Full-life-cycle camera shooting monitoring method and system based on large-span arch bridge

Abstract

The invention relates to the technical field of large-span arch bridge engineering camera measurement, in particular to a full-life-cycle camera monitoring method and system based on a large-span arch bridge, and the system comprises a measurement module, a software processing module and a visual management module. The measurement module acquires an image of a measurement target spot; the software processing module generates a real-time change curve and generates the variable quantity of an arch axis according to the real-time change curve; and the visual management module monitors the large-span arch bridge according to the variable quantity of the arch axis and the space coordinate of the measured point. According to the invention, the construction of the camera measurement system for key working conditions such as turning over of arch rib sections, closure of main arch rings, pouring of concrete in the pipe and construction and operation of the large-span arch bridge is elaborated through related cases, and the whole life cycle monitoring from the whole construction process to the operation of the large-span arch bridge can be completed; the method has the advantages of real-time synchronization, high robustness, convenience in replacement, high durability and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of bridge monitoring by camera measurement, and particularly relates to a full-life-cycle camera monitoring method and system for long-span arch bridges. Background Art

[0002] With the rapid development of China's traffic engineering construction, the span of bridges is continuously increasing, and long-span arch bridges are increasingly widely used in expressways, railways, etc. With the increasing traffic volume in developed areas, the frequency of dynamic loads borne by bridges far exceeds the design value. At the same time, China's transportation infrastructure strategy is being implemented in the western regions with "large height differences, many geological disasters, and frequent extreme climates". The long-term dynamic real-time monitoring and service performance evaluation of the full life cycle of long-span arch bridges have become particularly important.

[0003] There are the following technical difficulties in the long-term monitoring means of long-span bridges. The contact-type long-term bridge monitoring method based on strain gauges, displacement sensors, etc. can only measure and obtain values at the measuring points where the test elements are pasted. To accurately monitor the influence of the changing load distribution on the overall structure of the bridge, a large number of sensors need to be installed at key positions of the bridge, which is greatly restricted by environmental and working condition conditions, and may also affect the beauty and function of the bridge. Among non-contact monitoring, technologies such as laser, radar, acoustic emission, and camera measurement have become hotspots in long-span bridge monitoring. Among them, camera measurement technology has developed rapidly and been applied in practice in recent years.

[0004] With the development of digital image processing, laser technology, and computer vision, camera measurement has become an efficient and accurate deformation monitoring method. This technology can be well applied to the bridge monitoring process. Moreover, camera measurement can simultaneously obtain information on the entire surface of the structure, rather than just the deformation data of local points, so as to more comprehensively understand the deformation of the structure; it can automatically collect data and can monitor the deformation of the structure in real time, which helps to detect abnormal situations in a timely manner.

[0005] During the operation period of bridges, long-span arch bridge projects often use bridge health monitoring systems to monitor and evaluate the service conditions of long-span arch bridges. However, the number of sensors used in the system is large, and the service life generally does not exceed 15 years, and they need to be replaced regularly. The construction of a set of mature systems requires huge funds, the system maintenance cost is high, and it cannot be widely popularized. On the other hand, traditional contact-type measurement methods will interfere with the measurement object itself, and the measurement system layout is cumbersome and the number of measurement points is limited, which cannot meet the requirements of full-field, high-precision measurement and dynamic real-time monitoring of long-span arch bridges. Summary of the Invention

[0006] The purpose of the present invention is to overcome the problems of usage limitations and high maintenance costs existing in the prior art.

[0007] To achieve the above object, the following technical solutions are proposed:

[0008] A full-life-cycle camera monitoring system based on a long-span arch bridge, comprising a measurement module, a software processing module, and a visualization management module;

[0009] The measurement module acquires images of measurement target points, and the measurement target points are set at measured points;

[0010] The software processing module extracts image features in the images of the measurement target points, calculates the spatial coordinates of the measured points according to the image features, generates a real-time change curve based on the spatial coordinates of the measured points, and generates a change amount of the arch axis according to the real-time change curve;

[0011] The visualization management module monitors the long-span arch bridge according to the change amount of the arch axis and the spatial coordinates of the measured points.

[0012] Preferably, the measurement module includes measurement target points and industrial cameras;

[0013] The industrial cameras are used to photograph the measurement target points and acquire image data of the measured points;

[0014] The measurement target points include light-emitting marks, reflective marks, or natural structural features on the long-span arch bridge, and the measurement target points are fixed on the structural surface of the long-span arch bridge through a bottom plate.

[0015] Preferably, the industrial cameras are fixed at monitoring points through a base, and are fixed at the monitoring points in a sleeved, hinged, or snap-locked manner with the base.

[0016] Preferably, the spacing between the measurement target points is determined according to the arch axis equation, and the arch axis equation is calculated according to the arch axis coefficient.

