Automatic Driving Method, Automatic Driving System, and Automatic Driving Program

Abstract

To provide an automatic running method, an automatic running system and an automatic running program capable of maintaining a work precision even if the positioning scheme of a work vehicle changes.SOLUTION: A positioning process unit 181 measures the position of a work vehicle 10 by a predetermined positioning scheme on the basis of satellite signals received from a satellite 20. A running process unit 111 causes the work vehicle 10 to automatically run on the basis of positional information representing the position of the work vehicle 10 measured by the positioning process unit 181. Moreover, when the work vehicle 10 can automatically run by the first positioning scheme and when the positioning scheme changes to a second positioning scheme that has a different positioning precision from that of the first positioning scheme, the running process unit 111 prohibits the automatic running.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an automatic driving method, an automatic driving system, and an automatic driving program capable of automatically driving a work vehicle.

Background Art

[0002] When there are obstacles such as windbreaks and buildings near a work vehicle that is automatically driving, positioning obstacles may occur due to the inability to receive radio waves from satellites or the inability to receive radio waves from a predetermined number of satellites due to radio wave interference. When the positioning obstacle occurs, there is a problem that the work efficiency decreases because the work vehicle stops automatic driving.

[0003] Conventionally, when the positioning obstacle occurs, a system has been proposed that avoids stopping the work vehicle by automatically driving the work vehicle by inertial navigation (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] By the way, known positioning methods for work vehicles include the DGNSS (Differential Global Navigation Satellite System) method and the real-time kinematic method (RTK-GPS positioning method, hereinafter referred to as the "RTK method") which has higher positioning accuracy than the DGNSS method. Since the DGNSS method and the RTK method have different positioning accuracies, for example, when the work vehicle switches to the RTK method while automatically traveling using the DGNSS method, the self-recognized position of the work vehicle before and after the switch of the positioning method will deviate significantly. As a result, since the work vehicle operates to follow the target path immediately after the switch of the positioning method, there arises a problem that the behavior of the work vehicle becomes unstable and the work accuracy decreases.

[0006] An object of the present invention is to provide an automatic driving method, an automatic driving system, and an automatic driving program capable of maintaining work accuracy even when the positioning method of a work vehicle is switched.

Means for Solving the Problems

[0007] The automatic driving method according to the present invention includes positioning the position of a work vehicle by a predetermined positioning method based on satellite signals received from satellites, automatically driving the work vehicle based on position information indicating the position of the positioned work vehicle, and when the work vehicle is in a state where it can automatically travel by a first positioning method, prohibiting automatic driving when the positioning method switches to a second positioning method having a different positioning accuracy from the first positioning method.

[0008] The automatic driving system according to the present invention includes a positioning processing unit and a driving processing unit. The positioning processing unit measures the position of the work vehicle by a predetermined positioning method based on satellite signals received from satellites. The driving processing unit automatically drives the work vehicle based on position information indicating the position of the work vehicle measured by the positioning processing unit. Further, when the work vehicle is in a state where it can automatically drive by a first positioning method, the driving processing unit can prohibit automatic driving when the positioning method switches to a second positioning method having a different positioning accuracy from the first positioning method.

[0009] The automatic driving program according to the present invention is for causing one or more processors to execute: measuring the position of a work vehicle by a predetermined positioning method based on satellite signals received from satellites; automatically driving the work vehicle based on position information indicating the measured position of the work vehicle; and being able to prohibit automatic driving when the work vehicle is in a state where it can automatically drive by a first positioning method and the positioning method switches to a second positioning method having a different positioning accuracy from the first positioning method.

Advantages of the Invention

[0010] According to the present invention, it is possible to provide an automatic driving method, an automatic driving system, and an automatic driving program capable of maintaining work accuracy even when the positioning method of the work vehicle is switched.

Brief Description of the Drawings

[0011]

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MODE FOR CARRYING OUT THE INVENTION

[0012] The following embodiments are examples of embodying the present invention and do not limit the technical scope of the present invention.

[0013] As shown in FIGS. 1 and 2, the automatic driving system 1 according to an embodiment of the present invention includes a work vehicle 10, a satellite 20, and a base station (not shown). In this embodiment, the case where the work vehicle 10 is a tractor will be described as an example. As another embodiment, the work vehicle 10 may be a rice transplanter, a combine, a construction machine, a snowplow, or the like. The work vehicle 10 performs a predetermined operation (for example, tilling operation) while traveling along a target path R in response to an operator's operation within a field F (see FIG. 4). Specifically, the work vehicle 10 travels straight along the target path R in response to automatic steering, and turns in response to manual steering (driving operation) by the operator. The work vehicle 10 travels within the field F while switching between automatic driving on a straight path and manual driving on a turning path to perform work. The target path R may be generated in advance based on the operator's operation and stored as path data.

[0014] The work vehicle 10 travels, for example, in the field F shown in FIG. 4, repeating straight running and turning running until the work is completed. Each of the plurality of straight paths is substantially parallel to each other. The target path R shown in FIG. 4 is an example, and the target path R is appropriately determined according to the size of the work vehicle 10, the size of the work implement 14, the work content, the shape of the field F, and the like.

[0015] Note that the automatic driving system 1 may include an operation terminal (such as a tablet terminal or a smartphone) operated by the operator. The operation terminal can communicate with the work vehicle 10 via a communication network such as a mobile phone line network, a packet line network, or a wireless LAN. For example, the operator performs an operation of registering various information (work vehicle information, field information, work information, etc.) on the operation terminal. Further, the operator can grasp the traveling status, work status, etc. of the work vehicle 10 based on the traveling locus displayed on the operation terminal at a location away from the work vehicle 10.

[0016] The satellite 20 is a positioning satellite that constitutes a satellite positioning system such as GNSS (Global Navigation Satellite System), and transmits GNSS signals (satellite signals).

[0017] The positioning device 16 executes a positioning process for calculating the current position (latitude and longitude) of the work vehicle 10 by using the GNSS signals transmitted from the satellite 20. Specifically, the positioning device 16 can position the work vehicle 10 by using a DGNSS positioning method for positioning the work vehicle 10 based on positioning information (such as GNSS signals) received by one receiver (positioning antenna 164).

[0018] Also, the positioning device 16 can position the work vehicle 10 by using an RTK positioning method for positioning the work vehicle 10 based on GNSS signals and correction information generated based on the GNSS signals. For example, the positioning device 16 receives the correction information and performs positioning by the RTK method by connecting to a base station (not shown) installed corresponding to the field F or a mobile terminal (smartphone) possessed by the operator. The RTK method is a positioning method with higher positioning accuracy than the DGNSS method.

[0019] The first positioning method and the second positioning method of the present invention are two positioning methods with different positioning accuracies. For example, one of the DGNSS method and the RTK method is an example of the first positioning method of the present invention, and the other is an example of the second positioning method of the present invention. Note that the positioning method of the present invention is not limited to the DGNSS method and the RTK method, and may be a DGPS method or other positioning methods.

[0020] [Work vehicle 10] As shown in FIGS. 1 and 2, the work vehicle 10 includes a vehicle control device 11, a storage unit 12, a traveling device 13, a working machine 14, a communication unit 15, a positioning device 16, an operation device 17, etc. The vehicle control device 11 is electrically connected to the storage unit 12, the traveling device 13, the working machine 14, the positioning device 16, the operation device 17, etc. Note that the vehicle control device 11 and the positioning device 16 may be capable of wireless communication.

