Work area estimation method, work area estimation system, and work area estimation program

Abstract

To efficiently estimate a work area in which a work vehicle has carried out agricultural work.SOLUTION: The method includes the steps of: acquiring the location information measured at multiple positioning points (P) through which a work vehicle (2) that carries out agricultural work while moving within a field (9) passes (S01); generating graph information of a connected graph of any two of multiple positioning points (S03) when the distance between two positioning points (P) is shorter than a first threshold and a time interval between positioning times at the two positioning points (P) is shorter than a second threshold; detecting a community that is a subgraph of a connected graph whose density is higher than another subgraph of the connected graph (S04); estimating work areas (81, 82, 83, 84) where the work vehicle has carried out agricultural work in the field (S05) on the basis of the community; and outputting the work area information that represents the work area to the outside (S06).SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a work area estimation method, a work area estimation system, and a work area estimation program, which can be suitably used, for example, to estimate a work area where agricultural work has been performed. [Background technology]

[0002] Patent Document 1 (Japanese Patent Publication No. 6946217) discloses a patent for a field registration device. This field registration device includes a position information storage processing unit and a field identification data generation unit. The position information storage processing unit acquires position information for multiple positioning points obtained by sampling positioning data at a predetermined interval using a positioning device mounted on a work vehicle while the work vehicle is moving using GNSS (Global Navigation Satellite System). The field identification data generation unit performs convex hull processing on the point cloud of the multiple positioning points to identify the shape of the field.

[0003] The farm field registration device of Patent Document 1 is effective when there is a single work area. However, when a work vehicle moves between multiple fields and performs farm work in these multiple fields, multiple positioning points will straddle the work areas where farm work was performed in the multiple fields and roads and other areas outside the work areas. Therefore, to distinguish and identify the shapes of these multiple work areas, time-consuming work is required, such as referring to map information to detect positioning points outside the field and exclude them from the target of convex hull processing. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6946217 Summary of the Invention [Problem to be solved by the invention]

[0005] In view of the above circumstances, one object of the present disclosure is to provide a work area estimation method, a work area estimation system, and a work area estimation program for efficiently estimating the work area in which a work vehicle has performed agricultural work. Other objects and novel features will become apparent from the description of this specification and the accompanying drawings. [Means for solving the problem]

[0006] The following describes the means for solving the problems using the numbers used in the (Mode for Carrying Out the Invention). These numbers are added to clarify the correspondence between the statements in the (Claims) and the (Mode for Carrying Out the Invention). However, these numbers should not be used to interpret the technical scope of the invention described in the (Claims).

[0007] According to one embodiment, a work area estimation method includes acquiring (S01) position information obtained by measuring the position at a plurality of positioning points (P) passed by a work vehicle (2) performing agricultural work while moving within a field (9). The work area estimation method further includes generating (S03) graph information of a connected graph in which any two of the plurality of positioning points (P) are connected as a node (N) when the distance between the two positioning points (P) is shorter than a first threshold and the time interval between the positioning times at the two positioning points (P) is shorter than a second threshold, and detecting (S04) a community that is a subgraph of the connected graph and has a higher density than another subgraph of the connected graph. The work area estimation method further includes estimating (S05) work areas (81, 82, 83, 84) in which the work vehicle (2) performed agricultural work within the field (9) based on the community, and outputting (S06) work area information representing the work areas (81, 82, 83, 84) to the outside.

[0008] According to one embodiment, the work area estimation system (1) includes an acquisition unit (421), a generation unit (423), a detection unit (424), an estimation unit (425), and an output unit (426). The acquisition unit (421) acquires position information obtained by measuring the position at a plurality of positioning points (P) passed by a work vehicle (2) performing agricultural work while moving within a farm field (9). The generation unit (423) generates graph information of a connected graph in which any two of the plurality of positioning points (P) are connected as a node (N) when the distance between the two positioning points (P) is shorter than a first threshold and the time interval between the positioning times at the two positioning points (P) is shorter than a second threshold. The detection unit (424) detects a community, which is a subgraph of the connected graph and has a higher density than another subgraph of the connected graph. The estimation unit (425) estimates, based on the community, work areas (81, 82, 83, 84) in which the work vehicle (2) performed farm work within the field (9). The output unit (426) outputs work area information indicating the work areas (81, 82, 83, 84) to the outside.

