JP2929875B2 - 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 is applied to a vehicle, and reduces noise by causing a control sound emitted from a control sound source to interfere with noise transmitted between a vehicle body and a road surface as a noise source. More specifically, the present invention relates to an active noise control device including an adaptive digital filter having a variable filter coefficient for generating a control sound, and adaptive processing means for updating a filter coefficient of the adaptive digital filter so as to reduce noise in space. In the above, the divergence phenomenon and the sound increase phenomenon of the control system can be effectively solved.

[0002]

2. Description of the Related Art Conventional active noise control devices include those described in British Patent No. 2,149,614 and Japanese Patent Publication No. 1-501344. These conventional devices are, for example, noise reduction devices applied to a closed space such as a cabin of an aircraft, and microphones installed at a plurality of positions in such a closed space to detect sound pressure, and a microphone installed in the closed space. A plurality of loudspeakers that generate control sounds are provided, and based on the noise generation state of the noise source, the loudspeakers generate control sounds having a phase opposite to the noise transmitted to the closed space to cancel the noises.

[0003] As a method of generating a control sound emitted from a loudspeaker, PROCEEDINGS OF THE IEEE, VOL.
63 PAGE 1692, 1975, “ADAPTIVE NOISE CANSELLATION:
PRINCIPLES AND APPLICATIONS ”
DROW LMS 'algorithm is applied to multiple channels. The contents are described in a paper by the inventor of the above patent, “A MULTIPLE ERROR LMS ALGORITHM AND
ITS APPLICATION TOTHE ACTIVE CONTROL OF SOUND AND
VIBRATION ”, IEEE TRANS.ACOUST., SPEECH, SIGNAL PRO
CESSING, VOL. ASSP-35, PP. 1423-1434, 1987.

That is, the LMS algorithm is one of suitable algorithms for updating the filter coefficient of the adaptive digital filter, and is, for example, a so-called Filter.
In the ed-X LMS algorithm, a filter representing a transfer function from a loudspeaker to a microphone is set for all combinations of loudspeakers and microphones, and a reference signal representing a noise generation state of a noise source is processed by the filter. The filter coefficient of the adaptive digital filter provided for each loudspeaker is updated based on the calculated value and the residual noise detected by each microphone.

However, in such a conventional active noise control device, the filter coefficient of the adaptive digital filter is determined based on a reference signal indicating the noise generation state and a residual noise signal indicating the residual noise in the control space. Because of the update configuration, if there is a temporary large-level input as a reference signal or residual noise signal, the filter coefficient of the adaptive digital filter will fluctuate significantly, which may cause divergence or increased noise in the control system. There is a problem that there is.

That is, when the filter coefficient of the adaptive digital filter fluctuates due to the influence of a temporary large input, even if a standard level reference signal or a residual noise signal is input after the large input, it becomes unnecessary. Loud control sounds are generated. As a conventional technique capable of preventing such a problem, Japanese Patent Application No. 3-176 previously proposed by the present applicant has been proposed.
980, there is provided a means for resetting the value of the filter coefficient of the adaptive digital filter to zero when a residual noise signal of a predetermined level or more is input. This avoids the use of adaptive digital filter coefficients that fluctuate greatly due to sudden large input, and reduces noise when the signal driving the control sound source exceeds a predetermined level and divergence is predicted. The control was stopped.

[0007]

However, in the above-mentioned prior art, since the filter coefficient of the adaptive digital filter is reset to zero when a large input is received, for example, the period generated from the internal combustion engine is reduced. When the number of taps (the number of filter coefficients) of the adaptive digital filter is small, as in the case of an active noise control device that reduces dynamic noise, the filter coefficients converge to the optimal value in a short time, so there are practical problems. However, if the number of taps of the adaptive digital filter is large, as in the case of an active noise control device that reduces random noise such as road noise transmitted to the vehicle interior, it is difficult to converge to an optimum value. It takes time, and after resetting to zero, noise cannot be reduced for a relatively long time, and in some cases it may diverge. There is a condition. That is, since the filter coefficient of the adaptive digital filter is changed according to the temporary large input, the subsequent control is adversely affected, and the noise reduction effect such as divergence and increased sound is reduced.

[0008] In addition, the above-mentioned prior art has a configuration in which the generation of the control sound itself is stopped when the control system has a tendency to diverge, so that the active noise control device for reducing the noise generated from the internal combustion engine is used. There is no particular problem in practice because large inputs rarely occur if they are present.However, an active noise control device that reduces noise such as road noise, which generates large inputs relatively frequently during actual driving, is used. In such a case, the control is frequently stopped, and the noise reduction effect may be significantly reduced.

SUMMARY OF THE INVENTION The present invention has been made in view of such unresolved problems of the prior art, and provides an active noise control device capable of more effectively solving a problem with a large input. With the goal.

[0010]

In order to achieve the above object, the invention described in claim 1 is applied to a vehicle, and includes a wheel and a vehicle.
A control sound source capable of generating a control sound in a vehicle compartment in which noise is transmitted from between road surfaces, a noise generation state detecting means for detecting a noise generation state of the noise source and outputting the noise generation state as a reference signal, and at a predetermined position in the space. Residual noise detection means for detecting residual noise and outputting the same as a residual noise signal; an adaptive digital filter having variable filter coefficients; and a drive for generating a signal for driving the control sound source by filtering the reference signal with the adaptive digital filter. An active noise control device comprising: a signal generating unit; and an adaptive processing unit that updates a filter coefficient of the adaptive digital filter so that noise in the space is reduced based on the reference signal and the residual noise signal. A large input for directly or indirectly detecting that an input signal to the adaptive processing means is a large input exceeding a predetermined threshold value. Output means; update processing stopping means for stopping update processing of the filter coefficient of the adaptive digital filter by the adaptive processing means when the large input detection means detects the large input; and a filter coefficient setting holding means for setting or holding the filter coefficient of the adaptive digital filter unaffected value of the large input when the process was stopped, the
Predetermined update after update processing stop means stops update processing
Release the suspension of the update process after the suspension time has elapsed
And updating process resumption means to resume the update process, the formed, before
The update stop time is made variable according to the vehicle speed.

