CN111724761B - Vehicle-mounted active noise control device and method - Google Patents
Vehicle-mounted active noise control device and method Download PDFInfo
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Abstract
The invention discloses a vehicle-mounted active noise control device and method. The device includes: the rotating speed measuring module is used for acquiring a rotating speed signal of a vehicle engine; the shaping module is used for shaping the rotating speed signal; the clock signal generating module is used for generating a clock signal according to the shaped rotating speed signal; the processing unit is used for generating a reference signal according to the clock signal and filtering the reference signal to generate a control signal; the power amplification module is used for driving a loudspeaker to sound according to the control signal; the microphone is used for acquiring an acoustic response signal of the loudspeaker; and the processing unit is further used for calculating the power of the residual noise in the current clock cycle according to the acoustic response signal, and comparing the power of the residual noise with the power of the residual noise in the previous clock cycle to correspondingly adjust the coefficient of the filter. The invention has less calculation amount and obviously reduces the consumption of calculation resources.
Description
Technical Field
The invention belongs to the technical field of vehicle-mounted noise reduction, and relates to a vehicle-mounted active noise control device and method.
Background
With the increase of the degree of vehicle intelligence, the requirements of drivers and passengers on the acoustic environment in the vehicle are more strict. The noise in the automobile can reduce the comfort of drivers and passengers, and cause the dysphoria and fatigue of the passengers in the automobile; also can influence the definition of exchanging the conversation, influence the driver to the perception of car outer signal sound even, increase the traffic hidden danger. Automotive NVH (Noise, vision, harshness) is an important concern for automotive plants. The noise is reduced by modifying the structural design and adding damping materials or using devices such as damping springs and the like, the devices are collectively called passive noise control, and the control mode has a good noise reduction effect on middle and high frequency noise. However, such control methods have a poor effect on low frequencies, particularly noise of an engine in a vehicle cabin, road noise caused by collision friction between a road surface and tires, and even airflow wind noise, which are often concentrated on low frequencies. The main sources of noise in the vehicle that are of major concern to the driver and passengers are engine noise, intake and exhaust noise, road tire noise and noise caused by wind excitation. In addition, passive noise control requires a long training time and is difficult to control cost. On the contrary, the scheme of active noise reduction utilizes a vehicle-mounted audio system to effectively reduce the noise in a carriage, but hardly adds extra counterweight to the automobile, is favorable for reducing the exhaust emission, and is a green energy-saving solution.
At present, patent documents disclose a vehicle-mounted active noise reduction method, which includes the following steps:
CN107600011A discloses an active control noise reduction system and method for automobile engine noise, which receives a rotating speed signal of an engine, and filters a square wave signal to obtain a fundamental wave as a reference signal; the reference signal needs to be convoluted with a transfer function, and a general FxLMS algorithm is applied; the way in which the reference signal is constructed is relatively easy to implement.
CN101473370B discloses active noise reduction with adaptive filter leakage regulation, the active noise reduction system receiving a high delay signal of the engine speed, providing a signal at a reference frequency related to the engine speed, generating an audio signal at a frequency corresponding to a predetermined multiple of the reference frequency; or receiving an engine speed signal from a bus associated with the audio entertainment system; a sine wave signal is generated from the frequency and the general FxLMS algorithm is applied.
CN101473371B discloses determination of the speed of an active noise reduction engine, accepting a low latency signal representing the engine speed from a vehicle data bus, transmitting a high latency signal representing the engine speed from an entertainment bus; a sine wave signal is generated from the frequency and the general FxLMS algorithm is applied.
CN105164748B discloses adaptive feed forward noise reduction for motor vehicles, sine wave generator inputs signals related to engine harmonics (including RPM, torque, accelerator pedal position, manifold absolute pressure MAP), from which the frequency of harmonics to be eliminated is determined; a sine wave signal is generated from the frequency and the general FxLMS algorithm is applied.
CN106089361A discloses an active noise reduction system and method for an engine in a vehicle, which introduces the engine speed as a reference signal; how the reference signal is constructed from the engine speed is not explained in detail.