[0009] According to one embodiment, the work area estimation program is a program for executing a predetermined process. This process includes acquiring (S01) position information obtained by measuring the position at a plurality of positioning points (P) passed by a work vehicle (2) performing agricultural work while moving within a field (9). This process further includes generating (S03) graph information of a connected graph in which any two of the plurality of positioning points (P) are connected as a node (N) when the distance between the two positioning points (P) is shorter than a first threshold and the time interval between the positioning times at the two positioning points (P) is shorter than a second threshold, and detecting (S04) communities that are subgraphs of the connected graph and have a higher density than another subgraph of the connected graph. This process further includes estimating (S05) the work areas (81, 82, 83, 84) in the field (9) where the work vehicle (2) performed agricultural work based on the community, and outputting (S06) work area information representing the work areas (81, 82, 83, 84) to the outside. [Effects of the Invention]

[0010] According to one embodiment, it is possible to efficiently estimate the work area in which the work vehicle has performed farm work. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a diagram showing an example of the configuration of a working area estimation system according to an embodiment. [Figure 2] FIG. 2 is a block circuit diagram showing an example of the configuration of a working area estimation device according to an embodiment. [Figure 3] FIG. 3 is a flowchart showing an example of a configuration of a working area estimation method according to an embodiment. [Figure 4A] FIG. 4A is a diagram illustrating generation of graph information of a connected graph according to one embodiment. [Figure 4B] FIG. 4B is a diagram illustrating generation of graph information of a connected graph according to one embodiment. [Figure 5A] FIG. 5A is a diagram illustrating generation of graph information of a connected graph according to one embodiment. [Figure 5B] FIG. 5B is a diagram illustrating generation of graph information of a connected graph according to one embodiment. [Figure 5C] FIG. 5C is a diagram illustrating generation of graph information of a connected graph according to one embodiment. [Figure 5D] FIG. 5D is a diagram illustrating generation of graph information of a connected graph according to one embodiment. [Figure 6] FIG. 6 is a diagram illustrating community detection according to an embodiment. [Figure 7A] FIG. 7A is a diagram illustrating estimation of a working area according to one embodiment. [Figure 7B] FIG. 7B is a diagram illustrating estimation of a working area according to one embodiment. [Figure 7C]FIG. 7C is a diagram illustrating estimation of a working area according to one embodiment. [Figure 7D] FIG. 7D is a diagram illustrating the estimation of the working area according to one embodiment. [Figure 7E] FIG. 7E is a diagram illustrating estimation of a working area according to one embodiment. [Figure 7F] FIG. 7F is a diagram illustrating estimation of a working area according to one embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0012] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS With reference to the accompanying drawings, embodiments for implementing a working area estimation method, a working area estimation system, and a working area estimation program according to the present disclosure will be described below.

[0013] (Embodiment) As shown in FIG. 1, a work area estimation system 1 according to one embodiment includes a work area estimation device 4. The work area estimation system 1 may further include an external terminal 5. The work area estimation device 4, the external terminal 5, and an on-board terminal 20 mounted on the work vehicle 2 may be communicably connected via a network 3. The work vehicle 2 performs work such as agricultural work while moving within fields 9A and 9B. The work vehicle 2 may also move between the fields 9A and 9B. Hereinafter, when there is no need to distinguish between the fields 9A and 9B, they will be collectively referred to as field 9.

[0014] 2, the working space estimation device 4 according to one embodiment may be configured as a so-called computer. That is, the working space estimation device 4 includes a bus 41, a calculation device 42, a storage device 43, a communication device 44, and an input / output device 45. The bus 41 is configured to connect the calculation device 42, the storage device 43, the communication device 44, and the input / output device 45 so that they can communicate with each other.

[0015] The calculation device 42 includes an acquisition unit 421, a calculation unit 422, a generation unit 423, a detection unit 424, an estimation unit 425, and an output unit 426. The storage device 43 includes a work area estimation program storage unit 431. The work area estimation program storage unit 431 stores a work area estimation program.

