JP3371477B2 - Active vibration control device for vehicle and active noise control device for vehicle - 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 vibration control device for a vehicle, an engine, etc., for reducing the vibration by interfering the control vibration with the periodic vibration emitted from a vibration source such as an engine and propagating in a vehicle body. The present invention relates to an active noise control device for a vehicle, which reduces noise by interfering control noise with noise transmitted from the noise source to the vehicle interior, and in particular to the vibration or noise as a reference signal indicating a vibration or noise generation state. In a device using synchronized impulse trains, it is possible to obtain a stable vibration noise reduction effect against vibration or noise in a wide frequency band.

[0002]

2. Description of the Related Art As a conventional technique of this type, there are those described in British Patent No. 2149614 and Japanese Patent Publication No. 1-501344. These conventional devices are noise reduction devices applied to aircraft cabins and similar closed spaces, and a single noise source such as an engine located outside the closed space has a fundamental frequency f ₀ and its harmonics. It operates under the condition that noise including the waves f _{1 to} f _n is generated.

[0003] More specifically, includes a microphone for detecting a plurality of the installed sound pressure to a location within the closed space, and a plurality of loudspeakers for generating a control sound to the closed space, the frequency f ₀ of the noise source - Based on the f _n component, those frequencies f ₀ ~
The loudspeaker is driven by a signal having a phase opposite to that of the f _n component,
Therefore, a control sound having a phase opposite to that of the noise transmitted to the closed space is generated from the loudspeaker to cancel the noise.

Then, as a method of generating the control sound emitted from the loudspeaker, PROCEEDINGS OF THE IEEE, VOL.
63 PAGE 1692,1975, “ADAPTIVE NOISE CANSELLATION:
PRINCIPLES AND APPLICATIONS ”
An algorithm that applies the DROW LMS 'algorithm to multiple channels is applied. The content of the paper is "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 the algorithms suitable 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 transfer function filter that models the transfer function from the loudspeaker to the microphone is set for all combinations of the loudspeaker and the microphone, and a reference signal representing the noise generation state of the noise source is set. Update the filter coefficient of the adaptive digital filter with variable filter coefficient provided for each loudspeaker so that the value of the predetermined evaluation function based on the value processed by the filter and the residual noise detected by each microphone is reduced. is doing.

Further, as another conventional active noise control device, there is a device described in "Acoustic Society of Japan 1992 Spring Research Presentation Lecture Proceedings", pages 515-516. Synchronous Filtered-X
It is called an LMS algorithm, and is characterized in that an impulse train synchronized with the fundamental frequency of noise is applied as a reference signal representing the noise generation state. That is, in such a conventional device, since the reference signal is an impulse train, multiplication is unnecessary, convolution calculation can be performed only by addition, and addition is not necessary in some cases. Therefore, there is an advantage that the processing can be performed at high speed.

[0007]

Certainly, the above-mentioned synchronous F
When the iltered-X LMS algorithm is applied, there is an advantage that the calculation load is reduced as a result of simplifying the convolution calculation. However, when the period of vibration or noise to be reduced is long (when the frequency is low) and when the period is short (when the frequency is high), the former is the number of filter coefficients of the adaptive digital filter that outputs within one period. However, there is an imbalance in that the calculation load is large due to the large number of calculation errors and therefore the calculation load is large. Clock (sampling of residual vibration signal and residual noise signal
It is a clock, which has to be determined to be equal to the drive signal generation period. However, when the sampling clock is determined in this way, in the case of high frequency vibration, high frequency noise input, etc. The sampling clock becomes relatively coarse with respect to the cycle of noise, and the number of drive signals output in one cycle is reduced, which makes it impossible to expect highly accurate vibration reduction control or noise reduction control. .

To solve such a problem, the number of drive signals output in one cycle is fixed, that is, vibration reduction control and noise reduction control are always performed using 1 / N of one cycle as a sampling clock. Measures can be considered. However, if such a solution is adopted, sampling
Since the clock changes continuously, it is necessary to change the transfer function filter expressed on the time axis continuously by following the continuous change of the sampling clock. Therefore, vibration reduction control, noise reduction control, etc. It is necessary to perform transfer function identification processing in parallel with the above, or to store in memory a large number of types of transfer function filters.
Therefore, it is necessary to develop an identification method that does not significantly increase the calculation load or install a large-capacity memory.