[0021] The communication unit 15 is a communication interface for connecting the work vehicle 10 to a communication network, either wired or wirelessly, and performing data communication according to a predetermined communication protocol with external devices (such as an operation terminal) via the communication network.

[0022] The storage unit 12 is a non-volatile storage unit such as an HDD (Hard Disk Drive) or an SSD (Solid State Drive) that stores various types of information. The storage unit 12 stores control programs such as an automatic driving program for causing the vehicle control device 11 to execute the automatic driving process (see FIG. 11) described later. For example, the automatic driving 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 12. Note that the automatic driving program may be downloaded from a server (not shown) to the work vehicle 10 via the communication network and stored in the storage unit 12. Further, the storage unit 12 may store data of the target route R generated in the operation terminal.

[0023] The traveling device 13 is a driving unit for driving the work vehicle 10. As shown in FIG. 2, the traveling device 13 includes an engine 131, front wheels 132, rear wheels 133, a transmission 134, a front axle 135, a rear axle 136, a steering wheel 137, and the like. Note that the front wheels 132 and the rear wheels 133 are respectively provided on the left and right sides of the work vehicle 10. Further, the traveling device 13 is not limited to a wheel type including the front wheels 132 and the rear wheels 133, and may be a crawler type including crawlers provided on the left and right sides of the work vehicle 10.

[0024] The engine 131 is a drive source such as a diesel engine or a gasoline engine that is driven using fuel supplied from a fuel tank (not shown). The traveling device 13 may be provided with an electric motor as a drive source together with the engine 131 or instead of the engine 131. A generator (not shown) is connected to the engine 131, and electric power is supplied from the generator to electrical components such as the vehicle control device 11 provided in the work vehicle 10 and the battery. The battery is charged by the electric power supplied from the generator. The electrical components such as the vehicle control device 11, the positioning device 16, and the operation device 17 provided in the work vehicle 10 can be driven by the electric power supplied from the battery even after the engine 131 stops.

[0025] The driving force of the engine 131 is transmitted to the front wheels 132 via the transmission 134 and the front axle 135, and is transmitted to the rear wheels 133 via the transmission 134 and the rear axle 136. Also, the driving force of the engine 131 is transmitted to the work implement 14 via a PTO shaft (not shown). The traveling device 13 performs a traveling operation according to an instruction from the vehicle control device 11.

[0026] The work implement 14 is, for example, a tiller, a seeder, a lawn mower, a plow, or a fertilizer applicator, and is detachable from the work vehicle 10. Thereby, the work vehicle 10 can perform various operations using each of the work implements 14. FIG. 2 shows the case where the work implement 14 is a tiller. The work implement 14 may be supported by the work vehicle 10 so as to be able to move up and down by a lifting mechanism (not shown). The vehicle control device 11 can control the lifting mechanism to raise and lower the work implement 14.

[0027] The steering wheel 137 is an operation unit that is operated by an operator or the vehicle control device 11. For example, the traveling device 13 changes the angle of the front wheels 132 by a hydraulic power steering mechanism (not shown) or the like according to the operation of the steering wheel 137 by the operator or the vehicle control device 11, and changes the traveling direction of the work vehicle 10.

[0028] In addition to the steering wheel 137, the traveling device 13 includes a shift lever (not shown), an accelerator, a brake, etc. that are operated by the vehicle control device 11. In the traveling device 13, according to the operation of the shift lever by the vehicle control device 11, the gears of the transmission 134 are switched to forward gears or reverse gears, etc., and the traveling mode of the work vehicle 10 is switched to forward or reverse, etc. Also, the vehicle control device 11 controls the rotational speed of the engine 131 by operating the accelerator. Further, the vehicle control device 11 operates the brake to brake the rotation of the front wheels 132 and the rear wheels 133 using an electromagnetic brake.

[0029] The positioning device 16 is a communication device including a positioning control unit 161, a storage unit 162, a communication unit 163, a positioning antenna 164, etc. For example, as shown in FIG. 2, the positioning device 16 is provided on the upper part of the cabin 18 where the operator rides. Also, the installation location of the positioning device 16 is not limited to the cabin 18. Further, the positioning control unit 161, the storage unit 162, the communication unit 163, and the positioning antenna 164 of the positioning device 16 may be distributed and arranged at different positions in the work vehicle 10. As described above, the battery is connected to the positioning device 16, and the positioning device 16 can operate even when the engine 131 is stopped. Also, as the positioning device 16, for example, a mobile phone terminal, a smartphone, or a tablet terminal may be substituted.

[0030] The positioning control unit 161 is a computer system including one or more processors and storage memories such as non-volatile memory and RAM. The storage unit 162 is a non-volatile memory or the like that stores a positioning control program for causing the positioning control unit 161 to execute positioning processing, and data such as positioning information and movement information. For example, the positioning control 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 162. Note that the positioning control program may be downloaded from a server (not shown) to the positioning device 16 via a communication network and stored in the storage unit 162.

[0031] The communication unit 163 is a communication interface for connecting the positioning device 16 to a communication network by wire or wirelessly and performing data communication according to a predetermined communication protocol with external devices such as a base station server via the communication network.

[0032] The positioning antenna 164 is an antenna that receives radio waves (GNSS signals) transmitted from the satellite 20.

[0033] The positioning control unit 161 includes various processing units such as a positioning processing unit 181 and a switching processing unit 182. Note that the positioning control unit 161 functions as the various processing units by executing various processes according to the automatic driving program. Further, as another embodiment, a part or all of the positioning processing unit 181 and the switching processing unit 182 may be configured by an electronic circuit.

[0034] The positioning processing unit 181 positions the working vehicle 10 by a predetermined positioning method (DGNSS method, RTK method, etc.) based on the GNSS signal received by the positioning antenna 164 from the satellite 20. Specifically, when the positioning method is set to the DGNSS method, the positioning processing unit 181 positions the working vehicle 10 by the DGNSS method, and when the positioning method is set to the RTK method, the positioning processing unit 181 positions the working vehicle 10 by the RTK method. The positioning processing unit 181 is an example of the positioning processing unit of the present invention.

[0035] The switching processing unit 182 mutually switches between the DGNSS method and the RTK method. Specifically, the switching processing unit 182 switches between the DGNSS method and the RTK method based on operations by the operator, the positioning state in the positioning processing unit 181, etc. For example, when the operator connects a mobile terminal (such as a smartphone) to the positioning device 16 via Bluetooth (registered trademark) or a communication cable and the positioning state becomes a state where RTK positioning is possible, the switching processing unit 182 switches the positioning method from the DGNSS method to the RTK method. Also, when the number of satellites 20 capable of receiving GNSS signals is large and the positioning state becomes a state where RTK positioning is possible, the switching processing unit 182 switches the positioning method from the DGNSS method to the RTK method. Further, when the number of satellites 20 capable of receiving GNSS signals decreases due to the presence of obstacles such as windbreaks and buildings near the field F and the positioning state deteriorates, the switching processing unit 182 switches the positioning method from the RTK method to the DGNSS method.

