Linear dimension measuring method and device for total length of road guardrail stand column

Abstract

The invention provides a linear dimension measurement method and device for the total length of a road guardrail stand column, and relates to the field of linear dimension measurement, the device is deployed on a detection vehicle, and comprises a control module, a ground penetrating radar measurement module, a 3D camera measurement module, a sensor module, a lower computer and an upper computer; according to the invention, accurate data acquisition is realized through multi-module cooperative control, and the lower computer is combined with the AI image recognition technology to realize accurate acquisition of contour data; the lower computer transmits radar original data (reflected waves and diffracted waves) and 3D contour data (column cap space coordinates) to the upper computer, the upper computer achieves data fusion through a hierarchical velocity model (time-depth conversion) and a coordinate system mapping algorithm (3D-road coordinate system), and the accuracy of the total length measurement error is greatly improved compared with that of single module detection. The method solves the problems of low efficiency, large destructiveness and poor accuracy of traditional manual detection, and has the advantages of method innovation and engineering landing.

Description

Technical Field

[0001] The invention relates to the field of linear dimension measurement, and in particular to a linear dimension measurement method and device for the total length of a highway guardrail column. Background Art

[0002] Highway guardrails are important facilities to ensure traffic safety and are the last barrier to ensure road traffic safety and protect lives. Their anti-collision performance is mainly reflected in two indicators: the underground buried depth of the column and the surface exposed height; among them, as the main body to bear the impact of vehicles rushing out of the road, whether the column has sufficient buried depth and exposed height according to the design requirements directly affects its ability to protect vehicles; therefore, it is necessary to measure the linear dimensions of the total length of the highway guardrail column (underground buried depth + exposed height). The current mainstream method of measuring the total length of highway guardrail columns is manual operation.

[0003] The manual inspection method for the total length of highway guardrail posts is to pull out the posts on site, that is, to measure their linear dimensions with a ruler after pulling out the posts. This method has the highest accuracy for measuring the total length of posts, but the measurement of the buried depth is greatly affected by the subjective factors of different manual inspections due to the objective reason that there is no obvious dry-wet boundary in the part of the stratum where the posts are buried. At the same time, the post pulling inspection is time-consuming and labor-intensive, and it is easy to damage the integrity of the slope and roadbed and it is not easy to restore the construction site. It is highly destructive and affects traffic, and cannot be used as a means of daily inspection.

[0004] Therefore, it is necessary to provide a linear dimension measurement method and device for the total length of highway guardrail posts to solve the technical problems of the prior art that the underground buried depth and exposed height cannot be accurately judged, the road closure during inspection will affect the normal traffic on the highway, and there are safety hazards and low efficiency. Summary of the invention

[0005] The purpose of the present invention is to provide a linear dimension measurement method and device for the total length of highway guardrail posts, aiming to achieve accurate measurement of underground buried depth and exposed height, avoid road closures affecting normal highway traffic, and improve the safety and measurement efficiency of the execution process.

[0006] In order to solve the above technical problems, the present invention adopts the following solutions: A linear dimension measuring device for the total length of a highway guardrail column is deployed on a detection vehicle and close to one side of the highway guardrail column, comprising a ground penetrating radar measuring module, a 3D camera measuring module, a sensor module, a control module, a lower computer and a host computer; wherein, The control module is electrically connected to the ground penetrating radar measurement module, the 3D camera measurement module, the sensor module, and the lower machine, and obtains linear dimension measurement data by executing linear dimension measurement control; The sensor module is used to obtain sensor data of the inspection vehicle in real time, and the sensor data is used to trigger linear dimension measurement control; The 3D camera measurement module is used to measure the height of the column exposed on the ground, including: 3D camera, used to collect contour data of the exposed part of the column on the ground; An observation camera is used to collect image data of the exposed part of the column on the ground; The ground penetrating radar measurement module is used to measure the underground buried depth of the column, including: Ground penetrating radar, used to collect raw radar data from beneath the ground where the inspection vehicle is located; The lower computer is used to collect linear dimension measurement data and perform local processing on image data, including a ground penetrating radar acquisition module, a 3D camera acquisition module, an observation camera acquisition module and an observation camera processing module; The upper computer is electrically connected to the lower computer, including: The ground penetrating radar data processing module processes the original radar data to obtain the underground buried depth of the column; The 3D camera data processing module processes the contour data to obtain the height of the column exposed above the ground.

[0007] Furthermore, the sensor module includes: A distance sensor is used to obtain distance data of the driving direction of the detection vehicle; Trigger sensor: used to generate corresponding trigger signals according to the highway guardrail posts passed by the detection vehicle.

[0008] Furthermore, the ground penetrating radar metrology module is installed on the lower middle part of the inspection vehicle through a radar mounting bracket, and the 3D camera metrology module is installed on the upper middle part of the inspection vehicle through a camera mounting bracket; wherein the ground penetrating radar metrology module and the 3D camera metrology module are installed on the same vertical line.