The present invention has been made by paying attention to such unsolved problems in the prior art, and does not cause problems such as deterioration of control accuracy during high frequency vibration and high frequency noise input, and the like. Synchronous Filtered-X
An object of the present invention is to provide an active vibration control device for a vehicle and an active noise control device for a vehicle that can effectively utilize the advantages of the LMS algorithm.

[0010]

In order to achieve the above object, an active vibration control device for a vehicle according to the invention of claim 1 interferes with periodic vibrations emitted from a vibration source and propagating in a vehicle body. Control vibration source capable of generating control vibration, reference signal generating means for generating a reference signal having an impulse train of the same cycle as the periodic vibration, and vibration after the interference is detected and output as a residual vibration signal. Residual vibration detection means,
Reference processing signal generating means for generating a reference processing signal by convolving the transfer function filter modeling the transfer function between the control vibration source and the residual vibration detecting means, and the reference signal and the filter coefficient of the transfer function filter. An adaptive digital filter having a variable filter coefficient, and the filter coefficients of the adaptive digital filter are sequentially output to the control vibration source as drive signals at intervals of a predetermined sampling clock from the time when the latest impulse of the reference signal is generated. Drive signal generating means, adaptive processing means for updating the filter coefficient of the adaptive digital filter based on the reference processed signal and the residual vibration signal so as to reduce the vibration after the interference, and the frequency of the vibration is detected. Frequency detection means and a high frequency based on the frequency of the vibration detected by this frequency detection means. Sampling clock switching means for switching the predetermined sampling clock so that the wave side becomes shorter than the low frequency side, and the sampling clock switching means comprises intervals between filter coefficients of the transfer function filter on the time axis. The predetermined sampling clock is switched so as to be an integral multiple of.

In order to achieve the above object, the vehicle active noise control device according to a second aspect of the invention is a control for interfering with periodic noise emitted from a noise source and transmitted to the vehicle interior. A control sound source capable of generating sound, reference signal generating means for generating a reference signal having an impulse train having the same period as the periodic noise, and residual noise detection for detecting the noise after the interference and outputting it as a residual noise signal. Means, a transfer function filter modeling a transfer function between the control sound source and the residual noise detecting means, and a reference processing signal for generating a reference processing signal by convolving the reference signal and the filter coefficient of the transfer function filter. Generating means, an adaptive digital filter with variable filter coefficient, and the adaptive function at a predetermined sampling clock interval from the time when the latest impulse of the reference signal is generated. Drive signal generating means for sequentially outputting the filter coefficients of the digital filter as a drive signal to the control sound source, and the adaptive digital filter for reducing the noise after the interference based on the reference processed signal and the residual noise signal. Adaptive processing means for updating the filter coefficient, frequency detection means for detecting the frequency of the noise,
Sampling clock switching means for switching the predetermined sampling clock so that the high frequency side is shorter than the low frequency side based on the frequency of the noise detected by the frequency detecting means, and the sampling clock switching means comprises: The predetermined sampling clock is switched so that it becomes an integral multiple of the interval on the time axis of each filter coefficient of the transfer function filter.

[0012]

According to the first aspect of the present invention, the drive signal generating means sets the filter coefficient of the adaptive digital filter at a predetermined sampling clock interval from the time when the latest impulse generated by the reference signal generating means is generated. Since the control vibration is output to the controlled vibration source in order as a drive signal, the controlled vibration corresponding to the filter coefficient of the adaptive digital filter is generated from the controlled vibration source. The vibration propagating in the vehicle body is not necessarily reduced because the vibration does not necessarily converge to the.

However, the adaptive processing means is based on the reference processing signal generated by the reference processing signal generating means by convolving the reference signal and the filter coefficient of the transfer function filter, and the residual vibration signal detected by the residual vibration detecting means. However, since the filter coefficient of the adaptive digital filter is updated so that the vibration after interference is reduced, the filter coefficient of the adaptive digital filter converges to the optimum value as the control progresses, and therefore, the control generated from the control vibration source is controlled. The vibration cancels the vibration and reduces the vibration level.

