Method and system for determining the position coordinates of the center of a steel plate, and a crane.

Abstract

The present invention provides a method and system for determining the position coordinates of the center of a steel plate, which can more reliably and accurately determine the position coordinates of the center of the steel plate, as well as a crane. [Solution] The method for determining the position coordinates of the center of a steel plate comprises a preparation step S100 and a determination step S200. In the preparation step S100, the vertical distance b from a predetermined point P located within the area R occupied by the identification information N to the short side Ss of the steel plate SP, and the vertical distance a from the predetermined point P to the long side Ls are determined in advance. In the determination step S200, image data D1 is acquired by the imaging device 2, and the image data D1 is processed by the arithmetic device 3 to determine the width dimension W and length dimension H of the steel plate SP based on the identification information N, as well as the position coordinates (x, y) of the predetermined point P in the steel plate coordinate system Cs. Based on the width dimension W, length dimension H, position coordinates (x, y) of the predetermined point P, and vertical distances a and b, the position coordinates (xc, yc) of the center C are determined.

Description

Technical Field

[0001] The present invention relates to a method and a system for specifying the position coordinates of the center of a steel plate, and a crane. More specifically, the present invention relates to a method and a system for specifying the position coordinates of the center of a steel plate, which can more reliably and accurately specify the position coordinates of the center of the steel plate, and a crane.

Background Art

[0002] For the automation of the handling of steel plates by a crane in a steelworks or a steel material warehouse, it is essential to specify the position coordinates of the center of the steel plate. A method has been proposed for detecting the center point and the center of gravity position of a steel slab, which is the material of the steel plate, using an image captured by a camera (see Patent Document 1). The method proposed in Patent Document 1 performs image processing on an image captured by a camera using the difference in brightness between the plane and the side surface of the steel slab, extracts a plane image (an image in which the edge of the plate surface is specified) and a side surface image, and obtains the center point and the center of gravity position of the steel slab.

[0003] In a steelworks or a steel material warehouse, a plurality of steel plates stacked on a pallet or the like are handled by a crane. Steel plates include thin plates (less than 3 mm thick), medium plates (3 mm or more and less than 6 mm thick), thick plates (6 mm or more and less than 150 mm thick), extra thick plates (150 mm or more thick), etc. Generally, the thickness of the steel plate is very small compared to the thickness of the steel slab. In addition, the stacked steel plates generally exhibit approximately the same color. Therefore, not only is it difficult to distinguish the boundaries (edges) between the steel plates in a top view image, but it is also difficult to distinguish the boundaries between the steel plates in a side view image. Therefore, even if the method proposed in Patent Document 1 is simply applied to the steel plate, it is difficult to accurately specify the edge of each steel plate, and the position coordinates of the center of the steel plate cannot be specified. Therefore, there is room for improvement in more reliably and accurately specifying the position coordinates of the center of the steel plate.

Prior Art Documents

Patent Documents

[0004] [Patent Document 1] Japanese Patent Application Publication No. 7-330287 [Overview of the project] [Problems that the invention aims to solve]

[0005] The object of the present invention is to provide a method and system for determining the position coordinates of the center of a steel plate, and a crane, which can more reliably and accurately determine the position coordinates of the center of the steel plate. [Means for solving the problem]

[0006] The present invention provides a method for determining the position coordinates of the center of a steel plate that achieves the above objective, comprising: acquiring image data of the upper surface of a steel plate on which identification information exists using a photographic device; and using the acquired image data to determine the position coordinates of the center of the steel plate using a calculation device, wherein the method comprises a determination step for determining the position coordinates of the center and a preparation step preceding this determination step, wherein in the preparation step, the vertical distance from a predetermined point within the area occupied by the identification information to the short side of the steel plate and the vertical distance from the predetermined point to the long side of the steel plate are determined in advance; in the determination step, the image data is acquired using the photographic device, and the image data is processed by the calculation device to determine the width dimension and length dimension of the steel plate based on the identification information, and to determine the position coordinates of the predetermined point in a steel plate coordinate system having coordinate axes oriented in the respective extending directions of the short side and the long side, and to determine the position coordinates of the center in the steel plate coordinate system based on the width dimension, the length dimension, the position coordinates of the predetermined point and the respective vertical distances determined in advance.

