Tunnel imaging detection device and tunnel detection method

Abstract

The present disclosure provides a tunnel imaging detection device and a tunnel detection method, and relates to the technical field of tunnel detection. The device comprises a tunnel detection vehicle and two or more tunnel imaging detection modules. Each of the tunnel imaging detection modules comprises at least two linear array scanning units and a ranging unit arranged on each of the linear array scanning units. Each of the linear array scanning units is arranged in a circumferential distribution manner on an image acquisition surface of the tunnel imaging detection module, so that each of the linear array scanning units corresponds to a different area of the inner wall of the tunnel. In a high-speed detection scene of the tunnel, the tunnel imaging detection device can self-adaptively select a target tunnel imaging detection module and perform image acquisition, so that high-definition images of the inner wall of the tunnel can be acquired in the high-speed detection process, thereby providing a solid foundation for subsequent tunnel detection.

Description

Technical Field

[0001] This disclosure relates to the field of tunnel inspection technology, and in particular to a tunnel imaging inspection device and a tunnel inspection method. Background Technology

[0002] Existing tunnel appearance inspection projects primarily utilize 2D linear scan cameras for imaging. In practical applications, due to the diverse types of tunnels and their often large internal diameters (5m or more), a significant depth of field is required for clear imaging. Under the same conditions, a large depth of field necessitates a smaller aperture for the camera lens, resulting in a darker image. Furthermore, the maximum exposure time for a single acquisition cannot exceed the reciprocal of the sampling frequency (a single sampling period). Since the sampling frequency is related to vehicle speed, higher speeds require a faster sampling frequency, which reduces the maximum settable exposure time. Therefore, during high-speed tunnel inspections, the camera cannot increase image brightness by increasing exposure, severely limiting the final imaging quality. Thus, improving imaging performance during high-speed tunnel inspections has become a pressing technical problem for those skilled in the art. Summary of the Invention

[0003] In view of this, this disclosure proposes a tunnel imaging detection device and a tunnel detection method that can improve the clarity of imaging in high-speed tunnel detection scenarios.

[0004] According to a first aspect of this disclosure, a tunnel imaging detection apparatus is provided, comprising: The tunnel inspection vehicle and two or more tunnel imaging detection modules are configured to be installed on the vehicle body of the tunnel inspection vehicle in an array, and when the tunnel imaging detection modules are installed on the vehicle body of the tunnel inspection vehicle, the image acquisition surface of each tunnel imaging detection module faces the inner wall of the tunnel to be inspected, so as to realize the imaging detection of the inner wall of the tunnel. Each of the tunnel imaging detection modules includes: at least two linear array scanning units and a ranging unit arranged on each of the linear array scanning units, and each of the linear array scanning units is arranged in a circular distribution on the image acquisition surface of the tunnel imaging detection module so that each linear array scanning unit corresponds to a different area of ​​the tunnel inner wall. Each of the aforementioned ranging units is used to, upon receiving a ranging command, respond to the ranging command to measure the distance between the image acquisition surface of the tunnel imaging detection module and the inner wall of the tunnel; Each of the linear array scanning units is used to acquire images of the tunnel inner wall according to the received image acquisition command after receiving the image acquisition command, to obtain a detection image of the tunnel inner wall, so as to detect the tunnel inner wall to be detected according to the detection image; The tunnel imaging detection module that currently receives the image acquisition command is a tunnel imaging detection module selected from at least two tunnel imaging detection modules based on the distance between the image acquisition surface of each tunnel imaging detection module and the inner wall of the tunnel.

[0005] In one possible implementation, the device further includes a control unit, which is connected to each of the tunnel imaging detection modules respectively; For each of the tunnel imaging detection modules, the control unit is configured to send the ranging command to each of the ranging units of the tunnel imaging detection module, receive and select one tunnel imaging detection module from at least two tunnel imaging detection modules based on the distance between the image acquisition surface of the tunnel imaging detection module and the inner wall of the tunnel measured by each of the ranging units, and send image acquisition commands to each linear scan unit of the selected tunnel imaging detection module to control it to acquire images of the inner wall of the tunnel and obtain a detection image of the inner wall of the tunnel.

[0006] In one possible implementation, each of the linear scanning units includes a linear scanning camera and a laser light source, wherein the linear scanning camera and the laser light source are arranged adjacent to each other, and the lens of the linear scanning camera and the lens of the laser light source are located on the same plane. The linear scan camera in each of the linear scan units is directly connected to the control unit to receive and perform image acquisition according to the image acquisition command sent by the control unit; The tunnel imaging detection module also includes lasers corresponding to each of the linear array scanning units. The laser source in each of the linear array scanning units is connected to the control unit through the corresponding laser to receive and supplement the image acquisition process of the linear array scanning camera in the same linear array scanning unit according to the supplementary lighting command sent by the control unit.

[0007] In one possible implementation, the linear scan camera of each of the linear scan units is a high-resolution, high-speed linear scan camera.

[0008] In one possible implementation, the measuring axes of each ranging unit of each tunnel imaging detection module intersect at a point in opposite directions.

[0009] In one possible implementation, each of the tunnel imaging detection modules includes a power supply connector to connect to an external power source and provide a stable operating voltage for each of the tunnel imaging detection modules.

[0010] According to a second aspect of this disclosure, a tunnel imaging detection method is provided, comprising: the method being implemented based on the tunnel imaging detection apparatus described in any one of the first aspects of this disclosure, including: A ranging command is sent to each ranging unit of each tunnel imaging detection module, so that each ranging unit of each tunnel imaging detection module, upon receiving the ranging command, responds to the ranging command to measure the distance between the image acquisition surface of the tunnel imaging detection module and the inner wall of the tunnel. The system receives and selects one tunnel imaging detection module from at least two tunnel imaging detection modules as the target tunnel imaging detection module based on the distance between the image acquisition surface of each tunnel imaging detection module and the inner wall of the tunnel. Then, it sends an image acquisition command to each linear scan unit of the target tunnel imaging detection module so that each linear scan unit can acquire an image of the inner wall of the tunnel. The system receives and generates a panoramic detection image of the tunnel inner wall based on the detection images acquired by each of the linear array scanning units in the target tunnel imaging detection module, so as to detect the inner wall of the tunnel to be detected based on the panoramic detection image.

