JP7504961B2 - Work vehicle control method - Google Patents

Description

The present invention primarily relates to a work vehicle control method capable of autonomously driving a work vehicle along a driving route.

Conventionally, work vehicles are known that can switch between a driving mode in which the work vehicle is driven manually and a driving mode in which the work vehicle is driven autonomously (automatically). Patent Document 1 discloses this type of work vehicle.

Patent document 1 states that the condition for switching from a driving mode in which the work vehicle is manually driven to a driving mode in which the work vehicle is autonomously driven is that the forward/reverse switching means must be in neutral.

JP 2014-182453 A

However, if the forward/reverse switching means needs to be in neutral when switching the driving mode, the work vehicle needs to be stopped every time the driving mode is switched. Therefore, it is not possible to smoothly transition from a driving mode in which the work vehicle is manually driven to a driving mode in which the work vehicle is autonomously driven.

The present invention has been made in consideration of the above circumstances, and its main objective is to provide a work vehicle control method that allows for smooth transition from a driving mode in which the work vehicle is driven manually to a driving mode in which the work vehicle is driven autonomously, and that can confirm whether the operator intends to drive the work vehicle autonomously.

A work vehicle control method according to one embodiment is a work vehicle control method capable of causing a work vehicle to travel autonomously, and includes a process of interrupting the autonomous travel of the work vehicle when a mode transition condition is satisfied during the autonomous travel of the work vehicle, the mode transition condition including a condition related to the operation of an operating tool provided on the work vehicle.

1 is a side view showing the overall configuration of a tractor equipped with a control device according to an embodiment of the present invention; FIG. FIG. 1 shows a wireless communication terminal. FIG. 2 is a block diagram showing the main configuration of a control system of a tractor and a wireless communication terminal. FIG. 4 is an explanatory diagram showing types of driving modes and driving mode transition conditions. 10 is a flowchart showing a process for identifying a work route on which autonomous traveling can be started. FIG. 13 is a diagram showing candidate work routes from which autonomous driving can begin. 11A and 11B are diagrams for explaining conditions for determining whether a work route is one in which autonomous traveling can be started.

Next, an embodiment of the present invention will be described with reference to the drawings. In the following, the same components in each of the drawings will be given the same reference numerals, and duplicated explanations may be omitted. In addition, the names of components, etc. corresponding to the same reference numerals may be rephrased in a simplified manner, or rephrased with the name of a higher or lower concept.

The autonomous driving system autonomously drives one or more work vehicles in a work area and a non-work area to perform all or part of the work. In this embodiment, a tractor is used as an example of a work vehicle, but in addition to tractors, work vehicles also include rice transplanters, combine harvesters, civil engineering and construction work equipment, snowplows, and other ride-on work machines, as well as walk-behind work machines. In this specification, autonomous driving means that the tractor's control unit (ECU) controls the tractor's configuration related to driving, and the tractor drives along a predetermined route, and autonomous operation means that the tractor's control unit controls the tractor's configuration related to work, and the tractor performs work along a predetermined route. Note that autonomous driving and autonomous operation include cases where a person is riding on the tractor and cases where a person is not riding on the tractor. In contrast, manual driving and manual operation mean that the tractor's configuration is operated by the user to drive and work.

Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a side view showing the overall configuration of a tractor 1 provided in an autonomous driving system 99 according to one embodiment of the present invention. FIG. 2 is a plan view of the tractor 1. FIG. 3 is a diagram showing a wireless communication terminal 46. FIG. 4 is a block diagram showing the main configuration of the control system of the tractor 1 and the wireless communication terminal 46.

As shown in FIG. 1, the tractor 1 provided in the autonomous driving system 99 is a work vehicle that is operated by wireless communication with a wireless communication terminal 46. A user can operate the wireless communication terminal 46 to appropriately exchange signals with a control unit (work vehicle control device) 4 of the tractor 1, thereby making the tractor 1 autonomously drive and work.

First, the tractor 1 equipped with the autonomous driving system 99 will be described with reference mainly to Figures 1 and 2.

The tractor 1 is equipped with a traveling body (vehicle body) 2 capable of autonomously traveling within a farm field (traveling area). A working machine 3 shown in Figs. 1 and 2 is removably attached to the traveling body 2. Examples of the working machine 3 include various working machines such as cultivators, plows, fertilizer applicators, grass cutters, and seed sowing machines. A desired working machine 3 can be selected from these as needed and attached to the traveling body 2. The traveling body 2 is configured to be able to change the height and posture of the attached working machine 3.

The configuration of the tractor 1 will be described in more detail with reference to Figures 1 and 2. As shown in Figure 1, the running body 2 of the tractor 1 is supported at its front by a pair of left and right front wheels 7, 7, and at its rear by a pair of left and right rear wheels 8, 8.

A bonnet 9 is disposed at the front of the traveling body 2. Inside this bonnet 9, an engine 10, which is the driving source of the tractor 1, and a fuel tank (not shown) are housed. This engine 10 can be configured, for example, as a diesel engine, but is not limited to this and may be configured, for example, as a gasoline engine. Also, an electric motor may be used as the driving source in addition to or instead of the engine.

A cabin 11 for the user to board is located behind the bonnet 9. Inside the cabin 11, the main components are a steering handle (steering operation tool) 12 for the user to operate the steering wheel, a seat 13 on which the user can sit, and various operation tools for performing various operations. However, the work vehicle such as the tractor 1 is not limited to one with a cabin 11, and may not have a cabin 11.

Examples of the above-mentioned operating tools include the monitor device 14, throttle lever 15, main shift lever 27, multiple hydraulic control levers 16, PTO switch 17, PTO shift lever 18, sub-shift lever 19, forward/reverse switch lever 25, parking brake 26, work equipment lift switch 28, brake pedal 61, clutch pedal 62, and accelerator pedal 63, all of which are shown in FIG. 2. These operating devices are located near the seat 13 or near the steering wheel 12.

