Work vehicle, work vehicle control system and control method

Abstract

To more accurately determine a travel direction even when a work vehicle is traveling at a low speed.SOLUTION: A work vehicle can perform automatic steering driving in both forward and backward directions. The work vehicle includes: a positioning device which outputs time-series position data of the work vehicle; a control device which performs steering control of the work vehicle on the basis of the time-series position data and a predetermined target route in the automatic steering mode; and a changeover switch which switches between forward travel and backward travel of the work vehicle. The control device determines a travel direction of the work vehicle on the basis of the time-series position data and a state of the changeover switch when a movement speed of the work vehicle is lower than a first speed in the automatic steering mode.SELECTED DRAWING: Figure 10

Description

[Technical Field]

[0001] The present disclosure relates to a work vehicle, a control system and a control method for a work vehicle. [Background technology]

[0002] Research and development is underway to automate work vehicles such as tractors used in farm fields. For example, work vehicles that run with automatic steering using positioning systems such as the Global Navigation Satellite System (GNSS), which enables precise positioning, have been put into practical use. Work vehicles that not only automatically steer but also automatically control speed have also been put into practical use.

[0003] Patent Document 1 discloses a technology for easily performing automatic steering when reversing. The work vehicle disclosed in Patent Document 1 is equipped with a control device that issues a command for automatic reverse steering when automatic steering is initiated by a steering selector switch so that the vehicle body travels backward along a planned travel line that corresponds to a travel reference line. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2020-54316 Summary of the Invention [Problem to be solved by the invention]

[0005] Work vehicles that operate under automatic steering are required to accurately detect their direction of travel (forward or reverse). The direction of travel can be determined, for example, from a sensor that detects the direction of rotation of gears included in the transmission, or from time-series position data acquired from a positioning system such as GNSS.

[0006] However, when a work vehicle is traveling at a very low speed (for example, less than 0.2 km / h), the conventional method cannot accurately detect the direction of travel.

[0007] The present disclosure provides systems and methods for more accurately detecting direction of travel of a work vehicle, even when the work vehicle is traveling at very low speeds. [Means for solving the problem]

[0008] A work vehicle according to an exemplary embodiment of the present disclosure is capable of automatic steering operation in both forward and reverse. The work vehicle includes a positioning device that outputs time-series position data of the work vehicle, a control device that, in an automatic steering mode, controls the steering of the work vehicle based on the time-series position data and a predetermined target route, and a selector switch for switching between forward and reverse movement of the work vehicle. In the automatic steering mode, when the movement speed of the work vehicle is lower than a first speed, the control device determines the traveling direction of the work vehicle based on the time-series position data and the state of the selector switch.

[0009] A general or specific aspect of the present disclosure may be realized by an apparatus, a system, a method, an integrated circuit, a computer program, or a computer-readable non-transitory storage medium, or any combination thereof. The computer-readable storage medium may include a volatile storage medium or a non-volatile storage medium. An apparatus may be composed of multiple devices. When an apparatus is composed of two or more devices, the two or more devices may be located in a single device or may be located separately in two or more separate devices. [Effects of the Invention]

[0010] According to the embodiments of the present disclosure, it is possible to more accurately detect the direction of travel of a work vehicle even when the work vehicle is traveling at a very slow speed. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a perspective view showing an example of the appearance of a work vehicle in a first embodiment. [Figure 2] 1 is a side view that schematically illustrates an example of a work vehicle and a work implement coupled to the work vehicle. [Figure 3] FIG. 1 is a block diagram showing an example of a schematic configuration of a work vehicle and a work machine. [Figure 4] FIG. 1 is a conceptual diagram showing an example of a work vehicle that performs positioning using RTK-GNSS. [Figure 5] FIG. 2 is a schematic diagram showing an example of an operation terminal and an operation switch group provided inside the cabin. [Figure 6] FIG. 10 is a diagram illustrating an example of the traveling of a work vehicle in automatic steering mode. [Figure 7] FIG. 1 is a diagram schematically illustrating an example of a target route for a work vehicle traveling in a farm field using automatic steering. [Figure 8] 4 is a flowchart showing an example of an operation during automatic steering executed by the control device. [Figure 9A] FIG. 1 is a diagram illustrating an example of a work vehicle traveling along a target route. [Figure 9B] FIG. 10 is a diagram illustrating an example of a work vehicle at a position shifted to the right from the target route. [Figure 9C] FIG. 10 is a diagram illustrating an example of a work vehicle that is shifted to the left from the target route. [Figure 9D] FIG. 10 is a diagram illustrating an example of a work vehicle facing in an inclined direction relative to a target route. [Figure 10] 10 is a flowchart showing an example of a method for determining a traveling direction according to a moving speed of a work vehicle. [Figure 11] FIG. 10 is a diagram showing an example of the operation of changing the automatic steering mode when the changeover switch is operated while the work vehicle is traveling at a low speed. [Figure 12] FIG. 10 is another diagram showing another example of the operation of changing the automatic steering mode when the change-over switch is operated while the work vehicle is traveling at a low speed. [Figure 13]FIG. 10 is a diagram illustrating yet another example of the operation of changing the automatic steering mode when the changeover switch is operated while the work vehicle is traveling at a low speed. [Figure 14] FIG. 10 is a diagram showing an example of a situation in which an operation of switching from forward to reverse is performed. [Figure 15] FIG. 10 is a diagram illustrating an example of a display on an operation terminal. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, embodiments of the present disclosure will be described. However, more detailed descriptions than necessary may be omitted. For example, detailed descriptions of already well-known matters and redundant descriptions of substantially identical configurations may be omitted. This is to avoid unnecessary redundancy in the following description and to facilitate understanding by those skilled in the art. Note that the inventors provide the accompanying drawings and the following description to enable those skilled in the art to fully understand the present disclosure, and do not intend for them to limit the subject matter described in the claims. In the following description, components having the same or similar functions are designated by the same reference numerals.

[0013] The following embodiments are examples, and the technology of the present disclosure is not limited to the following embodiments. For example, the numerical values, shapes, steps, the order of the steps, the layout of the display screen, and the like shown in the following embodiments are merely examples, and various modifications are possible as long as no technical contradiction occurs. Furthermore, one aspect can be combined with another aspect as long as no technical contradiction occurs.

[0014] An embodiment in which the technology of the present disclosure is applied to an agricultural tractor, which is an example of a work vehicle, will be described below. The technology of the present disclosure is not limited to tractors, but can be applied to any work vehicle that travels with automatic steering. The work vehicle may be, for example, a rice transplanter, a combine harvester, a mower, a harvester, a snowplow, or a construction vehicle.

[0015] (Embodiment) A work vehicle and a control system for the work vehicle in an exemplary embodiment of the present disclosure will be described.

[0016] The work vehicle in this embodiment is equipped with a control system that performs control to achieve automatic steering operation. The control system is a computer system including a storage device and a control device. The storage device includes one or more storage media and stores various data such as a target route for the work vehicle. The control device includes one or more computers, processors, or control circuits and controls the operation of the work vehicle. The control device can operate in both automatic steering mode and manual steering mode. The control device switches between the automatic steering mode and the manual steering mode in response to, for example, a driver's operation. In automatic steering mode, the control device controls the steering of the work vehicle so that the work vehicle travels along the target route based on the position of the work vehicle determined by the positioning device and the target route stored in the storage device. The positioning device is located inside or outside the work vehicle. The positioning device includes, for example, a GNSS receiver and determines the position of the work vehicle based on signals from multiple GNSS satellites and outputs time-series position data. The positioning device may also include devices other than the GNSS receiver, such as a LiDAR sensor or a camera. The position of the work vehicle can be estimated by matching data acquired by the LiDAR sensor or camera with a pre-prepared environmental map. The target route is a route that is set within the area in which the work vehicle will travel and serves as a target for travel. The target route is set and recorded in a storage device before automatic steering operation begins. The target route may be set within a farm field, for example.

