Tilt-angle-free stablilizing mount for image-based deflectometer, and method for eliminating tilt-angle error of image-based deflectometer

Abstract

A tilt-angle-free stabilizing mount for an image-based deflectometer (3), and a method for eliminating a tilt-angle error of the image-based deflectometer (3), the mount comprising a supporting assembly (6) and a suspending assembly (5), wherein the supporting assembly (6) is mounted at a deflection monitoring point on a bridge, the suspending assembly (5) is mounted below the supporting assembly (6), the suspending assembly (5) can rotate about at least one fulcrum (4) relative to the supporting assembly (6), and the image-based deflectometer (3) is mounted on the suspending assembly (5); and a rotary connection portion is provided between the supporting assembly (6) and the suspending assembly (5) so as to be capable of restricting the movement of the suspending assembly (5) in the longitudinal and transverse directions of the bridge, such that the suspending assembly (5) pitches only in a vertical plane under the action of gravity.

Description

Image deflectometer tilt-free stabilizing bracket and method for eliminating tilt error in image deflectometer Technical Field

[0001] This application relates to the field of bridge health monitoring technology, and in particular to a tilt-free stabilizing bracket for an image deflectometer and a method for eliminating tilt error in an image deflectometer. Background Technology

[0002] The static and dynamic deflection of a bridge reflects its overall vertical stiffness and is a crucial indicator for assessing its structural condition and performance, playing a significant role in bridge health monitoring. Currently, there are over one million highway bridges in service in China, among which continuous beam bridges constitute a large proportion due to their advantages such as negative bending moments at supports resisting positive bending moments at mid-span, light weight, mature construction technology, good overall integrity, and fewer expansion joints on the bridge deck. However, with the increasing volume of traffic and heavy-duty vehicles, the deterioration of material properties, and untimely maintenance, a considerable number of bridges have developed concrete cracking defects, such as vertical, transverse, and diagonal cracks in the top slab, bottom slab, and mid-span web, leading to insufficient overall vertical stiffness and reduced safety margin. Therefore, accurate and convenient monitoring of the static and dynamic deflection of continuous beam bridges during operation has become a practical need for evaluating bridge service performance and providing timely structural safety warnings. Currently, the main methods for measuring the static and dynamic deflection of continuous beam bridges include the displacement gauge method, leveling instrument method, connecting pipe method, GPS method, and millimeter-wave radar method.

[0003] However, displacement gauges require mounting on fixed supports, making them unsuitable for bridges spanning rivers or deep valleys; optical levels cannot measure dynamic deflection; connecting pipes suffer from insufficient real-time monitoring due to fluid flow resistance and are limited by range, making them unsuitable for long-span bridges with significant longitudinal slopes; GPS is susceptible to satellite clock errors, orbital errors, and ionospheric errors, making it difficult to guarantee long-term stable positioning accuracy of the receiving terminal; and millimeter-wave radar devices are expensive and difficult to deploy in large quantities. With the development of machine vision and photoelectric sensing technologies, bridge static and dynamic deflection measurement methods based on digital image correlation (DIC) are gradually being applied to long-term monitoring of bridge structural displacement due to their advantages of non-contact operation, multi-point synchronous monitoring, high measurement accuracy, and low equipment cost. Digital image correlation is a measurement method that tracks (or matches) the same physical point (or pixel) between a reference image and a target image. Through correlation calculation and sub-pixel interpolation, it accurately measures the relative change in the number of pixels of multiple target points on the camera image under vehicle load, and then, combined with the conversion between pixel coordinates and world coordinates, outputs the actual deformation result.

[0004] However, for the numerous and widespread continuous beam bridges, deflection monitoring methods based on digital image correlation still have certain shortcomings. Variable cross-section continuous beam bridges undergo displacement under vehicle loads, causing deflection and vertical deformation of the image deflectometer, target, and reference target, introducing errors into deflection testing and making it difficult to fully utilize the advantages of digital image correlation technology in deflection monitoring.

