JP6737142B2 - Noise control device, noise control method, and power machine - Google Patents

Description

The present invention relates to a noise control device, a noise control method, and a power machine.

Active noise control (ANC) is one of the measures against the noise generated by the power source. ANC is a technique of silencing by interfering control sounds of the same amplitude and opposite phase with the control target sound. The ANC is effective for low frequency noise and does not require a large space as an installation place. For this reason, the ANC is often used for reducing vehicle interior noise and engine muffled noise.

As a noise control device to which ANC is applied, for example, in Patent Document 1, a sine wave signal having a fundamental frequency and a sine wave signal having a frequency of a multiple thereof included in a sound generated from a power source are used as reference signals, and ambient sound is generated. There is disclosed a noise control device for controlling noise generated in a power source by inputting the error signal to an adaptive filter. This adaptive filter operates according to the HFxLMS (Harmonic Filtered-x Least Mean Square) algorithm.

JP, 2014-153571, A

When the power source is, for example, an engine of a motorcycle, the fundamental frequency of the engine sound changes with the acceleration/deceleration. However, since the adaptive filter has a mechanism that gradually changes the filter characteristics with time, if the frequency of the engine sound changes due to acceleration/deceleration, the update of the adaptive filter may be delayed in response to the change. was there.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a noise control device, a noise control method, and a power machine that can improve the followability to changes in the fundamental frequency of the power source.

In order to achieve the above object, the noise control device according to the first aspect of the present invention is
A basic frequency calculation unit that calculates the basic frequency of the pulse signal that drives the power source,
A sine wave signal of a specific order frequency among multiples of the fundamental frequency, and a plurality of different values within a range determined based on the variation characteristic of the driving frequency of the power source with the specific order frequency as a reference. A signal generation unit that generates a sine wave signal of a frequency,
A voice input unit for inputting sounds around the power source;
An adaptive filter that operates according to the LMS algorithm is provided for each of the plurality of sine wave signals generated by the signal generation unit, and each of the adaptive filters inputs the corresponding sine wave signal as a reference signal, and the voice input unit An adaptive filter unit that inputs an input voice signal as an error signal and outputs an output signal obtained by adding the signals output from the respective adaptive filters,
A voice output unit that outputs a voice corresponding to the output signal of the adaptive filter unit;
Equipped with.

In this case, the signal generation unit determines, for each signal of the sine wave signal having the fundamental frequency and the sine wave signal having a frequency of a multiple thereof, a corresponding frequency determined based on a variation in the drive frequency of the power source. Generate multiple sinusoidal signals with different frequencies in the reference range,
It may be that.

Further, the power source is an engine,
The pulse signal is an ignition pulse signal indicating the ignition timing of the engine,
It may be that.

Each of the adaptive filters is implemented in a separate processor or programmable logic circuit that can operate in parallel,
It may be that.

A power machine according to a second aspect of the present invention is
A noise control device of the present invention;
A main unit that operates by the power generated by the power source,
Equipped with.

A noise control method according to a third aspect of the present invention is
A fundamental frequency calculating step of calculating a fundamental frequency of a pulse signal for driving the power source,
A sine wave signal of a specific order frequency among multiples of the fundamental frequency, and a plurality of different values within a range determined based on the variation characteristic of the driving frequency of the power source with the specific order frequency as a reference. A signal generation step for generating a sine wave signal of frequency,
A voice input step of inputting a sound around the power source,
The plurality of adaptive filters operating according to the LMS algorithm provided for each of the plurality of sine wave signals generated in the signal generating step inputs the corresponding sine wave signals as reference signals and also the voice input in the voice input step. An adaptive filter step of inputting a signal as an error signal and outputting an output signal corresponding to the sum of outputs of the adaptive filter;
A voice output step of outputting a voice corresponding to the output signal output in the adaptive filter step,
Is repeatedly executed.

According to the present invention, the adaptive filter is provided not only for the specific frequency of the pulse signal that drives the power source, but also for the sinusoidal wave signals of other frequencies within the range based on the specific frequency, and the outputs of the adaptive filters are added. An output signal for controlling the noise is generated. By doing this, even if the fundamental frequency of the power source changes, internal parameters such as the convergence coefficient are optimized at the changed fundamental frequency, so it is necessary to quickly follow changes in the fundamental frequency. You can As a result, it is possible to improve the followability to changes in the fundamental frequency of the power source.

