WO2017175261A1

WO2017175261A1 - Turbidity detection apparatus, turbidity detection method, and submerged inspection apparatus

Info

Publication number: WO2017175261A1
Application number: PCT/JP2016/004654
Authority: WO
Inventors: 武史島本; 信昭中村
Original assignee: パナソニックＩｐマネジメント株式会社
Priority date: 2016-04-04
Filing date: 2016-10-21
Publication date: 2017-10-12

Abstract

This turbidity detection apparatus is provided with: a measuring member that has a dark area and a bright area; a camera that generates image data by photographing the dark area and the bright area of the measuring member through a liquid; and a turbidity detection unit that detects turbidity on the basis of image information about the dark area in the image data and image information about the bright area in the image data. The bright area of the measuring member has a higher brightness than the dark area. The turbidity detection apparatus can detect the turbidity of a liquid by means of a simple configuration.

Description

Turbidity detection device, turbidity detection method, and in-liquid inspection device

The present disclosure relates to a turbidity detection device that detects turbidity of a liquid, a turbidity detection method, and an in-liquid inspection device that inspects a structure in the liquid.

Patent Document 1 discloses an underwater inspection apparatus capable of clearly photographing an inspection target surface of an underwater structure even under high turbidity conditions when inspecting the underwater structure with an underwater camera. This underwater inspection apparatus includes an underwater camera for photographing a surface to be inspected of an underwater structure, a telescopic airtight container, fresh water supply means for supplying fresh water from a fresh water reservoir to the inside of the airtight container, and the apparatus main body in water A propulsion mechanism for moving in a three-dimensional direction. The sealed container is disposed at the front part of the underwater camera and has a first light transmitting part on the inspection target surface side and a second light transmitting part on the camera front part side. The propelling mechanism shrinks the sealed container during movement and extends it during shooting. The underwater camera takes a picture of the inspection target surface through the closed container filled with fresh water from the fresh water storage part with the first translucent part being in contact with or close to the inspection target surface due to expansion and contraction of the closed container. According to this underwater inspection apparatus, the underwater camera is moved from the fresh water storage portion in a state where the first light transmitting portion is in contact with or close to the inspection target surface of the underwater structure by expansion and contraction of the sealed container disposed in front of the underwater camera. Since the surface to be inspected is photographed through a sealed container filled with clean water, the surface to be inspected can be clearly photographed even under high turbidity conditions.

As described in Patent Document 1, when photographing an image of a structure (dam, bridge, etc.) in water, the turbidity of water is one of the factors affecting the image quality of the photographed image. Patent Document 2 discloses a method for detecting the turbidity of water. In Patent Document 2, the luminance distribution (histogram) of an image taken in water is measured, and the turbidity of water is determined based on the luminance distribution. ing.

Japanese Patent Laying-Open No. 2015-214335 JP-A-62-241513

The turbidity detection device includes a measurement member having a dark region and a bright region, a camera that captures the dark region and the bright region of the measurement member through a liquid and generates image data, and an image of the dark region in the image data A turbidity detecting unit for detecting turbidity based on the information and the image information of the bright region. The bright area of the measuring member has a higher brightness than the dark area.

This turbidity detection device can detect the turbidity of a liquid with a simple configuration.