[0036] Here, the positioning method may be set to the DGNSS method in advance. That is, the default of the positioning method may be set to the DGNSS method. In this case, when the engine 131 of the work vehicle 10 starts, the positioning processing unit 181 starts receiving GNSS signals transmitted from the satellites 20 and performs positioning processing until the positioning state becomes a state where DGNSS positioning is possible. The positioning processing unit 181 transmits a notification of positioning completion to the vehicle control device 11. The vehicle control device 11 permits automatic traveling by the DGNSS method when the positioning state becomes a state where DGNSS positioning is possible. When the traveling processing unit 111 of the vehicle control device 11 receives a traveling start instruction from the operator in a state where the positioning state is a state where DGNSS positioning is possible, it starts the automatic traveling of the work vehicle 10 by the DGNSS method.

[0037] The operation device 17 is a device operated by an operator who boards the work vehicle 10, and is provided with an operation display unit 171. The operation display unit 171 is a user interface including a display unit such as a liquid crystal display or an organic EL display for displaying various types of information, and an operation unit such as an operation button or a touch panel for receiving operations. The operation display unit 171 displays various setting screens, work screens, and the like. Further, the operation display unit 171 receives the operations of the operator on the setting screen and the work screen. Further, as shown in FIGS. 2 and 3 for example, the operation device 17 is installed near the steering wheel 137 in the cabin 18. Further, the operation device 17 may be an operation terminal (such as a tablet terminal or a smartphone) that can be carried by the operator. Further, the operation display unit 171 includes an auto run button (not shown) for the operator to give an auto run start instruction when starting the automatic running of the work vehicle 10.

[0038] Further, the operator can perform various settings related to automatic running on the operation device 17. For example, the operator can set the positioning method on the setting screen D1.

[0039] FIG. 5A shows an example of the setting screen D1. Among the plurality of setting items displayed on the setting screen D1, the item K1 of "working accuracy" is an item for setting the positioning method.

[0040] When the operator sets or changes the positioning method, the operator selects the item K1 (presses the determination button) on the setting screen D1. When the operator selects the item K1, the operation device 17 displays the setting screen D2 shown in FIG. 5B. On the setting screen D2, "DGNSS", "RTK working accuracy priority", and "RTK working continuity priority" are displayed as selectable positioning methods. "RTK working accuracy priority" is a setting item for executing a process of stopping the automatic running (automatic steering) when the positioning accuracy decreases while performing positioning by the RTK method. "RTK working continuity priority" is a setting item for executing a process of continuing the automatic running (automatic steering) for a certain period even when the positioning accuracy decreases while performing positioning by the RTK method.

[0041] The operator can select a positioning method according to the work content. In this embodiment, it is assumed that the positioning method is set to the DGNSS method as the initial setting (default).

[0042] The vehicle control device 11 includes control devices such as a CPU, a ROM, and a RAM. The CPU is a processor that executes various arithmetic processes. The ROM is a non-volatile storage unit in which control programs such as BIOS and OS for causing the CPU to execute various arithmetic processes are stored in advance. The RAM is a volatile or non-volatile storage unit that stores various information and is used as a temporary storage memory (working area) for various processes executed by the CPU. Then, the vehicle control device 11 controls the work vehicle 10 by executing various control programs stored in advance in the ROM or the storage unit 12 with the CPU.

[0043] As shown in FIG. 1, the vehicle control device 11 includes various processing units such as a travel processing unit 111 and a reception processing unit 112. Note that the vehicle control device 11 functions as the various processing units by executing various processes according to the automatic driving program with the CPU. Also, some or all of the processing units may be configured by electronic circuits. Note that the automatic driving program may be a program for causing a plurality of processors to function as the processing units.

[0044] The traveling processing unit 111 controls the traveling of the work vehicle 10. Specifically, the traveling processing unit 111 automatically travels the work vehicle 10 based on the position information indicating the position of the work vehicle 10 measured by the positioning processing unit 181. For example, when the positioning state becomes a state where DGNSS positioning is possible and the operator presses the automatic traveling button of the operating device 17, the traveling processing unit 111 starts the automatic traveling of the work vehicle 10 based on the position information indicating the position of the work vehicle 10 measured by the DGNSS method. Thereby, the work vehicle 10 starts automatic traveling according to the target route R and starts the work by the work implement 14. Note that the traveling processing unit 111 may automatically travel the straight traveling route by automatic steering and manually travel the turning route by the operator's manual steering.

[0045] Further, when the operator remotely operates the work vehicle 10 without boarding the work vehicle 10, the operator inputs a traveling start instruction at the operation terminal. When the traveling processing unit 111 acquires the traveling start instruction from the operation terminal, the traveling processing unit 111 automatically travels the work vehicle 10 along the target route R while performing positioning by the DGNSS method. Also, when the traveling processing unit 111 acquires a traveling stop instruction from the operation terminal, the traveling processing unit 111 stops the automatic traveling of the work vehicle 10. The traveling processing unit 111 is an example of the traveling processing unit of the present invention.

[0046] The work vehicle 10 according to the present embodiment may be in either a traveling mode (first traveling mode) in which the vehicle travels while switching between automatic steering and manual steering by the operator, or a traveling mode (second traveling mode) in which the vehicle travels only by automatic steering.

[0047] Here, a specific example (first traveling pattern) of the first traveling mode will be described with reference to FIGS. 6 and 7. In the present embodiment, in the farm field F shown in FIG. 4, the work vehicle 10 is automatically traveled along a straight traveling route.

[0048] First, the operator sets a reference line L1 for generating a straight-ahead path that is the target path R. For example, the operator manually drives the work vehicle 10 in a direction (target direction) in which the work vehicle 10 is desired to travel and work at an arbitrary position (e.g., the outer peripheral end) within the field F. Specifically, the operator drives the work vehicle 10 straight ahead in a direction parallel to the working direction (e.g., the tilling direction) when the work vehicle 10 is working in the work area. Then, when the operator is manually driving the work vehicle 10 in the intended target direction, the operator operates the operation display unit 171 twice (e.g., touch operation) at an arbitrary position (e.g., the front and rear ends of the work area). The vehicle control device 11 registers the position (point A) of the work vehicle 10 by the operator's first operation and registers the position (point B) of the work vehicle 10 by the operator's second operation. When the vehicle control device 11 acquires the position information of point A and point B, it sets a straight line passing through point A and point B as the reference line L1 (see FIG. 6A). Note that the vehicle control device 11 may be able to register point B when the work vehicle 10 has traveled a predetermined distance (e.g., 5 m) after registering point A. Thereby, a more accurate reference line L1 can be set. The vehicle control device 11 generates a travel path (target path R) including the reference line L1 and a plurality of straight lines parallel to the reference line L1. For example, the vehicle control device 11 generates a plurality of parallel straight lines at equal intervals to the left and right around the reference line L1 based on a preset working width (the lateral width of the work implement 14) and a lap width (the width overlapping the adjacent worked area) (see FIG. 6B). The vehicle control device 11 registers the generated target path R in the storage unit 12 and displays it on the operation device 17.

[0049] After the target path R is generated, when the operator drives the work vehicle 10 straight ahead by automatic steering within the field F, while looking at the target path R displayed on the operation device 17, the operator moves the work vehicle 10 by manual steering so that the direction (azimuth) of the work vehicle 10 is within a predetermined range (predetermined azimuth) with respect to the direction of the reference line L1 (satisfying the automatic driving start condition) (see FIG. 6C).