[0007] The present invention provides a system for determining the center coordinates of a steel plate, comprising: a shooting device that acquires image data of the upper surface of a steel plate on which identification information exists; and a calculation device that determines the center coordinates of the steel plate based on the acquired image data. The system is characterized in that it has a storage unit that stores in advance the vertical distance from a predetermined point within the area occupied by the identification information to the short side of the steel plate and the vertical distance from the predetermined point to the long side of the steel plate. The calculation device is configured to perform data processing that determines the length and width dimensions of the steel plate based on the image data, and determines the position coordinates of the predetermined point in a steel plate coordinate system in which mutually orthogonal coordinate axes are oriented in the respective extending directions of the short side and the long side, and determines the center coordinates in the steel plate coordinate system based on the length dimension, the width dimension, the position coordinates of the predetermined point, and the respective vertical distances stored in the storage unit.

[0008] The crane of the present invention is characterized by comprising the center position coordinate identification system of the steel plate described above. [Effects of the Invention]

[0009] According to the present invention, even when the boundaries between steel plates in image data are unclear, the identification information is clear, so a predetermined point located in the area occupied by that identification information can be reliably detected. The positional relationship between the predetermined point and the center in the steel plate coordinate system can be expressed by the vertical distance from the predetermined point to each of the short and long sides of the steel plate, and the width and length dimensions of the steel plate. Therefore, by knowing the respective vertical distances in advance and determining the position coordinates of the predetermined point in the steel plate coordinate system, the position coordinates of the center in the steel plate coordinate system can be determined with high accuracy. As a result, even when the boundaries between steel plates in image data are unclear due to the steel plates being of similar colors or being thin, the position coordinates of the center of the steel plate can be determined with greater reliability and accuracy. [Brief explanation of the drawing]

[0010] [Figure 1]This is an explanatory diagram illustrating an embodiment of a system for determining the position coordinates of the center of a steel plate and a crane. [Figure 2] This is an explanatory diagram illustrating image data. [Figure 3] This flowchart illustrates the procedure for an embodiment of a method for determining the position coordinates of the center of a steel plate. [Figure 4] This is an explanatory diagram illustrating the upper surface of a steel plate in the steel plate coordinate system. [Figure 5] This is an explanatory diagram illustrating management data. [Figure 6] This is an explanatory diagram illustrating the upper surface of a steel plate in a crane coordinate system. [Modes for carrying out the invention]

[0011] The method and system for determining the center position coordinates of a steel plate, as well as the crane, according to the present invention, will be described below based on the embodiments shown in the figures.

[0012] The specific system 1 illustrated in Figure 1 comprises a camera 2 and a computing device 3. This specific system 1 is an embodiment of the steel plate center position coordinate identification system of the present invention, and the crane 10 equipped with this specific system 1 is an embodiment of the crane of the present invention. The method for identifying the center position coordinate of a steel plate illustrated in Figure 3 is performed using this specific system 1. This identification method is performed when the crane 10 is loading or unloading a steel plate SP and is used to identify the position coordinates (Xc, Yc) of the center C of the steel plate SP.

[0013] The outline of this identification method will be explained. This identification method utilizes unique identification information N present on the upper surface of the steel plate SP, as illustrated in Figure 4, which will be described later. In the procedure of this identification method, in the preparation step S100, the vertical distances a and b from a predetermined point P in the region R occupied by the identification information N to each of the long side Ls and short side Ss of the steel plate SP are determined. Next, in the identification step S200, image data D1 is acquired by the imaging device 2 (S210). Then, by processing the image data D1 with the arithmetic device 3, the length dimension H and width dimension W of the steel plate SP are determined based on the identification information N, and the position coordinates (x, y) of the predetermined point P in the steel plate coordinate system Cs are determined. Next, based on the length dimension H, width dimension W, position coordinates (x, y) of the predetermined point P, and vertical distances a and b, the position coordinates (xc, xc) of the center C of the steel plate SP in the steel plate coordinate system Cs are determined (S230, S240). Finally, the position coordinates (Xc, Yc) of the center C of the steel plate SP in the crane coordinate system Cc are determined (S250). Note that the steel plate coordinate system Cs and the crane coordinate system Cc may be the same.

