Positioning device, work vehicle, positioning method, and positioning program

Abstract

To provide a positioning device, a work vehicle, a positioning method, and a positioning program that can prevent base station switching when positioning a mobile body based on correction information corresponding to a specific base station.SOLUTION: When RTK positioning is enabled in one field, in which the position of a work vehicle 10 is calculated based on correction information generated based on the satellite signal received by one base station from a satellite, a positioning device 14 performs RTK positioning at all positions within the field based on the correction information corresponding to the same base station by using positioning information of the position of the work vehicle 10 in the field calculated based on satellite signals immediately before RTK positioning is enabled.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a positioning device that calculates the current position of a moving object. [Background technology]

[0002] Conventionally, a real-time kinematic method (RTK-GPS positioning method, hereinafter referred to as "RTK method") has been known that can measure the position of a work vehicle such as a tractor with high accuracy. The RTK method enables highly accurate positioning by using correction information corresponding to a base station (reference station) close to the work vehicle.

[0003] Another known positioning method is the Virtual Reference Station (VRS) method. For example, Patent Document 1 discloses a technique in which a VRS information broadcasting center generates VRS reference information for antenna stations (Ak: A1 to An) using satellite observation information from fixed reference stations (R1 to R4), and transmits the generated VRS reference information to a mobile station. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2002-318273 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the conventional technology, the base station closest to the work vehicle is selected and the current position of the work vehicle is calculated using the correction information corresponding to that base station. For example, if a field in which the work vehicle is working is located midway between two base stations, the base station corresponding to the correction information may be switched while the work vehicle is autonomously traveling in the field. If the base station is switched while the work vehicle is autonomously traveling, the RTK positioning is temporarily interrupted, causing a problem that the autonomous traveling of the work vehicle is interrupted. This problem is not limited to work vehicles that autonomously travel in fields, but can occur in a similar manner in various systems that use correction information to position a moving object.

[0006] An object of the present invention is to provide a positioning device, a work vehicle, a positioning method, and a positioning program that are capable of preventing switching of a base station when positioning a moving body based on correction information corresponding to a specific base station. [Means for solving the problem]

[0007] The positioning method of the present invention, when it becomes possible to perform specific positioning in a field, in which a base station calculates the position of a moving body based on correction information generated based on a satellite signal received from a satellite, performs the specific positioning at all positions in the field based on the correction information corresponding to the same base station by utilizing positioning information of the position of the moving body in the field calculated based on the satellite signal just before the specific positioning becomes possible.

[0008] The work vehicle of the present invention is a work vehicle that travels in the field, and is equipped with a positioning device that positions the work vehicle using a positioning method described in any one of claims 1 to 5, and a control device that executes travel processing based on position information calculated by the positioning device.

[0009] The positioning device of the present invention, when it becomes possible to perform specific positioning in a field, in which a base station calculates the position of a moving body based on correction information generated based on a satellite signal received from a satellite, performs the specific positioning at all positions in the field based on the correction information corresponding to the same base station by utilizing positioning information of the position of the moving body in the field calculated based on the satellite signal just before the specific positioning becomes possible.

[0010] The positioning program of the present invention is a positioning program that causes one or more processors to perform specific positioning at all positions in a field based on the correction information corresponding to the same base station, by utilizing positioning information of the position of the moving body in the field calculated based on the satellite signal just before the specific positioning becomes possible, in which the position of the moving body is calculated based on correction information generated based on a satellite signal received by a base station from a satellite, when the specific positioning becomes possible in the field. Effect of the Invention

[0011] According to the present invention, it is possible to provide a positioning device, a work vehicle, a positioning method, and a positioning program that are capable of preventing switching of a base station when positioning a moving body based on correction information corresponding to a specific base station. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 is a schematic diagram showing the configuration of a positioning system according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a diagram showing a system configuration of a positioning system according to an embodiment of the present invention. [Diagram 3] FIG. 3 is an external view showing an example of a work vehicle according to an embodiment of the present invention. [Figure 4] FIG. 4 is a diagram showing an example of a travel route of the work vehicle according to the embodiment of the present invention. [Diagram 5]FIG. 5 is a diagram showing an example of positioning information recorded by the positioning device according to the embodiment of the present invention. [Figure 6] FIG. 6 is a diagram showing an example of movement information recorded by the positioning device according to the embodiment of the present invention. [Figure 7] FIG. 7 is a diagram showing an example of base station information registered in the base station server according to the embodiment of the present invention. [Figure 8] FIG. 8 is a diagram showing an example of the positioning process of a work vehicle performed by the positioning device according to the embodiment of the present invention. [Figure 9] FIG. 9 is a flowchart showing an example of a procedure of a positioning process executed by the positioning device according to the embodiment of the present invention. [Figure 10] FIG. 10 is a diagram showing an example of the positioning process of a work vehicle performed by the positioning device according to the embodiment of the present invention. [Figure 11] FIG. 11 is a diagram showing an example of the positioning process of a work vehicle performed by the positioning device according to the embodiment of the present invention. [Figure 12] FIG. 12 is a flowchart showing an example of a procedure of a positioning process executed by the positioning device according to the embodiment of the present invention. [Figure 13] FIG. 13 is a diagram showing an example of a positioning process of a work vehicle performed by a positioning device according to another embodiment of the present invention. [Figure 14] FIG. 14 is a diagram showing an example of a positioning process of a work vehicle performed by a positioning device according to another embodiment of the present invention. [Figure 15] FIG. 15 is a diagram showing an example of a positioning process of a work vehicle performed by a positioning device according to another embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] The following embodiment is an example of the present invention, and is not intended to limit the technical scope of the present invention.

[0014] 1, a positioning system 1 according to an embodiment of the present invention includes a work vehicle 10, a base station server 20, a base station 30, and a satellite 40. The work vehicle 10 and the base station server 20 are capable of communicating with each other via a communication network N1 (see FIG. 2), such as a mobile phone network, a packet network, or a wireless LAN.

[0015] In this embodiment, the work vehicle 10 will be described as a tractor. In other embodiments, the work vehicle 10 may be a rice transplanter, a combine harvester, construction machinery, a snowplow, or the like. The work vehicle 10 is configured to be capable of autonomous travel (automatic travel) along a travel route within a field F (see FIG. 4). For example, the work vehicle 10 can autonomously travel along a travel route that has been generated in advance for the field F, based on position information of the current position of the work vehicle 10 calculated by the positioning system 1. The work vehicle 10 is an example of a moving body of the present invention.

[0016] The satellite 40 is a positioning satellite constituting a satellite positioning system such as GNSS (Global Navigation Satellite System), and transmits a GNSS signal (satellite signal). The positioning system 1 includes multiple satellites 40. The base station 30 is a reference point (reference station) constituting the satellite positioning system, and is installed at multiple locations in advance. In this embodiment, two base stations 30A, 30B are illustrated. The base station server 20 is a management server that manages the multiple base stations 30, and transmits correction information to the work vehicle 10 for calculating the current position of the work vehicle 10. The base station 30A is an example of a first base station of the present invention, and the base station 30B is an example of a second base station of the present invention.

[0017] The work vehicle 10 executes a positioning process to calculate the current position (latitude and longitude) of the work vehicle 10 based on the GNSS signal transmitted from the satellite 40 and the correction information transmitted from the base station server 20. Here, in this embodiment, the positioning system 1 uses an RTK positioning method to position the work vehicle 10. Since the RTK positioning method is a well-known method, detailed explanations are omitted, and only an overview is provided below. For example, when the work vehicle 10 receives a GNSS signal from the satellite 40, it calculates the position of the work vehicle 10 based on the GNSS signal (single positioning). The base station server 20 generates correction information for correcting the position based on positioning information (such as a GNSS signal) acquired from the base station 30 closest to the work vehicle 10. The positioning system 1 corrects the calculated position of the work vehicle 10 based on the correction information to calculate the current position of the work vehicle 10. The work vehicle 10 autonomously travels along the travel route in the field F while acquiring the current position.

