Ground penetrating radar-based ancient city wall defect detection device and method

Abstract

The invention relates to the technical field of ancient city wall defect detection, in particular to an ancient city wall defect detection device and method based on a ground penetrating radar. The device comprises an upper moving support mechanism, a chain type guide mechanism, an attachment detection mechanism and a lower moving mechanism, the chain type guide mechanism comprises an extension arm and a guide chain which are arranged on the upper moving supporting mechanism, one end of the guide chain is connected with the lower moving mechanism, and the other end of the guide chain is arranged on a winch in the upper moving supporting mechanism; the attaching detection mechanism comprises an attaching walking frame arranged on the guide chain, and a ground penetrating radar unit is arranged at the bottom of the attaching walking frame. Meanwhile, the invention discloses a method based on the device and an ancient city wall defect detection device and method based on the ground penetrating radar, the device and method are suitable for an inclined wall surface, a mixed adsorption unit is adopted, adsorption of a porous and rough non-magnetic surface is achieved, adsorption and movement can be guaranteed, and the surface of an ancient city wall cannot be scratched or polluted at all.

Description

Technical Field

[0001] This invention relates to the field of ancient city wall defect detection technology, and in particular to an ancient city wall defect detection device and method based on ground penetrating radar. Background Technology

[0002] Due to their long history, ancient city walls often exhibit surface or internal hidden defects. These defects are mostly concealed, such as internal rammed earth voids, gaps between bricks and rammed earth, and deep cracks. These defects are not visible to the naked eye but will continue to worsen over time due to rainwater infiltration and temperature changes. Current technology generally uses ground-penetrating radar (GPR) for defect detection, providing reliable data for subsequent repairs. Because ancient city walls are relatively high, GPR is typically used in conjunction with rope traction devices for comprehensive inspection. For example, patent CN218762491 discloses a non-destructive radar scanning device for ancient city walls. However, in actual use, the radar antenna sways significantly, and the slope of ancient city walls makes it difficult to maintain proper contact with the wall surface during comprehensive scanning. Summary of the Invention

[0003] The purpose of this invention is to provide a ground-penetrating radar-based device for detecting defects in ancient city walls, thereby solving the aforementioned technical problems.

[0004] To achieve the above objectives, the present invention provides a ground-penetrating radar-based ancient city wall defect detection device, comprising an upper movable support mechanism, a chain-type guide mechanism, an attachment detection mechanism, and a lower movable mechanism; the chain-type guide mechanism includes an extension arm and a guide chain mounted on the upper movable support mechanism, one end of the guide chain being connected to the lower movable mechanism, and the other end of the guide chain being mounted on a winch in the upper movable support mechanism; the attachment detection mechanism includes an attachment walking frame mounted on the guide chain, and a ground-penetrating radar unit being mounted at the bottom of the attachment walking frame.

[0005] Preferably, the attachment walking frame includes a fixed chassis, a control box is fixed on the upper side of the fixed chassis, a ground-penetrating radar unit is fixed on the lower side of the fixed chassis, and at least four adsorption feet are provided on the fixed chassis. Each adsorption foot includes a first rotating servo motor connected to the fixed chassis. The first rotating servo motor is connected to a second rotating servo motor through a first connector, and the second rotating servo motor is connected to a hybrid adsorption unit through a second connector. The ground-penetrating radar unit, the first rotating servo motor, the second rotating servo motor, and the hybrid adsorption unit are all electrically connected to the control box.

[0006] Preferably, the hybrid adsorption unit includes a negative pressure adsorption component and several wall-climbing claws; The negative pressure adsorption assembly is connected to the negative pressure pump through the solenoid valve ventilation unit in the control box. The negative pressure adsorption assembly is equipped with several adsorption plates arranged in a matrix, and at least one flexible sealing ring is provided on the inner side of the adsorption plate. The bottom of the climbing claw is equipped with a bristle array. One end of several climbing claws is evenly and detachably installed on the circumference of the negative pressure adsorption component, and the other end of several climbing claws is connected to the output end of the second rotating servo motor through a steel wire rope.

[0007] Preferably, the second connector is provided with a detection ring, and the detection ring is equipped with several photoelectric sensors for detecting the unevenness of the wall surface around the mixing adsorption unit. The photoelectric sensor is electrically connected to the control box.

