Suspension bridge measuring system and method based on three-dimensional laser scanning

Abstract

The invention relates to a suspension bridge measurement technology, discloses a suspension bridge measurement system and method based on three-dimensional laser scanning, and aims to realize accurate prediction of a linear graph of a suspension cable part corresponding to a point cloud missing part on the premise of reducing manual intervention and safety risks. According to the scheme, three-dimensional laser scanners are arranged around each suspension cable anchoring area of the bridge floor of the suspension bridge to scan corresponding suspension cables, and suspension cable information obtained through scanning is transmitted to a background server; the server receives the suspension cable information and processes the suspension cable information to obtain point cloud data of each suspension cable, and when it is judged that the point cloud of the suspension cable is missing, based on a linear trend formed by adjacent point clouds above and below the missing point cloud, a preliminary linear graph of a suspension cable part corresponding to the missing point cloud is preliminarily predicted; and then the suspension cable is scanned again by controlling the laser scanners around the corresponding suspension cable anchoring area to move and adjust the angle, and the server predicts a secondary linear graph of the missing point cloud and outputs a final prediction result by integrating the primary linear graph.

Description

TECHNICAL FIELD

[0001] The present application relates to suspension bridge measurement technology, in particular to a kind of suspension bridge measurement system and method based on three-dimensional laser scanning. BACKGROUND

[0002] Three-dimensional laser scanning technology has been widely applied in bridge engineering measurement field due to its high precision, non-contact and high efficiency. Suspension bridge as a complex large-scale engineering structure, the form monitoring of its suspension, bridge deck and other key parts is crucial to ensure the safe operation of the bridge. However, in the process of three-dimensional laser scanning of suspension bridge, due to the high reflectivity coating or rust section on the surface of suspension, the signal reflection is abnormal during laser scanning, and the point cloud data obtained by scanning often has missing problem, which affects the accuracy of subsequent modeling and analysis. To solve this problem, the existing technology usually uses reflective plate to paste on the high-reflective coating section or rust section of the suspension, but this method requires manual operation on the suspension, which not only increases the measurement workload, but also has safety risks of high-altitude operation. SUMMARY

[0003] The technical problem to be solved by the present application is to provide a suspension bridge measurement system and method based on three-dimensional laser scanning, which can accurately predict the linear graph of the missing part of the point cloud corresponding to the suspension part under the premise of reducing manual intervention and safety risk.

[0004] The technical solution adopted by the present application to solve the above technical problem is: On the one hand, the present application provides a suspension bridge measurement system based on three-dimensional laser scanning, comprising: a background server and a plurality of first three-dimensional laser scanners, at least one first three-dimensional laser scanner is arranged around each suspension anchorage zone of the bridge deck of the suspension bridge, for scanning the corresponding suspension, and transmitting the scanned suspension information to the background server; the background server receives the suspension information and processes to obtain the point cloud data of each suspension, when it is judged that the point cloud of the suspension is missing, the preliminary linear graph of the suspension part corresponding to the missing point cloud is preliminarily predicted based on the linear trend formed by the upper and lower adjacent point clouds of the missing part point cloud.

[0005] In the above-mentioned scheme, the first three-dimensional laser scanner is used to scan the suspension information and upload to the background server, the background server processes the suspension information into point cloud data, when it is judged that the point cloud is missing, the preliminary linear graph of the suspension part corresponding to the missing point cloud is preliminarily predicted based on the linear trend formed by the upper and lower adjacent point clouds of the missing part point cloud, compared with the existing method of pasting reflective plate on the part where the point cloud may be missing, the measurement workload of the suspension bridge can be greatly reduced, and the safety risk is reduced.

[0006] Further, when the background server analyzes that the point cloud of the suspension cable is missing, the first three-dimensional laser scanner around the anchoring area of the corresponding suspension cable is controlled to move a set distance and adjust the angle, and then scan the suspension cable again, and the secondary suspension cable information obtained by scanning is transmitted to the background server.

[0007] In the above scheme, the suspension cable is measured again by adjusting the position and angle of the corresponding first three-dimensional laser scanner again, which can verify whether the missing part of the suspension cable point cloud is caused by sudden obstruction or weak reflection itself, and can be used for the background server to comprehensively and accurately predict the missing part based on the point cloud data collected before and after.

[0008] Further, the background server obtains secondary point cloud data of the suspension cable according to the secondary suspension cable information, predicts a secondary line graph of the suspension cable part corresponding to the missing point cloud based on the linear trend formed by the upper and lower adjacent point clouds of the missing part, and combines the preliminary line graph and the secondary line graph to comprehensively predict the line graph of the missing part of the suspension cable point cloud.