The monitor device 14 is configured to be able to display various information about the tractor 1. The throttle lever 15 is an operating tool for setting the rotation speed of the engine 10. The main speed change lever 27 is an operating tool for steplessly changing the traveling speed of the tractor 1. The hydraulic operation lever 16 is an operating tool for switching the hydraulic external take-off valve (not shown). The PTO switch 17 is an operating tool for switching between transmitting and cutting off power to the PTO shaft (not shown) (power take-off shaft) protruding from the rear end of the transmission 22. That is, when the PTO switch 17 is in the ON state, power is transmitted to the PTO shaft, which rotates and drives the work machine 3, while when the PTO switch 17 is in the OFF state, power to the PTO shaft is cut off, the PTO shaft does not rotate, and the work machine 3 is stopped. The PTO shift lever 18 is used to change the power input to the working machine 3, and is specifically an operating tool for changing the rotation speed of the PTO shaft. The sub-shift lever 19 is an operating tool for changing the gear ratio of the traveling sub-shift gear mechanism in the transmission 22. The forward/reverse switching lever 25 is configured to be switchable between a forward position, a neutral position, and a reverse position. When the forward/reverse switching lever 25 is in the forward position, the power of the engine 10 is transmitted to the rear wheels 8, causing the tractor 1 to move forward. When the forward/reverse switching lever 25 is in the neutral position, the tractor 1 does not move forward or backward. When the forward/reverse switching lever 25 is in the reverse position, the power of the engine 10 is transmitted to the rear wheels 8, causing the tractor 1 to move backward. The parking brake (braking operating tool) 26 is an operating tool that is operated by the user's hand to generate a braking force, and is used, for example, when stopping the tractor 1 for a while. The work machine lift switch 28 is an operating tool for lifting and lowering the height of the work machine 3 attached to the traveling body 2 within a predetermined range. The brake pedal (braking operating tool) 61 is an operating tool that the user operates with his/her foot to generate a braking force. The clutch pedal 62 is an operating tool that the user operates with his/her foot to switch the clutch between transmission and non-transmission. The accelerator pedal 63 is an operating tool that increases the rotation speed of the engine 10. Note that an accelerator lever may be provided instead of or in addition to the accelerator pedal 63.

As shown in FIG. 1, the chassis 20 of the tractor 1 is provided under the traveling body 2. The chassis 20 is composed of a body frame 21, a transmission 22, a front axle 23, and a rear axle 24.

The machine frame 21 is a support member at the front of the tractor 1, and supports the engine 10 directly or via vibration-proof members or the like. The transmission 22 changes the power from the engine 10 and transmits it to the front axle 23 and the rear axle 24. The front axle 23 is configured to transmit the power input from the transmission 22 to the front wheels 7. The rear axle 24 is configured to transmit the power input from the transmission 22 to the rear wheels 8.

As shown in FIG. 4, the tractor 1 is equipped with a control unit 4 for controlling the operation of the traveling body 2 (forward, backward, stop, turning, etc.), the driving mode (manual driving mode and autonomous driving mode, etc.), and the operation of the work machine 3 (lifting, lowering, driving, stopping, etc.), and for performing processing related to the route. Therefore, the control unit 4 is configured to include a forward/reverse control unit 4a that controls forward and backward movement, a driving mode control unit 4b, and a route processing unit 4c. The control unit 4 is configured with a CPU, ROM, RAM, I/O, etc. (not shown), and the CPU can read and execute various programs, etc. from the ROM. The control unit 4 is electrically connected to a controller for controlling each component (e.g., engine 10, etc.) of the tractor 1, and a wireless communication unit 40 that can wirelessly communicate with other wireless communication devices, etc.

As the above controllers, the tractor 1 is equipped with at least an engine controller, a vehicle speed controller, a steering controller, and a lift controller (not shown). Each controller can control each component of the tractor 1 in response to an electrical signal from the control unit 4.

The engine controller controls the rotation speed and other parameters of the engine 10. Specifically, the engine 10 is provided with a governor device 41 equipped with an actuator (not shown) that changes the rotation speed of the engine 10. The engine controller can control the rotation speed of the engine 10 by controlling the governor device 41. The engine 10 is also provided with a fuel injection device 45 that adjusts the injection timing and injection amount of fuel to be injected (supplied) into the combustion chamber of the engine 10. By controlling the fuel injection device 45, the engine controller can, for example, stop the supply of fuel to the engine 10 and stop the operation of the engine 10.

The vehicle speed controller controls the vehicle speed of the tractor 1. Specifically, the transmission 22 is provided with a transmission 42, which is, for example, a hydraulic variable speed device of a movable swash plate type. The vehicle speed controller can change the gear ratio of the transmission 22 and achieve the desired vehicle speed by changing the angle of the swash plate of the transmission 42 using an actuator (not shown).

The steering controller controls the rotation angle of the steering handle 12. Specifically, a steering actuator 43 is provided midway on the rotation axis (steering shaft) of the steering handle 12. With this configuration, when the tractor 1 travels along a predetermined route, the control unit 4 calculates an appropriate rotation angle of the steering handle 12 so that the tractor 1 travels along that route, and outputs a control signal to the steering controller to achieve the obtained rotation angle. The steering controller drives the steering actuator 43 based on the control signal input from the control unit 4, and controls the rotation angle of the steering handle 12.

The lift controller controls the lifting and lowering of the working implement 3. Specifically, the tractor 1 is provided with a lift actuator 44 consisting of a hydraulic cylinder or the like, near the three-point link mechanism that connects the working implement 3 to the traveling body 2. With this configuration, the lift controller drives the lift actuator 44 based on a control signal input from the control unit 4 to appropriately raise and lower the working implement 3, allowing the working implement 3 to perform agricultural work at a desired height. With this control, the working implement 3 can be supported at a desired height, such as a retraction height (a height at which agricultural work is not performed) and a working height (a height at which agricultural work is performed).

In addition, since the multiple controllers not shown in the figure control each part such as the engine 10 based on signals input from the control unit 4, it can be understood that the control unit 4 essentially controls each part.

The tractor 1 equipped with the control unit 4 as described above is configured so that a user can ride in the cabin 11 and perform various operations to control each part of the tractor 1 (the traveling body 2, the work implement 3, etc.) using the control unit 4, thereby performing agricultural work while traveling in a field. In addition, when a user is on board the tractor 1, the tractor 1 is capable of autonomous traveling and autonomous work based on a predetermined control signal output by the wireless communication terminal 46. The tractor 1 has the function of autonomous traveling even when a user is not on board the tractor 1.