[0014] First, we will explain the details of the crane 10 and the specific system 1.

[0015] The crane 10 illustrated in Figure 1 is used for loading and unloading steel plates SP in steel mills and steel warehouses. Various known cranes can be used as crane 10. For example, crane 10 is a gantry crane used for loading and unloading steel plates SP shipped from a steel mill onto a ship S. Crane 10 comprises a structure 11, a trolley 12, a lifting device 13, and a specific system 1.

[0016] The structure 11 has a traveling device 14, a girder (boom, etc.) 15 that extends in one direction (from land to sea), and multiple legs 17 to which the traveling device 14 is attached at the lower end and which are connected to each other by horizontal members (sill beam, tie beam, etc.) 16. The trolley 12 runs along the girder 15. The lifting device 13 is suspended from the trolley 12 via a cable-like body (wire rope).

[0017] The crane 10 is not limited to the above configuration. The crane 10 may be, for example, a transfer crane (gantry crane) or an overhead crane that handles the steel plate SP across a storage lane for temporarily storing the steel plate SP.

[0018] The imaging device 2 is installed on any one of the trolley 12, the spreader 13, the horizontal member 16, and the leg 17 of the crane 10, and acquires image data D1 of the upper surface of the steel plate SP. Various known cameras can be used for this imaging device 2. It is desirable that the optical axis of the lens is perpendicular to the upper surface of the steel plate SP, but it may be inclined from the perpendicular line of the upper surface. It is not necessary for the entire steel plate SP to be present in the acquired image data D1 by the imaging device 2, and it is sufficient if the entire identification information N present on the upper surface of the steel plate SP is present. However, when the positions of the identification information N on the plurality of stacked steel plates SP are not aligned, it is preferable that the entire plurality of stacked steel plates SP are present in the imaging device 2. The image data D1 acquired by the imaging device 2 is stored in the auxiliary storage unit 6 of the arithmetic unit 3.

[0019] The arithmetic unit 3 receives and stores various data, and performs data processing using these data. Various known computers can be used for the arithmetic unit 3. The arithmetic unit 3 has a central processing unit (CPU) 4, a main storage unit (memory) 5, and an auxiliary storage unit (for example, HDD) 6. The auxiliary storage unit 6 corresponds to the storage unit of the present invention. The image data D1 and the vertical distances a and b illustrated in FIG. 4 described later are stored in this auxiliary storage unit 6.

[0020] The image data D1 illustrated in FIG. 2 is acquired by the imaging device 2 whose optical axis of the lens is perpendicular to the upper surface of the steel plate SP, and is stored in the auxiliary storage unit 6. In the image data D1, there are a plurality of steel plates SP stacked on the pallet PL. Specifically, there are four steel plates SP with different dimensions stacked on the pallet PL in the image data D1. Also, in the image data D1, the identification information N (XXXXX, YYYYY, ZZZZZ) of the first, second, and fourth steel plates SP from the top is present.

[0021] Steel plate SP is produced and managed at steel mills and steel material warehouses, shipped to clients such as manufacturers and processors, and processed into products. Steel plate SP is a steel material processed from a steel ingot (slab) into a plate shape. Steel plate SP is classified into four types according to its thickness: thin plate (less than 3 mm thick), medium plate (3 mm or more and less than 6 mm thick), thick plate (6 mm or more and less than 150 mm thick), and extra-thick plate (150 mm or more thick). Steel plate SP also includes surface-treated steel plates such as galvanized steel plate, tin-plated steel plate, tin-free steel plate, vinyl chloride-coated steel plate, copper-plated steel plate, and painted steel plate, which have undergone surface treatment processing.