[0011] In one possible implementation, when selecting one tunnel imaging detection module from at least two tunnel imaging detection modules as the target tunnel imaging detection module, the switching is based on a preset switching threshold and switching rules for each of the tunnel detection modules.

[0012] In one possible implementation, prior to performing the tunnel imaging detection method, the method further includes: The profile of the tunnel to be detected and the relative positions of each tunnel imaging detection module to the profile during the detection process are obtained; Based on the profile and the relative position, determine the maximum and minimum distances between each tunnel imaging detection module and the tunnel inner wall during the detection process; Based on the maximum and minimum distances between each tunnel imaging detection module and the tunnel inner wall, the focus position of each linear array scanning unit in each tunnel imaging detection module is adjusted.

[0013] In one possible implementation, the method further includes: Based on the maximum and minimum distances between each tunnel imaging detection module and the tunnel inner wall, preset switching thresholds and switching rules are set for each tunnel imaging detection module.

[0014] This disclosure provides a tunnel imaging detection device and a tunnel detection method. The device includes a tunnel detection vehicle and two or more tunnel imaging detection modules. Each tunnel imaging detection module includes at least two linear scanning units and a ranging unit disposed on each linear scanning unit. The linear scanning units are arranged in a circular distribution on the image acquisition surface of the tunnel imaging detection module, so that each linear scanning unit corresponds to a different region of the tunnel inner wall. During tunnel detection, the ranging units of each tunnel imaging detection module are first activated to measure the distance between the image acquisition surface of each tunnel imaging detection module and the tunnel inner wall. Subsequently, based on the distance between the image acquisition surface of each tunnel imaging detection module and the tunnel inner wall, a tunnel imaging detection module whose distance matches the target distance is selected from at least two tunnel imaging detection modules. Then, the target tunnel imaging detection module is activated to acquire images of the tunnel inner wall. Given that the target tunnel imaging detection module is compatible with the currently measured distance, this indicates that each linear scanning unit within the module can acquire images of the tunnel interior at that distance within the optimal aperture adjustment range. This eliminates the need to excessively reduce the aperture to achieve clear image acquisition at this distance, thus ensuring image quality. In high-speed tunnel inspection scenarios, the tunnel imaging detection device can adaptively select the target tunnel imaging detection module and acquire images, ensuring high-definition images of the tunnel interior during high-speed inspection, providing a solid foundation for subsequent tunnel inspection.

[0015] Other features and aspects of this disclosure will become clear from the following detailed description of exemplary embodiments with reference to the accompanying drawings. Attached Figure Description

[0016] The accompanying drawings, which are included in and form part of this specification, illustrate exemplary embodiments, features, and aspects of this disclosure together with the specification and serve to explain the principles of this disclosure.

[0017] Figure 1 A structural diagram of a tunnel imaging detection apparatus according to an embodiment of the present disclosure is shown; Figure 2 A structural diagram of a tunnel imaging detection module according to an embodiment of the present disclosure is shown; Figure 3 A schematic diagram showing the imaging field of view and the configuration of the corresponding sector region of each linear array scanning unit in a tunnel imaging detection module according to an embodiment of the present disclosure is provided. Figure 4 A flowchart of a tunnel detection method according to an embodiment of the present disclosure is shown; Figure 5 A flowchart illustrating an example of a tunnel detection method according to an embodiment of the present disclosure is shown. Detailed Implementation

[0018] Various exemplary embodiments, features, and aspects of this disclosure will now be described in detail with reference to the accompanying drawings. The same reference numerals in the drawings denote elements that have the same or similar functions. Although various aspects of the embodiments are shown in the drawings, they are not necessarily drawn to scale unless specifically indicated otherwise.

[0019] The term “exemplary” as used herein means “serving as an example, embodiment, or illustration.” Any embodiment illustrated herein as “exemplary” is not necessarily to be construed as superior to or better than other embodiments.

[0020] Furthermore, to better illustrate this disclosure, numerous specific details are set forth in the following detailed description. Those skilled in the art will understand that this disclosure can be practiced without certain specific details. In some instances, methods, means, components, and circuits well known to those skilled in the art have not been described in detail in order to highlight the main points of this disclosure.

[0021] <Device Embodiment> Figure 1 A schematic diagram of a tunnel imaging detection apparatus according to an embodiment of the present disclosure is shown. Figure 1 As shown, the device 100 includes: a tunnel inspection vehicle 120 and two or more tunnel imaging detection modules 110 with identical hardware configurations. Each tunnel imaging detection module 110 is configured to be mounted on the body of the tunnel inspection vehicle 120 in an array arrangement (e.g., along the central axis of each tunnel imaging detection module 110). Figure 1 (The red axis in the diagram coincides with the central axis and is parallel to the tunnel detection direction). When each tunnel imaging detection module 110 is installed on the body of the tunnel detection vehicle 120, the image acquisition surface of each tunnel imaging detection module 110 faces the inner wall of the tunnel to be detected, so as to realize the imaging detection of the inner wall of the tunnel.

[0022] Each tunnel imaging detection module 110, such as Figure 2 The diagram shows at least two linear scanning units 112 and ranging units 111 arranged on each linear scanning unit, with each linear scanning unit 112 arranged in a circular pattern on the image acquisition surface of the tunnel imaging detection module (i.e., Figure 2 The plane formed by connecting the lens surfaces of each linear array scanning unit 112 is such that each linear array scanning unit corresponds to a different area of ​​the tunnel inner wall, so as to realize the image acquisition of the complete cross section of the tunnel.

[0023] Since the hardware configuration of each tunnel imaging detection module 110 in the device 100 is the same, only the focusing position of each linear scan unit is different, the structure of one tunnel imaging detection module 110 will be described in detail below.