It is a block diagram which shows the structure of the noise control apparatus which concerns on Embodiment 1 of this invention. It is a graph which shows an example of an ignition pulse signal. It is a graph which shows the frequency characteristic of an engine. 3 is a table showing a relationship between a reference signal and its frequency in the noise control device of FIG. 1. It is a graph which shows the relationship of the time change of a drive frequency and the range of a sine wave signal frequency. It is a control block diagram of the engine sound of the control system centering on the adaptive filter part which operates according to the LMS algorithm. It is a flowchart of operation|movement of the noise control apparatus of FIG. 7 is a graph showing a control result of the noise control device in an environment in which an engine sound obtained during steady running is simulated. FIG. 9A is a graph showing the control result of the conventional noise control device. FIG. 9B is a graph showing the control result of the noise control device of FIG. It is a block diagram which shows the structure of the noise control apparatus which concerns on Embodiment 2 of this invention. 11 is a table showing a relationship between reference signals and frequencies in the noise control device of FIG. 10.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

Embodiment 1.
First, the first embodiment of the present invention will be described.

The noise control device 1 according to the present embodiment is attached to a vehicle body (body device) 2. The noise control device 1 and the vehicle body 2 constitute a power machine 100. The vehicle body 2 includes an engine 3 and a drive unit 4 that drives the engine 3. The noise control device 1 is used to control a noise (engine sound) generated from the engine 3 driven by an ignition pulse signal output from the drive unit 4 and indicating an ignition timing of the engine 3. The noise control device 1 responds to changes in the frequency of the engine sound by including a plurality of adaptive filters 20 as digital filters corresponding to different frequencies. A detailed configuration of the noise control device 1 for realizing such correspondence will be described.

As shown in FIG. 1, the noise control device 1 includes a fundamental frequency calculation unit 10, a signal generation unit 11, a voice input unit 12, an adaptive filter unit 13, and a voice output unit 14.

The basic frequency calculation unit 10 calculates the basic frequency of the pulse signal that drives the power source. In this embodiment, the power source is the engine 3. The pulse signal is an ignition pulse signal indicating the timing of ignition of the engine 3. FIG. 2 shows an example of the ignition pulse signal. The arrow in the figure indicates the pulse period. When the engine 3 is an in-line 4-cylinder 4-cycle engine, the pulse period is represented by the following mathematical formula.
Pulse period = (engine speed [rpm]/time [s]) ^-1
The in-line 4-cylinder 4-cycle engine sequentially performs intake, compression, explosion (ignition), and exhaust while the crankshaft makes two revolutions. If it has four cylinders, it will explode twice in one rotation.

The frequency characteristic of the sound of the engine 3 changes according to the driving speed of the engine 3. For example, when the rotation speed of the engine 3 changes from 2700 rpm to 2900 rpm, the frequency characteristic of the engine sound changes as shown in FIG. The noise control device 1 has a configuration that follows such a change in engine sound.

Returning to FIG. 1, the signal generation unit 11 includes the fundamental frequency f _b calculated by the fundamental frequency calculation unit 10 and its multiple frequencies 2f _b , 3f _b, ..., That is, the multiple frequencies f _b , 2f of the fundamental frequency f _b. Generates a sine wave signal of a specific frequency of a specific order among the frequencies of _{b 1} , 3f _b, .... In this specification, a signal that fluctuates at a specific frequency is defined as a sine wave signal, and the signal includes a cosine wave signal. Further, the frequency of multiple order may be, for example, the frequency of 1.5 order. This sine wave signal is a digital signal. The sampling number of this digital signal is n (n is a natural number). In the present embodiment, the signal generator 11 generates a sine wave signal x ₁ (n) having a fundamental frequency f _b (see FIG. 4).

