Standard concrete test piece and calibration method of concrete test piece size non-contact measurement system

Abstract

The invention discloses a standard concrete test piece and a calibration method of a concrete test piece size non-contact measurement system using the standard concrete test piece, the standard concrete test piece comprises a test piece body, the test piece body is a rectangular block body, the test piece body is provided with a size detection module, an angle detection module and a flatness detection module, and the size detection module is connected with the angle detection module. The size detection module has three different size standard values set for the lengths of the test piece body on three orthogonal dimensions, and the flatness detection module has three different flatness standard values set for steps of the test piece body on three orthogonal dimension planes. The angle detection module has three different angle standard values for setting included angles which are formed by three groups of adjacent surfaces of the test piece body and are positioned on three orthogonal dimension planes. According to the invention, the number of standard components is reduced, the storage and transportation cost is reduced, the measurement error caused by the difference between test pieces is effectively weakened, the accuracy and repeatability of the measurement result are improved, and the detection efficiency is improved.

Description

Technical Field

[0001] The present invention relates to a standard concrete specimen and also to a calibration method of a non-contact measurement system for concrete specimen dimensions using the standard concrete specimen. Background Art

[0002] Concrete is one of the primary and most important materials used in buildings, playing a key role in the quality and safety of construction projects. Concrete compressive strength testing is one of the most typical and fundamental testing items in construction projects.

[0003] The traditional method of measuring the size of concrete specimens is to use measuring instruments such as vernier calipers, feeler gauges, and vernier protractors through manual measurement. This method has shortcomings such as slow measurement speed, many human interference factors, and large measurement uncertainty.

[0004] In recent years, with the continuous advancement of modern testing technology and the need for digital and intelligent transformation, non-contact measurement methods have been gradually applied to the field of construction engineering material testing. Among them, the most common application is the non-contact measurement system for concrete specimen dimensions used for intelligent concrete compressive strength testing. This system has replaced traditional manual measurement methods and has been widely used in engineering testing institutions in my country. It is developing rapidly and is gradually replacing traditional testing equipment.

[0005] Non-contact measurement technology eliminates the need for direct contact with the object being measured. Instead, it uses physical methods such as lasers, infrared, and ultrasound to perform measurements at a distance or even inaccessible locations. This effectively avoids the errors and damage that can be introduced by traditional contact measurement, greatly improving the convenience and safety of measurement. However, maintaining and improving its accuracy is a complex and critical issue. This is because changes in various physical factors and environmental conditions involved in the measurement process, such as light source stability, sensor sensitivity, surface characteristics of the object being measured, and ambient temperature and humidity, can significantly affect the measurement results, leading to fluctuations in measurement accuracy.

[0006] Currently, non-contact measurement systems for concrete specimen dimensions lack metrological traceability methods, specifically calibration techniques. This results in an inability to guarantee the accuracy of measurement results, standardize the uniformity of the concrete specimen dimension measurement process, and ensure the consistency and accuracy of value transfer and traceability, hindering the widespread application of intelligent building material testing equipment. Therefore, establishing and implementing a regular, scientific calibration mechanism is crucial to ensuring the accuracy and reliability of non-contact measurement systems and promoting their widespread application. Summary of the Invention

[0007] The first object of the present invention is to provide a standard concrete specimen that can reduce the number of standard parts, improve the accuracy and repeatability of measurement results, increase detection efficiency, and reduce storage and transportation costs.

[0008] The first object of the present invention is achieved through the following technical measures: a standard concrete specimen, including a specimen body, which is a rectangular block, characterized in that a size detection module, an angle detection module and a flatness detection module are arranged on the specimen body, the size detection module has three different size standard values ​​set for the length of the specimen body in three orthogonal dimensions, the flatness detection module has three different flatness standard values ​​set for the steps of the specimen body on the three orthogonal dimensions, and the angle detection module has three different angle standard values ​​set for the angles formed by three groups of adjacent surfaces of the specimen body on the three orthogonal dimensions, so that during detection, the measurement system can simultaneously measure and calibrate the three different size standard values ​​of the size detection module, the three different angle standard values ​​of the angle detection module and the three different flatness standard values ​​of the flatness detection module in each posture of the standard concrete specimen.

[0009] This integrated standard concrete specimen combines three functional modules for dimension, angle, and flatness testing. This multi-parameter integration reduces the number of standard components, lowering storage and transportation costs, effectively minimizing measurement errors caused by inter-specimen variations, and improving the accuracy and repeatability of measurement results. During measurement, the measurement system simultaneously calibrates key parameters such as dimension, angle, and flatness, improving inspection efficiency.