[0017] The work vehicle in this embodiment is capable of automatic steering operation in both forward and reverse. The work vehicle is equipped with a selector switch for switching the work vehicle between forward and reverse. In automatic steering mode, the control device controls the steering of the work vehicle based on time-series position data output from the positioning device and a predetermined target route. In automatic steering mode, when the movement speed of the work vehicle is lower than a predetermined threshold (referred to as the "first speed"), the control device determines the direction of travel of the work vehicle based on the time-series position data and the state of the selector switch. Here, "movement speed" refers to the magnitude (absolute value) of the speed at which the work vehicle is moving and is also referred to as "vehicle speed." In the following description, the movement speed when reversing may be specifically referred to as the "reverse speed." "Determining the direction of travel" does not mean determining the exact direction of travel, but rather determining whether the work vehicle is moving forward or backward (or stopped). The first speed may be set to a very low speed, such as 0.2 kilometers per hour (0.2 km / h). In the following description, such a low speed range may be referred to as an "extremely low speed range."

[0018] When a work vehicle is traveling at extremely low speeds, conventional methods have difficulty determining the actual traveling direction of the work vehicle, i.e., whether it is moving forward or backward. When the work vehicle is traveling at a speed of, for example, 0.5 km / h or higher, the traveling direction of the work vehicle can be accurately detected using a sensor that detects the rotation of gears included in the transmission. Even at speeds below 0.5 km / h, if the traveling speed is, for example, 0.2 km / h or higher, the traveling direction can be determined with some degree of accuracy based on time-series position data obtained by a high-precision positioning device such as RTK (Real Time Kinematic)-GNSS. However, at extremely low speeds, such as below 0.2 km / h, it is difficult to accurately determine the traveling direction due to fluctuations in the position data, even when a high-precision positioning device such as RTK-GNSS is used. For example, when the driver switches the work vehicle between forward and reverse at extremely low speeds in automatic steering mode, it is difficult to accurately determine whether the work vehicle is traveling forward or backward. Therefore, there has been a problem in that, in extremely low speed ranges, it is not possible to continue reliable control such as automatic steering based on the results of determining the direction of travel of the work vehicle.

[0019] To solve this problem, the control device in this embodiment determines the traveling direction (forward or reverse) of the work vehicle in an extremely low speed range lower than the first speed based on the state of a selector switch (e.g., a shuttle lever or shuttle switch) that switches between forward and reverse, in addition to the time-series position data acquired by the positioning device. For example, the control device can be configured to determine that the work vehicle is moving in the traveling direction when the traveling direction estimated from the time-series position data matches the traveling direction indicated by the selector switch.

[0020] By introducing the above-described determination method, the reliability of the determination of the direction of travel can be improved by taking into account information indicating the state of a selector switch such as a shuttle lever, even in extremely low speed ranges where the reliability of the determination of the direction of travel based on the time-series position data output from the positioning device is low. As a result, the reliability of automatic steering in extremely low speed ranges can be improved.

[0021] The configuration and operation of the work vehicle of this embodiment will be described in more detail below.

[0022] <Configuration> FIG. 1 is a perspective view showing an example of the appearance of a work vehicle 100 in this embodiment. FIG. 2 is a side view that schematically shows an example of the work vehicle 100 and an implement 300 coupled to the work vehicle 100. The work vehicle in this embodiment is a tractor used in farm fields. The technology in this embodiment can also be applied to work vehicles other than tractors.

[0023] The work vehicle 100 in this embodiment is equipped with a positioning device 120 and one or more obstacle sensors 130. Although one obstacle sensor 130 is illustrated in FIG. 1, the obstacle sensors 130 may be provided at multiple locations on the work vehicle 100. Note that the obstacle sensors 130 are provided as needed. If not needed, the work vehicle 100 does not need to be equipped with the obstacle sensors 130.

[0024] As shown in Fig. 2, work vehicle 100 includes a vehicle body 101, a prime mover (engine) 102, and a transmission 103. Vehicle body 101 is provided with wheels 104 with tires and a cabin 105. Wheels 104 include a pair of front wheels 104F and a pair of rear wheels 104R. Inside cabin 105, a driver's seat 107, a steering device 106, a plurality of pedals 109, an operation terminal 200, and a group of switches for operation are provided. One or both of front wheels 104F and rear wheels 104R may be replaced with a plurality of wheels (crawlers) equipped with tracks rather than with tires.

[0025] The positioning device 120 in this embodiment includes a GNSS receiver. The GNSS receiver may include an antenna that receives signals from GNSS satellites and a processor that determines the position of the work vehicle 100 based on the signals received by the antenna. The positioning device 120 receives GNSS signals transmitted from multiple GNSS satellites and performs positioning based on the GNSS signals. GNSS is a general term for satellite positioning devices such as GPS (Global Positioning System), QZSS (Quasi-Zenith Satellite System, for example, Michibiki), GLONASS, Galileo, and BeiDou. The positioning device 120 in this embodiment is provided on top of the cabin 105, but may be provided in another location.

[0026] The positioning device 120 may include an inertial measurement unit (IMU). Signals from the IMU can be used to complement the position data. The IMU can measure the tilt and minute movements of the work vehicle 100. Data acquired by the IMU can be used to complement or correct position data based on satellite signals, thereby improving positioning performance.

[0027] The positioning device 120 may include other types of devices, such as a LiDAR sensor or a camera (including an image sensor), instead of or in addition to a GNSS receiver. If there are features that function as feature points in the environment in which the work vehicle 100 is traveling, the position of the work vehicle 100 can be estimated with high accuracy based on data acquired by the LiDAR sensor or camera and an environmental map that is pre-recorded in the storage device 170. The LiDAR sensor 110 or camera may be used in conjunction with the GNSS receiver. The position of the work vehicle 100 can be determined with higher accuracy by using the data acquired by the LiDAR sensor 110 or camera to correct or complement position data based on GNSS signals.

[0028] In the example shown in FIGS. 1 and 2 , the obstacle sensor 130 is provided at the rear of the vehicle body 101. The obstacle sensor 130 may also be provided at a location other than the rear of the vehicle body 101. For example, one or more obstacle sensors 130 may be provided at any of the sides, front, and cabin 105 of the vehicle body 101. The obstacle sensor 130 detects objects present around the work vehicle 100. The obstacle sensor 130 may include, for example, a laser scanner or an ultrasonic sonar. The obstacle sensor 130 outputs a signal indicating the presence of an obstacle when an object is present closer than a predetermined distance from the obstacle sensor 130. Multiple obstacle sensors 130 may be provided at different positions on the body of the work vehicle 100. For example, multiple laser scanners and multiple ultrasonic sonars may be provided at different positions on the body. Providing such a large number of obstacle sensors 130 reduces blind spots in monitoring obstacles around the work vehicle 100. As described above, the work vehicle 100 does not necessarily have to include the obstacle sensor 130.

[0029] The prime mover 102 may be, for example, a diesel engine. An electric motor may be used instead of a diesel engine. The transmission 103 can change the propulsive force and travel speed of the work vehicle 100 by changing gears. The transmission 103 can also switch the work vehicle 100 between forward and reverse travel.

[0030] The steering device 106 includes a steering wheel, a steering shaft connected to the steering wheel, and a power steering device that assists steering by the steering wheel. The front wheels 104F are steerable wheels, and the traveling direction of the work vehicle 100 can be changed by changing the turning angle (also referred to as the "steering angle"). The steering angle of the front wheels 104F can be changed by operating the steering wheel. The power steering device includes a hydraulic device or an electric motor that supplies an assisting force to change the steering angle of the front wheels 104F. When automatic steering is performed, the steering angle is automatically adjusted by the force of the hydraulic device or electric motor under control of a control device arranged inside the work vehicle 100.

[0031] The pedals 109 include an accelerator pedal, a clutch pedal, and a brake pedal. Each pedal is provided with a sensor that detects when the pedal is depressed.