The invention according to claim 2 is applied to a vehicle.
To control the cabin where noise is transmitted between the wheels and the road surface
A control sound source capable of generating sound and a noise generation state of the noise source
Detection means for detecting noise and outputting as a reference signal
Detecting residual noise at a predetermined position in the space and
A residual noise detecting means for outputting as a background noise signal;
An adaptive digital filter having variable data coefficients, and the reference signal
By the adaptive digital filter
Drive signal generation means for generating a signal for driving a control sound source
And, based on the reference signal and the residual noise signal,
The adaptive digital filter is designed to reduce noise in the space.
Adaptive processing means for updating filter coefficients of the filter.
In the active noise control device, the adaptive processing means
Check that the input signal is a large input that exceeds the predetermined threshold.
Large input detection means for detecting, and the large input detection means
When a large input is detected, the adaptive processing means
Stop updating of filter coefficient of digital filter
Update processing stopping means, and the update processing stopping means
When the update process is stopped, the adaptive digital filter
Filter coefficient to a value not affected by the large input
And a filter coefficient setting holding means for setting or holding
In addition, the large input detecting means is provided between the vehicle body and the road surface.
A distance detecting means for detecting a distance, the distance detecting means
Input signal to the adaptive processing means according to the detection result of
Indirect detection of large input exceeding the threshold
I did it. According to a third aspect of the present invention, in accordance with the second aspect of the present invention, the updating by the updating process stopping means is performed.
Update processing restart to cancel the processing stop and restart the update processing
Opening means were provided .

[0012] The invention described in claim 4 is the above-described claim.
In the invention according to the third aspect, the updating process resuming means includes an adaptive process
Update when the input signal to the means falls below a predetermined threshold
New processing is restarted .

[0013] Further, according to a fifth aspect of the present invention, in the fourth aspect of the present invention, the update processing resuming means includes an update processing restart means.
When a predetermined update is stopped after the update stop means stops the update process
The update process is restarted after a lapse of time . According to a sixth aspect of the present invention, in the fifth aspect of the invention, the predetermined update suspension time is variable .

According to a seventh aspect of the present invention, in the first to sixth aspects, the filter coefficient setting is performed.
The constant holding means is a filter coefficient of the adaptive digital filter.
To the value at the time when the update process stopping means stopped the update process.
To carry it . According to an eighth aspect of the present invention, in the first to sixth aspects, the filter coefficient setting is performed.
The holding means is a filter coefficient of the adaptive digital filter.
To the value before the update process stop means stopped the update process.
I set it .

The invention according to claim 9 is suitable for a vehicle.
Control the cabin where noise is transmitted between the wheels and the road surface.
A control sound source capable of generating sound, and the noise generation state of the noise source
For detecting the noise generation state that detects the state and outputs it as a reference signal
And detecting the residual noise at a predetermined position in the space.
A residual noise detecting means for outputting as a residual noise signal;
An adaptive digital filter with variable filter coefficients and the reference signal
Signal by the adaptive digital filter
Drive signal generating means for generating a signal for driving the control sound source
And, based on the reference signal and the residual noise signal,
The adaptive digital filter is designed to reduce noise in the space.
Adaptive processing means for updating filter coefficients of the filter.
In the active noise control device, the adaptive processing means
Check that the input signal is a large input that exceeds the predetermined threshold.
A large input detection means for detecting directly or indirectly;
When the input detection means detects the large input, the adaptive processing
Filter of the adaptive digital filter by means of logical means
Update processing stopping means for stopping the number of update processing;
Predetermined update stop after processing stop means stops update processing
After the time has elapsed, release the suspension of the update process and update
Update processing restart means for restarting the processing.
The new stop time is variable according to the vehicle speed . In addition,
The invention according to claim 10 is applied to a vehicle, and includes a wheel and a road surface.
Control that can generate control sound in the cabin where noise is transmitted from between
A sound source, and a reference signal for detecting a noise generation state of the noise source.
And a noise generation state detecting means for outputting the noise in the space.
Detects residual noise at a fixed position and outputs it as a residual noise signal.
Residual noise detection means and adaptive data with variable filter coefficients.
A digital filter and the adaptive signal
Drive the control sound source by filtering with a filter
Drive signal generating means for generating a signal, the reference signal and
Noise in the space is reduced based on the residual noise signal.
So that the filter coefficient of the adaptive digital filter is
Active noise control device comprising: an adaptive processing means for updating
Wherein the input signal to said adaptive processing means has a predetermined threshold
Large input detection method to detect large input exceeding
Stage and the large input detecting means detects the large input.
The adaptive digital filter by the adaptive processing means.
Update stop means for stopping the filter coefficient update processing
And the large input detecting means includes a vehicle body and
Has a distance detecting means that detect the distance between the road surface, the distance
Input signal to adaptive processing means according to the detection result of detection means
Is a large input that exceeds a predetermined threshold.
Detected .

[0016] Further, according to an eleventh aspect of the present invention, in the ninth aspect of the present invention, the large input detecting means is provided near the vehicle.
The input signal to the adaptive processing means is
Indirect detection of large input exceeding a certain threshold
I did it. The invention of claim 12, wherein, in the active noise control system of the upper Symbol claim 11, Dainyuu
Detecting means for detecting a distance between the vehicle body and the road surface;
Means, adapted according to the detection result of this distance detecting means
Large input when the input signal to the processing means exceeds a predetermined threshold
Is detected indirectly .

According to a thirteenth aspect of the present invention, in the first to twelfth aspects of the invention, the predetermined threshold value as a reference for determining whether or not a large input is made variable. According to a fourteenth aspect of the present invention, in the thirteenth aspect, an average value of the input signal to the adaptive processing means within a predetermined time is set as a predetermined threshold value.

[0018]

According to the first aspect of the present invention, the drive signal generating means generates a noise generated between a wheel as a noise source and a road surface.
Since a reference signal indicating the state of (road noise) generation is filtered by an adaptive digital filter to generate a signal for driving the control sound source, a control sound having a correlation with noise is generated from the control sound source. Since the filter coefficient of the adaptive digital filter does not always converge to the optimum value, it cannot be said that the noise is necessarily canceled by the control sound.

[0019] However, the adaptive processing means, so the noise in the passenger compartment is to update the filter coefficients of the adaptive digital filter so as to reduce the basis of the reference signal and the residual noise signals,
Since the filter coefficients of the adaptive digital filter in accordance with the control progresses converges toward the optimal value, become the noise is canceled by the control sound generated from the control sound source, the noise in the passenger compartment (road noise) is reduced .

For example, when a large noise is generated temporarily due to a sudden phenomenon occurring in the noise source, or when the residual noise detecting means suddenly detects a large residual noise, the large input detecting means , Directly or indirectly detects that the reference signal or the residual noise signal input to the adaptive processing means is a large input exceeding a predetermined threshold value. Here, directly detecting the large input means that the reference signal or the residual noise signal input to the adaptive processing means is directly compared with a predetermined threshold value to determine whether the input is a large input. To do. In addition, indirect detection of a large input means monitoring other signals correlated with the signal input to the adaptive processing means and phenomena directly affecting the signal input to the adaptive processing means. Is used to determine whether the reference signal or the residual noise signal input to the adaptive processing means is a large input.

When the large input detecting means directly or indirectly detects that the input signal to the adaptive processing means is a large input exceeding a predetermined threshold value, the updating processing stopping means makes the adaptive processing means Since the update processing of the filter coefficient of the adaptive digital filter is stopped, the value of the filter coefficient of the adaptive digital filter is prevented from largely fluctuating due to the temporary large input as described above.