Specifically, as shown in FIG. 4 etc., the tractor 1 is equipped with various configurations that enable it to travel and work autonomously. For example, the tractor 1 is equipped with a positioning antenna 6 etc. that is necessary for acquiring position information of the tractor 1 itself (the traveling body 2) based on a positioning system. With this configuration, the tractor 1 is able to acquire its own position information based on the positioning system and travel autonomously on a farm field.

Next, the configuration of the tractor 1 to enable autonomous driving will be described in more detail. Specifically, as shown in FIG. 4 etc., the tractor 1 of this embodiment is equipped with a positioning antenna 6, a wireless communication antenna 48, a front camera 56, a rear camera 57, a memory unit 55, a vehicle speed sensor 53, a steering angle sensor 52, etc. In addition to these, the tractor 1 is equipped with an inertial measurement unit (IMU) that can identify the attitude (roll angle, pitch angle, yaw angle) of the traveling body 2.

The positioning antenna 6 receives signals from positioning satellites that constitute a positioning system such as a global navigation satellite system (GNSS). As shown in FIG. 1, the positioning antenna 6 is attached to the upper surface of the roof 92 of the cabin 11 of the tractor 1. The positioning signal received by the positioning antenna 6 is input to a position information acquisition unit 49 serving as a position detection unit shown in FIG. 4. The position information acquisition unit 49 calculates and acquires the position information of the running body 2 of the tractor 1 (specifically, the positioning antenna 6) as, for example, latitude and longitude information. The position information acquired by the position information acquisition unit 49 is input to the control unit 4 and used for autonomous driving.

In this embodiment, a highly accurate satellite positioning system using the GNSS-RTK method is used, but this is not limited to this, and other positioning systems may be used as long as they can obtain highly accurate position coordinates. For example, it is possible to use a differential GPS (Digital GPS System) or a satellite-based augmentation system (SBAS).

The wireless communication antenna 48 receives signals from the wireless communication terminal 46 operated by the user and transmits signals to the wireless communication terminal 46. As shown in FIG. 1, the wireless communication antenna 48 is attached to the upper surface of the roof 92 of the cabin 11 of the tractor 1. The signal received by the wireless communication antenna 48 from the wireless communication terminal 46 is processed by the wireless communication unit 40 shown in FIG. 4 and then input to the control unit 4. In addition, the signal to be transmitted from the control unit 4 to the wireless communication terminal 46 is processed by the wireless communication unit 40, then transmitted from the wireless communication antenna 48 and received by the wireless communication terminal 46.

The front camera 56 takes pictures of the area in front of the tractor 1. The rear camera 57 takes pictures of the area behind the tractor 1. The front camera 56 and the rear camera 57 are attached to the roof 92 of the tractor 1. Video data taken by the front camera 56 and the rear camera 57 is transmitted by the wireless communication unit 40 from the wireless communication antenna 48 to the wireless communication terminal 46. The wireless communication terminal 46, which receives the video data, displays the contents on the display 37.

The vehicle speed sensor 53 detects the vehicle speed of the tractor 1, and is provided, for example, on the axle between the front wheels 7, 7. The detection result data obtained by the vehicle speed sensor 53 is output to the control unit 4. The vehicle speed of the tractor 1 may be calculated based on the travel time of the tractor 1 over a predetermined distance based on the positioning antenna 6, without being detected by the vehicle speed sensor 53. The steering angle sensor 52 is a sensor that detects the steering angle of the front wheels 7, 7. In this embodiment, the steering angle sensor 52 is provided on a kingpin (not shown) provided on the front wheels 7, 7. The detection result data obtained by the steering angle sensor 52 is output to the control unit 4. The steering angle sensor 52 may be provided on the steering handle 12.

The storage unit 55 is a memory that stores the driving route for the tractor 1 to drive autonomously and the work route for the tractor 1 to work autonomously, and stores the progress of the position (driving trajectory) of the tractor 1 (strictly speaking, the positioning antenna 6) during autonomous driving. In addition, the storage unit 55 stores various information necessary for the tractor 1 to drive and work autonomously.

As shown in FIG. 3, the wireless communication terminal 46 is configured as a tablet-type personal computer equipped with a touch panel 39. The user can refer to and confirm information displayed on the display 37 of the wireless communication terminal 46 (e.g., information from the front camera 56, the rear camera 57, the vehicle speed sensor 53, etc.). The user can also operate the above-mentioned touch panel 39 or a hardware key 38 arranged near the display 37 to send a control signal (e.g., a pause signal, etc.) for controlling the tractor 1 to the control unit 4 of the tractor 1. Note that the wireless communication terminal 46 is not limited to a tablet-type personal computer, and instead, for example, it can be configured as a notebook-type personal computer. In addition, when the tractor 1 is made to perform autonomous driving and autonomous work with a user on board the tractor 1, the tractor 1 side (e.g., the monitor device 14) may have the same function as the wireless communication terminal 46.

The tractor 1 configured in this manner can perform agricultural work using the work implement 3 along the work path P1 while traveling along the travel path P in the field based on instructions from a user using the wireless communication terminal 46.

Specifically, the user can use the wireless communication terminal 46 to perform various settings to generate a travel path (path) P as a series of routes that alternate between a straight or broken line work path P1 along which agricultural work is performed and a circular arc-shaped turning path (non-work path along which the tractor 1 turns) P2 connecting the ends of the work path P1 (see FIG. 7). Then, by inputting (transferring) information on the travel path (work path P1 and non-work path P2) P thus generated to a memory unit 55 electrically connected to the control unit 4 of the tractor 1 and performing a predetermined operation, the control unit 4 can control the tractor 1 to autonomously travel along the travel path P while autonomously operating the work implement 3 along the work path P1.

The configuration of the wireless communication terminal 46 is described in more detail below with reference to Figures 3 to 5.

As shown in Figures 3 and 4, the wireless communication terminal 46 of this embodiment includes a display 37, hardware keys 38, and a touch panel 39, as well as a display control unit 31, a memory unit 32, a field acquisition unit 33, a work area acquisition unit 34, and a travel route acquisition unit 35, etc., as main components of the control system.

Specifically, the wireless communication terminal 46 is configured as a computer as described above, and includes a CPU, ROM, RAM, etc. The ROM also stores appropriate programs for causing the tractor 1 to travel and work autonomously. Through cooperation between this software and hardware, the wireless communication terminal 46 can operate as the display control unit 31, memory unit 32, field acquisition unit 33, work area acquisition unit 34, travel route acquisition unit 35, etc.

