Medium and small span bridge multi-point dynamic displacement monitoring system and data analysis method thereof

Abstract

The invention provides a medium and small span bridge multi-point dynamic displacement monitoring system and a data analysis method thereof. According to the multi-point dynamic displacement monitoring system for the small and medium span bridge, the reflection / transmission window is arranged in the measuring device, the window not only ensures that the laser beam forms a stable laser spot on the target, but also allows the laser beam to reach a subsequent receiver and a laser receiving device through the window, so that the measurement accuracy is improved. And the stability of the system and the realization of the multi-point measurement capability are ensured. The invention further provides a unique monitoring data processing method, the measuring device and the acceleration sensor are arranged in the monitoring system, the advantage of high precision of the measuring device is utilized, the advantage of high-frequency sampling of the acceleration sensor is utilized, and the defect of low sampling frequency is compensated. And high-precision dynamic monitoring of multi-point dynamic displacement of the structure is realized.

Description

Technical Field

[0001] The present invention belongs to the technical fields of structural health monitoring and computer science, and particularly relates to a multi-point dynamic displacement monitoring system for medium and small span bridges and a data analysis method thereof. Background Art

[0002] Bridges play an indispensable role in connecting different regions, promoting logistics transportation, boosting economic growth, and improving the quality of life of residents. However, during the long-term use of bridges, they are affected by various factors such as material aging, fatigue damage, temperature fluctuations, foundation settlement, and heavy vehicle loads, resulting in a weakened bearing capacity. If these problems are not detected in a timely manner, it may lead to huge economic losses. Therefore, establishing an efficient bridge deformation monitoring system to monitor the deformation and overall health status of bridges can detect potential hidden dangers as early as possible and enhance their durability in use.

[0003] In order to accurately measure the deformation / displacement response of bridges, many scholars at home and abroad have carried out numerous studies. The mainstream bridge deformation / displacement monitoring methods mainly include the accelerometer method, the GNSS method, the total station method, and the computer vision method. The accelerometer method obtains the displacement of the structure by integrating the acceleration twice, but during long-term operation, the acceleration integration will produce drift, increasing the monitoring error and making it difficult to obtain the correct structural displacement response. Although the GNSS method is convenient to use, its monitoring accuracy is relatively low, and at the same time, its signal is easily interfered with and it is not easy to deploy in mountainous areas. The total station method has high monitoring accuracy, but it can only monitor one point at a time, and at the same time, the real-time performance of this method is poor, making it difficult to be used for multi-point dynamic displacement measurement of large structures. The computer vision method is a method widely used in recent years. It mainly monitors the displacement of the structure by using the change of pixels, and has the advantages of good real-time performance and multi-point monitoring. However, due to the limitation of the lens resolution, it is difficult to monitor the entire structure globally, and at the same time, due to the influence of external light and exposure time and other limiting conditions, the monitoring accuracy and sampling frequency of this method are restricted.

[0004] Therefore, it is of great practical value to develop a bridge multi-point dynamic displacement monitoring technology that can be efficient and accurate. Summary of the Invention

[0005] The purpose of the present invention is to solve the problems of the existing structure deformation / displacement monitoring technology being complex, costly, and difficult to achieve multi-point dynamic displacement monitoring of medium and small span bridges, etc., and proposes a multi-point dynamic displacement monitoring system for medium and small span bridges and a data analysis method thereof.

[0006] The present invention is realized through the following technical solutions. The present invention provides a multi-point dynamic displacement monitoring system for medium and small-span bridges. The monitoring system includes: a laser transmitter 1 installed on a pier on one side of the structure to be measured, which is internally provided with a laser; a measuring device 2 installed at the position to be measured, a laser receiving device 3 installed on the pier on the other side, and a data processing and synchronization device 4 installed on the structure to be measured; the measuring device 2 and the laser receiving device 3 are both arranged on the optical path of the laser transmitter 1;

[0007] The measuring device 2 includes a measuring device housing 2-1, a first camera 2-2, a first processor 2-3, an acceleration sensor 2-4, a reflection / transmission window 2-5, a transmission window 2-6, and a target 2-7. The transmission window 2-6 is used to receive the laser beam emitted by the laser transmitter 1. When the laser beam passes through the reflection / transmission window 2-5, reflected light and transmitted light will be generated. The transmitted light will continue to pass through the next measurement node, and the reflected light will form a light spot on the target 2-7. The first camera 2-2 is used to photograph the light spot formed by the laser beam on the target 2-7. The acceleration sensor 2-4 is used to obtain the acceleration data at the point to be measured. The first processor 2-3 is used to control the first camera 2-2 to take pictures, extract the displacement of the light spot, obtain the acceleration data, and perform data processing and network transmission;

[0008] The laser receiving device 3 includes a transparent window 3-5, a full diffuse reflection target 3-4, a laser receiver device housing 3-1, a second camera 3-2, and a second processor 3-3. The transparent window 3-5 is used to receive the laser beam emitted by the laser transmitter 1. The full diffuse reflection target 3-4 cooperates with the second camera 3-2 to photograph the laser light spot on the target. The second processor 3-3 is used to control the second camera 3-2 to take pictures, extract the displacement of the light spot, and perform data transmission.