FIG. 1 is a block diagram of the underwater inspection apparatus in the first embodiment. FIG. 2 is a block diagram of the turbidity detection apparatus in the first embodiment. FIG. 3 is an external view of the underwater robot of the underwater inspection apparatus in the first embodiment. FIG. 4A is a diagram showing a measurement member of the underwater inspection apparatus in the first embodiment. FIG. 4B is a diagram for explaining an attachment state of the measurement member of the underwater inspection apparatus in the first embodiment. FIG. 5A is a diagram illustrating the state of the measurement member photographed by the steering camera of the underwater inspection apparatus in the first embodiment. FIG. 5B is a diagram showing an image of the measurement member in the first embodiment. FIG. 5C is a diagram showing an image of the measurement member in the first embodiment. FIG. 6A is a diagram showing an image of a measurement member in the first embodiment. FIG. 6B is a diagram showing an image of the measurement member in the first embodiment. FIG. 6C is a diagram showing an image of the measurement member in the first embodiment. FIG. 7 is a diagram showing the relationship between the turbidity of water and the luminance difference obtained from the image of the measurement member in the first embodiment. FIG. 8 is a diagram showing the relationship between the turbidity detected by the underwater inspection apparatus in Embodiment 1 and the distance to the inspection object. FIG. 9 is a flowchart showing a process of controlling the distance to the inspection object based on the turbidity of water in the underwater inspection apparatus in the first embodiment. FIG. 10A is a diagram showing an image taken by the inspection camera of the underwater inspection apparatus in the first embodiment. FIG. 10B is a diagram showing an image taken by the inspection camera of the underwater inspection apparatus in the first embodiment. FIG. 11A is a diagram showing a relationship between the detected turbidity of the underwater inspection apparatus in Embodiment 1 and the distance to the inspection object. FIG. 11B is a diagram for explaining turbidity-subject distance relationship information of the underwater inspection apparatus in the first embodiment. FIG. 12A is a diagram illustrating a relationship between a luminance difference obtained from an image of a measurement member of the underwater inspection apparatus according to Embodiment 2 and a distance to an inspection object. FIG. 12B is a diagram illustrating correspondence information stored in the memory of the underwater inspection device according to Embodiment 2. FIG. 13 is a flowchart showing processing for controlling the distance to the inspection object based on the luminance difference obtained from the image of the measurement member in the underwater inspection apparatus according to the second embodiment. FIG. 14A is a diagram showing a relationship between a luminance difference obtained from an image of a measurement member of the underwater inspection apparatus in Embodiment 2 and a distance to an inspection object. FIG. 14B is a diagram showing the relationship between the luminance difference obtained from the image of the measurement member of the underwater inspection apparatus in Embodiment 2 and the distance to the inspection object. FIG. 15A is a diagram illustrating a measurement member of the underwater inspection apparatus according to Embodiment 3. FIG. 15B is a diagram for explaining a measurement member of the underwater inspection apparatus according to Embodiment 3. FIG. 16A is a diagram showing the relationship between the turbidity of water in the underwater inspection apparatus in Embodiment 3 and the resolution obtained from the image of the measurement member. FIG. 16B is a diagram illustrating correspondence information stored in the memory of the underwater inspection apparatus in the third embodiment. FIG. 17 is a flowchart showing processing for controlling the distance to the inspection object based on the resolution of the image of the measurement member in the underwater inspection apparatus according to the third embodiment. FIG. 18 is a cross-sectional view of the underwater inspection apparatus in the fourth embodiment.

Hereinafter, embodiments will be described in detail with reference to the drawings as appropriate. However, more detailed description than necessary may be omitted. For example, detailed descriptions of already well-known matters and repeated descriptions for substantially the same configuration may be omitted. This is to avoid the following description from becoming unnecessarily redundant and to facilitate understanding by those skilled in the art.

It is to be noted that this specification provides the accompanying drawings and the following description for those skilled in the art to fully understand the present disclosure, and is not intended to limit the claimed subject matter. Absent.

(Embodiment 1)
[1-1. Constitution]
FIG. 1 is a block diagram of an underwater inspection apparatus 10 (an example of an in-liquid inspection apparatus) equipped with the turbidity detection apparatus according to the first embodiment. The underwater inspection apparatus 10 takes an image of the surface of a structure in water in order to inspect a submerged portion of a structure such as a dam or a bridge, for example, a wall surface of a dam or a bridge girder. The underwater inspection apparatus 10 includes an underwater robot (Removal Operated Vehicle: ROV) 100 (an example of a submerged robot) that captures an image of a structure in water while moving in liquid water. And a ground unit 200 for controlling the operation of the above on the ground. For example, the underwater robot 100 and the ground unit 200 are connected by a communication cable 300 for passing an electrical signal. The operator manipulates the underwater robot 100 by operating the controller 220 while viewing the maneuvering image sent from the underwater robot 100. Hereinafter, specific configurations of the underwater robot 100 and the ground unit 200 will be described.

[1-1-1. Ground unit]
The ground unit 200 includes a computer 250 that issues instructions to the underwater inspection apparatus 10, a controller 220 that is operated by a user, and a communication unit 230 that performs communication between the computer 250 and the underwater robot 100.

The underwater robot 100 and the ground unit 200 are connected by a communication cable 300. The communication cable 300 is an electric wire for passing an electric signal, for example. The communication unit 230 is a unit that converts data from the computer 250 into a predetermined communication protocol (for example, PLC) suitable for communication via electric wires for passing electrical signals, and realizes communication between the underwater robot 100 and the computer 250. To do.

The computer 250 includes a display unit 211, a communication interface unit 212, a CPU 210, and a memory 218.

The display unit 211 includes a liquid crystal display or an organic EL display. The display unit 211 displays an operation image that is a moving image transmitted from the underwater robot 100. The communication interface unit 212 performs communication according to a predetermined standard such as a LAN standard.

The CPU 210 implements various functions by executing programs. For example, the CPU 210 implements the functions of the turbidity detection unit 214 and the distance determination unit 216 by executing a program. The CPU 210 acquires from the underwater robot 100 an operation image that is a moving image taken in water via the communication interface unit 212.

The memory 218 is a non-volatile memory such as a flash memory, and stores

information

218a and 218b necessary for determining the turbidity and the distance to the inspection object, as shown in FIG.

The pilot transmits an instruction for operating the underwater robot 100 to the underwater robot 100 using the controller 220. The controller 220 includes an operation foil, an operation stick, a switch, and the like. The pilot operates the underwater robot 100 by operating the controller 220 while viewing the control image displayed on the display unit 211.