Further, the signal generator 11 generates a plurality of sine wave signals x ₂ (n) to x _N (n) having different frequencies within the range of the frequency band with the specific frequency as a reference. N is the number of sinusoidal signals generated. In the present embodiment, these frequencies are f _b ±1, f _b ±2,..., F _b ±m (Hz) (m is a natural number). Note that this interval may include a decimal number such as 0.5.

The frequency range in which the sine wave signals x ₂ (n) to x _N (n) are generated is determined based on the variation characteristic of the drive frequency of the engine 3. That is, it is set within a range that does not cause a delay longer than the permissible time with respect to the change over time of the drive frequency of the engine 3. Further, the number of frequencies selected from this range can be determined by the capability of the processor or the programmable logic circuit in which the adaptive filter unit 13 described later is mounted. The narrower the frequency interval, the more highly accurate noise tracking control becomes possible.

The voice input unit 12 inputs ambient sound including the power source (engine 3). As the voice input unit 12, for example, a small microphone is used. In the present embodiment, the digital audio signal input by the audio input unit 12 becomes the error signal e(n) in the noise control device 1.

Returning to FIG. 1, the adaptive filter unit 13 is a digital filter mounted on a computer or a programmable logic circuit that performs signal processing. The computer mainly includes a processor such as a CPU (Central Processing Unit) and a DSP (Digital Sound Processor). The processor executes the processing program of the LMS algorithm stored in the memory or the programmable logic circuit operates to execute the processing of the adaptive filter 20.

The adaptive filter unit 13 includes a plurality of adaptive filters 20 that operate according to the LMS algorithm. The LMS algorithm will be described later. The adaptive filter 20 is provided for each of the plurality of sine wave signals x ₁ (n) to x _N (n) generated by the signal generation unit 11. Each adaptive filter 20 inputs the corresponding sine wave signal as a reference signal x _k (n) (one of natural numbers k=1 to N), and outputs the audio signal input by the audio input unit 12 as an error signal e( n).

As shown in FIG. 4, the reference signal x ₁ (n) is a sine wave signal having a fundamental frequency f _b (Hz), and x ₂ (n) and x ₃ (n) are fundamental frequencies f _b ±Δf ₁ (Hz ) Becomes a sine wave signal. Further, x ₄ (n) and x ₅ (n) are sine wave signals having a fundamental frequency f _b ±Δf ₂ (Hz), and x _N−1 (n) and x _N (n) are fundamental frequencies f _b ±Δf It becomes a sine wave signal of _m (Hz).

Each adaptive filter 20 of the adaptive filter unit 13 inputs a plurality of sine wave signals x _k (n) of different frequencies within the range of the frequency band f _b −Δf _{m to} f _b +Δf _m as a reference signal and outputs the corresponding frequency. The calculation result of the adaptive filter 20 for is output.

Further, the adaptive filter unit 13 includes an adding unit 21. The adder 21 adds the signals output from the adaptive filters 20. The adaptive filter unit 13 outputs the output signal obtained by the adding unit 21.

As shown in FIG. 5, the adaptive filter unit 13 applies the adaptive filter 20 to the sine wave signals x _k (n) having different frequencies within the frequency bands f _b −Δf _{m to} f _b +Δf _m , respectively. Thus, the frequency band to be controlled centering on the fundamental frequency f _b is expanded to f _b −Δf _{m to} f _b +Δf _m . Each adaptive filter 20 inputs the error signal e(n) while inputting the sine wave signals x _k (n) of a plurality of different frequencies within the range of f _b −Δf _{m to} f _b +Δf _m , and will be described later. Thus, it operates according to the LMS algorithm and outputs each output signal y _k (n). The audio output unit 14 outputs a signal obtained by adding the outputs y _k (n) of the respective adaptive filters 20. That is, the output signal output from the audio output unit 14 is always a signal obtained by adding the outputs y _k (n) of the respective adaptive filters 20. The internal parameters of each adaptive filter 20 are optimized according to the error signal e(n).