[0017] Preferably, the installation positions of the measurement target points include the crown of the arch, the arch feet, 1 / 6L, 1 / 4L, the position with the maximum bending moment, the position with the maximum internal force, and the position with the most sensitive change, where L is the full-span length of the arch bridge.

[0018] Preferably, the software processing module includes an image feature extraction solver and a data processor. The image feature extraction solver converts image feature points into spatial feature points to obtain the time-history coordinates of the measured points, and the data processor calculates the change amount of the time-history coordinates of the measured points and generates a real-time change curve of the displacement of the measured points according to the change amount of the time-history coordinates.

[0019] Preferably, the visualization management module includes a three-dimensional visualization module, a big data storage module, a data prediction and analysis module, an environmental data monitoring module, and an abnormal data warning module;

[0020] The three-dimensional visualization module is used to generate the 3D model diagram of the long-span arch bridge, and is used to display the change amount of the spatial coordinates or time-history coordinates of the measured points;

[0021] The big data storage module stores the historical data of the images of the measurement target points and the images of the measurement target points obtained in real time;

[0022] The data prediction and analysis module analyzes the historical data of the images of the measurement target points, predicts the change of the arch axis by using the historical data, and displays the real-time change curve and the change amount of the arch axis; the environmental data monitoring module displays the environmental data;

[0023] The abnormal data warning module is also used to compare the displacement change amount of the real-time visualization model with a preset threshold value, and issue a warning when the preset threshold value is exceeded.

[0024] In a second aspect, the present invention provides a camera measurement monitoring method based on the whole life cycle of the construction to operation of a long-span arch bridge, including the following steps:

[0025] S1: Set measurement target points on the long-span arch bridge, and obtain the images of the measurement target points, and the measurement target points are set at the measured points;

[0026] S2: The measurement module sends the obtained image data of the measured points to the software processing module. The software processing module extracts the image features in the images of the measurement target points, calculates the spatial coordinates of the measured points according to the image features, generates a real-time change curve according to the spatial coordinates of the measured points, and generates the change amount of the arch axis according to the real-time change curve; the visualization management module monitors the long-span arch bridge according to the spatial coordinates of the measured points and the change amount of the arch axis.

[0027] In particular, the spacing between the measurement target points is determined by the arch axis equation of the arch bridge, and the calculation formula of the arch axis equation is:

[0028]

[0029] where m is the arch axis coefficient, f is the height of the arch axis, y is the height of the arch in the vertical direction, that is, the distance from the reference line to any point on the arch, x is the position of the arch in the horizontal direction, that is, the horizontal distance from one end of the arch to any point on the arch, l is the horizontal distance from the crown to the springing point of the arch, H g is the horizontal thrust of the self-weight of the arch structure, g d is the intensity of the load distribution at the crown of the arch.

[0030] Preferably, the step of generating the change amount of the arch axis from the real-time change curve includes:

[0031] S101: Obtain an image of the measurement target; extract the feature points of the measurement target from the image of the measurement target, convert the coordinates of the feature points from the image pixel coordinate system to the world coordinate system to obtain the three-dimensional coordinates of the feature points, and obtain the position information of the measurement target according to the three-dimensional coordinates of the feature points;

[0032] S102: By comparing the position information of the measurement target at different times, calculate the displacement and inclination change of the measurement target, and draw a displacement change diagram of the measurement target in the X direction and the Y direction according to the change amount, so as to obtain the real-time change curve of the measurement target;

[0033] S103: Generate a change curve of the arch axis according to the real-time change curve of the measurement target to obtain the change amount of the arch axis.

[0034] Compared with the prior art, the beneficial effects of the present invention are:

[0035] The present invention provides a full-life cycle camera monitoring method and system for long-span arch bridges. By building a camera measurement system for key working conditions such as the turning over of arch rib segments, segment hoisting, closure of the main arch ring, pouring of concrete in the pipe, casting of outer concrete, and operation after completion of long-span arch bridges, the monitoring of the entire construction process to the entire life cycle of operation of long-span arch bridges can be completed, and it has the advantages of real-time synchronization, strong robustness, convenient replacement, and high durability. Description of the Drawings

[0036] Figure 1 It is a system module diagram of Embodiment 1 of the present invention;

[0037] Figure 2 It is a flowchart of Embodiment 2 of the present invention;

[0038] Figure 3 It is a schematic diagram of a monocular camera and a measurement target of the camera measurement system for long-span arch bridges in Embodiment 2 of the present invention;

[0039] Figure 4 It is a schematic diagram of a multi-camera platform of the camera measurement system for long-span arch bridges in Embodiment 2 of the present invention;

[0040] Figure 5 It is a schematic diagram of camera measurement during the turning over of arch rib segments of long-span arch bridges in Embodiment 2 of the present invention;

[0041] Figure 6 It is a schematic diagram of camera measurement and monitoring of arch axis deformation during the operation period of long-span arch bridges in Embodiment 2 of the present invention;

[0042] Figure 7 It is a schematic diagram of the visualization management system for long-span arch bridges in Embodiment 2 of the present invention. Detailed Embodiment

[0043] The present invention will be further described in detail below in conjunction with test examples and specific embodiments. However, it should not be understood that the scope of the above-mentioned subject matter of the present invention is limited to the following embodiments. All technologies implemented based on the content of the present invention belong to the scope of the present invention.