[0050] FIG. 7A shows an operation screen indicating that the work vehicle 10 has satisfied the automatic driving start condition and has become capable of automatic driving. When the work vehicle 10 satisfies the automatic driving start condition, the vehicle control device 11 causes the operation screen shown in FIG. 7A to be displayed on the operation display unit 171. When the work vehicle 10 becomes capable of automatic driving, the operator presses an automatic driving button (not shown) on the operation display unit 171 to give a travel start instruction. When the reception processing unit 112 receives the travel start instruction, the travel processing unit 111 starts automatic steering of the work vehicle 10 along the straight travel route closest to the current position P0 (see FIG. 6C). Thereby, the travel processing unit 111 automatically drives the work vehicle 10 along the straight travel route by automatic steering.

[0051] FIG. 7B shows a display screen when the work vehicle 10 is in automatic driving. When the work vehicle 10 starts automatic driving, the vehicle control device 11 causes the display screen shown in FIG. 7B to be displayed on the operation display unit 171. The vehicle control device 11 displays a straight travel route, a worked area (work status), etc. on the display screen.

[0052] As described above, the first travel pattern of the first travel method is configured to generate a target route R in advance according to the work width and lap width of the work vehicle 10 and perform automatic driving. As the second travel pattern of the first travel method, a configuration may be adopted in which the target route R is generated based on the position of the work vehicle 10 and automatic driving is performed.

[0053] In the second travel pattern, for example, after the reference line L1 is set (see FIG. 6A), when the operator moves the work vehicle 10 to the position where the work starts and presses the automatic driving button, the vehicle control device 11 automatically steers the work vehicle 10 from that position and makes it travel straight parallel to the reference line L1.

[0054] Note that the vehicle control device 11 may apply the first driving pattern and the second driving pattern according to the selection operation of the operator. For example, the vehicle control device 11 may display on a setting screen (not shown) the first route creation mode corresponding to the first driving pattern and the second route creation mode corresponding to the second driving pattern so that they can be selected, and may execute automatic driving according to the route creation mode selected by the operator.

[0055] Also, in the first driving pattern and the second driving pattern, when the traveling processing unit 111 determines that the work vehicle 10 is traveling straight by automatic steering and approaching the end point Pe (the intersection of the perpendicular line passing through the B point on the reference line L1 and the straight traveling route (straight line)) corresponding to the B point of the reference line L1 (see FIG. 6C), the traveling processing unit 111 notifies (message display, voice guidance, etc.) the operator of the guidance information indicating that it has approached the end point Pe. When the operator confirms the guidance information, the operator ends the automatic steering.

[0056] When the work vehicle 10 reaches the end point Pe (the end point of the straight traveling route), the traveling processing unit 111 switches the traveling mode to manual driving. The traveling processing unit 111 may switch the traveling mode to manual driving when it determines that the work vehicle 10 has reached the end point Pe, or may switch the traveling mode to manual driving according to the operation of the operator. When the traveling mode is switched to manual driving, for example, the operator manually steers the work vehicle 10 to perform turning travel (manual driving).

[0057] As described above, the traveling processing unit 111 switches the traveling mode according to the operation of the operation device 17 by the operator, and automatically drives the work vehicle 10 along the straight traveling route (target route R) by automatic steering and manually drives the work vehicle 10 along the turning route by manual steering. Note that the traveling method of the work vehicle 10 of the present invention is not limited to the above-described embodiment.

[0058] The reception processing unit 112 receives various operations by the operator. For example, the reception processing unit 112 receives operations for setting the type of the working machine 14, the working width, the wrap width, the route offset amount, etc. on a setting screen (not shown) for setting the work information displayed on the operation device 17. Further, the reception processing unit 112 receives an operation for setting the positioning method on the setting screen D1 (see FIGS. 5A and 5B). In the present embodiment, the positioning method is set to the DGNSS method, and the traveling processing unit 111 automatically travels the work vehicle 10 by the DGNSS method.

[0059] By the way, since the DGNSS method and the RTK method have different positioning accuracies, for example, when the work vehicle 10 switches to the RTK method while automatically traveling with the DGNSS method for positioning, the self-recognition position of the work vehicle 10 before and after the switching of the positioning method will deviate greatly. As a result, since the work vehicle 10 operates to follow the target route R immediately after the positioning method is switched, there arises a problem that the behavior of the work vehicle 10 becomes unstable and the work accuracy decreases. Specific examples of this problem are shown in FIGS. 8A and 8B.

[0060] In FIG. 8A, "R" indicates the target route (straight traveling route), "P1" and "P1'" indicate the current self-recognition position of the work vehicle 10, and "P0" indicates the self-recognition position corresponding to the traveling history of the work vehicle 10. Since the DGNSS method does not have high positioning accuracy, an error of a certain degree (several m) occurs in the self-recognition position with respect to the current position of the work vehicle 10.

[0061] Here, there may be a case where the positioning method switches to the RTK method while the work vehicle 10 is automatically traveling by the DGNSS method. For example, when the operator's mobile terminal (smartphone) is connected to the positioning device 16 via Bluetooth or a communication cable and becomes in a state where RTK positioning is possible (high-precision state), the switching processing unit 182 switches the positioning method to the RTK method. When the positioning method switches from the DGNSS method to the RTK method, as shown in FIG. 8A, a positional deviation occurs between the self-recognition position P1 measured by the DGNSS method and the self-recognition position P1' measured by the RTK method.

[0062] When there is a displacement between the self-recognition positions P1 and P1' before and after the switching of the positioning method, the travel processing unit 111 executes travel control to cause the self-recognition position P1' of the work vehicle 10 by the RTK method to follow the target route R. For example, as shown in FIG. 8B, the steering wheel 137 is greatly turned to the left to change the travel direction of the work vehicle 10. For this reason, the behavior of the work vehicle 10 becomes unstable, and the work accuracy of the work vehicle 10 decreases. In addition, it gives discomfort to the operator riding on the work vehicle 10. Note that the above problem also occurs when the positioning method is switched from the RTK method to the DGNSS method while the work vehicle 10 is automatically traveling.

[0063] In addition, the above problem also occurs when the work vehicle 10 starts automatic travel. For example, when the positioning method is set to the DGNSS method, if the positioning method is switched from the DGNSS method to the RTK method after the work vehicle 10 satisfies the automatic travel start condition and the operator gives a travel start instruction, there is a displacement between the self-recognition position P1 measured by the DGNSS method and the self-recognition position P1' measured by the RTK method. In this case, immediately after the start of automatic travel, the steering wheel 137 is greatly turned and the behavior of the work vehicle 10 becomes unstable. Thus, when the work vehicle 10 switches from the first positioning method to the second positioning method with different positioning accuracies, the problem that the behavior of the work vehicle 10 becomes unstable and the work accuracy decreases occurs.

[0064] Therefore, the work vehicle 10 according to the present embodiment is provided with a configuration capable of maintaining the work accuracy even when the positioning method is switched. Hereinafter, specific configurations will be shown as a first configuration example, a second configuration example, and a third configuration example.

[0065] [First Configuration Example] As a first configuration example, when the work vehicle 10 is in a state where it can automatically travel by the first positioning method, the travel processing unit 111 prohibits automatic travel when the positioning method is switched to a second positioning method having a different positioning accuracy from the first positioning method.

