[0005] Also, the perception of rolling noise by users is influenced by prior knowledge or observation of the condition of the road surface. Thus, when the vehicle travels successively on different surfaces, users only tolerate a certain variation in the perceived rolling noise, which they will attribute to a change in a road surface. Beyond a certain limit, user comfort is affected and it is the characteristics of the vehicle and / or the effectiveness of the adaptive rolling noise control system that are called into question. Such a problem is particularly highlighted in electric motor vehicles, the interior acoustics of which are dominated by rolling noise.

[0006] The present invention falls within this context and aims to optimize the active control of rolling noise in order to ensure better passenger comfort.

[0007] To this end, the invention proposes a method for adaptive control of the rolling noise perceived in a motor vehicle passenger compartment during driving, comprising: - the acquisition of data relating to at least one parameter capable of defining a level of roughness of a portion of road by means of at least one sensor and the determination of the level of roughness of said portion of road from the acquired data, said level of roughness being defined according to a classification distinguishing a smooth, semi-rough or rough portion of road; - the determination of a sound correction to be applied in the vehicle for the portion of road considered corresponding to a sound signal at least defined by a correction sound pressure, as a function of the determined roughness level, the sound correction being limited so that a difference between the correction sound pressure specific to said correction and a predefined reference sound pressure is less than or equal to a limit threshold of sound pressure difference; - the emission, via at least one acoustic device, of the sound correction determined so as to perceive, in the passenger compartment, a final rolling noise defined by a resulting acoustic pressure.

[0008] In particular, the sound correction is selected from a predefined and / or calculated set of sound correction values, each of said sound correction values of said set being intended to be applied for at least one of the detected roughness levels and being limited so that a difference between the correction acoustic pressure specific to said sound correction and the predefined reference acoustic pressure is less than or equal to the acoustic pressure difference limit threshold.

[0009] For example, the sound correction is defined so that the resulting sound pressure is less than or equal to a predefined maximum sound pressure comfort threshold.

[0010] Optionally, the determination of the sound correction includes: - the determination of a maximum predicted sound correction, corresponding to a sound signal at least defined by a maximum predicted correction sound pressure, to be applied according to the determined roughness level in order to reduce the final perceived rolling noise to the maximum possible capacity of the at least one acoustic device; - the determination of a forecast sound pressure difference corresponding to the difference between the maximum forecast correction sound pressure and the predefined reference sound pressure; - the comparison of the predicted sound pressure difference with the sound pressure difference limit threshold and, when an exceeding of said threshold is detected, the adjustment of the predicted maximum sound correction in order to obtain a adjusted sound correction of which an adjusted correction sound pressure presents, relative to the reference sound pressure, a difference less than or equal to the sound pressure difference limit threshold.

[0011] The sound correction emitted via the acoustic device is then the maximum predicted sound correction or, when an exceeding of the acoustic pressure difference limit threshold is detected, the adjusted sound correction.

[0012] According to different exemplary embodiments, the predefined reference acoustic pressure is selected from: - a first predefined correction acoustic pressure corresponding to an acoustic pressure to be applied in the vehicle when it travels along a smooth section of road; - a second correction acoustic pressure previously applied at a time tx for the vehicle traveling a smooth section of road; - a third correction acoustic pressure previously applied at a time tx for the vehicle traveling a portion of road with a roughness level distinct from the portion of road traveled at a time t; or - a fourth correction acoustic pressure predicted for a portion of road to come at a time t+x presenting a roughness level distinct from the portion of road traveled at a time t. For example, the first predefined correction sound pressure to be applied in a vehicle when it travels on a smooth section of road is included in the correction set.

[0013] Optionally, the method comprises modifying the selected reference acoustic pressure when it is detected that the vehicle is traveling on a portion of road or a plurality of portion(s) of road(s) of the same level of roughness for a duration and / or a distance greater than or equal to a predefined duration and / or distance threshold.

[0014] Optionally, the data acquisition includes: - the acquisition of data relating to a portion of the road traveled being in contact with at least one wheel of the vehicle, the at least one sensor being selected from an accelerometer and / or a microphone arranged at the level of the body, the steering knuckle and / or the at least one wheel of the vehicle; and / or - the acquisition of data relating to a portion of the road located upstream of the vehicle via at least one camera, a means of locating the vehicle and / or a connected device.

[0015] Optionally, the sound correction is defined as a function of the correction sound pressure and as a function of a sound quality level.

[0016] Optionally, the method further comprises a step of informing the driver via a human-machine interface including visual and / or audible communication of parameters relating to the sound correction applied.

[0017] According to an exemplary embodiment, the acoustic pressure deviation limit threshold is determined as a function of a driver preference.

[0018] The invention also relates to a system for adaptively controlling the rolling noise of a vehicle, the system comprising hardware and / or software elements implementing the method according to the invention, the hardware elements comprising at least one data processing unit, at least one sensor, such as an accelerometer and / or an external microphone, and at least one acoustic device, such as a loudspeaker or a speaker.

[0019] The invention can also be extended to a motor vehicle comprising an adaptive rolling noise control system according to the invention.

[0020] The invention may also extend to a computer program product comprising program code instructions recorded on a computer-readable medium for implementing the steps of the method according to the invention when said program operates on a computer. Alternatively, said computer program product is downloadable from a communications network and / or recorded on a computer-readable data medium and / or executable by a computer.

[0021] Other details, characteristics and advantages will emerge more clearly on reading the detailed description given below, for informational and non-limiting purposes, in relation to the various exemplary embodiments illustrated in the following figures:

[0022] [Fig.l] is a schematic representation of an exemplary embodiment of a motor vehicle equipped with an adaptive rolling noise control system.

[0023] [Fig.2] is a general flowchart of an example of execution of an adaptive rolling noise control method.

