JPH06161467A - Vibration reducing device - Google Patents

Abstract

PURPOSE:To adapt the device with simple constitution to high-speed processing by considering the propagation delay of a signal, which is caused by a suppressive vibration generating means and a residual vibration detecting means, by using a simple arithmetic expression. CONSTITUTION:An adaptive digital filter 8 includes a shift register composed of (n) registers 80-8n-1, a selector composed of (n) switches SWO-SWn-1, coefficient multipliers 90 and 91, an adder 93, a coefficient arithmetic part 94, and a delay data memory 95. A storage means is stored with data on the propagation delay caused by the suppressive vibration generating means and residual vibration detecting means as to respective vibration frequencies and 1st and 2nd coefficient data for considering the propagation delay are obtained from a 2nd simple predetermined arithmetic expression by using the propagation data obtained by referring to the storage means. Therefore, the propagation delay is brought into consideration, so the arithmetic quantity is reduced as compared with a conventional example which requires much arithmetic and consequently, the high-speed processing is enabled.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vibration mitigation device, and more particularly to a vibration mitigation device for mitigating a vibration generated from a vibration source by applying a suppressing vibration.

[0002]

2. Description of the Related Art Conventionally, an active noise control device has been known as a device for suppressing noise of a blower and an engine. The active noise control device can suppress noise or vibration by secondarily generating sound waves or vibrations having a phase difference of 180 degrees with the noise or vibration and having the same amplitude, and causing interference. .

Prior art relating to suppression of periodic noise is as follows: (1) "Adaptive Noise Canceling: Pr by WIDROW et al.
The paper entitled "Inciples and Application" (PROCEEDI
NGS OF THE IEEE, VOL.63, NO.12, December, 1975) (2) Tokuhyo 3-501317 (3) Nakaji et al. "Research on active muffled sound control technology focusing on sound field characteristics in vehicle interior , Etc. (Japanese Society of Mechanical Engineers, No.910-52, Symposium Proceedings) are known.

11 and 12 are a vector diagram and a vibration waveform diagram for explaining the principle of active noise control. The present invention and the above prior arts (1) to (3)
In, the principle for active noise control shown in FIGS. 11 and 12 is used.

Referring to FIG. 11, vector V0 indicates the noise emitted from the noise source. Vector V1 indicates the vibration of the noise source. The vector V2 has a phase 9 more than the vector V1.
The vector delayed by 0 degrees is shown. Vector V3 indicates an antiphase added sound that should be added to suppress noise. The coefficients H0 and H1 are used to calculate the antiphase added sound vector V3, and the vectors V1 and V2 are used.
Respectively corresponds to the absolute value of.

FIG. 12 shows the relationship between the vectors V0 to V3 shown in FIG. 11 on the time axis. Referring to FIG. 12, the horizontal axis represents the passage of time in terms of rotation angle (degrees), and the vertical axis represents the sound pressure level. The curve C0 shows the noise, and the curve C1 shows the vibration of the noise source,
The curve C2 shows the vibration of the noise source vibration C1 delayed by 90 degrees, and the curve C3 shows the antiphase added sound.

Generally, the noise vector V0 to be suppressed
Can't know. Therefore, in the principle of active noise control, the vibration vector V1 of the noise source is detected, the vector V2 delayed by 90 degrees from the vector V1 is obtained, and the inverse of the vector V1 and V2 that should be added to suppress noise is determined. The phase-added sound vector V3 is calculated. Antiphase added sound vector V obtained by calculation
On the basis of No. 3, the speaker emits an anti-phase added sound, which reduces the noise level.

[0008]

In the active noise control device disclosed in the above-mentioned prior art examples (1) and (2), the vibration vector (that is, V2) delayed by 90 degrees of the vibration of the noise source is obtained. , Phased Locked
A loop (hereinafter referred to as "PLL") is required, and the circuit is complicated. Further, in the prior art examples (1) and (2), the time delay in the speaker drive path for generating the secondary additional sound was not considered.

On the other hand, in the prior art example (3), an additional digital filter is required because the time delay in the speaker drive path for generating the secondary additional sound is taken into consideration, and they are configured by software. The amount of calculation was large, and as a result, it was not suitable for high speed processing.

