CN116052628A - Active noise reduction method for automobile engine - Google Patents
Active noise reduction method for automobile engine Download PDFInfo
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- CN116052628A CN116052628A CN202211663842.6A CN202211663842A CN116052628A CN 116052628 A CN116052628 A CN 116052628A CN 202211663842 A CN202211663842 A CN 202211663842A CN 116052628 A CN116052628 A CN 116052628A
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- G—PHYSICS
- G10—MUSICAL INSTRUMENTS; ACOUSTICS
- G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
- G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
- G10K11/16—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
- G10K11/175—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound
- G10K11/178—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound by electro-acoustically regenerating the original acoustic waves in anti-phase
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- G—PHYSICS
- G10—MUSICAL INSTRUMENTS; ACOUSTICS
- G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
- G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
- G10K11/16—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
- G10K11/175—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound
- G10K11/178—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound by electro-acoustically regenerating the original acoustic waves in anti-phase
- G10K11/1785—Methods, e.g. algorithms; Devices
- G10K11/17853—Methods, e.g. algorithms; Devices of the filter
- G10K11/17854—Methods, e.g. algorithms; Devices of the filter the filter being an adaptive filter
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- G—PHYSICS
- G10—MUSICAL INSTRUMENTS; ACOUSTICS
- G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
- G10K2210/00—Details of active noise control [ANC] covered by G10K11/178 but not provided for in any of its subgroups
- G10K2210/10—Applications
- G10K2210/128—Vehicles
- G10K2210/1282—Automobiles
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- Engineering & Computer Science (AREA)
- Acoustics & Sound (AREA)
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- Soundproofing, Sound Blocking, And Sound Damping (AREA)
- Fittings On The Vehicle Exterior For Carrying Loads, And Devices For Holding Or Mounting Articles (AREA)
Abstract
The invention discloses an active noise reduction method for an automobile engine, which comprises the following steps: s1, offline parameter acquisition, including: (1) Acquiring a secondary channel transfer function from a vehicle-mounted loudspeaker to a human ear position; (2) Acquiring weight coefficients of the adaptive filters corresponding to different running conditions of the vehicle; s2, online noise reduction: and according to the current vehicle operation condition, the weight coefficient of the adaptive filter under the operation condition which is the same as or similar to the current vehicle operation condition in the step S1 is called, and a loudspeaker driving signal is generated to send out a counteracting signal. The automobile engine active noise reduction method does not need convergence time in the actual noise reduction process, can improve the stability of an algorithm, can optimize the noise reduction effect of the position of the human ear, improves the noise reduction effect, does not need an error microphone in the online noise reduction process, and can reduce the cost of an active noise reduction system.
Description
Technical Field
The invention relates to the technical field of active noise control, in particular to an active noise reduction method for an automobile engine.
Background
The engine is one of main noise sources of the fuel automobile, in order to reduce the noise of the automobile engine, a host factory adopts various passive noise reduction methods, such as adding sound absorption cotton, a vibration absorber and a damping fin on a transmission path, and using a connecting bushing with better vibration isolation capability, etc., but the passive noise reduction methods can additionally increase the overall weight of the automobile body, even affect the operation stability of the automobile, and meanwhile, the noise reduction effect is limited, so that the engine active noise reduction method is applied to the field of automobile noise vibration control.
The traditional engine active noise reduction system is based on FxLMS algorithm, the system comprises a loudspeaker, an error microphone, a controller and other hardware, the controller obtains real-time engine rotation speed information from a vehicle-mounted CAN bus, generates a reference signal for signal processing, takes the minimum mean square error of main order noise of the engine as a target, updates the weight of a self-adaptive filter, generates a secondary signal to drive the loudspeaker to sound, and further counteracts engine noise in a vehicle. The method can effectively reduce the noise of the engine of the target point in the vehicle, but is limited by the defects of the algorithm, the algorithm needs to converge for a certain time to obtain the optimal self-adaptive filter coefficient, and when the rotation speed of the engine changes rapidly, the algorithm is difficult to ensure real-time tracking of the change, iterates to complete convergence, and influences the control effect. In addition, the error microphone mounting position is affected by the vehicle body structure, resulting in an actual control position that is not the human ear position, and thus the noise reduction effect may be affected on subjective feeling.
Disclosure of Invention
The invention aims to solve the problems in the prior art and provides an active noise reduction method for an automobile engine, which has stable performance, good noise reduction effect and low cost.
