Long object shape measurement system and shape measurement method

Abstract

To provide a long object shape measurement system and shape measurement method which can facilitate the prior calibration of the relative position and correctly measure the shape of a long object.SOLUTION: A shape measurement system 1 comprises: an irradiation unit 10 which has a plurality of multi-line light sources 10A; an imaging unit 20 which images the object surface of a long object including a line marker drawn by the irradiation unit 10 in the oblique direction from the end side in the longitudinal direction of the long object; and a processing unit 100 which acquires a distance from the irradiation unit 10 to the object surface of the long object and calculates a curve indicating the shape of the edge or contour of the long object on the basis of the position of each line marker in the image captured by the imaging unit 20 and the acquired distance from the irradiation unit 10 to the object surface of the long object.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a shape measurement system and a shape measurement method for long objects.

Background Art

[0002] In order to ensure the quality of steel materials shipped from steel mills, shape measurement of steel materials is performed after rolling. The shape measurement of steel materials is automatically performed by a shape measurement device installed on the production line. For example, Patent Document 1 discloses a shape measurement device including four or more laser light sources that irradiate a steel plate with laser light, a camera that photographs the irradiation range of the laser light from each laser light source, and a computer that extracts a plurality of edges at the side end portion of the steel plate from the image photographed by the camera and calculates the amount of bending of the steel plate based on the extracted edges.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the shape measurement device of Patent Document 1, four or more laser light sources that irradiate each laser light perpendicularly to the target surface of the steel material are required. For this reason, there is a problem that a lot of time and labor are required for calibration of the relative positions of the respective laser light sources with respect to the camera. And such a problem exists not only when measuring the shape of steel materials but also when measuring the shapes of other long objects.

[0005] The present invention has been made based on such a background, and an object thereof is to provide a shape measurement system and a shape measurement method for long objects that are easy to calibrate the relative positions in advance and can accurately measure the shape of long objects.

Means for Solving the Problems

[0006] To achieve the above object, a shape measurement system according to a first aspect of the present invention includes an irradiation unit including a plurality of multi-line light sources, wherein the multi-line light sources emit a plurality of linear beams in directions away from each other, and are arranged side by side in the longitudinal direction of the long object, and an edge extending in the longitudinal direction of the long object Ji and an irradiation unit that draws a plurality of intersecting line markers on the target surface of the long object; a photographing unit that photographs the target surface of the long object including the line markers drawn by the irradiation unit obliquely from the end side in the longitudinal direction of the long object; obtains the distance from the irradiation unit to the target surface of the long object, and based on the position of each line marker in the image photographed by the photographing unit and the obtained distance from the irradiation unit to the the aforesaid target surface of the long object, a processing unit that calculates a curve indicating the shape of the long object Ji-shaped is obtained. is provided with the processing unit includes an intersection extraction unit that extracts intersections between each line marker and the edge of the long object in the image captured by the imaging unit; a coordinate conversion unit that converts the coordinates of each intersection extracted by the intersection extraction unit based on the distance from the irradiation unit to the target surface of the long object, such that the image captured by the imaging unit is an image that vertically captures the target surface of the long object from above; a shape calculation unit that calculates a curve indicating the edge shape of the long object based on a point group composed of intersections whose coordinates have been converted by the coordinate conversion unit. is obtained.

[0007] To achieve the above object, a shape measurement system according to a second aspect of the present invention is an irradiation unit including a plurality of multi-line light sources, wherein the multi-line light sources emit a plurality of line-shaped beams in directions away from each other, and are arranged side by side in the longitudinal direction of the long object, and draw a plurality of line markers intersecting the edge extending in the longitudinal direction of the long object on the target surface of the long object; an imaging unit that obliquely captures the target surface of the long object including the line markers drawn by the irradiation unit from the end side in the longitudinal direction of the long object; a processing unit that acquires the distance from the irradiation unit to the target surface of the long object, and calculates a curve indicating the edge shape of the long object based on the positions of each line marker in the image captured by the imaging unit and the acquired distance from the irradiation unit to the target surface of the long object. The processing unit includes an intersection extraction unit that extracts intersections between each line marker and the edge of the long object in the image captured by the imaging unit; a coordinate conversion unit that converts the coordinates of each intersection extracted by the intersection extraction unit such that the image captured by the imaging unit is an image that vertically captures the target surface of the long object from above; a shape calculation unit that calculates a curve indicating the edge shape of the long object based on a point group composed of intersections whose coordinates have been converted by the coordinate conversion unit. The coordinate conversion unit selects a conversion table corresponding to the distance stored in the storage unit based on the distance between the irradiation unit and the target surface of the long object; refers to the selected conversion table and converts the coordinates of each intersection extracted by the intersection extraction unit such that the image captured by the imaging unit is an image that vertically captures the target surface of the long object from above.

[0008] In order to achieve the above object, a shape measurement system according to a third aspect of the present invention includes: an irradiation unit including a plurality of multi-line light sources, wherein the multi-line light sources are arranged side by side in the longitudinal direction of a long object by emitting a plurality of linear beams in directions away from each other, and draw a plurality of line markers intersecting a contour extending in the longitudinal direction of the long object on a target surface of the long object; a photographing unit that photographs the target surface of the long object including the line markers drawn by the irradiation unit obliquely from an end side in the longitudinal direction of the long object; a processing unit that acquires the distance from the irradiation unit to the target surface of the long object, and calculates a curve indicating the contour shape of the long object based on the positions of the respective line markers in the image photographed by the photographing unit and the acquired distance from the irradiation unit to the target surface of the long object; the processing unit includes: a line marker extraction unit that extracts a plurality of points constituting each line marker in the image photographed by the photographing unit; a coordinate conversion unit that converts the coordinates of each point extracted by the line marker extraction unit based on the acquired distance from the irradiation unit to the target surface of the long object so that the image photographed by the photographing unit is an image obtained by vertically photographing the target surface of the long object from above; a shape calculation unit that calculates a curve indicating the contour shape of the long object based on a point group composed of points whose coordinates are converted by the coordinate conversion unit.

