Active noise reduction method and system for automobile engine noise based on dynamic partition

Abstract

The invention relates to an automobile engine noise active noise reduction method and system based on dynamic partition, and belongs to the field of noise control. The method comprises the steps that engine noise characteristic parameters are collected, a crankshaft inertia compensation item is obtained based on the engine noise characteristic parameters, and noise compensation frequency is obtained; generating an active cancellation sound wave based on the noise compensation frequency; generating a dynamic partition driving signal according to the active offset sound wave and executing a dynamic partition noise reduction instruction; and introducing a regulation and control mechanism, and regulating and controlling a dynamic partition driving signal based on the regulation and control mechanism. According to the method, frequency tracking under the variable rotating speed working condition is achieved, the sound field space heterogeneity is comprehensively considered, and the noise reduction performance under the complex working condition can be remarkably improved.

Description

Technical Field

[0001] The invention belongs to the technical field of noise control, and in particular relates to a method and system for actively reducing automobile engine noise based on dynamic partitioning. Background Art

[0002] Active noise reduction technology achieves noise cancellation by generating sound waves with opposite phase to the noise. It has been applied in the fields of headphones and automobiles. In the automotive field, active noise reduction technology mainly targets low-frequency engine noise and road noise. It achieves noise reduction by emitting reverse sound waves through the speakers in the car. The existing technology has also been extended to three-dimensional noise reduction and realizes full-range noise reduction in the car through multi-channel sound field control, but the technical threshold is high and the cost is expensive. At present, active noise reduction methods still have certain shortcomings: (1) Frequency tracking delay: Traditional methods rely on FFT or fixed-order tracking and cannot respond to sudden changes in engine speed (such as sudden acceleration) in real time, resulting in a lag in the generation of reverse sound waves and a sharp drop in noise reduction effect. (2) Limitation of sound field control: Most systems use unified noise reduction for the entire car, ignoring the differences in passenger positions, resulting in poor noise reduction effect in local areas. (3) Poor environmental adaptability: The strategy cannot be dynamically adjusted according to road conditions (such as tunnels, heavy rain), resulting in insufficient cancellation of high-speed wind noise or rain noise. (4) Weak user experience: User comfort is not fully considered, resulting in poor user experience. Summary of the invention

[0003] In order to solve the above problems existing in the prior art, the present invention provides a method and system for active noise reduction of automobile engine noise based on dynamic partitioning.

[0004] The purpose of the present invention can be achieved through the following technical solutions: A method for actively reducing noise of an automobile engine based on dynamic partitioning, the implementation of the method for actively reducing noise of an automobile engine includes the following steps: Collecting engine noise characteristic parameters, obtaining crankshaft inertia compensation items based on the engine noise characteristic parameters and obtaining noise compensation frequency; generating an active cancellation sound wave based on the noise compensation frequency; Generate a dynamic partition driving signal according to the active cancellation sound wave and execute a dynamic partition noise reduction instruction; A regulation mechanism is introduced, and the dynamic partition driving signal is regulated based on the regulation mechanism.

[0005] Preferably, the acquisition of the noise compensation frequency includes: The engine noise characteristic parameters include engine speed, engine order and crankshaft inertia compensation coefficient, and the crankshaft inertia compensation term is calculated based on the engine noise characteristic parameters; The basic noise frequency is defined based on the engine noise characteristic parameters, which can be mathematically described as ,in,f base (t) is the basic noise frequency at time t, rpm t is the engine speed at time t, O is the engine order; The noise compensation frequency is obtained by compensating the basic noise frequency through the crankshaft inertia compensation term.

[0006] Preferably, the calculation formula of the crankshaft inertia compensation term is: , where β(t) is the crankshaft inertia compensation term at time t, α is the crankshaft inertia compensation coefficient, rpm t is the engine speed at time t, and t is the time.

[0007] Preferably, the mathematical description of the noise compensation frequency is ,in, f 0 (t) is the noise compensation frequency at time t.

[0008] Preferably, the generation of the dynamic partition driving signal includes: Deploy speakers and microphones at fixed locations in the car, play a frequency sweep signal through the speakers, and record the response of the microphone to generate a transfer function; A transfer function channel model is generated based on the transfer function. The mathematical description of the transfer function channel model is: , where H(f) is the transfer function channel model, h ij (f) is the transfer function from the jth loudspeaker to the ith microphone, i=1,2,…,n,j=1,2,…,m; Generate a channel activation instruction through a pressure sensor to activate only the transfer function channel of the occupant area and update the transfer function channel model; The dynamic partition drive signal is generated according to the transfer function channel model.