[0018] [Work vehicle 10] 2 and 3, the work vehicle 10 includes a vehicle control device 11, a traveling device 12, a working device 13, and a positioning device 14. The vehicle control device 11 is electrically connected to the traveling device 12, the working device 13, and the positioning device 14. The vehicle control device 11 and the positioning device 14 may be capable of wireless communication.

[0019] The vehicle control device 11 is a computer system including one or more processors and storage memories such as non-volatile memory and RAM. The vehicle control device 11 controls the operation of the work vehicle 10 in response to various user operations on the work vehicle 10. The vehicle control device 11 also executes autonomous driving processing of the work vehicle 10 based on the current position of the work vehicle 10 calculated by a positioning device 14 described below and a driving route generated in advance (see FIG. 4). The vehicle control device 11 is an example of a control device of the present invention, and the autonomous driving processing is an example of a driving processing of the present invention. The driving route is stored in the work vehicle 10 or a server (not shown) that manages the work vehicle 10.

[0020] The traveling device 12 is a drive unit that causes the work vehicle 10 to travel. As shown in Fig. 3, the traveling device 12 includes an engine 121, front wheels 122, rear wheels 123, a transmission 124, a front axle 125, a rear axle 126, a handlebar 127, and the like. The front wheels 122 and the rear wheels 123 are provided on the left and right sides of the work vehicle 10, respectively. The traveling device 12 is not limited to a wheel type that includes the front wheels 122 and the rear wheels 123, but may be a crawler type that includes crawlers provided on the left and right sides of the work vehicle 10.

[0021] The engine 121 is a drive source such as a diesel engine or a gasoline engine that is driven by fuel supplied to a fuel tank (not shown). The traveling device 12 may be equipped with an electric motor as a drive source together with the engine 121 or instead of the engine 121. A generator (not shown) is connected to the engine 121, and power is supplied from the generator to electrical components such as the vehicle control device 11 and the battery provided in the work vehicle 10. The battery is charged by the power supplied from the generator. The vehicle control device 11, the positioning device 14, and other electrical components provided in the work vehicle 10 can be driven by the power supplied from the battery even after the engine 121 is stopped.

[0022] The driving force of the engine 121 is transmitted to front wheels 122 via a transmission 124 and a front axle 125, and to rear wheels 123 via the transmission 124 and a rear axle 126. The driving force of the engine 121 is also transmitted to the work device 13 via a PTO shaft (not shown). When the work vehicle 10 performs autonomous traveling, the traveling device 12 performs traveling operation in accordance with commands from the vehicle control device 11.

[0023] The work implements 13 are, for example, a cultivator, a plow, a fertilizer applicator, a grass cutter, or a seed sower, and are detachable from the work vehicle 10. This allows the work vehicle 10 to perform various types of work using each of the work implements 13.

[0024] Specifically, the working device 13 shown in Fig. 3 is a cultivator equipped with a plurality of cultivating tines 132 that rotate about a rotary shaft 131 by driving force from an engine 121 to cultivate a field. The working device 13 is supported in the work vehicle 10 by a lifting mechanism (not shown) so that it can be raised and lowered. The vehicle control device 11 controls the lifting mechanism to raise and lower the working device 13. For example, the vehicle control device 11 lowers the working device 13 when the work vehicle 10 moves forward in a work target area of ​​the field, and raises the working device 13 when the work vehicle 10 moves backward.

[0025] The handle 127 is an operating unit that is operated by a user or the vehicle control device 11. For example, in the traveling device 12, the angle of the front wheels 122 is changed by a hydraulic power steering mechanism (not shown) or the like in response to the operation of the handle 127 by the vehicle control device 11, and the traveling direction of the work vehicle 10 is changed.

[0026] In addition to the handlebar 127, the traveling device 12 is equipped with a shift lever, accelerator, brake, etc. (not shown) that are operated by the vehicle control device 11. In the traveling device 12, the gear of the transmission 124 is switched to a forward gear, a reverse gear, etc., and the speed change ratio is operated to control the rotation speed of the front wheels 122 and the rear wheels 123 in response to the operation of the shift lever by the vehicle control device 11. The traveling mode of the work vehicle 10 is switched to forward or reverse, etc. The vehicle control device 11 also operates the accelerator to control the rotation speed of the engine 121. The vehicle control device 11 also operates the brake to brake the rotation of the front wheels 122 and the rear wheels 123 using an electromagnetic brake.

[0027] The positioning device 14 is a communication device including a control unit 141, a memory unit 142, a communication unit 143, and a positioning antenna 144. For example, as shown in FIG. 3, the positioning device 14 is provided on the upper part of a cabin 17 in which a user boards. The location of the positioning device 14 is not limited to the cabin 17. The control unit 141, the memory unit 142, the communication unit 143, and the positioning antenna 144 of the positioning device 14 may be disposed in different positions in the work vehicle 10. As described above, the battery is connected to the positioning device 14, and the positioning device 14 can operate even when the engine 121 is stopped. The positioning device 14 may be substituted with, for example, a mobile phone terminal, a smartphone, or a tablet terminal.

[0028] The control unit 141 is a computer system including one or more processors and storage memories such as a non-volatile memory and a RAM. The storage unit 142 is a non-volatile memory that stores a positioning program for causing the control unit 141 to execute a positioning process (see FIG. 9) described later, and positioning information D1 (see FIG. 5) and movement information D2 (see FIG. 6) described later. For example, the positioning program is non-temporarily recorded on a computer-readable recording medium such as a CD or a DVD, and is read by a predetermined reading device (not shown) and stored in the storage unit 142. The positioning program may be downloaded from a server (not shown) to the positioning device 14 via a communication network N1 and stored in the storage unit 142.

[0029] The communication unit 143 is a communication interface for connecting the positioning device 14 to the communication network N1 by wire or wirelessly, and for executing data communication with an external device such as the base station server 20 via the communication network N1 in accordance with a predetermined communication protocol.

[0030] The positioning antenna 144 is an antenna that receives radio waves (GNSS signals) transmitted from the satellites 40.

[0031] The control unit 141 includes various processing units such as a first positioning processing unit 151, a transmission processing unit 152, an acquisition processing unit 153, and a second positioning processing unit 154. The control unit 141 functions as the various processing units by executing various processes according to the positioning program. In another embodiment, a part or all of the first positioning processing unit 151, the transmission processing unit 152, the acquisition processing unit 153, and the second positioning processing unit 154 may be configured with an electronic circuit.

[0032] The first positioning processing unit 151 calculates the position of the work vehicle 10 based on the GNSS signal (an example of a satellite signal of the present invention) received by the positioning antenna 144 from the satellite 40. For example, when the work vehicle 10 autonomously travels in the field F, when the positioning antenna 144 receives radio waves (such as transmission time and orbit information) transmitted from each of the multiple satellites 40, the first positioning processing unit 151 calculates the distance between the positioning antenna 144 and each satellite 40, and calculates the position (latitude and longitude) of the work vehicle 10 based on the calculated distance. In this way, the first positioning processing unit 151 calculates the position of the work vehicle 10 by so-called independent positioning (corresponding to the first positioning of the present invention). The first positioning processing unit 151 records positioning information (hereinafter referred to as "independent positioning information") corresponding to the calculated position in the positioning information D1 of the storage unit 142. The first positioning processing unit 151 is an example of the first positioning processing unit of the present invention.

