A box girder crack detection robot and detection method

Abstract

The present invention relates to a box girder crack detection robot and detection method, belonging to the field of robot visual inspection technology. The robot and detection method include a remote-controlled vehicle, and magnetic devices are provided at the front and rear ends of the vehicle chassis. The first magnetic device is located at the front end of the vehicle chassis, and the second magnetic device is located at the rear end of the vehicle chassis. The magnetic devices include a base, a movable shaft, a driven gear, a connecting rod, a magnetic plate, a control motor, and a driving gear. The remote-controlled vehicle is provided with a first and a second angle measuring device, and a control terminal can control the rotation of the control motors of the first and second magnetic devices based on the angles monitored by the first and second angle measuring devices. A visual recognition device for capturing images of the inner surface of the box girder is fixedly mounted on the upper surface of the vehicle chassis. The robot and detection method are capable of detecting cracks on the inner surface of the box girder, and the angle of the magnetic plate can be adjusted to ensure magnetic attraction to the box girder cavity surface.

Description

Technical Field

[0001] The present invention belongs to the technical field of robot vision detection, and in particular relates to a crack detection robot and a detection method for a box girder. Background Art

[0002] Box girder is a commonly used structural form in bridge engineering. Common box girder types include prestressed reinforced concrete box girder and steel box girder.

[0003] A steel box girder is primarily composed of a top plate, two webs, and a bottom plate. These form a box girder cavity. Generally, the surface of the box girder cavity is considered the inner surface, while the surface outside the box girder cavity is considered the outer surface.

[0004] For steel box girders, they need to undergo a full surface inspection before being put into use to check for cracks, damage and corrosion.

[0005] The meaning of full surface inspection is to inspect both the inner and outer surfaces of the box girder. The meaning of surface inspection is to rely on the human eye to visually observe whether there are cracks on the surface of the steel box girder.

[0006] Since the external space of the box girder is large, it is convenient for inspectors to stand, so it is relatively convenient for inspectors to conduct surface inspections on the outer surface of the box girder, and the inspectors are not constrained by space. However, the cavity size of the box girder is generally small. For steel box girders with a span of less than 40m, the height of the box girder cavity is less than 1.8m, which makes it difficult for inspectors to stand upright and enter the box girder cavity. For steel box girders with a span of less than 30m, the height of the box girder cavity is even less than 1.2m, which makes it impossible for inspectors to enter the box girder cavity. Therefore, it is relatively inconvenient to inspect the cavity surface of the box girder. It is necessary to design a crack detection robot and detection method for the box girder that can perform surface inspections on the cavity surface of the box girder. Summary of the Invention

[0007] A crack detection robot and detection method for a box girder of the present invention can perform surface detection on the cavity surface of a steel box girder without requiring detection personnel to enter the steel box girder.

[0008] A crack detection robot for a box girder of the present invention includes a remote-controlled vehicle, wherein the remote-controlled vehicle is arranged to move in an X direction; the remote-controlled vehicle includes a vehicle chassis, front wheels, and rear wheels, wherein the drive shaft axes of the front wheels and rear wheels are arranged in a Y direction, and the X direction is perpendicular to the Y direction; a magnetic device is provided at both the front and rear ends of the vehicle chassis, wherein the first magnetic device is located at the front end of the vehicle chassis, and the second magnetic device is located at the rear end of the vehicle chassis; and the magnetic device is located on the lower surface of the vehicle chassis;

[0009] The magnetic device includes:

[0010] A base, fixed to the lower surface of the vehicle chassis;

[0011] The movable shaft is rotatably connected to the base and can rotate relative to the base around its own axis, with the axis of the movable shaft being along the Y direction;

[0012] A driven gear is fixedly connected to the movable shaft, and the axis of the driven gear coincides with the axis of the driven gear;

[0013] A connecting rod, one end of which is fixed to the side surface of the movable shaft, and the axis of which is arranged along the radial direction of the movable shaft;

[0014] The magnetic plate is a permanent magnet connected to the other end of the connecting rod;

[0015] The control motor is a servo motor, used to rotate the movable shaft; the control motor is electrically connected to the control terminal;

[0016] The driving gear is fixed to the rotating shaft of the control motor, and the axis of the driving gear coincides with the axis of the control motor; the driving gear is meshed with the driven gear;

[0017] The remote control vehicle is provided with a first angle measuring device and a second angle measuring device, both of which are electrically connected to the control terminal. The control terminal can control the rotation of the control motors of the first magnetic device and the second magnetic device according to the angles monitored by the first angle measuring device and the second angle measuring device.

[0018] A visual recognition device for capturing images of the inner surface of the box beam is fixedly installed on the upper surface of the vehicle chassis.

[0019] Furthermore, the first angle measuring device includes three laser rangefinders. The laser emission points of the three laser rangefinders of the first angle measuring device are respectively point 1, point 2, and point 3. The laser emission directions of the three laser rangefinders of the first angle measuring device are along the X direction and facing forward. The plane formed by point 1, point 2, and point 3 is plane Q. The X direction is perpendicular to plane Q. When observed in the X direction, point 1, point 2, and point 3 are not collinear.

[0020] The second angle measuring device also includes three laser rangefinders. The laser emission points of the three laser rangefinders of the second angle measuring device are respectively point four, point five, and point six. The laser emission directions of the three laser rangefinders of the second angle measuring device are perpendicular to the vehicle floor and facing downward; the plane formed by points four, five, and six is ​​assumed to be plane M, and plane M is parallel to the plane where the vehicle floor is located. When observed from a perspective perpendicular to plane M, points four, five, and six are not collinear; the first angle measuring device and the second angle measuring device are both electrically connected to the control terminal.