[0005] Patent application CN117824959A addresses the aforementioned issues by proposing a method for correcting deflection monitoring errors in continuous beam bridges based on digital image measurement. This method analyzes the distribution range and patterns of related errors through image deflectometer and target deflection tests, constructing a deflection monitoring error model library for continuous beam bridges of different spans. Based on this error model library, it corrects deflection monitoring errors. However, due to the varying digital image correlation algorithms among different image deflectometer manufacturers, this invention's method of clarifying image deflectometer deflection test errors through testing is difficult to adapt to all manufacturers' image deflectometers. Even if adaptation is successful, these manufacturers will subsequently upgrade and optimize their digital image correlation algorithms, rendering the initially established deflection monitoring error model library inapplicable. Furthermore, limitations in test sites, costs, and instruments make it difficult to cover bridges of different spans, resulting in insufficient applicability of the deflection monitoring error model library.

[0006] Summary of the Invention

[0007] To address the problems existing in the prior art, this application proposes a tilt-free stabilizing bracket for an image deflectometer and a method for eliminating tilt errors in the image deflectometer. This eliminates the need for a reference target, thus eliminating the possibility of reverse errors caused by the reference target, improving the installation efficiency, stability, and testing accuracy of the image deflectometer, and reducing the implementation cost of the bridge health monitoring system.

[0008] In a first aspect, this application provides a tilt-free stabilizing bracket for an image deflectometer, comprising:

[0009] Support components are installed at the deflection monitoring points;

[0010] A suspension assembly is installed below the support assembly. At least one rotatable connection is provided between the suspension assembly and the support assembly. The suspension assembly rotates relative to the support assembly around a pivot point on the rotatable connection, so that when the support assembly pitches under vehicle load, the suspension assembly rotates around the pivot point under gravity to adjust the deflection angle of the vertical plane.

[0011] An image deflectometer is mounted on the suspension assembly.

[0012] In one embodiment of the first aspect, the support assembly includes a first mounting portion mounted on the top plate of the chamber near block zero, the first mounting portion extending longitudinally along the bridge; the suspension assembly is mounted below the first mounting portion, the suspension assembly forming a relative rotational connection with the first mounting portion around a fulcrum.

[0013] In one embodiment of the first aspect, the support assembly includes a first mounting portion and a second mounting portion, the first mounting portion being mounted on the transverse diaphragm of block zero; the second mounting portion extending longitudinally along the bridge, one end of the second mounting portion being fixedly connected to the first mounting portion; the suspension assembly being mounted below the second mounting portion, the suspension assembly forming a relative rotational connection with the second mounting portion around a fulcrum.

[0014] In one embodiment of the first aspect, a first limiting groove extending laterally along the bridge is provided at the rotatable connection between the support assembly and the suspension assembly, the width of the first limiting groove being greater than the diameter of the screw; the rotatable connection includes a plurality of screws, which, after passing through the suspension assembly, limit the suspension assembly within the first limiting groove.

[0015] In one embodiment of the first aspect, the bottom of the first limiting groove does not penetrate the support assembly, and a second limiting groove is formed at the bottom of the first limiting groove. The width of the second limiting groove is smaller than the width of the first limiting groove, but larger than the diameter of the screw. After the screw passes through the suspension assembly, it limits the suspension assembly to the second limiting groove.

[0016] Furthermore, the first limiting groove and / or the second limiting groove are arc-shaped grooves.

[0017] In one embodiment of the first aspect, the suspension assembly includes a counterweight. When the support assembly generates a pitch angle under vehicle load, the counterweight drives the rotating connection to rotate counterclockwise or clockwise around the fulcrum, so that the suspension assembly restores balance and adjusts the deflection angle of the vertical plane.

[0018] In one embodiment of the first aspect, the number of the fulcrums is multiple, and the line connecting the multiple fulcrums is parallel to the transverse direction of the bridge.

[0019] Secondly, this application provides a method for eliminating tilt angle error in an image deflectometer, comprising the following:

[0020] The support assembly is installed longitudinally along the bridge at the deflection monitoring point. The height of the suspension assembly below the support assembly and the direction of the image deflectometer are adjusted so that the camera's field of view covers the target. The suspension assembly forms a relative rotational connection with the support assembly around the fulcrum.

[0021] Under the vehicle load, the zero block undergoes a pitch angle change, causing the support component to deflect by an angle of θ. The suspension component, due to gravity, undergoes a pitch rotation in the vertical plane around the fulcrum that is opposite to the pitch angle change of the zero block. After the suspension component returns to balance, the bracket undergoes a vertical displacement of x in the vertical plane.

[0022] Define the length of the support component along the longitudinal direction of the bridge as h. According to geometric relationships, the vertical displacement of the support in the vertical plane is x≈sinθ·h≈θ.