[0022] Each of the plurality of steel plates SP stacked on the pallet PL has its orientation, such as the short side direction or long side direction of each steel plate SP, generally aligned with the short side direction or long side direction of the pallet PL. Also, the centers of the plurality of stacked steel plates SP are generally aligned, and their centers are generally aligned with the center of the pallet PL. Therefore, when there are a plurality of identification information N in the image data D1, the identification information N closest to the center of the pallet PL is the identification information N of the topmost steel plate SP.

[0023] Unique identification information N is assigned to the upper surface of the steel plate SP and is managed according to this identification information N. The identification information N has a unique management number different for each steel plate SP as essential information, and as other information, for example, it may have each dimension (thickness dimension, width dimension, length dimension) of the steel plate SP, raw material name, destination (client name), manufacturer, etc. The identification information N in the embodiment has a management number (XXXXX, YYYYY, ZZZZZ, etc.). For the identification information N, for example, a character string representing each of the above-mentioned information, a one-dimensional barcode, a two-dimensional barcode, etc. are used. The identification information N is directly written on the upper surface of the steel plate SP by stenciling using a template (stencil sheet), or is displayed on a label pasted on the upper surface.

[0024] The identification information N is located at a predetermined position on the upper surface of the steel plate SP. This predetermined position can be set arbitrarily, except for the center C of the upper surface. If the identification information N is located at the center C of the upper surface, the position coordinates of the center C can be roughly determined using the identification information N as a landmark, so this embodiment is not necessary.

[0025] The identification information N has a high contrast with the upper surface of the steel plate SP so that it can be easily confirmed by visual inspection. Therefore, even if the boundaries between multiple steel plates SP in the image data D1 are unclear and the edges (outer periphery of the steel plate SP) cannot be identified even after image processing, the identification information N is clear and its position in the image data D1 can be reliably determined. In other words, in this embodiment, the position coordinates of the center C of the steel plate SP are determined by using the identification information N, which is clearer than the edges of the steel plate SP, as a clue.

[0026] In the procedure for determining the center coordinates of a steel plate as illustrated in Figure 3, the preparation step S100 and the identification step S200 are performed in order. The details of each step S210 to S240 of the preparation step S100 and the identification step S200 are described below.

[0027] In preparation step S100, the vertical distance a from a predetermined point P to the long side Ls of the steel plate SP and the vertical distance b from the predetermined point P to the short side Ss are determined. These vertical distances a and b may be measured using an actual steel plate SP, or they may be set values ​​used in the manufacturing process of the steel plate SP. The determined vertical distances a and b are stored in the auxiliary storage unit 6 of the calculation unit 3.

[0028] Figure 4 shows the top surface of the steel plate SP in the steel plate coordinate system Cs. The X and Y axes in Figure 4 are the coordinate axes of the steel plate coordinate system Cs. The X axis is oriented in the direction of the extension of the long side Ls of the steel plate SP, and the Y axis is oriented in the direction of the extension of the short side Ss of the steel plate SP, and they are orthogonal to each other. The dashed rectangle in Figure 4 represents the region R, and the white circles represent the center C, a predetermined point P, and a reference point Q.

[0029] The steel plate coordinate system Cs is a Cartesian coordinate system having mutually orthogonal coordinate axes (X-axis, Y-axis) oriented in the respective directions of extension of the long side Ls and short side Ss of the steel plate SP. The origin of the steel plate coordinate system Cs can be set arbitrarily within the range of the image data D1, but it is preferable to set it at the center of the image data D1. When the imaging device 2 captures the image data D1, if the horizontal and vertical directions in the image data D1 are aligned with the respective directions of extension of the long side Ls and short side Ss of the steel plate SP, then the coordinate system of the image data D1 can be used for the steel plate coordinate system Cs. If the coordinate system of the steel plate coordinate system Cs and the coordinate system of the image data D1 are different, the coordinate system of the image data D1 can be converted to the steel plate coordinate system Cs. Various known coordinate transformation methods can be used for this coordinate transformation. For example, since the outer perimeter of pallet PL in image data D1 is clear, a coordinate transformation can be determined so that the extension directions of the long and short sides of pallet PL coincide with the horizontal and vertical directions of image data D1, and this coordinate transformation can be used to convert the coordinate system of image data D1 to the steel plate coordinate system Cs. Alternatively, the degree of inclination between the optical axis of the lens of the imaging device 2 and the upper surface of the steel plate SP can be determined in advance, and a coordinate transformation corresponding to that inclination can be determined, and this coordinate transformation can be used to convert the coordinate system of image data D1 to the steel plate coordinate system Cs. Furthermore, if the imaging device 2 is positioned on the trolley 12 or lifting device 13, the coordinate system of image data D1 can be used as the crane coordinate system Cc.

