JP7556103B2 - Autonomous driving method and system - Google Patents

Description

The present invention relates to an automatic driving method and an automatic driving system.

Some of the above-mentioned automatic driving systems for work vehicles are equipped with a target route generation unit that generates a target route that enables automatic driving of the work vehicle by performing the following steps: inputting the working width of the work equipment provided at the rear of the work vehicle; setting the work area in the field; setting the work start position and the work stop position; setting the reference driving start direction; setting headlands at both ends of the work area; and setting the driving route in the field (see, for example, Patent Document 1).

International Publication No. WO 2015/119263

The target route generated by the target route generating unit includes a plurality of parallel routes, including a work route that moves a work vehicle whose work implement is switched to a working state forward, and a plurality of direction-changing routes that change the direction of a work vehicle whose work implement is switched to a non-working state. When the various setting processes exemplified in the above-mentioned Patent Document 1 have been performed, the target route generating unit arranges a plurality of parallel routes in parallel with a predetermined interval based on the working width of the work implement for the set work area, and arranges a plurality of turning routes that connect the plurality of parallel routes in the travel order of the work vehicle for the headlands set at both ends of the work area, thereby generating a target route that enables automatic travel of the work vehicle.

To make the work vehicle automatically travel along the target route generated in this way, it is necessary to equip the work vehicle with a positioning unit that measures the position of the work vehicle on the work site using a satellite positioning system, a distance sensor, or the like. When equipping the work vehicle with a positioning unit, a positioning antenna that enables positioning of the work vehicle using a satellite positioning system, or a distance sensor that measures the distance of the work vehicle to the edge of the work site, is typically placed at a specified position on the work vehicle, and that position is set as the positioning reference point for the work vehicle.

In this configuration, when the work vehicle is automatically driven along the target route, for example, when the positioning reference point of the work vehicle reaches the end position of the parallel route, the work vehicle reaches the end position of the parallel route, and as a result, the route on which the work vehicle travels is switched from the parallel route to the turning route. The end position of the parallel route is set to the end position of the work route, and based on this route switching, the work device is switched from a working state to a non-working state. Therefore, at the end of each parallel route, the position of the work device when the positioning reference point of the work vehicle reaches the end position of the work route becomes the work end position of the work device of the work vehicle on the work route.

In other words, in the target route generated based on the technology described in Patent Document 1, the position located back from the end position of each work route (start position of the direction change route) toward the start of the work route by the work vehicle at the end side of each work route is the work end position by the work vehicle on the end side of each work route. Therefore, in each work route, between the end position of the work route and the work end position of the work vehicle when it reaches this end position, there is an unworked route that cannot be worked on by the work vehicle that is automatically traveling along the work route, by the aforementioned distance, and this leads to a decrease in work efficiency when working with the work vehicle automatically traveling.

In view of this situation, the main objective of the present invention is to shorten as much as possible the unworked paths that exist on each work route, thereby improving work efficiency when work is performed by an autonomous work vehicle.

An automatic driving method according to one embodiment is an automatic driving method for a work vehicle equipped with a working device at the rear that can be switched between a working state and a non-working state, in which the work vehicle, with the working device switched to the working state, is caused to travel forward beyond a working end position to a travel end position, and when the work vehicle reaches the travel end position, the working device is switched to the non-working state and the work vehicle is caused to travel backward, and before the work vehicle reaches the work end position, the work vehicle is switched from reverse travel to turning travel.

An automated driving system according to one embodiment is an automated driving system that includes a control unit that automatically drives a work vehicle equipped with a working device at the rear that can be switched between a working state and a non-working state. The control unit drives the work vehicle, with the working device switched to the working state, forward past the working end position to the traveling end position, switches the working device to the non-working state when the work vehicle reaches the traveling end position and drives the work vehicle in reverse, and switches the work vehicle from traveling in reverse to traveling in a turn before the work vehicle reaches the working end position.

