JP2743639B2 - Active noise control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an active noise control device for suppressing noise by causing a noise from a noise source to interfere with a noise suppression signal generated by a control sound source, and in particular to modeling a space transfer function. The present invention relates to an active noise control device capable of identifying a modeled space transfer function at a predetermined timing.

[0002]

2. Description of the Related Art Conventionally, as an active noise control device of this type, there is one described in, for example, Japanese Patent Application Laid-Open No. 1-501344. This conventional example is an active noise control device that emits a control sound from a loudspeaker to reduce noise transmitted from a noise source into the vehicle interior, and detects residual noise in the vehicle interior using a plurality of microphones. Adaptively filtering the reference signal by generating at least one reference signal including optionally selectable harmonics of the noise source and providing the residual noise detection signal and the reference signal to a processor / storage unit. Thus, a drive signal for the loudspeaker is formed. Here, in the adaptive filter processing, the i-th filter coefficient W _mi (n + 1) is set to minimize the evaluation function J set as the mean square sum of the detection signals V _ek of the plurality of microphones according to the LMS algorithm. Then, updating is performed sequentially according to the following equation (1).

[0003]Where W_mi(n) is the filter at the previous or n-th sample.
Luta coefficient, μ is the convergence coefficient, V_ekIs the k-th microphone
Output, x is a reference signal correlated to the noise source, C _km'Is m
The real sky between the ith speaker and the kth microphone
Corresponding to the model space transfer function
Base filter coefficients.

Further, the processor / storage unit supplies white noise generated from the white noise generator to the speaker as a drive signal during the initialization program,
By detecting this with a microphone and inputting the detection signal, the base filter coefficient C _km (n) is identified.

[0005]

However, in the above-mentioned conventional active noise control device, the control algorithm for updating the filter coefficient of the adaptive filter uses the actual spatial transfer function C _km itself between the loudspeaker and the microphone. Instead, the model space transfer function C _km 'that models this is used.
When the actual transfer function changes due to the deterioration of the microphone, the temperature change in the closed space, the opening and closing of the door, and the like, the filter coefficient W _{mi of the} adaptive filter calculated by the above equation (1).
An error occurs in (n + 1), and the evaluation function J diverges without converging,
Since abnormal noise may occur, it is necessary to identify the model space transfer function and the actual space transfer function, but the model space transfer function is identified only in the initial program. When the actual space transfer function changes due to long-time running, a change in the temperature in the cabin, opening / closing of a door, etc., the actual space transfer function cannot be followed, and there is a difference between the real space transfer function and the modeled space transfer function. There is an unsolved problem that the noise reduction performance of the control system is deteriorated.

The present invention has been made in view of the above-mentioned unsolved problems of the prior art, and is an active type which can frequently identify a model space transfer function without causing discomfort to an occupant. It is intended to provide a noise control device.

[0007]

In order to achieve the above object, an active noise control apparatus according to a first aspect of the present invention, as shown in FIG. Input to the control sound source via the control sound source, and the combined sound pressure of the sound pressure transmitted from the control sound source and the ambient noise sound pressure is detected by the residual noise detection means, and the reference signal is transmitted between the control sound source and the residual noise detection means. A filter coefficient updating unit updates the filter coefficient of the adaptive filter based on a signal filtered by a filter unit using a model space transfer function as a filter coefficient and modeling the space transfer function and the residual noise detection signal. In the active noise control device, accelerated running state detecting means for detecting the accelerated running state of the vehicle,
When the acceleration traveling state is detected by the acceleration traveling state detection means, a test signal is supplied to the control sound source and the filter means instead of the reference signal, and the test signal detected by the residual noise detection means and the filter means. Identification means for comparing the test signal subjected to the filter processing with the filter signal to identify a model space transfer function of the filter means.

The active noise control apparatus according to claim 2 inputs a reference signal according to a control noise generation state to a control sound source through an adaptive filter means as shown in FIG. The synthesized sound pressure of the transmitted sound pressure and the surrounding noise sound pressure is detected by the residual noise detection means, and the reference signal is converted into a model space transfer function obtained by modeling a space transfer function between the control sound source and the residual noise detection means. In the active noise control apparatus, the filter coefficient of the adaptive filter is updated by the filter coefficient updating means based on the signal filtered by the filter means as the filter coefficient and the residual noise detection signal. Traveling speed detecting means for detecting vehicle speed, vehicle speed detecting means for detecting vehicle speed, and a vehicle speed detection value detected by the vehicle speed detecting means being equal to or higher than a predetermined vehicle speed threshold value and accelerating. A test signal is supplied to the control sound source and the filter means in place of the reference signal when the acceleration state is detected by the line state detection means, and the test signal detected by the residual noise detection means is filtered by the filter means. Identification means for comparing the test signal with the test signal and identifying a model space transfer function of the filter means.