[0009] On the other hand, a linear dimension measurement method for the total length of a highway guardrail column is provided, which is applied to the linear dimension measurement device as described above, and the linear dimension measurement of the total length of the highway guardrail column is performed through the following steps: Step 1: The detection vehicle drives along the road surface, and the sensor module continuously obtains the sensor data of the detection vehicle in real time and sends it to the control module; Step 2: When the linear dimension measurement control is triggered, the control module controls the ground penetrating radar measurement module and the 3D camera measurement module to perform the linear dimension measurement control respectively; Step 3: The control module completes the linear dimension measurement control, obtains the linear dimension measurement data and controls the corresponding module to send it to the lower computer; wherein the linear dimension measurement data includes contour data, image data and radar raw data; Step 4: The lower computer collects linear dimension measurement data and processes the image data locally; Step 5: The upper computer receives the contour data and radar raw data sent by the lower computer, and processes the data respectively to obtain the underground buried depth of the column and the height of the column exposed above the ground; Step 6: Repeat steps 1 to 5 to obtain the total length of each highway guardrail column passed by the inspection vehicle until the linear dimension measurement is stopped.

[0010] Furthermore, the control module performs linear dimension measurement control on the ground penetrating radar measurement module through the following steps: Control the ground penetrating radar to start at a preset center frequency, wavelength and scanning rate; The ground penetrating radar emits radar waves under the ground where the inspection vehicle is located; wherein the radar waves are radiation waves; The ground penetrating radar collects reflected waves and diffracted waves from the ground below the road; the reflected waves are obtained by the reflection of the strata, and the diffracted waves are generated by the diffraction points corresponding to the highway guardrail columns; The control module controls the ground penetrating radar to pack the reflected wave and the diffraction wave into the corresponding radar raw data and send it to the lower computer. The lower computer receives the radar raw data through the ground penetrating radar acquisition module.

[0011] Furthermore, the control module performs linear dimension measurement control on the 3D camera measurement module through the following steps: Adjust the inspection vehicle to the inspection position and control the observation camera to start; The image data is sent to the lower computer, and the lower computer receives the image data through the observation camera acquisition module; The lower computer processes the image data through the observation camera processing module, and infers and identifies whether there is a column cap in the preset area of ​​the image; If yes, start the 3D camera to obtain contour data; Otherwise, adjust the shooting angle until the column cap is located in the preset area in the image; The control module controls the 3D camera to send the contour data to the lower computer, and the lower computer receives the contour data through the 3D camera acquisition module.

[0012] Furthermore, the observation camera processing module identifies the column caps through a target detection model; wherein the target detection model is trained through a YOLOV8 network and deployed using a 16-bit inference engine of TensorRT.

[0013] Furthermore, the ground penetrating radar data processing module processes the radar raw data through the following steps: Preprocessing the raw radar data to obtain ground penetrating radar data; Analyze the stratum interface through reflected waves and obtain the number of stratum layers; Perform velocity fitting on radar waves of each layer to obtain electromagnetic wave velocity of each layer; Build a velocity model and perform time-to-depth conversion to convert the time domain of the velocity model into the depth domain; The specific parameter values ​​are extracted based on the ground penetrating radar data and substituted into the velocity model to solve the underground burial depth of the column.

[0014] Furthermore, the 3D camera data processing module processes the contour data through the following steps: Preprocessing the contour data and converting the contour data into contour image data; The contour image data is preprocessed, and the image to be analyzed is obtained by image filtering, binary threshold extraction, and removal of discrete points and fitting straight lines. Extract the contour lines that meet the requirements in the image to be analyzed as the road reference line and calculate the mapping relationship, and use the mapping relationship to map the image to be analyzed to the road coordinate system; According to the features of the column cap, the column cap contour is extracted from the image to be analyzed, and the corresponding column cap reference line is obtained by combining the spatial coordinate information of the contour data; The height of the column exposed above the ground is calculated through the spatial position information corresponding to the road surface baseline and the column cap baseline.

[0015] Furthermore, the mapping relationship between the 3D camera coordinate system and the road coordinate system is obtained through prior knowledge; wherein the prior knowledge is: The z-axis of the road coordinate system is the horizontal axis, perpendicular to the road direction; the x-axis of the road coordinate system is the vertical axis, perpendicular to the road surface; the y-axis of the road coordinate system is parallel to the road surface along the road direction; The z-axis of the 3D camera coordinate system is the extension line of the receiver optical axis of the 3D camera; the x-axis of the 3D camera coordinate system is perpendicular to the z-axis and points to the ground; the y-axis of the 3D camera coordinate system is parallel to the driving direction.

