Self-adaptive feedforward noise reduction method for motor vehicle
阅读说明：本技术 机动车自适应前馈降噪的方法 (Self-adaptive feedforward noise reduction method for motor vehicle ) 是由 梁秉章 于 2020-05-29 设计创作，主要内容包括：本发明公开了一种机动车自适应前馈降噪的方法,包括：获取噪声信号,并将获取的噪声信号划分成多个分段噪声信号；对于每个分段噪声信号,利用1/3倍频程谱分析其对应的声压数据；声压数据被用于驱动一个或多个换能器,使得一个或多个换能器的输出自适应的背景修正声压信号被引导以用来降低所述噪声信号。本发明旨在通过将声信号划分成多个分段噪声信号并利用1/3倍频程谱分析其对应的声压数据,增加噪声的各频率段分布值,以获得更加精确平缓的降噪效果。(The invention discloses a self-adaptive feedforward noise reduction method for a motor vehicle, which comprises the following steps: acquiring a noise signal, and dividing the acquired noise signal into a plurality of segmented noise signals; for each segmented noise signal, analyzing corresponding sound pressure data by using 1/3 octave spectrum; the acoustic pressure data is used to drive the one or more transducers such that an output adaptive background-corrected acoustic pressure signal of the one or more transducers is directed to reduce the noise signal. The invention aims to increase the distribution value of each frequency segment of noise by dividing an acoustic signal into a plurality of segmented noise signals and analyzing the corresponding sound pressure data by using 1/3 octave spectrum so as to obtain more accurate and gentle noise reduction effect.)
1. A method for adaptive feedforward noise reduction in a motor vehicle, comprising:
acquiring a noise signal, and dividing the acquired noise signal into a plurality of segmented noise signals;
analyzing its corresponding sound pressure data using 1/3 octave spectra based on each segmented noise signal; the acoustic pressure data is used to drive one or more transducers such that an output adaptive background-corrected acoustic pressure signal of the one or more transducers is directed to reduce the noise signal;
wherein the sound pressure data comprises at least an operating total sound pressure data LTBackground noise sound pressure data LBAnd said background corrected sound pressure signal LN。
2. A method for adaptive feedforward noise reduction in a motor vehicle as claimed in claim 1, wherein the analyzing the sound pressure data corresponding thereto using 1/3 octaves spectrum includes:
and performing FFT spectrum transformation calculation on the segmented noise signal after utilizing a hamming window function so as to eliminate discontinuous data at the beginning and the end of the segmented noise signal.
3. A method for adaptive feedforward noise reduction in a motor vehicle as set forth in claim 2, wherein the analyzing the sound pressure data corresponding thereto using 1/3 octaves spectrum further comprises:
classifying the segmented noise signals according to upper and lower limit frequencies to which 1/3 octaves belong according to the spectrum spectral line values after FFT calculation;
carrying out IFFT calculation on the classified segmented noise signals to obtain sound pressure root mean square corresponding to the segmented noise signals;
correcting the A characteristic of the root mean square of the sound pressure by using A weighting network measurement to obtain A weighting 1/3 octave sound pressure level LAi；
Performing equivalent sound pressure level processing on the multi-segment A weighted 1/3 octave sound pressure level to obtain sound pressure data LAeq；
Wherein, according to LAiCalculating LAeqThe method comprises the following steps:
4. a method for automotive adaptive feed forward noise reduction according to claim 3, characterized in that the time window of the segmented noise signal is variable.
5. A method for adaptive feedforward noise reduction in a motor vehicle according to claim 4, wherein the background modified acoustic pressure signal L isNThe calculation method comprises the following steps:
if the total sound pressure data L is operatedTSound pressure data L of background noiseBIs greater than 10dB, then LN＝LT；
If the total sound pressure data L is operatedTSound pressure data L of background noiseBThe absolute value of the difference is 3 to 10 dB;
if the total sound pressure data L is operatedTSound pressure data L of background noiseBIs less than 3dB, then
6. The method for adaptive feedforward noise reduction in an automotive vehicle of claim 1, further comprising:
the acquired noise signal is subtracted from the background corrected acoustic pressure signal output by the transducer to acquire a new noise signal.