[0024] It should be noted that, during the design process, to enable the tunnel imaging detection module 110 to be applicable to large-angle scanning of the tunnel cross-section, the entire tunnel cross-section can be equally divided into multiple sector regions with the same angle. For each sector region, one linear array scanning unit 112 is configured on the image acquisition surface of the tunnel imaging detection module 110, with the lens surface of the linear array scanning unit 112 facing the inner wall of the tunnel within the sector region, and the optical axis of the linear array scanning unit 112 coinciding with the angle bisector of the corresponding sector region. Preferably, the imaging field of view (i.e., the angle of view of each linear array scanning unit 112 configured on each tunnel imaging detection module 110) is... Figure 1 The black triangles in the middle are configured with angles greater than their respective corresponding sector areas, so that the images acquired by adjacent sector areas form an overlapping area at the circumferential edge. This overlapping area is used for subsequent image stitching processing to obtain a complete image of the entire tunnel cross-section at each angle. That is, the number of linear scanning units 112 in the tunnel imaging detection module 110 is determined according to the preset number of partitions of the tunnel cross-section. The specific partitioning method can be set according to specific needs and is not specifically limited here.

[0025] In a specific example, such as Figure 3 As shown, the tunnel cross-section is a 360° circle (i.e., Figure 2 The black circle in the diagram can be divided into six equal fan-shaped regions, each with a central angle of 60°. A linear scanning unit 112 (corresponding to modules 1 to 6 in the diagram) is configured for each fan-shaped region, with the optical axis of each unit 112 coinciding with the angle bisector of the corresponding fan-shaped region. The imaging field of view of each linear scanning unit 112 is configured to 70°. Since 70° > 60°, the imaging range of two adjacent linear scanning units 112 extends 5° beyond their respective fan-shaped boundaries in the circumferential direction, thus forming a 10° overlap region at the junction of adjacent fan-shaped regions. This overlap region provides sufficient registration features for subsequent image stitching, effectively avoiding stitching gaps caused by installation deviations or imaging edge distortion, ensuring a seamless and complete 360° panoramic inspection image of the entire tunnel cross-section.

[0026] Each ranging unit 111, deployed on each linear scan unit 112 in the tunnel imaging detection module 110, is used to measure the distance between the image acquisition surface of its respective tunnel imaging detection module and the tunnel wall upon receiving a ranging command. It should be clearly noted that the distance measured by each ranging unit between the image acquisition surface of its respective tunnel imaging detection module and the tunnel wall is actually the distance between the center of the camera field of view of the linear scan unit where the ranging unit is located and the focal point of the arc surface of the tunnel wall covered by the imaging field of view. Specifically, each ranging unit 111 receives a ranging command simultaneously. After receiving the command, it measures the distance from the lens surface of its respective linear scan unit to the corresponding tunnel wall. Based on the measured distances from the lens surface of each linear scan unit to the corresponding tunnel wall, the distance between the image acquisition surface of the tunnel imaging detection module 110 and the tunnel wall is determined. Specifically, the average distance from the lens surface of each linear scan unit to the corresponding tunnel wall can be used as the distance between the image acquisition surface of the tunnel imaging detection module 110 and the tunnel wall. Alternatively, the maximum distance among the distances from the lens surface of each linear scan unit to the corresponding tunnel wall can be used as the distance between the image acquisition surface of the tunnel imaging detection module 110 and the tunnel wall.

[0027] In one possible implementation, the measuring axes of the various ranging units 111 arranged on each linear scanning unit in the tunnel imaging detection module 110 intersect at a point in opposite directions (such as the center of the circle in the above-mentioned circular distribution), thus enabling 0-360° full-coverage distance measurement. Each ranging unit can use a laser rangefinder, or other types of rangefinders, without specific limitations.

[0028] Each linear scan unit 112 in the tunnel imaging detection module 110 is used to acquire images of the tunnel inner wall according to the received image acquisition command after receiving the command, thereby obtaining a detection image of the tunnel inner wall, which is then used to detect the tunnel inner wall to be detected. Specifically, each linear scan unit 112 receives an image acquisition command simultaneously. After receiving the command, it acquires images of the tunnel inner wall within its imaging field of view, obtaining a detection image of the tunnel inner wall within its imaging field of view. Subsequently, detection images of the tunnel inner wall within different imaging field of view ranges in the same tunnel imaging detection module 110 are sent to the control unit 113, so that the control unit 113 can stitch these detection images within different imaging field of view ranges into a panoramic detection image of the tunnel inner wall under the current cross-section.

[0029] The tunnel imaging detection module currently receiving the image acquisition command is selected from at least two tunnel imaging detection modules based on the distance between the image acquisition surface of each module and the tunnel wall. Specifically, the average distance between the image acquisition surface of each module and the tunnel wall can be calculated, or the maximum distance can be selected, or a specific distance between the image acquisition surface of a particular module and the tunnel wall can be chosen as the selection distance value (referred to as the selection distance value). Then, a tunnel imaging detection module matching the selected distance value is chosen from at least two modules to receive the image acquisition command.

[0030] It should be noted that the tunnel imaging detection device 100 includes a control unit 113, and the aforementioned ranging command and image acquisition command are issued by the control unit 113.

[0031] In one possible implementation, the linear array scanning units 112 in the tunnel imaging detection module 110 are as follows: Figure 2 The diagram shows a linear scanning camera 112-1 and a laser light source 112-2, which are arranged adjacent to each other. The lens of the linear scanning camera 112-1 and the lens of the laser light source 112-2 are located on the same plane. The ranging unit 111 is positioned between the linear scanning camera 112-1 and the laser light source 112-2 (see [reference]). Figure 2 (The red markings in the text).

[0032] In this embodiment, the tunnel imaging detection module 110 also includes a laser 114 configured for each laser source 112-2 in the linear scan unit 112. The linear scan camera 112-1 in the linear scan unit 112 is directly connected to the control unit 113 to receive image acquisition commands sent by the control unit 113 and acquire images of the tunnel interior within its imaging field of view according to the received commands. The laser source 112-2 in the linear scan unit 112 is connected to the control unit 113 via its corresponding laser 114 to receive and supplement the image acquisition process of the linear scan camera in the same linear scan unit according to the supplementary lighting commands sent by the control unit 113. Specifically, after each laser 114 synchronously receives the supplementary lighting command sent by the control unit 113, it emits laser light to the laser source 112-2 connected to it. Each laser source 112-2, after receiving its corresponding laser light, preprocesses it to supplement the image acquisition process of the linear scan camera 112-1 in the same linear scan unit 112.

[0033] In one possible implementation, the linear scan camera 112-1 of each linear scan unit 112 in the tunnel imaging detection module 110 can be a high-resolution high-speed linear scan camera 112-1 to improve the image acquisition quality in high-speed detection scenarios.

