A device and method for measuring the diameter change rate of a PVC pipe

Abstract

The invention discloses a measuring device and a measuring method for the diameter change rate of a PVC pipe. The PVC pipe is an asymmetric periodic corrugated structure. The measuring method comprises the following steps: introducing the PVC pipe to be measured into a multi-degree-of-freedom measuring platform along the axial direction, synchronously collecting comprehensive image data of the PVC to be measured through an annular camera array, extracting surface features, and generating an outer contour three-dimensional point cloud model; using a multi-angle ultrasonic probe group to obtain ultrasonic data, performing a joint analysis in the time-frequency domain, and reconstructing a distribution map of the inner wall thickness of the pipe; aligning the spatial coordinates of the outer contour point cloud model and the inner wall thickness distribution map, and establishing a dual-modal weighted evaluation model based on periodic features; generating a feedback control signal based on the real-time evaluation result of the dual-modal weighted evaluation model, and performing a matching degree analysis on the diameter change rate data after weighted fusion and the corrugation tolerance curve, and outputting a pipe structure consistency evaluation index; the measurement accuracy and reliability of the diameter change rate of the asymmetric corrugated structure pipe are significantly improved.

Description

Technical Field

[0001] The invention relates to the field of photovoltaic tubes, and in particular to a device and method for measuring the diameter change rate of a PVC pipe. Background Art

[0002] PVC pipes are widely used in building drainage, municipal engineering, agricultural irrigation and other fields due to their corrosion resistance, light weight, high strength and low cost. In recent years, with the diversification of engineering needs, PVC pipes with corrugated reinforcement structures have gradually become the mainstream of the market. Their asymmetric periodic corrugation design significantly improves the pipe's compressive performance and fluid flow efficiency. However, this complex structure also brings quality control difficulties, especially the alternating distribution of corrugated and smooth sections, and the non-uniformity of corrugation depth and spacing, which makes it difficult for traditional measurement methods to accurately capture changes in pipe diameter, directly affecting pipe performance evaluation and production process optimization.

[0003] In the prior art, optical measurement methods are mainly used to measure the diameter of PVC pipes. For example, the outer contour data of the pipe is obtained through laser scanning or visual imaging, and then the diameter change rate is calculated through algorithms. However, this type of method has obvious limitations when facing asymmetric corrugated structures: first, optical measurement relies on surface reflection characteristics, and the complex curved surface of the corrugated structure will cause light scattering, reducing measurement accuracy; second, the prior art usually only focuses on the outer contour data and cannot obtain the thickness change information of the inner wall of the pipe, resulting in systematic errors in the diameter calculation. For example, the prior art (CN110595369B) uses a single visual measurement method. Although it can realize the diameter detection of conventional pipes, when dealing with asymmetric corrugated structures, its measurement error can reach more than ±0.5mm, which cannot meet the requirements of high-precision quality control.

[0004] In view of this, it is necessary to improve the diameter measurement technology of PVC pipes in the prior art to solve the technical problem that high-precision measurement of asymmetric corrugated structures cannot be achieved. Summary of the invention

[0005] The purpose of the present invention is to provide a device and method for measuring the diameter change rate of a PVC pipe to solve the above technical problems.

[0006] To achieve this object, the present invention adopts the following technical solutions:

[0007] A method for measuring the diameter change rate of a PVC pipe, wherein the PVC pipe is an asymmetric periodic corrugated structure, which includes a corrugated section and a smooth section, and the measuring method includes:

[0008] The PVC pipe to be tested is introduced into the multi-degree-of-freedom measuring platform along the axial direction, so that the corrugated section and the smooth section pass through the composite detection area in sequence;

[0009] The camera array arranged in a ring synchronously collects comprehensive image data of the outer surface of the PVC to be tested. At the same time, a multi-angle ultrasonic probe group is used to transmit focused ultrasonic waves to the inner wall of the pipe and receive reflected signals, and the ultrasonic data is obtained by signal conversion.

[0010] Extract the surface features of the comprehensive image data based on adaptive illumination compensation to generate a three-dimensional point cloud model of the outer contour; perform a joint analysis of the ultrasonic data in the time and frequency domains to reconstruct a distribution map of the inner wall thickness of the pipe;

[0011] The spatial coordinates of the outer contour point cloud model and the inner wall thickness distribution map are aligned, and the equivalent diameter sequences of the peak, valley and smooth section of the corrugated section are calculated by fusion; and a dual-modal weighted evaluation model is established based on the periodic characteristics of the corrugated structure: the curvature change weight is given to the comprehensive image data, and the thickness fluctuation weight is given to the ultrasonic data, and the weight coefficient is dynamically adjusted through the particle swarm optimization algorithm;

[0012] According to the real-time evaluation results of the dual-modal weighted evaluation model, a feedback control signal is generated to synchronously adjust the rotation speed and axial feed speed of the multi-degree-of-freedom measurement platform so that the corrugated section obtains a higher sampling density. At the same time, the diameter change rate data after weighted fusion is matched with the preset asymmetric corrugation tolerance curve to output the pipe structure consistency evaluation index.

