JP2018090981A - Inspection device and inspection method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inspection device and an inspection method capable of determining whether or not a resolution of an acquired image is right at that point it was acquired, and capable of performing an inspection based on an image by acquiring the image having an appropriate resolution in which it is possible to check the state of cracking, etc.SOLUTION: An inspection device of the claimed invention comprises means for acquiring an image, means for measuring a distance, means for measuring an attitude, means for estimating a resolution, and means for determining image acquisition. The means for estimating a resolution estimates the resolution of an acquired image on the basis of "the distance from the means for acquiring an image and an object" and "the posture of the means for acquiring an image". The means for determining image acquisition determines image acquisition to be affirmative when a resolution estimated by the means for estimating a resolution is higher than a resolution threshold value and determines image acquisition to be negative when the resolution estimated by the means for estimating a resolution is lower than the resolution threshold value.SELECTED DRAWING: Figure 5

Description

  The present invention relates to an inspection technique for an object, and more specifically, to an apparatus and method capable of inspecting based on an image having a resolution that can confirm a damaged state of the object. is there.

  It has been pointed out that the construction infrastructure (hereinafter referred to as “construction infrastructure”) that has been intensively developed during the period of high economic growth has already undergone considerable deterioration. In 2014, the “Proposal for Full Implementation of Road Aging Measures (Social Capital Development Council)” was compiled, giving examples of the Choshi Tunnel in 2012, “In the near future, human life and society such as the collapse of bridges” It will lead to a fatal situation related to the equipment, "he urged and emphasized the importance of maintaining construction infrastructure.

  Against this backdrop, the government promulgated a ministerial ordinance to revise a part of the Road Law Enforcement Regulations, and showed a specific method for inspecting construction infrastructure, points of major deformations, pictures of judgment cases, etc. The inspection procedure is formulated. This periodic inspection procedure covers bridges with a length of 2.0 m or more, which is said to be about 700,000 bridges. The first inspection is performed within 2 years after the start of service, and then the periodic inspection is performed once every 5 years thereafter. I am going to do that.

  In the construction infrastructure inspection, damaged parts such as concrete cracks are detected, and the results are recorded for later confirmation. For example, when detecting cracks in a concrete floor slab of a bridge, it is necessary to record not only detailed information such as the degree of cracking (length, width, etc.) but also where the cracks are occurring. In the conventional inspection, cracks are visually detected, and the positions of the cracks are sometimes written on the structure drawings prepared in advance.

  However, it is not so easy to visually inspect the bridge deck (especially the lower surface). Normally, scaffolds are assembled to get close to the bridge, but if the girder height is extremely high, a considerable scale of scaffolding is required. In the case of an overpass or overpass, a scaffold is assembled on a road or track, and in some cases, it is not possible to actually build a scaffold. Also, it is not easy to write the crack position on the scaffold on the drawing. The work of comparing the position on the scaffold with the drawings at the site is more difficult than you think, and the drawings themselves will be large on long bridges, etc., so it is quite complicated to bring in the site or to expand it and fill it in. It becomes work.

  Therefore, in recent years, inspection work using images has also been performed. Since the damaged part can be confirmed from the acquired image, the damage can be detected without being limited in place and time, and the person other than the inspector can also determine the damage more objectively. Furthermore, if an image is acquired in an appropriate photographing range, a damage position such as a crack can be recorded, so that the trouble of preparing the drawing and the trouble of filling in the drawing at the site can be saved. For example, Patent Document 1 proposes a method of inspecting using a carriage moving on a bridge surface and an arm attached to the carriage. The tip of the arm is arranged on the lower surface of the bridge and connected to the tip of the arm. Proposed a technique in which a flying object photographs the underside of a bridge with a camera.

Japanese Patent Laid-Open No. 2006-79684

  In addition to the case where the image is taken close to the lower surface of the bridge as in Patent Document 1, it is not necessary to assemble the scaffold in the inspection work using the image including the case where the image is taken with the telephoto lens from below, and the damaged part is This is very suitable in that it saves the trouble of drawing on the site. However, in order to detect damage such as cracks from an image, an image having a considerable resolution must be acquired. However, it is not easy to check the resolution on the spot when the image is acquired, and if the resolution of the image confirmed at a later date is not sufficient, it will result in going to the site again and acquiring an image with an appropriate resolution. .

