Position identification system, position identification device, and position identification method

Abstract

A position identification system (50) comprises: a position information detector (53); and a controller (52) that identifies the position of a turning axis (AX) of an upper turning body (2) of a work machine (100) by using turning-time information which is information acquired by the position information detector (53) when the upper turning body (2) turns. The turning-time information includes specific part position information which is information regarding the positions of specific parts (5, 60) of the work machine (100), which rotate about the turning axis (AX) along with the turning of the upper turning body (2).

Description

Location determination system, location determination device, and location determination method

[0001] The present disclosure relates to a location system, a location device, and a location method.

[0002] Patent Document 1 discloses a work machine equipped with a position measurement system. The technology described in Patent Document 1 measures the absolute position in three-dimensional space of a monitor point set on the work device using a global navigation satellite system (GNSS).

[0003] Patent Document 2 discloses a position detection system for a tunnel boring machine that cuts the face of a tunnel using an automatic cross-section boring machine. The technology described in Patent Document 2 identifies the coordinates of the work machine by using the automatic tracking function of a total station.

[0004] The technology described in Patent Document 1 has a problem in that the accuracy of position measurement can be reduced depending on the conditions of the area in which the technology is used, resulting in limited use scenarios and poor versatility. Specifically, for example, in technology using GNSS, the accuracy of position measurement can be reduced depending on the positioning conditions of navigation satellites. Furthermore, the accuracy of position measurement can also be reduced by interference between the communication (frequency) between the fixed station and the radio of the work machine with other wireless communications. Furthermore, the accuracy of position measurement can also be reduced in areas such as inside tunnels, near high-voltage power lines, in mountain valleys, and near large buildings.

[0005] Furthermore, total station equipment with an automatic tracking function, such as that described in Patent Document 2, is expensive, so there is a problem that the situations in which it can be used are limited and it lacks versatility.

[0006] JP 2020-139933 A JP 2002-161696 A

[0007] An object of the present disclosure is to provide a highly versatile position identification system, position identification device, and position identification method that can identify the position of a work machine.

[0008] The position identification system provided by the present disclosure comprises a position information detector and a controller that identifies the position of the rotation axis of the upper rotating body using rotation time information, which is information acquired by the position information detector when the upper rotating body of the work machine rotates, and the rotation time information includes specific part position information, which is information regarding the position of a specific part of the work machine that rotates around the rotation axis as the upper rotating body rotates.

[0009] FIG. 1 is a perspective view showing an example of a working device. FIG. 2 is a schematic diagram showing a positioning system according to a first embodiment. FIG. 3 is a flowchart showing an example of calculation processing performed by a controller of the positioning system according to the first embodiment. FIG. 4 is a schematic diagram showing an example of three-dimensional position information acquired by a position information detector of the positioning system according to the first embodiment. FIG. 5 is a schematic diagram showing an example of specific part position information selected from three-dimensional position information as turning time information acquired by the position information detector in the first embodiment. FIG. 6 is a diagram showing a plane specified using the specific part position information in the first embodiment. FIG. 7 is a diagram showing a part of a circle specified using the specific part position information, and the position of a turning axis specified using the plane and the circle in the first embodiment. FIG. 8 is a schematic diagram showing a positioning system according to a modified example of the first embodiment. FIG. 9 is a schematic diagram showing a positioning system according to a second embodiment. FIG. 10 is a flowchart showing an example of calculation processing performed by a controller of the positioning system according to the second embodiment. FIG. 11 is a schematic diagram showing three-dimensional position information as turning time information acquired by a position information detector of the positioning system in the second embodiment. FIG. 12 is a flowchart showing an example of calculation processing performed by a controller of the positioning system according to Modification 1 of the second embodiment. FIG. 13 is a schematic diagram showing a positioning system according to Modification 2 of the second embodiment.

[0010] An embodiment of the present disclosure will be described with reference to the drawings. Fig. 1 is a perspective view showing an example of a work machine 100. The work machine 100 shown in Fig. 1 is a hydraulic excavator, but the work machine in the present disclosure is not limited to hydraulic excavators and may be other work machines such as a crane or a bulldozer.

[0011] The work machine 100 includes a lower traveling body 1, an upper rotating body 2, and a working device 3. The lower traveling body 1 has a traveling device including crawlers. However, the lower traveling body 1 may have a traveling device including tires (not shown) instead of crawlers.

[0012] The upper rotating body 2 is supported by the undercarriage 1 so as to be able to rotate relative to the undercarriage 1 about a rotation axis AX extending vertically. The upper rotating body 2 has a rotating frame 2a supported by the undercarriage 1, a cab 11 disposed on the rotating frame 2a, and a counterweight 12. The upper rotating body 2 has an outer surface 13 including a right side surface, a left side surface, a top surface, and a rear surface.

[0013] The working device 3 is supported on the upper rotating body 2 so that it can be raised and lowered. The working device 3 includes a boom 4, an arm 5 rotatably attached to the tip of the boom 4, and a tip attachment 6 rotatably attached to the tip of the arm 5. The tip attachment 6 shown in Fig. 1 is a bucket, but it may also be a gripping device such as a grapple or fork, a crusher, a lifting magnet, or another tip attachment.

[0014] The work machine 100 is equipped with a plurality of actuators. The plurality of actuators include a boom cylinder 7, an arm cylinder 8, a tip attachment cylinder 9, a swing motor 10, and left and right travel motors 14.

[0015] The boom 4 performs a hoisting operation to raise and lower the boom 4 relative to the upper rotating body 2 in accordance with the extension and contraction of the boom cylinder 7. Specifically, when the boom cylinder 7 contracts, the boom 4 performs a boom-down operation in which the tip of the boom 4 approaches the ground. When the boom cylinder 7 extends, the boom 4 performs a boom-up operation in which the tip of the boom 4 moves away from the ground.

[0016] The arm 5 performs a rotational movement relative to the boom 4 in accordance with the extension and retraction movement of the arm cylinder 8. Specifically, when the arm cylinder 8 retracts, the arm 5 performs an arm-pushing movement in which the tip of the arm 5 moves away from the boom 4. When the arm cylinder 8 extends, the arm 5 performs an arm-pulling movement in which the tip of the arm 5 moves toward the boom 4.

[0017] The tip attachment 6 rotates relative to the arm 5 in accordance with the extension and contraction of the tip attachment cylinder 9. The upper rotating body 2 rotates (right or left) relative to the lower traveling body 1 in accordance with the operation of the swing motor 10. The lower traveling body 1 travels in accordance with the operation of the left and right traveling motors 14.

[0018] [Positioning System] Fig. 2 is a schematic diagram showing a positioning system 50 according to the first embodiment, and Fig. 9 is a schematic diagram showing a positioning system 50 according to the second embodiment. First, common features of the positioning system 50 according to the first embodiment and the positioning system 50 according to the second embodiment will be described.