In order to achieve the above purpose, the invention adopts the following technical scheme:
an active noise reduction method for an automobile engine comprises the following steps:
s1, offline parameter acquisition, including:
(1) Acquiring a secondary channel transfer function from a vehicle-mounted loudspeaker to a human ear position;
(2) Based on FxLMS algorithm, generating sine and cosine reference signals as input signals of the algorithm by using the engine speed, constructing a Filter-x signal by combining a secondary channel transfer function, and obtaining corresponding self-adaptive Filter weight coefficients under different running conditions of the vehicle by using the minimum mean square value of the noise error signal at the human ear position as an optimization target;
s2, online noise reduction: and according to the current vehicle operation condition, the weight coefficient of the adaptive filter under the operation condition which is the same as or similar to the current vehicle operation condition in the step S1 is called, and a loudspeaker driving signal is generated to send out a counteracting signal.
Preferably, in step S1, the secondary channel transfer function modeling method is as follows: the vehicle-mounted loudspeaker emits a reference signal x (n), a response signal e (n) is collected through a microphone arranged at the position of the human ear, and a weight coefficient W (n) of a modeling filter from the loudspeaker to the position of the human ear is calculated according to the reference signal x (n) and the response signal e (n) and is used as the secondary channel transfer function.
Further, the calculation formula of the weight coefficient W (n) of the secondary channel transfer function is as follows: w (n+1) =w (n) +2μx (n) e (n), where μ is the filter iteration update step size, X (n) = [ X (n), X (n-1),. The term X (n-l+1)] T L is the length of W (n).
Further, the on-board speaker is driven to emit the reference signal x (n) using white noise or a swept frequency signal.
Preferably, the operating conditions of the vehicle include an automobile gear and an engine speed.
Further, the method for acquiring the weight coefficient of the adaptive filter corresponding to different running conditions of the vehicle specifically comprises the following steps:
(1) Acquiring main order noise y of an engine at the ear position in an automobile at different rotation speeds under each gear of the automobile MiNj ；
(2) Respectively calculating the FIR filter coefficient W corresponding to the minimum error of the mean square value of the main order noise of the engine in the vehicle under each operation condition MiNj ；
(3) Construction of adaptive Filter weight coefficient W MN(n) And (5) a database.
Further, engine main order noise y of the human ear position is collected by a microphone arranged at the human ear position MiNj 。
Further, the method for setting the rotation speed of the automobile in each gear is as follows: engine minimum speed N of automobile at each gear position by step k min And a maximum rotation speed N max Discretizing the rotation speed interval between the two, and rotating speed N j The method comprises the following steps: n (N) j ∈[N min ，N min+k ，N min+2k ，......，N max ]。
Further, FIR filter coefficients W MiNj The calculation formula of (2) is as follows: w (W) MiNj ＝-(E[r(n)r T (n)]) -1 E[d(n)r(n)]Where E (x) represents time-averaging the arguments, r (n) is the Filter-x signal, which is the convolution of the input signal with the secondary channel transfer function, d (n) =y MiNj Is the desired signal.
Further, in step S2, the calculation formula of the speaker driving signal y (n) is:
where x is a vector, and the length of x is L, l=1, 2 … … L.
Due to the application of the technical scheme, compared with the prior art, the invention has the following advantages: according to the active noise reduction method for the automobile engine, the optimal adaptive filter weight coefficient of each operation condition of the automobile is obtained offline, the filter weight coefficient can be directly called according to the actual operation condition of the automobile in the actual noise reduction process, convergence time is not needed, and therefore stability of an algorithm can be improved. Meanwhile, the active noise reduction method takes the position of the human ear as a noise reduction target point, so that the noise reduction effect of the position of the human ear can be optimized, and the noise reduction effect is improved. In addition, an error microphone is not needed in the online noise reduction process, so that the cost of the active noise reduction system is reduced, and the applicability of the active noise reduction system is improved.
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FIG. 1 is a flow chart of an active noise reduction method for an automobile engine according to the present invention.
Detailed Description
In order that the above-recited objects, features and advantages of the present invention will become more readily apparent, a more particular description of the invention will be rendered by reference to the appended drawings and appended detailed description.
The implementation flow of the active noise reduction method of the automobile engine is shown in figure 1. The method specifically comprises the following implementation steps:
s1, acquiring offline parameters.