[0044] In the description of the specific embodiments of the present invention, without special instructions, the expression terms indicating the orientation or positional relationship such as "upper", "lower", "left", "right", "center", "inner", "outer", etc. are all based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship when the invention product / device / equipment is usually used and placed. These terms of orientation or positional relationship are only for the convenience of describing the solution of the present invention or simplifying the description in the specific embodiments, so as to facilitate technicians to quickly understand the solution, rather than indicating or implying that a specific device / component / element must have a specific orientation or be constructed and operated in a specific positional relationship. Therefore, it should not be construed as a limitation to the present invention.

[0045] In addition, in the description of the embodiments of the present invention, "several", "multiple", and "a number of" represent at least two. It can be any situation such as 2, 3, 4, 5, 6, 7, 8, 9, etc., or even more than 9.

[0046] In addition, in the description of the technical solution of the present invention, unless otherwise clearly specified / defined / limited, when the terms "set", "installed", "connected", "connected", "provided with", "laid", "arranged" appear, they should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection. It can be connection means commonly used in the art such as welding, riveting, bolting, and threaded connection. Such a connection can be a mechanical connection, an electrical connection, or a communication connection; it can be directly connected, or indirectly connected through an intermediate medium, and can be the communication inside two components.

[0047] Embodiment 1

[0048] A full-life cycle camera monitoring system based on a long-span arch bridge, as Figure 1 shown, includes a measurement module, a software processing module, and a visualization management module;

[0049] The measurement module acquires images of measurement target points, and the measurement target points are set at the measured points;

[0050] The software processing module extracts image features from the images of the measurement target points, calculates the spatial coordinates of the measured points according to the image features, generates a real-time change curve according to the spatial coordinates of the measured points, and generates a change amount of the arch axis according to the real-time change curve;

[0051] The visualization management module monitors the long - span arch bridge according to the change amount of the arch axis and the spatial coordinates of the measured points.

[0052] The measurement module includes measurement target points and industrial cameras;

[0053] The industrial camera is used to photograph the measurement target points and obtain the image data of the measured points;

[0054] The measurement target points include luminous markers, reflective markers or natural structural features on the long - span arch bridge. The measurement target points are fixed on the structural surface of the long - span arch bridge through a base plate.

[0055] The industrial camera is fixed at the monitoring point through a base. It is fixed at the monitoring point by means of socket connection, hinge connection or snap - locking with the base.

[0056] The spacing between the arranged measurement target points is determined according to the arch axis equation, and the arch axis equation is calculated based on the arch axis coefficient. The arch axis equation of the long - span arch bridge is constructed and the arch axis coefficient is calculated. Based on the arch axis equation, arch axis coefficient, the force and deflection of the long - span arch bridge, the spacing and quantity of the arranged measurement target points are set.

[0057] The installation positions of the measurement target points include the crown of the arch, the arch feet, 1 / 6L, 1 / 4L, the positions with the maximum bending moment, the positions with the maximum internal force and the positions with the most sensitive changes. L is the total span length of the arch bridge.

[0058] The software processing module includes an image feature extraction solver and a data processor. The image feature extraction solver converts the image feature points into spatial feature points to obtain the time - history coordinates of the measured points. The data processor calculates the change amount of the time - history coordinates of the measured points and generates a real - time change curve of the displacement of the measured points according to the change amount of the time - history coordinates.

[0059] The visualization management module includes a 3D visualization module, a big data storage module, a data prediction and analysis module, an environmental data monitoring module and an abnormal data warning module;

[0060] The 3D visualization module is used to generate a 3D model diagram of the long - span arch bridge, which is used to display the change amount of the spatial coordinates or time - history coordinates of the measured points;

[0061] The big data storage module stores the historical data of the images of the measurement target points and the images of the measurement target points obtained in real - time;

[0062] The data prediction and analysis module analyzes the historical data of the images of the measurement target points, predicts the change of the arch axis by using the historical data, and displays the real - time change curve and the change amount of the arch axis; The environmental data monitoring module displays environmental data;

[0063] The abnormal data warning module is also used to compare the displacement change of the real-time visualization model with a preset threshold, and give a warning when the preset threshold is exceeded.

[0064] Among them, the environmental data includes but is not limited to wind speed, wind direction, temperature and bearing weight, which are directly measured by devices such as analyzers, temperature sensors, and weight sensors. The measured data can be directly displayed on the 3D model interface of the visualization management system for reference by observers.