CN106128449A discloses an active noise reduction method for an automobile, arranging a microphone (i.e. a microphone) in an engine compartment, and collecting a noise signal of the engine compartment as a reference signal; the noise reduction effect is influenced by mixing the sound signals in the cabin with other irrelevant noises.
CN106382143B discloses an active noise reduction device and method based on engine speed, which pre-calibrate the corresponding relation between the engine speed and the engine noise, collect noise signals near the engine, and store reference noise signals; when the system works normally, reading an engine rotating speed signal through a bus; the calibration process is relatively complex and does not take the difference of noise of the engine under different load conditions into consideration; storing the noise signal also requires a relatively large memory space.
CN107642426A discloses an active control method and system for noise of an automobile engine, which obtains a rotation speed signal of the engine, performs frequency division and integration on the rotation speed signal to construct the frequency of an engine order noise reference signal, and generates a reference signal by using a cosine function; the method of constructing the reference signal is accurately described, but the calculation amount of the integration operation is large.
CN110246481A discloses an automobile active noise reduction method for predicting the rotating speed of an engine, which estimates the rotating speed of the engine by combining a BP neural network according to a brake signal, an accelerator opening signal and an accelerator pedal signal; calling the stored fitting noise audio frequency according to the rotating speed of the engine to play so as to realize noise reduction; the system has too high computational complexity and is difficult to implement on a vehicle-mounted embedded platform.
The active noise reduction method disclosed in the above patent document has the following disadvantages:
1. for constructing the reference signal or its frequency, part of the above-mentioned patent documents describe a method for constructing the reference signal by the engine speed, which is most simply a filtering process to obtain the fundamental frequency signal. However, in the engineering, a fundamental frequency signal with higher signal-to-noise ratio is obtained, and the design and implementation of the filter are more complicated; the existing schemes are complicated in the way of constructing the reference signal.
2. For generating the reference signal, the active noise control systems are all processed in the discrete digital domain. The existing solutions either generate sinusoidal signals or sample analog signals through an analog-to-digital converter, all based on a given sampling rate. Noise signals with different frequencies have different frequency resolutions under the same sampling rate; for ultra-low frequency, too many sampling points are needed, and for slightly higher frequency, few sampling points are needed; but also requires a higher sampling rate to meet sufficient frequency resolution, which further increases the resource consumption of the processor.
3. For the selection of the noise reduction algorithm, the existing scheme adopts a feedforward adaptive algorithm such as FxLMS, either explicitly stated or cited in the existing literature. The key point is that the transfer function (or called response) of the secondary channel needs to be estimated, and a filter with the transfer function characteristic is used for filtering the reference signal; this requires a large amount of computation, especially in a multi-channel control system involving multiple positions in space, which increases exponentially.
Disclosure of Invention
In view of at least one of the above technical problems, an object of the present invention is to provide a vehicle active noise control apparatus and method, which have less calculation amount and significantly reduce the calculation resource consumption.
In order to achieve the purpose, the invention adopts a technical scheme that:
an on-vehicle active noise control device comprising:
the rotating speed measuring module is used for acquiring a rotating speed signal of a vehicle engine;
the shaping module is used for shaping the rotating speed signal;
the clock signal generating module is used for generating a clock signal according to the shaped rotating speed signal;
the processing unit is used for generating a reference signal according to the clock signal and filtering the reference signal to generate a control signal;
the power amplification module is used for driving a loudspeaker to sound according to the control signal; and
a microphone for acquiring an acoustic response signal of the speaker;
the processing unit is further configured to calculate power of remaining noise in a current clock cycle according to the acoustic response signal, and compare the power of the remaining noise in a previous clock cycle to adjust a coefficient of the filter accordingly.
Preferably, the processing unit includes:
the signal generating module is used for updating an addressing address according to the triggering of the clock signal so as to read a signal amplitude value from a pre-stored sine signal lookup table and generate a sine signal and a cosine signal as the reference signal;
an adaptive filtering module, configured to perform filtering processing on the reference signal;
and the noise power monitoring module is used for calculating the power of the residual noise of the current clock cycle, comparing the power with the power of the residual noise of the previous clock cycle and correspondingly adjusting the coefficient of the adaptive filtering module.
