Water-based inspection device and water-based inspection method

Abstract

Provided is an on-water inspection device and an on-water inspection method that efficiently capture two-dimensional images from different viewpoints and accurately construct three-dimensional images. [Solution] Water inspection method 50 is a water inspection method using water inspection equipment equipped with multiple cameras and multiple direction change means for changing the shooting directions of the multiple cameras, and includes a shooting step S51 in which the multiple cameras take two-dimensional images including structures at time intervals as the water inspection equipment moves on the water along a route, and the shooting step S51 includes route-by-route shooting steps S51-1 to S51-3 in which at least one of the multiple direction change means is adjusted each time the water inspection equipment completes movement along the entire route, so that the multiple cameras take multiple sets of two-dimensional images with different combinations of shooting directions.

Description

[Technical Field]

[0001] The present invention relates to an on-water inspection device and an on-water inspection method for inspecting a structure. [Background technology]

[0002] Conventionally, inspections have been carried out to detect abnormalities occurring in structures such as bridges and piers. For example, small vessels that can accommodate workers have been used as inspection devices, and visual inspections and hammering tests have been carried out by the onboard workers. However, small vessels that can accommodate workers cannot enter, for example, the narrow space between the underside of a bridge girder and the water surface, which has led to the problem of being unable to carry out inspections adequately. To solve these problems, technology has been developed in recent years to enable inspections in narrow spaces by using small unmanned vessels equipped with cameras, and an invention related to this has already been disclosed.

[0003] Patent Document 1 discloses an invention entitled "Structure Diagnosis Method" that relates to a diagnostic method for checking the condition of a structure using an unmanned small boat equipped with a camera. The invention disclosed in Patent Document 1 is a structure diagnosis method that includes a photographing process in which a structure is simultaneously photographed with multiple cameras mounted on a vehicle on water and arranged in a line directly above the vehicle, and a diagnosis process in which the surface condition of the structure is confirmed using the images taken by the cameras.The multiple cameras are fixed to a rod-shaped mounting member fixed to the vehicle, and are therefore fixed to the vehicle without using a shooting direction adjustment mechanism.The mounting member is perpendicular to the direction of travel of the vehicle, the shooting directions of the multiple cameras are parallel, and the range photographed by one camera overlaps with at least a portion of the range photographed by another adjacent camera.The diagnosis process is characterized in that the surface condition of the structure is confirmed over a wide area by superimposing images from adjacent cameras on each other. In this invention, multiple cameras can be used to capture images of the underside of a structure over a wide area, eliminating the need for a complex mechanism to control the camera's shooting direction. Furthermore, the surface condition of a structure can be confirmed over a wide area with a single navigation. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6242515 Summary of the Invention [Problem to be solved by the invention]

[0005] However, according to the invention disclosed in Patent Document 1, the multiple cameras are fixed perpendicular to the traveling direction of the moving means without using an imaging direction adjustment mechanism, so the imaging directions of the cameras cannot be adjusted. As a result, the number of different viewpoints is small, and there is a risk that a 3D image cannot be constructed with high accuracy.

[0006] The present invention has been made in response to such conventional circumstances, and aims to provide an underwater inspection device and an underwater inspection method that are equipped with a direction change means that can adjust the shooting direction of each of multiple cameras, thereby making it possible to efficiently capture two-dimensional images from different viewpoints and to accurately construct three-dimensional images. [Means for solving the problem]

[0007] In order to achieve the above-mentioned object, the first invention is an underwater inspection device comprising an aircraft body, a photographing unit for photographing structures, a support structure attached to the aircraft body and supporting the photographing unit, and a propulsion structure for moving on the water, wherein the photographing unit is a plurality of cameras arranged in parallel at intervals along the width direction of the aircraft body, and the plurality of cameras each take two-dimensional images that overlap each other in part in the width direction, and the support structure is characterized by comprising a plurality of direction change means capable of changing the photographing direction of each of the plurality of cameras, and a long member to which the plurality of direction change means are attached.

