Vehicle and pedestrian warning system based on active noise reduction and control method

Abstract

The invention discloses a vehicle and pedestrian warning system based on active noise reduction and a control method, and relates to the technical field of vehicle active safety and noise reduction, and the method comprises the steps that a warning sound generation module synthesizes a source audio signal according to vehicle driving data and divides the source audio signal into two synchronous paths; the first path drives the outside-vehicle audio output unit to radiate sound waves outwards; and the second path is directly transmitted to the reverse sound wave generation module as a reference signal. The in-vehicle sound collection unit collects and feeds back in-vehicle residual noise signals. And the reverse sound wave generation module generates a reverse counteracting audio signal through an adaptive filtering algorithm by using the reference signal and the residual noise signal, and drives the in-vehicle audio output unit to play reverse sound waves, and the reverse sound waves and warning sound noise transmitted into the vehicle are superposed and counteracted. According to the invention, the source signal is directly used as a reference signal, delay and distortion caused by physical acquisition are eliminated, and quietness in the vehicle is effectively improved while the warning effect outside the vehicle is guaranteed.

Description

A vehicle and pedestrian warning system and control method based on active noise reduction Technical Field

[0001] This application relates to the field of vehicle active safety and noise reduction technology, and in particular to a vehicle pedestrian warning system and control method based on active noise reduction. Background Technology

[0002] Currently, with the popularization of new energy vehicle technology, the quietness of pure electric vehicles and hybrid vehicles at low speeds has improved. To address the pedestrian safety hazards caused by excessive quietness, regulations mandate that these vehicles be equipped with Vehicle Audio Alert Systems (AVAS). This system emits simulated engine sounds or specific alert tones through external speakers when the vehicle is traveling at low speeds or reversing. This ensures that visually impaired individuals and pedestrians nearby can promptly perceive the approach and location of the vehicle through hearing.

[0003] For the application of the aforementioned warning sounds, existing technical solutions typically place the sound-generating device inside the vehicle's front bumper or grille. The controller reads the vehicle's speed and gear information in real time, calls a pre-stored audio algorithm to synthesize a warning sound signal that varies with vehicle speed, and drives external speakers to radiate sound waves outwards. Regarding in-vehicle acoustic environment management, some models have begun to introduce active noise cancellation technology. The conventional approach is to place a reference microphone near the noise source to collect vibration or sound pressure signals, and then emit inverse sound waves through the in-vehicle audio system to cancel out engine noise or low-frequency road noise.

[0004] However, existing warning sound solutions present a significant trade-off between user experience and cost. To ensure effective warning, external sounds must reach a certain sound pressure level, inevitably leading to the transmission of warning sounds into the vehicle. This disrupts the acoustic environment of the passenger compartment, causing interference from a continuous buzzing sound for the driver and passengers. The clarity of conversations inside the vehicle decreases, and music playback quality is significantly reduced. Simply lowering the warning volume fails to meet safety regulations. Relying on passive noise reduction methods such as adding sound insulation increases hardware costs and vehicle weight. Furthermore, traditional active noise cancellation technologies have limitations in handling such external synthetic noise. Collecting external warning sounds through physical microphones introduces wind noise interference. The airborne propagation path introduces non-linear delays, and the purity of the reference signal is insufficient. This makes it difficult for the noise cancellation system to accurately target and effectively cancel out the warning sound frequency.

[0005] Therefore, the present invention provides a vehicle and pedestrian warning system and control method based on active noise reduction to overcome the shortcomings of the prior art. Summary of the Invention

[0006] The purpose of this invention is to provide a vehicle pedestrian warning system and control method based on active noise cancellation, which aims to solve the problems that existing low-speed warning sounds of electric vehicles can cause acoustic interference to occupants while ensuring the safety of pedestrians outside the vehicle, as well as the high cost of existing passive sound insulation and the insufficient accuracy of traditional active noise cancellation.

[0007] The present invention provides the following solution: In a first aspect, the present invention provides a vehicle and pedestrian warning control method based on active noise reduction, comprising the following steps:

[0008] Step S1: The vehicle status acquisition unit reads the vehicle driving data in real time and sends the vehicle driving data to the warning sound generation module. The warning sound generation module synthesizes a source audio signal based on the vehicle driving data and divides the source audio signal into a synchronous first signal transmission path and a second signal transmission path. The first signal transmission path drives the external audio output unit to radiate sound waves to the outside of the vehicle. The second signal transmission path transmits the source audio signal directly to the reverse sound wave generation module as a reference signal.

[0009] Step S2: The in-vehicle sound acquisition unit collects acoustic environment data in the passenger compartment of the vehicle in real time. The acoustic environment data includes warning noise components transmitted from outside the vehicle and background noise components. The in-vehicle sound acquisition unit converts the collected sound waves into residual noise signals and feeds back the residual noise signals to the reverse sound wave generation module in real time.