[0013] Optionally, performing surface feature extraction based on adaptive illumination compensation on the comprehensive image data to generate an outer contour three-dimensional point cloud model specifically includes:

[0014] The original comprehensive image data obtained by the camera array uses a local illumination compensation algorithm based on Retinex theory to eliminate shadow areas and non-uniform illumination interference caused by the corrugated structure;

[0015] The compensated comprehensive image data is subjected to Gaussian filtering for noise reduction, which retains the ripple edge features while suppressing high-frequency noise;

[0016] The Canny edge detection algorithm is used to extract the preliminary feature points of the outer contour of the pipe, and the contour gaps are filled through morphological closing operations to generate a continuous outer contour binary image;

[0017] The SIFT feature point detection algorithm is used, combined with the periodic prior information of the ripple structure, to locate the key feature points of the ripple peak, valley bottom and smooth segment in the outer contour binary image;

[0018] The feature points are connected into an initial surface mesh through a triangulated meshing algorithm, and the Laplace smoothing algorithm is used to optimize the mesh curvature, eliminate local distortion, and obtain an optimized surface mesh.

[0019] Based on the optimized surface mesh, the iterative closest point algorithm is used to align the comprehensive image data from multiple perspectives to generate a complete outer contour 3D point cloud model.

[0020] Optionally, the performing a time-frequency domain joint analysis on the ultrasonic data to reconstruct the pipe inner wall thickness distribution map specifically includes:

[0021] Perform wavelet transform on the original reflection signal collected by the multi-angle ultrasonic probe group to separate the direct wave, interface reflection wave and noise components;

[0022] The envelope signal of the interface reflection wave is extracted through Hilbert transform, the propagation time of ultrasonic wave on the inner wall of the pipe is calculated, and the inner wall thickness distribution is inverted by combining the sound velocity model;

[0023] Adaptive threshold filtering is used to eliminate outliers in thickness data, and a continuous distribution map of inner wall thickness is reconstructed using a cubic spline interpolation algorithm.

[0024] Establish a unified reference coordinate system based on the geometric centerline and axial symmetry of the pipe;

[0025] The spatial position of the outer contour point cloud model and the inner wall thickness distribution map are roughly aligned using the least squares method.

[0026] Optionally, aligning the outer contour point cloud model with the inner wall thickness distribution map in spatial coordinates specifically includes:

[0027] Based on the roughly aligned outer contour point cloud model and the inner wall thickness distribution map, the iterative closest point algorithm is used to align the outer contour point cloud model and the inner wall thickness distribution map to minimize the spatial error between the two.

[0028] By introducing the periodic constraint of the corrugated structure, the rotation and translation parameters in the registration process are optimized to ensure the spatial position consistency of the corrugated peak, valley and smooth segment.

[0029] The registered data is used to generate a joint 3D model of the inner and outer walls of the pipe.

[0030] Optionally, the fusion calculation of the equivalent diameter sequence of the peak, valley and smooth segment of the ripple segment specifically includes:

[0031] In the joint 3D model, the cross-sectional profile data is extracted at preset intervals along the axial direction of the pipe;

[0032] For each cross section, the elliptical model of the inner and outer wall contours was fitted using the least squares method to calculate the local equivalent diameters of the corrugation peaks, valleys, and smooth sections;

[0033] The discrete equivalent diameter data are smoothed by cubic spline interpolation algorithm to generate a continuous equivalent diameter change curve.

[0034] Optionally, the bimodal weighted evaluation model is established based on the periodic characteristics of the corrugated structure, and then further includes:

[0035] Comparison between simulation data and actual measurement data obtained through the output of the dual-modal weighted evaluation model is used to evaluate the adaptability of the model under different corrugated structures;

[0036] The root mean square error and correlation coefficient R² were used as evaluation indicators to verify the fitting accuracy of the equivalent diameter change curve;

[0037] According to the verification results of the fitting accuracy, the weight function and the optimization algorithm are iteratively adjusted to verify the effectiveness of the bimodal weighted evaluation model.

[0038] Optionally, according to the real-time evaluation result of the dual-modal weighted evaluation model, a feedback control signal is generated to synchronously adjust the rotation speed and the axial feed speed of the multi-degree-of-freedom measurement platform, specifically including:

[0039] Acquire the fluctuation characteristics of the equivalent diameter change curve in real time, wherein the fluctuation characteristics include the diameter extreme value and change rate of the corrugation peak, valley bottom and smooth section;

[0040] The curvature complexity and thickness unevenness of the current measurement area are calculated based on the fluctuation characteristics, and a dynamic sampling demand index is generated;

[0041] The sampling requirement index is mapped into adjustment parameters of the rotation speed and axial feed speed of the multi-degree-of-freedom measurement platform to generate a feedback control signal;

[0042] According to the feedback control signal, the PID control algorithm is used to adjust the rotation speed of the measurement platform in real time, so that the high curvature corrugation section can obtain a higher angular velocity sampling density;

[0043] At the same time, the axial feed speed is adjusted so that the length of the pipe covered by the measuring platform per unit time matches the rotation speed.