Further, the processing unit further includes:
a multiplication module for coefficient update iterations of the adaptive filtering module.
Furthermore, the input end of the multiplication module is electrically connected with the noise power monitoring module, the input end of the multiplication module is also electrically connected with the microphone through an analog-to-digital conversion module, and the output end of the multiplication module is electrically connected with the adaptive filtering module.
Further, the adaptive filtering module includes an adaptive filter that can vary with a trend of a power variation of the residual noise.
Further, the clock signal generating module is a phase-locked loop frequency divider.
The invention also adopts the following technical scheme:
a vehicle-mounted active noise control method comprises the following steps:
s1, acquiring a rotating speed signal of a vehicle engine;
s2, shaping the rotating speed signal;
s3, generating a clock signal according to the shaped rotating speed signal;
s4, generating a reference signal according to the clock signal and filtering the reference signal to generate a control signal; collecting the acoustic response signal of a loudspeaker, calculating the power of the residual noise in the current clock period according to the collected acoustic response signal, and comparing the power with the power of the residual noise in the previous clock period to correspondingly adjust the coefficient of the filter.
Further, the step S4 specifically includes:
s41, generating a reference signal, wherein the reference signal comprises a sine signal and a cosine signal, the counter cnt starts counting from the time of the 1 st clock period, and the sine signal x 1 (k) = sig (k), cosine signal
For the second clock cycle, counter cnt +1, k +1; when counter
Zero clearing counter, k is also zero clearing, sine signal
Cosine signal x 2 (k) = sig (k); with the counter again accumulating and
zero clearing counter, k is also zero clearing, sine signal x 1 (k) = sig (k), cosine signal
With the counter again accumulating and
zero clearing counter, k is also zero clearing, sine signal
Cosine signal x 2 (k) = sig (k); at this time, a complete cycle is finished and is recorded as T; the above steps are repeated in a circulating way, and a sine wave signal and a cosine signal with fixed frequency resolution are generated along with the clock; wherein k represents a table index in the sine signal table, sig represents a numerical value corresponding to the table index in the sine signal table, and Δ f represents a frequency resolution;
s42, generating a control signal y (k) = w 1 *x 1 (k)+w 2 *x 2 (k) Wherein w is 1 、w 2 Respectively representing filter coefficients;
s43, picking up an acoustic response signal of a loudspeaker and recording the acoustic response signal as a residual noise signal e (k);
s44, updating the coefficient of the filter to be w 1 ＝w 1 +sign*μ*e(k)*x 1 (k)；w 2 ＝w 2 +sign*μ*e(k)*x 2 (k) Wherein sign is a constant representing positive and negative numbers, such as sign = +1 or sign = -1, μ is a constant for adjusting the convergence step of the algorithm, and affects the convergence effect and stability of the algorithm;
s45, monitoring the noise variation trend and accumulating the residual noise power E 1 ＝E 1 +[e(k)] 2 Until a complete period T is over; in the next cycle, the residual noise power E is accumulated 2 ＝E 2 +[e(k)] 2 (ii) a Comparison E 1 And E 2 If E is 2 ＞E 1 Changing the number of symbols sign = -sign; otherwise, the number of symbols remains unchanged; two periods T are over and zero clearing E 1 And E 2 The monitoring is re-accumulated in the next period T.
Further, the step S4 further comprises a step S45 of introducing a leakage factor λ into the filter coefficient update, w 1 ＝(1-λ)*w 1 +sign*μ*λ*e(k)*x 1 (k)；w 2 ＝(1-λ)*w 2 +sign*μ*λ*e(k)*x 2 (k)。
Further, in step S3, the clock signal is generated by a phase-locked loop divider.
