Binocular stereo camera-based three-dimensional measurement splicing method for steel box girder under temperature change

Abstract

The invention discloses a binocular stereo camera-based three-dimensional measurement splicing method under temperature change of a steel box girder, and the method comprises the steps: S1, arranging a temperature sensor on the surface of a to-be-spliced steel box girder, binocular stereo cameras are installed outside the two sides of a splicing seam formed between the to-be-spliced steel box girder and the fixed steel box girder in the transverse bridge direction; s2, monitoring the temperature of the to-be-spliced steel box girder in real time by using the temperature sensor, and shooting images of the sections of the to-be-spliced steel box girder and the fixed steel box girder in real time by using the binocular stereo camera; and S3, temperature information collected by the temperature sensor and image information collected by the binocular stereo camera are processed through an integrated system, and the axial elongation and the beam end rotation angle of the to-be-spliced steel box girder are calculated so that the position of the to-be-spliced steel box girder can be adjusted. The device has the advantage that the position of the to-be-spliced steel box girder can be adjusted.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of steel box girder three-dimensional information recognition and splicing, and particularly relates to a three-dimensional measurement splicing method for steel box girder under temperature change based on a binocular stereo camera. BACKGROUND

[0002] Steel box girder has become a key load-bearing component in modern large bridges (such as long-span cable-stayed bridges, suspension bridges and arch bridges) and important building structures (such as stadiums and terminal buildings) due to its excellent mechanical properties, high industrialization degree and good economy. One of the core links of the on-site construction is the high-precision splicing between multiple steel box girders. The splicing quality directly affects the integrity, stress performance, linear smoothness and long-term service safety of the structure.

[0003] However, the steel box girder structure is inevitably exposed to the natural environment in actual construction and is subjected to significant diurnal and seasonal temperature changes. The inherent thermal expansion and contraction physical properties of steel make the steel box girder (especially in the length direction) produce complex deformation (mainly manifested as axial expansion and contraction and slight rotation of the beam end section) with temperature fluctuations. This dynamic structural deformation caused by temperature load brings severe challenges to the accurate positioning splicing that needs to be carried out under specific environmental conditions:

[0004] 1. Geometric deviation caused by deformation: the actual geometric shape of the target splicing section (including the spatial position and angle of its end face) will deviate from its design state or nominal size in real time with temperature changes. This dynamic geometric deviation, if not accurately perceived and compensated, will directly lead to:

[0005] a. Splicing misalignment: the interface of adjacent girder sections cannot be accurately matched, resulting in misalignment, gaps or forced assembly;

[0006] b. Stress concentration: forced assembly will introduce additional stress at the connection site (such as welds and bolt connections) that is not designed as expected;

[0007] c. Structural performance degradation: affecting the overall stiffness, stability, fatigue life of the structure, and even burying safety hazards;

[0008] d. Low construction efficiency: requiring repeated adjustment, repair or waiting for specific temperature windows, delaying the construction period.

[0009] 2. Limitations of existing solutions: in response to the influence of temperature deformation, the industry has tried or is using various methods, but all have obvious shortcomings:

[0010] a, empirical formula and manual measurement compensation: relying on historical experience data or simplified formula to estimate temperature deformation, supplemented by manual intermittent measurement positioning using total station, steel ruler, etc. This method has low precision, poor real-time performance, relies on operator experience, is difficult to capture complex deformation under transient temperature field, and is inefficient;

[0011] b, single temperature sensor combined with fixed model: a small number of temperature sensors (such as point or line) are installed on the beam body to monitor temperature changes, and the compensation amount is calculated based on a pre-set, fixed parameter linear or simple nonlinear thermal expansion model; this method assumes that the uniformity of the temperature field distribution is too idealized (actual steel box girder has uneven sunshine, temperature gradient caused by internal ventilation differences), the model is oversimplified (does not fully consider the influence of constraint conditions, material nonlinearity, geometric nonlinearity on the actual deformation mode), and cannot accurately reflect complex three-dimensional deformation (especially beam end rotation), the accuracy of the calculated compensation amount is limited;

[0012] c, static measurement and post-correction: static measurement positioning splicing is performed at a specific temperature (such as night or cloudy day); this method is subject to weather conditions, the construction window period is limited, and the construction progress is seriously affected, and it cannot cope with temperature fluctuations that may occur during construction;

[0013] d, lack of real-time closed-loop control: most existing technologies are limited to monitoring or open-loop compensation, and lack a closed-loop feedback control mechanism based on real-time deformation sensing to dynamically guide the action of the splicing equipment.