[0023] In one embodiment of the second aspect, the support assembly is mounted on the diaphragm of block zero or on the top plate of the chamber near block zero.

[0024] Compared with the prior art, this application has the following beneficial effects:

[0025] This application achieves a self-balancing effect by using a rotating connection between the support assembly and the suspension assembly, so that when the support assembly pitches under vehicle load, the suspension assembly can rotate around the fulcrum of the two components, ensuring that the center of gravity of the suspension assembly is always below the fulcrum. This allows the camera's tilt angle to be automatically eliminated by gravity.

[0026] This application sets a limiting groove at the fulcrum position to restrict the range of movement of the suspension assembly in the longitudinal and transverse directions, so that it can only undergo pitch changes in the vertical plane, while other angle changes are restricted, thus ensuring the stability of the installation position of the image deflectometer and the testing accuracy.

[0027] The support structure of this application is simple and easy to install. After installing the image deflectometer using this support, there is no need to use a reference target, which reduces the implementation cost of the bridge health monitoring system. At the same time, it eliminates the possibility of reverse error caused by the reference target. It has been verified that the measurement error generated by the deflection of the tilt-free support of this application is much smaller than the measurement error of conventional methods, which can provide more reliable support for the health assessment, safety monitoring and risk warning of continuous beam bridges. Attached Figure Description

[0028] Figure 1 is a schematic diagram of the installation of an image deflectometer tilt-free stabilizing bracket provided in an embodiment of this application;

[0029] Figure 2 is a structural diagram of a tilt-free stabilizing bracket for an image deflectometer provided in an embodiment of this application;

[0030] Figure 3 is a schematic diagram of the limiting groove of an image deflectometer without tilt angle stabilization bracket provided in an embodiment of this application;

[0031] Figure 4 is a schematic diagram of the image deflection of a conventional deflectometer.

[0032] Figure 5 is a schematic diagram of the deflection of an image deflectometer without tilt angle stabilization bracket provided in an embodiment of this application;

[0033] Explanation of reference numerals in the attached drawings: 1. Zero block; 2. Transverse diaphragm; 3. Image deflectometer; 4. Fulcrum; 5. Suspension assembly; 500. First suspension arm; 501. Second suspension arm; 6. Support assembly; 600. First mounting part; 601. Second mounting part; 7. First limiting groove; 8. Second limiting groove. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of this application clearer, the application will now be described in further detail with reference to the accompanying drawings.

[0035] It should be understood that the described embodiments are merely some, not all, of the embodiments in this application. All other embodiments obtained by those skilled in the art based on the embodiments in this application without inventive effort are within the scope of protection of this application.

[0036] The terminology used in the embodiments of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of this application. The singular forms “a,” “the,” and “the” used in the embodiments of this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0037] In the following description, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this application, unless otherwise stated, "a plurality of" means two or more.

[0038] Furthermore, in this application, directional terms such as "upper" and "lower" are defined relative to the orientation of the components shown in the accompanying drawings. It should be understood that these directional terms are relative concepts, used for relative description and clarification, and can change accordingly depending on the orientation of the components in the accompanying drawings.

[0039] It should be understood that the term "and / or" used in this document is merely a description of the same field in the related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, and B alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0040] Referring to Figures 1-3, a tilt-free stabilizing bracket for an image deflectometer includes:

[0041] Support component 6 is installed at the deflection monitoring point, preferably at the transverse partition 2 of zero block 1 or the top plate of the chamber near zero block 1;

[0042] The suspension assembly 5 is installed below the support assembly 6. At least one rotating connection is provided between the suspension assembly 5 and the support assembly 6. The suspension assembly 5 rotates relative to the support assembly 6 around the pivot point 4 on the rotating connection, so that when the support assembly produces a pitch angle under the action of vehicle load, the suspension assembly 5 rotates around the pivot point 4 under the action of gravity to adjust the deflection angle of the vertical plane.

[0043] Image deflectometer 3 is mounted on suspension assembly 5.

[0044] In one possible implementation, the support assembly 6 is mounted on the top plate of the compartment near block 1. The support assembly 6 includes a first mounting part 600, which is mounted on the top plate of the compartment near block 1 and extends longitudinally along the bridge (i.e., the direction in which block 1 extends into the building on both sides); the suspension assembly 5 is mounted below the first mounting part 600, and the suspension assembly 5 is rotatably connected to the first mounting part 600 around the fulcrum 4.