[0009] The coordinate conversion unit may convert the coordinates of each point of the line marker extracted by the line marker extraction unit by applying triangulation to a first point where the multi-line light source is arranged, a second point where the photographing unit is arranged, and a third point on the line marker drawn by the multi-line light source.

[0010] The processing unit may calculate the distance from the irradiation unit to the target surface of the long object based on the interval between the line markers drawn by the same multi-line light source in the image photographed by the photographing unit.

[0011] The shape measurement system may further include a moving mechanism that movably supports the irradiation unit in the width direction of the long object.

[0012] The irradiation unit may be provided in association with the multi-line light source, the relative position to the multi-line light source is calibrated, and may further include a calibration camera that photographs different portions of the long object.

[0013] The irradiation unit includes at least three or more of the calibration cameras. The processing unit may calculate a curve indicating the edge shape of the long object based on at least three images showing different portions of the long object simultaneously captured by each calibration camera.

[0014] To achieve the above object, a shape measurement method according to a fourth aspect of the present invention is a shape measurement method executed by a shape measurement system, a step of drawing a plurality of line markers intersecting an edge extending in the longitudinal direction of the long object on the target surface of the long object by the multi-line light source of the irradiation unit emitting a plurality of line-shaped beams in directions away from each other and arranging them side by side in the longitudinal direction of the long object; a step of the imaging unit photographing the target surface of the long object including the line markers drawn by the multi-line light source obliquely from the end side in the longitudinal direction of the long object; a step of the processing unit extracting intersections between each line marker and the edge of the long object in the image photographed by the imaging unit; a step of the processing unit obtaining the distance from the irradiation unit to the target surface of the long object and converting the coordinates of each extracted intersection based on the obtained distance from the irradiation unit to the target surface of the long object so that the image photographed by the imaging unit is an image photographing the target surface of the long object vertically from above; a step of the processing unit calculating a curve indicating the edge shape of the long object based on a point group composed of intersections whose coordinates have been converted; and includes.

[0015] To achieve the above object, the shape measurement method according to the 5 viewpoint of the present invention is a shape measurement method executed by a shape measurement system, wherein a multi-line light source of an irradiation unit emits a plurality of linear beams in directions away from each other, and a plurality of line markers arranged side by side in the longitudinal direction of the long object and intersecting the contour are drawn on the target surface of the long object; ring a step of drawing a plurality of line markers that intersect the contour on the target surface of the long object by emitting a plurality of linear beams in directions away from each other, arranged side by side in the longitudinal direction of the long object and extending in the longitudinal direction of the long object; The step of the imaging unit photographing a target surface of a long object including a line marker drawn by the multi-line light source from an end side in the longitudinal direction of the long object in an oblique direction; a step of the processing unit extracting a plurality of points constituting each line marker in the image photographed by the imaging unit; a step of the processing unit obtaining the distance from the irradiation unit to the target surface of the long object and converting the coordinates of each extracted point based on the obtained distance from the irradiation unit to the target surface of the long object so that the image photographed by the imaging unit is an image photographing the target surface of the long object vertically from above; a step of the processing unit calculating a curve indicating the contour shape of the long object based on a point group composed of points whose coordinates have been converted; including.

Effect of the Invention

[0016] According to the present invention, it is possible to provide a shape measurement system and a shape measurement method for a long object that are easy to calibrate the relative position in advance and can accurately measure the shape of the long object.

Brief Description of the Drawings

[0017]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

Figure 15

Embodiments for Carrying Out the Invention

[0018] Hereinafter, the shape measurement system and the shape measurement method according to the embodiments of the present invention will be described in detail with reference to the drawings. In each drawing, the same or equivalent parts are denoted by the same reference numerals. In each embodiment, the case of measuring the shape of a steel material as a long object will be described as an example, but the long object is not limited to a steel material and includes members of any shape extending in a certain direction.

[0019] (Embodiment 1) Referring to FIGS. 1 to 8, a shape measurement system and a shape measurement method according to Embodiment 1 will be described. FIG. 1 is a front view showing the configuration of a shape measurement system 1 according to Embodiment 1. The shape measurement system 1 according to Embodiment 1 is a system that measures the shape of an edge extending in the longitudinal direction of a steel material based on an image obtained by photographing the target surface of the steel material obliquely from the end side in the longitudinal direction of the steel material. The target surface of the steel material is the surface irradiated with the laser beam, and the edge is the edge where the target surface of the steel material intersects with another surface.

[0020] The shape measurement system 1 includes an irradiation unit 10 that irradiates a plurality of laser beams onto the target surface of the steel material to draw a plurality of line markers intersecting the edge on the target surface, a photographing unit 20 that photographs the target surface on which the plurality of line markers are drawn by the irradiation unit 10, and a processing unit 100 that calculates a curve indicating the edge shape of the steel material based on the image photographed by the photographing unit 20. The line marker is drawn on the target surface of the steel material during the irradiation of the laser beam and disappears when the irradiation of the laser beam stops. Hereinafter, a rectangular coordinate system (world coordinate system) is used in which the direction in which the irradiation unit 10 and the photographing unit 20 are arranged side by side is the Y-axis direction, the direction extending on the horizontal plane and perpendicular to the Y-axis is the X-axis direction, and the direction orthogonal to the X-axis direction and the Y-axis direction (vertical direction) is the Z-axis direction. Also, the side of the steel material on the photographing unit 20 side is referred to as the base end side, and the opposite side is referred to as the tip end side.