[0010] As an embodiment of the present invention, notch-shaped grooves are respectively provided at the corners of the planes of the three orthogonal dimensions of the specimen body, and the three angles formed by the groove walls of the three grooves and the planes where the corresponding grooves are located constitute an angle detection module. Three steps are respectively provided on the groove bottom surfaces of the three grooves to constitute a flatness detection module, and the corners formed by the planes of the three orthogonal dimensions where the grooves are set have three adjacent orthogonal edges to constitute a size detection module.

[0011] As another embodiment of the present invention, notch-shaped grooves are respectively provided at the corners of the planes of the three orthogonal dimensions of the specimen body, and the three angles formed by the groove walls of the three grooves and the planes where the corresponding grooves are located constitute an angle detection module. Three steps are respectively provided on the planes of the three orthogonal dimensions where the grooves are set to constitute a flatness detection module, and the corner formed by the planes of the three orthogonal dimensions where the grooves are set has three adjacent orthogonal edges that constitute a size detection module.

[0012] The specifications of the different size detection modules of the present invention are 99mm×100mm×101mm, 149mm×150mm×151mm and 299mm×300mm×301mm, among which the size detection module with a specification of 99mm×100mm×101mm is used for measuring the target size of 100mm×100mm×100mm, the size detection module with a specification of 149mm×150mm×151mm is used for measuring the target size of 150mm×150mm×150mm, and the size detection modules with specifications of 149mm×150mm×151mm and 299mm×300mm×301mm are combined for measuring the target size of 150mm×150mm×300mm.

[0013] The maximum permissible error of the standard size value of the present invention is within ±0.05mm.

[0014] The standard angle values ​​of the angle detection module of the present invention are: 89.5°, 90°, and 90.5°.

[0015] The error of the angle standard value of the present invention is within ±0.02°.

[0016] According to the present invention, for a standard concrete specimen of 100mm×100mm×100mm, the three standard flatness values ​​of the flatness detection module are: 0.02mm, 0.05mm and 0.08mm; for a standard concrete specimen of 150mm×150mm×150mm, the three standard flatness values ​​of the flatness detection module are: 0.05mm, 0.10mm and 0.15mm; for a standard concrete specimen of 300mm×300mm×300mm, the three standard flatness values ​​of the flatness detection module are: 0.10mm, 0.15mm and 0.20mm.

[0017] The maximum allowable error of the flatness standard value of the present invention is within ±0.005mm.

[0018] A second object of the present invention is to provide a calibration method for a non-contact measurement system for concrete specimen dimensions using the above-mentioned concrete specimen, which can achieve accurate calibration to ensure the accuracy of the measurement results.

[0019] The second object of the present invention is achieved by the following technical measures: a method for calibrating a non-contact measurement system for concrete specimen dimensions using the above-mentioned concrete specimen, characterized by comprising the following steps:

[0020] S1. Place the standard concrete specimen on the base of the concrete specimen size non-contact measurement system;

[0021] S2. Start the measurement system, and perform multiple repetitive measurements on the calibration points on each module of the standard concrete specimen in the initial position to obtain measurement data for each calibration point. The measurement data of each calibration point are averaged and the indication error is calculated to obtain the measurement results of each calibration point. The calibration points refer to the corresponding standard value measurement points in the size detection module, angle detection module, and flatness detection module of the standard concrete specimen.

[0022] S3. Use a controller to automatically rotate the standard concrete specimen 90 degrees along the X-axis, Y-axis, and Z-axis, and perform multiple repetitive measurements on the calibration points on each module of the standard concrete specimen in this position each time. Measured data for each calibration point is obtained, and the measured data for each calibration point is averaged and the indication error is calculated to obtain the measurement results for each calibration point.

[0023] S4. Analyze the measurement results obtained in steps S2 and S3, that is, analyze the dimensional measurement uncertainty, angle measurement uncertainty, and flatness measurement uncertainty respectively, and finally perform a combined measurement system uncertainty analysis to evaluate whether the measurement system meets the accuracy requirements.

[0024] This invention utilizes three-degree-of-freedom flip calibration technology, which not only reduces the use of standard components and measurement uncertainty caused by differences between test pieces, ensuring the uniqueness and accuracy of measurement data, but also significantly reduces the number of test pieces required, lowers calibration costs, and improves the practicality and cost-effectiveness of the calibration process. This invention can comprehensively assess and enhance the accuracy, reliability, and standardization of existing measurement systems, ensuring that their application in engineering quality inspections achieves highly unified, accurate, and traceable metrological standards.

[0025] The dimension detection of the measurement system of the present invention meets the accuracy requirements, which means that the dimension error variation of the dimension standard concrete specimen is no more than 0.1mm; the angle detection of the measurement system meets the accuracy requirements, which means that the angle variation of the angle standard concrete specimen is less than 0.05°; the flatness detection of the measurement system meets the accuracy requirements, which means that the flatness variation of the flatness standard concrete specimen is no more than 0.005mm.