The present invention has been made to solve the above problems, and an object thereof is to provide a vibration damping device having a simple structure and suitable for high-speed processing.

[0011]

A vibration damping device according to the present invention comprises a sampling means for sampling the vibrations emitted from a vibration source at a predetermined sampling time interval and outputting sampled vibration data U _n. shifts at predetermined sampling time intervals vibration data U _n outputted from the sampling means, to n pieces of no vibration data U _n-1 delayed shift register means for outputting the U _0, vibration data U _n To U ₀ by applying the first and second vibration data and the first and second coefficient data having a phase difference of approximately 90 degrees to the first predetermined arithmetic expression, the vibration suppression signal is obtained. From the vibration source, the first calculation means for outputting, the suppression vibration generating means for generating the suppression vibration for suppressing the vibration emitted from the vibration source in response to the vibration suppression signal, and the vibration source. Residual vibration detection means for detecting residual vibration that is not suppressed by the suppressed vibration, and storage means for storing propagation delay data of signals generated in the suppressed vibration generation means and the residual vibration detection means for each vibration frequency. A frequency detection means for detecting the frequency of the vibration emitted from the vibration source, propagation delay data in the storage means determined by the frequency detected by the frequency detection means, and residual vibration data detected by the residual vibration detection means. The first and second calculation means for the first calculation means are applied to two predetermined calculation expressions.
Second calculation means for outputting the coefficient data of.

[0012]

In the vibration damping device according to the present invention, the vibration mitigating device
The shift register means is used to obtain the first and second vibration data having a phase difference of degrees, and therefore the configuration can be simplified as compared with the case of using the PLL.
In addition to this, the propagation delay data generated in the suppression vibration generation means and the residual vibration detection means for each vibration frequency is stored in the storage means, and the propagation delay data is obtained by referring to the storage means. The first and second coefficient data for considering
It is obtained by a predetermined arithmetic expression of. Therefore,
Compared with the conventional one, which requires a lot of calculation to consider the propagation delay, the amount of calculation is reduced, and as a result, high speed processing can be achieved.

[0013]

2 is a block diagram of an active noise control system showing an embodiment of the present invention. The example shown in FIG. 2 shows an example in which the present invention is applied to suppress noise emitted from a blower. Referring to FIG. 2, a vibration sensor 12 for detecting vibration of the rotating device 1 is attached to the rotating device 1 which is a power source of the blower. The rotation frequency and the vibration vector of the rotating device 1 are detected via the vibration sensor 12. The detected vibration is given to the A / D converter 9 via the filter 3 provided with an amplifier (not shown).

In the A / D converter 9, vibration is sampled for each predetermined sampling period, and vibration data is given to the adaptive digital filter 8. For example,
Rotating device 1 in the active noise control system shown in FIG.
In the case where the vibration frequency is 250 to 500 Hz, and the sampling time interval is 500 Hz, the number of samplings is 20 at 250 Hz, 5
It becomes 10 at 00 Hz.

A secondary additional sound signal is obtained by the arithmetic processing in the adaptive digital filter 8, and the secondary additional sound signal is given to the speaker 6 via an amplifier (not shown) provided in the filter 5. A secondary additional sound for suppressing noise generated from the rotating device 1 is emitted via the speaker 6.

The error detection microphone 4 detects the residual noise (or error) in which the noise emitted from the rotating device 1 and the secondary additional sound are combined, and gives it to the filter 7. Filter 7
The residual noise signal (or error signal) is given to the adaptive digital filter 8 via the.

FIG. 1 is a block diagram of the adaptive digital filter 8 shown in FIG. Referring to FIG. 1, the adaptive digital filter 8 includes n registers 80 to 8 _n-1.
A shift register constituted by a switch and a selector constituted by _n switches SW0 to SW _n-1
It includes coefficient multipliers 90 and 91, an adder 93, a coefficient calculator 94, and a delay data memory 95.