[0010] Step S3: The reverse sound wave generation module receives the reference signal transmitted through the second signal transmission path and the residual noise signal fed back by the in-vehicle sound acquisition unit, processes the reference signal and the residual noise signal using an adaptive filtering algorithm, calculates and generates a reverse cancellation audio signal, the amplitude of the reverse cancellation audio signal matches the amplitude of the warning noise component and is opposite in phase;

[0011] Step S4: The reverse sound wave generation module transmits the reverse cancellation audio signal to the in-vehicle audio output unit. The in-vehicle audio output unit plays the reverse sound wave according to the reverse cancellation audio signal. The reverse sound wave is superimposed and canceled by the incoming warning noise component in the vehicle passenger compartment.

[0012] By adopting the above technical solution, the reference signal of the active noise cancellation system is obtained by directly splitting the digital source signal. Compared with the traditional method of collecting noise sources through physical microphones, this suppresses the acoustic delay and nonlinear distortion introduced by the air propagation path and avoids the contamination of the reference signal by wind noise and road noise. The pure and delay-free reference signal has a high linear correlation with the actual warning noise in the vehicle, thereby improving the calculation accuracy and convergence speed of the reverse sound wave generation module. While effectively performing the external warning function, it reduces the acoustic interference of the warning sound to the occupants in the vehicle and improves the cabin quietness.

[0013] Preferably, in step S1, the vehicle driving data includes a real-time vehicle speed signal and a current gear signal. The warning sound generation module dynamically synthesizes the source audio signal based on the vehicle driving data, and the frequency components of the source audio signal shift to higher frequencies as the real-time vehicle speed increases.

[0014] By adopting the above technical solutions, the acoustic characteristics of the warning sound meet the regulatory requirements and can intuitively reflect the vehicle's driving status. At the same time, the active noise cancellation system can adjust the cancellation strategy in real time according to frequency changes.

[0015] Preferably, in step S1, the first signal transmission path processes the source audio signal through a digital-to-analog converter circuit and a power amplifier circuit to drive the external audio output unit; the second signal transmission path maintains the original digital signal format of the source audio signal and transmits the source audio signal as the reference signal without air propagation attenuation to the reverse sound wave generation module through the internal data bus.

[0016] By adopting the above technical solution, the reference signal is ensured to maintain pure digital characteristics, avoiding the noise interference introduced by the analog transmission link, and providing an ideal feedforward input for adaptive filtering.

[0017] Preferably, in step S2, the in-vehicle sound acquisition unit performs gain adjustment and anti-aliasing filtering on the acquired analog residual noise signal through a signal conditioning circuit, and converts it into a digital signal sequence through an analog-to-digital converter. The digital signal sequence is transmitted to the feedback input port of the reverse sound wave generation module through a signal feedback line.

[0018] By adopting the above technical solution, high-frequency interference signals are filtered out, sampling distortion caused by signal aliasing is prevented, and the authenticity of the error signal fed back to the control algorithm is guaranteed.

[0019] Preferably, in step S3, the reverse acoustic wave generation module has a pre-stored estimation model of the secondary channel transfer function. The reverse acoustic wave generation module performs a convolution operation on the reference signal through the estimation model of the secondary channel transfer function to generate a filtered reference signal. The filtered reference signal represents the predicted waveform state of the reference signal after propagation through the physical secondary channel to the error acquisition point.

[0020] By adopting the above technical solution, the changes in amplitude-frequency characteristics and phase lag caused by electroacoustic conversion and physical space propagation path are compensated, the phase mismatch problem in adaptive control is solved, and the stability of the system is guaranteed.

[0021] Preferably, in step S3, the adaptive filtering algorithm uses the minimum mean square error criterion to calculate the gradient descent direction of the filter weight vector based on the current filter weight vector, the filtered reference signal, and the residual noise signal, and iteratively updates the filter weight vector according to a preset step size factor, driving the power of the residual noise signal to converge in the direction of minimization; the iterative update process of the filter weight vector includes: calculating that the filter weight vector at the next time step is equal to the filter weight vector at the current time step plus a correction term, wherein the correction term is composed of the step size factor, the amplitude of the residual noise signal at the current time step, and the filtered reference signal vector at the current time step.

[0022] By adopting the above technical solution and using the gradient descent principle to dynamically find the optimal filter parameters, the system can adaptively track the noise frequency drift caused by changes in vehicle speed and the slight changes in the in-vehicle sound field environment, thus maintaining the best noise reduction effect.

[0023] Preferably, in step S4, the reverse acoustic wave generation module outputs the reverse cancellation audio signal in digital form to the digital-to-analog converter circuit, the digital-to-analog converter circuit converts the reverse cancellation audio signal into an analog voltage signal, and the analog voltage signal enters the power amplifier circuit for power gain amplification to drive the speaker diaphragm of the in-vehicle audio output unit to vibrate.