  In addition, in order to record the arrangement of cracks and the like, it is necessary to obtain an image (so-called panoramic view) of the entire inspection target (for example, bridge floor slab), but a limited range of images to obtain a considerable resolution. There is a restriction that it must be acquired. Therefore, it is conceivable to obtain an entire image by connecting individual images. In this case, it is necessary to overlap (wrap) adjacent images to a considerable extent. However, it is difficult to confirm the degree of overlap on the spot when the image is acquired. If there is not enough overlap between images confirmed at a later date, the result is that the user goes to the site again and acquires an appropriately overlapped image.

  The object of the present invention is to determine whether the resolution is right or wrong on the spot when the image is acquired, and to acquire an image having an appropriate resolution that can confirm the state of cracks, etc. It is an object to provide an inspection device and an inspection method that can be performed.

  The present invention is an invention made on the basis of an unconventional idea of estimating the resolution of an acquired image on the spot based on the distance from the image acquiring unit to the object and the attitude of the image acquiring unit. is there.

  The inspection apparatus of the present invention is an apparatus that inspects an object using an image, and includes an image acquisition unit, a distance measurement unit, a posture measurement unit, a resolution estimation unit, and an image acquisition determination unit. . Of these, the distance measuring means measures the distance from the image acquiring means to the object, and the attitude measuring means measures the attitude of the image acquiring means. Further, the resolution estimation means estimates the resolution of the acquired image based on the “distance from the image acquisition means to the object” and the “attitude of the image acquisition means”. When the estimated resolution exceeds the resolution threshold, image acquisition is affirmed, and when the resolution falls below the resolution threshold, image acquisition is denied. The inspection device of the present invention can also constitute a distance measuring means and an attitude measuring means by a laser measuring instrument. This laser measuring instrument has three or more laser light irradiation means for irradiating laser light (however, the positional relationship with the image acquisition means is known), or laser light (however, the positional relationship with the image acquisition means is It is provided with a movable laser beam irradiation means for irradiating (known).

  The inspection device according to the present invention may further include a crack extracting unit that extracts a crack of the object from the image acquired by the image acquiring unit.

  The inspection device according to the present invention may instruct the image acquisition unit to acquire an image when the image acquisition determination unit affirms the image acquisition. In this case, the image acquisition unit acquires an image of the object according to a command from the image acquisition determination unit.

  The inspection device of the present invention may further include a pan head, a calculation unit, and a control unit. The camera platform fixes the image acquisition means, and can move the image acquisition means and change the posture. In addition, when the image acquisition determination unit denies acquisition of the image, the control unit selects an image that exceeds the resolution threshold based on the distance from the image acquisition unit to the object, the attitude of the image acquisition unit, and the estimated resolution of the image. The position and orientation of image acquisition means that can be acquired are calculated. The control means controls the camera platform so that the image acquisition means has the position and orientation calculated by the calculation means.

  The inspection method of the present invention is a method of acquiring an image of an object by an image acquisition means and inspecting the object. A distance measurement process, an attitude measurement process, a resolution estimation process, an image acquisition determination process, an image It is a method comprising an acquisition step. Of these, the distance measurement step measures the distance from the image acquisition means to the object, the posture measurement step measures the attitude of the image acquisition means, and the resolution estimation step determines "the distance from the image acquisition means to the object" And the resolution of the acquired image is estimated based on “the posture of the image acquiring unit”. Further, in the image acquisition determination step, when the resolution of the image estimated in the resolution estimation step exceeds the resolution threshold, image acquisition is affirmed, and when the resolution is lower than the resolution threshold, image acquisition is denied, and in the image acquisition step, the determination step When the image acquisition is affirmed, an image of the object is acquired. Then, the object is inspected based on the image acquired in the image acquisition process.