Each register 80 constituting the shift register
Through 8 _n-1 have a time delay Z ^-1 corresponding to one sampling time interval in the A / D converter 9 shown in FIG. The number of registers corresponding to a time length of 90 degrees is
For example, 5 at 250Hz, 2 or 3 at 500Hz
Equivalent to. In the example shown in FIG. 1, the 90 degree time delay is obtained by the two registers, so that only the switch SW _n-2 is turned on. Note that FIG.
Although the switches SW0 to SW _n-1 are used in the example shown in Fig. 1, when the adaptive digital filter 8 shown in Fig. 1 is entirely configured by software, the switches SW0 to SW _n-1 are also software. And is functionally fulfilled as a switch.

Switches SW0 to SW in the selector
_{When one} of _n-1 is turned on, one of the delayed noise data U ₀ to U _n-1 is given to the coefficient multiplier 90 or the coefficient calculator 94. The undelayed noise data U _n is given to the coefficient multiplier 91.

The coefficient multiplier 91 multiplies the vibration data U _n by the coefficient H1 and gives the multiplied data to the adder 93. The coefficient multiplier 90 uses the delayed vibration data U ₀ to U
_{One of n-1} is multiplied by the coefficient H0, and the multiplied data is given to the adder 93. The adder 93 adds the two given multiplication data and outputs the addition data as a secondary additional sound signal Y.

The coefficient calculator 94 performs an operation for updating the coefficients H0 and H1 used in the operations in the coefficient multipliers 90 and 91. The delay data memory 95 has 2
Data regarding the propagation delay of the signal in the next additional sound generation path is stored for each vibration frequency. Delay data memory 9
The data stored in 5 is used in the calculation process for updating the coefficient in the coefficient calculation unit 94.

The basic operation for noise suppression control is performed using the shift register, selector, coefficient multipliers 90 and 91, and adder 93. That is, _assuming that the noise data delayed by 90 degrees with respect to the current noise data U _n is U _n−2 , the switch SW shown in FIG.
_n-2 is turned on and therefore coefficient multipliers 90 and 91
, The vibration data U _n−2 delayed by 90 degrees and the current vibration data U _n are respectively given. Therefore, the coefficient multipliers 90 and 91 and the adder 93 perform the calculation according to the following equation, and the output signal Y of the adder 93 is output as a secondary additional sound signal.

Y = U _n * H1 + U _n-2 * H0 (1) As a result, the antiphase additional sound vector V3 is obtained as the secondary additional sound signal Y based on the principle diagram shown in FIG.
Based on the secondary additional sound signal Y, the secondary additional sound for suppressing noise is emitted from the speaker 6.

In the coefficient calculation unit 94 shown in FIG. 1, the calculation processing represented by the following equation is performed to update the coefficient.

H1 = H1′-2 * α * U _nm * E (2) H0 = H0′-2 * α * U _n-2-m * E (3) The above formula (2) and In (3), the coefficients H1 and H0
Indicates the updated coefficient, and the coefficients H1 'and H0' indicate the old coefficient before being updated. Further, α is a small positive value (for example, 0.01), and E corresponds to error data (residual noise data) detected by the sensor 4 shown in FIG.

The data m is stored for each vibration frequency in the delay data memory 95 shown in FIG. Since the delay time length of the signal in the generation path of the secondary additional sound is changed according to the frequency of the noise, the delay data memory 95
The data m is read out according to the noise frequency.

In the above equation (1), it is assumed that the vibration data delayed by 90 degrees with respect to the input vibration data U _n is output from the register 8 _n-2 shown in FIG. In other words, it is assumed that the 90 degree delay is obtained via two registers. Further, α is determined by the stability or responsiveness of the system required in the noise control system.

FIG. 3 shows the relationship between the delay time difference between the two vibration data used in the adaptive digital filter shown in FIG. 1 and the number of updates of the coefficient required for the error (residual noise) to converge stably. It is a graph. Referring to FIG. 3, the horizontal axis represents the delay time difference (degree) between the two vibration data, and the vertical axis represents the number of updates of the coefficient required for stable convergence. As can be seen from FIG. 3, it is most preferable that the delay time difference is 90 degrees in order to stably converge the coefficients in a short time, but it is not always necessary to fix it to 90 degrees, and it is not necessary to fix it to about 80 degrees to 100 degrees. Within the range, the time required for convergence does not change much. Therefore, it is sufficient that the delay time difference between the current vibration data U _n and its 90-degree delay data (U _{n-2 in} the example shown in FIG. 1) is set to about 90 degrees.