[0009] Furthermore, when the point to be measured undergoes displacement, the light spot in the measuring device 2 will also move. By using the displacement of the light spot in the laser receiving device 3, the true displacement generated at the point to be measured can be corrected, and the accurate dynamic displacement at the point to be measured can be obtained by combining the acceleration data of the acceleration sensor 2-4.

[0010] Furthermore, a plurality of measuring devices 2 are arranged between the laser transmitter 1 and the laser receiving device 3, so that the laser beam emitted by the laser transmitter 1 passes through the plurality of measuring devices 2 to realize multi-point measurement of the structure to be measured.

[0011] Furthermore, the second camera 3-2 and the first camera 2-2 respectively photograph the laser light spot images on the full diffuse reflection target 3-4 and the target 2-7, and then use the method of machine vision to identify the center position of the laser light spot.

[0012] Further, the reflection / transmission window 2-5 of the measuring device 2 needs to have the optical characteristics of both high reflectivity and high transmittance to ensure that a clear spot image can be formed on the target 2-7, while allowing the laser beam to be smoothly transmitted to the subsequent measuring device 2 and laser receiving device 3.

[0013] Further, the first processor 2-3 in the measuring device 2 and the second processor 3-3 in the laser receiving device 3 both have multi-threaded or multi-core processing capabilities, storage capabilities, and network communication capabilities, and can simultaneously complete multiple tasks such as taking pictures and extracting the center of the spot, obtaining acceleration values, and performing numerical calculations. Moreover, the first processor 2-3 can perform stable and fast data and instruction exchanges with the data processing and synchronization device 4 and the second processor 3-3. The storage capability refers to the ability to store corresponding computer programs, acceleration, and spot displacement data.

[0014] Further, the data processing and synchronization device 4 includes a synchronization control module, which can simultaneously control the camera shooting actions of multiple measuring devices 2 and laser receiving devices 3 to ensure that the spot displacement data and acceleration data at each measurement point are collected at the same time point, thereby realizing the dynamic displacement synchronous measurement of multiple points.

[0015] The present invention also proposes a data analysis method for a multi-point dynamic displacement monitoring system of a small and medium-span bridge. The method is implemented according to the multi-point dynamic displacement monitoring system of a small and medium-span bridge described above, and the method includes the following steps:

[0016] Step 1: Establish a three-dimensional coordinate system at the laser transmitter 1, where the X-axis is distributed along the transverse direction of the bridge, the Y-axis is distributed along the vertical direction of the bridge, and the Z-axis is distributed along the longitudinal direction of the bridge and is perpendicular to the laser receiver 3 and the measuring device 2. At the same time, establish a two-dimensional target coordinate system X-O-Y on the reflection / transmission window 2-5 and the full diffuse reflection target 3-4, and this two-dimensional target coordinate system is parallel to the X-O-Y plane of the three-dimensional coordinate system.

[0017] Step 2: Measure the distances L1, L2, L3, and L between the laser transmitter 1 and the points to be measured A, B, C of the structure to be measured and the laser receiving device 3.

[0018] Step 3: Calibrate the first camera 2-2 in each measuring device 2 and the second camera 3-2 in the laser receiving device 3 to obtain the radial distortion coefficient and tangential distortion coefficient of the camera.

[0019] Step 4: Select the displacements of each measuring point at a certain moment as the monitoring reference value, and the structural displacement responses at other moments are expressed as the offsets relative to the reference value. Use Steps 5 and 6 to obtain the monitoring reference values of each measuring point of the structure to be measured.

[0020] Step 5: Use the data processing and synchronization device 4 to control the first cameras 2-2 in each measuring device 2 and the laser receiving device 4 to take pictures simultaneously, so as to obtain the spot pictures formed by the laser on the target 2-7 and the full diffuse reflection target 3-4 at the same moment. Use the distortion coefficients of each camera obtained in Step 3 to orthodontically correct the spot pictures to obtain distortion-free spot pictures;

[0021] Step 6: After obtaining the distortion-free spot images of each measuring point in Step 5, use the method of machine vision to obtain the coordinates A1(x A1 ,y A1 )、B1(x B1 ,y B1 )、C1(x C1 ,y C1 ) and D1(x D1 ,y D1 ) of the spot center in the coordinate systems of each target, and use these coordinates as the monitoring reference values of each measuring point;

[0022] Step 7: After obtaining the monitoring reference values in Step 6, conduct structural displacement monitoring. Control each measuring device 2 and the laser receiving device 4 through the data processing and synchronization device 4 to simultaneously obtain the spot pictures of each measuring point at intervals of time T. At the same time, set the sampling frequency of the acceleration sensor 2-4 in the measuring device 2 and collect the acceleration data a(T) within the time period T;

[0023] Step 8: Use the methods in Step 5 and Step 6 to calculate the coordinates A2(x A2 ,y A2 )、B2(x B2 ,y B2 )、C2(x C2 ,y C2 ) and D2(x D2 ,y D2 ) of the spot center in the spot pictures in Step 7. Combine the reference coordinates A1, B1, C1 and D1 in Step 6 to obtain the displacements Δ A (x A2 -x A1 ,y A2 -y A1 )、Δ B (x B2 -x B1 ,y B2 -y B1 )、Δ C (x C2 -x C1 ,y C2 -y C1 )、Δ D (x D2 -x D1, y D2 -y D1 );