[0019] Each of the position specifying system 50 according to the first embodiment and the position specifying system 50 according to the second embodiment includes a position specifying device 51, a position information detector 53, and a display 54. The position specifying device 51 includes a controller 52. In the position specifying system 50, the display 54 is not an essential component and can be omitted.

[0020] The position information detector 53 is configured to acquire swing time information when the upper rotating body 2 of the work machine 100 swings. The swing time information includes specific part position information, which is information regarding the position of a specific part of the work machine 100 that rotates about the swing axis AX as the upper rotating body 2 swings. In the first embodiment, the specific part is the mark 60, and in the second embodiment, the specific part is the arm 5. The position information detector 53 inputs the detection results to the controller 52. The controller 52 identifies the position of the swing axis AX using the swing time information acquired by the position information detector 53 when the upper rotating body 2 swings. The controller 52 has a computer including an arithmetic processing unit and a memory. The controller 52 performs various arithmetic processing, including identifying the position of the swing axis AX, by the arithmetic processing unit executing a control program stored in the memory. The display 54 may, for example, display the identified position of the swing axis AX or information related thereto.

[0021] Generally, a work machine equipped with a rotating upper body, i.e., a slewing work machine, always has a rotating axis, and since this rotating axis is located at a fixed central position on the work machine, it can be a representative part when indicating the position of the work machine. In each of the first and second embodiments, the controller 52 can identify the position of the rotating axis AX using rotation information acquired by the position information detector 53 when the upper body 2 rotates. Specifically, the specific part is a part that rotates around the rotating axis AX, which is common to the upper body 2, as the upper body 2 rotates, and moves along a fixed annular orbit (circular orbit T1 in FIG. 2 and cylindrical orbit T2 in FIG. 9) centered on the rotating axis AX during rotation. Therefore, the specific part position information included in the rotation time information acquired by the position information detector 53 when the upper rotating body 2 rotates includes information on the position of the specific part that rotates around the rotation axis AX as the upper rotating body 2 rotates, i.e., information on the annular orbit (circular orbit T1 or cylindrical orbit T2) that the specific part traces when the upper rotating body 2 rotates, and the rotation axis AX is located at the center of the annular orbit (circular orbit T1 or cylindrical orbit T2). Therefore, the controller 52 can identify the position of the rotation axis AX using the rotation time information including the specific part position information.

[0022] The position information detector 53 is disposed in a position such that the detection target, including the specific portion, is included in its detection range (field of view range). Specifically, as shown in Figures 2 and 9, for example, the position information detector 53 is disposed at the work site at a certain distance from the work machine 100 so that the entire or almost entire work machine 100 is included in the detection range. However, the position information detector 53 need only be disposed so that at least the mark 60 (specific portion) is included in the detection target when the upper rotating body 2 rotates, and therefore it is not necessarily disposed so that the entire work machine 100 is included in the detection range.

[0023] In each of the first and second embodiments, the position information detector 53 does not need to be a large-scale position measurement system such as a GNSS or total station, but may be, for example, a simple detector that can detect the position information of a detection target including the specific part at the work site where the work machine 100 is located.

[0024] Specifically, the position information detector 53 may be, for example, a three-dimensional position information detector that detects three-dimensional information of a detection target at a work site. The three-dimensional position information detector may be, for example, a three-dimensional camera that can detect two-dimensional information (vertical and horizontal) about the detection target and depth information about the detection target. The three-dimensional camera may be a stereoscopic three-dimensional camera (stereo camera), a TOF (Time of Flight) three-dimensional camera, or a three-dimensional camera that combines a projector and a camera. The TOF three-dimensional camera may be, for example, a LiDAR (Light Detection and Ranging) camera. The position information detector 53 may be a millimeter-wave radar or an ultrasonic sensor. However, the position information detector 53 is not limited to the above specific examples as long as it is capable of detecting three-dimensional information about a detection target at a work site. Furthermore, the position information detector 53 may be a combination of two or more of the above specific examples of three-dimensional position information detectors. However, the position information detector is not limited to these specific examples.

[0025] The turning information is three-dimensional position information acquired by the position information detector 53 and includes three-dimensional position information of the detection target including the specific part. The controller 52 selects the specific part position information from the three-dimensional position information and identifies the position of the turning axis AX using the selected specific part position information. In each of the first and second embodiments, even if the three-dimensional position information detected by the position information detector 53 includes not only the specific part position information, which is information about the position of the specific part included in the detection target, but also information other than the specific part position information, i.e., information about the positions of other parts included in the detection target, the controller 52 can select the specific part position information from the three-dimensional position information and identify the position of the turning axis AX using the selected specific part position information.

[0026] The above features are common to the first and second embodiments. The features of the first and second embodiments will be described below individually.

[0027] [First embodiment] In the first embodiment shown in Fig. 2, the specific portion is configured by a mark 60 attached to the upper rotating body 2. In the specific example shown in Fig. 2, the mark 60 is attached to the outer surface 13 of the upper rotating body 2. More specifically, the mark 60 is attached to the back surface of the upper rotating body 2, on the outer surface 13.

[0028] The mark 60 includes a reflective material. This reflective material is made of a material that reflects light such as laser light more easily than the outer surface 13 of the upper rotating body 2. The reflective material may be, for example, a retroreflective material or another reflective material.

[0029] The controller 52 uses the specific part position information to identify a circle or a portion of a circle corresponding to the trajectory of the mark 60 when the upper rotating body 2 rotates, and identifies the position of the center of the identified circle as the position of the rotation axis AX. If the mark 60 moves along a constant circular path T1 centered on the rotation axis AX when the upper rotating body 2 rotates, the trajectory of the mark 60 when the upper rotating body 2 rotates will be a circle or an arc shape centered on the rotation axis AX, and therefore the specific part position information includes information on the trajectory of the circular or arc-shaped mark 60. Therefore, the controller 52 can use the specific part position information to identify a circle or a portion of a circle (arc) corresponding to the trajectory of the mark 60, and can identify the position of the center of the identified circle as the position of the rotation axis AX.

[0030] The controller 52 identifies the relative position of the work machine 100 with respect to the ground surface GR on which the undercarriage 1 of the work machine 100 is placed, based on the relative position information, which is information relating to the relative position of the mark 60 with respect to the upper rotating body 2, and the position of the swing axis AX. The relative position of the work machine 100 may be, for example, the position of the intersection P1 between an extension of the swing axis AX and the ground surface GR, or the position of a portion whose relative position with respect to the swing axis AX has been identified in advance.

[0031] The following description will be given taking as an example a case where the position information detector 53 is LiDAR. In this case, the three-dimensional position information includes point cloud data related to the upper rotating body 2, the boom 4, the arm 5, and the mark 60 (specific portion) when the upper rotating body 2 is rotating. LiDAR can irradiate a detection target with laser light and measure the distance to the detection target, the shape of the detection target, etc. based on information about the reflected light.

[0032] FIG. 3 is a flowchart showing an example of a calculation process performed by the controller 52 of the position specifying system 50 according to the first embodiment.