FIG. 2 is a block diagram of the turbidity detection device 10A in the first embodiment. The turbidity detection device 10A includes a (steering) camera 116, a measurement member 170, a battery 160, a lighting device 120, a turbidity detection unit 214, and a memory 218 in the underwater inspection device 10 illustrated in FIG. Is provided. In Embodiment 1, the measurement member 170 has a plate shape.

[1-1-2. Underwater robot]
FIG. 3 is an external view of the underwater robot 100 of the underwater inspection apparatus 10. The underwater robot 100 moves and takes an image in accordance with a command from the ground unit 200. The underwater robot 100 transmits a maneuvering image to the ground unit 200 via the communication cable 300. The configuration of the underwater robot 100 will be described with reference to FIGS. 1 and 3. The underwater robot 100 includes a main unit 110, a lighting device 120, a thruster 130, a sonar 140, an inspection camera 150, a battery 160, and a measurement member 170. The underwater robot 100 further includes a frame 105 to which the above constituent members are attached.

The main unit 110 includes a communication unit 112 for communicating with the ground unit 200, a control unit 114 for controlling the operation of the underwater robot 100, and a control camera 116 for capturing an image for the operator. The main unit 110 is accommodated in a waterproof container 118 having a waterproof property. The control unit 114 includes a CPU, and executes a predetermined function by executing a predetermined program. The steering camera 116 shoots an image such as a moving image or a still image for a pilot on the ground to check the position of the underwater robot 100 and the state in the water. An image taken by the steering camera 116 is transmitted to the ground unit 200 via the communication unit 112. The communication unit 112 communicates with the ground unit 200 according to a predetermined communication standard such as TCP / IP.

The illumination device 120 irradiates the inspection object with light to take an image, and includes a light source such as an LED element and an optical system. The thruster 130 is a propulsion device that provides the propulsive force of the underwater robot 100 and includes, for example, a screw and a motor. In order to allow the underwater robot 100 to move three-dimensionally, a plurality of thrusters 130 are attached in the directions of three axes. The sonar 140 uses sound waves to measure the distance from the underwater robot 100 to an object such as a wall of a dam in the water. The battery 160 is a rechargeable battery, and supplies power for driving the underwater robot 100.

The inspection camera 150 captures an image of the inspection object in the water, and records image data of moving image data or still image data generated by the imaging on an internal recording medium (for example, a memory card). The inspection camera 150 can capture a higher-definition image (for example, a 4K image) than the steering camera 116 in order to capture an inspection image.

The underwater robot 100 has a vertical direction, a horizontal direction, and a front-back direction as shown in FIG. The direction of the inspection object whose image is captured by the steering camera 116 and the inspection camera 150 is defined as the forward direction, and the direction from the inspection camera 150 toward the steering camera 116 is defined as the upward direction. The underwater robot 100 translates vertically and horizontally while facing the inspection object, that is, with the optical axes of the

cameras

116 and 150 being substantially orthogonal to the surface of the inspection object to be imaged. Take a picture of the surface.

The underwater robot 100 further includes a measurement member 170. FIG. 4A shows the measurement member 170. The measuring member 170 has a dark region 170b and a bright region 170w having a higher brightness than the dark region. The dark area 170b and the bright area 170w are provided on the surface 170k of the measuring member 170. In the first embodiment, the hues of the dark region 170b and the bright region 170w are the same, the dark region 170b is black, and the bright region 170w is white.

FIG. 4B is a diagram illustrating an attachment state of the measurement member 170. The measurement member 170 is supported by the support member 180 and fixed to the upper part of the waterproof container 118. In particular, the measurement member 170 is disposed between the illumination device 120 and the steering camera 116 such that a surface 170k provided with a dark region 170b and a bright region 170w faces downward in the vertical direction and faces the camera 116. . In other words, the surface 170k provided with the dark region 170b and the bright region 170w of the measuring member 170 has a vertical direction and a vertical direction when the underwater robot 100 has a posture in which the vertical direction coincides with the vertical direction. It spreads in the direction between the horizontal direction perpendicular to the direction. By arranging the measurement member 170 in this way, the sunlight LL1 incident from above is blocked by the lighting device 120 and the measurement member 170 and does not reach the steering camera 116. For this reason, when the water depth is shallow, it can exclude that sunlight LL1 injects with respect to the measurement member 170. FIG. Further, since the illumination light LL2 from the illumination device 120 is blocked by the measurement member 170 and does not reach the control camera 116, the influence of the illumination light LL2 on the measurement member 170 when the water depth is deep can be eliminated. The light irradiated to the measurement member 170 becomes scattered light from the surroundings or reflected light that has passed through the path including the inspection target 10 </ b> P, the waterproof container 118, and the measurement member 170 from the illumination device 120. For this reason, the bright region 170w of the measuring member 170 is not saturated and the contrast between the bright region 170w and the dark region 170b can be detected stably.