[0024] [Fig. 3] is a graph illustrating a variation in the sound pressure of rolling noise, without sound correction, as a function of the roughness level of road sections in a vehicle not equipped with an adaptive rolling noise control system.

[0025] [Fig.4] is a graph illustrating a variation in the sound pressure of rolling noise as a function of the roughness level of road portions when a maximum correction is applied by an adaptive rolling noise control system of the prior art.

[0026] [Fig.5] is a graph illustrating a variation in the acoustic pressure of rolling noise as a function of the roughness level of road sections when a limited and adaptive sound correction according to the invention is applied.

[0027] [Fig.6] is a graph illustrating a smoothing of rolling noise jumps between different types of surfaces, thanks to a database anticipating the level of roughness of a future section of road.

[0028] [Fig.7] is a graph illustrating a measurement of rolling noise, for a given road roughness level, when a sound correction according to the invention is applied.

[0029] [Fig.8] is a flowchart of an alternative example of executing the adaptive rolling noise control method.

[0030] [Fig.l] schematically illustrates an exemplary embodiment of a motor vehicle 1. The vehicle 1 considered may be of any type. For example, the vehicle 1 may have a thermal, electric or hybrid engine. Also, the vehicle 1 may be a private vehicle, a utility vehicle or a vehicle dedicated to public transport.

[0031] The vehicle 1 comprises an active adaptive rolling noise control system 2. The adaptive control system 2 makes it possible to reduce or even eliminate the rolling noise perceived inside the passenger compartment in order to improve user comfort and / or the interior acoustic performance of the vehicle 1. The term “rolling noise” means the noise emitted in the passenger compartment and transmitted through the structure of the vehicle 1 by the wheels, in particular the tires, in contact with the roadway. Indeed, the interaction between the tires of the vehicle 1 in motion and the roadway causes vibrations and / or shocks which are transmitted by the chassis. The rolling noise perceived in the passenger compartment depends directly on the longitudinal speed of the vehicle 1, the roughness of the portion of road traveled by the vehicle 1 and the singularities or defects of said portion of road.As further explained below, "portion of road" means, for example, a portion of a road traveled by the vehicle, in contact with the wheels or located in front of the vehicle, or a portion of a road to come. The condition of the portion of road considered can be characterized in the microscopic sense, in particular by the roughness of its surface, or grain size, and macroscopically, in particular by the presence or absence of defects, in particular potholes.

[0032] The adaptive control system 2 comprises hardware and / or software elements capable of implementing an adaptive control method 100 of the rolling noise perceived in a passenger compartment according to the invention, further defined below. The hardware elements comprise at least one data processing unit 3, at least one sensor 4, such as an accelerometer and / or an external microphone, and at least one acoustic device 5, such as a loudspeaker or a speaker, arranged in the passenger compartment of the vehicle 1.

[0033] Optionally, the adaptive rolling noise control system 2 comprises at least one of: - a means of locating 6 the vehicle 1 in the road infrastructure; - a human-machine interface 7; - an image capture device 8 such as a camera; - a communication module 9 configured to exchange data with a connected device and / or with at least one database.

[0034] The processing unit 3 comprises at least one computer comprising hardware and software resources, more precisely at least one processor, or microprocessor, cooperating with one or more memory elements included in the adaptive rolling noise control system 2 or equipped in the vehicle 1. The memory element is a storage space constituting a recording medium readable by a computer or by the computer of the processing unit 3 and which comprises instructions which, when executed by the computer or the computer, lead the latter to implement the method according to the invention. The computer is thus able to execute instructions for the implementation of a computer program.

[0035] The at least one sensor 4 is capable of evaluating or determining a level of roughness, i.e. a granulometry, of a portion of road of the road network traveled by the vehicle and directly in contact with at least one of the wheels, in particular one of the tires, of the vehicle 1. Preferably, the adaptive control system 2 comprises a plurality of said sensors 4. In particular, the at least one sensor 4 is configured to evaluate at least one parameter capable of defining a level of roughness of the portion of road, in particular of a coating of the portion of road traveled. For example, the at least one sensor 4 is capable of measuring a vibration signal and / or noise, in particular noise in the vicinity of the sensor 4. In this sense, the at least one sensor 4 is an accelerometer, for example piezoelectric. Alternatively or additionally, the at least one sensor 4 is a microphone.

[0036] For example, the processing unit 3 is capable of determining or measuring roughness parameters such as the IRI, i.e. the International Roughness Index, and / or the PMP, i.e. the Average Profile Depth as a function of the data acquired by the at least one sensor 4. Preferably, the at least one sensor 4 is arranged close to at least one of the wheels of the vehicle 1, for example on a chassis, a cradle and / or a steering knuckle of a vehicle 1. By "steering knuckle" is meant a part through which an axis of rotation of at least one of the wheels passes.

[0037] The acoustic device 5 comprises at least one enclosure, a loudspeaker and / or a microphone capable of emitting an acoustic signal, particularly here a corrective acoustic signal, referred to as sound correction or predictive sound correction. In particular, the acoustic device 5 is arranged in the passenger compartment at the head of a user such as a driver and / or a passenger, for example above at least one opening of the vehicle 1.

[0038] The location means 6 allows in particular the location of the vehicle 1 in the road infrastructure. It integrates, for example, a system for locating the vehicle 1 and / or a high-definition map of the road infrastructure. In particular, the location of the vehicle 1 can be provided by a GPS type system, from the English acronym “Global Positioning System”. Alternatively or in addition, the location means 6 can be a location system embedded in the vehicle 1. Also, the location means 6 can provide data relating to a level of roughness of a portion of road, traveled by the vehicle 1 and / or to come. Such data can be associated with the map provided and / or come from a database. Such data are, for example, provided by the vehicle or by other vehicles traveling, or having traveled, in the road infrastructure.