[0033] 3, the controller 52 causes the upper rotating body 2 to start a swing operation (step S1). The controller 52 may control hydraulic equipment including a hydraulic pump and a control valve so that the upper rotating body 2 performs a swing operation in response to an operation of an operating lever by an operator. Alternatively, the controller 52 may control the hydraulic equipment so that the upper rotating body 2 performs a swing operation even if the operator does not operate the operating lever.

[0034] The position information detector 53 acquires point cloud data, which is three-dimensional position information of the detection target while the upper rotating body 2 is rotating, and the controller 52 records the point cloud data input from the position information detector 53 (step S2). FIG. 4 is a schematic diagram showing an example of three-dimensional position information (point cloud data) acquired by the position information detector 53. The point cloud data shown in FIG. 4 is point cloud data of the detection target at a certain point in time while the upper rotating body 2 is rotating. As shown in FIG. 4, the difference between the reflected light from the mark 60 (specific portion) containing a reflective material and the reflected light from the outer surface 13 of the upper rotating body 2, the boom 4, and the arm 5 (portions other than the mark 60) is clearly evident in the point cloud data shown in FIG.

[0035] The controller 52 selects the point cloud data of the mark 60 (specific portion) from all the point cloud data by filtering by reflectance (step S3). Since the mark 60 includes a reflective material, the difference between the specific portion position information (point cloud data of the mark 60) and information other than the specific portion position information (point cloud data of portions other than the mark 60, such as the outer surface 13 of the upper rotating body 2, the boom 4, and the arm 5) becomes clear in the rotation time information acquired by the position information detector 53. In other words, the reflectance of the mark 60 is higher than the reflectance of portions other than the mark 60, so the controller 52 can easily select the specific portion position information from the rotation time information (the three-dimensional position information).

[0036] The threshold value for filtering based on reflectance may be a value that is preset in the controller 52, or may be manually specified by the operator while checking the point cloud data displayed on the display 54, for example.

[0037] The controller 52 may also perform filtering, for example, as follows. That is, the controller 52 may divide the three-dimensional coordinates into grids so that the three-dimensional coordinates are partitioned into predetermined sizes, and calculate the average reflectance of the point cloud included in each grid. In this case, the controller 52 may compare the average reflectance of each grid with a predetermined threshold, extract grids whose average reflectance exceeds the predetermined threshold from among the multiple grids, and identify the extracted grids as data of the landmark 60. The predetermined threshold may be, for example, the average value of the reflectances of all the point cloud data plus a predetermined value. The predetermined value may be, for example, twice the standard deviation calculated using the reflectances of all the point cloud data.

[0038] FIG. 5 is a schematic diagram showing an example of specific portion position information selected from the three-dimensional position information. As shown in FIG. 5 , the specific portion position information acquired and selected during the rotation of the upper rotating body 2, i.e., the point cloud data of the marker 60, includes information regarding the trajectory of the marker 60 moving around the rotation axis AX when the upper rotating body 2 rotates. The trajectory of the marker 60 has a circular or arc shape centered on the rotation axis AX in three-dimensional coordinates. The selected point cloud data shown in FIG. 5 includes not only the point cloud data of the marker 60 but also the point cloud data of the other portions 70. However, because the trajectory of the marker 60 has a circular or arc shape in three-dimensional coordinates, the controller 52 can distinguish between the point cloud data of the marker 60 and the point cloud data of the other portions 70.

[0039] The controller 52 determines whether or not the upper rotating body 2 has completed one revolution, i.e., whether or not the upper rotating body 2 has rotated 360° (step S4). If the revolution has not been completed (NO in step S4), the controller 52 continues recording (step S2) and filtering (step S3) of the point cloud data. If the revolution has been completed (YES in step S4), the controller 52 performs the process of step S5.

[0040] The controller 52 uses the selected specific portion position information, i.e., the point cloud data of the selected landmarks 60, to identify a plane corresponding to the trajectory of the landmarks 60 (step S5). FIG. 6 is a diagram showing the plane PS identified using the selected specific portion position information. As shown in FIG. 6, the point cloud data of the landmarks 60 includes a large number of coordinate data of the landmarks 60 arranged in an arc in a three-dimensional coordinate system represented by mutually orthogonal x-, y-, and z-axes. The x- and y-axes may be mutually orthogonal coordinate axes in a plane parallel to the ground GR, or may be mutually orthogonal coordinate axes in a horizontal plane at a predetermined height, or may be other coordinate axes. The z-axis may be a coordinate axis orthogonal to the x- and y-axes. The arc-shaped trajectory of the landmark 60 represented by the coordinate data of the landmark 60 is located on or near a certain plane (e.g., the plane PS in FIG. 6). Therefore, the controller 52 can identify the plane PS using the selected point cloud data of the landmarks 60 (a large number of coordinate data of the landmarks 60). The plane PS specified by the controller 52 may be represented by an equation of a plane. Specifically, for example, the plane PS may be represented by an equation of a plane in the three-dimensional coordinate system.

[0041] Next, the controller 52 calculates the normal vector (n) of the identified plane PS (step S6).

[0042] Next, the controller 52 uses the selected specific portion position information, i.e., the point cloud data of the selected landmarks 60, to identify a circle corresponding to the trajectory of the landmarks 60 (step S7). Fig. 7 is a diagram showing a circle CL (a part of a circle) identified using the specific portion position information. Specifically, for example, the controller 52 may project a large number of coordinate data of the landmarks 60 arranged in an arc onto a plane PS as shown in Fig. 7, and calculate a circle that best fits the large number of projected coordinate data, thereby identifying the circle CL corresponding to the trajectory of the landmarks 60.

[0043] Next, the controller 52 calculates the position of the pivot axis AX using the normal vector (n) of the plane PS and the center of the circle CL (step S8). The identified position of the pivot axis AX is shown in FIG.

[0044] Next, controller 52 identifies the relative position of work machine 100 with respect to ground surface GR on which undercarriage 1 of work machine 100 is placed, based on the relative position information, which is information relating to the relative position of mark 60 with respect to upper rotating body 2 or lower running body 1, and the position of swing axis AX (step S9). The relative position of work machine 100 with respect to ground surface GR may be, for example, the position of intersection P1 between an extension of swing axis AX and ground surface GR, as shown in Figure 2. Alternatively, the relative position of work machine 100 with respect to ground surface GR may be the position of a predetermined portion on swing axis AX of upper rotating body 2.

[0045] The controller 52 may store in advance, as the relative position information, information relating to the relative position of the mark 60 with respect to the upper rotating body 2. In this case, the relative position information may be stored based on a time when the rotation angle of the upper rotating body 2 with respect to the lower traveling body 1 is zero. Furthermore, the controller 52 may store in advance, as the relative position information, information relating to the relative height position of the mark 60 with respect to the lower traveling body 1.

[0046] [Modification of First Embodiment] Fig. 8 is a schematic diagram showing a position specifying system 50 according to a modification of the first embodiment. The position specifying system 50 according to the modification shown in Fig. 8 differs from the position specifying system 50 shown in Fig. 2 in that it includes a plurality of position information detectors 53, but the other configurations are similar to those of the position specifying system 50 shown in Fig. 2.