[0024] By adopting the above technical solution, the calculated digital cancellation signal is restored to physical sound wave with high fidelity, ensuring accurate physical superposition with the noise field.

[0025] Preferably, step S4 further includes a closed-loop feedback control process: the in-vehicle sound acquisition unit continuously monitors the residual sound field after physical superposition and feeds back the updated residual noise signal to the reverse sound wave generation module. The reverse sound wave generation module corrects the filter weight coefficients according to the updated residual noise signal and adjusts the waveform characteristics of the output reverse cancellation audio signal, so that the active noise cancellation system dynamically adapts to changes in vehicle driving conditions.

[0026] By adopting the above technical solution, a real-time closed-loop control loop is formed, which enhances the robustness of the system and enables it to meet the noise suppression requirements under non-steady operating conditions such as vehicle acceleration and deceleration and road surface changes.

[0027] Secondly, the present invention provides a vehicle and pedestrian warning system based on active noise reduction, comprising:

[0028] The vehicle status acquisition unit is configured to read the vehicle's driving data in real time.

[0029] The warning sound generation module is connected to the vehicle status acquisition unit and is configured to synthesize a source audio signal based on the driving data, and divide the source audio signal into a first output signal and a second output signal, wherein the second output signal is used as a reference signal.

[0030] An external audio output unit is connected to the first output terminal of the warning sound generation module and is configured to receive the first output signal and radiate sound waves to the outside of the vehicle.

[0031] The in-vehicle sound acquisition unit is located in the passenger compartment of the vehicle and is configured to collect acoustic environmental data in the passenger compartment and output residual noise signals.

[0032] The reverse sound wave generation module is connected to the second output terminal of the warning sound generation module and the in-vehicle sound acquisition unit, respectively. It is configured to receive the reference signal and the residual noise signal, and use an adaptive filter to calculate and generate a reverse cancellation audio signal.

[0033] An in-vehicle audio output unit is connected to the reverse sound wave generation module and is configured to receive the reverse cancellation audio signal and play the reverse sound wave in the vehicle's passenger compartment.

[0034] By adopting the above technical solution, the system integrates the dual functions of external vehicle warning and in-vehicle noise reduction. In terms of hardware architecture, the direct signal transmission eliminates the dependence of traditional noise reduction systems on reference microphones, reducing hardware costs and installation complexity. At the same time, through the collaborative work of various modules, it achieves efficient and accurate suppression of warning noise.

[0035] The above solution achieves the following beneficial technical effects:

[0036] This application utilizes digital signal transmission to directly transmit the source audio signal synthesized by the warning sound generation module to the inverse sound wave generation module, replacing the traditional method of acquiring noise sources through physical microphones in active noise cancellation systems. This technical feature suppresses acoustic delay and nonlinear distortion introduced by air propagation and avoids contamination of the reference signal by wind noise and road noise during vehicle operation. This provides the adaptive filtering algorithm with high-fidelity, zero-latency prior data that is highly linearly correlated with the noise source, improving the accuracy of inverse sound wave calculation and the system's convergence speed.

[0037] This application employs a dual-path splitting processing architecture for warning sound signals, collaboratively controlling the cancellation of external audio output and in-vehicle reverse sound waves. The first signal transmission path drives the external audio output unit to radiate high sound pressure level warning sounds to meet pedestrian safety alert requirements. Simultaneously, the second signal transmission path drives the reverse sound wave generation module to generate anti-phase sound waves inside the vehicle to physically cancel the incoming warning sound noise. This architecture effectively resolves the conflict between ensuring external driving safety and maintaining cabin quietness in electric vehicles' low-speed warning sounds, achieving a balance between external warning functionality and in-vehicle acoustic comfort.

[0038] This application utilizes an in-vehicle sound acquisition unit to construct a real-time closed-loop feedback control circuit. Combined with real-time driving data provided by a vehicle status acquisition unit, it drives an adaptive filter to dynamically update its weight coefficients. This technical solution enables the reverse sound wave generation module to track in real-time the drift of the warning audio frequency caused by changes in vehicle speed and the minute changes in the sound field transmission path inside the vehicle. This ensures that, under vehicle acceleration, deceleration, or different road conditions, the reverse cancellation audio signal always maintains a precise match in amplitude and phase with the intruding warning noise inside the vehicle, thus maintaining the robustness and stability of the noise reduction effect. Attached Figure Description

[0039] Figure 1 is a diagram of the vehicle and pedestrian warning system based on active noise reduction according to the present invention.

[0040] Figure 2 is a schematic flowchart of the vehicle and pedestrian warning control method based on active noise reduction of the present invention.