[0016] The linear dimension measuring method and device for the total length of highway guardrail columns provided by the present invention have the following beneficial effects: 1. The present invention realizes precise data synchronous acquisition through multi-module collaborative control. Through the core scheduling function of the control module, the operating timing of the ground penetrating radar and the 3D camera module is dynamically coordinated. Based on the real-time data of the sensor module, the relative position of the inspection vehicle and the column is accurately determined, and the ground penetrating radar is synchronously triggered to emit radar waves and the 3D camera is synchronously triggered to collect contour data, ensuring the temporal and spatial consistency of the underground burial depth and the exposed height. 2. The lower computer of the present invention combines AI image recognition technology to realize accurate collection of contour data; the lower computer transmits the radar raw data (reflected wave + diffraction wave) and 3D contour data (column cap space coordinates) to the upper computer, and the upper computer realizes data fusion through the layered velocity model (time-depth conversion) and the coordinate system mapping algorithm (3D→road coordinate system), and the total length measurement error is greatly improved in accuracy compared with the single module detection; 3. The present invention improves the measurement reliability through hierarchical control logic; ground penetrating radar control chain: preset radar parameters → transmit radiation waves → capture diffraction waves → data preprocessing → stratum interface analysis → velocity model fitting, to solve the calculation deviation of buried depth caused by the difference of electromagnetic wave velocity in multiple strata; 3D camera control chain: observation camera target detection → trigger 3D camera → contour data acquisition → road surface baseline extraction → coordinate system mapping → exposed height calculation, to achieve millimeter-level positioning accuracy of column caps under complex lighting conditions; 4. The present invention deeply couples hardware deployment with logic control. The ground penetrating radar and the 3D camera are installed vertically in alignment through a bracket. The control module calibrates the relative posture of the two in real time to ensure the spatial matching of the radar wave emission direction and the optical axis of the 3D camera, eliminating the coordination error caused by viewing angle deviation. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 A schematic diagram of the structure of a linear dimension measuring device provided by the present invention; Figure 2 A schematic diagram of the installation of the linear dimension measuring device provided by the present invention; Figure 3 A schematic diagram of the structure of the lower computer module provided by the present invention; Figure 4 A schematic diagram of the processing flow of the ground penetrating radar data processing module provided by the present invention; Figure 5 A schematic diagram of a single formation model provided by the present invention; Figure 6 A schematic diagram of a multi-stratum model calculation scenario provided by the present invention; Figure 7 A schematic diagram of the calculation process of the exposed height of the column provided by the present invention; Figure 8 A schematic diagram of a scenario for calculating the exposed height of a column provided by the present invention. DETAILED DESCRIPTION

[0018] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present invention and its application or use. 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.

[0019] The relative arrangement of components and steps, the numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present invention unless specifically stated otherwise.

[0020] At the same time, it should be understood that for the convenience of description, the sizes of the various parts shown in the drawings are not drawn according to the actual proportional relationship.

[0021] Additionally, descriptions of well-known structures, functions, and configurations may be omitted for clarity and conciseness.One of ordinary skill in the art will recognize that various changes and modifications may be made to the examples described herein without departing from the spirit and scope of the present disclosure.

[0022] Technologies, methods, and apparatus known to ordinary technicians in the relevant field may not be discussed in detail, but where appropriate, such technologies, methods, and apparatus should be considered part of the authorization specification.

[0023] In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limiting. Therefore, other examples of the exemplary embodiments may have different values.

[0024] The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with embodiments: Example 1 See also Figure 1 This embodiment provides a linear dimension measuring device for the total length of highway guardrail columns, which is mainly composed of a ground penetrating radar measuring module, a 3D camera measuring module, a sensor module, a control module, a lower computer and a host computer, and is Figure 2 The installation method shown is deployed on the detection vehicle and close to the side of the highway guardrail post.

[0025] In order to accurately determine the underground burial depth and exposed height, the present application requires the control module to cooperate with the ground penetrating radar measurement module and the 3D camera measurement module to collect corresponding data information respectively; wherein, the control module is composed of a single-chip microcomputer and necessary peripheral circuits, and is mainly used to perform linear dimension measurement control, thereby obtaining linear dimension measurement data, and controlling the corresponding module to send it to the lower computer for further processing.

[0026] Linear dimension measurement includes triggering process and control process. In the triggering process: the sensor module obtains the sensor data of the inspection vehicle in real time, and the control module determines whether to trigger the linear dimension measurement control according to the sensor data; when executing the control process, the control module needs to coordinate with the ground penetrating radar measurement module, 3D camera measurement module and lower computer for processing.

[0027] The sensor module is mainly composed of a distance sensor and a trigger sensor. The distance sensor can be set up with a photoelectric encoder as the core and installed on the wheel hub of the inspection vehicle. It can accurately obtain the mileage of the inspection vehicle and perform calibration before use, that is, to match the actual distance traveled by the wheel with the number of pulses sent by the distance sensor.

[0028] Calibration operation: First determine the distance to be calibrated, mark the starting point and the end point on a straight road, start the distance sensor counting when the inspection vehicle passes the starting point, and stop counting when the inspection vehicle passes the end point mark. Repeat the measurement several times, and record the average value of the calibration distance and pulse count. The distance sensor will send a pulse signal to the control module every time it follows the wheel for a certain distance.

[0029] The trigger sensor uses a reflective laser sensor, which can be set to output a trigger signal when the object being measured is within a certain distance range to avoid false triggering by objects that are too close or too far; the trigger sensor can measure the distance from the pillar to the vehicle body, and can be used to correct the horizontal distance from the ground-penetrating mine to the surface of the pillar to reduce the error; the trigger sensor is installed on the lower part of the vehicle body, and the specific height can be adjusted according to actual road conditions.

[0030] The ground penetrating radar metrology module is installed in the lower middle part of the inspection vehicle through the radar mounting bracket. The radar mounting bracket can adjust the height of the ground penetrating radar from the ground, the horizontal distance from the guardrail column, and the inclination of the radar and the ground. The 3D camera metrology module is installed in the upper middle part of the inspection vehicle through the camera mounting bracket and is installed on the same vertical line as the ground penetrating radar metrology module. According to specific inspection requirements, the two inspection modules can be installed on any side or both sides of the inspection vehicle.

[0031] In specific implementation, the inspection vehicle can be a modified ordinary medium or large vehicle. The control module, the lower computer, and the upper computer are installed inside the inspection vehicle. The inspection vehicle can be driven to the corresponding road position according to the inspection requirements, so that the device has the advantages of flexible deployment and convenient transportation. During the inspection, the inspection vehicle only needs to be parked at the corresponding position. There is no need to occupy the road or close the road, and it will not affect the normal traffic on the highway. There is no need to get off the vehicle, thereby improving the safety of the execution process.