[0016] By executing the working area estimation program, the arithmetic device 42 realizes the processing of the acquisition unit 421, calculation unit 422, generation unit 423, detection unit 424, estimation unit 425, and output unit 426. In other words, the acquisition unit 421, calculation unit 422, generation unit 423, detection unit 424, estimation unit 425, and output unit 426 are virtual functional blocks that perform processing realized by the arithmetic device 42 and storage device 43 working together. The processing of these functional blocks will be described later.

[0017] The working area estimation program may be read from an external recording medium 430 and stored in the working area estimation program storage unit 431. The recording medium 430 may be a non-transitory and tangible medium.

[0018] The communication device 44 is controlled by the acquisition unit 421 or the output unit 426, and communicates with external devices including the in-vehicle terminal 20 and / or the external terminal 5 by wireless communication and / or wired communication via the network 3. The working area estimation program may be received by the communication device 44 from the outside via the network 3 and stored in the working area estimation program storage unit 431.

[0019] The input / output device 45 outputs information to the user and accepts operations input by the user. As an example, the input / output device 45 includes a display device that outputs images, a speaker that outputs audio, buttons that accept press operations, a microphone that accepts audio input, a touch panel that accepts touch operations and outputs images, etc.

[0020] The in-vehicle terminal 20 includes a positioning device and a communication device, and is configured to transmit position information indicating a position measured by the positioning device using a Global Navigation Satellite System (GNSS) or the like to the working area estimation device 4 via the network 3. The in-vehicle terminal 20 may be configured as a computer in which an arithmetic device executes a program to realize processing.

[0021] The external terminal 5 includes a communication device and a display device, and is configured to output information received from the working area estimation device 4 via the network 3 on the display device. The external terminal 5 may be configured as a computer in which an arithmetic device executes a program to realize processing.

[0022] An example of the configuration of a work area estimation method according to an embodiment will be described with reference to the flowchart of Fig. 3. In other words, an example of the operation of the work area estimation system 1 according to an embodiment will be described with reference to the flowchart of Fig. 3. In other words, the flowchart of Fig. 3 shows an example of the configuration of a work area estimation program executed by the work area estimation device 4 according to an embodiment.

[0023] Before the processing of the flowchart in Figure 3 begins, the positioning device of the on-board terminal 20 of the work vehicle 2 measures its position and acquires position information. The point at which the on-board terminal 20 acquires position information is called the positioning point. The positioning point is included in the operating trajectory that the work vehicle 2 passed while performing agricultural work in the field 9, or the movement trajectory that the work vehicle 2 moved without performing agricultural work. The on-board terminal 20 acquires position information at each of multiple times and stores the position information in a storage device in association with positioning time information that indicates the positioning time at which the position information was acquired. The on-board terminal 20 may perform positioning at a predetermined interval. Strictly speaking, the position information indicates the position of the positioning device at the corresponding positioning time, but if the positioning device is fixed to the work vehicle 2, it effectively represents the position of the work vehicle 2 at that positioning time. The on-board terminal 20 begins acquiring position information when the work vehicle 2 begins operation by operating the key-on. Furthermore, the in-vehicle terminal 20 stops acquiring position information when the work vehicle 2 ends its operation by turning the key off, and transmits the position information stored in the storage device to the work area estimation device 4 via the network 3. When the work area estimation device 4 receives the position information, it starts the processing of the flowchart in Figure 3.

[0024] 3 starts, step S01 is executed. In step S01, the acquisition unit 421 of the work area estimation device 4 acquires position information of the positioning point. More specifically, the acquisition unit 421 controls the communication device 44 to receive the position information transmitted from the on-board terminal 20 and stores it in the storage device 43. The operation of the on-board terminal 20 to measure the position of the work vehicle 2 and acquire the position information may be executed in step S01, or may be executed before step S01.

[0025] The position information of each positioning point may include, for example, the latitude and longitude of the positioning point. Furthermore, the position information of each positioning point may be recorded in association with the order in which the positioning was performed, in addition to positioning time information indicating the time at which the positioning was performed. The order in which the positioning was performed may be calculated from the positioning time information.

[0026] After step S01, step S02 is executed. In step S02, the calculation unit 422 of the working space estimation device 4 calculates the distance and the time interval between two consecutive positioning points. More specifically, the calculation unit 422 calculates the distance between any two consecutive positioning points among the multiple positioning points based on the position information of these two positioning points. The calculation unit 422 also calculates the time interval between two positioning times associated with these two positioning points, respectively, based on these positioning times.