Further, as shown in FIG. 3, the active noise control device according to claim 3 inputs a reference signal according to a control noise generation state to a control sound source through an adaptive filter means.
A model obtained by detecting a combined sound pressure of the sound pressure transmitted from the control sound source and the sound pressure of the surrounding noise by residual noise detection means, and modeling the reference signal as a spatial transfer function between the control sound source and the residual noise detection means. In an active noise control apparatus, a filter coefficient updating unit updates a filter coefficient of the adaptive filter based on a signal filtered by a filter unit using a space transfer function as a filter coefficient and the residual noise detection signal. A test signal supplied to the control sound source and the filter means in place of the reference signal, and the test signal detected by the residual noise detection means and filtered by the filter means. An identification means for identifying a model space transfer function of the filter means by comparing the test signal obtained by the Timing means for detecting that a predetermined time has elapsed from the predetermined time, and the identification means performs identification when the predetermined time has elapsed by the time counting means and when the accelerated traveling state is detected by the accelerated traveling state detection means. It is characterized by.

Further, as shown in FIG. 4, the active noise control device according to claim 4 inputs a reference signal corresponding to a control noise generation state to a control sound source through an adaptive filter means, and Model sound transfer function in which a residual sound detecting means detects a combined sound pressure of a sound pressure transmitted from the apparatus and a surrounding noise sound pressure, and the reference signal is a spatial transfer function between the control sound source and the residual noise detecting means. In the active noise control device, the filter coefficient of the adaptive filter is updated by the filter coefficient updating means based on the signal filtered by the filtering means and the residual noise detection signal. Acceleration traveling state detecting means for detecting a state, vehicle speed detecting means for detecting a vehicle speed,
A test signal is supplied to the control sound source and the filter means in place of the reference signal, and a test signal detected by the residual noise detection means is compared with a test signal filtered by the filter means to obtain a model of the filter means. Identifying means for identifying the space transfer function, and timing means for detecting that a predetermined time has elapsed since the identification by the identifying means, wherein the identifying means detects the lapse of a predetermined time by the timing means. Identification is performed when the vehicle speed detection value detected by the vehicle speed detection means is equal to or greater than a predetermined vehicle speed threshold value and the acceleration traveling state detection means detects the accelerated traveling state.

Here, it is desirable that the identification means performs the initial identification even at the time of starting the engine.

[0012]

In the active noise control device according to the first aspect, when the acceleration traveling state detecting means detects a predetermined acceleration traveling state (for example, when the rate of change of the engine speed becomes equal to or more than a certain set threshold). Since the model space transfer function is identified by the identification means, the noise can be large due to acceleration, so that the identification can be performed without giving the occupant a feeling of discomfort.

Further, in the active noise control device according to the second aspect, the vehicle speed detection value detected by the vehicle speed detection means is equal to or greater than a predetermined threshold value, and the predetermined acceleration traveling state is detected by the acceleration traveling state detection means. Since the identification means sometimes identifies the model space transfer function, the noise due to acceleration is further increased, so that the identification can be performed without giving the occupant any discomfort.

Further, in the active noise control apparatus according to claim 3 (or claim 4), a predetermined time has elapsed since the previous identification (or a predetermined time has elapsed since the previous identification, and the vehicle speed detection value is equal to or greater than the threshold value). In addition, when the acceleration traveling state detection means detects a predetermined acceleration traveling state, the identification means identifies the model space transfer function, so that excessive identification is suppressed.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 5 is a schematic configuration diagram showing one embodiment in which the present invention is applied to a vehicle equipped with a four-cylinder engine. In FIG. 5, reference numeral 1 denotes a vehicle body, and a four-cylinder engine 3 as a noise source is disposed in front of a vehicle compartment 2. Inside the cabin 2, a front seat 4F and a rear seat 4R are provided, and for example, a lower portion of the dashboard and a rear seat 4R.
The loudspeakers 5a and 5b, which also serve as control sound sources for outputting audio signals as control sound sources, are disposed behind the microphones, and microphones 6a, 6b and 6c as residual noise detecting means are respectively provided at the front, center and rear of the ceiling. Are arranged.

A crank angle sensor 7 is attached to the engine 3. The crank angle sensor 7 outputs a one-cycle sine wave signal X, for example, every one rotation of the crankshaft by 180 degrees. Each time the shaft rotates 15 degrees, an engine speed detection signal E _N composed of one sinusoidal signal is output. Further, the vehicle has a vehicle speed sensor 8 that detects a vehicle speed and outputs a pulse signal corresponding to the vehicle speed, and a white noise generator that generates white noise as a test signal for identification by a control signal CB from the controller 15. 9 are mounted.