[0021] Furthermore, the visual recognition device includes:

[0022] A first rotating motor, wherein the non-rotating shaft end is fixed to the upper surface of the vehicle chassis; the rotating shaft of the first rotating motor is perpendicular to the plane of the vehicle chassis; and the first rotating motor is electrically connected to the control terminal;

[0023] a mounting plate fixed to the rotating shaft of the first rotating motor;

[0024] Two brackets, fixed on the upper surface of the mounting plate;

[0025] The mounting shaft is rotatably connected to the two brackets, and the axis of the mounting shaft is parallel to the plane where the chassis is located;

[0026] A second rotating motor, used to rotate the mounting shaft; electrically connected to the control terminal;

[0027] Camera, mounted on the mounting shaft.

[0028] Furthermore, the two laser rangefinders corresponding to point one and point two are at the same height.

[0029] The two laser rangefinders corresponding to point 1 and point 2 are at the same height. The control terminal can indicate that the robot's forward direction X direction is parallel to the end face of the box beam by making the two laser rangefinders corresponding to point 1 and point 2 at the same height.

[0030] Furthermore, a lighting system is installed on the vehicle chassis, and the lighting system is electrically connected to the control terminal, and the control terminal can control the lighting system to change the brightness.

[0031] The lighting system can provide light. When the visual recognition device takes an image, the image will not be too dark due to the presence of the lighting system, which is more conducive to identifying cracks.

[0032] Furthermore, a box girder crack detection method, based on the box girder crack detection robot according to claim 4, comprises the following steps:

[0033] S1: Adaptation orientation;

[0034] The specific steps include:

[0035] S1.1: The operator places the robot from one end of the box girder on one of the surfaces of the box girder cavity, ensuring that the robot's front and rear wheels are simultaneously placed on one of the surfaces of the box girder cavity; and ensure that the front of the robot faces the other surface of the box girder cavity;

[0036] S1.2: After the operator turns on the robot, the control terminal controls the three laser rangefinders in the first angle measurement device to emit lasers once. The lasers from the three laser rangefinders illuminate the other surface in step S1.1 and are then reflected. The three laser rangefinders each measure the distance to the other surface, and the control terminal obtains the distances monitored by the three laser rangefinders.

[0037] S1.3: Determine whether the distances between the two laser rangefinders at the same height in the first angle measuring device are equal, and determine whether the orientation adaptation is complete;

[0038] S1.3.1: If the distances between the two laser rangefinders at the same height in the first angle measuring device are not equal, and orientation adaptation is not complete, the control terminal controls the robot to adjust its direction accordingly. Adjusting the direction means: the control terminal controls the robot to rotate along the plane of the chassis. Repeat step S1.3.1, and the control terminal continuously controls the three laser rangefinders in the first angle measuring device to emit lasers and measure the distance to another surface until the distances between the two laser rangefinders at the same height are equal. At this point, orientation adaptation is complete, and the robot no longer rotates along the plane of the chassis.

[0039] S1.3.2: If the distances between the two laser rangefinders at the same height are equal, the adaptation is complete and the robot no longer rotates along the plane of the chassis.

[0040] S2: Adaptation angle between the first magnetic device and the second magnetic device;

[0041] The specific steps include:

[0042] S2.1: Determine the angle α between the plane of the vehicle chassis and another surface in front of it;

[0043] After orientation adaptation is completed, the control terminal continuously controls the three laser rangefinders of the first angle measurement device to emit lasers multiple times at a designed frequency. Each time the three lasers hit another surface and reflect, the first magnetic device calculates the angle α between the other surface in front of the robot and the robot chassis based on the distances monitored by the three laser rangefinders. During this laser emission, the distances to the other surface in front monitored by the three laser rangefinders are H1, H2, and H3, respectively, where H1=H2.

[0044] S2.2: Determine the angle β between the chassis plane and the surface with which the rear wheels come into contact;

[0045] The control terminal continuously controls the three laser rangefinders of the second magnetic device to emit lasers multiple times at a designed frequency. Each time the three lasers hit the surface that the rear wheel contacts and are reflected, the second magnetic device calculates the angle β between the plane of the vehicle chassis and the surface that the rear wheel contacts based on the distance monitored by the three laser rangefinders. If the surface that the rear wheel contacts is parallel to the vehicle chassis surface, the angle β = 0.

[0046] S2.3: Calculate the angle of the second magnetic device; determine the state of the first magnetic device and determine the angle of the first magnetic device;

[0047] The specific steps include:

[0048] S2.3.1: Calculate the angle of the second magnetic device. Looking in the Y direction, let A' be the end of the magnetic plate in the second magnetic device that is away from the active axis, and O' be the point where the active axis 9 is located. Draw a ray parallel to the chassis from O' toward the rear of the vehicle chassis, with B' on that ray. Then, ∠A'O'B' = 90 - β.

[0049] S2.3.2: Observing in the Y direction, let point A be the end of the magnetic plate in the first magnetic device away from the active axis, point O be the active axis, and point B be a point on a ray from point O toward the forward direction. If H1, H2, and H3 are all greater than or equal to the set threshold R, the robot's front end is far from the other surface, and the first and second magnetic devices maintain the same angle, that is, ∠AOB = ∠A'O'B' = 90 - β.