[0044] Optionally, the weighted fused diameter change rate data is matched with the preset asymmetric corrugation tolerance curve to output the pipe structure consistency evaluation index, including:

[0045] According to the design specifications and application scenarios of the pipe, define the upper and lower limits of the asymmetric corrugation tolerance curve, including the allowable deviations of corrugation height, spacing and diameter changes;

[0046] The dynamic time warping algorithm is used to match the real-time measured diameter change rate curve with the tolerance curve, and the similarity score between the two is calculated;

[0047] Generate a pipe structure consistency evaluation index based on the similarity score and the deviation distribution, wherein the consistency evaluation index also includes the overall qualified rate and the location information of the local out-of-tolerance area;

[0048] The consistency evaluation indicators are transmitted to the display module in real time to display the measurement results and out-of-tolerance areas in a visual form;

[0049] The hierarchical processing mechanism is triggered according to the evaluation results:

[0050] For areas with slight deviations, record deviation data and generate process optimization suggestions;

[0051] For areas with serious deviations, mark the position coordinates and drive the laser marking machine for physical identification;

[0052] The evaluation results and treatment suggestions are stored in the database.

[0053] The present invention provides a device for measuring the diameter change rate of a PVC pipe, using the above-mentioned method for measuring the diameter change rate of a PVC pipe, and the measuring device comprises:

[0054] Multi-degree-of-freedom measuring platform, used to fix and drive the PVC pipe to be tested to rotate axially and feed linearly;

[0055] The camera array is arranged in a ring shape around the pipe and is used to synchronously collect comprehensive image data of the outer surface of the PVC to be tested;

[0056] Multi-angle ultrasonic probe set, used to transmit focused ultrasonic waves to the inner wall of the pipe and receive reflected signals to obtain ultrasonic data;

[0057] Data processing module, used to process comprehensive image data and ultrasonic data, including adaptive illumination compensation, surface feature extraction, time-frequency domain joint analysis, data fusion and model calculation;

[0058] A feedback control module is used to generate a control signal according to the real-time evaluation results and adjust the motion parameters of the multi-degree-of-freedom measurement platform;

[0059] The display module is used to display the diameter change rate data and consistency evaluation indicators.

[0060] Compared with the prior art, the present invention has the following beneficial effects: firstly, the axial motion control of the asymmetric periodic corrugated structure PVC pipe is realized through a multi-degree-of-freedom measurement platform, and the outer surface image data and inner wall ultrasonic data of the pipe are synchronously collected by using an annular camera array and a multi-angle ultrasonic probe group; the image data generates an outer contour three-dimensional point cloud model through adaptive illumination compensation and surface feature extraction, and the ultrasonic data reconstructs the inner wall thickness distribution map through time-frequency domain joint analysis; through spatial coordinate alignment and bimodal weighted evaluation model, the equivalent diameter sequence of the peak, valley and smooth section of the corrugated section is dynamically fused and calculated, and the weight coefficient is adjusted in real time in combination with the particle swarm optimization algorithm; based on the evaluation result, a feedback control signal is generated to adjust the rotation speed and axial feed speed of the measurement platform to achieve high-density sampling of the high-curvature corrugated section, and at the same time, the diameter change rate data is matched with the asymmetric corrugation tolerance curve to output the pipe structure consistency evaluation index; through the fusion of visual and ultrasonic bimodal data, the method not only overcomes the limitations of optical measurement, but also can dynamically optimize the measurement parameters, significantly improving the measurement accuracy and reliability of the diameter change rate of the asymmetric corrugated structure pipe. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0062] The structures, proportions, sizes, etc. illustrated in the drawings of this specification are only used to match the contents disclosed in the specification so as to facilitate understanding and reading by persons familiar with this technology. They are not used to limit the conditions under which the present invention can be implemented, and therefore have no substantive technical significance. Any structural modification, change in proportion or adjustment of size, without affecting the effects and purposes that can be achieved by the present invention, should still fall within the scope of the technical contents disclosed by the present invention.

[0063] Figure 1 This is a schematic diagram of a flow chart of a method for measuring a diameter change rate of a PVC pipe according to Embodiment 1;

[0064] Figure 2 This is a schematic diagram of the production process of the outer contour three-dimensional point cloud model of the method for measuring the diameter change rate of a PVC pipe in Example 1. DETAILED DESCRIPTION

[0065] In order to make the purpose, features and advantages of the present invention more obvious and easy to understand, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described below 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 creative work are within the scope of protection of the present invention.