[0032] The ground penetrating radar metering module is composed of a ground penetrating radar and its related supporting components. The ground penetrating radar is fixed to the middle and rear part of the vehicle body through a connecting device to collect radar raw data from the ground under the road where the inspection vehicle is located. During the collection process, the ground penetrating radar slides along the ground to ensure that the horizontal distance with the column is basically consistent. The ground penetrating radar and the lower computer use wireless communication protocol to transmit data, which expands the convenience and operability of the ground penetrating radar. The transmission is stable and reliable, and at the same time avoids frequent plugging and unplugging of wired connections. The lower computer can display and store radar data in real time.

[0033] The 3D camera metrology module includes a 3D camera and an observation camera; the observation camera is an ordinary monocular camera, and the 3D camera is set up based on laser emission and receiver; when collecting data, the observation camera detects whether there are pillars in the image through the lower computer observation camera processing module, and can provide a basis for manual review; the 3D camera projects the laser emitted by the laser onto the surface of the object to be measured, and captures the position of the reflected laser through the receiver to realize contour data collection.

[0034] like Figure 3 As shown, the lower computer integrates a ground penetrating radar acquisition module, a 3D camera acquisition module, an observation camera acquisition module and an observation camera processing module; data is transmitted between the lower computer and the upper computer by wireless or wired means; among them, the observation camera processing module is specifically a deep learning target recognition program; the upper computer is equipped with a ground penetrating radar data processing module and a 3D camera data processing module, which are used to analyze and process the data obtained from the lower computer and obtain results; of course, if the computer performance is sufficient, the upper computer and the lower computer can be implemented on one computer.

[0035] Example 2 Based on the above-mentioned embodiment 1, this embodiment measures the linear dimension of the total length of the highway guardrail column through the following steps: Step 1: The detection vehicle drives along the road surface, and the sensor module continuously obtains the sensor data of the detection vehicle in real time and sends it to the control module; Step 2: When the linear dimension measurement control is triggered, the control module controls the ground penetrating radar measurement module and the 3D camera measurement module to perform the linear dimension measurement control respectively; Step 3: The control module completes the linear dimension measurement control, obtains the linear dimension measurement data and controls the corresponding module to send it to the lower computer; wherein the linear dimension measurement data includes contour data, image data and radar raw data; Step 4: The lower computer collects linear dimension measurement data and processes the image data locally; Step 5: The upper computer receives the contour data and radar raw data sent by the lower computer, and processes the data respectively to obtain the underground buried depth of the column and the height of the column exposed above the ground; Step 6: Repeat steps 1 to 5 to obtain the total length of each highway guardrail column passed by the inspection vehicle until the linear dimension measurement is stopped.

[0036] It should be noted that: in order to accurately determine the underground burial depth and the exposed height, this embodiment makes detailed settings for the control logic of each link, aiming to coordinate the corresponding module to accurately obtain the corresponding data according to the actual situation, and control the upper computer and the lower computer to process the collected data in an orderly manner, thereby obtaining the total length of the highway guardrail column. The control processing steps of each link are explained in detail below.

[0037] The control module performs linear dimension measurement control on the ground penetrating radar measurement module through the following steps: Control the ground penetrating radar to start at a preset center frequency, wavelength and scanning rate; The ground penetrating radar emits radar waves under the ground where the inspection vehicle is located; wherein the radar waves are radiation waves; The ground penetrating radar collects reflected waves and diffracted waves from the ground below the road; the reflected waves are obtained by the reflection of the strata, and the diffracted waves are generated by the diffraction points corresponding to the highway guardrail columns; The control module controls the ground penetrating radar to pack the reflected wave and the diffraction wave into the corresponding radar raw data and send it to the lower computer. The lower computer receives the radar raw data through the ground penetrating radar acquisition module.

[0038] In a specific embodiment, the center frequency of the ground penetrating radar used is 200MHZ, the wavelength is about 1.5 meters, the detection depth can reach up to 15 meters, and the scanning rate can reach 1000 scans / second; during on-site detection, the ground penetrating radar is placed on a bracket connected to the inspection vehicle, close to the ground, and moves along the direction of column arrangement on the road surface next to the column, that is, the direction of road travel. The control module triggers data collection through the distance sensor to obtain radar data under the road surface.

[0039] The radiation beam of the ground penetrating radar antenna has a certain width. Therefore, the ground penetrating radar can not only detect the target directly below the antenna, but also detect the target within a certain range that deviates from the directly below. By using the beam width of the ground penetrating radar, the side target detection can not only detect the surface structure characteristics directly below the instrument, but also detect the bottom signal of the side column. Among them, the diffraction wave generated when the radar wave encounters the bottom of the column is the key signal for detecting the buried depth of the column. The present invention simultaneously uses the reflected waves from each layer interface and the diffraction waves from each diffraction point to distinguish the strata and calculate the buried depth of the column.

[0040] Among them, electromagnetic scattering occurs when radar waves encounter a target. When the target is much larger than the wavelength, the effect of the wave is called reflection, which is a special case of scattering. When the target is less than or equal to the wavelength, diffraction occurs. Radar waves are reflected when encountering layer interfaces. Diffraction occurs when encountering diffraction points. This scheme uses the diffraction signal generated when the radar wave reaches the bottom of the column to detect the target, and then obtain the accurate position of the bottom of the column. The radar raw data also contains the reflection signal of each interface and the diffraction signal of each diffraction point.