[0009] In the above scheme, the secondary point cloud data of the suspension cable is obtained based on the secondary suspension cable information, so as to predict the line graph of the missing part of the secondary point cloud data, thereby obtaining the secondary line graph of the suspension cable corresponding to the missing point cloud, and combining the secondary line graph and the preliminary line graph to predict the line graph of the final missing part of the suspension cable point cloud, which can greatly improve the accuracy of the prediction of the line graph of the missing part of the point cloud.

[0010] Further, the length of the suspension cable corresponding to the missing part is predicted based on the upper and lower adjacent point clouds of the missing part, and only when the predicted length does not exceed a set value, the line graph of the missing part of the suspension cable is predicted.

[0011] In the above scheme, if the length of the suspension cable corresponding to the missing part of the point cloud is too long, the prediction method may have a large error, and in this case, no prediction is performed, and only when the length does not exceed a set value, the prediction is performed.

[0012] Further, the system further comprises a support for mounting the first three-dimensional laser scanner, the support comprising a vertical middle frame body and an arc-shaped horizontal frame body which can slide and be positioned vertically along the middle frame body, a base being arranged at the bottom of the middle frame body, the inner circle of the arc-shaped horizontal frame body being a ring gear, a gear being engaged with the ring gear, the gear being fixed with the output shaft of a motor, the motor being fixed on the side surface of a mounting seat, the first three-dimensional laser scanner being detachably mounted on the top surface of the mounting seat, a horizontal guide frame body being arranged at the upper part of the arc-shaped horizontal frame body, a T-shaped slot being formed on the outer side of the horizontal guide frame body, and a T-shaped sliding block being arranged on the upper surface of the mounting seat and being in sliding cooperation with the T-shaped slot.

[0013] In the above scheme, through the design of the support, not only is the first three-dimensional laser scanner installed, but also the position and angle of the three-dimensional laser scanner can be automatically adjusted. When the position needs to be adjusted, a position adjustment command can be directly issued to start the motor, and the motor output drives the gear to rotate, thereby moving along the arc trajectory of the arc rack, that is, the first three-dimensional laser scanner can be adjusted along the circumferential position of the corresponding cable anchorage area. Through the setting of the guide structure, the movement of the three-dimensional laser scanner is more stable.

[0014] Further, the middle frame body is hollow and open on the side facing the first three-dimensional laser scanner. A vertical screw rod is arranged in the middle frame body and driven by a motor. A connecting seat is arranged on the arc-shaped horizontal frame body, and a strip-shaped opening is formed in the side surface of the middle frame body. The connecting seat extends into the middle frame body through the strip-shaped opening and is circumferentially limited by the inner wall of the middle frame body. Threaded holes are formed in the connecting seat and threadedly connected with the screw rod.

[0015] In the above scheme, when the motor drives the screw rod to rotate, the connecting seat cannot rotate with the screw rod due to the circumferential limitation of the inner wall of the middle frame body, but will rise or fall along the screw rod, thereby adjusting the height position to cooperate with scanning in different directions.

[0016] Further, when the first three-dimensional laser scanner is located in the preset cable scanning height range, it is used for scanning the cable; and when the first three-dimensional laser scanner is located in the preset bridge scanning height and parallel to the bridge deck, it is used for scanning the bridge deck.

[0017] In the above scheme, many other three-dimensional laser scanners do not need to be additionally installed on the bridge deck for measuring the bridge deck, which can greatly save the measurement cost and installation time. When measuring the cable, each first three-dimensional laser scanner is adjusted to a middle or high position, and when measuring the bridge deck, each first three-dimensional laser scanner is adjusted to a low position for measuring the bridge deck.

[0018] Further, a plurality of second three-dimensional laser scanners are further included, which are arranged on the symmetrical observation piers outside the suspension bridge and at the same height as the suspension bridge, and are used for scanning the bridge deck and the cable of the suspension bridge.

[0019] In the above scheme, through the setting of the second three-dimensional laser scanner, complementary scanning with the first three-dimensional laser scanner can be achieved to obtain more reliable point cloud data and models.

[0020] Further, the background server is provided with a preset point cloud density reference standard; when the background server receives the cable information collected by the first three-dimensional laser scanner and processes the point cloud corresponding to the cable, part of the regional point cloud is randomly selected from the point cloud, the regional point cloud density is determined and compared with the point cloud density reference standard, if the regional point cloud density is greater than or equal to the point cloud density reference standard, it is determined that the current scanning is effective.

