JPH1019657A - Exciting force estimating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To strengthen stability against noises, to enable the obtention of a good estimation result of both amplitude and vibration exciting force duration, and also to enable the adaptation to estimation of continuous exciting force. SOLUTION: When an excitation test is conducted, an already-known load is applied to an exciting force application point A of an apparatus-to-be- measured 11 by using an impulse hammer 12, an acceleration response at a vibration response measuring point B is detected by an acceleration detector 13, and the exciting force of the impulse hammer 12 and the acceleration response are memorized in a first memory device 14. A first computing device 15 computes an impulse response function between the vibration response measuring point B and the exciting force application point A of the apparatus 11 based on the exciting force and the acceleration response at the time of the excitation test memorized in the first memory device 14. A time window processing routine 18 cuts the vibration response into short lengths in a time domain and a second computing device 17, regarding each of them as a transient response to pulse-like exciting force, estimates exciting force, and thereafter a superimposition processing part 19 superimposes them into a continuous waveform.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exciting force estimating apparatus for estimating an exciting force in a device, such as an engine, to which an exciting exciting force acts during operation.

[0002]

2. Description of the Related Art Conventionally, an excitation force estimating apparatus for estimating an excitation force in a device, such as an engine, to which a shocking excitation force acts during operation is configured as shown in FIG. In FIG. 10, a is an impulse response function measurement unit, b is a vibration response measurement unit when the device is operating, c is an excitation force estimation calculation unit,
Using the impulse response function obtained by the impulse response function measuring unit a and the vibration response during operation of the device measured by the vibration response measuring unit b during operation of the device, an excitation force estimation calculation unit c calculates an excitation force estimation value.

In the impulse response function measuring section a, reference numeral 1 denotes a structural system, that is, a device to be measured, when a vibration test is performed, a known load (impulse) is applied to an excitation force application point A by an impulse hammer 2. . In addition, the device under test 1 is provided with an acceleration detector 3 at the vibration response measurement point B,
The acceleration response (acceleration signal) when a load is applied by the impulse hammer 2 is detected. The excitation force of the impulse hammer 2 and the acceleration response detected by the acceleration detector 3 are stored in the first memory device 4 and sent to the first arithmetic device 5. The first arithmetic unit 5 performs an impulse response function calculation based on the input signal,
The impulse response function obtained by this calculation is output to the second memory device 6 of the vibration response measuring section b.

The second memory device 6 stores an acceleration response during operation of the device under test 1 in the acceleration detector 3.
Is detected and stored. Then, the acceleration response and the impulse response function at the time of device operation stored in the second memory device 6 are calculated by the second calculation device 7 of the excitation force estimation calculation unit c.
Is input to

[0005] In the above configuration, the excitation force estimated value is obtained as follows. (1) First, the impulse hammer 2 strikes the excitation force applied point A of the device 1 to be measured, and the excitation force of the impulse hammer 2 and the acceleration response detected by the acceleration detector 3 are temporarily stored in the first memory device 4. Then, the first arithmetic unit 5 calculates an impulse response function.

(2) Next, a vibration response measuring unit b during operation of the device
Detects the acceleration response of the device under measurement 1 during operation by the acceleration detector 3 and stores the measurement data in the second memory device 6.

[0007] (3) The excitation force estimating calculation unit c calculates the impulse response function calculated by the first calculation unit 5 and the acceleration response measurement data measured by the vibration response measurement unit b. To perform an excitation force estimation calculation in the frequency domain.

In the frequency domain, the vibration response of the structural system is represented by the product of the excitation force and the frequency response function of the system. Therefore, the vibration response spectrum X (ω) during the operation of the equipment (representation of the vibration response in the frequency domain) Is divided by the frequency response function H (ω) to obtain a spectrum F of the excitation force applied to the structural system.
Find (ω). Excitation force F obtained in frequency domain
By converting (ω) into the time domain, a time-series waveform f (t) of the excitation force is obtained.

