Vehicle-mounted 3D ultrasonic system and method for monitoring health of subway tunnel structure

Abstract

The invention discloses a vehicle-mounted 3D ultrasonic system and method for monitoring the health of a subway tunnel structure, and relates to the technical field of subway tunnel structure health monitoring, and the system comprises a vehicle-mounted ultrasonic sensor array device, a chip-based ultrasonic controller, and a computer-based subway tunnel structure health analysis module. The sensor array design of the vehicle-mounted ultrasonic sensor array device can cover the whole cross section of a tunnel, monitoring comprehensiveness is ensured, and the beam former enhances signals from a specific direction through the beam forming technology. The beamforming technique can improve the directionality of the system, so that the sensor array can distinguish signals from different directions. After the ultrasonic signal after beam forming is wirelessly transmitted to the subway tunnel structure health analysis module, health degree evaluation can be carried out based on a three-dimensional imaging reconstruction result subsequently, and potential structure problems can be found in time, so that the safety of subway operation is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of subway tunnel structure health monitoring, and in particular to a system and method for vehicle-mounted 3D ultrasonic monitoring of subway tunnel structure health. Background Art

[0002] As an important part of urban rail transit, the structural health of subway tunnels is directly related to operational safety. With the acceleration of urbanization, the construction and operation mileage of subway tunnels are increasing, and the demand for monitoring the structural health of tunnels is becoming increasingly urgent. Unlike LiDAR and cameras, ultrasonic sensors are less affected by environmental factors (such as insufficient light, dust or temperature changes). Ultrasound can also detect reflective or transparent surfaces, such as glass or mirrors. Obviously, other traditional monitoring methods, such as manual inspections, levels, total stations, GPS, displacement meters, etc., have monitoring blind spots (only monitoring the surface, deep layers such as cavities, density behind tunnel walls, etc.), insufficient accuracy, etc., and it is difficult to meet the high requirements of modern rail transit for safety and real-time performance.

[0003] Therefore, developing a new monitoring method can make up for the deficiencies of traditional monitoring elements of the health status of tunnel structures, which is of great significance for ensuring the safe operation of rail transit. Summary of the invention

[0004] In order to solve the above-mentioned technical problems of subway tunnel structural health monitoring, the present invention provides a system and method for vehicle-mounted 3D ultrasonic monitoring of subway tunnel structural health. The following technical solutions are adopted:

[0005] A system for monitoring the structural health of a subway tunnel by using a vehicle-mounted 3D ultrasonic wave, comprising a vehicle-mounted ultrasonic sensor array device, a chip-based ultrasonic controller and a computer-based subway tunnel structural health analysis module, wherein the vehicle-mounted ultrasonic sensor array device comprises an autonomous mobile terminal, a sensor mounting platform, a plurality of ultrasonic sensor units, a beam former and a vehicle-mounted wireless data transceiver module, wherein the bottom of the sensor mounting platform is mounted on the top of the autonomous mobile terminal, the sensor mounting platform is provided with a sensor mounting plate, a plurality of ultrasonic sensor units are respectively mounted around the sensor mounting plate, when the plurality of ultrasonic sensor units are working, the formed sensor array covers the cross section of the target tunnel, the beam former communicates with the plurality of ultrasonic sensor units to receive ultrasonic signals, and is wirelessly connected to the subway tunnel structural health analysis module through the vehicle-mounted wireless data transceiver module, the ultrasonic controller is respectively connected to the autonomous mobile terminal, the plurality of sensor mounting platforms and the plurality of ultrasonic sensor units, and the subway tunnel structural health analysis module performs three-dimensional reconstruction of the subway tunnel structure based on the beamforming ultrasonic data of the plurality of vehicle-mounted ultrasonic sensor array devices and outputs a three-dimensional reconstruction image.

