Method for reducing uncertainty based on seismic interference mode identification and global measurement

Abstract

The invention belongs to the technical field of structural health monitoring, and particularly relates to an uncertainty reduction method based on seismic interference mode recognition and global measurement. The method comprises the following steps of: erecting high-speed image recording equipment in front of a tested beam body by adopting a three-axis holder, acquiring a lateral deformation time sequence image when the tested beam body is subjected to transverse excitation, constructing a structure global displacement field based on the time sequence image, and realizing accurate conversion from pixel coordinates to engineering data; the method comprises the following steps: obtaining an impulse response function of a tested beam body based on an earthquake interference method, determining a time domain theoretical model of the earthquake interference method, and solving modal parameters of the time domain theoretical model of the earthquake interference method by using a least square method, thereby improving the accuracy of modal parameter identification, reducing the uncertainty in modal parameter identification, and improving the accuracy of modal parameter identification. The spatial resolution of structural modal identification is improved, and dense measurement of vibration modes is realized.

Description

Technical Field

[0001] The present invention belongs to the technical field of structural health monitoring, and in particular relates to an uncertainty reduction method based on seismic interferometry mode identification and global measurement. Background Art

[0002] Modal parameters are crucial for identifying structural damage and determining service status, directly reflecting the dynamic characteristics and performance of a structure. In modern structural health monitoring systems, seismic interferometry, based on wave theory, has become an important tool for modal parameter identification due to its ability to decouple soil-structure interactions and its high robustness. Specifically, this method extracts the system's impulse response function to determine the dynamic characteristics of a structure. However, in practical applications, the accuracy and uncertainty of seismic interferometry are limited by factors such as the number of samples, sensor network density, and measurement noise levels.

[0003] An effective way to reduce uncertainty is to increase the number of measurement points. However, traditional sensors (such as accelerometers and strain gauges) have limitations in terms of cost and technology: on the one hand, the cost of multi-channel synchronous measurement is very high, and on the other hand, the installation of the sensor itself also disturbs the structural characteristics. At the same time, it is difficult to deploy a sufficient number of contact sensors in an engineering environment to achieve ultra-high-density measurement, resulting in a sparse sensor topology layout, which is difficult to meet the actual needs of uncertainty control. Therefore, the shortcomings of existing technologies can be summarized as follows: (1) low spatial resolution of modal parameters; (2) large uncertainty in parameter identification.

[0004] Therefore, an uncertainty reduction method based on seismic interferometry mode identification and full-domain measurement is urgently needed to solve the above problems. Summary of the Invention

[0005] The purpose of the present invention is to provide an uncertainty reduction method based on seismic interferometry modal identification and global measurement, aiming to improve the accuracy of modal parameter identification, reduce the uncertainty in modal parameter identification, improve the spatial resolution of structural modal identification, and realize dense measurement of vibration modes.

[0006] The purpose of the present invention can be achieved through the following technical solutions: A method for reducing uncertainty based on seismic interferometry mode identification and global measurement, the method comprising: A high-speed image recording device is set up in front of the beam under test using a three-axis pan-tilt platform to collect time-series images of the lateral deformation of the beam under test when it is subjected to lateral excitation. The optical axis of the high-speed image recording device is orthogonal to the lateral deformation plane. Constructing the global displacement field of the structure based on time-series images to achieve accurate conversion from pixel coordinates to engineering data; Based on the seismic interferometry method, the impulse response function of the tested beam is obtained, the time domain theoretical model of the seismic interferometry method is determined, and the modal parameters of the time domain theoretical model of the seismic interferometry method are solved using the least squares method.

[0007] Furthermore, before collecting the time-series images of the lateral deformation of the beam under test when subjected to lateral excitation, the method further includes: Adjust the shooting angle and focal length so that the lens image and the deformation surface are completely aligned, and turn on the camera's video function; use the actual measured object size and the number of pixels in the photo to determine the spatial calibration coefficient p in mm / pixel.