[0032] A coupling device 108 is provided at the rear of the vehicle body 101. The coupling device 108 includes, for example, a three-point support device (also referred to as a "three-point link" or "three-point hitch"), a PTO (Power Take Off) shaft, a universal joint, and a communication cable. The coupling device 108 allows the work implement 300 to be attached to and detached from the work vehicle 100. The coupling device 108 can raise and lower the three-point link using, for example, a hydraulic device, to control the position or attitude of the work implement 300. Power can also be sent from the work vehicle 100 to the work implement 300 via the universal joint. The work vehicle 100 can cause the work implement 300 to perform a predetermined task while towing the work implement 300. The coupling device may be provided at the front of the vehicle body 101. In this case, the work implement can be connected to the front of the work vehicle 100.

[0033] 2 is a rotary tiller, but the work machine 300 is not limited to a rotary tiller. Any work machine, such as a mower, seeder, spreader, rake, baler, harvester, sprayer, or harrow, can be connected to the work vehicle 100 and used.

[0034] 3 is a block diagram showing an example of a schematic configuration of the work vehicle 100 and the work implement 300. The work vehicle 100 and the work implement 300 can communicate with each other via a communication cable included in the coupling device 108.

[0035] The work vehicle 100 in the example of FIG. 3 includes a positioning device 120, an obstacle sensor 130, an operation terminal 200, a drive unit 140, a sensor group 150, a control system 160, a communication interface (I / F) 190, an operation switch group 210, and a buzzer 220. These components are communicatively connected to each other via a bus. The positioning device 120 includes a GNSS receiver 121, an RTK receiver 122, an inertial measurement unit (IMU) 125, and a processor 126. The sensor group 150 may include, for example, a steering wheel sensor 152, a turning angle sensor 154, and a transmission (T / M) rotation sensor 156. The switch group 210 may include, for example, a clutch pedal 212, a selector switch 214 for switching between forward and reverse, and a switch 216 for switching between automatic steering mode and manual steering mode. The control system 160 includes a storage device 170 and a control device 180. The control device 180 includes multiple electronic control units (ECUs) 182, 183, 184, and 185. The work implement 300 includes a drive device 340, a control device 380, and a communication interface (I / F) 390. Note that Fig. 3 shows components that are relatively closely related to the automatic steering or automatic driving operations of the work vehicle 100, and does not show other components.

[0036] The GNSS receiver 121 in the positioning device 120 receives satellite signals transmitted from multiple GNSS satellites and generates GNSS data based on the satellite signals. The GNSS data is generated in a predetermined format, such as the NMEA-0183 format. The GNSS data may include, for example, values ​​indicating the identification number, elevation angle, azimuth angle, and reception strength of each satellite from which the satellite signal is received.

[0037] The positioning device 120 shown in FIG. 3 performs positioning of the work vehicle 100 using RTK (Real Time Kinematic)-GNSS. FIG. 4 is a conceptual diagram showing an example of a work vehicle 100 performing positioning using RTK-GNSS. Positioning using RTK-GNSS uses correction signals transmitted from a reference station 60 in addition to satellite signals transmitted from multiple GNSS satellites 50. The reference station 60 may be installed near the field where the work vehicle 100 will be traveling (for example, within 10 km of the work vehicle 100). The reference station 60 generates correction signals, for example in RTCM format, based on the satellite signals received from the multiple GNSS satellites 50 and transmits them to the positioning device 120. The RTK receiver 122 includes an antenna and a modem and receives the correction signals transmitted from the reference station 60. A processor 126 of the positioning device 120 corrects the positioning results obtained by the GNSS receiver 121 based on the correction signals. By using RTK-GNSS, it is possible to perform positioning with an accuracy of, for example, a few centimeters. Position information including latitude, longitude, and altitude information is acquired through highly accurate positioning using RTK-GNSS. The positioning device 120 calculates the position of the work vehicle 100, for example, at a frequency of approximately 1 to 10 times per second. The positioning device 120 outputs time-series position data including information on the calculated position (coordinates).

[0038] The positioning method is not limited to RTK-GNSS, and any positioning method (such as interferometric positioning or relative positioning) that can obtain position information with the required accuracy can be used. For example, positioning may be performed using a Virtual Reference Station (VRS) or a Differential Global Positioning System (DGPS). If position information with the required accuracy can be obtained without using a correction signal transmitted from the reference station 60, the positioning information may be generated without using a correction signal. In this case, the positioning device 120 does not need to be equipped with the RTK receiver 122.

[0039] The positioning device 120 shown in FIG. 3 further includes an IMU 125. The IMU 125 includes a three-axis acceleration sensor and a three-axis gyroscope. The IMU 125 may also include a direction sensor such as a three-axis geomagnetic sensor. The IMU 125 functions as a motion sensor and can output signals indicating various quantities such as the acceleration, velocity, displacement, and attitude of the work vehicle 100. The processor 126 of the positioning device 120 can estimate the position and orientation of the work vehicle 100 with higher accuracy based on the signal output from the IMU 125 in addition to the GNSS signal and correction signal. The signal output from the IMU 125 can be used to correct or complement the position calculated based on the GNSS signal and correction signal. The IMU 125 outputs a signal at a higher frequency than the GNSS signal. Using this high-frequency signal, the position and orientation of the work vehicle 100 can be measured at a higher frequency (e.g., 10 Hz or higher). Instead of the IMU 125, a three-axis acceleration sensor and a three-axis gyroscope may be separately provided. The IMU 125 may be provided as a device separate from the positioning device 120. Note that at least some of the functions of the processor 126 in the positioning device 120 may be executed by any of the ECUs in the control device 180.

[0040] The positioning device 120 may include other types of sensors, such as a LiDAR sensor or an image sensor, in addition to or instead of the GNSS receiver 121, the RTK receiver 122, and the IMU 125. If there are features that can serve as landmarks in the environment in which the work vehicle 100 travels, the position and orientation of the work vehicle 100 can be estimated by matching the sensor data output from these sensors with an environmental map. In such a configuration, an external sensor, such as a LiDAR sensor or an image sensor, may be included in the positioning device.

[0041] The drive device 140 includes various devices necessary for the travel of the work vehicle 100 and the driving of the work implement 300, such as the aforementioned prime mover 102, transmission 103, steering device 106, and coupling device 108. The prime mover 102 may be equipped with an internal combustion engine such as a diesel engine. The drive device 140 may be equipped with an electric motor for traction instead of or in addition to the internal combustion engine.

[0042] The steering wheel sensor 152 measures the rotation angle of the steering wheel of the work vehicle 100. The turning angle sensor 154 measures the turning angle of the front wheels 104F, which are the steered wheels.

[0043] The T / M rotation sensor 156 is a sensor for measuring the rotational speed of the axle connected to the wheel 104, i.e., the number of rotations per unit time. The T / M rotation sensor 156 may be a sensor that uses, for example, a magnetoresistive element (MR), a Hall element, or an electromagnetic pickup. The T / M rotation sensor 156 outputs, for example, a pulse signal that is proportional to the rotational speed of a gear included in the transmission. The T / M rotation sensor 156 may be used to determine the vehicle speed and direction of travel of the work vehicle 100.

[0044] The measurement values ​​from the steering wheel sensor 152, the turning angle sensor 154, and the T / M rotation sensor 156 are used for steering control by the control device 180.

[0045] Storage device 170 includes one or more storage media, such as flash memory or a magnetic disk. Storage device 170 stores various data generated by each sensor and control device 180. The data stored in storage device 170 may include map data of the environment in which work vehicle 100 is traveling, and target route data for automatic steering. Storage device 170 also stores computer programs that cause each ECU in control device 180 to perform various operations, which will be described later. Such computer programs may be provided to work vehicle 100 via a storage medium (e.g., a semiconductor memory or an optical disk) or an electric communication line (e.g., the Internet). Such computer programs may be sold as commercial software.

