Steel box girder automatic detection trolley and method based on magnetic attraction

Abstract

The invention discloses a steel box girder automatic detection trolley and method based on magnetic attraction, the trolley comprises a mobile platform, a mounting plate, a camera shooting detection module, an ultrasonic distance measurement module, a control module, a screen and a power supply, the mobile platform comprises magnetic attraction wheels, a coupler, a driving mechanism, a driving support and a connecting plate, and the mounting plate comprises nylon columns. The camera shooting detection module comprises a detection support, a horizontal rotating steering engine, a vertical rotating steering engine, a camera, an illuminating lamp and a rotating plate, the ultrasonic distance measuring module comprises an ultrasonic transmitting end, a rotating support and a steering engine, and the control module comprises a control panel and a circuit board box cover. According to the steel box girder automatic detection trolley and method based on magnetic attraction, welding seam locating can be achieved, the detection efficiency is improved, the risk of missing detection and misjudgment caused by manual detection is reduced, in addition, the device has the autonomous movement capacity, can stably work in the complex environment, meanwhile, a detection report easy to read is generated, and the detection efficiency is improved. And the effects of simplicity and convenience in operation and low maintenance cost can be achieved.

Description

Technical Field

[0001] This invention belongs to the field of steel box girder maintenance and inspection technology, and more specifically, relates to an automatic inspection trolley and method for steel box girders based on magnetic attraction. Background Technology

[0002] Steel box girders, as the core load-bearing structure of transportation engineering projects such as long-span bridges, cross-sea channels, and urban elevated roads, are widely used in modern infrastructure due to their advantages of high strength, high rigidity, and flexible design. However, steel box girders are used in complex outdoor environments for extended periods, bearing multiple effects such as vehicle loads, temperature changes, wind and rain erosion, and marine atmosphere (coastal scenarios). This makes them prone to fatigue cracks, corrosion damage, and weld cracking. If not inspected and repaired in a timely manner, these issues may lead to structural failure and threaten traffic safety. Therefore, regular non-destructive testing of steel box girders is a crucial link in ensuring the durability and safety of engineering structures. The core requirement is to achieve full coverage testing of key components such as the top plate, bottom plate, web plate, welds, and stiffening ribs of the steel box girder, while simultaneously meeting the practical requirements of high-altitude operation safety, adaptation to complex curved surfaces, and a balance between testing efficiency and accuracy.

[0003] Current methods for the maintenance and inspection of steel box girders mainly include manual inspection, inspection vehicle inspection, and crawling robot inspection. Manual inspection relies on personnel entering the box girder, where confined spaces and poor ventilation pose safety hazards, leading to low efficiency, high subjectivity, and a tendency to miss minor defects. Current inspection vehicles include truck-mounted bridge inspection vehicles, suspended platform bridge inspection vehicles, single-sided bridge inspection vehicles, and fixed bridge inspection vehicles. These vehicles can only inspect the external structure of the steel box girder and cannot perform internal inspections, exhibiting significant limitations. Existing internal inspection robots for steel box girders rely on preset paths or manual remote control, lacking autonomous navigation and obstacle avoidance capabilities, making them ill-suited to the complex internal environment and exhibiting low levels of intelligence. Furthermore, most devices are equipped with only a single sensor (such as a vision camera), unable to simultaneously collect multi-dimensional data such as corrosion depth, crack width, and coating thickness. Summary of the Invention

[0004] To address the aforementioned deficiencies or improvement needs of existing technologies, this invention provides an automatic inspection trolley and method for steel box girders based on magnetic attraction. The inspection trolley of this invention utilizes camera detection modules mounted at the four corners of the top of a mounting plate to achieve multi-angle and omnidirectional detection of cracks between the top and bottom plates and longitudinal stiffening ribs of the steel box girder during movement. An ultrasonic ranging module mounted at the bottom of the mounting plate can measure the distance between the inspection trolley and the steel plate in front in real time, providing distance data support for the trolley's autonomous movement. A control module mounted at the center of the top of the moving platform processes the trolley's detection information and outputs correct commands to control the trolley's movement and operation.