FIG. 4 is a flow chart showing the arithmetic processing flow in the adaptive digital filter shown in FIG. Referring to FIG. 4, in step 21, the vibration data is shifted by the shift register shown in FIG.
Therefore, after one sampling time interval has elapsed, the current vibration data U _n is output as the delayed vibration data U _n-1 . At the same time, new vibration data U _n is input to the first register 8 _n-1 .

In step 22, the delay data memory 95 is referenced. That is, the delay data memory 95 is referenced using the current vibration frequency, and the data m is read.

In step 23, new coefficients H1 and H0 are calculated by applying the data m to the above equations (2) and (3).

In step 24, the new coefficients H1,
By applying H0 to the above equation (1), the secondary additional sound data Y is obtained by calculation.

In step 25, the secondary additional sound is generated from the speaker 6 based on the obtained secondary additional sound data Y.

The process after step 25 returns to step 21, and the processes of steps 21 to 25 are repeated. As a result, the two coefficients H1 and H0 both converge to 0,
Control for noise suppression is performed.

FIG. 5 is a graph showing the progress of updating the coefficients H1 and H0 updated by the equations (2) and (3). Referring to FIG. 5, the horizontal axis represents the change in coefficient H1, and the vertical axis represents the change in coefficient H0. As can be seen from FIG. 5, both the coefficients H1 and H0 quickly converge.

FIG. 6 is a graph showing changes in the level of the error data E corresponding to the updating of the coefficients H1 and H0 shown in FIG. With reference to FIG. 6, the horizontal axis represents the number of updates of the coefficients H1 and H0, and the vertical axis represents the error E (decibel).
In FIG. 6, the error E before updating the coefficient is 0 dB. As can be seen from FIG. 6, the error E is stably converging.

FIG. 7 is a graph showing the process of updating the coefficients H1 and H0 when the equation (2) and the data m in the addition are not considered. In the example shown in FIG. 7, the delay time difference is also shifted by one register shown in FIG.
1, H0 changes unstablely, and it takes a long time to converge.

FIG. 8 is a graph showing changes in the level of the error data E corresponding to the updating of the coefficients H1 and H0 shown in FIG. As can be seen by comparing FIG. 8 with FIG. 6, the error E
Can be temporarily large and therefore unstable,
It can be seen that the time required for convergence is long.

In the following description, the data m to be stored in the delay data memory 95 will be described. As described above, the propagation delay that changes according to the vibration frequency occurs in the generation path of the secondary additional sound. Therefore, this propagation delay is measured in advance and the propagation delay data is stored in the delay data memory 95.

More specifically, in the measurement mode, the sine wave signal is output as the signal Y from the adaptive digital filter 8 shown in FIG. 2, and the filter 5, the speaker 6, the microphone 4, and the filter 7 shown in FIG. The delay time of the signal in the path returning to the adaptive digital filter 8 via is measured. The delay caused in this path includes the air propagation delay from the speaker 6 to the microphone 4. Also, because filters 5 and 7 include amplifiers (not shown), these delays are also included in the measurement. The delay time in the above path is measured for each vibration frequency.

For example, assuming that the sampling frequency of the vibration data U is 5000 Hz, the delay time length by one register shown in FIG. 1 is 200 μsec. Therefore, if a 500 Hz sine wave signal is generated as the output signal Y and the time delay in the above path is measured, the measurement result shown in FIG. 9 is obtained.

Referring to FIG. 9, the horizontal axis represents the frequency (kHz) of the sine wave signal, and the vertical axis represents the delay time (msec). The delay time here is defined between the signal Y (sine wave signal) and the error signal E as shown in FIG.

Therefore, when the data m to be used in the equations (2) and (3) is obtained in consideration of the delay time for each frequency, the data shown in the following Table 1 is obtained as an example. This data is stored in the delay data memory 95 shown in FIG.

[0044]

[Table 1]

Therefore, since the data shown in Table 1 is stored in the delay data memory 95, the coefficients H1 and H0 are calculated based on the vibration frequency when the equations (2) and (3) are used. The data m is read by using the read data m, and an operation is performed using the read data m.