Then, the signals are output from the microphones 6a to 6c.
Residual noise detection signal e₁~ E _ThreeIs controller 1
5 and the crank angle sensor 7
Angle detection signal X, engine speed detection signal E_N, Vehicle speed
Vehicle speed detection signal V, which is a digital signal of
White noise and ignition switch of noise generator 9
Switch 10 switch signal and starter switch 11 switch signal.
The switch signal is also input to the controller 15.

As shown in FIG. 6, the controller 15
The crank angle detection signal X and the white noise XW are input, and are input to the control signal C from the microcomputer 26.
An analog multiplexer 20 selected by A, an A / D conversion circuit 21 for A / D converting and outputting a selected output of the analog multiplexer 20, and a microphone 6
an amplifier 22a~22c for amplifying the residual noise detecting signals e ₁ to e ₃ of A～6c, A / D conversion circuit 23a for outputting the amplified output of the amplifiers 22a~22c A / D conversion
And ～23C, a waveform shaping circuit 24 to the engine rotational speed detection signal E _N and waveform shaping the pulse signal outputted from the crank angle sensor 7, the A / D converter circuit 21,23a~
23c conversion output, waveform shaping output of waveform shaping circuit 24,
Vehicle speed detection signal of the vehicle speed sensor 8, the microcomputer 26 switches the signal of the ignition switch 10 and starter switch 11 is input, loudspeaker 5a outputted from the microcomputer 26, 5b of the drive signal y _1, y ₂ D D / A conversion circuits 27a and 27b for converting and outputting A / A, and D / A conversion circuits 27a and 27b
27b and the white noise of the white noise generator 9 are input, and analog multiplexers 28a and 28b for selecting them by a control signal CA from the microcomputer 26, and amplify the analog signals output from the analog multiplexers 28a and 28b. Amplifiers 29a, 2 supplying the loudspeakers 5a, 5b
9b.

Here, the microcomputer 26 is normally
, The filter coefficient W which is sequentially updated _miBased on the reference signal
Calculation of the engine speed detection signal X as a signal
To drive signals y for loudspeakers 5a and 5b.
_1,y_TwoAdaptive digital filter processing to calculate
Microphone and speaker based on the
Model according to the number of combinations of spatial transfer functions between
With the filter coefficients corresponding to the model space transfer function
Processed reference signal r_km(See equations (6) and (7) below)
Digital filter processing for generating the
Processed reference signal r_kmAnd residual noise detection signal e₁ ~ E_ThreeWhen
In adaptive digital filter processing based on
Coefficient W_miTo the LMS (Least Mean Square) algorithm
When executing the filter coefficient update processing to be updated using
Then, the identification process is executed at a predetermined timing.

Here, the control principle of the microcomputer 26 will be described using a general formula. Now, the residual noise detection signals detected by the k-th microphones 6a to 6c are set to e _k
(n), k-th microphones 6a to 6c when there is no control sound (secondary sound) from loudspeakers 5a and 5b
Table transfer function H _miles in FIR (finite impulse response) function between but the residual noise detecting signals detected e _pt (n), and m-th loudspeaker 5a and 5b and the k-th microphone 6a~6c J (j = 0, 1,
2, ──I _c -1) is the filter coefficient corresponding to the term
_kmj ′, the engine speed detection signal X (n), the engine speed detection signal X (n), and the ith (i = 0, i = 0, i) of the adaptive digital filter that drives the m-th loudspeakers 5a and 5b. 1,2, when the coefficients of ─I _F -1) and W _mi, the following equation (2) is satisfied.

[0021] Here, each term with (n) is a sample value at sampling time n, and K is the microphone 6a
6c (three in this embodiment), M is the number of loudspeakers 5a and 5b (two in this embodiment), and I _C is FIR
The number of taps of the filter coefficients C _miles' expressed by the digital filter (filter order), a I _F is the number of taps of the filter coefficient W _mi represented in the adaptive digital filter (filter order).

In the above expression (2), “｛ΣW _mi · X (nj
-i)｝ ”(= y _m ) is the engine speed detection signal X
Represents the output when adaptive digital filter processing is performed, and
The term “{C _kmj ｛ΣW _mi ＸX (nji) は] indicates that the signal energy input to the m-th loudspeakers 5a and 5b is output as acoustic energy from these loudspeakers 5a and 5b, and the space transfer function in the vehicle compartment The signal at the time of reaching the k-th microphones 6a to 6c after C _km is shown. Further, the entire second term on the right side of “{C _kmj ｛ΣW _mi · X (nji)}” is the k-th microphone 6a Since the signals reaching to 6c are added for all speakers,
Represents the sum of secondary sounds reaching the k-th microphones 6a to 6c.