The inspection device and the inspection method of the present invention have the following effects.
(1) Since the inspection work is based on an image, it is not necessary to assemble a scaffold, and it is possible to save the trouble of writing a damaged part on the site.
(2) Since an image is acquired after determining whether the resolution is right or wrong, an image with sufficient resolution can be acquired, and the trouble of going to the site again at a later date can be avoided.

The longitudinal cross-sectional view which shows a road bridge. The top view which shows the floor slab of 1 diameter which looked from the lower part, and shows the floor slab lower surface equivalent to one panel. The partial top view which shows one panel. The flowchart which shows the flow of the main processes and processes of this invention. The side view which shows the condition which measures the distance of the image acquisition means on a tripod, and a floor slab lower surface, and image | photographs the floor slab lower surface with an image acquisition means. The block diagram which shows the main structures of this invention. The image figure which shows the crack extracted from the image.

  An example of an embodiment of an inspection device and an inspection method of the present invention will be described with reference to the drawings. The inspection device and inspection method of the present invention can be any object including a concrete structure (hereinafter referred to as “object”), but here, for convenience, the road bridge shown in FIG. An example of a bridge inspection that uses the lower surface of a concrete floor slab (hereinafter simply referred to as “the floor slab lower surface”) as an object and grasps the state of cracks generated on the lower surface of the floor slab will be described.

  When inspecting the bottom of the floor slab, the entire floor slab is divided into multiple panels in advance. The panel is one unit of the inspection range, and is set by dividing the bridge axis direction by a horizontal beam or a diagonal structure and dividing the bridge axis perpendicular direction by a main beam. For example, in FIG. 2, the panel PN is set by dividing the bridge axis direction by one diameter and dividing the direction perpendicular to the bridge axis by main digits.

  FIG. 3 is a partial plan view showing one panel PN. As shown in this figure, it is not unusual for the concrete floor slabs of road bridges that have been in service for a long time (especially RC slabs), and the cracks are gradually expanding. Not a few. If we can grasp the occurrence of this crack and the location (distribution) of the crack, we can take appropriate measures at the right time, and as a result we can prevent unexpected accidents and at the same time It is possible to extend the life.

  Hereinafter, the main flow of the process of the inspection apparatus of the present invention and the flow of the main steps of the inspection method will be described in more detail with reference to FIG. FIG. 4 is a flowchart showing the processing and flow, showing the processing and steps to be performed in the center column, the left column shows the input information necessary for the processing and steps, and the right column shows the processing and steps It shows the output information that is born.

  First, the image acquisition apparatus 101 is installed at a position where the underside of the floor slab can be seen (Step 10). The image acquisition unit 101 can acquire an image, and a digital camera can be given as a representative example. As shown in FIG. 5, the image acquisition unit 101 is fixedly installed on a support table such as a tripod 102. As will be described later, the image acquisition device 101 can be installed on a movable pan head mounted on a tripod 102. At this point, it is not necessary to acquire an image yet.

  When the image acquisition means 101 can be installed, the distance from the image acquisition means 101 to the floor slab lower surface (object) (hereinafter, this distance is referred to as “target distance”) is measured by the distance measurement means 103 (Step 20). Then, the posture of the image acquisition unit 101 (hereinafter referred to as “photographing posture”) is measured by the posture measurement unit 104 (Step 30). In FIG. 4, the shooting posture is measured after the target distance is measured. However, the present invention is not limited to this, and the target distance may be measured after the shooting posture is measured. The measurement of the shooting posture may be performed in parallel.

  The distance measuring means 103 for measuring the target distance can use various techniques conventionally used as long as it can measure the distance between two points, for example, using a laser measurement technique. Can do. Laser measurement is performed by receiving a reflection signal of laser light irradiated to an object to be measured, and can measure the distance between two points from the time difference between the irradiation time and the reception time. FIG. 5 shows the situation in which the target distance is measured by the laser measuring instrument (ranging means 103), and the arrows in the figure indicate the laser light emitted from the laser measuring instrument. At this time, the distance from the lens center of the image acquisition means 101 to the lower surface of the floor slab may be measured. Actually, as shown in FIG. 5, the distance from the lens center of the image acquisition means 101 to the bottom surface of the floor slab is approximately measured by laser light that has been translated by a small amount in the direction passing through the lens center (optical axis direction). To do.

