A device for acquiring the rotation angle of a crane's lifting device and a method for acquiring the rotation angle thereof, and a crane

Abstract

The present invention provides a device for acquiring the rotation angle of a crane's lifting device, a method for acquiring the rotation angle of a crane's lifting device, and a crane, which can acquire the rotation angle of the lifting device around the horizontal axis with higher precision. [Solution] The rotation angle acquisition device 1 for the lifting device 11 of the crane 10 comprises a pair of markers 2a and 2b installed on the upper surface 11a of the lifting device 11, a camera device 3 installed on the trolley 13 of the crane 10 to acquire image data D1 of the upper surface 11a, and a calculation device 4. The pair of markers 2a and 2b have different height dimensions. The calculation device 4 has an auxiliary storage unit 8 that stores the difference H of the height dimensions, an input unit 9, and a calculation processing unit 6. The calculation processing unit 6 is configured to perform data processing to acquire the rotation angle based on the difference in the displacement amounts of the pair of markers 2a and 2b obtained from the image data D1 and the difference H of the height dimensions.

Description

Technical Field

[0001] The present invention relates to a rotation angle acquisition device for a crane spreader, a rotation angle acquisition method thereof, and a crane. More specifically, the present invention relates to a rotation angle acquisition device for a crane spreader that can acquire the rotation angle of the crane spreader around the horizontal axis with higher accuracy, a rotation angle acquisition method thereof, and a crane.

Background Art

[0002] A detection device for the swing angle and height of a crane spreader has been proposed, in which a plurality of markers are arranged on the upper surface of the crane spreader with regularity, and the swing angle and height of the spreader are detected by measuring the distance between the plurality of markers projected onto the image projected by the camera (see Patent Document 1). In the detection device proposed in this Patent Document 1, the inclination of the spreader is calculated based on the degree of deformation of the polygonal shape connecting the center points of the plurality of markers (see paragraph 0032 of Patent Document 1).

[0003] However, when the detection device proposed in Patent Document 1 is applied to a crane spreader with a lifting height of about 60 m, the degree of change in the polygonal shape becomes small. For example, when the spreader is inclined by about 1° around the horizontal axis extending in the longitudinal direction, the distance between the markers separated in the short side direction changes by at most about 3 mm. It is not easy to accurately measure this minute change from the image projected by the camera. Therefore, the detection device proposed in Patent Document 1 cannot acquire the rotation angle of the spreader with high accuracy. Therefore, there is room for improvement in acquiring the rotation angle of the crane spreader around the horizontal axis with higher accuracy.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] The object of the present invention is to provide a crane lifting device rotation angle acquisition device and a method for acquiring the rotation angle, as well as a crane, that can acquire the rotation angle of the crane lifting device around the horizontal axis with higher accuracy. [Means for solving the problem]

[0006] The present invention, which achieves the above objective, is a crane lifting device rotation angle acquisition device installed on the trolley of a crane and comprising a camera device that acquires image data of the upper surface of the crane lifting device and a calculation device that acquires the rotation angle of the lifting device around the horizontal axis using the image data, wherein the device is provided with a pair of markers installed on the upper surface, the height dimensions from the upper surface to the upper surface of the pair of markers are different, the calculation device has a storage unit that stores the difference in the height dimensions of the pair of markers, an input unit that receives the image data acquired by the camera device, and a calculation processing unit, and the calculation processing unit is configured to perform data processing to acquire the rotation angle based on the difference in the displacement amount of each of the pair of markers in the rotational circumferential direction of the lifting device around the horizontal axis obtained from the image data and the difference in the height dimensions stored in the storage unit.

[0007] The present invention provides a method for acquiring the rotation angle of a crane lifting device, wherein a camera device installed on the trolley of the crane acquires image data of the upper surface of the lifting device, and a computing device uses the image data to acquire the rotation angle of the lifting device around the horizontal axis, the method comprising an acquisition step for acquiring the rotation angle and a preparation step performed before the acquisition step, wherein in the preparation step, a pair of markers having different height dimensions from the upper surface to the upper surface of the markers are installed on the upper surface, and the difference in height dimensions of the pair of markers is known in advance, and in the acquisition step, the image data is acquired by the camera device, and the acquired image data is processed by the computing device, thereby acquiring the rotation angle based on the difference in the displacement amount of each of the pair of markers in the rotational circumferential direction of the lifting device around the horizontal axis obtained from the image data and the difference in height dimensions known in advance.