The display control unit 31 creates display data to be displayed on the display 37 and controls the display content as appropriate. For example, while the tractor 1 is autonomously traveling along the travel path P and working along the work path P1, the display control unit 31 causes a predetermined monitoring screen, instruction screen, etc. to be displayed on the display 37.

The storage unit 32 is a memory that stores information about the tractor 1 and information about the field input by the user by operating the touch panel 39 of the wireless communication terminal 46, as well as information about the created travel path P (work path P1 and non-work path P2).

The field acquisition unit 33 stores the position and shape of the field (travel area) in which the tractor 1 will travel and work autonomously. The position and shape of the field can be acquired, for example, by a user getting on the tractor 1 and driving it around the perimeter of the field, and recording the progress of the position information of the positioning antenna 6 at that time. The position and shape of the field acquired by the field acquisition unit 33 are stored in the memory unit 32 as field information.

The work area acquisition unit 34 sets the position of the work area in which agricultural work is performed, which is to be placed within the field in which the tractor 1 will travel autonomously. Specifically, the wireless communication terminal 46 of this embodiment is configured to be able to set the width of the headland and the width of the non-cultivated land by performing a specified operation. The non-work area consisting of the headland and non-cultivated land is then determined based on the above settings and the position and shape of the field acquired by the field acquisition unit 33, and the area of the field excluding the non-work area is determined as the work area.

The travel path acquisition unit 35 generates and acquires a travel path P that alternates between a work path P1 along which the tractor 1 autonomously performs agricultural work in the field and a non-work path (turning path) P2 that connects the ends of the work path P1. When the user inputs information necessary for generating the travel path P via the touch panel 39 or the like, the travel path acquisition unit 35 automatically creates the travel path P (work path P1 and non-work path P2) based on that information. This travel path P is generated so that the straight or broken line work path P1 is included in the work area and the non-work path (turning path) P2 is included in a non-work area such as a headland. The travel path P generated by the travel path acquisition unit 35 is stored in the memory unit 32.

The user appropriately operates the wireless communication terminal 46 to input (transfer) information about the travel route P generated by the travel route acquisition unit 35 to the memory unit 55 of the tractor 1. The user then gets on and drives the tractor 1, placing the tractor 1 at the start position of the travel route P. The user then dismounts from the tractor 1 and operates the wireless communication terminal 46 to instruct the start of autonomous travel and autonomous work. As a result, the control unit 4 controls the travel and agricultural work of the tractor 1 so that the tractor 1 travels along the travel route P while performing agricultural work along the work route P1.

Next, the process of switching the driving mode of the tractor 1 will be described with reference to Figs. 5 to 8. Fig. 5 is an explanatory diagram showing types of driving modes and conditions for transitioning between driving modes. Fig. 6 is a flowchart showing the process of identifying a work route on which autonomous driving can be started. Fig. 7 is a diagram showing candidates for work routes on which autonomous driving is possible. Fig. 8 is a diagram explaining the conditions for determining whether a work route is capable of autonomous driving or not.

The user can switch the tractor 1 from manual driving mode to automatic driving mode, or from automatic driving mode to manual driving mode, by operating the touch panel 39 of the wireless communication terminal 46. Note that the manual driving mode and automatic driving mode of the tractor 1 may be switched by operating the monitor device 14 of the tractor 1 or a dedicated operating tool, rather than the wireless communication terminal 46. However, when the user instructs switching between the manual driving mode and the automatic driving mode, the switching is not performed unconditionally, but is performed after other conditions are met.

Specifically, as shown in FIG. 5, the tractor 1 of this embodiment is set to a manual driving mode, an autonomous driving preparation mode, a first autonomous driving mode, a second autonomous driving mode, and a manual driving preparation mode. Of these five driving modes, in the manual driving mode and the autonomous driving preparation mode, the tractor 1 performs manual driving. In the first autonomous driving mode and the second autonomous driving mode, the tractor 1 performs autonomous driving. In the manual driving preparation mode, the tractor 1 is stopped without performing manual driving or autonomous driving. Therefore, the manual driving mode and the autonomous driving preparation mode may be collectively referred to as the manual driving mode. In addition, the first autonomous driving mode and the second autonomous driving mode may be collectively referred to as the automatic driving mode.

Note that the method of classifying the driving modes is an example, and any of the driving modes shown in FIG. 5 may be omitted. Driving modes other than the five shown in FIG. 5 may also be included. For example, in order to transition from the autonomous driving preparation mode to the first autonomous driving execution mode, multiple conditions must be satisfied, and a state in which some of these conditions are satisfied may be treated as a different driving mode.

The manual driving execution mode is a driving mode for making the tractor 1 drive manually. The autonomous driving preparation mode is a driving mode that is used before switching from the manual driving execution mode to the autonomous driving mode. In the autonomous driving preparation mode, the tractor 1 drives manually, since it is before switching to autonomous driving.

The first autonomous driving execution mode and the second autonomous driving execution mode are driving modes for making the tractor 1 perform autonomous driving. When transitioning from the autonomous driving preparation mode, the first autonomous driving execution mode is the first. In the first autonomous driving execution mode, if a predetermined process (details will be described later) is not performed within a certain period of time, the tractor 1 transitions to the manual driving execution mode via the manual driving preparation mode, etc. In other words, the first autonomous driving execution mode can be said to be a time-limited (temporary) autonomous driving mode. In contrast, in the second autonomous driving execution mode, the driving mode is maintained unless an instruction to transition to the manual driving execution mode or an operation that clearly indicates a desire for manual driving is performed. Therefore, the second autonomous driving execution mode can be said to be the official (original) autonomous driving mode. The manual driving preparation mode is a driving mode that may be passed through when transitioning from the autonomous driving mode to the manual driving execution mode. In the manual driving preparation mode, as described above, the tractor 1 is stopped without performing manual driving or autonomous driving.

Next, the transition conditions for each driving mode will be described in detail. Control of each driving mode is performed by the driving mode control unit 4b of the control unit 4.