FIG. 1 is a diagram showing a schematic configuration of an automatic driving system for a work vehicle. Schematic diagram showing the transmission configuration of a tractor A block diagram showing the schematic configuration of an automatic driving system for a work vehicle. A block diagram showing the schematic configuration of an obstacle detection unit, etc. FIG. 1 is a plan view showing an example of a target route for automatic driving; An enlarged view of a target route showing a state in which a work vehicle is moving forward along a work route in a work travel state. An enlarged view of a target route showing a state in which a work vehicle advances along a work route while in a work travel state and reaches an end position of the work route. FIG. 13 is an enlarged view of a target path showing a state in which the work vehicle has traveled backward along a first reverse path in a non-work traveling state and reached the start position of a start-side turning path; FIG. 1 is an enlarged view of a target path showing a state in which a work vehicle advances along a starting-end side turning path in a non-work traveling state and reaches an end position of the starting-end side turning path. FIG. 2 is an enlarged view of a target path showing a state in which the work vehicle advances along the right forward path in a non-work traveling state and reaches the end position of the right forward path; FIG. 2 is an enlarged view of a target path showing a state in which the work vehicle is moving backward along the left reverse path in a non-work traveling state and has reached the end position of the left reverse path; FIG. 13 is an enlarged view of a target path showing a state in which a work vehicle advances along a terminal side turning path in a non-work traveling state and reaches a terminal position of the terminal side turning path. An enlarged view of a target route showing a state in which a work vehicle advances along a non-work route in a non-work driving state and reaches an end position of the non-work route. FIG. 2 is an enlarged view of a target path showing a state in which the work vehicle has traveled backward along a second reverse path in a non-work traveling state and reached an end position of the second reverse path; An enlarged view of a target route showing a state in which a work vehicle is moving forward along a work route in a work travel state. A flowchart showing the control operation of the target route generation unit in the target route generation control. A flowchart showing the control operation of the target path generating unit in the parallel path generating process. A flowchart showing the control operation of the target route generating unit in the direction change route generating process. FIG. 13 is an enlarged view of a target path showing another embodiment in which a switching position is set at a position before the end position of the work path.

As an example of a form for implementing the present invention, an embodiment in which the automatic driving system for a work vehicle according to the present invention is applied to a tractor, which is an example of a work vehicle, will be described below with reference to the drawings.

The automatic driving system for a work vehicle according to the present invention can be applied to ride-on work vehicles capable of automatic driving, such as ride-on management machines, ride-on grass cutters, ride-on rice transplanters, and ride-on seed sowing machines, in addition to tractors, as well as unmanned work vehicles such as unmanned tillers and unmanned grass cutters.

As shown in FIG. 1, the tractor 1 illustrated in this embodiment has a rotary tilling device 3, which is an example of a working device, connected to the rear of the tractor 1 via a link mechanism 2 so that the rotary tilling device 3 can be raised, lowered, and rolled. This makes the tractor 1 configured for rotary tilling.

In addition, instead of the rotary tilling device 3, other work implements such as a plow, disc harrow, cultivator, subsoiler, seed sowing device, spraying device, grass cutting device, and harvesting device can be connected to the rear of the tractor 1.

By using an automatic driving system for work vehicles, the tractor 1 can be automatically driven in a field A (see FIG. 5), which is an example of a work site. As shown in FIGS. 1 and 3, the automatic driving system for work vehicles includes an automatic driving unit 4 mounted on the tractor 1, and a mobile communication terminal 5, which is an example of a wireless communication device set to be able to wirelessly communicate with the automatic driving unit 4. The mobile communication terminal 5 is equipped with a multi-touch display device 50 that allows various information related to automatic driving to be displayed and input operations to be performed.

The mobile communication terminal 5 may be a tablet-type personal computer or a smartphone. For wireless communication, a wireless LAN (Local Area Network) such as Wi-Fi (registered trademark) or a short-range wireless communication such as Bluetooth (registered trademark) may be used.

As shown in Figures 1 and 2, the tractor 1 is equipped with left and right front wheels 10 that can be driven and steered, and left and right rear wheels 11 that can be driven, as a traveling device. As shown in Figures 1 to 3, the tractor 1 is equipped with a cabin 13 that forms a riding driver's section 12, an electronically controlled diesel engine (hereinafter referred to as the engine) 14 with a common rail system, a bonnet 15 that covers the engine 14 and the like, and a transmission unit 16 that changes the speed of the power from the engine 14. Note that the engine 14 may be an electronically controlled gasoline engine with an electronic governor, etc.

As shown in FIG. 3, the tractor 1 is equipped with a fully hydraulic power steering unit 17 for steering the left and right front wheels 10, a brake unit 18 for braking the left and right rear wheels 11, an electronically controlled working clutch unit 19 for interrupting the transmission of power to the rotary tilling device 3, an electronically controlled lifting drive unit 20 for lifting and lowering the rotary tilling device 3, an electronically controlled rolling unit 21 for driving the rotary tilling device 3 in the roll direction, a vehicle state detection device 22 including various sensors and switches for detecting various settings and operating states of each part of the tractor 1, and an on-board control unit 23 having various control units. The power steering unit 17 may be an electric type having an electric motor for steering.