[0034] In one possible implementation, each tunnel imaging detection module includes a power supply connector to connect to an external power source and provide a stable operating voltage for each tunnel imaging detection module.

[0035] It should be noted that the tunnel imaging detection device 100 includes at least two tunnel imaging detection modules 110. The linear scanning units 112 of each tunnel imaging detection module 110 have identical hardware parameters and all use fixed-focus lenses. Before performing tunnel detection, the lenses of the linear scanning units 112 of each tunnel imaging detection module 110 need to be focused to different object distances, thereby allowing each tunnel imaging detection module 110 to obtain different depth-of-field ranges, i.e., each has a different clear imaging range. Thus, during the detection of the tunnel inner wall, the actual distance between the image acquisition surface of each tunnel imaging detection module 110 and the tunnel inner wall can be adaptively selected to obtain a clear image at that distance. The selected tunnel imaging detection module 110 is then used to acquire images of the tunnel inner wall. This setup ensures the clarity of the tunnel inner wall detection images and facilitates a natural transition of the field of view during the stitching process of panoramic detection images of different sections of the tunnel inner wall acquired by different tunnel imaging detection modules 110, improving the consistency of the stitching effect.

[0036] In one possible implementation, when the lenses of the linear scan units 112 of each tunnel imaging detection module 110 are focused to different object distance positions, so that each tunnel imaging detection module 110 obtains different depth ranges, the following steps may be included: First, the profile of the tunnel to be inspected and the relative positions of each tunnel imaging detection module 110 to the profile are obtained during the inspection process. Each tunnel to be inspected has a pre-existing profile, which includes the profile of each cross-section of the tunnel. The shape and size distribution of the inner wall of the tunnel at each cross-section can be determined from the profile of each cross-section. The relative position of the tunnel imaging detection module 110 to the profile actually refers to the center point of the tunnel imaging detection module 110 (…). Figure 1 The red markers in the diagram indicate the location of each cross-sectional profile.

[0037] Second, based on the profile of the tunnel to be inspected and the relative positions of each tunnel imaging detection module 110 to the profile during the inspection process, the maximum and minimum distances between each tunnel imaging detection module 110 and the inner wall of the tunnel to be inspected are determined. Specifically, based on the position of the center point of each tunnel imaging detection module 110 in each cross-sectional profile diagram, the distance from the image acquisition surface of each tunnel imaging detection module 110 to the inner wall of the tunnel can be calculated. Then, based on the distance from the image acquisition surface of each tunnel imaging detection module 110 to the inner wall of the tunnel, the selected distance value is determined. This selected distance value is the distance from the image acquisition surface of each tunnel imaging detection module 110 to the inner wall of the tunnel on the current cross-sectional profile diagram. After traversing all cross-sectional profile diagrams in the inspection process, a series of selected distance values ​​are obtained. The global maximum and global minimum values ​​are extracted from these values ​​and used as the maximum and minimum distances between each tunnel imaging detection module 110 and the inner wall of the tunnel to be inspected, respectively.

[0038] Third, based on the maximum and minimum distances between each tunnel imaging detection module 110 and the tunnel inner wall, the focus positions of each linear scanning unit 112 in each tunnel imaging detection module 110 are adjusted, thereby enabling each tunnel imaging detection module 110 to obtain a different depth of field range. Specifically, for each linear scanning unit 112 in the first tunnel imaging detection module 110, its focus position is set to the aforementioned minimum distance value. According to the preset optimal aperture range (e.g., F5.6 to F8) and the focus position (i.e., minimum distance) of any linear scanning unit 112, the depth of field range of the first tunnel imaging detection module 110 can be calculated using the optical imaging depth of field calculation formula, and the farthest object distance that this depth of field range can cover can be obtained. Next, the focus positions of each linear scanning unit 112 in the second tunnel imaging detection module 110 are set to the farthest object distance that the depth of field range of the first tunnel imaging detection module 110 can cover, and the depth of field range of the second tunnel imaging detection module 110 and its farthest object distance that can be covered are calculated using the same method. By analogy, the farthest object distance covered by the depth of field of the Nth tunnel imaging detection module 110 is taken as the focus position of each linear scanning unit 112 in the N+1th tunnel imaging detection module 110, and so on, until the farthest object distance covered by the depth of field calculated by a certain tunnel imaging detection module 110 within the same optimal aperture range can cover or exceed the aforementioned maximum distance. Through the above recursive setting, the clear imaging range of each tunnel imaging detection module 110 is sequentially adjacent or partially overlapped in the object distance direction, jointly covering the entire working distance range from the minimum distance to the maximum distance.

[0039] Furthermore, after setting the focus position of each linear scan unit 112 in each tunnel imaging detection module 110, a distance switching threshold is set for each tunnel imaging detection module 110. This threshold is equal to the farthest object distance that the depth of field of each tunnel imaging detection module 110 can cover (referred to as the farthest object distance in the depth of field). Specifically: the farthest object distance in the depth of field of the first tunnel imaging detection module 110 is denoted as the first switching threshold A; the farthest object distance in the depth of field of the second tunnel imaging detection module 110 is denoted as the second switching threshold B; and so on, the farthest object distance in the depth of field of the i-th tunnel imaging detection module 110 is denoted as the i-th switching threshold.

[0040] Furthermore, after setting the aforementioned switching thresholds, the switching rules for each tunnel imaging detection module 110 are determined based on the set switching thresholds. The switching rules are as follows: When the distance between each tunnel imaging detection module 110 and the inner wall of a certain tunnel section (referred to as the measured distance) is less than or equal to the first switching threshold A, the first tunnel imaging detection module 110 is activated to acquire images; when the measured distance is greater than the first switching threshold A and less than or equal to the second switching threshold B, the second tunnel imaging detection module 110 is activated to acquire images; and so on, when the measured distance is greater than the (i-1)th switching threshold and less than or equal to the ith switching threshold, the ith tunnel imaging detection module 110 is activated to acquire images; when the measured distance is greater than the switching threshold of the last tunnel imaging detection module 110, the last tunnel imaging detection module 110 is activated to acquire images.