[0041] like Figure 4 As shown, the ground penetrating radar data processing module further processes the raw radar data; which includes: The raw radar data is preprocessed to obtain ground penetrating radar data; wherein the data preprocessing includes: removing direct waves, removing DC components, gain, filtering, removing background, etc.

[0042] Remove direct waves. The transmitting antenna is very close to the receiving antenna. The energy of the transmitting antenna reaches the receiving antenna directly without being reflected by the underground target. The received signal is called a direct wave. Ground penetrating radar data generally has strong direct waves. Direct waves are one of the main sources of interference to ground penetrating radar. The intensity of direct waves may be greater than the target echo amplitude. Therefore, it is necessary to remove the strong direct waves first. The mean method is relatively simple to implement. The average value of all channels is calculated, and then this average value is subtracted from each channel.

[0043] To remove the DC component, a normal data fluctuates around zero, but the instability of electronic devices during the detection process causes the data to deviate from zero. The waveform needs to be corrected to ensure that the average value of each data item is close to zero. The method is to accumulate and sum each data channel, then divide it by the number of sampling points of each channel to obtain the mean value, and then subtract the mean value from each data point of the channel to obtain the data after removing the DC component.

[0044] The calculation formula is: For the corrected data, is the data before correction, is the number of paths, For the time window, is the number of sampling points per channel, Iterate over variables for summation.

[0045] Gain: Electromagnetic waves decay quickly underground, resulting in a decrease in the amplitude of the reflected echo. This attenuation may make it impossible to accurately identify the target. The gain method is used to restore the waveform amplitude, amplify the amplitude of the attenuated part of the signal, observe the waveform more clearly, and optimize signal visibility.

[0046] Filtering: Ground penetrating radar data is affected by complex underground media and external signal interference, and often contains noise, so it is necessary to effectively suppress noise, and mean filtering or median filtering is commonly used. FIRBPF (Finite Impulse Response Bandpass Filter) is used to selectively retain or remove signal components in a specific frequency range during signal processing. It allows signals within a specific frequency range to pass, while preventing signals below or above this range from passing.

[0047] The stratum interface is analyzed through reflected waves to obtain the number of stratum layers. When the radar wave encounters the layer interface, it will be reflected. Its characteristic in the radar image is a straight line dividing light and dark, which can easily determine the number of stratum layers.

[0048] The velocity of the radar waves in each layer is fitted to obtain the electromagnetic wave velocity in each layer; the velocity of electromagnetic waves in different layers is different, and the hyperbolic characteristics formed by diffraction when encountering underground targets are also different. The image feature formed by the diffraction of electromagnetic waves encountering underground columns is a hyperbola. The characteristic curve in the radar profile can be expressed by the center of the hyperbola ( ) at a point in the image plane: Among them, a is the semi-real axis length and b is the semi-imaginary axis length.

[0049] The hyperbola fitting method is used to fit the electromagnetic wave velocity of different strata. This is a fast method. The Gauss-Newton fitting method is used to fit the hyperbola to obtain the characteristic parameters of the hyperbola. Since the electromagnetic wave velocity of different strata is only related to the eccentricity of the hyperbola, the characteristic parameters of the hyperbola can be obtained by fitting the hyperbola to calculate the electromagnetic wave velocity of the current stratum.

[0050] by Figure 5 Taking the single-stratum model shown as an example, there is an equation: Converted to general hyperbolic form: , whose focus is in the vertical direction, in, is the distance between the radar and the bottom of the column, is the current formation electromagnetic wave velocity, is the shortest time of diffraction wave at the bottom of the column, is the horizontal distance between the radar and the column, The buried depth of guardrail posts.

[0051] It can be seen that , , the eccentricity of the hyperbola can be calculated as ,in, is the semi-real axis length, is the semi-imaginary axis length.

[0052] Build a velocity model and perform time-depth conversion to convert the time domain of the velocity model into the depth domain; for further explanation without loss of generality, combine the following Figure 6 In the multi-stratum model calculation scenario shown in the figure, the road underground is a conventional three-layer structure. In addition to the direct wave, the radar also receives the diffraction wave at the intersection of the column and the layer interface, the diffraction wave at the bottom of the column, and the reflection wave of the interface. The phase axis composed of the direct wave and the stratum reflection wave is distributed in a straight line, and each diffraction wave is distributed in a hyperbolic manner. The relationship between the various parameters can be expressed as: in, ——The stratum is 1 layer thick, ——The stratum is 2 layers thick, ——Deepness of column embedment, ——The shortest time of diffraction waves at the bottom of the column, ——arrival time of the first interface reflection wave, ——arrival time of the reflected wave at the second interface, ——the layer velocity of layer 1, ——the layer velocity of layer 2, ——the layer velocity of layer 3, ——The horizontal distance between the radar and the column, ——the incident angle of the radar wave in the layer 1, ——the refraction angle / incident angle of the radar wave in layer 2, ——The refraction angle of radar waves in layer 3.

[0053] Among them, speed , , The arrival time is obtained by velocity fitting. , , It is obtained through radar images, D is obtained through measurement, and is calculated by the formula , , , , Then, through Determine the buried depth of the pillars.

[0054] Tilt correction: In some complex road conditions, detection is difficult. The radar can be installed at an angle to increase the radiation energy of the antenna toward the bottom of the column. In this case, the final burial depth result needs to be tilted.