On the other hand, when the frequency detecting means detects the frequency of the vibration emitted from the vibration source, the sampling / clock switching means performs sampling / clocking based on the detection result.
Since the clock is switched, the generation period of the drive signal when the high frequency vibration occurs is shorter than the generation period of the drive signal when the low frequency vibration occurs. Therefore, the generation cycle of the drive signal does not become rough when high frequency vibration occurs.

In addition, the sampling clock switching means is an interval on the time axis of each filter coefficient of the transfer function filter, that is, an integer of a sampling clock (hereinafter referred to as a basic sampling clock) for identifying the transfer function filter. Predetermined sampling to be doubled
In order to switch the clock, even if the sampling clock is switched by the sampling clock switching means, if the filter coefficients of the transfer function filter identified by the basic sampling clock are appropriately thinned, the sampling clock after the switching is changed. A transfer function filter expressed in time intervals of clocks is used. Therefore, the transfer function identification process is unnecessary, and since it is sufficient to set only one type of transfer function filter corresponding to the basic sampling clock, a large-capacity memory is unnecessary.

The invention described in claim 1 is intended for vibration, whereas the invention claimed in claim 2 is intended for noise. Therefore, the operation of the invention of claim 2 is substantially the same as that of claim 1 although there is a difference between vibration and sound.
It is similar to the described invention.

[0017]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing an embodiment of the present invention. In this embodiment, a so-called active vibration control apparatus for a vehicle according to the present invention is used to actively reduce vibration transmitted from an engine to a vehicle body. It is applied to the engine mount.

First, the structure will be described. As shown in FIG. 1, the engine mount 1 is integrally provided with a mounting bolt 2a for mounting the engine 30 as a vibration source on the upper side, and has a hollow inside and a lower side. The mounting member 2 has an opening, and the upper end of the inner cylinder 3 is caulked to the outer surface of the lower portion of the mounting member 2. Inside the inner cylinder 3, a diaphragm 4 is disposed so as to vertically divide the space inside the mounting member 2 and the inner cylinder 3 into two parts, which are sandwiched by the caulking prevention portions of the mounting member 2 and the inner cylinder 3. Of the space divided by the diaphragm 4, the space above the diaphragm 4 communicates with the atmospheric pressure, and the space below the diaphragm 4 is provided with the orifice structure 5.

On the other hand, on the outer peripheral surface of the inner cylinder 3, the inner peripheral surface of a cylindrical support elastic body 6 which is formed such that the axial positions of the inner peripheral surface and the outer peripheral surface are higher on the inner peripheral side is vulcanized. The outer peripheral surface of the supporting elastic body 6 is vulcanized and adhered to the inner peripheral surface of the outer cylinder 7. The lower end of the outer cylinder 7 is caulked to the upper portion of the cylindrical actuator holding member 8, and the lower end surface of the actuator holding member 8 is provided with a mounting bolt 9a for mounting the member 35 as a vehicle body on the lower side. A disc-shaped mounting member 9 provided integrally is fixed.

A cylindrical member 10 fixed to the lower end portion of the outer cylinder 7 by caulking is fixed to the upper end surface of the actuator holding member 8 and further to the inner peripheral surface of the cylindrical member 10. The movable member 12 is held by the cylindrical elastic body 11 so as to be vertically displaceable with a predetermined clearance from the upper end surface of the actuator holding member 8. The movable member 12 is made of a magnetizable material and is formed into a disk shape having a concave upper surface.

Inside the actuator holding member 8, there is arranged an electromagnetic actuator 13 including an electromagnetic coil and the like, which displaces the movable member 12 in the vertical direction according to a control signal supplied from the outside. There is. Further, in this embodiment, the lower surface of the support elastic body 6 and the movable member 1 are
2, a main fluid chamber 15 is formed in a portion defined by the upper surface of the second fluid, and a sub fluid chamber 16 is formed in a portion defined by the diaphragm 4 and the orifice structure 5. The chambers 16 communicate with each other via the orifice 5a formed in the orifice structure 5. A fluid such as oil is enclosed in the main fluid chamber 15, the sub fluid chamber 16 and the orifice 5a.