The excitation force estimating and calculating section c comprises a discrete Fourier transformer 7a and a discrete Fourier inverse transformer 7b as shown in FIG. The discrete Fourier transformer 7a is an arithmetic unit that converts time-series data into frequency-domain data. The discrete Fourier transformer 7a includes a vibration response when the device is in operation, a vibration response measurement point B measured in advance by the impulse response function measurement unit a, and an excitation force. The impulse response function between the application points is converted into frequency domain data.

The inverse discrete Fourier transformer 7b has a function of converting the data into time-series data in the frequency domain. By dividing the vibration response spectrum by the frequency response function, an excitation force estimated value spectrum is obtained. By performing an operation by the discrete Fourier inverse transformer 7b on the excitation force estimated value spectrum, the excitation force estimated value is time-series. Asking.

[0011]

FIGS. 12 and 13 show examples of analysis of data measured by the above-mentioned conventional apparatus. 12 and 13 show examples of the frequency response function of the device 1 during hammering. FIG. 12 shows the amplitude (acceleration / force), and FIG. 13 shows the phase (rad). Has a number of resonance points (parts where the amplitude peaks in FIG. 12) and anti-resonance points (parts where the amplitude falls in FIG. 12). In order to accurately determine the excitation force in the frequency domain using the conventional technology, it is necessary to accurately measure these values. Particularly at the anti-resonance point, accurate measurement is often difficult because the amplitude value decreases to the noise level or the dynamic range of the measuring device is limited. That is, at the anti-resonance point, if the amplitude cannot be correctly evaluated due to the influence of noise or the limitation of the dynamic range of the measuring instrument, the phase value in that section becomes indefinite, which causes a large error in the evaluation of the frequency response function. When an excitation force estimated value is calculated using a frequency response function including this error, an error due to the evaluation error occurs in the estimated waveform.

The present invention has been made in order to solve the above-mentioned problems, and has a high stability to noise, a good estimation result in both amplitude and exciting force duration, and a continuous excitation force. An object of the present invention is to provide an excitation force estimation device that can be applied to estimation.

[0013]

SUMMARY OF THE INVENTION The present invention provides an excitation force estimating apparatus for estimating an excitation force applied to a structural system using an impulse response function between a vibration response measurement point of the structural system and an excitation force applied point. And an acceleration detector for detecting a vibration acceleration at a vibration response measurement point of the structural system, and a first memory for storing an acceleration response detected by the acceleration detector and an excitation force signal applied to the structural system during a vibration test. And an impulse response function between the vibration response measurement point and the excitation force applied point of the structural system based on the excitation force and acceleration response during the excitation test stored in the first storage means. First
Calculation means, and second storage means for storing an impulse response function calculated by the first calculation means and an acceleration response at the time of device operation detected by the acceleration detector,
A time window processing means for time-divisionally extracting the acceleration response at the time of device operation stored in the second storage means and sequentially extracting the time-response output from the time window processing means with respect to a pulse-like excitation force; The second excitation means for estimating the excitation force by the complex cepstrum processing and the Kefrensif window processing is superimposed on the partial excitation force estimated by the second arithmetic means to obtain a continuous excitation force estimation value. And a superimposition processing unit for obtaining

The second arithmetic means includes a discrete Fourier transformer for converting the impulse response function stored in the second storage means and the acceleration response during operation of the device into frequency domain data, a frequency response function and a response spectrum. A complex logarithmic converter that takes a complex logarithm of, a discrete Fourier inverse transformer that performs an inverse discrete Fourier transform on a logarithmic spectrum of a response and a logarithmic frequency response function, and converts the complex cepstrum into a window function. Short cfrency region extractor that extracts only short ceffrench data, and complex cepstrum of each of the response and impulse response function subjected to the above window function processing, to obtain a complex cepstrum of the excitation force estimated value, and then perform a Fourier transform Discrete Fourier transformer that transforms to the frequency domain by using A complex exponential converter that, characterized by comprising a discrete inverse Fourier transformer for obtaining a time series excitation force estimate by performing a discrete Fourier inverse transform on the exciting force estimates spectra converted to the antilogarithm.