[0005] To achieve the above objectives, according to a first aspect of the present invention, an automatic inspection trolley for steel box girders based on magnetic attraction is provided, comprising: The mobile platform that serves as the main body of the detection vehicle, the mounting plate located directly above the mobile platform, the camera detection module connected to the four top corners of the mounting plate by bolts, the ultrasonic ranging module located at the bottom front end of the mounting plate, and the control module located between the mobile platform and the mounting plate and at the top center of the mobile platform. The mobile platform includes a connecting plate, drive brackets located at the four corners of the bottom of the connecting plate, a drive mechanism placed on the drive brackets with its output shaft on the same side as the drive brackets, a coupling connected to the output shaft of the drive mechanism on one side, and a magnetic wheel connected to the other side of the coupling; the drive mechanism drives the magnetic wheel to rotate through the coupling, thereby realizing the forward or backward movement of the detection trolley; The camera detection module includes a detection bracket located on the top of the mounting plate, a horizontal rotating servo motor connected at both ends to the top center of the square base plate of the detection bracket and the conformal mounting seat of the detection bracket, a vertical rotating servo motor connected to the top slot of the conformal mounting seat of the detection bracket, and a rotating plate located at the center of the slot of the conformal mounting seat of the detection bracket and connected to both sides of the slot; the rotating plate can rotate around an axis. The ultrasonic ranging module includes a servo motor located at the bottom front end of the mounting plate and a rotating bracket located at the bottom of the servo motor.

[0006] Furthermore, the magnetic chuck is made of permanent magnet material and contains high-performance neodymium iron boron.

[0007] Furthermore, the drive mechanism employs a DC geared motor to increase the load on the detection trolley.

[0008] Furthermore, the horizontal and vertical rotation servos increase the detection range and angular accuracy of the detection vehicle by adjusting the angles of the two degrees of freedom of the camera detection module.

[0009] Furthermore, the mounting plate also includes nylon columns connected on one side to the four outer corners of the top of the connecting plate and on the other side of the mounting plate.

[0010] Furthermore, the camera detection module also includes a camera located on the upper outer side of the rotating plate and a lighting lamp located on the lower outer side of the rotating plate.

[0011] Furthermore, the ultrasonic ranging module also includes ultrasonic transmitting ends symmetrically distributed on the side of the rotating bracket.

[0012] Furthermore, the control module also includes a circuit board cover disposed between the mobile platform and the mounting plate, and a control board located at the center of the circuit board cover. The circuit board cover has multiple holes for wiring, and the control board has a step-down module for converting the voltage into a 5V input.

[0013] Furthermore, it also includes a screen located at the top center of the mounting plate and a power supply located at the top center of the mounting plate for supplying power to the various modules of the detection vehicle.

[0014] According to a second aspect of the present invention, an operation method for an automatic inspection trolley for steel box girders based on magnetic attraction is provided, which is implemented using an automatic inspection trolley for steel box girders based on magnetic attraction, comprising: S100: After the trolley enters the steel box girder, it starts the ultrasonic ranging module and the camera detection module to scan the internal structure, generate a three-dimensional point cloud map and mark the key detection areas; S200: Based on map information, the topology map method is used to plan the vehicle's driving path. The key nodes of the vehicle's driving path are the transverse partitions and longitudinal ribs at the end of the lane. After the vehicle automatically locates the key nodes, it drives according to the planned path. S300: During driving, the PID algorithm is used to dynamically control the vehicle's driving posture to prevent the vehicle from deviating from its course. S400: The camera inspection module is used to inspect the weld, the YOLOv7 image recognition algorithm is used to perform preliminary analysis of cracks, and the location of cracks is marked by the positioning system to facilitate later maintenance; S500: The inspection trolley is moved to another section of the steel box girder for inspection. Since the trolley is difficult to climb over the diaphragm, it needs to be moved manually. At the same time, the cracks after the inspection are completed are evaluated and repaired.