[0008] The crane of the present invention is characterized by being equipped with a device for acquiring the rotation angle of the crane's lifting equipment as described above. [Effects of the Invention]

[0009] According to the present invention, by making the height dimensions of a pair of markers different, the amount of displacement of each of the pair of markers in the circumferential direction of rotation can be made to differ significantly when the suspension device rotates around the horizontal axis. That is, the difference in the amount of displacement of each of the pair of markers from a state where the suspension device is not tilted to a state where the suspension device is tilted becomes larger, and this difference in displacement is more clearly reflected in the image data, so that the difference in displacement can be accurately acquired. Then, by using the relationship between the difference in displacement, the difference in height dimensions, and the rotation angle of the suspension device around the horizontal axis, the rotation angle can be acquired with high accuracy. [Brief explanation of the drawing]

[0010] [Figure 1] This is an explanatory diagram illustrating an embodiment of a crane and a device for acquiring the rotation angle of a crane's lifting equipment. [Figure 2] Figure 2 is an explanatory diagram illustrating a crane. [Figure 3] This is an explanatory diagram illustrating image data in an untilted state. [Figure 4] This is an explanatory diagram illustrating image data that is tilted around the horizontal axis. [Figure 5] This is an explanatory diagram illustrating image data that is tilted around a different horizontal axis. [Figure 6] This flowchart illustrates the procedure for obtaining the rotation angle of a crane's lifting device. [Figure 7] This is a schematic diagram illustrating a suspension device and a pair of markers in a front view when not tilted. [Figure 8] This is an explanatory diagram illustrating a suspension device and a pair of markers in a tilted position, viewed from the front. [Figure 9] This is an explanatory diagram illustrating a suspension device and a pair of markers in a side view when not tilted. [Figure 10] This is an explanatory diagram illustrating a suspension device and a pair of markers in a tilted position, viewed from the side. [Modes for carrying out the invention]

[0011] The following describes the crane lifting device and rotation angle acquisition method of the present invention, as well as the crane itself, based on the embodiments shown in the figures.

[0012] The rotation angle acquisition device 1 illustrated in Figures 1 and 2 comprises a pair of markers 2a and 2b, a camera device 3, and a computing device 4. This rotation angle acquisition device 1 is installed on a crane 10. This rotation angle acquisition device 1 is an embodiment of the rotation angle acquisition device for the lifting equipment of a crane according to the present invention, and the crane 10 is an embodiment of the crane according to the present invention.

[0013] In FIGS. 1 and 2, the directions indicated by the X and Y arrows respectively represent the longitudinal direction and the lateral direction of the spreader 11 in a non-inclined state, the direction indicated by the Z arrow represents the vertical direction, and these directions are perpendicular to each other. In the crane 10, the X direction is the traveling direction and the Y direction is the traversing direction. The dashed line in FIG. 1 indicates the horizontal axis Lx extending in the X direction, and the dashed-dotted line indicates the horizontal axis Ly extending in the Y direction. The horizontal axes Lx and Ly are virtual lines defining the rotation axes of the spreader 11. The horizontal axis Lx is located at the center of the spreader 11 in a front view (view in the axial direction of the horizontal axis Lx). The horizontal axis Ly is located at the center of the spreader 与其11 in a side view (view in the axial direction of the horizontal axis Ly). The rotation angle of the spreader 11 around the horizontal axis Lx is defined as the list amount θx, and the rotation angle around the horizontal axis Ly is defined as the trim amount θy.

[0014] Using this rotation angle acquisition device 1, an embodiment of a method for acquiring the rotation angle of the spreader of the crane illustrated in FIG. 5 is implemented. This acquisition method is used to acquire the list amount θx and the trim amount θy. In the procedure of this acquisition method, in the preparation step S100, a pair of markers 2a and 2b are installed on the upper surface of the spreader 11 (S110), and the height dimension difference H and the reference distances L1 and L2 are grasped (S120). In the acquisition step S200, image data D1 is acquired by the camera device 3 (S210). Then, by processing the image data D1 by the arithmetic device 4, the list amount θx and the trim amount θy are acquired (S220, S23).

[0015] First, the details of the crane 10 will be described.

[0016] The crane 10 illustrated in FIG. 2 is a gantry crane for handling the container C at the container terminal. Various known cranes such as gantry cranes, transfer cranes, and ceiling cranes can be used for this crane 10.

[0017] The crane 10 has a spreader 11 to which the container C is connected. This spreader 11 is suspended from a trolley 13 via a wire rope 12. The trolley 13 travels along a girder portion (such as a boom, girt, etc.) 15 supported on the upper part of the leg structure 14. A traveling device 16 is provided at the lower end of the leg structure 14.

[0018] The configuration of the crane 10 can be appropriately changed according to the type of the crane 10. For example, in the case of a ceiling crane, the leg structure 14 is omitted and the traveling device 16 is provided at the lower end of the girder portion 15. Further, when the object to be handled is a steel plate or the like, a lifting magnet, a coil lifter, or the like is used as the spreader 11.

[0019] Next, the rotation angle acquisition device 1 illustrated in FIG. 1 will be described.