Next, an evaluation function J is placed as shown in the following equation (3). In this embodiment, the LMS algorithm is adopted,
A filter coefficient W _mi that minimizes the evaluation function J is obtained, and each filter coefficient W _mi of the adaptive digital filter processing is updated. The LMS algorithm, which is the steepest descent method, uses an n-th value W as a filter coefficient for adaptive digital filtering.
with _mi (n), calculates the gradient ∂J / ∂W _mi of mean square error, which was α multiplied seeking (n + 1) th value W _mi (n + 1), to reduce the value of the evaluation function J Calculation is performed as follows.

The equation for calculating the gradient ∂J / ∂W _{mi is given by} the following equation (3). Then, from the above equation (2), So, Here, the right side of equation (5) is In other words, the gradient of the evaluation function for the filter coefficient ∂J /
∂W _mi is Can be represented by

Therefore, the updating equation of the filter coefficient is given by the following equation (9) including the weight coefficient γ _k . Here, α is a convergence coefficient, which is related to the speed at which the adaptive digital filter processing converges optimally and the stability at that time.

As described above, the filter coefficient W _mi (n + 1) in the adaptive digital filter processing is determined by the microphone 6
a to 6c output residual noise detection signals e ₁ (n) to e
₃ (n) and the engine speed detection signal X (n) from the crank angle sensor 7 are sequentially updated in accordance with the LMS algorithm, so that the input residual noise detection signal e
Drive signals y ₁ (n) and y ₂ (n) minimizing ₁ (n) to e ₃ (n) are formed, and these are supplied to loudspeakers 5a and 5b, and control sounds output from these are output. This cancels out the noise in the passenger compartment 2.

Next, the operation of the above embodiment will be described with reference to the flowcharts of FIGS. The power of the entire system is turned on when the key switch is turned on, and the microcomputer 26 executes the timer interrupt processing shown in FIG. 7 every predetermined time (for example, 1 msec). The control signal CA by the initialization processing by the main program at power-on is set to "0", this analog multiplexer 28a, the drive signals y _1, y ₂ which are outputted from the microcomputer 26 by 28b is selected by At the same time, the count value T of the time counter for counting the elapsed time is cleared to “0”.

That is, in step S1, the switch signal of the ignition switch 10 is read, and it is determined whether or not the switch signal is on. This determination is for determining whether or not the engine 3 is rotating. When the ignition switch 10 is in the off state, it is determined that the engine is being stopped, and the timer interrupt processing is terminated as it is. When 10 is in the ON state, the process proceeds to step S2.

In step S2, a switch signal of the starter switch 11 is read, and it is determined whether or not the switch signal is on. This determination is for determining whether or not the engine is being started. When the starter switch 11 is on, the occupant does not feel uncomfortable even if the loud noise is performed at the time of the engine start and the identification process is performed. When the starter switch 11 is in the OFF state, it is determined that the engine is rotating after the start of the engine, and the process proceeds to step S3.

In step S3, the count value T of the time counter is incremented. Then, the process proceeds to step S4, where the engine speed detection signal from the crank angle sensor 7 is read, and the pulse interval time is measured or The number of pulses per unit time is counted to calculate an engine speed detection value _{NE (n)} , and then the process proceeds to step S5 to execute the previous processing from the calculated current engine speed detection value _{NE (n).} The engine speed change rate ΔN is calculated by dividing the value obtained by subtracting the engine speed detection value _{NE (n-1)} calculated at the time by the timer interrupt period τ.

Next, the routine proceeds to step S6, where it is determined whether or not the detected engine speed N _{E (n)} is _{equal to} or greater than a preset speed threshold N _ET for starting noise suppression control.
_{When E (n)} < _NET , the timer interrupt process is terminated as it is. When NE _(n) ≧ _NET , it is determined that the noise suppression control is to be started, and the process proceeds to step S7. .

In step S7, the count value T of the time counter is set to a threshold value T _T corresponding to a preset time.
Is determined, and if T <T _T , the process proceeds to step S8, where the normal noise suppression control process shown in FIG. 8 is executed, the timer interrupt process is terminated, and the predetermined main program is executed. returning to, the process proceeds to step S9 when it is T ≧ T _T.

In step S9, the vehicle speed detection signal of the vehicle speed sensor 8 is read, and the pulse interval time is measured or the number of pulses per unit time is counted to calculate the vehicle speed detection value V. Then, in step S10, migration and determines whether the vehicle speed detection value V is the vehicle speed threshold V _T more than a preset, when a V <V _T moves to the step S8, when a V ≧ V _T moves to step S11 I do.

In this step S11, step S11
5 engine speed change rate .DELTA.N calculated in it is determined whether the threshold value .DELTA.N _T above a preset, when a .DELTA.N <.DELTA.N _T, the process proceeds to step S8, .DELTA.N ≧ .DELTA.N
_If it is _T , the process proceeds to step S12 to execute the identification process of FIG. 9, and then proceeds to step S13 to clear the count value T of the time counter to "0", and then terminate the timer interrupt process and execute the predetermined process. Return to the main program.