[0014] Therefore, how to accurately and dynamically perceive the actual three-dimensional deformation of the steel box girder (especially the axial extension and the beam end rotation) under complex and variable environmental temperature conditions, and calculate a high-precision spatial pose compensation amount accordingly, and then form an executable splicing control instruction, has become a key technical bottleneck that needs to be solved for realizing high-quality, high-efficiency and high-safety splicing of steel box girders. The existing technology cannot meet the increasing demand of large and complex projects for intelligent construction process, real-time precision control and active safety guarantee. SUMMARY

[0015] The purpose of the present application is to provide a three-dimensional measurement splicing method for steel box girders under temperature changes based on binocular stereo cameras, which sets temperature sensors on the surface of the steel box girder to be spliced, and installs binocular stereo cameras on the outside of the two sides of the transverse bridge of the splicing joint formed between the steel box girder to be spliced and the fixed steel box girder, and processes the temperature information collected by the temperature sensors and the image information collected by the binocular stereo cameras using an integrated system, thereby calculating the axial extension and the beam end rotation of the steel box girder to be spliced, and realizing the position adjustment of the steel box girder to be spliced.

[0016] The technical scheme of the present application is realized by the following technical scheme:

[0017] A three-dimensional measurement splicing method for steel box girder under temperature change based on a binocular stereo camera, the method comprising:

[0018] S1: arranging temperature sensors on the surface of the steel box girder to be spliced, and installing binocular stereo cameras outside the two sides of the transverse bridge direction of the splicing joint formed between the steel box girder to be spliced and the fixed steel box girder;

[0019] S2: using the temperature sensors to monitor the temperature of the steel box girder to be spliced in real time, and using the binocular stereo cameras to shoot images of the cross section of the steel box girder to be spliced and the fixed steel box girder in real time;

[0020] S3: processing the temperature information collected by the temperature sensors and the image information collected by the binocular stereo cameras by an integrated system, and calculating the axial elongation and beam end angle of the steel box girder to be spliced to adjust the position of the steel box girder to be spliced.

[0021] In step S1, the temperature sensors are arranged in multiple intervals along the height direction of the steel box girder to be spliced.

[0022] In step S3, the integrated system processes the image information collected by the binocular stereo cameras to generate three-dimensional point cloud data.

[0023] In step S3, the calculation formula of the axial elongation of the steel box girder to be spliced is as follows:

[0024] Delta L x = alpha * L x * Delta T avg ;

[0025] In the formula, Delta L x is the axial elongation of the steel box girder to be spliced; alpha is the linear expansion coefficient of the steel material of the steel box girder to be spliced; L x is the length of the steel box girder to be spliced; Delta T avg is the temperature change of the steel box girder to be spliced.

[0026] In step S3, the calculation formula of the beam end angle of the steel box girder to be spliced is as follows:

[0027]

[0028] In the formula, Delta theta y is the beam end angle of the steel box girder to be spliced; T(y) is the temperature distribution function along the cross section height y of the steel box girder to be spliced; h is the cross section height of the steel box girder to be spliced; alpha is the linear expansion coefficient of the steel material of the steel box girder to be spliced.