[0020] A pair of markers 2a and 2b are installed on the upper surface 11a of the spreader 11 at intervals from each other. The pair of markers 2a and 2b can be installed at any location on the upper surface 11a as long as they are arranged at intervals from each other. Arranging at intervals from each other means that the pair of markers 2a and 2b do not overlap in the Z direction in a top view of the spreader 11.

[0021] The lifting device 11 in this embodiment consists of a spreader 17 to which the container C is connected, and a head block 18 to which the spreader is connected. In other words, the top surface 11a refers to the top surface of the head block 18. In a top view, the head block 18 is smaller than the spreader 17. Various devices such as cable baskets 18a for storing various cables are set on this top surface 11a, and a platform 18b for workers to work on is also formed there. Therefore, the pair of markers 2a and 2b are installed in a location on the top surface of the head block 18 that avoids the cable baskets 18a and the platform 18b, and are installed in such a way that the pair of markers 2a and 2b are always present in the image data D1 acquired by the camera device 3. For the pair of markers 2a and 2b to always be present in the image data D1, it means that no devices such as cable baskets 18a are interposed between the camera device 3 and the pair of markers 2a and 2b. The pair of markers 2a and 2b in this embodiment are installed at a predetermined distance apart on a straight line parallel to the horizontal axis Lx at one end in the Y direction of the upper surface 11a that satisfies these installation conditions.

[0022] The pair of markers 2a and 2b can be arbitrarily selected within a range where their shape, color, and other specifications can be clearly distinguished from the top surface 11a in the image data D1 acquired by the camera device 3, but it is preferable that they be composed of light-emitting bodies. By having the pair of markers 2a and 2b composed of light-emitting bodies, the pair of markers 2a and 2b can be identified even at night. Therefore, this is advantageous for determining the degree of tilt of the lifting device 11 during nighttime cargo handling. An example of a light-emitting body is a beacon that emits a light signal. Depending on the specifications of the crane 10, a pair of beacons may be installed on the top surface 11a of the lifting device 11 for the purpose of acquiring the horizontal displacement and periodic swing angle of the lifting device 11, and the pair of beacons can be used as light-emitting bodies. Therefore, in a crane 10 in which a pair of beacons are installed on the top surface 11a of the lifting device 11, the installed pair of beacons can be used as markers 2a and 2b, which is advantageous in reducing introduction costs. In a crane 10 where a pair of beacons are installed on the upper surface 11a of the lifting device 11, a camera device installed on the trolley 13 measures the light signals emitted from the pair of beacons at a predetermined period (for example, about 50 ms), and the relative horizontal displacement and periodic swing angle between the lifting device 11 and the trolley 13 are obtained based on the measured light signals.

[0023] The pair of markers 2a and 2b have different heights from the top surface 11a to their respective top surfaces. Specifically, marker 2a is directly mounted on the top surface 11a, while marker 2b is mounted on the top surface 11a via the support 5. That is, the difference H between the heights of the pair of markers 2a and 2b (the length from the top surface 11a to the top surfaces of each marker 2a and 2b) can be considered as the height of the support 5 (the length from the bottom end to the top end of the support 5).

[0024] The support 5 is fixed at one end to the upper surface 11a and at the other end to the lower surface of the marker 2b. The height dimension of the support 5 can be set to any value, but it is preferable to set it to any value within a predetermined range from a lower limit to an upper limit.

[0025] More specifically, the lower limit is set based on the resolution of the rotation angle (trim amount θx and list amount θy) acquired by the rotation angle acquisition device 1. Furthermore, this resolution is set based on the minimum value of the horizontal resolution (angle resolution) of the camera device 3 at the desired lifting height of the crane 10 (the vertical travel distance between the upper and lower limits on which the lifting device 11 can be effectively raised and lowered). In other words, the lower limit is set based on the minimum value of the horizontal resolution of the camera device 3 at the desired lifting height of the crane 10. The desired lifting height of the crane 10 is based on the specifications of the crane 10.

[0026] The detection accuracy of the rotation angle acquired by the rotation angle acquisition device 1 should be less than 1°. Assuming a detection error of approximately 10 times, the rotation angle resolution is preferably 0.1° or less, and more preferably 0.05° or less. For the rotation angle resolution to be 0.1° or less, the difference in displacement between a pair of markers 2a and 2b when the rotation angle is displaced by 1° should be 10 times or more the horizontal resolution of the camera device 3 at the desired lifting height. Similarly, for the rotation angle resolution to be 0.05° or less, the difference should be 20 times or more the horizontal resolution of the camera device 3 at the desired lifting height. That is, the lower limit of the difference H is preferably set so that the difference in displacement between a pair of markers 2a and 2b when the rotation angle is displaced by 1° is 10 times or more the horizontal resolution of the camera device 3 at the desired lifting height, and more preferably 20 times or more.