[0026] Compared with the prior art, the present invention has the following significant effects:

[0027] (1) The present invention adopts three-degree-of-freedom flip calibration technology, which uses a single high-precision specimen to achieve flexible rotation in the X, Y, and Z directions, thereby comprehensively and multi-angle evaluating the performance of the measurement system in different spatial positions, reducing the demand for standard specimens, reducing calibration costs, and improving the practicality and economy of the calibration process.

[0028] The present invention designs an integrated standard concrete specimen that combines three functional modules for dimension, angle, and flatness testing. This multi-parameter integration concept reduces the number of standard components, effectively reducing measurement errors caused by differences between specimens and improving the accuracy and repeatability of measurement results. During measurement, the measurement system can simultaneously measure and calibrate key parameters such as dimension, angle, and flatness, improving detection efficiency and reducing storage and transportation costs.

[0029] (3) To test the measurement system's dimensional measurement capabilities, the present invention designed a standard concrete specimen dimensional detection module with an integrated three-degree-of-freedom flipping mechanism. This module sets differentiated dimensions in three orthogonal dimensions. Based on a high-precision dimensional control benchmark, it simulates the various dimensional challenges encountered in actual measurements, thereby testing the measurement system's ability to identify non-standard components and the accuracy of independent dimensional measurements. This calibration process not only verifies the measurement system's dimensional detection accuracy, but also utilizes a three-degree-of-freedom flipping strategy to evaluate the system's stability in different postures and the consistency of the measurement data.

[0030] (4) To test the measurement system's angular measurement capabilities, the present invention designed a standard concrete specimen angle detection module with an integrated three-degree-of-freedom flip mechanism. This module sets different standard angle values ​​for three sets of adjacent face angles. Based on a high-precision angle control benchmark, the measurement system's angle detection accuracy is thoroughly verified. Furthermore, using three-degree-of-freedom flip calibration technology, the stability of the measurement system under different postures is examined, ensuring high consistency in the measured data.

[0031] (5) To test the flatness measurement capability of the measurement system, the present invention designed a standard concrete specimen flatness detection module with an integrated three-degree-of-freedom flipping mechanism. This module controls flatness by setting steps of varying heights to simulate actual measurements. This specimen calibration process not only accurately verifies the measurement system's flatness accuracy, but also, with the help of three-degree-of-freedom flipping technology, comprehensively evaluates the system's stability in different postures and the reliability of the measurement data, providing a solid guarantee for the accuracy of flatness detection.

[0032] (6) By designing a standard specimen and combining it with three-degree-of-freedom flip calibration technology, the present invention effectively reduces the measurement deviation that may be caused by a single perspective and comprehensively evaluates the status of the specimen. It not only accurately reflects the true status of the specimen's size, angle, and flatness, but also further improves the scientificity and comprehensiveness of the calibration process, opening up a new calibration path for non-contact measurement technology of concrete specimen dimensions. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0034] Figure 1This is one of the schematic diagrams of the model of the non-contact measurement system for concrete specimen dimensions;

[0035] Figure 2 This is the second schematic diagram of the non-contact measurement system model for concrete specimen dimensions;

[0036] Figure 3 It is one of the structural schematic diagrams of the standard concrete specimen of the present invention;

[0037] Figure 4 This is the second structural diagram of the standard concrete specimen of the present invention;

[0038] Figure 5 This is a schematic diagram of the structure of the standard concrete specimen size detection module of the present invention with a specification of 149mm×150mm×151mm;

[0039] Figure 6 is a schematic diagram of the present invention performing a flipping experiment on a standard concrete specimen;

[0040] Figure 7 This is a schematic structural diagram of the angle detection module of a standard concrete specimen with a specification of 149mm×150mm×151mm according to the present invention;

[0041] Figure 8 It is a structural schematic diagram of the flatness detection module of a standard concrete specimen with a specification of 149mm×150mm×151mm according to the present invention.

[0042] Figure 9 It is a structural schematic diagram of another embodiment of the flatness detection module of a standard concrete specimen with a specification of 149mm×150mm×151mm according to the present invention. DETAILED DESCRIPTION

[0043] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0044] The existing non-contact measurement system model of concrete specimen size is as follows: Figure 1 、 Figure 2 As shown, the system mainly consists of a base 1 and several high-precision laser sensors (or image sensors) 3. The base 1 serves as the supporting structure of the system, and the concrete specimen 2 ( Figure 1 The standard concrete specimen of the present invention is used in the calibration process. Figure 2The concrete specimen to be tested (in the middle) is placed on the base 1; sensors are arranged in the X-axis direction and on both sides of the specimen for measuring the dimensional data of the specimen in the X-axis direction; sensors are arranged in the Y-axis direction and on both sides of the specimen for measuring the dimensional data of the specimen in the Y-axis direction; sensors are arranged in the Z-axis direction and above the specimen for measuring the dimensional data of the specimen in the Z-axis direction.