[0066] In the description of the present invention, it should be understood that the terms "upper", "lower", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention. It should be noted that when a component is considered to be "connected" to another component, it may be directly connected to the other component or there may be a centrally arranged component at the same time.

[0067] The technical solution of the present invention is further described below with reference to the accompanying drawings and through specific implementation methods.

[0068] Embodiment 1:

[0069] Combination Figure 1 to Figure 2 As shown, an embodiment of the present invention provides a method for measuring the diameter change rate of a PVC pipe. The PVC pipe is an asymmetric periodic corrugated structure, which includes a corrugated section and a smooth section. The measuring method includes:

[0070] S1, guide the PVC pipe to be tested into the multi-degree-of-freedom measurement platform along the axial direction, so that the corrugated section and the smooth section pass through the composite detection area in sequence.

[0071] S2, through the circularly arranged camera array, synchronously collects the comprehensive image data of the outer surface of the PVC to be tested, and uses a multi-angle ultrasonic probe group to emit focused ultrasonic waves to the inner wall of the pipe and receive the reflected signals, and obtains ultrasonic data through signal conversion.

[0072] S3, extracts surface features based on adaptive illumination compensation from comprehensive image data to generate a three-dimensional point cloud model of the outer contour; performs joint analysis of ultrasonic data in the time and frequency domains to reconstruct the distribution map of the inner wall thickness of the pipe.

[0073] S4, align the spatial coordinates of the outer contour point cloud model with the inner wall thickness distribution map, and fuse and calculate the equivalent diameter sequence of the peak, valley and smooth segment of the corrugated segment; and establish a bimodal weighted evaluation model based on the periodic characteristics of the corrugated structure: assign curvature change weights to the comprehensive image data, assign thickness fluctuation weights to the ultrasonic data, and dynamically adjust the weight coefficients through the particle swarm optimization algorithm.

[0074] S5, based on the real-time evaluation results of the dual-modal weighted evaluation model, generates feedback control signals, synchronously adjusts the rotation speed and axial feed speed of the multi-degree-of-freedom measurement platform, so that the corrugated section obtains a higher sampling density. At the same time, the weighted fused diameter change rate data is matched with the preset asymmetric corrugation tolerance curve to output the pipe structure consistency evaluation index.

[0075] The working principle of the present invention is as follows: first, the axial motion control of the asymmetric periodic corrugated structure PVC pipe is realized through a multi-degree-of-freedom measurement platform, and the outer surface image data and inner wall ultrasonic data of the pipe are synchronously collected by a ring camera array and a multi-angle ultrasonic probe group; the image data is subjected to adaptive illumination compensation and surface feature extraction to generate an outer contour three-dimensional point cloud model, and the ultrasonic data is reconstructed through time-frequency domain joint analysis of the inner wall thickness distribution map; through spatial coordinate alignment and a bimodal weighted evaluation model, the equivalent diameter sequence of the peak, valley and smooth section of the corrugated section is dynamically fused and calculated, and the weight coefficient is adjusted in real time in combination with a particle swarm optimization algorithm; based on the evaluation result, a feedback control signal is generated to adjust the rotation speed and axial feed speed of the measurement platform to achieve high-density sampling of high-curvature corrugated sections, and at the same time, the diameter change rate data is matched with the asymmetric corrugation tolerance curve to output the pipe structure consistency evaluation index; through the fusion of visual and ultrasonic bimodal data, the method not only overcomes the limitations of optical measurement, but also can dynamically optimize the measurement parameters, significantly improving the measurement accuracy and reliability of the diameter change rate of the asymmetric corrugated structure pipe.

[0076] In this embodiment, it is specifically described that step S3 specifically includes:

[0077] S301 uses the original comprehensive image data obtained by the camera array and adopts the local illumination compensation algorithm based on Retinex theory to eliminate the shadow area and non-uniform illumination interference caused by the corrugated structure;

[0078] The Retinex theory is used to simulate the adaptability of the human eye to illumination, separate the illumination component and the reflection component in the image, and eliminate the shadow and non-uniform illumination interference caused by the ripple structure. This improves image quality and ensures the accuracy of subsequent feature extraction, especially in complex lighting conditions, where the details of the ripple structure can still be clearly captured.

[0079] S302, performing Gaussian filtering noise reduction processing on the compensated comprehensive image data to retain the ripple edge features while suppressing high-frequency noise;

[0080] The image is smoothed using a Gaussian filter, which retains the ripple edge features while suppressing high-frequency noise. This reduces random noise interference in the image, enhances the continuity of the ripple edge, and provides high-quality input data for subsequent edge detection.

[0081] S303, using the Canny edge detection algorithm to extract preliminary feature points of the outer contour of the pipe, and filling the contour gaps through morphological closing operations to generate a continuous outer contour binary image.