[0033] Fig. 5 is a diagram showing an example of positioning information D1. Positioning information D1 includes independent positioning information and transmitted positioning information. A first positioning processing unit 151 calculates the independent positioning information based on a GNSS signal received from a satellite 40. In Fig. 5, the independent positioning information is shown as X1 to X15 and Y1 to Y15, but the actual independent positioning information includes latitude and longitude indicating the position of the work vehicle 10 instead of X1 to X15 and Y1 to Y15. Note that although time information is shown in the positioning information D1 shown in Fig. 5, the time information does not have to be included in the positioning information D1.

[0034] The transmission processing unit 152 transmits the positioning information (independent positioning information) corresponding to the position of the work vehicle 10 calculated by the first positioning processing unit 151 to the base station server 20.

[0035] Specifically, the transmission processing unit 152 transmits the individual positioning information to the base station server 20 at a predetermined cycle (for example, one second cycle) in a predetermined transmission data format. For example, the transmission processing unit 152 transmits a GGA message (sentence) including time, latitude, and longitude corresponding to the individual positioning information to the base station server 20 at one second cycle according to the NMEA0183 data transmission standard. The GGA message is an example of positioning information (the individual positioning information) of the present invention. The transmission processing unit 152 is an example of a transmission processing unit of the present invention.

[0036] Furthermore, the transmission processing unit 152 records the independent positioning information to be transmitted to the base station server 20 in positioning information D1 (see FIG. 5) as transmitted positioning information. In FIG. 5, the transmitted positioning information is shown as X1 to X12 and Y1 to Y12, but the actual transmitted positioning information includes latitude and longitude indicating the position of the work vehicle 10 instead of X1 to X12 and Y1 to Y12. Furthermore, the independent positioning information and the transmitted positioning information are recorded in positioning information D1 in association with each other.

[0037] When the base station server 20 receives the transmitted positioning information (the independent positioning information) transmitted from the transmission processing unit 152, it selects one base station 30 from among the multiple base stations 30 based on the position of the work vehicle 10, and generates the correction information based on the GNSS signal received by the selected base station 30 from the satellite 40. The correction information includes positioning information of the position calculated by the base station 30 based on the GNSS signal, reference position information of the position where the base station 30 is installed, time information, etc. The base station server 20 transmits the generated correction information to the work vehicle 10. A specific configuration of the base station server 20 will be described later.

[0038] The acquisition processing unit 153 acquires the correction information from the base station server 20. The acquisition processing unit 153 acquires the correction information from the base station server 20 in real time, for example, while the work vehicle 10 is autonomously traveling. The acquisition processing unit 153 records the acquired correction information in movement information D2. The acquisition processing unit 153 is an example of the acquisition processing unit of the present invention.

[0039] FIG. 6 is a diagram showing an example of movement information D2. The movement information D2 includes independent positioning information, correction information, and location information. When the acquisition processing unit 153 acquires the correction information from the base station server 20, it records the correction information in the movement information D2 in association with the independent positioning information. In FIG. 6, the correction information is shown as Xs3 to Xs15 and Ys3 to Ys15, but the actual correction information includes latitude and longitude indicating the position of the base station 30 (positioning information, reference position information, etc.), time information, etc., instead of Xs3 to Xs15 and Ys3 to Ys15. Note that although time information is shown in the movement information D2 shown in FIG. 6, the time information does not have to be included in the movement information D2.

[0040] The second positioning processing unit 154 executes RTK positioning (corresponding to specific positioning and second positioning of the present invention) that calculates the position of the work vehicle 10 based on the correction information acquired by the acquisition processing unit 153. For example, the second positioning processing unit 154 corrects the independent positioning information of the work vehicle 10 based on the signal received from the satellite 40 based on the correction information corresponding to the positioning information of the selected base station 30 to calculate the current position of the work vehicle 10. The second positioning processing unit 154 records the calculated position information indicating the current position of the work vehicle 10 in the movement information D2 (see FIG. 6). The current position of the work vehicle 10 is calculated as described above. While the positioning device 14 calculates the current position of the work vehicle 10, the vehicle control device 11 executes autonomous driving processing of the work vehicle 10 based on the current position and a driving route generated in advance. The second positioning processing unit 154 is an example of the second positioning processing unit of the present invention.

[0041] [Base station server 20] 2, the base station server 20 is a server including a control unit 21, a storage unit 22, and a communication unit 23. The base station server 20 is not limited to a single computer, and may be a computer system in which multiple computers work together. Various processes executed by the base station server 20 may be executed in a distributed manner by one or multiple processors.

[0042] The communication unit 23 is a communication interface that connects the base station server 20 to the communication network N1 via a wired or wireless connection, and performs data communication in accordance with a predetermined communication protocol with external devices such as one or more work vehicles 10 via the communication network N1.

[0043] The storage unit 22 is a non-volatile storage unit such as an HDD (Hard Disk Drive) or an SSD (Solid State Drive) that stores various information. The storage unit 22 stores a control program for causing the control unit 21 to execute various processes. For example, the control program is non-temporarily recorded on a computer-readable recording medium such as a CD or a DVD, and is read by a reading device (not shown) such as a CD drive or a DVD drive provided in the base station server 20 and stored in the storage unit 22. The control program may be downloaded from a server (not shown) to the base station server 20 via the communication network N1 and stored in the storage unit 22.

[0044] The storage unit 22 also includes data such as base station information D3. Fig. 7 is a diagram showing an example of the base station information D3. The base station information D3 includes a base station name, reference position information, and the like. The base station name is the name (identification information) of each of all base stations 30 included in the positioning system 1. The reference position information is position information (latitude and longitude) indicating the installation position of the base station 30. The base station 30 is installed by a telecommunications carrier, a local government, or the like, and the base station name and the reference position information are registered in the base station information D3 when the base station 30 is installed.

[0045] The control unit 21 includes various processing units such as a reception processing unit 211, a selection processing unit 212, a generation processing unit 213, and a transmission processing unit 214. The control unit 21 functions as the various processing units by executing various processes according to the control program. In another embodiment, the reception processing unit 211, the selection processing unit 212, the generation processing unit 213, and the transmission processing unit 214 may be partially or entirely configured with electronic circuits.

[0046] The reception processing unit 211 receives positioning information (independent positioning information) corresponding to the position of the work vehicle 10 calculated by the first positioning processing unit 151 of the positioning device 14 mounted on the work vehicle 10 from the positioning device 14. Specifically, the reception processing unit 211 receives the independent positioning information (see FIG. 5) transmitted by the transmission processing unit 152 of the positioning device 14 at a predetermined period (for example, one second period).

[0047] The selection processing unit 212 selects one base station 30 from among the multiple base stations 30 based on the position of the work vehicle 10. Specifically, the selection processing unit 212 selects one base station 30 that is closest to the position of the work vehicle 10 corresponding to the independent positioning information received by the reception processing unit 211 from among the multiple base stations 30 included in the pre-registered base station information D3.

[0048] FIG. 8 illustrates a field F and a work vehicle 10 performing work within the field F. The field F is located between two base stations 30A, 30B. When the work vehicle 10 is located at point P1 where work is to begin, the reception processing unit 211 receives the independent positioning information corresponding to point P1 from the positioning device 14. In this case, the selection processing unit 212 selects the base station 30 (here, base station 30A) closest to point P1 from among the multiple base stations 30 included in the base station information D3.

[0049] The generation processing unit 213 generates the correction information for correcting the position (single positioning information) of the work vehicle 10 calculated by the first positioning processing unit 151 of the positioning device 14. Specifically, the generation processing unit 213 generates the correction information based on the GNSS signal (satellite signal) received from the satellite 40 by the base station 30 selected by the selection processing unit 212. In the example shown in FIG. 8, the generation processing unit 213 generates the correction information for the work vehicle 10 based on the GNSS signal received from the satellite 40 by the base station 30A. The correction information includes positioning information of the position calculated by the base station 30A based on the GNSS signal, reference position information of the position where the base station 30A is installed (see "Xa, Ya" in FIG. 7), and time information.