  As the posture measuring means 104 for measuring the photographing posture, various techniques conventionally used can be used as long as the posture can be measured. Here, the posture is a direction in which the image acquisition unit 101 is facing and means an inclination with respect to an object (in this case, the bottom surface of the floor slab). For example, if the floor slab lower surface is a horizontal plane, the inclination with respect to the floor slab lower surface, that is, the photographing posture can be obtained by measuring the elevation angle (angle formed with the horizontal plane) and the vertical angle (angle formed with the vertical axis) of the image acquisition unit 101. it can. The posture measuring means 104 is typically an inclinometer, a geomagnetic sensor (electronic compass), or an acceleration sensor, but other techniques such as a gyro sensor or a combination of these techniques can be used. A terminal device incorporating a so-called 6-axis sensor that incorporates both an electronic compass and an acceleration sensor is also commercially available, and this terminal device may be used.

  Further, the posture measuring means 104 may be a laser measuring instrument, that is, the attitude of the image acquiring means 101 can be acquired by the laser measuring instrument. After clarifying the positional relationship between the laser measuring instrument and the image acquisition means 101 (including the tilt angle from the optical axis) and irradiating the bottom surface of the slab with laser light, the coordinates of the point reflected on the bottom surface of the slab can be acquired. . These coordinates are relative coordinates represented by this coordinate system when an arbitrary coordinate system consisting of three axes including the optical axis is set with the center of the image acquisition means 101 as the origin. Therefore, if the coordinates of three or more points of the floor slab lower surface are acquired by irradiating three or more points, the inclination of the lower surface of the floor slab with respect to the image acquisition means 101 is applied by applying a well-known plane calculation formula. That is, the photographing posture can be obtained. In this case, the laser measuring instrument may be equipped with three or more means for irradiating laser light (hereinafter referred to as “laser light irradiating means”), or one (or two) movable lasers. An irradiation means may be mounted. When the posture measuring means 104 is made of a laser measuring instrument, the positional relationship (including the distance) between the floor slab lower surface and the image acquiring means can be obtained from the plane equation, that is, the target distance can be obtained. Therefore, the distance measuring means 103 can be used instead. In other words, when the posture measuring means 104 is a laser measuring instrument equipped with three or more laser light emitting means or one (or two) movable laser light emitting means, a distance measuring means for measuring a target distance. 103 and posture measuring means 104 for measuring the photographing posture are provided at the same time.

  The target distance measured by the distance measuring unit 103 and the photographing posture measured by the posture measuring unit 104 are stored in the spatial information storage unit 105 as shown in FIG. FIG. 6 is a block diagram showing a main configuration of the inspection device 100 of the present invention.

  When the target distance and the shooting posture are obtained, the resolution of the image is estimated by the resolution estimating means 106 (FIG. 4: Step 40). However, it is not necessary to actually acquire an image at this time. In other words, the resolution is (to the last) estimated for an image that should be obtained if the image is taken with the target distance and the shooting posture obtained so far. Specifically, as shown in FIG. 6, the resolution estimation unit 106 that reads the target distance and the shooting posture from the spatial information storage unit 105 is based on the specifications (view angle, screen distance, etc.) of the image acquisition unit 101. Estimate the resolution of the image that should be acquired. When the target distance, the shooting posture, and the specifications of the image acquisition unit 101 are obtained, the range of the floor slab lower surface acquired by the image acquisition unit 101 (hereinafter referred to as “image range”) as shown by the broken line in FIG. It can be calculated. Since the number of pixels of the image acquisition unit 101 is known in advance, the resolution of the image can be estimated from the relationship between the number of pixels and the image range.