[0047] In the specific example shown in Figure 8, the multiple position information detectors 53 include a first position information detector 53 arranged at a position offset in one direction relative to the work machine 100, and a second position information detector 53 arranged at a position offset in the opposite direction relative to the work machine 100. The rotation information acquired by these position information detectors 53 when the upper rotating body 2 rotates can include information about an arc-shaped trajectory with a larger central angle or a completely circular trajectory (trajectory of the mark 60) compared to rotation information acquired by only one position information detector 53 as shown in Figure 2. Therefore, in this modified example, the circle or arc corresponding to the trajectory of the mark 60 can be identified with greater accuracy.

[0048] The calculation process by the controller 52 in this modified example is basically the same as the calculation process shown in Fig. 3. In this modified example, the controller 52 may perform the following calculation process, for example.

[0049] The controller 52 may perform the processes of steps S2 and S3 of FIG. 3 using the turning information acquired by the first position information detector 53 and the processes of steps S2 and S3 of FIG. 3 using the turning information acquired by the second position information detector 53 in parallel. When one rotation of the vehicle is completed (YES in step S4), the controller 52 may identify a plane using the specific part position information selected from the turning information acquired by the first position information detector 53, and may identify a plane using the specific part position information selected from the turning information acquired by the second position information detector 53. The controller 52 may then identify one plane PS from the two identified planes (step S5 of FIG. 3). Specifically, for example, the controller 52 may identify an intermediate (average) plane between the two identified planes as the plane PS (step S5 of FIG. 3). In addition, the controller 52 may generate composite position information by combining the specific body part position information selected from the turning information acquired by the first position information detector 53 and the specific body part position information selected from the turning information acquired by the second position information detector 53, and use this composite position information to identify the plane PS (step S5 in Figure 3).

[0050] Second Embodiment In a second embodiment shown in Fig. 9, the specific part is configured by an arm 5. In the second embodiment, the arm 5 is an example of a specific part of a working device in the present disclosure.

[0051] In the second embodiment, the controller 52 uses the specific part position information to identify a cylinder or a portion of a cylinder corresponding to the trajectory of the arm 5 when the upper rotating body 2 rotates, and identifies the position of the identified center line of the cylinder as the position of the rotation axis AX. As shown in Fig. 9 , if the arm 5 (the specific part of the working device) moves along a fixed cylindrical trajectory T2 centered on the rotation axis AX when the upper rotating body 2 rotates, the trajectory of the arm 5 when the upper rotating body 2 rotates will be cylindrical or shaped like a portion of a cylinder centered on the rotation axis AX. Therefore, the specific part position information includes information on the trajectory of the arm 5 (the specific part of the working device) that has a cylindrical shape or a shape like a portion of a cylinder. Therefore, the controller 52 can use the specific part position information to identify a cylinder or a portion of a cylinder that corresponds to the cylindrical trajectory (cylindrical trajectory T2) drawn by the arm 5, and can identify the position of the identified center line of the cylinder as the position of the rotation axis AX.

[0052] In the second embodiment, in order to improve the accuracy of identifying the cylinder or a part of the cylinder that corresponds to the cylindrical trajectory traced by the arm 5, it is preferable that the length of the arm 5 in the vertical direction (the direction of the rotation axis) is longer, and it is also preferable that the horizontal distance between the arm 5 and the upper rotating body 2 is longer. The longer the vertical length of the cylindrical trajectory T2 traced by the arm 5 when the upper rotating body 2 rotates, the clearer the position and shape of the cylinder become. Furthermore, the greater the horizontal distance between the arm 5 and the upper rotating body 2, the easier it becomes to distinguish between information regarding the trajectory of the arm 5 (cylindrical trajectory) and information regarding the trajectory of the upper rotating body 2, which are included in the three-dimensional position information.

[0053] In the position identification system 50 according to the second embodiment, the specific part (the work device specific part) is the arm 5 of the work device 3. When the position information detector 53 acquires the rotation information, the arm 5 is positioned in a position extending along the rotation axis AX, i.e., in a vertical position, as shown in FIG. 9 . Therefore, the specific part position information includes arm trajectory information, which is information about the trajectory (cylindrical trajectory) of the arm 5 when the arm 5 rotates around the rotation axis AX in a position extending along the rotation axis AX. The arm 5 can be positioned in a position extending vertically, and the vertical length of the arm 5 positioned in this position is significantly greater than, for example, the vertical dimension of the bucket 6. Furthermore, by positioning the arm 5 in a position extending vertically while reducing the angle between the boom 4 and the ground GR, it is also possible to increase the horizontal distance between the arm 5 and the upper rotating body 2. Therefore, in the position identification system 50 according to the second embodiment, the accuracy with which the controller 52 identifies the cylinder or a portion of the cylinder can be improved.

[0054] FIG. 10 is a flowchart showing an example of a calculation process performed by the controller 52 of the position specifying system 50 according to the second embodiment.

[0055] As shown in Fig. 10 , the controller 52 adjusts the working device 3 to a predetermined posture (step S21). Specifically, as shown in Fig. 9 , the controller 52 adjusts the posture of the working device 3 so that the arm 5 is disposed in a posture extending along the rotation axis AX. The controller 52 may control hydraulic equipment including the hydraulic pump and the control valve so that the working device 3 is adjusted to the predetermined posture in response to an operation applied to an operating lever by an operator. Furthermore, the controller 52 may control the hydraulic equipment so that the working device 3 is adjusted to the predetermined posture even when no operation is applied to an operating lever by an operator.

[0056] Next, the controller 52 causes the upper rotating body 2 to start a swing operation (step S22). The controller 52 may control hydraulic equipment including a hydraulic pump and a control valve so that the upper rotating body 2 performs a swing operation in response to an operation of the control lever by the operator. Alternatively, the controller 52 may control the hydraulic equipment so that the upper rotating body 2 performs a swing operation even if the operator does not operate the control lever.

[0057] The position information detector 53 acquires point cloud data, which is three-dimensional position information of the detection target, including the arm 5, during the rotation of the upper rotating body 2, and the controller 52 records the point cloud data input from the position information detector 53 (step S23). During the rotation, the controller 52 may sequentially store the point cloud data of the detection target at predetermined timings. The predetermined timings may be, for example, predetermined times, predetermined control cycles, or other timings. The controller 52 then writes the newly stored point cloud data to the previously stored point cloud data, thereby synthesizing these point cloud data (step S24). That is, the controller 52 generates synthesized point cloud data in which point cloud data at various rotation angles are synthesized.