[0050] The transmission processing unit 214 transmits the correction information generated by the generation processing unit 213 to the work vehicle 10. When the work vehicle 10 acquires the correction information transmitted for the first time from the base station server 20, positioning by the RTK method (RTK positioning) is started. That is, when the work vehicle 10 acquires the correction information corresponding to the selected base station 30 transmitted for the first time from the base station server 20, RTK positioning based on the correction information corresponding to the base station 30 becomes possible. In this embodiment, the "state in which RTK positioning based on correction information corresponding to a selected base station 30 (base station 30A in the above example) is possible" is also referred to as the "state in which communication between the work vehicle 10 and the base station 30 (base station 30A) is established."

[0051] As described above, the positioning system 1 uses the RTK method to measure the position of the work vehicle 10. Furthermore, the work vehicle 10 performs autonomous driving using positioning information obtained by the RTK method.

[0052] However, for example, when a field F is located at the midpoint between two base stations 30, there is a possibility that the base station 30 may be switched while the work vehicle 10 is autonomously traveling in the field F. For example, as shown in FIG. 8, when the midpoint C0 between the base station 30A and the base station 30B is located in the field F, the field F includes a first area F1 on the base station 30A side of the midpoint C0, and a second area F2 on the base station 30B side of the midpoint C0. In this case, the work vehicle 10 autonomously travels in the first area F1 while acquiring position information calculated using the correction information corresponding to the base station 30A. However, when the work vehicle 10 passes the midpoint C0 and enters the second area F2, the base station 30B becomes the base station closest to the work vehicle 10, and the base station 30 that establishes communication with the work vehicle 10 is switched. As a result, the correction information is switched in the work vehicle 10, and the positioning calculation by the RTK method is temporarily interrupted, and the autonomous traveling of the work vehicle 10 is interrupted. 8, when the work vehicle 10 is located in the first area F1 and when the work vehicle 10 is located in the second area F2, it is possible to perform RTK positioning of the work vehicle 10 using the correction information corresponding to the base station 30A, and it is also possible to perform RTK positioning of the work vehicle 10 using the correction information corresponding to the base station 30B. That is, in the field F, RTK positioning is possible using the correction information corresponding to each of the multiple base stations 30.

[0053] In contrast, as described below, according to the positioning device 14 of this embodiment, when positioning the work vehicle 10 based on correction information corresponding to a specific base station 30, it is possible to prevent switching of that base station 30.

[0054] Here, an example shown in Fig. 8 will be described. When the work vehicle 10 is located at point P1 in the first area F1, the base station server 20 selects the base station 30A (the base station closest to point P1) based on the single positioning information corresponding to point P1 received from the work vehicle 10, generates correction information corresponding to the selected base station 30A, and transmits it to the work vehicle 10. When the acquisition processing unit 153 of the positioning device 14 acquires the first correction information from the base station server 20, RTK positioning corresponding to the base station 30A becomes possible. That is, communication between the work vehicle 10 and the base station 30A is established.

[0055] When RTK positioning of the work vehicle 10 based on the correction information corresponding to the base station 30A (corresponding to the second positioning of the present invention) becomes possible, the transmission processing unit 152 of the positioning device 14 transmits to the base station server 20 the same positioning information as the independent positioning information immediately before RTK positioning of the work vehicle 10 based on the correction information corresponding to the base station 30A becomes possible. The independent positioning information includes at least latitude information, longitude information, and time information. For example, when RTK positioning of the work vehicle 10 becomes possible, the transmission processing unit 152 transmits to the base station server 20 the longitude information immediately before RTK positioning of the work vehicle 10 becomes possible, and the same latitude information and longitude information as the latitude information.

[0056] For example, assume that the positioning device 14 transmits independent positioning information "X3, Y3" (see FIG. 5) to the base station server 20, the base station server 20 selects the base station 30A based on the independent positioning information "X3, Y3", the selected base station 30A generates correction information based on the GNSS signal received from the satellite 40, and transmits the first correction information to the work vehicle 10. The positioning device 14 acquires the first correction information from the base station server 20, thereby enabling RTK positioning of the work vehicle 10 based on the correction information corresponding to the base station 30A. In this case, the transmission processing unit 152 of the positioning device 14 transmits to the base station server 20 the positioning information "X3, Y3" that is the same as the independent positioning information "X3, Y3" transmitted immediately before RTK positioning of the work vehicle 10 based on the correction information corresponding to the base station 30A becomes possible, as shown in FIG. 5. That is, the transmitted positioning information transmitted from the positioning device 14 to the base station server 20 is fixed to the independent positioning information "X3, Y3" immediately before RTK positioning of the work vehicle 10 based on the correction information corresponding to the base station 30A becomes possible (see Figure 5).

[0057] As a result, the transmission processing unit 152 continues to transmit the same single positioning information "X3, Y3" to the base station server 20 regardless of the position of the work vehicle 10 while RTK positioning of the work vehicle 10 based on the correction information corresponding to the base station 30A is possible. For example, in the example shown in FIG. 8, when RTK positioning of the work vehicle 10 based on the correction information corresponding to the base station 30A is possible at all positions in the field F, even if the work vehicle 10 moves from the first area F1 to point P2 in the second area F2, the transmission processing unit 152 continues to transmit the single positioning information "X3, Y3" corresponding to the position in the first area F1 to the base station server 20. For this reason, the base station server 20 continues to select the base station 30A and does not select the base station 30B in order to receive the same single positioning information "X3, Y3" (transmission positioning information) regardless of the actual position of the work vehicle 10. Then, the base station server 20 continues to transmit the correction information corresponding to the base station 30A to the work vehicle 10. As a result, the positioning device 14 continues to receive the correction information corresponding to the base station 30A without interruption and continues to calculate the current position of the work vehicle 10 while the work vehicle 10 is traveling at least within the field F. This makes it possible to prevent the autonomous traveling of the work vehicle 10 within the field F from being interrupted.

[0058] In this way, when RTK positioning of the work vehicle 10 based on the correction information corresponding to the base station 30A becomes possible, the acquisition processing unit 153 of the positioning device 14 acquires the correction information generated based on the GNSS signal received by the base station 30A from the satellite 40 from the base station server 20, and the second positioning processing unit 154 positions the work vehicle 10 based on the correction information corresponding to the base station 30A acquired by the acquisition processing unit 153. Specifically, when RTK positioning of the work vehicle 10 based on the correction information corresponding to the base station 30A becomes possible, in each of the cases where the work vehicle 10 is located in a location (first area F1 in FIG. 8) closer to the base station 30A than the base station 30B and where the work vehicle 10 is located in a location (second area F2 in FIG. 8) closer to the base station 30B than the base station 30A, the acquisition processing unit 153 acquires the correction information corresponding to the base station 30A from the base station server 20, and the second positioning processing unit 154 calculates the position of the work vehicle 10 based on the correction information corresponding to the base station 30A acquired by the acquisition processing unit 153. In other words, when RTK positioning of the work vehicle 10 based on correction information corresponding to base station 30A becomes possible, the second positioning processing unit 154 locates the position of the work vehicle 10 based on the correction information corresponding to base station 30A, both when the work vehicle 10 is traveling in the first area F1 and when the work vehicle 10 is traveling in the second area F2.