[0065] Embodiment 2

[0066] A full-life cycle camera monitoring method based on a long-span arch bridge, as Figure 2 shown, the present invention includes the following steps:

[0067] S1: Provide target measuring points and install the target measuring points at key components of the arch bridge.

[0068] S2: Provide a monocular or multiocular industrial camera, and take corresponding images of the target measuring points through the camera.

[0069] S3: Provide an image feature extraction solver, deconstruct the image feature points and convert them into spatial coordinate points to obtain the time-history coordinates of indicators such as the displacement and inclination angle of the measured points.

[0070] S4: Use a data processor to calculate the time-history changes of the spatial coordinates of each monitoring point after conversion, and automatically generate a real-time change curve of the displacement of each monitoring point according to the acquisition frequency.

[0071] S5: According to the data signal transmission system, transmit the monitoring data to the visualization management system in real time.

[0072] S6: Provide a visualization management system. Use the data of each point of the bridge obtained to be reflected in the 3D model diagram of the bridge in real time, and provide the display of the current environmental data.

[0073] S7: Use the visualization management system to analyze the historical monitoring data, make an intelligent prediction of the deformation of the arch axis, set the deflection threshold, and give a warning reminder for abnormal data.

[0074] In an optional implementation manner, in step one, a multi-camera array imaging measurement system composed of monocular or multiocular cameras is adopted in the construction full-life cycle of a long-span stiffening girder concrete arch bridge. According to the physical parameters, geometric parameters and actual working conditions of the long-span arch bridge, select the connection form of the camera array, and select the appropriate measurement camera and measurement target point considering parameters such as the field of view, viewing distance and pixel.

[0075] As Figure 3As shown in the figure, a camera platform is set up near the arch seats of a long-span arch bridge, and a camera is installed. The camera base is bolted to the surface of the measurement base station, and the camera is hinged on the base. The camera includes components such as a photosensitive chip, an aperture, and a lens, and is connected to a data calculation, transmission, and power supply device through a connecting wire. The camera can be rotated and adjusted according to the construction characteristics.

[0076] During the construction period, such as the detailed observation of the coupling pre-assembly, turning over, and hoisting of the arch rib segments, when the measurement platform is less affected by the environment and construction, a monocular camera is used for the deformation measurement in the construction stage, which has the advantages of easy installation and adjustment.

[0077] For the long-term operation stage, a multi-camera can be used for the linear measurement of the arch axis of the arch bridge. When the deformation of the arch axis of the already hoisted segments during the construction period, the in-pipe concrete pouring after closure, the casting of the outer concrete, the arch columns, and the entire observation area during the bridge operation period have large distances, wide viewing angles, and are more affected by interference, a multi-camera is used to maintain the stability and accuracy of the camera measurement.

[0078] During the whole process of monitoring, whether a monocular camera or a multi-camera is used, it is advisable to select an industrial camera with a relatively high resolution. The reasonable range of the camera pixel resolution is 5 million pixels to 20 million pixels. On the premise of ensuring that the measurement accuracy meets the measurement requirements, the appropriate industrial camera can be selected by comprehensively considering the maintenance cost and economic benefits.

[0079] Preferably, the measurement accuracy of the camera measurement system is as follows: for a longitudinal distance of 15 - 50m, the accuracy ≤ ±0.2mm; for a longitudinal distance of 100m, the accuracy < ±0.5mm; for a longitudinal distance of 200m, the accuracy ≤ ±1mm; for a longitudinal distance of more than 300m, the accuracy < ±2mm. The cameras at each measurement station collect images synchronously, and the signal acquisition synchronization time ≤ 1ms. The camera pixel resolution is 5 million pixels to 20 million pixels.

[0080] In particular, one camera can monitor multiple measurement targets simultaneously. At least two cameras are arranged to observe the same target, and calibration is carried out through coordinate calculation to improve the system accuracy and robustness.

[0081] First, the measurement accuracy of the camera measurement system can reach the sub-pixel level, which is more accurate than the traditional optical measurement system. It can perform comprehensive multi-point synchronous measurement on the entire object to be measured, avoiding the deficiencies of local single-point measurement; it can obtain the information of the object to be measured in real time, and perform real-time monitoring and analysis, which can improve the efficiency and timeliness of measurement; it can obtain the information of the object to be measured in real time, and perform real-time monitoring and analysis, which can improve the efficiency and timeliness of measurement; it is equipped with a powerful computer and related software, which can quickly process and analyze the collected data, and generate corresponding reports and images, improving the readability and visualization of the measurement results.

[0082] Second, while ensuring comprehensive monitoring coverage of key sections, the camera measurement system for synchronous camera array shooting measurement of long-span arch bridges improves the overall performance of the system by optimizing the number of camera arrays.