First, the first mode transition condition, which is the condition for transitioning from the manual driving execution mode to the autonomous driving preparation mode, will be described. As shown in FIG. 3, the first mode transition condition has multiple condition items set, but these are AND conditions, and transition to the autonomous driving preparation mode occurs when all of the multiple condition items are satisfied. Specific condition items set are (a) the engine rotation speed being equal to or higher than a predetermined value (e.g., equal to or higher than idling speed), and (b) no abnormality is occurring in the equipment (sensors, actuators, etc.).

Regarding condition (a), the control unit 4 acquires the engine rotation speed based on the detection results of sensors attached to the engine 10 that output pulses in response to the rotation of the crankshaft, and determines whether the engine rotation speed is equal to or higher than a predetermined value. Also, regarding condition (b), the control unit 4 determines whether there is an abnormality in the equipment based on the detection results of various sensors attached to the tractor 1. Note that, although the control unit 4 may determine whether there is an abnormality in all the equipment, it may also determine whether there is an abnormality only in the equipment required for autonomous driving (such as the position information acquisition unit 49 and the steering angle sensor 52).

Next, we will explain the second mode transition condition, which is the condition for transitioning from the autonomous driving preparation mode to the manual driving execution mode. As shown in Figure 3, if the above first mode transition condition is not met, the driving mode transitions to the manual driving execution mode. In other words, after the first mode transition condition is met and transitions to the autonomous driving preparation mode, if the first mode transition condition is subsequently no longer met, the driving mode returns to the manual driving execution mode. Note that the second mode transition condition is given priority over the third mode transition condition. In other words, if both the second mode transition condition and the third mode transition condition are met, the second mode transition condition becomes valid and transitions to the manual driving execution mode.

Next, the third mode transition condition, which is a condition for transitioning from the autonomous driving preparation mode to the first autonomous driving execution mode, will be described. As shown in FIG. 3, the third mode transition condition has multiple condition items set, which are AND conditions, and transition to the first autonomous driving execution mode occurs when all of the multiple condition items are met. Specific condition items are set as follows: (a) the forward/reverse switching lever 25 is in the forward position or neutral position; (b) none of the brake pedal 61, clutch pedal 62, and parking brake 26 are operated; (c) the shift position is on the lower side than a predetermined speed; (d) the steering angle is within a predetermined angle; (e) a route on which autonomous driving is possible has been identified; and (f) an instruction to start autonomous driving has been issued.

Regarding conditions (a) to (c), the control unit 4 acquires and determines the operation state of each operating tool (forward/reverse switching lever 25, brake pedal 61, clutch pedal 62, parking brake 26, main shift lever 27, and sub-shift lever 19) based on sensors provided on each operating tool or electrical signals output by each operating tool. Here, in the past, the autonomous driving mode could only be switched to when the forward/reverse switching lever 25 was in the neutral position, so the tractor 1 could not be switched from the manual driving mode to the automatic driving mode unless it was stopped. In contrast, in this embodiment, the transition condition to the autonomous driving mode (first autonomous driving implementation mode) is satisfied not only when the forward/reverse switching lever 25 is in the neutral position but also when it is in the forward position (in other words, the transition condition to the autonomous driving mode is not satisfied when the forward/reverse switching lever 25 is in the reverse position). Therefore, the tractor 1 can be switched from the manual driving mode to the autonomous driving mode without stopping. In this case, the tractor 1 may move without the user's intention if it subsequently moves to manual driving mode because the autonomous driving mode is switched to with the forward/reverse switching lever 25 in the forward position. Therefore, in the tractor 1 of this embodiment, various processes are performed to prevent the tractor 1 from moving without the user's intention.

Regarding condition (d), the control unit 4 obtains the steering angle based on the detection result of the steering angle sensor 52 and determines whether it is within a predetermined angle.

Regarding condition (e), the control unit 4 performs the process shown in FIG. 6 to determine whether or not there is a work route that can be driven autonomously. First, the control unit 4 (route processing unit 4c) communicates with the wireless communication terminal 46 to acquire multiple (e.g., five) work routes P1 that are close to the current position of the tractor 1 (S101). In FIG. 7, the work routes P1 acquired in this process are shown in bold lines. Note that, in order to appropriately switch between the manual driving mode and the autonomous driving mode, only the work routes P1 (straight-line routes) are acquired (as candidates for routes that can be driven autonomously), not the non-work routes P2 (turning routes).

Next, the control unit 4 extracts the work path P1 that satisfies all of the following conditions from the acquired work path P1 (S102). Condition (1) is that the distance between the work path P1 and the tractor 1 (distance L1 in FIG. 8) is within a predetermined range. In the example shown in FIG. 8, the position of the positioning antenna 6 of the tractor 1 is used as the reference, but another position (for example, the center position of the front end of the tractor 1 or the center position of the rear end of the work implement 3) may be used as the reference. Condition (2) is that the difference between the direction of the work path P1 and the direction of the tractor 1 (angle θ in FIG. 8) is within a predetermined range. Since both the work path P1 and the tractor 1 have directions, the angle θ is calculated taking their directions into consideration. Condition (3) is that when the tractor 1 is in the work area, the distance to the non-work area (headland) (distance L2 shown in FIG. 8) is within a predetermined range. Condition (4) is that when the tractor 1 is in the non-work area, the distance to the work area (distance L3 shown in FIG. 8) is within a predetermined range. The threshold (predetermined value) for each condition is arbitrary, but it is preferable that the threshold for condition (1) < the threshold for condition (4) < the threshold for condition (3). For example, the threshold for condition (1) is 10 cm, the threshold for condition (2) is 10°, the threshold for condition (3) is 10 m, and the threshold for condition (4) is 10 m. Note that each threshold may be ±50% of these values. The fifth condition is that conditions (1) to (4) are continuously satisfied for a predetermined period of time.

The control unit 4 performs a judgment of conditions (1) to (5) for all work paths P1 acquired in step S101. Note that conditions (3) and (4) are conditions unrelated to the work path P1, and therefore do not have to be performed for all work paths P1 (a judgment is required only once for a specific work path P1). Next, the control unit 4 judges whether a work path P1 that satisfies the above conditions has been extracted (S103). If a work path P1 that satisfies the above conditions has not been extracted, the control unit 4 stores a message that no P1 capable of autonomous driving exists (S104). In this case, the third mode transition condition is no longer satisfied, and therefore the system does not transition to the first autonomous driving implementation mode.