[0050] S2.3.3: If any of H1, H2, and H3 is less than the threshold R, the robot front end is close to the other surface, then ∠AOB = 90-α;

[0051] S3: The operator controls the robot via the control terminal to advance a distance D and then stop. During the advancement, the control terminal executes S2, controlling the first magnetic device and the second magnetic device to adapt their angles in the manner described in S2.

[0052] S4: After the robot stops, the operator rotates the first rotary motor and the second rotary motor in the visual recognition device through the control terminal. The camera automatically adjusts the focus and captures an image of the box girder surface. The visual recognition device identifies cracks using image recognition technology. If cracks are identified, the visual recognition device sends the information to the control terminal. A display connected to the control terminal displays the cracks.

[0053] S5: Repeat S3-S4 until the robot moves one circle along the end face of the box girder. Because the distance of one circle of the box girder end face is a known quantity, the operator can determine whether the robot has completed one circle by multiplying the distance D of each movement by the number of movements. When the robot moves one circle along the end face of the box girder, the operator stops moving the robot in the forward direction and the visual recognition device captures an image of one circle of the box girder end face.

[0054] S6: The operator sends a lateral movement command to the robot through the control terminal, and the control terminal causes the robot to move horizontally for a distance N in a direction perpendicular to the end face of the box beam and then stop. The robot continues to move around the inner cavity of the box beam once more, and captures images of the inner cavity of the box beam in the same manner as in steps S3 and S4.

[0055] S7: Repeat S6 until the robot moves out from the other end of the box beam and completes the entire surface inspection of the inner cavity surface of the box beam.

[0056] Beneficial effects

[0057] This robot can move on the inner surface of the box beam, and when the front wheels and rear wheels are on different surfaces of the box beam inner cavity respectively, the two magnetic devices can control the angles respectively through the control terminal, so that the two magnetic devices are magnetically attracted to the corresponding inner surfaces of the box beam respectively, so that the magnetic plate and the inner surface of the box beam are as close as possible to ensure sufficient magnetic force. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] Figure 1 This is a schematic diagram of the overall structure of the robot;

[0059] Figure 2 This is a top view of the robot chassis and wheels;

[0060] Figure 3 It is a structural diagram of the magnetic device;

[0061] Figure 4 It is a structural diagram of a visual recognition device;

[0062] Figure 5 This is a schematic diagram of the position of the robot when it is on two adjacent surfaces of the cross-frame box beam;

[0063] Figure 6 is a distribution position diagram of three laser rangefinders of the first angle measuring device;

[0064] Figure 7 This is a schematic diagram of the robot placed on the bottom plate of the box beam;

[0065] Figure 8 This is a schematic diagram showing the angle between the first magnetic device of the robot and the front plane;

[0066] Figure 9 This is a schematic diagram of the angle of the plane where the second magnetic device of the robot contacts the rear wheel.

[0067] 1. Chassis; 2. First magnetic device; 3. Second magnetic device; 4. First angle measuring device; 5. Second angle measuring device; 6. Visual recognition device; 7. Lighting system; 8. Base; 9. Movable shaft; 10. Driven gear; 11. Connecting rod; 12. Magnetic plate; 13. Control motor; 14. Driving gear; 15. First rotating motor; 16. Mounting plate; 17. Bracket; 18. Mounting shaft; 19. Camera DETAILED DESCRIPTION

[0068] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of them. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention. Example

[0069] See Figure 1 A crack detection robot for a box girder includes a remote control car, which is connected to a control terminal by a wired manner. An operator sends a movement signal to the remote control car through the control terminal and manually controls the remote control car to move forward or sideways.

[0070] See Figure 2 The remote control car belongs to the prior art. The remote control car includes a chassis 1, two front wheels and two rear wheels. Both the front wheels and the rear wheels adopt Mecanum wheels. Assume that the remote control car of this embodiment is placed on a horizontal plane, the chassis 1 is a rectangular plate, and the chassis 1 is rectangular when viewed from above. Let the direction of the drive shaft of the front wheel or the rear wheel of the remote control car be the Y direction, and one of the sides of the chassis 1 is parallel to the Y direction; let the direction perpendicular to the Y direction be the X direction, and let the positive direction of the X direction be the aforementioned forward direction, that is, Figure 1 The left side is the front, and the negative direction is the back, that is, Figure 1 The middle right side is the back. Figure 1 The direction inward of the paper is the positive direction of the Y direction, that is, the aforementioned lateral movement direction.

[0071] From a top view, let P1 be the front end of the front wheel, and P2 be the front end of the chassis 1. P1 is located in front of P2. Similarly, let m1 be the rear end of the rear wheel, and m2 be the rear end of the chassis 1. M1 is located behind m2. This design is useful when the remote control car moves forward in the X direction, and the front and rear wheels of the remote control car are located on two adjacent surfaces of the box beam cavity, that is, Figure 5 When the front and rear ends of the chassis 1 are in contact with the movement of the remote control car, it can be ensured that the front and rear wheels of the remote control car are always in contact with the surface of the box beam cavity, and the front and rear ends of the non-chassis 1 are in contact with the surface of the box beam cavity.

[0072] Two magnetic devices are installed on the lower surface of the vehicle chassis 1. The magnetic devices are used to maintain magnetic attraction between the remote control car and the inner wall of the box beam cavity, thereby ensuring that the remote control car does not fall on the inner wall of the box beam cavity and can also meet the friction required for the movement of the remote control car. The two magnetic devices are respectively arranged on the front and rear end lower surfaces of the vehicle chassis 1.