[0030] Region R represents the area occupied by the identification information N. The shape and dimensions of region R can be arbitrarily set as long as all of the identification information N is included within its range, but it is preferable that they be the same as the shape and dimensions of the template or label used when assigning the identification information N to the steel plate SP. That is, it is preferable that the outer perimeter of region R represents the outer perimeter of the template or label. In this embodiment, the shape of region R is a rectangle having sides parallel to the short side Ss and sides parallel to the long side Ls. The shape and dimensions of region R may differ for each steel plate SP with different identification information N.

[0031] Identification information N is assigned to a region R at a predetermined interval between each of the long side Ls and short side Ss that form the reference point Q, with one of the four corners of the upper surface of the steel plate SP serving as the reference point Q. For example, in a steel mill, a belt conveyor is used to produce the steel plates SP, and the assignment of identification information N to the steel plates SP is performed on the belt conveyor. In this case, identification information N is assigned with the corner formed at one of the ends of the short side Ss, which is either the leading or trailing end of the belt conveyor, as the reference point Q. Therefore, as long as the shape and dimensions of region R, the reference point P, and the predetermined interval are not changed, the positional relationship between identification information N (region R) and reference point Q will be approximately the same even for steel plates SP of different types and dimensions. The predetermined intervals for each of the long side Ls and short side Ss may be the same or different.

[0032] The predetermined point P can be set arbitrarily within the range of region R, but it is preferable to set it at a characteristic location within region R (for example, the center or corner of region R). As described above, even if the steel plates SP differ in type and dimensions, if the shape and dimensions of region R, the reference point Q, and the predetermined interval are the same, the positional relationship between the reference point Q and the identification information N (region R) will be approximately the same. Therefore, the positional relationship between the predetermined point P and the reference point Q will also be the same.

[0033] In this embodiment, the predetermined point P is a corner of region R located near the reference point Q in the manufacturing process of the steel plate SP. The vertical distance a is the length of the perpendicular from the predetermined point P to the long side Ls, and the vertical distance b is the length of the perpendicular from the predetermined point P to the short side Ss. In other words, the vertical distance a is the shortest distance from the long side Ls to the side of region R parallel to the long side Ls, and the vertical distance b is the shortest distance from the short side Ss to the side of region R parallel to the short side Ss. That is, the respective vertical distances a and b can be set to a predetermined interval used when assigning identification information N to the steel plate SP. Furthermore, the sum of the vertical distance a and the length of the side of region R parallel to the short side Ss is less than half the width dimension W of the steel plate SP, and the sum of the vertical distance b and the length of the side of region R parallel to the long side Ls is less than half the length dimension H of region R.

[0034] Once determined, the respective vertical distances a and b remain the same even for steel plates SP of different types and dimensions, as long as the shape and dimensions of the region R, the reference point Q, and the predetermined intervals are not changed. Therefore, in the position coordinate identification method of this embodiment, the preparation step S100 can be omitted after it has been performed once.

[0035] In step S210, the imaging device 2 acquires image data D1 of the upper surface of the steel plate SP. The acquired image data D1 is stored in the auxiliary storage unit 6 of the arithmetic unit 3. This step S210 is performed, for example, when a pallet PL with multiple steel plates SP stacked on top of each other is placed between the legs of the crane 10, and the crane 10 starts loading and unloading these steel plates SP. In other words, this step S210 is performed in conjunction with the operation commands and control commands related to the loading and unloading of the crane 10.