[0021] In the above scheme, by presetting the point cloud density reference standard in the background server, if the point cloud density obtained by scanning is less than the reference standard, the point cloud data obtained by scanning and the model error may be larger and not applicable, so it needs to be rescaned, only when the regional point cloud density is greater than or equal to the point cloud density reference standard, it is determined that the current scanning is effective. Moreover, the present scheme is not to compare the density of all point clouds, but to randomly select part of the region for comparison, which can reduce the comparison amount and comparison time and improve the efficiency.

[0022] In a second aspect, the present application further provides a suspension bridge measurement method based on three-dimensional laser scanning, comprising the following steps: A plurality of first three-dimensional laser scanners respectively scan corresponding cables, and transmit the scanned cable information to a background server; the background server receives the cable information and processes to obtain point cloud data of each cable; it is judged whether the point cloud of the cable is missing, if so, based on the linear trend formed by the upper and lower adjacent point clouds of the missing part of the point cloud, a preliminary linear graph of the cable part corresponding to the missing point cloud is preliminarily predicted; When the background server analyzes that the point cloud of the cable is missing, the first three-dimensional laser scanner around the anchorage zone of the corresponding cable is controlled to move a set distance and adjust the angle, and then scan the cable again, and transmit the scanned secondary cable information to the background server; The background server obtains secondary point cloud data of the cable according to the secondary cable information, predicts a secondary linear graph of the cable part corresponding to the missing point cloud based on the linear trend formed by the upper and lower adjacent point clouds of the missing part of the point cloud, and combines the preliminary linear graph and the secondary linear graph to comprehensively predict the linear graph of the missing part of the cable point cloud.

[0023] In the above scheme, the point cloud data is obtained by processing the cable information scanned by the first three-dimensional laser scanner, and the point cloud missing judgment is performed, if the point cloud is missing, the preliminary line type diagram of the cable part corresponding to the missing point cloud is preliminarily predicted based on the line type trend formed by the upper and lower adjacent point clouds of the missing part point cloud, then the position of the first three-dimensional laser scanner around the cable with missing point cloud part is adjusted, the cable information is scanned again and uploaded, the point cloud data is obtained by the server based on the secondary cable information, and the secondary line type diagram of the cable part corresponding to the missing point cloud is predicted based on the line type trend formed by the upper and lower adjacent point clouds of the missing part point cloud; finally, the line type diagram of the missing part of the cable point cloud is comprehensively predicted by combining the preliminary line type diagram and the secondary line type diagram, so as to improve the prediction accuracy.

[0024] The beneficial effects of the present application are: (1) Reduce the measurement workload and safety risk: By predicting the preliminary line type diagram of the missing part based on the line type trend of the upper and lower adjacent point clouds of the missing part point cloud, it is not necessary to paste a reflector plate on the high-reflective coating section or the rusted section of the cable, thereby reducing manual high-altitude operation and reducing workload and safety risk.

[0025] (2) Improve the accuracy of line type prediction of the missing part: By adjusting the position and angle of the first three-dimensional laser scanner for secondary scanning, the missing part line type is comprehensively predicted by combining the preliminary line type diagram and the secondary line type diagram, thereby improving the prediction accuracy; at the same time, only the part with a missing length not exceeding the set value is predicted, thereby avoiding large errors caused by long-distance missing.

[0026] (3) Realize flexible adjustment and multifunctional reuse of the measuring equipment: Based on the design of the special support, the first three-dimensional laser scanner can be automatically adjusted in the circumferential and height directions to ensure the scanning stability; and the scanner can scan the cable at the medium and high positions, and can scan the bridge deck when being at the low position and being parallel to the bridge deck, thereby saving cost and time without the need of additional installation of equipment.

[0027] (4) Improve the reliability of point cloud data and model: The complementary scanning of the second three-dimensional laser scanner and the first three-dimensional laser scanner compensates for the limitations of single device scanning; the fixed coordinate characteristics of the second scanner can correct the coordinate deviation caused by the bridge deck deformation of the first scanner, thereby improving the accuracy of point cloud data and model.

[0028] (5) Optimize the scanning effectiveness judgment efficiency: The background server determines the scanning effectiveness by comparing the point cloud density of part of the area with the reference standard, thereby reducing the comparison amount and time and improving the work efficiency without the need of processing all point clouds. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 A cross-sectional view of a support for a first three-dimensional laser scanner in an embodiment of the present application.

[0030] Figure 2 A flowchart of a method for measuring a suspension bridge based on three-dimensional laser scanning in an embodiment of the present application.