FIG. 4B shows the angle of view X of the control camera 116, that is, the shooting range R1. FIG. 5A shows the angle of view X (shooting range R1) of the steering camera 116 when viewed from the steering camera 116. FIG. As shown in FIG. 5A, the positional relationship between the measurement member 170 and the steering camera 116 is defined so that the image captured by the steering camera 116 includes only the lower portion 170p of the measurement member 170 (FIG. 4B). reference). FIG. 5B shows an image taken by the steering camera 116. In the upper center of the image P1 photographed by the steering camera 116, a lower portion 170p) which is a part of the measuring member 170 is included in the image P1. Note that since the image of the measurement member 170 is not necessary for the operation, the measurement member 170 is removed from the image (see FIG. 5B) taken by the operation camera 116 as the image presented (displayed) to the operator. It may be an image.

FIG. 5C shows an enlarged region R2 shown in FIG. 5B. In particular, the computer 250 extracts the luminance of a partial region R11 of the dark region 170b and a partial region R12 of the bright region 170w of the measurement member 170 reflected in the image captured by the control camera 116, and becomes turbid. Find the degree. As described above, the turbidity is detected using the information of the dark areas 170b and the partial areas R11 and R12 of the bright area 170w of the measurement member 170 reflected in the captured image. Even when there is a variation in the attachment position of the camera 116, it is possible to accurately extract information on the dark area 170b and the bright area 170w. Specifically, the turbidity detection unit 214 of the computer 250 calculates an average value of the luminance in the partial areas R11 and R12 of the dark area 170b and the bright area 170w, as the luminance of the dark area 170b and the luminance of the bright area 170w. Value. The turbidity detection unit 214 calculates the difference between the luminance of the dark region 170b and the luminance of the bright region 170w, and calculates turbidity based on the luminance difference (details will be described later).

Note that the measurement member 170 is not limited to a plate shape, and may have other shapes such as a column shape as long as it has a dark region 170b and a bright region 170w.

[1-2. Operation]
The operation of the underwater inspection apparatus 10 configured as described above will be described below.

The underwater inspection apparatus 10 takes an image of the surface of the inspection object 10P (FIG. 4B) in the water. At that time, an image is taken from a position away from the inspection object 10P by a predetermined distance. The farther the predetermined distance is, the wider range can be photographed, and the inspection object 10P can be inspected efficiently. However, if the turbidity of water is high, a clear captured image cannot be obtained if the distance is long. Therefore, the distance is set according to the turbidity of water so that a clear image can be obtained. Therefore, the underwater inspection apparatus 10 in Embodiment 1 detects the turbidity of water and determines the distance to the inspection object 10P according to the detected turbidity. First, the operation of detecting the turbidity of water in the underwater inspection apparatus 10 will be described.

[1-2-1. Turbidity detection operation]
6A to 6C show the relationship between the turbidity of water, which is a liquid, and the luminance difference (contrast) in an image obtained by imaging the measurement member 170. FIG. 6A to 6C show only an image of a partial region R2 in the entire captured image for convenience of explanation. FIG. 6A shows a captured image of the measurement member portion 170p when the turbidity is relatively low. FIG. 6C shows a captured image of the portion 170p of the measurement member 170 when the turbidity is relatively high. FIG. 6B shows a captured image of the portion 170p of the measurement member 170 when the turbidity is intermediate between the case shown in FIG. 6A and the case shown in FIG. 6C. As shown in FIGS. 6A to 6C, the lower the turbidity of water, the greater the difference (contrast) between the luminance of the dark area 170b and the luminance of the bright area 170w of the portion 170p of the measuring member 170, and the turbidity in water is higher. The higher the difference, the smaller the difference in brightness. Thus, turbidity is detected from the difference in luminance based on the correlation between the luminance difference (contrast) between the dark region 170b and the bright region 170w and turbidity.

FIG. 7 shows the relationship between the turbidity of water and the normalized luminance difference that is the difference in luminance obtained from the captured image of the measuring member 170. This relationship can be obtained from actually measured values. Here, the normalized luminance difference Nc is expressed by Equation 1 using the luminance Ib of the dark region 170b of the captured image of the measurement member 170, the luminance Iw of the bright region 170w, and the correction coefficients A, B, and C.

As shown in FIG. 7, the higher the turbidity, the smaller the luminance difference (normalized luminance difference Nc). Luminance difference-turbidity correspondence information 218a indicating the relationship between turbidity and normalized luminance difference Nc as shown in FIG. 7 is obtained in advance and stored in the memory 218 of the computer 250 of the ground unit 200. The luminance difference-turbidity correspondence information 218a is given as a table or a function, for example.

Furthermore, in the computer 250 of the ground unit 200, turbidity-distance correspondence information 218b indicating the relationship between the detected turbidity and the distance to the inspection object 10P is stored in the memory 218. FIG. 8 shows turbidity-distance correspondence information 218b showing the relationship between the detected turbidity and the distance to the inspection object 10P. The memory 218 stores a table or function giving the relationship shown in FIG. 8 as turbidity-distance correspondence information 218b.