[0021] The irradiation unit 10 is installed above the steel material and draws linear markers arranged in parallel to each other in the longitudinal direction of the steel material on the target surface of the steel material by scanning the laser beam toward the target surface of the steel material. The irradiation unit 10 is supported, for example, by a moving mechanism (not shown) that can move the irradiation unit 10 in the X-axis direction (width direction of the steel material). Since the imaging range of the photographing unit 20 can be adjusted in the X-axis direction by the moving mechanism, the edge of the steel material can be arranged at the center of the photographed image.

[0022] The irradiation unit 10 includes a plurality of multi-line light sources 10A and a housing 10B that supports each multi-line light source 10A while accommodating it inside. The multi-line light source 10A includes a laser light source that repeatedly scans a laser beam in the X-axis direction, and a beam splitting element that splits the laser beam from the laser light source into two. As the laser light source, in order to suppress the measurement error of the edge shape caused by laser speckle, it is preferable to use a high-frequency superimposed laser light source and perform smoothing in the scanning direction of the laser beam.

[0023] Figs. 2(a) and (b) are a front view and a plan view showing the trajectories of the laser beams emitted by the multi-line light source 10A according to the first embodiment, respectively. The beam splitting element of the multi-line light source 10A splits the laser beam from the laser light source so that the two laser beams are symmetric with respect to a vertical plane in which the two laser beams extend perpendicular to the target surface of the steel material, in other words, so that they have the same inclination angle θ with respect to the vertical plane. The multi-line light source 10A emits two laser beams in directions away from each other, thereby drawing two line markers on the target surface of the steel material. Note that the relative positions of the multi-line light sources 10A with respect to the imaging unit 20 are calibrated in advance.

[0024] Returning to Fig. 1, the imaging unit 20 is installed on the end side in the longitudinal direction of the steel material arranged at the measurement position, and as shown in the camera field of view of Fig. 1, it captures the entire target surface of the steel material from the end in the longitudinal direction of the steel material and transmits the obtained image data to the processing unit 100. The imaging unit 20 includes, for example, a camera 21 and a lens 22 that is arranged on the tip side of the camera 21 and makes the image of the target surface incident on the camera 21. In the imaging unit 20, in order to increase the depth of field and focus on the entire target surface of the steel material, tilt imaging may be performed by tilting the optical axis of the lens 22 with respect to the photosensitive surface of the imaging element of the camera 21.

[0025] The processing unit 100 calculates the distance between the irradiation unit 10 and the target surface of the long object based on the intervals between the line markers drawn by the same multi-line light source 10A in the image captured by the imaging unit 20, and calculates a curve indicating the edge shape of the long object based on the positions of the respective line markers in the image captured by the imaging unit 20 and the calculated distance from the irradiation unit 10 to the target surface of the long object.

[0026] The processing unit 100 is, for example, a general-purpose computer. The processing unit 100 is communicably connected to the irradiation unit 10 and the imaging unit 20, respectively. The processing unit 100 supplies control signals to the irradiation unit 10 and the imaging unit 20 and acquires image data from the imaging unit 20.

[0027] FIG. 3 is a block diagram showing the hardware configuration of the processing unit 100 according to the embodiment. The processing unit 100 includes an operation unit 110, a display unit 120, a communication unit 130, and a storage unit 140. Each unit of the processing unit 100 is communicably connected to each other via an internal bus (not shown).

[0028] The operation unit 110 receives a user's instruction and supplies an operation signal corresponding to the received operation to the control unit 150. The operation unit 110 includes, for example, a keyboard and a mouse. The operation unit 110 receives, for example, a user's instruction regarding the start of measurement of the edge shape of the steel material.

[0029] The display unit 120 displays various images for the user who operates the processing unit 100 based on the image data supplied from the control unit 150. The display unit 120 displays, for example, a captured image by the imaging unit 20 and an image indicating the edge shape of the steel material.

[0030] The communication unit 130 is, for example, an interface capable of connecting to a communication network such as an Internet line.

[0031] The storage unit 140 includes, for example, a RAM (Random Access Memory), a ROM (Read Only Memory), a flash memory, and a hard disk drive. The storage unit 140 stores programs and various data to be executed by the control unit 150, and functions as a work memory for the control unit 150 to execute processing. Further, the storage unit 140 includes an image data storage unit 141 and a conversion table storage unit 142.

[0032] FIG. 4(a) shows an example of a data table stored in the image data storage unit 141 according to the embodiment. The image data storage unit 141 stores the image data obtained by the imaging unit 20 in association with a management ID (Identification) individually assigned to each steel material to be measured.

[0033] FIG. 4(b) shows an example of a conversion table stored in the conversion table storage unit 142 according to the embodiment. The conversion table storage unit 142 stores a conversion table showing the correspondence between the X'Y' coordinates (local coordinates) of an image obtained by photographing the target surface of the steel material obliquely from the base end side of the steel material and the XY coordinates (world coordinates) of an image obtained by photographing the target surface of the steel material vertically from above. As shown in FIGS. 5(a) and 5(b), the local coordinates are an orthogonal coordinate system in which the left-right direction of an image obtained by photographing the target surface of the steel material obliquely from the base end side of the steel material is the X' axis direction, and the up-down direction of the image is the Y' axis direction. The conversion table is created for each distance from the irradiation unit 10 to the target surface of the steel material. This is because the position of the line marker on the target surface of the steel material changes depending on the distance from the irradiation unit 10 to the target surface of the steel material.

[0034] Returning to FIG. 3, the control unit 150 includes, for example, a CPU (Central Processing Unit) and controls each part of the processing unit 100. The control unit 150 executes the shape measurement process of FIG. 7 and the coordinate conversion process of FIG. 8 by executing the program stored in the storage unit 140. Functionally, the control unit 150 includes an acquisition unit 151, an intersection extraction unit 152, a coordinate conversion unit 153, a shape calculation unit 154, a straightness calculation unit 155, and an output unit 156.

[0035] The acquisition unit 151 acquires the image data captured by the imaging unit 20 and stores it in the image data storage unit 141 in association with the management ID. The image acquired by the acquisition unit 151 is an image obtained by photographing the target surface of the steel material from diagonally above the base end side of the steel material, as shown in FIG. 5(a).