[0059] Furthermore, when RTK positioning of the work vehicle 10 based on correction information corresponding to the base station 30A becomes possible, even if the work vehicle 10 moves from a location close to the base station 30A (first area F1 in FIG. 8) to a location close to the base station 30B (second area F2 in FIG. 8), the acquisition processing unit 153 acquires the correction information corresponding to the base station 30A from the base station server 20, and the second positioning processing unit 154 locates the position of the work vehicle 10 based on the correction information corresponding to the base station 30A acquired by the acquisition processing unit 153. In this way, the positioning device 14 calculates the current position of the work vehicle 10.

[0060] [Positioning processing] An example of the positioning process executed by the control unit 141 of the positioning device 14 will be described below with reference to Fig. 9. For example, the positioning process is started by the control unit 141 when the control unit 141 receives a satellite signal (GNSS signal) from a satellite 40. The positioning process may also be started in response to a predetermined user operation on the work vehicle 10 equipped with the positioning device 14.

[0061] The present invention may be understood as an invention of a positioning method in which the control unit 141 executes part or all of the positioning process, or an invention of a positioning program for causing the control unit 141 to execute part or all of the positioning method. The positioning process may be executed by one or more processors. For example, the positioning process may be executed by the control unit 141 of the positioning device 14 and the control unit 21 of the base station server 20 in cooperation with each other.

[0062] In step S1, the control unit 141 starts a reception process for receiving a GNSS signal from a satellite 40. For example, the control unit 141 receives radio waves (GNSS signals) including transmission time, orbit information, and the like from each of the multiple (four) satellites 40.

[0063] In step S2, the control unit 141 (first positioning processing unit 151) starts independent positioning to calculate the position of the work vehicle 10 based on the GNSS signal received from the satellite 40. The control unit 141 records positioning information (independent positioning information) corresponding to the calculated position in positioning information D1 (see FIG. 5) of the memory unit 142.

[0064] In step S3, the control unit 141 (transmission processing unit 152) starts a transmission process for transmitting the independent positioning information corresponding to the position of the work vehicle 10 calculated in step S2 to the base station server 20. For example, the control unit 141 transmits a GGA message including the time, latitude, and longitude corresponding to the independent positioning information to the base station server 20 at one-second intervals according to the NMEA0183 data transmission standard. In addition, the control unit 141 records the independent positioning information to be transmitted to the base station server 20 in the positioning information D1 (see FIG. 5) as transmitted positioning information.

[0065] The base station server 20 selects the base station 30 closest to the work vehicle 10 based on the individual positioning information transmitted from the positioning device 14, generates correction information corresponding to the selected base station 30, and transmits it to the work vehicle 10.

[0066] In step S4, the control unit 141 determines whether RTK positioning has become possible. For example, when the control unit 141 acquires the first correction information from the base station server 20, the control unit 141 determines that RTK positioning has become possible (S4: Yes), and the process proceeds to step S5. The control unit 141 waits until acquiring the first correction information from the base station server 20 (S4: No). For example, in the example shown in FIG. 8, when the control unit 141 acquires the first correction information corresponding to the base station 30A from the base station server 20, the control unit 141 determines that RTK positioning based on the correction information corresponding to the base station 30A has become possible.

[0067] In step S5, the control unit 141 (transmission processing unit 152) fixes the independent positioning information (transmitted positioning information) to be transmitted to the base station server 20 to the independent positioning information (see "X3, Y3" in FIG. 5) immediately before RTK positioning of the work vehicle 10 becomes possible based on the correction information corresponding to the base station 30A. That is, in the above example, the control unit 141 transmits the independent positioning information "X3, Y3" (GGA message) to the base station server 20 at one-second intervals. In addition, the control unit 141 transmits only the latitude information and longitude information ("X3, Y3") of the independent positioning information to the base station server 20 at one-second intervals. Note that the time information included in the GGA message is updated.

[0068] In step S6, the control unit 141 (acquisition processing unit 153) determines whether or not the correction information has been acquired from the base station server 20. Here, the control unit 141 determines whether or not the correction information corresponding to the base station 30A has been acquired. If the control unit 141 has acquired the correction information (S6: Yes), the process proceeds to step S7. The control unit 141 waits until the correction information is acquired (S6: No).

[0069] After the individual positioning information is fixed, the control unit 141 continues to transmit the same individual positioning information ("X3, Y3") to the base station server 20. The base station server 20 also selects a base station 30A based on the individual positioning information ("X3, Y3") transmitted from the positioning device 14, and continues to generate and transmit correction information corresponding to the selected base station 30A to the work vehicle 10. As a result, the control unit 141 continues to obtain correction information corresponding to the same base station 30A regardless of the position of the work vehicle 10.

[0070] In step S7, the control unit 141 (second positioning processing unit 154) corrects the position corresponding to the individual positioning information of the work vehicle 10 calculated in step S2 based on the correction information acquired in step S6, to calculate the current position of the work vehicle 10. Here, the control unit 141 corrects the position corresponding to the individual positioning information based on the correction information corresponding to the base station 30A to calculate the current position of the work vehicle 10. Also, as shown in FIG. 8, whether the work vehicle 10 is located in the first area F1 or the second area F2, the control unit 141 calculates the current position of the work vehicle 10 using the correction information corresponding to the base station 30A.

[0071] In step S8, the control unit 141 determines whether or not the work by the work vehicle 10 has been completed. For example, when the work by the work vehicle 10 has completed work in all areas within the field F, i.e., when autonomous travel along the set travel route has been completed, the control unit 141 determines that the work by the work vehicle 10 has been completed (S8: Yes). When the work is completed, the control unit 141 ends the positioning process. On the other hand, when the control unit 141 determines that the work by the work vehicle 10 has not been completed (S8: No), the process proceeds to step S6. When proceeding to step S6, the control unit 141 continues the process of acquiring the correction information from the base station server 20 and calculating the current position of the work vehicle 10. In this manner, the control unit 141 executes the positioning process.

[0072] Incidentally, when the distance L10 between the work vehicle 10 and the base station 30 becomes equal to or greater than a predetermined distance, the communication environment with the base station 30 deteriorates and the positioning device 14 is no longer able to perform positioning (RTK positioning) of the moving body to be positioned (the work vehicle 10 in this embodiment). For example, when the work vehicle 10 (positioning device 14) is 5 km or more away from the base station 30A, the positioning device 14 is no longer able to perform RTK positioning of the work vehicle 10 based on the correction information corresponding to the base station 30A.

[0073] In the example shown in FIG. 8, for example, when the distance L10 between the work vehicle 10 and the base station 30A is less than a predetermined distance regardless of where the work vehicle 10 is located in the field F, the positioning device 14 can perform RTK positioning based on the correction information corresponding to the base station 30A. However, for example, as shown in FIG. 10, when the work vehicle 10 moves to a point P4 outside the field F and the distance L10 between the work vehicle 10 and the base station 30A becomes greater than or equal to a predetermined distance, a problem occurs in which the positioning device 14 cannot perform RTK positioning of the work vehicle 10 based on the correction information corresponding to the base station 30A. The predetermined distance at which the positioning device 14 can perform RTK positioning based on the correction information corresponding to the base station 30A varies depending on the communication environment between the positioning device 14 and the base station 30, etc. For this reason, for example, when the positioning device 14 is in a state where RTK positioning is possible based on the correction information corresponding to the base station 30A, if the work vehicle 10 moves too far away from the base station 30A, the positioning device 14 cannot perform the RTK positioning at that time.

[0074] Therefore, when RTK positioning of the work vehicle 10 based on the correction information corresponding to the base station 30A becomes impossible, the transmission processing unit 152 releases the fixation of the individual positioning information and transmits to the base station server 20 the individual positioning information corresponding to the position of the work vehicle 10 calculated by the first positioning processing unit 151 after RTK positioning of the work vehicle 10 based on the correction information corresponding to the base station 30A becomes impossible.