[0008] Furthermore, constructing the global displacement field of the structure based on time-series images specifically includes the following processes: Based on the principle of optical flow motion estimation: ; Sub-pixel motion vectors , Represents location information, is the time information, is the light intensity of the reference frame, is the light intensity after deformation of the measured object. Combined with the pre-calibrated spatial conversion coefficient p, the discrete pixel displacement data is mapped to the physical coordinate system, and finally a global displacement field with engineering dimensions is generated, where is the reference motion vector.

[0009] Furthermore, obtaining the impulse response function of the measured beam based on the seismic interferometry method specifically includes the following process: The impulse response function of the measured beam is obtained based on the seismic interferometry method: ; in, is the impulse response function, represents the displacement of the structural motion trajectory field, Indicates the reference point The displacement, is the inverse Fourier transform, * represents the complex conjugate, and the regularization parameter is introduced It is intended to stabilize computations by preventing division by zero instabilities.

[0010] Furthermore, determining the time domain theoretical model of seismic interferometry specifically includes the following processes: The time domain theoretical model of seismic interferometry is determined to be the superposition of orthogonal modal fields: ; in is the time domain theoretical model expression of seismic interferometry, is the position of the structural motion trajectory field, is the reference sensor position, For time, is the height of the object being measured, is the shear wave velocity, is the damping ratio, is the modal order, For the order of frequency, where the damping ratio and quality factor exist relationship, in which is the quality factor.

[0011] Furthermore, the least squares method is used to solve the modal parameters of the time domain theoretical model of seismic interferometry, which specifically includes the following process: Constructing the residual function The residual function is defined as the error between the observed data and the model prediction value: r(t)=y(t)-f(p,t) Where: y(t) is the observed signal vector; f(p,t) is the model prediction signal, P is the modal parameter, and the modal parameter is The frequency and damping ratio of the order, r(t) is the residual vector; The objective function is to minimize the residual sum of squares: ; in, is the modulus value of r(t), M is the number of sampling points; Solve the minimization problem using an optimization algorithm: .

[0012] Furthermore, combined with the pre-calibrated spatial conversion coefficient p, the discrete pixel displacement data is mapped to the physical coordinate system, and finally a global displacement field with engineering dimensions is generated. The specific process includes the following: for the contour edges and surface texture feature areas of the component, features with significant grayscale gradients are extracted, the movement trajectory of the points is tracked using an image analysis algorithm, and then the physical displacement time history is converted using the spatial conversion coefficient p.

[0013] Compared with the existing solutions, the present invention achieves the following beneficial effects: The present invention uses a three-axis pan-tilt head to set up a high-speed image recording device in front of the measured beam, collects time-series images of the lateral deformation of the measured beam when it is subjected to lateral excitation, constructs the global displacement field of the structure based on the time-series images, and realizes the accurate conversion of pixel coordinates to engineering data; based on the seismic interferometry method, the impulse response function of the measured beam is obtained, the time-domain theoretical model of the seismic interferometry method is determined, and the modal parameters of the time-domain theoretical model of the seismic interferometry method are solved using the least squares method, thereby improving the accuracy of modal parameter identification, reducing the uncertainty in modal parameter identification, improving the spatial resolution of structural modal identification, and realizing dense measurement of vibration modes.

[0014] Compared with the existing modal identification measurement method, instead of using sparse sensors, the global displacement measurement method is directly used to realize global dense modal parameter identification. At the same time, compared with the existing modal identification method, the present invention not only decouples the soil-structure interaction through seismic interferometry, but also significantly reduces the uncertainty in modal parameter identification. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments described in the present invention. For ordinary technicians in this field, other drawings can also be obtained based on these drawings.