[0036] As shown in FIG. 5(b), the intersection extraction unit 152 extracts the intersections of each line marker and the edge in the image captured by the imaging unit 20.

[0037] The coordinate conversion unit 153 converts the X'Y' coordinates of the intersections of each line marker and the edge in the local coordinate system, which are extracted by the intersection extraction unit 152, into the XY coordinates of the world coordinate system. For the coordinate conversion, projective transformation may be performed so that the coordinates of the image obtained by photographing the target surface of the steel material from diagonally above, as shown in FIG. 5(b), become the coordinates of the image obtained by vertically photographing the target surface of the steel material from above, as shown in FIG. 5(c).

[0038] Specifically, first, the distance from the irradiation unit 10 to the target surface of the steel material is calculated. The distance from the irradiation unit 10 to the target surface of the steel material may be calculated based on the interval between two line markers drawn by the same multi-line light source 10A, for example, the multi-line light source 10A at the most proximal side, and the inclination angle of each laser beam emitted from the multi-line light source 10A. The interval between the two line markers drawn by the multi-line light source 10A can be read from the image captured by the imaging unit 20. For example, a data table showing the correspondence between the interval between the two line markers in the captured image and the actual interval between the two line markers is stored in the storage unit 140 in advance, and the interval between the two line markers read from the captured image is converted into the actual interval between the two line markers by referring to the data table. Next, based on the distance from the irradiation unit 10 to the target surface of the steel material, the conversion table stored in the conversion table storage unit 142 in FIG. 4(b) is selected, and the coordinates of the intersection points between each line marker and the edge extracted by the intersection point extraction unit 152 are converted based on the selected conversion table.

[0039] Based on the point group composed of the intersection points between each line marker and the edge whose coordinates have been converted by the coordinate conversion unit 153, the shape calculation unit 154 calculates a curve indicating the edge shape of the steel material. The edge shape is represented by, for example, an approximate curve generated based on all the intersection points between each line marker and the edge, such as an approximate quadratic curve, as shown in FIG. 5(d). In FIG. 5(d), for easy understanding, the scale in the X-axis direction is exaggerated compared to FIG. 5(c).

[0040] Based on the curve indicating the edge shape of the steel material calculated by the shape calculation unit 154, the straightness calculation unit 155 calculates the straightness at the edge of the steel material. The straightness is an index indicating the magnitude of the deviation from the geometrically correct straight line of a linear object. The straightness calculation unit 155 may calculate, for example, as shown in FIG. 6, the difference d between the maximum value and the minimum value of the X coordinate values in the edge shape of the steel material as the straightness.

[0041] The output unit 156 outputs data regarding the edge shape calculated by the shape calculation unit 154 and data regarding the straightness calculated by the straightness calculation unit 155. The output unit 156 creates, for example, a display image based on the calculated edge shape and straightness, and causes the display unit 120 to display it. Further, the output unit 156 supplies a control signal for controlling the operations of the irradiation unit 10 and the imaging unit 20 to each of the irradiation unit 10 and the imaging unit 20 based on the instruction of the user received by the operation unit 110. The above is the configuration of the processing unit 100 according to the first embodiment.

[0042] (Shape measurement process) Next, with reference to the flowchart of FIG. 7, the shape measurement process executed by the processing unit 100 according to the embodiment will be described. The shape measurement process is a process of measuring the shape of an edge extending in the longitudinal direction of a steel material based on an image obtained by photographing the target surface of the steel material obliquely from the end side in the longitudinal direction of the steel material. The shape measurement process is started when the operation unit 110 of the processing unit 100 receives an instruction from the user. Hereinafter, it is assumed that a plurality of line markers have already been drawn on the target surface of the steel material by the irradiation unit 10.

[0043] First, the acquisition unit 151 acquires the image data photographed by the imaging unit 20 and stores it in the image data storage unit 141 of FIG. 4(a) in association with the management ID (step S1). Specifically, the control unit 150 of the processing unit 100 transmits a control signal to the imaging unit 20 to cause it to photograph the entire target surface of the steel material including the line markers, and acquires the image data obtained by the imaging of the imaging unit 20. Then, a photographed image as shown in FIG. 5(a) is obtained.

[0044] Next, the intersection extraction unit 152 extracts the intersections of each line marker and the edge in the photographed image of the steel material obtained by the process of step S1, and acquires the coordinates of each intersection (step S2).

[0045] Next, the coordinate conversion unit 153 executes a coordinate conversion process for converting the coordinates of each intersection point extracted in the process of step S2 (step S3). Hereinafter, with reference to the flowchart of FIG. 8, the flow of the coordinate conversion process executed by the processing unit 100 according to the first embodiment will be described.

[0046] (Coordinate Conversion Process) First, the coordinate conversion unit 153 obtains the distance between two line markers drawn by the multi-line light source 10A at the most proximal end from the captured image of the steel material obtained by the process of step S1, and based on the obtained distance between the two line markers and the inclination angle of each laser beam emitted from the multi-line light source 10A, calculates the distance from the irradiation unit 10 to the target surface of the steel material (step S31). The distance between the two line markers drawn by the multi-line light source 10A at the most proximal end is obtained by converting the distance between the two line markers read from the captured image into the actual distance between the two line markers using the conversion table stored in the storage unit 140.

[0047] Next, the coordinate conversion unit 153 selects a conversion table corresponding to the distance from a plurality of conversion tables stored in the conversion table storage unit 142 of FIG. 4(b) based on the distance from the irradiation unit 10 to the target surface of the steel material calculated in the process of step S31 (step S32).