Further, since the filter coefficient setting and holding means sets or holds the filter coefficient of the adaptive digital filter to a value which is not affected by a large input, even if the drive signal generating means subsequently generates a drive signal, Since the drive signal is generated by the adaptive digital filter which is not affected by the large input, generation of an unnecessarily large control sound is prevented.

Here, an adaptive digital filter which is not affected by a large input differs depending on a method of detecting a large input. For example, when a large input and be able to advance detect that there is, it can be detected before the filter coefficient of the adaptive digital filter even larger input is inputted to the adaptive processing means is updated, according to claim 7, wherein As in the present invention, if the filter coefficient setting holding unit holds the value at the time of stopping the update processing, that is, the filter coefficient of the last adaptive digital filter, the filter coefficient of the adaptive digital filter is affected by a large input. Value is not held.

[0024] However, in the case that a large input is detected, such as after the filter coefficient of the adaptive digital filter is updated influenced by the large input, as in the invention of claim 8, the filter coefficient setting If the holding unit sets the value before the update process is stopped, that is, the filter coefficient of the adaptive digital filter set in the process several steps before, the filter coefficient of the adaptive digital filter is not affected by the large input. It is set to the value.

Further, the processing contents of the filter coefficient setting and holding means are not limited to the invention described in claim 7 or 8 , and the point is that the filter coefficient of the adaptive digital filter is affected by a large input. What is necessary is just to set or hold to the value which is not. Therefore, when a large input is detected, the filter coefficient of the adaptive digital filter may be set to a predetermined value. In addition,
In the active noise control apparatus according to claim 1,
Reference signal and residual noise signal when passing over unevenness on the road
Large input occurs, but once it reaches a high level
The decay time of residual noise tends to be shorter for high-frequency components.
And the ratio between the high-frequency and low-frequency components of the residual noise
Is roughly determined by the speed of the vehicle as it passes over bumps and dips on the road surface.
You. Therefore, the predetermined update stop time is variable according to the vehicle speed.
(For example, the higher the vehicle speed, the longer the update stop time
(By shortening), large input affects update process
Is reliably prevented and there is no effect of large input
In some situations, the filter coefficients of the adaptive digital filter
Updated to converge towards the optimal value.

On the other hand, the invention according to claim 2 also corresponds to the above-described claim.
It has substantially the same configuration as the invention described in 1, but is different
The point is that there is no update processing restart means
And that the configuration of the platform input detection means is further limited
is there. That is, the invention according to claim 2 is a vehicle
Level of road noise generated between both wheels and road surface
It is noted that
Therefore, based on road conditions near the vehicle,
The presence or absence of generation of force is detected indirectly.
More specifically, the level of road noise
Since it is roughly determined by the size of the upper unevenness, the distance
According to the distance between the vehicle body and the road surface detected by the separation detecting means,
It is easy to confirm that the input signal to the adaptive processing means is large.
Detect indirectly in advance.

[0027]

According to the third aspect of the present invention, the update processing restarting means cancels the update processing stoppage by the update processing stop means and restarts the update processing. After the detection and the update processing stopping means stop the update processing, the filter coefficients of the adaptive digital filter are updated again. Therefore, even once the updating process is stopped, the value of the filter coefficient of the adaptive digital filter is not updated at all and is not kept at a constant value.

According to the fourth aspect of the present invention, the update processing restart means restarts the update processing when the input signal to the adaptive processing means falls below a predetermined threshold value.
The update processing of the filter coefficient by the adaptive processing means is stopped when the input signal exceeds a predetermined threshold,
It will be executed only when it is below. Therefore, the filter coefficient of the adaptive digital filter fluctuates only under the influence of the normal-level input signal below the predetermined threshold value.

On the other hand, in the invention according to claim 5 , the update processing restart means restarts the update processing after a predetermined update stop time has elapsed since the update processing was stopped. Although the update process is restarted regardless of the above, generally a large input is a temporary phenomenon, so if the predetermined update stop time is an appropriate value, the level of the input signal and the like are not constantly monitored. Even so, the influence of the large input is prevented from affecting the update processing.

In particular, when the predetermined update stop time is variable as in the invention according to claim 6 , the predetermined update stop time is changed according to the frequency of occurrence of large input, the decay time of high-level residual noise, and the like. by adjusting the stop time, even if no constantly monitors the level of the input signal is the influence of the large input Ru is reliably prevented from reaching the updating process.

On the other hand, as in the invention according to the ninth to twelfth aspects, the same large input detection as in the first aspect of the invention is provided.
If it has at least a means and an update processing stopping means,
Adaptive digital filter fill under the influence of large input
At least prevents the coefficient from fluctuating significantly.
Re that.

The predetermined threshold value, which is used as a reference for determining whether or not there is a large input, differs depending on the use condition of the active noise control device. For example, when traveling on a pavement road, the input may be considered as a large input, but when traveling on a mountain road, the input may be regarded as a normal level input. Therefore, if the predetermined threshold value is made variable as in the invention of claim 13, it becomes possible to set an appropriate threshold value in accordance with the use condition of the active noise control device.

In particular, when the average value of the input signal within a predetermined time period is set as the predetermined threshold value, the lower threshold value can be set when the level of the input signal is low. If the input signal level is high, a higher threshold value is set.

[0035]

Embodiments of the present invention will be described below with reference to the drawings. Figure 1 is a diagram showing an overall configuration of a first embodiment of the present invention, this embodiment reduces the load noise is transmitted to the noise source or al car chamber 6 between the road surface and the wheel 2a~2d The present invention is applied to an active noise control device 1 for achieving the above.

First, the structure will be described. The vehicle body 3 is supported by suspensions interposed between the vehicle body 3 and the front wheels 2a, 2b, the rear wheels 2c, 2d and the wheels 2a to 2d. The vehicle shown in FIG. 1 is a so-called front-engine front-wheel drive vehicle in which front wheels 2a and 2b are rotationally driven by an engine 4 arranged in the front part of the vehicle body 3. Acceleration sensors 5a, 5b, 5c and 5d as noise generation state detecting means are attached to each of the suspensions interposed between the wheels 2a to 2d and the vehicle body 3, and load sensors input from the road surface are provided. Reference signal x _k (k = 1 to K: acceleration signal corresponding to noise: In this embodiment, K =
4) is supplied to the controller 10.

A loudspeaker 7a, 7b, 7c as a control sound source is provided in a cabin 6 as a space in the vehicle body 3.
And 7d are front seat S _1, S ₂ and a rear seat S _3, S
₄ are arranged at door portions facing each other. In addition, the head restraint position of the seat S ₁ to S _4, and a microphone 8a~8h as residual noise detecting means, are respectively disposed two by two, these microphones 8
a to 8h are residual noise signals e _{1 to} e ₈ measured as sound pressures
Is supplied to the controller 10.