[0016] Figure 1 1 is a flow chart of an uncertainty reduction method based on seismic interferometry mode identification and global measurement according to an embodiment of the present invention; Figure 2 2. It is a schematic diagram showing the result of the frequency recognition accuracy as the measurement points increase according to the embodiment of the present invention; Figure 3 3 is a schematic diagram comparing the vibration mode identification results of an embodiment of the present invention with the theoretical values. DETAILED DESCRIPTION

[0017] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0018] In addition, the described features, structures or characteristics can be combined in any suitable manner in one or more example embodiments. In the following description, many specific details are provided to provide a full understanding of the example embodiments of the present disclosure. However, those skilled in the art will appreciate that the technical solutions of the present disclosure can be practiced while omitting one or more of the specific details, or other methods, components, steps, etc. can be adopted. In other cases, well-known structures, methods, implementations or operations are not shown or described in detail to avoid obscuring various aspects of the present disclosure.

[0019] The following uses the vibration measurement of a cantilever beam structure as an example to illustrate the implementation steps of the proposed method for reducing uncertainty in seismic interferometry modal identification based on full-field measurement. First, the measurement conditions are described: the cantilever beam is the object of measurement, the excitation method is excitation from a bottom vibration table, and the excitation signal is a broadband signal.

[0020] Figure 1 is a flow chart of an uncertainty reduction method based on seismic interferometry mode identification and global measurement according to an embodiment of the present invention. Figure 1 As shown, the method includes the following steps: A high-speed imaging device was mounted in front of the beam under test using a three-axis gimbal, with the optical axis perpendicular to the vibration plane for observation. The recording system used a Sony PXW-FS5M2 professional camera equipped with a 24mm fixed-focus optical system. The image sensor has an effective capture area of 2.07 million pixels (1920×1080 array), and a 120Hz sampling rate for motion capture, achieving 8-bit bit depth per frame. This setup fully records the lateral deformation response of the beam under lateral excitation, ensuring perfect coplanarity between the measurement plane and the imaging coordinate system by adjusting the pitch angle.

[0021] Adjust the shooting angle and focal length so that the lens image and the deformation surface are completely aligned, and turn on the camera's video function; use the actual measured object size and the number of pixels in the photo to determine the spatial calibration coefficient p in mm / pixel.

[0022] For the contour edge and surface texture feature areas of the component, features with significant grayscale gradients are extracted, and the movement trajectory of the points is tracked using an image analysis algorithm. The physical displacement time history is then converted using the spatial conversion coefficient p: The construction of the global displacement field of the structure based on time-series images specifically includes the following processes: Based on the principle of optical flow motion estimation: ; Sub-pixel motion vectors , Represents location information, is the time information, is the light intensity of the reference frame, is the light intensity after deformation of the measured object. Combined with the pre-calibrated spatial conversion coefficient p, the discrete pixel displacement data is mapped to the physical coordinate system, and finally a global displacement field with engineering dimensions is generated, where is the reference motion vector.

[0023] The specific process of obtaining the impulse response function of the measured beam based on the seismic interferometry method includes the following steps: The impulse response function of the measured beam is obtained based on the seismic interferometry method: ; in, is the impulse response function, represents the displacement of the structural motion trajectory field, Indicates the reference point The displacement, is the inverse Fourier transform, * represents the complex conjugate, and the regularization parameter is introduced It is intended to stabilize computations by preventing division by zero instabilities.

[0024] Determining the time domain theoretical model of seismic interferometry specifically includes the following processes: The time domain theoretical model of seismic interferometry is determined to be the superposition of orthogonal modal fields: ; in is the time domain theoretical model expression of seismic interferometry, is the position of the structural motion trajectory field, is the reference sensor position, For time, is the height of the object being measured, is the shear wave velocity, is the damping ratio, is the modal order, For the order of frequency, where the damping ratio and quality factor exist relationship, in which is the quality factor.