[0048] Next, the coordinate conversion unit 153 performs a projective conversion on the coordinates of each intersection point extracted in the process of step S2 using the conversion table selected in the process of step S32 (step S33), and returns the process. By the process of step S33, as shown in FIG. 5(b), the coordinates of each intersection point in the image obtained by photographing the target surface of the steel material obliquely can be converted into the coordinates of each intersection point in the image obtained by photographing the target surface of the steel material directly from above as shown in FIG. 5(c). The above is the flow of the coordinate conversion process according to the first embodiment.

[0049] Returning to FIG. 7, the shape calculation unit 154 calculates a curve indicating the edge shape of the steel material based on the point group composed of the intersections between each line marker whose coordinates have been transformed by the coordinate transformation unit 153 and the edge (step S4).

[0050] Next, the straightness calculation unit 155 calculates the straightness of the steel material to be measured based on the curve indicating the edge shape calculated by the shape calculation unit 154 (step S5).

[0051] Next, the output unit 156 generates an image including the curve indicating the edge shape calculated in the process of step S4 and the straightness calculated in the process of step S5, and causes the display unit 120 to display the image (step S6), and ends the process. The above is the flow of the shape measurement process according to Embodiment 1.

[0052] As described above, the shape measurement system 1 according to Embodiment 1 includes an irradiation unit 10 including a plurality of multi-line light sources 10A, an imaging unit 20 that captures an object surface of a long object including line markers drawn by the irradiation unit 10 obliquely from an end side in the longitudinal direction of the long object, a distance acquisition unit that acquires the distance from the irradiation unit 10 to the object surface of the long object, and a processing unit 100 that calculates a curve indicating the edge shape of the long object based on the positions of each line marker in the image captured by the imaging unit 20 and the acquired distance from the irradiation unit 10 to the object surface of the long object. Since the multi-line light source 10A is used as the laser light source, the number of laser light sources can be reduced compared with a laser light source that emits a single laser beam. As a result, the time and labor required for calibrating the relative positions of the laser light sources can be reduced.

[0053] Further, the shape measurement system 1 according to Embodiment 1 extracts the intersections between each line marker and the edge of the steel material in the image captured by the imaging unit 20, and calculates a curve indicating the edge shape of the steel material based on the point group composed of the plurality of extracted intersections. Therefore, the edge shape extending in the longitudinal direction of the steel material can be accurately measured.

[0054] (Embodiment 2) With reference to FIGS. 9 to 14, the shape measurement system 1 and the shape measurement method according to Embodiment 2 will be described. In Embodiment 1, a curve indicating the edge shape of the steel material was calculated, whereas in Embodiment 2, a curve indicating the contour shape extending in the longitudinal direction of the steel material is calculated. The contour shape is not limited to the edge of the object, but includes contours formed by curved surfaces and unevenness. Hereinafter, the description will focus on the differences between the two.

[0055] FIG. 9 is a front view showing the configuration of the shape measurement system 1 according to Embodiment 2. The irradiation unit 10 is supported by the housing 10B and further includes a calibration camera 10C provided corresponding to a part of each multi-line light source 10A. The relative position of the calibration camera 10C with respect to the multi-line light source 10A is calibrated in advance by a known method. Also, the relative position of the calibration camera 10C with respect to the imaging unit 20 is calibrated. Specifically, a known object is placed near the steel material to be measured, and the same known object is imaged by the imaging unit 20 and the calibration camera 10C, and the relative position of the calibration camera 10C with respect to the imaging unit 20 is calibrated by solving the PNP (Perspective-n-Point) problem. When a plurality of calibration cameras 10C are installed in the irradiation unit 10, the above calibration operation is sequentially repeated for each calibration camera 10C. Thereby, the coordinate system of the imaging unit 20 and the coordinate system of each multi-line light source 10A are made to coincide. Here, it is assumed that the internal parameters of the imaging unit 20 and the calibration camera 10C, for example, the lens focal length, the optical center, and the shear coefficient, are pre-calibrated.

[0056] FIG. 10 is a diagram showing the hardware configuration of the processing unit 100 according to Embodiment 2. Functionally, the control unit 150 of the processing unit 100 includes an acquisition unit 151, a line marker extraction unit 152A, a coordinate conversion unit 153, a shape calculation unit 154, a straightness calculation unit 155, and an output unit 156.

[0057] The line marker extraction unit 152A extracts the images of the respective line markers drawn on the target surface of the steel material by the irradiation unit 10 from the image acquired by the acquisition unit 151. The image acquired by the acquisition unit 151 is, for example, an image of the target surface of the steel material taken obliquely from above as shown in FIG. 11(a), and the images of the respective line markers are extracted from this image as shown in FIG. 11(b). The points constituting each line marker are, for example, those obtained by extracting pixels whose pixel values in the image are equal to or greater than a threshold value. In FIG. 11(b), for ease of understanding, the line markers are represented by continuous lines, but in reality, they are represented by a plurality of pixels in the image.

[0058] The coordinate conversion unit 153 converts the coordinates of the plurality of points constituting each line marker, which is extracted by the line marker extraction unit 152A and is in the local coordinate system, into the coordinates in the world coordinate system. The coordinate conversion unit 153 performs triangulation so that the coordinates of the image of the target surface of the steel material taken obliquely from above as shown in FIG. 11(b) become the coordinates of the image of the target surface of the steel material taken vertically from above as shown in FIG. 11(c). In FIG. 11(c), for ease of understanding, the illustration of the steel material is omitted.

[0059] As shown in FIG. 12, the coordinate conversion unit 153 applies the triangulation method to the first point (point A) where the multi-line light source 10A is arranged, the second point (point B) where the lens 22 is arranged, and the third point (point C) on the line marker. In triangulation, the line AB connecting the two points A and B is used as the baseline. Hereinafter, the procedure for calculating the coordinate value of point C using the triangulation method is as follows. First, the interior angles A, B, and C are calculated respectively based on the captured image of the target surface of the steel material acquired by the camera 21. Next, based on the baseline length and the interior angles A, B, and C, the distance from point A to the target surface of the steel material is calculated. Next, based on the coordinate value of point A and the distance from point A to the target surface of the steel material, the coordinate value of point C is calculated. It is assumed that the baseline length, which is the length of the line AB, has been calculated from the coordinate values of points A and B during pre-calibration.