7. The method for adaptive feedforward noise reduction in an automotive vehicle of claim 1, further comprising:
applying individually to each segmented noise signal an amplitude scaling factor suitable for application;
combining multiple shifted and amplitude scaled background-corrected sound pressure signals LNTo form a composite anti-noise signal。
8. A method for automotive adaptive feedforward noise reduction according to claim 7, wherein the composite anti-noise signal is multiplied by a sine wave of the noise signal and provided as an input to an adaptive narrowband filter to guide the adaptation of the adaptive narrowband filter.
9. A method for automotive adaptive feed forward noise reduction in accordance with claim 1, wherein said noise signal further comprises engine noise.
10. An apparatus for adaptive feedforward noise reduction of a motor vehicle, for implementing the method for adaptive feedforward noise reduction of a motor vehicle as claimed in any one of claims 1 to 9.
Technical Field
The invention relates to an electronic and automatic noise elimination technology, in particular to a self-adaptive feedforward noise reduction technology for a motor vehicle.
Background
An engine noise cancellation system is an adaptive feed-forward noise reduction system used in a motor vehicle, such as in a passenger compartment or in a muffler assembly, to reduce or cancel engine noise. The sine wave at the frequency to be cancelled is used as the input to the adaptive filter. The engine noise cancellation system also uses one or more microphones as error input transducers. The adaptive filter may change the amplitude and/or phase of the input sine wave. The output of the adaptive filter is applied to one or more transducers (i.e., speakers) that produce sound that is acoustically opposite the undesirable engine noise to be cancelled, to suppress the noise by destructive interference. The noise of the motor vehicle also has road noise besides the engine noise, which provides higher technical challenges for the adaptive feedforward noise reduction of the motor vehicle.
At present, the noise of the automobile road is measured by simply measuring a plurality of sound pressure levels by using a sound pressure meter, and then the average value of the sound pressure levels is taken. However, the sound pressure level measured in this processing method cannot ignore the influence of the wind noise outside the vehicle; in addition, only one total sound pressure level cannot show the distribution value of each frequency band under the noise, so that the targeted noise reduction strategy optimization improvement on the road noise generated by the automobile cannot be performed. Despite ever greater computational processing power, the correctness of the signal-to-noise ratio depends greatly on whether the estimation of the noise is reliable and accurate, and thus the noise reduction effect is much worse for dynamic, rapidly changing sounds or sounds containing higher frequencies.
Disclosure of Invention
The invention mainly solves the technical problem of providing a self-adaptive feedforward noise reduction method for a motor vehicle, and aims to increase the distribution value of each frequency segment of noise by dividing an acoustic signal into a plurality of segmented noise signals and analyzing the corresponding acoustic pressure data by using 1/3 octave spectrums so as to obtain more accurate and smooth noise reduction effect.
In order to solve the technical problem, the invention discloses a method for self-adaptive feedforward noise reduction of a motor vehicle, which comprises the following steps:
acquiring a noise signal, and dividing the acquired noise signal into a plurality of segmented noise signals;
analyzing its corresponding sound pressure data using 1/3 octave spectra based on each segmented noise signal; the acoustic pressure data is used to drive one or more transducers such that an output adaptive background-corrected acoustic pressure signal of the one or more transducers is directed to reduce the noise signal.
The sound pressure data comprises at least total operating sound pressure data LTBackground noise sound pressure data LBAnd the background correction sound pressure signal LN。
In a preferred embodiment, the analyzing the corresponding sound pressure data by using 1/3 octave spectrum includes performing FFT spectrum transformation calculation on the segmented noise signal after using a hamming window function, so that discontinuous data at the beginning and end of the segmented noise signal is eliminated.