[0008] In an invention having such a configuration, the number of the multiple cameras may be two or more. The support structure may be provided, for example, along the width direction of the aircraft. The direction change means may change the shooting direction of the multiple cameras, for example, in the direction of travel perpendicular to the width direction of the aircraft, or may change the shooting direction along the width direction of the aircraft. The direction change means may change the shooting directions of the multiple cameras to the same direction or to different directions. The structure is not particularly limited as long as it is installed above the water surface or at least partially submerged in water. In the invention with the above configuration, the shooting directions of multiple cameras are changed, so that images of structures taken from multiple viewpoints can be efficiently obtained as the underwater inspection device moves on the water along a set route.

[0009] A second invention is a method for surface inspection using a surface inspection device, the surface inspection device comprising a body, a photographing unit for photographing structures, and a support structure attached to the body and supporting the photographing unit, the photographing unit being a plurality of cameras arranged in parallel at intervals along the width direction of the body, the plurality of cameras each photographing two-dimensional images that overlap each other in part in the width direction, the support structure comprising a plurality of direction changing means capable of changing the photographing direction of the plurality of cameras respectively, and a long member to which the plurality of direction changing means are attached, the method comprising: a photographing process in which the plurality of cameras photograph two-dimensional images including structures at time intervals as the surface inspection device moves on the water along a set route, the photographing process comprising a plurality of route-by-route photographing processes, wherein at least one of the plurality of direction changing means is adjusted each time the surface inspection device completes movement along the entire route, so that the plurality of cameras each photograph multiple sets of two-dimensional images with different combinations of photographing directions of the multiple cameras.

[0010] In the invention having such a configuration, the two-dimensional images captured at time intervals may be either moving images or still images. Furthermore, the multiple route-specific photographing steps may be performed two or more times, and each route may be the same or different. Furthermore, the combination of the shooting directions of the multiple cameras being different each time the water inspection device completes its movement along the entire route means, for example, that the shooting directions of the multiple cameras are changed while remaining aligned, or changed individually without being aligned, for each route and shooting process.

[0011] In the invention having the above configuration, the shooting direction of the multiple cameras is changed for each route shooting process, and by combining the number of route shooting processes and the shooting directions of the multiple cameras, two-dimensional images are captured from various viewpoints throughout the entire shooting process in the width direction of the aircraft and in the direction of travel perpendicular to this width direction.

[0012] The third invention is characterized in that, in the second invention, an image construction process is provided after the photographing process, and the image construction process is characterized in that an image construction unit provided in the abnormality detection device that detects abnormalities in a structure constructs at least a three-dimensional image from multiple sets of two-dimensional images. In the invention having such a configuration, the plurality of sets of two-dimensional images include images from various multiple viewpoints, so that the surface shape of the structure can be clearly recognized in the three-dimensional image and noise can be reduced. In addition to the three-dimensional image, an orthoimage may also be generated.

[0013] A fourth invention is characterized in that, in the third invention, the abnormality detection device is provided with an actual dimension calculation unit, and an actual dimension calculation process is performed after the image construction process, and the multiple sets of two-dimensional images include, in addition to the structure, a known scale reference object attached to the structure, and the actual dimension calculation process is characterized in that the actual dimension calculation unit calculates the actual dimension of the abnormal part by comparing the size of the abnormal part of the structure detected from the three-dimensional image with the known size of the scale reference object included in the three-dimensional image. In the invention configured as above, the size of the abnormal portion of the structure and the known size of the scale reference object are both length or area. Furthermore, the abnormal portion may be detected by a person from a 3D image, or may be automatically detected from a 3D image by artificial intelligence that has learned the shape of an abnormality through machine learning. In the invention having the above configuration, in addition to the effect of the third invention, the actual dimensions of the abnormal area are calculated from the three-dimensional image, so that the state of the abnormal area can be grasped in detail. [Effects of the Invention]

[0014] According to the first aspect of the present invention, by changing the shooting directions of multiple cameras, two-dimensional images can be efficiently captured from multiple viewpoints, making it possible to construct a highly accurate three-dimensional image with a small number of cameras. In addition, by changing the line of sight direction, it is possible to adjust the shooting direction to the optimum direction for detecting abnormalities in a structure.