The computer 250 can obtain the turbidity based on the luminance difference (normalized luminance difference Nc) by referring to the luminance difference / turbidity correspondence information 218a, and can refer to the turbidity / distance correspondence information 218b. The distance from the underwater robot 100 to the inspection object 10P can be determined based on the turbidity.

[1-2-2. Distance control operation according to turbidity]
FIG. 9 is a flowchart showing a process in the ground unit 200 for controlling the distance to the inspection object 10P based on the turbidity of water in the first embodiment.

CPU210 acquires the image image | photographed with the camera 116 for operation of the underwater robot 100 via the communication unit 230 and the communication interface part 212 (step S21). The turbidity detection unit 214 of the CPU 210 calculates the brightness of each of the bright area 170w and the dark area 170b based on the image of the portion 170p of the measurement member 170 included in the acquired image (step S22). Next, the turbidity detection unit 214 obtains a normalized luminance difference Nc that is a value obtained by normalizing the obtained luminance difference between the bright region 170w and the dark region 170b based on (Equation 1) (step S23).

Further, the turbidity detecting unit 214 refers to the luminance difference-turbidity correspondence information 218a (see FIG. 7) and calculates the turbidity from the obtained normalized luminance difference Nc (step S24). Next, the distance determining unit 216 refers to the turbidity-distance correspondence information 218b (see FIG. 8), and determines the distance from the obtained turbidity to the inspection object 10P (step S25).

The CPU 210 of the computer 250 controls the position of the underwater robot 100 so that the distance from the underwater robot 100 to the inspection object 10P becomes the determined distance (step S26). The underwater robot controls the thruster 130 according to an instruction from the computer 250 to maintain the distance between the underwater robot 100 and the inspection object 10P at the determined distance.

By the control as described above, the distance from the underwater robot 100 to the inspection object 10P can be controlled to a distance according to the turbidity of water. That is, as the turbidity increases, the distance is controlled so that the distance between the underwater robot 100 and the inspection object 10P becomes shorter.

10A and 10B show images taken by the inspection camera 150. FIG. For example, when the turbidity is high and a clear image cannot be obtained by the inspection camera 150 at a distance Dx from the inspection object 10P to the underwater robot 100 (inspection camera 150) as shown in FIG. As shown in 10B, the underwater robot 100 is brought closer to the inspection object 10P so that the distance from the underwater robot 100 to the inspection object 10P is the distance Dy (<Dx). As a result, as shown in FIG. 10B, the angle of view of the image captured by the inspection camera 150 is reduced, but a clear image can be obtained.

In the above example, the memory 218 holds one luminance difference-turbidity correspondence information 218a. The memory 218 holds a plurality of luminance difference-turbidity correspondence information, and may be used by switching according to the application. For example, as shown in FIG. 11A, the memory 218 may hold two types of luminance difference-

turbidity correspondence information

1218a and 2218a, each indicating the relationship between turbidity and the subject distance to the inspection object 10P. The luminance difference-turbidity correspondence information 1218a is used when performing a rough inspection, and the luminance difference-turbidity correspondence information 2218a is used when performing a precise inspection. When the brightness difference / turbidity correspondence information 1218a is used, the underwater robot 100 is separated from the inspection object 10P and the image of the inspection object 10P is taken, but the clarity of the image is deteriorated, but a wide range that is good at once. Therefore, it is possible to shorten the time for capturing an image of the entire inspection range. Such an inspection is effective when it is desired to first obtain an overview of the entire inspection object 10P. On the other hand, when the luminance difference-turbidity correspondence information 2218a is used, the range that can be captured at a time becomes narrower by capturing the image of the inspection target 10P by bringing the underwater robot 100 closer to the inspection target 10P, and the inspection range is reduced. Although it takes a long time to capture the entire image, the clarity of the image can be improved. Therefore, as shown in FIG. 11A, the memory 218 holds two types of brightness difference-

turbidity correspondence information

1218a and 2218a according to the use for rough inspection and precise inspection, and switches between them. By using it, it becomes possible to perform a suitable inspection according to the application.

Further, the turbidity-distance correspondence information 218b shown in FIG. 8 gives the distance to the subject continuously with respect to the turbidity, but the subject distance information is not limited to this. FIG. 11B shows other turbidity-distance correspondence information 1218b in the first embodiment. The turbidity-distance correspondence information 1218b shown in FIG. 11B gives the distance to the inspection object 10P stepwise based on the turbidity, that is, discretely.

[1-3. Effect]
As described above, the turbidity detection device 10A is used for steering to generate image data by photographing the measurement member 170 having the dark region 170b and the bright region 170w and at least a part 170p of the measurement member 170 in water. Turbidity that calculates turbidity based on image information (luminance difference) between the dark area 170b and the bright area 170w in the image indicated by the acquired image data, the communication interface unit 212 that acquires image data from the camera 116, and the steering camera 116. Degree detector 214 (CPU 210). In the first embodiment, the dark region 170b is black and black, and the bright region 170w is white and white.