[0039] The human-machine interface 7 comprises in particular a screen. It is capable of broadcasting information, in particular an audible and / or visual message to the user. Also, the human-machine interface 7 is capable of receiving data entered by a user, in particular relating to the driver's preferences.

[0040] The image capture device 8 is preferably equipped at the front or on the side parts of the vehicle 1, for example at the side doors or the rearview mirrors. It may comprise a radar, a lidar and / or a camera.

[0041] The communication module 9 is configured to receive data from a database or from one or more connected devices, such as a mobile phone, a connected watch or other, via a low-frequency or high-frequency wireless link. It may, for example, be a wireless link based on “cellular”, “Wi-Fi” and / or “Bluetooth” technologies. As further explained below, the communication module 9 can extract data relating to the position coordinates of the vehicle 1 and / or to a level of roughness of a portion of road traveled by the vehicle 1 and / or of a portion of road to come.

[0042] Figures 2 and 8 illustrate examples and variants of execution of an adaptive control method 100 of rolling noise. Such a method can also be considered as being a method of operation of the adaptive control system 2 described previously or as a method of operation of the motor vehicle 1 equipped with such a system. The method according to the invention is particularly implemented when the vehicle 1 is in a rolling situation.

[0043] The method comprises a step of acquiring data E01 relating to at least one parameter capable of defining a level of roughness of a portion of road, in particular traveled by the vehicle. As indicated above, the acquisition of the data is carried out by means of at least one sensor 4 or a plurality of sensors 4. The acquired data comprise one or more parameter(s) capable of defining the level of roughness of the portion of road traveled. In particular, said data may be related to vibrations and / or noise, i.e. to the acoustic emission of the contact of vehicle 1 on the section of road. For example, the roughness parameters are related to the IRI and / or the PMP as explained above.

[0044] The acquisition of data E01 is, according to an exemplary execution of the method, carried out so as to obtain data relating to a portion of the road traveled directly in contact with at least one of the wheels of the vehicle 1 via the at least one sensor 4. When the vehicle 1 travels said portion of road, the at least one sensor 4 collects, in real time or at regular time intervals, data relating to the at least one parameter and transmits them to the processing unit 3.

[0045] Alternatively or additionally, the data acquisition E01 is carried out so as to obtain data relating to a portion of the road in contact with the vehicle 1 and / or to come, that is to say a portion of road located in front of the vehicle 1, visible or not, or a portion of road that the vehicle 1 is likely to travel on its route. For example, data relating to the at least one parameter capable of determining a level of roughness of the portion of road located directly upstream of the vehicle 1 can be extracted by the image capture device 8 equipped at the front of the vehicle 1.

[0046] Alternatively or additionally, data relating to at least one upcoming road portion may be extracted via the location means 6 or via the communication module 9 and a connected device. The data relating to a roughness level of the upcoming road portion are then associated with the mapping provided by the location means 6 and / or come from a database. Conventionally, the location means 6 and / or the connected device may be configured so as to obtain or calculate the longitudinal speed of the vehicle 1 at a given instant so as to be able to extract relevant data, relating to the roughness level of the road portion considered, as a function of the position of the vehicle 1 and its longitudinal speed.Optionally, such a principle may apply mutatis mutandis to at least one portion of road already travelled by the vehicle and / or included in the road infrastructure.

[0047] The use of data relating to at least one portion of road ahead, located in front of the vehicle or not visible, advantageously makes it possible to anticipate in an optimized manner changes in types of surfaces and variations in the level of roughness when the vehicle 1 travels on portions of road having different levels of roughness. In this way, as illustrated in [Fig.6] in dotted lines in the circled areas, the method can thus reduce possible acoustic peaks resulting from a latency in the application of the sound correction due to the execution of the method according to the invention on the basis of only the data from the at least one sensor 4, relating to the portion of the road in contact with the vehicle 1.

[0048] Optionally, the adaptive rolling noise control system 2 can store the measured and / or extracted data on the at least one memory element so as to construct its own mapping or so as to complete an existing mapping.

[0049] The method then comprises a step of determining the roughness level E02 of the portion of road from the acquired data. For example, in a known manner, laws establishing the roughness of a portion of road as a function of the vibration level, or vibration signal, processed may be previously constructed or recorded, in particular on the at least one memory element, as a function of the longitudinal speed of the motor vehicle 1 moving on different surfaces. The same applies to laws linking the roughness parameters of the roadway, in particular the mean depth of the profile, or PMP, the vibration signal provided by the at least one sensor 4 of the vehicle 1 and / or the longitudinal speed of the vehicle 1. These laws may be compared to the measurements made and allow an estimation of the roughness level of the portion of road traveled with an uncertainty of the order of 10%.A similar principle applies mutatis mutandis to data relating to a future section of road.

[0050] According to a preferred example of execution of the method according to the invention, the level of roughness of the road portion is organized according to a classification distinguishing different types of roads having different levels of roughness. For example, the roughness of a road portion is defined according to the CNOSSOS / NMPB2008 standard in force, comprising a classification of the acoustics of road surfaces according to three categories corresponding to a rough road portion, a semi-rough road portion and a smooth road portion. Such a classification can be directly programmed in the vehicle 1, in particular in the processing unit 3 and / or recorded on the at least one memory element. Alternatively, such a classification can be made accessible via the location means 6 and / or the communication module 9.Also, once the level of roughness of the portion of road considered, in contact with vehicle 1 and / or to come, is estimated, the processing unit 3 can extract the road category corresponding to the portion of road considered.