[0031] In the figure, 1 is a base, 2 is a middle frame body, 3 is a screw rod, 4 is a connecting seat, 5 is an arc-shaped horizontal frame body, 6 is a gear, 7 is a motor, 8 is a mounting seat, 9 is a first three-dimensional laser scanner, 10 is a horizontal guide frame body, and 11 is a T-shaped sliding block. DETAILED DESCRIPTION

[0032] The present application aims to provide a suspension bridge measurement system and method based on three-dimensional laser scanning, which realizes accurate prediction of the line graph of the missing part of the point cloud under the premise of reducing manual intervention and safety risks. The core idea is: by setting a first three-dimensional laser scanner in the suspension anchorage zone, combining the processing of the suspension point cloud data by the background server, predicting the line graph of the missing part based on the line trend of the adjacent point clouds above and below the missing part, and using an adjustable support to automatically adjust the position and angle of the scanner, supporting the reuse of scanning of the suspension and the bridge surface, and introducing a second three-dimensional laser scanner outside the bridge for complementary scanning and coordinate correction, ultimately improving the efficiency, accuracy and equipment utilization of suspension bridge measurement under the premise of reducing workload and safety risks.

[0033] The specific implementation means of the above core idea of the present application include but are not limited to: With the powerful computing power of the background server, the present application predicts the preliminary line graph of the missing part according to the line trend of the point clouds in the adjacent areas above and below the missing part point cloud. And by controlling the first three-dimensional laser scanner to perform secondary scanning, the line graphs generated by the primary and secondary scanning are fused, which significantly improves the prediction accuracy, accurately restores the true form of the suspension, effectively avoids measurement errors caused by point cloud missing, and ensures the integrity and reliability of the measurement data.

[0034] The special support designed by the present application integrates an automatic adjustment function. The first three-dimensional laser scanner can accurately vertically slide along the middle frame body, and can flexibly adjust the scanning position and angle by cooperating with the circumferential rotation of the arc-shaped horizontal frame body, ensuring the stability and accuracy of the scanning process. At the same time, the same scanner can not only complete fine scanning of the suspension at different heights and attitudes, but also can measure the bridge surface, greatly expanding the application range of the equipment and avoiding the increase in cost and installation time caused by installing separate equipment for different parts.

[0035] In order to further improve the accuracy of the measurement, the application introduces a second three-dimensional laser scanner arranged on the outer symmetrical observation pier of the suspension bridge, which cooperates with the first three-dimensional laser scanner around the anchoring area. The second three-dimensional laser scanner can effectively correct the error caused by the small deformation of the bridge deck under external force, which causes the coordinate of the first three-dimensional laser scanner installed on the bridge deck to change, and ensures that the measurement data always maintains high accuracy.

[0036] The preferred embodiments of the application will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described below are only used to explain the application and do not limit the scope of protection of the application. In addition, the terms "first", "second" and the like used in the application are used to distinguish similar objects, not to describe a specific order or sequence.

[0037] The embodiment first provides a suspension bridge measurement system based on three-dimensional laser scanning, which includes a background server and a plurality of first three-dimensional laser scanners arranged around each suspension anchoring area of the bridge deck of the suspension bridge. The spacing between adjacent first three-dimensional laser scanners is set to 60-80m. Each first three-dimensional laser scanner is used to scan the corresponding suspension cable and transmit the scanned suspension cable information to the background server. The background server receives each suspension cable information and processes it to obtain the point cloud data of each suspension cable. The background server is provided with a point cloud density reference standard. After obtaining the point cloud data of the suspension cable, some area point clouds are randomly selected from the point cloud to determine the area point cloud density. The obtained area point cloud density is compared with the stored point cloud density reference standard. If the area point cloud density is greater than or equal to the point cloud density reference standard, it is determined that the current scanning is effective. Then, it is determined whether there is a missing point cloud of the suspension cable. If yes, the length of the suspension cable corresponding to the missing part of the point cloud is predicted based on the point clouds above and below the missing part of the point cloud. If the predicted length does not exceed the set value, the linear graph of the missing part of the suspension cable is predicted.