As shown in FIG. 1, the driving section 12 is equipped with a steering wheel 25 for manual steering, a seat 26 for the passenger, and an operation terminal 27 that enables various information displays and input operations. Although not shown in the figure, the driving section 12 is also equipped with operation levers such as an accelerator lever and a gear lever, and operation pedals such as an accelerator pedal and a clutch pedal. The operation terminal 27 can be a multi-touch LCD monitor or an ISOBUS-compatible virtual terminal.

As shown in FIG. 2, the transmission unit 16 is equipped with a traveling transmission system 16A that changes the speed of the power from the engine 14 for traveling, and a work transmission system 16B that changes the speed for work. The power after the speed change by the traveling transmission system 16A is transmitted to the left and right front wheels 10 via a front-wheel drive transmission shaft 28 and a front wheel differential 30 built into a front axle case 29. The power after the speed change by the work transmission system 16B is transmitted to the rotary tilling device 3. The transmission unit 16 is equipped with left and right brakes 31 that individually brake the left and right rear wheels 11.

The traveling transmission system 16A includes an electronically controlled main transmission 32 that changes the speed of the power from the engine 14, an electronically controlled forward/reverse switching device 33 that switches the power from the main transmission 32 between forward and reverse, a geared auxiliary transmission 34 that changes the forward or reverse power from the forward/reverse switching device 33 to two high and low speed stages, a geared creep transmission 35 that changes the forward or reverse power from the forward/reverse switching device 33 to an ultra-low speed stage, a rear wheel differential 36 that distributes the power from the auxiliary transmission 34 or the creep transmission 35 to the left and right rear wheels 11, left and right reduction gears 37 that reduce the speed of the power from the rear wheel differential 36 and transmit it to the left and right rear wheels 11, and an electronically controlled transmission switching device 38 that switches the transmission from the auxiliary transmission 34 or the creep transmission 35 to the left and right front wheels 10.

The work transmission system 16B includes a hydraulic work clutch 39 that interrupts the power from the engine 14, a work speed change device 40 that switches the power passing through the work clutch 39 between three forward speeds and one reverse speed, and a PTO shaft 41 that outputs the power from the work speed change device 40 for work use. The power extracted from the PTO shaft 41 is transmitted to the rotary tilling device 3 via an external transmission shaft (not shown) or the like. The work clutch 39 is included in the work clutch unit 19 together with an electromagnetic control valve (not shown) that controls the flow of oil to the work clutch 39, and the like.

The main transmission 32 uses an integrated hydrostatic mechanical transmission (I-HMT), an example of a hydrostatic mechanical continuously variable transmission that has higher transmission efficiency than a hydrostatic continuously variable transmission (HST).

In addition, instead of the I-HMT, the main transmission 32 may be a continuously variable transmission such as an HMT (Hydraulic Mechanical Transmission), which is an example of a hydromechanical continuously variable transmission, a hydrostatic continuously variable transmission, or a belt type continuously variable transmission. Also, instead of a continuously variable transmission, an electronically controlled stepped transmission having multiple hydraulically-controlled speed change clutches and multiple electromagnetic speed change valves that control the flow of oil to them may be used.

The transmission switching device 38 switches the transmission state to the left and right front wheels 10 between a transmission cut-off state in which the transmission to the left and right front wheels 10 is cut off, a constant speed transmission state in which power is transmitted to the left and right front wheels 10 so that the peripheral speed of the left and right front wheels 10 is the same as the peripheral speed of the left and right rear wheels 11, and a double speed transmission state in which power is transmitted to the left and right front wheels 10 so that the peripheral speed of the left and right front wheels 10 is approximately twice as fast as the peripheral speed of the left and right rear wheels 11. This allows the drive state of the tractor 1 to be switched between a two-wheel drive state, a four-wheel drive state, and a double front wheel speed state.

Although not shown in the figure, the brake unit 18 includes the left and right brakes 31 described above, a foot brake system that activates the left and right brakes 31 in conjunction with depression of the left and right brake pedals provided on the driver's unit 12, a parking brake system that activates the left and right brakes 31 in conjunction with operation of a parking lever provided on the driver's unit 12, and a turning brake system that activates the brake 31 on the inside of a turn in conjunction with steering of the left and right front wheels 10 beyond a set angle. The turning brake system includes an electronically controlled brake operating device 18A that can operate the left and right brakes 31 independently.

The vehicle state detection device 22 is a collective term for various sensors and switches provided in various parts of the tractor 1. As shown in FIG. 4, the vehicle state detection device 22 includes an accelerator sensor 22A that detects the operating position of the accelerator lever, a gear shift sensor 22B that detects the operating position of the gear shift lever, a reverser sensor 22C that detects the operating position of the reverser lever for switching between forward and reverse, a first rotation sensor 22D that detects the output speed of the engine 14, a vehicle speed sensor 22E that detects the vehicle speed of the tractor 1, a steering angle sensor 22F that detects the steering angle of the front wheels 10, a height sensor 22G that detects the height position of the rotary tilling device 3, and a second rotation sensor 22H that detects the rotation speed of the PTO shaft 41 as the drive rotation speed of the rotary tilling device 3.