[0082] S304, using SIFT feature point detection algorithm, combined with the periodic prior information of the corrugation structure, locates the key feature points of the corrugation peak, valley bottom and smooth segment in the outer contour binary image; improves the accuracy of feature point detection and adapts to the complexity of asymmetric corrugation structure.

[0083] S305, connect the feature points into an initial surface mesh through a triangulated meshing algorithm, and use the Laplace smoothing algorithm to optimize the mesh curvature, eliminate local distortion, and obtain an optimized surface mesh; generate a smooth and high-precision surface mesh model, providing a high-quality geometric foundation for subsequent three-dimensional point cloud generation.

[0084] S306, based on the optimized surface mesh, the iterative closest point algorithm is used to register the comprehensive image data of multiple perspectives to generate a complete outer contour 3D point cloud model. A complete and consistent outer contour 3D point cloud model is generated to ensure the global consistency of the measurement data.

[0085] S307, performing wavelet transformation on the original reflection signal collected by the multi-angle ultrasonic probe group to separate the direct wave, the interface reflection wave and the noise component.

[0086] S308, extracting the envelope signal of the interface reflection wave through Hilbert transform, calculating the propagation time of the ultrasonic wave on the inner wall of the pipe, and inverting the inner wall thickness distribution in combination with the sound velocity model.

[0087] S309, using adaptive threshold filtering to eliminate outliers in the thickness data, and reconstructing a continuous distribution map of the inner wall thickness through a cubic spline interpolation algorithm to eliminate the influence of measurement noise and outliers.

[0088] S310, based on the geometric centerline and axial symmetry of the pipe, establishes a unified reference coordinate system to provide a benchmark for the spatial alignment of the outer contour point cloud model and the inner wall thickness distribution map, ensuring the accuracy of data fusion.

[0089] S311, roughly align the spatial position of the outer contour point cloud model and the inner wall thickness distribution map by the least square method, so as to provide initial conditions for subsequent precise registration, reduce registration errors, and improve the efficiency of data fusion.

[0090] In this embodiment, it is specifically described that step S4 specifically includes:

[0091] S401, based on the roughly aligned outer contour point cloud model and the inner wall thickness distribution map, an iterative closest point algorithm is used to align the outer contour point cloud model and the inner wall thickness distribution map to minimize the spatial error between the two;

[0092] Based on the rough alignment results, the iterative closest point (ICP) algorithm is used to accurately align the outer contour point cloud model and the inner wall thickness distribution map. By minimizing the spatial error between the two, the consistency of the spatial position of the outer contour and inner wall data is ensured, providing a high-precision data foundation for the subsequent generation of a joint 3D model.

[0093] S402, by introducing the periodic constraint conditions of the corrugation structure, the rotation and translation parameters in the registration process are optimized to ensure the consistency of the spatial positions of the corrugation peaks, valleys and smooth segments; thereby adapting to the complexity of the asymmetric corrugation structure, reducing the registration error and improving the accuracy of data fusion.

[0094] S403, using the registered data to generate a joint 3D model of the inner and outer walls of the pipe, the joint 3D model reflects the geometric characteristics of the pipe and provides comprehensive data support for equivalent diameter calculation and change rate analysis.

[0095] S404, in the joint three-dimensional model, extract cross-sectional profile data at preset intervals along the axial direction of the pipe, obtain geometric feature information at different positions of the pipe, and provide input data for subsequent calculation of local equivalent diameter.

[0096] S405, for each cross section, the elliptical model of the inner and outer wall contours is fitted using the least squares method to calculate the local equivalent diameters of the corrugation peaks, valleys and smooth sections, reflecting the diameter changes of the pipe at different locations.

[0097] S406, performing smoothing processing on the discrete equivalent diameter data by using a cubic spline interpolation algorithm to generate a continuous equivalent diameter change curve.

[0098] The discrete equivalent diameter data are smoothed by the cubic spline interpolation algorithm to generate a continuous equivalent diameter change curve, providing smooth and continuous diameter change data for subsequent analysis and visualization.

[0099] S407, and establish a dual-modal weighted evaluation model based on the periodic characteristics of the corrugated structure: assign curvature change weights to the comprehensive image data, assign thickness fluctuation weights to the ultrasonic data, and dynamically adjust the weight coefficients through the particle swarm optimization algorithm; optimize the calculation accuracy of the diameter change rate to adapt to the measurement requirements of different corrugated structures.

[0100] S408, comparing the simulation data and the actual measurement data obtained by the dual-modal weighted evaluation model output, and evaluating the adaptability of the model under different corrugated structures.

[0101] S409, using root mean square error and correlation coefficient R² as evaluation indicators, verifies the fitting accuracy of the equivalent diameter change curve, quantifies the calculation error and fitting effect of the model, and provides a basis for model optimization.