In a preferred embodiment, the analyzing the sound pressure data corresponding to the sound pressure data by using 1/3 octave spectrum further comprises:
classifying the spectrum spectral line values after FFT calculation according to the upper and lower limit frequency division of the segmented noise signals in 1/3 octaves;
classifying the segmented noise signals according to upper and lower limit frequencies to which 1/3 octaves belong according to the spectrum spectral line values calculated by FFT, namely the acoustic energy amplitude spectral lines of the segmented noise signals;
carrying out IFFT calculation on the classified segmented noise signals to obtain sound pressure root mean square corresponding to the segmented noise signals;
correcting the A characteristic of the root mean square of the sound pressure by using A weighting network measurement to obtain A weighting 1/3 octave sound pressure level LAi；
Performing equivalent sound pressure level processing on the multi-segment A weighted 1/3 octave sound pressure level to obtain sound pressure data LAeq；
Wherein, according to LAiCalculating LAeqThe method comprises the following steps:
further, the time window of the segmented noise signal is variable. The time window of the segmented noise signal may be 10s, 20 or 30 s.
Specifically, the background correction sound pressure signal LNThe calculation method comprises the following steps:
if the total sound pressure data L is operatedTSound pressure data L of background noiseBIs greater than 10dB, then LN＝LT；
If the total sound pressure data L is operatedTSound pressure data L of background noiseBThe absolute value of the difference is 3 to 10 dB;
if the total sound pressure data L is operatedTSound pressure data L of background noiseBThe absolute value of the difference of (a) is less than 3dB,
in a preferred embodiment, the method further comprises:
the acquired noise signal is subtracted from the background corrected acoustic pressure signal output by the transducer to acquire a new noise signal.
In a preferred embodiment, the method further comprises:
applying individually to each segmented noise signal an amplitude scaling factor suitable for application;
combining multiple shifted and amplitude scaled background-corrected sound pressure signals LNTo form a composite anti-noise signal. Further, the composite anti-noise signal is multiplied by a sine wave of the noise signal and provided as an input to an adaptive narrowband filter to guide adaptation of the adaptive narrowband filter.
In a preferred embodiment, the noise signal further comprises engine noise. Background correction sound pressure signal LNIs directed into the vehicle cabin to eliminate engine noise and road noise.
The invention has the beneficial effects that: the adaptive feedforward noise reduction device for motor vehicle is aimed at increasing distribution value of noise in each frequency band by dividing sound signal into several segmental noise signals and analyzing their correspondent sound pressure data by using 1/3 octave spectrum, then applying the output of adaptive filter to produce background corrected sound pressure signal LNThe background corrected sound pressure signal L, the one or more transducers (i.e. loudspeakers) ofNIn contrast to the noise acoustics to be cancelled, to suppress the noise by destructive interference to obtain a more precise and gradual noise reduction effect. Background corrected sound pressure signal LNNoise reduction strategy system combined with vehicle typeAnd the road noise elimination effect of the vehicle type is improved in a targeted manner.
Drawings
The invention and its advantages will be better understood by studying the following non-limiting examples, which are given by way of illustration in the accompanying drawings, in which:
FIG. 1 is a flow chart illustrating a method for adaptive feedforward noise reduction in a motor vehicle according to an embodiment of the present invention.
Detailed Description
Referring to the drawings, wherein like reference numbers refer to like elements throughout, the principles of the present invention are illustrated in an appropriate environment. The following description is based on illustrated embodiments of the invention and should not be taken as limiting the invention with regard to other embodiments that are not detailed herein.
The word "embodiment" is used herein to mean serving as an example, instance, or illustration. In addition, the articles "a" and "an" as used in this specification and the appended claims may generally be construed to mean "one or more" unless specified otherwise or clear from context to be directed to a singular form.