[0024] Step Nine: Since the pier will bend under the load, causing the laser emitter 1 to rotate, the rotation angle α generated by this rotation will have an error effect on the spot displacement of the measuring point. The rotation angle value can be obtained based on the spot displacement in the laser receiving device 4. From Equation (1), the rotation angle value is:

[0025]

[0026] Step Ten: From Equation (1) in Step Nine and the spot displacement values Δ A , Δ B and Δ C in Step Eight, the precise displacement of the measuring point to be measured at time T can be obtained from Equations (2) to (4):

[0027]

[0028] Step Eleven: According to the relevant knowledge of kinematics, the displacement at time T is determined by the initial velocity v0 and the acceleration value from the initial time to time T. The displacement at time T can also be expressed by Equations (5) to (7). The displacement β caused by the acceleration during this time period is expressed by Equations (8) to (10). Therefore, the initial velocities of each measuring point at the initial time can be obtained from Equations (5) to (10) and expressed as Equations (11) to (13):

[0029]

[0030]

[0031] Step Twelve: Based on the initial velocities v0 of each measuring point obtained in Step Eleven, combined with the sampling frequency and acceleration value of the acceleration sensors 2 - 4, using the relevant knowledge of dynamics, the dynamic displacement of the measuring point to be measured at any time h during the time period from the initial time to time T can be obtained as Equations (14) to (16):

[0032]

[0033] Step Thirteen: According to Steps Four to Twelve, the acquisition of the dynamic displacement of the measuring point to be measured within one time period from the initial time to time T can be completed. To acquire the dynamic displacement within the next time period T, the coordinates need to be updated. Update the initial coordinates A1(x A1 , y A1 ), B1(x B1 , y B1 ), C1(x C1 , y C1 ) and D1(x D1 , y D1 ) to A2(xA2 , y A2 ), B2(x B2 , y B2 ), C2(x C2 , y C2 ), and D2(x D2 , y D2 ). Use Step Eight to obtain the spot center coordinates of each measurement point at the end of the second period and update them to A2, B2, C2, and D2. Then repeat Step Eight to Step Twelve to obtain the dynamic displacements of the points to be measured relative to the updated initial coordinates A1, B1, and C1 within this period.

[0034] Step Fourteen: Perform the displacement update operation for the points to be measured. Add the dynamic displacement values of the second monitoring period obtained in Step Thirteen relative to the updated initial coordinates to the displacement values relative to the reference position at the end of the previous monitoring period, i.e., at time T, to obtain the dynamic displacements of each monitoring point relative to the reference position within the second monitoring period.

[0035] Step Fifteen: By repeatedly executing Step Thirteen to Step Fourteen, it is possible to continuously obtain the dynamic displacements of each point to be measured relative to the reference position at any time, realizing continuous monitoring of the dynamic displacements.

[0036] The present invention also proposes an electronic device, including a memory and a processor. The memory stores a computer program, and when the processor executes the computer program, it implements the steps of the data analysis method for a multi-point dynamic displacement monitoring system of a small and medium-span bridge.

[0037] The present invention also proposes a computer-readable storage medium for storing computer instructions. When the computer instructions are executed by a processor, they implement the steps of the data analysis method for a multi-point dynamic displacement monitoring system of a small and medium-span bridge.

[0038] Compared with the prior art, the beneficial effects of the present invention are:

[0039] 1. The present invention proposes a multi-point dynamic displacement monitoring system for small and medium-span bridges. A reflection / transmission window is set in the measuring device. This window not only ensures the formation of a stable laser spot on the target by the laser beam but also allows the laser beam to pass through the window to reach the subsequent receiver and laser receiving device, ensuring the stability of the system and the realization of the multi-point measurement ability.

[0040] 2. The present invention proposes a multi-point dynamic displacement monitoring system for small and medium-span bridges. By setting a laser receiving device on one side pier to calculate the deflection angle of the laser beam caused by the bending of the pier where the laser emitter is located and correct the measurement error of the displacement of the point to be measured caused by the deflection, the measurement accuracy is further ensured.

[0041] 3. The present invention proposes a unique method for processing monitoring data. By setting up a measuring device and an acceleration sensor in the monitoring system, it not only takes advantage of the high-precision of the measuring device, but also compensates for the deficiency of its low sampling frequency through the advantage of high-frequency sampling of the acceleration sensor, realizing high-precision dynamic monitoring of the multi-point dynamic displacement of the structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only the embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on the provided drawings.

[0043] Figure 1 It is a schematic diagram of a multi-point dynamic displacement monitoring system for medium and small span bridges of the present invention;

[0044] Figure 2 It is a sectional view of the internal structure of the measuring device of the present invention;

[0045] Figure 3 It is an optical path diagram of the measuring device of the present invention;

[0046] Figure 4 It is a sectional view of the internal structure of the laser receiving device of the present invention;

[0047] Figure 5 It is a schematic diagram based on the measurement principle of a multi-point dynamic displacement monitoring system for medium and small span bridges of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0048] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0049] Combined with Figures 1-5 , the present invention proposes a multi-point dynamic displacement monitoring system for medium and small span bridges. The monitoring system includes: a laser transmitter 1 installed on one side pier of the structure to be measured, which is internally provided with a laser; a measuring device 2 installed at the position to be measured, a laser receiving device 3 installed on the other side pier, and a data processing and synchronization device 4 installed on the structure to be measured; both the measuring device 2 and the laser receiving device 3 are arranged on the optical path of the laser transmitter 1;

[0050] The laser emitter 1 and the laser receiving device 3 are installed on the piers on both sides of the structure to be measured. The laser beam emitted by the laser emitter 1 points to the laser receiving device 3. The laser emitter housing and the laser receiving device housing are tightly connected to the piers of the structure to be measured through connectors provided on the housings.