[0015] According to the second invention, the photographing process comprises a plurality of photographing processes for each route, so that two-dimensional images are taken from a variety of viewpoints throughout the entire photographing process, and therefore, as with the first invention, a highly accurate three-dimensional image can be constructed using a small number of cameras.

[0016] According to the third invention, in addition to the effect of the second invention, the surface shape of the structure can be clearly recognized in the three-dimensional image, so that an abnormal portion can be detected with high accuracy.

[0017] According to the fourth invention, in addition to the effect of the third invention, the state of the abnormal part can be grasped in detail, so that it is possible to estimate, for example, the necessity of repairing the abnormal part and the timing of repair. [Brief explanation of the drawings]

[0018] [Figure 1] 1 is an external view of an on-water inspection device according to a first embodiment. [Figure 2] 1 is a configuration diagram of an underwater inspection device and an abnormality detection device according to a first embodiment. [Figure 3] 1 is a front view of a photographing unit and a support structure that constitute the on-water inspection device according to Example 1. FIG. [Figure 4] FIG. 4 is a view taken along the line A in FIG. 3. [Figure 5] FIG. 4 is a view taken along the line A in FIG. 3. [Figure 6] FIG. 10 is a process diagram of an on-water inspection method according to a second embodiment. [Figure 7] FIG. 10 is an explanatory diagram illustrating a photographing range along the direction of travel of the aircraft. [Figure 8] FIG. 10 is an explanatory diagram illustrating a photographing range along the width direction of the aircraft body. DETAILED DESCRIPTION OF THE INVENTION [Example]

[0019] A water-based inspection device according to a first embodiment of the present invention will be described in detail with reference to Figures 1 to 5. Figure 1 is an external view of the water-based inspection device according to the first embodiment. As shown in FIG. 1, the surface inspection device 1 according to the first embodiment is specifically an underwater drone, and includes a body 2, a photographing unit 3 for photographing structures, a support structure 4 attached to the body 2 and supporting the photographing unit 3, a plurality of propulsion structures 5 for moving on the water, floats 6, lighting equipment 7, and a slot 8 (see FIG. 2). A storage medium for storing two-dimensional images photographed by the photographing unit 3 is inserted into the slot 8. Of the above, everything except the support structure 4 has a general configuration. The surface inspection device 1 also includes a front end 1a and a rear end 1b. The direction in which the surface inspection device 1 travels with the front end 1a in the lead is the traveling direction F.

[0020] Of the water-based inspection device 1, the aircraft body 2 is a frame that holds a propulsion structure 5, floats 6, lighting devices 7, and slots 8 (see Figure 2). The photographing unit 3 is a pair of cameras that are spaced apart and arranged in parallel along the width direction W of the aircraft body 2. The pair of cameras each capture two-dimensional images that partially overlap each other in the width direction W. The propulsion structure 5 is made up of a plurality of thrusters, and is capable of propelling the on-water inspection device 1 in the width direction W and in a forward direction F perpendicular to the width direction W, as well as moving backward and turning. The configuration of the support structure 4 will be explained using Figure 3.

[0021] Next, an abnormality detection device used together with the on-water inspection device 1 will be described with reference to Fig. 2. Fig. 2 is a configuration diagram of the on-water inspection device and the abnormality detection device according to the first embodiment. As shown in Figure 2, the abnormality detection device 30 is a device for detecting abnormalities in a structure, and is installed independently without wireless or wired communication with the surface inspection device 1. Furthermore, the propulsion structure 5 of the surface inspection device 1 is controlled by propulsion control means 10 via a cable 9. The propulsion control means 10 is a general controller.