Then, the controller 10 controls the reference signal x _k supplied from the acceleration sensors 5a to 5d and the residual noise signals e _{1 to} e supplied from the microphones 8a to 8h.
₈ to execute loudspeakers 7a to 7d such that control sounds for canceling road noise transmitted into the cabin 6 are emitted from the loudspeakers 7a to 7d. and outputs a drive signal y ₁ ~y _4.

As shown in FIG. 2, the controller 10
A / D converters 11a to 11d for converting reference signals x _k supplied from acceleration sensors 5a to 5d into digital values
When a digital filter 12 the reference signal x _k which has been converted into a digital value by the A / D converter 11a~11d is inputted, the filter coefficient variable of the adaptive digital filter 13 which is also the reference signal x _k is inputted, A / D converters 15a to 15h for converting the residual noise signals e _{1 to} e ₈ supplied from the microphones 8a to 8h and amplified by the amplifiers 14a to 14h into digital values, and processed signals filtered by the digital filter 12. a microprocessor 16 for executing predetermined arithmetic processing based on r _klm and the residual noise signals e _{1 to} e ₈ converted into digital values by the A / D converters 15a to 15h to update the filter coefficients of the adaptive digital filter 13 And the drive signals y _{1 to} y ₄ output from the adaptive digital filter 13.
D / A converter 1 which converts into analog values and supplies the analog values to amplifiers 18a to 18d for driving loudspeakers 7a to 7d
7a to 17d.

Here, the digital filter 12 is a digital filter C ＾ _lm (l = 1, 2, 2) in which a transfer function between the loudspeakers 7a to 7d and the microphones 8a to 8h is modeled in the form of a finite impulse response function. …, L,
m = 1, 2,..., M) is M (in this embodiment, M =
4) for all combinations (L × M) of the loudspeakers 7a to 7d and L (L = 8 in this embodiment) microphones 8a to 8h, and outputs the reference signal x _k to the digital filters C _生成 Generate and output a value r _klm filtered by _lm .

On the other hand, the adaptive digital filter 13
Quasi-signal x_kAnd the number of loudspeakers 7a to 7d
K × M filter coefficient variable adaptive digital filter
Ruta W_kmAnd the reference signal x_kThe adaptive di
Digital filter W_kmBy filtering with
Motion signal y₁~ Y_FourGenerate and output And micro
The processor 16 receives the signal supplied from the digital filter 12.
Processing signal r_klmAnd from the microphones 8a to 8h
The supplied residual noise signal e₁~ E₈And depending on the
Each adaptive digital filter W of the digital filter 13 _km
Update filter coefficients based on LMS algorithm
I do.

Here, the LMS algorithm is one of suitable algorithms for updating the filter coefficient of the adaptive digital filter, and is an l-th (l = 1, 2,...,
The residual noise signal detected by the microphone of L: L = 8) is e _l (n), the residual noise signal detected by the l-th microphone when no control sound is generated from the loudspeaker is d _l (n), The m-th (m = 1, 2,..., M: M =
4) The jth (j = 0, 1, j) of the digital filter C ＾ _lm which models the transfer function between the loudspeaker and the lth microphone in the form of a finite impulse response function
2, ..., J-1: J is a constant).
_{Lm lmj} , the reference signal x _k (n), the i-th (i = 0, 1, 2,..., Of the adaptive digital filter W _km driving the m-th loudspeaker to which the reference signal x _k (n) is input) I
−1: I is a constant) and the filter coefficient is W _kmi , Holds.

Note that any term after (n) is a sump.
Represents the sample value at ring time n, and J is
Filter C ＾_lmThe number of taps (the number of filter coefficients), I is
Adaptive digital filter W_kmNumber of taps (filter coefficient
). In the above equation (1), “ΣΣW_kmi
x_k(N-j-i) "is applied to the adaptive digital filter.
Reference signal x_kOutput y when (n) is input_m(N)
Then, "ΣC ＾_lmj｛ΣΣW_kmix_k(N-ji)｝ "
Is the signal y input to the m-th loudspeaker
_m(N) is output therefrom as a control sound to the space and transmitted
Number C ＾ _lmAnd when it reaches the l-th microphone
Signal, and “{C}_lmj｛ΣΣW_kmix_k
(N-ji)｝ ”term reaches the l-th microphone.
Since the signals that have reached are added together, the l-th micro
Represents the sum of control sounds reaching the phone.

Next, the evaluation function Je is And

The LMS algorithm determines the filter coefficient W _kmi that minimizes the evaluation function Je. More specifically, the evaluation function Je is calculated by using each filter coefficient W _kmi.
The filter coefficient W _kmi is updated with the value obtained by partially differentiating. Therefore, from the above equation (2), From the above equation (1), Therefore, if the right side of the equation (4) is set to r _klm (n−i), the update of the filter coefficient is as shown in the following equation (5).

[0046] That is, the microprocessor 16 determines the filter coefficient W of the adaptive digital filter W _km based on the above equation (5).
Update _kmi . Note that α is a coefficient called a convergence coefficient, and is related to the speed at which the filter converges optimally and its stability.

Further, the microprocessor 16 is supplied with a reference signal x _{k in} addition to the residual noise signal e _l and the processing signal r _klm , and the microprocessor 16 receives the residual noise signal e _l and the reference signal x k as input signals. It is determined whether or not _k is a large input exceeding a predetermined threshold. If these signals do not exceed the predetermined threshold, a process of updating the filter coefficient W _kmi according to the above equation (5) is executed. to one, performs the control to maintain the value of the time value update processing stops the filter coefficient W _KMI coefficient and the filter stop processing of updating the W _KMI if it exceeds. And Phil
Stop the update process after stopping the update process of the coefficient W _kmi
After a lapse of time, it is determined that the large input has been
The process of updating the _ruta coefficient W _kmi is restarted
I have. Moreover, as the vehicle speed V increases, the filter coefficient W _{kmi increases} .
The time for stopping the update process is shortened.

FIG. 3 is a flowchart showing the outline of the processing executed in the controller 10. The operation of this embodiment will be described below with reference to FIG. That is, step 10
After reading the reference signal x _k and the residual noise signal el in ₁ , the process proceeds to step 102 where the reference signal x _k is read.
Is greater than a reference signal upper limit value x _MAX as a predetermined threshold value. If the determination in step 102 is "NO", the process further proceeds to step 103,
Residual noise signal e _l is determined whether it exceeds the residual noise signal upper limit e _MAX as a predetermined threshold value.

If the determinations in steps 102 and 103 are both "NO", it can be determined that the reference signal _xk and the residual noise signal _el are at the normal level, that is, that they are not large inputs. Then, the processing shifts to step 104, where the reference signal x _k is filtered by the digital filter C ＾ _lm to calculate the processing signal r _klm.
Then, the process goes to 5 to update the filter coefficient W _kmi of the adaptive digital filter W _km according to the above equation (5).