[0051] The measuring device 2 is installed at the measurement point between the laser emitter 1 and the laser receiving device 3. The measuring device housing is tightly connected to the structure to be measured through connectors provided on the measuring device 2 to ensure that the displacement response of the measuring device 2 is the same as that of the measurement point. The measuring device 2 includes a measuring device housing 2-1, a first camera 2-2, a first processor 2-3, an acceleration sensor 2-4, a reflection / transmission window 2-5, a transmission window 2-6, and a target 2-7. The transmission window 2-6 is used to receive the laser beam emitted by the laser emitter 1. When the laser beam passes through the reflection / transmission window 2-5, reflected light and transmitted light will be generated. The transmitted light will continue to pass through the next measurement node, and the reflected light will form a light spot on the target 2-7. The first camera 2-2 is used to capture the light spot formed by the laser beam on the target 2-7. The acceleration sensor 2-4 is used to obtain the acceleration data at the measurement point. The first processor 2-3 is used to control the first camera 2-2 to take pictures, extract the displacement of the light spot, obtain the acceleration data, and perform data processing and network transmission;

[0052] The laser receiving device 3 includes a transparent window 3-5, a full diffuse reflection target 3-4, a laser receiver device housing 3-1, a second camera 3-2, and a second processor 3-3. The transparent window 3-5 is used to receive the laser beam emitted by the laser emitter 1. The full diffuse reflection target 3-4 cooperates with the second camera 3-2 to capture the laser light spot on the target. The second processor 3-3 is used to control the second camera 3-2 to take pictures, extract the displacement of the light spot, and perform data transmission.

[0053] When the measurement point is displaced, the light spot in the measuring device 2 will be displaced. By using the displacement of the light spot in the laser receiving device 3, the true displacement generated at the measurement point can be corrected, and the accurate dynamic displacement at the measurement point can be obtained by combining the acceleration data of the acceleration sensor 2-4.

[0054] Multiple measurement points can be selected on the optical path of the laser emitter 1, and then the measuring device 2 is installed at each measurement point to realize multi-point measurement of the structure to be measured. That is, multiple measuring devices 2 are arranged between the laser emitter 1 and the laser receiving device 3, and the laser beam emitted by the laser emitter 1 passes through multiple measuring devices 2 to realize multi-point measurement of the structure to be measured.

[0055] The second camera 3-2 and the first camera 2-2 respectively capture the laser spot images on the full diffuse reflection target 3-4 and the target 2-7, and then use machine vision methods to identify the center positions of the laser spots. Methods such as the centroid method, the shape centroid method, and the ellipse fitting method can be used to identify the center of the spot.

[0056] The reflection / transmission window 2-5 of the measuring device 2 needs to have the optical properties of both high reflectivity and high transmittance to ensure that a clear spot image can be formed on the target 2-7, and at the same time allow the laser beam to be transmitted smoothly to the subsequent measuring device 2 and the laser receiving device 3. Materials with the optical properties of high reflectivity and high transmittance can use smooth quartz glass or other materials processed by other processes. That is to say, the reflection / transmission window 2-5 uses smooth quartz glass or other materials to cause the laser beam irradiated on its surface to be reflected to form a stable spot on the target, and at the same time continue to propagate forward through the transmission window.

[0057] The first processor 2-3 in the measuring device 2 and the second processor 3-3 in the laser receiving device 3 both have multi-threaded or multi-core processing capabilities, storage capabilities, and network communication capabilities, and can simultaneously complete multiple tasks such as taking pictures and extracting the center of the spot, obtaining acceleration values, and numerical calculations. And the first processor 2-3 can perform stable and fast data and instruction exchanges with the data processing and synchronization device 4 and the second processor 3-3. The storage capability refers to the ability to store corresponding computer programs, accelerations, and spot displacement data.

[0058] The data processing and synchronization device 4 includes a synchronization control module, which can simultaneously control the camera shooting actions of multiple measuring devices 2 and laser receiving devices 3 to ensure that the spot displacement data and acceleration data at each measurement point are collected at the same time point, so as to realize the dynamic displacement synchronous measurement of multiple points and improve the overall accuracy and reliability of the monitoring system.

[0059] Adjust the direction of the laser in the laser emitter 1 so that the laser emitted by the laser can form a clear laser spot image in the target 2-7 and the full diffuse reflection target 3-4 inside the measuring device 2 installed at the point to be measured before performing the multi-point dynamic displacement measurement of the structure.