As shown in FIG. 2, the vehicle speed sensor 22E is a rotation sensor that detects the rotation speed and direction of the transmission shaft 49 that transmits power from the sub-transmission device 34 or the creep transmission device 35 to the rear wheel differential device 36.

As shown in Figures 3 and 4, the vehicle control unit 23 includes an engine control unit 23A that controls the engine 14, a transmission unit control unit 23B that controls the transmission unit 16, such as the tractor 1's speed and forward/reverse switching, a steering control unit 23C that controls steering, a work device control unit 23D that controls work devices such as the rotary tiller 3, a display control unit 23E that controls displays and notifications on the operation terminal 27, an automatic travel control unit 23F that controls automatic travel, and a non-volatile vehicle storage unit 23G that stores a target route P for automatic travel (see Figure 5) generated according to the field A. Each control unit 23A to 23F is constructed by an electronic control unit in which a microcontroller or the like is integrated, various control programs, and the like. Each control unit 23A to 23F is connected to be able to communicate with each other via a CAN (Controller Area Network).

Note that communication standards other than CAN or next-generation communication standards, such as in-vehicle Ethernet or CAN-FD (CAN with Flexible Data rate), may be used for mutual communication between the control units 23A to 23F.

The engine control unit 23A performs engine speed maintenance control, which maintains the engine speed at a speed that corresponds to the operating position of the accelerator lever, based on the detection information from the accelerator sensor and the detection information from the first rotation sensor 22D.

The transmission unit control unit 23B calculates the actual vehicle speed of the tractor 1 and determines the traveling direction of the tractor 1 based on the detection information of the speed sensor 22E. The transmission unit control unit 23B executes vehicle speed control that controls the operation of the main transmission 32 so that the vehicle speed of the tractor 1 is changed to a speed corresponding to the operating position of the shift lever based on the detection information of the speed sensor 22B and the detection information of the speed sensor 22E, and forward/reverse switching control that switches the transmission state of the forward/reverse switching device 33 based on the detection information of the reverser sensor 22C. The vehicle speed control includes a deceleration/stop process that, when the shift lever is operated to the zero speed position, decelerates the main transmission 32 to the zero speed state to stop the tractor 1 from traveling.

The transmission unit control section 23B switches the driving mode of the tractor 1 between two-wheel drive mode, four-wheel drive mode, front wheel acceleration mode, turning brake mode, and front wheel acceleration turning brake mode based on the operation of a first selection switch (not shown) that enables the selection of the driving mode of the tractor 1. The first selection switch is provided in the driving section 12 and is included in the vehicle state detection device 22.

In the two-wheel drive mode, the transmission unit control unit 23B switches the transmission switching device 38 to a transmission cut-off state, causing the tractor 1 to travel in a two-wheel drive state in which power transmission to the left and right front wheels 10 is cut off and only the left and right rear wheels 11 are driven.

In the four-wheel drive mode, the transmission unit control unit 23B switches the transmission switching device 38 to a constant speed drive state, causing the tractor 1 to travel in a four-wheel drive state in which power is transmitted to the left and right front wheels 10 and the left and right rear wheels 11 are driven at a constant speed.

In the front wheel speed increase mode, the speed change unit control section 23B executes front wheel speed change control to switch the transmission switching device 38 between a constant speed transmission state and a double speed transmission state based on the detection information of the steering angle sensor 22F. The front wheel speed change control includes a front wheel speed increase process to determine that the tractor 1 has started turning when the steering angle of the front wheels 10 reaches a set angle or more, and to switch the transmission switching device 38 from the constant speed transmission state to the double speed transmission state, and a front wheel deceleration process to determine that the tractor 1 has finished turning when the steering angle of the front wheels 10 falls below the set angle. As a result, in the front wheel speed increase mode, the tractor 1 can be made to run in a front wheel speed increase state when the tractor 1 is turning, and the turning radius of the tractor 1 can be reduced.