[0073] See Figure 3 , the magnetic device includes:

[0074] The base 8 is mounted on the lower surface of the vehicle chassis 1 by means of bolts.

[0075] The movable shaft 9 is passed through the base 8. The base 8 is provided with a hole for the movable shaft 9 to pass through. The axis of the movable shaft 9 is parallel to the axis of the drive shaft of the wheel, that is, the axis of the movable shaft 9 is along the Y direction. The movable shaft 9 is connected to the base 8 by means of a bearing. The movable shaft 9 can rotate around its own axis relative to the base 8.

[0076] The driven gear 10 has a circular hole in the middle. The driven gear 10 is sleeved on the movable shaft 9 via the circular hole. The driven gear 10 and the movable shaft 9 are welded and fixed. The axis of the driven gear 10 coincides with the axis of the movable shaft 9.

[0077] One end of the connecting rod 11 is welded and fixed to the side of the movable shaft 9, and the axis of the connecting rod 11 is arranged along the radial direction of the movable shaft 9. When designing the connecting rod 11, ensure that the connecting rod 11 does not interfere with the driven gear 10. In this embodiment, two connecting rods 11 are provided.

[0078] The magnetic plate 12 is a permanent magnet in the shape of a plate. In this embodiment, the magnetic plate 12 is an artificial permanent magnet, such as a neodymium magnet. The magnetic plate 12 is bonded to the other end of the connecting rod 11 by glue.

[0079] The control motor 13, with its non-rotating shaft end bolted to the base 8, is a small servo motor with a self-locking function when powered off. Furthermore, the servo motor can precisely control its rotation angle in response to a control signal from the control terminal, thereby ensuring that the magnetic plate 12 generates magnetic attraction at a set angle with the cavity surface of the corresponding box girder. The control motor 13 is electrically connected to the control terminal via a wired connection, and the control terminal automatically controls the rotation angle of the control motor 13 based on the corresponding control signal. The two magnetic devices are controlled separately by the control terminal, and they do not interfere with each other.

[0080] The driving gear 14 has a circular hole in the middle. The driving gear 14 is sleeved on the rotating shaft of the control motor 13 by means of the circular hole. The driving gear 14 is welded and fixed to the rotating shaft of the control motor 13. The axis of the driving gear 14 coincides with the axis of the rotating shaft of the control motor 13. The driving gear 14 is meshed with the driven gear 10.

[0081] The control motor 13 of the corresponding magnetic attraction device can achieve the rotation of the magnetic attraction plate 12. The specific operation process is as follows: the control terminal sends a corresponding control signal, which causes the control motor 13 to rotate the corresponding angle. The control motor 13 rotates the driven gear 10 through the driving gear 14. The driven gear 10, the movable shaft 9, the connecting rod 11, and the magnetic attraction plate 12 rotate as a whole around the axis of the movable shaft 9 relative to the base 8. Through this rotation, the magnetic attraction plate 12 can adaptively generate magnetic attraction with the corresponding surface of the box beam cavity, ensuring sufficient magnetic attraction between the remote control vehicle and the box beam cavity surface. The magnetic attraction plate of this solution does not directly contact and attract the inner surface of the box beam cavity.

[0082] The magnetic device located at the front end of the vehicle chassis 1 is referred to as the first magnetic device 2, and the other magnetic device located at the rear end of the vehicle chassis 1 is referred to as the second magnetic device 3. A first angle measuring device 4 is mounted on the front upper surface of the vehicle chassis 1, and a second angle measuring device 5 is mounted on the rear lower surface of the vehicle chassis 1. The first angle measuring device 4 is electrically connected to a control terminal via a wired connection, and the second angle measuring device 5 is also electrically connected to the control terminal via a wired connection. The control terminal controls the first and second magnetic devices 2 and 3 to different angles based on the angles monitored by the first and second angle measuring devices 4 and 5, respectively.

[0083] See Figure 1 Specifically, the first angle measuring device 4 includes at least three laser rangefinders, all fixedly mounted on the upper surface of the vehicle chassis 1. This embodiment employs three laser rangefinders. The lasers emitted by the three laser rangefinders of the first angle measuring device 4 are all along the X-direction, and all three lasers are directed toward the front of the vehicle. The laser emission points of the three laser rangefinders are respectively designated as point 1, point 2, and point 3. The plane formed by points 1, 2, and 3 is designated as plane Q, and the X-direction is perpendicular to plane Q. Viewed in the X-direction, points 1, 2, and 3 are not collinear. The three laser rangefinders are electrically connected to the control terminal.

[0084] In this embodiment, see Figure 6 The two laser rangefinders corresponding to points 1 and 2 (laser rangefinder 1 and laser rangefinder 2) are at the same height, while the two laser rangefinders corresponding to point 3 are at a higher height than the two laser rangefinders corresponding to points 1 and 2. The purpose of deploying these three laser rangefinders is to ensure that, when the two laser rangefinders corresponding to points 1 and 2 are at the same height, the distances measured by the laser rangefinders corresponding to points 1 and 2 are equal, regardless of the remote control car's position, indicating that the remote control car's X direction is parallel to the end face of the box girder. If the distances measured by the laser rangefinders corresponding to points 1 and 2 are not equal, indicating that the remote control car's X direction is not parallel to the end face of the box girder, the control terminal will automatically control the remote control car to turn along the plane of the remote control car chassis, restoring the distances measured by the two corresponding laser rangefinders corresponding to points 1 and 2 to be equal, and restoring the remote control car's X direction to the end face of the box girder.