[0060] The present invention also proposes a data analysis method for a multi-point dynamic displacement monitoring system of a small and medium-span bridge. The method is realized according to the multi-point dynamic displacement monitoring system of a small and medium-span bridge, and the method includes the following steps:

[0061] Step 1: Establish a three-dimensional coordinate system at the laser emitter 1, where the X-axis is distributed along the transverse direction of the bridge, the Y-axis is distributed along the vertical direction of the bridge, and the Z-axis is distributed along the longitudinal direction of the bridge and is perpendicular to the laser receiver 3 and the measuring device 2. At the same time, establish a two-dimensional target coordinate system X-O-Y on the reflection / transmission window 2-5 and the full diffuse reflection target 3-4, and this two-dimensional target coordinate system is parallel to the X-O-Y plane of the three-dimensional coordinate system;

[0062] Step 2: Measure the distances L1, L2, L3, and L between the points to be measured A, B, C of the structure to be measured and the laser receiving device 3 and the laser emitter 1;

[0063] Step 3: Calibrate the first camera 2-2 in each measuring device 2 and the second camera 3-2 in the laser receiving device 3 to obtain internal parameters such as the radial distortion coefficient and tangential distortion coefficient of the camera;

[0064] Step 4: Select the displacements of each measuring point at a certain moment as the monitoring reference value, and the structural displacement responses at other moments are expressed as offsets relative to the reference value. Use Step 5 and Step 6 to obtain the monitoring reference values of each measuring point of the structure to be measured;

[0065] Step 5: Use the data processing and synchronization device 4 to control the first camera 2-2 in each measuring device 2 and the second camera 3-2 in the laser receiving device 4 to take pictures simultaneously to obtain the spot pictures formed by the laser on the target 2-7 and the full diffuse reflection target 3-4 at the same moment. Use the distortion coefficients of each camera obtained in Step 3 to orthodontically correct the spot pictures to obtain undistorted spot pictures;

[0066] Step 6: After obtaining the undistorted spot images of each measuring point in Step 5, use the method of machine vision to obtain the coordinates A1(x A1 ,y A1 )、B1(x B1 ,y B1 )、C1(x C1 ,y C1 ) and D1(x D1 ,y D1 ) of the spot center in each target coordinate system, and use these coordinates as the monitoring reference values of each measuring point;

[0067] Step 7: After obtaining the monitoring reference values in Step 6, conduct structural displacement monitoring. Use the data processing and synchronization device 4 to control each measuring device 2 and the laser receiving device 4. At intervals of time T, simultaneously obtain the spot pictures of each measuring point, and at the same time set the sampling frequency of the acceleration sensor 2-4 in the measuring device 2, and collect the acceleration data a(T) within the T time period;

[0068] Step 8: Use the methods in Step 5 and Step 6 to find the coordinates A2(x A2, y A2 ), B2(x B2 , y B2 ), C2(x C2 , y C2 ), and D2(x D2 , y D2 ), combined with the reference coordinates A1, B1, C1, and D1 in Step Six, the displacement Δ A (x A2 - x A1 , y A2 - y A1 ), Δ B (x B2 - x B1 , y B2 - y B1 ), Δ C (x C2 - x C1 , y C2 - y C1 ), Δ D (x D2 - x D1 , y D2 - y D1 ) can be obtained;

[0069] Step Nine: Since the bridge pier will bend under the action of the load, causing the laser transmitter 1 to rotate, the rotation angle α generated by this rotation will have an error effect on the spot displacement of the measuring point. According to the spot displacement in the laser receiving device 4, this rotation angle value can be obtained. From Equation (1), the rotation angle value is:

[0070]

[0071] Step Ten: From Equation (1) in Step Nine and the spot displacement values Δ A , Δ B , and Δ C in Step Eight, the accurate displacement of the measuring point at time T can be obtained from Equations (2) to (4):

[0072]

[0073] Step Eleven: According to the relevant knowledge of kinematics, the displacement at time T is determined by the initial velocity v0 and the acceleration value from the initial moment to time T. The displacement at time T can also be expressed by Equations (5) to (7). The displacement β caused by the acceleration during this time period is expressed by Equations (8) to (10). Therefore, from Equations (5) to (10), the initial velocities of each measuring point at the initial moment can be obtained and expressed as Equations (11) to (13):

[0074]

[0075]

[0076] Step Twelve: According to the initial velocity v0 of each measurement point obtained in Step Eleven, combined with the sampling frequency and acceleration value of the acceleration sensor 2-4, using the relevant knowledge of dynamics, it can be obtained that within the time period from the initial moment to the T moment, the dynamic displacement of any measurement point h at any moment is expressed by Equations (14) to (16):

[0077]

[0078] Step Thirteen: According to Steps Four to Twelve, the acquisition of the dynamic displacement of the measurement points within one time period from the initial moment to the T moment can be completed. To obtain the dynamic displacement within the next time period T, the coordinates need to be updated. The initial coordinates A1(x A1 , y A1 ), B1(x B1 , y B1 ), C1(x C1 , y C1 ) and D1(x D1 , y D1 ) are updated to A2(x A2 , y A2 ), B2(x B2 , y B2 ), C2(x C2 , y C2 ) and D2(x D2 , y D2 ). The light spot center coordinates of each measurement point at the end of the second period are obtained using Step Eight and updated to A2, B2, C2, and D2. Then, Steps Eight to Twelve are repeated to obtain the dynamic displacement of the measurement points within this period relative to the updated initial coordinates A1, B1, C1;

[0079] Step Fourteen: Perform the displacement update operation for the measurement points. Add the dynamic displacement value within the second monitoring period relative to the updated initial coordinates obtained in Step Thirteen to the displacement value relative to the reference position at the end of the previous monitoring period, i.e., at the T moment, to obtain the dynamic displacement of each monitoring point relative to the reference position within the second monitoring period;

[0080] Step Fifteen: By repeatedly executing Steps Thirteen to Fourteen, it is possible to continuously obtain the dynamic displacement of each measurement point relative to the reference position at any moment, realizing continuous monitoring of the dynamic displacement.