[0015] In summary, compared with the prior art, the above-described technical solutions conceived by this invention can achieve the following beneficial effects: 1. The inspection trolley of the present invention, through camera inspection modules installed at the four corners of the top of the mounting plate, can detect cracks between the top plate and bottom plate of the steel box girder and the longitudinal stiffening ribs of the trolley from multiple angles and in all directions during the movement of the trolley. Through the ultrasonic ranging module installed at the bottom of the mounting plate, the distance between the inspection trolley and the steel plate in front can be measured in real time to provide distance data support for the autonomous movement of the inspection trolley. Through the control module installed at the center of the top of the mobile platform, the inspection information of the trolley can be processed and the correct instructions can be output to control the movement and operation of the trolley.

[0016] 2. The mobile platform of the present invention connects the magnetic chuck to the drive mechanism via a coupling, so that the drive mechanism drives the magnetic chuck to rotate, thereby realizing the forward or backward movement of the detection trolley. The drive mechanism, the coupling and the magnetic chuck are fixedly mounted on the connecting plate via a drive bracket.

[0017] 3. The camera detection module of the present invention is mounted on the top four corners of the mounting plate by means of the square base plate of the detection bracket. The rotating plate is fixed and kept rotating by means of the contour mounting base of the detection bracket. The camera detection module can be adjusted in two degrees of freedom by means of the rotation servo and the vertical rotation servo, thereby increasing the detection range and angle accuracy.

[0018] 4. The control module of the present invention completes the task of wiring and protecting the control board through a circuit board cover with multiple holes. The power supply voltage is delivered to other structures through the step-down module in the control board. The control board controls the movement of the detection car and the camera detection. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the structure of the automatic steel box girder inspection trolley based on magnetic attraction according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the structure of the automatic inspection trolley moving platform for steel box girders based on magnetic attraction, according to an embodiment of the present invention. Figure 3 This is a schematic diagram of the camera detection module of the automatic steel box girder detection trolley based on magnetic attraction, according to an embodiment of the present invention. Figure 4 This is a schematic diagram of the ultrasonic ranging module of the automatic inspection trolley for steel box girders based on magnetic attraction, according to an embodiment of the present invention. Figure 5 This is a flowchart of the PID algorithm for the automatic detection trolley of the steel box girder based on magnetic attraction, according to an embodiment of the present invention. Figure 6 This is a flowchart of the SLAM system for an automatic inspection trolley of a steel box girder based on magnetic attraction, according to an embodiment of the present invention. Figure 7 This is a flowchart illustrating the workflow of the magnetically-based automatic inspection trolley for steel box girders according to an embodiment of the present invention.

[0020] In all the accompanying drawings, the same reference numerals denote the same technical features, specifically: 1-moving platform, 11-magnetic wheel, 12-coupling, 13-drive mechanism, 14-drive bracket, 15-connecting plate, 2-mounting plate, 21-nylon column, 3-camera detection module, 31-detection bracket, 32-horizontal rotation servo, 33-vertical rotation servo, 34-camera, 35-lighting lamp, 36-rotating plate, 4-ultrasonic ranging module, 41-ultrasonic transmitter, 42-rotating bracket, 43-servo, 5-control module, 51-circuit board cover, 52-control board, 6-screen, 7-power supply. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0022] In the description of the embodiments of the present invention, it should be noted that if terms such as "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of the invention is in use, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. Furthermore, terms such as "first," "second," and "third" are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0023] Furthermore, the use of terms such as "horizontal," "vertical," and "sag" does not imply that the component must be absolutely horizontal or suspended, but rather that it can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal relative to "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0024] In the description of the embodiments of the present invention, "multiple" means at least two.

[0025] In the description of the embodiments of the present invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in the present invention according to the specific circumstances.