[0055] The correction equation is: in, is the actual buried depth of the column, is the measured buried depth of the column, is the horizontal distance between the ground penetrating radar and the column.

[0056] Specific parameter values ​​are extracted based on the ground penetrating radar data and substituted into the velocity model for solution, thus completing the measurement of the underground buried depth of the column.

[0057] On the other hand, the control module performs linear dimension measurement control on the 3D camera measurement module through the following steps: Adjust the inspection vehicle to the inspection position and control the observation camera to start; The image data is sent to the lower computer, and the lower computer receives the image data through the observation camera acquisition module; The lower computer processes the image data through the observation camera processing module, and infers and identifies whether there is a column cap in the preset area of ​​the image; If yes, start the 3D camera to obtain contour data; Otherwise, adjust the shooting angle until the column cap is located in the preset area in the image; The control module controls the 3D camera to send the contour data to the lower computer, and the lower computer receives the contour data through the 3D camera acquisition module.

[0058] In the specific implementation, the inspection vehicle drives on the road to be inspected, and the observation camera and distance sensor start working first. The observation camera continuously collects images, and the observation camera processing module of the lower computer, that is, the deep learning target detection algorithm, identifies whether there is a pillar in the preset area of ​​the current image.

[0059] The trigger sensor detects the existence of the column and is within the preset distance, and sends a signal to the control module, which then communicates with the lower computer to report that the 3D camera can be triggered to shoot. The observation camera processing module uses the YOLOV8 deep learning target detection program and the TensorRT 16-bit inference engine to deploy inference and quickly identify whether there is a column cap in the image.

[0060] The process of using the YOLOV8 network to identify column caps is as follows: First, we obtain a large number of images of various column caps collected by observation cameras, and after data enhancement, data balancing, data cleaning and other operations, we label them according to unified specifications to ensure the consistency, completeness and accuracy of the labels. We use the YOLOV8 network training to obtain the target detection model, and deploy the target detection model using the TensorRT 16-bit inference engine.

[0061] During the actual detection, the image collected by the observation camera is input into the YOLOV8 target detection network, and the pre-trained target detection model is used to select the target in combination with the preset detection target label category, confidence and other parameters to obtain the anchor frame of the column cap, calculate and extract the horizontal and vertical coordinates and area of ​​the area where the anchor frame is located, and combine the recognition scheme for the column to perform target detection; Among them, A feasible solution is provided for the identification of columns: The distance between columns on the road is generally fixed at 1 meter, 2 meters or 4 meters. In addition to identifying the column caps, the driving distance of the inspection vehicle passing two adjacent columns is further compared with the fixed distance between the columns to more accurately determine the position of the columns. For example, the distance between adjacent columns on the road being inspected is 4 meters. After the first column triggers the detection, the driving distance of the inspection vehicle from the current column to the next column is recorded, and this driving distance is compared with the fixed distance between the columns. If it is within the error range, the comparison is successful. Combined with the column cap image recognition, it is accurately determined whether there is a column. Compare whether the column cap anchor frame is in the ROI of the preset observation camera. If the anchor frame is in the preset ROI and the driving distance is successfully compared with the fixed distance between the columns, it is determined that the 3D camera can be triggered to shoot at this moment. If it does not meet the requirements, the next image is detected.

[0062] Another feasible solution is provided for the identification of columns: The column is installed behind the guardrail, and the special cross-sectional contour shape of the column and the guardrail is deeply learned to determine whether there is a column. Specifically, guardrails generally have double waves and triple waves, and the contours composed of the exposed parts of the same type of guardrail and column are consistent and universal. The cross-sectional contour shape characteristics of different types of guardrails and columns are different. The 3D camera captures the complete column and guardrail contour information, and after a series of processing, data screening, data cleaning, and YOLO8 network training, the target model is obtained. The target model is used to identify whether there is a column in the preset area of ​​the current observation camera.

[0063] The lower computer comprehensively observes the detection results of the camera image and the state of the trigger sensor. When both conditions are met, after a specific distance delay between the distance sensor and the 3D module, the control module controls the 3D camera to continuously shoot and collect multiple sets of data to ensure that the entire column cap is fully collected. The horizontal physical distance between the observation camera and the 3D camera is very small. Even at a faster vehicle speed, the trigger delay is very small and can be regarded as a real-time trigger.

[0064] After receiving the 3D profile data of the current column, the lower computer saves the data and transmits it to the upper computer for analysis and processing. The lower computer has a data acquisition module that collects and displays the data uploaded by the ground penetrating radar, 3D camera, and observation camera in real time. Data analysis and processing can be performed offline or online in real time. The data saved by the lower computer can be read offline for analysis and processing to obtain the results, or the data forwarded by the lower computer can be obtained in real time, analyzed and processed online, and the processing results can be given.

[0065] The 3D camera processing module in the host computer is used to load raw data, process data, export data and modify detection parameters. Figure 7 , the specific process of data analysis and processing is Preprocessing the contour data and converting the contour data into contour image data; The contour image data is preprocessed, and the image to be analyzed is obtained by image filtering, binary threshold extraction, and removal of discrete points and fitting straight lines. Extracting the road surface reference line according to the road surface characteristics; specifically: extracting the contour line that meets the requirements in the image to be analyzed as the road surface reference line and calculating the mapping relationship, and then mapping the image to be analyzed to the road coordinate system using the mapping relationship; According to the features of the column cap, the column cap contour is extracted from the image to be analyzed, and the corresponding column cap reference line is obtained by combining the spatial coordinate information of the contour data; The height of the column exposed above the ground is calculated through the spatial position information corresponding to the road surface baseline and the column cap baseline.