[0029] The advantages of the present application are:

[0030] 1. Each component is convenient to carry, and each component is easy to disassemble after measurement, so that it can be used multiple times;

[0031] 2. By combining the binocular stereo camera, the identification and splicing accuracy of the steel box girder three-dimensional data is significantly improved;

[0032] 3. It is suitable for the construction of various steel box girder structures of bridges, buildings and the like, and has strong practical application value. BRIEF DESCRIPTION OF DRAWINGS

[0033] Fig. 1 It is a schematic diagram of the installation of the temperature sensor and the binocular stereo camera of the present application;

[0034] Fig. 2 It is a schematic diagram of the temperature sensor of the present application;

[0035] Fig. 3 It is a schematic diagram of the binocular stereo camera of the present application;

[0036] As shown in Figs. 1-3 , the marks in the figure respectively represent:

[0037] The fixed steel box girder 1a, the steel box girder to be spliced 1b, the temperature sensor 2, the binocular stereo camera 3, the integrated system 4, and the data line 5. DETAILED DESCRIPTION

[0038] The features of the present application and other related features will be further described in detail below by combining the drawings through embodiments, so as to facilitate the understanding of the same industry technical personnel:

[0039] Embodiment: as shown in Figs. 1-3 , the present embodiment relates to a three-dimensional measurement splicing method for steel box girder temperature change based on binocular stereo camera, which mainly includes the following steps:

[0040] S1: arranging the temperature sensor 2 on the surface of the steel box girder to be spliced 1b, and installing the binocular stereo camera 3 outside the two sides of the transverse bridge direction of the splicing joint formed between the steel box girder to be spliced 1b and the fixed steel box girder 1a.

[0041] Among them, the binocular stereo camera 3 is used to shoot the steel box girder contour line in the splicing process, until the closure is completed.

[0042] The temperature sensor 2 is arranged in multiple along the height direction of the steel box girder to be spliced 1b, specifically, the steel box girder to be spliced 1b is arranged with multiple (at least two) temperature sensors 2 along the height direction (on the center axis of the side web plate) of the side web plate, and the temperature sensor 2 can also be arranged on the top plate and the bottom plate of the steel box girder to be spliced 1b.

[0043] S2: Real-time monitoring the temperature of the steel box girder 1b to be spliced by the temperature sensor 2, and real-time shooting the image of the cross section of the steel box girder 1b to be spliced and the fixed steel box girder 1a by the binocular stereo camera 3.

[0044] S3: Processing the temperature information collected by the temperature sensor 2 and the image information collected by the binocular stereo camera 3 by the integrated system 4, and calculating the axial elongation and the beam end angle of the steel box girder 1b to be spliced to adjust the position of the steel box girder 1b to be spliced.

[0045] Wherein, the temperature sensor 2 and the binocular stereo camera 3 are respectively electrically connected with the integrated system 4 through the data line 5. The integrated system 4 processes the image information collected by the binocular stereo camera 3 to generate three-dimensional point cloud data.

[0046] The calculation formula of the axial elongation of the steel box girder 1b to be spliced is as follows:

[0047] ΔL x =α×L x ×ΔT avg ;

[0048] In the formula, ΔL x is the axial elongation of the steel box girder to be spliced; α is the linear expansion coefficient of the steel material of the steel box girder to be spliced (the measured value of the linear expansion coefficient of Q345 steel is 1.2×10 -5 / ℃);L x is the length of the steel box girder to be spliced (unit: m);ΔT avg is the temperature change of the steel box girder to be spliced (unit: ℃)。

[0049] The calculation formula of the beam end angle of the steel box girder 1b to be spliced is as follows:

[0050]

[0051] In the formula, Δθ y is the beam end angle of the steel box girder to be spliced;T(y) is the temperature distribution function along the cross section height y of the steel box girder to be spliced (measured by the temperature sensor or linear temperature gradient);h is the cross section height of the steel box girder to be spliced (unit: m);α is the linear expansion coefficient of the steel material of the steel box girder to be spliced.

[0052] Through the above calculation method, the beam cross section point cloud data transmitted by the binocular stereo camera 3 is compensated and corrected, and the splicing adjustment instruction is output at the same time, so as to realize the high-precision splicing of the steel box girder. The integrated system 4 written by MATLAB processes the image information captured by the binocular stereo camera 3, can realize target data tracking, generate three-dimensional point cloud data, and import the temperature data of the temperature sensor 2 into the Matlab program, calculate the axial length compensation amount (axial elongation) and the beam end angle compensation amount (beam end angle), and real-time correct the point cloud data collected by the binocular stereo camera 3, while outputting the steel box girder splicing instruction, so as to realize the high-precision splicing of the steel box girder.