[0051] The method then comprises a step of determining a sound correction E03 to be applied. The sound correction Cx corresponds to a sound signal to be applied, or emitted, in the passenger compartment in order to reduce the rolling noise perceived in the passenger compartment so that a user present in the vehicle 1 perceives an attenuated rolling noise, in particular having a resulting acoustic pressure PAfx reduced compared to a similar situation without any application of sound correction Cx. For the sake of clarity, the rolling noise before application of the sound correction Cx and of "final rolling noise BRf" the rolling noise perceived by the user with application of the sound correction Cx. Note that "correction" means a modification by reduction or increase of the initial rolling noise BRi in order to obtain a target final rolling noise BRf. "Resulting sound pressure PAfx" also means the sound pressure of the final rolling noise BRf perceived by a user located in the passenger compartment when a sound correction Cx is applied, that is to say, in other words, the volume of the final rolling noise BRf. The sound correction Cx is in particular a counter-noise presenting a spectrum in phase opposition with the rolling noise perceived at a given instant. The sound correction Cx varies, in a known manner, according to the level of roughness of the portion of road considered and according to the longitudinal speed of the vehicle 1.

[0052] Particularly according to the invention, the sound correction Cx corresponds to a sound signal at least defined by a limited correction acoustic pressure PAx such that a difference KPx between the correction acoustic pressure PAx specific to said sound correction Cx and a predefined reference acoustic pressure PRfx is less than or equal to a predefined acoustic pressure difference limit threshold Sk_max. Note that the value of the difference KPx, compared to the difference limit threshold Sk_max, may be the absolute value of said difference.

[0053] According to a particular example of execution of the method according to the invention, the sound correction Cx to be applied is particularly selected from a predefined and / or calculated set of sound correction values ECx, each of said sound correction values being intended to be applied for at least one of the roughness levels that can be detected. Here, the term "predefined" means that all of said values are either entered and recorded on the memory element prior to the execution of the method. The term "calculated" means that all of said values can be calculated by the processing unit 3 prior to the implementation of the step E03 of determining the sound correction Cx to be applied and / or simultaneously with a part of said step.According to the invention, the set of correction values ECx is particularly limited, each of said sound correction values, capable of being applied for at least one of the detected roughness levels, being limited so that a difference KPx between the correction sound pressure PAx specific to each of the sound corrections Cx of the set ECx and a predefined reference sound pressure PRfx is less than or equal to a limit threshold of difference Sk_max of sound pressure. Note that the value of each of these differences KPx, compared to the limit threshold of difference Sk_max, can be the absolute value of said difference.

[0054] Thus, according to the invention, the sound correction Cx, for example selected from the set of sound corrections ECx, to be applied is limited so as to regulate the variation of the perceived final rolling noise BRf, of the resulting acoustic pressure PAfx, and thus optimize user comfort. Limitation of the correction acoustic pressure PAx by the KPx difference advantageously makes it possible to limit the variation of the perceived final rolling noise BRf when the vehicle is traveling on sections of road with different levels of roughness, thus limiting the dynamics of said final rolling noise BRf.

[0055] For example, the threshold limit of deviation Sk_max of acoustic pressure is set so as to be less than 10 dB. In particular, according to an exemplary embodiment, the threshold limit of deviation Sk_max of acoustic pressure is set at 8 dB. Such values correspond to a degree of deviation, or variation, of the acoustic pressure below which the difference in rolling noise is estimated as impacting the comfort of the drivers.

[0056] According to an exemplary embodiment, during the step E03 of determining the sound correction Cx to be applied, the processing unit 3 extracts the sound correction Cx to be applied from a predefined set of sound corrections ECx associating with each roughness level at least one sound correction value Cx defined by a suitable acoustic pressure PAx. For example, such a set of sound corrections ECx is organized in the form of a table associating with each roughness level, in particular defined according to a classification as set out above, a sound correction value Cx to be applied or a range of sound correction values Cx that can be applied. In particular, said sound correction values Cx are also associated with a longitudinal speed of the vehicle.

[0057] The method then comprises a step E04 of transmitting, via the adaptive control system 2, the sound correction Cx defined in the passenger compartment. The sound correction Cx is transmitted by the acoustic device 5 as described above.

[0058] The method according to the invention is thus distinguished from the conventional operation of an active correction system of the prior art. Indeed, an active control system according to the prior art automatically applies, depending on the vibration level of the running gear and the acoustic pressure in the vehicle in particular, a maximum possible sound correction having a maximum acoustic pressure in phase opposition so as to reduce the perceived rolling noise as much as possible, to the extent of the capabilities of the adaptive control system at a given time. A high-performance adaptive control system can thus apply a sound correction Cx making it possible to lower the acoustic pressure of the perceived rolling noise to a value of the order of 5 or 6 dB for example.However, such a principle does not take into account the general context of vehicle circulation and the fact that the correction capacity of the adaptive control system depends on the level of roughness of the section of road traveled. The result is that when the vehicle travels successively on sections of road with different levels of roughness, variations im . rolling noise levels are perceived by users despite the application of maximum sound correction. User comfort is affected by such variation and their perception of the operation of the adaptive rolling noise control system may be impacted. In particular, users may question the quality of the adaptive rolling noise control system and its operation.

[0059] The adaptive rolling noise control system 2 and the method according to the invention advantageously make it possible to solve such a problem by regulating the acoustic dynamics in the vehicle 1 and by controlling the variations in the rolling noise perceived in the vehicle 1 in a driving situation by limiting the sound correction Cx as explained above.

[0060] Also, optionally but preferably, the sound correction Cx is, in addition, defined or adjusted so that the resulting acoustic pressure PAfx is less than or equal to a predefined maximum comfort threshold Sc_max of acoustic pressure. The maximum comfort threshold Sc_max of acoustic pressure can be defined by the user via the human-machine interface 7 according to his preferences. Alternatively or additionally, the maximum comfort threshold Sc_max of acoustic pressure can be predefined by the manufacturer. Such a threshold corresponds to a threshold below which the acoustic pressure of the perceived rolling noise is judged less comfortable, or even uncomfortable for the user and / or by the user.