In the turning brake mode, the transmission unit control unit 23B executes turning brake control that controls the operation of the brake operating device 18A to switch the left and right brakes 31 between a brake release state and a turning inside brake state based on the detection information of the steering angle sensor 22F. The turning brake control includes a turning inside braking process that determines that the tractor 1 has started turning when the steering angle of the front wheels 10 reaches a set angle or more, determines the steering direction of the front wheels 10 from the direction of increase or decrease in the steering angle at that time, and switches the turning inside brake 31 from the brake release state to the braked state, and a brake release process that determines that the tractor 1 has finished turning when the steering angle of the front wheels 10 reaches less than the set angle, and switches the brake 31 in the braked state (turning inside) to the brake release state. As a result, in the turning brake mode, the tractor 1 can be driven in a braking state on the inside of the turn when the tractor 1 is turning, thereby reducing the turning radius of the tractor 1.

In the front wheel acceleration turning brake mode, the speed change unit control unit 23B executes the front wheel speed change control and turning brake control described above based on the detection information of the steering angle sensor 22F. As a result, in the front wheel acceleration turning brake mode, the tractor 1 can be made to run in a front wheel acceleration turning inside braking state when the tractor 1 is turning, and the turning radius of the tractor 1 can be further reduced.

The working device control unit 23D executes a work clutch control that controls the operation of the work clutch unit 19 based on the operation of the PTO switch 22K (see FIG. 4) provided in the driving unit 12, a lift control that controls the operation of the lift drive unit 20 based on the operation of the lift switch 22L (see FIG. 4) provided in the driving unit 12 and the setting value of the height setting dial, and a rolling control that controls the operation of the rolling unit 21 based on the setting value of the roll angle setting dial provided in the driving unit 12. The PTO switch 22K, the lift switch 22L, the height setting dial, and the roll angle setting dial are included in the vehicle state detection device 22.

As shown in FIG. 3, the tractor 1 is equipped with a positioning unit 42 that measures the position and orientation of the tractor 1. The positioning unit 42 includes a satellite navigation device 43 that measures the position and orientation of the tractor 1 using a global navigation satellite system (GNSS), which is an example of a satellite positioning system, and an inertial measurement unit (IMU) 44 that has a three-axis gyroscope and a three-directional acceleration sensor and measures the attitude and orientation of the tractor 1. Positioning methods that use the GNSS include DGNSS (Differential GNSS: relative positioning method) and RTK-GNSS (Real Time Kinematic GNSS: interferometric positioning method). In this embodiment, RTK-GNSS, which is suitable for positioning mobile objects, is used. Therefore, as shown in FIG. 1, base stations 6 that enable positioning using RTK-GNSS are installed at known positions around the field.

As shown in Figs. 1 and 3, the tractor 1 and the base station 6 are each equipped with a GNSS antenna 45, 60 for receiving radio waves transmitted from a positioning satellite 7 (see Fig. 1), and a communication module 46, 61 for enabling wireless communication of information including positioning information between the tractor 1 and the base station 6. This allows the satellite navigation device 43 of the positioning unit 42 to measure the position and orientation of the tractor 1 with high accuracy based on the positioning information obtained by the GNSS antenna 45 of the tractor 1 receiving radio waves from the positioning satellite 7 and the positioning information obtained by the GNSS antenna 60 of the base station 6 receiving radio waves from the positioning satellite 7. In addition, the positioning unit 42 has the satellite navigation device 43 and the inertial measurement unit 44, and can measure the position, orientation, and attitude angles (yaw angle, roll angle, pitch angle) of the tractor 1 with high accuracy.

In this tractor 1, the inertial measurement unit 44, GNSS antenna 45, and communication module 46 of the positioning unit 42 are included in the antenna unit 47 shown in FIG. 1. The antenna unit 47 is located in the center of the upper left and right sides on the front side of the cabin 13.

Although not shown in the figure, the position of the tractor 1 measured by the positioning unit 42 (positioning reference position) is set to the installation position of the GNSS antenna 45 on the tractor 1. The GNSS antenna 45 is installed at the upper front side of the cabin 13, at the left-right center of the tractor 1.
The position of the tractor 1 measured by the positioning unit 42 may be set to the rear axle center position of the tractor 1 instead of the installation position of the GNSS antenna 45. In this case, the position of the tractor 1 can be obtained from the positioning information of the positioning unit 42 and vehicle information including the positional relationship between the installation position of the GNSS antenna 45 on the tractor 1 and the rear axle center position.

As shown in FIG. 3, the mobile communication terminal 5 is equipped with a terminal control unit 51 having an electronic control unit in which a microcontroller and the like are integrated, various control programs, and the like. The terminal control unit 51 includes a display control unit 51A that controls display and notification on the display device 50 and the like, a target route generation unit 51B that generates a target route P that enables the tractor 1 to travel automatically, and a non-volatile terminal memory unit 51C that stores the target route P generated by the target route generation unit 51B, and the like. The terminal memory unit 51C stores various information used to generate the target route P, such as vehicle body information including the turning radius of the tractor 1 and the working width of the rotary tilling device 3, and field information including the position and shape of the field A, and the like.