[0045] This non-contact measurement system uses sensor detection technology, arranging sensors in the X-axis, Y-axis, and Z-axis directions in the three-dimensional space of the test piece. By collecting measurement data output by sensors in each direction and combining the calibration data of these sensors in their initial state, the precise position and size model of the test piece in three-dimensional space is established, thereby achieving non-contact, high-precision measurement of the test piece's dimensions.

[0046] The non-contact concrete specimen dimension measurement system has a resolution of 0.01 mm and can measure dimensions within the range of (0 to 300) mm, with the maximum allowable error controlled within ±0.2 mm.

[0047] In order to verify the measurement accuracy of the system, the present invention provides a standard concrete specimen, such as Figure 3 、 Figure 4 As shown, it includes a specimen body, which is a rectangular block. A size detection module 4, an angle detection module 5 and a flatness detection module 6 are arranged on the specimen body, that is, the size detection module 4, the angle detection module 5 and the flatness detection module 6 are integrated on the specimen body, wherein the size detection module 4 has three different size standard values ​​set for the length of the specimen body in three orthogonal dimensions, which are L1, L2, and L3, and their values ​​are set as required; the angle detection module 5 has three different angle standard values ​​set for the angles formed by three groups of adjacent surfaces on three orthogonal dimensional planes, which are A1, A2, and A3, and their values ​​are set as required; the flatness detection module has three different flatness standard values ​​set for three steps of the specimen body on three orthogonal dimensional planes, which are F1, F2, and F3, and their values ​​are set as required.

[0048] In this embodiment, three notch-shaped grooves 7 are respectively provided at the corners of the planes of the three orthogonal dimensions of the specimen body. The three angles formed by the groove walls of the three grooves 7 and the planes where the corresponding grooves are located constitute the angle detection module 5, and the three different angle standard values ​​of the angle detection module 5 are A1, A2, and A3; three steps 8 are respectively provided on the groove bottom surfaces of the three grooves 7 to constitute the flatness detection module 6, and the three different flatness standard values ​​of the flatness detection module 6 are F1, F2, and F3; the corner formed by the planes of the three orthogonal dimensions where the grooves are set has three adjacent orthogonal edges to constitute the size detection module 4, and the three different size standard values ​​of the size detection module 4 are L1, L2, and L3.

[0049] In addition, the present invention also provides a calibration method for a non-contact measurement system for the concrete specimen size using the above-mentioned standard concrete specimen.

[0050] The present invention covers three core aspects: 1. Design and measurement method of standard concrete specimen size detection module; 2. Design and measurement method of standard concrete specimen angle detection module; 3. Design and measurement method of standard concrete specimen flatness detection module.

[0051] 1. Design and measurement method of standard concrete specimen size detection module

[0052] 1.1 Size detection module design

[0053] In compliance with the provisions of GB / T 50081-2019, "Standard for Test Methods of Physical and Mechanical Properties of Concrete," the dimensional tolerances of specimens, such as side length, diameter, and height, must not exceed 1mm. To objectively verify the accuracy of the non-contact measurement system in detecting concrete specimen dimensions, particularly its ability to identify minute dimensional variations, this paper uses standard specimens meeting common concrete prism specifications (e.g., 100mm×100mm×100mm, 150mm×150mm×150mm, and 150mm×150mm×300mm) with differentiated dimensions to simulate minute deviations in actual measurements.

[0054] At the same time, the present invention has constructed a comprehensive experimental framework that integrates test strategies, experimental planning, and data processing methods. The framework aims to evaluate the performance of the measurement system when processing objects that are close to the standard size but have slight deviations (such as ±1mm difference in length, width, or height) through standardized processes. Taking the 150mm×150mm×150mm specimen size standard as an example, the size detection module with a design size of 149mm×150mm×151mm simulates the measurement of objects that are close to but slightly smaller than the target size, such as Figure 5 As shown, the remaining dimensions can be designed with reference to this dimension. The specific experimental steps are as follows:

[0055] S1. Place the standard concrete specimen on the base of the concrete specimen size non-contact measurement system;

[0056] In this embodiment, a standard concrete specimen containing a detection module that has been high-precision machined to a size of 149mm×150mm×151mm is selected and placed at the geometric center of the base to ensure that it is firmly installed and strictly parallel to the reference surface of the base. This is used as a calibration reference to minimize measurement errors introduced by external factors.