[0045] In another possible implementation, the support assembly 6 is mounted on the transverse diaphragm 2 of block 1. The support assembly 6 includes a first mounting part 600 and a second mounting part 601. The first mounting part 600 is mounted on the transverse diaphragm 2 of block 1. The rear end of the second mounting part 601 is fixedly connected to the first mounting part 600, and the other end extends longitudinally along the bridge. The suspension assembly 5 is mounted below the second mounting part 601 and forms a relative rotational connection with the second mounting part 601 around the fulcrum 4.

[0046] Furthermore, the suspension assembly 5 also includes a counterweight. When the support assembly 6 pitches under vehicle load, the counterweight drives the rotating connection to rotate counterclockwise or clockwise around the fulcrum 4 under the action of gravity, so that the suspension assembly 5 can be restored to balance.

[0047] In one possible implementation, the suspension assembly 5 is installed in a limiting groove. The limiting groove can limit the rotational connection while ensuring that its rotational space can accommodate the range of motion of the suspension assembly 5. Specifically, a first limiting groove 7 extending laterally along the bridge is formed at the connection between the support assembly 6 and the suspension assembly 5. The width of the first limiting groove 7 is greater than the diameter of the screw. The rotational connection includes several screws. After the screws pass through the suspension assembly 5, they limit the suspension assembly 5 within the first limiting groove 7. It should be noted that limiting refers to restricting the longitudinal and transverse movement of the suspension assembly 5. Since the width of the first limiting groove 7 is greater than the diameter of the screw, a reserved space is provided between the screw and the first limiting groove 7, allowing the screw to rotate within the first limiting groove 7.

[0048] Furthermore, the first limiting groove 7 is located at the end of the second mounting part 601, and the screw and the first suspension arm 500 are threaded together. After the screw passes through the first suspension arm 500, it is installed and limited in the first limiting groove 7, and the screw connection forms a fulcrum 4.

[0049] To further improve the stability of the suspension assembly 5 in the longitudinal and transverse directions, a second limiting groove 8 is opened at the bottom of the first limiting groove 7. The width of the first limiting groove 7 is at least twice the screw diameter, and the width of the second limiting groove 8 is smaller than the width of the first limiting groove but slightly larger than the screw diameter. After the screw passes through the suspension assembly 5, it limits the suspension assembly 5 within the second limiting groove 8. Adding two levels of limiting grooves deepens the vertical depth of the screw, better limiting the lower half of the screw and further restricting the displacement of the suspension assembly 5 in the longitudinal and transverse directions. Simultaneously, the first limiting groove 7 provides greater rotational space for the upper half of the screw. During initial installation, select an appropriate field of view height and direction, adjust the height of the first suspension arm 500 on the screw, and keep the image deflectometer 3 at a suitable height level to ensure that the camera's field of view covers the target. When the transverse diaphragm 2 of block 1 pitches under vehicle load, the combination of the first limiting groove 7 and the second limiting groove 8 can effectively limit the movement of the suspension assembly in the longitudinal and transverse directions. At the same time, the center of gravity of the suspension assembly 5 is always below the fulcrum 4, which can restore balance and ensure the stability of the height and orientation of the image deflectometer 3.

[0050] Preferably, the screw's tip angle is 35° to 40° to accommodate rotation within the limiting groove. More preferably, the first limiting groove 7 and / or the second limiting groove 8 are arc-shaped grooves. In this case, the depth of the groove varies at different positions, being deeper in the middle and shallower at both ends. When the screw slides laterally along both sides of the limiting groove, it moves upward with the arc-shaped groove opening, overcoming the gravity of the suspension assembly 5 and increasing energy consumption, thus stabilizing the screw as quickly as possible. The radius of curvature is not greater than the width of the support assembly.

[0051] In one possible implementation, there are multiple fulcrums 4, and the line connecting the multiple fulcrums 4 is parallel to the transverse direction of the bridge (or the plane of the diaphragm 2). Setting multiple fulcrums can better limit the changes of the suspension components in other angles or orientations, and further eliminate test errors.