[0083] Secondly, the test system consists of multiple camera arrays and independent test targets. If a test component is damaged due to external force or expired lifespan, only the relevant single test component needs to be replaced. After replacement, the camera or test target can continue to serve the test system to complete the measurement continuation work through coordinate reset calibration. This can not only reduce the operation monitoring cost of long-span arch bridges throughout their lifespan but also provide great convenience. More importantly, it can eliminate the errors caused by replacement and ensure the continuity of full-life monitoring.

[0084] Step 2: According to the physical parameters, geometric parameters, and actual working conditions of the long-span arch bridge, consider the connection form, structural configuration, and matching degree with the camera to select appropriate measurement target points, install them on the surface of the component to be measured, face the camera, and collect images by the camera. During the full-life cycle, use the multi-camera array shooting measurement method to monitor the deformation of the long-span arch bridge under different actual working conditions; for the construction and operation process of the arch bridge, select stress-sensitive components, weld the base of the measurement target point on the surface of the component, and use socket and hinge connections for the measurement target point on the base. The measurement target point can be rotated and adjusted to the appropriate angle and height position according to the structural characteristics and construction features of the long-span arch bridge.

[0085] During the construction process, when it is necessary to monitor working conditions with large spatial position changes such as segment turning over, measurement target points should be installed preferentially at the segment suspension points, chord members, and horizontal bracings to provide physical quantities such as deformation and displacement of key monitoring points; when it is necessary to monitor working conditions with small position changes such as concrete pouring and long-term operation, the positions with the largest bending moment, internal force, and the most sensitive deformation should be considered preferentially for installing measurement target points to provide physical quantities such as deformation and displacement of key monitoring points.

[0086] To ensure the measurement accuracy of the arch axis, at least one measurement target point needs to be installed at a certain interval on the arch bridge, and the reasonable horizontal layout interval between the target points is 10 - 50 meters.

[0087] Long-span arch bridges often adopt the catenary equation. For such arch bridges, when arranging measurement target points, there is a reference factor, the arch axis coefficient:

[0088]

[0089] g j : The load distribution intensity at the arch foot, g d : The load distribution intensity at the arch crown;

[0090] Using the arch axis coefficient, the arch axis equation of the catenary arch bridge can be calculated as:

[0091]

[0092] Among them, m is the arch axis coefficient, f is the height of the arch axis, y is the height of the arch in the vertical direction, that is, the distance from the reference line to any point on the arch, x is the position of the arch in the horizontal direction, that is, the horizontal distance from one end of the arch to any point on the arch, l is the horizontal distance from the crown to the springing point of the arch, and H g is the horizontal thrust of the self-weight of the arch structure (without considering elastic compression), and g d is the intensity of the load distribution at the crown of the arch.

[0093] The magnitude of the arch axis coefficient can indicate the trend of the load-bearing capacity and stability of the arch bridge. The larger the arch axis coefficient, the better the load-bearing capacity and stability of the arch bridge, the fewer the number of measurement target points to be arranged, and the layout interval between the target points can be set to a larger distance. Using the arch axis equation of the catenary arch bridge, the key positions of the arch can be determined, such as the crown, the arch feet, and other important nodes. The non-critical nodes can be reasonably arranged with reference to the magnitude of the arch axis coefficient to accurately position the target points. And because the arch axis equation provides the theoretically ideal shape, by comparing the actual measurement data with the theoretical values, it can be evaluated whether the actual deformation of the arch is within the allowable range.

[0094] For the specific positions of the measurement target points on the arch bridge, in addition to referring to the arch axis coefficient and the arch axis equation, it is also necessary to comprehensively consider the stress conditions and the deflection magnitudes of the arch bridge to arrange the measurement target points. For areas where the internal force change rate of adjacent components is large and the deflection and deformation are large, it is advisable to set multiple measurement target points to accurately monitor the deformation of the arch axis at the key positions.

[0095] In the vertical direction, if the position for installing the target points is insufficient, the measurement target points should be preferentially installed at the center position of the structure surface; if the position for installing the target points is sufficient, it is advisable to evenly arrange multiple target points to ensure robustness.

[0096] If multiple measurement target points are to be installed in the vertical direction, the reasonable vertical layout interval between the target points is 0.5 - 3 meters. When there are multiple measurement target points at the same position, the multiple data obtained from the measurement can be comprehensively calculated by the data resolver to obtain the actual deformation value of the arch axis at that place.

[0097] Under the condition of meeting the reasonable layout distance of the measurement target points, it is preferable to install multiple measurement target points to ensure the redundancy of the measurement system and increase the fault tolerance of the system.

[0098] For an arch bridge with transverse supports, measurement target points should be arranged on the transverse supports, preferably installed at positions that can be monitored by the measurement camera to monitor the transverse displacement and torsion.

[0099] When monitoring the hoisting of segments, due to the involved turning process and large displacement and rotation changes during hoisting, it is advisable to install measurement target points at the positions of chord members and web members in four directions. Measurement target points can be installed on each chord member and web member that can be monitored by the measurement cameras, and are preferably installed at the center of the member. Measurement target points should be installed at nodes, lifting points, and auxiliary members such as suspension rods, support rods, and horizontal bracings. At least one measurement target point should be installed at the ends and the middle of the segment.