The normal noise suppression control process is performed as shown in FIG.
First, in step S21, the residual noise detection signal e₁~ E_Three
And the reference signal X (n), and then to step S22.
Then, the digital filter processing corresponding to the equation (7) is performed.
And the filtered reference signal r_kmIs calculated,
Next, the process proceeds to step S23, where the calculated filtering process is performed.
Processed reference signal r_kmAnd residual noise detection signal e₁~ E_ThreeWhen
Based on the above, the filter coefficient update processing according to the equation (9) is performed.
Go to filter coefficient W_mi(n + 1), then
The filter coefficient W calculated in step S24_mi(n + 1)
Performs adaptive digital filter processing based on
Drive signal y for speakers 5a and 5b _1,y_TwoCalculate
And then proceeds to step S25 to calculate the calculated drive signal.
y_1,y_TwoIs output to the D / A conversion circuits 27a and 27b?
The normal noise suppression control process and the timer interrupt process.
And returns to the predetermined main program.

In the identification process, as shown in FIG. 9, first, in step S31, a control signal CA of "1" is output to the analog multiplexers 28a and 28b, and these inputs are sent to the white noise generator 9 side. Switch. Next, the process proceeds to step S32, where the control signal CB having the logical value “1” is set.
Is output to the white noise generator 9, which is activated, and then proceeds to step S 33.

In step S33, the residual noise detection signals e _{1 to} e ₃ from the microphones 6a to 6c are read, and the white noise XW from the white noise generator 9 is read. Then, the process proceeds to step S34. By subjecting the white noise XW to digital filter processing using the model space transfer function C _km 'as a filter coefficient,
Filtered white noise signals r _{1m to} r _3m (=
C _km ′ × XW), and each speaker 5a, 5
by adding the filtered white noise signal for b, and calculates the white noise signal r ₁ ~r ₃ which is filtered corresponding to the residual noise detecting signals e ₁ to e ₃ of each microphone 6 a to 6 c.

[0038] Then, the processing proceeds to step S35, the actual speakers 5a, 5b and white noise signal r ₁ ~ from the residual noise detecting signals e ₁ to e ₃ which includes a spatial transfer function is filtered between the microphone 6a~6c The difference ε _{1 to} ε ₃ between them is calculated by subtracting r ₃ . Next, the process proceeds to step S36, where the calculation of the following equation (13) is performed to calculate the filter coefficient C _km ′ (n + 1) of the digital filter processing in the next step S34, and the calculated filter coefficient C _km ′ After updating (n + 1), the flow shifts to step S37.

C _km ′ (n + 1) = C _km ′ (n) −α · ε _km (n) · X (ni) (13) This filter coefficient updating equation is a filter for digital filter processing. The evaluation function J of the coefficient C _km 'is placed as shown in the following equation (14), and a filter coefficient C _km ' (n + 1) that minimizes the evaluation function J is obtained by employing the LMS algorithm. J = E ｛ε _k (n) ² … (14) where E ｛is an expected value.

The filter coefficient C at time n_km'of
Value C_km'(N) is proportional to the value obtained by differentiating the evaluation function J, that is, the gradient.
Amount_km′ (N), the filter coefficient
C_km′ (N), the evaluation function J
Target filter coefficient C to be small _optApproaching. Concrete
In general, In the LMS algorithm, instead of the expected value, ε_k
(n) By using the instantaneous value of X (n-i) as it is,
(13) Filter coefficient C_km′ (N + 1)
You.

In step S37, the filter coefficient C _km '
The gradient (αε _k (n) XW (ni) of the evaluation function J with respect to the second term on the right side of the equation (13), that is, the filter coefficient, for updating
) Is equal to or less than a predetermined value ΔJ, and it is determined whether or not the evaluation function J has reached the target filter coefficient C _opt at which the evaluation function J becomes the minimum.
_{If k} (n) XW (ni) ≧ ΔJ, it is determined that the filter coefficient C _km ′ (n) has not reached the target filter coefficient C _opt , and the flow returns to step S33 to return to αε _k (n)
When XW (ni) <ΔJ, the target filter coefficient C
It is determined that identification has been completed by reaching _opt , and step S
38, the control signal CB having the logical value “0” is output to the white noise generator 9, and the white noise generator 9 is stopped. Then, the process proceeds to step S39, where the control signal CA having the “0” is outputted. To the analog multiplexer 28
a, and outputs the 28b, the drive signal y ₁ the input side, y ₂
The identification process is terminated from the side, and the process returns to the process of FIG.