[0036] In step S220, the arithmetic unit 3 reads identification information N from the image data D1 and performs data processing to identify the length dimension H (extended length of the long side Ls) and width dimension W (extended length of the short side Ss) of the steel plate SP based on the identification information N. Various known optical character recognition (OCR) functions and barcode reader functions can be used to read the identification information N from the image data D1. If the identification information N contains the dimensions of the steel plate SP, in step S220, only those dimensions need to be read. The dimensions of the steel plate SP are, for example, thickness × width dimension W × length dimension H. If the identification information N does not contain the dimensions of the steel plate SP, in step S220, a management number is read as the identification information N, and the length dimension H and width dimension W can be identified based on the management data D2, which is an aggregate of the length dimension H and width dimension W for each management number, and the read management number.

[0037] The management data D2 illustrated in Figure 5 is stored in the auxiliary storage unit 6 of the arithmetic unit 3. This management data D2 is used for managing steel plates SP in steel mills and steel warehouses. The management data D2 contains data such as vertical distances a and b, dimensions (thickness × width W × length H), and raw material names for each management number (XXXXX, YYYYY, ..., ZZZZZ, ...). In Figure 5, these are abbreviated with "...", but in reality, numerical values ​​and names are written in place of "...". When changing the shape and dimensions of the area R, the reference point Q, or predetermined intervals for each management number, that is, when vertical distances a and b differ for each management number, it is preferable to identify the vertical distances a and b based on the management data D2 when specifying the length H and width W of the steel plate SP in step S220. In this way, even if vertical distances a and b differ for each management number, the appropriate vertical distances a and b can be identified for each management number by using the management data D2.

[0038] In step S230, the arithmetic unit 3 detects a predetermined point P from the image data D1 and performs data processing to determine the position coordinates (x, y) of the predetermined point P in the steel plate coordinate system Cs. To detect the predetermined point P from the image data D1, the character area or barcode area detected in the process of various known optical character recognition (OCR) functions or barcode reader functions is used as area R. Therefore, each function should be set so that the shape and dimensions of the character area or barcode area are approximately equal to the shape and dimensions of area R. If the predetermined point P is a corner of area R located near the reference point Q when assigning identification information N to the steel plate SP, the predetermined point P is identified based on the corner of the pallet PL. Since the edge of the pallet PL in the image data D1 is sharper than the edge of the steel plate SP, the corner of the pallet PL can be identified based on the image data D1. Furthermore, since the sum of the vertical distance a and the extended length of the side of region R parallel to the short side Ss is less than half the width dimension W of the steel plate SP, and the sum of the vertical distance b and the extended length of the side of region R parallel to the long side Ls is less than half the length dimension H of region R, the predetermined point P can be identified as the corner of the detected region R that is closest to any corner of the pallet PL.

[0039] In step S240, the calculation unit 3 performs data processing to determine the position coordinates (xc, yc) of the center C of the steel plate SP in the steel plate coordinate system Cs, based on the length dimension H, width dimension W, position coordinates (x, y) of a predetermined point P, and the vertical distances a and b that have been determined in advance. Specifically, in this step S240, the position coordinates (xc, yc) of the center C in the steel plate coordinate system Cs are determined using the following formula (1).

[0040]

number

[0041] In step S250, the arithmetic unit 3 performs data processing to determine the position coordinates (Xc, Yc) of the center C in the crane coordinate system Cc, using a coordinate transformation from the steel plate coordinate system Cs to the crane coordinate system Cc. If the steel plate coordinate system Cs and the crane coordinate system Cc are the same, this step S250 can be omitted. If the steel plate coordinate system Cs and the crane coordinate system Cc are different, the position coordinates (Xc, Yc) of the center C in the crane coordinate system Cc are determined by transforming the position coordinates (xc, yc) determined in step S240 above, using a coordinate transformation from the steel plate coordinate system Cs to the crane coordinate system Cc.