[0026] This invention provides an automatic inspection trolley for steel box girders based on magnetic attraction, such as... Figure 1As shown, the system includes a mobile platform 1, a mounting plate 2, a camera detection module 3, an ultrasonic ranging module 4, a control module 5, a screen 6, and a power supply 7. The mobile platform 1 serves as the main body of the automatic inspection trolley. The mounting plate 2 is located directly above the mobile platform 1 and is fixed to the top of the mobile platform 1 by bolts using multiple nylon columns 21 (four in this embodiment). Multiple camera detection modules 3 (four in this embodiment) are bolted to the four corners of the top of the mounting plate 2. The camera detection modules 3 can perform multi-angle and omnidirectional detection of cracks between the top and bottom plates of the steel box girder and the longitudinal stiffening ribs during the trolley's movement. The mounting plate 2 is bolted to the bottom and front of the automatic inspection trolley. An ultrasonic ranging module 4 is installed in a connection manner. The ultrasonic ranging module 4 is used to measure the distance between the detection trolley and the front steel plate in real time to provide distance data support for the autonomous movement of the detection trolley. A control module 5 is installed between the mobile platform 1 and the mounting plate 2, and is installed at the top center of the mobile platform 1. The control module 5 processes the detection information of the trolley and outputs correct instructions to control the movement and operation of the trolley. A screen 6 is installed at the top center of the mounting plate 2. The screen 6 is a touch screen and can be used to set the parameters of the detection trolley. A power supply 7 is installed at the top center of the mounting plate 2. The screen 6 is located in front of the power supply 7. The power supply 7 consists of 6 12V batteries and a battery box, which can be used to power the various modules of the detection trolley. The inspection trolley of this invention uses camera inspection modules installed at the four corners of the top of the mounting plate to detect cracks between the top and bottom plates of the steel box girder and the longitudinal stiffening ribs of the trolley from multiple angles and in all directions during its movement. An ultrasonic ranging module installed at the bottom of the mounting plate can measure the distance between the inspection trolley and the steel plate in front in real time to provide distance data support for the autonomous movement of the inspection trolley. A control module installed at the center of the top of the mobile platform processes the inspection information of the trolley and outputs correct instructions to control the movement and operation of the trolley.

[0027] Specifically, such as Figure 2As shown, the mobile platform 1 includes a magnetic chuck 11, a coupling 12, a drive mechanism 13, a drive bracket 14, and a connecting plate 15. The connecting plate 15 serves as the main body of the mobile platform 1. The connecting plate 15 is a rectangular plate with through holes for gripping at both the front and rear ends. The drive mechanism 13 uses a DC geared motor to increase the load on the detection trolley. The drive mechanism 13 is powered by 12V. Multiple drive mechanisms 13 (four in this embodiment) are mounted on the bottom of the connecting plate 15 via the drive bracket 14 with the output shaft on the outside. At each of the four corners, the drive bracket 14 is located on one side of the output shaft of the drive mechanism 13. A coupling 12 is installed on the output shaft of the drive mechanism 13, and a magnetic chuck 11 is installed on the other side of the coupling 12. The coupling 12 can be fixed to the magnetic chuck 11 using the threaded holes on the magnetic chuck 11. The coupling 12 is fixed to the drive mechanism 13 by a set screw. The magnetic chuck 11 contains high-performance neodymium iron boron, which is a permanent magnet material and can maintain stable adsorption on the steel plate of the steel box girder. The moving platform 1 drives the magnetic chuck 11 to rotate through the drive mechanism 13 to realize the forward or backward movement of the inspection trolley. In this invention, the moving platform connects the magnetic chuck to the drive mechanism through the coupling, and the drive mechanism drives the magnetic chuck to rotate to realize the forward or backward movement of the inspection trolley. The drive mechanism, coupling, and magnetic chuck are fixedly mounted on the connecting plate by the drive bracket.

[0028] Specifically, such as Figure 3 As shown, the camera detection module 3 includes a detection bracket 31, a horizontal rotation servo 32, a vertical rotation servo 33, a camera 34, a lighting lamp 35, and a rotating plate 36. The detection bracket 31 consists of a square base plate and a contour mounting base, serving as the main body of the camera detection module 3. The square base plate of the detection bracket 31 is bolted to the top of the mounting plate 2. One side of the horizontal rotation servo 32 is mounted at the center of the top of the square base plate of the detection bracket 31, and the other side of the horizontal rotation servo 32 is connected to the contour mounting base of the detection bracket 31. The detection bracket 31 has a vertical rotating servo motor 33 installed in the top slot of the contour mounting base. A rotating plate 36 is installed at the center of the slot of the contour mounting base of the detection bracket 31 and connected to both sides of the slot. The rotating plate 36 can rotate around an axis and is located on the side of the vertical rotating servo motor 33. A camera 34 is installed on the upper part of the outer-facing panel of the rotating plate 36, and a lighting lamp 35 is installed on the lower part. The horizontal rotating servo motor 32 and the vertical rotating servo motor 33 can realize the angle adjustment of the two degrees of freedom of the camera detection module 3, increasing the detection range and angle accuracy. In this invention, the camera detection module is installed at the top four corners of the mounting plate by the square base plate of the detection bracket. The rotating plate is fixed and kept rotating by the contour mounting base of the detection bracket. The horizontal rotating servo motor and the vertical rotating servo motor realize the angle adjustment of the two degrees of freedom of the camera detection module, thereby increasing the detection range and angle accuracy.