[0046] The control device 180 includes multiple ECUs. The multiple ECUs include an ECU 182 for driving control, an ECU 183 for automatic steering control, an ECU 184 for work equipment control, and an ECU 185 for display control. The ECU 182 controls the speed of the work vehicle 100 by controlling the prime mover 102, transmission 103, accelerator, and brake included in the drive unit 140. The ECU 182 also controls the steering of the work vehicle 100 by controlling the hydraulic device or electric motor included in the steering unit 106 based on measurements from the steering wheel sensor 152. The ECU 183 performs calculations and controls to achieve automatic steering operation based on signals output from the positioning device 120, the steering wheel sensor 152, the turning angle sensor 154, the T / M rotation sensor 156, etc. During automatic steering operation, the ECU 183 sends a command to the ECU 182 to change the steering angle. The ECU 182 changes the steering angle by controlling the steering device 106 in response to the command. The ECU 184 controls the operation of the coupling device 108 to cause the work implement 300 to perform the desired operation. The ECU 184 also generates a signal to control the operation of the work implement 300 and transmits this signal to the work implement 300 from the communication I / F 190. The ECU 185 controls the display of the operation terminal 200. For example, the ECU 185 causes the display device of the operation terminal 200 to display various items such as a map of the field, the position and target route of the work vehicle 100 on the map, pop-up notifications, and setting screens.

[0047] Through the operation of these ECUs, the control device 180 realizes driving by manual steering or automatic steering. During automatic steering driving, the control device 180 controls the drive device 140 based on the position of the work vehicle 100 measured or estimated by the positioning device 120 and the target route stored in the storage device 170. In this way, the control device 180 can cause the work vehicle 100 to travel along the target route.

[0048] The multiple ECUs included in the control device 180 can communicate with each other in accordance with a vehicle bus standard such as CAN (Controller Area Network). In FIG. 3, ECUs 182, 183, 184, and 185 are shown as individual blocks, but the functions of each of these may be realized by multiple ECUs. Also, an on-board computer that integrates at least some of the functions of ECUs 182, 183, 184, and 185 may be provided. The control device 180 may include ECUs other than ECUs 182, 183, 184, and 185. Any number of ECUs may be provided depending on the functions. Each ECU includes a control circuit including one or more processors.

[0049] The communication I / F 190 is a circuit that communicates with the communication I / F 390 of the work implement 300. The communication I / F 190 transmits and receives signals compliant with ISOBUS standards such as ISOBUS-TIM to and from the communication I / F 390 of the work implement 300. This makes it possible to cause the work implement 300 to perform desired operations and to obtain information from the work implement 300. The communication I / F 190 may communicate with an external computer via a wired or wireless network. The external computer may be, for example, a server computer in a farming support system that centrally manages information about farm fields on the cloud and supports agriculture by utilizing data on the cloud.

[0050] The operation terminal 200 is a terminal through which a user performs operations related to the travel of the work vehicle 100 and the operation of the work implement 300, and is also referred to as a virtual terminal (VT). The operation terminal 200 may include a display device such as a touch screen and / or one or more buttons. By operating the operation terminal 200, a user can perform various operations, such as switching the automatic steering mode on / off, setting the initial position of the work vehicle 100, setting a target route, recording or editing a map, and switching the work implement 300 on / off. At least some of these operations can also be achieved by operating the operation switch group 210. FIG. 3 shows a clutch pedal 212, a forward / reverse switch 214, and an automatic steering switch 216 as examples of the operation switch group 210. The display on the operation terminal 200 is controlled by the ECU 185.

[0051] Buzzer 220 is an audio output device that emits a warning sound to alert the user to an abnormality. For example, buzzer 220 emits a warning sound when work vehicle 100 deviates from the target route by a predetermined distance or more during automatic steering operation. Instead of buzzer 220, a similar function may be realized by a speaker of operation terminal 200.

[0052] The drive unit 340 in the work implement 300 performs the operations required for the work implement 300 to perform a predetermined task. The drive unit 340 includes devices appropriate for the intended use of the work implement 300, such as a hydraulic system, an electric motor, or a pump. The control device 380 controls the operation of the drive unit 340. The control device 380 causes the drive unit 340 to perform various operations in response to signals transmitted from the work vehicle 100 via the communication I / F 390. The control device 380 can also transmit signals appropriate to the state of the work implement 300 from the communication I / F 390 to the work vehicle 100.

[0053] 5 is a diagram showing an example of an operation terminal 200 and an operation switch group 210 provided inside the cabin 105. The switch group 210 includes a plurality of switches that can be operated by a user and is arranged inside the cabin 105. The switch group 210 may include, for example, a switch 216 for switching between an automatic steering (auto-steer) mode and a manual steering (manual-steer) mode, a selector switch 214 (e.g., a shuttle lever or shuttle switch) for switching between forward and reverse, a switch for selecting a gear stage of the main transmission or auxiliary transmission, and a switch for raising and lowering the work machine 300. The switch group 210 also includes a plurality of pedals 109 (e.g., a clutch pedal 212) that are not shown in FIG. 5.

[0054] <Operation> Next, the operation of the work vehicle 100 will be described. The control device 180 in this embodiment can switch between manual steering mode and automatic steering mode in response to operation by the user (e.g., the driver) of the work vehicle 100. In manual steering mode, the control device 180 controls steering by driving the power steering device in response to operation of the steering wheel by the user. In automatic steering mode, the control device 180 controls steering by driving the power steering device based on the position of the work vehicle 100 measured by the positioning device 120 and a pre-recorded target route. Even in automatic steering mode, the speed is adjusted by accelerator and brake operation by the user.

[0055] FIG. 6 is a diagram showing an example of the travel of the work vehicle 100 in automatic steering mode. (a) of FIG. 6 schematically shows the work vehicle 100 traveling along a straight-line target route P. (b) of FIG. 6 schematically shows the work vehicle 100 traveling along a curved target route P. (c) of FIG. 6 schematically shows the work vehicle 100 traveling along a target route P that includes two adjacent straight routes and a curved route connecting them. The target route P is set in advance and recorded in the storage device 170. When the work vehicle 100 is traveling in automatic steering mode, the control device 180 calculates the deviation between the position and orientation of the work vehicle 100 measured by the positioning device 120 and the target route P, and repeatedly controls the steering device to reduce the deviation. This causes the work vehicle 100 to travel along the target route P.

[0056] FIG. 7 is a diagram schematically illustrating an example of a target route for the work vehicle 100 traveling through a field using automatic steering. In this example, the field includes a work area 70 where the work vehicle 100 and the work implement 300 will work, and a headland 80 located near the outer periphery of the field. The user can set in advance which areas on the field map correspond to the work area 70 and the headland 80 by operating the operation terminal 200. The target route includes multiple parallel main paths P1 and multiple turning paths P2 connecting the multiple main paths P1. The main paths P1 are located within the work area 70, and the turning paths P2 are located in the headland 80. The dashed line in FIG. 7 represents the working width of the work implement 300. The working width is set in advance and recorded in the storage device 170. The working width can be set by the user operating the operation terminal 200 and recorded in the storage device 170. Alternatively, the working width may be automatically recognized when the work implement 300 is connected to the work vehicle 100 and recorded in the storage device 170. The spacing between the multiple main paths P1 is adjusted to the working width. The target path may be determined based on a user operation before automatic steering operation is started.

[0057] Next, an example of control performed by the control device 180 during automatic steering will be described.

[0058] FIG. 8 is a flowchart showing an example of the operation during automatic steering executed by the control device 180. The control device 180 performs automatic steering operation by executing the operations of steps S101 to S105 shown in FIG. 8 while the work vehicle 100 is traveling. The control device 180 first acquires data indicating the position of the work vehicle 100 generated by the positioning device 120 (step S101). Next, the control device 180 calculates the deviation between the position of the work vehicle 100 and the target route (step S102). The deviation represents the distance between the position of the work vehicle 100 at that time and the target route. The control device 180 determines whether the calculated position deviation exceeds a preset threshold (step S103). If the deviation exceeds the threshold, the control device 180 changes the steering angle by changing the control parameters of the steering device included in the drive device 140 so that the deviation is reduced. If the deviation does not exceed the threshold in step S103, the operation of step S104 is omitted. In the following step S105, the control device 180 determines whether or not a command to end the operation has been received. The command to end the operation can be issued, for example, when the user uses the operation terminal 200 to instruct the automatic steering mode to be stopped, or when the work vehicle 100 has reached its destination. If a command to end the operation has not been issued, the process returns to step S101, and the same operation is performed based on the newly measured position of the work vehicle 100. The control device 180 repeats the operations of steps S101 to S105 until a command to end the operation is issued. The above operations are performed by the ECU 183 in the control device 180.