[0085] Similarly, the second angle measuring device 5 also includes at least three laser rangefinders, each fixedly mounted on the lower surface of the vehicle chassis 1. This embodiment employs three laser rangefinders, each emitting laser light perpendicular to the vehicle floor and pointing downward. The laser emission points of the three laser rangefinders are designated as points 4, 5, and 6. The plane formed by points 4, 5, and 6 is designated as plane M. Plane M is parallel to the plane of the vehicle chassis. When viewed from a perspective perpendicular to plane M, points 4, 5, and 6 are not collinear. The three laser rangefinders are electrically connected to the control terminal.

[0086] Assume that the remote control car has been placed in the aforementioned manner, that is, the forward direction of the remote control car is parallel to the end face of the box beam. And assume that the front and rear wheels of the remote control car are placed on the same surface of the box beam cavity at the same time. The position diagram of the remote control car at this time is as follows Figure 7 shown. Figure 7 It is assumed that the front and rear wheels of the remote control car are in contact with the bottom plate surface of the box beam cavity. If the bottom plate of the box beam cavity is set horizontally, the chassis of the remote control car is set horizontally. In other cases, the front and rear wheels of the remote control car are in contact with other surfaces of the box beam cavity at the same time. The principle is the same. For the convenience of expression, this scheme is described as the case where the front and rear wheels of the remote control car are in contact with the bottom plate.

[0087] The three laser rangefinders of the first angle measuring device 4 each emit a laser beam forward along the X direction. After the three laser beams hit the surface of the web in front of the remote-controlled vehicle, part of the laser is reflected back to the corresponding laser rangefinder along the original optical path. The laser rangefinder multiplies the time difference between emitting and receiving the laser by the speed of light to obtain the distance from the laser emission holes of the three laser rangefinders to the web surface.

[0088] Assume that the reflection points of the three laser rangefinders on the web are K1, K2, and K3. Since the position coordinates of the three laser rangefinders are known, the coordinates of K1, K2, and K3 can be calculated based on the distances from the corresponding laser rangefinders to the web. Therefore, a unique plane equation 1 can be constructed based on the coordinates of K1, K2, and K3. This plane equation is the plane equation of the web plane. Since the plane on which the chassis is located is a horizontal plane, a unique plane equation 2 can be constructed from the horizontal plane. According to the plane angle formula, the angle between plane equations 1 and 2 can be calculated. Let this angle be α, α∈(0,,90); see Figure 8 , looking in the Y direction, let the end of the magnetic plate 12 in the first magnetic device 2 away from the movable shaft 9 be point A; the point where the movable shaft 9 is located be point O; draw a ray from point O to the forward direction, and a point on the ray is point B; according to the relationship between the sum of the interior angles of a triangle, ∠AOB=90-α, at this time, the magnetic plate of the first magnetic device 2 is closest to the web.

[0089] Similarly, the second angle measuring device 5 can calculate the plane equation 3 where the box beam cavity bottom plate is located. According to the plane angle formula, the angle between plane equation 3 and plane equation 2 is calculated. Obviously, when the front and rear wheels of the remote control car are on the same surface of the box beam cavity, that is, Figure 8 In the state, the angle between plane equation three and plane equation two does not exist, and the two are parallel to each other. If plane equation three is parallel to plane equation two, the virtual angle β between the two is considered to be 0 degrees.

[0090] When the front and rear wheels of the remote control car are located on different surfaces of the box beam cavity, that is, Figure 9 When , in the same manner as above, the first magnetic device 2 can still calculate the angle α between the front web and the chassis. Similarly, the second magnetic device 3 can also calculate the actual angle β between plane equation three and plane equation two, β∈(0,,90).

[0091] Looking in the Y direction, let's assume that the end of the magnetic plate 12 of the second magnetic device 3 away from the movable axis 9 is end A', the movable axis 9 is located at point O', and a ray parallel to the vehicle chassis is drawn from point O' toward the rear of the vehicle chassis, with point B' on the ray. Then, ∠A'O'B'=90-β.

[0092] The control terminal adjusts the angles of the two magnetic devices with the chassis plane according to the angles α and β monitored by the two corresponding angle measuring devices, that is, ∠AOB=90-α and ∠A'O'B'=90-β.

[0093] See Figure 1 and Figure 4 A visual recognition device 6 is provided on the upper surface of the vehicle chassis 1. The visual recognition device 6 is used to capture the image of the box beam cavity surface. The visual recognition device 6 uses image recognition technology to identify cracks on the box beam cavity surface. If cracks appear, the image of the cracks is sent to the control terminal. Image recognition technology belongs to the existing technology.

[0094] The visual recognition device 6 includes:

[0095] The non-rotating shaft end of the first rotating motor 15 is bolted to the upper surface of the vehicle chassis 1, with the rotating shaft of the first rotating motor 15 perpendicular to the plane of the vehicle chassis 1. The first rotating motor 15 is electrically connected to the control terminal via a wired connection, and the rotation of the first rotating motor 15 is manually controlled through the control terminal.

[0096] The mounting plate 16 is welded and fixed to the rotating shaft of the first rotating motor 15 and can rotate along with the rotating shaft of the first rotating motor 15 .

[0097] Two brackets 17 are welded and fixed to the upper surface of the mounting plate 16 .