[0057] S2. Start the measurement system, perform multiple repetitive measurements on each calibration point of the dimensional detection module of the standard concrete specimen in the initial position, obtain measurement data of each calibration point, average the measurement data of each calibration point, calculate the indication error, and obtain the measurement result of each calibration point;

[0058] To comprehensively and accurately calibrate the measurement system's three orthogonal dimensions—X (length), Y (width), and Z (height)—the present invention implements a multi-dimensional independent calibration process. Ten repeatability measurements are performed in each dimension (see Table 1 - Repeatability Data for Specimen X-Axis Dimension Measurements). The average and indicated error are then used as the measurement result, enhancing data robustness and statistical validity, correcting for both systematic bias and random error sources.

[0059] Serial number 1 2 3 4 5 data <![CDATA[L1mm]]> <![CDATA[L2mm]]> <![CDATA[L3mm]]> <![CDATA[L4mm]]> <![CDATA[L5mm]]> Serial number 6 7 8 9 10 data <![CDATA[L6mm]]> <![CDATA[L7mm]]> <![CDATA[L8mm]]> <![CDATA[L9mm]]> <![CDATA[L 10 mm]]>

[0060] (Table 1)

[0061] The average value of experimental measurements at each calibration point:

[0062]

[0063] Among them, L i is the data of the i-th time, n=10, It is the average (mm) of 10 dimensional measurements of each calibration point in the X, Y, and Z directions of the measurement system.

[0064] Dimension indication error at each calibration point:

[0065]

[0066] Where, L S is the reference value of the standard specimen size (mm), δ L It is the indication error (mm) of the measurement system in the X, Y and Z directions at each calibration point.

[0067] S3, such as Figure 6As shown, the controller is used to automatically rotate the standard concrete specimen 90 degrees along the X-axis, Y-axis and Z-axis respectively. Each time it is flipped, multiple repetitive measurements are performed on each calibration point of the standard concrete specimen in this position to obtain the measurement data of each calibration point. The measurement data of each calibration point are averaged and the indication error is calculated to obtain the measurement results of each calibration point.

[0068] S4. Analyze the measurement results and evaluate whether the measurement system meets the accuracy requirements.

[0069] To verify the performance consistency and accuracy of the measurement system under different spatial orientations, we designed and performed a flip experiment. During this experiment, the standard specimen was rotated 90 degrees along each of the X, Y, and Z axes to simulate various directional changes that might be encountered in real-world applications. The measurement calibration process was repeated to comprehensively verify the measurement system's responsiveness under different spatial orientations. The measurement results were then compared and analyzed with known reference values ​​to comprehensively assess whether the measurement system met accuracy requirements and specifications.

[0070] Examples:

[0071] In the standard concrete specimen size measurement module, enter the quantity The primary source of uncertainty is the repeatability of the measurement system. A 149mm × 150mm × 151mm standard specimen was measured 10 times in three positions (Position 1 - X(149mm), Y(150mm), Z(151mm)), (Position 2 - X(151mm), Y(149mm), Z(150mm)), and (Position 3 - X(150mm), Y(151mm), Z(149mm)). The results are shown in the table below.

[0072]

[0073] (Table 2)

[0074] This non-contact concrete specimen dimensional measurement system demonstrates exceptional dimensional detection capabilities in all three dimensions: X, Y, and Z. It can accurately capture and measure extremely small deviations (±1mm in length, width, and height) in standard specimens, ensuring high accuracy. In repeated measurement experiments, the system's output data was virtually identical, with an indication error ranging from +0.038mm to +0.049mm, a variation of 0.011mm, meeting the requirement of less than 0.1mm variation. There was no significant fluctuation or accumulated deviation, fully demonstrating the stability and reliability of its measurement results.

[0075] 2. Design and measurement method of standard concrete specimen angle detection module

[0076] 2.1 Angle detection module design

[0077] GB / T 50081-2019 "Standard for Test Methods of Physical and Mechanical Properties of Concrete" stipulates that the angle between adjacent surfaces of the specimen should be 90°, and its tolerance shall not exceed 0.5°. Therefore, in the angle measurement calibration process of the measurement system, the present invention adopts a standard concrete specimen angle detection module (such as 89.5°, 90°, 90.5°) with precise angle reference values. Figure 7 The standard angle measurement module (shown in Figure 1) serves as a calibration benchmark to assess the accuracy and sensitivity of the measurement system when processing angles close to the standard but with slight deviations (e.g., ±0.5°), ensuring a highly accurate calibration process. Therefore, the error of the standard concrete specimen angle detection module used in this invention must be strictly controlled within ±0.02°. Furthermore, to verify the stability and repeatability of the measurement results, the fluctuation of the angle data obtained from multiple measurements on the same specimen must not exceed a limit of 0.05°.