In addition, the underwater inspection apparatus 10 according to the first embodiment takes an image of the inspection object 10P in the water, includes a turbidity detection apparatus 10A, and controls the distance to the inspection object 10P according to the turbidity. . That is, the underwater inspection apparatus 10 captures image data by photographing a measurement member 170 having a dark region 170b and a bright region 170w, and at least a part of the dark region 170b and the bright region 170w of the measurement member 170 in water. A computer that controls the distance between the inspection object 10P and the underwater robot 100 based on the image information of the camera 116 (steering camera) to be generated and the dark region 170b and the bright region 170w indicated by the image data generated by the camera 116. 250.

As described above, in the first embodiment, turbidity can be detected based on the image information of the measurement member 170. Since the measurement member 170 is photographed in a state of being immersed in water, it is not particularly necessary to store it in the water pressure resistant container. The measuring member 170 may be small and light and can be easily mounted on the underwater robot 100. Thus, 10 A of turbidity detection apparatuses of a simple structure can be provided.

Also, the underwater inspection apparatus 10 controls the distance between the underwater robot 100 and the inspection object 10P according to the turbidity of water. Specifically, the underwater inspection apparatus 10 controls the distance so that the higher the turbidity, the smaller the distance between the underwater robot 100 and the inspection object 10P. For this reason, even in a cloudy underwater environment, an image of the inspection object 10P can be taken at a distance suitable for inspection.

(Embodiment 2)
In the underwater inspection apparatus 10 of the first embodiment, the turbidity of water is first obtained from the luminance difference obtained from the captured image of the measuring member 170, and then the distance from the turbidity to the inspection object 10P is obtained. In the underwater inspection apparatus 10 according to the second embodiment, a configuration for directly obtaining the subject distance from the luminance difference obtained from the captured image of the measurement member 170 will be described. The configuration and operation of the underwater inspection apparatus 10 of the second embodiment are basically the same as those shown in the first embodiment. Hereinafter, the configuration and operation of the underwater inspection apparatus 10 of the present embodiment, which are different from those of the first embodiment, will be described.

FIG. 12A shows the relationship between the normalized luminance difference Nc obtained from the captured image of the measurement member 170 and the distance to the inspection object in the second embodiment. This relationship can be obtained by combining the luminance difference-turbidity correspondence information 218a (see FIG. 7) and the turbidity-distance correspondence information 218b (see FIG. 8) shown in the first embodiment.

The memory 218 of the computer 250 of the underwater inspection apparatus 10 according to the second embodiment stores the luminance difference-distance correspondence information 218c indicating the relationship between the normalized luminance difference Nc shown in FIG. 12B and the distance to the inspection object 10P. Yes.

FIG. 13 is a flowchart showing a process for controlling the distance between the underwater robot 100 and the inspection object 10P based on the turbidity of water in the ground unit 200 of the second embodiment.

The CPU 210 of the computer 250 acquires an image captured by the steering camera 116 of the underwater robot 100 via the communication unit 230 and the communication interface unit 212 (step S31). The turbidity detection unit 214 obtains the brightness of each of the bright region 170w and the dark region 170b of the portion 170p of the measurement member 170 based on the image of the portion 170p of the measurement member 170 included in the acquired image (step S32). Next, the turbidity detection unit 214 obtains a normalized luminance difference Nc using (Equation 1) from the obtained luminance of each of the bright region 170w and the dark region 170b (step S33).

The CPU 210 of the computer 250 refers to the luminance difference / distance correspondence information 218c (see FIGS. 12A and 12B) and calculates the distance from the obtained normalized luminance difference Nc to the inspection object 10P (step S34).

The CPU 210 of the computer 250 controls the position of the underwater robot 100 so that the distance from the underwater robot 100 to the inspection object 10P is the calculated distance (step S35).

As described above, in the underwater inspection apparatus 10 according to the second embodiment, the distance from the luminance difference obtained from the captured image of the portion 170p of the measuring member 170 to the inspection target 10P is directly calculated, and the underwater robot 100 is based on the calculated distance. And the distance to the inspection object 10P is controlled.

14A and 14B show other luminance difference-

distance correspondence information

1218c and 2218c in the second embodiment. The relationship between the luminance difference and the subject distance can be set as appropriate according to the inspection application, but basically the subject distance monotonously increases with respect to the luminance difference. Therefore, the normalized luminance difference Nc has a relationship between the distance to the inspection object 10P and the luminance difference-distance correspondence information 1218c shown in FIG. 14A. Alternatively, in the luminance difference / distance correspondence information 2218c shown in FIG. 14B, the distance corresponds to the luminance difference in a step-like manner (discretely).

(Embodiment 3)
The configuration and operation of the underwater inspection apparatus 10 in the third embodiment are basically the same as those shown in the first embodiment. Hereinafter, the configuration and operation of the underwater inspection apparatus 10 of the third embodiment, which is different from the first embodiment, will be described.