[0066] In the image to be analyzed, the contour lines that are parallel to each other and meet a certain distance interval are first extracted, and then the road surface baseline and column cap baseline are extracted respectively according to their length, spatial distribution and other characteristic differences.

[0067] The basis for extracting contour lines that meet the requirements is that the road surface baseline and the column cap baseline are parallel straight line segments with fixed lengths, and the road surface baseline is longer than the column cap baseline. The geometric parameters of the road surface baseline are obtained, and the mapping relationship between the 3D camera coordinate system and the road coordinate system is obtained through prior knowledge. The image to be analyzed is mapped to the road coordinate system using the mapping relationship.

[0068] The prior knowledge is: The z-axis of the road coordinate system is the horizontal axis, perpendicular to the road direction; the x-axis of the road coordinate system is the vertical axis, perpendicular to the road surface; the y-axis of the road coordinate system is parallel to the road surface along the road direction; The z-axis of the 3D camera coordinate system is the extension line of the receiver optical axis of the 3D camera; the x-axis of the 3D camera coordinate system is perpendicular to the z-axis and points to the ground; the y-axis of the 3D camera coordinate system is parallel to the driving direction.

[0069] The laser profile data contains the spatial coordinate information of each data point. The height of the column cap from the road surface is calculated by using the spatial position information corresponding to the extracted road surface baseline and the column cap baseline.

[0070] like Figure 8 As shown in the figure, the distance between any point A on the column cap and any point B on the road surface is the exposed height of the column: The coordinates of point A are , the coordinates of point B are .

[0071] Multiple sets of contour data are collected for one column. Each set of contour data can calculate an exposed height result. The average height of the multiple sets of contour data is calculated as the final exposed height data.

[0072] Every time the inspection vehicle passes by a column, it will collect the underground and ground data of the current column at the same time. After the above steps in this article, the buried depth and exposed height of the column are obtained respectively, and then the upper computer software adds them together to obtain the overall length of the current column.

[0073] In summary, in addition, the present application can not only measure highway guardrail posts, but also measure the linear dimensions of other "semi-hidden" or "partially hidden" objects.

[0074] In summary, the present invention constructs a dual-modal data fusion measurement system of underground burial depth and ground exposure height by controlling the coordinated scheduling of the ground penetrating radar and the 3D camera module by the control module: Precise control logic: Based on real-time sensor feedback, dynamic triggering of multi-module synchronous acquisition, combined with the layered velocity model and spatial coordinate system mapping algorithm, the total length measurement error is greatly reduced, breaking through the bottleneck of the traditional column pulling method restricted by subjective factors.

[0075] Deep coupling of hardware and algorithms: The vertical installation structure and dynamic parameter calibration mechanism ensure the spatial consistency of multiple modules. Combined with YOLOv8 target detection and TensorRT accelerated reasoning, millisecond-level positioning and millimeter-level accuracy of column caps can be achieved under complex road conditions.

[0076] Engineering practical value: The non-contact detection solution greatly reduces the time spent on single-column detection, providing efficient and reliable technical support for highway guardrail safety inspections.

[0077] The present invention combines method innovation with engineering feasibility, and provides a standardized solution for the field of total length measurement of highway guardrail posts.

[0078] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. According to the technical essence of the present invention, within the spirit and principles of the present invention, any simple modification, equivalent replacement and improvement made to the above embodiment still falls within the protection scope of the technical solution of the present invention.

Claims

1. A linear dimension measuring device for the total length of a highway guardrail column, deployed on a detection vehicle and close to one side of the highway guardrail column, characterized in that: It includes ground penetrating radar measurement module, 3D camera measurement module, sensor module, control module, lower computer and upper computer; among them, The control module is electrically connected to the ground penetrating radar measurement module, the 3D camera measurement module, the sensor module, and the lower machine, and obtains linear dimension measurement data by executing linear dimension measurement control; The sensor module is used to obtain sensor data of the inspection vehicle in real time, and the sensor data is used to trigger linear dimension measurement control; The 3D camera measurement module is used to measure the height of the column exposed on the ground, including: 3D camera, used to collect contour data of the exposed part of the column on the ground; An observation camera is used to collect image data of the exposed part of the column on the ground; The ground penetrating radar measurement module is used to measure the underground buried depth of the column, including: Ground penetrating radar, used to collect raw radar data from beneath the ground where the inspection vehicle is located; The lower computer is used to collect linear dimension measurement data and perform local processing on image data, including a ground penetrating radar acquisition module, a 3D camera acquisition module, an observation camera acquisition module and an observation camera processing module; The upper computer is electrically connected to the lower computer, including: The ground penetrating radar data processing module processes the original radar data to obtain the underground buried depth of the column; The 3D camera data processing module processes the contour data to obtain the height of the column exposed above the ground.

2. A linear dimension measuring device for the total length of a highway guardrail column according to claim 1, characterized in that: The sensor module comprises: A distance sensor is used to obtain distance data of the driving direction of the detection vehicle; Trigger sensor: used to generate corresponding trigger signals according to the highway guardrail posts passed by the detection vehicle.