[0038] In an exemplary embodiment, the process of the background server receiving each suspension cable information and processing it to obtain the point cloud data of each suspension cable is as follows: The Gaussian filter is used for denoising the scanned cable information (containing original point cloud data of massive three-dimensional coordinate points of the cable surface), eliminating noise, and performing point cloud segmentation to obtain the relevant point cloud of the cable, and then fitting, such as using the random sample consensus algorithm RANSAC for fitting to obtain the linear type of the corresponding cable. Specifically, first, randomly select samples for linear estimation; then, calculate the distance of each point in the data set to the estimated linear type, if the distance of the point to the estimated linear type is less than the pre-set consistency threshold, the point is consistent with the linear type, and the point is added to the consistency set, if the distance of the point to the estimated linear type is greater than or equal to the consistency threshold, the point is ignored; thirdly, the quality of the current model is evaluated according to the number of points in the consistency set; finally, repeat the above steps, iterate N times, and return the best linear type that meets the requirements. The "best linear type" is the reference morphological feature of the cable point cloud.

[0039] In an exemplary embodiment, the process of predicting the linear type of the missing part of the cable is as follows: The background server processes the point cloud data of the cable to obtain a three-dimensional model of the cable, then applies an edge detection algorithm to the generated three-dimensional model to identify the edge lines of the cable from the three-dimensional model, divides the edge lines into a plurality of single lines based on the standard line length by setting the standard line length, calculates the curvature of each single line, if the curvature of each single line is within the set curvature threshold range, the single line segmentation is effective, if not, the standard line length is reset, the above steps are repeated to re-segment each single line, until the curvature of each single line is within the set curvature threshold range. Then, the intersection point of the tangent of the lowermost single line above the missing part and the tangent of the uppermost single line below the missing part is taken as the predicted connection point of the missing part, a plurality of predicted single lines are extended upwards and downwards from the predicted connection point respectively until the plurality of predicted single lines are connected end to end and connected with the lowermost single line above and the uppermost single line below, the curvatures of the predicted single lines are calculated, if the curvatures of the predicted single lines are within the same range as the curvatures of the upper single line and the lower single line, the linear prediction is completed, otherwise, continue to repeat the prediction in the above manner.

[0040] On the basis of the above system, the preliminary line profile of the missing part of the cable point cloud can be predicted, but in actual application scenarios, the first three-dimensional laser scanner may miss part of the point cloud when scanning the cable due to temporary obstructions. At this time, the preliminary line profile of the missing part of the cable point cloud may have a large deviation from the actual situation. In order to improve the accuracy of the prediction, the position and angle of the first three-dimensional laser scanner can be adjusted to scan the cable again, and the line profile of the missing part of the point cloud is predicted again based on the scanning results, and the preliminary line profile is comprehensively obtained to obtain the final prediction result.

[0041] In order to realize the automatic adjustment of the position of the first three-dimensional laser scanner, reduce manual intervention, and save labor and time cost, the embodiment sets a support for installing the first three-dimensional laser scanner. The support can automatically adjust the position of the first three-dimensional laser scanner. In an exemplary embodiment, the structure of the support is as shown in Figure 1 The support includes a vertical middle frame body 2 and an arc-shaped horizontal frame body 5 that can slide vertically and be positioned along the middle frame body 2. A base 1 is provided at the bottom of the middle frame body 2. The inner circle of the arc-shaped horizontal frame body 5 is a ring gear. A gear 6 is provided to engage with the ring gear. The gear 6 is fixed to the output shaft of a motor 7. The motor 7 is fixed to the side of a mounting seat 8. The first three-dimensional laser scanner 9 can be detachably mounted on the top surface of the mounting seat 8. A horizontal guide frame 10 is provided on the upper part of the arc-shaped horizontal frame body 5. A guide structure is provided between the upper side of the mounting seat 8 and the guide frame. Specifically, a T-shaped slot is opened on the outer side of the guide frame. A T-shaped sliding block 11 is provided on the upper side of the mounting seat 8 to slide with the T-shaped slot. The middle frame body 2 is hollow and open on the side facing the first three-dimensional laser scanner 9. A vertical screw rod 3 is provided inside the middle frame body 2. The screw rod 3 is driven by the motor 7. A connecting seat 4 is provided on the arc-shaped horizontal frame body 5. A strip-shaped opening is provided on the side of the middle frame body 2. The connecting seat 4 extends into the middle frame body 2 through the strip-shaped opening to limit the circumference of the middle frame body 2. Threaded holes are provided on the connecting seat 4. The connecting seat 4 is threadedly connected with the screw rod 3 through the threaded holes.

[0042] In the embodiment, when the first three-dimensional laser scanner is located at a middle-high position, the first laser scanner is used for scanning the cable. When the first three-dimensional laser scanner is located at a low position and parallel to the bridge deck, the first three-dimensional laser scanner is used for scanning the bridge deck. In the embodiment, the angle adjustment of the first three-dimensional laser scanner is realized by the existing structure design of the instrument itself, which belongs to the prior art and will not be described here.