In Embodiment 1, the measurement member 170 having one bright area 170w and one dark area 170b shown in FIG. 4A is used. 15A and 15B show a bright region 170w and a dark region 170b of the measurement member 170 in the underwater inspection apparatus 10 according to the third embodiment. In the measurement member 170 shown in FIGS. 15A and 15B, the dark region 170b has a plurality of dark portions 170s having different widths. The bright region 170w has a plurality of bright portions 170t arranged alternately with the plurality of dark portions 170s. In the third embodiment, the plurality of dark portions 170s are black and black, and the plurality of light portions 170t are white and white. The plurality of dark portions 170s and the plurality of bright portions 170t arranged alternately constitute a resolution chart.

The image of the resolution chart is taken with the steering camera 116, the taken image is analyzed, the resolution of the image is obtained, and the turbidity of water can be detected from the obtained resolution. In this case, as shown in FIG. 16A, the relationship between resolution and turbidity is experimentally obtained in advance. As shown in FIG. 16B, the relationship is stored in the memory 218 of the computer 250 as resolution-turbidity correspondence information 218d. The distance determination unit 216 of the computer 250 can determine the distance from the resolution of the captured image to the inspection object by referring to the resolution-turbidity correspondence information 218d.

FIG. 17 is a flowchart showing processing for controlling the distance of the underwater robot 100 based on the turbidity of water in the ground unit 200 in the third embodiment.

The CPU 210 of the computer 250 acquires an image photographed by the steering camera 116 of the underwater robot 100 via the communication unit 230 and the communication interface unit 212 (step S41). The turbidity detection unit 214 obtains the resolution of the resolution chart image of the portion 170p of the measurement member 170 included in the acquired image (step S42). Next, the turbidity detection unit 214 refers to the resolution-turbidity correspondence information 218d to obtain turbidity from the obtained resolution (step S43).

Next, the distance determination unit 216 refers to the turbidity-distance correspondence information 218b and calculates the distance from the obtained turbidity to the inspection object 10P (step S44).

The CPU 210 of the computer 250 controls the position of the underwater robot 100 so that the distance from the underwater robot 100 to the inspection object 10P becomes the calculated distance (step S45).

As described above, the turbidity can be obtained from the resolution of the resolution chart image of the measurement member 170. As in the second embodiment, resolution-distance correspondence information that associates the resolution with the distance to the inspection object 10P is prepared in advance, and the distance from the image resolution to the inspection object 10P is directly determined. Can also be sought.

(Embodiment 4)
FIG. 18 is a cross-sectional view of the underwater inspection apparatus 10C in the fourth embodiment. In FIG. 18, the same reference numerals are assigned to the same parts as those of the underwater inspection apparatus 10 in Embodiment 1 shown in FIGS. 1 to 4B. 10C of underwater inspection apparatuses are further provided with the light-shielding part 401 which covers the measurement member 170 of the underwater inspection apparatus 10 in Embodiment 1 shown to FIG. 4B, and the reference light source 402. FIG. The light shielding unit 401 covers a part of the angle of view X of the control camera 116.

In the underwater inspection apparatus 10 according to Embodiment 1 shown in FIGS. 1 to 4B, the light irradiated on the measurement member 170 is scattered light from the surroundings, or the inspection object 10P, the waterproof container 118, and the measurement from the illumination device 120. The reflected light that has passed through the path including the member 170, that is, the light around the measuring member 170.

In the underwater inspection apparatus 10 </ b> C shown in FIG. 18, the light shielding unit 401 blocks the light around the measurement member 170 so as not to reach the measurement member 170. The reference light source 402 irradiates light to the bright area 170w and the dark area 170b of the measuring member 170. In the underwater inspection apparatus 10C, the measurement member 170 can be irradiated with stable light regardless of the surrounding light of the measurement member 170, so that the contrast between the bright region 170w and the dark region 170b of the measurement member 170 can be detected more stably.

(Other embodiments)
As described above, Embodiments 1 to 4 have been described as examples of the technology disclosed in the present application. However, the technology in the present disclosure is not limited to this, and can also be applied to an embodiment in which changes, replacements, additions, omissions, and the like are appropriately performed. Also, it is possible to combine the components described in the first to third embodiments to form a new embodiment. Therefore, other embodiments will be exemplified below.

In the above embodiment, the turbidity is determined based on the information (brightness difference and resolution) of the image captured by the steering camera 116 of the underwater robot 100, but the turbidity is determined from the information of the image captured by the inspection camera 150. The degree may be determined.

In the above embodiment, the steering camera that captures the steering image and the inspection camera that captures the inspection image are provided separately, but the steering image and the inspection image are provided by the same camera. You may make it photograph.

The configuration of the turbidity detection device shown in the above embodiment is not limited to the detection of turbidity of water, but can also be applied to the detection of turbidity of liquids other than water.