[0100] When monitoring the closure process of the main arch ring, additional measurement target points need to be arranged at the middle position of the arch ring.

[0101] When monitoring the concrete in the pouring pipe, at least one measurement target point should be installed at the top, bottom, middle position of the pouring pipe, and near the concrete pouring port.

[0102] In the case where the measurement target points are preferably observed by the nearest camera station, the farther camera station can still observe and measure the measurement target points. The data obtained from the observation is used as an alternative and reference, and the data measured by the nearest measurement base station is preferably taken as the main data.

[0103] Step 3: Install components such as the photogrammetric camera, power supply device, and data resolution device in the measurement base station, as Figure 4 shown. According to the mechanical parameter monitoring indicators in Step 2, the acquired images are transmitted to the data processing part through the measurement hardware part. Each measurement base station is equipped with an independent image acquisition and data processor, transmission and power supply device. Each measurement base station is equipped with an independent image acquisition and data processing system. The main server sends an image synchronization acquisition signal, and the cameras of each measurement base station synchronously acquire images of each measurement target point. Develop an intelligent noise reduction image feature point recognition, extraction, and coordinate transformation system. According to the camera frequency and the coordinate difference of the image feature points before and after, calculate the position change amount of the measurement target point on the image, complete the spatial deconstruction of the measured target, obtain the important monitoring indicators of the spatial deformation of the important monitoring points of the long-span arch bridge, and perform real-time tracking.

[0104] The measurement base station is connected to the ground and can be integrally cast with concrete or fabricated from steel structures.

[0105] Adopt a camera chain for long-term continuous monitoring of the arch axis of the arch bridge, through a multi-station camera relay measurement network composed of high-resolution industrial cameras, measurement target points, and a processing system;

[0106] Each component of the system is independent of each other and is installed in the measurement base station together. Each component can be independently disassembled, installed, and adjusted without affecting the operation of other components. After the component is replaced, it can be automatically calibrated and set to maintain the corresponding parameter settings to ensure the continuity of the monitoring data.

[0107] The environmental status measurement module includes environmental measurement components such as a thermometer, an anemometer, and a weighing scale, and transmits data to the main server in real time through a data signal transmission system together with the camera measurement data.

[0108] Partial replacement and maintenance do not affect the overall measurement, and the comprehensive calculation of the maintenance cost over the entire life cycle is relatively low.

[0109] The image processing part includes the following steps:

[0110] Step 3-1: Select boundary points, perform segmentation processing on the image, extract the characteristic part of the camera measurement target point in the image, perform pattern recognition on the target according to the obtained target characteristics, and use the sub-pixel method to locate and track the positions and movement trajectories of the extracted feature points.

[0111] Step 3-2: According to the mechanical parameter monitoring indicators, obtain the high-precision monitoring results of the synchronous camera measurement of the multi-camera array under different working conditions of the arch bridge, perform physical noise reduction and distortion data elimination on the monitoring data, and obtain the accurate value of the camera measurement.

[0112] Step 3-3: Compare the changes in the three-dimensional coordinates of the measurement target points at different time points, obtain the internal parameters and external parameters by camera calibration, and convert the two-dimensional image data into actual three-dimensional space data. The software processing system converts the detected and tracked luminous marks between the world coordinate system and the image pixel coordinate system. After the conversion from the image pixel coordinate system to the world coordinate system, the change in the displacement of the camera measurement target point is obtained, and the true deformation result is obtained.

[0113] The expression for the conversion between the world coordinate system and the image pixel coordinate system in Step 3-3 is as follows:

[0114] Where [R T] is the external parameter matrix of the camera, K is the internal parameter matrix of the camera, and P is the projection matrix of the camera.

[0115] Where (xw, yw, zw) are the world coordinates and (u, v) are the pixel coordinates.

[0116] Step 3-4: At the initial moment, the software processing system calculates and stores the initial positions (x0, y0) of each camera measurement target point, selects a good sampling frequency. When the measured structure has a linear change, the software processing system will calculate and obtain the positions (xk, yk) of each camera measurement target point at different moments in real time. k = 1, 2, 3, 4, 5...

[0117] Step 3-5: Calculate the displacement change amounts in the X direction and Y direction at different moments:

[0118] X1 = x1 - x0, X2 = x2 - x0, X3 = x3 - x0... Xk = xk - x0

[0119] Y1 = y1 - y0, Y2 = y2 - y0, Y3 = y3 - y0 …… Yk = yk - y0

[0120] Steps Three to Six: By calculating the displacement change of the target measured by the camera, the displacement change diagrams of the target measured by each camera in the X and Y directions can be drawn.