The characteristics of the fluid mount, which is determined by the flow path shape of the orifice 5a and the like, are the characteristics of the engine mount 1 when an engine shake occurs during running, that is, at 5 to 15 Hz.
Is adjusted so that it exhibits a high dynamic spring constant and high damping force when is excited. The electromagnetic actuator 13 is connected to the controller 20 and generates a predetermined electromagnetic force according to the drive signal y supplied from the controller 20.

The controller 20 includes a microcomputer, necessary interface circuits, A / D converter, D / A
It is composed of a converter, an amplifier, etc., and is a vibration in a frequency band in which a fluid cannot move between the main fluid chamber 15 and the sub-fluid chamber 16 through the orifice 5a, that is, a vibration of a higher frequency than the engine shake described above. When idle vibration, muffled sound vibration, or vibration during acceleration is input, the transmission force to the mounting member 9 becomes “0” in synchronization with the vibration (specifically, the support elastic body 6 The drive signal y is generated and supplied to the electromagnetic actuator 13 so that the input due to the elastic deformation and the input due to the volume change of the main fluid chamber 15 can be canceled out.

Here, idle vibration and muffled sound vibration are
For example, in the case of a reciprocating 4-cylinder engine, the engine rotation 2
The main cause is that the engine vibration of the next component is transmitted to the member 35 via the engine mount 1. Therefore, if the drive signal y is generated and output in synchronization with the secondary component of the engine rotation, the vibration transmissibility is increased. Can be reduced. Therefore, in the present embodiment, an impulse signal that is synchronized with the rotation of the crank angle of the engine 30 (for example, in the case of a reciprocating 4-cylinder engine, one impulse is generated every 180 degrees of the crank) is generated and output as the reference signal x. A pulse generator 21 as a reference signal generating means for
Is supplied to the controller 20 as a signal indicating a vibration generation state in the engine 30.

On the other hand, the member 35 is provided with an acceleration sensor 22 as a residual vibration detecting means for detecting the vibration state of the member 35 in the form of acceleration and outputting it as a residual vibration signal e in the vicinity of the mounting position of the engine mount 1. The residual vibration signal e, which is fixed, is supplied to the controller 20 as a signal representing the vibration after the interference. Then, the controller 20 is based on the reference signal x and the residual vibration signal e, and is a Filtered-X LMS algorithm which is one of the adaptive algorithms of the successive update type.
More specifically, the synchronous Filtered-X LMS
The drive signal y is generated and output according to the algorithm.

That is, the controller 20 has an adaptive digital filter W having a variable filter coefficient W _i (i = 0, 1, 2, ..., I-1: I is the number of taps), and the latest reference signal x Is output from the engine 30 to the member 35 via the engine mount 1 while the filter coefficient W _i of the adaptive digital filter W is sequentially output as the drive signal y at a predetermined sampling clock SC interval. The reference signal x
And a process of appropriately updating the filter coefficient W _i of the adaptive digital filter W based on the residual vibration signal e.

The update formula of the adaptive digital filter W is F
The following equation (1) follows the iltered-X LMS algorithm. _{W i (n + 1) =} W i (n) -αR T e (n) ...... (1) where, indicates that a value at term time n stick is (n), also, alpha is a convergence factor It is a coefficient that is called and is related to the speed of convergence of the filter coefficient W _i and its stability. R ^T is theoretically a value (reference signal or Filtered-X signal) obtained by filtering the reference signal x with a transfer function filter C ^ representing the transfer function C between the engine mount 1 and the acceleration sensor 22. In this embodiment, since the reference signal x is an impulse train as a result of applying the synchronized Filtered-X LMS algorithm, those impulses generated when the impulse response of the transfer function filter C ^ is generated one after another in synchronization with the reference signal x. It matches the sum of the response waveforms at time n.

Further, theoretically, the reference signal x is filtered by the adaptive digital filter W to generate the driving signal y, and the filtering process corresponds to the convolution operation in the digital operation, but the reference signal x is Since it is an impulse train, even if each filter coefficient W _i of the adaptive digital filter W is sequentially output as the drive signal y at a predetermined sampling clock interval from the time when the latest reference signal x is input as described above. , The same result as when the filtering result is the drive signal y.