[0022] The abnormality detection device 30 is specifically a computer, and includes a slot 31 , an input unit 32 , a control unit 33 , a storage unit 37 , and a display unit 41 . Of the above, slot 31, like slot 8, is used to insert a storage medium into which a two-dimensional image captured by the imaging unit 3 is stored. The input unit 32 is specifically a keyboard, and as will be described later, it is possible to input the known length of a scale reference object attached to a structure and the file name of a two-dimensional image captured by the imaging unit 3. Next, the control unit 33 is a central processing unit that controls the operation of the abnormality detection device 30, and includes an image construction unit , a detection unit 35, and an actual dimension calculation unit . The storage unit 37 includes an image storage unit 38, an abnormality location storage unit 39, and an actual dimension storage unit 40. The display unit 41 is specifically a monitor. Each component of the control unit 33 will be described below.

[0023] The image construction unit constructs a three-dimensional image and an orthoimage from the two-dimensional image captured by the imaging unit 3. The constructed three-dimensional image and orthoimage are stored in the image storage unit . The detection unit 35 detects abnormal locations in the structure from the three-dimensional image. This detection method can be, for example, a method in which an operator manually inputs abnormal locations from the three-dimensional image displayed on the display unit 41, or a method in which artificial intelligence that has learned the patterns of abnormal locations automatically detects them from the three-dimensional image. The detected abnormal locations are superimposed on the three-dimensional image and stored in the abnormal location storage unit 39. The actual dimension calculation unit 36 ​​calculates the actual dimension of the abnormal area by comparing the size of the abnormal area detected by the detection unit 35 with the known size of the scale reference object included in the three-dimensional image. The calculated actual dimension is stored in the actual dimension storage unit 40 in association with the abnormal area.

[0024] Next, the configuration of the support structure will be described with reference to Fig. 3 to Fig. 5. Fig. 3 is a front view of the photographing unit and the support structure that constitute the on-water inspection device according to Example 1. Fig. 4 and Fig. 5 are views taken in the direction of the arrow A in Fig. 3. 3, a pair of cameras 11, 12 constituting the photographing unit 3 are housed in waterproof cases 13, 13. This waterproof case 13 has an attachment part 13a (see FIG. 4) for attachment to direction changing means 14. The support structure 4 also comprises a pair of direction change means 14, 14 that can change the shooting direction of the cameras 11, 12, respectively, a plate-shaped elongated member 15 to which the direction change means 14, 14 are attached, and a pair of fixing parts 16, 16 that fix the elongated member 15 to the aircraft body 2.

[0025] Of these, the elongated member 15 has end portions 15a, 15a. Furthermore, the elongated member 15 has slide holes 15b, 15b formed along the longitudinal direction of the elongated member 15 between the end portions 15a, 15a. The fixing part 16 is made up of an attachment 16a, which is a short L-shaped metal fitting, and fasteners 16b and 16c that respectively fix the attachment 16a to the machine body 2 and the end 15a of the elongated member 15. The fasteners 16b and 16c are both bolts and nuts.

[0026] Next, the direction change means 14 comprises a thumbscrew 17 provided on the underside of the elongated member 15, a base 18 provided on the upper surface of the elongated member 15, a rod-shaped body 19, a screw 20, a support 21 (see Figure 4) and a screw 22 (see Figure 4) provided at the upper end of the body 19. Of these, thumbscrew 17 passes through slide hole 15b of elongated member 15 and screws into a threaded hole provided in base 18. Therefore, by loosening thumbscrew 17, direction change means 14 can slide along slide hole 15b. In other words, the positions of cameras 11 and 12 in width direction W and the distance between them can be manually adjusted.

[0027] Additionally, the upper end 18a of the base 18 and the lower end 19a of the body 19 correspond to the barrel of the hinge structure H1, and the screw 20 corresponds to the pin of the hinge structure H1. Therefore, when an operator inserts the screw 20 into the central holes of the upper end 18a and the lower end 19a, which mesh with each other, the body 19 is fixed so that it cannot tilt relative to the base 18. On the other hand, when an operator pulls out the screw 20 from the central holes of the upper end 18a and the lower end 19a, the body 19 can be tilted to a desired tilt angle relative to the base 18.