[0075] For example, in Fig. 5, time t9 represents the time when RTK positioning of the work vehicle 10 based on the correction information corresponding to the base station 30A becomes impossible due to the movement of the work vehicle 10. When RTK positioning of the work vehicle 10 based on the correction information corresponding to the base station 30A becomes impossible, the transmission processing unit 152 releases the fixation of the independent positioning information "X3, Y3" and transmits independent positioning information "X9, Y9" corresponding to the position of the work vehicle 10 calculated by the first positioning processing unit 151 after the release to the base station server 20. Thereafter, the transmission processing unit 152 sequentially transmits new independent positioning information calculated by the first positioning processing unit 151 according to the position of the work vehicle 10 to the base station server 20.

[0076] Furthermore, when the fixation of the independent positioning information "X3, Y3" is released, for example, when the work vehicle 10 moves beyond the waypoint C0 toward the base station 30B, the base station server 20 selects the base station 30B to acquire the independent positioning information on the base station 30B side. Then, the base station server 20 generates correction information based on the GNSS signal that the base station 30B receives from the satellite 40 and transmits it to the positioning device 14. In the positioning device 14, the acquisition processing unit 153 acquires the correction information corresponding to the base station 30B from the base station server 20, and the second positioning processing unit 154 positions the position corresponding to the independent positioning information of the work vehicle 10 calculated by the first positioning processing unit 151 based on the correction information corresponding to the base station 30B acquired by the acquisition processing unit 153, thereby calculating the current position of the work vehicle 10.

[0077] The above-described configuration of calculating the current position of the work vehicle 10 by switching the base station 30 that establishes communication with the work vehicle 10 is effective, for example, when the work vehicle 10 moves to a field Fb after finishing work in a field Fa and continues work in the field Fb, as shown in Fig. 11. In the example shown in Fig. 11, the work vehicle 10 starts work at a point P5 in the field Fb. At the point P5, the distance L10 between the work vehicle 10 and the base station 30B is less than a predetermined distance.

[0078] When the work vehicle 10 is located at the point P5 where the work is to be started, the transmission processing unit 152 transmits the independent positioning information "X12, Y12" (see FIG. 5) corresponding to the position of the work vehicle 10 calculated by the first positioning processing unit 151 to the base station server 20. The reception processing unit 211 of the base station server 20 receives the independent positioning information "X12, Y12" corresponding to the point P5 from the positioning device 14. In this case, the selection processing unit 212 selects the base station 30B closest to the point P5 from among the multiple base stations 30 included in the base station information D3. The generation processing unit 213 generates the correction information for the work vehicle 10 based on the GNSS signal that the base station 30B receives from the satellite 40, and the transmission processing unit 214 transmits the generated correction information corresponding to the base station 30B to the work vehicle 10. When the work vehicle 10 acquires the correction information corresponding to the selected base station 30B that is first transmitted from the base station server 20, RTK positioning based on the correction information corresponding to the base station 30B becomes possible.

[0079] 5, the transmission processing unit 152 of the positioning device 14 transmits to the base station server 20 the positioning information "X12, Y12" which is the same as the independent positioning information "X12, Y12" transmitted immediately before RTK positioning of the work vehicle 10 based on the correction information corresponding to the base station 30B becomes possible. That is, the transmitted positioning information transmitted from the positioning device 14 to the base station server 20 is fixed to the independent positioning information "X12, Y12" immediately before RTK positioning of the work vehicle 10 based on the correction information corresponding to the base station 30B becomes possible (see FIG. 5).

[0080] As a result, while RTK positioning of the work vehicle 10 based on the correction information corresponding to the base station 30B is possible, the transmission processing unit 152 continues to transmit the same single positioning information "X12, Y12" to the base station server 20 regardless of the position of the work vehicle 10. Then, when RTK positioning of the work vehicle 10 based on the correction information corresponding to the base station 30B is possible at all positions in the field Fb, the transmission processing unit 152 continues to transmit the same single positioning information "X12, Y12" to the base station server 20. Therefore, the base station server 20 receives the same single positioning information "X12, Y12" (transmitted positioning information) regardless of the actual position of the work vehicle 10, so it continues to select the base station 30B and does not select another base station 30. Then, the base station server 20 continues to transmit the correction information corresponding to the base station 30B to the work vehicle 10. As a result, while the work vehicle 10 is traveling at least within the field Fb, the positioning device 14 continues to receive the correction information corresponding to the base station 30B without interruption and continues to calculate the current position of the work vehicle 10. This makes it possible to prevent the autonomous traveling of the work vehicle 10 within the field Fb from being interrupted.

[0081] An example of the positioning process corresponding to the example shown in Figures 10 and 11 will be described with reference to Figure 12. In the positioning process shown in Figure 12, the same steps as those in the positioning process shown in Figure 9 are given the same step numbers and their description will be omitted. In the positioning process shown in Figure 12, steps S81 and S82 are further added to the positioning process shown in Figure 9.

[0082] In step S8, if the control unit 141 determines that the work by the work vehicle 10 has not been completed (S8: No), the process proceeds to step S81.

[0083] In step S81, the control unit 141 determines whether it has become impossible to perform RTK positioning of the work vehicle 10 based on the correction information corresponding to the base station 30A that has established communication with the work vehicle 10. If the control unit 141 determines that RTK positioning corresponding to the base station 30A has become impossible (S81: Yes), the process proceeds to step S82. On the other hand, if the control unit 141 determines that RTK positioning corresponding to the base station 30A is possible (S81: No), the process proceeds to step S6.

[0084] In step S82, the control unit 141 releases the fixation of the independent positioning information. For example, as shown in Fig. 10, when the work vehicle 10 moves from point P3 to point P4 and is unable to acquire the correction information from the base station 30A, making RTK positioning impossible, the control unit 141 releases the fixation of the independent positioning information "X3, Y3" (see Fig. 5). After releasing the fixation of the independent positioning information "X3, Y3", the control unit 141 then starts transmitting the independent positioning information according to the position of the work vehicle 10 in step S3.

[0085] After that, in step S4, the control unit 141 determines whether or not RTK positioning has become possible for the work vehicle 10. Here, for example, in the example shown in Fig. 10 and Fig. 11, when the control unit 141 acquires the first correction information corresponding to the base station 30B from the base station server 20, it determines that RTK positioning based on the correction information corresponding to the base station 30B has become possible (S4: Yes).

[0086] Also, in step S5, the control unit 141 fixes the independent positioning information (transmitted positioning information) to be transmitted to the base station server 20 to the independent positioning information (see "X12, Y12" in FIG. 5) immediately before RTK positioning of the work vehicle 10 becomes possible based on the correction information corresponding to the base station 30B. Then, the control unit 141 acquires the correction information corresponding to the base station 30B (step S6), corrects the position corresponding to the independent positioning information of the work vehicle 10 calculated in step S2 based on the correction information acquired in step S6, and calculates the current position of the work vehicle 10 (step S7).

[0087] As described above, the positioning device 14 calculates (single-unit positioning) the position (single-unit positioning information) of the moving body (work vehicle 10) based on the satellite signal (GNSS signal) received from the satellite 40, and transmits the calculated single-unit positioning information to the base station server 20. The base station server 20 selects one base station 30 from among the multiple base stations 30 based on the single-unit positioning information, generates correction information corresponding to the selected base station 30, and transmits it to the positioning device 14. When the positioning device 14 acquires the correction information from the base station server 20, it positions the work vehicle 10 based on the correction information. In addition, when the positioning device 14 becomes capable of RTK positioning of the moving body based on the correction information corresponding to the selected base station 30, it transmits to the base station server 20 the same positioning information as the single-unit positioning information transmitted immediately before the RTK positioning of the moving body based on the correction information becomes possible. In this way, the positioning device 14 fixes the position information of the single-unit positioning information so that the base station server 20 does not switch the base station 30. This makes it possible to prevent the base station 30 corresponding to the correction information from being switched while the work vehicle 10 is autonomously traveling in the field F, for example, when the field F is located midway between two base stations (see FIG. 8). This makes it possible to prevent, for example, a situation in which reception of the correction information from the base station server 20 is cut off and the autonomous traveling of the work vehicle 10 is interrupted.