[0009] Preferably, the mathematical description of the transfer function is , where R(t) i is the microphone response signal of the i-th microphone, T(t) j is the speaker output signal of the jth speaker.

[0010] Preferably, the mathematical description of the dynamic partition drive signal is , wherein Y(t) is the dynamic partition driving signal at time t, y(t) is the active cancellation sound wave at time t, and the dynamic partition noise reduction instruction is executed based on the dynamic partition driving signal.

[0011] Preferably, the regulatory mechanism includes: Collecting road condition information and physiological signals, wherein the road condition information includes tunnel distance and real-time vehicle speed, and the physiological signals include heart rate variability signals and skin conductance signals; The preloading time is calculated based on the road condition information and a noise reduction preloading instruction is generated. The calculation formula of the preloading time is t pre =L t / v t , where L t is the distance between the vehicle and the tunnel at time t, v t is the real-time vehicle speed at time t; Calculating a comfort index according to the physiological signal; When the comfort index is greater than a preset upper threshold value, the dynamic partition driving signal is regulated to attenuate the noise reduction intensity; when the comfort index is less than a preset lower threshold value, the dynamic partition driving signal is regulated to enhance the noise reduction intensity.

[0012] Preferably, the calculation formula of the comfort index is: , where ω 1 is the heart rate variability signal weight, ω 2 is the skin conductance signal weight, HRV high HRV is the energy intensity of the heart rate variability signal in the middle and high frequency bands. total is the total energy of the heart rate variability signal in the full frequency band, EDA is the skin conductance signal, and K is the normalization coefficient of the skin conductance change rate.

[0013] An active noise reduction system for automobile engine noise based on dynamic partitioning, used to implement the above-mentioned active noise reduction method for automobile engine noise, including a noise frequency dynamic compensation module, an active cancellation sound wave synthesis module, a dynamic partition noise reduction module and an intelligent control module; The noise frequency dynamic compensation module is used to collect engine noise characteristic parameters, obtain crankshaft inertia compensation items based on the engine noise characteristic parameters, and obtain noise compensation frequency; The active cancellation sound wave synthesis module is used to generate active cancellation sound waves based on the noise compensation frequency; The dynamic partition noise reduction module is used to generate a dynamic partition driving signal according to the active cancellation sound wave and execute a dynamic partition noise reduction instruction; The intelligent control module is used to introduce a control mechanism, and to control the dynamic partition driving signal based on the control mechanism.

[0014] The beneficial effects of the present invention are: (1) Dynamic adaptability is enhanced by the crankshaft inertia compensation item, which can respond to sudden changes in engine speed (such as sudden acceleration) in real time and generate active sound waves to cancel them out, significantly improving the noise reduction effect.

[0015] (2) Dynamic zoning control can be used to improve the noise reduction effect in local areas and reduce speaker power consumption, thereby achieving energy efficiency and cost optimization.

[0016] (3) Enhance environmental adaptability through control mechanisms, fully consider road conditions and user comfort, improve noise reduction effects and enhance user experience. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to facilitate understanding by those skilled in the art, the present invention is further described below with reference to the accompanying drawings.

[0018] Figure 1 The present invention is a flowchart of the steps of a method for active noise reduction of automobile engine noise based on dynamic partitioning. DETAILED DESCRIPTION

[0019] In order to further explain the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the specific implementation methods, structures, features and effects of the present invention are described in detail below in conjunction with the accompanying drawings and preferred embodiments.

[0020] The working principle and use process of the present invention: See also Figure 1 , an active noise reduction method for automobile engine noise based on dynamic partitioning, comprising: S1: collecting engine noise characteristic parameters, obtaining crankshaft inertia compensation items based on the engine noise characteristic parameters and obtaining noise compensation frequency; S2: Generate an active cancellation sound wave based on the noise compensation frequency. The mathematical description of the active cancellation sound wave is y(t)=sin[2π· f 0 (t)·t+π], where y(t) is the active cancellation sound wave at time t; S3: generating a dynamic partition driving signal according to the active cancellation sound wave and executing a dynamic partition noise reduction instruction; S4: introducing a regulation mechanism, and regulating the dynamic partition driving signal based on the regulation mechanism.