[0058] FIG. 11 is a schematic diagram showing three-dimensional position information serving as rotation time information acquired by the position information detector 53 of the position identification system 50 in the second embodiment. FIG. 11 is an example of the composite point cloud data generated in step S24. The composite point cloud data shown in FIG. 11 includes, for example, point cloud data of the arm 5 acquired at a first timing (5-1), point cloud data of the arm 5 acquired at a second timing (5-2), point cloud data of the arm 5 acquired at a third timing (5-3), point cloud data of the arm 5 acquired at a fourth timing (5-4), point cloud data of the arm 5 acquired at a fifth timing (5-5), and point cloud data of the arm 5 acquired at a sixth timing (5-6). The composite point cloud data shown in FIG. 11 also includes point cloud data of the upper rotating body 2, the boom 4, and the bucket 6 acquired at the above timings (5-1) to (5-6).

[0059] The controller 52 determines whether or not the upper rotating body 2 has completed one revolution, i.e., whether or not the upper rotating body 2 has rotated 360° (step S25). If the revolution has not been completed (NO in step S25), the controller 52 continues recording the point cloud data (step S23) and writing the point cloud to the composite point cloud (step S24). If the revolution has been completed (YES in step S25), the controller 52 performs the process of step S26.

[0060] Next, the controller 52 performs downsampling. The controller 52 also removes some of the points from the generated composite point cloud (step S26). Downsampling is a process for reducing the amount of data in the composite point cloud to an extent that does not significantly affect the accuracy of identifying the position of the rotation axis AX. This downsampling reduces the load of the calculation process performed by the controller 52. Specifically, for example, the controller 52 may perform downsampling by dividing the three-dimensional coordinates into grids so that the three-dimensional coordinates are partitioned into sections of a predetermined size, setting some of the points included in each grid (e.g., one of the points) as representative points in the grid, and removing the other points in the grid. Removing some of the points from the composite point cloud is a process performed to improve the accuracy of identifying the cylinder. This process is a process for removing some or all of the background points (hidden points) behind the foreground from the composite point cloud. The controller 52 may perform this process using a known algorithm for removing hidden points. Note that the process of step S26, that is, the process relating to downsampling and the process relating to removing a portion of the point cloud from the composite point cloud, is not essential, and one or both of these processes can be omitted.

[0061] Next, the controller 52 uses the composite point cloud or the downsampled composite point cloud to identify a cylinder corresponding to the trajectory of the arm 5 during rotation (step S27). As described above, when the upper rotating body 2 rotates, the arm 5 traces a trajectory along the cylindrical trajectory T2 (a trajectory along a cylindrical surface) as shown in FIGS. 9 and 11 . Therefore, the controller 52 can identify a cylinder using the composite point cloud or the downsampled composite point cloud in three-dimensional coordinates represented by mutually orthogonal x-, y-, and z-axes. The cylinder identified by the controller 52 may be represented by an equation of a cylindrical surface. Specifically, for example, the identified cylinder may be represented by an equation of a cylindrical surface in the three-dimensional coordinates.

[0062] In step S27, the controller 52 may identify a cylinder from the composite point cloud using a technique such as shape fitting. Specifically, in step S27, the controller 52 may identify a cylinder from the composite point cloud using an algorithm for shape fitting such as RANSAC (Random sample consensus) or MSAC (M-estimator sample consensus).

[0063] Next, the controller 52 calculates the position of the pivot axis AX using the identified cylinder (cylindrical surface) (step S28). The identified position of the pivot axis AX is shown in FIG.

[0064] Next, the controller 52 determines the relative position of the work machine 100 with respect to the ground surface GR based on ground surface information, which is information about the ground surface GR on which the undercarriage 1 is placed, and the position of the swing axis AX (step S29). The relative position of the work machine 100 may be, for example, the position of an intersection P1 (see FIG. 9 ) between an extension of the swing axis AX and the ground surface GR, or the position of a portion whose relative position with respect to the swing axis AX has been determined in advance. The ground surface information may be information that can determine the position of the ground surface GR, such as the coordinates of the ground surface GR. The controller 52 may store the ground surface information in advance, or an operator may input the ground surface information to the controller 52. The controller 52 may also extract the position of the ground surface GR using a technique such as plane fitting. In addition, if the work machine 100 is equipped with an inclination sensor, such as an IMU sensor, that can detect the attitude of the work machine 100 (e.g., the attitude of the undercarriage 1 or the attitude of the upper swing structure 2), the controller 52 may calculate the position of the ground surface GR based on the detection results of the inclination sensor.

[0065] [First Modification of Second Embodiment] In the position identification system 50 according to the first modification of the second embodiment, the controller 52 may perform the following calculation process shown in Fig. 12. In step S22', the controller 52 stores the point cloud data of the detection target at the start of the rotation operation of the upper rotating body 2 as base point cloud data.

[0066] The controller 52 then calculates a point cloud difference, which is the difference between the point cloud data acquired subsequently and the base point cloud data, and writes this point cloud difference to the point cloud data acquired up to that point, thereby generating a composite point cloud (step S24'). The point cloud difference mainly contains a high proportion of point cloud data corresponding to the working device 3 including the arm 5. This is because, as shown in FIG. 11 , the point cloud data corresponding to the upper structure 2 does not change much near the rotation axis AX, whereas the point cloud data corresponding to the working device 3 including the arm 5 changes relatively greatly depending on the timing at which the point cloud data is acquired, as shown in the point cloud data at the first to sixth timings (5-1) to (5-6).

[0067] In the position identification system 50 according to the first modification of the second embodiment, by calculating the point cloud difference, it is possible to extract point cloud data corresponding to the working device 3 including the arm 5 from all point cloud data. Therefore, in this first modification, the accuracy with which the controller 52 identifies the cylinder or a part of the cylinder can be further improved. Note that steps S21, S23, and S25-S29 shown in FIG. 12 are the same as steps S21, S23, and S25-S29 shown in FIG. 10.

[0068] [Modification 2 of Second Embodiment] Fig. 13 is a schematic diagram showing a position specifying system 50 according to Modification 2 of the second embodiment. The position specifying system 50 according to Modification 2 shown in Fig. 13 differs from the position specifying system 50 according to the second embodiment shown in Fig. 9 in that it includes a plurality of position information detectors 53, but the other configurations are similar to those of the position specifying system 50 shown in Fig. 9.

[0069] 13, the multiple position information detectors 53 include a first position information detector 53 arranged at a position offset in one direction relative to the work machine 100, and a second position information detector 53 arranged at a position offset in the opposite direction relative to the work machine 100. The rotation information acquired by these position information detectors 53 when the upper rotating body 2 rotates can include information about a nearly complete cylindrical trajectory (trajectory of the arm 5), compared to rotation information acquired by only one position information detector 53 as shown in FIG. 9. Therefore, in this modified example 2, the cylinder or part of the cylinder corresponding to the trajectory of the arm 5 can be identified with greater accuracy.

[0070] The calculation process by the controller 52 in this modified example 2 is basically the same as the calculation process shown in Fig. 10 (or Fig. 12). In this modified example, the controller 52 may perform the following calculation process, for example.