[0050] Then, the process proceeds to step 106, the reference signal x _k filtered to generate the drive signal y _m in the adaptive digital filter W _miles, each loudspeaker 7a~7d the drive signal y _m at step 107 Output to Then, control sounds are generated in the vehicle compartment 6 from the loudspeakers 7a to 7d. Immediately after the control starts, each filter coefficient W _kmi of the adaptive digital filter W _km is not always converged to an optimum value. It cannot be said that the road noise transmitted into the vehicle interior 6 is necessarily reduced.

However, since the processing of steps 101 to 107 in FIG. 3 is repeatedly executed in accordance with a predetermined sampling clock, each filter coefficient W of the adaptive digital filter W _km is determined as long as the determination in steps 102 and 103 is “NO”. _{Since kmi} is appropriately updated according to the above equation (5), each filter coefficient W _kmi converges toward the optimum value, and the road noise transmitted into the vehicle interior 6 is emitted from the loudspeakers 7a to 7d. As a result, the noise in the passenger compartment 6 is reduced.

On the other hand, when a large and sudden displacement occurs in the vertical direction, for example, when at least one of the wheels 2a to 2d gets over a protrusion on the traveling road surface, a reference corresponding to the wheel on which the protrusion has been run. level signal x _k is rapidly increases, the value of the reference signal x _k exceeds the reference signal upper limit value x _MAX is determined at step 102 I become "YES", the process proceeds to step 134. Stay
After shifting to step 134, the counter variable t is initialized to 1.
Then, the process proceeds to step 108.

Then, in step 108, step 1
The update process of the filter coefficient W _kmi as shown in _FIG.
Set. W _kmi (n + 1) = W _kmi (n) (6) That is, the determination in step 102 or 103 is “YES”
When, the current filter coefficient W _kmi (n) is used as it is as a new filter coefficient W _kmi (n + 1).
After the processing of step 108 is performed, step 136
And the counter variable t is incremented by one,
Next, at step 137, a drive signal y _m is generated and the drive signal y _m is generated.
In step 138, the dynamic signal y _m is output to each of the loudspeakers 7a to 7a.
7d. Further, the processing shifts to step 139,
Whether the counter variable t has reached the counter upper limit value t _MAX
Is determined, if not reached, in step 140
After reading the new reference signal x _k , go to step 108
Returning, the above-mentioned processing is repeatedly executed. And
When the determination in step 139 is “YES”
Returns to step 101 and repeatedly executes the above-described processing.
I do.

As described above, the adaptive digital filter W _km
Filter coefficients W _KMI of, ing to the current value without being updated is maintained when any one of the reference signal x _k and the residual noise signal e _l is larger input.

[0055] That is, with the configuration of this embodiment, each filter coefficient W _KMI of the adaptive digital filter W _miles, the reference signal x _k and the residual noise signal e _l is updated only when in the normal level, a large input , The filter coefficient W _kmi is not updated and is kept at the latest value.
Is prevented from changing unnecessarily. As a result, the risk of the control becoming a divergent state or an increased sound state is reduced, and even when the reference signal x _k and the residual noise signal e ₁ have returned to the normal level from the state of the large input, the filter coefficient W _kmi is kept in a good condition in accordance with its normal level,
A control sound capable of canceling noise can be generated.

In this embodiment, even when a large input is detected, only the updating process of the filter coefficient W _kmi is stopped.
It _m Generating is continued using the filter coefficients when updating stop, the reference signal x _k is driven if a large input signal y
_{Since m} has a size commensurate with that, it is also possible to cancel road noise at the time of a large input.

Further, after a large input is detected, the counter
After a lapse of a predetermined corresponding time to the upper limit value t _MAX is stearyl
Since the processing after step 101 is executed again, it is possible to easily return to the state before the large input state. And book
In the embodiment, the counter upper limit value t _MAX is set according to the vehicle speed V.
Because it is strange, the effect of large input affects the update process
Can be reliably prevented. That is, as shown in FIG.
The time required for the noise to attenuate is lower for high-frequency components
While the frequency component can be shorter than the frequency component, as shown in FIG.
The higher the speed, the higher the frequency component of the generated road noise
It will be. Therefore, the counter variable t _MAX is _calculated as shown in FIG.
As shown in FIG.
Then, it will be set to an appropriate value. In other words, the book
In the case of the configuration of the embodiment, the time since the update process was stopped
It is determined whether the large input has been canceled according to
After the input is determined, steps 102 and 10
Since the processing of step 3 is omitted, the calculation load is reduced,
Moreover, as the vehicle speed V increases, the filter coefficient W _kmi is updated.
When the update process is stopped because the time to stop
As a result, the update time is set to the optimal value
Can be stopped unnecessarily long.
You. In this embodiment, the digital filter 12 and the microprocessor 16 constitute an adaptive processing means, and the processing in steps 102 and 103 corresponds to the large input detecting means, and the determination in step 102 or 103 is “YES”. In this case, the flow in which the processing of steps 104 and 105 is not executed corresponds to the update processing stopping means, the processing in step 108 corresponds to the filter coefficient setting holding means, and the processing in steps 134, 136 and 139
The processing performed by the processing corresponds to the update processing restarting means.

[0058]

FIG. 7 is a view showing a main part of the second embodiment of the present invention, and is a flowchart showing an outline of processing executed in the controller similarly to FIG. 3 in the first embodiment. Are given the same reference numerals. The other configuration is the same as that of the first embodiment, and its illustration and description are omitted. That is, in this embodiment, the adaptive digital filter W
After updating the filter coefficient W _{kmi of km} , step 11
The processing shifts to 0, and the new filter coefficient W _kmi is stored in the backup memory.

At step 110, the filter coefficient W _kmi
Is a memory _capable of storing a filter coefficient W _kmi , and in step 110, the latest filter coefficient W _kmi (n
When +1) is stored, the contents stored in the backup memory are shifted to sequentially delete the oldest filter coefficient W _kmi .

Then, step 102 or step 10
If the determination of step 3 is “YES”, step 13
4 and then go to step 111,
The filter coefficient W _kmi before a sampling stored in the memory is _set as a new filter coefficient W _kmi (n + 1). That is, in the present embodiment, unlike the first embodiment, the filter coefficient W
_{Instead of using kmi} (n) as a new filter coefficient W _kmi (n + 1), the filter coefficient W _kmi calculated in the processing a sampling before the update processing is stopped is _replaced with a new filter coefficient W _kmi (n + 1). ), And holds the value until the determination in step 139 becomes " YES " later.

[0062] That is, since it is when the determination in step 102 or 103 is already the reference signal x _k or the residual noise signal e _l is becoming a "YES" has become a large input, step while approaching the Dainyuu Since the processes of 104 and 105 have been executed, the filter coefficient W _kmi of the adaptive digital filter W _km is also likely to fluctuate under the influence of the large input.