[0043] The embodiment further includes a plurality of second three-dimensional laser scanners provided on a plurality of symmetrical observation piers outside the suspension bridge and consistent with the height of the suspension bridge. The plurality of second three-dimensional laser scanners are used for scanning the bridge deck and the cable of the suspension bridge.

[0044] In this embodiment, first, the second three-dimensional laser scanner is arranged, and the plurality of second laser scanners are fixed on the observation pier outside the suspension bridge and consistent with the height of the suspension bridge, instead of being fixed on the bridge deck of the suspension bridge itself. Therefore, when the bridge deck is scanned by the second laser scanner, if the bridge deck is slightly deformed due to some external force factors, the positions of the plurality of second laser scanners will not change following the deformation of the bridge deck, that is, the coordinates of each second laser scanner will not change, so that the bridge deck point cloud obtained after scanning the bridge deck can be guaranteed, and the coordinate transformation can be more accurate. Therefore, the bridge deck point cloud and the three-dimensional model of the bridge deck obtained by scanning by the second laser scanner will be more accurate.

[0045] Secondly, the bridge deck point cloud data and the three-dimensional model of the bridge deck obtained by scanning by the second laser scanner can be used to correct and compensate the coordinates of the plurality of first three-dimensional laser scanners arranged on the bridge deck. Since the first three-dimensional laser scanner is installed on the bridge deck, when the bridge deck is affected by external forces (such as wind load) and is deformed, whether the suspension cable or the bridge deck is scanned by the first three-dimensional laser scanner, the scanning accuracy will be affected due to the dynamic change of the coordinates of the first three-dimensional laser scanner itself. Therefore, after the three-dimensional model of the bridge deck is obtained by the bridge deck point cloud data collected by the second three-dimensional laser scanner, the coordinates of the first three-dimensional laser scanner can be compensated and corrected, so that the point cloud data and the model obtained by the first three-dimensional laser scanner after scanning are also more accurate.

[0046] Further, after the coordinates of the first laser scanner are compensated by the scanning results of the second laser scanner, the system obtains a more accurate model data by comparing, synthesizing and extracting the cable models obtained from the point cloud data scanned by the plurality of first laser scanners and the point cloud data scanned by the plurality of second three-dimensional laser scanners in the cable measurement of the suspension bridge. Since the point cloud data is obtained by scanning with the first three-dimensional laser scanner alone, in addition to the high reflectivity or corrosion of the cable part, there may also be occlusion between structures on the cable. Moreover, the first three-dimensional laser scanner is installed in the anchorage area of the cable, and the reflected signal of the free end of the cable may be relatively weak, and the collected point cloud data is limited. Therefore, the first three-dimensional laser scanner alone may still have the problem of low measurement accuracy. If the second three-dimensional scanner is used alone to scan the cable, since the second three-dimensional scanner is far away from the cable, the reflected signal of some thin cables far away from the second three-dimensional laser scanner may be weak, and there may also be occlusion between cable structures. Therefore, the system compares, synthesizes and extracts the point cloud data scanned by the first laser scanner and the point cloud data scanned by the second three-dimensional laser scanner to make up for the shortcomings of both, so as to obtain more accurate point cloud data and further obtain a more accurate, perfect and more consistent three-dimensional model of the current state of the cable.

[0047] Similarly, the system compares, synthesizes and extracts the point cloud data obtained by scanning the bridge deck with the first three-dimensional laser scanner and the point cloud data obtained by scanning the bridge deck with the second three-dimensional laser scanner to obtain a more accurate, perfect and more consistent three-dimensional model of the current state of the bridge deck of the suspension bridge. Although the first three-dimensional laser scanner is arranged on the bridge deck and is closer to the bridge deck, and is arranged at the same height as the bridge deck during measurement, the bridge deck itself may be blocked by passing vehicles, which may affect the detection accuracy of the bridge deck. For the second three-dimensional laser scanner, the vehicles on the bridge deck have little effect on it. However, the second three-dimensional laser scanner is installed on the observation pier outside the bridge, that is, the number of installations is limited, and it may not be installed near the middle of the bridge (for example, the suspension bridge is high or the river-crossing bridge, and the observation pier cannot be arranged near the middle or water area), so the scanning near the middle may have the problem of weak reflection and less point cloud data due to the long distance. Therefore, the system combines the point cloud data obtained by the first three-dimensional laser scanner and the point cloud data obtained by the second three-dimensional laser scanner to make up for the respective shortcomings and improve the scanning accuracy to establish a more accurate bridge deck model.