[0061] According to different alternatives for executing the method according to the invention, the reference acoustic pressure PRfx can in particular be selected from: - a first predefined correction acoustic pressure PRfl, i.e. programmed, to be applied in a vehicle 1 when it travels along a smooth section of road; - a second correction acoustic pressure PRf2 previously applied at a time tx for vehicle 1 traveling a smooth section of road; - a third correction acoustic pressure PRf3 previously applied for vehicle 1 traveling a portion of road with a roughness level distinct from the portion of road traveled at time t; or - a fourth correction acoustic pressure PRf4 predicted for a portion of road to come at a time t+x presenting a roughness level distinct from the portion of road traveled at time t.

[0062] It should be noted here that the terms “first”, “second”, “third” and “fourth” are intended here to distinguish the type of sound pressure value used as reference sound pressure PRfx and not to define a hierarchy within these values.

[0063] For example, when the reference sound pressure PRfx is the first predefined correction sound pressure PRfl, the reference sound pressure PRfx corresponds to a sound correction that can be applied in the vehicle 1 when it travels a smooth road portion. The processing unit 3 can calculate an average of the sound pressures used for this type of road portion or extract a stored value. This calculation can be carried out from data stored on at least one memory element, corresponding to a history of smooth roads traveled by the vehicle 1. Additionally or alternatively, this calculation can be carried out from data communicated via the database, the location means 6 and / or the communication module 9. Alternatively again, the value of the average of the sound pressures used on smooth roads can be directly extracted from the database.According to an alternative example, the first correction sound pressure PRfl is one of the sound pressure value(s) extracted from the set of sound corrections ECx, described previously, intended to be implemented on the road list, for example set by the manufacturer according to the correction capabilities of the adaptive control system 2.

[0064] Such a principle allows a limitation of the most severe correction sound pressure PAx. The variations in the resulting sound pressure PAfx of the final perceived rolling noise BRf when the vehicle travels on portions of roads with distinct roughness levels, particularly semi-rough or rough, are then strictly included in the difference KPx, which is defined in relation to a sound pressure representative of an acoustic environment that is most comfortable for the user, namely on a smooth portion of road.

[0065] It should be noted that, advantageously, the correction sound pressure PAx to be applied on a smooth road, used as the reference sound pressure PRfl as set out above, may correspond to a reduction, a maintenance or an increase in the sound pressure of the initial rolling noise BRi on a smooth road in order to optimize the sound corrections Cx that can be applied to roads of different roughness levels, in particular semi-rough and rough roughness levels, and to allow a maximum reduction in the final rolling noise BRf perceived for the noisiest types of roads while limiting the acoustic dynamics within the vehicle.Such a principle is, for example, automatically or manually implemented by the processing unit 3 in order to set sound corrections Cx specific to different levels of roughness, for example in a table as set out above, at values less than or equal to the maximum comfort threshold Sc_max.

[0066] Thus, as illustrated in [Fig.5] or 6, the adaptive control system 2 makes it possible to understand and optimize the sound correction to be applied on the scale of the different possible roughness levels. In particular, the adaptive control system 2 can define a set of sound correction values ECx, from which the sound correction Cx to be applied is derived, making it possible to limit the reduction in the sound pressure of the initial rolling noise BRi when the vehicle is traveling on a smooth section of road, or even apply a sound correction Cx artificially increasing the sound pressure of the final rolling noise BRf compared to the initial rolling noise BRi in order to optimize and maximize a sound correction Cx to be applied, for a future situation for example, when the vehicle is traveling on a rough or semi-rough section of road, ensuring that the reduction in sound pressure then implemented remains within the limit of the deviation relative to the reference sound pressure PRfl here, less than or equal to the threshold limit of deviation Sk_max of sound pressure.

[0067] According to another alternative example, the reference acoustic pressure PRfx is the second correction acoustic pressure PRf2, corresponding to the acoustic pressure PAx of an acoustic correction Cx previously applied at a time tx for the vehicle 1 traveling a smooth portion of road. The preceding description thus applies mutatis mutandis and the processing unit 3 then uses, similarly to what was indicated above, a reference acoustic pressure PRfx representative of a current driving situation of the vehicle. The second correction acoustic pressure PRf2 used may in particular be the most recent correction acoustic pressure PAx applied for a portion of road comprising a smooth surface.

[0068] According to another example, the reference acoustic pressure PRfx used is the third correction acoustic pressure PRf3, corresponding to the acoustic pressure PAx of the sound correction Cx previously applied at a time tx, preferably at a time t-1, for the vehicle 1 traveling a portion of road with a roughness level distinct from the portion of road traveled at time t. Such a principle allows the calculation of the difference KPx between the correction acoustic pressure PAx and a reference acoustic pressure PRfx representative of a most recent distinct acoustic situation, for example recorded on the at least one memory element. The limitation of the sound correction Cx applied is thus limited less strictly than the aforementioned examples but limits the dynamics of variation of the rolling noise to an extent allowing the improvement of user comfort.

[0069] According to another example, the reference acoustic pressure PRfx used is the fourth correction acoustic pressure PRf4, corresponding to the acoustic pressure PAx of the sound correction Cx planned for a portion of road to come at a time t+x, preferably t+1, having a level of roughness distinct from the portion of road traveled at time t. Such a principle advantageously allows to anticipate a future acoustic situation and thus to optimize the sound correction Cx to be applied, and by extension the resulting acoustic pressure PAfx, for the instant t and the instant t+1. In particular, such a principle makes it possible to optimize the reduction of the resulting acoustic pressure PAfx relative to the maximum comfort threshold Sc_max when the latter is applied. Alternatively or additionally, such a principle can make it possible to integrate a smoothing of acoustic jumps as described above with reference to [Fig.6]. The data relating to a level of roughness of a portion of road which will be traveled at an instant t+1 can then be obtained via the location means 6, the image capture device 8 and / or the communication module 9 as explained previously.