[0098] The mounting shaft 18 is simultaneously inserted into the two brackets 17. Both brackets 17 have holes for the mounting shaft 18 to pass through. The holes in the two brackets 17 are each equipped with bearings. The mounting shaft 18 is connected to the two brackets 17 by the two bearings. The mounting shaft 18 can rotate about its own axis relative to the brackets 17 by virtue of the bearings. The axis of the mounting shaft 18 is parallel to the plane of the vehicle chassis.

[0099] The second rotating motor (not shown) is bolted to one of the brackets 17 at its non-rotating shaft end. The axis of the second rotating motor's rotating shaft coincides with the axis of the mounting shaft 18, and the rotating shaft of the second rotating motor is welded to the mounting shaft 18. The second rotating motor is electrically connected to the control terminal via a wired connection, and its rotation is manually controlled through the control terminal. Both the first and second rotating motors are small servo motors that can self-lock when powered off.

[0100] Camera 19 is bolted to mounting shaft 18. Mounting shaft 18 is provided with a bolt hole, the axis of which is radially aligned with mounting shaft 18 and located in the middle of mounting shaft 18. A mounting bolt is inserted into the bolt hole and then screwed into the housing of camera 19, thereby integrally connecting camera 19 to mounting shaft 18. Rotation of first rotary motor 15 rotates camera 19 about the axis of second rotary motor 15; rotation of the second rotary motor also rotates camera 19 about the axis of mounting shaft 18.

[0101] A lighting system 7 is installed on the upper surface of the vehicle chassis 1. The lighting system 7 is an LED lamp with variable light intensity. It is electrically connected to the control terminal through a wired manner. People can manually control the brightness of the lighting system 7 through a wired manner to ensure that the camera 19 can clearly capture the crack image. Example

[0102] A method for detecting cracks in a box girder comprises the following steps:

[0103] S1: Adaptation orientation;

[0104] The specific steps include:

[0105] S1.1: The operator places the robot on one surface of the box beam cavity from one end of the box beam, ensuring that the front and rear wheels of the robot are placed on one surface of the box beam cavity at the same time; and ensuring that the front of the robot faces the other surface of the box beam cavity; for ease of operation, in this embodiment, the operator places the robot on the bottom plate with the front of the robot facing the web of the box beam cavity.

[0106] S1.2: After the operator turns on the robot, the control terminal controls the three laser rangefinders in the first angle measurement device to emit lasers once. The lasers from the three laser rangefinders illuminate the other surface in step S1.1 and are then reflected. The three laser rangefinders each measure the distance to the other surface, and the control terminal obtains the distances monitored by the three laser rangefinders.

[0107] S1.3: Determine whether the distances between the two laser rangefinders at the same height in the first angle measuring device are equal, and determine whether the orientation adaptation is complete;

[0108] S1.3.1: If the distances between the two laser rangefinders at the same height in the first angle measuring device are not equal, and orientation adaptation is not complete, the control terminal controls the robot to adjust its direction accordingly. Adjusting the direction means: the control terminal controls the robot to rotate along the plane of the chassis. Repeat step S1.3.1, and the control terminal continuously controls the three laser rangefinders in the first angle measuring device to emit lasers and measure the distance to another surface until the distances between the two laser rangefinders at the same height are equal. At this point, orientation adaptation is complete, and the robot no longer rotates along the plane of the chassis.

[0109] S1.3.2: If the distances between the two laser rangefinders at the same height are equal, the adaptation is complete and the robot no longer rotates along the plane of the chassis.

[0110] S2: The first magnetic device and the second magnetic device adapt to the angle;

[0111] The specific steps include:

[0112] S2.1: Determine the angle α between the plane of the vehicle chassis and another surface in front of it;

[0113] After orientation adaptation is completed, the control terminal continuously controls the three laser rangefinders of the first angle measurement device to emit lasers multiple times at a designed frequency. Each time the three lasers hit another surface and reflect, the first magnetic device calculates the angle α between the other surface in front of the robot and the robot chassis based on the distances monitored by the three laser rangefinders. During this laser emission, the distances to the other surface in front monitored by the three laser rangefinders are H1, H2, and H3, respectively, where H1=H2.

[0114] S2.2: Determine the angle β between the chassis plane and the surface with which the rear wheels come into contact;

[0115] The control terminal continuously controls the three laser rangefinders of the second magnetic device to emit lasers multiple times at a designed frequency. Each time the three lasers hit the surface that the rear wheel contacts and are reflected, the second magnetic device calculates the angle β between the plane of the vehicle chassis and the surface that the rear wheel contacts based on the distance monitored by the three laser rangefinders. If the surface that the rear wheel contacts is parallel to the vehicle chassis surface, the angle β = 0.

[0116] S2.3: Calculate the angle of the second magnetic device; determine the state of the first magnetic device and determine the angle of the first magnetic device;

[0117] The specific steps include:

[0118] S2.3.1: Calculate the angle of the second magnetic device. Looking in the Y direction, let A' be the end of the magnetic plate in the second magnetic device that is away from the active axis, and O' be the point where the active axis 9 is located. Draw a ray parallel to the chassis from O' toward the rear of the vehicle chassis, with B' on that ray. Then, ∠A'O'B' = 90 - β.