[0028] Next, as shown in FIG. 4, the support part 21 and the attachment part 13a of the waterproof case 13 correspond to the barrel of the hinge structure H2, and the screw 22 corresponds to the pin of the hinge structure H2. Therefore, by inserting the screw 22 into the center holes of the interlocking support part 21 and the mounting part 13a, the worker fixes the waterproof case 13 so that it cannot tilt relative to the support part 21. On the other hand, by pulling out the screw 22 from the center holes of the support part 21 and the mounting part 13a, the worker can tilt the waterproof case 13 to a desired tilt angle relative to the support part 21.

[0029] Next, the operation of the direction changing means 14 will be described with reference to FIGS. FIG. 4 shows a case where the waterproof case 13 is attached to the support part 21 so that the attachment part 13a of the waterproof case 13 faces the rear end 1b (see FIG. 1) side of the on-water inspection device 1. As shown in Figure 4, the waterproof case 13 shown by the solid line is positioned so that the lens 11a of the camera 11 faces upward along the vertical direction V. Here, assuming that the underwater inspection device 1 is sailing under the girder of a bridge 60 (see Figures 7 and 8), the shooting direction X1 of the camera 11 faces directly toward the underside 60a of the girder of the bridge 60.

[0030] In contrast, by pulling out the screw 22, the waterproof case 13 is positioned so as to tilt, for example, at a tilt angle α of 45 degrees counterclockwise from the horizontal direction H around the axial center 22a of the screw 22, as shown by the dotted line. Therefore, the shooting direction X2 of the camera 11 is in a direction inclined at the tilt angle α with respect to the girder underside 60a of the bridge 60, i.e., toward the girder underside 60a that is located behind the camera 11.

[0031] Next, FIG. 5 shows a case where the waterproof case 13 is attached to the support part 21 so that the attachment part 13a of the waterproof case 13 faces the front end 1a (see FIG. 1) side of the on-water inspection device 1. 5, the waterproof case 13 is disposed so as to tilt at a tilt angle α of 135 degrees counterclockwise from the horizontal direction H around the axial center 22a of the screw 22. Therefore, the shooting direction X3 of the camera 11 is directed toward the girder underside 60a located in front of the camera 11. 4 and 5, by providing direction change means 14, it is possible to manually change the photographing direction of camera 11 in the traveling direction F. The same applies to camera 12. Furthermore, to change the shooting direction of the camera 11, in addition to adjusting the tilt of the waterproof case 13 relative to the body 19, the tilt of the body 19 relative to the base 18 may also be adjusted. The same applies to the camera 12.

[0032] As described above, according to the water inspection device 1, the support structure 4 is equipped with a direction change means 14, a long member 15, etc., so that the positions of the cameras 11 and 12 along the width direction W and the shooting direction in the direction of travel F can be manually adjusted, making it possible to easily capture two-dimensional images from multiple viewpoints and to create accurate three-dimensional images with a small number of cameras. Furthermore, when the photographing direction is changed, the overlapping range R of the two-dimensional images photographed by the cameras 11 and 12 is also changed. F ,R W Therefore, for example, it is possible to reduce the obstruction of abnormal areas and improve detection accuracy. Furthermore, the components other than the support structure 4 have a general configuration, and the support structure 4 does not have a complex configuration such as being automatically controlled remotely, so the manufacturing costs of the on-water inspection device 1 can be reduced. [Example]