[0078] 2.2 Angle measurement method

[0079] During the calibration process, a standard concrete specimen is first precisely placed on the measurement system's base. The system then performs angular measurements along three orthogonal axes, namely, the X, Y, and Z axes, to comprehensively evaluate the system's measurement capabilities and accuracy in different spatial directions. Ten independent, repeatable measurements are performed on each axis (X, Y, and Z) (see Table 3 for repeatability data for the same angle measurement on the specimen). This accumulation of sufficient data samples allows for precise calibration of the measurement system's performance in complex, multi-angle measurement scenarios, ensuring the comprehensiveness and accuracy of the overall calibration.

[0080] Serial number 1 2 3 4 5 data <![CDATA[A1°]]> <![CDATA[A2°]]> <![CDATA[A3°]]> <![CDATA[A4°]]> <![CDATA[A5°]]> Serial number 6 7 8 9 10 data <![CDATA[A6°]]> <![CDATA[A7°]]> <![CDATA[A8°]]> <![CDATA[A9°]]> <![CDATA[A 10 °]]>

[0081] (Table 3)

[0082] After data collection is complete, the measured data is further processed. This involves calculating the mean value and indication error, providing a solid statistical basis for evaluating the accuracy of the measurement system.

[0083] The average value of experimental measurements at each calibration point:

[0084]

[0085] Among them, A i is the data of the i-th time, n=10, It is the average (°) of 10 dimensional measurements of each calibration point in the X, Y, and Z directions of the measurement system.

[0086] Dimension indication error at each calibration point:

[0087]

[0088] Where A S is the reference value of the standard specimen size (°), δ A The measurement system shows the error (°) of the dimensional measurement at each calibration point in the X, Y and Z directions.

[0089] Finally, the standard specimen is rotated 90 degrees along the X, Y, and Z axes, and the measurement process is repeated to test the angle measurement performance of the measurement system in different spatial postures. By comparing and analyzing the measurement results with known standard values ​​and adopting strict evaluation criteria, a comprehensive assessment is made to determine whether the measurement system meets the established accuracy requirements and specifications.

[0090] Examples:

[0091] In the standard concrete specimen angle measurement module, input The main source of uncertainty is the repeatability of the measurement system. Ten measurements were repeated under the same conditions at the measurement points of 89.5°, 90°, and 90.5°. (Position 1: X(89.5°), Y(90.0°), Z(90.5°)), (Position 2: X(90.5°), Y(89.5°), Z(90.0°)), and (Position 3: X(90.0°), Y(90.5°), Z(89.5°)) are shown in Table 4.

[0092]

[0093] (Table 4)

[0094] This non-contact concrete specimen dimension measurement system demonstrates exceptional angle detection capabilities in all three dimensions: X, Y, and Z. It can accurately capture and measure extremely small deviations (±0.5°) in angle-standard concrete specimens, ensuring extremely high accuracy. In repeated measurement experiments, the system's output data was virtually identical, with an indication error ranging from -0.03° to 0°, a variation of 0.03°, meeting the requirement for an angle variation of less than 0.05°. There was no significant fluctuation or accumulated deviation, fully demonstrating the stability and reliability of its measurement results.

[0095] 3. Design and measurement method of standard concrete specimen flatness detection module

[0096] 3.1 Design of standard concrete specimens for flatness

[0097] GB / T 50081-2019 "Standard for Test Methods of Physical and Mechanical Properties of Concrete" stipulates that the flatness tolerance of the bearing surface of the specimen shall not exceed 0.0005d, where d is the side length of the specimen. Therefore, based on the profound consideration of the resolution and sensitivity of the measurement system, the flatness reference dimensions designed and manufactured are 0.05mm, 0.10mm, and 0.15mm (such as Figure 8 (as shown), the maximum allowable flatness error is controlled within ±0.005mm, with a variation of no more than 0.005mm. Artificial flatness errors are created to simulate the slight deviations that may be encountered in actual applications. This allows the accuracy and sensitivity of the measurement system to be evaluated when dealing with near-standard flatness but with slight deviations (0.1mm, 0.05mm, and 0.15mm), ensuring its reliability in actual measurement tasks.

[0098] 3.2 Flatness measurement method

[0099] During the measurement, a standard flatness concrete specimen was placed on the base of the measurement system. Subsequently, each direction was measured 10 times under the same conditions to improve the accuracy and reliability of the results, reduce the impact of random errors, and enhance the stability and scientific nature of the results through repeated data verification. The measurement data (same plane) are shown in Table 5.

[0100] Serial number 1 2 3 4 5 data <![CDATA[F1mm]]> <![CDATA[F2mm]]> <![CDATA[F3mm]]> <![CDATA[F4mm]]> <![CDATA[F5mm]]> Serial number 6 7 8 9 10 data <![CDATA[F6mm]]> <![CDATA[F7mm]]> <![CDATA[F8mm]]> <![CDATA[F9mm]]> <![CDATA[F 10 mm]]>

[0101] (Table 5)

[0102] After data collection is complete, the measured data is processed in depth. By calculating the average value and indication error, a solid statistical basis is provided for evaluating the accuracy of the measurement system.