[0041] In another possible implementation, the depth-of-field ranges of two adjacent tunnel imaging detection modules 110 are configured to partially overlap in the object distance direction, and a distance switching threshold is set within the overlapping area. Specifically, the two tunnel imaging detection modules arranged in order of near to far object distance along the path of clear imaging are the first tunnel imaging detection module and the second tunnel imaging detection module. First, the focusing distance of each linear scan unit in the first tunnel imaging detection module is set to the minimum working distance corresponding to the current module, and the farthest object distance that its depth of field can cover is calculated based on a preset optimal aperture range. Then, a preset overlap offset is introduced, which is a positive value, and its magnitude can be determined according to the measurement accuracy of the ranging unit or the actual working conditions of tunnel detection. The focusing distance of each linear scan unit in the second tunnel imaging detection module is set to the farthest object distance of the first tunnel imaging detection module minus the overlap offset. In this way, the nearest clear object distance of the second tunnel imaging detection module will be less than the farthest object distance of the first tunnel imaging detection module, thereby making the depth-of-field ranges of the two tunnel imaging detection modules overlap in the object distance direction. Furthermore, the switching threshold between the two is set within the overlapping area. Simultaneously, to avoid frequent invalid switching at the threshold boundary due to ranging errors, a comparison logic with hysteresis is adopted: when the currently enabled module is the first tunnel imaging detection module, switching to the second tunnel imaging detection module is only performed if the measured distance is greater than the switching threshold; when the currently enabled module is the second tunnel imaging detection module, switching back to the first tunnel imaging detection module is only performed if the measured distance is less than the switching threshold minus a preset hysteresis width.

[0042] The following is an example using specific numerical values. Assume a tunnel imaging detection module has a global minimum working distance of 2.5 meters and a global maximum working distance of 5.0 meters. The focusing distance of the first unit (near-end unit) is set to 2.5 meters. Within the preset optimal aperture range, its depth of field is calculated to be 2.1 meters to 3.8 meters, meaning the farthest sharp object distance of the first tunnel imaging detection module is 3.8 meters. With a preset overlap offset of 0.2 meters, the focusing distance of the second tunnel imaging detection module is set to 3.8 meters minus 0.2 meters, i.e., 3.6 meters. The calculated depth of field range of the second tunnel imaging detection module is 3.0 meters to 4.7 meters. Therefore, the depth of field range of the first tunnel imaging detection module (2.1 meters to 3.8 meters) and the depth of field range of the second tunnel imaging detection module (3.0 meters to 4.7 meters) form an overlapping area from 3.0 meters to 3.8 meters, with an overlap width of 0.8 meters. The switching threshold between the two is set within this overlapping area, for example, 3.5 meters. The preset hysteresis width is 0.1 meters. The switching rules are as follows: When the first tunnel imaging detection module is currently activated, if the measured distance is greater than 3.5 meters, switch to the second tunnel imaging detection module; when the second tunnel imaging detection module is currently activated, if the measured distance is less than 3.4 meters (i.e., 3.5 meters minus 0.1 meters), switch back to the first tunnel imaging detection module. The measured distance here is the distance between each tunnel imaging detection module and the inner wall of the current tunnel section.

[0043] During tunnel detection, when the measured distance is within the overlapping area (e.g., between 3.48 meters and 3.52 meters), even if the ranging unit has a random error of ±0.05 meters, and the measured reading may fluctuate around 3.5 meters, due to the hysteresis logic (the distance needs to drop below 3.4 meters to switch back from the second tunnel imaging detection module to the first tunnel imaging detection module), the system will not experience back-and-forth oscillations between the first and second tunnel imaging detection modules. Furthermore, since the depth of field of the first tunnel imaging detection module covers up to 3.8 meters, and the depth of field of the second tunnel imaging detection module covers up to 3.0 meters, both covering the overlapping area, the acquired images remain clear regardless of which tunnel imaging detection module is currently in use. The system only smoothly performs a switch when the measured distance significantly moves out of the overlapping area (e.g., drops below 3.4 meters or rises above 3.5 meters and continues to deviate). Through the above configuration, the technical solution disclosed herein effectively overcomes the uncertainty caused by ranging error, avoids invalid switching at threshold boundaries, and significantly improves the stability and robustness of image acquisition during high-speed tunnel detection.

[0044] After setting the switching threshold and switching rules as described above, they are configured in the control unit of the tunnel imaging detection device 100. In this way, as the tunnel imaging detection device 100 travels along the tunnel, it can automatically select the tunnel imaging detection module with the clearest image at the moment for image acquisition based on the real-time measured distance value and the configured switching threshold and switching rules, thereby ensuring that high-quality detection images are always obtained throughout the entire working distance range.

[0045] In this application, multiple tunnel imaging detection modules are defined sequentially as a first tunnel imaging detection module, a second tunnel imaging detection module, a third tunnel imaging detection module, and so on, according to the focusing positions of their respective linear scan units from near to far. The focusing position of the first tunnel imaging detection module is set to the aforementioned minimum distance value; the focusing position of the second tunnel imaging detection module is set to the farthest object distance in the depth of field of the first tunnel imaging detection module; the focusing position of the third tunnel imaging detection module is set to the farthest object distance in the depth of field of the second tunnel imaging detection module, and so on.

[0046] In one possible implementation, the number of tunnel imaging detection modules 110 in the device 100 can be determined based on the maximum distance that can be covered by the tunnel imaging detection device 100 as set during the design. Specifically, based on the aforementioned minimum distance and a preset optimal aperture range, the minimum number of tunnel imaging detection modules 110 required is calculated recursively as follows: the focus position of the first tunnel imaging detection module 110 is set to the aforementioned minimum distance, and its depth of field range is calculated according to the preset optimal aperture range (e.g., F5.6 to F8) to obtain the farthest object distance that this depth of field can cover; then the focus position of the second tunnel imaging detection module 110 is set to the farthest object distance of the first tunnel imaging detection module 110, and the same method is used to calculate the farthest object distance of the second tunnel imaging detection module 110; and so on, the farthest object distance of the Nth tunnel imaging detection module 110 is used as the focus position of the N+1th second tunnel imaging detection module, until the calculated farthest object distance can cover or exceed the maximum distance. At this point, the cumulative number of tunnel imaging detection modules 110 involved is the minimum number required to meet the aforementioned maximum distance coverage requirement. In actual design, the total number of tunnel imaging detection modules 110 actually configured can be determined based on this minimum number and considering redundancy or assembly factors.