[0059] 8, the control device 180 controls the drive device 140 based only on the deviation between the position of the work vehicle 100 identified by the positioning device 120 and the target route, but the control may also take into consideration the deviation in heading. For example, when the heading deviation, which is the angular difference between the direction of the work vehicle 100 identified by the positioning device 120 and the direction of the target route, exceeds a preset threshold, the control device 180 may change the control parameters (e.g., steering angle) of the steering device of the drive device 140 in accordance with the deviation.

[0060] An example of steering control by the control device 180 will be described in more detail below with reference to FIGS. 9A to 9D.

[0061] FIG. 9A is a diagram showing an example of a work vehicle 100 traveling along a target route P. FIG. 9B is a diagram showing an example of a work vehicle 100 shifted to the right from the target route P. FIG. 9C is a diagram showing an example of a work vehicle 100 shifted to the left from the target route P. FIG. 9D is a diagram showing an example of a work vehicle 100 facing in an inclined direction with respect to the target route P. In these figures, the pose indicating the position and orientation of the work vehicle 100 measured by the positioning device 120 is expressed as r(x, y, θ). (x, y) are coordinates representing the position of the reference point of the work vehicle 100 in the XY coordinate system, which is a two-dimensional coordinate system fixed to the Earth. In the examples shown in FIGS. 9A to 9D, the reference point of the work vehicle 100 is located at the position where the GNSS antenna on the cabin is installed, but the position of the reference point is arbitrary. θ is an angle representing the measured orientation of the work vehicle 100. In the examples shown, the target route P is parallel to the Y axis, but generally, the target route P is not necessarily parallel to the Y axis.

[0062] As shown in FIG. 9A, if the position and orientation of the work vehicle 100 do not deviate from the target route P, the control device 180 maintains the steering angle and speed of the work vehicle 100 unchanged.

[0063] As shown in Fig. 9B, when the position of work vehicle 100 has shifted to the right from target route P, control device 180 changes the steering angle by changing the rotation angle of the steering wheel included in drive device 140 so that the traveling direction of work vehicle 100 tilts to the left and approaches route P. At this time, the speed may also be changed in addition to the steering angle. The magnitude of the steering angle can be adjusted, for example, according to the magnitude of position deviation Δx.

[0064] As shown in Fig. 9C, when the position of the work vehicle 100 has shifted to the left from the target route P, the control device 180 changes the steering angle by changing the rotation angle of the steering wheel so that the traveling direction of the work vehicle 100 tilts to the right and approaches the route P. In this case, too, the speed may be changed in addition to the steering angle. The amount of change in the steering angle may be adjusted, for example, according to the magnitude of the position deviation Δx.

[0065] As shown in FIG. 9D , when the position of the work vehicle 100 is not significantly deviated from the target route P but the heading is different from the direction of the target route P, the control device 180 changes the steering angle to reduce the azimuth deviation Δθ. In this case, the speed may also be changed in addition to the steering angle. The magnitude of the steering angle may be adjusted, for example, according to the magnitudes of the position deviation Δx and the azimuth deviation Δθ. For example, the smaller the absolute value of the position deviation Δx, the greater the amount of change in the steering angle according to the azimuth deviation Δθ. When the absolute value of the position deviation Δx is large, the steering angle will be changed significantly to return to the route P, which inevitably increases the absolute value of the azimuth deviation Δθ. Conversely, when the absolute value of the position deviation Δx is small, it is necessary to bring the azimuth deviation Δθ closer to zero. For this reason, it is appropriate to relatively increase the weight of the azimuth deviation Δθ (i.e., the control gain) used to determine the steering angle.

[0066] Control techniques such as PID control or MPC control (model predictive control) can be applied to the steering control and speed control of work vehicle 100. By applying these control techniques, it is possible to smooth the control that brings work vehicle 100 closer to target path P.

[0067] If an obstacle is detected by one or more obstacle sensors 130 while traveling, the control device 180 may stop the work vehicle 100 or switch from automatic steering mode to manual steering mode. The control device 180 may control the drive device 140 to avoid the obstacle when an obstacle is detected.

[0068] <Judging direction of travel at low speeds> Next, an example of a method for determining the traveling direction when work vehicle 100 is moving at a low speed in automatic steering mode will be described.

[0069] When the work vehicle 100 is traveling in automatic steering mode, the control device 180 can determine the traveling direction of the work vehicle 100, i.e., whether it is traveling forward or backward, based on the signal output from the T / M rotation sensor 156. However, when the traveling speed of the work vehicle 100 is low, for example, below 0.5 km / h, the axle rotation speed is too low and it is not possible to determine the traveling direction based on the signal from the T / M rotation sensor 156. For this reason, in such low-speed ranges, the control device 180 can determine the traveling direction based on time-series position data output from a positioning device 120 that uses, for example, RTK-GNSS. However, even when a positioning device 120 capable of such high-accuracy positioning is used, in extremely low-speed ranges, such as below 0.2 km / h, the reliability of determining the traveling direction based on the time-series position data output from the positioning device 120 decreases. This is because the actual displacement of the work vehicle 100 is too small compared to the variation in coordinate values ​​in the time-series position data, making it difficult to determine whether the vehicle is traveling forward or backward. Therefore, in this embodiment, in an extremely low speed range where the vehicle speed is, for example, below 0.2 km / h, the traveling direction is determined taking into consideration the state of the changeover switch 214 that switches between forward and reverse, in addition to the time-series position data from the positioning device 120. This improves the reliability of the traveling direction determination in an extremely low speed range.

[0070] Figure 10 is a flowchart showing an example of a method for determining the direction of travel in accordance with the travel speed (vehicle speed) of work vehicle 100. The operation shown in Figure 10 is executed by ECU 183 in control device 180. The operation of each step will be described below.

[0071] In step S121, the control device 180 determines whether the vehicle speed is equal to or greater than a first threshold. The first threshold may be set to a relatively low value, such as 0.5 km / h. The first threshold may be changed as appropriate depending on the system configuration or required performance. The first threshold may be set to a value between 0.3 km / h and 1.0 km / h, or between 0.4 km / h and 0.7 km / h, for example. If the vehicle speed is equal to or greater than the first threshold, the process proceeds to step S123. If the vehicle speed is less than the first threshold, the process proceeds to step S122.

[0072] In step S122, the control device 180 determines whether the vehicle speed is equal to or greater than a second threshold value that is smaller than the first threshold value. The second threshold value corresponds to the aforementioned "first speed" and may be set to a low value such as 0.2 km / h. The second threshold value may be changed as appropriate depending on the system configuration or required performance. The second threshold value (first speed) may be set to a value between 0.1 km / h and 0.3 km / h, or between 0.15 km / h and 0.25 km / h, for example. If the vehicle speed is equal to or greater than the second threshold value, the process proceeds to step S124. If the vehicle speed is less than the second threshold value, the process proceeds to step S125.

[0073] In steps S121 and S122, the control device 180 can estimate the vehicle speed based on the signal output from the T / M rotation sensor 156 or the time-series position data output from the positioning device 120. For example, if the vehicle speed is equal to or greater than a first threshold, the vehicle speed can be estimated based on the signal output from the T / M rotation sensor 156. On the other hand, if the vehicle speed is less than the first threshold, the vehicle speed can be estimated based on the time-series position data output from the positioning device 120. A signal output from the IMU 125 may be used to estimate the vehicle speed.

[0074] In step S123, the control device 180 determines the traveling direction (i.e., forward or reverse) of the work vehicle 100 based on the signal output from the T / M rotation sensor 156. When the vehicle speed is equal to or greater than the first threshold value, the traveling direction can be accurately determined based on the signal output from the T / M rotation sensor 156.