(Action) A known load is applied to the excitation force applied point of the structural system using an impulse hammer or the like at the time of the vibration test, and the acceleration response at the vibration response measurement point is detected by the acceleration detector. The excitation force and acceleration response are stored in a memory device. The first calculation means calculates an impulse response function between the vibration response measurement point of the structural system and the excitation force applied point based on the excitation force and the acceleration response during the excitation test stored in the memory device. The second calculating means includes a first calculating means.
The impulse response function calculated by the calculation means and the acceleration response at the time of device operation detected by the acceleration detector are converted into data (complex cepstrum) in the quefrency region to estimate the excitation force applied to the structural system. Since the effects of the resonance / anti-resonance of the structural system appear in the long quefrency region of the complex cepstrum, short-path quefrency window processing is performed to remove these effects.

For continuous excitation force estimation, the time window processing means treats the continuous waveform as virtually a continuous shocking waveform, thereby estimating the excitation force by the same processing as described above. Can be. That is,
The vibration response is finely divided in the time domain, and each is regarded as a transient response to the pulse-like excitation force, and the excitation force is estimated by the second calculating means. Then, the estimated virtual shock waveform is superimposed to form a continuous waveform. I do.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a configuration of an excitation force estimation device according to one embodiment of the present invention.

In FIG. 1, a is an impulse response function measuring unit, b is a vibration response measuring unit when the device is operating, c is an excitation force estimation calculating unit, and the impulse response function and the device operating value obtained by the impulse response function measuring unit a. An excitation force estimation calculation unit c calculates an excitation force estimation value using the vibration response during operation of the device measured by the vibration response measurement unit b at the time.

In the impulse response function measuring section a, reference numeral 11 denotes a structural system, that is, a device to be measured. When a vibration test is performed, a known load (impulse) is applied to the excitation force application point A by the impulse hammer 12. . The device under test 11 has an acceleration detector 13 at the vibration response measurement point B.
And an acceleration response (acceleration signal) when a load is applied by the impulse hammer 12 is detected. Exciting force and acceleration detector 13 of the impulse hammer 12
Is stored in the first memory device 14 and sent to the first arithmetic device 15. The first arithmetic unit 15 performs an impulse response function calculation based on the input signal, and outputs the impulse response function obtained by the calculation to the second memory device 16.

In the second memory device 16, an acceleration response during operation of the device under test 11 is detected by the acceleration detector 13 and stored. Then, the acceleration response and the impulse response function at the time of device operation stored in the second memory device 16 are input to the excitation force estimation calculation unit c.

The excitation force estimating operation unit c is a second operation unit 1
7. It comprises a time window processing routine 18 and a superimposition processing unit 19, and receives an impulse response function and an acceleration response during device operation stored in the second memory device 16.

As shown in FIG. 2, the second arithmetic unit 17 includes a discrete Fourier transformer 21, a complex logarithmic converter 22, an inverse discrete Fourier transformer 23, a short Kefrency range extractor 24, a discrete Fourier transformer 25, It comprises an exponential converter 26 and an inverse discrete Fourier transformer 27, and has an arithmetic function for calculating an excitation force estimated value by complex cepstrum calculation and short-pass Kefrensif window processing.

The second arithmetic unit 17 finely divides the vibration response by the time window processing routine 18 and performs complex cepstrum calculation and short-pass Kefrensif window processing by regarding each as a transient response to a pulse-like excitation force. An excitation force estimation value is obtained and output to the superposition processing unit 19. The superimposition processing section 19 superimposes the calculation results of the second calculation device 17 and outputs the results as continuous excitation force estimation values.

Next, the operation of the above embodiment will be described. First, in an impulse response function measuring section a, the impulse hammer 12 strikes the excitation force applied point A of the device under test 11, and the excitation force of the impulse hammer 12 and the acceleration response detected by the acceleration detector 3 are stored in a first memory device. 14, and the first arithmetic unit 15 calculates an impulse response function. This impulse response function is stored in the second memory device 16.