The target route P is stored in the terminal storage unit 51C in association with vehicle information, field information, etc., and can be displayed on the display device 50 of the mobile communication terminal 5. The target route P includes various information related to automatic driving, such as the direction of travel of the tractor 1, the target vehicle speed, the front wheel steering angle, the start position pa of automatic driving, and the end position pb of automatic driving.

As shown in FIG. 3, the tractor 1 and the mobile communication terminal 5 are equipped with communication modules 48, 52 that enable wireless communication of various information, including positioning information, between the on-board control unit 23 and the terminal control unit 51. When Wi-Fi is used for wireless communication with the mobile communication terminal 5, the communication module 48 of the tractor 1 functions as a converter that converts communication information in both directions, between CAN and Wi-Fi. The terminal control unit 51 can obtain various information related to the tractor 1, including the position and orientation of the tractor 1, through wireless communication with the on-board control unit 23. This allows various information, including the position and orientation of the tractor 1 relative to the target route P, to be displayed on the display device 50 of the mobile communication terminal 5.

In response to a transmission request command from the vehicle control unit 23, the terminal control unit 51 transmits the field information, the target route P, and the like stored in the terminal storage unit 51C to the vehicle control unit 23. The vehicle control unit 23 stores the received field information, the target route P, and the like in the vehicle storage unit 23G. Regarding the transmission of the target route P, for example, the terminal control unit 51 may transmit all of the target route P from the terminal storage unit 51C to the vehicle control unit 23 at once before the tractor 1 starts automatic traveling. Alternatively, the terminal control unit 51 may divide the target route P into a plurality of divided route information for each predetermined distance, and sequentially transmit a predetermined number of divided route information according to the traveling order of the tractor 1 from the terminal storage unit 51C to the vehicle control unit 23 each time the traveling distance of the tractor 1 reaches a predetermined distance from the stage before the tractor 1 starts automatic traveling.

Detection information from various sensors and switches included in the vehicle state detection device 22 is input to the automatic driving control unit 23F. This allows the automatic driving control unit 23F to monitor various setting states and the operating state of each part of the tractor 1.

When a user, such as a passenger or manager, performs various manual setting operations to enable automatic driving of the tractor 1 and switches the driving mode of the tractor 1 from manual driving mode to automatic driving mode, and the display device 50 of the mobile communication terminal 5 is operated to instruct the start of automatic driving, the automatic driving control unit 23F starts automatic driving control to automatically drive the tractor 1 according to the target route P while acquiring the position, direction, etc. of the tractor 1 using the positioning unit 42.

When the automatic driving control is being performed, for example, if the user operates the display device 50 of the mobile communication terminal 5 to instruct the end of automatic driving, or if the user in the driver's unit 12 operates a manual operation tool such as the steering wheel 25 or accelerator pedal, the automatic driving control unit 23F ends the automatic driving control and switches the driving mode from the automatic driving mode to the manual driving mode.

The automatic driving control by the automatic driving control unit 23F includes an automatic engine control process that transmits automatic driving control commands related to the engine 14 to the engine control unit 23A, an automatic vehicle speed control process that transmits automatic driving control commands related to the tractor 1's vehicle speed and forward/reverse switching to the transmission unit control unit 23B, an automatic steering control process that transmits automatic driving control commands related to the steering to the steering control unit 23C, and an automatic work control process that transmits automatic driving control commands related to work equipment such as the rotary tiller 3 to the work equipment control unit 23D.

In the automatic engine control process, the automatic driving control unit 23F transmits to the engine control unit 23A an engine speed change command that instructs a change in engine speed based on the set speed included in the target route P. The engine control unit 23A executes engine speed change control that automatically changes the engine speed in response to various control commands related to the engine 14 transmitted from the automatic driving control unit 23F.

In the automatic vehicle speed control process, the automatic travel control unit 23F transmits to the transmission unit control unit 23B a speed change operation command that instructs the main transmission 32 to change speed based on the target vehicle speed included in the target route P, and a forward/reverse switch command that instructs the forward/reverse switch operation of the forward/reverse switch based on the traveling direction of the tractor 1 included in the target route P. The transmission unit control unit 23B executes an automobile speed control that automatically controls the operation of the main transmission 32, an automatic forward/reverse switch control that automatically controls the operation of the forward/reverse switch, and the like, in response to various control commands related to the main transmission 32 and the forward/reverse switch transmitted from the automatic travel control unit 23F. The automobile speed control includes, for example, an automatic deceleration/stop process that decelerates the main transmission 32 to a zero speed state to stop the tractor 1 from traveling when the target vehicle speed included in the target route P is zero speed.