[0075] In step S124, the control device 180 determines the traveling direction of the work vehicle 100 based on the time-series position data output from the positioning device 120. If the vehicle speed is below the first threshold, it becomes impossible to accurately determine the traveling direction based on the signal output from the T / M rotation sensor 156. For this reason, the control device 180 determines the traveling direction based on the time-series position data output from the positioning device 120, i.e., the change over time in coordinate values.

[0076] In step S125, the control device 180 determines the traveling direction of the work vehicle 100 based on the time-series position data output from the positioning device 120 and the state of the change-over switch 214 for switching between forward and reverse. When the vehicle speed is lower than a second threshold (first speed), even if the positioning device 120 outputs highly accurate position data using RTK-GNSS, there is a possibility that an error will occur in the traveling direction determination based on the position data. Therefore, when the vehicle speed is lower than the second threshold (first speed), the traveling direction is determined based on the state of the change-over switch 214 in addition to the time-series position data output from the positioning device 120. For example, when the traveling direction estimated from the time-series position data matches the traveling direction indicated by the change-over switch 214, the control device 180 determines that the work vehicle 100 is moving in that traveling direction. This improves the reliability of the traveling direction determination.

[0077] Control device 180 repeats the operations of steps S121 to S125 during operation of work vehicle 100. The determination of the traveling direction shown in Fig. 10 is performed regardless of whether or not automatic steering operation is in progress.

[0078] The above operation makes it possible to more accurately determine the direction of travel of work vehicle 100 even in extremely low speed ranges where the vehicle speed is below the first speed. This improves the reliability of automatic steering in extremely low speed ranges.

[0079] In this embodiment, when the work vehicle 100 is in the automatic steering mode and the changeover switch 214 is operated to switch between forward and reverse while the travel speed of the work vehicle 100 is lower than the first speed, the control device 180 may transition to a standby mode in which the automatic steering is temporarily canceled. Furthermore, if a predetermined return condition is met within a predetermined time (hereinafter, sometimes referred to as the "first time") from the time of transition to the standby mode, the control device 180 may return to the automatic steering mode from the standby mode. The return condition may include, for example, a condition (first condition) that "the traveling direction estimated from the time-series position data matches the traveling direction indicated by the changeover switch 214." The first time may be, for example, 5 or 10 seconds, and may be set in advance. The first time may be set, for example, to a length of 1 second or more and 30 seconds or less.

[0080] The return condition may further include a condition (second condition) that "the travel speed of the work vehicle is equal to or greater than a second speed." Here, the second speed may be set to a value equal to or less than the first speed. For example, if the first speed is 0.2 km / h, the second speed may be set to a value lower than the first speed, such as 0.1 km / h or 0.15 km / h. The second speed may be set to the same value as the first speed, or may be set to a value higher than the first speed.

[0081] The work vehicle 100 in this embodiment is equipped with a prime mover 102, a transmission 103, and a clutch that switches between transmitting and not transmitting power from the prime mover 102 to the transmission 103. The clutch is operated by a clutch pedal 212. In this case, the return condition may further include a condition (third condition) that the clutch is engaged. For example, the control device 180 can determine that the clutch is engaged when the clutch pedal 212 is not depressed, i.e., when there is no input from the user to disengage the clutch. The control device 180 can determine whether the clutch is engaged based on a signal from a sensor provided on the clutch pedal 212. When the clutch is not engaged (i.e., the clutch is disengaged), power from the prime mover 102 is not transmitted to the transmission 103, and this does not result in a change in the rotational direction of the axle, and therefore the return condition may include the third condition.

[0082] If the travel speed of work vehicle 100 exceeds the first speed within a predetermined time after transitioning to standby mode, control device 180 may return to automatic steering mode regardless of whether other conditions such as the first condition are met. This is because when the travel speed exceeds the first speed, it is possible to relatively accurately determine the direction of travel based on the time-series position data from positioning device 120, regardless of the state of changeover switch 214.

[0083] If the return condition is not satisfied within a predetermined time from the time of transition to the standby mode, the control device 180 may transition from the standby mode to the manual steering mode. In the manual steering mode, the control device 180 maintains the manual steering mode until the user performs an operation to switch to the automatic driving mode.

[0084] Hereinafter, with reference to FIGS. 11 to 13, a specific example of the operation when the changeover switch 214 is used to change between forward and reverse travel during low-speed travel will be described.

[0085] 11 to 13 show an example of the operation of changing the automatic steering mode when the selector switch 214 (in this example, the shuttle lever) is operated while the work vehicle 100 is traveling at a low speed. The graphs shown in FIGS. 11 to 13 show an example of the change over time in the actual vehicle speed (absolute value) of the work vehicle 100. Below the graphs are shown the actual traveling direction of the work vehicle 100, the traveling direction based on the time-series position data output from the positioning device 120, the traveling direction indicated by the shuttle lever, and the automatic steering status. Forward is represented as "F," reverse is represented as "R," the automatic steering mode status is represented as "Active," the standby mode status is represented as "Pending," and the manual steering mode status is represented as "Disengaged." The traveling direction based on the time-series position data is the traveling direction based on GNSS data and can be estimated by the processor 126 of the positioning device 120, for example.

[0086] In the example of FIG. 11 , while the work vehicle 100 is moving forward at 0.15 km / h in the automatic steering mode, at time t the user (driver) operates the changeover switch 214 (shuttle lever) to switch from forward to reverse. This type of operation may be performed, for example, as illustrated in FIG. 14 , when the work vehicle 100 is turned on a headland 80 outside the work area 70 in a farm field, and then the work vehicle 100 is temporarily moved in reverse to approach the target route P. In response to the shuttle lever switching operation, the control device 180 temporarily cancels the automatic steering and transitions to a standby mode (Pending). Even after the user switches the shuttle lever, the forward state continues for a while, and at some point the actual traveling direction of the work vehicle 100 switches to a reverse direction. Thereafter, the reverse speed of the work vehicle 100 gradually increases, and at some point the traveling direction estimated based on the time-series position data changes from a forward direction (F) to a reverse direction (R). As a result, the traveling direction estimated based on the time-series position data and the traveling direction indicated by the shuttle lever match. In the example of FIG. 11, the two traveling directions match before a predetermined time x (for example, 5 or 10 seconds) has elapsed from time t. When the control device 180 detects that the traveling direction based on the time-series position data and the traveling direction indicated by the shuttle lever match before the predetermined time x has elapsed since detecting the forward / reverse switching operation, it changes the automatic steering state from "Pending" to "Active." In other words, the automatic steering mode is restored from standby mode. Thereafter, the control device 180 causes the work vehicle 100 to move backward in automatic steering mode.

[0087] On the other hand, in the example shown in FIG. 12, the traveling direction estimated based on the time-series position data output from the positioning device 120 remains in the forward direction (F) even after a predetermined time x has elapsed since the shuttle lever was switched. In such a case, the control device 180 changes the automatic steering state from "Pending" to "Disengaged" when the predetermined time x has elapsed since the time t when the switching operation was performed. In other words, the automatic steering mode is switched from the standby state to the manual steering mode. After that, the manual steering mode continues even if the traveling direction based on the time-series position data reverses to the reverse direction (R). Thereafter, the manual steering mode is maintained until the user performs an operation to start the automatic steering mode.

[0088] When the mode is shifted from standby mode to manual steering mode, the control device 180 may display a warning on a display device such as the operation terminal 200 or may cause the buzzer 220 to emit a warning sound. Furthermore, the control device 180 may cause a display device to display whether the current mode is automatic steering mode, standby mode, or manual steering mode while the work vehicle 100 is traveling. The control device 180 may also cause the display device of the operation terminal 200 to display the results of its determination of the traveling direction of the work vehicle 100.