[0121] Step Four - One: According to the pre - preparation of camera measurement in Steps One to Three, a camera array is used for continuous monitoring of the turning - over process during the construction stage, as Figure 5 shown. After the truss - type steel pipe skeleton is processed, it is placed flat on the processing site. The camera measurement system is arranged at both ends of the bridge. When the truss - type steel pipe skeleton is turned over, measurement targets are arranged at each drop rod, suspension point, and chord position. Calibration rods are set on the web members and horizontal bracings at both end faces of the arch rib steel pipe segment for oblique camera calibration. It is rotated from the lying state in the air by lifting the suspension cable and flipped by 90°. The segment is hoisted to the preset position by the cable - suspended crane of the trolley to achieve high - precision closure. For the butt elevation of the chord pipes at the closure joint, the main server of the measurement system sends an image synchronization acquisition signal, and the cameras of each measurement base station synchronously acquire the images of each measurement target.

[0122] Step Four - Two: According to the requirements of camera measurement point layout in Steps One to Three, measurement targets are installed at the top, bottom, and middle positions of the perfusion pipe and near the concrete pouring port. A multi - camera array is used for continuous monitoring of the deformation of the installed arch rib segments during the process of in - pipe concrete perfusion in the construction stage. A pump and a vacuum pump are used for vacuum - assisted and multi - stage jacking perfusion. The deformation of the arch support is monitored at any time during the perfusion process, and the linear change of the arch rib during pouring is observed.

[0123] Step Four - Three: Considering the construction characteristics and mechanical properties of the cast - in - situ concrete of the outsourced concrete of the stiffening - skeleton concrete arch bridge with multi - ring and multi - section and multi - working - face pouring, measurement targets are additionally arranged at positions with large bending moments, internal forces, and sensitive deformation. During the process of pouring the outsourced concrete, a multi - camera array is used for real - time measurement of the deformation of key parts, providing technical support for the construction process. It can achieve multi - point synchronous monitoring of arch bridges with a span of ≥600m. The measuring points can be added and arranged arbitrarily according to requirements, and the synchronous time difference ≤10ms. Moreover, the system can achieve static, quasi - static, and dynamic measurements, and can achieve high - precision and large - span measurements in an unstable platform environment.

[0124] Step Five, as Figure 6 shown, in the operation stage, measurement targets are installed at key positions of the arch bridge, including the crown, arch feet, hinge points, support positions, piers / abutments, and positions with large calculated bending moments, internal forces, and sensitive deformation. Continuous monitoring is carried out using the measurement base stations. A long - term camera measurement base station is established in a wide - view area near the arch bridge. Multiple multi - camera platforms simultaneously measure multiple measurement targets, so the measurement data can be mutually verified to ensure the stability of the camera measurement data.

[0125] Each component of the measurement platform is independent of each other. Local damage or temporary replacement does not affect the operation of other components. After component replacement, the settings can be automatically calibrated to maintain the corresponding parameter settings, ensuring the continuity of monitoring data.

[0126] Step 6: Use the data signal transmission system to transmit the camera measurement data and environmental measurement data of each measurement base station to the main server in the form of a wireless network. The main server can remotely control each component of the measurement base station in the same way.

[0127] Step 7: Based on the camera measurement monitoring of the entire life cycle of the long-span arch bridge construction to operation in Steps 1 to 6, develop a visualization management system, as Figure 7 shown. The visualization management system includes a three-dimensional visualization module, a big data storage module, a data prediction and analysis module, an environmental data monitoring module, and an abnormal data warning module. Based on the measurement data of each measuring station, draw the development trend of the arch axis, record and display environmental factors and variable information, complete the real-time transmission of camera measurement data, long-term storage of data, and visualization development. By measuring the spatial deformation of the structure under its entire life cycle, analyze the influence law of the effect and the development law of the structural deformation, and issue a warning for abnormal data. The visualization management system runs on the back-end server and can achieve visual all-weather observation.

[0128] Particularly, according to specifications such as the "Technical Specification for Building and Bridge Structure Monitoring", the "General Specification for Highway Bridge and Culvert Design", and the "Technical Specification for Highway Bridge and Culvert Construction", set the deflection threshold for the target displacement in advance. Once it is detected that the current data exceeds the threshold, or the system analyzes and predicts a part that may exceed the threshold, the system can immediately issue a warning in the form of a pop-up window, flashing, etc., and list it in the important work log.

[0129] This method integrates a variety of advanced technologies for eliminating systematic errors and test errors, and studies the multi-camera array synchronous camera measurement method for long-span arch bridges. This method can adjust the number of measurement units according to actual monitoring needs, and has the advantages of flexible layout, precise measurement, and automatic processing.

[0130] The above are only the preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principles of the present invention shall be included in the protection scope of the present invention.