[0006] By adopting the above technical solution, when the autonomous mobile terminal of the vehicle-mounted ultrasonic sensor array device moves in the target tunnel, the sensor array design of the vehicle-mounted ultrasonic sensor array device can cover the entire cross-section of the tunnel, ensuring the comprehensiveness of monitoring without missing any potential problem areas. Multiple ultrasonic sensor units obtain 3D spatial information of the target tunnel structure by emitting ultrasonic waves and receiving the reflected signals. The beamformer uses beamforming technology to enhance signals from specific directions while suppressing signals from other directions. Beamforming technology can improve the directionality of the system, allowing the sensor array to distinguish signals from different directions.

[0007] After the beamformed ultrasonic signal is wirelessly transmitted to the subway tunnel structure health analysis module, the subway tunnel structure health analysis module can use 3D imaging technology to realize three-dimensional imaging reconstruction of the subway tunnel structure. Subsequently, health assessment can be performed based on the three-dimensional imaging reconstruction results to timely discover potential structural problems, thereby improving the safety of subway operations.

[0008] Optionally, the sensor mounting platform includes a base, an electric turntable, an electric telescopic rod and a sensor mounting plate, the base is detachably mounted on the top of the autonomous mobile terminal, the electric turntable is detachably mounted on the base, the bottom of the electric telescopic rod is detachably mounted on the rotating part at the top of the electric turntable, and the middle part of one side of the sensor mounting plate is detachably mounted on the telescopic rod of the electric telescopic rod through a mounting block.

[0009] By adopting the above technical solution, the movement adjustment of the electric turntable and the electric telescopic rod can realize the adjustment of the angle and height of the sensor mounting plate, so that the ultrasonic signal intensity of the multiple ultrasonic sensor units installed on the sensor mounting plate can be uniform, so that the sensor array formed by the multiple ultrasonic sensor units covers the cross-section of the current tunnel.

[0010] Optionally, if the ultrasonic signal strength fed back by the multiple ultrasonic sensor units is lower than the set ultrasonic strength threshold, the ultrasonic controller controls the electric turntable and the electric telescopic rod to perform fine-tuning actions respectively until the ultrasonic signal strength fed back by the multiple ultrasonic sensor units is greater than or equal to the set ultrasonic strength threshold;

[0011] The fine-tuning action means that the electric turntable rotates 1° clockwise or counterclockwise, and the piston rod of the electric telescopic rod rises or falls 1mm.

[0012] By adopting the above technical solution, if it is detected that the ultrasonic signal fed back by the ultrasonic sensing unit is missing or the intensity is lower than the threshold, it may indicate that the cross section is not effectively covered. The ultrasonic controller calculates the mechanical instructions that need to be adjusted according to the results of the defect detection and sends them to the electric turntable and the electric telescopic rod to realize the automatic adjustment of the adaptive sensor array.

[0013] Optionally, the ultrasonic sensing unit includes a shell, an ultrasonic transmitter and an ultrasonic sensor, the shell is detachably mounted on the sensor mounting plate, an axial extension line of the shell passes through the center of the sensor mounting plate, the ultrasonic transmitter and the ultrasonic sensor are respectively in the shell, and the sensor head faces outward, the data output end of the ultrasonic sensor is communicatively connected to the signal input end of the beam former, and the ultrasonic controller is communicatively connected to the ultrasonic sensor.

[0014] By adopting the above technical solution, the ultrasonic transmitter can transmit ultrasonic signals toward the tunnel structure, the ultrasonic sensor receives the reflected signals, the data output ends of the multiple ultrasonic sensor units communicate with the beamformer to interactively receive the ultrasonic signals, and the beamformer processes the ultrasonic signals based on the beamforming technology. The processed ultrasonic signals are more conducive to three-dimensional reconstruction.

[0015] Optionally, the subway tunnel structure health analysis module includes a computer-side wireless transceiver module, a memory and a data analysis computer, wherein the computer-side wireless transceiver module is wirelessly connected to the vehicle-side wireless data transceiver module, the memory is communicatively connected to the computer-side wireless transceiver module, and the data analysis computer is communicatively connected to the memory. The data analysis computer uses a synthetic aperture focusing imaging method to perform three-dimensional reconstruction of the subway tunnel structure based on beamforming ultrasonic data from multiple vehicle-mounted ultrasonic sensor array devices, output a three-dimensional reconstructed image, and evaluate the structural health of the subway tunnel based on the three-dimensional reconstructed image.