[0060] Based on the point cloud composed of a plurality of points that make up each line marker whose coordinates have been transformed by the coordinate transformation unit 153, the shape calculation unit 154 calculates a curve indicating the contour shape of a desired portion of the steel material as shown in FIG. 11(d). Specifically, an approximate curve is set based on the point cloud composed of a plurality of points that make up each line marker, a plurality of points within a certain range of the curvature of the approximate curve are extracted, and an approximate curve is set based on the extracted plurality of points, thereby calculating a curve indicating the contour shape of a desired portion of the steel material.

[0061] Based on the curve indicating the contour shape of a desired portion of the steel material calculated by the shape calculation unit 154, the straightness calculation unit 155 calculates the straightness at the desired portion of the steel material. The above is the configuration of the processing unit 100 according to the second embodiment.

[0062] (Shape measurement process) With reference to the flowchart of FIG. 13, the flow of the shape measurement process executed by the processing unit 100 according to the second embodiment will be described. After the execution of the image acquisition process in step S1 by the acquisition unit 151, the line marker extraction unit 152A extracts a point cloud composed of a plurality of points that make up each line marker drawn on the target surface of the steel material by the irradiation unit 10 from the image acquired by the acquisition unit 151 (step S2A).

[0063] Next, the coordinate transformation unit 153 executes a coordinate transformation process for transforming the coordinates of each point that makes up the line marker extracted by the line marker extraction unit 152A so that the image of the target surface of the steel material taken obliquely from above becomes the image of the target surface of the steel material taken vertically from above (step S3). Hereinafter, with reference to the flowchart of FIG. 14, the flow of the coordinate transformation process executed by the processing unit 100 according to the second embodiment will be described.

[0064] (Coordinate transformation process) First, the coordinate transformation unit 153 calculates the interior angles A, B, and C shown in FIG. 12 based on the captured image of the target surface of the steel material acquired by the camera 21 (step S31A).

[0065] Next, based on the base line length (the length of line AB) and the interior angles A, B, and C calculated in the process of step S31A, the coordinate conversion unit 153 calculates the distance from point A to the target surface of the steel material (step S32A).

[0066] Next, based on the coordinate value of point A and the distance from point A to the target surface of the steel material calculated in the process of step S32A, the coordinate conversion unit 153 calculates the coordinates of each point constituting the line marker extracted by the line marker extraction unit 152A (step S33A), and returns the process. By the process of step S33A, as shown in FIG. 11(b), the coordinates of each point in the image obtained by photographing the target surface of the steel material obliquely can be converted into the coordinates of each point in the image obtained by photographing the target surface of the steel material directly from above, as shown in FIG. 11(c). The above is the flow of the coordinate conversion process according to the second embodiment.

[0067] Returning to FIG. 13, based on the point group composed of a plurality of points constituting each line marker whose coordinates have been converted by the coordinate conversion unit 153, the shape calculation unit 154 calculates a curve indicating the contour shape of a desired portion of the steel material, as shown in FIG. 11(d) (step S4A). Next, the straightness calculation unit 155 and the output unit 156 sequentially execute the processes of step S5 and step S6, respectively, and end the process. The above is the flow of the shape measurement procedure according to the second embodiment.

[0068] As described above, the shape measurement system 1 according to the second embodiment extracts the shape of each line marker drawn on the target surface of the steel material, and calculates a curve indicating the contour shape of a desired portion of the steel material based on the point group constituting each line marker. Therefore, even for a steel material that does not have a sharp edge, the shape of the steel material can be accurately measured.

[0069] The present invention is not limited to the above embodiments, and the following modifications are also possible.

[0070] (Modification example) In the above-described embodiment, the multi-line light source 10A emits laser beams, but the present invention is not limited to this. As long as the imaging unit 20 can image the line marker, the beam emitted from the multi-line light source 10A may be other than a laser beam.

[0071] In the above-described embodiment, the multi-line light source 10A emits two line-shaped laser beams in directions away from each other to draw two line markers on the target surface of the steel material. However, the present invention is not limited to this. For example, the multi-line light source 10A may emit three or more laser beams in directions away from each other. Even in this case, it is preferable that the angle formed by adjacent laser beams is constant. Also, when the multi-line light source 10A emits an odd number of beams, the laser beam located in the middle is preferably perpendicular to the target surface of the steel material.

[0072] In the above-described embodiment, the distance between the pair of line markers is obtained from the captured image of the camera, and the distance between the multi-line light source 10A and the target surface of the steel material is calculated based on the distance between the pair of line markers, thereby obtaining the distance from the irradiation unit 10 to the target surface of the steel material. However, the present invention is not limited to this. For example, when the displacement of the multi-line light source 10A can be ignored depending on the length of the long object, the coordinate value of the multi-line light source 10A may be set as a design value. The distance from the irradiation unit 10 to the target surface of the steel material calculated based on the coordinate value of the multi-line light source 10A is stored in the storage unit 140, and the distance from the irradiation unit 10 to the target surface of the steel material may be obtained from the storage unit 140 when the shape measurement process is executed.

[0073] In the above-described embodiment, the approximate curve generated based on all the intersections between each line marker and the edge is used as the curve indicating the edge shape. However, the present invention is not limited to this. For example, the curve indicating the edge shape may be generated by connecting adjacent intersections with a smooth curve.

[0074] In the above-described Embodiment 2, the calibration camera 10C was provided in association with a part of the multi-line light source 10A. However, the present invention is not limited to this. For example, the calibration camera 10C may be provided in one-to-one association with all of the multi-line light sources 10A.