[0071] The controller 52 may perform the processes of steps S23 and S24 in FIG. 10 using the rotation information acquired by the first position information detector 53 and the processes of steps S23 and S24 in FIG. 10 using the rotation information acquired by the second position information detector 53 in parallel. When one rotation is completed (YES in step S25), the controller 52 may identify a cylinder using the specific part position information selected from the rotation information acquired by the first position information detector 53, and may identify a cylinder using the specific part position information selected from the rotation information acquired by the second position information detector 53. The controller 52 may then identify one of the two identified cylinders (step S27 in FIG. 10). Specifically, for example, the controller 52 may identify an intermediate (average) cylinder between the two identified cylinders as the cylinder corresponding to the trajectory of the arm 5 (step S27 in FIG. 10). In addition, the controller 52 may generate composite position information by combining the specific body part position information selected from the turning information acquired by the first position information detector 53 and the specific body part position information selected from the turning information acquired by the second position information detector 53, and use this composite position information to identify the cylinder (step S27 in Figure 10).

[0072] [Other Modifications] Although the embodiments and some modifications of the present disclosure have been described above, the present disclosure is not limited to the above-described contents and further includes, for example, the following modifications.

[0073] (A) Regarding the Position Identifying Device The position identifying device 51 including the controller 52 may be mounted on the work machine 100, but may also be configured so that it is not mounted on the work machine 100 but can be located in a location separate from the work machine 100. In this case, the position identifying device 51 may be included in an information terminal. The information terminal may be, for example, a mobile information terminal such as a laptop computer, smartphone or tablet terminal, or a stationary information terminal such as a desktop personal computer, or may be a management device such as a server.

[0074] (B) Regarding the Work Machine The work machine in the present disclosure may be configured to be operated by an operator in the cab of the upper rotating body 2, or may be configured to be operated by an operator using a remote control device located in a remote location. In this case, the position identification device 51 may be located in a remote location.

[0075] (C) Regarding specific portions In the first embodiment, the mark 60 is attached to the back surface of the upper rotating body 2 on the outer surface 13, but the portion to which the mark 60 is attached is not limited to the outer surface 13 of the upper rotating body 2. The mark 60 may also be attached to another portion (for example, the surface of the work device 3) that rotates about the rotation axis AX as the upper rotating body 2 rotates. Furthermore, the mark 60 may not be a member attached to the upper rotating body 2 or the work device 3, but may be a portion of the work machine 100. The portion of the work machine 100 may be, for example, a portion of the upper rotating body 2 or a portion of the work device 3.

[0076] In the first embodiment, when the mark 60 has a shape that is long in the vertical direction, the controller 52 may identify a cylinder corresponding to the trajectory of the mark 60, rather than identifying a circle corresponding to the trajectory of the mark 60, and may use the center line of the cylinder to identify the position of the rotation axis.

[0077] In the second embodiment, the specific part (working device specific part) is the arm 5, but the working device specific part is not limited to the arm 5. The working device specific part may be at least a part of the working device, and may be, for example, a bucket or part of a bucket of the working device, or a boom or part of a boom of the working device.

[0078] As described above, the present disclosure provides a highly versatile position identification system, position identification device, and position identification method that can identify the position of a work machine.

[0079] The position identification system according to the first aspect comprises a position information detector and a controller that identifies the position of the rotation axis of the upper rotating body of a work machine using rotation time information, which is information acquired by the position information detector when the upper rotating body of the work machine rotates, and the rotation time information includes specific part position information, which is information regarding the position of a specific part of the work machine that rotates around the rotation axis as the upper rotating body rotates.

[0080] A work machine equipped with a rotating body, i.e., a slewing work machine, always has a rotating axis, which is located at a fixed central position on the work machine and can therefore be a representative part when expressing the position of the work machine. In a first aspect, the controller can identify the position of the above-mentioned rotating axis using the rotation information acquired by the position information detector when the upper rotating body rotates. Specifically, the specific part of the work machine is a part that rotates around the rotating axis, which is common to the upper rotating body, as the upper rotating body rotates, and moves along a fixed circular or cylindrical orbit centered on the rotating axis during rotation. Therefore, the specific part position information included in the rotation information acquired by the position information detector when the upper rotating body rotates includes information about the position of the specific part that rotates around the rotating axis as the upper rotating body rotates, i.e., information about the circular or cylindrical orbit described by the specific part when the upper rotating body rotates, and the rotating axis is located at the center of the circular or cylindrical orbit. Therefore, the controller can identify the position of the swing axis using the swing time information including the specific part position information. Note that in the first aspect, the position information detector does not need to be a large-scale position measurement system such as a GNSS and a total station, and can be, for example, a simple detector (such as a LiDAR) that can detect position information of a detection target including the specific part at the work site where the work machine is located. From the above, the position identification system according to the first aspect can identify the position of a work machine without using a GNSS and a total station, and is therefore highly versatile.

[0081] A second aspect may further include the following feature in the position identification system according to the first aspect. That is, in the position identification system according to the second aspect, the turning information may include three-dimensional position information acquired by the position information detector, the three-dimensional position information of the detection target including the specific part, and the controller may select the specific part position information from the three-dimensional position information and identify the position of the turning axis using the selected specific part position information. In this second aspect, even if the three-dimensional position information detected by the position information detector includes not only the specific part position information, which is information about the position of the specific part included in the detection target, but also information other than the specific part position information, i.e., information about the positions of other parts included in the detection target, the controller can select the specific part position information from the three-dimensional position information and identify the position of the turning axis using the selected specific part position information. In this second aspect, the position information detector may include a three-dimensional position information detector capable of acquiring three-dimensional position information of the detection target including the specific part.

[0082] A third aspect may further include the following feature in the position identification system according to the second aspect. That is, in the position identification system according to the third aspect, the specific portion may include a mark on the upper rotating body or a mark on a work implement supported by the upper rotating body, and the controller may use the specific portion position information to identify a circle or a portion of a circle corresponding to the trajectory of the mark when the upper rotating body rotates, and identify the position of the center of the circle as the position of the rotation axis. If the mark moves along a constant circular orbit centered on the rotation axis when the upper rotating body rotates, the trajectory of the mark when the upper rotating body rotates will be a circle or an arc shape centered on the rotation axis, and the specific portion position information includes information on the circular or arc-shaped trajectory of the mark. Therefore, the controller can use the specific portion position information to identify a circle or a portion of a circle (arc) corresponding to the trajectory of the mark, and can identify the position of the center of the identified circle as the position of the rotation axis. In this third aspect, the marker may be a part of the upper rotating body, a member attached to the upper rotating body, a part of the working device, or a member attached to the working device.