[0027] If the in-vehicle terminal 20 performs positioning periodically at a predetermined cycle, the time interval may be considered known and calculation of the time interval may be omitted. However, even in this case, the time interval may be calculated based on the recorded positioning time, taking into consideration the possibility that a malfunction occurred in receiving the GNSS signal.

[0028] After step S02, step S03 is executed. In step S03, the generation unit 423 of the working space estimation device 4 generates graph information of a connected graph that connects two of the multiple positioning points that satisfy a predetermined condition. The condition includes a first condition related to a first threshold and a second condition related to a second threshold. More specifically, the generation unit 423 performs a process of connecting two positioning points when the distance between the two positioning points is shorter than the first threshold and the time interval between two positioning times associated with the two positioning points is shorter than the second threshold. The generation unit 423 performs this process for each combination of any two positioning points included in the multiple positioning points, thereby generating graph information that represents a connected graph that connects some of the positioning points. Here, the graph information is data that represents the connected graph in a format that can be handled by a computer. The graph information includes, for example, information that represents each node and edge included in the connected graph and information that represents the connection relationship between the nodes and edges.

[0029] Generation of graph information for a connected graph according to one embodiment will be described with reference to Figures 4A and 4B. The first connected graph shown in the example of Figure 4A includes nodes N10, N11, N12, N13, N14, and N15. Hereinafter, when nodes N10 to N15 are not distinguished from one another, they will be collectively referred to as node N. In the example of Figure 4A, these nodes N represent multiple positioning points where positioning was performed by the work vehicle 2 while it was moving. The position of each node N in Figure 4A represents the position of the corresponding positioning point, and the connection between these nodes N indicates that the order of positioning at the corresponding two positioning points is consecutive.

[0030] 4A, node N10 and node N11 are connected, node N11 and node N12 are connected, node N12 and node N13 are connected, node N13 and node N14 are connected, and node N14 and node N15 are connected. These connections indicate that the positioning points corresponding to nodes N10, N11, N12, N13, N14, and N15 have been measured in this order.

[0031] Boundary line C in Figure 4A is an arc that is part of a circle centered at node N10. In other words, nodes N11, N12, N14, and N15, which are inside this circle, are closer to node N10 than the radius of this circle. Conversely, node N13, which is outside this circle, is farther from node N10 than the radius of this circle.

[0032] Among the connections in Fig. 4A, connections drawn with solid lines represent connections with positioning points that were located before a predetermined time has elapsed since the positioning time of node N10. Conversely, connections drawn with dashed dotted lines represent connections with positioning points that were located after a predetermined time has elapsed since the positioning time of node N10. In the example of Fig. 4A, the positions of nodes N11, N12, N13, and N14 are measured before a predetermined time has elapsed since the positioning time of node N10. The position of the remaining node N15 is measured after a predetermined time has elapsed since the positioning time of node N10.

[0033] Focusing on node N10 in Figure 4A, nodes N11, N12, and N14 satisfy the conditions that their distance from node N10 is shorter than the radius of the circle of boundary line C, and that their positioning time is shorter than a predetermined time from the positioning time of node N10, while the remaining nodes N13 and N15 do not. This is represented as in the second connected graph in Figure 4B. In the example of Figure 4B, node N10 of interest is connected to nodes N11, N12, and N14, which satisfy the above conditions, but is not connected to nodes N13 and N15, which do not satisfy the above conditions.

[0034] 4A and 4B, nodes N11, N12, and N14 connected to node N10 in the second connected graph of Fig. 4B are drawn with solid lines, while nodes N13 and N15 not connected to node N10 in the second connected graph of Fig. 4B are drawn with dashed lines.