[0033] A method for inspection on water according to a second embodiment of the present invention will be described in detail with reference to Figures 6 to 8. Figure 6 is a process chart of the method for inspection on water according to the second embodiment. 6, the surface inspection method 50 according to the second embodiment is a surface inspection method using the surface inspection device 1 according to the first embodiment and the abnormality detection device 30, and includes an imaging step S51, an image construction step S52, a detection step S53, an actual dimension calculation step S54, and a display step S55. Each step will be described below. The photographing step S51 is a step in which, as the on-water inspection device 1 moves on the water along a set route, the cameras 11 and 12 photograph two-dimensional images including the structure and a known scale reference attached to the structure at time intervals. Specifically, the scale reference is a straight-ruler-like adhesive sticker with a known total length that can be attached to the surface of the structure. The two-dimensional images may be either moving or still images. If the structure is a bridge, the route may be either a route that travels along the bridge length and then turns back in the bridge width direction, or a route that travels along the bridge width and then turns back in the bridge length direction. This route is set so that the cameras 11 and 12 can ensure an overlap in the travel direction F and a side lap in the turning direction.

[0034] The photographing step of S51 includes a total of three photographing steps for each route, S51-1 to S51-3. In the photographing steps for each route, S51-1 to S51-3, each time the waterborne inspection device 1 completes movement along the entire route, at least one of the direction changing means 14 is adjusted, so that the cameras 11 and 12 each take a plurality of sets of two-dimensional images with different photographing directions.

[0035] As an example, in the route-by-route photographing process of S51-1, as shown in Figure 4, the photographing direction of camera 11 is set to face the structure directly (tilt angle α is 0 degrees), and the photographing direction of camera 12 is tilted so that the tilt angle α is 30 degrees relative to the structure, and two-dimensional images are taken along the route.

[0036] Here, the imaging range of the cameras 11 and 12 along the traveling direction F will be described with reference to Fig. 7. Fig. 7 is an explanatory diagram illustrating the imaging range along the traveling direction of the aircraft. As shown in FIG. 7, when the on-water inspection device 1 is navigating under the girder of a bridge 60, in the route-by-route photographing step S51-1, the cameras 11 and 12 each photograph a first set of two-dimensional images that partially overlap each other in the traveling direction F. The cameras 11 and 12 each photograph a range R 11 ,R 12 In order to capture the image, the overlapping range R is shown in the shaded area. F occurs. Note that the overlapping range R F In this example, the two-dimensional images also partially overlap in the width direction W. In this state, when photographing of the entire route is completed, only the direction changing means 14 supporting the camera 12 is adjusted so that the photographing direction of the camera 12 is directly facing the girder underside 60a of the bridge 60. After that, the photographing process for each route in S51-2 is executed.

[0037] Next, the imaging range of the cameras 11 and 12 along the width direction W will be described with reference to Fig. 8. Fig. 8 is an explanatory diagram illustrating the imaging range along the width direction of the aircraft body. As shown in Fig. 8, in the route-by-route photographing step S51-2, the cameras 11 and 12 each photograph a second set of two-dimensional images that partially overlap each other in the width direction W. In this case, the overlapping range R is indicated in the shaded area. W As mentioned above, the overlapping range R W In this case, the overlapping range R F is formed. Then, when photographing of the entire route in this state is completed, the direction changing means 14, 14 supporting the cameras 11, 12 are adjusted so that the photographing directions of the cameras 11, 12 are tilted in unison with respect to the girder underside 60a of the bridge 60. At this time, the tilt angle α (see Figures 4 and 5) with respect to the horizontal direction H is set to 150 degrees for both cameras 11, 12, or 135 degrees for both cameras 11, 12. Thereafter, the photographing process for each route in S51-3 is executed.

[0038] Returning to FIG. 6, in the route-by-route photographing step S51-3, the cameras 11 and 12 each capture a third pair of two-dimensional images that partially overlap each other in the traveling direction F. In this case, too, the overlapping range R F and the overlapping range RW However, this is different from the route-by-route photography process of S51-1 and the route-by-route photography process of S51-2. In this way, in the photographing step of S51, the photographing directions of the cameras 11 and 12 are changed for each route photographing step of S51-1 to S51-3, so that the cameras 11 and 12 photograph three sets of two-dimensional images with different combinations of photographing directions.