In the above embodiment, the program executed by the CPU 210 may be provided by a recording medium such as a DVD-ROM or CD-ROM, or may be downloaded from a server on a network via a communication line. The functions of the CPU 210 are realized by cooperation of hardware and software (application program), but may be realized only by a hardware circuit designed exclusively for realizing a predetermined function. Therefore, instead of the CPU 210, the above-described functions may be realized by an MPU, DSP, FPGA, ASIC, or the like.

As described above, the embodiments have been described as examples of the technology in the present disclosure. For this purpose, the accompanying drawings and detailed description are provided.

Accordingly, among the components described in the accompanying drawings and the detailed description, not only the components essential for solving the problem, but also the components not essential for solving the problem in order to illustrate the above technique. May also be included. Therefore, it should not be immediately recognized that these non-essential components are essential as those non-essential components are described in the accompanying drawings and detailed description.

In addition, since the above-described embodiment is for illustrating the technique in the present disclosure, various modifications, replacements, additions, omissions, and the like can be performed within the scope of the claims or an equivalent scope thereof.

The turbidity inspection apparatus according to the present disclosure is useful for an inspection apparatus that inspects an object (dam wall, bridge girder of a bridge, etc.) in water.

10 Underwater inspection equipment (in-liquid inspection equipment)
10A Turbidity Detector 100 Underwater Robot (Liquid Robot)
110 Main unit 112 Communication unit 114 Control unit 116 Steering camera 120 Illumination device 130 Thruster 140 Sonar 150 Inspection camera 160 Battery 170 Measuring member 200 Ground unit 210 CPU
211 Display unit 214 Turbidity detection unit 216 Distance determination unit 212 Communication interface unit 218 Memory 218a Luminance difference-turbidity correspondence information 218b Turbidity-distance correspondence information 218c Luminance difference-distance correspondence information 218d Resolution-turbidity correspondence information 220 Controller 230 Communication unit 250 Computer 300 Communication cable

Claims

A turbidity detection device for detecting the turbidity of a liquid,
A measuring member having a dark region and a bright region having a higher brightness than the dark region;
A camera that captures the dark region and the bright region of the measurement member through the liquid to generate image data;
A turbidity detector that detects the turbidity based on the first image information of the dark region and the second image information of the bright region in the image data;
A turbidity detection device comprising:
A lighting device;
The turbidity detection device according to claim 1, wherein the measurement member is disposed between the illumination device and the camera in a state where the dark region and the bright region face the camera.
The first image information of the dark region is a luminance of the dark region;
The second image information of the bright area is the brightness of the bright area;
The turbidity detection device according to claim 1, wherein the turbidity detection unit detects the turbidity based on a difference between the luminance of the dark region and the luminance of the bright region.
The turbidity detection device according to claim 1, wherein the dark region is black and the bright region is white.
2. The turbidity detection unit according to claim 1, wherein the turbidity detection unit obtains a resolution of an image indicated by the image data from the first image information and the second image information, and detects the turbidity based on the resolution. Degree detection device.
The dark region has a plurality of black regions having different widths from each other,
The turbidity detection device according to claim 5, wherein the bright region has a plurality of white regions arranged alternately with the plurality of black regions.
An in-liquid inspection device for taking an image of an inspection object in a liquid,
A measuring member having a dark region and a bright region having a higher brightness than the dark region;
A camera that captures the dark area and the bright area through the liquid to generate image data;
A control unit for controlling a distance between the inspection object and the submerged inspection device based on the first image information of the dark region and the second image information of the bright region indicated by the image data;
In-liquid inspection device with
Further comprising an illumination device for irradiating the inspection object with light,
The in-liquid inspection device according to claim 7, wherein the measurement member is disposed between the illumination device and the camera in a state where the dark region and the bright region face the camera.
The first image information of the dark region is a luminance of the dark region;
The second image information of the bright area is the brightness of the bright area;
The liquid according to claim 7, wherein the control unit controls the distance between the inspection object and the submerged inspection apparatus based on a difference between the luminance of the dark region and the luminance of the bright region. Medium inspection device.
The submerged inspection apparatus according to claim 7, wherein the dark region is black and the bright region is white.
The control unit obtains a resolution of an image indicated by the image data based on the first image information and the second image information, and based on the resolution, the inspection object and the submerged inspection apparatus The in-liquid inspection device according to claim 7, wherein the distance between the two is controlled.
The dark region has a plurality of dark portions having different widths from each other;
The in-liquid inspection device according to claim 11, wherein the bright region has a plurality of bright portions arranged alternately with the plurality of dark regions.
A measuring member having a dark area and a bright area having a higher brightness than the dark area is disposed in the liquid;
Photographing the dark region and the bright region of the measuring member through the liquid to generate image data,
Detecting the turbidity of the liquid based on image information of the dark area and the bright area in the image indicated by the image data;
Turbidity detection method.
The turbidity detection method according to claim 13, wherein the dark region is black and the bright region is white.