[0070] By way of non-limiting examples, Figures 3 to 5 make it possible to compare similar driving situations between a vehicle without an adaptive rolling noise control system, a vehicle equipped with a system according to the prior art only capable of applying maximum sound correction and a vehicle according to the invention.

[0071] As shown in [Fig.3], if at a time t the vehicle 1 is traveling at a fixed speed on a portion of road with a smooth surface, for which, without correction, the perceived rolling noise acoustic pressure amounts to XI dB and a portion of road ahead at a time t+1 is a rough portion of road for which, without correction, the perceived rolling noise amounts to X2 dB and has a difference of 14 dB relative to the value XL The users then perceive, without any correction, a significant variation in the rolling noise acoustic pressure between the two portions of road.

[0072] [Fig.4] illustrates the non-limiting example of an adaptive rolling noise control system according to the prior art, applying at all times a maximum possible correction for the level of roughness considered and, for example, capable of reducing the rolling noise from an acoustic pressure of 5 dB to its maximum correction capacity. A solid line curve represents the variations in the resulting acoustic pressure PAfx, after application of a sound correction in a vehicle traveling on portions of roads with different levels of roughness. It should be noted here that the importance of the sound correction increases with the level of roughness of the portion of road considered, the sound correction applied having a lower correction acoustic pressure on a smooth road than on a rough road.In this case, the adaptive control system of the prior art applies a sound correction of the order of 2 dB for the smooth road portion, lowering the resulting acoustic pressure PAfx of the final rolling noise BRf to XI' dB, while it applies to the rough road portion a maximum correction of 5 dB, lowering the resulting acoustic pressure PAfx of the final rolling noise BRf to X2' dB. The variation between these two portions of . roads is then of the order of 11 dB.

[0073] As previously described with reference to [Fig. 5], the adaptive control system 2 according to the invention limits and adjusts the sound correction Cx in order to reduce the acoustic dynamics within the passenger compartment and to optimize user comfort. A solid line curve represents the variations in the resulting acoustic pressure PAfx, after application of such a limited sound correction Cx. In order to prevent strong acoustic dynamics as is the case in the example described with reference to [Fig. 4], the limitation of the correction by the defined gap makes it possible to adjust the sound correction acoustic pressures Cx to be applied by considering the correction capacity of the adaptive control system 2 and user comfort.Thus, in the illustrated example, the adaptive control system 2 cannot further lower the sound pressure of the final rolling noise BRf perceived on a rough portion of road compared to its maximum correction capacity. Also, for example, within the set of possible sound corrections ECx, the processing unit 3 is able to define at least one sound pressure value PAx of a possible sound correction Cx on a smooth portion of road which is adjusted so as to respect the limitation imposed by the difference KPx and the difference limit threshold Sk_max while making it possible to optimize the reduction of the final rolling noise BRf. In the illustrated example, described above with reference to [Fig.6], such a principle is represented by the application of a sound correction Cx implementing an increase in the resulting sound pressure PAfx compared to the sound pressure of the initial rolling noise BRi.

[0074] Indeed, the resulting acoustic pressure PAfx perceived when the vehicle 1 is traveling on the smooth portion of road may be judged to be comfortable, or even be less than or equal to the predefined maximum comfort threshold Sc_max of acoustic pressure as explained above. Conversely, the sound correction Cx to be applied to the rough, limited portion of road may result in a resulting acoustic pressure PAfx that is not optimized, i.e. for example greater than the maximum comfort threshold Sc_max of acoustic pressure.

[0075] The sound correction Cx can, for example, thus increase by 1 dB the resulting sound pressure PAfx perceived for the smooth road portion, raising it to a comfortable level of XI” dB instead of lowering it as proposed for an execution with maximum sound correction. When a sound correction Cx of 5 dB is then provided for a rough road portion to be traveled at a time t+x and if the reference sound pressure PRfx used is based on the first, second or third correction sound pressure PRfl, PRf2, PRf3 as described previously, the measured deviation KPx, and therefore the variation of the final rolling noise BRf, perceived is limited to a value lower than the deviation limit threshold Sk max. The rolling noise final perceived BRf when the vehicle travels between sections of roads with different levels of roughness and the resulting sound pressure PAfx remains within a range of values comfortable for the user and the acoustic dynamics perceived by the user is optimized.

[0076] Optionally, the predefined reference acoustic pressure PRfx can be modified according to the situations, a different reference acoustic pressure being able to be selected from the examples set out above. Such a selection can be made manually by the user or automatically, according to preferences entered via the human-machine interface 7 for example. Optionally, such a selection can be made automatically by the adaptive control system 2 according to the resulting acoustic pressure PAfx and the predefined maximum comfort threshold Sc_max of acoustic pressure, in particular in order to ensure that the resulting acoustic pressure PAfx is less than or equal to the maximum comfort threshold Sc_max. Optionally again, such a selection can be executed conditionally, as further explained below.