On the other hand, when a work path P1 that satisfies the above conditions is extracted, the control unit 4 determines whether multiple work paths P1 have been extracted (S105). When multiple work paths P1 have not been extracted (i.e., when only one is extracted), the control unit 4 stores the extracted work path P1 as a path capable of autonomous travel (S106). When multiple work paths P1 have been extracted, the control unit 4 stores the work path P1 that is closest to the start position of the travel path P among the multiple work paths P1 as a path capable of autonomous travel (S107). Note that instead of the work path P1 closest to the start position, the work path P1 may be selected based on the smallness of at least one of the distance L1 to the tractor 1 and the angle θ of the difference in direction from the tractor 1, for example.

Regarding condition (f) of the third mode transition condition, the control unit 4 determines whether or not a command to switch to autonomous driving has been issued based on an operation performed by the user on the touch panel 39 of the wireless communication terminal 46 or the monitor device 14.

In order to transition from manual driving mode to autonomous driving mode, the first mode transition condition and the third mode transition condition must be satisfied, and the combination of these corresponds to the autonomous driving start condition.

Next, the fourth mode transition condition, which is a condition for transitioning from the first autonomous driving implementation mode to the second autonomous driving implementation mode, will be described. Specific condition items are set as follows: (a) the forward/reverse switch lever 25 is in the neutral position. In other words, in this embodiment, since transition to the autonomous driving mode is possible even if the forward/reverse switch lever 25 is in the forward position, the autonomous driving mode is transitioned to the second autonomous driving implementation mode, which is the official autonomous driving mode, after transitioning to the autonomous driving mode, and the forward/reverse switch lever 25 is changed to the neutral position. This makes it possible to switch to autonomous driving without stopping the tractor 1, and prevents switching to manual driving when the forward/reverse switch lever 25 is in the forward position. Note that when transitioning from the autonomous driving preparation mode to the first autonomous driving implementation mode, if the forward/reverse switch lever 25 is in the neutral position, the first autonomous driving implementation mode is immediately transitioned to the second autonomous driving implementation mode. In addition, in the first autonomous driving mode and the second autonomous driving mode, the driving of the tractor 1 is controlled regardless of the position of the forward/reverse switch lever 25, and even if the fourth mode transition condition is met, i.e., even if the forward/reverse switch lever 25 is in the neutral position, the tractor 1 does not stop and continues autonomous driving along a predetermined route.

Next, the fifth mode transition condition, which is the condition for transitioning from the first autonomous driving implementation mode to the manual driving implementation mode, will be described. Specific condition items are set as follows: (a) the forward/reverse switch lever 25 must be in the reverse position. When transitioning to the first autonomous driving implementation mode, the forward/reverse switch lever 25 is in the forward or neutral position, so condition (a) is not met unless the user operates the forward/reverse switch lever 25. Therefore, when condition (a) is met, the user's intention to return to manual driving is clear, so the mode is transitioned to the manual driving implementation mode (the autonomous driving mode is ended).

Next, the sixth mode transition condition, which is a condition for transitioning from the first autonomous driving implementation mode to the manual driving preparation mode, will be described. As shown in FIG. 3, the sixth mode transition condition has multiple condition items set, which are OR conditions, and transition to the manual driving preparation mode occurs when at least one of the condition items is satisfied. Specific condition items are set as follows: (a) the first mode transition condition is not satisfied; (b) any of the brake pedal 61, clutch pedal 62, parking brake 26, and steering wheel 12 is operated; (c) the forward/reverse switch lever 25 is in the forward position for a predetermined time; (d) the distance to the route and the difference in direction from the route are greater than or equal to a predetermined value; and (e) there is an instruction to start manual driving. Note that the sixth mode transition condition is given priority over the fourth and fifth mode transition conditions. In other words, even if the fourth or fifth mode transition condition is satisfied, if the sixth mode transition condition is satisfied, transition to the manual driving preparation mode occurs.

The method of determining conditions (a) to (c) is the same as above, so the explanation will be omitted. Condition (c) is a condition item for preventing the autonomous driving mode from continuing with the forward/reverse switching lever 25 in the forward position. The specified time for condition (c) is, for example, 5 seconds, but may be any value between 3 and 30 seconds. In addition, in the fifth mode transition condition, if the forward/reverse switching lever 25 is operated, the user's intention to return to manual driving is clear, so the manual driving mode is transitioned to. However, if other operating tools (brake pedal 61, clutch pedal 62, parking brake 26, steering wheel 12) are simply operated, the user's intention to return to manual driving is not clear. Therefore, the manual driving preparation mode is transitioned to.

In condition (d), the distance from the path is the distance between the work path P1 and the tractor 1. Also, the difference in direction from the path is the angle between the work path P1 and the tractor 1. When these values exceed predetermined values, condition (d) is met.

In condition (e), the control unit 4 determines whether or not a command to switch to manual driving has been issued based on an operation performed by the user on the touch panel 39 of the wireless communication terminal 46 or the monitor device 14.

Next, the seventh mode transition condition, which is the condition for transitioning from the first autonomous driving implementation mode to the manual driving implementation mode, will be described. Specific condition items are set as follows: (a) the forward/reverse switch lever 25 must be in the forward or reverse position. When transitioning to the second autonomous driving implementation mode, the forward/reverse switch lever 25 is in the neutral position, so condition (a) is not met unless the user operates the forward/reverse switch lever 25. Therefore, when condition (a) is met, the user's intention to return to manual driving is clear, so a transition to the manual driving implementation mode is made.

Next, the conditions for transitioning from the second autonomous driving implementation mode to the manual driving preparation mode will be described. These conditions are the same as the conditions for transitioning from the first autonomous driving implementation mode to the manual driving preparation mode. Note that in the second autonomous driving implementation mode, the mode transitions to the manual driving implementation mode when the forward/reverse switch lever 25 is placed in the forward position, so condition (c) of the sixth mode transition condition is never satisfied. Also, as in the first autonomous driving implementation mode, the sixth mode transition condition is given priority over the seventh mode transition condition.

Next, the eighth mode transition condition, which is a condition for transitioning from the manual driving preparation mode to the manual driving execution mode, will be described. As shown in FIG. 3, the eighth mode transition condition has multiple condition items set, which are AND conditions, and transition to the manual driving execution mode occurs when all of the multiple condition items are met. Specific condition items are set as follows: (a) the forward/reverse switching lever 25 is in the neutral position, and (b) the vehicle speed is equal to or lower than a predetermined value. By setting condition (a), it is possible to prevent switching to manual driving when the forward/reverse switching lever 25 is in the forward position. In addition, the control unit 4 determines condition (b) based on the detection result of the vehicle speed sensor 53.