[0052] In this embodiment, the support component 6 includes a first mounting part 600, which is vertically mounted on the transverse partition 2 of the zero block 1. A second mounting part 601 is provided at the upper end of the first mounting part 600. The two are arranged perpendicularly to form an L-shaped or T-shaped support. The second mounting part 601 extends longitudinally along the bridge. To improve the overall stability of the support component 6, it can also be an integrated bracket structure. Furthermore, reinforcing ribs can be provided between the first mounting part 600 and the second mounting part 601.

[0053] In this embodiment, the suspension assembly 5 is a C-shaped suspension component, including a first suspension arm 500. The shape of the first suspension arm 500 is adapted to the second mounting part 601. In this embodiment, both are flat structures. The first suspension arm 500 is horizontally mounted on the front end of the second mounting part 601, and the two are connected by a rotating connection part. The rotating connection part is a pair of screws. The front end of the second mounting part 601 has a two-stage limiting groove structure, wherein neither the first limiting groove 7 nor the second limiting groove 8 penetrates the second mounting part 601. After the pair of screws pass through the first suspension arm 500, they are confined within the second limiting groove 8, forming two fulcrums 4 at the connection. When the second mounting part 601 is thinner, the second limiting groove can also be opened through the second mounting part 601. In this case, the screws pass through the first suspension arm 500 and the second mounting part 601 in sequence, connecting the two together. The second suspension arm 501 is provided below the first suspension arm 500, and the two are connected. An image deflectometer 3 is provided on the second suspension arm 501. The suspension assembly 5 can be a fully enclosed or semi-enclosed frame structure, or a split or integrated frame structure. The first suspension arm 500 and the second suspension arm 501 can be connected flexibly or rigidly, which is not limited here.

[0054] In this application, the screw is a simple rotating connection part. Structures such as rotational damping can also achieve equivalent technical effects. The combination of the limiting groove and the screw enables the rotation of the suspension assembly 5. The depth, number, and shape of the limiting groove can be determined according to the thickness of the suspension assembly 5 and the shape of the rotating connection part, and are not limited here. For example, the width of the limiting groove can gradually increase from bottom to top. The limiting groove may not penetrate the suspension assembly 5, or it may penetrate it. Limiting holes or other structures can also be used instead of limiting grooves. The rotating connection part should restrict the movement of the suspension assembly 5 along the longitudinal and transverse directions of the bridge, allowing it to only undergo pitch changes in the vertical plane. Simultaneously, it should ensure that the center of gravity of the suspension assembly 5 is below the fulcrum. Therefore, when the bracket undergoes a pitch angle change, the suspension assembly 5 can automatically adjust its deflection angle due to gravity, restoring balance and ensuring the stability of the image deflectometer's installation position and orientation. Therefore, those skilled in the art can use one or more of these methods in combination to achieve the rotation of the suspension assembly 5. It should be noted that the weight of the counterweight in the suspension assembly 5 should be greater than the mechanical resistance of the rotating connection so that the suspension assembly can restore its balance within a preset time range.

[0055] A method for eliminating tilt error in an image deflectometer based on the aforementioned tilt-free stabilizing bracket includes the following:

[0056] The support assembly 6 is installed longitudinally along the bridge at the point to be monitored. The image deflectometer is installed on the suspension assembly 5. The height and direction of the image deflectometer are adjusted so that the camera's field of view covers the target. The suspension assembly 5 is rotatably connected to the support assembly 6 around the fulcrum 4. Preferably, the support assembly 6 is installed on the transverse diaphragm 2 of the zero block 1 or on the top plate of the box chamber near the zero block 1.

[0057] Under the vehicle load, block 1 produces a pitch angle change, causing support component 6 to deflect by an angle of θ; suspension component 5, due to gravity, produces a pitch rotation in the vertical plane around fulcrum 4 that is opposite to the pitch angle change of block 1. When suspension component 5 returns to balance, the entire bracket produces a vertical displacement x in the vertical plane.

[0058] Define the length of the support component 6 along the longitudinal direction of the bridge as h. According to the geometric relationship, the vertical displacement generated by the support in the vertical plane is x≈sinθ·h≈θ.

[0059] The following analysis uses comparative examples to explain the aforementioned errors. This embodiment does not consider measurement errors caused by lens distortion, non-perpendicularity between the camera optical axis and the CCD sensor (image deflectometer), or different sub-pixel interpolation algorithms.