In the description of the present invention, it is to be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", and the like, are used in the orientations and positional relationships indicated in the drawings, which are merely for convenience of description and simplicity of description, and do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus are not to be considered as limiting the present invention.
In the description of the present invention, it is to be noted that, unless otherwise explicitly specified or limited, the terms "disposed," "connected," and "connected" are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected; may be mechanically connected, may be electrically connected or may be in communication with each other; they may be directly connected or indirectly connected through intervening media, or may be connected through the interconnection of two elements or through the interaction of two elements. The specific meaning of the above terms in the present invention can be understood by those of ordinary skill in the art according to specific situations.
Further, unless expressly stated or limited otherwise, the first feature "on" or "under" the second feature may comprise direct contact of the first and second features, or may comprise direct contact of the first and second features through another feature in between. Further, the first feature being "on," "above" and "over" the second feature includes the first feature being directly on and obliquely above the second feature, or indicating that the first feature is higher in level than the second feature. A first feature being "under," "below," and "beneath" a second feature includes the first feature being directly under and obliquely below the second feature, or meaning that the first feature is at a lesser elevation than the second feature.
The following disclosure provides many different embodiments or examples for implementing different features of the invention. To simplify the disclosure of the present invention, the components and arrangements of specific examples are described below. Of course, they are merely examples and are not intended to limit the present invention. Furthermore, the present invention may repeat reference numerals and/or reference letters in the various examples, which have been repeated for purposes of simplicity and clarity and do not in themselves dictate a relationship between the various embodiments and/or arrangements discussed. In addition, the present invention provides examples of various specific processes and materials, but one of ordinary skill in the art may recognize applications of other processes and/or uses of other materials.
Example 1
First, with reference to fig. 1, a method for adaptive feedforward noise reduction of a motor vehicle according to embodiment 1 of the present invention includes:
s1, acquiring a noise signal, and dividing the acquired noise signal into a plurality of segmented noise signals, wherein the noise signal is a road noise;
s2, analyzing corresponding sound pressure data by using 1/3 octave spectrum based on each segmented noise signal;
s3, the acoustic pressure data is used to drive one or more transducers such that an output adaptive background-corrected acoustic pressure signal of the one or more transducers is directed to reduce the noise signal.
The sound pressure data comprises total operating sound pressure data LTBackground noise sound pressure data LBAnd said background corrected acoustic pressure signal LN。
In step S2, analyzing the corresponding sound pressure data by using 1/3 octave spectrum, including:
s21, performing FFT spectrum transformation calculation on the segmented noise signal after utilizing a hamming window function so as to eliminate discontinuous data at the beginning and the end of the segmented noise signal;
s22, classifying the segmented noise signals according to upper and lower limit frequencies to which 1/3 octaves belong by referring to spectrum line values calculated by FFT, namely acoustic energy amplitude spectrum lines of the segmented noise signals;
s23, carrying out IFFT calculation on the classified segmented noise signals to obtain sound pressure root mean square corresponding to the segmented noise signals;
s24, correcting the A characteristic of the root mean square of the sound pressure by utilizing the measurement of the A weighting network to obtain the A weighting 1/3 octave sound pressure level LAi；
S26, carrying out equivalent sound pressure level processing on the multiple segments of A weighted 1/3 octave sound pressure levels to obtain sound pressure data LAeq；
Wherein, according to LAiCalculating LAeqThe method comprises the following steps:
the time window of the segmented noise signal is variable. The time window of the segmented noise signal of this embodiment is 20 s.