[0029] Specifically, such as Figure 1 As shown, the mounting plate 2 includes nylon pillars 21, one side of which is connected to the four outer corners of the top of the connecting plate 15 of the mobile platform 1, and the other side of which is mounted on the mounting plate 2.

[0030] Specifically, such as Figure 4 As shown, the ultrasonic ranging module 4 includes an ultrasonic transmitter 41, a rotating bracket 42, and a servo motor 43. The servo motor 43 serves as the main body of the ultrasonic ranging module 4. The servo motor 43 is installed at the bottom front end of the mounting plate 2. The bottom of the servo motor 43 is connected to the top of the rotating bracket 42. The rotating bracket 42 is an L-shaped bracket. Multiple ultrasonic transmitters 41 (two in this embodiment) are symmetrically installed on the side of the rotating bracket 42. By emitting ultrasonic waves through the ultrasonic transmitters 41, the detection vehicle can determine the distance to obstacles in front and take timely action. The servo motor 43 can be used to change the ultrasonic ranging orientation of the detection vehicle, thereby achieving the function of 180° ranging.

[0031] Specifically, such as Figure 1 As shown, the control module 5 includes a circuit board cover 51 and a control board 52. The circuit board cover 51 serves as a protective structure for the control module 5 and is located outside the control board 52. The circuit board cover 51 is installed between the moving platform 1 and the mounting plate 2, and is located at the center of the moving platform 1. The circuit board cover 51 has multiple holes for easy wiring. The control board 52 is installed at the center of the circuit board cover 51 and is equipped with a step-down module that converts the 12V voltage output from the power supply 7 to 5V for the camera detection module 3, the ultrasonic ranging module 4, and the screen 6. The control board 52 is used to control the movement of the detection cart and the camera detection. The control module of this invention uses a circuit board cover with multiple holes to handle wiring and protect the control board. The step-down module within the control board delivers the power supply voltage to other structures, and the control board controls the movement of the detection cart and the camera detection.

[0032] like Figure 5 As shown, during the movement of the detection trolley, a PID algorithm is used to dynamically control the trolley's attitude to prevent it from deviating from its intended path. The PID algorithm is an error-based inertial control algorithm. This system continuously calculates the deviation between the actual distance and the preset safety distance, and generates control signals based on the proportional, integral, and derivative terms of the deviation. This precisely maintains the detection trolley at the center of the track. The PID control equation is as follows: in, Represents the system output value. This represents the measured error value. , , These are the PID parameters, referred to as the proportional, integral, and derivative coefficients, respectively.

[0033] The weld seam is inspected using camera detection module 3, and then the YOLOv7 image recognition algorithm is used to perform preliminary analysis of the crack. The crack location is marked by the positioning system. The YOLOv7 image recognition algorithm extracts and preprocesses the image, and then outputs the data to the YOLOv7 model for inference. After feature extraction, fusion and generation by the YOLOv7 model, the data is output and processed, and finally the detection result is output to screen 6.

[0034] like Figure 6 As shown, starting from the initial position of the detection vehicle, its trajectory is first predicted. Then, the onboard sensors observe the steel box girder structure (such as welds and stiffening rib intersections) to extract various structural feature information. Next, the newly extracted features are correlated with existing data to update the status and determine the maintenance status of the steel box girder. After that, closed-loop detection is carried out. If there is a deviation in the detection results, closed-loop correction is performed. If the requirements are met, a detection report is output. At the same time, the map is continuously expanded during the detection process to improve the digital map of steel box girder maintenance detection. The whole process is repeated to achieve continuous and accurate maintenance detection of steel box girders, providing reliable technical support for the safe operation and maintenance of steel box girders.