[0021] In this embodiment, the crankshaft inertia compensation item is obtained based on the engine noise characteristic parameter and the noise compensation frequency is obtained, which can be specifically implemented by the following steps: S101: The engine noise characteristic parameters include engine speed (rpm), engine order and crankshaft inertia compensation coefficient. The engine order is determined by the number of cylinders and the ignition cycle. For a six-cylinder four-stroke engine, the crankshaft rotates twice and each cylinder ignites once, that is, there are three ignition events per rotation. The engine order is 3. The crankshaft inertia compensation coefficient characterizes the response delay characteristics of the mechanical system. It is generally 0.02-0.05 for gasoline vehicles and 0.05-0.08 for diesel vehicles due to greater inertia. The crankshaft inertia compensation term is calculated based on the engine noise characteristic parameters. The calculation formula is: , where β is the crankshaft inertia compensation term at time t, α is the crankshaft inertia compensation coefficient, rpm t is the engine speed at time t, t is the time; the crankshaft inertia compensation term quantifies the degree to which the actual noise frequency (i.e., the noise compensation frequency) deviates from the theoretical value (i.e., the basic noise frequency) when the crankshaft inertia causes a sudden change in the engine speed. When the engine speed suddenly changes due to the crankshaft inertia, the actual noise frequency is higher than the theoretical value, and positive compensation is required. When the engine speed suddenly changes due to the crankshaft inertia (d(rpm) / dt>0), the actual noise frequency is higher than the theoretical value, and positive compensation is required. When the engine speed suddenly changes due to the crankshaft inertia (d(rpm) / dt<0), the actual noise frequency is lower than the theoretical value, and negative compensation is required.

[0022] S102: defining a basic noise frequency based on the engine noise characteristic parameter, which is mathematically described as ,in, f base (t) is the basic noise frequency at time t, rpm t is the engine speed at time t, O is the engine order; S103: Compensating the basic noise frequency by the crankshaft inertia compensation term to obtain the noise compensation frequency, which is mathematically described as ,in, f 0 (t) is the noise compensation frequency at time t, through which noise changes can be predicted in advance and noise reduction can be compensated. Example: When the engine speed of a four-cylinder gasoline car accelerates from 1500rpm to 3000rpm (taking 2 seconds), the engine speed at t=1 second is 2250rpm, and its basic noise frequency is f base (1)=(2250×2) / 60=75Hz, the crankshaft inertia compensation term is [0.03×(3000-1500)] / 2=22.5Hz, then the noise compensation frequency is f 0 (1)=75+22.5=97.5Hz.

[0023] In this embodiment, the dynamic partition driving signal is generated according to the active cancellation of the sound wave and the dynamic partition noise reduction instruction is executed, which can be specifically implemented by the following steps: S301: Deploy speakers and microphones at fixed positions in the car (the installation position must correspond to the seat position in the car), play a sweep signal (the frequency changes continuously from 20Hz to 20KHz) through the speaker, and record the response of the microphone to generate a transfer function, which is mathematically described as , where h ij (f) is the transfer function from the jth loudspeaker to the ith microphone, R(t) i is the microphone response signal of the i-th microphone, T(t) j is the speaker output signal of the jth speaker; S302: Generate a transfer function channel model based on the transfer function. The mathematical description of the transfer function channel model is: , where H(f) is the transfer function channel model, i=1,2,…,n, j=1,2,…,m; S303: Generate a channel activation instruction through the pressure sensor arranged under the seat, activate only the transfer function channel in the passenger area and update the transfer function channel model, and set the transfer function on the channel in the non-passenger area to zero, that is, when only the driver is in the seat, activate h 11 (f) Channel: When people get on or off the bus, the channel at the corresponding position is activated or closed; S304: Generate the dynamic partition driving signal according to the transfer function channel model, which is mathematically described as , where Y(t) is the dynamic partition driving signal at time t, and the dynamic partition noise reduction instruction is executed based on the dynamic partition driving signal, that is, the dynamic partition driving signal is accurately output to the position where people are sitting in the car through the speaker to offset the noise, and no noise control is performed for unoccupied seats; In this embodiment, the dynamic partition driving signal is regulated based on the regulation mechanism, which can be implemented by the following steps: S401: collecting road condition information and physiological signals, wherein the road condition information includes tunnel distance and real-time vehicle speed, and the physiological signals include heart rate variability signals and skin conductance signals; S402: Calculate the preloading time based on the road condition information and generate a noise reduction preloading instruction. The calculation formula of the preloading time is t pre =L t / v t , where L t is the distance between the vehicle and the tunnel at time t, v t is the real-time vehicle speed at time t, i.e., t in advance pre The dynamic partition driving signal is loaded to avoid a loud noise when the vehicle enters the tunnel; S403: Calculate the comfort index according to the physiological signal, the calculation formula is: , where ω 1 is the heart rate variability signal weight, ω 2 is the skin conductance signal weight, HRV high HRV is the energy intensity of the heart rate variability signal in the medium and high frequency band (0.15-0.4 Hz), corresponding to parasympathetic nerve activity (larger in relaxation state and smaller in tension state). total is the total energy of the heart rate variability signal in the full frequency band (0-0.4 Hz). When the value is close to 1, the parasympathetic nervous system is dominant (relaxation), When the value is close to 0, the sympathetic nerves are dominant (tension / anxiety), EDA is the skin conductance signal, K is the normalization coefficient of the skin conductance change rate, and When it is greater than 0, the user's tension increases. When it is less than 0, the user is in a relaxed state; S404: When the comfort index is greater than a preset upper threshold, the dynamic partition driving signal is regulated to attenuate the noise reduction intensity; when the comfort index is less than a preset lower threshold, the dynamic partition driving signal is regulated to enhance the noise reduction intensity.