[0102] S410, according to the verification result of the fitting accuracy, iteratively adjust the weight function and the optimization algorithm to verify the effectiveness of the bimodal weighted evaluation model. Dynamically optimize the parameter setting of the model to improve the effectiveness and calculation accuracy of the bimodal weighted evaluation model and ensure the high reliability of the measurement method.

[0103] In this embodiment, it is specifically described that step S5 specifically includes:

[0104] S501, real-time acquisition of fluctuation characteristics of the equivalent diameter change curve, the fluctuation characteristics including the diameter extreme values ​​and change rates of the corrugation peaks, valleys and smooth sections;

[0105] The fluctuation characteristics of the equivalent diameter change curve are obtained in real time, including the diameter extreme values ​​and change rates of the corrugation peaks, valleys and smooth sections. By analyzing these characteristics, data support is provided for subsequent dynamic sampling and feedback control.

[0106] S502, calculating the curvature complexity and thickness unevenness of the current measurement area according to the fluctuation characteristics, and generating a dynamic sampling demand index;

[0107] According to the fluctuation characteristics, the curvature complexity and thickness unevenness of the current measurement area are calculated to generate a dynamic sampling demand index, which reflects the demand for sampling density in the measurement area and provides a basis for adjusting the motion parameters of the measurement platform.

[0108] S503, mapping the sampling requirement index into adjustment parameters of the rotation speed and axial feed speed of the multi-degree-of-freedom measurement platform to generate a feedback control signal;

[0109] The sampling demand index is mapped to the adjustment parameters of the rotation speed and axial feed speed of the multi-degree-of-freedom measurement platform to generate feedback control signals to ensure that the measurement platform can dynamically adjust the motion state according to the geometric characteristics of the pipe.

[0110] S504, according to the feedback control signal, using the PID control algorithm to adjust the rotation speed of the measurement platform in real time, so that the high curvature corrugation section obtains a higher angular velocity sampling density;

[0111] According to the feedback control signal, the PID control algorithm is used to adjust the rotation speed of the measurement platform in real time, so that the high curvature corrugation segment can obtain a higher angular velocity sampling density, thereby improving the measurement accuracy of complex areas.

[0112] S505, at the same time, adjust the axial feed speed so that the pipe length covered by the measuring platform per unit time matches the rotation speed; avoid data overlap or omission, and monitor the platform motion state in real time through the closed-loop feedback mechanism of the motion controller to ensure the stability and accuracy of the adjustment process.

[0113] S506, defining the upper and lower limits of the asymmetric corrugation tolerance curve according to the design specifications and application scenarios of the pipe, including the allowable deviations of corrugation height, spacing and diameter changes;

[0114] According to the design specifications and application scenarios of the pipe, the upper and lower limits of the asymmetric corrugation tolerance curve are defined, including the allowable deviations of corrugation height, spacing and diameter changes, providing standards for subsequent consistency evaluation.

[0115] S507, using a dynamic time warping algorithm to match the real-time measured diameter change rate curve with the tolerance curve, calculate the similarity score between the two, and quantify the degree of deviation between the measurement result and the design requirement.

[0116] S508, generating a pipe structure consistency evaluation index based on the similarity score and the deviation distribution, wherein the consistency evaluation index also includes the overall qualified rate and the location information of the local out-of-tolerance area;

[0117] Based on the similarity score and deviation distribution, the pipe structure consistency evaluation index is generated, including the overall qualified rate and the location information of the local out-of-tolerance area, providing data support for quality judgment and process optimization.

[0118] S509, transmitting the consistency evaluation index to the display module in real time, and displaying the measurement results and the out-of-tolerance area in a visual form;

[0119] The consistency evaluation indicators are transmitted to the display module in real time, and the measurement results and out-of-tolerance areas are displayed in a visual form, making it easier for operators to intuitively understand the quality status of the pipe.

[0120] S510, triggering a hierarchical processing mechanism according to the evaluation results:

[0121] For areas with slight deviations, record deviation data and generate process optimization suggestions;

[0122] For areas with serious deviations from tolerance, mark the position coordinates and drive the laser marking machine for physical identification.

[0123] The grading processing mechanism is triggered based on the evaluation results: for areas with slight deviations, the deviation data is recorded and process optimization suggestions are generated; for areas with serious deviations, the position coordinates are marked and the laser marking machine is driven for physical identification to ensure that the unqualified areas can be accurately identified and processed.

[0124] S511, store the evaluation results and processing suggestions in the database to provide data support for subsequent quality traceability and process improvement.

[0125] Embodiment 2:

[0126] The present invention further provides a device for measuring the diameter change rate of a PVC pipe, using the method for measuring the diameter change rate of a PVC pipe as in the first embodiment, the measuring device comprises:

[0127] The multi-degree-of-freedom measuring platform is used to fix and drive the PVC pipe to be tested to rotate axially and feed linearly.