[0066] For example, when the positioning method switches from the first positioning method to the second positioning method while the work vehicle 10 is automatically driving according to the first positioning method, the travel processing unit 111 stops the automatic driving (stops the work vehicle 10). For example, as shown in FIG. 8A, when the positioning method switches from the DGNSS method to the RTK method while the work vehicle 10 is automatically driving along the target route R according to the DGNSS method, the travel processing unit 111 stops the automatic driving (stops the work vehicle 10). When the vehicle control device 11 stops the automatic driving, it may display warning information on the operation device 17. For example, the vehicle control device 11 may display a message prompting to cut off the communication of the mobile terminal connected to the positioning device 16. When the positioning method switches from the RTK method to the DGNSS method (when it returns), the travel processing unit 111 resumes the automatic driving.

[0067] Also, for example, when the positioning method switches from the RTK method to the DGNSS method while the work vehicle 10 is automatically driving along the target route R according to the RTK method, the travel processing unit 111 stops the automatic driving (stops the work vehicle 10). In this case, the vehicle control device 11 may display on the operation device 17 a message prompting to wait until the positioning accuracy reaches a state where RTK positioning is possible, or a message prompting to move the work vehicle 10 manually by steering until it reaches a position where the positioning accuracy reaches a state where RTK positioning is possible. Also, when the positioning method switches from the DGNSS method to the RTK method (when it returns), the travel processing unit 111 resumes the automatic driving.

[0068] Also, for example, when the positioning method is set to the DGNSS method (see FIG. 5A) and the positioning method switches to the RTK method when the work vehicle 10 starts automatic driving, the travel processing unit 111 prohibits the start of automatic driving. When the vehicle control device 11 prohibits the start of automatic driving, it may display on the operation device 17 a message prompting to cut off the communication of the mobile terminal connected to the positioning device 16. Also, when the positioning method switches from the RTK method to the set DGNSS method, the travel processing unit 111 permits automatic driving.

[0069] For example, when the positioning method is set to the RTK method (see FIG. 5B) and the positioning method switches to the DGNSS method when the work vehicle 10 starts automatic driving, the travel processing unit 111 prohibits the start of automatic driving. When the vehicle control device 11 prohibits the start of automatic driving, it may cause the operation device 17 to display a message prompting to wait until the positioning accuracy reaches a state where RTK positioning is possible, or a message prompting to move the work vehicle 10 by manual steering to a position where the positioning accuracy reaches a state where RTK positioning is possible. Further, the travel processing unit 111 permits automatic driving when the positioning method switches from the DGNSS method to the set RTK method.

[0070] As described above, in the first configuration example, when the work vehicle 10 is in a state where it can perform automatic driving by the first positioning method (when performing automatic driving by the first positioning method or when it is in a state where it can start automatic driving by the first positioning method), the vehicle control device 11 prohibits automatic driving (for example, stops automatic driving, stops the work vehicle 10, or prohibits the start of automatic driving) when the positioning method switches to the second positioning method.

[0071] [Second Configuration Example] As a second configuration example, the travel processing unit 111 prohibits automatic driving when the positioning method switches from the first positioning method to the second positioning method and the distance difference between the position of the work vehicle 10 (self-recognition position) measured by the first positioning method and the position of the work vehicle 10 (self-recognition position) measured by the second positioning method is equal to or greater than a threshold value. The distance difference is the distance from the position of the previous positioning process to the position of the current positioning process.

[0072] For example, when the positioning method switches from the first positioning method to the second positioning method while the work vehicle 10 is automatically traveling by the first positioning method, and the distance difference between the position of the work vehicle 10 measured by the first positioning method and the position of the work vehicle 10 measured by the second positioning method is equal to or greater than a threshold value, the travel processing unit 111 stops the automatic travel (stops the work vehicle 10). For example, as shown in FIG. 9A, when the positioning method switches from the DGNSS method to the RTK method while the work vehicle 10 is automatically traveling by the DGNSS method, and the distance difference L2 between the self-recognition position P1 of the work vehicle 10 measured by the DGNSS method and the self-recognition position P1' of the work vehicle 10 measured by the RTK method is equal to or greater than the threshold value Lth, the travel processing unit 111 stops the automatic travel (stops the work vehicle 10).

[0073] Also, for example, as shown in FIG. 9A, when the positioning method switches from the RTK method to the DGNSS method while the work vehicle 10 is automatically traveling by the RTK method, and the distance difference L2 between the self-recognition position P1 of the work vehicle 10 measured by the RTK method and the self-recognition position P1' of the work vehicle 10 measured by the DGNSS method is equal to or greater than the threshold value Lth, the travel processing unit 111 stops the automatic travel (stops the work vehicle 10).

[0074] Also, for example, as shown in FIG. 9B, when the positioning method switches from the DGNSS method to the RTK method while the work vehicle 10 is automatically traveling by the DGNSS method, and the distance difference L2 between the self-recognition position P1 of the work vehicle 10 measured by the DGNSS method and the self-recognition position P1' of the work vehicle 10 measured by the RTK method is less than the threshold value Lth, the travel processing unit 111 continues the automatic travel. In this case, the work vehicle 10 continues the automatic travel while following the target path R while being measured by the RTK method.

[0075] For example, as shown in FIG. 9B, when the positioning method is switched to the DGNSS method while the work vehicle 10 is automatically traveling by the RTK method, and the distance difference L2 between the self-recognition position P1 of the work vehicle 10 measured by the RTK method and the self-recognition position P1' of the work vehicle 10 measured by the DGNSS method is less than the threshold value Lth, the travel processing unit 111 continues the automatic travel. In this case, the work vehicle 10 continues the automatic travel while following the target path R while positioning by the DGNSS method.

[0076] For example, when the positioning method is set to the DGNSS method (see FIG. 5A) and the positioning method is switched to the RTK method when the work vehicle 10 starts automatic travel, and the distance difference L2 is equal to or greater than the threshold value Lth, the travel processing unit 111 prohibits the start of automatic travel.

[0077] For example, when the positioning method is set to the RTK method (see FIG. 5B) and the positioning method is switched to the DGNSS method when the work vehicle 10 starts automatic travel, and the distance difference L2 is equal to or greater than the threshold value Lth, the travel processing unit 111 prohibits the start of automatic travel.

[0078] For example, when the positioning method is set to the DGNSS method (see FIG. 5A) and the positioning method is switched to the RTK method when the work vehicle 10 starts automatic travel, and the distance difference L2 is less than the threshold value Lth, the travel processing unit 111 permits the start of automatic travel.

[0079] For example, when the positioning method is set to the RTK method (see FIG. 5B) and the positioning method is switched to the DGNSS method when the work vehicle 10 starts automatic travel, and the distance difference L2 is less than the threshold value Lth, the travel processing unit 111 permits the start of automatic travel.

[0080] As described above, in the second configuration example, when the work vehicle 10 is in a state where it can automatically travel by the first positioning method (when automatically traveling by the first positioning method or when it is in a state where automatic traveling can be started by the first positioning method), and the distance difference L2 between the position of the work vehicle 10 (self-recognition position P1) measured by the first positioning method and the position of the work vehicle 10 (self-recognition position P1') measured by the second positioning method is equal to or greater than the threshold value Lth, automatic traveling is prohibited, and when the distance difference L2 is less than the threshold value Lth, automatic traveling is permitted (continued or started). In this way, when the change in the self-recognition position is small, the behavior change of the work vehicle 10 is small, so automatic traveling may be permitted.

[0081] Note that the threshold value Lth is set to a distance at which the work vehicle 10 can follow the stable target path R from the self-recognition position P1' when continuing or starting the automatic traveling of the work vehicle 10. Further, the vehicle control device 11 may make the threshold value Lth used in the determination process when switching from the DGNSS method to the RTK method different from the threshold value Lth used in the determination process when switching from the RTK method to the DGNSS method.