[0048] Finally, the embodiment also provides a suspension bridge measurement method based on three-dimensional laser scanning, which is described with reference to Figure 2 and includes the following steps: The corresponding suspension cable is scanned by a plurality of first three-dimensional laser scanners respectively, and the scanned suspension cable information is transmitted to a background server; the background server receives the suspension cable information and processes to obtain point cloud data of each suspension cable; it is judged whether the point cloud of the suspension cable is missing, if so, based on the linear trend formed by the upper and lower adjacent point clouds of the missing part of the point cloud, the preliminary linear graph of the suspension cable part corresponding to the missing point cloud is preliminarily predicted; When the background server analyzes that the point cloud of the suspension cable is missing, the first three-dimensional laser scanner around the anchorage zone of the corresponding suspension cable is controlled to move a set distance and adjust the angle, and then scan the suspension cable again, and the scanned secondary suspension cable information is transmitted to the background server; The background server obtains secondary point cloud data of the suspension cable according to the secondary suspension cable information, predicts the secondary linear graph of the suspension cable part corresponding to the missing point cloud based on the linear trend formed by the upper and lower adjacent point clouds of the missing part of the point cloud, and combines the preliminary linear graph and the secondary linear graph to comprehensively predict the linear graph of the missing part of the suspension cable point cloud.

[0049] It should be noted that the specific step implementation means in the suspension bridge measurement method has been fully described in the foregoing system description, and will not be repeated here.

[0050] Although the embodiments of the present application have been described, it can be understood by those skilled in the art that various changes, modifications, replacements and variations can be made to these embodiments without departing from the principles and spirits of the present application, and all of them are within the protection scope of the present application.

Claims

1. A system for measuring a suspension bridge based on three-dimensional laser scanning, Characterized in that, It comprises: A background server and a plurality of first three-dimensional laser scanners, at least one of which is arranged around each cable anchorage area of the suspension bridge deck to scan the corresponding suspension cable and transmit the scanned suspension cable information to the background server; The background server receives the suspension cable information and processes the point cloud data of each suspension cable. When it is determined that the point cloud of the suspension cable is missing, the preliminary linear pattern of the missing part of the suspension cable corresponding to the missing point cloud is predicted based on the linear trend formed by the upper and lower adjacent point clouds of the missing part.

2. The three-dimensional laser scanning-based suspension bridge measurement system according to claim 1, characterized in that, When the background server analyzes that the point cloud of the suspension cable is missing, the first three-dimensional laser scanner around the corresponding suspension cable anchorage area is controlled to move a set distance and adjust the angle before scanning the suspension cable again, and the secondary suspension cable information scanned is transmitted to the background server.

3. The three-dimensional laser scanning-based suspension bridge measurement system according to claim 2, characterized in that, The background server obtains the secondary point cloud data of the suspension cable according to the secondary suspension cable information, predicts the secondary linear pattern of the missing part of the suspension cable corresponding to the missing point cloud based on the linear trend formed by the upper and lower adjacent point clouds of the missing part, and combines the preliminary linear pattern and the secondary linear pattern to comprehensively predict the linear pattern of the missing part of the suspension cable point cloud.

4. The three-dimensional laser scanning-based suspension bridge measurement system according to claim 1, characterized in that, The length of the missing part of the suspension cable corresponding to the missing point cloud is predicted based on the upper and lower adjacent point clouds of the missing part, and only when the predicted length does not exceed a set value, the linear pattern of the missing part of the suspension cable is predicted.

5. The three-dimensional laser scanning-based suspension bridge measurement system according to claim 1, characterized in that, The system further comprises a support for mounting the first three-dimensional laser scanner, the support comprising a vertical middle frame body and an arc-shaped horizontal frame body that can slide and be positioned vertically along the middle frame body, a base being arranged at the bottom of the middle frame body, the inner circle of the arc-shaped horizontal frame body being a ring gear, a gear being engaged with the ring gear, the gear being fixed with the output shaft of a motor, the motor being fixed on the side of a mounting seat, the first three-dimensional laser scanner being detachably mounted on the top surface of the mounting seat, a horizontal guide frame body being arranged at the upper part of the arc-shaped horizontal frame body, a T-shaped slot being opened on the outer side of the horizontal guide frame body, and a T-shaped sliding block being arranged on the upper side of the mounting seat and being in sliding cooperation with the T-shaped slot.