Compared with the prior art, the invention has at least one of the following advantages by adopting the scheme:
according to the vehicle-mounted active noise control device and method, the active noise control system with the time-varying sampling rate is provided, and the clock of the system can change along with the rotating speed of the engine, so that the tracking performance of the system is guaranteed;
the sampling rate changes along with the change of the rotating speed of the engine, and the sampling precision of each noise frequency needing to be controlled is ensured to be consistent, so that less noise reduction is realized;
sine signals generated by sin or cos functions are not needed to be used as reference signals, and the consumption of computing resources is reduced;
the transfer function of a secondary channel does not need to be measured, so that the complexity of training is reduced;
and the reference signal does not need to be filtered, so that the calculation amount is reduced.
Drawings
In order to more clearly illustrate the technical solution of the present invention, the drawings required to be used in the description of the embodiments will be briefly introduced below, and it is apparent that the drawings in the description below are only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained based on these drawings without creative efforts.
Fig. 1 is a block diagram of a vehicle-mounted active noise control apparatus according to an embodiment of the present invention;
FIG. 2 is a flow chart of the adaptive processing operation within one clock cycle according to an embodiment of the present invention;
fig. 3 is a flowchart of the adaptive processing operation within one cycle period T according to the embodiment of the present invention.
Detailed Description
Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings so that the advantages and features of the invention may be more readily understood by those skilled in the art. It should be noted that the description of the embodiments is provided to help understanding of the present invention, but the present invention is not limited thereto. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.
The invention aims to pay attention to engine noise and intake and exhaust noise, the noise frequency is distributed in a low frequency range, an active noise reduction scheme is suitable, the noise frequency component is relatively simple, mainly linear spectrum noise, and the noise frequency is strictly related to the engine speed. Based on this, the present embodiment provides an in-vehicle active noise control device. The vehicle-mounted active noise control device of the embodiment comprises: the device comprises a rotating speed measuring module, a shaping module, a clock signal generating module, a processing unit, a power amplification module, a loudspeaker and a microphone. The apparatus is described in detail below with reference to fig. 1.
And the rotating speed measuring module is used for acquiring a rotating speed signal of the vehicle engine. In this embodiment, the rotation speed measuring module is a sensor of the vehicle, such as a crank signal sensor and/or an ignition pulse signal sensor.
The shaping module is specifically a square wave shaping module, and the input end of the shaping module is electrically connected with the output end of the rotating speed measuring module. The rotating speed signal of the engine is a square wave signal, but the waveform may have some noise waves due to the background noise of the sensor, the transmission loss of the transmission line and the like, and the waveform is not regular enough. In this embodiment, the signal is shaped by the shaping module to filter out clutter, interference waves and the like. A general voltage comparator is specifically selected, and the general voltage comparator is further a Schmitt trigger.
And the clock signal generating module is used for generating a clock signal according to the shaped rotating speed signal, and the input end of the clock signal generating module is electrically connected with the output end of the shaping module. In this embodiment, the clock signal generating module is specifically a pll divider. The square wave signal is passed through a phase-locked loop frequency divider to generate a clock signal. The clock signal is determined by the periodic characteristics of the square wave signal, and the variation of the engine speed can cause the periodic variation of the square wave signal, and the frequency of the clock signal is changed. The period of the clock signal does not completely correspond to the period of the square wave signal, and the present embodiment adjusts the period of the square wave signal by using the parameter of the frequency division number of the phase-locked loop frequency divider.
The processing unit is used for generating a reference signal according to the clock signal and filtering the reference signal to generate a control signal; and meanwhile, the device is also used for calculating the power of the residual noise in the current clock period according to the acoustic response signal, comparing the power with the power of the residual noise in the previous clock period and correspondingly adjusting the coefficient of the filter.
And the power amplifier module is used for driving a loudspeaker to sound according to the control signal output by the processing unit. The input end of the power amplifier module is electrically connected to the output end of the processing unit through the digital-to-analog conversion module. The control signal output by the processing unit is a sweep frequency signal in a digital format, and the digital-to-analog conversion module is used for converting the control signal into an analog signal. The loudspeaker in the embodiment is a door panel loudspeaker installed on an automobile door panel, converts an electric signal into an acoustic signal, and replays in a sound field space in an automobile.