However, as in this embodiment, the filter coefficient W _kmi up to several samplings before is stored in step 110, and if a large input is detected, step 1 is _executed.
In the configuration using the filter coefficient W _kmi before several samplings in step 11, it is possible to set the filter coefficient W _kmi that is not affected by the large input without fail. Can be prevented.

In this embodiment, steps 110 and 111
Corresponds to the filter coefficient setting holding unit. Other functions and effects are the same as those of the first embodiment. FIG. 9 is a view showing a main part of the third embodiment of the present invention, and is a flowchart showing an outline of processing executed in the controller similarly to FIG. 3 in the first embodiment, and the same processing is performed. The steps to be executed are denoted by the same reference numerals. The other configuration is the same as that of the first embodiment, and its illustration and description are omitted.

That is, in this embodiment, as in the second embodiment, the filter coefficient W which is not affected by the large input is surely provided.
_The purpose is to maintain _kmi , but the processing content is slightly different from that of the second embodiment. In particular,
After updating the filter coefficient W _kmi in step 105,
The process proceeds to step 121, where it is determined whether or not the current sampling time n is a multiple of the predetermined value a. If this determination is yes, the _{process proceeds} to step 122, and the filter coefficient W _kmi is _stored in the backup memory. To memorize. Therefore, the backup memory only needs to have a capacity capable of storing the filter coefficient W _kmi in one sampling. In step 111, the filter coefficient W _kmi stored in the backup memory is _set to a new filter coefficient W _kmi (n + 1).

With such a configuration, the past filter coefficient W is used instead of the filter coefficient W _kmi (n) when updating is stopped.
_kmi is the new filter coefficient W _kmi (n
Since +1) is set, the possibility of using a filter coefficient affected by a large input can be significantly reduced. In addition, the capacity of the backup memory is
There is an advantage that the number of operations is smaller than that of the embodiment, and the content of the backup memory does not need to be shifted when storing, so that the calculation load is reduced.

Note that the predetermined value a may be a fixed value, but it is desirable to make it slightly larger when the control system is stable, and to make it slightly smaller when the control system is changing. The change in the system can be grasped from the change in the number of occupants, the state of opening and closing the windows, and the like. In this embodiment, step 1
Processes 11, 121, and 122 correspond to a filter coefficient setting holding unit. Other functions and effects are the same as those of the first embodiment.

It is to be noted that, instead of storing the filter coefficient during the execution of the control as in the present embodiment, for example, the filter coefficient when the engine was stopped last time is stored, and step 11 is executed.
1, the stored filter coefficient may be read. FIG. 9 is a view showing a main part of a fourth embodiment of the present invention, and is a flowchart showing an outline of processing executed in the controller similarly to FIG. 3 in the first embodiment. The steps to be executed are denoted by the same reference numerals.

[0069] That is, in the first to third embodiments, is detected directly Dainyuu based on the reference signal x _k or the residual noise signal e _l, that the load noise irregularities of road surface In this embodiment, since the level is substantially determined, the state of the traveling road surface is constantly monitored, and the presence of a large input is detected in advance and indirectly. Specifically, in step 101, the reference signal x _k and the residual noise signal e
After reading _l , the process proceeds to step 131, where the output of a sensor for monitoring the condition of the running road surface (for example, an ultrasonic sensor mounted on the front of the vehicle and measuring the distance between the vehicle body and the road surface) is read. , The height H of the protrusion existing in front of the vehicle is read. In step 131, the current vehicle speed V is also read.

[0070] By the process proceeds to step 132, referring to the storage table shown in FIG. 10, for example, the acceleration x _p that is input as soon reference signal x _k
Is calculated. Note that in the storage table of FIG.
The higher the vehicle speed V, the larger the value of the acceleration x _p is, even if the projections have the same height H, the larger the vehicle speed V when passing, the larger the value of the acceleration x _p generated. It is.

When the acceleration x _p is calculated, step 13
3 proceeds to determine whether the acceleration x _p exceeds the reference signal upper limit value x _k. If the determination in step 133 is "NO", the flow shifts to step 104 and the above-described processing is executed as appropriate. However, step 13
When the determination in Step 3 is “YES”, the processing after Step 134 is executed.

First, at step 134, the counter variable t is initialized to 1, and then at step 135, a new filter coefficient W _kmi (n + 1) is _obtained according to the above equation (6).
Set. Then, at step 136, the counter variable t
Is incremented by 1, then generates a drive signal y _m in step 137, step 13 and the drive signal y _m
At 8, output is made to each of the loudspeakers 7 a to 7 d.

Further, the flow shifts to step 139, where it is determined whether or not the counter variable t has reached the counter upper limit value t _MAX. If not, a new reference signal x _k is read in step 140 after reading. Returning to step 135, the above processing is repeatedly executed. When the determination in step 139 is “YES”, the process returns to step 101 and the above-described processing is repeatedly executed.

That is, the determination in step 133 is “YE
After “S”, the filter coefficient W _kmi is held at the value at the time when the update is stopped until the time corresponding to the counter upper limit value t _MAX elapses. This is because in the present embodiment, when a protrusion is found in front of the vehicle, it is indirectly detected that there is a large input, and the determination in step 133 becomes “YES”, and the updating process of the filter coefficient W _kmi is stopped. However, in this case, the state in which no large input occurs is after the rear wheel of the vehicle has passed over the protrusion,
The update process cannot be restarted for a predetermined time after the protrusion is found.

Accordingly, the counter upper limit value t _MAX can be set according to the following equation (7) based on the sampling frequency f _s , the vehicle speed V, and the distance S from when the filter coefficient update is stopped to when the rear wheel passes over the protrusion. it can. In the configuration of _{t MAX = f s · S /} V ...... (7) This embodiment thus, updating of the filter coefficient W _KMI with and indirectly detected before things <br/> that there is a large input Processing can be stopped, and the counter upper limit value t _MAX
Since the update process continues to be stopped until a predetermined time (update stop time) corresponding to the time elapses, the filter coefficient W _kmi
Can be reliably prevented from unnecessarily fluctuating due to the influence of a large input, and the divergent state and the increased sound state can be more reliably prevented.

Here, in this embodiment, steps 131 to 131 are executed.
Step 133 corresponds to the large input detecting means.
Determined at 3 flows without executing the processing of step 105 when it is determined "YES" corresponds to the update processing suspension unit, processing in step 135 corresponds to the filter coefficient setting holding means, step 134,136,13 9 Corresponds to the update process resuming means. Other functions and effects are the same as those of the first embodiment.