[0035] This invention also provides an automatic control method for an automatic inspection trolley for steel box girders based on magnetic attraction, comprising the following steps: First, the two longitudinal stiffening ribs are defined as a lane. The detection vehicle is placed at the starting point of the first lane of the steel box girder to be inspected. The vehicle is started, the camera angle is adjusted, and the feature points of the longitudinal stiffening ribs, diaphragms, and top plate are extracted by visual SLAM algorithm. Combined with the ultrasonic ranging module, a three-dimensional semantic map is generated. The intersection of welds and stiffening ribs is marked as a high-risk detection area. The interior of the steel box girder is divided into logical grids according to lanes, and the center point of the diaphragm is set as a topological node to construct a two-layer topological map.

[0036] During the detection of the car's movement, the camera can capture the edges of the left and right U-ribs in real time, calculate the centerline offset E, and drive the left and right wheel sets through differential drive to drive E close to 0, so that the car can drive stably in the middle of the lane.

[0037] The vehicle is set to travel at a speed of 10 m / min. A high-definition camera records images of the weld seam, and the cracks are identified in real time using the YOLOv7 model. The cracks are classified into three levels according to their severity: Level 1, Level 2, and Level 3. At the same time, the video will also show in real time which lane the vehicle is traveling in and how far it has traveled, which will facilitate accurate location of the cracks and subsequent repairs.

[0038] like Figure 7 As shown, in another embodiment of the present invention, an operation method for an automatic inspection trolley for steel box girders based on magnetic attraction is provided, including the following steps: After the trolley enters the steel box girder, the ultrasonic ranging module 4 and the camera detection module 3 are activated to scan the internal structure (including the top plate, bottom plate, U-rib distribution and transverse diaphragm position), generate a three-dimensional point cloud map and mark key detection areas (such as welds and stiffening rib intersections).

[0039] Based on map information, the topology map method is used to plan the car's driving path. The key nodes of the car's driving path are the transverse partitions and longitudinal ribs at the end of the lane. After the car automatically locates the key nodes, it drives according to the planned path.

[0040] During operation, the PID algorithm is used to dynamically control the vehicle's driving posture to prevent the vehicle from deviating from its course.

[0041] The camera inspection module 3 is used to inspect the weld, and the YOLOv7 image recognition algorithm is used to perform preliminary analysis of the cracks. The location of the cracks is marked by the positioning system to facilitate later maintenance.

[0042] The inspection trolley was moved to another section of the steel box girder for further inspection. Since the trolley had difficulty climbing over the transverse diaphragms, it needed to be moved manually. At the same time, the cracks that were inspected were assessed and repaired.

[0043] In summary, the magnetically-based automatic inspection trolley and method for steel box girders can achieve weld seam positioning, improve inspection efficiency, and reduce the risk of missed detections and misjudgments caused by manual inspection. In addition, the equipment has autonomous movement capabilities, can work stably in complex environments, and generates easy-to-interpret inspection reports. It also achieves the effects of simple operation and low maintenance costs.

[0044] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An automatic inspection trolley for steel box girders based on magnetic attraction, characterized in that, include: The mobile platform (1) that serves as the main body of the detection vehicle, the mounting plate (2) located directly above the mobile platform (1), the camera detection module (3) connected to the four corners of the top of the mounting plate (2) by bolts, the ultrasonic ranging module (4) located at the bottom front end of the mounting plate (2), and the control module (5) located between the mobile platform (1) and the mounting plate (2) and located at the top center of the mobile platform (1). The mobile platform (1) includes a connecting plate (15), a drive bracket (14) located at the four corners of the bottom of the connecting plate (15), a drive mechanism (13) placed on the drive bracket (14) with its output shaft on the same side as the drive bracket (14), a coupling (12) connected to the output shaft of the drive mechanism (13) on one side, and a magnetic chuck (11) connected to the other side of the coupling (12); the drive mechanism (13) drives the magnetic chuck (11) to rotate through the coupling (12), thereby realizing the forward or backward movement of the detection trolley; The camera detection module (3) includes a detection bracket (31) located on the top of the mounting plate (2), a horizontal rotating servo motor (32) connected at both ends to the center of the top of the square base plate of the detection bracket (31) and the contour mounting seat of the detection bracket (31), a vertical rotating servo motor (33) connected to the top slot of the contour mounting seat of the detection bracket (31), and a rotating plate (36) located at the center of the slot of the contour mounting seat of the detection bracket (31) and connected to both sides of the slot; the rotating plate (36) can rotate around an axis; The ultrasonic ranging module (4) includes a servo motor (43) located at the bottom of the front end of the mounting plate (2) and a rotating bracket (42) located at the bottom of the servo motor (43).

