High-precision measurement method and device for boundary dimension of precast concrete member

Abstract

The invention provides a high-precision measurement method and device for the boundary dimension of a precast concrete member, and belongs to the technical field of boundary dimension detection of precast concrete members. The device comprises a computer platform, a line laser array and a CCD camera, the line laser array comprises a first laser, a second laser and a third laser, and laser emitted by the first laser and the second laser is projected on the precast concrete member to form a first stripe and a second stripe which are parallel to the first direction; laser emitted by the third laser device is projected to the prefabricated concrete member to form third stripes; the CCD camera is used for shooting the precast concrete member to obtain a member image with combined laser stripes of the first stripe, the second stripe and the third stripe; the computer platform comprises an image processing system, and the image processing system is used for calculating the boundary dimension of the precast concrete member based on the machine vision technology. The device is simple in structure, easy to use and high in measurement precision and efficiency.

Description

Technical Field

[0001] The present application relates to the technical field of precast concrete component external dimension detection, and in particular to a high-precision measurement method and device for the external dimension of a precast concrete component. Background Art

[0002] Precast concrete components are components whose bottom surface is mainly made of reinforced concrete slabs, and whose upper surface and surrounding side walls are made of other hard materials. They are widely used in the construction industry. In actual production, specific requirements are put forward for the dimensions of precast concrete components, including the measurement of length, width, height (thickness) indicators. The allowable deviation of the dimensions is usually in the millimeter level. For example, the conventional length of precast concrete components is 12m, and the allowable deviation is ±5mm. Strict requirements are placed on the dimensions.

[0003] In production, the current measurement of the dimensions of precast concrete components mainly adopts traditional methods to check their dimensional parameters, such as manual measurement with steel tape measures, height gauges, angle gauges, etc. This kind of manual contact measurement has high labor intensity, long measurement time, low measurement accuracy and is prone to human errors, and is no longer suitable for the needs of modern automated measurement. On the other hand, with the rapid development of my country's construction industry, the dimensional accuracy of precast concrete components in the production process has an important impact on the quality of their finished products. This manual measurement method may even produce human errors, which in turn affects the quality of precast concrete components. It can be seen that manual measurement is not only time-consuming and labor-intensive, but also difficult to meet the needs of modern automated measurement.

[0004] Some existing technologies also introduce laser measurement into the size measurement of precast concrete components. By controlling the speed and time of the conveyor belt and combining it with laser ranging technology, the component size is automatically obtained. However, this measurement method relies on the coordinated movement of multiple groups of lasers to obtain the measurement results. This method makes the relationship between the various structures of the system more complicated, which easily leads to the accumulation of system errors, resulting in the final accuracy still failing to meet the requirements.

[0005] Therefore, it is necessary to provide an improved technical solution to address the above-mentioned deficiencies in the prior art. Summary of the invention

[0006] The purpose of the present application is to provide a high-precision measurement method and device for the external dimensions of precast concrete components, so as to solve or alleviate the problems existing in the above-mentioned prior art.

[0007] In order to achieve the above objectives, this application provides the following technical solutions:

[0008] In a first aspect, the present application provides a high-precision measuring device for the external dimensions of a precast concrete component, the measuring device comprising a computer platform, a line laser array, and a CCD camera;

[0009] The line laser array comprises a first laser, a second laser and a third laser, the lasers emitted by the first laser and the second laser are projected onto the precast concrete component to form first stripes and second stripes parallel to a first direction, the first stripes and the second stripes are parallel to each other and the actual interval between the first stripes and the second stripes is a calibration value; the lasers emitted by the third laser are projected onto the precast concrete component to form third stripes parallel to the second direction;

[0010] Wherein, the first direction is the X-axis direction of the image coordinate system, and the second direction is the Z-axis direction of the image coordinate system;

[0011] The CCD camera is used to photograph the precast concrete component to obtain a component image having the first stripes, the second stripes, and the third stripes combined with the laser stripes;

[0012] The computer platform comprises an image processing system, and the image processing system is used to calculate the external dimensions of the precast concrete component according to the calibration value and the component image based on machine vision technology.