Next, the vibration response measuring unit b during operation of the device measures the acceleration response during operation of the device under measurement 11 by the acceleration detector 13.
And the measurement data is stored in the second memory device 16.

The excitation force estimating calculation unit c is configured to calculate the second impulse response function based on the impulse response function calculated by the first calculation unit 15 and the acceleration response measured by the vibration response measurement unit b. In step 17, an excitation force estimation calculation in the frequency domain is performed.

In this case, for continuous excitation force estimation, the excitation force is estimated by treating the continuous waveform as virtually continuous shocking waveforms using the time window processing routine 18. Can be.

The arithmetic operation of the second arithmetic unit 17 is performed as follows. The impulse response function calculated by the first arithmetic unit 15 and the measurement data of the acceleration response measured by the vibration response measurement unit b are calculated by the discrete Fourier transformer 21
And processed, followed by a complex logarithmic converter 22,
Discrete Fourier inverse transformer 23, short quefrency area extractor 2
4. Processing is sequentially performed by the discrete Fourier transformer 25, the complex exponential converter 26, and the discrete Fourier inverse transformer 27, and the excitation power estimation value is output from the discrete Fourier inverse transformer 27. In this case, the excitation force is estimated by converting the vibration response and the impulse response function into a complex cepstrum ＾ x (τ), which will be described in detail below. The complex cepstrum ＾ x (τ) is given by the inverse Fourier transform of the complex logarithm of the Fourier transform of the time series x (t). The definition formula is as follows

[0029]

(Equation 1) F [...]: Indicated by Fourier transform of [...].

The name of the complex cepstrum is
It was given from the viewpoint that the spectrum was inversely transformed. The complex cepstrum is a function in a domain having the same dimension as time, but is defined as a function in a quefrency domain from the viewpoint of performing an inverse Fourier transform on a function in a frequency domain. An area where the quefrency is close to “0” is called a short quefrency area in association with time, and an area opposite thereto is called a long quefrency area.

Then, the complex cepstrum ＾ x (τ) of the vibration response and the impulse response function is calculated, and a window function process for extracting only the components of the short quefrency region is performed. Since the effect of the resonance / anti-resonance of the frequency spectrum appears in the long quefrency region, this window function processing (the window function in the quefrency region is a quefrency window, and the quefrency window for extracting only the components in the short quefrency region is a short path quefrency window) ) Can reduce the effect of resonance / anti-resonance on the spectrum of both the vibration response / impulse response function.

Since the resonance / anti-resonance of the structural system is due to the reflection of vibrations propagating through the structure, reducing this effect means detecting only the direct response to the excitation force, and therefore The accuracy of the estimation of the shocking excitation force can be improved.

When the complex cepstrum of the impulse response function is calculated, the influence of noise is large near the anti-resonance point of the frequency response function, and the phase value is uncertain. There is. In order to avoid this phenomenon, it is assumed that the impulse response function satisfies the minimum phase condition, and the phase of the frequency response function is determined from the amplitude value.

Since the complex cepstrum of the vibration response is given by the sum of the complex cepstrum of the input and the complex cepstrum of the impulse response function, by taking the difference between the complex cepstrum of the vibration response subjected to the quefrency window process, A complex cepstrum of the excitation force waveform estimated value can be obtained. Then, this is converted into a time series to obtain an excitation force waveform estimated value.

For continuous excitation force estimation, the time window processing routine 18 is used to treat continuous waveforms as continuous shocking waveforms.
Exciting force can be estimated by the same processing. FIG.
FIG. 4 shows a conceptual diagram of time window processing.