2. The automatic inspection trolley for steel box girders based on magnetic attraction according to claim 1, characterized in that, The magnetic chuck (11) is made of permanent magnet material and contains high-performance neodymium iron boron.

3. The automatic inspection trolley for steel box girders based on magnetic attraction according to claim 2, characterized in that, The drive mechanism (13) uses a DC geared motor to increase the load on the detection trolley.

4. The automatic inspection trolley for steel box girders based on magnetic attraction according to claim 3, characterized in that, The horizontal rotation servo (32) and the vertical rotation servo (33) increase the detection range and angle accuracy of the detection trolley by adjusting the angles of the two degrees of freedom of the camera detection module (3).

5. An automatic inspection trolley for steel box girders based on magnetic attraction according to any one of claims 1-4, characterized in that, The mounting plate (2) also includes nylon columns (21) connected on one side to the four outer corners of the top of the connecting plate (15) and on the other side of the mounting plate (2).

6. An automatic inspection trolley for steel box girders based on magnetic attraction according to any one of claims 1-4, characterized in that, The camera detection module (3) also includes a camera (34) located on the upper outer side of the rotating plate (36) and a lighting lamp (35) located on the lower outer side of the rotating plate (36).

7. An automatic inspection trolley for steel box girders based on magnetic attraction according to any one of claims 1-4, characterized in that, The ultrasonic ranging module (4) also includes ultrasonic transmitters (41) symmetrically distributed on the side of the rotating bracket (42).

8. An automatic inspection trolley for steel box girders based on magnetic attraction according to any one of claims 1-4, characterized in that, The control module (5) also includes a circuit board cover (51) located between the mobile platform (1) and the mounting plate (2) and a control board (52) located at the center of the circuit board cover (51). The circuit board cover (51) has multiple holes for wiring, and the control board (52) has a step-down module for converting the voltage into 5V input.

9. An automatic inspection trolley for steel box girders based on magnetic attraction according to any one of claims 1-4, characterized in that, It also includes a screen (6) located at the top center of the mounting plate (2) and a power supply (7) located at the top center of the mounting plate (2) for supplying power to the various modules of the detection vehicle.

10. An operation method for an automatic inspection trolley for steel box girders based on magnetic attraction, characterized in that, The automatic inspection trolley for steel box girders based on magnetic attraction, as described in any one of claims 1-9, is implemented by: S100: After the trolley enters the steel box girder, the ultrasonic ranging module (4) and the camera detection module (3) are activated to scan the internal structure, generate a three-dimensional point cloud map and mark the key detection areas; S200: Based on map information, the topology map method is used to plan the vehicle's driving path. The key nodes of the vehicle's driving path are the transverse partitions and longitudinal ribs at the end of the lane. After the vehicle automatically locates the key nodes, it drives according to the planned path. S300: During driving, the PID algorithm is used to dynamically control the vehicle's driving posture to prevent the vehicle from deviating from its course. S400: The camera detection module (3) is used to detect the weld, and the YOLOv7 image recognition algorithm is used to perform preliminary analysis of the crack. The location of the crack is marked by the positioning system to facilitate later maintenance. S500: The inspection trolley is moved to another section of the steel box girder for inspection. Since the trolley is difficult to climb over the diaphragm, it needs to be moved manually. At the same time, the cracks after the inspection are completed are evaluated and repaired.

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