[0013] In combination with the first aspect, in some possible implementations, the image processing system includes a preprocessing module, a centerline extraction module, a feature point extraction module, and a size calculation module;

[0014] The preprocessing module is used to filter the component image and perform binarization processing on the filtered component image using a maximum inter-class variance method;

[0015] The centerline extraction module is used to extract the centerline of the laser stripes in the component image after the binary processing by using the gray center method to obtain the centerline of the first stripe, the second stripe, and the third stripe; and calculate the actual physical size S corresponding to each pixel according to the centerline of the first stripe, the second stripe and the predetermined calibration value;

[0016] The feature point extraction module is used to identify the fracture feature image in the center line of the third stripe after the binarization process to determine the position of the upper surface of the precast concrete component and determine the pixel position of the upper surface position in the component image, which is recorded as P S8 ;

[0017] The size calculation module is used to calculate the size of each pixel according to the actual physical size S corresponding to each pixel and the pixel position P of the upper surface in the component image. S8, calculate the height difference between the second stripe and the upper surface of the precast concrete component, and then sum the height difference with the pre-calibrated actual height of the second stripe to obtain the actual size of the precast concrete component.

[0018] In combination with the first aspect, in some possible implementations, the feature point extraction module further includes a center pixel acquisition submodule and a pixel actual size calculation submodule;

[0019] The center pixel acquisition submodule is used to determine the center point pixel of the first stripe and the second stripe in the component image by using an image processing algorithm, which is denoted by P S6 and P S7 ;

[0020] The pixel actual size calculation submodule is used to calculate the pixel actual size of the first stripe according to the center point pixel P of the component image. S6 and the center point pixel P of the second stripe in the component image S7 , combined with the pre-calibrated actual height difference between the first stripe and the second stripe, the actual physical size S corresponding to each pixel is calculated.

[0021] In combination with the first aspect, in some possible implementations, the computer platform further includes a main control module, which is used to control the switching of the line laser array through an array I / O card, and control the CCD camera to shoot in normal working state or to shoot at a fixed time in standby state.

[0022] In conjunction with the first aspect, in some possible implementations, the computer platform further includes: a data storage / reading module;

[0023] The data storage / reading module is used to store the measured external dimension information of the precast concrete component and read the historical information.

[0024] In combination with the first aspect, in some possible implementations, the computer platform further includes: a printing module;

[0025] The printing module is used to display the measured dimensional information of the precast concrete component on the screen, generate a test report, and print the measurement results according to demand.

[0026] In combination with the first aspect, in some possible implementations, the first laser, the second laser, and the third laser are all single-word lasers.

[0027] In combination with the first aspect, in some possible implementations, the optical central axis of the CCD camera is coplanar with the central axes of the first laser, the second laser and the third laser, and the first stripes and the second stripes are parallel and form a certain angle with the optical central axis of the CCD camera.

[0028] In combination with the first aspect, in some possible implementations, the CCD camera adopts a wide-angle lens, and the pixel resolution of the CCD camera is 5um×5um.

[0029] In a second aspect, this embodiment provides a method for measuring the external dimensions of a precast concrete component using the measuring device described in any of the above embodiments, comprising:

[0030] The line laser array emits line lasers toward the precast concrete component to form first stripes, second stripes, and third stripes on the surface of the precast concrete component;

[0031] The first stripes and the second stripes are parallel to a first direction, and the first stripes and the second stripes are parallel to each other and the interval between them is a preset value; the laser emitted by the third laser is projected onto the precast concrete component to form a third stripe parallel to the second direction; the first direction is the length direction of the precast concrete component, and the second direction is the height direction of the precast concrete component;

[0032] Using the CCD camera to photograph the precast concrete component, obtaining a component image having the first stripes, the second stripes, and the third stripes combined with laser stripes;

[0033] The image processing system calculates the outer dimensions of the precast concrete component based on a machine vision technology according to a predetermined calibration value and the component image.

[0034] The technical solution of the embodiment of the present application has the following beneficial effects:

[0035] 1. The technical solution provided in this embodiment provides a high-precision measurement method through a pre-calibrated laser stripe spacing (the spacing between the first stripe and the second stripe is the calibration value). Because the stripe spacing is a known physical parameter, combined with the image information captured by the CCD camera, the actual size can be accurately calculated. This calibration-based method significantly improves the measurement accuracy and avoids the deviation caused by the accumulated equipment error or environmental factors in traditional measurement. In addition, the laser stripes projected by the line laser form clear boundaries and produce clearly identifiable image features on the surface of the precast concrete component, which can accurately locate the surface and edge position of the component and improve the measurement accuracy.