The vibration response shown in FIG. 3A is cut short in the time domain as shown in FIG.
As shown in FIG. 6, the excitation response is regarded as a transient response to a pulse-like excitation force, and the excitation force is estimated by complex cepstrum + Kefren shift window processing as shown in FIG. After that, the estimated virtual shock waveform is superimposed by the superimposition processing unit 19 to obtain a continuous waveform shown in FIG.

Next, the processing function of each arithmetic unit for performing the above-described arithmetic operation will be described. The discrete Fourier transformer 21 converts a discrete Fourier transform into an acceleration response at the time of device operation and an impulse response function h ′ (t) between a response measurement point B and an excitation force applied point A measured in advance by the impulse response function measurement unit a. The data is converted to frequency domain data. Although the response is given by convolution of the excitation force and the impulse response of the system in the time domain (ie x (t) = f (t) * h (t)), the excitation force spectrum and the frequency are converted into the frequency domain. Is given by the product of the response functions (ie X (ω)
= F (ω) × H (ω)).

The complex logarithmic converter 22 calculates the response spectrum X
(Ω) and the complex logarithm of the frequency response function spectrum H ′ (ω). The complex logarithm of the response spectrum "＾ X (ω) =
logX (ω) = log | X (ω) | + jφ ”is the sum of the complex logarithm of the excitation force spectrum and the complex logarithm of the frequency response function (ie ＾ X (ω) = ＾ F (ω) + ＾ H ( ω)).

The inverse discrete Fourier transformer 23 generates a logarithmic spectrum ＾ X (ω) of the response and a logarithmic frequency response function ＾ H ′.
(Ω) is subjected to inverse discrete Fourier transform to be converted into data (complex cepstrum) in the quefrency domain. FIG. 4 shows an example of a complex cepstrum of the impulse response function of this structural system. The effect of the resonance of the structural system appears in the long-frequency region.

The short quefrency range extractor 24 performs a window function process for extracting only short quefrency data from the complex cepstrum. Since the width of the window function needs to be changed depending on the target device, it can be input from the outside. FIG.
FIG. 4 shows an example of a complex cepstrum that has been subjected to this window function processing, that is, a quefrency window processing.
Only the data of the short quefrency area is extracted.

The discrete Fourier transformer 25 calculates the complex cepstrum of the excitation force estimated value by calculating the complex cepstrum of each of the response subjected to the window function processing and the impulse response function, and then performs a Fourier transform on the complex cepstrum. Convert to 6 and 7 show examples of the frequency response function subjected to the quefrency window processing, that is, those obtained by transforming the complex cepstrum of FIG. 5 into the frequency domain. FIG. 6 shows the amplitude, and FIG. 7 shows the phase. .

The complex exponential converter 26 converts the complex logarithm of the excitation force estimated value spectrum into an antilog. The inverse discrete Fourier transformer 27 performs an inverse discrete Fourier transform on the excitation force estimation value spectrum to obtain the excitation force estimation value as a time series.

As described above, the second arithmetic unit 17 converts the vibration response and the impulse response function into a complex cepstrum, and estimates the excitation force in the quefrency region. Also,
By using the complex cepstrum + short path kefrensif window processing as shown in the above embodiment, it is possible to remove the influence of resonance / anti-resonance and extract only the direct response, which is effective when identifying a shocking waveform. . Furthermore,
By estimating the virtual impact force by the time window process, the continuous excitation force waveform as shown in FIG. 4 also has a good match compared with the analysis value shown in FIG.
High estimation accuracy can be obtained. FIGS. 4 and 5 show waveforms of the piston slap force as an example.

[0044]

As described above, according to the present invention, even when the amplitude of the frequency response function cannot be measured accurately due to the noise level or the limitation of the dynamic range of the measuring instrument, the influence of resonance / anti-resonance is short-circuited. By removing it by the Pasque frequency window processing, the stability against noise is strong, and a reasonable estimation result can be obtained for both the amplitude and the excitation force duration. Therefore, the excitation force estimating device according to the present invention has excellent functions as compared with the conventional device, and is particularly effective for identifying a shocking excitation force waveform. Furthermore, by estimating a virtual impact force by time window processing, the present invention can be applied to continuous estimation of an excitation force.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an excitation force estimation device according to an embodiment of the present invention.

