KR19990050658A - Active Noise Vibration Control Method - Google Patents

Abstract

The present invention relates to an active noise control method for controlling vibration noise by eliminating adverse effects of error characteristics such as convergence speed degradation due to delay by introducing a new error. A new error signal is defined instead of the actual error noise signal This is accomplished by moving the filter coefficient in the opposite direction of the slope of the error signal to the filter coefficient based on the minimum descent method so that all the filter coefficients are updated in the direction in which the square of the error signal becomes smaller, So that the adverse influence of the error system characteristic, particularly the convergence speed degradation due to the delay, can be eliminated, and the noise vibration can be effectively controlled.

Description

Active Noise Vibration Control Method

More particularly, the present invention relates to an active noise control method for controlling vibration noise by eliminating an adverse effect of an error system characteristic, in particular, a convergence speed degradation due to delay, by introducing a new error .

Generally, when the vehicle is traveling, the driver receives various vibrations due to the state of the road surface, the tire, the engine, and the rotation of the drive system itself.

Among these vibrations, the vibration generated from the road surface and the tire is transmitted to the suspension, reduced by the vibration characteristics of the suspension itself, and then transmitted to the vehicle body.

This vibration is transmitted through the floor of the car body to the foot of the passenger directly, through the seat to the buttocks and waist, through the handle and by hand, in various forms with uncomfortable vibration.

The vibrations of the engine and the driveline are likewise transmitted to the passenger through the vehicle body.

At this time, if the vibration inputted to the vehicle body and the natural frequency of the body coincide with each other, resonance occurs, which causes various noise and vibration phenomena such as car shake, booming noise and road noise.

The double booming noise is caused by the vibration of the vehicle body and the resonance phenomenon due to the shape of the interior of the vehicle by vibrating the vehicle body due to unbalance of the engine rotation part, impact at the time of explosion, unbalance of the propeller shaft, vibration of the exhaust pipe, The driver 's ears were pressed to hinder the stability and convenience of the vehicle operation.

There have been many studies to prevent the stability and convenience of the vehicle operation due to the noise vibrations of various vehicles as described above. The basic principle is to control the noise vibration by canceling each other with the sound source of the opposite wavelength.

The active noise control feed-forward method generally used for this purpose will now be described with reference to FIG.

In general, the active noise control feed-forward method is used to generate an instantaneous error signal The square of To minimize In this case, Using the steepest descent method which moves the coefficients of the controller filter Lt; RTI ID = 0.0 > And the output signal is output from the noise control speaker The instantaneous error signal Can be expressed by the following equation (1).

In Equation (1) Can be represented as < RTI ID = 0.0 > Is expressed by the following equation (2).

In the above, The controller filter Lt; / RTI > The error meter Lt; / RTI > The error meter of Lt; th >

The instantaneous error signal < RTI ID = 0.0 > Based on the peak descent method, of Th coefficient end The slope for So that all the coefficients are multiplied by the square of the instantaneous error signal So that the instantaneous error signal A signal capable of offsetting And outputs an instantaneous error signal To control the noise vibration.

The length to which the above- In filter of Th coefficient Is expressed by the following equation (3). &Quot; (3) "

In the above, Is the convergence factor.

In addition, On a curved surface The slope for The (Slow time varying) of the following equation (4). &Quot; (4) "

In the above, Is the filtered reference signal and the error model (5) " (5) "

From the above equations (3) and (4), the update equation is expressed by the following equation (6).

Therefore, As an input signal detected from the sensing microphone as shown in Equation (6) To adjust the input signal < RTI ID = 0.0 > ≪ / RTI > So as to control the noise vibration.

In addition, Reference signals, Control speakers, and (6) can also be applied to the case where the error microphone is composed of four error microphones.

In these multiple systems Th error signal Wow Control output of the second control speaker Are expressed by the following equations (7) and (8), respectively.

In the above, The Th reference signal, The Th reference signal Control filter to the first control speaker of Th coefficients, and The Th reference signal Th control sound source.

Also, Th reference signal Control filter to the first control speaker of Weight coefficient Is updated by the maximum descent method as shown in the following Equation (9).

In the above, Lt; The Th speaker Of the predicted error system transfer function up to the first error microphone Th FIR filter coefficient.

In the conventional method as described above, since the slow time-varying assumption is used, there is a problem in that the vibration noise can not be completely controlled due to the degradation of the convergence speed due to the error characteristic due to the inherent characteristic that the convergence speed is limited.

SUMMARY OF THE INVENTION The present invention has been made in order to solve such problems, and it is an object of the present invention to provide an active noise control method capable of controlling vibration noise by eliminating an adverse effect of an error system characteristic, .

According to an aspect of the present invention, a new error signal is defined in place of an actual error noise signal, and the filter coefficient is moved in a direction opposite to the slope of the error signal based on the peak- The coefficients are updated in a direction in which the square of the error signal is reduced and the noise vibration is controlled by the control speaker from the control sound source to a predetermined control sound source so that the adverse influence of the error system characteristic, So that it can be controlled.

FIG. 1 is a block diagram schematically illustrating a method of controlling active noise and vibration according to the present invention,

FIG. 2 is a block diagram schematically illustrating a method of controlling a multi-active noise and vibration according to the present invention,

3 is a block diagram schematically showing a conventional active noise and vibration control method.