[0053] Specifically, when the binocular stereo camera 3 captures the end surface images of the fixed steel box girder 1a and the steel box girder 1b to be spliced, and detects that the top plate temperature of the steel box girder 1b to be spliced is 38℃ and the bottom plate temperature is 22℃, for the 30m long steel box girder 1b to be spliced, the integrated system 4 calculates the gradient temperature difference: ΔT grad = 16℃.

[0054] The thermal expansion displacement amount ΔL = 1.2 × 10 -5 × 30 × 16 = 5.76mm.

[0055] The cross section height h = 1.8m, the curvature κ = 1.2 × 10 -5 × 16 / 1.8 = 1.07 × 10 -4 rad / m;

[0056] The beam end angle θ = 1.07 × 10 -4 × 30 = 0.00321 rad, the integrated system 4 outputs the instruction to lift 6.2mm on the west side of the beam end of the steel box girder 1b to be spliced and to lower 6.2mm on the east side, and the flatness error of the splicing joint after compensation is ≤0.5mm.

[0057] The beneficial technical effects of the embodiment are:

[0058] 1. Each component is convenient to carry, and each component is easy to disassemble after measurement, so that it can be used multiple times;

[0059] 2. By combining the binocular stereo camera, the identification and splicing precision of the steel box girder three-dimensional data is significantly improved;

[0060] 3. It is suitable for the construction of various steel box girder structures such as bridges and buildings, and has strong practical application value.

[0061] Although the above embodiment has made a detailed description of the concept and embodiment of the purpose of the application with reference to the drawings, those skilled in the art can recognize that various improvements and changes can be made to the application without departing from the scope defined by the claims, and therefore are not described here.

Claims

1. A method for splicing three-dimensional measurement of steel box girder under temperature change based on binocular stereo camera, characterized by The method comprises: S1: arranging a temperature sensor on the surface of the steel box girder to be spliced, and installing a binocular stereo camera outside the two sides of the transverse bridge of the splicing joint formed between the steel box girder to be spliced and the fixed steel box girder; S2: monitoring the temperature of the steel box girder to be spliced in real time by using the temperature sensor, and shooting the image of the section of the steel box girder to be spliced and the fixed steel box girder in real time by using the binocular stereo camera; S3: processing the temperature information collected by the temperature sensor and the image information collected by the binocular stereo camera by an integrated system, and calculating the axial elongation and the beam end angle of the steel box girder to be spliced to adjust the position of the steel box girder to be spliced.

2. The three-dimensional measurement splicing method for steel box girder under temperature change based on binocular stereo camera according to claim 1, characterized in that In step S1, a plurality of temperature sensors are arranged along the height direction of the steel box girder to be spliced.

3. The three-dimensional measurement splicing method for steel box girder under temperature change based on binocular stereo camera according to claim 1, characterized in that In step S3, the integrated system processes the image information collected by the binocular stereo camera to generate three-dimensional point cloud data.

4. The three-dimensional measurement splicing method for steel box girder under temperature change based on binocular stereo camera according to claim 3, characterized in that In step S3, the calculation formula of the axial elongation of the steel box girder to be spliced is as follows: ΔL x = α x L x x ΔT avg ; In the formula, ΔL x is the axial elongation of the steel box girder to be spliced; α is the linear expansion coefficient of the steel material of the steel box girder to be spliced; L x is the length of the steel box girder to be spliced; ΔT avg is the temperature change of the steel box girder to be spliced.

5. The three-dimensional measurement splicing method for steel box girder under temperature change based on binocular stereo camera according to claim 4, characterized in that In step S3, the calculation formula of the beam end angle of the steel box girder to be spliced is as follows: In the formula, Δθ y is the beam end rotation angle of the steel box girder to be spliced; T(y) is a temperature distribution function along the cross-sectional height y of the steel box girder to be spliced; h is the cross-sectional height of the steel box girder to be spliced; and a is the linear expansion coefficient of the steel material of the steel box girder to be spliced.

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