[0025] The use of the least squares method to solve the modal parameters of the time domain theoretical model of seismic interferometry specifically includes the following process: Constructing the residual function The residual function is defined as the error between the observed data and the model prediction value: r(t)=y(t)-f(p,t) Where: y(t) is the observed signal vector; f(p,t) is the model prediction signal, P is the modal parameter, and the modal parameter is The frequency and damping ratio of the order, r(t) is the residual vector; The objective function is to minimize the residual sum of squares: ; in, is the modulus value of r(t), M is the number of sampling points; Solve the minimization problem using an optimization algorithm: .

[0026] In summary, the present invention uses a three-axis pan-tilt head to set up a high-speed image recording device in front of the measured beam, collects time-series images of the lateral deformation of the measured beam when it is subjected to lateral excitation, constructs the global displacement field of the structure based on the time-series images, and realizes the accurate conversion of pixel coordinates to engineering data; based on the seismic interferometry method, the impulse response function of the measured beam is obtained, the time-domain theoretical model of the seismic interferometry method is determined, and the modal parameters of the time-domain theoretical model of the seismic interferometry method are solved using the least squares method, thereby improving the accuracy of modal parameter identification, reducing the uncertainty in modal parameter identification, improving the spatial resolution of structural modal identification, and realizing dense measurement of vibration modes.

[0027] In some embodiments, in order to verify the advantages of the full-area measurement method, modal parameters are identified by using different numbers of measurement points and the identified uncertainties are given. Figure 2 FIG. 1 is a schematic diagram showing the result of the frequency recognition accuracy of an embodiment of the present invention increasing with the increase of the measurement points. Figure 2 As shown in the figure, the recognition accuracy of the global parameter (frequency) increases with the number of measurement points, while its uncertainty (variance) increases with the number of measurement points. It can be clearly concluded that global measurement has a significant effect on reducing uncertainty.

[0028] In some embodiments, Figure 3 FIG. 1 is a schematic diagram comparing the vibration mode recognition results of an embodiment of the present invention with the theoretical values. Figure 3 As shown in the figure, the local parameters (mode shapes) have high accuracy and extremely high spatial resolution, which can provide a good basis for subsequent damage identification.

[0029] In summary, compared with the existing modal identification measurement method, instead of using sparse sensors, the global displacement measurement method is directly used to realize global dense modal parameter identification. At the same time, compared with the existing modal identification method, the present invention not only decouples the soil-structure interaction through seismic interferometry, but also significantly reduces the uncertainty in modal parameter identification.

[0030] The above embodiments can be implemented in whole or in part via software, hardware, firmware, or any other combination. When implemented using software, the above embodiments can be implemented in whole or in part in the form of a computer program product. The computer program product comprises one or more computer instructions or computer programs. When loaded or executed on a computer, the processes or functions described in the embodiments of this application are fully or partially generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, the computer instructions can be transmitted from one website, computer, server, or data center to another website, computer, server, or data center via wired means (e.g., infrared, wireless, microwave, etc.). The computer-readable storage medium can be any available medium accessible by a computer or a data storage device such as a server or data center that contains a collection of one or more available media. The available medium can be magnetic media (e.g., floppy disks, hard disks, tapes), optical media (e.g., DVDs), or semiconductor media. The semiconductor media can be a solid-state drive.

[0031] Those skilled in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0032] Those skilled in the art will clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and units described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0033] In the several embodiments provided in this application, it should be understood that the disclosed systems, devices and methods can be implemented in other ways. For example, the device embodiments described above are merely schematic. For example, the division of the units is only for some logical functions. In actual implementation, there may be other division methods, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0034] The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed across multiple network units. Some or all of these units may be selected to achieve the purpose of this embodiment according to actual needs.

[0035] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of this application. Therefore, the scope of protection of this application should be based on the scope of protection of the claims.