Specifically, performing IFFT on the energy amplitude of the segmented noise signal divided by 1/3 octaves to obtain sound pressure data corresponding to the segmented noise signal, including:
the sound pressure level L of the segmented noise signal under 28 frequency bands in 1/3 octaves is calculated by using the formula (1)P：
A weighting attenuation correction is carried out on the sound pressure levels under 28 frequency bands in 1/3 octaves of each noise signal section, the obtained A weighting sound pressure levels under 28 frequency bands are calculated by using a formula (2):
since the 10s segmented noise signal contains 20 frame data segments, the equivalent continuous A weighted sound pressure level L under the 10s segmented noise signal can be obtained according to the formula (3)AeqNamely:
in step S2, the background correction sound pressure signal L isNThe calculation method comprises the following steps:
if the total sound pressure data L is operatedTSound pressure data L of background noiseBIs greater than 10dB, then LN＝LT；
If the total sound pressure data L is operatedTSound pressure data L of background noiseBThe absolute value of the difference is 3 to 10 dB;
if the total sound pressure data L is operatedTSound pressure data L of background noiseBThe absolute value of the difference of (a) is less than 3dB,
as the vehicle adaptive feed forward noise reduction advances, acquiring a new noise signal is subtracted from the background modified acoustic pressure signal output by the transducer to acquire a new noise signal.
The method further comprises the following steps:
applying individually to each segmented noise signal an amplitude scaling factor suitable for application;
combining multiple shifted and amplitude scaled background-corrected sound pressure signals LNTo form a composite anti-noise signal. Further, the composite anti-noise signal is multiplied by a sine wave of the noise signal and provided as an input to an adaptive narrowband filter to guide adaptation of the adaptive narrowband filter.
The method of adaptive feedforward noise reduction for motor vehicles of the present embodiment is intended to increase the distribution value of each frequency segment of noise by dividing an acoustic signal into a plurality of segmented noise signals and analyzing the corresponding sound pressure data thereof using 1/3 octave spectrum, and then applying the output of an adaptive filter to generate a background corrected sound pressure signal LNThe background corrected sound pressure signal L, the one or more transducers (i.e. loudspeakers) ofNAs opposed to the noise acoustics to be cancelled, to suppress the noise by destructive interference to obtain a more precise and gradual noise reduction effect. Background corrected sound pressure signal LNAnd making a noise reduction strategy by combining the vehicle type, thereby pertinently improving the road noise elimination effect of the vehicle type.
Example 2
Only the differences between embodiment 2 and embodiment 1 will be described below, and the descriptions of the similarities will be omitted. The noise signal also includes engine noise.
Background corrected sound pressure signal LNIs directed into the vehicle cabin to eliminate engine noise and road noise. Background corrected sound pressure signal LNAnd the comprehensive noise reduction strategy is formulated by combining the vehicle type and the road condition, so that the customization is flexible, and the road noise elimination effect of the vehicle type is improved.
Example 3
Only the differences between embodiment 3 and embodiment 1 will be described below, and the descriptions of the similarities will be omitted.
In step S2, the analyzing the sound pressure data corresponding to the sound source data by using 1/3 octave spectrum includes:
s21, performing FFT spectrum transformation calculation on the segmented noise signals;
s22, classifying the spectrum spectral line values after FFT calculation according to the upper and lower limit frequency division of the segmented noise signals in 1/3 octaves;
s23, carrying out IFFT calculation on the energy amplitude of the segmented noise signal with 1/3 octaves to obtain sound pressure data corresponding to the segmented noise signal;
s24, processing the sound pressure data by using a hamming window function, so that the discontinuous data at the beginning and end of the sound pressure data are eliminated.
The noise signal is a time-varying signal, but the characteristic change is less in a short time range, so that each section of data can be seen as a stable signal in the short time, and the error of the frequency spectrum data after fast Fourier transform can be reduced).
While the invention has been described above with reference to certain embodiments, various modifications may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In particular, the various features of the various embodiments of the present disclosure may be used in any combination, provided that there is no structural conflict, and the combination is not exhaustively described in this specification for brevity and resource conservation. Therefore, it is intended that the invention not be limited to the particular embodiments disclosed, but that the invention will include all embodiments falling within the scope of the appended claims.