[0008] Preferably, a limiting channel is provided on the top of the attachment frame via a lifting turntable. The lifting turntable is used to determine the direction of the attachment frame and the distance from the wall. A through hole is provided on the limiting channel. A drive motor is fixed on the top of the lifting turntable. The output end of the drive motor meshes with the guide chain in the limiting channel via a sprocket. Both the lifting turntable and the drive motor are electrically connected to the control box.

[0009] Preferably, the ground-penetrating radar unit includes an adjusting spring array mounted on the bottom of a fixed chassis, a ground-penetrating radar antenna mounted on the adjusting spring array, anti-collision plates with an inclination on both sides of the ground-penetrating radar antenna, a flexible protective cover fixed to the bottom of the fixed chassis, and the ground-penetrating radar antenna and the adjusting spring array housed within the flexible protective cover.

[0010] Preferably, the upper moving support mechanism includes an upper moving carriage, on which a folding support frame is provided. One end of the extension arm is hinged to the upper moving carriage. An angle adjusting cylinder is provided on the folding support frame. The telescopic end of the angle adjusting cylinder is slidably provided on the outer wall of the extension arm for adjusting the tilt angle of the extension arm. A sprocket is provided at the other end of the extension arm, and a guide chain meshes with the sprocket.

[0011] Preferably, the lower moving mechanism includes a lower moving carriage, a cleaning swing arm is provided at the bottom of the lower moving carriage, and a tension sensor and an inclinometer are provided at the connection of the guide chain on the lower moving carriage. The tension sensor is used to detect the tension of the guide chain, and the inclinometer is used to detect the tilt angle of the guide chain. The lower moving carriage communicates with the upper moving carriage.

[0012] Preferably, the limiting channel is provided with an electronic safety pin that is positioned opposite to the guide chain, and the electronic safety pin is electrically connected to the control box.

[0013] A method for detecting defects in ancient city walls based on ground-penetrating radar, with the following specific steps: Step S1: Deploy the moving mechanism and adjust the tilt angle and tension of the guide chain; Based on the slope of the ancient city wall to be measured, after unfolding the folding support frame, adjust the extension length of the extension arm, control the winch to make the lower moving mechanism gradually descend until it reaches the bottom of the ancient city wall, adjust the extension length again to make the tilt angle of the guide chain, and at the same time control the winch to adjust the tension of the guide chain. Step S2: Start the attachment detection mechanism to perform scanning vertical defect detection; The direction and distance between the attachment frame and the wall are adjusted by the lifting turntable, and the drive motor is started to make the attachment frame move along the guide chain; at the same time, the adsorption and release of the adsorption feet are controlled to assist the attachment frame in adhering to the wall and moving up and down. During adsorption, the second rotating servo drives the second connector to move closer to the wall, causing the negative pressure adsorption component to adhere to the wall surface. The negative pressure pump is activated to put the negative pressure adsorption component attached to the wall surface into a negative pressure state. At the same time, the steel wire rope is loosened, causing the climbing claw to return to its initial angle and adhere to the wall surface by the van der Waals force. When released, the solenoid valve ventilation unit is activated to release air from the corresponding negative pressure adsorption component. Then, the second rotating servo motor drives the second connecting piece away from the wall, and at the same time, the steel wire rope tightens, causing the climbing claw to lift up and detach from the wall. When the adsorption foot is in the released state, the first rotating servo motor is activated to move the adsorption foot. During the movement of the adsorption foot, the detection ring detects the unevenness of the wall surface and sets the negative pressure adsorption component relative to the wall surface with an unevenness not greater than the set value, and then performs adsorption. Step S3: The upper and lower moving cars move simultaneously, driving the entire device to move laterally, realizing the detection of different lateral positions of the device; when crossing the crenellations of the ancient city wall, the tilt angle of the extension arm is adjusted by the angle adjustment cylinder, and the tension of the guide chain is adjusted by the winch in real time, and the position of the lower moving car is adjusted according to the tilt angle of the guide chain. Step S4: After the detection is completed, the recovery device is used; With the adsorption foot of the attachment detection mechanism away from the wall, the drive motor is started, causing the attachment detection mechanism to return to the top of the ancient city wall, making it easier for staff to retrieve it. After adjusting the extension length of the extension arm, the winch is started to hoist the lower trolley back, folding the folding support frame and retracting the extension arm to the initial position.