[0027] The upper limit of difference H is based on the maintainability of marker 2b. The larger the difference H, the greater the height dimension of marker 2b, which reduces maintainability. Therefore, the upper limit of difference H is preferably less than 2.0m, and more preferably 1.8m or less, as this can be considered a height that is easy to maintain.

[0028] Camera device 3 is installed on the trolley 13 and acquires image data D1 of the upper surface 11a. Camera device 3 can be any known camera device, such as a monocular camera. Camera device 3 only needs to have a pair of markers 2a and 2b installed on the upper surface 11a in the image data D1 it acquires, and the installation position of the trolley 13 is not particularly limited. The optical axis of the lens of camera device 3 is preferably oriented perpendicular to the upper surface 11a when the suspension device 11 is not rotating, i.e., in the Z direction, but it may also be oriented in a direction tilted from the Z direction.

[0029] The arithmetic unit 4 is composed of a computer, and various data are input and stored, and data processing is performed using this data. Various known computers can be used for the arithmetic unit 4. The arithmetic unit 4 has an arithmetic processing unit (CPU) 6, a main memory unit (memory) 7, an auxiliary storage unit (e.g., HDD) 8, and an input unit 9. The arithmetic unit 4 may be connected to an output unit such as a monitor that displays the results of data processing.

[0030] This computing device 4 may be installed on the crane 10, or it may be installed in a remote location away from the crane 10 (for example, in the control building of a container terminal). In this embodiment, the computing device 4 is installed in the machine room 19 of the crane 10 as illustrated in Figure 2.

[0031] The auxiliary storage unit 8 corresponds to the storage unit of the present invention. The auxiliary storage unit 8 stores the image data D1 acquired by the camera device 3. The auxiliary storage unit 8 also stores the difference H in the height dimensions of a pair of markers 2a and 2b, and the reference distances L1 and L2. The reference distances L1 and L2 will be described later.

[0032] The input unit 9 utilizes various known interfaces, such as wireless communication devices capable of communicating with the camera device 3. Image data D1 acquired by the camera device 3 is input via this input unit 9 and stored in the auxiliary storage unit 8.

[0033] Figure 3 shows image data D1 acquired when the suspension device 11 is not tilted. Figure 4 shows image data D1 acquired when the suspension device 11 is tilted around the horizontal axis Lx. Figure 5 shows image data D1 acquired when the suspension device 11 is tilted around the horizontal axis Ly. These image data D1 are acquired by the camera device 3 and stored in the auxiliary storage unit 8 of the arithmetic unit 4 via the input unit 9. It is desirable that the image data D1 contains the positional relationship of a pair of markers 2a and 2b in a horizontal view. Therefore, if the optical axis of the camera device 3 is tilted with respect to the Z direction, the arithmetic unit 4 corrects the image data acquired by the camera device 3 according to the tilt of the optical axis so that image data D1 containing the positional relationship of a pair of markers 2a and 2b in a horizontal view is stored in the auxiliary storage unit 8.

[0034] In Figure 3, L1 represents the reference distance, which is the distance between a pair of markers 2a and 2b in the Y direction when the suspension device 11 is not tilted, and L2 represents the reference distance, which is the distance between a pair of markers 2a and 2b in the X direction. As illustrated in Figure 3, the reference distance L1 can be considered zero. It can be considered zero if the line segment connecting the centers of the pair of markers 2a and 2b in a horizontal view can be considered to be approximately parallel to the horizontal axis Lx, and the angle between that line segment and the horizontal axis Lx in a horizontal view is preferably less than 1°, more preferably less than 0.5°.

[0035] In Figure 4, L3 represents the distance between the pair of markers 2a and 2b in the Y direction when the suspension device 11 is tilted around the horizontal axis Lx. Regarding the tilt around the horizontal axis Lx in Figure 4, when viewing the suspension device 11 from left to right, counterclockwise rotation around the horizontal axis Lx is considered positive, and clockwise rotation is considered negative. Furthermore, if the distance between markers L3 is smaller than the reference distance L1, the difference in displacement between the pair of markers 2a and 2b in the Y direction is negative; if it is larger than the reference distance L1, the difference in displacement is positive. Therefore, in the image data D1 of Figure 4, the suspension device 11 is tilted counterclockwise around the horizontal axis Lx, and the distance between markers L3 is smaller than the reference distance L1, resulting in a negative difference in displacement between the pair of markers 2a and 2b in the Y direction.

[0036] In Figure 5, L4 represents the distance between the pair of markers 2a and 2b in the X direction when the suspension device 11 is tilted around the horizontal axis Ly. In Figure 5, the tilt around the horizontal axis Ly is considered positive when viewing the suspension device 11 from bottom to top, with counter-clockwise rotation around the horizontal axis Ly as the axis, and negative when clockwise rotation. Furthermore, if the distance between markers L4 is smaller than the reference distance L2, the difference in displacement between the pair of markers 2a and 2b in the X direction is negative; if it is larger than the reference distance L2, the difference in displacement is positive. Therefore, in the image data D1 of Figure 5, the suspension device 11 is tilted counter-clockwise around the horizontal axis Ly, and the distance between markers L4 is smaller than the reference distance L2, resulting in a negative difference in displacement between the pair of markers 2a and 2b in the X direction.