Claims

1. A full life cycle camera monitoring system based on a long-span arch bridge, characterized in that: It includes measurement module, software processing module and visual management module; The measuring module acquires an image of a measuring target point, and the measuring target point is set at a measured point; The software processing module extracts image features from the image of the measurement target point, converts the spatial coordinates of the measured point according to the image features, generates a real-time change curve according to the spatial coordinates of the measured point, and generates the change amount of the arch axis according to the real-time change curve; The visualization management module monitors the long-span arch bridge according to the change in the arch axis and the spatial coordinates of the measured points.

2. According to claim 1, a full life cycle camera monitoring system based on a long-span arch bridge is characterized in that: The measurement module includes a measurement target and an industrial camera; The industrial camera is used to photograph the measurement target point and obtain image data of the measured point; The measurement target includes a luminous mark, a reflective mark or a natural structural feature on the long-span arch bridge, and the measurement target is fixed on the structural surface of the long-span arch bridge through a base plate.

3. According to claim 2, a full life cycle camera monitoring system based on a long-span arch bridge is characterized in that: The industrial camera is fixed at the monitoring point via a base, and is fixed at the monitoring point by a sleeve connection, hinge connection or snap lock between the base and the base.

4. According to claim 1, a full life cycle camera monitoring system based on a long-span arch bridge is characterized in that: The spacing of the measurement target points is determined according to the arch axis equation, and the arch axis equation is calculated based on the arch axis coefficient.

5. The full life cycle camera monitoring system based on a long-span arch bridge according to claim 1 is characterized in that: The installation positions of the measurement target points include the arch top, arch foot, 1 / 6L, 1 / 4L, the position with the largest bending moment, the position with the largest internal force and the position with the most sensitive changes, and L is the full span length of the arch bridge.

6. The full life cycle camera monitoring system based on a long-span arch bridge according to claim 1 is characterized in that: The software processing module includes an image feature extraction solver and a data processor. The image feature extraction solver converts image feature points into spatial feature points to obtain the time-course coordinates of the measured points. The data processor calculates the change in the time-course coordinates of the measured points and generates a real-time change curve of the displacement of the measured points based on the change in the time-course coordinates.

7. The full life cycle camera monitoring system based on a long-span arch bridge according to claim 1 is characterized in that: The visualization management module includes a three-dimensional visualization module, a big data storage module, a data prediction and analysis module, an environmental data monitoring module and an abnormal data early warning module; The three-dimensional visualization module is used to generate a 3D model diagram of the long-span arch bridge, which is used to display the change in the spatial coordinates or time-history coordinates of the measured points; The big data storage module stores historical data of images of measurement targets and images of measurement targets acquired in real time; The data prediction and analysis module analyzes the historical data of the image of the measurement target point, uses the historical data to predict the change of the arch axis, and displays the real-time change curve and the change amount of the arch axis; the environmental data monitoring module displays the environmental data; The abnormal data warning module is also used to compare the displacement change of the real-time visualization model with the preset threshold and issue a warning when it exceeds the preset threshold.

8. A full life cycle camera monitoring method based on a long-span arch bridge, characterized in that: The following steps are involved: S1: setting a measurement target point on a long-span arch bridge and acquiring an image of the measurement target point, wherein the measurement target point is set at a measured point; S2: The measurement module sends the acquired image data of the measured point to the software processing module, and the software processing module extracts the image features in the image of the measured target point, converts the spatial coordinates of the measured point according to the image features, generates a real-time change curve according to the spatial coordinates of the measured point, and generates the change amount of the arch axis according to the real-time change curve; The visualization management module monitors the long-span arch bridge according to the spatial coordinates of the measured points and the changes in the arch axis.

9. The full life cycle video monitoring method based on a long-span arch bridge according to claim 8 is characterized in that: The spacing of the measurement target points is determined by the arch axis equation of the arch bridge, and the calculation formula of the arch axis equation is: Among them, m is the arch axis coefficient, f is the height of the arch axis, y is the height of the arch in the vertical direction, that is, the distance from the reference line to any point on the arch, x is the position of the arch in the horizontal direction, that is, the horizontal distance from one end of the arch to any point on the arch, l is the horizontal distance from the arch top to the arch starting point, H g is the horizontal thrust of the arch structure, g d is the concentration of the vault load distribution.

10. The full life cycle video monitoring method based on a long-span arch bridge according to claim 8, characterized in that: The step of generating the variation of the arch axis by the real-time variation curve comprises: S101: Acquire an image of a measurement target; extract feature points of the measurement target from the image of the measurement target, convert the coordinates of the feature points from the image pixel coordinate system to the world coordinate system to obtain three-dimensional coordinates of the feature points, and obtain position information of the measurement target according to the three-dimensional coordinates of the feature points; S102: By comparing the position information of the measurement target at different times, the displacement and inclination change of the measurement target are calculated, and according to the change, a displacement change diagram of the measurement target in the X direction and the Y direction is drawn, so as to obtain a real-time change curve of the measurement target; S103: Generate a change curve of the arch axis according to the real-time change curve of the measurement target point, and obtain the change amount of the arch axis.

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