[0014] Therefore, the present invention employs the above-mentioned ground-penetrating radar-based ancient city wall defect detection device and method, which has the following beneficial effects: (1) An upper moving support mechanism and a lower moving mechanism are used in conjunction with a chain-type guide mechanism to adjust the angle of the guide chain, so that the attachment detection mechanism is kept parallel to the wall surface, which facilitates subsequent detection. It also realizes detection in both horizontal and vertical directions, which facilitates comprehensive detection of the wall surface.

[0015] (2) In order to be suitable for wall surface testing of ancient city walls, a hybrid adsorption unit was set up to achieve adsorption on porous, rough, non-magnetic surfaces. This ensures stable adsorption and movement without causing scratches or contamination to the surface of the ancient city walls.

[0016] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of a ground-penetrating radar-based ancient city wall defect detection device according to the present invention. Figure 2 To attach a 3D diagram of the testing organization; Figure 3 This is a schematic diagram of the internal structure of the negative pressure adsorption component of the present invention; Figure 4 This is a schematic diagram of the ground-penetrating radar unit structure of the present invention; Figure 5 This is a schematic diagram of the lowering of the mobile vehicle according to the present invention; Figure 6 This is a schematic diagram of the adjustment results when crossing stacks according to the present invention.

[0018] Figure Labels 1. Upper moving support mechanism; 11. Upper moving trolley; 12. Folding support frame; 121. Angle adjustment cylinder; 2. Chain-type guide mechanism; 21. Extension arm; 22. Guide chain; 23. Winch; 3. Attachment detection mechanism; 31. Attachment traveling frame; 311. Fixed chassis; 312. Control box; 32. Ground penetrating radar unit; 321. Adjustable spring array; 322. Ground penetrating radar antenna; 323. Anti-collision plate; 324. Flexible protective cover; 33. Adsorption foot; 331 331. First rotating servo motor; 332. First connecting piece; 333. Second rotating servo motor; 334. Second connecting piece; 34. Mixed adsorption unit; 341. Negative pressure adsorption assembly; 342. Climbing claw; 343. Flexible sealing ring; 344. Steel wire rope; 35. Detection ring; 36. Lifting turntable; 37. Limiting channel; 38. Drive motor; 39. Electronic safety pin; 40. Lower moving mechanism; 41. Lower moving carriage; 42. Cleaning swing arm; 43. Tension sensor; 44. Inclinometer. Detailed Implementation

[0019] In the description of this invention, it should be noted that the terms "upper," "lower," "inner," and "outer," etc., 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 is in use. They are used only for the convenience of describing the 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. Therefore, they should not be construed as limitations on the invention. In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," and "connect" 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 communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0020] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0021] like Figure 1 As shown, a ground-penetrating radar-based ancient city wall defect detection device includes an upper moving support mechanism 1, a chain-type guiding mechanism 2, an attachment detection mechanism 3, and a lower moving mechanism 4.

[0022] The chain-type guide mechanism 2 includes an extension arm 21 and a guide chain 22 mounted on the upper moving support mechanism 1. The chain-type guide mechanism 2 is used to deploy the lower moving mechanism 4 and provide the main traveling power. One end of the guide chain 22 is connected to the lower moving mechanism 4, and the other end of the guide chain 22 is mounted on the winch 23 in the upper moving support mechanism 1. The guide chain 22 is tensioned between the upper moving support mechanism 1 and the lower moving mechanism 4.