[0081] The present invention provides a multi-point dynamic displacement monitoring system for medium and small-span bridges considering the sway of bearings and a data analysis and processing method thereof, belonging to the field of structural health monitoring. The monitoring system mainly consists of a laser transmitter, a laser receiving device, a data processing and synchronization device, and a measuring device installed at the points to be measured. Among them, the laser transmitter is installed at the bridge pier and emits laser to the measuring device at the point to be measured and the laser receiving device at the other pier; the measuring device includes components such as a through window, a reflection / through window, a processor, an acceleration sensor, a target, and a camera, and is used to measure the displacement of the point to be measured; the laser receiving device is composed of a full diffuse reflection target, a camera, and a processor, etc. When the point to be measured undergoes displacement, when the laser passes through the reflection / through window, it will cause the light spot on the target to move. The displacement of the light spot is obtained through the camera and the processor, and the displacement of the light spot of the measuring device is corrected by combining the displacement of the light spot of the laser receiving device, so as to obtain the accurate displacement of the point to be measured. At the same time, using the acceleration sensor data in the measuring device and the data processing method proposed by the present invention, the accurate dynamic displacement of the point to be measured can be further obtained. In addition, with the help of the data processing and synchronization device in the monitoring system, the dynamic displacements of multiple points to be measured can be synchronously acquired and processed, and then the multi-point dynamic displacement measurement of the structure to be measured can be realized.

[0082] The present invention also provides an electronic device, including a memory and a processor, where the memory stores a computer program, and when the processor executes the computer program, the steps of the data analysis method of the multi-point dynamic displacement monitoring system for medium and small-span bridges are realized.

[0083] The present invention also provides a computer-readable storage medium for storing computer instructions, and when the computer instructions are executed by a processor, the steps of the data analysis method of the multi-point dynamic displacement monitoring system for medium and small-span bridges are realized.

[0084] The memory in the embodiments of the present application may be a volatile memory or a non-volatile memory, or may include both volatile and non-volatile memories. Among them, the non-volatile memory may be a read only memory (ROM), a programmable ROM (PROM), an erasable PROM (EPROM), an electrically erasable PROM (EEPROM), or a flash memory. The volatile memory may be a random access memory (RAM), which is used as an external cache. By way of example but not limitation, many forms of RAM are available, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDR SDRAM), enhanced SDRAM (ESDRAM), synchlink DRAM (SLDRAM), and direct rambus RAM (DRRAM). It should be noted that the memory of the method described in the present invention is intended to include but not limited to these and any other suitable types of memories.

[0085] In the above embodiments, it can be implemented in whole or in part by software, hardware, firmware, or any combination thereof. When implemented using software, it can be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer instructions are loaded and executed on a computer, the processes or functions described in the embodiments of the present application are generated in whole or in part. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable devices. 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 (such as coaxial cable, fiber optic, digital subscriber line (DSL)) or wireless (such as infrared, wireless, microwave, etc.) means. The computer-readable storage medium can be any available medium that can be accessed by a computer or a data storage device such as a server, data center, etc. that includes one or more integrated available media. The available media can be magnetic media (such as floppy disks, hard disks, magnetic tapes), optical media (such as high-density digital video discs (DVDs)), or semiconductor media (such as solid state discs (SSDs)), etc.

[0086] In the implementation process, each step of the above method can be completed by the integrated logic circuit of the hardware in the processor or the instructions in the form of software. The steps of the method disclosed in combination with the embodiments of the present application can be directly embodied as being executed and completed by the hardware processor, or executed and completed by a combination of the hardware and software modules in the processor. The software module can be located in a mature storage medium in the art such as random access memory, flash memory, read-only memory, programmable read-only memory, or electrically erasable programmable memory, registers, etc. This storage medium is located in the memory, and the processor reads the information in the memory and combines its hardware to complete the steps of the above method. To avoid repetition, it will not be described in detail here.

[0087] It should be noted that the processor in the embodiments of the present application can be an integrated circuit chip with signal processing capabilities. In the implementation process, the steps of the above method embodiments can be completed by the integrated logic circuit in the hardware of the processor or instructions in the form of software. The above-mentioned processor can be a general-purpose processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components. It can implement or execute the various methods, steps, and logic block diagrams disclosed in the embodiments of the present application. The general-purpose processor can be a microprocessor or the processor can also be any conventional processor, etc. The steps of the method disclosed in combination with the embodiments of the present application can be directly embodied as being executed and completed by the hardware decoding processor, or executed and completed by a combination of the hardware and software modules in the decoding processor. The software module can be located in a mature storage medium in the art such as random access memory, flash memory, read-only memory, programmable read-only memory, or electrically erasable programmable memory, registers, etc. This storage medium is located in the memory, and the processor reads the information in the memory and combines its hardware to complete the steps of the above method.