[0016] Optionally, the autonomous mobile terminal is an AGV electric vehicle.

[0017] By adopting the above technical solution, the AGV electric car can move accurately in the tunnel, and the battery of the AGV electric car can also power the on-board ultrasonic sensor array device.

[0018] A method for monitoring the structural health of a subway tunnel using a vehicle-mounted 3D ultrasonic wave, which uses a vehicle-mounted 3D ultrasonic wave monitoring system for monitoring the structural health of a subway tunnel to reconstruct a three-dimensional image of the internal structure of a target tunnel, and evaluates the structural health of the subway tunnel based on the three-dimensional image of the internal structure of the target tunnel, comprising the following steps:

[0019] Step 1, controlling the autonomous mobile terminal to travel along the central axis of the target tunnel, and stopping to perform ultrasonic data collection actions at set intervals;

[0020] Step 2, the ultrasonic controller controls the electric turntable and the electric telescopic rod to perform fine-tuning actions respectively until the ultrasonic signal strengths fed back by the multiple ultrasonic sensor units are greater than or equal to the set ultrasonic intensity threshold, so that the sensor array formed by the multiple ultrasonic sensor units covers the cross section of the target tunnel;

[0021] Step 3: multiple ultrasonic sensor units are turned on, and the beam former uses beamforming technology to enhance the ultrasonic signal from the target tunnel structure, and the enhanced ultrasonic signal data is sent to the subway tunnel structure health analysis module through the vehicle-mounted wireless data transceiver module;

[0022] Step 4, the data analysis computer uses a synthetic aperture focusing imaging method to process the beamforming ultrasonic data enhanced by the beamforming technology, and uses the synthetic aperture focusing imaging method to perform three-dimensional reconstruction of the subway tunnel structure and output a three-dimensional reconstructed image;

[0023] Step 5: the autonomous mobile terminal drives to the end of the central axis of the target tunnel to complete the three-dimensional reconstruction of all cross sections;

[0024] Step 6: The data analysis computer extracts features for health assessment based on the three-dimensional reconstructed images of all cross sections. The features include crack width, volume change, and material degradation. The extracted features are used to assess the health of the tunnel structure.

[0025] Optionally, in step 3, the calculation formula for beamforming is:

[0026]

[0027] where y ( t ) is the ultrasonic signal output after beamforming, w i is the weight vector of the beamformer; h i( t ) The received signal after signal processing, x i( t ) is a channel receiving signal, s ( t ) is the target signal, a ( θ is the direction vector, w H is the conjugate transpose of w.

[0028] Optionally, in step 4, the formula of the synthetic aperture focusing imaging method is:

[0029]

[0030] Among them I ( f,θ ) is the imaging result, y ( t ) is the ultrasonic signal output after beamforming, f is the ultrasonic signal frequency, θ is the angle of the ultrasonic signal, and N is the number of ultrasonic signal sampling points.

[0031] Optionally, in step 6, the formula for evaluating the health of the tunnel structure using the extracted features is:

[0032] H=f ( F 1 , F 2 , …, F n ) ;

[0033] Where H is the health assessment index of the tunnel structure, F 1 , F 2 , …, F n is the feature item extracted from the three-dimensional reconstructed image for health assessment, n is the number of feature items, and f is the evaluation function; the evaluation function is a linear combination, weighted average or machine learning model.

[0034] In summary, the present invention includes at least one of the following beneficial technical effects:

[0035] The present invention can provide a system and method for on-board 3D ultrasonic monitoring of subway tunnel structural health. The sensor array design of the on-board ultrasonic sensor array device can cover the entire cross-section of the tunnel, ensuring the comprehensiveness of monitoring without missing any potential problem areas. Multiple ultrasonic sensor units obtain 3D spatial information of the target tunnel structure by emitting ultrasonic waves and receiving the reflected signals. The beamformer uses beamforming technology to enhance signals from specific directions while suppressing signals from other directions. Beamforming technology can improve the directionality of the system, allowing the sensor array to distinguish signals from different directions.