Hereinafter, a preferred embodiment of the present invention will be described with reference to the accompanying drawings.

1, Is the reference signal from the noise source sensed by the sensing microphone Is the original noise signal due to the noise source detected in the error microphone, and Is a signal from an error microphone by a control sound source.

In the above, Sampling interval And the actual time is .

And Is a transfer function from the input unit to the error microphone as a target system, Is a transfer function from the controller output to the error microphone output as an error system, Is an error model.

In addition, the filter of the controller for active noise control Generally uses an FIR (Finite Impulse Response) filter or an IIR (Infinite Impulse Response) filter. In the present invention, an FIR filter is used.

This is because when the IIR filter is used as a controller filter, it can be effectively used when the target system has a feedback effect due to acoustic feedback or acoustic reflection, but it has many elements that can become more unstable than when using the FIR filter.

In the present invention, Instead, the newly defined < RTI ID = 0.0 > To minimize the square of In this case, Based on the peak-falling method of moving the coefficients of the controller, .

In Equation (10) The controller filter Lt; / RTI > The error meter Lt; / RTI > The error meter of Lt; th >

The length In filter of Th coefficient Is expressed by the following equation (20). &Quot; (20) "

in this case On a curved surface The slope for Can be summarized as the following equation (30) without the assumption that it is a slow time-variant as in the conventional method.

here Lt; RTI ID = 0.0 > .

Therefore, from equations (20) and (30) Is updated in the same manner as in the conventional method as shown in the following Equation (40).

The difference from Equation (6) in the conventional method in Equation (40) In place There is only one.

Therefore, in Equation 40, Is expressed by Equation (10) and Equation (2) in the above-described conventional method The following equation (50) can be obtained.

As described above, the present invention has an advantage of eliminating the adverse effect of the error system characteristic, particularly the convergence speed degradation due to delay, by introducing a new error.

As shown in FIG. 2, Reference signals, Control speakers, and (40) can also be extended and applied. In this case, the error meter Dogs.

In this case also, Th error signal Instead, a new error signal < RTI ID = 0.0 > In order to minimize the square of the filter coefficient .

In the above, to be.

The update formula of the filter to which this is applied is expressed by the following equation (70).

In the above equation (70) From Equations (7) and (60) Is corrected as follows.

In addition, the present invention introduces a leakage factor so that it can adapt to a time-varying environment more quickly.

That is, there is a fixed optimal value of the weight when the weight of the target system and the reference signal are unchanged at time.

However, when the target system is time-varying or the reference signal is time-varying, the optimal value of the weight that minimizes the residual noise changes every moment.

In this case, updating the weights reflects the effect of forgetting the value of the previous weight so that it can adapt more quickly to the time-varying environment.

This function is possible by multiplying the weight value of all steps by a value smaller than 1, and the update formula at that time is expressed as follows.

In the above, Is a leaky factor that is greater than or equal to 0 and less than 1.

Also, in case of multiple input / output, the leakage factor can be extended and applied. In case of multiple input / output using leaky factor Th reference signal Control filter to the first control speaker of Th coefficient Is updated as follows.

Such a leaky factor contributes to the stability of the controller since it not only provides the controller with characteristics suitable for the time-varying environment, but also serves to reduce the weight continuously.

Also, since the values of the controller are continuously forgotten, the amount of energy passing through the controller is also reduced, thereby reducing the energy required for control.

As described above, according to the present invention, it is possible to eliminate the adverse effect of the error system characteristic, particularly the convergence speed degradation due to the delay, by introducing a new error, thereby effectively controlling the noise vibration.

Claims (10)

Wherein the active noise control method further comprises the step of updating the coefficient of the filter according to an error signal defined as follows instead of the actual error noise signal to control the noise vibration. In the above, The controller filter Order, The error meter Order, The error meter of Lt; th > The active noise vibration control method according to claim 1, wherein the slope of the filter coefficient on the squared curved surface of the defined error signal is summarized as follows, without assuming that the slope is slow. In the above, Is a filtered reference signal. The active noise control method according to claim 1 or 2, wherein the filter coefficient is updated as follows according to the defined error signal. The method of claim 3, wherein in the formula defined above Is expressed as follows: < EMI ID = 1.0 > 4. The method of claim 3, wherein the error signal The actual noise error signal Wherein the active noise control method comprises the steps of: 4. The active noise control method of claim 3, wherein the updated filter coefficient is updated as follows by introducing a leakage factor. In the above, Is a leaky factor that is greater than or equal to 0 and less than 1. A method of controlling a multi-input / output active noise and vibration control method, comprising: updating a coefficient of a filter according to an error signal defined as follows instead of an actual error noise signal to control noise vibration. In the above, The Th reference signal, The Th reference signal Control filter to the first control speaker of Th coefficient, The Th reference signal Th control sound source. 8. The method of claim 7, wherein the filter coefficients are updated as follows according to the defined error signal. 9. The method of claim 8, wherein the error signal The actual noise error signal Wherein the active noise control method comprises the steps of: The active noise control method of claim 8, wherein the updated filter coefficient is updated as follows by introducing a leakage factor. In the above, The Th reference signal Control filter to the first control speaker of Lt; th >