[0047] In one possible implementation, the tunnel imaging detection device 100 includes: a control unit 113, which is connected to each ranging unit 111 and each linear array scanning unit 112 in each tunnel imaging detection module 110. Upon receiving a tunnel detection command, the control unit 113 synchronously sends ranging commands to each ranging unit 111 of each tunnel imaging detection module 110; it receives and selects one tunnel imaging detection module 110 from at least two based on the distance between the image acquisition surface of each tunnel imaging detection module 110 and the tunnel inner wall measured by each ranging unit 111; and sends image acquisition commands to each linear array scanning unit 112 of the selected tunnel imaging detection module 110 to control the linear array scanning units 112 within it to synchronously acquire images of the inner wall of the current tunnel section, thereby achieving the detection image acquisition of the tunnel inner wall across the entire viewing angle on the same tunnel section through the collaborative efforts of each linear array scanning unit 112.

[0048] In one possible implementation, after receiving the tunnel inner wall detection images acquired by each linear array scanning unit 112 of the selected tunnel imaging detection module 110, the control unit 113 will stitch these tunnel inner wall detection images together according to the imaging perspective to obtain a stitched image on the same tunnel cross section.

[0049] In one possible implementation, the control unit 113 includes a main control unit and a sub-control unit configured in each tunnel imaging detection module 110. In this control architecture, the main control unit is responsible for receiving tunnel detection commands. After receiving the tunnel detection command, the main control unit sends a detection trigger command to the sub-control units in each tunnel imaging detection module 110. Upon receiving the detection trigger command, each sub-control unit first controls its internal ranging units to perform distance measurements, receives and calculates the distance between the image acquisition surface of each tunnel imaging detection module and the tunnel wall of the current tunnel section based on the distance measured by each ranging unit, and calculates a selected distance based on the distance between the image acquisition surface of each tunnel imaging detection module and the tunnel wall of the current tunnel section, and then feeds this selected distance back to the main control unit. Based on the selected distance and the switching thresholds and rules set for each tunnel imaging detection module 110, the main control unit selects a tunnel imaging detection module 110 from among the multiple modules 110 that can clearly image at the average distance. It then sends an image acquisition command to its internal sub-control unit. Upon receiving the command, the sub-control unit instructs its internal linear scanning units to acquire images, receiving the tunnel inner wall detection images acquired by each unit and sending them back to the main control unit. The main control unit stitches together the tunnel inner wall detection images acquired by each unit to obtain a panoramic detection image of the current tunnel cross-section. The main control unit can also stitch together panoramic detection images of multiple tunnel cross-sections during the detection process to obtain a detection image of the tunnel inner wall over a larger area.

[0050] In the above embodiments, the tunnel inner walls of different sector areas on the same tunnel cross-section are detected and imaged by multiple linear array scanning units in the same tunnel imaging detection module. In another possible implementation, the tunnel inner walls of different sector areas on the same tunnel cross-section can also be detected and imaged by linear array scanning camera units in different tunnel imaging detection modules. Specifically, different sector areas on the same tunnel cross-section are traversed. For the current sector area, the ranging units deployed on the linear array scanning units corresponding to the sector area in each tunnel imaging detection module are first controlled to measure the distance from the camera field of view center of each linear array scanning unit to the arc of the tunnel inner wall of the current sector area. Then, based on the multiple measured distance values, the distance between each linear array scanning unit facing the current sector area and the arc of the tunnel inner wall of the current sector area is determined. For example, the average of multiple distance values ​​can be taken, the maximum value of multiple distance values ​​can be taken, or the distance value measured by a specified linear array scanning unit can be taken. No specific limitation is made here. After determining this final distance value, based on this final distance value, one linear array scanning unit that matches the distance value is selected from multiple linear array scanning units facing the current sector area as the target linear array scanning unit. Then, the control unit sends an image acquisition command to this target linear array scanning unit, and this target linear array scanning unit completes the detection image acquisition of the tunnel inner wall of the current sector area. Before executing this method, it is necessary to determine the maximum and minimum distances between the group of linear scanning units facing the current sector area and the tunnel wall of the current sector area throughout the entire detection process, based on the profile of the tunnel wall to be detected. The focus position, switching threshold, and switching rules of this group of linear scanning units are adjusted according to the determined maximum and minimum distances. For details on how to determine the focus position, switching threshold, and switching rules of each linear scanning unit in this group, please refer to the above text, which will not be repeated here. After configuring the group of linear scanning units facing the current sector area, during subsequent detection, once the distance between this group of linear scanning units and the arc of the tunnel wall of the current sector area is obtained, one of the linear scanning units facing the current sector area can be selected as the target linear scanning unit based on this distance, combined with the switching threshold and switching rules set for this group. The detection image of the tunnel wall of the current sector area is then acquired through this target linear scanning unit. The focusing process, switching threshold and switching rule configuration process, as well as the ranging and target linear scanning unit selection process for each group of linear scanning units facing other fan-shaped regions are consistent with those for the current fan-shaped region, and will not be repeated here. Finally, the control unit collects tunnel detection images of different fan-shaped regions on the same cross-section and stitches them together to obtain a panoramic detection image of that cross-section.

[0051] In other words, in this feasible method, the linear array scanning units of the same sector facing the inner wall of the tunnel in each tunnel imaging detection module are configured and switched as a group. In this way, even if the driving path of the detection vehicle changes in the tunnel during the detection process, the detection images of different sector areas on the tunnel cross-section can be accurately and quickly acquired.