[0041] Figure 3 is a schematic diagram of the AVAS audio signal generation and splitting steps of the present invention.

[0042] Figure 4 is a schematic diagram of the real-time monitoring steps for in-vehicle noise environment according to the present invention.

[0043] Figure 5 is a schematic diagram of the reverse noise reduction wave calculation and generation steps of the present invention.

[0044] Figure 6 is a schematic diagram of the acoustic wave superposition cancellation and closed-loop control steps of the present invention. Detailed Implementation

[0045] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0046] Referring to Figure 1, this invention provides a vehicle pedestrian warning system based on active noise cancellation, which includes a vehicle status acquisition unit, a warning sound generation module, a reverse sound wave generation module, an external audio output unit, an internal audio output unit, and an internal sound acquisition unit. The various modules and units are connected via an onboard communication bus or dedicated signal lines to achieve data transmission and command interaction.

[0047] The vehicle status acquisition unit is configured to read the vehicle's driving data in real time. This driving data includes, but is not limited to, the vehicle's real-time speed, gear status, and start / stop status. This unit sends the acquired vehicle driving data to the warning sound generation module as the basic parameters for generating the warning sound.

[0048] The warning sound generation module is the system's signal source, internally storing preset warning sound algorithms or audio files. It receives driving data from the vehicle status acquisition unit and synthesizes or retrieves corresponding pedestrian warning sound audio signals based on this data. This pedestrian warning sound audio signal is configured as two output signals. The first output signal is transmitted to the external audio output unit via a signal line, while the second output signal is directly transmitted to the reverse sound wave generation module via an internal data bus. The second output signal transmitted to the reverse sound wave generation module is defined as a reference signal. This reference signal has the same frequency and time domain characteristics as the first output signal, and it is a pure signal source unaffected by air propagation attenuation.

[0049] The external audio output unit is located on the exterior of the vehicle, typically in the front bumper or grille area. It receives the first output signal from the warning sound generation module and converts this electrical signal into a sound wave signal, which is radiated outwards to warn pedestrians. While radiating outwards, some of the sound waves penetrate the vehicle's structure or enter the interior through gaps, creating an in-vehicle warning noise.

[0050] The in-vehicle sound acquisition unit is located within the passenger compartment of the vehicle. In one embodiment, the in-vehicle sound acquisition unit is positioned at the headrest of the driver's seat or on the vehicle roof near the driver's ear. The in-vehicle sound acquisition unit is configured to acquire acoustic environmental data within the passenger compartment in real time. This acoustic environmental data includes in-vehicle warning noise from outside the vehicle and other background noise within the vehicle. The in-vehicle sound acquisition unit converts the acquired sound waves into electrical signals, which are defined as residual noise signals. The signal output terminal of the in-vehicle sound acquisition unit is connected to the signal input terminal of the reverse sound wave generation module, transmitting the residual noise signal to the reverse sound wave generation module in real time.

[0051] The reverse acoustic wave generation module is the core control unit of the system, with its inputs connected to the warning sound generation module and the in-vehicle sound acquisition unit. The reverse acoustic wave generation module receives a reference signal from the warning sound generation module and a residual noise signal from the in-vehicle sound acquisition unit. An adaptive filter is integrated within the reverse acoustic wave generation module. This adaptive filter is configured to use the reference signal as a feedforward signal and the residual noise signal as a feedback error signal. The reverse acoustic wave generation module processes the reference signal and the residual noise signal through its internal logic to calculate and generate a reverse cancellation audio signal. The amplitude of this reverse cancellation audio signal is equal to or approximately equal to the amplitude of the in-vehicle warning sound noise, and the phase of the reverse cancellation audio signal is opposite to the phase of the in-vehicle warning sound noise.

[0052] The in-vehicle audio output unit is located in the passenger compartment of the vehicle. It can be either the vehicle's existing in-vehicle entertainment system speakers or a specially configured active noise-canceling speaker. The signal input terminal of the in-vehicle audio output unit is connected to the signal output terminal of the reverse sound wave generation module. The in-vehicle audio output unit receives the reverse cancellation audio signal and converts it into a reverse sound wave for playback within the passenger compartment. This reverse sound wave interferes with and superimposes with the in-vehicle warning noise entering the vehicle in physical space, thereby reducing or canceling the sound pressure level of the warning noise at the occupant's ear position.

[0053] In this embodiment, by directly using the raw audio data generated by the warning sound generation module as the reference signal for the active noise cancellation system, the delay and nonlinear distortion introduced by the additional reference microphone used in traditional active noise cancellation systems are avoided. This ensures a high correlation between the reference signal and the noise source signal, providing a high-quality data foundation for the accurate calculation of the reverse sound wave generation module. The system forms a closed-loop control circuit. The reverse sound wave generation module continuously adjusts the filter parameters based on the residual noise signal fed back from the in-vehicle sound acquisition unit to adapt to noise changes under different vehicle speeds and vehicle body sound insulation characteristics, thereby maintaining a quiet sound environment inside the vehicle while ensuring the external warning effect.