Further, the controller 20 controls the engine 3
It has a function of detecting the frequency of vibration transmitted from 0 to the member 35 via the engine mount 1. Specifically, a timer function for measuring the generation interval of the reference signal x,
And a calculation function for obtaining the frequency of the vibration transmitted to the member 35 based on the measured generation interval, and the vibration is reduced at a predetermined threshold value based on the calculated frequency of the vibration. It is determined which of the frequency band, the medium frequency band and the high frequency band, and according to the result of the determination, the generation cycle of the drive signal y is set so that the high frequency side is shorter than the low frequency side. In addition, the sampling clock SC, which is the reading interval of the residual vibration signal e, is switched in three steps.

However, the sampling clock SC is
The transfer function filter C ^ can be switched stepwise to an integral multiple of a basic sampling clock SC ₀ which is a sampling clock for identifying the transfer function filter C ^. Specifically, when the vibration is determined to be in the low frequency band, the sampling clock SC is four times the basic sampling clock SC ₀ , and when the vibration is determined to be in the medium frequency band, sampling is performed. clock SC is two times the basic sampling clock SC _0, so that the vibration is in the 1 times the sample clock SC is basic sampling clock SC ₀ when it is determined that the high-frequency band, are respectively set Has become.

Furthermore, the controller 20 is adapted to change the transfer function filter C ^ used when calculating the reference signal R ^T according to the sampling clock SC which is switched in three stages. However, the sampling clock SC is set to one, two, or four times the basic sampling clock SC ₀ as described above, and on the time axis of each filter coefficient of the transfer function filter C ^. Since the interval of is the basic sampling clock SC ₀ , the transfer function filter C ^ may use all the filter coefficients as they are when the sampling clock SC is the basic sampling clock SC ₀ itself. If the sampling clock SC is twice or four times the reference processing signal SC _0, a new transfer function filter C ^ may be set by appropriately thinning out the filter coefficient according to the multiple.

Next, the operation of this embodiment will be described. That is,
When an engine shake occurs, the shape of the flow path of the orifice 5a is appropriately selected.
Since it functions as a support device for high dynamic spring constant and high damping force, the engine shake generated in the engine 30 is damped by the engine mount 1 and the vibration level on the member 35 side is reduced. In such a case, it is not particularly necessary to displace the movable member 12.

On the other hand, when vibration at a frequency higher than the idle vibration frequency at which the fluid in the orifice 5a becomes a stick state and the fluid cannot move between the main fluid chamber 15 and the sub-fluid 16 is input, the controller 20 executes a predetermined arithmetic processing, outputs a drive signal y to the electromagnetic actuator 13, and causes the engine mount 1 to generate an active control force capable of reducing vibration.

This will be specifically described with reference to FIG. 2, which is a flow chart showing the outline of the processing executed in the controller 20 when the idle vibration and the muffled sound vibration are input.
First, after performing a predetermined initial setting in step 101, the process proceeds to step 102, and the frequency of vibration is calculated based on the generation interval of the reference signal x. When the vibration frequency is calculated, the process proceeds to step 103 and the sampling clock SC is set. Specifically, as described above, it is determined whether the vibration frequency calculated in step 102 is in the low frequency range, the medium frequency range, or the high frequency range,
Based on the result of the judgment, the sampling clock SC is set as follows.

Low frequency band: SC = SC ₀ × 4 Medium frequency band: SC = SC ₀ × 2 High frequency band: SC = SC ₀ × 1 Then, the process proceeds to step 104, and the transfer function filter C
The reference signal R ^T is calculated based on ^. In addition,
In this step 104, the reference signals R ^T for one cycle are collectively calculated.

Here, the transfer function filter C ^ is a digital filter consisting of a series set in advance by sampling the impulse response between the engine mount 1 and the acceleration sensor 22 at intervals of the basic sampling clock SC ₀ . Therefore, as a result of the determination that it is in the high frequency band in step 103,
When the clock SC is set to the basic sampling clock SC ₀ itself, the preset sequence C ^ _j (j = 0, 1, 2, 3, ..., J-1: J is a transfer function) The tap number of the filter C ^) may be used as it is for the calculation of the reference signal R ^T.