As shown in FIG. 5, in the period from time 0 to t1, when the frequency of the engine sound is constant at f _b , the error signal e(n) mainly contains the component of the frequency f _b . As the component included in the output signal output from the audio output unit 14, the output y _k (n) of the adaptive filter 20 to which the sine wave signal x _k (n) of the frequency f _b is input becomes maximum, but the frequency The other adaptive filters 20 corresponding to frequencies around f _b are also optimized so that the output y _k (n) does not become 0 but has a certain size. That is, in the adaptive filter unit 13, each adaptive filter 20 operates by being optimized by the feedback of the error signal e(n), and in the state where each output is weighted, an output signal that cancels the engine sound as a whole is generated. ing.

During the period from time t1 to t2, when the frequency of the engine sound increases due to acceleration and reaches the frequency fb+Δf ₁ , the output y _k (n) of the adaptive filter 20 that inputs the sine wave signal x _k (n) of the frequency f _b. Lags behind changes in its frequency. However, in the adaptive filter unit 13, the adaptive filter 20 that inputs the sine wave signal x _k (n) of the frequency fb+Δf ₁ has already been optimized at that frequency, and the output y _k (n) corresponding to this frequency change. Is being output. With this output y _k (n), the adaptive filter unit 13 can improve the followability with respect to the adaptive filter having the sinusoidal signal of a single frequency as an input.

Similarly, the time t2 to t3, during the period of t3 to t4, even when the frequency of the engine sound becomes high as _{f b + Δf 2 ~f b +} Δf 3, f b + Δf 3 ~f b + Δf m, the respective frequency Since the corresponding adaptive filter 20 is already operating optimized at the corresponding frequency, the output y _k (n) of the adaptive filter 20 at the corresponding frequency responds rapidly to sudden changes in frequency. be able to.

The basic frequency calculated by the basic frequency calculation unit 10 changes according to the acceleration, and the frequency of the sine wave signal x _k (n) input to each adaptive filter 20 also changes. However, the adaptive filter unit 13 can quickly follow the frequency change of the sine wave signal x _k (n) in advance of the frequency change. The above is the same even when the engine 3 is decelerated and the frequency of the engine sound is reduced.

The voice output unit 14 outputs a voice corresponding to the output signal of the adaptive filter unit 13. As the audio output unit 14, for example, a speaker is used. This speaker is installed, for example, in the upper part of the engine 3 of the vehicle body 2 in the vicinity of a pipe that sends air from the intake port to the engine 3 on the front side of the seat. However, the place where the speaker is installed is not limited to this, and it is desirable that the place where the causality of noise is satisfied, such as sharing the speaker for audio.

ここで、Ｎ_ｃは、音が発生する空間の伝達関数Ｇ（ｎ）の長さである。 Next, a control system for controlling noise will be described focusing on the adaptive filter unit 13. The updating formula of the adaptive filter 20 in this control system is shown below.

Here, N _c is the length of the transfer function G(n) of the space where the sound is generated.

As shown in FIG. 6, in this control system, the reference signals x ₁ (n) to x _N (n) are input to the filters of the corresponding internal parameters (impulse response) W ₁ (n) to W _N (n). To be done. The filter outputs the outputs y ₁ (n) to y _N (n) as control signals by performing a convolution operation of x ₁ (n) to x _N (n) and W ₁ (n) to W _N (n). ..

A sound signal obtained by adding the outputs y ₁ (n) to y _N (n) is output to the surroundings of the engine 3. This audio signal propagates in the surrounding space. G(n) in FIG. 6 is the transfer function of the sound in this space. This propagated audio signal corresponds to the second term on the right side of the above equation (1). This voice signal interferes with the sound (desired signal) d(n) from the engine 3 and is acquired as an error signal e(n) as shown in the above equation (1).

に入力される。また、誤差信号ｅ（ｎ）は、収束係数μ_ｋ（ｎ）に掛け合わされ、ＬＭＳに入力される。ＬＭＳでは、上記式（２）を演算して、サンプリング番号ｎ＋１における内部パラメータＷ_ｋ（ｎ＋１）を求め、フィルタに設定する。 On the other hand, the reference signals x ₁ (n) to x _N (n) are the modeling transfer functions of G(n).

Entered in. Further, the error signal e(n) is multiplied by the convergence coefficient μ _k (n) and input to the LMS. In the LMS, the above equation (2) is calculated to find the internal parameter W _k (n+1) at the sampling number n+1 and set it in the filter.