[0042] If the imaging device 2 is positioned on the trolley 12 or lifting device 13 of the crane 10, the crane coordinate system Cc is the coordinate system of the image data D1. Therefore, the coordinate transformation from the steel plate coordinate system Cs to the crane coordinate system Cc can be performed using the inverse coordinate transformation from the coordinate system of the image data D1 to the steel plate coordinate system Cs. If the imaging device 2 is positioned on the horizontal member 16 or leg 17 of the crane 10, the coordinate transformation from the steel plate coordinate system Cs to the coordinate system of the image data D1 is performed first, and then the coordinate transformation from the coordinate system of the image data D1 to the crane coordinate system Cs is performed. In this case, the coordinate transformation from the steel plate coordinate system Cs to the image data D1 can be performed using the inverse coordinate transformation from the coordinate system of the image data D1 to the steel plate coordinate system Cs. Furthermore, the coordinate transformation from the coordinate system of the image data D1 to the crane coordinate system Cc can be performed using a coordinate transformation based on the positional relationship between the imaging device 2 and another imaging device positioned on the trolley 12 or lifting device 13 of the crane 10 and used during the handling of steel plates SP.

[0043] Figure 6 shows the top surface of the steel plate SP in the crane coordinate system Cc. The X and Y directions in Figure 6 represent the traverse and travel directions of the crane 10, and are orthogonal to each other. The white circle in Figure 6 indicates the center C of the first steel plate SP from the top among several stacked steel plates SP. Since the position coordinates (Xc, Yc) of the center C of the steel plate SP in the crane coordinate system Cc are specified, the amount of movement of the crane 10 in the traverse and travel directions when handling the steel plate SP with the crane 10 can be calculated based on the position coordinates (Xc, Yc). From this, the landing position of the lifting device 13 can be controlled with high precision.

[0044] As described above, according to this embodiment, even if the boundaries between steel plates SP or the edges (outer periphery of steel plates SP) in the image data D1 are unclear, the identification information N is clear, so a predetermined point P located in the region R occupied by the identification information N can be reliably detected. The positional relationship between the predetermined point P and the center C in the steel plate coordinate system Cs can be expressed by the vertical distances a and b from the predetermined point P to the respective short side Ss and long side Ls of the steel plate SP, and the width dimension W and length dimension H of the steel plate SP. Therefore, by knowing the respective vertical distances a and b in advance and determining the position coordinates (x, y) of the predetermined point P in the steel plate coordinate system Cs, the position coordinates (xc, yc) of the center C in the steel plate coordinate system Cs can be determined with high accuracy. As a result, even if the boundaries between steel plates SP in the image data D1 are unclear due to the steel plates being of similar colors or being thin, the position coordinates (xc, yc) of the center C of the steel plate SP can be determined with greater reliability and accuracy.

[0045] By identifying the position coordinates (Xc, Yc) of the center C of the steel plate SP in the crane coordinate system Cc, the landing position of the lifting device 13 when the steel plate SP is loaded and unloaded by the crane 10 can be controlled with high precision, greatly contributing to improved loading and unloading efficiency. Furthermore, by using the specific system 1, it becomes possible to automate the loading and unloading of the steel plate SP by the crane 10, significantly reducing the burden on workers such as verification work.

[0046] In step S230 described above, if the identification information N consists of multiple character strings, multiple regions R corresponding to each character string may be identified. In this case, optical character recognition identifies multiple character regions corresponding to each character string as multiple regions R. Then, a region R located near the reference point Q is selected from among the multiple regions R, and a predetermined point P is identified within the range of the selected region R. To select a region R located near the reference point Q from among the multiple regions R, the corners of the pallet PL can be used, similar to how the predetermined point P is identified. Note that if multiple steel plates SP are stacked directly on the ground instead of on the pallet PL, the boundary between the ground and the steel plates SP is clear, so the stacked steel plates SP can be treated as a single object. Therefore, in this case, the outer shape of the stacked steel plates SP viewed from above can be considered as a rectangle, and the corners of that rectangle can be used as corners of the pallet PL.

[0047] In step S240 described above, it is also possible to use a formula in which "-b+H / 2" is changed to "+bH / 2" and "+aW / 2" is changed to "-a+W / 2" in formula (1) described above. In this case, in the preparation step S100 described above, the vertical distance a from the predetermined point P to a long side different from the long side LS that constitutes the reference point Q, and the vertical distance b from the predetermined point P to a short side different from the short side SS that constitutes the reference point Q are determined. Thus, the vertical distances a and b that are determined in advance in the preparation step S100 are appropriately selected according to the formula used in step S240.