[0023] The upper moving support mechanism 1 includes an upper moving carriage 11, on which a folding support frame 12 is installed for easy storage and to provide support for the extension arm 21, enhancing safety during operation. One end of the extension arm 21 is hinged to the upper moving carriage 11, and rests on the folding support frame 12. An angle adjusting cylinder 121 is installed on the folding support frame 12, and the telescopic end of the angle adjusting cylinder 121 is slidably mounted on the outer wall of the extension arm 21 to adjust the tilt angle of the extension arm 21. A sprocket is installed at the other end of the extension arm 21, and a guide chain 22 meshes with the sprocket. The lower moving mechanism 4 includes a lower moving carriage 41. A cleaning swing arm 42 is provided at the bottom of the lower moving carriage 41 (driven by a motor, the swing arm is used to clean up debris in front of the lower moving carriage 41 to prevent debris from affecting the movement or tilt angle of the lower moving carriage 41). A tension sensor 43 and an inclinometer 44 are provided at the connection of the guide chain 22 on the lower moving carriage 41. The tension sensor 43 is used to detect the tension of the guide chain 22, and the inclinometer 44 is used to detect the tilt angle of the guide chain 22. The lower moving carriage 41 communicates with the upper moving carriage 11 to facilitate the simultaneous movement of the lower moving carriage 41 and the upper moving carriage 11 and the transmission of detection data, and to facilitate the control of the winch and the extension arm 21. The lower moving carriage 41 and the upper moving carriage 11 adopt the existing vehicle structure, and the specific model and structure are not limited here.

[0024] The attachment detection mechanism 3 is mounted on the guide chain 22 and can move vertically along the guide chain 22. By simultaneously moving the lower moving carriage 41 and the upper moving carriage 11, the lateral position of the attachment detection mechanism 3 can be adjusted, achieving comprehensive wall surface detection. Figure 2 As shown, the attachment detection mechanism 3 includes an attachment walking frame 31 mounted on a guide chain 22. The attachment walking frame 31 includes a fixed chassis 311. A control box 312 is fixed on the upper side of the fixed chassis 311, and a ground-penetrating radar unit 32 is fixed on the lower side of the fixed chassis 311. At least four adsorption feet 33 are provided on the fixed chassis 311. Each adsorption foot 33 includes a first rotating servo motor 331 connected to the fixed chassis 311. The first rotating servo motor 331 is connected to a second rotating servo motor 333 via a first connector 332. The second rotating servo motor 333 is connected to a hybrid adsorption unit 34 via a second connector 334.

[0025] The ground-penetrating radar unit 32, the first rotating servo motor 331, the second rotating servo motor 333, and the hybrid adsorption unit 34 are all electrically connected to the control box 312 to realize the control of the above-mentioned electronic components and the reception of data. The ground-penetrating radar unit 32, the first rotating servo motor 331, and the second rotating servo motor 333 adopt existing commercially available products.

[0026] The hybrid adsorption unit 34 includes a negative pressure adsorption component 341 and several wall-climbing claws 342. It employs negative pressure adsorption and a biomimetic structure to adhere to the wall, achieving effective adhesion and preventing adhesion failure. The negative pressure adsorption component 341 is connected to a negative pressure pump via a solenoid valve ventilation unit within the control box 312. Figure 3 As shown, the negative pressure adsorption component 341 has multiple adsorption plates arranged in a matrix on its inner side. The adsorption plates have a small contact area, making it easier to adhere to local unevenness (such as small pits or protrusions) on the wall surface. Leakage from a single adsorption plate has little impact on the overall adsorption force, avoiding the concentration of adsorption force. Two flexible sealing rings 343 are located inside the adsorption plates. The flexible sealing rings 343 are made of silicone, rubber, or polyurethane. A soft gel material is embedded on the end face of the flexible sealing ring 343 where it meets the wall surface. Through multiple sealing structures and the soft gel material, tiny gaps can be filled, leaving no residue after removal, making it suitable for extremely rough wall surfaces.

[0027] Meanwhile, a flexible sealing ring 343 is provided. The bottom of the climbing claw 342 is provided with a bristle array. One end of several climbing claws 342 is evenly and detachably installed (screw-mounted) on the circumference of the negative pressure adsorption component 341, which facilitates the replacement of climbing claws 342 in the future. The other end of several climbing claws 342 is connected to the output end of the second rotating servo motor 333 through a steel wire rope 344. During the operation of the second rotating servo motor 333, the angle of the climbing claws 342 is adjusted simultaneously. The climbing claws 342 are provided with shape memory alloy, so that they maintain a suitable angle in the natural state and achieve adsorption with the wall surface through van der Waals forces.