[0077] According to a particular, optional exemplary embodiment, the predefined reference acoustic pressure PRfx is modified, so as to select a different type of reference acoustic pressure PRfx, from among the aforementioned examples, when it is detected that the vehicle 1 is traveling on a portion of road or several portions of road(s) with the same level of roughness for a duration and / or a distance greater than or equal to a predefined duration and / or distance threshold S_dt. The duration and / or distance threshold S_dt can be preprogrammed by the manufacturer or defined by the user via the human-machine interface 7.For example, in a non-limiting manner, when it is detected that the vehicle 1 travels a portion of road or several portions of road(s) with the same level of roughness for more than 10 minutes while traveling at 90 km / h, it may be more relevant to select a reference sound pressure PRfx corresponding to the fourth correction sound pressure PRf4, planned for a portion of road to come, rather than the third correction sound pressure PRf3 previously applied for a portion of road traveled earlier. The dynamics of the variations in sound pressure of the final rolling noise BRf is in fact lower in such a situation and less perceptible by a user.

[0078] [Fig.8] illustrates a particular example of execution, optional, of the method of adaptive control 100 of rolling noise allowing the automated execution of a mode allowing the automated implementation of one of a maximum sound correction, similar to what can be done by conventional active control systems, or a limited Cx sound correction as set out above.

[0079] In such an exemplary embodiment, the step E03 of determining the correction sound Cx comprises, in a first step, a sub-step E031 of determining a maximum predicted sound correction Cx_max_p to be applied. The maximum predicted sound correction Cx_max_p corresponds here to an estimation, or forecast of a sound signal at least defined by a predicted maximum correction sound pressure PAx_max, to be applied according to the determined roughness level in order to reduce as much as possible, on the basis of the correction capabilities of the adaptive rolling noise control system 2, the rolling noise perceived in the passenger compartment and its resulting sound pressure PAfx.

[0080] The determination E03 of the sound correction Cx then comprises a sub-step E032 of determining a predicted sound pressure difference KPx_p corresponding to the difference between the predicted maximum correction sound pressure PAx_max and the predefined reference sound pressure PRfx as set out above. The above description, relating to the reference sound pressure PRfx or to the difference KPx between the correction sound pressure PAx and the reference sound pressure PRfx applies here mutatis mutandis.

[0081] The method then comprises a sub-step E033 of comparing the predicted sound pressure difference KPx_p with the limit threshold of the sound pressure difference Sk_max. When an exceeding of said threshold is detected, the method comprises a sub-step E034 of adjusting the predicted maximum sound correction Cx_max_p in order to obtain an adjusted sound correction Cx_A of which an adjusted correction sound pressure PAx_A has, relative to the reference sound pressure PRfx, a difference KPx less than or equal to the limit threshold of the sound pressure difference Sk_max. The method thus implements a limitation similar to that set out above when it is detected that the maximum correction is not adapted to a comfortable driving situation and is likely to cause variations in the final perceived rolling noise BRf that are too significant.Also the various execution options and alternatives described above apply mutatis mutandis.

[0082] Then, the correction step E04 is executed so that the sound correction Cx emitted via the adaptive rolling noise control system 2 corresponds to the maximum predicted sound correction Cx_max_p when no overshoot is detected. Conversely, when an overshoot of the acoustic pressure deviation limit threshold Sk_max is detected, the sound correction Cx corresponds to the adjusted and limited sound correction Cx_A. The sound correction Cx to be applied is thus automatically selected between a sound correction allowing the most effective correction, i.e. maximum or allowing to obtain a lowest resulting acoustic pressure PAfx for the level of roughness considered, and the sound correction Cx most suitable for limiting the dynamics of variation of the resulting sound pressure PAfx in the passenger compartment over time and over the different sections of road(s) traveled.

[0083] Optionally, independently of the method of execution, the sound correction Cx is defined as a function of the correction sound pressure, as explained above, and as a function of a level of improvement in the sound quality of the rolling noise. As illustrated in [Fig.7], the term “improvement in sound quality” of the sound correction Cx means the smoothing of the curve of the acoustic spectrum of the rolling noise Cx in order to eliminate acoustic peaks while remaining at the same overall level and thus to approach an acoustic spectrum of ideal quality, an example of which is represented here in dotted lines. Preferably, the sound correction Cx applied has a maximum level of improvement in the sound quality of the rolling noise, adapted to the level of roughness of the portion of road traveled, and this independently of the application or not of a limitation of the correction sound pressure PAx.In this way, regardless of the type of correction sound pressure applied, limited or maximum, the quality of the rolling noise is improved to the maximum of the capabilities of the adaptive rolling noise control system 2.

[0084] As explained above, the adaptive control system 2 optionally comprises the human-machine interface 7. This can be used by the user to communicate preferences. Additionally or alternatively, it can be used to communicate to the user information relating to the method according to the invention.

[0085] According to one example, the method may optionally comprise, at the start of the execution of the method or prior to it, a step E00 of providing information on at least one user preference. Such a preference may relate to a value of the acoustic pressure deviation limit threshold Sk_max, to the resulting acoustic pressure PAfx and / or to the maximum comfort threshold Sc_max.

[0086] For example, optionally, prior to or simultaneously with the emission E04 of the sound correction Cx, the method comprises a step of informing the user comprising the visual and / or audible communication of parameters relating to the sound correction Cx applied. In particular, the human-machine interface 7 can indicate the correction acoustic pressure PAx specific to the sound correction Cx applied and / or the resulting acoustic pressure PAfx perceived in the passenger compartment. Alternatively or additionally, when the method is executed so as to automatically implement a sound correction Cx that is the most suitable between the predicted maximum sound correction Cx_max_p and the limited sound correction Cx, also referred to above as adjusted sound correction, the human-machine interface 7 informs the user of the operating mode executed.

[0087] The present invention thus proposes a method for adaptive active control of the rolling noise perceived in a motor vehicle passenger compartment making it possible to optimize the dynamics of variation of the acoustic pressure of the rolling noise perceived in the passenger compartment when a sound correction is applied. Thus, beyond the simple overall reduction of the rolling noise perceived in the passenger compartment, the invention makes it possible to minimize the transitions in the acoustic pressure of rolling noise from one covering to another and thus optimize user comfort.