And the microphone is used for synchronously acquiring the acoustic response signals of the loudspeaker in real time. The microphone is electrically connected to the input end of the processing unit through the analog-to-digital conversion module and used for converting the acoustic response signals which are analog signals and collected by the microphone into digital signals.
The processing unit comprises a signal generating module, a self-adaptive filtering module, a noise power monitoring module and a multiplying module. And the input end of the signal generation module is electrically connected with the output end of the phase-locked loop frequency division area, the signal generation module updates an addressing address according to the triggering of each clock signal, reads a signal amplitude value from a sine signal lookup table prestored in the storage unit, and generates a sine signal and a cosine signal which are used as reference signals. The input end of the adaptive filtering module is electrically connected with the output end of the signal generating module and is used for filtering the reference signal, and the coefficient of the filter is updated along with the residual noise signal and the reference signal; in particular, in the present embodiment, the coefficients of the filter also change due to the tendency of the remaining noise power to change. In this embodiment, a general adaptive filter, such as LMS, RLS, or the like, is selected; or adaptive notch filter, which is particularly useful for engine noise reduction. And the input end of the noise power detection module is electrically connected with the output end of the analog-to-digital conversion module, and the noise power detection module is used for calculating the power of the residual noise in a fixed period, comparing the power with the noise power in the previous period, judging the noise reduction performance of the active noise reduction system, and correspondingly adjusting the updating parameters of the adaptive filter, so that the noise reduction system is ensured to work stably and normally without divergence or howling. The multiplication module is used for finishing the function of signal multiplication and updating and iterating the coefficient of the adaptive filtering module, one input end of the multiplication module is electrically connected with the output end of the noise power monitoring module, the other input end of the multiplication module is also electrically connected with the microphone through the analog-to-digital conversion module, and the output end of the multiplication module is electrically connected with one input end of the adaptive filtering module.
The embodiment also correspondingly provides a vehicle-mounted active noise control method, which comprises the following steps:
s1, acquiring a rotating speed signal of a vehicle engine;
s2, shaping the rotating speed signal;
s3, generating a clock signal according to the shaped rotating speed signal;
s4, generating a reference signal according to the clock signal and filtering the reference signal to generate a control signal; collecting the acoustic response signal of a loudspeaker, calculating the power of the residual noise in the current clock period according to the collected acoustic response signal, comparing the power of the residual noise with the power of the residual noise in the previous clock period, and correspondingly adjusting the coefficient of a filter.
The step S4 specifically includes:
s41, generating a reference signal, wherein the reference signal comprises a sine signal and a cosine signal, the counter cnt starts counting from the time of the 1 st clock period, and the sine signal x 1 (k) = sig (k), cosine signal
For the second clock cycle, counter cnt +1, k +1; when the counter
Zero clearing counter, k is also zero clearing, sine signal
Cosine signal x 2 (k) = sig (k); with the counter being incremented again and
zero clearing counter, k is also zero clearing, sine signal x 1 (k) = sig (k), cosine signal
With the counter again accumulating and
zero clearing counter, k is also zero clearing, sine signal
Cosine signal x 2 (k) = sig (k); at this time, a complete cycle is finished and is recorded as T; the cycle is repeated, and sine wave signals and cosine signals with fixed frequency resolution are generated along with the clock; wherein k represents a table index in the sine signal table, sig represents a numerical value corresponding to the table index in the sine signal table, and Δ f represents the frequency resolution;
s42, generating a control signal y (k) = w 1 *x 1 (k)+w 2 *x 2 (k) Wherein w is 1 、w 2 Respectively representing filter coefficients;
s43, picking up the acoustic response signal of the loudspeaker and recording the acoustic response signal as a residual noise signal e (k);
s44, updating the coefficient of the filter to be w 1 ＝w 1 +sign*μ*e(k)*x 1 (k)；w 2 ＝w 2 +sign*μ*e(k)*x 2 (k) Wherein sign is a constant representing a positive or negative number, and μ is a constant for adjusting the convergence step of the algorithm;
s45, monitoring the noise variation trend and accumulating the residual noise power E 1 ＝E 1 +[e(k)] 2 Until a complete period T is finished; in the next cycle, the residual noise power E is accumulated 2 ＝E 2 +[e(k)] 2 (ii) a Comparison E 1 And E 2 If E is 2 ＞E 1 Changing the number of symbols sign = -sign; otherwise, the number of symbols remains unchanged; two periods T are over and zero cleared E 1 And E 2 The monitoring is re-accumulated in the next period T.