[0128] The camera array is arranged in a ring shape around the pipe and is used to synchronously collect comprehensive image data of the outer surface of the PVC to be tested.

[0129] The multi-angle ultrasonic probe group is used to transmit focused ultrasonic waves to the inner wall of the pipe and receive reflected signals to obtain ultrasonic data.

[0130] The data processing module is used to process comprehensive image data and ultrasonic data, including adaptive illumination compensation, surface feature extraction, time-frequency domain joint analysis, data fusion and model calculation.

[0131] The feedback control module is used to generate control signals according to the real-time evaluation results and adjust the motion parameters of the multi-degree-of-freedom measurement platform.

[0132] The display module is used to display the diameter change rate data and consistency evaluation indicators.

[0133] As described above, the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features thereof may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for measuring the diameter change rate of a PVC pipe, characterized in that: The PVC pipe is an asymmetric periodic corrugated structure, which includes a corrugated section and a smooth section. The measuring method includes: The PVC pipe to be tested is introduced into the multi-degree-of-freedom measuring platform along the axial direction, so that the corrugated section and the smooth section pass through the composite detection area in sequence; The camera array arranged in a ring synchronously collects comprehensive image data of the outer surface of the PVC to be tested. At the same time, a multi-angle ultrasonic probe group is used to transmit focused ultrasonic waves to the inner wall of the pipe and receive reflected signals, and the ultrasonic data is obtained by signal conversion. Extract the surface features of the comprehensive image data based on adaptive illumination compensation to generate a three-dimensional point cloud model of the outer contour; perform a joint analysis of the ultrasonic data in the time and frequency domains to reconstruct a distribution map of the inner wall thickness of the pipe; The spatial coordinates of the outer contour point cloud model and the inner wall thickness distribution map are aligned, and the equivalent diameter sequences of the peak, valley and smooth section of the corrugated section are calculated by fusion; and a dual-modal weighted evaluation model is established based on the periodic characteristics of the corrugated structure: the curvature change weight is given to the comprehensive image data, and the thickness fluctuation weight is given to the ultrasonic data, and the weight coefficient is dynamically adjusted through the particle swarm optimization algorithm; According to the real-time evaluation results of the dual-modal weighted evaluation model, a feedback control signal is generated to synchronously adjust the rotation speed and axial feed speed of the multi-degree-of-freedom measurement platform so that the corrugated section obtains a higher sampling density. At the same time, the diameter change rate data after weighted fusion is matched with the preset asymmetric corrugation tolerance curve to output the pipe structure consistency evaluation index; The process of extracting surface features based on adaptive illumination compensation from the comprehensive image data to generate a three-dimensional point cloud model of the outer contour specifically includes: The original comprehensive image data obtained by the camera array uses a local illumination compensation algorithm based on Retinex theory to eliminate shadow areas and non-uniform illumination interference caused by the corrugated structure; The compensated comprehensive image data is subjected to Gaussian filtering for noise reduction, which retains the ripple edge features while suppressing high-frequency noise; The Canny edge detection algorithm is used to extract the preliminary feature points of the outer contour of the pipe, and the contour gaps are filled through morphological closing operations to generate a continuous outer contour binary image; The SIFT feature point detection algorithm is used, combined with the periodic prior information of the ripple structure, to locate the key feature points of the ripple peak, valley bottom and smooth segment in the outer contour binary image; The feature points are connected into an initial surface mesh through a triangulated meshing algorithm, and the Laplace smoothing algorithm is used to optimize the mesh curvature, eliminate local distortion, and obtain an optimized surface mesh. Based on the optimized surface mesh, the iterative closest point algorithm is used to align the comprehensive image data from multiple perspectives to generate a complete outer contour 3D point cloud model.

2. The method for measuring the diameter change rate of a PVC pipe according to claim 1, characterized in that: The time-frequency domain joint analysis of the ultrasonic data to reconstruct the pipe inner wall thickness distribution map specifically includes: Perform wavelet transform on the original reflection signal collected by the multi-angle ultrasonic probe group to separate the direct wave, interface reflection wave and noise components; The envelope signal of the interface reflection wave is extracted through Hilbert transform, the propagation time of ultrasonic wave on the inner wall of the pipe is calculated, and the inner wall thickness distribution is inverted by combining the sound velocity model; Adaptive threshold filtering is used to eliminate outliers in thickness data, and a continuous distribution map of inner wall thickness is reconstructed using a cubic spline interpolation algorithm. Establish a unified reference coordinate system based on the geometric centerline and axial symmetry of the pipe; The spatial position of the outer contour point cloud model and the inner wall thickness distribution map are roughly aligned using the least squares method.