The LMS algorithm changes the internal parameters of the filter so that the root mean square error is minimized. The second term on the right side of the above equation (2) is an error term for approaching the optimum solution with the minimum mean square error.

The procedure of the LMS algorithm is as follows.
(A) At start time n=0, an appropriate initial value is given to W _k (n). All the initial values of the elements of W _k (n) may be 0 or the initial values considered to be optimum values.
(B) The output y _k (n) of the filter at time n is obtained based on x _k (n) and W _k (n), and the output signal that is the added value of y _k (n) is output. Then, the error signal e(n) is obtained.
Using (C)x _k (n) and e(n), W _k (n+1) is obtained using the above equation (2) in the LMS of FIG. 6 and set in the adaptive filter.
(D) Update n to n+1 and return to (B).

In the adaptive filter 20, by repeating the above process, W _k (n) is changed by sequential calculation, and the internal parameter W _k (n) is optimized so that the error signal e(n) is minimized.

Next, the operation of the noise control device 1 will be described.

As shown in FIG. 7, first, it is determined whether the engine 3 is started (step S1). If it has not started (step S1; No), the noise control device 1 waits until the engine 3 starts.

When the engine 3 is started (step S1; Yes), the basic frequency calculation unit 10 calculates the basic frequency f _b of the ignition pulse signal that drives the engine 3 (step S2; basic frequency calculation step).

Then, the signal generator 11 outputs the sine wave signal x ₁ (n) of the specific frequency (here, the first-order frequency) f _b of the fundamental frequency f _b and its multiple-order frequencies to the engine 3 a plurality of different frequencies in the range relative to the frequency f _b is determined based on the fluctuation of the drive frequency (the fundamental frequency f _b as well its overtones, their frequencies around) sine wave such as f _b ± Δf _m The signals x ₂ (n) to x _N (n) are generated (step S3; signal generation step).

Subsequently, the voice input unit 12 inputs a sound around the engine 3 (step S4; voice input step). The input audio signal becomes the error signal e(n).

Subsequently, in the adaptive filter unit 13, the plurality of adaptive filters 20 operating according to the LMS algorithm provided for each of the plurality of sine wave signals generated by the signal generation unit 11 convert the corresponding sine wave signal into the reference signal x _k ( n) and the audio signal input by the audio input unit 12 as the error signal e(n), and generate and output an output signal corresponding to the sum of the outputs of the adaptive filter 20 (step S5; adaptation). Filter process).

Then, the audio output unit 14 outputs the audio corresponding to the output signal of the adaptive filter unit 13 (step S6; audio output step). This sound is a sound that cancels the sound of the engine 3.

Then, the noise control device 1 returns to step S1 and repeats steps S2 to S6 if the engine is not stopped (step S1; Yes). This repetition is performed at fixed sampling intervals, and one process is performed within the sampling time range. The execution order of steps S2, S3, and S4 is not limited to that shown in FIG.

FIG. 8 shows the control result of the noise control device 1 under the environment in which the engine sound obtained during steady running is simulated. The broken line in the figure shows the frequency characteristic before control, and the solid line shows the frequency characteristic during control. As shown in FIG. 8, when the control by the noise control device 1 was executed, the sound pressure level at 100 Hz (fundamental frequency f _b ) targeted for control was reduced by 25 dB or more. Further, the tracking performance is not deteriorated at frequencies other than the control target frequency, and stable control is realized. As described above, the noise control device 1 according to the present embodiment satisfactorily reduces the engine sound during steady running without acceleration/deceleration while inputting a plurality of sine wave signals.

FIG. 9(A) shows a control result when control is performed using the conventional HFxLMS algorithm during acceleration traveling. Further, FIG. 9(B) shows the result of control by the noise control device 1 according to the present embodiment during accelerated travel. As can be seen by comparing FIG. 9(A) and FIG. 9(B), there is almost no difference in the control results during steady running (approximately 0 to 4 seconds). However, when acceleration starts, the noise control by the HFxLMS algorithm cannot follow the frequency change and cannot muffle, whereas the noise control device 1 according to the present embodiment follows the frequency change quickly. , The noise is significantly reduced.