However, as a result of the determination in step 103 that the sampling clock SC is in the low frequency band or the medium frequency band, the sampling clock SC becomes the basic sampling clock SC.
_When it is twice or four times _0, the transfer function filter C ^ used for calculation of the reference signal R ^T is set by appropriately thinning out the sequence C ^ _j . Specifically, the sampling clock SC is the basic sampling
In the case of twice the clock SC _0, the even number C ^ _j
Other values are not required, sampling clock SC
Is 4 times the basic sampling clock SC ₀ , no numerical value other than the numerical value C ^ _j that is a multiple of 4 is necessary, so that each of the transfer function filters C ^ used in the calculation of the reference signal R ^{T is} eventually determined. The filter coefficients are as follows.

Low frequency band: C ^ = C ^ ₀ , C ^ ₄ , C ^ ₈ , ..., C ^ _{(J-1) / 4 * 4} Medium frequency band: C ^ = C ^ ₀ , C ^ ₂ , C ^ ₄ , ..., C ^ _{(J-1) / 2 * 2} High frequency band: C ^ = C ^ ₀ , C ^ ₁ , C ^ ₂ , ..., C ^ _J-1 However, [a] is a real number. Represents the integer part of a. And
After shifting to step 105 and clearing the counter i to zero, it shifts to step 106 and outputs the i-th filter coefficient W _i of the adaptive digital filter W as the drive signal y.

When the drive signal y is output in step 106, the process proceeds to step 107, and the timer for measuring the sampling interval is reset and started. Then, when the process proceeds to step 108 and the residual vibration signal e is read, the process proceeds to step 109 and each filter coefficient of the adaptive digital filter W is updated according to the above equation (1).

After the updating process in step 109 is completed, the process proceeds to step 110, and it is determined whether or not the next reference signal x is input. If it is determined that the reference signal x is not input here, After incrementing the counter i in step 111, the process proceeds to step 112 and waits until the measured value of the timer started in step 107 reaches the sampling clock SC. When the measured value of the timer reaches the sampling clock SC in step 112, the process returns to step 106 and the above-described processing is repeated.

However, if it is determined in step 110 that the reference signal x has been input, the process proceeds to step 102 and the above-described processing is repeatedly executed. As a result of repeatedly executing such processing, as shown in FIG. 3, which represents the relationship among the reference signal x, the drive signal y, and the transfer function filter C ^,
From the controller 20 to the engine mount 1,
From the time when the reference signal x is input, the filter coefficients W _i of the adaptive digital filter W are sequentially supplied as the drive signal y at intervals of the sampling clock SC, and each filter coefficient W _i of the adaptive digital filter W is , Is sequentially updated by the above (1) according to the synchronous Filtered-X LMS algorithm, and therefore, after a certain amount of time has passed and each filter coefficient W _i of the adaptive digital filter W has converged to the optimum value, By supplying y to the engine mount 1, idle vibration and muffled sound vibration transmitted from the engine 30 to the member 35 side via the engine mount 1 are reduced. The control force in the engine mount 1 causes the movable member 12 to vibrate by the electromagnetic force generated from the electromagnetic actuator 13, and the vibration causes the inner cylinder 3 to pass through the fluid in the main fluid chamber 15 and the expansion spring of the support elastic body 6. It is obtained by acting as a force between the outer cylinder 7 and the outer cylinder 7.

Moreover, in this embodiment, step 1
The frequency of the vibration is obtained at 02, and the sampling clock SC is switched stepwise so that the high frequency side becomes shorter than the low frequency side in accordance with the frequency of the vibration at step 103. Therefore, the output of the drive signal y is output. The interval becomes relatively long when low-frequency side vibration is input, and relatively short when high-frequency side vibration is input.

Therefore, when the low frequency side vibration is input, the number of drive signals y output in one cycle becomes too large, and the number of filter coefficients W _i of the adaptive digital filter W to be updated becomes large, resulting in an extremely heavy calculation load. Therefore, it is possible to prevent the control accuracy from decreasing due to a large number and the number of drive signal signals y output in one cycle when high frequency vibration is input.