[0060] Figure 4 illustrates the deflection of an image deflectometer under conventional conditions. Currently, in long-term displacement monitoring of continuous beam bridges, considering on-site construction and subsequent equipment maintenance, the image deflectometer is typically installed on the top plate of the box girder near the mid-span. Targets are placed on the top plates of the box girder at 1 / 4, mid-span, and 3 / 4 of the main span, while the reference target is placed on the top plate of the box girder near the mid-span on the opposite side. When the continuous beam bridge displaces under vehicle loads, it causes a certain degree of deflection and vertical deformation in both the image deflectometer and the reference target. Since the image deflectometer and reference target are installed near the mid-span, the vertical deformation is minimal. However, the tilt and elevation angles at the mid-span caused by vehicle loads significantly affect the image point deflection test, and this effect increases with the bridge span. In Figure 4, the image deflectometer exhibits a tilt angle of θ1, generating E... 11 Measurement errors. If the reference target is tilted downwards, it is difficult to correct the image deflectometer, and it may even introduce reverse errors.

[0061] In this embodiment, the image deflectometer is installed on the suspension assembly with no tilt bracket, and the support assembly is installed on the transverse diaphragm 2 of block 1. The image deflectometer captures images of the inside of the box girder.

[0062] Figure 5 shows a schematic diagram of the tilt-free bracket deflection in this embodiment. Both the first mounting part 600 and the second mounting part 601 are flat plate structures, perpendicular to each other to form an L-shaped support plate. The first mounting part 600 is vertically mounted on the transverse partition 2 of block 1. The rear end of the second mounting part 601 is fixedly connected to the first mounting part 600, and the other end extends longitudinally along the bridge.

[0063] Under the vehicle load, block 1 produces a pitch angle change, causing the support assembly 6 (L-shaped support plate) to deflect as a whole by an angle of θ2. Due to gravity, the suspension assembly 5 produces a pitch rotation in the vertical plane around the fulcrum 4 that is opposite to the pitch angle change of block 1. After restoring balance, the suspension assembly 5 only produces a vertical displacement x in the vertical plane.

[0064] Assuming the length of the second mounting part 601 is h, then the vertical displacement of the second mounting part 601 is sinθ2·h; x≈sinθ2·h.

[0065] The measurement errors E1 and E2 of the conventional installation method and the installation method of this application are obtained as shown in equations (1) and (2), respectively.

[0066] E1 = E 11 +E 12 (1)

[0067] E2 = E 21 +E 22 (2)

[0068] In equations (1) and (2), E 11 E represents the measurement error caused by fulcrum deflection in conventional installation methods. 11 =tanθ1·L;E 12 E represents the measurement error caused by vertical movement of the fulcrum in conventional installation methods. 21 E represents the measurement error caused by the deflection of the tilt-free support in this application. 21 =sinθ2·h;E 22 This indicates the measurement error caused by the vertical movement of the fulcrum in the tilt-free support of this application.

[0069] Due to E 22 =E 12 Therefore, E1 is simplified to E'1 = E 11 Simplify E2 to E'2 = E 21 By E 11 =tanθ1·L、 E 21 As can be seen from sinθ2·h, the measurement error caused by the deflection of the image deflectometer in the conventional installation method tends to increase with the increase of the deflection angle and the span L. Since the measurement error caused by the deflection of the angleless support is related to the length h of the second mounting part 601 and the deflection angle θ2, and h is fixed and much smaller than the span L, under the same vehicle load, the deflection angle θ1=θ2=θ. At the same time, the deflection angle of the middle support (the beam above the middle support of the continuous beam bridge is the zero block) is generally small under the vehicle load, which can be approximated as θ≈sinθ≈tanθ. Therefore, the measurement deviation E caused by the deflection of the angleless support is small.21 =sinθ2·h is much smaller than the error E caused by the deflection of the conventional image deflectometer. 11 =tanθ1·L, thus achieving the goal of error elimination.

[0070] The above embodiments are only for illustrating the technical concept and features of this application, and are intended to enable those skilled in the art to understand the content of this application and implement it accordingly. They should not be used to limit the scope of protection of this application. For those skilled in the art, several improvements and modifications can be made without departing from the principles of this application, and these improvements and modifications should also be considered within the scope of protection of this application.