As described above in detail, according to the present embodiment, the adaptive filter 20 causes the sine of not only the specific frequency of the ignition pulse signal for driving the engine 3 but also other frequencies within the range based on the specific frequency. A wave signal is provided, and the outputs of the adaptive filter 20 are added to generate an output signal for controlling noise. In this way, even if the fundamental frequency of the engine 3 changes, internal parameters such as the convergence coefficient are optimized at the changed fundamental frequency, so that it is possible to quickly follow changes in the fundamental frequency. You can As a result, it is possible to enhance the followability to changes in the fundamental frequency of the engine 3.

Embodiment 2.
Next, a second embodiment of the present invention will be described.

In the above-described embodiment, the frequency is set to generate a sine wave signal having any one of the fundamental frequency f _b and the frequencies of multiples thereof. In the present embodiment, as shown in FIG. 10, the signal generation unit 11 uses not only a sine wave signal around the fundamental frequency f _b but also sine waves having frequencies 2f _b and 3f _b that are multiples of the fundamental frequency f _b. For each of the signals, a sine wave signal having a plurality of different frequencies within a range defined based on the variation of the driving frequency of the engine 3 and having the frequency as a reference is generated.

More specifically, the signal generator 11, as shown in FIG. 11, the fundamental frequency _{f b} of the fundamental frequency band around the frequency _{f b -Δf m} ~f b + _Δf reference signal a sine wave signal of _{m x} 1 ( n) to x _M (n) are input to the adaptive filter unit 13. Further, the signal generator 11, reference signal a sine wave signal of a frequency _{2f b -Δf m ~2f b + Δf} m of double frequency band near the frequency 2f _b twice _{x M + 1 (n) ~x} 2M (n) Is input to the adaptive filter unit 13. Further, the signal generator 11, three times the frequency _3f triple frequency band near the frequency 3f _{b b} -Δf _m ~3f _b + reference signal a sine wave signal of _{Δf m x 2M + 1 (n} ) ~x 3M (n) Is input to the adaptive filter unit 13.

Thus, not only around the fundamental frequency f _b . By operating the adaptive filter 20 in parallel for a plurality of frequencies around the multiple-order frequencies 2f _b and 3f _b , it is possible to further cope with changes in the multiple-order component frequencies 2f _b and 3f _b due to acceleration/deceleration. You can

In the above embodiment, a plurality of different frequencies in the range of the frequency band with the specific frequency as a reference are defined as, for example, f _b ±Δf ₁ , f _b ±Δf ₂ ,..., F _b ±Δf _m (Hz). However, the present invention is not limited to this. For example, the frequencies around these may be 0.998f _b , 0.999f _b , 1.001f _b , and 1.002f _b . The number and interval of frequencies can be set arbitrarily. Also, the frequency intervals need not all be the same.

In each of the above embodiments, the engine 3 is an in-line 4-cylinder 4-cycle engine, but the engine 3 is not limited to this.

Further, in each of the above embodiments, the ignition pulse signal is used to calculate the fundamental frequency, but the present invention is not limited to this. Other pulse signals, such as a cam position sensor signal that detects the rotational position of the cam shaft and a crank angle sensor signal that detects the rotational angle of the crank shaft, that can determine the engine rotation state, either individually or in combination It can also be used for frequency calculation.

In each of the above embodiments, the noise control device 1 is used to control the noise of the engine 3 of the vehicle body 2, but the present invention is not limited to this. For example, it may be used for controlling the noise of the engine of each vehicle other than the automobile. In this case, the power source is not limited to the engine and may be a motor or the like. Further, the present invention is not limited to vehicles, but can be applied to various power machines such as machine tools having a power source. For example, the present invention can be applied to a power machine having a rotating mechanism such as an engine or a motor.

Further, each adaptive filter 20 may be implemented in a separate processor or programmable logic circuit that can operate in parallel. With this configuration, the processing capability of the adaptive filter unit 13 can be increased without increasing the load on the processor or the programmable logic circuit.