[0036] After the beamformed ultrasonic signal is wirelessly transmitted to the subway tunnel structure health analysis module, the subway tunnel structure health analysis module can use 3D imaging technology to realize three-dimensional imaging reconstruction of the subway tunnel structure. Subsequently, health assessment can be performed based on the three-dimensional imaging reconstruction results to timely discover potential structural problems, thereby improving the safety of subway operations. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 It is a schematic diagram of the component connection principle of a system for monitoring the structural health of a subway tunnel on a vehicle using 3D ultrasonic waves according to the present invention;

[0038] Figure 2 It is a schematic diagram of the structural principle of a vehicle-mounted ultrasonic sensor array device of a system for monitoring the structural health of a subway tunnel with a vehicle-mounted 3D ultrasonic wave according to the present invention.

[0039] Figure 3 It is a flow chart of a method for monitoring the structural health of a subway tunnel using vehicle-mounted 3D ultrasonic waves according to the present invention.

[0040] Explanation of the reference numerals: 11. Autonomous mobile terminal; 12. Sensor mounting platform; 121. Sensor mounting plate; 122. Base; 123. Electric turntable; 124. Electric telescopic rod; 13. Ultrasonic sensing unit; 131. Shell; 132. Ultrasonic transmitter; 133. Ultrasonic sensor; 14. Beam former; 15. Vehicle-mounted wireless data transceiver module; 2. Ultrasonic controller; 3. Metro tunnel structure health analysis module; 31. Computer-end wireless transceiver module; 32. Memory; 33. Data analysis computer. DETAILED DESCRIPTION

[0041] The present invention is further described in detail below in conjunction with the accompanying drawings.

[0042] The embodiment of the present invention discloses a system and method for monitoring the structural health of a subway tunnel using vehicle-mounted 3D ultrasonic waves.

[0043] Reference Figure 1 - Figure 3 Embodiment 1, a vehicle-mounted 3D ultrasonic monitoring system for subway tunnel structure health, comprising a vehicle-mounted ultrasonic sensor array device, a chip-based ultrasonic controller 2 and a computer-based subway tunnel structure health analysis module 3, the vehicle-mounted ultrasonic sensor array device comprising an autonomous mobile terminal 11, a sensor mounting platform 12, a plurality of ultrasonic sensor units 13, a beam former 14 and a vehicle-mounted wireless data transceiver module 15, the bottom of the sensor mounting platform 12 is mounted on the top of the autonomous mobile terminal 11, the sensor mounting platform 12 is provided with a sensor mounting plate 121, and the plurality of ultrasonic sensor units 13 are respectively mounted on the sensor mounting plate 121 All around, when multiple ultrasonic sensor units 13 are working, the formed sensor array covers the cross-section of the target tunnel, the beam former 14 communicates with the multiple ultrasonic sensor units 13 to interact with the received ultrasonic signals, and is wirelessly connected to the subway tunnel structure health analysis module 3 through the vehicle-mounted wireless data transceiver module 15, the ultrasonic controller 2 is respectively connected to the autonomous mobile terminal 11, multiple sensor installation platforms 12 and multiple ultrasonic sensor units 13, and the subway tunnel structure health analysis module 3 performs three-dimensional reconstruction of the subway tunnel structure based on the beamforming ultrasonic data of multiple vehicle-mounted ultrasonic sensor array devices and outputs a three-dimensional reconstructed image.

[0044] When the autonomous mobile terminal 11 of the vehicle-mounted ultrasonic sensor array device moves in the target tunnel, the sensor array design of the vehicle-mounted ultrasonic sensor array device can cover the entire cross-section of the tunnel, ensuring the comprehensiveness of monitoring without missing any potential problem areas. The multiple ultrasonic sensor units 13 obtain the 3D spatial information of the target tunnel structure by emitting ultrasonic waves and receiving the reflected signals. The beamformer 14 uses beamforming technology to enhance signals from a specific direction and suppress signals from other directions. Beamforming technology can improve the directionality of the system, allowing the sensor array to distinguish signals from different directions.