[0036] 2. The technical solution provided in this embodiment designs three lasers to form laser stripes parallel to the length direction (first direction) and height direction (second direction) of the precast concrete component respectively. By multi-directional projection of the laser stripes and capturing a combined image containing multiple laser stripes by a CCD camera, multiple key dimension information can be obtained in one image, thereby reducing measurement time and improving measurement efficiency. At the same time, by forming combined laser stripes on the surface of the precast concrete component, precast concrete components of different shapes and sizes can be measured, especially complex components with obvious edges or height differences. The laser stripes can accurately depict changes in the surface and edges of the workpiece, and are suitable for measuring irregular objects such as large building components or objects that are difficult to accurately measure using traditional methods.

[0037] 3. Relying on the image processing system in the computer platform, the machine vision technology is used to analyze and process the images taken by the CCD camera. By automatically identifying the laser stripes in the image and combining the calibration value, the dimensions of the precast concrete components can be automatically and quickly calculated, which not only improves the measurement efficiency, but also reduces the complexity and potential errors of manual operation. In addition, due to the introduction of image processing technology, the system can process the captured images and calculate the dimensions in real time, which is suitable for online measurement and quality monitoring on industrial assembly lines to ensure that the dimensions of the components meet the specification requirements.

[0038] In summary, the measuring device provided in the present application is not only simple in structure and easy to use, but also adopts a novel linear laser array structure design to achieve precise position marking reference. It forms high-precision automatic measurement based on machine vision technology, which solves the problem of relying on manual measurement in the actual production process. At the same time, it also avoids the accuracy deviation caused by the system's cumulative error to a certain extent, thereby improving the measurement accuracy and efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 This is a schematic structural diagram of a high-precision measurement device for the external dimensions of a precast concrete component provided according to some embodiments of the present application.

[0040] Figure 2 This is a schematic diagram of the principle of a high-precision measurement device for the external dimensions of a precast concrete component provided according to some embodiments of the present application.

[0041] Figure 3 Schematic diagram of the refraction characteristics of laser stripes at the edge of precast concrete components.

[0042] Figure 4 The schematic diagram of the working process of the high-precision measuring device for the external dimensions of precast concrete components is shown in FIG.

[0043] Explanation of the reference numerals: 1 - precast concrete component; 2 - CCD camera; 3 - first laser; 4 - second laser; 5 - third laser; 6 - first stripe; 7 - second stripe; 8 - third stripe; 9 - component image. DETAILED DESCRIPTION

[0044] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0045] In order to alleviate the problems existing in the prior art, the present application provides a high-precision measurement method and device for the outer dimensions of a precast concrete component 1, which adopts a novel linear laser array structure design to achieve accurate position marking reference, and uses a CCD industrial camera to obtain an image containing linear laser stripes. By preprocessing the image, the geometric center of the laser light stripes and the pixel position of the edge position feature point of the object to be measured are extracted, and the size converted from the image coordinate system to the physical coordinate system is calculated. Combined with the device system calibration value, the outer dimensions of the precast concrete component 1 are calculated.

[0046] The various embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0047] Embodiment 1:

[0048] The present application embodiment provides a high-precision measurement device for the external dimensions of a precast concrete component 1. Figure 1 It is a schematic structural diagram of a high-precision measuring device for the external dimensions of a precast concrete component 1 provided according to some embodiments of the present application. Figure 2 Schematic diagram of the principle of a high-precision measurement device for the external dimensions of a precast concrete component 1 provided according to some embodiments of the present application. Figure 1 , Figure 2 As shown, the measuring device includes a computer platform (industrial computer), a line laser array, and a CCD camera 2. The industrial computer is communicatively connected with the line laser array and the CCD camera 2 respectively.

[0049] The line laser array includes three lasers, namely a first laser 3, a second laser 4 and a third laser 5. The lasers emitted by the first laser 3 and the second laser 4 are projected onto the precast concrete component 1 to form first stripes 6 and second stripes 7 parallel to the first direction. The first stripes 6 and the second stripes 7 are parallel to each other and the actual interval therebetween is a calibrated value. The laser emitted by the third laser 5 is projected onto the precast concrete component 1 to form third stripes 8 parallel to the second direction.

[0050] The first direction is the X-axis direction of the image coordinate system, and the second direction is the Z-axis direction of the image coordinate system. In addition, the Y-axis is the optical axis direction of the CCD camera 2 .

[0051] The CCD camera 2 is used to photograph the precast concrete component 1 to obtain a component image 9 having laser stripes combined with the first stripes 6 , the second stripes 7 , and the third stripes 8 .

[0052] The computer platform comprises an image processing system, and the image processing system is used to calculate the external dimensions of the precast concrete component 1 according to the calibration value and the component image 9 based on machine vision technology.