3. A linear dimension measuring device for the total length of a highway guardrail column according to claim 1, characterized in that: The ground penetrating radar metrology module is installed at the lower middle part of the inspection vehicle through a radar mounting bracket, and the 3D camera metrology module is installed at the upper middle part of the inspection vehicle through a camera mounting bracket; wherein the ground penetrating radar metrology module and the 3D camera metrology module are installed on the same vertical line.

4. A linear dimension measuring method for the total length of a highway guardrail column, applied to a linear dimension measuring device as claimed in any one of claims 1 to 3, characterized in that: The linear dimension measurement of the total length of highway guardrail posts is carried out through the following steps: Step 1: The detection vehicle drives along the road surface, and the sensor module continuously obtains the sensor data of the detection vehicle in real time and sends it to the control module; Step 2: When the linear dimension measurement control is triggered, the control module controls the ground penetrating radar measurement module and the 3D camera measurement module to perform the linear dimension measurement control respectively; Step 3: The control module completes the linear dimension measurement control, obtains the linear dimension measurement data and controls the corresponding module to send it to the lower computer; wherein the linear dimension measurement data includes contour data, image data and radar raw data; Step 4: The lower computer collects linear dimension measurement data and processes the image data locally; Step 5: The upper computer receives the contour data and radar raw data sent by the lower computer, and processes the data respectively to obtain the underground buried depth of the column and the height of the column exposed above the ground; Step 6: Repeat steps 1 to 5 to obtain the total length of each highway guardrail column passed by the inspection vehicle until the linear dimension measurement is stopped.

5. A linear dimension measurement method for the total length of a highway guardrail column according to claim 4, characterized in that: The control module performs linear dimension measurement control on the ground penetrating radar measurement module through the following steps: Control the ground penetrating radar to start at a preset center frequency, wavelength and scanning rate; The ground penetrating radar emits radar waves under the ground where the inspection vehicle is located; wherein the radar waves are radiation waves; The ground penetrating radar collects reflected waves and diffracted waves from the ground below the road; the reflected waves are obtained by the reflection of the strata, and the diffracted waves are generated by the diffraction points corresponding to the highway guardrail columns; The control module controls the ground penetrating radar to pack the reflected wave and the diffraction wave into the corresponding radar raw data and send it to the lower computer. The lower computer receives the radar raw data through the ground penetrating radar acquisition module.

6. A linear dimension measurement method for the total length of a highway guardrail column according to claim 4, characterized in that: The control module performs linear dimension measurement control on the 3D camera measurement module through the following steps: Adjust the inspection vehicle to the inspection position and control the observation camera to start; The image data is sent to the lower computer, and the lower computer receives the image data through the observation camera acquisition module; The lower computer processes the image data through the observation camera processing module, and infers and identifies whether there is a column cap in the preset area of ​​the image; If yes, start the 3D camera to obtain contour data; Otherwise, adjust the shooting angle until the column cap is located in the preset area in the image; The control module controls the 3D camera to send the contour data to the lower computer, and the lower computer receives the contour data through the 3D camera acquisition module.

7. A linear dimension measurement method for the total length of a highway guardrail column according to claim 6, characterized in that: The observation camera processing module identifies the column cap through a target detection model; wherein the target detection model is trained through a YOLOV8 network and deployed using a 16-bit inference engine of TensorRT.

8. A linear dimension measurement method for the total length of a highway guardrail column according to claim 5, characterized in that: The ground penetrating radar data processing module processes the radar raw data through the following steps: Preprocessing the raw radar data to obtain ground penetrating radar data; Analyze the stratum interface through reflected waves and obtain the number of stratum layers; Perform velocity fitting on radar waves of each layer to obtain electromagnetic wave velocity of each layer; Build a velocity model and perform time-to-depth conversion to convert the time domain of the velocity model into the depth domain; The specific parameter values ​​are extracted based on the ground penetrating radar data and substituted into the velocity model to solve the underground burial depth of the column.

9. A linear dimension measurement method for the total length of a highway guardrail column according to claim 6, characterized in that: The 3D camera data processing module processes the contour data by the following steps: Preprocessing the contour data and converting the contour data into contour image data; The contour image data is preprocessed, and the image to be analyzed is obtained by image filtering, binary threshold extraction, and removal of discrete points and fitting straight lines. Extract the contour lines that meet the requirements in the image to be analyzed as the road reference line and calculate the mapping relationship, and use the mapping relationship to map the image to be analyzed to the road coordinate system; According to the features of the column cap, the column cap contour is extracted from the image to be analyzed, and the corresponding column cap reference line is obtained by combining the spatial coordinate information of the contour data; The height of the column exposed above the ground is calculated through the spatial position information corresponding to the road surface baseline and the column cap baseline.

10. A linear dimension measurement method for the total length of a highway guardrail column according to claim 9, characterized in that: The mapping relationship between the 3D camera coordinate system and the road coordinate system is obtained through prior knowledge; wherein the prior knowledge is: The z-axis of the road coordinate system is the horizontal axis, perpendicular to the road direction; the x-axis of the road coordinate system is the vertical axis, perpendicular to the road surface; the y-axis of the road coordinate system is parallel to the road surface along the road direction; The z-axis of the 3D camera coordinate system is the extension line of the receiver optical axis of the 3D camera; the x-axis of the 3D camera coordinate system is perpendicular to the z-axis and points to the ground; the y-axis of the 3D camera coordinate system is parallel to the driving direction.

Images