[0103] The average value of experimental measurements at each calibration point:

[0104]

[0105] Among them, F i is the data of the i-th time, n=10, It is the average (mm) of 10 dimensional measurements of each calibration point in the X, Y, and Z directions of the measurement system.

[0106] Dimension indication error at each calibration point:

[0107]

[0108] Where, F S is the reference value of the standard specimen size (mm), δ F The measurement system shows the error (mm) of the dimensional measurement at each calibration point in the X, Y and Z directions.

[0109] Finally, the specimen is flipped over and scanned comprehensively and meticulously in three dimensions: X, Y, and Z. This multi-dimensional measurement method effectively avoids measurement deviations that may be caused by a single viewing angle and comprehensively evaluates the flatness of the specimen.

[0110] Examples:

[0111] In the standard concrete specimen flatness measurement module, input the The main source of uncertainty is the repeatability of the measurement system. Using measurement points at 0.05mm, 0.10mm, and 0.15mm, the following table shows the results of 10 repeated measurements under the same conditions: (pose 1 - X(0.05mm), Y(0.10mm), Z(0.15mm)), (pose 2 - X(0.10mm), Y(0.15mm), Z(0.05mm)), and (pose 3 - X(0.15mm), Y(0.05mm), Z(0.10mm)).

[0112]

[0113] (Table 6)

[0114] This non-contact concrete specimen dimensional measurement system demonstrates exceptional flatness measurement capabilities in all three dimensions: X, Y, and Z. It can accurately capture and measure extremely small deviations (0.05mm, 0.10mm, and 0.15mm) in the plane of a standard concrete specimen, ensuring the accuracy of the measurement results. In repeated measurement experiments, the system demonstrated extremely high data consistency, with nearly identical output results. The indication error remained stable within a narrow range of +0.0013mm to +0.0040mm, and the overall variation was strictly controlled within 0.0027mm, far below the standard variation limit of no more than 0.005mm. This performance significantly demonstrates that the system produced no perceptible fluctuations or error accumulation during the measurement process, thus firmly verifying the excellent stability and high reliability of its measurement results.

[0115] In addition, in step S4, the measurement results are analyzed, that is, the dimensional measurement uncertainty, angle measurement uncertainty and flatness measurement uncertainty are analyzed respectively, and finally the measurement system synthetic uncertainty analysis is performed (which is the existing technology), so as to evaluate whether the measurement system meets the accuracy requirements.

[0116] In other embodiments, according to actual conditions, size detection modules, flatness detection modules and angle detection modules of different specifications may be provided on the specimen body; size detection modules of different specifications, i.e., different size standard values, for example, in addition to the size detection module with a specification of 149mm×150mm×151mm, other size detection modules include 99mm×100mm×101mm and 299mm×300mm×301mm; flatness detection modules of different specifications, i.e., different flatness standard values, for example, in addition to the flatness detection modules with specifications of 0.05mm, 0.10mm, and 0.15mm, other flatness detection modules include 0.10mm, 0.15mm, 0.20mm and 0.02mm, 0.05mm, and 0.08mm; angle detection modules of different specifications, i.e., different angle standard values, generally require angle detection modules with specifications of 89.5°, 90°, and 90.5°. If the instrument has special requirements, the standard value of the angle detection module can be set as required, such as 89°, 90°, and 91°.

[0117] like Figure 9 As shown, in another embodiment, this embodiment is different from the above embodiment in that: the setting position of the flatness detection module is different. In this embodiment, three steps are respectively provided at the corners of the planes of the three orthogonal dimensions where the groove is set to form a flatness detection module, and the specific position of the steps on each plane can be set according to actual conditions.

[0118] The present invention is effective for a non-contact measurement system for concrete specimen dimensions, and uses a high-precision standard concrete specimen integrated with dimension, angle, and flatness detection modules for calibration. Using one standard concrete specimen, the dimension, angle, and flatness measurement capabilities of the non-contact measurement system for concrete specimen dimensions can be accurately calibrated.

[0119] The present invention adopts three-degree-of-freedom flip calibration technology to effectively avoid the measurement deviation that may be caused by a single viewing angle, comprehensively evaluate the status of the test piece, reduce the use of standard parts, reduce the measurement uncertainty caused by differences between test blocks, ensure the uniqueness and accuracy of the measurement data, reduce calibration costs, and improve the practicality and economy of the calibration process.

[0120] The present invention incorporates precise control standards for dimensions, angles, and flatness in the design of test pieces, enabling simulation of various conditions encountered in actual measurements. During measurement, the measurement system simultaneously calibrates key parameters such as dimensions, angles, and flatness, improving inspection efficiency and reducing storage and transportation costs.