[0045] After the beam-formed ultrasonic signal is wirelessly transmitted to the subway tunnel structure health analysis module 3, the subway tunnel structure health analysis module 3 can use 3D imaging technology to achieve three-dimensional imaging reconstruction of the subway tunnel structure. Subsequently, health assessment can be performed based on the three-dimensional imaging reconstruction results to promptly discover potential structural problems, thereby improving the safety of subway operations.

[0046] In embodiment 2, the sensor mounting platform 12 includes a base 122, an electric turntable 123, an electric telescopic rod 124 and a sensor mounting plate 121. The base 122 is detachably mounted on the top of the autonomous mobile terminal 11, the electric turntable 123 is detachably mounted on the base 122, the bottom of the electric telescopic rod 124 is detachably mounted on the rotating part at the top of the electric turntable 123, and the middle part of one side of the sensor mounting plate 121 is detachably mounted on the telescopic rod of the electric telescopic rod 124 through a mounting block.

[0047] The movement adjustment of the electric turntable 123 and the electric telescopic rod 124 can realize the adjustment of the angle and height of the sensor mounting plate 121, so that the ultrasonic signal intensity of the multiple ultrasonic sensor units 13 installed on the sensor mounting plate 121 can be uniform, so that the sensor array formed by the multiple ultrasonic sensor units 13 covers the cross-section of the current tunnel.

[0048] Embodiment 3: If the ultrasonic signal strength fed back by the plurality of ultrasonic sensor units 13 is lower than the set ultrasonic strength threshold, the ultrasonic controller 2 controls the electric turntable 123 and the electric telescopic rod 124 to perform fine-tuning actions respectively until the ultrasonic signal strength fed back by the plurality of ultrasonic sensor units 13 is greater than or equal to the set ultrasonic strength threshold;

[0049] The fine-tuning action means that the electric turntable 123 rotates 1° clockwise or counterclockwise, and the piston rod of the electric telescopic rod 124 rises or falls 1 mm.

[0050] If it is detected that the ultrasonic signal fed back by the ultrasonic sensor unit 13 is missing or the intensity is lower than the threshold, it may indicate that the cross section is not effectively covered. The ultrasonic controller 2 calculates the mechanical instructions that need to be adjusted according to the results of the defect detection and sends them to the electric turntable 123 and the electric telescopic rod 124 to realize the automatic adjustment of the adaptive sensor array.

[0051] Embodiment 4, the ultrasonic sensing unit 13 includes a shell 131, an ultrasonic transmitter 132 and an ultrasonic sensor 133, the shell 131 is detachably mounted on the sensor mounting disk 121, the axis extension line of the shell 131 passes through the center of the sensor mounting disk 121, the ultrasonic transmitter 132 and the ultrasonic sensor 133 are respectively in the shell 131, and the sensor head faces outward, the data output end of the ultrasonic sensor 133 is communicatively connected to the signal input end of the beam former 14, and the ultrasonic controller 2 is communicatively connected to the ultrasonic sensor 133.

[0052] The ultrasonic transmitter 132 can emit ultrasonic signals toward the tunnel structure, and the ultrasonic sensor 133 receives the reflected signals. The data output ends of the multiple ultrasonic sensor units 13 communicate and interact with the beamformer 14 to receive the ultrasonic signals. The beamformer 14 processes the ultrasonic signals based on the beamforming technology. The processed ultrasonic signals are more conducive to three-dimensional reconstruction.

[0053] Embodiment 5, the subway tunnel structure health analysis module 3 includes a computer-side wireless transceiver module 31, a memory 32 and a data analysis computer 33. The computer-side wireless transceiver module 31 is wirelessly connected to the vehicle-mounted wireless data transceiver module 15, the memory 32 is communicatively connected to the computer-side wireless transceiver module 31, and the data analysis computer 33 is communicatively connected to the memory 32. The data analysis computer 33 uses a synthetic aperture focusing imaging method to perform three-dimensional reconstruction of the subway tunnel structure based on beamforming ultrasonic data of multiple vehicle-mounted ultrasonic sensor array devices, outputs a three-dimensional reconstructed image, and evaluates the structural health of the subway tunnel based on the three-dimensional reconstructed image.