[0037] In the image data D1 of Figures 4 and 5, the shape of the suspension device 11 is deformed compared to the image data D1 of Figure 3. For example, the length of the suspension device 11 in the short direction in Figure 4 is shorter than the length of the suspension device 11 in the short direction in Figure 3. Also, the length of the suspension device 11 in the long direction in Figure 5 is shorter than the length of the suspension device 11 in the long direction in Figure 3. The pair of markers 2a and 2b have different height dimensions, so the amount of displacement of each in the direction in which the suspension device 11 rotates is different. Specifically, since the height dimension of marker 2b is larger than the height dimension of marker 2a, the amount of displacement of marker 2b is larger than the amount of displacement of marker 2a, and the difference in the amount of displacement of each is clearly shown in the image data D1.

[0038] Next, the procedure for obtaining the rotation angle of the crane lifting device, as illustrated in Figure 6, will be described in detail. In this procedure, the preparation process S100 and the acquisition process S200 are carried out in order. The preparation process S100 (steps S110 and S120) and the acquisition process S200 (steps S210 to S230) will be described in detail below.

[0039] In step S110, a pair of markers 2a and 2b are installed on the upper surface 11a of the suspension device 11. If an existing pair of markers is to be used as the pair of markers 2a and 2b, in step S110, a support 5 can be interposed between one of the existing markers and the upper surface 11a to make the height dimensions of the existing pair of markers different. An example of an existing pair of markers is a pair of beacons that emit light.

[0040] In step S120, the difference in height dimension H, and the reference distances L1 and L2 are determined. The determined difference in height dimension H, and the reference distances L1 and L2 are stored in the auxiliary storage unit 8 of the calculation unit 4. The difference in height dimension H may be a value measured after placing a pair of markers 2a and 2b on the upper surface 11a, but the height dimension of the support 5 is used as is. Similarly, the reference distances L1 and L2 may be values ​​measured using the image data D1 exemplified in Figure 3 when the suspension device 11 is not rotating, but the design values ​​from the design stage are used.

[0041] Once installed, the pair of markers 2a and 2b can be used as is. Also, the height difference H and reference distances L1 and L2, once determined, can be used any number of times as long as their respective values ​​do not change. Therefore, the installation of the pair of markers 2a and 2b (S110) and the determination of the height difference H and reference distances L1 and L2 (S120) do not need to be repeated each time the acquisition process S200 is performed, so the preparation process S100 can be omitted.

[0042] Furthermore, for cranes 10 that can be considered to have roughly the same specifications, it is preferable to make the difference in height dimension H and the reference distances L1 and L2 the same. This way, if step S120, in which the difference in height dimension H and the reference distances L1 and L2 are determined, is performed for one crane among the cranes 10 with the same specifications, then step S120 can be omitted for the other cranes. The degree to which they can be considered to have the same specifications is such that the lifting height of the cranes 10 and the condition of the top surface 11a (area when viewed from above, installation status of each device, etc.) can be considered to be roughly the same.

[0043] In step S210, the camera device 3 acquires image data D1 of the upper surface 11a of the suspension device 11. The acquired image data D1 is stored in the auxiliary storage unit 8 of the arithmetic unit 4. The acquisition period of image data D1 by the camera device 3 can be arbitrarily selected. A shorter acquisition period is advantageous for more detailed understanding of the tilt of the suspension device 11. This acquisition period is, for example, about 50 ms.

[0044] In step S220, the arithmetic unit 4 performs data processing to acquire the marker distances L3 and L4 in the image data D1. The acquired marker distances L3 and L4 are stored in the auxiliary storage unit 8 of the arithmetic unit 4. Known image dimension measurement methods can be used for this data processing. For example, the marker distance L3 is calculated by multiplying the horizontal pixel resolution of the camera device 3 (pixel field of view / number of pixels in the vertical direction of the image data D1) by the number of pixels between a pair of markers 2a and 2b in the Y direction. Similarly, the marker distance L4 is also calculated by multiplying the horizontal pixel resolution of the camera device 3 (pixel field of view / number of pixels in the left-right direction of the image data D1) by the number of pixels between a pair of markers 2a and 2b in the X direction.