[0082] For example, when switching from a positioning method with low positioning accuracy to a positioning method with high positioning accuracy, the time until the positioning method returns becomes shorter, and when switching from a positioning method with high positioning accuracy to a positioning method with low positioning accuracy, the time until the positioning method returns tends to become longer. Therefore, the vehicle control device 11 may set the threshold value Lth used in the determination process when returning to the DGNSS method when switching from the DGNSS method to the RTK method to be shorter than the threshold value Lth used in the determination process when returning to the RTK method when switching from the RTK method to the DGNSS method.

[0083] [Third Configuration Example] As a third configuration example, when the work vehicle 10 is in a state where it can automatically travel by the first positioning method, if the positioning method switches to a second positioning method with a different positioning accuracy from the first positioning method, the traveling processing unit 111 permits automatic traveling until a predetermined time has elapsed after the switch from the first positioning method to the second positioning method.

[0084] For example, when the positioning method switches to the second positioning method while the work vehicle 10 is automatically traveling by the first positioning method, the traveling processing unit 111 continues automatic traveling until a predetermined time has elapsed after the switch from the first positioning method to the second positioning method. For example, as shown in FIG. 10, when the positioning method switches to the RTK method while the work vehicle 10 is automatically traveling by the DGNSS method, the traveling processing unit 111 continues automatic traveling until a predetermined time has elapsed after the switch to the RTK method. The traveling route Ra shown in FIG. 10 indicates the route traveled by the work vehicle 10 during a predetermined time after the position shift of the work vehicle 10.

[0085] Also, when the positioning method switches (returns) from the RTK method to the DGNSS method before the predetermined time has elapsed, the traveling processing unit 111 continues automatic traveling in the DGNSS method. The traveling route Rb shown in FIG. 10 indicates the traveling route of the work vehicle 10 after returning to the DGNSS method after the predetermined time has elapsed.

[0086] Further, when the positioning method does not switch from the second positioning method to the first positioning method while the predetermined time has elapsed after the positioning method switches from the first positioning method to the second positioning method, the traveling processing unit 111 prohibits automatic traveling. For example, when the positioning method does not switch from the RTK method to the DGNSS method while the predetermined time has elapsed after the positioning method switches from the DGNSS method to the RTK method, the traveling processing unit 111 stops the automatic traveling. In this case, the work vehicle 10 automatically travels along the traveling route Ra by the RTK method and stops.

[0087] For example, when the positioning method is set to the DGNSS method (see Fig. 5A), when the work vehicle 10 starts automatic driving and the positioning method switches to the RTK method, automatic driving is started and continued by the RTK method until the predetermined time elapses. Further, when the positioning method does not switch from the RTK method to the DGNSS method before the predetermined time elapses, the traveling processing unit 111 stops the automatic driving.

[0088] For example, when the positioning method is set to the RTK method (see Fig. 5B), when the work vehicle 10 starts automatic driving and the positioning method switches to the DGNSS method, automatic driving is started and continued by the DGNSS method until the predetermined time elapses. Further, when the positioning method does not switch from the DGNSS method to the RTK method before the predetermined time elapses, the traveling processing unit 111 stops the automatic driving.

[0089] As described above, in the third configuration example, when the work vehicle 10 is in a state where it can automatically travel by the first positioning method (when automatically traveling by the first positioning method or when it is in a state where automatic driving can be started by the first positioning method), when the positioning method switches to the second positioning method, automatic driving is permitted until the predetermined time elapses, and automatic driving is prohibited when the positioning method does not return to the first positioning method before the predetermined time elapses.

[0090] Note that the predetermined time may be set according to the history of the positioning state. For example, when a location where the positioning state changes within the field F can be specified from the information on the traveling history in past work, the predetermined time can be set by calculating the time required to pass through the location.

[0091] Further, the vehicle control device 11 may make the predetermined time used for the determination process when switching from the DGNSS method to the RTK method different from the predetermined time used for the determination process when switching from the RTK method to the DGNSS method. For example, when switching from a positioning method with low positioning accuracy to a positioning method with high positioning accuracy, the distance difference between the self - recognition positions before and after the switching of the positioning method becomes large. When switching from a positioning method with high positioning accuracy to a positioning method with low positioning accuracy, the distance difference between the self - recognition positions before and after the switching of the positioning method tends to become small. Therefore, the vehicle control device 11 may set the predetermined time used for the determination process when switching from the DGNSS method to the RTK method to be shorter than the predetermined time used for the determination process when switching from the RTK method to the DGNSS method.

[0092] [Automatic driving process] Hereinafter, an example of the automatic driving process executed by the vehicle control device 11 will be described with reference to FIG. 11. Note that the present invention may be regarded as an invention of an automatic driving method in which the vehicle control device 11 executes part or all of the automatic driving process, or an invention of an automatic driving program for causing the vehicle control device 11 to execute part or all of the automatic driving method. Also, one or a plurality of processors may execute the automatic driving process.

[0093] Hereinafter, it is assumed that the positioning method of the work vehicle 10 is set to the DGNSS method (see FIG. 5A).

[0094] In step S1, the vehicle control device 11 determines whether the work vehicle 10 is in a state where it can perform automatic driving. For example, the vehicle control device 11 determines that the work vehicle 10 is in a state where it can perform automatic driving when the automatic driving start conditions such as the orientation of the work vehicle 10 being within a predetermined orientation are satisfied. When the vehicle control device 11 determines that the work vehicle 10 is in a state where it can perform automatic driving (S1: Yes), the process proceeds to step S2. The vehicle control device 11 waits until the work vehicle 10 is in a state where it can perform automatic driving (S1: No).

[0095] Next, in step S2, the vehicle control device 11 determines whether it has received an operation from the operator to start autonomous driving (a driving start instruction). For example, when the operator presses the autonomous driving button of the operation device 17, the vehicle control device 11 receives the driving start instruction. When the vehicle control device 11 receives the driving start instruction (S2: Yes), it transfers the process to step S3. The vehicle control device 11 waits until it receives the driving start instruction (S2: No).

[0096] In step S3, the vehicle control device 11 executes autonomous driving processing. For example, the vehicle control device 11 starts autonomous driving by the DGNSS method. Specifically, the vehicle control device 11 starts automatic steering so that the work vehicle 10 follows the straight driving route closest to the current position P0 among the plurality of straight driving routes included in the target route R (see FIG. 6C). Thereby, the vehicle control device 11 automatically drives the work vehicle 10 along the straight driving route by automatic steering. The work vehicle 10 performs autonomous driving along the straight driving route while positioning by the DGNSS method.

[0097] Next, in step S4, the vehicle control device 11 determines whether the positioning method has changed (switched). Here, the vehicle control device 11 determines whether the positioning method has switched from the DGNSS method to the RTK method. For example, when the operator's mobile terminal (smartphone) is connected to the positioning device 16 via Bluetooth or a communication cable and is in a state where RTK positioning is possible (high-precision state), the positioning device 16 (switching processing unit 182) switches the positioning method to the RTK method. In this case, the vehicle control device 11 determines that the positioning method has switched from the DGNSS method to the RTK method. When the vehicle control device 11 determines that the positioning method has changed (S4: Yes), it transfers the process to step S5. On the other hand, when the vehicle control device 11 determines that the positioning method has not changed (S4: No), it transfers the process to step S8.