[0052] In this disclosure, the tunnel imaging detection device includes: a tunnel detection vehicle and two or more tunnel imaging detection modules. Each tunnel imaging detection module includes: at least two linear array scanning units and a ranging unit deployed on each linear array scanning unit. The linear array scanning units are arranged in a circular distribution on the image acquisition surface of the tunnel imaging detection module, so that each linear array scanning unit corresponds to a different region of the tunnel inner wall. When conducting tunnel detection, the ranging unit of each tunnel imaging detection module is first activated to measure the distance between the image acquisition surface of each tunnel imaging detection module and the tunnel inner wall. Subsequently, based on the distance between the image acquisition surface of each tunnel imaging detection module and the tunnel inner wall, a tunnel imaging detection module whose distance matches the target distance is selected from at least two tunnel imaging detection modules. Then, the target tunnel imaging detection module is activated to acquire images of the tunnel inner wall. Given that the target tunnel imaging detection module is compatible with the currently measured distance, this indicates that each linear scanning unit within the module can acquire images of the tunnel interior wall at that distance within the optimal aperture adjustment range. This eliminates the need for excessive aperture reduction to achieve image acquisition at this distance, thus ensuring image quality. In high-speed tunnel inspection scenarios, the tunnel imaging detection device can adaptively select the target tunnel imaging detection module and acquire images, ensuring high-definition images of the tunnel interior wall are obtained during high-speed inspection, providing a solid foundation for subsequent tunnel inspection.

[0053] <Method Implementation> Figure 4 A flowchart illustrating a tunnel detection method according to an embodiment of the present disclosure is shown. When this method is implemented by any of the devices in the device embodiments, such as... Figure 4 As shown, the method includes steps S2100-S2300: S2100 sends a ranging command to each ranging unit of each tunnel imaging detection module, so that each ranging unit of each tunnel imaging detection module, upon receiving the ranging command, responds to the ranging command to measure the distance between the image acquisition surface of the tunnel imaging detection module and the inner wall of the tunnel. S2200: Receive and select one tunnel imaging detection module from at least two tunnel imaging detection modules as the target tunnel imaging detection module based on the distance between the image acquisition surface of each tunnel imaging detection module and the tunnel inner wall, and send an image acquisition command to each linear array scanning unit of each target tunnel imaging detection module so that each linear array scanning unit can acquire an image of the tunnel inner wall. S2300 receives and generates a panoramic detection image of the tunnel inner wall based on the detection images acquired by each linear scan unit in the target tunnel imaging detection module, so as to detect the inner wall of the tunnel to be detected based on the panoramic detection image.

[0054] In one possible implementation, when selecting one tunnel imaging detection module from at least two tunnel imaging detection modules as the target tunnel imaging detection module, the switching is based on a preset switching threshold and switching rules for each tunnel detection module.

[0055] In one possible implementation, the method includes the following before performing the tunnel imaging detection method: Acquire the profile of the tunnel to be inspected and the relative position of each tunnel imaging detection module to the profile during the inspection process; Based on the profile and relative position, determine the maximum and minimum distances between each tunnel imaging detection module and the tunnel inner wall during the detection process; Based on the maximum and minimum distances between each tunnel imaging detection module and the tunnel wall, the focus position of the linear array scanning unit in each tunnel imaging detection module is adjusted.

[0056] In one possible implementation, the method further includes: Based on the maximum and minimum distances between each tunnel imaging detection module and the tunnel wall, preset switching thresholds and switching rules are set for each tunnel imaging detection module.

[0057] The implementation details of each step in the method embodiment are described in the specific description in the device embodiment, and will not be repeated here.

[0058] To clearly illustrate this method, the following will be combined with... Figure 5 A specific embodiment will be used to further illustrate the method. The specific steps are as follows: Step S1: Preliminary Configuration Steps S101, Obtain the profile of the tunnel to be inspected. Specifically, obtain a pre-constructed profile of the tunnel to be inspected. This profile reflects the geometric structure information of the tunnel at each cross-section, including the shape and size distribution of the inner wall at each cross-section.

[0059] S102, based on the profile diagram and the relative positions of each tunnel imaging detection module 110 and the profile diagram during the detection process, determine the maximum and minimum distances between each tunnel imaging detection module 110 and the inner wall of the tunnel to be detected during this detection process.

[0060] S103, based on the maximum and minimum distances between each tunnel imaging detection module 110 and the tunnel inner wall, adjust the focus position of each linear array scanning unit 112 in each tunnel imaging detection module 110, so that each tunnel imaging detection module 110 obtains a different depth of field range. This step further includes: First, the focus positions of the linear array scanning units 112 in each tunnel imaging detection module 110 are recursively set. Specifically, the focus position of the linear array scanning unit 112 in the first tunnel imaging detection module 110 is set to the aforementioned minimum distance value. The optimal aperture range for each linear array scanning unit 112 during operation is set, for example, F5.6 to F8. Based on the optical depth-of-field calculation formula, the depth-of-field range of the first tunnel imaging detection module 110 is calculated according to the focus position (i.e., the aforementioned minimum distance) and the optimal aperture range of any linear array scanning unit 112, and the farthest object distance that this depth-of-field range can cover is obtained. The focus position of each linear array scanning unit in the second tunnel imaging detection module 110 is set to this farthest object distance within the depth of field. This process continues, with the farthest object distance within the depth of field of the Nth tunnel imaging detection module 110 used as the focus position of each linear array scanning unit in the N+1th tunnel imaging detection module 110, until the farthest object distance within the depth of field of a certain tunnel imaging detection module 110 can cover or exceed the aforementioned maximum distance.

[0061] Secondly, a distance switching threshold is set for each tunnel imaging detection module 110. Specifically, the farthest object distance in the depth of field of each tunnel imaging detection module 110 is used as the switching threshold for that module. Specifically: the farthest object distance in the depth of field of the first tunnel imaging detection module 110 is denoted as the first switching threshold A; the farthest object distance in the depth of field of the second tunnel imaging detection module 110 is denoted as the second switching threshold B; and so on.

[0062] Finally, the switching rules are determined. Specifically, the switching rules are as follows: when the measured distance is less than or equal to the first switching threshold A, the first tunnel imaging detection module 110 is activated to acquire images; when the measured distance is greater than A and less than or equal to B, the second tunnel imaging detection module 110 is activated to acquire images; and so on, when the measured distance is greater than the previous switching threshold and less than or equal to the current switching threshold, the current tunnel imaging detection module 110 is activated to acquire images; when the measured distance is greater than the last switching threshold, the last tunnel imaging detection module 110 is activated to acquire images.

[0063] S104: Configure the set switching threshold and switching rules into the control unit. Specifically, store the switching threshold and switching rules of each tunnel imaging detection module 110 in the control unit.

[0064] At this point, the preliminary configuration is complete.