[0083] A fourth aspect may further include the following feature in the position identification system according to the second aspect. That is, in the position identification system according to the fourth aspect, the specific portion may include a mark on the upper rotating body or a mark on a work implement supported by the upper rotating body, and the controller may use the specific portion position information to identify a cylinder or a portion of a cylinder corresponding to a trajectory of the mark when the upper rotating body rotates, and identify the position of a center line of the cylinder as the position of the rotation axis. If the mark moves along a constant cylindrical trajectory centered on the rotation axis when the upper rotating body rotates, the trajectory of the mark when the upper rotating body rotates will have a cylindrical shape or a shape resembling a portion of a cylinder centered on the rotation axis, and therefore the specific portion position information includes information on the trajectory of the mark that has a cylindrical shape or a shape resembling a portion of a cylinder. Therefore, the controller can use the specific portion position information to identify the cylinder or a portion of the cylinder that corresponds to the trajectory of the mark, and can identify the position of the center line of the identified cylinder as the position of the rotation axis. In this fourth aspect, the mark may be a portion of the upper rotating body, a member attached to the upper rotating body, a portion of the working device, or a member attached to the working device.

[0084] A fifth aspect may be the position identification system according to the third or fourth aspect, further including the following feature. That is, in the position identification system according to the fifth aspect, the controller may identify the relative position of the work machine with respect to the ground on which the undercarriage of the work machine is placed, based on relative position information, which is information relating to the relative position of the marker with respect to the upper rotating body or the undercarriage, and the position of the swing axis. The relative position of the work machine may be, for example, the position of the intersection of an extension of the swing axis and the ground, or the position of a part whose relative position with respect to the swing axis has been identified in advance.

[0085] A sixth aspect may further include the following feature in the position identification system according to any one of the third to fifth aspects: In the position identification system according to the sixth aspect, the three-dimensional position information may include point cloud data relating to the upper rotating body and the landmarks when the upper rotating body is rotating, and the controller may select the specific part position information from the point cloud data.

[0086] A seventh aspect may be the position identification system according to the second aspect, further including the following feature. That is, in the position identification system according to the seventh aspect, the specific part may include a work equipment specific part that is at least a part of a work equipment supported by the upper rotating body, and the controller may use the specific part position information to identify a cylinder or a part of a cylinder corresponding to a trajectory of the work equipment specific part when the upper rotating body rotates, and identify the position of a center line of the cylinder as the position of the rotation axis. If the work equipment specific part moves along a constant cylindrical trajectory centered on the rotation axis when the upper rotating body rotates, the trajectory of the work equipment specific part when the upper rotating body rotates will have a cylindrical shape or a shape resembling a part of a cylinder centered on the rotation axis, and therefore the specific part position information includes information on the trajectory of the work equipment specific part that has a cylindrical shape or a shape resembling a part of a cylinder. Therefore, the controller can use the specific part position information to identify a cylinder or part of a cylinder corresponding to the trajectory of the specific part of the work device, and can identify the position of the center line of the identified cylinder as the position of the rotation axis.

[0087] The work implement specific portion may be at least a part of the work implement, and may be, for example, a bucket or part of a bucket of the work implement, or a boom or part of a boom of the work implement. However, in the position identification system according to the seventh aspect, to improve the accuracy of identifying the cylinder or part of the cylinder, the longer the vertical length (direction of the rotation axis) of the work implement specific portion is, the more preferable it is, and the longer the horizontal distance between the work implement specific portion and the upper rotating body is, the more preferable it is. This is because the longer the vertical length of the cylindrical trajectory traced by the work implement specific portion during the rotation, the clearer the position and shape of the cylinder becomes, and the greater the horizontal distance between the work implement specific portion and the upper rotating body, the easier it is to distinguish between information relating to the trajectory of the work implement specific portion and information relating to the trajectory of the upper rotating body, which are included in the three-dimensional position information.

[0088] Therefore, an eighth aspect preferably further includes the following feature in the positioning system according to the seventh aspect. That is, in the positioning system according to the eighth aspect, the specific part of the work device preferably includes an arm of the work device, and the specific part position information preferably includes arm trajectory information, which is information regarding the trajectory of the arm when the arm rotates around the pivot axis with the arm in an orientation extending along the pivot axis. The arm of the work device can be positioned in an orientation extending vertically, i.e., extending along the pivot axis, and the vertical length of the arm positioned in this orientation is significantly greater than, for example, the dimensions of the bucket. Furthermore, by positioning the arm in an orientation extending vertically while reducing the angle between the boom and the ground, it is also possible to increase the horizontal distance between the arm and the upper rotating body. Therefore, the positioning system according to the eighth aspect can improve the accuracy with which the controller identifies the cylinder or a portion of the cylinder.

[0089] A ninth aspect may be the position identification system according to the seventh or eighth aspect, further comprising the following feature. That is, in the position identification system according to the ninth aspect, the controller may identify the relative position of the work machine with respect to the ground surface based on ground surface information, which is information about the ground surface on which an undercarriage of the work machine is placed, and the position of the swing axis. The relative position of the work machine may be, for example, the position of the intersection between an extension of the swing axis and the ground surface, or the position of a part whose relative position with respect to the swing axis has been identified in advance.

[0090] A tenth aspect may further include the following feature in the position identification system according to any one of the seventh to ninth aspects: In the position identification system according to the tenth aspect, the three-dimensional position information may include point cloud data relating to the upper rotating body and the work implement when the upper rotating body is rotating, and the controller may select the specific part position information from the point cloud data.

[0091] An eleventh aspect may further include the following feature in the position identification system according to the tenth aspect: That is, in the position identification system according to the eleventh aspect, the controller may select the specific portion position information by using a difference between point clouds calculated by using the point cloud data.

[0092] A twelfth aspect may further include the following feature in the position identification system according to the first aspect. That is, in the position identification system according to the twelfth aspect, the identification portion may include a mark on the upper rotating body or a mark on a work implement supported by the upper rotating body. When the upper rotating body rotates, the mark moves along a constant circular or cylindrical orbit centered on the rotation axis. When the mark moves along the circular orbit when the upper rotating body rotates, the trajectory of the mark when the upper rotating body rotates becomes circular or arc-shaped. Furthermore, when the mark moves along the cylindrical orbit when the upper rotating body rotates, the trajectory of the mark when the upper rotating body rotates becomes cylindrical or shaped like a portion of a cylinder. Therefore, in the position identification system according to the twelfth aspect, the trajectory of the mark makes it easy to identify the position of the rotation axis. In this twelfth aspect, the marker may be a part of the upper rotating body, a member attached to the upper rotating body, a part of the working device, or a member attached to the working device.

[0093] A thirteenth aspect is preferably the position identification system according to the third, fourth, or twelfth aspect further including the following feature: In other words, in the position identification system according to the thirteenth aspect, it is preferable that the mark includes a reflective material. When the mark includes a reflective material, the difference between the specific body part position information and information other than the specific body part position information becomes clearer in the turning information acquired by the position information detector, making it easier for the controller to select the specific body part position information from the turning information.