In this way, after transitioning to the manual driving preparation mode, it is not possible to transition directly to the first autonomous driving execution mode or the second autonomous driving execution mode. Therefore, if the sixth mode transition condition is satisfied in the first autonomous driving execution mode or the second autonomous driving execution mode, the autonomous driving mode ends and then transitions to the manual driving mode.

In this embodiment, since manual driving can be switched to autonomous driving with the forward/reverse switching lever 25 in the forward position, switching to autonomous driving can be performed without stopping the tractor 1. In addition, in order to prevent switching to manual driving with the forward/reverse switching lever 25 in the forward position, the fourth mode transition condition (a), the eighth mode transition condition (a), and the like are provided. This makes it possible to prevent the tractor 1 from traveling against the user's intentions even when switching to manual driving.

As described above, the control unit 4 of the tractor 1 of this embodiment includes a forward/reverse control unit 4a and a driving mode control unit 4b. The forward/reverse control unit 4a controls the forward/reverse movement of the tractor 1. The driving mode control unit 4b executes one of a plurality of driving modes including at least a manual driving mode in which the tractor 1 moves forward/reverse in response to the operation of an operating tool (e.g., the brake pedal 61, the accelerator pedal 63, the sub-shift lever 19, the main shift lever 27, etc.) equipped on the tractor 1, and an autonomous driving mode in which the tractor 1 moves forward/reverse without the operation of the operating tool. The driving mode control unit 4b executes the autonomous driving mode by satisfying the autonomous driving start condition (the first mode transition condition and the third mode transition condition). The forward/reverse switching lever 25 equipped on the tractor 1 can be switched at least between a forward position, a neutral position, and a reverse position. When the forward/reverse switching lever 25 is in the forward position, the autonomous driving start condition can be satisfied.

As a result, the conditions for starting autonomous driving are met even when the forward/reverse switch lever 25 is in the forward position, so that the tractor 1 can transition from manual driving to autonomous driving without stopping. This allows for a smooth transition from manual driving to autonomous driving.

In addition, in the control unit 4 of the tractor 1 of this embodiment, when the autonomous driving mode is executed with the forward/reverse switching lever 25 in the forward position, if the forward/reverse switching lever 25 is not changed to the neutral position before a predetermined time has elapsed after the autonomous driving mode is executed, the driving mode control unit 4b ends the autonomous driving mode (transitions to the manual driving execution mode via the manual driving preparation mode).

This prevents the autonomous driving mode from continuing when the forward/reverse switch lever 25 is in the forward position, so that when returning to manual driving, the tractor 1 can be prevented from moving regardless of the operator's intentions.

In addition, in the control unit 4 of the tractor 1 of this embodiment, if the forward/reverse switch lever 25 is changed to the neutral position before a predetermined time has elapsed, the manual driving mode is executed when the forward/reverse switch lever 25 is changed from the neutral position to a position other than the neutral position. If the forward/reverse switch lever 25 is not changed to the neutral position before the predetermined time has elapsed, the control unit 4 executes the manual driving mode after the forward/reverse switch lever 25 is changed to the neutral position (transitioning to the manual driving preparation mode, in which the manual driving preparation mode is executed).

As a result, if the forward/reverse switch lever 25 is changed from the neutral position to another position, the intention to change to manual driving is clear and it is possible to switch to manual driving. On the other hand, if the forward/reverse switch lever 25 is not changed to the neutral position within a specified time, there is a possibility that the tractor 1 will move regardless of the operator's intentions if the driver changes to manual driving, so the forward/reverse switch lever 25 is changed to the neutral position and then the manual driving mode is switched to.

In addition, in the control unit 4 of the tractor 1 of this embodiment, if at least one of the steering wheel 12, the brake pedal 61, and the parking brake 26 of the tractor 1 is operated after a predetermined time has elapsed, the driving mode control unit 4b (transitions to a manual driving preparation mode, and in this manual driving preparation mode) executes the manual driving mode after the forward/reverse switch lever 25 is changed to the neutral position.

As a result, while the operation of the forward/reverse switch lever 25 clearly indicates the intention to switch to manual driving, the operation of the steering wheel 12, the brake pedal 61, and the parking brake 26 does not clearly indicate the intention to switch to manual driving, so the forward/reverse switch lever 25 is changed to the neutral position and then the manual driving mode is entered, thereby realizing a mode switch that takes into account the operator's intention.

The control unit 4 of the tractor 1 in this embodiment can acquire position information of the tractor 1 from a position information acquisition unit 49 that acquires position information of the tractor 1. The tractor 1 is equipped with a route processing unit 4c that performs processing to generate or acquire a driving route including multiple work routes and multiple non-work routes. The autonomous driving start condition includes that a work route on which the tractor 1 can drive autonomously has been identified based on the current position information and driving route of the tractor 1.

This allows the system to switch to autonomous driving mode only when a route is available for autonomous driving, resulting in streamlined processing.

The above describes a preferred embodiment of the present invention, but the above configuration can be modified, for example, as follows:

The condition items of the various conditions described in the above embodiment are merely examples, and at least one condition item may be added, deleted, or changed. For example, in this embodiment, it is assumed that manual driving is switched to autonomous driving while the user is on board the tractor 1, so that the condition item of the first mode transition condition may include the fact that the user is on board the tractor 1. Note that the fact that the user is on board the tractor 1 can be detected, for example, by a load sensor provided on the seat 13.

In the above embodiment, the sixth mode transition condition includes not satisfying the first mode transition condition, and the transition condition from the manual driving execution mode to the autonomous driving preparation mode and the transition condition from the first or second autonomous driving execution mode to the manual driving preparation mode are partially common conditions, but the two may be different conditions. That is, the transition condition from the manual driving execution mode to the autonomous driving preparation mode may be a condition that permits autonomous driving (autonomous driving permission condition), while the transition condition from the first or second autonomous driving execution mode to the manual driving preparation mode may be a condition that prohibits autonomous driving (autonomous driving prohibition condition). In that case, for example, if the tractor 1 is equipped with a load sensor as described above, the autonomous driving permission condition may include the load sensor being ON, while the autonomous driving prohibition condition may not include the load sensor being ON. This is because the load sensor may be temporarily turned OFF when the user's body is lifted due to vibration of the tractor 1, etc. However, if the load sensor remains OFF for a predetermined period of time (e.g., 5 seconds), it may be determined that the user has dismounted from the tractor 1 and the tractor may transition to a manual driving preparation mode.