[0088] The above has introduced in detail a multi-point dynamic displacement monitoring system for medium and small span bridges and its data analysis method proposed by the present invention. Specific examples are used in this article to elaborate on the principle and implementation manner of the present invention. The description of the above embodiments is only used to help understand the method and its core idea of the present invention; at the same time, for those of ordinary skill in the art, according to the idea of the present invention, there will be changes in the specific implementation manner and application scope. In summary, the content of this specification should not be construed as a limitation to the present invention.

Claims

1. A multi-point dynamic displacement monitoring system for medium and small span bridges, characterized in that, The monitoring system includes: a laser emitter (1) installed on a pier on one side of the structure to be measured, which is built-in with a laser; a measuring device (2) installed at the position to be measured, a laser receiving device (3) installed on the pier on the other side, and a data processing and synchronization device (4) installed on the structure to be measured; both the measuring device (2) and the laser receiving device (3) are arranged on the optical path of the laser emitter (1); The measuring device (2) includes a measuring device housing (2-1), a first camera (2-2), a first processor (2-3), an acceleration sensor (2-4), a reflection / transmission window (2-5), a transmission window (2-6), and a target (2-7). The transmission window (2-6) is used to receive the laser beam emitted by the laser emitter (1). When the laser beam passes through the reflection / transmission window (2-5), reflected light and transmitted light will be generated. The transmitted light will continue to pass through the next measurement node, and the reflected light will form a light spot on the target (2-7). The first camera (2-2) is used to capture the light spot formed by the laser beam on the target (2-7). The acceleration sensor (2-4) is used to obtain the acceleration data at the point to be measured. The first processor (2-3) is used to control the first camera (2-2) to take pictures, extract the displacement of the light spot, obtain the acceleration data, and perform data processing and network transmission; The laser receiving device (3) includes a transparent window (3-5), a full diffuse reflection target (3-4), a laser receiver device housing (3-1), a second camera (3-2), and a second processor (3-3). The transparent window (3-5) is used to receive the laser beam emitted by the laser emitter (1). The full diffuse reflection target (3-4) cooperates with the second camera (3-2) to capture the laser light spot on the target. The second processor (3-3) is used to control the second camera (3-2) to take pictures, extract the displacement of the light spot, and perform data transmission.

2. The monitoring system according to claim 1, characterized in that, When the point to be measured is displaced, the light spot in the measuring device (2) will be displaced. By using the displacement of the light spot in the laser receiving device (3), the true displacement generated at the point to be measured can be corrected, and the accurate dynamic displacement at the point to be measured can be obtained by combining the acceleration data of the acceleration sensor (2-4).

3. The monitoring system according to claim 1, characterized in that A plurality of measuring devices (2) are arranged between the laser emitter (1) and the laser receiving device (3), so that the laser beam emitted by the laser emitter (1) passes through the plurality of measuring devices (2) to realize multi-point measurement of the structure to be measured.

4. The monitoring system according to claim 1, characterized in that, The second camera (3-2) and the first camera (2-2) respectively capture the laser light spot images on the full diffuse reflection target (3-4) and the target (2-7), and then use the method of machine vision to identify the central position of the laser light spot.

5. The monitoring system according to claim 1, characterized in that, The reflection / transmission window (2-5) of the measuring device (2) needs to have the optical characteristics of both high reflectivity and high transmittance to ensure that a clear light spot image can be formed on the target (2-7), and at the same time allow the laser beam to be transmitted smoothly to the subsequent measuring device (2) and laser receiving device (3).

6. The monitoring system according to claim 1, characterized in that, Both the first processor (2-3) in the measurement device (2) and the second processor (3-3) in the laser receiving device (3) have multi-threaded or multi-core processing capabilities, storage capabilities, and network communication capabilities. They can simultaneously complete tasks such as taking pictures, extracting the center of the light spot, obtaining acceleration values, and performing numerical calculations. Moreover, the first processor (2-3) can stably and quickly exchange data and instructions with the data processing and synchronization device (4) and the second processor (3-3). The storage capability refers to the ability to store corresponding computer programs, acceleration, and light spot displacement data.

7. The monitoring system according to claim 3, characterized in that, The data processing and synchronization device (4) includes a synchronization control module. This synchronization control module can simultaneously control the camera shooting actions of multiple measurement devices (2) and laser receiving devices (3), ensuring that the light spot displacement data and acceleration data of each measurement point are collected at the same time point, thereby realizing the synchronous measurement of multi-point dynamic displacements.