Said step S4 further comprises a step S45 of introducing a leakage factor λ into the filter coefficient update, w 1 ＝(1-λ)*w1+sign*μ*λ*ek*x1k；w2＝1-λ*w2+sign*μ*λ*ek*x2k。
The active noise control process of the embodiment is as follows:
(1) And generating a sine signal lookup table. Generating a sinusoidal signal sequence off-line from
Frequency resolution Δ f (e.g. frequency resolution selection)
When the frequency resolution is as high as possible, a set of sequences is generated, denoted by
The sequence has 2 pi/delta f values, and the amplitude of all sampling points can be calculated by only generating amplitude values in 1/4 period in consideration of the characteristics of the sine wave. By using the symmetrical characteristic, the amplitudes of all sampling points of the cosine signal can be calculated. It should be noted that the sampling points are all frequency points obtained by normalizing the sampling rate. The smaller the frequency resolution, the higher the number of sequence points, which requires more memory space on the processor, but the finer and smoother the signal generated, which requires trade-offs in the specific engineering. In addition, the sine signal sequence is generated at the PC end, and the calculation resource of an active noise control system is not consumed; the sine signal sequence is stored in a storage unit of the processor, namely a sine signal lookup table.
(2) And initializing parameters. Setting a counter cnt and resetting the counter; setting a filter coefficient w 1 ,w 2 Zero clearing filter coefficients; the number of symbols sign =1 is set.
(3) The following processing steps of the active noise control system are as follows:
1) And obtaining a rotating speed signal of the engine. Attempts have been made to obtain a signal of the engine speed from a source, for example from a sensor of the vehicle itself, such as a crank sensor, an ignition pulse signal, etc. The rotating speed signal of the engine is a square wave signal, the period of the square wave signal changes along with the change of the rotating speed of the engine, the rotating speed signal of the engine is obtained from the source, the delay (more than 10ms at least) of the rotating speed signal obtained from a vehicle communication bus such as a CAN line and the working condition of processing quick acceleration are avoided, and therefore the tracking performance of the noise reduction system is prevented from being weakened and the noise reduction performance is prevented from being influenced.
2) And shaping the engine speed signal. The rotating speed signal of the engine is a square wave signal, but due to background noise of a sensor, transmission loss of a transmission line and the like, the waveform may have some noise waves which are not regular enough.
3) And generating a clock signal. The square wave signal passes through a phase-locked loop frequency divider to generate a clock signal; the clock signal is determined by the periodic characteristics of the square wave signal, and the change of the rotating speed of the engine can cause the periodic change of the square wave signal, so that the frequency of the clock signal is changed; the period of the clock signal does not exactly correspond to the period of the square wave signal, and can be adjusted by the parameter of the frequency division number of the phase-locked loop frequency divider.