[0053] The calibration value refers to the actual stripe height of the specified laser, so as to determine the correspondence between the actual physical size and the pixel coordinate. The calibration value is determined by the calibration module. Specifically, during assembly, the parallelism, verticality, spacing of the laser plane and the angle between the laser plane and the camera axis are corrected or calibrated to obtain the calibration value to ensure measurement accuracy.

[0054] It should be noted that, in this embodiment, the lasers emitted by the three lasers form laser stripes on the precast concrete component 1, wherein the laser stripes corresponding to the first laser 3 are the first stripes 6, the laser stripes corresponding to the second laser 4 are the second stripes 7, and the laser stripes corresponding to the third laser 5 are the third stripes 8. Moreover, the first stripes 6 are parallel to the second stripes 7 and parallel to the X axis, which reduces the measurement error caused by the angle deviation during shooting and makes the measurement more accurate. The third stripes 8 are parallel to the Z axis, which helps to calculate the size information in the Z axis direction in the subsequent calculation. Through the structured combination design of laser stripes, the recognition ability of the machine vision system is enhanced, and the realization of the automated detection process of the image processing system is promoted, thereby reducing the complexity of manual operation and improving the efficiency of measurement. At the same time, the multi-directionality of the laser combination makes the system more flexible when measuring different types of components, and the clear structure of the laser stripes makes it easier for the image processing algorithm to perform feature recognition and coordinate calculation, thereby improving the data processing efficiency and accuracy of the measurement system.

[0055] It can be understood that the measuring device also includes a power supply module for providing working power to the line laser array, the CCD camera 2 and the industrial computer.

[0056] In summary, the technical solution provided by this embodiment adopts a novel linear laser array structure design to achieve accurate position marking reference, and combines the device system calibration value, and uses an image processing algorithm to accurately calculate the external dimensions of the precast concrete component 1. This method is not affected by factors such as lens distortion, shooting scene, camera calibration, and does not require a complex lighting system. It has the advantages of simple measurement method and high measurement accuracy. The device has a high degree of automation and can automatically measure the external dimensions of the precast concrete component 1 without manual intervention during the measurement process; the measuring device is simple, and the measurement system can be quickly built to achieve high-precision measurement indicators; the measurement efficiency is high, and the external dimensions of the precast concrete component 1 can be measured within seconds, thereby greatly improving work efficiency, saving manpower and material resources, and improving production efficiency.

[0057] Preferably, the optical center axis of the CCD camera 2 is coplanar with the center axes of the first laser 3, the second laser 4 and the third laser 5, and the first stripe 6 and the second stripe 7 are parallel and form a certain angle with the optical center axis of the CCD camera 2. In this solution, the angle design between the laser stripe and the optical center axis of the camera can make the projection of the laser stripe on the surface more directional, which helps to improve the clarity of the laser stripe in the image, thereby improving the measurement accuracy, and the angle between the laser stripe and the optical center axis of the camera can create a more obvious contrast, enhance the visibility of the stripe in the image, and help the image processing algorithm to better extract features; by setting the stripes to be parallel and form a certain angle with the optical center axis of the camera, the overlap or blur of the laser stripes in the image can be avoided, which helps to clearly distinguish different stripes and improve the accuracy of data processing; by ensuring that the laser stripes are coplanar with the optical axis plane of the camera, the subsequent data processing process can be simplified, the required correction and compensation steps can be reduced, and the overall measurement efficiency can be improved. By optimizing the geometric relationship between CCD camera 2 and the laser, this solution improves the measurement accuracy, enhances the image quality, improves the system adaptability, and simplifies the data processing process in the measurement of concrete component dimensions, thereby achieving more efficient and accurate measurement results.

[0058] Exemplarily, the angle between the optical central axis of the CCD camera 2 and the first laser 3 and the second laser 4 can be set to a small angle of 5° to 15°, which can reduce the diffusion of the laser stripes on the measured surface and ensure that the stripes are more concentrated in the image to meet the high-precision requirements. In another example, if the geometry of the concrete component is more complex, the angle can be set to 15° to 30° to ensure that the stripes can better cover different surfaces while maintaining a certain resolution. Preferably, when measuring tall precast concrete components 1, the angle can be set to about 20°, which is small enough to ensure that the laser stripes remain clear, and large enough to facilitate the visibility of the stripes on complex surfaces. Then, through the image processing algorithm, clear edge features can be extracted on this basis for dimensional measurement.