[0045] In step S230, data processing is performed by the arithmetic unit 4 to obtain the list amount θx and the trim amount θy. Specifically, the arithmetic unit 4 calculates the list amount θx and the trim amount θy using the following formula (1) based on the difference in displacement and the difference in height dimension H. The following formula (1) is pre-stored in the auxiliary storage unit 8 of the arithmetic unit 4. In the following formula (1), lab represents the distance between markers, Lab represents the reference distance, and θ represents the rotation angle. When obtaining the list amount θx, the distance between markers L3 is input to lab, the reference distance L1 is input to Lab, and the list amount θx is input to θ. Similarly, when obtaining the trim amount θy, the distance between markers L4 is input to lab, the reference distance L2 is input to Lab, and the trim amount θy is input to θ.

[0046]

number

[0047] When counterclockwise rotation around the horizontal axis is considered positive, the cosine of the angle obtained by adding the rotation angle θ and 90° represents the ratio of the difference in displacement between a pair of markers 2a and 2b in the horizontal direction perpendicular to the horizontal axis to the difference in height dimension H. The difference in displacement is the difference between the distance between markers lab and the virtual distance between markers (Lab × cosθ). This virtual distance between markers is based on the reference distance Lab and the rotation angle θ, and represents the distance between markers assuming that the difference in height dimension H in the state in which image data D1 was acquired is zero.

[0048] Figures 7 and 8 schematically represent the suspension device 11 and the pair of markers 2a and 2b in an axial view along the horizontal axis Lx, while Figures 9 and 10 schematically represent the suspension device 11 and the pair of markers 2a and 2b in an axial view along the horizontal axis Ly. Furthermore, Figures 7 and 9 schematically represent the suspension device 11 in an untilted state, Figure 8 schematically represents the suspension device 11 tilted around the horizontal axis Lx, and Figure 10 schematically represents the suspension device 11 tilted around the horizontal axis Ly.

[0049] As illustrated in Figures 7 and 8, the reference distance L1 is zero. That is, the difference in displacement between a pair of markers 2a and 2b in the horizontal direction (Y direction) perpendicular to the horizontal axis Lx is the distance between markers L3. Therefore, the list quantity θx is calculated using the above formula (1), where the distance between markers L3 = {difference in height dimension H × (-sinθx)}.

[0050] As illustrated in Figures 9 and 10, the difference in displacement between a pair of markers 2a and 2b in the horizontal direction (X direction) perpendicular to the horizontal axis Ly is the difference between the distance between markers L4 and the virtual distance between markers {reference distance L2 × cosθy}. Therefore, the trim amount θy is calculated using the above formula (1): distance between markers L4 = [virtual distance between markers (reference distance L2 × cosθy) + {difference in height dimension H × (-sinθy)}].

[0051] As described above, according to this embodiment, by making the height dimensions of the pair of markers 2a and 2b different, when the suspension device 11 is tilted around the horizontal axis, the amount of displacement of the pair of markers 2a and 2b in the rotational direction of the tilt can be made to differ significantly. That is, the difference in the amount of displacement of the pair of markers 2a and 2b from the state in which the suspension device 11 is not tilted to the state in which the suspension device 11 is tilted (for example, the difference between the distance between markers L3, the distance between markers L4 and the distance between virtual markers) becomes larger, and the difference in the amount of displacement appears more prominently in the image data D1, so that the difference in the amount of displacement can be accurately obtained. Furthermore, since the relationship between the difference in the amount of displacement, the difference in height dimension H, and the rotation angle of the suspension device 11 around the horizontal axis can be expressed using trigonometric functions, the rotation angle can be obtained with high accuracy.

[0052] This embodiment involves installing a pair of markers 2a and 2b with different heights on the upper surface 11a, allowing for the acquisition of both the list amount θx and trim amount θy rotation angles of the suspension device 11. In other words, the area required for installing the pair of markers 2a and 2b is minimized, increasing the degree of freedom in installation, and thus enabling adaptation to various conditions on the upper surface 11a (size of the upper surface 11a, installation status of devices on the upper surface 11a, etc.).

[0053] Furthermore, according to this embodiment, by making the height dimensions of a pair of markers 2a and 2b different, the rotation direction (clockwise or counterclockwise) of the list amount θx and trim amount θy can be determined. The distance between markers lab includes the difference in the displacement of the pair of markers 2a and 2b due to the rotation of the suspension device 11. Therefore, the rotation direction of the suspension device 11 can be determined by comparing the distance between markers lab with the reference distance Lab. As illustrated in Figures 7 and 8, if a positive list amount θx is considered counterclockwise and a negative list amount θx is considered clockwise, then when the distance between markers L3 is smaller than the reference distance L1, it is counterclockwise, and when the distance between markers L3 is larger than the reference distance L1, it is clockwise. As illustrated in Figures 9 and 10, if a positive trim amount θy is considered counterclockwise and a negative trim amount θy is considered clockwise, then when the distance between markers L4 is smaller than the reference distance L2, it is counterclockwise, and when the distance between markers L4 is larger than the reference distance L2, it is clockwise.