[0054] Referring to Figure 2, the present invention provides a vehicle pedestrian warning control method based on active noise cancellation. This method reduces the acoustic interference of the warning sound to the occupants of the vehicle by coordinating the playback of warning sounds outside the vehicle and the active noise cancellation processing inside the vehicle.

[0055] The method first performs a warning sound generation and distribution step. The system monitors the vehicle's driving status parameters in real time. When the vehicle is traveling at low speed or under specific triggering conditions, it generates a corresponding pedestrian warning sound audio signal according to a preset algorithm. This pedestrian warning sound audio signal is divided into a synchronized first signal path and a second signal path. The first signal path is used to drive the external sound-emitting device to radiate sound waves to the outside of the vehicle to alert nearby pedestrians. The second signal path directly transmits the generated audio data as a reference signal to the internal active noise reduction control algorithm.

[0056] The in-vehicle sound field acquisition step is then performed. While the external warning sound plays, the system acquires real-time acoustic environment data from sound acquisition devices positioned at specific locations within the vehicle. This acquired acoustic data includes the noise component of the external warning sound and the background noise component, constituting a residual noise signal. This residual noise signal is fed back to the control algorithm in real time as an error feedback quantity to measure the noise reduction effect.

[0057] Next, the reverse acoustic wave calculation step is performed. The system receives the reference signal transmitted via the second signal path and the residual noise signal fed back from the sound acquisition device. Using an adaptive filtering algorithm, the system uses the reference signal as the feedforward input and the residual noise signal as the error input to calculate the reverse cancellation audio signal through iterative calculation. This calculation process aims to adjust the amplitude and phase of the reverse cancellation audio signal so that it forms destructive interference with the incoming warning noise in a predetermined in-vehicle area.

[0058] Finally, the sound wave superposition and cancellation step is performed. The system converts the calculated inverse cancellation audio signal into an analog electrical signal and drives the in-vehicle audio playback device to emit an inverse sound wave. This inverse sound wave is superimposed on the incoming warning noise in the physical space, thereby reducing the sound pressure level at the occupants' ears and achieving active suppression of the warning noise inside the vehicle.

[0059] Referring to Figure 3, step S1: generation and splitting of AVAS audio signal. In the vehicle and pedestrian warning control method based on active noise reduction provided by the present invention, step S1 mainly includes the synthesis of warning sound source signal and dual-path splitting processing of signal.

[0060] When the vehicle is in the start-up, low-speed driving, or reversing state, the warning sound generation module receives vehicle status information from the vehicle control bus in real time. This vehicle status information includes at least the vehicle's real-time speed signal and current gear signal. The warning sound generation module internally runs an acoustic synthesis algorithm that dynamically synthesizes a set of digital audio sequences with specific frequency characteristics and sound pressure level variations based on the received vehicle status information. This digital audio sequence is defined as the source audio signal, denoted as […]. ,in Represents discrete time sampling points. Source audio signal. The frequency components shift linearly or non-linearly to higher frequencies as vehicle speed increases, in order to meet regulatory requirements for low-speed warning sounds for electric vehicles.

[0061] The alarm sound generation module generates the source audio signal. Then, a synchronization splitting operation is immediately performed on the signal, sending it to the first signal transmission path and the second signal transmission path respectively. The first signal transmission path and the second signal transmission path are strictly synchronized in timing to ensure the causal relationship in subsequent processing steps.

[0062] In the first signal transmission path, the source audio signal The signal is fed into a digital-to-analog converter (DAC) circuit and a power amplifier circuit. After DAC conversion, the analog signal is amplified to a predetermined voltage amplitude in the power amplifier circuit, and then drives an external audio output unit installed outside the vehicle. The external audio output unit converts the electrical signal into physical sound waves and radiates them outwards, creating a warning sound for pedestrians. As these physical sound waves propagate outwards, some of the sound energy penetrates the vehicle's structure, windows, and gaps in the bodywork, entering the passenger compartment and creating an in-vehicle warning noise field that needs to be eliminated.

[0063] In the second signal transmission path, the source audio signal Maintaining its original digital signal format, it is directly transmitted to the reverse acoustic wave generation module via the internal data bus or board-level communication interface. The signal transmitted in this path is directly defined as the reference signal for the active noise cancellation control system, denoted as... In this embodiment, the reference signal Numerically compared to the source audio signal Totally consistent.