As described above, in the active noise control system shown in FIG. 2, the adaptive digital filter 8 shown in FIG.
With, the vibration data with a time delay of 90 degrees can be obtained via a simple structure, ie a shift register. In addition to this, since the propagation delay of the signal in the secondary additional sound generation and the residual noise detection path can be easily considered by using the equations (2) and (3), a small amount of calculation is required, and therefore, it is suitable for high-speed processing. An active noise control system is obtained.

In the above embodiments, the present invention is applied to the active noise control system, but it is pointed out that the present invention can be widely applied to the vibration damping device for suppressing the vibration generated from the vibration source. To be done.

[0048]

As described above, according to the present invention, the shift register means is used to provide a phase difference of approximately 90 degrees.
Since one vibration data can be obtained and the propagation delay of the signal generated in the suppressed vibration generating means and the residual vibration detecting means can be taken into consideration by using a simple arithmetic expression, the vibration relaxation suitable for high-speed processing is simple. The device is obtained.

[Brief description of drawings]

FIG. 1 is a block diagram of an adaptive digital filter used in the active noise control system shown in FIG.

FIG. 2 is a block diagram of an active noise control system showing an embodiment of the present invention.

FIG. 3 is a graph showing a relationship between a delay time difference between two vibration data used in the adaptive digital filter shown in FIG. 1 and the number of update times of coefficients required for the error to converge stably.

FIG. 4 is a flowchart of a calculation process in the adaptive digital filter shown in FIG.

FIG. 5 is a graph showing the progress of updating the coefficients H1 and H0 updated by the arithmetic expressions (2) and (3).

6 is a graph showing a change in error E corresponding to the updating of the coefficient shown in FIG.

FIG. 7 is a graph showing the progress of updating the coefficients H1 and H0 when the data m in the arithmetic expressions (2) and (3) is not considered.

8 is a graph showing a change in error E corresponding to the updating of the coefficient shown in FIG.

FIG. 9 is a graph showing a measurement result between a vibration frequency and a time delay occurring in a secondary additional sound generation and a residual noise detection path.

10 is a graph defining the delay time shown in FIG.

FIG. 11 is a vector diagram for explaining the principle of active noise control.

FIG. 12 is a vibration waveform diagram for explaining the principle of active noise control.

[Explanation of symbols]

1 Rotating Device 2 Vibration Sensor 3, 5, 7 Filter 4 Error Detection Microphone 6 Speaker 8 Adaptive Digital Filter 9 A / D Converter 90, 91 Coefficient Multiplier 93 Adder 94 Coefficient Calculation Unit 95 Delay Data Memory 80 to 8 _n-1 register SW0 to SW _n-1 switch U, U _n to U ₀ Vibration data E Error signal Y Secondary additional sound signal

Claims (1)

[Claims] 1. A vibration mitigation device for mitigating vibration emitted from a vibration source, comprising: sampling means for sampling vibration at a predetermined sampling time interval, and outputting sampled vibration data U _n ; The vibration data U _n output from the means is shifted at the predetermined sampling time interval,
shift register means for outputting n pieces of delayed vibration data U _n-1 to U ₀ , first and second vibration data having a phase difference of approximately 90 degrees among the vibration data U _n to U ₀ , and A first calculation means for outputting a vibration suppression signal by applying the first and second coefficient data to a first predetermined calculation expression; and a signal generated from the vibration source in response to the vibration suppression signal. Suppressed vibration generating means for generating suppressed vibration for suppressing the generated vibration, residual vibration detection means for detecting residual vibration not suppressed by the suppressed vibration among the vibrations emitted from the vibration source, and for each vibration frequency Storage means for storing propagation delay data of signals generated in the suppressed vibration generation means and the residual vibration detection means, and a frequency for detecting a frequency of vibration emitted from the vibration source. The detection means and the propagation delay data in the storage means determined by the frequency detected by the frequency detection means and the residual vibration data detected by the residual vibration detection means are applied to a second predetermined arithmetic expression. By doing the first
And a second arithmetic means for outputting the first and second coefficient data for the arithmetic means of.