[0119] S2.3.2: Observing in the Y direction, let point A be the end of the magnetic plate in the first magnetic device away from the active axis, point O be the active axis, and point B be a point on a ray from point O toward the forward direction. If H1, H2, and H3 are all greater than or equal to the set threshold R, the robot's front end is far from the other surface, and the first and second magnetic devices maintain the same angle, that is, ∠AOB = ∠A'O'B' = 90 - β.

[0120] S2.3.3: If any of H1, H2, and H3 is less than the threshold R, the robot front end is close to the other surface, then ∠AOB = 90-α;

[0121] S3: The operator controls the robot via the control terminal to advance a distance D and then stop. During the advancement, the control terminal executes S2, controlling the first magnetic device and the second magnetic device to adapt their angles in the manner described in S2.

[0122] S4: After the robot stops, the operator rotates the first rotary motor and the second rotary motor in the visual recognition device through the control terminal. The camera automatically adjusts the focus and captures an image of the box girder surface. The visual recognition device identifies cracks using image recognition technology. If cracks are identified, the visual recognition device sends the information to the control terminal. A display connected to the control terminal displays the cracks.

[0123] S5: Repeat S3-S4. The operator controls the robot to continue walking a distance D according to step S3 and then stops, and presses S4 to capture the image of the inner surface of the box girder. Because the distance of one circle of the box girder end face is a known quantity, the operator can determine whether the robot has completed one circle by multiplying the distance D walked by the robot each time by the number of walks. Until the robot walks one circle in a direction parallel to the box girder end face, the operator no longer moves the robot in the forward direction.

[0124] S6: The operator sends a lateral movement command to the robot through the control terminal. The control terminal causes the robot to move horizontally for a distance N in a direction perpendicular to the end face of the box beam and then stop. According to the method in steps S3 and S4, the robot continues to move around the inner cavity of the box beam once more, and images of the inner cavity of the box beam are taken.

[0125] S7: Repeat S6 until the robot moves out from the other end of the box beam and completes the entire surface inspection of the inner cavity surface of the box beam.

[0126] With the above-described preferred embodiments of the present invention as a guide, and with reference to the above description, relevant personnel are fully capable of making various changes and modifications without departing from the technical scope of this invention. The technical scope of this invention is not limited to the contents of the specification and must be determined according to the scope of the claims.

Claims

1. A box girder crack detection robot, characterized in that: The remote control car includes a remote control car, wherein the forward direction of the remote control car is along the X direction; the remote control car includes a chassis, front wheels, and rear wheels, wherein the drive shaft axes of the front wheels and rear wheels are along the Y direction, and the X direction is perpendicular to the Y direction. The front and rear ends of the chassis are both provided with magnetic devices, wherein the magnetic device located at the front end of the chassis is a first magnetic device, and the magnetic device located at the rear end of the chassis is a second magnetic device, and the magnetic devices are located on the lower surface of the chassis; The magnetic device includes: A base, fixed to the lower surface of the vehicle chassis; The movable shaft is rotatably connected to the base and can rotate relative to the base around its own axis, with the axis of the movable shaft being along the Y direction; A driven gear is fixedly connected to the movable shaft, and the axis of the driven gear coincides with the axis of the driven gear; A connecting rod, one end of which is fixed to the side surface of the movable shaft, and the axis of which is arranged along the radial direction of the movable shaft; The magnetic plate is a permanent magnet connected to the other end of the connecting rod; The control motor is a servo motor, used to rotate the movable shaft; the control motor is electrically connected to the control terminal; The driving gear is fixed to the rotating shaft of the control motor, and the axis of the driving gear coincides with the axis of the control motor; the driving gear is meshed with the driven gear; The remote control vehicle is provided with a first angle measuring device and a second angle measuring device, both of which are electrically connected to the control terminal. The control terminal can control the rotation of the control motors of the first magnetic device and the second magnetic device according to the angles monitored by the first angle measuring device and the second angle measuring device. A visual recognition device for capturing images of the inner surface of the box girder is fixedly mounted on the upper surface of the vehicle chassis. The first angle measuring device includes three laser rangefinders. The laser emission points of the three laser rangefinders of the first angle measuring device are respectively point 1, point 2, and point 3. The laser emission directions of the three laser rangefinders of the first angle measuring device are along the X direction and facing forward. The plane formed by points 1, 2, and 3 is plane Q. The X direction is perpendicular to plane Q. When observed in the X direction, points 1, 2, and 3 are not collinear. The second angle measuring device also includes three laser rangefinders. The laser emission points of the three laser rangefinders of the second angle measuring device are set as point 4, point 5, and point 6 respectively. The laser emission directions of the three laser rangefinders of the second angle measuring device are perpendicular to the vehicle floor and facing downward. The plane formed by points 4, 5, and 6 is set as plane M. Plane M is parallel to the plane of the vehicle floor. When observed from a perspective perpendicular to plane M, points 4, 5, and 6 are not collinear. The first angle measuring device and the second angle measuring device are both electrically connected to the control terminal. The visual recognition device includes: A first rotating motor, wherein the non-rotating shaft end is fixed to the upper surface of the vehicle chassis; the rotating shaft of the first rotating motor is perpendicular to the plane of the vehicle chassis; and the first rotating motor is electrically connected to the control terminal; a mounting plate fixed to the rotating shaft of the first rotating motor; Two brackets, fixed on the upper surface of the mounting plate; The mounting shaft is rotatably connected to the two brackets, and the axis of the mounting shaft is parallel to the plane where the chassis is located; A second rotating motor, used to rotate the mounting shaft; electrically connected to the control terminal; Camera, mounted on the mounting shaft.