[0039] Next, in the image construction step of S52, the image construction unit 34 constructs a three-dimensional image and an orthoimage from the three sets of two-dimensional images taken by the cameras 11 and 12. The 3D image is constructed using the well-known SfM process, which extracts feature points from three sets of 2D images, calculates 3D coordinate data, and constructs a 3D model. From this 3D model, a 3D image and an orthogonal image are then generated.

[0040] In the detection step of S53, the detection unit 35 detects abnormal areas from the constructed 3D image. The detection unit 35 is, for example, an artificial intelligence that generates a model using known machine learning based on training data consisting of an image and an abnormality shape pattern, and estimates the abnormality pattern contained in the constructed 3D image and its position based on this model. This abnormality pattern and its estimated position are detected as abnormal areas and are stored in the abnormal area storage unit 39.

[0041] In the actual dimension calculation step S54, the actual dimension calculation unit 36 ​​calculates the actual dimension of the abnormal part by comparing the size of the abnormal part of the structure detected from the constructed three-dimensional image with the known size of the scale reference object included in the three-dimensional image. For example, the size of the abnormal area is the number of pixels corresponding to the maximum length of the abnormal area on the three-dimensional image. Also, the known size of the scale reference object is the number of pixels corresponding to the total length of the scale reference object on the three-dimensional image. The total length (actual size) of the scale reference object is input in advance from the input unit 32 and stored in the actual size storage unit 40. The calculated actual size of the abnormal area is associated with the pattern of the abnormality and its position, and stored in the actual size storage unit 40 as the inspection result.

[0042] In the display step of S55, the display unit 41 displays the inspection results stored in the actual dimension storage unit 40. In addition, the inspection results may be output to a printer (not shown) connected to the abnormality detection device 30.

[0043] As described above, according to the on-water inspection method 50, in the three route-specific photographing steps S51-1 to S51-3, the photographing directions of the cameras 11 and 12 can be changed while remaining aligned, or can be changed independently. Therefore, compared to the conventional technology in which a single camera whose photographing direction cannot be changed is used, the number of two-dimensional images that can be captured in the photographing step of S51 can be dramatically increased. Furthermore, when multiple cameras whose photographing directions cannot be changed are used, the number of two-dimensional images per voyage can be increased, but the number of viewpoints is limited by the number of cameras, and manufacturing costs may increase depending on the number of cameras. In contrast, surface inspection method 50 allows for a combination of the number of photographing steps for each route and changes in the photographing direction of cameras 11 and 12. Therefore, even with a small number of cameras, it is possible to photograph two-dimensional images from a variety of viewpoints throughout the entire photographing step S51. Therefore, surface inspection method 50 can improve the accuracy of detecting abnormalities while suppressing the manufacturing cost of surface inspection device 1 and the workload in the photographing step S51.

[0044] The surface inspection device 1 and surface inspection method 50 according to the present invention are not limited to those shown in the examples. For example, in the surface inspection device 1, the photographing unit 3 may be equipped with three or more cameras. Also, in the direction change means 14, either the hinge structure H1 or the hinge structure H2 may be omitted. Furthermore, a flexible arm may be used instead of the direction change means 14, and the waterproof case 13 may be omitted. Furthermore, the surface inspection device 1 may be a small vessel or a small unmanned boat, in addition to an underwater drone. In addition, the tilt angle α is not particularly limited in the route-by-route photographing steps S51-1 to S51-3 of the water inspection method 50. The route-by-route photographing step S51-3 may be omitted, or a fourth route-by-route photographing step may be added to the photographing step S51. Furthermore, the detection step S53 and the actual dimension calculation step S54, or the actual dimension calculation step S54, may be omitted. [Industrial Applicability]

[0045] The present invention can be used as an on-water inspection device and an on-water inspection method for inspecting a structure. [Explanation of symbols]