[0075] In the above-described Embodiment 2, the calibration camera 10C was used for calibrating the relative positions of the multi-line light source 10A and the imaging unit 20. However, the present invention is not limited to this. For example, the calibration camera 10C may be used to measure the shape of the target surface of the steel material by the optical cutting method. Specifically, a linear laser beam from the multi-line light source 10A may be irradiated onto the target surface of the steel material, the reflected light may be received by the calibration camera 10C, and the profile of the target surface of the steel material may be generated in the processing unit 100.

[0076] Further, when three or more calibration cameras 10C are provided in the irradiation unit 10, the edge shape of the steel material being conveyed may be measured by the successive three-point method. In the successive three-point method, the distance between adjacent calibration cameras 10C is known. From the captured images of each calibration camera 10C, the distance in the X-axis direction between the measurement reference line set to extend in the conveyance direction of the steel material and the edge of the steel material is calculated. Based on the distance between each calibration camera 10C and the distance in the X-axis direction between the measurement reference line and the edge of the steel material, a process of calculating the straightness of the edge of the steel material may be executed. The control unit 150 of the processing unit 100 may transmit a control signal instructing the imaging timing to each calibration camera 10C, and after receiving the images simultaneously captured by each calibration camera 10C, execute the above-described process. Hereinafter, the measurement of the edge shape of the steel material using the captured image of the imaging unit 20 is referred to as a static measurement method, and the measurement of the edge shape of the steel material using the captured image of the calibration camera 10C is referred to as a dynamic measurement method.

[0077] In connection with the above-described modification, the control unit 150 of the processing unit 100 may simultaneously perform static measurement of the edge shape of the steel material using the captured image of the imaging unit 20 and dynamic measurement of the edge shape of the steel material by the sequential three-point method using the captured images of the calibration cameras 10C. Generally, since the steel material to be measured deforms according to the applied stress, it deforms depending on the placement posture and the conveyance state. For this reason, the static measurement result A of the edge shape using the captured image of the imaging unit 20 and the dynamic measurement result B of the edge shape by the sequential three-point method using the captured images of the calibration cameras 10C are different from each other. Therefore, as shown in FIG. 15, the control unit 150 of the processing unit 100 may calculate the difference between the measurement results A and B, or may calculate the average of the measurement results A and B. The measurement results A and B may be, for example, an approximate curve indicating the edge shape, or may be straightness. Based on the difference between the measurement results A and B, the user can estimate the stress state applied to the steel material to be measured and the process of stress relaxation. Also, based on the average of the measurement results A and B, even when the stress state of the steel material and the process of stress relaxation differ for each individual to be measured, the edge shape of the steel material can be stably measured.

[0078] In the above embodiment, various data were stored in the storage unit 140 of the processing unit 100, but the present invention is not limited to this. For example, all or part of the various data may be stored in an external server or computer via a communication network.

[0079] In the above embodiment, the processing unit 100 operates based on the programs stored in the storage unit 140, respectively, but the present invention is not limited to this. For example, the functional configuration realized by the program may be realized by hardware.

[0080] In the above embodiment, the processing unit 100 is a general-purpose computer, but the present invention is not limited to this. For example, the processing unit 100 may be realized by a computer provided on the cloud.

[0081] In the above-described embodiment, the processing executed by the processing unit 100 was realized by executing a program stored in the storage unit 140 by a device having the above-described physical configuration. However, the present invention may be realized as a program, or may be realized as a storage medium on which the program is recorded.

[0082] Also, a program for executing the above-described processing operation may be stored and distributed in a non-temporary recording medium readable by a computer, such as a flexible disk, a CD-ROM (Compact Disk Read-Only Memory), a DVD (Digital Versatile Disk), or an MO (Magneto-Optical Disk). By installing the program in a computer, a device for executing the above-described processing operation may be configured.

[0083] The above-described embodiment is an example, and the present invention is not limited thereto. Various embodiments are possible without departing from the gist of the invention described in the claims. The constituent elements described in each embodiment and modification can be freely combined. Also, the invention equivalent to the invention described in the claims is included in the present invention.

Description of Reference Numerals

[0084] 1 Shape measurement system 10 Irradiation unit 10A Multi-line light source 10B Housing 10C Calibration camera 20 Imaging unit 21 Camera 22 Lens 100 Processing unit 110 Operation unit 120 Display unit 130 Communication unit 140 Storage unit 141 Image data storage unit 142 Conversion table storage unit 150 Control unit 151 Acquisition unit 152 Intersection Point Extraction Unit 152A Line Marker Extraction Unit 153 Coordinate Conversion Unit 154 Shape Calculation Unit 155 Straightness Calculation Unit 156 Output Unit

Claims

1. An irradiation unit including a plurality of multi-line light sources, wherein the multi-line light sources are arranged side by side in the longitudinal direction of an elongated object by emitting a plurality of linear beams in directions away from each other, and draw a plurality of line markers intersecting an edge extending in the longitudinal direction of the elongated object on a target surface of the elongated object; A photographing unit that photographs, in an oblique direction, a target surface of the elongated object including the line markers drawn by the irradiation unit, from an end side in the longitudinal direction of the elongated object; A processing unit that obtains a distance from the irradiation unit to the target surface of the elongated object, and calculates a curve indicating the edge shape of the elongated object based on the positions of the respective line markers in the image photographed by the photographing unit and the obtained distance from the irradiation unit to the target surface of the elongated object. The processing unit includes: An intersection extraction unit that extracts intersections between each line marker and the edge of the elongated object in the image photographed by the photographing unit; A coordinate conversion unit that converts the coordinates of each intersection extracted by the intersection extraction unit based on the obtained distance from the irradiation unit to the target surface of the elongated object so that the image photographed by the photographing unit is an image obtained by vertically photographing the target surface of the elongated object from above; A shape calculation unit that calculates a curve indicating the edge shape of the elongated object based on a point group composed of intersections whose coordinates have been converted by the coordinate conversion unit. A shape measurement system.