2. A box girder crack detection robot according to claim 1, characterized in that: The two laser rangefinders corresponding to point one and point two are at the same height.

3. The crack detection robot for box beams according to claim 2, characterized in that: A lighting system is installed on the vehicle chassis. The lighting system is electrically connected to a control terminal. The control terminal can control the lighting system to change brightness.

4. A box girder crack detection method, based on the box girder crack detection robot according to claim 1, characterized in that: Steps to follow: S1: Adaptation orientation; The specific steps include: S1.1: The operator places the robot from one end of the box girder on one of the surfaces of the box girder cavity, ensuring that the robot's front and rear wheels are simultaneously placed on one of the surfaces of the box girder cavity; and ensure that the front of the robot faces the other surface of the box girder cavity; S1.2: After the operator turns on the robot, the control terminal controls the three laser rangefinders in the first angle measurement device to emit lasers once. The lasers from the three laser rangefinders illuminate the other surface in step S1.1 and are then reflected. The three laser rangefinders each measure the distance to the other surface, and the control terminal obtains the distances monitored by the three laser rangefinders. S1.3: Determine whether the distances between the two laser rangefinders at the same height in the first angle measuring device are equal, and determine whether the orientation adaptation is complete; S1.3.1: If the distances between the two laser rangefinders at the same height in the first angle measuring device are not equal, and orientation adaptation is not complete, the control terminal controls the robot to adjust its direction accordingly. Adjusting the direction means: the control terminal controls the robot to rotate along the plane of the chassis. Repeat step S1.3.1, and the control terminal continuously controls the three laser rangefinders in the first angle measuring device to emit lasers and measure the distance to another surface until the distances between the two laser rangefinders at the same height are equal. At this point, orientation adaptation is complete, and the robot no longer rotates along the plane of the chassis. S1.3.2: If the distances between the two laser rangefinders at the same height are equal, the adaptation is complete and the robot no longer rotates along the plane of the chassis. S2: Adaptation angle between the first magnetic device and the second magnetic device; The specific steps include: S2.1: Determine the angle α between the plane of the vehicle chassis and another surface in front of it; After orientation adaptation is completed, the control terminal continuously controls the three laser rangefinders of the first angle measurement device to emit lasers multiple times at a designed frequency. Each time the three lasers hit another surface and reflect, the first magnetic device calculates the angle α between the other surface in front of the robot and the robot chassis based on the distances monitored by the three laser rangefinders. During this laser emission, the distances to the other surface in front monitored by the three laser rangefinders are H1, H2, and H3, respectively, where H1=H2. S2.2: Determine the angle β between the chassis plane and the surface with which the rear wheels come into contact; The control terminal continuously controls the three laser rangefinders of the second magnetic device to emit lasers multiple times at a designed frequency. Each time the three lasers hit the surface that the rear wheel contacts and are reflected, the second magnetic device calculates the angle β between the plane of the vehicle chassis and the surface that the rear wheel contacts based on the distance monitored by the three laser rangefinders. If the surface that the rear wheel contacts is parallel to the vehicle chassis surface, the angle β = 0. S2.3: Calculate the angle of the second magnetic device; determine the state of the first magnetic device and determine the angle of the first magnetic device; The specific steps include: S2.3.1: Calculate the angle of the second magnetic device. Looking in the Y direction, let A' be the end of the magnetic plate in the second magnetic device that is away from the active axis, and O' be the point where the active axis 9 is located. Draw a ray parallel to the chassis from O' toward the rear of the vehicle chassis, with B' on that ray. Then, ∠A'O'B' = 90 - β. S2.3.2: Observing in the Y direction, let point A be the end of the magnetic plate in the first magnetic device away from the active axis, point O be the active axis, and point B be a point on a ray from point O toward the forward direction. If H1, H2, and H3 are all greater than or equal to the set threshold R, the robot's front end is far from the other surface, and the first and second magnetic devices maintain the same angle, that is, ∠AOB = ∠A'O'B' = 90 - β. S2.3.3: If any of H1, H2, and H3 is less than the threshold R, the robot front end is close to the other surface, then ∠AOB = 90-α; S3: The operator controls the robot via the control terminal to advance a distance D and then stop. During the advancement, the control terminal executes S2, controlling the first magnetic device and the second magnetic device to adapt their angles in the manner described in S2. S4: After the robot stops, the operator rotates the first and second rotary motors in the visual recognition device through the control terminal. The camera automatically adjusts the focus and captures an image of the box girder surface. The visual recognition device identifies cracks using image recognition technology. If cracks are identified, the visual recognition device sends the information to the control terminal. A display connected to the control terminal displays the cracks. S5: Repeat S3-S4 until the robot moves one circle along the end face of the box girder. Because the distance of one circle of the box girder end face is a known quantity, the operator can determine whether the robot has completed one circle by multiplying the distance D of each movement by the number of movements. When the robot moves one circle along the end face of the box girder, the operator stops moving the robot in the forward direction and the visual recognition device captures an image of one circle of the box girder end face. S6: The operator sends a lateral movement command to the robot through the control terminal, and the control terminal causes the robot to move horizontally for a distance N in a direction perpendicular to the end face of the box beam and then stop. The robot continues to move around the inner cavity of the box beam once more, and captures images of the inner cavity of the box beam in the same manner as in steps S3 and S4. S7: Repeat S6 until the robot moves out from the other end of the box beam and completes the entire surface inspection of the inner cavity surface of the box beam.

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