[0059] Preferably, the first laser 3, the second laser 4 and the third laser 5 are all straight lasers. Since the straight laser can generate clear laser lines, it is helpful to accurately locate and measure the edge and surface features of the component, thereby improving the accuracy of measurement, and the straight laser is relatively economical and convenient to integrate with the CCD camera 2 or other image processing systems to form a complete automatic measurement system, thereby simplifying the operation process.

[0060] Preferably, the CCD camera 2 adopts a wide-angle lens, and the pixel resolution of the CCD camera 2 is 5um×5um. The CCD camera 2 using a wide-angle lens, with a pixel resolution of 5μm, has the following advantages for measuring the size of concrete components: first, the wide-angle lens can capture a wider range of scenes, reducing the need for camera movement or multiple shots, and the user does not need to frequently adjust the camera position, simplifying the operation process and improving the measurement efficiency. In addition, since it can capture a wider field of view, the wide-angle lens enables the camera to work effectively in different environments and conditions and adapt to complex measurement scenes; secondly, the pixel resolution of 5μm can provide high-detail images, ensuring that even tiny features and defects on the concrete surface can be clearly captured, which helps to more accurately locate feature points such as stripes and edges, thereby improving the accuracy of size measurement. In other words, combined with a wide-angle lens and high pixel resolution, the CCD camera 2 can significantly improve the efficiency and accuracy of measurement when measuring the size of concrete components, adapt to complex measurement requirements, reduce the complexity of operation, and thus improve the overall workflow.

[0061] Using image processing algorithms to efficiently and accurately extract the center position of the laser line from the captured image is the premise and basis for measuring the external dimensions of the precast concrete component 1. To this end, in some examples, the image processing system includes a preprocessing module, a centerline extraction module, a feature point extraction module, and a dimension calculation module.

[0062] When the laser is projected onto the surface of the precast concrete component 1, bright light will be generated due to impurities on the surface of the object to be measured, which will interfere with the extraction of feature points. The preprocessing module is used for image preprocessing, the main purpose of which is to reduce the image background noise and improve the recognition and extraction accuracy of the center line and edge feature points of the laser stripes.

[0063] Specifically, the preprocessing module is used to filter the component image 9 and use the maximum inter-class variance method (Otsu) to binarize the filtered component image 9 to separate the laser stripe target from the background to eliminate the influence of noise.

[0064] The center line extraction module is used to extract the center lines of the laser stripes in the component image 9 after binarization using the grayscale center method, that is, the grayscale value centroid of each row of laser stripe cross-section is used as the center line of the laser stripe to obtain the center lines of the first stripes 6, the second stripes 7, and the third stripes 8.

[0065] The feature point extraction module is used to identify the fracture feature image in the center line of the third stripe 8 after the binarization process to determine the position of the upper surface of the precast concrete component 1, and determine the pixel position of the upper surface position in the component image 9, which is recorded as P S8 .

[0066] In this embodiment, the preprocessing module, the centerline extraction module and the feature point extraction module are collectively referred to as the image processing module. Among them, the centerline extraction module and the feature point extraction module are mainly used for laser stripe centerline extraction and component edge feature point positioning. Specifically, the feature point refers to the pixel position of the upper surface edge of the precast concrete component 1 in the component image 9, also known as the edge feature point of the object to be measured. The positioning method is to first use the above-mentioned centerline extraction module to obtain the center line of the laser stripe parallel to the Z axis, that is, the center line of the third stripe 8, and then detect a jump in the center line of the laser stripe through the image detection algorithm. The jump position is regarded as the edge position of the upper surface of the object to be measured, that is, the feature point.

[0067] The size calculation module (outer dimension calculation module) is used to calculate the actual physical size S corresponding to each pixel and the pixel position P of the upper surface in the component image 9. S8 , calculate the height difference between the second stripe 7 and the upper surface of the precast concrete component 1, and then sum the height difference with the pre-calibrated actual height of the second stripe 7 to obtain the actual size of the precast concrete component 1.

[0068] By calculating the height difference between the second stripe 7 and the upper surface of the component, the actual shape and size change of the concrete component can be effectively reflected, especially when dealing with components with steps or complex surfaces, the flexibility and adaptability of measurement are improved.

[0069] Furthermore, the feature point extraction module further includes a center pixel acquisition submodule and a pixel actual size calculation submodule.

[0070] The center pixel acquisition submodule is used to determine the center point pixel of the first stripe 6 and the second stripe 7 in the component image 9 by using an image processing algorithm, which is denoted by P S6 and P S7 ;

[0071] The pixel actual size calculation submodule is used to calculate the pixel actual size of the first stripe 6 according to the center point pixel P in the component image 9. S6 and the center pixel P of the second stripe 7 in the component image 9 S7 , combined with the pre-calibrated actual height difference between the first stripes 6 and the second stripes 7, the actual physical size S corresponding to each pixel is calculated.