[0028] Because the surface of the ancient city wall is uneven and rough, in order to ensure the adsorption effect of the negative pressure adsorption component 341, a detection ring 35 is set on the second connector 334. Several photoelectric sensors are installed on the detection ring 35 to detect the unevenness of the wall surface around the mixed adsorption unit 34. The photoelectric sensors are electrically connected to the control box 312 so that the adsorption foot 33 falls on a relatively flat position during the movement.

[0029] To achieve engagement with the guide chain 22, a limiting channel 37 is provided on the top of the attachment walking frame 31 via a lifting turntable 36. The lifting turntable 36 is used to determine the direction of the attachment walking frame 31 and its distance from the wall. A through hole is provided on the limiting channel 37. A drive motor 38 is fixed on the top of the lifting turntable 36. The output end of the drive motor 38 engages with the guide chain 22 in the limiting channel 37 via a sprocket. Both the lifting turntable 36 and the drive motor 38 are electrically connected to the control box 312, enabling the attachment walking frame 31 to move along the guide chain 22. The lifting turntable 36 is used to adjust the walking direction of the attachment walking frame 31 and its distance from the wall. An electronic safety pin 39 is provided on the limiting channel 37, which is opposite to the guide chain 22. The electronic safety pin 39 is electrically connected to the control box 312. The electronic safety pin 39 engages with the guide chain 22. In the event of a failure of the drive motor 38, the attachment walking frame 31 is fixed on the guide chain 22 to prevent the attachment walking frame 31 from sliding to the bottom and causing serious damage to the device.

[0030] like Figure 4 As shown, the ground-penetrating radar unit 32 includes an adjusting spring array 321 installed at the bottom of the fixed chassis 311. A ground-penetrating radar antenna 322 is mounted on the adjusting spring array 321. Inclined anti-collision plates 323 are provided on both sides of the ground-penetrating radar antenna 322. During movement, when encountering a protruding part, the springs are compressed under the action of the inclined anti-collision plates 323, thereby adjusting and protecting the ground-penetrating radar antenna 322. A flexible protective cover 324 is fixed to the bottom of the fixed chassis 311 by bolts for easy replacement later. The ground-penetrating radar antenna 322 and the adjusting spring array 321 are set inside the flexible protective cover 324 (rubber) to avoid wear and tear on the ground-penetrating radar antenna 322 from the wall.

[0031] A method for detecting defects in ancient city walls based on ground-penetrating radar, with the following specific steps: Step S1: Deploy the moving mechanism 4 and adjust the tilt angle and tension of the guide chain 22, such as... Figure 5 As shown.

[0032] Based on the slope of the ancient city wall to be measured, after unfolding the folding support frame 12, adjust the extension length of the extension arm 21, control the winch to make the lower moving mechanism 4 gradually descend until it reaches the bottom of the ancient city wall, adjust the extension length again to make the tilt angle of the guide chain 22, and at the same time control the winch to adjust the tension of the guide chain 22.

[0033] Step S2: Start the attachment detection mechanism 3 to perform scanning vertical defect detection.

[0034] The direction and distance of the attachment walking frame 31 from the wall are adjusted by the lifting turntable 36, and the drive motor 38 is started to make the attachment walking frame 31 move along the guide chain 22; at the same time, the adsorption and release of the adsorption feet 33 are controlled to assist the attachment walking frame 31 in adhering to the wall and moving up and down.

[0035] During adsorption, the second rotating servo motor 333 drives the second connector 334 to move closer to the wall, so that the negative pressure adsorption component 341 adheres to the wall surface, and the negative pressure pump is activated to put the negative pressure adsorption component 341 attached to the wall surface into a negative pressure state. At the same time, the steel wire rope 344 is relaxed, so that the climbing claw 342 returns to its initial angle and adheres to the wall surface by the van der Waals force.

[0036] During release, the solenoid valve ventilation unit is activated to release air from the corresponding negative pressure adsorption component 341. Then, the second rotary servo motor 333 drives the second connector 334 away from the wall, while the steel wire rope 344 tightens, causing the climbing claw 342 to lift up and detach from the wall.

[0037] When the adsorption foot 33 is in the released state, the first rotating servo motor 331 is activated to move the adsorption foot 33. During the movement of the adsorption foot 33, the detection ring 35 detects the unevenness of the wall surface and sets the negative pressure adsorption component 341 relative to the wall surface with an unevenness not greater than a set value, and then performs adsorption.