[0094] A fourteenth aspect may further include the following feature in the position identification system according to the first aspect. That is, in the position identification system according to the fourteenth aspect, the specific part may include a work equipment specific part that is at least a part of a work equipment supported by the upper rotating body. When the upper rotating body rotates, the work equipment specific part moves along a constant circular or cylindrical orbit centered on the rotation axis. When the work equipment specific part moves along the circular orbit when the upper rotating body rotates, the trajectory of the work equipment specific part when the upper rotating body rotates is circular or arc-shaped. Furthermore, when the work equipment specific part moves along the cylindrical orbit when the upper rotating body rotates, the trajectory of the work equipment specific part when the upper rotating body rotates is cylindrical or shaped like a portion of a cylinder. Therefore, in the position identification system according to the fourteenth aspect, the trajectory of the work equipment specific part makes it easy to identify the position of the rotation axis.

[0095] A position identifying device according to a fifteenth aspect includes a controller that identifies the position of the rotating axis of an upper rotating body of a work machine using rotation time information, which is information acquired by a position information detector when the upper rotating body of the work machine rotates, and the rotation time information includes specific part position information, which is information about the position of a specific part of the work machine that rotates around the rotating axis as the upper rotating body rotates. In the fifteenth aspect, the controller can identify the position of the rotating axis as described above using the rotation time information acquired by the position information detector when the upper rotating body rotates. Specifically, the specific part of the work machine is a part that rotates around the rotating axis, which is common to the upper rotating body, as the upper rotating body rotates, and moves along a fixed circular or cylindrical orbit about the rotating axis during the rotation. Therefore, the specific part position information included in the rotation time information acquired by the position information detector when the upper rotating body rotates includes information about the position of the specific part that rotates around the rotation axis as the upper rotating body rotates, i.e., information about the circular orbit or cylindrical orbit described by the specific part when the upper rotating body rotates, and the rotation axis is located at the center of the circular orbit or cylindrical orbit. Therefore, the controller can identify the position of the rotation axis using the rotation time information including the specific part position information. Note that the position identification device according to the fifteenth aspect may further include the features of at least one of the second to fourteenth aspects.

[0096] A position identification method according to a sixteenth aspect includes acquiring swing time information when an upper rotating body of a work machine is rotating, and a controller identifying the position of the swing axis of the upper rotating body using the swing time information, wherein the swing time information includes specific part position information, which is information regarding the position of a specific part of the work machine that rotates around the swing axis as the upper rotating body rotates. In the sixteenth aspect, the controller can identify the position of the swing axis as described above using the swing time information acquired when the upper rotating body is rotating. Specifically, the specific part of the work machine is a part that rotates around the swing axis, which is common to the upper rotating body, as the upper rotating body rotates, and moves along a fixed circular or cylindrical orbit about the swing axis during the swing. Therefore, the specific part position information included in the rotation time information acquired during the rotation of the upper rotating body includes information regarding the position of the specific part that rotates around the rotation axis as the upper rotating body rotates, i.e., information regarding the circular orbit or the cylindrical orbit that the specific part traces during the rotation of the upper rotating body, and the rotation axis is located at the center of the circular orbit or the cylindrical orbit. Therefore, the controller can identify the position of the rotation axis using the rotation time information including the specific part position information. Note that the position identification method according to the sixteenth aspect may further include the features of at least one of the second to fourteenth aspects.

Claims

1. A position identification system comprising: a position information detector; and a controller that identifies the position of the rotation axis of an upper rotating body of a work machine using rotation time information, which is information acquired by the position information detector when an upper rotating body of the work machine rotates, wherein the rotation time information includes specific part position information, which is information regarding the position of a specific part of the work machine that rotates around the rotation axis as the upper rotating body rotates.

2. The position determination system of claim 1, wherein the turning information includes three-dimensional position information acquired by the position information detector, the three-dimensional position information of the detection object including the specific part, and the controller selects the specific part position information from the three-dimensional position information, and determines the position of the turning axis using the selected specific part position information.

3. A position identification system as described in claim 2, wherein the specific portion includes a mark on the upper rotating body or a mark on a work device supported by the upper rotating body, and the controller uses the specific portion position information to identify a circle or a portion of a circle corresponding to the trajectory of the mark when the upper rotating body rotates, and identifies the position of the center of the circle as the position of the rotation axis.

4. A position identification system as described in claim 2, wherein the specific portion includes a mark on the upper rotating body or a mark on a work device supported by the upper rotating body, and the controller uses the specific portion position information to identify a cylinder or a part of a cylinder corresponding to the trajectory of the mark when the upper rotating body rotates, and identifies the position of the center line of the cylinder as the position of the rotation axis.

5. A position determination system as described in claim 3 or 4, in which the controller determines the relative position of the work machine with respect to the ground on which the undercarriage of the work machine is placed based on relative position information, which is information regarding the relative position of the mark with respect to the upper rotating body or the undercarriage, and the position of the rotation axis.

6. A position determination system as described in claim 3 or 4, wherein the three-dimensional position information includes point cloud data relating to the upper rotating body and the landmarks when the upper rotating body is rotating, and the controller selects the specific part position information from the point cloud data.

7. A position identification system as described in claim 2, wherein the specific portion includes a work equipment specific portion that is at least a part of a work equipment supported by the upper rotating body, and the controller uses the specific portion position information to identify a cylinder or a part of a cylinder that corresponds to a trajectory of the work equipment specific portion when the upper rotating body rotates, and identifies the position of the center line of the cylinder as the position of the rotation axis.

8. A position identification system as described in claim 7, wherein the specific part of the working device includes an arm of the working device, and the specific part position information includes arm trajectory information which is information regarding the trajectory of the arm when the arm rotates around the pivot axis in a position such that the arm extends along the pivot axis.

9. A position determination system as described in claim 7, wherein the controller determines the relative position of the work machine with respect to the ground based on ground information, which is information about the ground on which the undercarriage of the work machine is placed, and the position of the pivot axis.

10. A position determination system as claimed in any one of claims 7 to 9, wherein the three-dimensional position information includes point cloud data relating to the upper rotating body and the work device when the upper rotating body is rotating, and the controller selects the specific part position information from the point cloud data.

11. The position specifying system according to claim 10, wherein the controller selects the specific part position information using a point cloud difference calculated using the point cloud data.

12. The position identification system according to claim 1, wherein the specific portion includes a mark on the upper rotating body or a mark on a work device supported by the upper rotating body.

13. The location system of claim 3, 4 or 12, wherein the indicia include a reflective material.

14. The position identification system according to claim 1, wherein the specific portion includes a work equipment specific portion that is at least a part of a work equipment supported by the upper rotating body.

15. A position identification device comprising: a controller that identifies the position of the rotation axis of an upper rotating body of a work machine using rotation time information, which is information acquired by a position information detector when the upper rotating body of the work machine rotates, wherein the rotation time information includes specific part position information, which is information regarding the position of a specific part of the work machine that rotates around the rotation axis as the upper rotating body rotates.

16. A position identification method comprising: acquiring rotation time information when an upper rotating body of a work machine rotates; and a controller identifying the position of the rotation axis of the upper rotating body using the rotation time information, wherein the rotation time information includes specific part position information, which is information regarding the position of a specific part of the work machine that rotates around the rotation axis as the upper rotating body rotates.

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