[0098] In step S5, the vehicle control device 11 stops the automatic driving of the work vehicle 10 (stops the work vehicle 10). For example, when the work vehicle 10 switches from the DGNSS method to the RTK method during automatic driving, the vehicle control device 11 stops the automatic driving (stops the work vehicle 10) at that time. Also, when the positioning method switches from the DGNSS method to the RTK method when the work vehicle 10 starts automatic driving, the vehicle control device 11 prohibits the start of automatic driving.

[0099] Next, in step S6, the vehicle control device 11 determines whether the positioning method has returned. Here, the vehicle control device 11 determines whether the positioning method has switched from the RTK method to the DGNSS method. For example, when the connection between the operator's mobile terminal and the positioning device 16 is disconnected, the positioning device 16 (switching processing unit 182) switches the positioning method to the DGNSS method. In this case, the vehicle control device 11 determines that the positioning method has switched from the RTK method to the DGNSS method. When the vehicle control device 11 determines that the positioning method has returned (S6: Yes), the process proceeds to step S7. The vehicle control device 11 maintains the state of stopping automatic driving until the positioning method returns (S6: No).

[0100] In step S7, the vehicle control device 11 executes the automatic driving process. For example, the vehicle control device 11 resumes the interrupted automatic driving by the DGNSS method. Also, for example, the vehicle control device 11 starts the prohibited automatic driving by the DGNSS method. As a result, the work vehicle 10 performs automatic driving according to the target path R (straight - ahead path) while positioning by the DGNSS method.

[0101] In step S8, the vehicle control device 11 determines whether the work vehicle 10 has finished working. When the vehicle control device 11 determines that the work vehicle 10 has finished working (S8: Yes), it ends the automatic driving process. On the other hand, when the vehicle control device 11 determines that the work vehicle 10 has not finished working (S8: No), the process proceeds to step S4.

[0102] When the work vehicle 10 starts automatic driving, the vehicle control device 11 repeatedly executes the processes of steps S4 to S8 until the work by the work vehicle 10 is completed.

[0103] As described above, the automatic driving system 1 according to the present embodiment measures the position of the work vehicle 10 by a predetermined positioning method based on the satellite signal received from the satellite 20, and automatically drives the work vehicle 10 based on the position information indicating the measured position of the work vehicle 10. Further, when the work vehicle 10 is in a state where it can automatically drive by the first positioning method, the automatic driving system 1 is configured to be able to prohibit automatic driving when the positioning method switches to a second positioning method having a different positioning accuracy from the first positioning method.

[0104] For example, when the work vehicle 10 is in a state where it can automatically drive by the first positioning method, the automatic driving system 1 stops automatic driving (stops the work vehicle 10) or prohibits the start of automatic driving when the positioning method switches to the second positioning method.

[0105] Further, when the work vehicle 10 is in a state where it can automatically drive by the first positioning method, the automatic driving system 1 prohibits automatic driving when a predetermined condition is satisfied when the positioning method switches to the second positioning method. Regarding the predetermined condition, for example, the automatic driving system 1 prohibits automatic driving when the distance difference between the self - recognition positions of the work vehicle 10 before and after the change of the positioning method is equal to or greater than a threshold value. Also, the automatic driving system 1 prohibits automatic driving when the positioning method does not return until a predetermined time has elapsed after the positioning method is switched. Note that the automatic driving system 1 may permit automatic driving when the distance difference is less than the threshold value. Also, the automatic driving system 1 may permit automatic driving until a predetermined time has elapsed after the positioning method is switched.

[0106] According to the above configuration, for example, when the work vehicle 10 switches to the RTK method while automatically traveling with the DGNSS method for positioning, the work vehicle 10 can be stopped, so that unstable behavior due to displacement of the self-recognition position of the work vehicle 10 can be prevented. Therefore, a decrease in work accuracy can be suppressed.

[0107] The present invention is not limited to the above-described embodiments. As another embodiment of the present invention, the automatic driving system 1 includes a restriction process for automatic driving when the positioning method switches to a second positioning method having a higher positioning accuracy than the first positioning method in a case where the work vehicle 10 is in a state where it can automatically drive by the first positioning method, and a restriction process for automatic driving when the positioning method switches to a first positioning method having a lower positioning accuracy than the second positioning method in a case where the work vehicle 10 is in a state where it can automatically drive by the second positioning method, and these may be made different from each other.

[0108] For example, when the work vehicle 10 is in a state where it can automatically drive by the DGNSS method, the vehicle control device 11 prohibits automatic driving when the positioning method switches to the RTK method. In this way, when switching from a positioning method with low positioning accuracy to a positioning method with high positioning accuracy, the distance difference between the self-recognition positions before and after the switching of the positioning method tends to be large, so automatic driving is prohibited (or stopped).

[0109] On the other hand, for example, when the work vehicle 10 is in a state where it can automatically drive by the RTK method, the vehicle control device 11 permits automatic driving for a predetermined time or a predetermined distance when the positioning method switches to the DGNSS method. In this way, when switching from a positioning method with high positioning accuracy to a positioning method with low positioning accuracy, the distance difference between the self-recognition positions before and after the switching of the positioning method tends to be small, so automatic driving is continued. In this case, the vehicle control device 11 may prohibit automatic driving when the positioning method does not switch to the RTK method after the work vehicle 10 has automatically driven for a predetermined time or a predetermined distance.

[0110] Incidentally, if the positioning process is continued while the work vehicle 10 is stopped, a problem occurs in that the self-recognized position gradually deviates from the target path R. For example, after the work vehicle 10 stops at time t1 (see (a) of FIG. 12), as time elapses, the positional deviation (position error) between the self-recognized position P1 of the work vehicle 10 and the target path R (straight-ahead path) increases (see (b) of FIG. 12). (b) of FIG. 12 shows the self-recognized position P1' of the work vehicle 10 at time t2. Thereafter, at time t3, when the automatic driving of the work vehicle 10 is restarted, the steering wheel 137 is turned significantly to the left to align the self-recognized position P1' with the target path R, and the traveling direction of the work vehicle 10 is changed. For this reason, the behavior of the work vehicle 10 becomes unstable, and the working accuracy of the work vehicle 10 decreases.

[0111] Therefore, when the work vehicle 10 that automatically travels by a predetermined positioning method stops and the stopped state continues for a predetermined time, the vehicle control device 11 may prohibit automatic driving. Specifically, when the work vehicle 10 stops during automatic driving using the DGNSS method or the RTK method or when the vehicle speed becomes less than the threshold value, the vehicle control device 11 starts measuring time (counting the timer). The vehicle control device 11 prohibits automatic driving (stops or stops the work vehicle 10) when the measured time elapses the predetermined time. Further, the vehicle control device 11 resumes automatic driving when the operator performs an operation to resume automatic driving before the measured time elapses the predetermined time. In this case, the vehicle control device 11 resets the measured time.