(1) And acquiring a secondary channel transfer function from the vehicle-mounted loudspeaker to the position of the human ear offline.
In this embodiment, the secondary channel transfer function modeling method is as follows: the white noise or sweep frequency signal is used for driving the vehicle-mounted loudspeaker to emit a reference signal x (n), a response signal e (n) is collected through a microphone arranged at the position of the human ear, and the weight coefficient W (n) of the modeling filter from the loudspeaker to the position of the human ear is calculated according to the reference signal x (n) and the response signal e (n) as a secondary channel transfer function.
The weight coefficient W (n) of the secondary channel transfer function is calculated as:
W(n+1)＝W(n)+2μX(n)e(n)
wherein μ is the filter iteration update step size, X (n) = [ X (n), X (n-1),] T l is the length of W (n).
(2) And obtaining the weight coefficient of the corresponding self-adaptive filter under different operation conditions of the vehicle offline.
Based on FxLMS algorithm, two paths of reference signals of sine and cosine are generated by using the engine speed as the input signals of the algorithm, a Filter-x signal is constructed by combining the secondary channel transfer function, the mean square value of the noise error signal at the target point position is minimum as an optimization target, and the corresponding adaptive Filter coefficient is obtained, so that the active control of the noise in the vehicle is realized. In this embodiment, the target point position is the ear position.
When the running working conditions of the vehicle are different, the corresponding engine noise is different, so that a weight coefficient database of the active noise reduction system filter under each running working condition needs to be established, and the active noise reduction system filter is conveniently called according to the corresponding running working condition type in the actual noise reduction process, and further, the active control of the engine noise in the vehicle is accurately and effectively realized.
The operating condition of the vehicle refers to a gear position when the vehicle is running and an engine speed at the gear position.
The filter weight coefficient of the vehicle under each operation condition is obtained as follows:
(1) Acquiring main order noise y of an engine at the ear position in an automobile at different rotation speeds under each gear of the automobile MiNj 。
Taking an example of a car at a certain gear position, the car has the lowest rotation speed N corresponding to the gear position min And a maximum rotation speed N max The minimum rotation speed N of the engine is set at the step length k min And a maximum rotation speed N max Discretizing the speed interval between them, i.e. the speed N after discretization j The method comprises the following steps: n (N) j ∈[N min ，N min+k ，N min+2k ，......，N max ]Thereby obtaining each engine speed of the automobile at the gear position. The microphone is arranged at the position of the human ear, so that the main order noise y of the engine at each rotating speed can be collected MiNj . The smaller the K value, the better the noise reduction effect, but the larger the calculation amount.
Similarly, the main order noise y of the engine at the human ear position in the automobile is obtained when the engine is at different rotation speeds in other gear positions of the automobile MiNj 。
(2) Respectively calculating the FIR filter coefficient W corresponding to the minimum error of the mean square value of the main order noise of the engine in the vehicle under each operation condition MiNj 。
Input signal obtained according to engine speed, stage channel transfer function and engine main order noise y MiNj Calculating the FIR filter coefficient W in corresponding operation condition MiNj The calculation formula is as follows:
W MiNj ＝-(E[r(n)r T (n)]) -1 E[d(n)r(n)]
wherein E (x) represents time averaging the independent variables; r (n) is the Filter-x signal, which is the convolution of the input signal with the secondary channel transfer function; d (n) =y MiNj Is the desired signal.
(3) Construction of adaptive Filter weight coefficient W MN(n) And (5) a database.
Calculating a series of FIR filter coefficients W of the automobile at different gear positions and different rotating speeds through the step (2) MiNj Constructing and forming a weight coefficient W of the adaptive filter MN(n) And (5) a database.
S2, online noise reduction is performed.
According to the current vehicle operation working condition, namely the real-time gear and the engine speed of the vehicle, the adaptive filter weight coefficient which is the same as the current vehicle gear and when the engine speed is the same or similar is called from the filter weight coefficient WMN (n) database, a loudspeaker driving signal y (n) is generated, and a counteracting signal is sent out through a loudspeaker, so that the reduction of the engine noise in the vehicle is realized, and the effect of active noise reduction is achieved.
The calculation formula of the speaker driving signal y (n) is:
where x is a vector, and the length of x is L, l=1, 2 … … L.