[0046] 1...surface inspection device 1a...front end 1b...rear end 2...airframe 3...photographing unit 4...support structure 5...propulsion structure 6...float 7...lighting device 8...slot 9...cable 10...propulsion control means 11, 12...camera 11a...lens 13...waterproof case 13a...mounting unit 14...direction change means 15...long member 15a...end 15b...slide hole 16...fixing unit 16a...attachment 16b, 16c...fastener 17...thumb screw 18...base 18a...upper end 19...body 19a...lower end 20...screw 21...support unit 22...screw 22a...axis center H1, H2...hinge structure 30...abnormality detection device 31...slot 32...input unit 33...control unit 34...image composition unit 35...Detection unit 36...Actual dimension calculation unit 37...Memory unit 38...Image memory unit 39...Abnormal location memory unit 40...Actual dimension memory unit 41...Display unit 50...Inspection method above water 60...Bridge 60a...Underside of girder

Claims

1. An on-water inspection device that moves on water along a set route, a body, a photographing unit that photographs a structure, a support structure that is attached to the body and supports the photographing unit, and a propulsion structure that moves on the water, the structure is a bridge installed above the water surface, The route follows the length or width of the bridge, the photographing unit is a plurality of cameras arranged in parallel at intervals along the width direction of the aircraft, The plurality of cameras each capture two-dimensional images that overlap each other in part in the width direction and at least part in the traveling direction of the on-water inspection device that is perpendicular to the width direction, the support structure includes a plurality of direction change units capable of changing the shooting directions of the plurality of cameras, respectively, and an elongated member to which the plurality of direction change units are attached; the elongated member is capable of adjusting the positions of the cameras in the width direction by sliding the direction change means along the longitudinal direction of the elongated member; This water-based inspection device is characterized in that the shooting direction can be changed for each of the multiple cameras when the water-based inspection device is traveling in the direction of travel, so that the camera faces directly at the structure, faces toward the structure in front of the camera, or faces toward the structure behind the camera.

2. A method for on-water inspection using an on-water inspection device that moves on water along a set route, comprising: The water inspection device includes a body, a photographing unit that photographs a structure, a support structure that is attached to the body and supports the photographing unit, and a propulsion structure that moves on the water, the structure is a bridge installed above the water surface, The route follows the length or width of the bridge, the photographing unit is a plurality of cameras arranged in parallel at intervals along the width direction of the aircraft, The plurality of cameras each capture two-dimensional images that overlap each other in part in the width direction and at least part in the traveling direction of the on-water inspection device that is perpendicular to the width direction, the support structure includes a plurality of direction change units capable of changing the shooting directions of the plurality of cameras, respectively, and an elongated member to which the plurality of direction change units are attached; the elongated member is capable of adjusting the positions of the cameras in the width direction by sliding the direction change means along the longitudinal direction of the elongated member; a photographing step in which, when the on-water inspection device moves on the water along the route, the plurality of cameras photographs the two-dimensional images including the structure at time intervals; The photographing step includes a plurality of photographing steps for each route, In the multiple route-by-route photographing process, at least one of the multiple direction change means is adjusted each time the on-water inspection device completes movement over the entire route, so that the multiple cameras each photograph multiple sets of the two-dimensional images having different combinations of the photographing directions of the multiple cameras, An underwater inspection method characterized in that the shooting direction can be changed for each of the multiple cameras when the underwater inspection device moves in the direction of travel, so that the camera faces directly at the structure, faces toward the structure in front of the camera, or faces toward the structure behind the camera.

3. an image construction step is provided after the photographing step, The underwater inspection method according to claim 2, characterized in that the image construction step comprises an image construction unit provided in an abnormality detection device that detects abnormalities in the structure, which constructs at least a three-dimensional image from multiple sets of the two-dimensional images.

4. The abnormality detection device includes an actual dimension calculation unit, an actual dimension calculation step is provided after the image construction step; the plurality of sets of two-dimensional images include the structure as well as a known scale reference attached to the structure; 4. The method for on-water inspection according to claim 3, characterized in that the actual dimension calculation step calculates the actual dimension of the abnormal part by comparing the size of the abnormal part of the structure detected from the three-dimensional image with the known size of the scale reference object included in the three-dimensional image.

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