6. The three-dimensional laser scanning-based suspension bridge measurement system according to claim 5, characterized in that, The middle frame body is hollow and open on the side facing the first three-dimensional laser scanner, a vertical screw rod being arranged in the middle frame body, the screw rod being driven by a motor, a connecting seat being arranged on the arc-shaped horizontal frame body, a strip-shaped opening being opened on the side of the middle frame body, the connecting seat extending into the interior of the middle frame body through the strip-shaped opening to limit the circumference of the middle frame body, and a threaded hole being opened on the connecting seat and being in threaded cooperation with the screw rod.

7. The three-dimensional laser scanning-based suspension bridge measurement system according to claim 6, characterized in that, When the first three-dimensional laser scanner is located at a preset suspension cable scanning height range, the first three-dimensional laser scanner is used to scan the suspension cable; when the first three-dimensional laser scanner is located at a preset bridge deck scanning height and is parallel to the bridge deck, the first three-dimensional laser scanner is used to scan the bridge deck. 8.The three-dimensional laser scanning based suspension bridge measurement system according to claim 7, further comprising a plurality of second three-dimensional laser scanners, wherein the plurality of second three-dimensional laser scanners are arranged on symmetric observation piers outside the suspension bridge and at a height consistent with the suspension bridge, and are used to scan the bridge deck and the suspension cables of the suspension bridge. 9.The three-dimensional laser scanning based suspension bridge measurement system according to claim 1, further comprising a plurality of second three-dimensional laser scanners, wherein the plurality of second three-dimensional laser scanners are arranged on symmetric observation piers outside the suspension bridge and at a height consistent with the suspension bridge, and are used to scan the bridge deck and the suspension cables of the suspension bridge. 8.The three-dimensional laser scanning based suspension bridge measurement system according to claim 7, further comprising a plurality of second three-dimensional laser scanners, wherein the plurality of second three-dimensional laser scanners are arranged on symmetric observation piers outside the suspension bridge and at a height consistent with the suspension bridge, and are used to scan the bridge deck and the suspension cables of the suspension bridge. 9.The three-dimensional laser scanning based suspension bridge measurement system according to claim 1, further comprising a plurality of second three-dimensional laser scanners, wherein the plurality of second three-dimensional laser scanners are arranged on symmetric observation piers outside the suspension bridge and at a height consistent with the suspension bridge, and are used to scan the bridge deck and the suspension cables of the suspension bridge.

10. The method for measuring a suspension bridge based on three-dimensional laser scanning, applied to the system for measuring a suspension bridge based on three-dimensional laser scanning as claimed in any one of claims 1-9, characterized in that, 8.The three-dimensional laser scanning based suspension bridge measurement system according to claim 7, further comprising a plurality of second three-dimensional laser scanners, wherein the plurality of second three-dimensional laser scanners are arranged on symmetric observation piers outside the suspension bridge and at a height consistent with the suspension bridge, and are used to scan the bridge deck and the suspension cables of the suspension bridge. 9.The three-dimensional laser scanning based suspension bridge measurement system according to claim 1, further comprising a plurality of second three-dimensional laser scanners, wherein the plurality of second three-dimensional laser scanners are arranged on symmetric observation piers outside the suspension bridge and at a height consistent with the suspension bridge, and are used to scan the bridge deck and the suspension cables of the suspension bridge. 8.The three-dimensional laser scanning based suspension bridge measurement system according to claim 7, further comprising a plurality of second three-dimensional laser scanners, wherein the plurality of second three-dimensional laser scanners are arranged on symmetric observation piers outside the suspension bridge and at a height consistent with the suspension bridge, and are used to scan the bridge deck and the suspension cables of the suspension bridge. 9.The three-dimensional laser scanning based suspension bridge measurement system according to claim 1, further comprising a plurality of second three-dimensional laser scanners, wherein the plurality of second three-dimensional laser scanners are arranged on symmetric observation piers outside the suspension bridge and at a height consistent with the suspension bridge, and are used to scan the bridge deck and the suspension cables of the suspension bridge. 8.The three-dimensional laser scanning based suspension bridge measurement system according to claim 7, further comprising a plurality of second three-dimensional laser scanners, wherein the plurality of second three-dimensional laser scanners are arranged on symmetric observation piers outside the suspension bridge and at a height consistent with the suspension bridge, and are used to scan the bridge deck and the suspension cables of the suspension bridge. 9.The three-dimensional laser scanning based suspension bridge measurement system according to claim 1, further comprising a plurality of second three-dimensional laser scanners, wherein the plurality of second three-dimensional laser scanners are arranged on symmetric observation piers outside the suspension bridge and at a height consistent with the suspension bridge, and are used to scan the bridge deck and the suspension cables of the suspension bridge.

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