[0035] Next, with reference to Figures 5A, 5B, 5C, and 5D, the generation of graph information for a connected graph according to one embodiment will be described in more detail. In the example of Figure 5A, a field 9 and positioning points P0, P1, P2, P3, P4, P5, P6, P7, P8, P9, P10, P11, and P12 are depicted. Hereinafter, when there is no need to distinguish between positioning points P0 to P12, they will be collectively referred to as positioning point P. Note that in Figure 5A, positioning point P, which does not actually have an area, is depicted as a circle centered at positioning point P to make it easier to see. This also applies to Figures 5B, 5C, and 5D, which will be described later. Positioning point P0 is located outside field 9, and the remaining positioning points P1 to P12 are located inside field 9. The arrows connecting the positioning points P0 to P12 in this order indicate that the work vehicle 2 performed positioning while passing through the positioning points P0 to P12 in this order. In the example of FIG. 5A, positioning at each positioning point P is performed at a predetermined positioning cycle, which is one minute. Also, in the example of FIG. 5A, the work vehicle 2 passes through positioning points P0 to P12 while moving at a constant speed, and the distance between two consecutive positioning points P is five meters. However, these specific numerical values ​​are merely an example and do not limit the embodiment.

[0036] FIG. 5B shows an example of a connection graph generated when the positioning point P0 is first focused on. Here, the boundary line C0 is a circle centered on the positioning point P0. The radius of this boundary line C0 is a first threshold used to determine whether or not to connect a certain positioning point P to the positioning point P0. In the example of FIG. 5B, the first threshold is 11 meters. As described above, in one embodiment, the first condition included in the conditions for connecting the positioning point P0 of interest to the certain positioning point P is that the distance from the positioning point P0 to the certain positioning point P is shorter than the first threshold. In the example of FIG. 5B, the positioning points P1, P2, and P8 satisfy the first condition, while the remaining positioning points P3 to P7 and P9 to P12 do not satisfy the first condition. Although boundary line C0 overlaps with the circles representing positioning points P7 and P9, it does not reach the center points of these circles, so the distance from the positioning point P0 of interest to positioning point P7 or P9 is longer than the first threshold, and therefore positioning points P7 and P9 are determined not to satisfy the first condition.

[0037] As described above, in one embodiment, the second condition included in the conditions for connecting the positioning point P0 of interest with a certain positioning point P is that the time interval from the positioning time at which the work vehicle 2 measures its position at positioning point P0 to the positioning time at that positioning point P is shorter than the second threshold. In the example of FIG. 5B, the second threshold is 7 minutes and 30 seconds. In the example of FIG. 5B, positioning points P1 to P7 satisfy the second condition, while the remaining positioning points P8 to P12 do not satisfy the second condition.

[0038] As described above, in one embodiment, the conditions for connecting a positioning point P0 of interest and a certain positioning point P include a first condition related to a first threshold and a second condition related to a second threshold. In the example of FIG. 5B, positioning points P1 and P2 satisfy the first condition and the second condition. In the example of FIG. 5B, the edges of the second connection graph generated in step S03 of the flowchart of FIG. 3 are indicated by thick solid lines. More specifically, the second connection graph of FIG. 5B includes an edge connecting positioning point P0 and positioning point P1, and an edge connecting positioning point P0 and positioning point P2.

[0039] The remaining positioning points P3 to P12 do not satisfy the first condition and / or the second condition, and are therefore not included in the second connected graph in Fig. 5B. In Fig. 5B, the positioning points P3 to P12 that do not satisfy the first condition and / or the second condition are indicated by dashed lines.

[0040] 5C shows an example of a third connected graph generated when first focusing on positioning point P0 and then on positioning point P1. The third connected graph shown in FIG. 5C includes edges represented by thick solid lines and edges represented by thin dashed lines. The edges represented by thick solid lines represent connections between positioning point P1 and other positioning points P. The edges represented by thin dashed lines are edges of the second connected graph shown in FIG. 5B that are not included in the third connected graph shown in FIG. 5C.

[0041] In the example of FIG. 5C, boundary line C1 is a circle centered on positioning point P1. The radius of this boundary line C1 is a first threshold value related to the first condition. The first threshold value in the example of FIG. 5C is the first threshold value used in the process described with reference to FIG. 5B, and is, for example, 11 meters. In the example of FIG. 5C, positioning points P0, P2, P3, and P7 to P9 satisfy the first condition related to the first threshold value, while the remaining positioning points P4 to P6 and P10 to P12 do not satisfy the first condition. Note that although boundary line C1 overlaps with the circles representing positioning points P6 and P10, it does not reach the center points of these circles. Therefore, the distance from the positioning point P1 of interest to positioning point P6 or P10 is longer than the first threshold value, and therefore positioning points P6 and P10 are determined not to satisfy the first condition.