Claims

1. A method for reducing uncertainty based on seismic interferometry mode identification and global measurement, characterized in that: Methods include: A high-speed image recording device is set up in front of the beam under test using a three-axis pan-tilt platform to collect time-series images of the lateral deformation of the beam under test when it is subjected to lateral excitation. The optical axis of the high-speed image recording device is orthogonal to the lateral deformation plane. Constructing the global displacement field of the structure based on time-series images to achieve accurate conversion from pixel coordinates to engineering data; Based on the seismic interferometry method, the impulse response function of the tested beam is obtained, the time domain theoretical model of the seismic interferometry method is determined, and the modal parameters of the time domain theoretical model of the seismic interferometry method are solved using the least squares method.

2. The uncertainty reduction method based on seismic interferometry mode identification and global measurement according to claim 1, characterized in that: Before acquiring the time-series images of the lateral deformation of the beam under test when subjected to lateral excitation, the method further includes: Adjust the shooting angle and focal length so that the lens image and the deformation surface are completely aligned, and turn on the camera's video function; use the actual measured object size and the number of pixels in the photo to determine the spatial calibration coefficient p in mm / pixel.

3. The uncertainty reduction method based on seismic interferometry mode identification and global measurement according to claim 1, characterized in that: Constructing the global displacement field of the structure based on time-series images The following processes are included: Based on the principle of optical flow motion estimation: ; Sub-pixel motion vectors , Represents location information, is the time information, is the light intensity of the reference frame, is the light intensity after deformation of the measured object. Combined with the pre-calibrated spatial conversion coefficient p, the discrete pixel displacement data is mapped to the physical coordinate system, and finally a global displacement field with engineering dimensions is generated, where is the reference motion vector.

4. The uncertainty reduction method based on seismic interferometry mode identification and global measurement according to claim 1, characterized in that: The impulse response function of the tested beam is obtained based on the seismic interferometry method. The following processes are included: The impulse response function of the measured beam is obtained based on the seismic interferometry method: ; in, is the impulse response function, represents the displacement of the structural motion trajectory field, Indicates at the reference point The displacement, is the inverse Fourier transform, * represents the complex conjugate, and the regularization parameter is introduced It is intended to stabilize computations by preventing division by zero instabilities.

5. The uncertainty reduction method based on seismic interferometry mode identification and global measurement according to claim 1, characterized in that: Determining the time domain theoretical model of seismic interferometry specifically includes the following processes: The time domain theoretical model of seismic interferometry is determined to be the superposition of orthogonal modal fields: ; in is the time domain theoretical model expression of seismic interferometry, is the position of the structural motion trajectory field, is the reference sensor position, For time, is the height of the object being measured, is the shear wave velocity, is the damping ratio, is the modal order, For the order of frequency, where the damping ratio and quality factor exist The relationship among them, is the quality factor.

6. The uncertainty reduction method based on seismic interferometry mode identification and global measurement according to claim 5, characterized in that: The use of the least squares method to solve the modal parameters of the time domain theoretical model of seismic interferometry specifically includes the following process: Constructing the residual function The residual function is defined as the error between the observed data and the model prediction value: r(t)=y(t)-f(p,t) Where: y(t) is the observed signal vector; f(p,t) is the model prediction signal, P is the modal parameter, and the modal parameter is The frequency and damping ratio of the order, r(t) is the residual vector; The objective function is to minimize the residual sum of squares: ； in, is the modulus value of r(t), M is the number of sampling points; Solve the minimization problem using an optimization algorithm: 。 7. The uncertainty reduction method based on seismic interferometry mode identification and global measurement according to claim 3, characterized in that: Combined with the pre-calibrated spatial conversion coefficient p, the discrete pixel displacement data is mapped to the physical coordinate system, and finally a global displacement field with engineering dimensions is generated. The specific process includes the following: for the contour edges and surface texture feature areas of the component, features with significant grayscale gradients are extracted, the movement trajectory of the points is tracked using an image analysis algorithm, and then the physical displacement time history is converted using the spatial conversion coefficient p.

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