[0064] This step establishes a feedforward signal acquisition mechanism based on non-acoustic acquisition by directly extracting the reference signal at the source of signal generation. Unlike traditional active noise cancellation systems that use a reference microphone installed near the noise source to acquire noise signals, this method obtains a reference signal... It does not propagate through the air medium, does not include acoustic delays introduced by physical paths, and is free from interference from environmental background noise such as wind noise and road noise. Reference signal It contains all the frequency components of the in-vehicle warning noise field and maintains a high linear correlation with the noise field entering the vehicle, providing accurate and pure prior data for the subsequent calculation of the reverse sound wave of the adaptive filter.

[0065] Referring to Figure 4, step S2: Real-time monitoring of the in-vehicle noise environment. While the external audio output unit radiates warning sound waves to the outside, the system simultaneously executes the in-vehicle sound field monitoring program. An in-vehicle sound acquisition unit located at a specific position in the passenger compartment continuously samples the acoustic environment near the driver's or passenger's ears. The in-vehicle sound acquisition unit uses a sound-to-electric conversion device to sense sound pressure fluctuations in the air and converts the received sound pressure changes into an analog voltage signal. This analog voltage signal objectively reflects the current state of the synthetic sound field in the target area inside the vehicle.

[0066] The synthesized sound field is formed by the linear superposition of various sound sources with different properties in physical space. This includes the warning noise component emitted by the external audio output unit and transmitted into the vehicle through physical paths such as the vehicle body structure, windows, and gaps; this component is the primary target of this system's suppression. In addition, the synthesized sound field also includes background noise components such as tire noise, wind noise, mechanical vibration noise, and the voices of occupants during vehicle operation. When the control system is in closed-loop operation, the synthesized sound field also includes residual sound waves resulting from the superposition of the reverse sound waves emitted by the in-vehicle audio output unit and the aforementioned noise. The system uniformly defines the electrical signal output by the in-vehicle sound acquisition unit as the residual noise signal, denoted as […]. ,in This is a discrete-time index.

[0067] The acquired residual noise signal in analog form first undergoes gain adjustment and anti-aliasing filtering in a signal conditioning circuit to filter out high-frequency interference signals that exceed the system's effective operating frequency band. Subsequently, the signal is sent to an analog-to-digital converter (ADC) to be compared with a reference signal. A consistent sampling frequency is maintained when converting the signal into a digital signal sequence. This digitized residual noise signal... The signal is transmitted in real time to the feedback input port of the reverse acoustic wave generation module via a dedicated signal feedback line, serving as the feedback input data for algorithm calculation.

[0068] In this control method, residual noise signal It serves as the error feedback variable in the adaptive filtering control system. The instantaneous amplitude and statistical characteristics of this signal directly characterize the deviation between the actual cancellation effect of the active noise reduction system and the ideal quiet target at the current moment. The reverse acoustic wave generation module uses the received residual noise signal... The system determines whether the generated reverse sound wave accurately matches the in-vehicle warning noise in terms of amplitude and phase, and calculates the gradient descent direction accordingly to adjust the filter's weight coefficients, driving the system towards the residual noise signal. The direction of power minimization converges.

[0069] Referring to Figure 5, step S3: calculation and generation of reverse noise reduction wave. In this step, the reverse sound wave generation module uses digital signal processing technology to synthesize a reverse signal in real time to cancel the in-vehicle warning noise based on the input reference signal and the feedback residual noise signal through an adaptive filtering algorithm.

[0070] The reverse acoustic wave generation module first receives the reference signal transmitted in step S1. and the residual noise signal fed back from step S2 To compensate for the changes in amplitude-frequency characteristics and phase delay caused by the physical acoustic transmission path from the in-vehicle audio output unit to the in-vehicle sound acquisition unit, as well as the digital-to-analog / analog-to-digital conversion circuit, the algorithm pre-stores or identifies the estimated model of the secondary channel transfer function online. The reverse acoustic wave generation module uses the reference signal... A convolution operation is performed using the estimated model of the secondary channel transfer function to generate a filtered reference signal. This filtered reference signal characterizes the predicted waveform state of the reference signal after propagation through the physical secondary channel to the error acquisition point.

[0071] The reverse acoustic wave generation module internally incorporates an adaptive filter with adjustable weight coefficients. This adaptive filter is applied to the original reference signal. Finite impulse response filtering is performed to calculate the digital inverse canceled audio signal, denoted as . This reverse cancels out the audio signal. It is the output of the adaptive filter at the current moment, which is designed to drive the in-vehicle speakers to produce a secondary sound field with the same amplitude but opposite phase as the primary noise field.

[0072] While outputting the inverse canceled audio signal, the inverse acoustic wave generation module performs a filter weight coefficient update process. This process aims to find and converge to the optimal filter transfer function, maximizing the reduction of residual noise signal. The algorithm minimizes the mean square error. It utilizes the minimum mean square error criterion, based on the current filter weight vector, the filtered reference signal, and the measured residual noise signal. The gradient descent direction of the weight vector is calculated, and the weight vector is iteratively updated according to the preset step size factor.