[0024] An active noise reduction system for automobile engine noise based on dynamic partitioning, comprising a noise frequency dynamic compensation module, an active cancellation sound wave synthesis module, a dynamic partition noise reduction module and an intelligent control module; The noise frequency dynamic compensation module is used to collect engine noise characteristic parameters, obtain crankshaft inertia compensation items based on the engine noise characteristic parameters, and obtain noise compensation frequency; The active cancellation sound wave synthesis module is used to generate an active cancellation sound wave based on the noise compensation frequency. The mathematical description of the active cancellation sound wave is y(t)=sin[2π· f 0 (t)·t+π], where y(t) is the active cancellation sound wave at time t; The dynamic partition noise reduction module is used to generate a dynamic partition driving signal according to the active cancellation sound wave and execute a dynamic partition noise reduction instruction; The intelligent control module is used to introduce a control mechanism, and to control the dynamic partition driving signal based on the control mechanism.

[0025] The computer storage medium of the embodiment of the present invention may adopt any combination of one or more computer-readable media. The computer-readable medium may be a computer-readable signal medium or a computer-readable storage medium. The computer-readable storage medium may be, for example, but not limited to, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, device or device, or any combination of the above. More specific examples (non-exhaustive list) of computer-readable storage media include: an electrical connection with one or more wires, a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the above. In this document, a computer-readable storage medium may be any tangible medium containing or storing a program that may be used by or in combination with an instruction execution system, device or device.

[0026] Computer-readable signal media may include data signals propagated in baseband or as part of a carrier wave, which carry computer-readable program code. Such propagated data signals may take a variety of forms, including but not limited to electromagnetic signals, optical signals, or any suitable combination of the above. Computer-readable signal media may also be any computer-readable medium other than a computer-readable storage medium, which may send, propagate, or transmit a program for use by or in conjunction with an instruction execution system, apparatus, or device.

[0027] The program code included on the computer readable medium can be transmitted with any appropriate medium, including but not limited to wireless, electric wire, optical cable, RF, etc., or any suitable combination of the above. The computer program code for performing the operation of the present invention can be written in one or more programming languages ​​or their combinations, and the programming language includes object-oriented programming languages-such as Java, Smalltalk, C++, and also includes conventional procedural programming languages-such as "C" language or similar programming languages. The program code can be executed completely on the user's computer, partially on the user's computer, as an independent software package, partially on the user's computer and partially on the remote computer, or completely on the remote computer or server. In the case of a remote computer, the remote computer can be connected to the user's computer through any type of network, including a local area network (LAN) or a wide area network (WAN), or it can be connected to an external computer (for example, using an Internet service provider to connect through the Internet).

[0028] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technical personnel in this field can make some changes or modify the technical contents disclosed above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A method for active noise reduction of automobile engine noise based on dynamic partitioning, characterized in that: The implementation of the active noise reduction method for automobile engine noise includes the following steps: Collecting engine noise characteristic parameters, obtaining crankshaft inertia compensation items based on the engine noise characteristic parameters and obtaining noise compensation frequency; generating an active cancellation sound wave based on the noise compensation frequency; Generate a dynamic partition driving signal according to the active cancellation sound wave and execute a dynamic partition noise reduction instruction; A regulation mechanism is introduced, and the dynamic partition driving signal is regulated based on the regulation mechanism.