[0072] By using the actual physical size S corresponding to each pixel for calculation, the pixel information in the image is converted into physical size, reducing the calculation error.

[0073] Refer to the following Figure 2 , Figure 3 The above scheme is described.

[0074] like Figure 2 As shown in FIG. 1 , when the laser emitted by the laser irradiates the surface of the precast concrete component 1, the CCD camera 2 can capture the image of the projection line of the combined laser on the precast concrete component 1. Based on the step effect, when the laser projection line is projected onto the surface of the precast concrete component 1 with a step extension, the third stripe 8 will bend at the edge of the step, forming a Figure 3 The characteristic image shown. Therefore, during the image acquisition process of the CCD camera 2, the precast concrete component 1 will form a broken laser stripe curve at the edge position under the laser projection, and the broken position is the upper edge position of the precast concrete component 1. The upper surface position of the precast concrete component 1 can be accurately located through this characteristic position. The actual height of the first stripe 6 and the second stripe 7 needs to be calibrated in advance, which is recorded as H S6 and H S7 , then the spacing between the first stripe 6 and the second stripe 7 is D = HS7-HS6. Using the image processing algorithm, the position of the center pixel of the first stripe 6 and the second stripe 7 can be obtained, denoted as P S6 and P S7, the unit is pixel, then the actual physical size S corresponding to each pixel can be obtained: S = D / (P S7 -P S6 ), the unit is um / pixel. Further, the refraction position of the third stripe 8 in the component image 9 is calculated, which is recorded as P S8 , in pixels. Then, the actual dimensions of the actual precast concrete structure are:

[0075] L = H S7 + P S8 × S = H S7 + P S8 × (H S7 -H S6 ) / (P S7 -P S6 ) (1)

[0076] In the formula, H S6 , H S7 are the actual heights of the first stripe 6 and the second stripe 7, respectively, obtained by actual height calibration, P S6 , P S7 and P S8 are the upper surface pixel positions determined by the center pixels of the first stripe 6, the second stripe 7, and the third stripe 8 in the component image 9, respectively. S6 , P S7 and P S8 The specific pixel position is obtained by using image processing algorithms.

[0077] In some embodiments, the computer platform further includes a main control module, which is used to control the switching of the line laser array through an array I / O card, and control the CCD camera 2 to shoot in normal working state or to shoot at a fixed time in standby state.

[0078] Among them, the array I / O card is a hardware interface card specifically used to control input / output devices (such as cameras, sensors, etc.). It can control multiple devices and allow the system to issue instructions based on external signals or preset conditions to adjust the working status of the device.

[0079] The main controller controls the status of CCD camera 2 and line laser array through the array I / O card to ensure that they shoot normally when needed and take timed photos at set time intervals in standby mode. This design effectively manages the workload of CCD camera 2 and line laser array, ensuring that the system can run efficiently in different working states, which not only guarantees the acquisition of required images but also saves resources.

[0080] In some embodiments, the computer platform further includes: a data storage / reading module.

[0081] The data storage / reading module is used to store the measured dimensional information of the precast concrete component 1 and read the historical information. Such a setting can effectively manage and store the measured dimensional information, so that the data can be quickly retrieved when needed, which is convenient for subsequent analysis and comparison, and is conducive to historical data tracking, quality control, and the generation of measurement reports.

[0082] In some embodiments, the computer platform further includes: a printing module.

[0083] The printing module is used to display the measured dimensions of the precast concrete component 1 on the screen, generate a test report, and print the measurement results as required. By displaying the measurement results on the screen, the user can intuitively view the dimensions of the concrete component, which is easy to understand and analyze; by providing intuitive measurement result display and automated report generation, the efficiency and accuracy of information transmission are enhanced, which helps to improve quality control, customer communication and decision support, and enhance the practicality and reliability of the overall measurement system.

[0084] Reference Figure 4 The working process of the measuring device provided in this embodiment is as follows:

[0085] The precast concrete component 1 to be measured is placed at the designated position in front of the measuring device, and the measuring device is started (i.e., the main program and the power module are started). The laser line light source array emits laser light to illuminate the surface to be measured to form a bright thin straight line. The CCD camera 2 is used to take a picture of the object to be measured, and image acquisition is started. The collected image is processed using machine vision technology to segment the center position of the laser stripe of interest. The shape dimension calculation module has been calibrated in advance based on the straight line laser height and spacing of the laser line light source, so as to use the laser stripe positioning to determine and calculate the size of the object to be measured. Further, by analogy, the length, width and height measurement of the shape dimensions of the precast concrete component 1 can be realized. The laser line light source has completed the horizontal or vertical correction during use to ensure the system error.