In addition, the hardware configuration and software configuration of the adaptive filter unit 13 (computer) are examples, and can be arbitrarily changed and modified.

The central part that performs computer processing can be realized using a normal computer system instead of a dedicated system. For example, a computer program for executing the above operation is stored in a computer-readable recording medium (flexible disk, CD-ROM, DVD-ROM, etc.) and distributed, and the computer program is installed in the computer. A computer may be configured to execute the above processing. Alternatively, the computer program may be stored in a storage device included in a server device on a communication network such as the Internet, and the computer may be configured by being downloaded by an ordinary computer system.

When the function of the computer is realized by sharing of the OS (operating system) and the application program, or by cooperation between the OS and the application program, only the application program portion may be stored in the recording medium or the storage device.

It is also possible to superimpose a computer program on a carrier wave and distribute it via a communication network. For example, the computer program may be posted on a bulletin board (BBS, Bulletin Board System) on the communication network, and the computer program may be distributed via the network. Then, the computer program may be started up and executed under the control of the OS in the same manner as other application programs so that the above-described processing can be executed.

The present invention allows various embodiments and modifications without departing from the broad spirit and scope of the present invention. Further, the above-described embodiments are for explaining the present invention and do not limit the scope of the present invention. That is, the scope of the present invention is shown not by the embodiments but by the scope of the claims. Various modifications made within the scope of the claims and the scope of the invention equivalent thereto are considered to be within the scope of the present invention.

The present invention can be applied to control the noise generated from a power source.

1 noise control device, 2 vehicle body, 3 engine, 4 drive unit, 10 basic frequency calculation unit, 11 signal generation unit, 12 audio input unit, 13 adaptive filter unit, 14 audio output unit, 20 adaptive filter, 21 addition unit, 100 power machinery

Claims (6)

A basic frequency calculation unit that calculates the basic frequency of the pulse signal that drives the power source,
A sine wave signal of a specific order frequency among multiples of the fundamental frequency, and a plurality of different values within a range determined based on the variation characteristic of the driving frequency of the power source with the specific order frequency as a reference. A signal generation unit that generates a sine wave signal of a frequency,
A voice input unit for inputting sounds around the power source;
An adaptive filter that operates according to the LMS algorithm is provided for each of the plurality of sine wave signals generated by the signal generation unit, and each of the adaptive filters inputs the corresponding sine wave signal as a reference signal, and the voice input unit An adaptive filter unit that inputs an input voice signal as an error signal and outputs an output signal obtained by adding the signals output from the respective adaptive filters,
A voice output unit that outputs a voice corresponding to the output signal of the adaptive filter unit;
Noise control device. The signal generation unit uses, as a reference, a corresponding frequency that is determined on the basis of fluctuations in the driving frequency of the power source for each of the sine wave signal having the fundamental frequency and the sine wave signal having a frequency of a multiple thereof Generate multiple sinusoidal signals of different frequencies in the range,
The noise control device according to claim 1. The power source is an engine,
The pulse signal is an ignition pulse signal indicating the ignition timing of the engine,
The noise control device according to claim 1 or 2, characterized in that. Each of the adaptive filters is implemented in a separate processor or programmable logic circuit that can operate in parallel,
The noise control device according to claim 1. A noise control device according to any one of claims 1 to 4,
A main unit that operates by the power generated by the power source,
Power machine equipped with. A fundamental frequency calculating step of calculating a fundamental frequency of a pulse signal for driving the power source,
A sine wave signal of a specific order frequency among multiples of the fundamental frequency, and a plurality of different values within a range determined based on the variation characteristic of the driving frequency of the power source with the specific order frequency as a reference. A signal generation step for generating a sine wave signal of frequency,
A voice input step of inputting a sound around the power source,
The plurality of adaptive filters operating according to the LMS algorithm provided for each of the plurality of sine wave signals generated in the signal generating step inputs the corresponding sine wave signal as a reference signal and the voice input in the voice input step. An adaptive filter step of inputting a signal as an error signal and outputting an output signal corresponding to the sum of outputs of the adaptive filter;
A voice output step of outputting a voice corresponding to the output signal output in the adaptive filter step,
A noise control method that repeatedly executes.

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