[0065] Step S2: Online detection step S201, Send detection command. Specifically, send a tunnel detection command to the control unit of the tunnel imaging detection device 100.

[0066] S202, the control unit synchronously controls each tunnel imaging detection module 110 to perform distance measurement, and selects a tunnel imaging detection module that matches the measured distance to acquire images of the current tunnel section.

[0067] S203, the control unit stitches together the images to generate a panoramic image. Specifically, the control unit receives the detection images fed back by the selected tunnel imaging detection module 110, stitches the detection images together, and generates a panoramic acquisition image of the current section.

[0068] S204. Repeat steps S202 to S203 until the entire tunnel inspection is completed.

[0069] As the tunnel imaging detection device 100 travels along the tunnel, the above-mentioned distance measurement, image acquisition and stitching operations are repeatedly performed on each detection section to finally obtain a panoramic detection image of the entire tunnel.

[0070] The various embodiments of this disclosure have been described above. These descriptions are exemplary and not exhaustive, and are not limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical applications, or technical improvements to the technology in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A tunnel imaging detection device, characterized in that, include: The tunnel inspection vehicle and two or more tunnel imaging detection modules are configured to be installed on the vehicle body of the tunnel inspection vehicle in an array, and when the tunnel imaging detection modules are installed on the vehicle body of the tunnel inspection vehicle, the image acquisition surface of each tunnel imaging detection module faces the inner wall of the tunnel to be inspected, so as to realize the imaging detection of the inner wall of the tunnel. Each of the tunnel imaging detection modules includes: at least two linear array scanning units and a ranging unit arranged on each of the linear array scanning units, and each of the linear array scanning units is arranged in a circular distribution on the image acquisition surface of the tunnel imaging detection module so that each linear array scanning unit corresponds to a different area of ​​the tunnel inner wall. Each of the aforementioned ranging units is used to, upon receiving a ranging command, respond to the ranging command to measure the distance between the image acquisition surface of the tunnel imaging detection module and the inner wall of the tunnel; Each of the linear array scanning units is used to acquire images of the tunnel inner wall according to the received image acquisition command after receiving the image acquisition command, so as to obtain a detection image of the tunnel inner wall, and to detect the tunnel inner wall to be detected according to the detection image; The tunnel imaging detection module that currently receives the image acquisition command is a tunnel imaging detection module selected from at least two tunnel imaging detection modules based on the distance between the image acquisition surface of each tunnel imaging detection module and the inner wall of the tunnel.

2. The apparatus according to claim 1, characterized in that, include: A control unit, which is connected to each of the tunnel imaging detection modules; For each of the tunnel imaging detection modules, the control unit is configured to send the ranging command to each of the ranging units of the tunnel imaging detection module, receive and select one tunnel imaging detection module from at least two tunnel imaging detection modules based on the distance between the image acquisition surface of the tunnel imaging detection module and the inner wall of the tunnel measured by each of the ranging units, and send image acquisition commands to each linear scan unit of the selected tunnel imaging detection module to control it to acquire images of the inner wall of the tunnel and obtain a detection image of the inner wall of the tunnel.

3. The apparatus according to claim 2, characterized in that, Each of the linear scanning units includes a linear scanning camera and a laser light source. The linear scanning camera and the laser light source are arranged adjacent to each other, and the lens of the linear scanning camera and the lens of the laser light source are located on the same plane. The linear scan camera in each of the linear scan units is directly connected to the control unit to receive and perform image acquisition according to the image acquisition command sent by the control unit; The tunnel imaging detection module also includes lasers corresponding to each of the linear array scanning units. The laser source in each of the linear array scanning units is connected to the control unit through the corresponding laser to receive and supplement the image acquisition process of the linear array scanning camera in the same linear array scanning unit according to the supplementary lighting command sent by the control unit.

4. The apparatus according to claim 3, characterized in that, The linear scan camera of each of the linear scan units is a high-resolution, high-speed linear scan camera.

5. The apparatus according to claim 1, characterized in that, The measuring axes of each ranging unit of each tunnel imaging detection module intersect at a point in opposite directions.

6. The apparatus according to claim 1, characterized in that, Each of the tunnel imaging detection modules includes a power supply connector to connect to an external power source and provide a stable operating voltage for each of the tunnel imaging detection modules.

7. A tunnel imaging detection method, characterized in that, The method is implemented based on the tunnel imaging detection device according to any one of claims 1-6, and includes: A ranging command is sent to each ranging unit of each tunnel imaging detection module, so that each ranging unit of each tunnel imaging detection module, upon receiving the ranging command, responds to the ranging command to measure the distance between the image acquisition surface of the tunnel imaging detection module and the inner wall of the tunnel. The system receives and selects one tunnel imaging detection module from at least two tunnel imaging detection modules as the target tunnel imaging detection module based on the distance between the image acquisition surface of each tunnel imaging detection module and the inner wall of the tunnel. Then, it sends an image acquisition command to each linear scan unit of the target tunnel imaging detection module so that each linear scan unit can acquire an image of the inner wall of the tunnel. The system receives and generates a panoramic detection image of the tunnel inner wall based on the detection images acquired by each of the linear array scanning units in the target tunnel imaging detection module, so as to detect the tunnel inner wall to be detected based on the panoramic detection image.

8. The method according to claim 7, characterized in that, When selecting one tunnel imaging detection module from at least two tunnel imaging detection modules as the target tunnel imaging detection module, the switching is implemented based on the preset switching threshold and switching rules for each tunnel imaging detection module.

9. The method according to claim 7, characterized in that, Before performing the tunnel imaging detection method, the method further includes: The profile of the tunnel to be detected and the relative positions of each tunnel imaging detection module to the profile during the detection process are obtained; Based on the profile and the relative position, determine the maximum and minimum distances between each tunnel imaging detection module and the tunnel inner wall during the detection process; Based on the maximum and minimum distances between each tunnel imaging detection module and the tunnel inner wall, the focus position of each linear array scanning unit in each tunnel imaging detection module is adjusted.

10. The method according to claim 9, characterized in that, Also includes: Based on the maximum and minimum distances between each tunnel imaging detection module and the tunnel inner wall, preset switching thresholds and switching rules are set for each tunnel imaging detection module.

Images