4) And the clock signal drives the processing unit. The clock signal is fed to a processing unit, and the processing unit is an embedded processing platform in various forms such as an MCU, a DSP or an FPGA; alternatively, the processing unit is a module integrated on the car audio system, or may be a separate component. The processing unit starts to operate according to the period of the clock signal, and mainly operates the self-adaptive filtering algorithm. With reference to fig. 2 and 3, the specific steps are as follows:
i. the reference signal is generated, mainly generating a sine signal and a cosine signal. From the time of the 1 st clock cycle, the counter cnt starts counting; sinusoidal signal x 1 (k) = sig (k); cosine signal
For the second clock cycle, the counter cnt +1, k +1; when the counter
Zero clearing counter, k is also zero clearing, sine signal
Cosine signal x 2 (k) = sig (k); with the counter again accumulating and
zero clearing counter, k is also zero clearing, sine signal x 1 (k) = -sig (k); cosine signal
With the counter again accumulating and
zero clearing counter, kAlso clear, sinusoidal signals
Cosine signal x 2 (k) = sig (k); at this time, a complete cycle is finished and is recorded as T; the steps are repeated in a circulating way; generating sine wave signals and cosine signals with fixed frequency resolution along with a clock; the frequency of the signal corresponds exactly to the clock frequency; as the clock frequency changes; the frequency of the reference signal is changed without delay;
ii. Generating a control signal, and calculating an output signal of a main noise control system to obtain y (k) = w 1 *x 1 (k)+w 2 *x 2 (k)；
iii, synchronously picking up microphone signals, and recording as residual noise signals e (k);
iv updating the coefficient of the filter to w 1 ＝w 1 +sign*μ*e(k)*x 1 (k)；w 2 ＝w 2 +sign*μ*e(k)*x 2 (k)；
v, monitoring noise variation trend, and accumulating residual noise power E 1 ＝E 1 +[e(k)] 2 Until a complete period T is finished; in the next cycle, the residual noise power E is accumulated 2 ＝E 2 +[e(k)] 2 (ii) a Comparison E 1 And E 2 If E is of a size of 2 ＞E 1 Changing the number of symbols sign = -sign; otherwise, the number of symbols remains unchanged; two periods T are over and zero cleared E 1 And E 2 Accumulating and monitoring again in the next period T;
vi, introducing a leakage factor into filter coefficient updating, such as:
w 1 ＝(1-λ)*w 1 +sign*μ*λ*e(k)*x 1 (k)；
w 2 ＝(1-λ)*w 2 +sign*μ*λ*e(k)*x 2 (k)；
to maintain stability of the active noise reduction system.
The above embodiments are merely illustrative of the technical ideas and features of the present invention, and are preferred embodiments, which are intended to enable those skilled in the art to understand the contents of the present invention and implement the present invention, and not to limit the scope of the present invention. All equivalent changes and modifications made according to the spirit of the present invention should be covered in the protection scope of the present invention.
Claims (10)
1. An on-vehicle active noise control device, characterized by comprising:
the rotating speed measuring module is used for acquiring a rotating speed signal of a vehicle engine;
the shaping module is used for shaping the rotating speed signal;
the clock signal generating module is used for generating a clock signal according to the shaped rotating speed signal;
the processing unit is used for generating a reference signal according to the clock signal and filtering the reference signal to generate a control signal;
the power amplification module is used for driving a loudspeaker to sound according to the control signal; and
a microphone for acquiring an acoustic response signal of the speaker;
and the processing unit is further used for calculating the power of the residual noise in the current clock cycle according to the acoustic response signal, and comparing the power of the residual noise with the power of the residual noise in the previous clock cycle to correspondingly adjust the coefficient of the filter.
2. The on-vehicle active noise control device according to claim 1, wherein the processing unit includes:
the signal generation module is used for updating an addressing address according to the triggering of the clock signal so as to read a signal amplitude value from a prestored sine signal lookup table and generate a sine signal and a cosine signal as the reference signal;
an adaptive filtering module, configured to perform filtering processing on the reference signal;
and the noise power monitoring module is used for calculating the power of the residual noise of the current clock cycle, comparing the power with the power of the residual noise of the previous clock cycle and correspondingly adjusting the coefficient of the adaptive filtering module.
3. The on-vehicle active noise control device according to claim 2, wherein the processing unit further includes:
a multiplication module for coefficient update iterations of the adaptive filtering module.
4. The vehicle-mounted active noise control device according to claim 3, wherein an input end of the multiplication module is electrically connected with the noise power monitoring module, an input end of the multiplication module is further electrically connected with the microphone through an analog-to-digital conversion module, and an output end of the multiplication module is electrically connected with the adaptive filtering module.