[0088] The present invention cannot, however, be limited to the means described and illustrated here and it also extends to any equivalent means and to any technically effective combination of such means insofar as they ultimately fulfill the functionalities described and illustrated in the present document.

Claims

1.

2.

3. Claims Method for adaptive control (100) of the rolling noise perceived in a vehicle interior (1) during driving, comprising: - the acquisition of data (E01) relating to at least one parameter capable of defining a level of roughness of a portion of road via at least one sensor (4) and the determination of the level of roughness (E02) of said portion of road from the acquired data, said level of roughness being defined according to a classification distinguishing a smooth, semi-rough or rough portion of road; - the determination (E03) of a sound correction (Cx) to be applied in the vehicle for the portion of road considered corresponding to a sound signal at least defined by a correction sound pressure (PAx), as a function of the determined roughness level, the sound correction (Cx) being limited so that a difference (KPx) between the correction sound pressure (PAx) specific to said correction and a predefined reference sound pressure (PRfx) is less than or equal to a difference limit threshold (Sk_max) of sound pressure; - the emission (E04), via at least one acoustic device (5), of the sound correction (Cx) determined so as to perceive, in the passenger compartment, a final rolling noise (BRf) defined by a resulting acoustic pressure (PAfx). Adaptive control method (100) of rolling noise according to the preceding claim, in which the sound correction (Cx) is selected from a predefined and / or calculated set of sound correction values (ECx), each of said sound correction values of said set being intended to be applied for at least one of the detected roughness levels and being limited so that a difference (KPx) between the correction sound pressure (PAx) specific to said sound correction and the predefined reference sound pressure (PRfx) is less than or equal to the sound pressure difference limit threshold (Sk_max). Adaptive control method (100) of rolling noise according to one of the preceding claims, in which the sound correction (Cx) is defined so that the resulting acoustic pressure (PAfx) is less than or equal to a predefined maximum comfort threshold (Sc_max) of acoustic pressure.

4.

5. Method for adaptive control (100) of rolling noise according to one of the preceding claims, in which the determination of the sound correction (Cx) comprises: - the determination (E031) of a maximum predicted sound correction (Cx_max_p), corresponding to a sound signal at least defined by a maximum predicted correction sound pressure (PAx_max), to be applied according to the determined roughness level in order to reduce to the maximum possible capacity of the at least one acoustic device (5) the final rolling noise (BRf) perceived; - the determination (E032) of a predicted sound pressure difference (KPx_p) corresponding to the difference between the predicted maximum correction sound pressure (PAx_max) and the predefined reference sound pressure (PRfx); - the comparison (E033) of the predicted sound pressure difference (KPx_p) with the sound pressure difference limit threshold (Sk_max) and, when an exceeding of said threshold is detected, the adjustment (E034) of the predicted maximum sound correction (Cx_max_p) in order to obtain an adjusted sound correction (Cx_A) of which an adjusted correction sound pressure (PAx_A) presents, relative to the reference sound pressure (PRfx), a difference less than or equal to the sound pressure difference limit threshold (Sk_max); the sound correction (Cx) emitted (E04) via the acoustic device (5) being the maximum predicted sound correction (Cx_max_p) or, when an exceeding of the acoustic pressure deviation limit threshold (Sk_max) is detected, the adjusted sound correction (Cx_A). Adaptive rolling noise control method (100) according to one of the preceding claims, in which the predefined reference sound pressure (PRfx) is selected from: - a first predefined correction acoustic pressure (PRfl) corresponding to an acoustic pressure to be applied in the vehicle (1) when it travels along a smooth section of road; - a second correction acoustic pressure (PRf2) previously applied at a time tx for the vehicle (1) traveling a smooth section of road; - a third correction acoustic pressure (PRf3) previously applied at a time tx for the vehicle (1) traveling a portion of road with a roughness level distinct from the portion of road traveled at a instant t; or - a fourth correction acoustic pressure (PRf4) predicted for a portion of road to come at an instant t+x presenting a roughness level distinct from the portion of road traveled at an instant t.

6. Method for adaptive control (100) of rolling noise according to the preceding claim, comprising the modification of the reference acoustic pressure (PRfx) selected when it is detected that the vehicle (1) is traveling on a portion of road or a plurality of portion(s) of road(s) of the same level of roughness for a duration and / or a distance greater than or equal to a predefined duration and / or distance threshold (S_dt).

7. Method for adaptive control (100) of rolling noise according to one of the preceding claims, in which the data acquisition (E01) comprises: - the acquisition of data (E01) relating to a portion of the road traveled being in contact with at least one wheel of the vehicle, the at least one sensor (4) being selected from an accelerometer and / or a microphone arranged at the level of the body, the steering knuckle and / or the at least one wheel of the vehicle (1); and / or - the acquisition of data (E01) relating to a portion of the road located upstream of the vehicle (1) by means of at least one camera, a location means (6) of the vehicle (1) and / or a connected device.

8. Method for adaptive control (100) of rolling noise according to one of the preceding claims, in which the sound correction (Cx) is defined as a function of the correction sound pressure (PAx) and as a function of a sound quality level.

9. Method for adaptive control (100) of rolling noise according to one of the preceding claims, in which the acoustic pressure deviation limit threshold (Sk_max) is determined as a function of a driver preference.

10. Adaptive control system (2) for the rolling noise of a vehicle (1), the system comprising hardware and / or software elements implementing the method according to the preceding claim, the hardware elements comprising at least one data processing unit (3), at least one sensor (4), such as an accelerometer and / or an external microphone, and at least one acoustic device (5), such as a loudspeaker or a speaker.