[0054] Instead of the above formula (1), the following formula (2) may be used. In the following formula (2), α represents the angle with respect to the horizontal plane of the line segment connecting the pair of markers 2a and 2b in the axial view of the horizontal axis when the suspension device 11 is not tilted. When obtaining the list amount θx, the distance between markers L3 is input to lab, the reference distance L1 is input to Lab, the list amount θx is input to θ, and the reference angle α1 is input to α. Similarly, when obtaining the trim amount θy, the distance between markers L4 is input to lab, the reference distance L2 is input to Lab, the trim amount θy is input to θ, and the reference angle α2 is input to α. The reference angle α is a value calculated by tanα = (difference in height dimension H / reference distance). The reference angle α may be stored in advance in the auxiliary storage unit 8, or it may be calculated as appropriate based on the difference in height dimension H and the reference distance Lab.

[0055]

number

[0056] The marker-to-marker distance lab, which includes the difference in displacement between a pair of markers 2a and 2b, is equal to the second virtual marker-to-marker distance. The second virtual marker-to-marker distance is based on a reference distance Lab, a difference in height H, a rotation angle θ, and a reference angle α. This second virtual marker-to-marker distance represents the horizontal length perpendicular to the horizontal axis of the line segment connecting the pair of markers 2a and 2b in the state in which the image data D1 was acquired, assuming that the line segment is viewed in a horizontal plane.

[0057] As illustrated in Figures 7 and 8, the reference distance L1 is zero and the reference angle α1 is 90°. Therefore, the list quantity θx can be calculated using the distance between markers L3 = {difference in height dimension H × (-sinθx)} based on the above formula (2).

[0058] As illustrated in Figures 9 and 10, the distance between the second virtual markers is the extension length of the line segment connecting the centers of the upper surfaces of the pair of markers 2a and 2b {(difference in height dimension H)}. 2 +(Reference distance L2) 2} 1 / 2 This can be expressed as the cosine of the angle obtained by adding the reference angle α2 and the trim amount θy. Therefore, the trim amount θy can be calculated using the above formula (2), where L4 = {extended length of the line segment × cos(θy + α2)}.

[0059] The embodiments described above can also be applied to configurations that acquire only one of the rotation angles, either the list amount θx or the trim amount θy. Furthermore, other markers besides the pair of markers 2a and 2b can be installed. For example, another marker may be installed on the upper surface 11a without the support 5, similar to marker 2a, and form a pair with marker 2b. This pair of markers 2b and the other marker are installed at a predetermined distance apart on a straight line parallel to the horizontal axis Ly, at one end of the upper surface 11a in the X direction that satisfies the installation conditions. In this configuration, the pair of markers 2a and 2b are used to acquire the list amount θx, and the pair of markers 2b and the other marker are used to acquire the trim amount θy.

[0060] If the reference distance Lab is zero, it is not necessary to pre-store the reference distance Lab in the auxiliary storage unit 8. For example, if the reference distance L1 is zero, the list quantity θx is calculated using the distance between markers L3 = {difference in height dimension H × (-sinθx)}. Therefore, if this formula is pre-stored in the auxiliary storage unit 8, the step of determining the reference distance L1 can be omitted. [Examples]

[0061] Tables 1 and 2 below show the distance L4 between markers for each trim amount θy in a crane 10 equipped with the rotation angle acquisition device 1 illustrated in Figures 1 and 2 above. The reference distance L2 was set to 2.1m. The lifting height of the crane 10 was set to 60m, and the horizontal resolution of the camera device 3 was set to 1mm. The difference H in height dimensions between the pair of markers 2a and 2b was set to 1.5m.

[0062] [Table 1]

[0063] [Table 2]

[0064] Generally, when container C is loaded or unloaded by crane 10, the trim amount θy of the lifting device 11 is within ±5°. Within this range, Tables 1 and 2 show that when the lifting device 11 rotates about 1° around the horizontal axis Ly, the distance L4 between markers changes by at least 23 mm. Also, when the trim amount θy is displaced within ±5°, the change in the distance L4 between markers per 1° of trim amount θy is approximately ±26.2 mm / deg. Therefore, the detection resolution of the trim amount θy, calculated by {horizontal resolution of camera device 3 / change in the distance L4 between markers per 1° of trim amount θy}, is approximately ±0.01°. If the detection error is multiplied by 10, the detection accuracy of the trim amount θy is approximately ±0.1°, which is high accuracy.