[0054] In the sixth embodiment, the autonomous mobile terminal 11 is an AGV electric vehicle.

[0055] The AGV electric car can move precisely in the tunnel, and the battery of the AGV electric car can also power the on-board ultrasonic sensor array device.

[0056] Embodiment 7, a method for monitoring the structural health of a subway tunnel with a vehicle-mounted 3D ultrasonic wave, using a system for monitoring the structural health of a subway tunnel with a vehicle-mounted 3D ultrasonic wave to reconstruct a three-dimensional image of the internal structure of a target tunnel, and evaluating the structural health of the subway tunnel based on the three-dimensional image of the internal structure of the target tunnel, comprising the following steps:

[0057] Step 1, controlling the autonomous mobile terminal 11 to travel along the central axis of the target tunnel, and stopping the ultrasonic data collection action at every set distance;

[0058] Step 2, the ultrasonic controller 2 controls the electric turntable 123 and the electric telescopic rod 124 to perform fine-tuning actions respectively until the ultrasonic signal strengths fed back by the multiple ultrasonic sensor units 13 are all greater than or equal to the set ultrasonic intensity threshold, so that the sensor array formed by the multiple ultrasonic sensor units 13 covers the cross section of the target tunnel;

[0059] Step 3, multiple ultrasonic sensor units 13 are turned on, and the beam former 14 uses beam forming technology to enhance the ultrasonic signal from the target tunnel structure, and sends the enhanced ultrasonic signal data to the subway tunnel structure health analysis module 3 through the vehicle-mounted wireless data transceiver module 15;

[0060] Step 4, the data analysis computer 33 uses a synthetic aperture focusing imaging method to process the beamforming ultrasonic data enhanced by the beamforming technology, and uses the synthetic aperture focusing imaging method to perform three-dimensional reconstruction of the subway tunnel structure and output a three-dimensional reconstructed image;

[0061] Step 5, the autonomous mobile terminal 11 drives to the end of the central axis in the target tunnel to complete the three-dimensional reconstruction images of all cross sections;

[0062] Step 6: The data analysis computer 33 extracts features for health assessment based on the three-dimensional reconstructed images of all cross sections, the features including crack width, volume change and material degradation, and uses the extracted features to assess the health of the tunnel structure.

[0063] In Example 8, in step 3, the calculation formula for beamforming is:

[0064]

[0065] where y ( t ) is the ultrasonic signal output after beamforming, w i is the weight vector of the beamformer; h i( t ) The received signal after signal processing, x i( t ) is a channel receiving signal, s ( t ) is the target signal, a ( θ is the direction vector, w H is the conjugate transpose of w.

[0066] In Example 9, in step 4, the formula of the synthetic aperture focusing imaging method is:

[0067]

[0068] Among them I ( f,θ ) is the imaging result, y ( t ) is the ultrasonic signal output after beamforming, f is the ultrasonic signal frequency, θ is the angle of the ultrasonic signal, and N is the number of ultrasonic signal sampling points.

[0069] In Example 10, in step 6, the formula for evaluating the health of the tunnel structure using the extracted features is:

[0070] H=f ( F 1 , F 2 , …, F n ) ;

[0071] Where H is the health assessment index of the tunnel structure, F 1 , F 2 , …, F n is the feature item extracted from the three-dimensional reconstructed image for health assessment, n is the number of feature items, and f is the evaluation function; the evaluation function is a linear combination, weighted average or machine learning model.

[0072] Based on the health index HH, risk assessment can be performed to determine whether maintenance or reinforcement is needed.

[0073] The risk assessment formula could be:

[0074] R = g(H);

[0075] Among them, R is the risk assessment result, and gg is a function that converts the health index into a risk level.

[0076] Through the above steps and core formulas, the health of the tunnel structure can be evaluated based on the 3D reconstructed image of the tunnel cross section.