[0042] In the example of Fig. 5C, the second threshold is the second threshold used in the process described with reference to Fig. 5B, and is, for example, 7 minutes 30 seconds. In the example of Fig. 5C, the positioning points P0 and P2 to P8 satisfy the second condition, while the remaining positioning points P9 to P12 do not satisfy the second condition.

[0043] In the example of Fig. 5C, positioning points P0, P2, P3, P7, and P8 satisfy the first and second conditions. In the example of Fig. 5C, edges connecting positioning point P1 to other positioning points P in the third connection graph generated in step S03 of the flowchart of Fig. 3 are indicated by thick solid lines. More specifically, the third connection graph of Fig. 5C includes edges connecting positioning point P1 to positioning points P0, P2, P3, P7, and P8, respectively. The third connection graph of Fig. 5C further includes an edge connecting positioning point P0 to positioning point P2, which is an edge unrelated to positioning point P1, in the second connection graph of Fig. 5B.

[0044] Thereafter, the positioning points P2 to P12 are sequentially focused on, and a connection graph is generated by adding edges connecting the focused positioning point P to the positioning point P that satisfies the first condition related to the first threshold value and the second condition related to the second threshold value. Fig. 5D shows an example of a connection graph generated as a result of combining the connection graphs generated by focusing on the positioning points P0 to P12, respectively.

[0045] After step S03 in the flowchart of Fig. 3, step S04 is executed. In step S04, the detection unit 424 of the working domain estimation device 4 detects a community from the connected graph. A community is a subgraph of the connected graph in which nodes are more densely connected than other parts. In one embodiment, a so-called network analysis technique is used to detect a subgraph of the connected graph in which connections are denser.

[0046] A method for detecting communities from a connected graph using a so-called network analysis technique will be described with reference to Figure 6. The connected graph shown in the example of Figure 6 includes nodes N21, N22, N23, N24, N25, and N26, and edges E1, E2, E3, E4, E5, E6, and E7. Hereinafter, when nodes N21 to N26 are not distinguished, they will be referred to as node N. Furthermore, when edges E1 to E7 are not distinguished, they will be referred to as edge E.

[0047] In the example of FIG. 6, edge E1 connects nodes N21 and N22. Similarly, edge E2 connects nodes N22 and N23. Edge E3 connects nodes N21 and N23. Edge E4 connects nodes N23 and N24. Edge E5 connects nodes N24 and N25. Edge E6 connects nodes N24 and N26. Edge E7 connects nodes N25 and N26.

[0048] First, for each combination of any two nodes included in the connected graph, the shortest path along the edges between these two nodes is calculated. In the example of FIG. 6, a method is known for determining the shortest path from one node N included in the connected graph to another node N included in the same connected graph via an edge E included in the same connected graph. As an example, the shortest path from node N21 to node N22 is edge E1. Similarly, the shortest path from node N21 to node N26 is edges E3, E4, and E6. Such shortest paths are calculated for each combination of any two nodes N included in the connected graph shown in the example of FIG. 6.

[0049] Next, for each edge included in the connected graph, the number of times it appears on the calculated shortest route is calculated. In the example of Figure 6, edge E1 appears only once on the shortest route between node N21 and node N22, so the number of times edge E1 appears on the shortest route is 1. Similarly, edge E7 appears on the shortest route is also 1. Furthermore, edge E2 appears a total of four times on the shortest routes between node N22 and each of nodes N23, N24, N25, and N26, so the number of times edge E2 appears on the shortest route is 4. Similarly, the number of times edges E3, E5, and E6 appear on the shortest route is also 4. Furthermore, edge E4 appears a total of nine times in the shortest paths between node N21 and each of nodes N24, N25, and N26, the shortest paths between node N22 and each of nodes N24, N25, and N26, and the shortest paths between node N23 and each of nodes N24, N25, and N26, so the number of times edge E4 appears in the shortest paths is nine.

[0050] Next, the edge that appears the most number of times on the shortest path is detected from among the edges included in the connected graph. In the example of Figure 6, the edge E that appears the most number of times on the shortest path is edge E4.