[0088] [Other embodiments] Other embodiments of the positioning system 1 according to this embodiment will be described below.

[0089] In another embodiment, the positioning device 14 may set in advance a range in which RTK positioning is possible (hereinafter referred to as the "positioning possible range AR"). For example, the positioning device 14 sets a range of a radius R (e.g., 5 km) centered on the work vehicle 10 (positioning device 14) as the positioning possible range AR.

[0090] In the example shown in Fig. 13, for example, RTK positioning is possible when the base station 30A is included in the positioning range AR regardless of where the work vehicle 10 is located in the field F. However, for example, when the work vehicle 10 is located at point P4 outside the field F, the base station 30A falls outside the positioning range AR. Note that in Fig. 13, "AR4" indicates the positioning range AR corresponding to point P4, and "AR3" indicates the positioning range AR corresponding to point P3. In this case, the positioning device 14 will not be able to perform RTK positioning of the work vehicle 10 based on the correction information corresponding to the base station 30A.

[0091] The control unit 141 determines whether the base station 30A is within the positioning range AR based on the positioning information of the base station 30A included in the correction information, and when the base station 30A is out of the positioning range AR, determines that RTK positioning of the work vehicle 10 based on the correction information corresponding to the base station 30A has become impossible. That is, when the base station 30A is located within a predetermined range (positioning range AR) from the work vehicle 10, RTK positioning of the work vehicle 10 based on the correction information corresponding to the base station 30A becomes possible, and when the base station 30A is located outside the predetermined range from the work vehicle 10, RTK positioning of the work vehicle 10 based on the correction information corresponding to the base station 30A becomes impossible.

[0092] When RTK positioning of the work vehicle 10 based on the correction information corresponding to the base station 30A becomes impossible, the transmission processing unit 152 releases the fixation of the individual positioning information and transmits to the base station server 20 the individual positioning information corresponding to the position of the work vehicle 10 calculated by the first positioning processing unit 151 after RTK positioning of the work vehicle 10 based on the correction information corresponding to the base station 30A becomes impossible.

[0093] Thereafter, for example, when the work vehicle 10 moves beyond the waypoint C0 toward the base station 30B, the base station server 20 selects the base station 30B to acquire the independent positioning information on the base station 30B side. The base station server 20 then generates correction information based on the GNSS signal that the base station 30B receives from the satellite 40 and transmits it to the positioning device 14. In the positioning device 14, the acquisition processing unit 153 acquires the correction information corresponding to the base station 30B from the base station server 20, and the second positioning processing unit 154 positions the position corresponding to the independent positioning information of the work vehicle 10 calculated by the first positioning processing unit 151 based on the correction information corresponding to the base station 30B acquired by the acquisition processing unit 153, thereby calculating the current position of the work vehicle 10.

[0094] Here, as shown in FIG. 14, when a field Fb is present on the side of base station 30B, and the work vehicle 10 moves to field Fb after completing work in field Fa and continues work in field Fb, the positioning device 14 calculates the current position of the work vehicle 10 by performing processing similar to that in the above-described embodiment.

[0095] In another embodiment, the positioning device 14 may be configured to measure the distance between the work vehicle 10 and the base stations 30, and switch the base station 30 that is the target of RTK positioning to the base station 30 that is closer to the work vehicle 10. For example, as shown in Fig. 11, when the work vehicle 10 is located in a field Fb, the positioning device 14 switches the base station 30 that is the target of RTK positioning from base station 30A to base station 30B when the work vehicle 10 moves beyond the midpoint C0 toward the base station 30B.

[0096] Specifically, when the base station 30 closest to the work vehicle 10 changes from base station 30A to base station 30B, the transmission processing unit 152 releases the fixation of the independent positioning information and transmits the independent positioning information corresponding to the position of the work vehicle 10 calculated by the first positioning processing unit 151 to the base station server 20. As a result, the base station server 20 selects the base station 30B to acquire the independent positioning information on the base station 30B side. Then, the base station server 20 generates correction information based on the GNSS signal that the base station 30B receives from the satellite 40 and transmits it to the positioning device 14. In the positioning device 14, the acquisition processing unit 153 acquires the correction information corresponding to the base station 30B from the base station server 20, and the second positioning processing unit 154 positions the position corresponding to the independent positioning information of the work vehicle 10 calculated by the first positioning processing unit 151 based on the correction information corresponding to the base station 30B acquired by the acquisition processing unit 153, thereby calculating the current position of the work vehicle 10.

[0097] In this way, the positioning device 14 may monitor the distance between the work vehicle 10 and the base station 30, and automatically switch the base station 30 that is the subject of RTK positioning to the base station 30 that is closest to the work vehicle 10.

[0098] For example, as shown in FIG. 15, a field F located between two base stations 30A, 30B may be located on the side of one of the base stations (here, the side of base station 30B). That is, the field F includes two divided areas divided at the midpoint between base station 30A and base station 30B, and one divided area is larger than the other divided area. Here, the field F is divided into a first area F1 on the side of base station 30A and a second area F2 on the side of base station 30B, and the second area F2 is larger than the first area F1. When positioning a work vehicle 10 traveling in such a field F, it is desirable to position the work vehicle 10 using correction information corresponding to base station 30B on the side of second area F2, which has a larger area, from the viewpoint of positioning accuracy.

[0099] However, for example, if the base station server 20 selects base station 30A at the time when the work vehicle 10 is located at point P1, generates correction information corresponding to base station 30A and transmits it to the positioning device 14, the positioning device 14 will calculate the current position of the work vehicle 10 using the correction information corresponding to base station 30A regardless of the position of the work vehicle 10 within the field F. For this reason, for example, when the work vehicle 10 is located in the second area F2, the distance between the work vehicle 10 and base station 30A becomes large, and there is a risk that the accuracy of the positioning of the work vehicle 10 will decrease.

[0100] Therefore, as another embodiment, the transmission processing unit 152 transmits independent positioning information corresponding to the large second area F2 (an example of the first divided area of ​​the present invention) to the base station server 20. Furthermore, the acquisition processing unit 153 acquires correction information generated based on the GNSS signal received from the satellite 40 by the base station 30B close to the large second area F2. Then, the second positioning processing unit 154 calculates (locates) the position of the work vehicle 10 based on the correction information acquired by the acquisition processing unit 153.

[0101] Specifically, when the work vehicle 10 is initially located in the small first area F1, the positioning device 14 calculates the current position of the work vehicle 10 based on the independent positioning information. That is, when the work start point is the first area F1, the work vehicle 10 performs autonomous traveling while traveling in the first area F1 using position information calculated based on the independent positioning information calculated by the first positioning processing unit 151. For this reason, the transmission processing unit 152 does not transmit the independent positioning information to the base station server 20 while the work vehicle 10 is traveling in the first area F1.