[0048] Although embodiments of the present invention have been described above, the method for determining the center position coordinates of a steel plate, the system for determining its position coordinates, and the crane are not limited to specific embodiments, and various modifications and changes are possible within the scope of the gist of the present invention. [Explanation of Symbols]

[0049] 1. Position Coordinate Identification System (Identification System) 2. Imaging device 3 Computing device 4. Processing Unit 5 Main memory 6 Auxiliary storage 10 Cranes 11 Structures 12 Trolley 13 Hanging equipment SP steel plate PL Palette N Identification Information Ls (long side) Short side C center R area P predetermined point Q reference point Cs Steel plate coordinate system Cc Crane Coordinate System D1 Image Data W width dimension of steel plate Length dimensions of H-shaped steel plate

Claims

1. In a method for determining the center coordinates of a steel plate, in which image data of the upper surface of a steel plate containing identification information is acquired by a photographing device, and the position coordinates of the center of the steel plate are determined by a calculation device using the acquired image data, The process includes a process for identifying the position coordinates of the center and a preparation process that precedes this identification process. In the preparation step, the vertical distance from a predetermined point within the area occupied by the identification information to the short side of the steel plate, and the vertical distance from the predetermined point to the long side of the steel plate are determined in advance. A method for determining the center coordinate of a steel plate, wherein in the specified step, the image data is acquired by the imaging device, and the image data is processed by the computing device to determine the width and length dimensions of the steel plate based on the identification information, and the position coordinates of the predetermined point in a steel plate coordinate system having coordinate axes oriented in the respective extending directions of the short side and the long side, and the position coordinates of the center in the steel plate coordinate system are determined based on the width dimension, the length dimension, the position coordinates of the predetermined point, and the respective vertical distances that have been determined in advance.

2. The method for determining the position coordinates of the center of a steel plate according to claim 1, wherein in the preparation step, the shape of the region is treated as a rectangle having sides substantially parallel to each of the short side and the long side, and the center of the rectangle or one of the four corners is selected as the predetermined point.

3. The method for determining the center coordinates of a steel plate according to claim 1, wherein in the specified step, the identification information is read by processing the image data, and the width dimension and length dimension are determined based on the management data which is an accumulation of the width dimension and length dimension for each piece of identification information and the identification information that has been read.

4. A method for determining the center coordinates of a steel plate according to claim 1, wherein in the specified step, the center coordinates are determined using the following formula (1), where the center coordinates are (xc, yc), the predetermined point coordinates are (x, y), the width dimension is W, the length dimension is H, the vertical distance from the predetermined point to the short side is b, and the vertical distance from the predetermined point to the long side is a. [Math 1] ・・・・・・（１）

5. The method for determining the position coordinates of the center of a steel plate according to claim 1, wherein the calculation device determines the position coordinates of the center in the crane coordinate system by using a coordinate transformation from the steel plate coordinate system to the crane coordinate system used by the crane that handles the steel plate during the handling of the steel plate.

6. A system for determining the center coordinates of a steel plate, comprising a shooting device that acquires image data of the upper surface of a steel plate on which identification information exists, and a calculation device that determines the center coordinates of the steel plate based on the acquired image data, The system has a storage unit that pre-stores the vertical distance from a predetermined point within the area occupied by the identification information to the short side of the steel plate, and the vertical distance from the predetermined point to the long side of the steel plate. A system for determining the center position coordinates of a steel plate, wherein the calculation device is configured to perform data processing to determine the length and width dimensions of the steel plate based on the image data, and to determine the position coordinates of a predetermined point in a steel plate coordinate system in which mutually orthogonal coordinate axes are oriented in the respective extending directions of the short side and the long side, and to perform data processing to determine the position coordinates of the center in the steel plate coordinate system based on the length dimension, the width dimension, the position coordinates of the predetermined point, and the respective vertical distances stored in the storage unit.

7. A crane equipped with a system for determining the position coordinates of the center of a steel plate as described in claim 6.

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