[0089] FIG. 15 is a diagram showing an example of the display of the operation terminal 200. In this example, the control device 180 displays a map of the farm field including the work vehicle 100 and the target route P on the display of the operation terminal 200. The control device 180 may display the result of the determination of the traveling direction (forward or reverse) of the work vehicle 100 on the display using an arrow as shown in FIG. 15. In the example of FIG. 15, an icon 86 indicating whether the automatic steering mode is on or off and a warning message 92 are displayed. The control device 180 may indicate whether the current mode is the automatic steering mode (Active), the standby mode (Pending), or the manual steering mode (Disengaged) by, for example, the color of the icon 86. For example, the color of the icon 86 may change so that "Active" is green, "Pending" is yellow, and "Disengaged" is gray. When the control device 180 switches from "Pending" to "Disengaged," it may also cause the operation terminal 200 to display a warning message 92 urging the user to increase speed, such as "Automatic steering has been released. Please increase speed to 0.2 km / h or more." In addition to displaying such a warning, the control device 180 may also cause the buzzer 220 to emit a warning sound. By outputting such a warning, it is possible to effectively notify the user that automatic steering has been released.

[0090] 11 and 12, the user operates the change-over switch 214 to switch from forward to reverse while the work vehicle 100 is moving forward at a low speed, but the user may also switch from reverse to forward. The control device 180 may also perform control similar to that described above when the user operates the change-over switch 214 to switch from reverse to forward while the work vehicle 100 is moving backward at a low speed.

[0091] In the example of FIG. 11, the state is restored from "Pending" to "Active" when the traveling direction based on the time-series position data matches the traveling direction indicated by the changeover switch 214 within a predetermined time x (first time) after the user performs a forward / reverse switching operation. That is, the state is restored from the standby state to the automatic steering mode when the first condition described above is satisfied. In addition to the first condition, a second condition that the vehicle speed exceeds a second speed may be imposed. That is, the control device 180 may restore from the standby mode to the automatic steering mode when a restoration condition including the first and second conditions described above is satisfied. The second speed may be set to a value lower than the first speed, such as 0.1 km / h.

[0092] FIG. 13 is a diagram showing an example in which the automatic steering mode is restored when both the first and second conditions are satisfied in the standby mode. In the example of FIG. 13, the timing at which the traveling direction estimated based on the time-series position data switches from the forward direction (F) to the reverse direction (R) is earlier than in the example of FIG. 11. At that timing, the vehicle speed is less than the second speed (0.1 km / h in the example of FIG. 13), so the automatic steering has not yet become "Active" and remains in "Pending" (standby mode). Thereafter, when the reverse speed of the vehicle 100 increases and exceeds the second speed, the automatic steering mode is switched from "Pending" to "Active." As in this example, the control device 180 may restore the automatic steering mode from the standby mode when the restoration conditions, including both the first and second conditions, are satisfied.

[0093] The control shown in FIGS. 11 to 13 is based on the premise that the user depresses the clutch pedal 212 to operate the selector switch 214 (shuttle lever), and then returns the clutch pedal 212 to a non-depressed state (i.e., the clutch is engaged). That is, the control device 180 returns from standby mode to automatic steering mode when the return conditions including the first and third conditions described above, or the return conditions including all of the first, second, and third conditions, are satisfied. However, after operating the selector switch 214, the user may continue to depress the clutch pedal 212 without releasing it. In this case, the clutch is disengaged, and the actual traveling direction of the work vehicle 100 does not change. The user may also switch the selector switch 214 to neutral to stop the work vehicle 100. In this case, power is cut off within the transmission, and the actual traveling direction of the work vehicle 100 does not change. To deal with such cases, the control device 180 may switch from the automatic steering mode to the manual steering mode when the selector switch 214 remains in a neutral state or the clutch is disengaged (e.g., the clutch pedal 212 is depressed) for a predetermined time or more (hereinafter, sometimes referred to as the "second time"). The second time may be the same as or different from the first time. The second time may be set to, for example, a length of 1 second or more and 30 seconds or less. In the automatic steering mode, the control device 180 may continue the automatic steering mode if the traveling speed is equal to or greater than a first speed (e.g., 0.2 km / h) until the second time has elapsed since the selector switch 214 became neutral or the clutch was disengaged. If the traveling speed is less than the first speed, the control device 180 may transition from the automatic steering mode to a standby mode. This control allows the mode to be appropriately switched when the user continues to depress the clutch pedal 212 or switches the shuttle lever to neutral.

[0094] As described above, in this embodiment, as shown in FIG. 10 , in automatic steering mode, when the vehicle speed is equal to or greater than the first threshold value (third speed), the control device 180 determines the traveling direction based on the signal output from the T / M rotation sensor 156. Furthermore, when the vehicle speed is equal to or greater than the second threshold value (first speed) and less than the first threshold value (third speed), the control device 180 determines the traveling direction of the work vehicle 100 based on the time-series position data regardless of the state of the change-over switch 214. However, this type of control is merely an example. Without setting the third speed, when the vehicle speed is equal to or greater than the first speed, the traveling direction may be determined based on the time-series position data regardless of the state of the change-over switch 214. Alternatively, when the first speed is set to a value close to 0.5 km / h, for example, the traveling direction may be determined based on the signal output from the T / M rotation sensor 156 regardless of the state of the change-over switch 214 when the vehicle speed is equal to or greater than the first speed.

[0095] In the above embodiments, work vehicle 100 may be an unmanned work vehicle that performs autonomous driving. In that case, components that are only necessary for manned driving, such as a cabin, driver's seat, steering wheel, and operation terminal, may not be provided in work vehicle 100. An unmanned work vehicle may perform operations similar to those in the above embodiments by autonomous driving or by remote control by a user.

[0096] A control system that provides the various functions described in the above embodiments can also be retrofitted to a work vehicle that does not have those functions. Such a control system can be manufactured and sold independently of the work vehicle. A computer program used in such a control system can also be manufactured and sold independently of the work vehicle. The computer program can be provided, for example, by being stored on a computer-readable non-transitory storage medium. The computer program can also be provided by downloading via a telecommunications line (for example, the Internet).

[0097] As described above, the present disclosure includes the work vehicles, control systems, and control methods described in the following items.

[0098] [Item 1] A work vehicle capable of automatic steering operation in both forward and reverse, a positioning device that outputs time-series position data of the work vehicle; a control device that performs steering control of the work vehicle based on the time-series position data and a predetermined target route in an automatic steering mode; a changeover switch for switching between forward and reverse movement of the work vehicle; Equipped with When the movement speed of the work vehicle is lower than a first speed in the automatic steering mode, the control device determines the traveling direction of the work vehicle based on the time-series position data and the state of the change-over switch. Work vehicle.

[0099] [Item 2] 2. The work vehicle according to claim 1, wherein, in the automatic steering mode, when the movement speed is lower than the first speed and a switching operation between forward and reverse is performed using the selector switch, the control device transitions to a standby mode in which the automatic steering is temporarily canceled.

[0100] [Item 3] Within a predetermined first hour from the time of transition to the standby mode, First condition: the traveling direction estimated from the time-series position data matches the traveling direction indicated by the changeover switch. When a return condition including the following is satisfied, the automatic steering mode is returned from the standby mode. A work vehicle as described in item 2.

[0101] [Item 4] The return condition is: A second condition is that the moving speed of the work vehicle is equal to or greater than a second speed. Item 3. A work vehicle according to item 3, comprising:

[0102] [Item 5] 5. The work vehicle according to item 4, wherein the second speed is equal to or less than the first speed.

[0103] [Item 6] The control device If the return condition is not satisfied within the first hour from the time of transition to the standby mode, transition from the standby mode to a manual steering mode, In the manual steering mode, the manual steering mode is maintained until a user performs an operation to switch to the automatic steering mode. 6. A work vehicle according to any one of items 3 to 5.

[0104] [Item 7] 7. The work vehicle according to item 6, wherein the control device causes a display device to display a warning urging the driver to increase speed when the mode transitions from the standby mode to the manual steering mode.

[0105] [Item 8] The prime mover and A transmission; a clutch that switches between transmitting and not transmitting power from the prime mover to the transmission; Furthermore, The return condition further includes: Third condition: the clutch is engaged. 6. A work vehicle according to any one of items 3 to 5, comprising:

[0106] [Item 9] The changeover switch is an operating device for switching between forward, neutral, and reverse, In the automatic steering mode, the control device When the changeover switch is in a neutral state or the clutch is disengaged for a predetermined second time period or longer, the automatic steering mode is switched to the manual steering mode. A work vehicle as described in item 8.