[0102] Thereafter, when the work vehicle 10 enters the second area F2 having a larger area, the transmission processing unit 152 transmits the independent positioning information within the second area F2 calculated by the first positioning processing unit 151 to the base station server 20. As a result, the base station server 20 selects the base station 30B, generates correction information corresponding to the base station 30B, and transmits it to the positioning device 14. When the positioning device 14 acquires the correction information from the base station server 20 and becomes capable of RTK positioning of the work vehicle 10 based on the correction information, the transmission processing unit 152 transmits to the base station server 20 the same positioning information as the independent positioning information transmitted immediately before RTK positioning of the work vehicle 10 based on the correction information corresponding to the base station 30B becomes possible. In other words, the transmission positioning information transmitted from the positioning device 14 to the base station server 20 is fixed to the independent positioning information immediately before RTK positioning of the work vehicle 10 based on the correction information corresponding to the base station 30B becomes possible.

[0103] Then, when RTK positioning of the work vehicle 10 based on the correction information corresponding to base station 30B becomes possible, the second positioning processing unit 154 calculates the position of the work vehicle 10 based on the correction information corresponding to base station 30B, both when the work vehicle 10 is traveling in the first area F1 and when the work vehicle 10 is traveling in the second area F2.

[0104] As a result, after the single positioning information is fixed, the positioning device 14 becomes able to calculate the current position of the work vehicle 10 using the correction information corresponding to the base station 30B regardless of the position of the work vehicle 10 (first area F1, second area F2) within the field F. In this way, the positioning device 14 calculates the current position of the work vehicle 10 by single positioning in the small first area F1, and when the work vehicle 10 subsequently moves to the large second area F2, it thereafter calculates the current position of the work vehicle 10 by RTK positioning using the correction information corresponding to the base station 30B which is closer to the second area F2.

[0105] Furthermore, when the work vehicle 10 is initially located in the larger second area F2, the configuration shown in the above embodiment makes it possible to calculate the current position of the work vehicle 10 throughout the entire field F using correction information corresponding to the base station 30B.

[0106] In each of the above-described embodiments, a work vehicle is given as an example of a mobile body (mobile station) of the present invention, but the mobile body of the present invention is not limited to a work vehicle. For example, the mobile body of the present invention may be a worker who carries a positioning device 14 and moves. The positioning device of the present invention may be a device that is pre-installed in the vehicle, or may be a portable device that can be carried (detached) in the vehicle. In each of the above-described embodiments, a case in which the work vehicle 10 performs autonomous driving based on the position information calculated by the positioning device 14 is given as an example, but the use of the position information calculated by the positioning device 14 is not limited to the autonomous driving of the work vehicle 10. For example, the position information calculated by the positioning device 14 may be used in the process of creating a driving route for the work vehicle 10, the process of creating a driving trajectory that the work vehicle 10 has traveled during work, and the like.

[0107] A positioning device according to an aspect of the present invention includes a first positioning processor, a transmission processor, an acquisition processor, and a second positioning processor. The first positioning processor executes a first positioning to calculate a position of a mobile object based on a satellite signal received from a satellite. The transmission processor transmits positioning information corresponding to the position of the mobile object calculated by the first positioning processor to a base station server that selects one base station from a plurality of base stations based on the position of the mobile object calculated by the first positioning processor. The acquisition processor acquires correction information generated based on a satellite signal received by the one base station from the satellite from the base station server. The second positioning processor executes a second positioning to calculate a position of the mobile object based on the correction information acquired by the acquisition processor. In addition, when the second positioning of the mobile object based on the first correction information corresponding to the first base station, which is the one base station, becomes possible, the transmission processor transmits to the base station server positioning information that is the same as the positioning information immediately before the second positioning of the mobile object based on the first correction information becomes possible.

[0108] A work vehicle according to one aspect of the present invention includes the positioning device, and a control device that executes driving processing based on position information calculated by the positioning device.

[0109] A positioning method according to one embodiment of the present invention is a positioning method that is executed by one or more processors to perform a first positioning that calculates a position of a mobile object based on a satellite signal received from a satellite, transmit positioning information corresponding to the calculated position of the mobile object to a base station server that selects one base station from a plurality of base stations based on the calculated position of the mobile object, obtain correction information generated based on the satellite signal received by the one base station from the satellite from the base station server, and perform a second positioning that calculates the position of the mobile object based on the correction information. In addition, in the positioning method, when the second positioning of the mobile object based on the first correction information corresponding to a first base station that is the one base station becomes possible, the same positioning information as the positioning information immediately before the second positioning of the mobile object based on the first correction information becomes possible is transmitted to the base station server.

[0110] A positioning program according to one embodiment of the present invention is a positioning program for causing one or more processors to execute the following: performing a first positioning to calculate a position of a mobile object based on a satellite signal received from a satellite; transmitting positioning information corresponding to the calculated position of the mobile object to a base station server that selects one base station from a plurality of base stations based on the calculated position of the mobile object; acquiring correction information generated based on the satellite signal received by the one base station from the satellite from the base station server; and performing a second positioning to calculate the position of the mobile object based on the correction information. In addition, when the second positioning of the mobile object based on the first correction information corresponding to a first base station that is the one base station becomes possible, the positioning program transmits to the base station server positioning information that is the same as the positioning information immediately before the second positioning of the mobile object based on the first correction information becomes possible. [Explanation of symbols]

[0111] 1: Positioning system 10: Work vehicle 14: Positioning device 20: Base station server 30:Base station 40:Satellite 144: Positioning antenna 151: First positioning processing unit 152: Transmission processing unit 153: Acquisition processing unit 154: Second positioning processing unit 211: Receiving processing unit 212: Selection processing unit 213: Generation processing unit 214: Transmission processing unit

Claims

1. One or more processors, When it becomes possible to perform specific positioning in which a position of a moving object is calculated based on correction information generated based on a satellite signal received by a base station from a satellite in a certain field, performing the specific positioning based on the correction information corresponding to the same base station at all positions in the farm field by utilizing positioning information of the position of the moving object in the farm field calculated based on the satellite signal immediately before the specific positioning becomes possible; Positioning method.

2. The one or more processors: When the specific positioning becomes possible, transmit the positioning information immediately before the specific positioning becomes possible to a base station server that selects one base station from among a plurality of base stations based on the positioning information while the specific positioning is possible; performing the specific positioning based on the correction information acquired from the base station server; The positioning method according to claim 1 .

3. When the specific positioning becomes possible, the one or more processors transmit the same positioning information to the base station server while the specific positioning is possible, regardless of the position of the mobile object within the field. The positioning method according to claim 2 .

4. When the specific positioning of the moving body based on the correction information becomes impossible, the one or more processors transmit to the base station server positioning information corresponding to the position of the moving body calculated after the specific positioning of the moving body based on the correction information becomes impossible. The positioning method according to claim 2 or 3.

5. The positioning information includes at least longitude information, latitude information, and time information, When the specific positioning of the mobile object becomes possible, the one or more processors transmit the longitude information and the latitude information immediately before the specific positioning of the mobile object becomes possible to the base station server. The positioning method according to any one of claims 2 to 4.

6. The moving body is a work vehicle that travels in the field, A positioning device that determines the position of the work vehicle by the positioning method according to any one of claims 1 to 5; A control device that executes a driving process based on the position information calculated by the positioning device; A work vehicle equipped with:

7. When it becomes possible to perform specific positioning in which a position of a moving object is calculated based on correction information generated based on a satellite signal received by a base station from a satellite in a certain field, performing the specific positioning based on the correction information corresponding to the same base station at all positions in the farm field by utilizing positioning information of the position of the moving object in the farm field calculated based on the satellite signal immediately before the specific positioning becomes possible; Positioning device.

8. One or more processors, When it becomes possible to perform specific positioning in which a position of a moving object is calculated based on correction information generated based on a satellite signal received by a base station from a satellite in a certain field, A positioning program for performing the specific positioning based on the correction information corresponding to the same base station at all positions in the field by utilizing positioning information of the position of the moving body in the field calculated based on the satellite signal immediately before the specific positioning becomes possible.

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