[0121] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A standard concrete specimen, comprising a specimen body, wherein the specimen body is a rectangular block, characterized in that: A size detection module, an angle detection module and a flatness detection module are arranged on the specimen body. The size detection module has three different size standard values ​​set for the length of the specimen body in three orthogonal dimensions, the flatness detection module has three different flatness standard values ​​set for the steps of the specimen body on the three orthogonal dimensional planes, and the angle detection module has three different angle standard values ​​set for the angles formed by three groups of adjacent faces of the specimen body on the three orthogonal dimensional planes, so that during detection, the measurement system can simultaneously measure and calibrate the three different size standard values ​​of the size detection module, the three different angle standard values ​​of the angle detection module and the three different flatness standard values ​​of the flatness detection module in each posture of the standard concrete specimen.

2. The standard concrete specimen according to claim 1, characterized in that: Notch-shaped grooves are respectively provided at the corners of the planes of the three orthogonal dimensions of the specimen body. The three angles formed by the groove walls of the three grooves and the planes where the corresponding grooves are located constitute an angle detection module. Three steps are respectively provided on the groove bottom surfaces of the three grooves to constitute a flatness detection module. The corners formed by the planes of the three orthogonal dimensions where the grooves are set have three adjacent orthogonal edges to constitute a size detection module.

3. The standard concrete specimen according to claim 1, characterized in that: Notch-shaped grooves are respectively provided at the corners of the planes of the three orthogonal dimensions of the specimen body, and three angles formed by the groove walls of the three grooves and the planes where the corresponding grooves are located constitute an angle detection module. Three steps are respectively provided on the planes of the three orthogonal dimensions where the grooves are set to constitute a flatness detection module, and the corner formed by the planes of the three orthogonal dimensions where the grooves are set has three adjacent orthogonal edges that constitute a size detection module.

4. The standard concrete specimen according to claim 2 or 3, characterized in that: The specifications of the different size detection modules are 99mm×100mm×101mm, 149mm×150mm×151mm and 299mm×300mm×301mm. Among them, the size detection module with the specification of 99mm×100mm×101mm is used for measuring the target size of 100mm×100mm×100mm; the size detection module with the specification of 149mm×150mm× The 151mm size detection module is used for measuring target sizes of 150mm×150mm×150mm; the size detection modules with specifications of 149mm×150mm×151mm and 299mm×300mm×301mm are combined for measuring target sizes of 150mm×150mm×300mm.

5. The standard concrete specimen according to claim 4, characterized in that: The maximum allowable error of the standard size value is within ±0.05mm.

6. The standard concrete specimen according to claim 5, characterized in that: The standard angle values ​​of the angle detection module are: 89.5°, 90°, 90.5°.

7. The standard concrete specimen according to claim 6, characterized in that: The maximum permissible error of the standard angle value is within ±0.02°.

8. The standard concrete specimen according to claim 7, characterized in that: For the standard concrete specimen of 100mm×100mm×100mm, the three flatness standard values ​​of the flatness detection module are: 0.02mm, 0.05mm and 0.08mm; for the standard concrete specimen of 150mm×150mm×150mm, the three flatness standard values ​​of the flatness detection module are: 0.05mm, 0.10mm and 0.15mm; for the standard concrete specimen of 300mm×300mm×300mm, the three flatness standard values ​​of the flatness detection module are: 0.10mm, 0.15mm and 0.20mm.

9. The standard concrete specimen according to claim 8, characterized in that: The maximum allowable error of the flatness standard value is within ±0.005mm.

10. A method for calibrating a non-contact measurement system for concrete specimen dimensions using the standard concrete specimen according to any one of claims 1 to 9, characterized in that The following steps are involved: S1. Place the standard concrete specimen on the base of the concrete specimen size non-contact measurement system; S2. Start the measurement system, and the measurement system performs multiple repetitive measurements on the calibration points on each module of the standard concrete specimen in the initial position to obtain the measurement data of each calibration point, and average the measurement data of each calibration point and calculate the indication error to obtain the measurement result of each calibration point; S3, using a controller to automatically rotate the standard concrete specimen by 90 degrees along the X-axis, Y-axis and Z-axis respectively, and each time it is flipped, multiple repetitive measurements are performed on the calibration points on each module of the standard concrete specimen in this position to obtain the measurement data of each calibration point, and the measurement data of each calibration point are averaged and the indication error is calculated to obtain the measurement result of each calibration point; S4. Analyze the measurement results obtained in steps S2 and S3, that is, analyze the dimensional measurement uncertainty, angle measurement uncertainty and flatness measurement uncertainty respectively, and finally perform a measurement system combined uncertainty analysis to evaluate whether the measurement system meets the accuracy requirements.

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