[0112] In addition, when the work vehicle 10 that automatically travels by a predetermined positioning method stops and the stopped state continues for a predetermined time, and the distance difference between the position of the work vehicle 10 (self-recognition position P1) measured at the time when the work vehicle 10 stops and the position of the work vehicle 10 (self-recognition position P1') measured at the time when the predetermined time has elapsed is equal to or greater than a threshold value, the vehicle control device 11 prohibits automatic driving. For example, as shown in FIG. 9A, when the work vehicle 10 stops during automatic driving by the DGNSS method and the stopped state continues for a predetermined time, and the distance difference L2 between the self-recognition position P1 of the work vehicle 10 when it stops and the self-recognition position P1' of the work vehicle 10 at the time when the predetermined time has elapsed is equal to or greater than the threshold value Lth, the travel processing unit 111 prohibits automatic driving.

[0113] Also, for example, as shown in FIG. 9B, when the work vehicle 10 stops during automatic driving by the DGNSS method and the stopped state continues for a predetermined time, and the distance difference L2 between the self-recognition position P1 of the work vehicle 10 when it stops and the self-recognition position P1' of the work vehicle 10 at the time when the predetermined time has elapsed is less than the threshold value Lth, the travel processing unit 111 permits automatic driving. For example, the travel processing unit 111 resumes automatic driving when the operator performs an operation to resume automatic driving.

[0114] In this way, the vehicle control device 11 may be configured to measure the position of the work vehicle 10 by a predetermined positioning method based on the satellite signal received from the satellite 20, automatically drive the work vehicle 10 based on the position information indicating the measured position of the work vehicle 10, and prohibit automatic driving when the work vehicle 10 stops for a predetermined time in a state where it can automatically travel by the first positioning method.

[0115] According to the above configuration, for example, when the work vehicle 10 stops continuously for a predetermined time in a state where it can automatically travel, automatic driving can be prohibited (stopped), so that unstable behavior caused by a deviation in the self-recognition position of the work vehicle 10 can be prevented. Therefore, a decrease in work accuracy can be suppressed. Note that in the above configuration, the vehicle control device 11 does not necessarily have a configuration for switching the positioning method.

[0116] The automatic driving system of the present invention may be composed of only the work vehicle 10, or may be configured to include each processing unit included in the vehicle control device 11. Further, the automatic driving system may be mounted on the work vehicle 10, or may be mounted outside the work vehicle 10, for example, on an operation terminal (tablet terminal, smartphone, etc.).

Explanation of Signs

[0117] 1: Automatic driving system 10: Work vehicle 20: Satellite 11: Vehicle control device 16: Positioning device 17: Operating device 20: Satellite 111: Travel processing unit 112: Reception processing unit 161: Positioning control unit 181: Positioning processing unit 182: Switching processing unit F: Field Lth: Threshold value L2: Distance difference P1: Self-recognition position P1´: Self-recognition position

Claims

1. Determining the position of a work vehicle by a predetermined positioning method based on a satellite signal received from a satellite; Automatically driving the work vehicle based on position information indicating the position of the work vehicle to be determined; When the work vehicle is in a state where it can automatically travel by a first positioning method, when the positioning method switches to a second positioning method having a different positioning accuracy from the first positioning method, enabling the prohibition of automatic driving; Permitting automatic driving until a predetermined time has elapsed after the positioning method switches from the first positioning method to the second positioning method; Setting the predetermined time when the positioning accuracy of the first positioning method is lower than the positioning accuracy of the second positioning method and the predetermined time when the positioning accuracy of the first positioning method is higher than the positioning accuracy of the second positioning method to different times; An automatic driving method for executing the above.

2. Setting the predetermined time when the positioning accuracy of the first positioning method is lower than the positioning accuracy of the second positioning method to a time shorter than the predetermined time when the positioning accuracy of the first positioning method is higher than the positioning accuracy of the second positioning method, The automatic driving method according to Claim 1.

3. When the positioning method switches from the first positioning method to the second positioning method, and the distance difference between the position of the work vehicle measured by the first positioning method and the position of the work vehicle measured by the second positioning method is equal to or greater than a threshold value, prohibiting automatic driving, The automatic driving method according to Claim 1 or 2.

4. When the positioning method switches from the first positioning method to the second positioning method, and the distance difference is less than the threshold value, permitting automatic driving, The automatic driving method according to Claim 3.

5. When the positioning method switches from the first positioning method to the second positioning method, and within the period until the predetermined time has elapsed, if the positioning method switches from the second positioning method to the first positioning method, permitting automatic driving, The automatic driving method according to any one of Claims 1 to 4.

6. When the positioning method switches from the first positioning method to the second positioning method, and within the period until the predetermined time has elapsed, if the positioning method does not switch from the second positioning method to the first positioning method, prohibiting automatic driving, The automatic driving method according to any one of Claims 1 to 5.

7. Receiving an operation for selecting the positioning method, The automatic driving method according to any one of claims 1 to 6, further comprising performing

8. When the work vehicle that automatically drives by the first positioning method stops and the stopped state continues for a predetermined time, prohibiting automatic driving The automatic driving method according to any one of claims 1 to 7, further comprising performing

9. When the work vehicle that automatically drives by the first positioning method stops and the stopped state continues for a predetermined time, and the distance difference between the position of the work vehicle measured at the time when the work vehicle stopped and the position of the work vehicle measured at the time when the predetermined time has elapsed is equal to or greater than a threshold value, prohibiting automatic driving The automatic driving method according to any one of claims 1 to 7, further comprising performing

10. Measuring the position of a work vehicle by a predetermined positioning method based on satellite signals received from satellites Automatically driving the work vehicle based on position information indicating the position of the work vehicle to be measured When the work vehicle is in a state where it can automatically drive by the first positioning method, when the positioning method switches to a second positioning method having a different positioning accuracy from the first positioning method, making it possible to prohibit automatic driving Permitting automatic driving by the second positioning method until a predetermined time elapses after the positioning method switches from the first positioning method to the second positioning method When the positioning method switches from the second positioning method to the first positioning method during the period until the predetermined time elapses after the positioning method switches from the first positioning method to the second positioning method, permitting automatic driving by the first positioning method Setting the predetermined time according to the history of the positioning state during past driving by the positioning method An automatic driving method for performing

11. Setting the predetermined time by specifying a location where the positioning state changes based on information on the driving history and calculating the time required to pass through the location The automatic driving method according to claim 10

12. A positioning processing unit that measures the position of a work vehicle by a predetermined positioning method based on satellite signals received from satellites A travel processing unit that automatically drives the work vehicle based on position information indicating the position of the work vehicle measured by the positioning processing unit Comprising When the traveling processing unit determines that the work vehicle is in a state where it can automatically travel using the first positioning method, and the positioning method switches to a second positioning method with a different positioning accuracy from the first positioning method, the traveling processing unit can prohibit automatic driving. The traveling processing unit permits automatic driving until a predetermined time has elapsed after the positioning method switches from the first positioning method to the second positioning method. The traveling processing unit sets different predetermined times depending on whether the positioning accuracy of the first positioning method is lower or higher than that of the second positioning method. An automatic driving system.

13. Determining the position of a work vehicle by a predetermined positioning method based on satellite signals received from satellites; Automatically driving the work vehicle based on position information indicating the position of the work vehicle to be determined; When the work vehicle is in a state where it can automatically travel using the first positioning method, and the positioning method switches to a second positioning method with a different positioning accuracy from the first positioning method, making it possible to prohibit automatic driving; Permitting automatic driving until a predetermined time has elapsed after the positioning method switches from the first positioning method to the second positioning method; Setting different predetermined times depending on whether the positioning accuracy of the first positioning method is lower or higher than that of the second positioning method; An automatic driving program for causing one or more processors to execute the above steps.

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