Here, the processing of steps S5 and S11 in FIG. 7 and the crank angle sensor 7 correspond to the acceleration running state detecting means, and the processing of steps S3 and S7 in FIG. 7 correspond to the time measuring means. The processing in steps S9 and S10 and the vehicle speed sensor 8 correspond to the vehicle speed detecting means, and correspond to step S9 in FIG.
Step 12 corresponds to the filter means, step S13 corresponds to the filter coefficient updating means, and step S1
4 and S15 correspond to adaptive filter processing, and the processing of FIG. 9 corresponds to identification means.

Therefore, assuming that the key switch is off and the vehicle is parked, the controller 1
5 is shut off, and the execution of the noise suppression control process and the identification process is stopped. When the key switch is turned on from this state, energization of the controller 15 is started, and the controller 15 executes the processing of FIGS. At this time, when the ignition switch 10 is maintained in the off state, the engine 3 is stopped and no noise is generated. Therefore, when the timer interrupt processing of FIG. The normal noise suppression control process and the identification process are not executed since the loading process ends.

In this state, the ignition switch 10
Is turned on, and then the starter switch 11 is turned on, and the engine 3 is started. When the timer interrupt process of FIG. 7 is executed, the process proceeds to step S1 and step S1.
2 and the starter switch 11 is on, so that the process shifts to step S12 to execute the identification processing of FIG.

In this identification processing, first, the analog multiplexers 20, 28a and 28b are respectively switched to the white noise generator 9 side (step S31), and the white noise generator 9 is activated to generate the white noise signal XW (step S31). Step S32). As a result, the white noise signal XW is transmitted to the loudspeakers 5a, 5a via the analog multiplexers 28a, 28b and the amplifiers 29a, 29b.
5b, and white noises are output from the loudspeakers 5a and 5b, which are collected by the microphones 6a to 6c, and are collected by the microphones 6a to 6c.
6c output residual noise detection signals e _{1 to} e _{3, which} are converted into digital values by A / D converters 23a to 23c and input to the microcomputer 26.

Therefore, in the microcomputer 26, the output from the white noise generator 9 is input to the A / D converter 25 via the analog multiplexer 20, and
The white noise signal XW converted into a digital value by the A / D converter 25 is subjected to digital filter processing using the model space transfer function C _km 'as a filter coefficient, and the residual noise of the microphones 6a to 6c filtered is detected. calculating a white noise filtered signal r ₁ ~r ₃ corresponding to the signal e ₁ to e ₃ (step S34). Then
Deviations ε _{1 to} ε between the input residual noise detection signals e _{1 to} e ₃ and the calculated white noise filter signals r _{1 to} r _3
3 (step S35), and these deviations ε _{1 to} ε ₃
By performing the operation described above on the basis (13) of the 'updating the filter coefficient C _miles the operation for the evaluation function J' filter coefficients C _miles in the digital filter processing of the next step S34 gradient of The process is repeatedly executed until the evaluation function reaches the target filter coefficient C _opt at which the evaluation function becomes the minimum, and the white noise generator 9 is stopped when the evaluation function reaches the target filter coefficient C _opt (step S38). 20 with switches on the reference signal X side, and analog multiplexer 28a, 28b was allowed to return to the drive signal y _1, y ₂ side (step S39) to terminate the identification process.

As described above, by performing the identification processing,
The model space transfer function C _km ′ in the digital filter processing in step S22 in the normal noise suppression control processing of FIG. 8 in the microcomputer 26 is the space transfer function C between the actual loudspeakers 5a and 5b and the microphones 6a to 6c. _km is approximately the same. From this state,
When the engine 3 is started and turned into a rotating state, the starter switch 11 is turned off. Therefore, when the timer interrupt processing of FIG. 7 is executed, the processing proceeds to step S3 via steps S1 and S2, and the time counter Is incremented and the engine speed detection value N _{E (n)} is incremented.
And the engine speed change rate ΔN is calculated (step S
The process proceeds from step S4) to step S6, and when the engine speed detection value N _{E (n)} becomes _{equal to} or greater than a predetermined threshold N _ET , the process proceeds from step S6 to step S8 via step S7, and proceeds to step S8 in FIG. Execute noise suppression control processing.

Therefore, the microcomputer 26 sequentially updates the filter coefficient _Wmi in the adaptive digital filter processing according to the LMS algorithm, and
The drive signals y _{1 and} y ₂ for the loudspeakers 5 a and 5 b are calculated so that
7a, 27b and analog multiplexers 28a, 28
b to the loudspeakers 5a and 5b. Therefore, the drive signals y _1, y from the loudspeakers 5a, 5b
_The control sound corresponding to ₂ is generated, and this interferes with the noise, so that the mute control is performed so that the residual noise detection signals e _{1 to} e ₃ of the microphones 6a to 6c are minimized.