In the automatic control process for steering, the automatic driving control unit 23F transmits to the steering control unit 23C steering commands instructing the steering of the left and right front wheels 10 based on the front wheel steering angle included in the target route P. In response to the steering commands transmitted from the automatic driving control unit 23F, the steering control unit 23C executes automatic steering control for controlling the operation of the power steering unit 17 to steer the left and right front wheels 10, and automatic turning brake control for operating the brake unit 18 to apply the brakes on the inside of a turn when the left and right front wheels 10 are steered beyond a set angle.

In the automatic control process for work, the automatic travel control unit 23F transmits to the work device control unit 23D a work start command that instructs the rotary tilling device 3 to switch to a working state based on the tractor 1 reaching each work start position included in the target route P, and a work end command that instructs the rotary tilling device 3 to switch to a non-working state based on the tractor 1 reaching each work stop position included in the target route P. In response to various control commands related to the rotary tilling device 3 transmitted from the automatic travel control unit 23F, the work device control unit 23D controls the operation of the work clutch unit 19 and the lift drive unit 20 to perform automatic work start control that drives the rotary tilling device 3 to lower it to the working height, and automatic work end control that raises the rotary tilling device 3 to the non-working height and stops driving it. This allows the driving state of the tractor 1, which runs automatically along the target route P, to be switched between a working driving state in which the tractor 1 runs automatically with the rotary tilling device 3 in a working state (when the rotary tilling device 3 is driven and lowered to the working height) and a non-working driving state in which the tractor 1 runs automatically with the rotary tilling device 3 in a non-working state (when the rotary tilling device 3 is raised to the non-working height and stopped being driven).

In other words, the aforementioned automatic driving unit 4 includes a power steering unit 17, a brake unit 18, a working clutch unit 19, a lifting drive unit 20, a rolling unit 21, a vehicle condition detection device 22, an on-board control unit 23, a positioning unit 42, and communication modules 46, 48. By properly operating these, the tractor 1 can be automatically driven with high precision along the target route P, and the rotary tilling device 3 can properly perform tilling work.

As shown in Figures 3 and 4, the tractor 1 is equipped with a surrounding condition acquisition system 8 that acquires the surrounding conditions of the tractor 1. As shown in Figure 4, the surrounding condition acquisition system 8 includes an imaging unit 80 that captures images of the surroundings of the tractor 1 to acquire image information, and an obstacle detection unit 85 that detects obstacles present around the tractor 1. Obstacles detected by the obstacle detection unit 85 include people such as workers working in the field A, other work vehicles, and existing utility poles and trees in the field A.

As shown in Figures 1 and 4, the imaging unit 80 includes a front camera 81 whose imaging range is set to a predetermined range forward from the cabin 13, a rear camera 82 whose imaging range is set to a predetermined range rearward from the cabin 13, and an image processing device 83 (see Figure 4) that processes image information from the front and rear cameras 81, 82. The image processing device 83 is constructed by an electronic control unit that integrates microcontrollers and various control programs. The image processing device 83 is connected to the on-board control unit 23 and the like via CAN so that they can communicate with each other.

The image processing device 83 performs image generation processing and the like to generate front and rear images of the tractor 1 corresponding to the imaging ranges of the cameras 81, 82 for the image information sequentially transmitted from the front and rear cameras 81, 82. Then, it performs image transmission processing to transmit each generated image to the display control unit 23E of the on-board control unit 23. The display control unit 23E transmits each image from the image processing device 83 to the operation terminal 27 via the CAN, and also transmits them to the display control unit 5A of the mobile communication terminal 5 via the communication modules 48, 52.

This allows the front and rear images of the tractor 1 generated by the image processing device 83 to be displayed on the operation terminal 27 of the tractor 1, the display device 50 of the mobile communication terminal 5, etc. This display allows the user to easily grasp the situation in front and behind the tractor 1.

As shown in Figures 1 and 4, the obstacle detection unit 85 includes a front obstacle sensor 86, whose obstacle detection range is set to the front side of the tractor 1, a rear obstacle sensor 87, whose obstacle detection range is set to the rear side of the tractor 1, and a lateral obstacle sensor 88, whose obstacle detection range is set to both the left and right sides of the tractor 1. The front obstacle sensor 86 and rear obstacle sensor 87 use lidar sensors that use pulsed near-infrared laser light to detect obstacles. The lateral obstacle sensor 88 uses sonar that uses ultrasonic waves to detect obstacles.