[0086] As an example, the high-precision measuring device for the external dimensions of the precast concrete component 1 provided in this embodiment may include two parts: a hardware control system and an image processing system. The hardware control system is based on a computer platform, on which a main control module and an image processing system are installed. The main control module uses a digital I / O card to switch the laser array on and off and controls the CCD camera 2 to collect images. The image processing system processes the collected images and then measures the dimensions. The external dimension measurement system for the precast concrete component 1 based on machine vision adopts a modular design, and the key functional points are realized by independent modules, and the overall measurement function is completed by calling each module to each other.

[0087] Since the physical size of the pixels of the CCD camera 2 is in the micrometer range, the actual size tolerance is usually in the millimeter range, so the internal parameters of the CCD camera 2 and the lens distortion parameters have negligible effects on the measurement accuracy, so there is no need to calibrate the internal parameters of the CCD camera 2 and the lens distortion parameters.

[0088] The high-precision measuring device for the external dimensions of the precast concrete component 1 provided in this embodiment is realized by using laser stripes with uniform light as a marking reference. The laser stripes are bright and extremely fine, and the surrounding light source has little effect on the measurement result, and the measurement result has excellent stability. The measuring device is realized by host control and software programming. It has the following advantages: the measuring device is easy to install; it realizes the full automation of the measurement process, and the measurement process does not require manual intervention, which greatly saves manpower and material resources; the measurement speed is fast, and the external dimensions of the precast concrete component 1 can be measured within a time range of seconds, which greatly improves the measurement efficiency.

[0089] Embodiment 2:

[0090] This embodiment provides a method for measuring the external dimensions of a precast concrete component 1 using the measuring device provided in any of the above embodiments, comprising:

[0091] The line laser array emits line lasers toward the precast concrete component 1 to form first stripes 6, second stripes 7, and third stripes 8 on the surface of the precast concrete component 1;

[0092] The first stripes 6 and the second stripes 7 are parallel to the first direction, and the first stripes 6 and the second stripes 7 are parallel to each other and the interval between them is a preset value; the laser emitted by the third laser 5 is projected onto the precast concrete component 1 to form a third stripe 8 parallel to the second direction; the first direction is the length direction of the precast concrete component 1, and the second direction is the height direction of the precast concrete component 1;

[0093] The precast concrete component 1 is photographed using the CCD camera 2 to obtain a component image 9 having laser stripes combined with the first stripes 6, the second stripes 7, and the third stripes 8;

[0094] The image processing system calculates the external dimensions of the precast concrete component 1 based on a predetermined calibration value and the component image 9 based on machine vision technology.

[0095] Furthermore, the image processing system calculates the external dimensions of the precast concrete component 1 based on the machine vision technology according to the predetermined calibration value and the component image 9, specifically:

[0096] Performing filtering processing on the component image 9, and performing binarization processing on the filtered component image 9 using the maximum inter-class variance method;

[0097] Using the grayscale center method to extract the center line of the laser stripes in the component image 9 after the binary processing, to obtain the center line of each stripe;

[0098] Identify the fracture feature image in the center line of the third stripe 8 after the binarization process to determine the position of the upper surface of the precast concrete component 1, and determine the pixel position of the upper surface position in the component image 9, which is recorded as P S8 ;

[0099] According to the center lines of the first stripes 6 and the second stripes 7 and the predetermined calibration value, the actual physical size S corresponding to each pixel is calculated, and according to the actual physical size S corresponding to each pixel and the pixel position P of the upper surface in the component image 9 S8 , calculate the height difference between the second stripe 7 and the upper surface of the precast concrete component 1, and then sum the height difference with the pre-calibrated actual height of the second stripe 7 to obtain the actual size of the precast concrete component 1.

[0100] The method for measuring the external dimensions of precast concrete components provided in this embodiment is implemented using the measuring device provided in any of the above embodiments. This method greatly improves the two major problems of low efficiency and low measurement accuracy of manual measurement, realizes full automation of the measurement process, saves manpower and material resources, improves measurement efficiency, and the measurement system is easy to operate.