[0038] Step S3: The upper moving carriage 11 and the lower moving carriage 41 move simultaneously, causing the entire device to move laterally, thus enabling the detection of different lateral positions of the device; for example... Figure 6 As shown, when crossing the crenellations of the ancient city wall, the tilt angle of the extension arm 21 is adjusted by the angle adjustment cylinder 121, while the tension of the guide chain 22 is adjusted by the winch 23 in real time, and the position of the lower moving vehicle 41 is adjusted according to the tilt angle of the guide chain 22.

[0039] Step S4: After the detection is completed, the recovery device is used; When the adsorption foot 33 in the attachment detection mechanism 3 is moved away from the wall, the drive motor 38 is started, so that the attachment detection mechanism 3 returns to the top of the ancient city wall, making it easy for the staff to retrieve it. After adjusting the extension length of the extension arm 21, the winch is started to lift the lower moving car 41 back, fold the folding support frame 12, and retract the extension arm 21 to the initial position.

[0040] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A ground penetrating radar-based ancient city wall defect detection device, characterized in that: The application relates to a wall-climbing robot, which comprises an upper moving support mechanism, a chain type guiding mechanism, an adhesion detection mechanism and a lower moving mechanism; the chain type guiding mechanism comprises an extension arm arranged on the upper moving support mechanism and a guiding chain, one end of the guiding chain is connected with the lower moving mechanism, and the other end of the guiding chain is arranged on a winch in the upper moving support mechanism; the adhesion detection mechanism comprises an adhesion walking frame arranged on the guiding chain, and a ground penetrating radar unit is arranged at the bottom of the adhesion walking frame.

2. The ancient city wall defect detection device based on ground penetrating radar according to claim 1, characterized in that: The adhesion walking frame comprises a fixed base plate, a control box is fixed to the upper side of the fixed base plate, a ground penetrating radar unit is fixed to the lower side of the fixed base plate, at least four adsorption feet are arranged on the fixed base plate, the adsorption feet comprise a first rotary rudder connected with the fixed base plate, the first rotary rudder is connected with a second rotary rudder through a first connecting piece, and the second rotary rudder is connected with a mixed adsorption unit through a second connecting piece. The ground penetrating radar unit, the first rotary rudder, the second rotary rudder and the mixed adsorption unit are electrically connected with the control box.

3. The ground penetrating radar-based ancient city wall defect detection device according to claim 2, characterized in that: The mixed adsorption unit comprises a negative pressure adsorption assembly and a plurality of wall-climbing claws. The negative pressure adsorption assembly is connected with a negative pressure pump through an electromagnetic valve ventilation unit in the control box, a plurality of adsorption discs arranged in a matrix are arranged in the negative pressure adsorption assembly, and at least one flexible sealing ring is arranged on the inner side of the adsorption disc. The bottom of the wall-climbing claw is provided with a bristle array, one end of the plurality of wall-climbing claws is uniformly and detachably arranged on the circumferential side of the negative pressure adsorption assembly, and the other end of the plurality of wall-climbing claws is connected with the output end of the second rotary rudder through a steel wire rope.

4. The ground penetrating radar-based ancient city wall defect detection device according to claim 3, characterized in that: A detection ring is arranged on the second connecting piece, a plurality of photoelectric sensors are arranged on the detection ring, and the photoelectric sensors are used for detecting the concave-convex degree of the wall surface around the mixed adsorption unit. The photoelectric sensors are electrically connected with the control box.

5. The ground penetrating radar-based ancient city wall defect detection device according to claim 4, characterized in that: A limiting channel is arranged on the top of the adhesion walking frame through a lifting turntable, the lifting turntable is used for the direction of the adhesion walking frame and the distance from the wall surface, a through hole is arranged on the limiting channel, a driving motor is fixed to the top of the lifting turntable, and the output end of the driving motor is engaged with a guiding chain in the limiting channel through a chain wheel. The lifting turntable and the driving motor are electrically connected with the control box.