[0065] Although embodiments of the present invention have been described above, the crane lifting device rotation angle acquisition device and rotation angle acquisition method, as well as the crane itself, 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]

[0066] 1. Rotation Angle Acquisition Device 2a, 2b markers 3 Camera device 4 Arithmetic unit 5 Support 6. Processing Unit 7 Main memory 8 Auxiliary storage 10 Cranes 11 Hanging equipment 11a Top side 12 Wire ropes 13 Trolley 14 leg structure 15 digits 16. Running gear 17 Spreader 18 Headblock 18a Cable cage 18b Landing 19 Machine room C Container D1 Image Data Lx, Ly horizontal axis H Difference in height dimension L1, L2 reference distance Distance between L3 and L4 markers List quantity θx Trim amount θy

Claims

1. A crane lifting device rotation angle acquisition device is installed on the trolley of a crane and comprises a camera device that acquires image data of the upper surface of the crane's lifting device, and a calculation device that acquires the rotation angle of the lifting device around the horizontal axis using the image data, It is equipped with a pair of markers installed on the upper surface, and the height dimensions from the upper surface to the upper surface of the markers are different for each pair. The calculation device includes a storage unit that stores the difference in height dimensions of the pair of markers, an input unit that receives the image data acquired by the camera device, and a calculation processing unit. A crane lifting device rotation angle acquisition device, wherein the calculation processing unit is configured to perform data processing to acquire the rotation angle based on the difference in the displacement amounts of each of the pair of markers in the rotational circumferential direction of the lifting device around the horizontal axis obtained from the image data and the difference in the height dimension stored in the storage unit.

2. The distance between the pair of markers in the horizontal direction perpendicular to the horizontal axis is defined as the distance between markers. The storage unit stores the distance between the markers when the suspension device is not tilted as a reference distance. The aforementioned processing unit is configured to perform data processing to acquire the distance between markers based on the image data, and data processing to acquire the rotation angle by considering the difference between the acquired distance between markers and the virtual distance between markers as the difference in displacement. The rotation angle acquisition device for a crane lifting device according to claim 1, wherein the virtual distance between markers is based on the reference distance and the rotation angle, and represents the distance between markers assuming that the difference in height dimension in the state in which the image data is acquired is zero.

3. The distance between the pair of markers in the horizontal direction perpendicular to the horizontal axis is defined as the distance between markers. The storage unit stores the distance between the markers when the suspension device is not rotating as a reference distance. The aforementioned arithmetic processing unit is configured to perform data processing to obtain the distance between markers based on the image data, and to perform data processing to obtain the rotation angle, assuming that the obtained distance between markers includes the difference in the displacement amount and that the distance between markers is equal to the second virtual distance between markers. The rotation angle acquisition device for a crane lifting device according to claim 1, wherein the second virtual marker distance is based on the angle derived from the reference distance and the height dimension, the difference between the reference distance and the height dimension, the rotation angle and the reference angle, and represents the horizontal length of the line segment perpendicular to the horizontal axis, assuming that the line segment connecting the pair of markers in the state in which the image data has been acquired is viewed in a horizontal plane.

4. The device for acquiring the rotation angle of a crane lifting device according to claim 1, wherein, when the shape of the lifting device in a top view can be considered as a rectangle, the horizontal axis is defined as a horizontal axis whose axial direction is oriented in the longitudinal direction of the rectangle and a horizontal axis whose axial direction is oriented in the short direction of the rectangle, and the rotation angle is obtained as the rotation angle of the horizontal axis in the longitudinal direction and the rotation angle of the horizontal axis in the short direction.

5. The rotation angle acquisition device for a crane lifting device according to claim 4, wherein the pair of markers are installed spaced apart from each other on a straight line parallel to the longitudinal direction.

6. The device for acquiring the rotation angle of a crane's lifting device according to any one of claims 1 to 5, wherein the marker is a light-emitting body.

7. The device for acquiring the rotation angle of a crane's lifting device according to claim 6, wherein the light-emitting element is a beacon.

8. The rotation angle acquisition device for a crane lifting device according to any one of claims 1 to 5, wherein the difference in the height dimension is set based on the horizontal resolution of the camera device and the lifting height of the crane.

9. In a method for acquiring the rotation angle of a crane's lifting device, in which a camera device installed on the crane's trolley acquires image data of the upper surface of the lifting device, and a computing device uses the image data to acquire the rotation angle of the lifting device around its horizontal axis, The process includes an acquisition step for acquiring the rotation angle and a preparation step performed prior to this acquisition step. In the preparation step, a pair of markers with different height dimensions from the top surface to the top surface of each marker are placed on the top surface, and the difference in height dimensions of the pair of markers is known in advance. A method for acquiring the rotation angle of a crane's lifting device, wherein the acquisition step involves acquiring the image data with the camera device, and processing the acquired image data with the computing device to acquire the rotation angle based on the difference in the displacement amounts of each of the pair of markers in the rotational circumferential direction of the lifting device around the horizontal axis obtained from the image data, and the difference in the height dimension which has been determined in advance.

10. A crane equipped with a device for acquiring the rotation angle of a crane's lifting device according to any one of claims 1 to 5.

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