For example, if it is determined in step 103 that the vibration is in the medium frequency band, sampling /
Clock SC is 2 of basic sampling clock SC ₀
Therefore, as shown in FIG. 3, the drive signal y outputs the same value twice as long as the basic sampling clock SC ₀ . On the other hand, in the conventional configuration, since the sampling clock SC is equal to the basic sampling clock SC ₀ regardless of the frequency of vibration, the drive signal y is the basic sampling clock SC ₀ as shown in FIG.
_Since the number of drive signals y output in one cycle increases, the number of filter coefficients W _i of the adaptive digital filter W to be updated increases, and the calculation load increases. It will end up.

That is, according to the configuration of this embodiment, the number of drive signals y output within one cycle falls within a substantially constant range regardless of the frequency of vibration. For example, the length of one cycle is the basic sampling clock SC _0.
If less than 13 times is a high frequency band, 13 times or more and less than 25 times is a medium frequency band, and 25 times or more is a low frequency band, the number of drive signals y to be output in one cycle is low frequency band: 7 or more Frequency band: 7 to 12 High frequency band: 12 or less. Therefore, even if the vibration frequency changes, the calculation load of the controller 20 becomes substantially constant.

Further, in the present embodiment, the sampling clock SC is set to one time the basic sampling clock SC ₀ ,
Since it is set to either double or quadruple, the transfer function identified by the basic sampling clock SC ₀ can be seen from the relationship between the drive signal y and the transfer function filter C ^ shown in FIG. All sampling clocks S are obtained by simply thinning out the filter coefficient of the filter C ^ as necessary.
A transfer function filter C ^ adapted to C can be obtained. Therefore, it is not necessary to perform a troublesome calculation process such as a transfer function identification process, and a large-capacity memory is also unnecessary.
The cost does not increase significantly.

When the vibration frequency becomes high, many filter coefficients of the transfer function filter C ^ must be added to calculate the reference signal R ^T , as compared with the case where the vibration frequency is low. However, it is known that if the number of additions exceeds a certain number, the accuracy will not be significantly affected by addition or non-addition, because of the relationship with the accuracy of the transfer function filter C ^. Therefore, if you set an appropriate upper limit for the number of additions,
The calculation load can be reduced.

Here, in this embodiment, the engine mount 1 constitutes a controlled vibration source, and step 10
The processing of step 4 constitutes the reference processing signal generating means, the processing of steps 106, 111 and 112 constitutes the driving signal generating means, the processing of step 109 constitutes the adaptive processing means, and the processing of step 102 constitutes the frequency detecting means. And the processing of step 103 constitutes sampling / clock switching means.

In the above embodiment, the filter coefficient W _i of the adaptive digital filter W is continuously used from the filter coefficient W ₀ regardless of the frequency of vibration. For example, the reference signal R ^T is calculated. in accordance with the transfer function filter C ^ filter coefficient C ^ _j for use in the low frequency _{band: W = W 0, W 4} , W 8, W 12, ...... in frequency band: W = W _0, W _{2, W 4, W 6,} ...... high frequency _{band: W = W 0, W 1} , W 2, W 3, may be used by thinning out the filter coefficient W _i appropriately so on .... However, even in such a case, since the number of drive signals y output within one cycle falls within a substantially constant range, the update of the adaptive digital filter W is performed by using the filter coefficient W _i that may be output as the drive signal y. It should be done only for.

In the above embodiment, the sampling clock is switched in two stages, but the invention is not limited to this, and it may be in three stages or more, and the sampling clock SC may be the basic sampling clock. It is also arbitrary how many times SC ₀ is set. Furthermore, in the above embodiment, the vibration frequency is detected based on the generation interval of the reference signal x, but the means for detecting the vibration frequency is not limited to this. For example, the rotation of the engine 30 may be changed. You may read from the number.

In the above embodiment, the active vibration control system for a vehicle according to the present invention is provided with the engine 30 to the member 3.
The case where the invention is applied to a so-called active engine mount for reducing the vibration transmitted to the vehicle 5 has been described. However, the application target of the invention is not limited to this, and if it is a periodic vibration, it is applied from a place other than the engine 30. It may be a device for reducing the vibration generated.

Furthermore, the object to be reduced is not limited to vibration, but may be, for example, an active noise control device for a vehicle that actively reduces periodic noise transmitted from the engine 30 into the vehicle interior. . In such a case, a loudspeaker (control sound source) that is driven by a drive signal supplied from the controller to generate a control sound in the vehicle compartment, and a microphone that detects residual noise in the vehicle compartment and outputs the residual noise signal to the controller ( Residual noise detecting means).