2. The method for active noise reduction of automobile engine noise according to claim 1, characterized in that: The acquisition of the noise compensation frequency includes: The engine noise characteristic parameters include engine speed, engine order and crankshaft inertia compensation coefficient, and the crankshaft inertia compensation term is calculated based on the engine noise characteristic parameters; The basic noise frequency is defined based on the engine noise characteristic parameters, which can be mathematically described as ,in, f base (t) is the basic noise frequency at time t, rpm t is the engine speed at time t, O is the engine order; The noise compensation frequency is obtained by compensating the basic noise frequency through the crankshaft inertia compensation term.

3. The method for active noise reduction of automobile engine noise according to claim 2, characterized in that: The calculation formula of the crankshaft inertia compensation term is: , where β(t) is the crankshaft inertia compensation term at time t, α is the crankshaft inertia compensation coefficient, rpm t is the engine speed at time t, and t is the time.

4. The method for active noise reduction of automobile engine noise according to claim 3, characterized in that: The mathematical description of the noise compensation frequency is ,in, f 0(t) is the noise compensation frequency at time t.

5. The method for active noise reduction of automobile engine noise according to claim 1, characterized in that: The generation of the dynamic partition driving signal includes: Deploy speakers and microphones at fixed locations in the car, play a frequency sweep signal through the speakers, and record the response of the microphone to generate a transfer function; A transfer function channel model is generated based on the transfer function. The mathematical description of the transfer function channel model is: , where H(f) is the transfer function channel model, h ij (f) is the transfer function from the jth loudspeaker to the ith microphone, i=1,2,…,n,j=1,2,…,m; Generate a channel activation instruction through a pressure sensor to activate only the transfer function channel of the occupant area and update the transfer function channel model; The dynamic partition drive signal is generated according to the transfer function channel model.

6. The method for active noise reduction of automobile engine noise according to claim 5, characterized in that: The mathematical description of the transfer function is , where R(t) i is the microphone response signal of the i-th microphone, T(t) j is the speaker output signal of the jth speaker.

7. The method for active noise reduction of automobile engine noise according to claim 6, characterized in that: The mathematical description of the dynamic partition driving signal is , wherein Y(t) is the dynamic partition driving signal at time t, y(t) is the active cancellation sound wave at time t, and the dynamic partition noise reduction instruction is executed based on the dynamic partition driving signal.

8. The method for active noise reduction of automobile engine noise according to claim 1, characterized in that: The regulatory mechanisms include: Collecting road condition information and physiological signals, wherein the road condition information includes tunnel distance and real-time vehicle speed, and the physiological signals include heart rate variability signals and skin conductance signals; The preloading time is calculated based on the road condition information and a noise reduction preloading instruction is generated. The calculation formula of the preloading time is t pre =L t / v t , where L t is the distance between the vehicle and the tunnel at time t, v t is the real-time vehicle speed at time t; Calculating a comfort index according to the physiological signal; When the comfort index is greater than a preset upper threshold value, the dynamic partition driving signal is regulated to attenuate the noise reduction intensity; when the comfort index is less than a preset lower threshold value, the dynamic partition driving signal is regulated to enhance the noise reduction intensity.

9. The method for active noise reduction of automobile engine noise according to claim 8, characterized in that: The calculation formula of the comfort index is: , where ω1 is the weight of the heart rate variability signal, ω2 is the weight of the skin conductance signal, HRV high HRV is the energy intensity of the heart rate variability signal in the middle and high frequency bands. total is the total energy of the heart rate variability signal in the full frequency band, EDA is the skin conductance signal, and K is the normalization coefficient of the skin conductance change rate.

10. An active noise reduction system for automobile engine noise based on dynamic partitioning, characterized in that: The system is applied to the active noise reduction method for automobile engine noise as claimed in any one of claims 1 to 9, comprising a noise frequency dynamic compensation module, an active cancellation sound wave synthesis module, a dynamic partition noise reduction module and an intelligent control module; The noise frequency dynamic compensation module is used to collect engine noise characteristic parameters, obtain crankshaft inertia compensation items based on the engine noise characteristic parameters, and obtain noise compensation frequency; The active cancellation sound wave synthesis module is used to generate active cancellation sound waves based on the noise compensation frequency; The dynamic partition noise reduction module is used to generate a dynamic partition driving signal according to the active cancellation sound wave and execute a dynamic partition noise reduction instruction; The intelligent control module is used to introduce a control mechanism, and to control the dynamic partition driving signal based on the control mechanism.

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