2. An irradiation unit including a plurality of multi-line light sources, wherein the multi-line light sources are arranged side by side in the longitudinal direction of an elongated object by emitting a plurality of linear beams in directions away from each other, and draw a plurality of line markers intersecting an edge extending in the longitudinal direction of the elongated object on a target surface of the elongated object; A photographing unit that photographs, in an oblique direction, a target surface of the elongated object including the line markers drawn by the irradiation unit, from an end side in the longitudinal direction of the elongated object; A processing unit that obtains a distance from the irradiation unit to the target surface of the elongated object, and calculates a curve indicating the edge shape of the elongated object based on the positions of the respective line markers in the image photographed by the photographing unit and the obtained distance from the irradiation unit to the target surface of the elongated object. The processing unit includes: An intersection extraction unit that extracts intersections between each line marker and the edge of the elongated object in the image photographed by the photographing unit; A coordinate conversion unit that converts the coordinates of each intersection point extracted by the intersection point extraction unit so that the image captured by the imaging unit is an image that vertically captures the target surface of the long object from above, A shape calculation unit that calculates a curve indicating the edge shape of the long object based on a point group composed of intersection points whose coordinates have been converted by the coordinate conversion unit, The coordinate conversion unit, Based on the distance between the irradiation unit and the target surface of the long object, selects a conversion table corresponding to the distance stored in the storage unit, With reference to the selected conversion table, converts the coordinates of each intersection point extracted by the intersection point extraction unit so that the image captured by the imaging unit is an image that vertically captures the target surface of the long object from above, Shape measurement system.

3. An irradiation unit including a plurality of multi-line light sources, wherein the multi-line light sources are arranged side by side in the longitudinal direction of the long object by emitting a plurality of line-shaped beams in directions away from each other, and draw a plurality of line markers intersecting the contour extending in the longitudinal direction of the long object on the target surface of the long object. An irradiation unit, An imaging unit that captures the target surface of the long object including the line markers drawn by the irradiation unit obliquely from the end side in the longitudinal direction of the long object, A processing unit that obtains the distance from the irradiation unit to the target surface of the long object, and calculates a curve indicating the contour shape of the long object based on the position of each line marker in the image captured by the imaging unit and the obtained distance from the irradiation unit to the target surface of the long object, The processing unit, A line marker extraction unit that extracts a plurality of points constituting each line marker in the image captured by the imaging unit, A coordinate conversion unit that converts the coordinates of each point extracted by the line marker extraction unit based on the obtained distance from the irradiation unit to the target surface of the long object so that the image captured by the imaging unit is an image that vertically captures the target surface of the long object from above, A shape calculation unit that calculates a curve indicating the contour shape of the long object based on a point group composed of points whose coordinates have been converted by the coordinate conversion unit, Shape measurement system.

4. The coordinate conversion unit applies triangulation to a first point where the multi-line light source is disposed, a second point where the imaging unit is disposed, and a third point on a line marker drawn by the multi-line light source, thereby converting the coordinates of each point of the line marker extracted by the line marker extraction unit. The shape measurement system according to claim 3.

5. The processing unit calculates the distance from the irradiation unit to the target surface of the long object based on the intervals between the line markers drawn by the same multi-line light source in the image captured by the imaging unit. The shape measurement system according to any one of claims 1 to 4.

6. The shape measurement system further includes a moving mechanism that movably supports the irradiation unit in the width direction of the long object. The shape measurement system according to any one of claims 1 to 5.

7. The irradiation unit is provided corresponding to the multi-line light source, the relative position with respect to the multi-line light source is calibrated, and further includes a calibration camera for photographing different portions of the long object. The shape measurement system according to any one of claims 1 to 6.

8. The irradiation unit includes at least three or more calibration cameras. The processing unit calculates a curve indicating the edge shape of the long object based on at least three images showing different portions of the long object simultaneously photographed by each calibration camera. The shape measurement system according to claim 7.

9. A shape measurement method executed by a shape measurement system, a step of drawing a plurality of line markers intersecting an edge extending in the longitudinal direction of the long object on the target surface of the long object by radiating a plurality of line-shaped beams in directions away from each other by the multi-line light source of the irradiation unit, and arranging them side by side in the longitudinal direction of the long object; a step of the imaging unit photographing the target surface of the long object including the line marker drawn by the multi-line light source obliquely from the end side in the longitudinal direction of the long object; a step of the processing unit extracting the intersection points between each line marker and the edge of the long object in the image captured by the imaging unit. The step of the processing unit obtaining the distance from the irradiation unit to the target surface of the long object, and converting the coordinates of each extracted intersection point based on the obtained distance from the irradiation unit to the target surface of the long object so that the image captured by the imaging unit is an image capturing the target surface of the long object vertically from above. The step of the processing unit calculating a curve indicating the edge shape of the long object based on a point cloud composed of intersection points whose coordinates have been converted. A shape measurement method including the above. [

10. ] A shape measurement method executed by a shape measurement system, The step of the multi-line light source of the irradiation unit emitting a plurality of line-shaped beams in directions away from each other, thereby drawing a plurality of line markers arranged side by side in the longitudinal direction of the long object and intersecting the contour extending in the longitudinal direction of the long object on the target surface of the long object. The step of the imaging unit capturing the target surface of the long object including the line markers drawn by the multi-line light source obliquely from the end side in the longitudinal direction of the long object. The step of the processing unit extracting a plurality of points constituting each line marker in the image captured by the imaging unit. The step of the processing unit obtaining the distance from the irradiation unit to the target surface of the long object, and converting the coordinates of each extracted point based on the obtained distance from the irradiation unit to the target surface of the long object so that the image captured by the imaging unit is an image capturing the target surface of the long object vertically from above. The step of the processing unit calculating a curve indicating the contour shape of the long object based on a point cloud composed of points whose coordinates have been converted. A shape measurement method including the above.

Images