Claims

1. A tilt-free stabilizing bracket for an image deflectometer, characterized in that, include: Support component (6) is installed at the deflection monitoring point; A suspension assembly (5) is installed below the support assembly (6). At least one rotating connection is provided between the suspension assembly (5) and the support assembly (6). The suspension assembly (5) rotates relative to the support assembly (6) around the pivot point (4) on the rotating connection. When the support assembly (6) pitches under the vehicle load, the suspension assembly (5) rotates around the pivot point (4) under the action of gravity to adjust the deflection angle of the vertical plane. The image deflectometer (3) is mounted on the suspension assembly (5).

2. The tilt-free stabilizing bracket for the image deflectometer according to claim 1, characterized in that, The support assembly (6) includes a first mounting part (600), which is mounted on the top plate of the box near the zero block (1) and extends longitudinally along the bridge; the suspension assembly (5) is mounted below the first mounting part (600) and forms a relative rotational connection with the first mounting part (600) around the fulcrum (4).

3. The tilt-free stabilizing bracket for the image deflectometer according to claim 1, characterized in that, The support assembly (6) includes a first mounting part (600) and a second mounting part (601). The first mounting part (600) is mounted on the transverse diaphragm (2) of the zero block (1). The second mounting part (601) extends longitudinally along the bridge, and one end of the second mounting part (601) is fixedly connected to the first mounting part (600). The suspension assembly (5) is mounted below the second mounting part (601), and the suspension assembly (5) forms a relative rotational connection with the second mounting part (601) around the fulcrum (4).

4. The tilt-free stabilizing bracket for the image deflectometer according to claim 1, characterized in that, A first limiting groove (7) extending laterally along the bridge is provided at the rotatable connection between the support assembly (6) and the suspension assembly (5). The width of the first limiting groove (7) is greater than the diameter of the screw. The rotatable connection includes a plurality of screws. After the screws pass through the suspension assembly (5), they limit the suspension assembly (5) within the first limiting groove (7).

5. The tilt-free stabilizing bracket for the image deflectometer according to claim 4, characterized in that, The first limiting groove (7) does not penetrate the support assembly (6). A second limiting groove (8) is opened at the bottom of the first limiting groove (7). The width of the second limiting groove (8) is smaller than the width of the first limiting groove (7), but larger than the diameter of the screw. After the screw passes through the suspension assembly (5), it limits the suspension assembly (5) to the second limiting groove (8).

6. The tilt-free stabilizing bracket for the image deflectometer according to claim 5, characterized in that, The first limiting groove (7) and / or the second limiting groove (8) are arc-shaped grooves.

7. The tilt-free stabilizing bracket for the image deflectometer according to claim 1, characterized in that, The suspension assembly (5) includes a counterweight. When the support assembly (6) pitches under vehicle load, the counterweight drives the rotating connection to rotate counterclockwise or clockwise around the fulcrum (4), so that the suspension assembly (5) can be restored to balance and the deflection angle of the vertical plane can be adjusted.

8. The tilt-free stabilizing bracket for the image deflectometer according to claim 1, characterized in that, The number of the fulcrums (4) is multiple, and the line connecting the multiple fulcrums (4) is parallel to the transverse direction of the bridge.

9. A method for eliminating tilt error of an image deflectometer based on a tilt-free stabilizing bracket as described in any one of claims 1-8, characterized in that, Includes the following: The support assembly (6) is installed longitudinally along the bridge at the monitoring point. The height of the suspension assembly (5) below the support assembly (6) and the direction of the image deflectometer are adjusted so that the camera's field of view covers the target. The suspension assembly (5) forms a relative rotational connection with the support assembly (6) around the fulcrum (4). Under the vehicle load, the zero block (1) produces a pitch angle change, causing the support component (6) to deflect by an angle of θ; the suspension component (5) produces a pitch rotation in the vertical plane around the fulcrum (4) due to gravity, which is opposite to the pitch angle change of the zero block (1). After the suspension component (5) returns to balance, the bracket produces a vertical displacement of x in the vertical plane. The length of the support component (6) along the longitudinal direction of the bridge is defined as h. According to the geometric relationship, the vertical displacement x≈sinθ·h≈θ generated by the support in the vertical plane.

10. The method for eliminating tilt angle error of an image deflectometer according to claim 9, characterized in that, The support assembly (6) is installed on the diaphragm (2) of the zero block (1) or on the top plate of the chamber near the zero block (1).

Images