3. The method for measuring the diameter change rate of a PVC pipe according to claim 2, characterized in that: The spatial coordinate alignment of the outer contour point cloud model and the inner wall thickness distribution map specifically includes: Based on the roughly aligned outer contour point cloud model and the inner wall thickness distribution map, the iterative closest point algorithm is used to align the outer contour point cloud model and the inner wall thickness distribution map to minimize the spatial error between the two. By introducing the periodic constraint of the corrugated structure, the rotation and translation parameters in the registration process are optimized to ensure the spatial position consistency of the corrugated peak, valley and smooth segment. The registered data is used to generate a joint 3D model of the inner and outer walls of the pipe.

4. The method for measuring the diameter change rate of a PVC pipe according to claim 3, characterized in that: The fusion calculation of the equivalent diameter sequence of the peak, valley and smooth segment of the ripple segment specifically includes: In the joint 3D model, the cross-sectional profile data is extracted at preset intervals along the axial direction of the pipe; For each cross section, the elliptical model of the inner and outer wall contours was fitted using the least squares method to calculate the local equivalent diameters of the corrugation peaks, valleys, and smooth sections; The discrete equivalent diameter data are smoothed by cubic spline interpolation algorithm to generate a continuous equivalent diameter change curve.

5. The method for measuring the diameter change rate of a PVC pipe according to claim 4, characterized in that: The method further includes establishing a dual-modal weighted evaluation model based on the periodic characteristics of the corrugated structure, and then further including: Comparison between simulation data and actual measurement data obtained through the output of the dual-modal weighted evaluation model is used to evaluate the adaptability of the model under different corrugated structures; The root mean square error and correlation coefficient R² were used as evaluation indicators to verify the fitting accuracy of the equivalent diameter change curve; According to the verification results of the fitting accuracy, the weight function and the optimization algorithm are iteratively adjusted to verify the effectiveness of the bimodal weighted evaluation model.

6. The method for measuring the diameter change rate of a PVC pipe according to claim 1, characterized in that: According to the real-time evaluation result of the dual-modal weighted evaluation model, a feedback control signal is generated to synchronously adjust the rotation speed and the axial feed speed of the multi-degree-of-freedom measurement platform, specifically including: Acquire the fluctuation characteristics of the equivalent diameter change curve in real time, wherein the fluctuation characteristics include the diameter extreme value and change rate of the corrugation peak, valley bottom and smooth section; The curvature complexity and thickness unevenness of the current measurement area are calculated based on the fluctuation characteristics, and a dynamic sampling demand index is generated; The sampling requirement index is mapped into adjustment parameters of the rotation speed and axial feed speed of the multi-degree-of-freedom measurement platform to generate a feedback control signal; According to the feedback control signal, the PID control algorithm is used to adjust the rotation speed of the measurement platform in real time, so that the high curvature corrugation section can obtain a higher angular velocity sampling density; At the same time, the axial feed speed is adjusted so that the length of the pipe covered by the measuring platform per unit time matches the rotation speed.

7. The method for measuring the diameter change rate of a PVC pipe according to claim 6, characterized in that: The weighted fused diameter change rate data is matched with the preset asymmetric corrugation tolerance curve to output the pipe structure consistency evaluation index, including: According to the design specifications and application scenarios of the pipe, define the upper and lower limits of the asymmetric corrugation tolerance curve, including the allowable deviations of corrugation height, spacing and diameter changes; The dynamic time warping algorithm is used to match the real-time measured diameter change rate curve with the tolerance curve, and the similarity score between the two is calculated; Generate a pipe structure consistency evaluation index based on the similarity score and the deviation distribution, wherein the consistency evaluation index also includes the overall qualified rate and the location information of the local out-of-tolerance area; The consistency evaluation indicators are transmitted to the display module in real time to display the measurement results and out-of-tolerance areas in a visual form; The hierarchical processing mechanism is triggered according to the evaluation results: For areas with slight deviations, record deviation data and generate process optimization suggestions; For areas with serious deviations, mark the position coordinates and drive the laser marking machine for physical identification; The evaluation results and treatment suggestions are stored in the database.

8. A device for measuring the diameter change rate of a PVC pipe, characterized in that: The method for measuring the diameter change rate of a PVC pipe as claimed in any one of claims 1 to 7 is adopted, wherein the measuring device comprises: Multi-degree-of-freedom measuring platform, used to fix and drive the PVC pipe to be tested to rotate axially and feed linearly; The camera array is arranged in a ring shape around the pipe and is used to synchronously collect comprehensive image data of the outer surface of the PVC to be tested; Multi-angle ultrasonic probe set, used to transmit focused ultrasonic waves to the inner wall of the pipe and receive reflected signals to obtain ultrasonic data; Data processing module, used to process comprehensive image data and ultrasonic data, including adaptive illumination compensation, surface feature extraction, time-frequency domain joint analysis, data fusion and model calculation; A feedback control module is used to generate a control signal according to the real-time evaluation results and adjust the motion parameters of the multi-degree-of-freedom measurement platform; The display module is used to display the diameter change rate data and consistency evaluation indicators.

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