6. The ground penetrating radar-based ancient city wall defect detection device according to claim 5, characterized in that: The ground penetrating radar unit comprises an adjusting spring array arranged at the bottom of the fixed base plate, a ground penetrating radar antenna is arranged on the adjusting spring array, and anti-collision plates arranged in an inclined mode are arranged on the two sides of the ground penetrating radar antenna; a flexible protective cover is fixed to the bottom of the fixed base plate, and the ground penetrating radar antenna and the adjusting spring array are arranged in the flexible protective cover.

7. The ground penetrating radar-based ancient city wall defect detection device according to claim 6, characterized in that: The upper moving support mechanism comprises an upper moving vehicle, a folding support frame is arranged on the upper moving vehicle, one end of the extension arm is hinged to the upper moving vehicle, an angle adjusting cylinder is arranged on the folding support frame, the telescopic end of the angle adjusting cylinder is slidingly arranged on the outer wall of the extension arm, and the angle adjusting cylinder is used for adjusting the inclination angle of the extension arm; the other end of the extension arm is provided with a chain wheel, and the guiding chain is engaged with the chain wheel. 8.The ground penetrating radar-based ancient city wall defect detection device according to claim 7, characterized in that: The lower moving mechanism comprises a lower moving vehicle, a cleaning swing arm is arranged at the bottom of the lower moving vehicle, a tension sensor and an inclinometer are arranged at the connecting position of the guiding chain on the lower moving vehicle, the tension sensor is used for detecting the tension of the guiding chain, the inclinometer is used for detecting the inclination angle of the guiding chain, and the lower moving vehicle communicates with the upper moving vehicle. 9.The ground penetrating radar-based ancient city wall defect detection device according to claim 8, characterized in that: An electronic safety pin is arranged on the limiting channel and opposite to the guiding chain, and the electronic safety pin is electrically connected with the control box.

10. The method of detecting defects in ancient city walls based on ground penetrating radar according to claim 9, characterized in that, The specific steps are as follows: Step S1: put down the moving mechanism and adjust the inclination angle and tension of the guide chain; According to the slope of the ancient city wall to be tested, adjust the extension arm length after unfolding the folding support frame, control the winch to make the lower moving mechanism gradually descend until reaching the bottom of the ancient city wall, and adjust the extension length again to make the inclination angle of the guide chain, and control the winch to adjust the tension of the guide chain; Step S2: start the adhesion detection mechanism for scanning vertical defect detection; Adjust the direction and distance of the adhesion walking frame from the wall surface by the lifting turntable, start the driving motor to make the adhesion walking frame move along the guide chain; at the same time, control the suction and release of the suction feet to help the adhesion walking frame adhere to the wall surface and move up and down; When suctioning, the second rotary rudder drives the second connecting piece to approach the wall, so that the negative pressure suction assembly adheres to the wall surface, and the negative pressure pump is started to make the negative pressure suction assembly adhered to the wall surface in a negative pressure state, and the steel wire rope is loosened, so that the wall climbing claws restore the initial angle and are adsorbed on the wall surface by the van der waals force; When releasing, the electromagnetic valve ventilation unit is started to bleed air to the corresponding negative pressure suction assembly, and then the second rotary rudder drives the second connecting piece to move away from the wall, and the steel wire rope is tightened, so that the wall climbing claws are raised to separate from the wall surface; The suction feet in the release state are started by the first rotary rudder to make the suction feet move, and the detection ring detects the concave-convex degree of the wall surface during the movement of the suction feet, and the negative pressure suction assembly is arranged opposite to the wall surface with a concave-convex degree not greater than a set value, and is adsorbed; Step S3: the upper moving vehicle and the lower moving vehicle move simultaneously, drive the device to move horizontally as a whole, realize the detection of different horizontal positions of the device; when crossing the battlements of the ancient city wall, adjust the inclination angle of the extension arm by the angle adjusting cylinder, and at the same time, adjust the tension of the guide chain by the winch in real time, and adjust the position of the lower moving vehicle according to the inclination angle of the guide chain; Step S4: after detection, recover the device; The suction feet in the adhesion detection mechanism move away from the wall surface, the driving motor is started to make the adhesion detection mechanism return to the top of the ancient city wall, so as to facilitate the recovery of the device by the staff, the extension arm length is adjusted, the winch is started, the lower moving vehicle is hoisted, the folding support frame is folded, and the extension arm is retracted to the initial position.

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