[0077] The above are all preferred embodiments of the present invention, and are not intended to limit the protection scope of the present invention. Therefore, any equivalent changes made based on the structure, shape, and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A vehicle-mounted 3D ultrasonic monitoring system for subway tunnel structural health, characterized by: The invention comprises a vehicle-mounted ultrasonic sensor array device, a chip-based ultrasonic controller (2) and a computer-based subway tunnel structure health analysis module (3). The vehicle-mounted ultrasonic sensor array device comprises an autonomous mobile terminal (11), a sensor installation platform (12), a plurality of ultrasonic sensor units (13), a beam former (14) and a vehicle-mounted wireless data transceiver module (15). The bottom of the sensor installation platform (12) is installed on the top of the autonomous mobile terminal (11). The sensor installation platform (12) is provided with a sensor installation plate (121). The plurality of ultrasonic sensor units (13) are respectively installed around the sensor installation plate (121). When the plurality of ultrasonic sensor units (13) are connected to the sensor installation plate (121), the plurality of ultrasonic sensor units (13) are connected to the sensor installation plate (121). 3) When working, the formed sensor array covers the cross section of the target tunnel, the beam former (14) communicates with the plurality of ultrasonic sensor units (13) to exchange the received ultrasonic signals, and is wirelessly connected to the subway tunnel structure health analysis module (3) through the vehicle-mounted wireless data transceiver module (15), the ultrasonic controller (2) is respectively connected to the autonomous mobile terminal (11), the plurality of sensor installation platforms (12) and the plurality of ultrasonic sensor units (13), and the subway tunnel structure health analysis module (3) performs three-dimensional reconstruction of the subway tunnel structure based on the beamforming ultrasonic data of the plurality of vehicle-mounted ultrasonic sensor array devices to output a three-dimensional reconstructed image.

2. The vehicle-mounted 3D ultrasonic monitoring system for subway tunnel structural health according to claim 1 is characterized by: The sensor installation platform (12) comprises a base (122), an electric turntable (123), an electric telescopic rod (124) and a sensor installation plate (121); the base (122) is detachably mounted on the top of the autonomous mobile terminal (11); the electric turntable (123) is detachably mounted on the base (122); the bottom of the electric telescopic rod (124) is detachably mounted on the rotating part at the top of the electric turntable (123); and the middle part of one side of the sensor installation plate (121) is detachably mounted on the telescopic rod of the electric telescopic rod (124) through a mounting block.

3. The vehicle-mounted 3D ultrasonic monitoring system for subway tunnel structural health according to claim 2 is characterized by: If the ultrasonic signal strength fed back by the plurality of ultrasonic sensor units (13) is lower than a set ultrasonic strength threshold, the ultrasonic controller (2) controls the electric turntable (123) and the electric telescopic rod (124) to perform fine adjustment actions respectively until the ultrasonic signal strength fed back by the plurality of ultrasonic sensor units (13) is greater than or equal to the set ultrasonic strength threshold; The fine adjustment action means that the electric turntable (123) rotates 1° clockwise or counterclockwise, and the piston rod of the electric telescopic rod (124) rises or falls 1mm.

4. The vehicle-mounted 3D ultrasonic monitoring system for subway tunnel structural health according to claim 3 is characterized by: The ultrasonic sensing unit (13) comprises a housing (131), an ultrasonic transmitter (132) and an ultrasonic sensor (133); the housing (131) is detachably mounted on a sensor mounting plate (121); an axis extension line of the housing (131) passes through the center of the sensor mounting plate (121); the ultrasonic transmitter (132) and the ultrasonic sensor (133) are respectively located in the housing (131) with the sensor head facing outward; a data output end of the ultrasonic sensor (133) is communicatively connected to a signal input end of a beam former (14); and the ultrasonic controller (2) is communicatively connected to the ultrasonic sensor (133).