  When the resolution of the acquired image is estimated, it is determined whether the image acquisition may actually be performed (FIG. 4: Step 50). As shown in FIG. 6, the image acquisition determination unit 107 reads a predetermined resolution threshold value (hereinafter referred to as “resolution threshold value”) from the resolution threshold storage unit 108, and compares the estimated resolution with the resolution threshold value. The right or wrong of image acquisition is determined. Specifically, when the estimated resolution exceeds the resolution threshold, image acquisition is affirmed, and when the estimated resolution is below the resolution threshold, image acquisition is denied. As can be seen from FIG. 5, there are cases where the resolution in one image is not uniform. In this case, the lowest value of the estimated resolutions may be compared with the resolution threshold value, or a statistically processed value such as an average value or a median value may be compared with the resolution threshold value. The result (image acquisition affirmation / negative) determined by the image acquisition determination unit 107 can be output to the output unit 109 such as a display or an audio output device.

  When the image acquisition determination unit 107 affirms image acquisition, the image acquisition unit 101 actually acquires an image (FIG. 4: Step 60). The image acquired here is stored in the image storage unit 110. At this time, a person may operate the image acquisition unit 101 to acquire an image, or automatic shooting may be performed according to the result of the image acquisition determination unit 107. Specifically, when the image acquisition determination unit 107 affirms image acquisition, a photographing control unit (not shown) that has received the information sends a signal to the image acquisition unit 101, and the image acquisition unit 101 that has received this signal. Automatically get images. Therefore, in this case, the image acquisition determination unit 107, the imaging control unit, and the image acquisition unit 101 each have a unit capable of transmitting and receiving information and signals, and each is connected by a wireless or wired communication unit. Has been. Note that the resolution estimation unit 106, the image acquisition determination unit 107, and the imaging control unit may be executed by the computer 111 illustrated in FIG.

  On the other hand, when the image acquisition determination unit 107 denies image acquisition, the image acquisition unit 101 in the installation state (position and posture) does not acquire an image, but adjusts the installation position and installation posture of the image acquisition unit 101 ( FIG. 4: Step 70). Then, the target distance is measured again (Step 20), the shooting posture is measured (Step 30), the resolution of the acquired image is estimated (Step 40), and the image acquisition determining unit 107 determines whether to acquire the image (Step 50). ).

  The adjustment operation of the image acquisition unit 101 performed when the image acquisition determination unit 107 denies image acquisition can be manually performed by a person, or can be automatically adjusted. In this case, the calculation unit 112 shown in FIG. 6 calculates an appropriate installation position and installation posture of the image acquisition unit 101, and the adjustment control unit 113 is added to the movable pan head 114 based on the appropriate installation position and installation posture. Send a command to move. Specifically, the calculation unit 112 that has received information that the image acquisition determination unit 107 has denied image acquisition is based on information such as the current target distance and shooting posture, the estimated resolution, and the resolution threshold. , Can obtain an image with a resolution that exceeds the resolution threshold), calculates the target distance and shooting posture, calculates the appropriate installation position and installation posture, and further, the moving amount and moving direction from the current state to the appropriate installation position, The moving inclination angle from the current state to the proper installation posture is calculated. The adjustment control means 113 having received this information indicates that adjustment should be made together with adjustment amounts (movement amount and movement direction, movement inclination angle) for achieving an appropriate installation position and installation posture with respect to the movable head 114. A command is sent, and in response to this, the pan head 114 moves and tilts. Therefore, the pan head 114 fixes the image acquisition unit 101 on the tripod 102, and can be moved with the image acquisition unit 101 fixed by using electric power or the like as a motive power. The posture can be changed (tilted) while being fixed. In this case, the image acquisition determination means 107, the calculation means 112, the adjustment control means 113, and the pan head 114 each have means capable of transmitting and receiving information and signals, and each of them is wireless or wired. It is connected by communication means. Note that the calculation means 112, the adjustment control means 113, and the pan head 114 may be executed by the computer 111 shown in FIG.

  When the image can be acquired, cracks are extracted from the image (FIG. 4: Step 80). FIG. 7 is an image diagram showing cracks extracted from the image PH. At this time, a crack may be extracted by a person visually reading the image, or the crack may be automatically extracted by the crack extracting means 115 shown in FIG. Specifically, the crack extraction means 115 that has read out the image from the image storage means 110 extracts the crack by automatically recognizing the image. This image recognition can be performed using a known technique such as a method of automatically discriminating based on a difference in luminance or color (hue, saturation, and brightness) on an image. For example, if a pixel that approximates (or matches) a preset brightness or color for a crack is detected from an image, and the detected pixels continue beyond a predetermined number (greater than a threshold value), Extract as a crack.