After that, until the count value T of the time counter reaches the threshold value T _T , the normal noise suppression control processing of FIG. 8 is continuously executed, but when the count value T reaches the threshold value T _T , The process proceeds from step S7 to step S9,
The vehicle speed detection value V at that time is calculated, and then step S1
0, and the vehicle speed detection value V becomes equal to the predetermined vehicle speed threshold V
_If it is less than _T , the process proceeds to step S8.
Continuing normal noise suppression control process, when the vehicle speed detection value V is greater than or equal to vehicle speed threshold value V _T is determined whether the engine speed change rate .DELTA.N is the threshold value .DELTA.N _T above a preset proceeds to step S11 When ΔN <ΔN _T , the process proceeds to step S8, so that the normal noise suppression control process is continued. When ΔN ≧ ΔN _T , the noise level in the passenger compartment 2 is large, and the identification process makes it difficult for the occupant. It is determined that no pleasure is given, and the process proceeds to step S12 to execute the above-described identification processing.

As described above, according to the above-described embodiment, at the time of starting the engine, the initial identification processing for matching the model space transfer function C _km ′ with the real space transfer function C _km is performed, and after the initial identification processing is performed, the predetermined identification processing is performed. whenever the elapsed time since executing the identification process in a state where the vehicle speed detecting value V is preset threshold V _T or more and the engine speed change rate .DELTA.N is greater than the threshold value .DELTA.N _T, without discomfort to the occupant, Since the identification processing is performed at predetermined intervals, the model space transfer function C _km '
And the real space transfer function C _km can be reliably prevented from deteriorating the noise suppression effect.

In the above embodiment, the execution timing of the identification process is determined after a predetermined time has elapsed since the identification process was performed.
The case where the vehicle speed detection value V is set when the vehicle speed detection value V is equal to or more than the set threshold value V _T and the engine speed change rate ΔN is equal to or more than the threshold value ΔN _T has been described. However, the present invention is not limited to this.
The identification process, the vehicle may be executed every a predetermined acceleration state is or vehicle speed detecting value V is equal to or more than the threshold V _T every a predetermined acceleration state.

In the above embodiment, the case where a loudspeaker is applied as a control sound source has been described. However, the present invention is not limited to this, and a vibrator can be applied, and a microphone as a residual noise detecting means can be used. Also, an acceleration vibration sensor can be applied. Further, the number of loudspeakers and microphones to be installed is not limited to the above embodiment, and may be any number equal to or more than one.

Further, in each of the above embodiments, the case where the engine noise is suppressed has been described. However, the present invention is not limited to this. The road noise can be suppressed by detecting the vibration input from the road surface to the wheel, or the window noise can be suppressed. Wind noise can be suppressed by detecting the vibration of the glass, and these complex sounds can also be suppressed. In each of the above embodiments, the case where the microcomputer 26 performs the adaptive digital filter processing and the digital filter processing of the filter coefficient according to the model space transfer function has been described. Filters can also be applied.

Further, in each of the above embodiments, the case where the present invention is applied to a vehicle has been described. However, the present invention is not limited to this, and can be applied to the case of reducing the noise in the cabin of an aircraft.

[0055]

As described above, according to the active noise control device of the first aspect, the model space transfer function which models the actual space transfer function between the control sound source and the residual noise detecting means is used. When active noise control is performed, the identification process for matching the model space transfer function to the actual space transfer function is performed when a predetermined acceleration state is detected by the acceleration state detection means. Identification can be performed when the size is large, and the occupants do not feel uncomfortable, and the identification processing frequency can be increased, so that the noise suppression effect due to the difference between the model space transfer function and the actual space transfer function is reduced. Can be obtained.

According to the active noise control device of the second aspect, the identification process is performed when the vehicle speed is equal to or higher than the set vehicle speed and the vehicle is in an acceleration state. The identification process can be performed without causing the occupant to feel discomfort at all. Further, according to the active noise control device according to claim 3 or 4, when a predetermined acceleration state is reached after a predetermined time has elapsed since the previous identification processing, or when the vehicle speed is equal to or higher than the set vehicle speed and the predetermined speed, Since the identification processing is performed when the acceleration state is reached, it is possible to obtain an effect that the identification processing frequency is set to an appropriate state and excessive identification processing can be prevented.

Further, according to the active noise control device of the fifth aspect, since the identification process is performed at the time of starting the engine, the identification process can be performed while reliably preventing the occupant from feeling uncomfortable. The effect is obtained.

[Brief description of the drawings]

FIG. 1 is a functional block diagram corresponding to claim 1 of the present invention.

FIG. 2 is a functional block diagram corresponding to claim 2 of the present invention.

FIG. 3 is a functional block diagram corresponding to claim 3 of the present invention.

FIG. 4 is a functional block diagram corresponding to claim 4 of the present invention.

FIG. 5 is a schematic configuration diagram of a first embodiment of the present invention.

FIG. 6 is a block diagram of a controller according to the first embodiment.

FIG. 7 is a flowchart of the first embodiment.