[0051] Next, the edge that appears most frequently on the shortest path is removed from the connected graph, thereby dividing the connected graph and detecting node communities. In the example of Figure 6, by removing edge E4 that appears most frequently on the shortest path from the connected graph, a first community 8A including nodes N21, N22, and N23 and a second community 8B including nodes N24, N25, and N26 are detected.

[0052] If the connected graph is not split even after removing the edge that appears most frequently on the shortest path, the node community is detected by continuing to remove edges in descending order of their frequency of appearing on the shortest path until the connected graph is split.

[0053] Step S05 is executed after step S04 in the flowchart of Figure 3. In step S05, the estimation unit 425 of the work area estimation device 4 estimates the work area in which the work vehicle 2 performed work, based on the communities detected in step S04. More specifically, the estimation unit 425 estimates the position and shape of the work area corresponding to each detected community by calculating the convex hull or concave hull of the positioning points included in each detected community, based on the position information of these positioning points.

[0054] As an example, a case will be described where the position information shown in Figure 7A has been acquired. In Figure 7A, multiple dots represent multiple positioning points at which the position of the work vehicle 2 has been measured, and multiple straight lines represent the movement trajectory of the work vehicle 2 when not working and the working trajectory of the work vehicle 2 when working in the field. Steps S02 to S04 of the flowchart in Figure 3 are executed based on the position information in Figure 7A, and communities of the positioning points shown in Figures 7B, 7C, 7D, and 7E are detected. Then, by calculating the convex hull of the positioning points included in each detected community, the position and shape of work areas 81, 82, 83, and 84 corresponding to each community are estimated, as shown in Figure 7F.

[0055] After step S05 in the flowchart of FIG. 3, step S06 is executed. In step S06, the output unit 426 of the work area estimation device 4 outputs work area information representing the estimated work area. More specifically, the output unit 426 controls the input / output device 45 to output the work area information representing the position and shape of the estimated work area to the outside. As an example, a display device or touch panel included in the input / output device 45 may display the estimated shape of the work area so that the user can visually recognize it. At this time, the estimated shape of the work area may be displayed superimposed on map information of the area including the work area so that the user can intuitively understand it. Furthermore, a positioning point P included in the work area may be displayed superimposed on the estimated shape and map information.

[0056] After step S06, the process of the flowchart in FIG. 3 ends.

[0057] As described above, according to one embodiment, the work area can be efficiently estimated by automatically excluding positioning points outside the work area based on position information measured by the work vehicle 2 at multiple positioning points.

[0058] (Variation 1) In the first embodiment described above, a configuration example in which a so-called network analysis technique is used to detect communities by excluding edges that appear most frequently on the shortest paths between nodes in step S04 of the flowchart in Fig. 3 has been described with reference to Fig. 6. As a variation of this configuration example, a configuration example in which communities are detected by excluding nodes included in the connected graph generated in step S03 of the flowchart in Fig. 3, where the total number of edges at each node is less than a predetermined threshold, will be described.

[0059] In the example of the connected graph shown in Figure 5D, the total number of edges of positioning point P0 as a node is 2, the number of edges of positioning points P4, P9, and P12 as nodes is 4, the number of edges of positioning point P1 as a node is 5, the number of edges of positioning points P3, P5, P8, P10, and P11 as nodes is 6, the number of edges of positioning point P2 as a node is 7, and the number of edges of positioning points P6 and P7 as nodes is 9. Here, if the threshold for the total number of edges of a node is set to, for example, 3, then positioning point P0 as a node outside field 9 and positioning points P1 to P12 as nodes inside field 9 are distinguished. This is due to the difference that when work vehicle 2 travels outside field 9 without performing farm work, there is a high probability that its movement trajectory will be a narrow, single road, and when work vehicle 2 travels inside field 9 while performing farm work, there is a high probability that its operation trajectory will include multiple parallel, adjacent lines. By excluding the positioning point P0 as a node whose total number of edges is less than the threshold value from the connected graph, a community consisting of the positioning points P1 to P12 as nodes remaining in the connected graph is detected.

[0060] The threshold for the total number of edges of a node may be set in advance to an appropriate value based on previously acquired position information.