  Usually, when an image is acquired with a considerably high resolution, the image range becomes limited. For this reason, it is difficult to fit one panel PN into one image as in the image range indicated by the broken line in FIG. 3, and the entire panel PN is captured with a plurality of images. Therefore, a plurality of images covering the entire panel PN are acquired, and cracks are extracted from all these images, so that the panel PN is inspected, and for all the panels PN constituting the bridge deck. The inspection of the bridge deck is completed by repeating a series of processes (steps).

  The inspection device and the inspection method of the present invention can be used for bridges for various purposes such as road bridges, railway bridges, pipeline bridges, and can be used for various construction infrastructures besides bridges. According to the invention of the present application, it is possible to grasp the deterioration status of the construction infrastructure in service, and repair and reinforcement measures according to the deterioration status are possible. It can be said that the invention can be expected to make a great contribution not only to society.

DESCRIPTION OF SYMBOLS 100 Inspection apparatus of this invention 101 Image acquisition means 102 Tripod 103 Distance measurement means 104 Attitude measurement means 105 Spatial information storage means 106 Resolution estimation means 107 Image acquisition determination means 108 Resolution threshold value storage means 109 Output means 110 Image storage means 111 Computer 112 Calculation Means 113 Adjustment control means 114 Pan head 115 Crack extraction means PH Image PN panel

Claims (6)

In a device that inspects objects using images,
Image acquisition means for acquiring an image of the object;
Ranging means for measuring the distance from the image acquisition means to the object;
Attitude measuring means for measuring the attitude of the image acquisition means;
Resolution estimation means for estimating the resolution of the acquired image based on the distance from the image acquisition means to the object and the attitude of the image acquisition means;
An image acquisition determination unit that affirms image acquisition when the resolution estimated by the resolution estimation unit exceeds a predetermined resolution threshold, and denies image acquisition when the resolution is lower than the resolution threshold;
A device for inspecting an object, comprising: From the image acquired by the image acquisition means, crack extraction means for extracting cracks of the object,
The inspection apparatus for an object according to claim 1, further comprising: The distance measuring means and the posture measuring means are laser measuring instruments,
The laser measuring instrument comprises three or more laser light irradiation means for irradiating laser light whose positional relationship with the image acquisition means is known, or laser light whose positional relationship with the image acquisition means is known. Equipped with movable laser light irradiation means to irradiate,
The inspection apparatus for an object according to claim 1 or 2, characterized in that When the image acquisition determination unit affirms image acquisition, the image acquisition unit is instructed to acquire an image,
The image acquisition means acquires an image of the object according to a command of the image acquisition determination means;
The inspection apparatus for an object according to any one of claims 1 to 3, wherein: The image acquisition means is fixed, the image acquisition means can be moved, and the pan head that can change the posture;
When the image acquisition determination unit denies acquisition of the image, the resolution threshold is set based on the distance from the image acquisition unit to the object, the attitude of the image acquisition unit, and the estimated resolution of the image. Computing means for calculating the position and orientation of the image obtaining means capable of obtaining an image that exceeds,
Control means for controlling the camera platform so that the image acquisition means has the position and orientation calculated by the calculation means;
The object inspection device according to claim 1, further comprising: In a method for acquiring an image of an object by an image acquisition means and inspecting the object,
A distance measuring step of measuring a distance from the image acquisition means to the object;
An attitude measurement step for measuring the attitude of the image acquisition means;
A resolution estimation step of estimating the resolution of the acquired image based on the distance from the image acquisition means to the object and the attitude of the image acquisition means;
An image acquisition determination step of affirming image acquisition when the resolution of the image estimated in the resolution estimation step exceeds a predetermined resolution threshold, and denying image acquisition when lower than the resolution threshold;
An image acquisition step of acquiring an image of the object when image acquisition is affirmed in the determination step;
An inspection method for an object, wherein the object is inspected based on the image acquired in the image acquisition step.

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