8. A data analysis method for a multi-point dynamic displacement monitoring system of medium and small span bridges, characterized in that, The method is implemented according to a multi-point dynamic displacement monitoring system for small and medium-span bridges described in any one of claims 1-7. The method includes the following steps: Step 1: Establish a three-dimensional coordinate system at the laser emitter (1), where the X-axis is distributed along the transverse direction of the bridge, the Y-axis is distributed along the vertical direction of the bridge, and the Z-axis is distributed along the longitudinal direction of the bridge and is perpendicular to the laser receiver (3) and the measurement device (2). At the same time, establish a two-dimensional target coordinate system X-O-Y on the reflection / transmission window (2-5) and the full diffuse reflection target (3-4). This two-dimensional target coordinate system is parallel to the X-O-Y plane of the three-dimensional coordinate system. Step 2: Measure the distances L1, L2, L3, and L between the laser emitter (1) and the measurement points A, B, C of the structure to be measured and the laser receiving device (3). Step 3: Calibrate the first camera (2-2) in each measurement device (2) and the second camera (3-2) in the laser receiving device (3) to obtain the radial distortion coefficient and tangential distortion coefficient of the camera. Step 4: Select the displacements of each measurement point at a certain moment as the monitoring reference value. The structural displacement responses at other moments are expressed as offsets relative to the reference value. Use steps 5 and 6 to obtain the monitoring reference values of each measurement point of the structure to be measured. Step 5: Use the data processing and synchronization device (4) to control the first camera (2-2) and the second camera (3-2) in each measurement device (2) and the laser receiving device (4) to take pictures simultaneously to obtain the light spot pictures formed by the laser on the target (2-7) and the full diffuse reflection target (3-4) at the same moment. Use the distortion coefficients of each camera obtained in step 3 to orthodontically correct the light spot pictures to obtain undistorted light spot pictures. Step 6. After obtaining the undistorted spot images of each measuring point in Step 5, use the machine vision method to obtain the coordinates A1(x A1 , y A1 ), B1(x B1 , y B1 ), C1(x C1 , y C1 ) and D1(x D1 , y D1 ) of the spot center in each target coordinate system, and use these coordinates as the monitoring reference values of each measuring point; Step 7: After obtaining the monitoring reference value in step 6, conduct structural displacement monitoring. Through the data processing and synchronization device (4), control each measurement device (2) and the laser receiving device (4) to simultaneously obtain the light spot pictures of each measurement point every time interval T. At the same time, set the sampling frequency of the acceleration sensor (2-4) in the measurement device (2) and collect the acceleration data a(T) within the T time period. Step 8: Use the methods in Steps 5 and 6 to find the center coordinates A2(x A2 ,y A2 )、B2(x B2 ,x B2 )、C2(x C2 ,y C2 ) and D2(x D2 ,y D2 ) of the light spot in the light spot image in Step 7. Combining with the reference coordinates A1, B1, C1, and D1 in Step 6, the displacements Δ A (x A2 -x A1 ,y A2 -y A1 ), Δ B (x B2 -x B1 ,y B2 -y B1 ), Δ C (x C2 -x C1 ,y C2 -y C1 ), and Δ D (x D2 -x D1 ,y D2 -y D1 ) of the light spot center in the target coordinates can be obtained; Step 9: Since the pier will bend under the action of the load, causing the laser emitter (1) to rotate, the rotation angle α generated by this rotation will have an error effect on the spot displacement of the measurement point. The rotation angle value can be obtained based on the spot displacement in the laser receiving device (4). According to Equation (1), the rotation angle value is: Step Ten: From the spot displacement values Δ A and Δ B in (1) of Step Nine and the spot displacement value Δ C in Step Eight, the precise displacement of the point to be measured at time T can be obtained from Equations (2) to (4): Step 11: According to the relevant knowledge of kinematics, the displacement at time T is determined by the initial velocity v0 and the acceleration value from the initial moment to time T. The displacement at time T can also be expressed by Equations (5) to (7). The displacement β caused by the acceleration during this time period is expressed by Equations (8) to (10). Therefore, the initial velocities of each measurement point at the initial moment can be obtained from Equations (5) to (10) and expressed as Equations (11) to (13): Step 12: Based on the initial velocities v0 of each measurement point obtained in Step 11, combined with the sampling frequency and acceleration value of the acceleration sensor (2-4), using the relevant knowledge of dynamics, the dynamic displacement of any measurement point h at any time during the time period from the initial moment to time T can be obtained as Equations (14) to (16): Step Thirteen: According to Steps Four to Twelve, the dynamic displacement of the point to be measured within a time period from the initial moment to moment T can be obtained. To obtain the dynamic displacement within the next time period T, the coordinates need to be updated. The initial coordinates A1(x A1 ,y A1 ), B1(x B1 ,y B1 ), C1(x C1 ,y C1 ) and D1(x D1 ,y D1 ) are updated to A2(x A2 ,y A2 ), B2(x B2 ,y B2 ), C2(x C2 ,y C2 ) and D2(x D2 ,y D2 ). The spot center coordinates of each measurement point at the end of the second period are obtained using Step Eight and updated to A2, B2, C2, and D2. Then, Steps Eight to Twelve are repeated to obtain the dynamic displacement of the point to be measured relative to the updated initial coordinates A1, B1, and C1 within this period; Step 14: Perform the displacement update operation for the measurement points to be measured. Add the dynamic displacement value of the second monitoring period relative to the updated initial coordinates obtained in Step 13 to the displacement value of the previous monitoring period end, i.e., at time T, relative to the reference position, to obtain the dynamic displacement of each monitoring point relative to the reference position in the second monitoring period; Step 15: By repeatedly executing Steps 13 to 14, the dynamic displacement of each measurement point to be measured relative to the reference position at any time can be continuously obtained, realizing the continuous monitoring of the dynamic displacement.

9. An electronic device, comprising a memory and a processor, the memory storing a computer program, characterized in that, When the processor executes the computer program, it implements the steps of the method described in Claim 8.

10. A computer-readable storage medium for storing computer instructions, characterized in that, When the computer instructions are executed by the processor, it implements the steps of the method described in Claim 8.

Images