[0061] (Variation 2) In the first embodiment described above, in step S06 of the flowchart in FIG. 3, the configuration was described in which the work area estimation device 4 displays and outputs work area information representing the estimated work area. As a variation of this configuration, the work area information may be output by displaying it on the external terminal 5. In this case, the output unit 426 of the work area estimation device 4 controls the communication device 44 to transmit the work area information to the external terminal 5 via the network 3. The communication device of the external terminal 5 receives the work area information, and the display device of the external terminal 5 outputs the work area information to the outside. At this time, the estimated shape of the work area may be displayed superimposed on map information of the area including the work area to allow the user to intuitively understand. Furthermore, the positioning point P included in the work area may be displayed superimposed on the estimated shape and map information.

[0062] The invention made by the inventor has been specifically described above based on the embodiments, but it goes without saying that the present invention is not limited to the embodiments and can be modified in various ways without departing from the spirit of the invention. Furthermore, the features described in the embodiments can be freely combined within the scope of technical compatibility. [Explanation of symbols]

[0063] 1. Work Area Prediction System 2 Work vehicles 20 In-vehicle terminal 3 Network 4 Work area estimation device 41 Bus 42 Arithmetic unit 421 Acquisition Department 422 Calculation Unit 423 Generation part 424 Detector 425 Guessing part 426 Output Section 43 Storage device 430 Recording Media 431 Working Area Estimation Program Memory 44 Communication equipment 45 Input / Output Devices 5 External terminal 8A and 8B communities 81, 82, 83, 84 work area Fields 9, 9A, and 9B C, C0, C1 border E1, E2, E3, E4, E5, E6, E7 edges N10, N11, N12, N13, N14, and N15 nodes N21, N22, N23, N24, N25, and N26 nodes P0, P1, P2, P3, P4, P5, P6, P7, P8, P9, P10, P11, P12 positioning points

Claims

1. Acquiring position information obtained by measuring the position at a plurality of positioning points passed by a work vehicle that moves within a farm field and performs agricultural work; generating graph information of a connected graph in which any two of the plurality of positioning points are connected as nodes when a distance between the two positioning points is shorter than a first threshold and a time interval between positioning times at the two positioning points is shorter than a second threshold; detecting communities that are subgraphs of the connected graph that have a higher density than other subgraphs of the connected graph; estimating a work area in the field where the work vehicle performed the farm work based on the community; outputting work area information representing the work area to the outside; Contains Work area estimation method.

2. 2. The working area estimation method according to claim 1, The detecting step includes: removing edges of the connected graph in descending order of frequency of appearance on the shortest path between any two of the plurality of positioning points until the subgraph is separated from the connected graph; Contains Work area estimation method.

3. 2. The working area estimation method according to claim 1, The detecting step includes: excluding nodes from the connected graph whose total number of edges is less than a third threshold; Contains Work area estimation method.

4. The working area estimation method according to any one of claims 1 to 3, The connection graph includes, as nodes, positioning points that the work vehicle passes through from the start to the end of its operation. Work area estimation method.

5. The working area estimation method according to any one of claims 1 to 4, The outputting step includes: Displaying the estimated shape of the work area superimposed on map information Contains Work area estimation method.

6. an acquisition unit that acquires position information obtained by measuring the position at a plurality of positioning points passed by a work vehicle that moves within a farm field while performing agricultural work; a generation unit that generates graph information of a connected graph in which any two of the plurality of positioning points are connected as nodes when a distance between the two positioning points is shorter than a first threshold and a time interval between positioning times at the two positioning points is shorter than a second threshold; a detector for detecting communities, each of which is a subgraph of the connected graph, the subgraph having a higher density than another subgraph of the connected graph; an estimation unit that estimates a work area in the field where the work vehicle performed the farm work based on the community; an output unit that outputs work area information representing the work area to the outside; Equipped with Work area estimation system.

7. A work area estimation program for realizing a predetermined process by executing the program, The process comprises: Acquiring position information obtained by measuring the position at a plurality of positioning points passed by a work vehicle that moves within a farm field and performs agricultural work; generating graph information of a connected graph in which any two of the plurality of positioning points are connected as nodes when a distance between the two positioning points is shorter than a first threshold and a time interval between positioning times at the two positioning points is shorter than a second threshold; detecting communities that are subgraphs of the connected graph that have a higher density than other subgraphs of the connected graph; estimating a work area in the field where the work vehicle performed the farm work based on the community; outputting work area information representing the work area to the outside; Contains Work area estimation program.

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