[0101] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A high-precision measuring device for the external dimensions of precast concrete components, characterized in that: The measuring device includes a computer platform, a line laser array, and a CCD camera; The line laser array comprises a first laser, a second laser and a third laser, the lasers emitted by the first laser and the second laser are projected onto the precast concrete component to form first stripes and second stripes parallel to a first direction, the first stripes and the second stripes are parallel to each other and the actual interval between the first stripes and the second stripes is a calibration value; the lasers emitted by the third laser are projected onto the precast concrete component to form third stripes parallel to the second direction; Wherein, the first direction is the X-axis direction of the image coordinate system, and the second direction is the Z-axis direction of the image coordinate system; The CCD camera is used to photograph the precast concrete component to obtain a component image having the first stripes, the second stripes, and the third stripes combined with the laser stripes; The computer platform comprises an image processing system, and the image processing system is used to calculate the external dimensions of the precast concrete component according to the calibration value and the component image based on machine vision technology.

2. The measuring device according to claim 1, characterized in that The image processing system includes a preprocessing module, a centerline extraction module, a feature point extraction module, and a size calculation module; The preprocessing module is used to filter the component image and perform binarization processing on the filtered component image using a maximum inter-class variance method; The center line extraction module is used to extract the center lines of the laser stripes in the component image after the binarization process by using the gray center method to obtain the center lines of the first stripes, the second stripes, and the third stripes; and calculating the actual physical size S corresponding to each pixel according to the center lines of the first stripes, the second stripes and the predetermined calibration value; The feature point extraction module is used to identify the fracture feature image in the center line of the third stripe after the binarization process to determine the position of the upper surface of the precast concrete component and determine the pixel position of the upper surface position in the component image, which is recorded as P S8 ; The size calculation module is used to calculate the size of each pixel according to the actual physical size S corresponding to each pixel and the pixel position P of the upper surface in the component image. S8 , calculate the height difference between the second stripe and the upper surface of the precast concrete component, and then sum the height difference with the pre-calibrated actual height of the second stripe to obtain the actual size of the precast concrete component.

3. The measuring device according to claim 2, characterized in that The feature point extraction module further includes a central pixel acquisition submodule and a pixel actual size calculation submodule; The center pixel acquisition submodule is used to determine the center point pixel of the first stripe and the second stripe in the component image by using an image processing algorithm, which is denoted by P S6 and P S7 ; The pixel actual size calculation submodule is used to calculate the pixel actual size of the first stripe according to the center point pixel P of the component image. S6 and the center point pixel P of the second stripe in the component image S7 , combined with the pre-calibrated actual height difference between the first stripe and the second stripe, the actual physical size S corresponding to each pixel is calculated.

4. The measuring device according to claim 1, characterized in that The computer platform also includes a main control module, which is used to control the switch of the line laser array through an array I / O card, and control the CCD camera to shoot in a normal working state or to shoot at a fixed time in a standby state.

5. The measuring device according to claim 1, characterized in that The computer platform also includes: a data storage / reading module; The data storage / reading module is used to store the measured external dimension information of the precast concrete component and read the historical information.

6. The measuring device according to claim 1, characterized in that The computer platform further comprises: a printing module; The printing module is used to display the measured dimensional information of the precast concrete component on the screen, generate a test report, and print the measurement results according to demand.

7. The measuring device according to claim 1, characterized in that The first laser, the second laser and the third laser are all single-word lasers.

8. The measuring device according to claim 1, characterized in that The optical center axis of the CCD camera is coplanar with the center axes of the first laser, the second laser and the third laser, and the first stripes and the second stripes are parallel and form a certain angle with the optical center axis of the CCD camera.

9. The measuring device according to claim 1, characterized in that The CCD camera adopts a wide-angle lens, and the pixel resolution of the CCD camera is 5um×5um.

10. A method for measuring the external dimensions of a precast concrete component using the measuring device according to any one of claims 1 to 9, characterized in that: include: The line laser array emits line lasers toward the precast concrete component to form first stripes, second stripes, and third stripes on the surface of the precast concrete component; The first stripes and the second stripes are parallel to a first direction, and the first stripes and the second stripes are parallel to each other and the interval between them is a preset value; the laser emitted by the third laser is projected onto the precast concrete component to form a third stripe parallel to the second direction; the first direction is the length direction of the precast concrete component, and the second direction is the height direction of the precast concrete component; Using the CCD camera to photograph the precast concrete component, obtaining a component image having the first stripes, the second stripes, and the third stripes combined with laser stripes; The image processing system calculates the external dimensions of the precast concrete component based on a machine vision technology according to a predetermined calibration value and the component image.

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