[0073] The iterative update of the filter weight coefficients follows the mathematical relationship:

[0074] ;

[0075] in, Defined as the updated filter weight vector for the next time step; Defined as the filter weight vector at the current moment; Defined as the step size factor, this parameter determines the convergence speed and steady-state error performance of the algorithm, and is a preset positive constant. Defined as the amplitude of the residual noise signal fed back by the in-vehicle sound acquisition unit at the current moment; Defined as the reference signal at the current time. The filtered reference signal vector is obtained after processing by the secondary channel transfer function estimation model.

[0076] Through the above calculation process, the adaptive filter can dynamically track the warning audio frequency drift caused by changes in vehicle speed and changes in the in-vehicle acoustic environment, and adjust the inverse cancellation audio signal in real time. The waveform characteristics ensure that the reverse sound wave always maintains an antiphase cancellation relationship with the warning noise that intrudes into the vehicle.

[0077] Referring to Figure 6, step S4: sound wave superposition cancellation and closed-loop control. In the vehicle and pedestrian warning control method based on active noise reduction provided by the present invention, step S4 mainly involves the continuous operation of electroacoustic signal conversion, physical sound field superposition, and closed-loop feedback control.

[0078] The reverse acoustic wave generation module outputs a digital inverse cancellation audio signal. The signal is first transmitted to a digital-to-analog converter (DAC). The DAC converts the discrete digital sequence into a continuously varying analog voltage signal. This analog voltage signal then enters a power amplifier circuit for power gain amplification, driving the speaker drivers in the in-vehicle audio output unit. The in-vehicle audio output unit, based on the input analog voltage signal, drives the diaphragm to vibrate, converting electrical energy into mechanical energy and further propelling the air medium, thereby radiating inverse sound waves in the physical form within the vehicle's passenger compartment.

[0079] The reverse sound wave propagates through the air in the passenger compartment and reaches the ears of the driver and passengers. At this spatiotemporal point, the reverse sound wave emitted by the in-vehicle audio output unit physically superimposes with the in-vehicle warning noise field transmitted from outside the vehicle. Because the reverse sound wave is generated by an algorithm that controls its sound pressure amplitude at the target location to be approximately equal to that of the warning noise, and its phase differs from the warning noise by 180 degrees, destructive interference occurs between the two in the superposition region. This physical interference reduces the total energy of the synthesized sound wave in this region, thus macroscopically manifesting as a decrease in the sound pressure level of the warning noise, thereby improving the quietness of the vehicle interior.

[0080] During this process, the entire control system operates in a real-time closed-loop state. The in-vehicle sound acquisition unit continuously monitors the residual sound field after the physical superposition and feeds back the acquired residual noise signal to the reverse sound wave generation module in real time. If the warning audio frequency changes due to a sudden change in vehicle speed, or if the sound field transmission path is slightly altered due to occupant movement, causing a deviation in the physical superposition effect, the in-vehicle sound acquisition unit will immediately detect the increased residual noise signal. The reverse sound wave generation module quickly corrects the filter weight coefficients based on this feedback signal, adjusting the output reverse sound wave characteristics to ensure that the noise reduction system can dynamically adapt to continuous changes in vehicle driving conditions and always maintain the optimal noise suppression effect.

[0081] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A vehicle and pedestrian warning control method based on active noise reduction, characterized in that, The method includes the following steps: S1, a vehicle status acquisition unit reads vehicle driving data in real time and sends the vehicle driving data to a warning sound generation module. The warning sound generation module synthesizes a source audio signal based on the vehicle driving data and divides the source audio signal into a synchronous first signal transmission path and a second signal transmission path. The first signal transmission path drives the external audio output unit to radiate sound waves to the outside of the vehicle, and the second signal transmission path directly transmits the source audio signal as a reference signal to the reverse sound wave generation module; S2, an in-vehicle sound acquisition unit collects acoustic environment data in the vehicle's passenger compartment in real time. The acoustic environment data includes a warning sound noise component transmitted from outside the vehicle and a background noise component. The in-vehicle sound acquisition unit converts the collected sound waves into residual sound. S3. The residual noise signal is received from the reference signal transmitted through the second signal transmission path and the residual noise signal fed back by the in-vehicle sound acquisition unit. The reference signal and the residual noise signal are processed using an adaptive filtering algorithm to calculate and generate a reverse cancellation audio signal. The amplitude of the reverse cancellation audio signal matches the amplitude of the warning noise component and is opposite in phase. S4. The reverse sound wave generation module transmits the reverse cancellation audio signal to the in-vehicle audio output unit. The in-vehicle audio output unit plays a reverse sound wave according to the reverse cancellation audio signal. The reverse sound wave is superimposed and cancels the incoming warning noise component in the vehicle passenger compartment.