[0107] [Item 10] In the automatic steering mode, the control device When the second time has not elapsed since the changeover switch was in the neutral state or the clutch was in the disengaged state, If the moving speed is equal to or greater than the first speed, continue the automatic steering mode; If the moving speed is less than the first speed, the automatic steering mode is switched to the standby mode. A work vehicle as described in item 9.

[0108] [Item 11] 6. The work vehicle according to any one of items 1 to 5, wherein the first speed is equal to or greater than 0.15 km / h and equal to or less than 0.25 km / h.

[0109] [Item 12] 6. The work vehicle described in any one of items 1 to 5, wherein in the automatic steering mode, when the movement speed is equal to or greater than the first speed and less than a third speed, the control device determines the direction of travel of the work vehicle based on the time-series position data regardless of the state of the selector switch.

[0110] [Item 13] 6. A work vehicle according to any one of items 1 to 5, wherein the positioning device includes a GNSS receiver.

[0111] [Item 14] 6. The work vehicle according to any one of items 1 to 5, wherein the control device causes a display device to display the result of the determination of the traveling direction of the work vehicle.

[0112] [Item 15] A control system for a work vehicle capable of automatic steering operation in both forward and reverse, The work vehicle is equipped with a positioning device that outputs time-series position data of the work vehicle, and a change-over switch for switching the work vehicle between forward and reverse travel, the control system includes a control device that, in an automatic steering mode, performs steering control of the work vehicle based on the time-series position data and a predetermined target route, When the movement speed of the work vehicle is lower than a first speed in the automatic steering mode, the control device determines the traveling direction of the work vehicle based on the time-series position data and the state of the change-over switch. Control system.

[0113] [Item 16] A control method for a work vehicle capable of performing automatic steering operation in both forward and reverse, The work vehicle is equipped with a positioning device that outputs time-series position data of the work vehicle, and a change-over switch for switching the work vehicle between forward and reverse travel, In an automatic steering mode, steering control of the work vehicle is performed based on the time-series position data and a predetermined target route. In the automatic steering mode, when the movement speed of the work vehicle is lower than a first speed, determining the traveling direction of the work vehicle based on the time-series position data and the state of the change-over switch; A control method comprising: [Industrial Applicability]

[0114] The techniques of the present disclosure may be applied to work vehicles used in agricultural applications, such as tractors, transplanters, or harvesters, etc. The techniques of the present disclosure may also be applied to work vehicles used in non-agricultural applications, such as construction vehicles or snowplows. [Explanation of symbols]

[0115] 50 GNSS satellite, 60 Reference station, 70 Working area, 80 Headland, 100 Work vehicle, 101 Vehicle body, 102 Prime mover, 103 Transmission, 104 Wheels, 105 Cabin, 106 Steering gear, 107 Driver's seat, 108 Coupling, 109 Pedals, 120 Positioning device, 121 GNSS receiver, 122 RTK receiver, 125 Inertial measurement unit (IMU), 126 Processor, 130 Obstacle sensor, 140 Drive unit, 150 Sensor group, 1 52...Steering wheel sensor, 154...Turning angle sensor, 156...T / M rotation sensor, 160...Control system, 170...Storage device, 180...Control device, 182, 183, 184, 185...ECU, 190...Communication interface, 200...Operation terminal, 210...Operation switch group, 212...Clutch pedal, 214...Forward / reverse switch, 216...Automatic steering switch, 220...Buzzer, 300...Work machine, 340...Drive device, 360...Control device, 390...Communication interface

Claims

1. A work vehicle capable of automatic steering operation in both forward and reverse, a positioning device that outputs time-series position data of the work vehicle; a control device that performs steering control of the work vehicle based on the time-series position data and a predetermined target route in an automatic steering mode; a changeover switch for switching between forward and reverse movement of the work vehicle; Equipped with In the automatic steering mode, the control device When the moving speed of the work vehicle is lower than a first speed, a traveling direction of the work vehicle is determined based on the time-series position data and the state of the change-over switch; When the changeover switch is operated to switch between forward and reverse while the traveling speed is lower than the first speed, the automatic steering is temporarily released and the vehicle transitions to a standby mode. Work vehicle.

2. Within a predetermined first hour from the time of transition to the standby mode, First condition: the traveling direction estimated from the time-series position data matches the traveling direction indicated by the changeover switch. When a return condition including the following is satisfied, the automatic steering mode is returned from the standby mode. The work vehicle according to claim 1 .

3. The return condition is: Second condition: the travel speed of the work vehicle is equal to or greater than a second speed. The work vehicle of claim 2 , comprising:

4. The work vehicle according to claim 3 , wherein the second speed is equal to or less than the first speed.

5. The control device If the return condition is not satisfied within the first hour from the time of transition to the standby mode, transition from the standby mode to a manual steering mode, In the manual steering mode, the manual steering mode is maintained until a user performs an operation to switch to the automatic steering mode. A work vehicle according to any one of claims 2 to 4.

6. The work vehicle according to claim 5, wherein the control device causes a display device to display a warning urging the driver to increase speed when the work vehicle transitions from the standby mode to the manual steering mode.

7. The prime mover and A transmission and a clutch that switches between transmitting and not transmitting power from the prime mover to the transmission; Furthermore, The return condition further includes: Third condition: the clutch is engaged. The work vehicle according to any one of claims 2 to 4, comprising:

8. The changeover switch is an operating device for switching between forward, neutral, and reverse, In the automatic steering mode, the control device The state in which the changeover switch is in neutral or the state in which the clutch is disengaged is a predetermined second If the above-mentioned automatic steering mode continues for more than 10 seconds, the automatic steering mode is switched to the manual steering mode. The work vehicle according to claim 7.

9. In the automatic steering mode, the control device When the second time has not elapsed since the changeover switch was in the neutral state or the clutch was in the disengaged state, If the moving speed is equal to or greater than the first speed, the automatic steering mode is continued; If the moving speed is less than the first speed, the automatic steering mode is switched to the standby mode. The work vehicle according to claim 8.

10. The work vehicle according to claim 1 , wherein the first speed is equal to or greater than 0.15 km / h and equal to or less than 0.25 km / h.

11. 5. The work vehicle according to claim 1, wherein, in the automatic steering mode, when the movement speed is equal to or greater than the first speed and less than a third speed, the control device determines the direction of travel of the work vehicle based on the time-series position data regardless of the state of the selector switch.

12. The work vehicle according to claim 1 , wherein the positioning device includes a GNSS receiver.

13. The work vehicle according to claim 1 , wherein the control device causes a display device to display a result of the determination of the traveling direction of the work vehicle.

14. A control system for a work vehicle capable of automatic steering operation in both forward and reverse, The work vehicle is equipped with a positioning device that outputs time-series position data of the work vehicle, and a change-over switch for switching the work vehicle between forward and reverse travel, the control system includes a control device that, in an automatic steering mode, performs steering control of the work vehicle based on the time-series position data and a predetermined target route, In the automatic steering mode, the control device When the moving speed of the work vehicle is lower than a first speed, a traveling direction of the work vehicle is determined based on the time-series position data and the state of the change-over switch; When the changeover switch is operated to switch between forward and reverse while the traveling speed is lower than the first speed, the automatic steering is temporarily released and the vehicle transitions to a standby mode. Control system.

15. A control method for a work vehicle capable of performing automatic steering operation in both forward and reverse, The work vehicle is equipped with a positioning device that outputs time-series position data of the work vehicle, and a change-over switch for switching the work vehicle between forward and reverse travel, In an automatic steering mode, steering control of the work vehicle is performed based on the time-series position data and a predetermined target route. In the automatic steering mode, when the movement speed of the work vehicle is lower than a first speed, determining the traveling direction of the work vehicle based on the time-series position data and the state of the change-over switch; In the automatic steering mode, when the changeover switch is operated to switch between forward and reverse while the traveling speed is lower than the first speed, transitioning to a standby mode in which the automatic steering is temporarily released; A control method comprising:

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