5. The vehicle-mounted 3D ultrasonic monitoring system for subway tunnel structural health according to claim 4, characterized in that: The subway tunnel structure health analysis module (3) comprises a computer-side wireless transceiver module (31), a memory (32) and a data analysis computer (33), wherein the computer-side wireless transceiver module (31) is wirelessly connected to a vehicle-mounted wireless data transceiver module (15), the memory (32) is communicatively connected to the computer-side wireless transceiver module (31), and the data analysis computer (33) is communicatively connected to the memory (32). The data analysis computer (33) uses a synthetic aperture focusing imaging method to perform three-dimensional reconstruction of the subway tunnel structure based on beamforming ultrasonic data of multiple vehicle-mounted ultrasonic sensor array devices, outputs a three-dimensional reconstruction image, and evaluates the subway tunnel structure health based on the three-dimensional reconstruction image.

6. The vehicle-mounted 3D ultrasonic monitoring system for subway tunnel structural health according to claim 5, characterized in that: The autonomous mobile terminal (11) is an AGV electric vehicle.

7. A method for monitoring the structural health of a subway tunnel using vehicle-mounted 3D ultrasonic waves, characterized in that: The system for monitoring the structural health of a subway tunnel by using a vehicle-mounted 3D ultrasonic wave according to claim 6 is used to reconstruct a three-dimensional image of the internal structure of a target tunnel, and the structural health of the subway tunnel is evaluated based on the three-dimensional image of the internal structure of the target tunnel, comprising the following steps: Step 1, controlling the autonomous mobile terminal (11) to travel along the central axis of the target tunnel, and stopping the ultrasonic data collection action at every set distance; Step 2, the ultrasonic controller (2) controls the electric turntable (123) and the electric telescopic rod (124) to perform fine-tuning actions respectively until the ultrasonic signal strengths fed back by the plurality of ultrasonic sensor units (13) are all greater than or equal to a set ultrasonic intensity threshold, so that the sensor array formed by the plurality of ultrasonic sensor units (13) covers the cross section of the target tunnel; Step 3, multiple ultrasonic sensor units (13) are turned on, and the beam former (14) uses beam forming technology to enhance the ultrasonic signal from the target tunnel structure, and sends the enhanced ultrasonic signal data to the subway tunnel structure health analysis module (3) through the vehicle-mounted wireless data transceiver module (15); Step 4, the data analysis computer (33) uses a synthetic aperture focusing imaging method to process the beamforming ultrasonic data enhanced by the beamforming technology, and uses the synthetic aperture focusing imaging method to perform three-dimensional reconstruction of the subway tunnel structure and output a three-dimensional reconstructed image; Step 5, the autonomous mobile terminal (11) drives to the end of the central axis in the target tunnel to complete the three-dimensional reconstruction images of all cross sections; Step 6, the data analysis computer (33) extracts features for health assessment based on the three-dimensional reconstructed images of all cross sections, the features including crack width, volume change and material degradation, and uses the extracted features to assess the health of the tunnel structure.

8. The method for monitoring the structural health of a subway tunnel using vehicle-mounted 3D ultrasonic waves according to claim 7, characterized in that: In step 3, the beamforming calculation formula is: where y ( t ) is the ultrasonic signal output after beamforming, w i is the weight vector of the beamformer; h i( t ) The received signal after signal processing, x i( t ) is a channel receiving signal, s ( t ) is the target signal, a ( θ is the direction vector, w H is the conjugate transpose of w.

9. The method for monitoring the structural health of a subway tunnel using vehicle-mounted 3D ultrasonic waves according to claim 8, characterized in that: In step 4, the formula for the synthetic aperture focusing imaging method is: Among them I ( f,θ ) is the imaging result, y ( t ) is the ultrasonic signal output after beamforming, f is the ultrasonic signal frequency, θ is the angle of the ultrasonic signal, and N is the number of ultrasonic signal sampling points.

10. The method for monitoring the structural health of a subway tunnel using vehicle-mounted 3D ultrasonic waves according to claim 9, characterized in that: In step 6, the formula for evaluating the health of the tunnel structure using the extracted features is: H=f ( F1,F2,…,F n ) ; Where H is the health assessment index of the tunnel structure, F1, F2, …, F n is the feature item extracted from the three-dimensional reconstructed image for health assessment, n is the number of feature items, and f is the evaluation function; the evaluation function is a linear combination, weighted average or machine learning model.

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