[0077]

[0078]

[0079]

[0080] Figure 1 1 is a diagram illustrating a fifth embodiment of the present invention. The other configuration is the same as that of the first embodiment, and its illustration and description are omitted. That is, in this embodiment, the reference signal upper limit value x _MAX and the residual noise signal upper limit value e _MAX which are the basis for determining whether or not the input is large in the above embodiments are set to variable and appropriate values. By
It is intended to further improve the control performance.

More specifically, in step 201, a counter variable p is initialized to 1 and then in step 202
Read reference signal x _k and the residual noise signal e _l in. The processing in step 202 is actually used also in the process of FIG. 3 and FIG. 7, etc. Step 101.
Then, the process proceeds to step 202, accumulates the reference signal x _k and the residual noise signal e _l read, the counter variable p at step 205 the counter variable p at step 204 after incremented by one within a predetermined value p _MAX It is determined whether or not it has reached, and the determination in step 205 is “YE
The processing of the above steps 202 to 204 is repeatedly executed until “S” is reached.

[0082] If a determination in step 205 is "YES", the process proceeds to step 206, the reference signal x _k and the residual noise signal e accumulation value x _t and e _t of _l, predetermined value p _MAX and the number of channels K , L, and these are defined as a reference signal upper limit _xMAX and a residual noise signal upper limit _eMAX . That is, if the configuration of the present embodiment, the reference signal upper limit value x _MAX and the residual noise signal upper limit e _MAX is the average value of the reference signal x _k and the residual noise signal e _l in the time within the p = 1 to p _MAX Becomes

For this reason, the reference signal upper limit value x _MAX and the residual noise signal upper limit value e _MAX have relatively large values when traveling on a rough road surface such as a mountain road, but have a relatively large value like a pavement road. When traveling on a quiet road surface, the value is relatively small, so that an optimal divergence prevention effect according to a change in the road surface can be exhibited. Other functions and effects are the same as those of the first embodiment.

[0084] Figure 1 2 is a diagram illustrating a sixth embodiment of the present invention. The basic configuration is the same as that of the first embodiment, and its illustration and description are omitted. That is, in the present embodiment, steps 101 to 108 , 134 , 136 , and 139
_Are the same as those in the first embodiment, but if it is determined in step 102 or 103 that the input is large and the _{process proceeds} to steps 134 and 108, the filter coefficient W _kmi is updated. Without performing any processing .
Steps 108 to 139 are repeatedly executed, and
When the determination in step 139 becomes "YES", the process returns to step 101.

Therefore, when it is determined that the input is large, the filter coefficient W _kmi of the adaptive digital filter W _km is _determined.
With update processing is stopped, since the generation and output of the drive signal y _m is stopped, the control sound is not generated.
However, the determination in step 139 later becomes “YES”.
If the, the processing of steps 104 to 107 is performed.

With such a configuration, it is possible to at least prevent the filter coefficient W _kmi from fluctuating significantly under the influence of a large input, as in the first embodiment. Further, once the updating process of the filter coefficient W _kmi is stopped, the noise reduction control is not stopped permanently, but when the input level returns to the normal level, the updating process of the filter coefficient W _{kmi and} the process of generating the control sound are performed. After the restart, the normal noise reduction control is executed thereafter.

[0087] Although not described specifically shown, the reference signal x _k as the above embodiment, when the remaining noise signal e _l have multiple channels, reference signal upper limit value x _MAX, residual noise signal e _By setting _MAX , the counter upper limit value _{tMAX, and the} like individually for each channel of the reference signal x _k and the residual noise signal _el , even when the frequency band and level of each signal are different, the optimum value is obtained. A large divergence preventing effect can be obtained.

[0088]

[0089]

[0090]

As described above, according to the present invention,
It is possible to directly or indirectly detect that the input signal to the adaptive processing means is a large input, and when this is detected, only the update processing of the filter coefficient of the adaptive digital filter is stopped, and the control sound is generated. Since the generation process is configured to continue, the filter coefficient is prevented from being unnecessarily fluctuated, and the risk of the control being in a divergent state or an increased sound state is reduced. Immediately after returning to a normal level from a large input state, the filter coefficient is maintained in a good state commensurate with the normal level. Can be generated. In particular, according to the first aspect of the present invention,
If the predetermined update stop time is variable according to the vehicle speed
This ensures that large inputs do not affect the update process
There is also an effect that can be done. Further, according to the second aspect of the present invention,
According to this, it is detected in advance and indirectly that there is a large input.
The update process of the filter coefficient can be stopped by
Filter coefficients unnecessarily fluctuate due to large input
There is an effect that it is possible to more reliably prevent the user from doing so.

According to the ninth to eleventh aspects of the present invention, when it is detected directly or indirectly that the input signal to the adaptive processing means is a large input, at least a filter of the adaptive digital filter is detected. Since the coefficient updating process is stopped, it is possible to at least prevent the filter coefficients from being unnecessarily changed due to the influence of the large input.

[Brief description of the drawings]

FIG. 1 is a diagram showing an overall configuration of a first embodiment.

FIG. 2 is a block diagram illustrating a configuration of a controller.

FIG. 3 is a flowchart illustrating an outline of a process according to the first embodiment.

FIG. 4 shows a frequency indicating a relationship between a noise frequency and a decay time.
It is a characteristic diagram .

FIG. 5 is a frequency characteristic diagram showing a relationship between vehicle speed and vehicle interior noise .

FIG. 6 is a graph showing an example of a relationship between a vehicle speed and an update stop time.
It is a flow.

FIG. 7 is a flowchart showing an outline of a process in a second embodiment .
It is a chart .

FIG. 8 is a flowchart showing an outline of processing in a third embodiment .
It is a chart .

FIG. 9 is a flowchart showing an outline of a process in a fourth embodiment .
It is a chart .

FIG. 10 shows the relationship between the height of the protrusion, the vehicle speed, and the generated acceleration.
It is a graph which shows a relationship .

FIG. 11 is a flowchart showing an outline of processing in a fifth embodiment .
It is a chart .

[12] Ru flowchart der showing an outline of processing in the sixth embodiment.