FIG. 8 is a flowchart illustrating a normal noise suppression control process according to the first embodiment.

FIG. 9 is a flowchart illustrating an identification process according to the first embodiment.

[Explanation of symbols]

 2 Cabin 3 Engine 5a, 5b Loudspeaker 6a-6c Microphone 7 Crank angle sensor 8 Vehicle speed sensor 9 White noise generator 10 Ignition switch 11 Starter switch 15 Controller 20 Analog multiplexer 26 Microcomputer 28a, 28b Analog multiplexer

Claims (5)

(57) [Claims] 1. A reference signal according to a control noise generation state is input to a control sound source through an adaptive filter means, and a combined sound pressure of a sound pressure transmitted from the control sound source and a surrounding sound noise pressure is used as a residual noise. The detection means detects the reference signal and the residual noise detection signal into a signal filtered by a filter means using a model space transfer function obtained by modeling a space transfer function between the control sound source and the residual noise detection means as a filter coefficient. In the active noise control device, the filter coefficient of the adaptive filter is updated by the filter coefficient updating means based on the acceleration traveling state detecting means for detecting an acceleration traveling state of the vehicle, and the acceleration traveling state is detected by the acceleration traveling state detecting means. When a state is detected, a test signal is supplied to the control sound source and the filter means instead of the reference signal, and a test signal detected by the residual noise detection means is provided. An active noise control device comprising: an identification unit configured to compare a test signal and a test signal filtered by the filter unit to identify a model space transfer function of the filter unit. 2. A reference signal corresponding to a control noise generation state is input to a control sound source through an adaptive filter means, and a combined sound pressure of a sound pressure transmitted from the control sound source and a surrounding sound pressure is used as a residual noise. The detection means detects the reference signal and the residual noise detection signal into a signal filtered by a filter means using a model space transfer function obtained by modeling a space transfer function between the control sound source and the residual noise detection means as a filter coefficient. In an active noise control device that updates the filter coefficient of the adaptive filter based on the filter coefficient updating means based on the acceleration traveling state detection means for detecting an acceleration traveling state of the vehicle, a vehicle speed detection means for detecting a vehicle speed, When the vehicle speed detection value detected by the vehicle speed detection means is equal to or higher than a predetermined vehicle speed threshold value and the acceleration traveling state detection means detects the acceleration traveling state, the control sound source and the control sound source are detected. And supplying a test signal to the filter means in place of the reference signal, and comparing the test signal detected by the residual noise detection means with the test signal filtered by the filter means to transmit the model space of the filter means. An active noise control device, comprising: identification means for identifying a function. 3. A reference signal according to a control noise generation state is input to a control sound source via an adaptive filter means, and a combined sound pressure of a sound pressure transmitted from the control sound source and a surrounding sound noise pressure is used as a residual noise. The detection means detects the reference signal and the residual noise detection signal into a signal filtered by a filter means using a model space transfer function obtained by modeling a space transfer function between the control sound source and the residual noise detection means as a filter coefficient. In the active noise control device, the filter coefficient of the adaptive filter is updated by the filter coefficient updating means based on the acceleration running state detecting means for detecting the acceleration running state of the vehicle, and A test signal is supplied in place of the signal, and the test signal detected by the residual noise detection means is compared with the test signal filtered by the filter means. And an identification unit for identifying a model space transfer function of the filter unit, and a timer unit for detecting that a predetermined time has elapsed since the identification unit performed the identification. An active noise control device characterized in that when a predetermined period of time has elapsed, the acceleration running state detecting means detects the acceleration running state. 4. A reference signal according to a control noise generation state is input to a control sound source through an adaptive filter means, and a combined sound pressure of a sound pressure transmitted from the control sound source and a surrounding sound pressure is used as a residual noise. The detection means detects the reference signal and the residual noise detection signal into a signal filtered by a filter means using a model space transfer function obtained by modeling a space transfer function between the control sound source and the residual noise detection means as a filter coefficient. In an active noise control device that updates the filter coefficient of the adaptive filter based on the filter coefficient updating means based on the acceleration traveling state detection means for detecting an acceleration traveling state of the vehicle, a vehicle speed detection means for detecting a vehicle speed, A test signal is supplied to the control sound source and the filter means in place of the reference signal, and the test signal detected by the residual noise detection means is filtered by the filter means. Identification means for comparing the test signal subjected to the filter processing to identify a model space transfer function of the filter means, and timing means for detecting that a predetermined time has elapsed since identification by the identification means. The identification means detects the elapse of a predetermined time by the timing means,
An active noise control device characterized in that identification is performed when a vehicle speed detection value detected by the vehicle speed detection means is equal to or higher than a predetermined vehicle speed threshold and an acceleration traveling state detection means detects an acceleration traveling state. 5. The active noise control device according to claim 1, wherein said identification means is configured to perform identification even when the engine is started.