In addition, in the above embodiment, when the first autonomous driving implementation mode is entered with the forward/reverse switching lever 25 in the forward position, if the forward/reverse switching lever 25 is changed to the neutral position after a predetermined time has elapsed, the mode is entered into the manual driving mode via the manual driving preparation mode. Alternatively, the autonomous driving mode may be maintained when the forward/reverse switching lever 25 is changed to the neutral position after a predetermined time has elapsed. In addition, in the first autonomous driving implementation mode or the second autonomous driving implementation mode, if any abnormality (for example, detection of the user not being on board) occurs, and the abnormality is quickly resolved, the mode may be returned to the first autonomous driving implementation mode or the second autonomous driving implementation mode.

In the above embodiment, when the first autonomous driving execution mode or the second autonomous driving execution mode is switched to the manual driving preparation mode, the eighth mode transition condition is satisfied to switch to the manual driving execution mode. However, under certain conditions, the manual driving preparation mode may be switched to the second autonomous driving execution mode when the ninth mode transition condition is satisfied in the manual driving preparation mode. Here, the specific condition is that the second autonomous driving execution mode is switched to the manual driving preparation mode when the above condition (c) among the sixth mode transition conditions (the brake pedal 61, the clutch pedal 62, the parking brake 26, or the steering wheel 12 is operated) is satisfied. In addition, the ninth mode transition condition is that the forward/reverse switching lever 25 is in the neutral position and an instruction to resume autonomous driving is issued based on the operation of the touch panel 39 of the wireless communication terminal 46.

In the above embodiment, the forward/reverse switching lever 25 in the shape of a lever has been described as an example of the forward/reverse switching operation tool, but a forward/reverse switching operation tool in a different shape (such as a slide switch shape) can also be used. The forward/reverse switching lever 25 can be switched to three positions, forward position, reverse position, and neutral position, but may be switched to other positions. The forward/reverse switching lever 25 is an operation tool that instructs switching between forward and reverse, but may also be an operation tool that can instruct both shifting and switching between forward and reverse. In this case, there will be multiple forward positions, and the autonomous driving mode may be switchable only when the vehicle is in a forward position on the low speed side, or may be switchable to the autonomous driving mode when the vehicle is in all forward positions.

In the above embodiment, the driving route acquisition unit 35 of the wireless communication terminal 46 generates the driving route, and the route processing unit 4c of the control unit 4 acquires a part or all of the route, but the route processing unit 4c may generate the driving route. Also, the monitor device 14 provided in the tractor 1 may generate the driving route, instead of the wireless communication terminal 46.

<Notes on the invention>
According to an aspect of the present invention, a work vehicle control device having the following configuration is provided. That is, the work vehicle control device includes a forward/reverse control unit and a travel mode control unit. The forward/reverse control unit controls the forward/reverse movement of the work vehicle. The travel mode control unit executes one of a plurality of travel modes including at least a manual travel mode in which the work vehicle is forward/reverse moved in response to the operation of an operating tool provided on the work vehicle, and an autonomous travel mode in which the work vehicle is controlled for forward/reverse movement without the operation of the operating tool. The travel mode control unit executes the autonomous travel mode by satisfying an autonomous travel start condition. The forward/reverse switching operating tool provided on the work vehicle is switchable between at least a forward position, a neutral position, and a reverse position. The autonomous travel start condition can be satisfied when the forward/reverse switching operating tool is in the forward position. When the autonomous travel mode is executed with the forward/reverse switching operating tool in the forward position, if the forward/reverse switching operating tool is not changed to the neutral position before a predetermined time has elapsed after the autonomous travel mode is executed, the travel mode control unit issues a warning that the autonomous travel mode will end.

As a result, the conditions for starting autonomous driving are met even when the forward/reverse switching device is in the forward position, so the work vehicle can be shifted from manual driving to autonomous driving without stopping. In addition, it is possible to confirm that the shift to autonomous driving has been made at the operator's discretion. Therefore, the switch from manual driving to autonomous driving can be made smoothly, improving safety.

In the work vehicle control device, the driving mode control unit continues the autonomous driving mode when the forward/reverse switching device is changed to the neutral position before the predetermined period has elapsed.

This allows the autonomous driving mode to continue with the forward/reverse switching device in the neutral position, preventing the work vehicle from moving regardless of the operator's intentions.

The driving mode control unit ends the autonomous driving mode if the forward/reverse switching device is not changed to the neutral position before the predetermined period has elapsed.

This prevents the autonomous driving mode from continuing when the forward/reverse switching device is in the forward position, so that when returning to manual driving, the work vehicle can be prevented from moving regardless of the operator's intentions.

1. Tractor (work vehicle)
4 Control unit (work vehicle control device)
4a Forward/reverse control unit 4b Travel mode control unit 4c Route processing unit 25 Forward/reverse switching lever (forward/reverse switching operation device)

Claims (3)

A work vehicle control method capable of causing a work vehicle to travel autonomously, comprising:
When a mode transition condition including a first operation state of an operating tool provided on the work vehicle is satisfied during the autonomous traveling of the work vehicle, a process of interrupting the autonomous traveling of the work vehicle;
and after the mode transition condition is satisfied and the autonomous driving of the work vehicle is interrupted, when another condition including a second operation state of an operating tool is satisfied , a process of enabling the work vehicle to be manually driven.
The second operation state is a state in which a forward/reverse switching lever as the operation tool is operated to a neutral position.
A work vehicle control method. The operating tool includes at least one of a brake pedal, a clutch pedal, a parking brake, and a steering handle in addition to the forward/reverse switching lever .
A work vehicle control method according to claim 1 . The method further includes a process of starting the autonomous driving of the work vehicle when an autonomous driving start condition is satisfied, the autonomous driving start condition including the identification of a work route along which the work vehicle can autonomously travel.
A work vehicle control method according to claim 1 or 2 .