[Description of Signs] 1 Active noise control device 2a to 2d Wheels (noise source) 5a to 5d Acceleration sensor (noise generation state detecting means) 6 Car room (space) 7a to 7d Loudspeaker (control sound source) 8a to 8d Microphone (Residual noise detecting means) 10 Controller 12 Digital filter 13 Adaptive digital filter 16 Microprocessor

──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Mihiro Doi Nissan Motor Co., Ltd. 2 Takaracho, Kanagawa-ku, Yokohama-shi, Kanagawa Prefecture (56) References JP-A-6-118971 (JP, A) JP-A-5 40486 (JP, A) JP-A-5-27776 (JP, A) JP-A-4-303898 (JP, A) JP-A-4-11291 (JP, A) JP-A-3-263573 (JP, A) Japanese Utility Model Application Hei 3-70490 (JP, U) Special Table Hei 1-501344 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) G10K 11/178 B60R 11/02 H03H 17 / 02 H03H 17/04 H03H 21/00

Claims (14)

(57) [Claims] 1. A control sound source applied to a vehicle and capable of generating a control sound in a vehicle compartment in which noise is transmitted from between a wheel and a road surface ;
A noise generation state detection means for detecting a noise generation state of the noise source and outputting it as a reference signal; a residual noise detection means for detecting residual noise at a predetermined position in the space and outputting it as a residual noise signal; An adaptive digital filter; drive signal generating means for filtering the reference signal with the adaptive digital filter to generate a signal for driving the control sound source; and noise in the space based on the reference signal and the residual noise signal. And an adaptive processing means for updating a filter coefficient of the adaptive digital filter so as to reduce the input signal. The input signal to the adaptive processing means is a large input exceeding a predetermined threshold value. A large input detecting means for directly or indirectly detecting that the large input detecting means detects the large input. Update processing stopping means for stopping the update processing of the filter coefficients of the adaptive digital filter by the adaptive processing means; and, when the update processing stop means stops the update processing, the filter coefficient of the adaptive digital filter is affected by the large input. Filter coefficient setting and holding means for setting or holding a value which has not been subjected to the update processing;
The specified update stop time has elapsed since the stage stopped updating
Release the suspension of the update process and restart the update process
Is thereby provided and update processing resuming means, and characterized in that a variable according to the updated stop time of the vehicle speed
Active noise control system according to. 2. The method according to claim 1 , wherein the noise is applied between a wheel and a road surface.
A control sound source capable of generating a control sound in a vehicle room to which sound is transmitted;
Detects the noise generation state of the noise source and outputs it as a reference signal
Noise generating state detecting means, and a predetermined position in the space.
To detect residual noise and output it as a residual noise signal
Noise detection means and adaptive digital filter with variable filter coefficients
A filter, and the adaptive digital filter
Filter to generate a signal for driving the control sound source.
Drive signal generating means for generating the reference signal and the residual signal.
So that the noise in the space is reduced based on the noise signal
Update the filter coefficients of the adaptive digital filter
An active noise control device having adaptive processing means.
Te, the input signal to the adaptive processing unit exceeded a predetermined threshold value
Large input detection means for detecting a large input
When the large input detecting means detects the large input, the
Filter of the adaptive digital filter by processing means
Update processing stopping means for stopping the coefficient update processing;
When the new process stopping means stops the updating process, the
The filter coefficient of the digital filter is
Filter coefficient settings that are set or maintained at unaffected values
Fixed holding means, and the large input detecting means further comprises a distance between a vehicle body and a road surface.
And a distance detecting means for detecting the distance.
The input signal to the adaptive processing means has a predetermined threshold according to the output result.
To detect indirectly large input that exceeds
An active noise control device characterized in that: 3. The update processing is stopped by the update processing stop means.
Update processing restart means to cancel the
The active noise control device according to claim 2, wherein 4. An updating process restarting means for updating an adaptive processing means.
Update processing when the input signal falls below a predetermined threshold
4. The active noise control device according to claim 3, which is restarted . 5. The update processing restarting means includes an update processing stopping means.
Has stopped the update process and the specified update stop time has passed.
5. The active noise control device according to claim 4 , wherein the updating process is restarted after the update . 6. The active noise control device according to claim 5, wherein the predetermined update stop time is variable . 7. An adaptive digital filter comprising :
The update processing stop means updates the filter coefficient of the digital filter.
Active noise control apparatus according to any one of claims 1 to 6 holds the value when stopping the updating process. 8. The adaptive filter according to claim 1, wherein said filter coefficient setting and holding means includes an adaptive filter.
The update processing stop means updates the filter coefficient of the digital filter.
Active noise control apparatus according to any one of claims 1 to 6 is set to the value before stopping the updating process. 9. Applicable to a vehicle, wherein noise is generated between a wheel and a road surface.
A control sound source capable of generating a control sound in a vehicle room to which sound is transmitted;
Output as the reference signal to detect the occurrence of noise state of the noise source
Noise generating state detecting means, and a predetermined position in the space.
To detect residual noise and output it as a residual noise signal
Noise detection means and adaptive digital filter with variable filter coefficients
A filter, and the adaptive digital filter
Filter to generate a signal for driving the control sound source.
Drive signal generating means for generating the reference signal and the residual signal.
So that the noise in the space is reduced based on the noise signal
Update the filter coefficients of the adaptive digital filter
An active noise control device having adaptive processing means.
Te, the input signal to the adaptive processing unit exceeded a predetermined threshold value
Large input that directly or indirectly detects that the input is large
Force detecting means, and the large input detecting means detects the large input
The adaptive digital processing by the adaptive processing means.
Update processing to stop the update processing of the filter coefficient of the filter
Stopping means for stopping the update processing;
Update processing after the specified update stop time has elapsed
To restart the update process to release the suspension of the process and restart the update process
And the update stop time is made variable according to the vehicle speed.
Active noise control system according to. 10. Applied to a vehicle, from between a wheel and a road surface
Control sound source that can generate control sound in the cabin where noise is transmitted
And the noise generation state of the noise source is detected and used as a reference signal.
A noise generation state detecting means for outputting, and a predetermined position in the space.
Detects residual noise in the device and outputs it as a residual noise signal
Residual noise detection means and an adaptive digital filter with variable filter coefficients
Filter and the adaptive digital filter
A signal for driving the control sound source after being filtered by a filter
Drive signal generating means for generating the reference signal,
The noise in the space is reduced based on the residual noise signal.
Update the filter coefficients of the adaptive digital filter
Active noise control device having adaptive processing means
And the input signal to the adaptive processing means exceeds a predetermined threshold.
Large input detection means for detecting a large input
When the large input detecting means detects the large input, the
Filter of the adaptive digital filter by processing means
Update processing stopping means for stopping the coefficient update processing.
Only, further said large input detecting means, a distance between the vehicle body and the road surface
A distance detection means to detect, detection of the distance detecting means
The input signal to the adaptive processing means has a predetermined threshold according to the output result.
To detect indirectly large input that exceeds
An active noise control device characterized in that: 11. The large input detecting means includes a road surface near a vehicle.
The input signal to the adaptive processing means is based on a predetermined threshold
A claim that indirectly detects that a large input exceeds the value
An active noise control device according to claim 9 . 12. The large input detecting means is provided between the vehicle body and the road surface.
A distance detecting means for detecting a distance, the distance detecting means
Input signal to the adaptive processing means according to the detection result of
Active noise control apparatus for indirectly detect <br/> claim 11 Symbol mounting that exceed the threshold is larger input. 13. The system according to claim 1, wherein the predetermined threshold value is variable.
The active noise control device according to claim 12. 14. The active noise control device according to claim 13, wherein an average value of the input signal to the adaptive processing means within a predetermined time is set as a predetermined threshold value.