The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and to implement the same, but are not intended to limit the scope of the present invention, and all equivalent changes or modifications made according to the spirit of the present invention should be included in the scope of the present invention.
Claims (10)
1. An active noise reduction method for an automobile engine is characterized by comprising the following steps of: the method comprises the following steps:
s1, offline parameter acquisition, including:
(1) Acquiring a secondary channel transfer function from a vehicle-mounted loudspeaker to a human ear position;
(2) Based on FxLMS algorithm, generating sine and cosine reference signals as input signals of the algorithm by using the engine speed, constructing a Filter-x signal by combining a secondary channel transfer function, and obtaining corresponding self-adaptive Filter weight coefficients under different running conditions of the vehicle by using the minimum mean square value of the noise error signal at the human ear position as an optimization target;
s2, online noise reduction: and according to the current vehicle operation condition, the weight coefficient of the adaptive filter under the operation condition which is the same as or similar to the current vehicle operation condition in the step S1 is called, and a loudspeaker driving signal is generated to send out a counteracting signal.
2. The method of active noise reduction for an automotive engine of claim 1, wherein: in step S1, the secondary channel transfer function modeling method includes: the vehicle-mounted loudspeaker emits a reference signal x (n), a response signal e (n) is collected through a microphone arranged at the position of the human ear, and a weight coefficient W (n) of a modeling filter from the loudspeaker to the position of the human ear is calculated according to the reference signal x (n) and the response signal e (n) and is used as the secondary channel transfer function.
3. The method of active noise reduction for an automotive engine of claim 2, wherein: the calculation formula of the weight coefficient W (n) of the secondary channel transfer function is as follows: w (n+1) =w (n) +2μx (n) e (n), where μ is the filter iteration update step size, X (n) = [ X (n), X (n-1),. The term X (n-l+1)] T L is the length of W (n).
4. The method of active noise reduction for an automotive engine of claim 2, wherein: the white noise or swept frequency signal is used to drive the on-board speaker to emit the reference signal x (n).
5. The method of active noise reduction for an automotive engine of claim 1, wherein: the operating conditions of the vehicle include vehicle gear and engine speed.
6. The method of active noise reduction for an automotive engine of claim 5, wherein: the method for acquiring the weight coefficient of the adaptive filter corresponding to different running conditions of the vehicle specifically comprises the following steps:
(1) Acquiring main order noise y of an engine at the ear position in an automobile at different rotation speeds under each gear of the automobile MiNj ；
(2) Respectively calculating the FIR filter coefficient W corresponding to the minimum error of the mean square value of the main order noise of the engine in the vehicle under each operation condition MiNj ；
(3) Construction of adaptive filtersWeight coefficient W of wave device MN(n) And (5) a database.
7. The method of active noise reduction for an automotive engine of claim 6, wherein: capturing engine primary order noise y of human ear position by microphone arranged at human ear position MiNj 。
8. The method of active noise reduction for an automotive engine of claim 6, wherein: the setting method of the rotating speed of the automobile in each gear comprises the following steps: engine minimum speed N of automobile at each gear position by step k min And a maximum rotation speed N max Discretizing the rotation speed interval between the two, and rotating speed N j The method comprises the following steps: n (N) j ∈[N min ，N min+k ，N min+2k ，......，N max ]。
9. The method of active noise reduction for an automotive engine of claim 6, wherein: FIR filter coefficients W MiNj The calculation formula of (2) is as follows: w (W) MiNj ＝-(E[r(n)r T (n)]) -1 E[d(n)r(n)]Where E (x) represents time-averaging the arguments, r (n) is the Filter-x signal, which is the convolution of the input signal with the secondary channel transfer function, d (n) =y MiNj Is the desired signal.
10. The method of active noise reduction for an automotive engine of claim 9, wherein: in step S2, the calculation formula of the speaker driving signal y (n) is:
where x is a vector, and x is L in length, l=1, 2. />
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN117690404A (en) * | 2024-02-04 | 2024-03-12 | 清华大学苏州汽车研究院（相城） | Active control method and device for engine noise of automobile |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN117690404A (en) * | 2024-02-04 | 2024-03-12 | 清华大学苏州汽车研究院（相城） | Active control method and device for engine noise of automobile |
| CN117690404B (en) * | 2024-02-04 | 2024-05-03 | 清华大学苏州汽车研究院（相城） | Active control method and device for engine noise of automobile |
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