5. The vehicle-mounted active noise control device according to claim 2, wherein the adaptive filtering module includes an adaptive filter that can change in accordance with a trend of a power change of the remaining noise.
6. The vehicle-mounted active noise control device according to claim 1, wherein the clock signal generation module is a phase-locked loop divider.
7. A vehicle-mounted active noise control method is characterized by comprising the following steps:
s1, acquiring a rotating speed signal of a vehicle engine;
s2, shaping the rotating speed signal;
s3, generating a clock signal according to the shaped rotating speed signal;
s4, generating a reference signal according to the clock signal and filtering the reference signal to generate a control signal; collecting the sound response signal of a loudspeaker, calculating the power of the residual noise in the current clock period according to the collected sound response signal, and comparing the power with the power of the residual noise in the previous clock period to correspondingly adjust the coefficient of the filter.
8. The vehicle-mounted active noise control method according to claim 7, wherein the step S4 specifically includes:
s41, generating a reference signal, wherein the reference signal comprises a sine signal and a cosine signal, and a counter is arranged from the time of the 1 st clock period
Start of count, sinusoidal signals
Cosine signal
(ii) a Second clock cycle, counter
，
(ii) a When the counter
The counter is reset to zero,
also clear, sinusoidal signals
Cosine signal
(ii) a With the counter again accumulating and
the counter is reset to zero,
also clear, sinusoidal signals
Cosine signal
(ii) a With the counter being incremented again and
the counter is reset to zero,
also clear, sinusoidal signals
(ii) a Cosine signal
(ii) a At this point, a complete cycle ends, which is recorded as
(ii) a The cycle is repeated, and sine wave signals and cosine signals with fixed frequency resolution are generated along with the clock; wherein,
representing the table index in the sine signal table,
represents the value corresponding to the table index in the sine signal table,
represents a frequency resolution;
s42, generating a control signal
Wherein
、
respectively representing filter coefficients;
s43, picking up the acoustic response signal of the loudspeaker and recording the acoustic response signal as a residual noise signal
；
S44, updating the coefficient of the filter to be
；
Wherein
is a constant that represents a positive or negative number,
a constant for adjusting the convergence step of the algorithm;
s45, monitoring the noise variation trend and accumulating the residual noise power
Up to a complete cycle
Finishing; accumulating the residual noise power in the next cycle
(ii) a Comparison
And
is large or small, if
Changing the number of symbols
(ii) a Otherwise, the number of symbols remains unchanged; two periods
End, clear
And
in the next cycle
And (5) accumulating the monitoring again.
9. The vehicle-mounted active noise control method according to claim 8, wherein the step S4 further comprises a step S46 of introducing a leakage factor
In the update of the coefficients of the filter,
；
。
10. the vehicle active noise control method according to claim 7, wherein in step S3, the clock signal is generated by a phase-locked loop divider.
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| CN112328949B (en) * | 2020-10-26 | 2024-02-27 | 中科上声（苏州）电子有限公司 | Reference signal generation method and device for active noise reduction system of automobile engine |
| CN113851102B (en) * | 2020-10-26 | 2025-02-25 | 中科上声（苏州）电子有限公司 | A mixing method and device for vehicle audio system |
| CN114255727A (en) * | 2021-04-13 | 2022-03-29 | 北京安声科技有限公司 | Active noise reduction method, vehicle active noise reduction system, and automobile |
| CN114255728A (en) * | 2021-04-13 | 2022-03-29 | 北京安声科技有限公司 | Active noise reduction method, vehicle-mounted active noise reduction system and automobile |
| CN114061941B (en) * | 2021-10-18 | 2023-12-19 | 吉林大学 | An experimental environment adjustment test method, system and test chamber for new energy vehicle gearboxes |
| CN114743534A (en) * | 2022-03-09 | 2022-07-12 | 中科上声（苏州）电子有限公司 | Vehicle noise reduction method for broadband noise |
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