[0053]

As described above, according to the present invention,
Depending on the frequency of vibration or noise, the sampling clock is switched so that the high frequency side is shorter than the low frequency side, and the sampling clock that can be switched is the filter coefficient of each transfer function filter. Since it is an integral multiple of the interval on the time axis, it does not cause problems such as a significant increase in cost, but increases the calculation load when inputting low-frequency vibration and high-frequency noise, and increases the high-frequency vibration and high-frequency noise input. There is an effect that it is possible to prevent the deterioration of the control accuracy at the time.

[Brief description of drawings]

FIG. 1 is a sectional view showing a configuration of an embodiment of the present invention.

FIG. 2 is a flowchart showing an outline of processing executed in a controller.

FIG. 3 is a waveform diagram showing a relationship between a reference signal, a drive signal, and a transfer function filter in the present embodiment.

FIG. 4 is a waveform diagram showing a relationship between a reference signal, a drive signal, and a transfer function filter in a conventional example.

[Explanation of symbols]

1 Engine mount (controlled vibration source) 13 Electromagnetic actuator 20 controller 21 pulse generator (reference signal generating means) 22 Accelerometer (Residual vibration detection means) 30 engine (vibration source) 35 members (car body) x Reference signal y drive signal e Residual vibration signal

Front page continued (58) Fields surveyed (Int.Cl. ⁷ , DB name) G10K 11/178 B60R 11/02 F16F 15/02 G05B 13/02 F01N 1/00 F01N 1/06

Claims (2)

(57) [Claims] 1. A control vibration source capable of generating a control vibration that interferes with a periodic vibration emitted from a vibration source and propagating through a vehicle body, and a reference signal composed of an impulse train having the same period as the periodic vibration. A reference signal generating means, a residual vibration detecting means for detecting the vibration after the interference and outputting it as a residual vibration signal, a transfer function filter modeling a transfer function between the control vibration source and the residual vibration detecting means, Reference processed signal generating means for generating a reference processed signal by convolving the reference signal and the filter coefficient of the transfer function filter;
An adaptive digital filter having a variable filter coefficient, and a drive for outputting the filter coefficient of the adaptive digital filter as a drive signal to the controlled vibration source in order at a predetermined sampling clock interval from the time when the latest impulse of the reference signal is generated. Signal generating means, adaptive processing means for updating the filter coefficient of the adaptive digital filter so as to reduce the vibration after the interference based on the reference processed signal and the residual vibration signal, and a frequency for detecting the frequency of the vibration. The sampling clock switching means for switching the predetermined sampling clock so that the high frequency side becomes shorter than the low frequency side based on the frequency of the vibration detected by the frequency detecting means. Means is provided for each filter function of the transfer function filter. Vehicular active vibration control system, characterized in that switches the predetermined sampling clock to be an integral multiple of the interval on the time axis. 2. A control sound source capable of generating a control sound that interferes with a periodic noise emitted from a noise source and transmitted to a vehicle interior, and a reference signal composed of an impulse train having the same period as the periodic noise. Reference signal generating means for generating, residual noise detecting means for detecting the noise after the interference and outputting as a residual noise signal, a transfer function filter modeling a transfer function between the control sound source and the residual noise detecting means, Reference processing signal generating means for generating a reference processing signal by convolving the reference signal and the filter coefficient of the transfer function filter, a filter coefficient variable adaptive digital filter, and a time point when the latest impulse of the reference signal is generated. From the drive signal, the filter coefficient of the adaptive digital filter is sequentially output as a drive signal to the control sound source at a predetermined sampling clock interval from Generating means, adaptive processing means for updating the filter coefficient of the adaptive digital filter so as to reduce the noise after the interference based on the reference processed signal and the residual noise signal, and frequency detection for detecting the frequency of the noise. Means, and sampling clock switching means for switching the predetermined sampling clock so that the high frequency side becomes shorter than the low frequency side based on the frequency of the noise detected by the frequency detecting means, the sampling clock switching means The active noise control device for a vehicle, wherein the predetermined sampling clock is switched so as to be an integral multiple of an interval on the time axis of each filter coefficient of the transfer function filter.