FIG. 2 is a configuration diagram showing details of a second arithmetic unit in the embodiment.

FIG. 3 is a conceptual diagram of a time window process in the embodiment.

FIG. 4 is a diagram showing an example of a complex cepstrum of an impulse response function of a structural system.

FIG. 5 is a diagram showing an example of a complex cepstrum subjected to a quefrency window process.

FIG. 6 is a diagram showing the amplitude of a frequency response function subjected to a quefrency window process.

FIG. 7 is a diagram showing the phase of a frequency response function subjected to quefrency window processing.

FIG. 8 is a diagram showing an example of an excitation force waveform (piston slap force) obtained by the method of the present invention.

FIG. 9 is a diagram showing an example of an excitation force waveform (piston slap force) obtained by analysis.

FIG. 10 is a block diagram showing a configuration of a conventional excitation force estimation device.

FIG. 11 is a block diagram showing a configuration of a second calculation device of the conventional excitation force estimation device.

FIG. 12 is a diagram illustrating an amplitude of a frequency response function of a structural system in which a minimum phase condition is introduced.

FIG. 13 is a diagram showing a phase of a frequency response function of a structural system in which a minimum phase condition is introduced.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Device to be measured 12 Impulse hammer 13 Acceleration detector 14 1st memory device 15 1st arithmetic device 16 2nd memory device 17 2nd arithmetic device 18 Time window processing routine 19 Superposition processing part 21 Discrete Fourier transformer 22 Complex logarithmic converter 23 Inverse discrete Fourier transformer 24 Short Kefrency range extractor 25 Discrete Fourier transformer 26 Complex exponential converter 27 Discrete Fourier inverse transformer

Claims (2)

[Claims] 1. An excitation force estimating apparatus for estimating an excitation force applied to a structural system using an impulse response function between a vibration response measurement point of the structural system and an excitation force applied point, wherein the vibration response of the structural system is An acceleration detector for detecting a vibration acceleration at a measurement point; first storage means for storing an acceleration response detected by the acceleration detector and an excitation force signal applied to the structural system during a vibration test; First calculating means for calculating an impulse response function between the vibration response measurement point and the excitation force applied point of the structural system based on the excitation force and the acceleration response at the time of the excitation test stored in the storage means; Second storage means for storing the impulse response function calculated by the first arithmetic means and an acceleration response detected by the acceleration detector when the equipment is operating; equipment operation stored in the second storage means Time window processing means for sequentially taking out the acceleration response of each of the above, and each time-sharing output by the time window processing means is regarded as a transient response to a pulse-like excitation force, and is excited by complex cepstrum processing and Kefrensif window processing. A second calculating means for estimating the force, and a superimposition processing unit for superimposing the partial exciting force estimated by the second calculating means to obtain a continuous exciting force estimated value. Excitation force estimation device. 2. A discrete Fourier transformer for converting an impulse response function stored in the second storage means and an acceleration response during operation of the device into data in a frequency domain, a frequency response function and a response. A complex logarithmic converter that takes a complex logarithm with the spectrum, a discrete Fourier inverse transformer that performs an inverse discrete Fourier transform on a logarithmic spectrum of the response and a logarithmic frequency response function, and converts the complex cepstrum, and a window function process on the complex cepstrum. After calculating the complex cepstrum of the excitation force estimated value by calculating the complex cepstrum of each of the response and impulse response function subjected to the window function processing described above, and the Fourier transform, Discrete Fourier Transformer that transforms to frequency domain by transform, and transforms complex logarithm of excitation force spectrum to antilog 2. A discrete exponential converter comprising: a complex exponential converter; and an inverse discrete Fourier transformer for performing an inverse discrete Fourier transform on the exciting force estimated value spectrum converted to an antilog to obtain an excited force estimated value as a time series. The excitation force estimating device according to the above.