2. The vehicle and pedestrian warning control method based on active noise reduction according to claim 1, characterized in that, In step S1, the vehicle driving data includes the vehicle's real-time driving speed signal and the current gear signal. The warning sound generation module dynamically synthesizes the source audio signal based on the vehicle driving data. The frequency components of the source audio signal shift to higher frequencies as the vehicle's real-time driving speed increases.

3. The vehicle and pedestrian warning control method based on active noise reduction according to claim 1, characterized in that, In step S1, the first signal transmission path processes the source audio signal through a digital-to-analog converter circuit and a power amplifier circuit to drive the external audio output unit; the second signal transmission path maintains the original digital signal format of the source audio signal and transmits the source audio signal as the reference signal without air propagation attenuation to the reverse sound wave generation module through the internal data bus.

4. The vehicle and pedestrian warning control method based on active noise reduction according to claim 1, characterized in that, In step S2, the in-vehicle sound acquisition unit performs gain adjustment and anti-aliasing filtering on the acquired analog residual noise signal through a signal conditioning circuit, and converts it into a digital signal sequence through an analog-to-digital converter. The digital signal sequence is transmitted to the feedback input port of the reverse sound wave generation module through a signal feedback line.

5. The vehicle and pedestrian warning control method based on active noise reduction according to claim 1, characterized in that, In step S3, the reverse acoustic wave generation module has a pre-stored estimation model of the secondary channel transfer function. The reverse acoustic wave generation module performs a convolution operation on the reference signal through the estimation model of the secondary channel transfer function to generate a filtered reference signal. The filtered reference signal represents the predicted waveform state of the reference signal after propagation through the physical secondary channel to the error acquisition point.

6. The vehicle and pedestrian warning control method based on active noise reduction according to claim 5, characterized in that, In step S3, the adaptive filtering algorithm uses the minimum mean square error criterion to calculate the gradient descent direction of the filter weight vector based on the current filter weight vector, the filtered reference signal, and the residual noise signal. It then iteratively updates the filter weight vector according to a preset step size factor, driving the power of the residual noise signal to converge in the direction of minimization.

7. The vehicle and pedestrian warning control method based on active noise reduction according to claim 6, characterized in that, In step S3, the iterative update process of the filter weight vector includes: calculating that the filter weight vector at the next time step is equal to the filter weight vector at the current time step plus a correction term, wherein the correction term is composed of the step size factor, the residual noise signal amplitude at the current time step, and the filtered reference signal vector at the current time step.

8. The vehicle and pedestrian warning control method based on active noise reduction according to claim 1, characterized in that, In step S4, the reverse acoustic wave generation module outputs the reverse cancellation audio signal in digital form to the digital-to-analog converter circuit. The digital-to-analog converter circuit converts the reverse cancellation audio signal into an analog voltage signal. The analog voltage signal enters the power amplifier circuit for power gain amplification and then drives the speaker diaphragm of the in-vehicle audio output unit to vibrate.

9. The vehicle and pedestrian warning control method based on active noise reduction according to claim 1, characterized in that, The S4 step also includes a closed-loop feedback control process: the in-vehicle sound acquisition unit continuously monitors the residual sound field after physical superposition and feeds back the updated residual noise signal to the reverse sound wave generation module. The reverse sound wave generation module corrects the filter weight coefficients according to the updated residual noise signal and adjusts the waveform characteristics of the output reverse cancellation audio signal, so that the active noise cancellation system dynamically adapts to changes in vehicle driving conditions.

10. A vehicle and pedestrian warning system based on active noise reduction, characterized in that, A control method for implementing any one of claims 1 to 9, comprising: a vehicle status acquisition unit configured to read vehicle driving data in real time; a warning sound generation module connected to the vehicle status acquisition unit, configured to synthesize a source audio signal based on the driving data, and divide the source audio signal into a first output signal and a second output signal, wherein the second output signal serves as a reference signal; an external audio output unit connected to the first output terminal of the warning sound generation module, configured to receive the first output signal and radiate sound waves to the outside of the vehicle; an internal sound acquisition unit disposed in the passenger compartment of the vehicle, configured to acquire acoustic environment data in the passenger compartment and output residual noise signals; a reverse sound wave generation module connected to the second output terminal of the warning sound generation module and the internal sound acquisition unit, configured to receive the reference signal and the residual noise signal, calculate and generate a reverse cancellation audio signal using an adaptive filter; and an internal audio output unit connected to the reverse sound wave generation module, configured to receive the reverse cancellation audio signal and play the reverse sound wave in the passenger compartment of the vehicle.

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