As shown in FIG. 4, the front obstacle sensor 86 and the rear obstacle sensor 87 have measurement units 86A, 87A that use near-infrared laser light to measure the distance to each distance measurement point (measurement object) in the measurement range, and control units 86B, 87B that perform operations such as generating distance images based on the measurement information of the measurement units 86A, 87A. The side obstacle sensor 88 has a right ultrasonic sensor 88A and a left ultrasonic sensor 88B that transmit and receive ultrasonic waves, and a single control unit 88C that measures the distance to the measurement object in the measurement range based on the transmission and reception of ultrasonic waves by each ultrasonic sensor 88A, 88B.

The control units 86B, 87B, and 88C of the obstacle sensors 86 to 88 are constructed using electronic control units that integrate microcontrollers and various control programs. The control units 86B, 87B, and 88C are connected to the vehicle control unit 23 and other units via CAN so that they can communicate with each other.

The automatic driving control unit 23F executes collision avoidance control to control the driving of the tractor 1 to avoid collision with an obstacle based on the positioning information of the positioning unit 42 and the detection information of each obstacle sensor 86-88 transmitted to the on-board control unit 23. In the collision avoidance control, the automatic driving control unit 23F controls the driving of the tractor 1 to avoid collision with an obstacle by instructing the transmission unit control unit 23B to execute driving control for each collision avoidance according to the detection information of each obstacle sensor 86-88.

The target path generating unit 51B executes target path generation control to generate a target path P based on vehicle information including the turning radius of the tractor 1 and the working width of the rotary tillage device 3, field information including the position and shape of the field A in which the tractor 1 is used to work, and various optional setting information set by the user.

The vehicle information includes a first distance L1 (see Figures 5 to 8) from the installation position of the GNSS antenna 45 on the tractor 1 to the rotary tillage device 3, which is measured by the positioning unit 42, and a second distance L2 (see Figures 5 to 8) from the rear wheels 11 of the tractor 1 to the rotary tillage device 3.

In this embodiment, as shown in FIG. 1, the first separation distance L1 is set to the distance from the installation position of the GNSS antenna 45 on the tractor 1 to the rotation center position X1 of the tilling tines 3A on the rotary tilling device 3. The second separation distance L2 is set to the distance from the axle center X2 of the rear wheel 11 on the tractor 1 to the rotation center position X1 of the tilling tines 3A.

The field information includes a number of shape-specific points (shape-specific coordinates) Cp1 to Cp4 (see FIG. 5) in field A that are acquired using GNSS when tractor 1 is driven along the outer edge of field A to identify the shape, size, etc. of field A, and a shape-specific line SL (see FIG. 5) that connects these shape-specific points to identify the shape, size, etc. of field A.

In this embodiment, as shown in FIG. 5, a rectangular field A is exemplified as field A, so four corner points Cp1 to Cp4 are acquired as multiple shape-specific points, and a rectangular shape-specific line SL is generated that connects the corner points Cp1 to Cp4.

The control operation of the target route generation unit 51B in the target route generation control will be described below based on the target route P shown in Figures 5 to 15 and the flowcharts shown in Figures 16 to 18.

In addition, this target route generation control will be explained on the assumption that various optional setting information, such as the start position pa and end position pb of automatic driving, and the work driving direction of the tractor 1, have already been manually input by the user.

As shown in the flowchart of FIG. 16, for example, in the rectangular field A shown in FIG. 5, when the start position pa and end position pb of the automatic driving are set to the positions shown in FIG. 5 and the working driving direction of the tractor 1 is set to the direction along the short side of the field A, the target path generating unit 51B first performs a first division process to divide the field A into a margin area A1 adjacent to the outer periphery of the field A and a workable area A2 located inside the margin area A1 based on the four corner points Cp1 to Cp4 and the rectangular shape specification line SL described above (step #1).

The margin area A1 is an area secured between the outer edge of the field A and the workable area A2 to prevent the rotary tilling device 3 and other devices from coming into contact with other objects such as ridges and fences adjacent to the field A when the tractor 1 automatically travels along the edge of the workable area A2.

The target path generating unit 51B performs a second division process based on the turning radius of the tractor 1 and the working width of the rotary tilling device 3, dividing the workable area A2 into a pair of direction change areas A2a set at the ends of each long side of the workable area A2, and a round trip travel area A2b set between the pair of direction change areas A2a (step #2).

In addition, in Figures 5 to 15, a boundary line BL is shown indicating the boundary between the direction change area A2a and the reciprocating driving area A2b to make it easier to understand the direction change area A2a and the reciprocating driving area A2b.

The target path generating unit 51B performs a parallel path generating process to generate multiple parallel paths P1 arranged in parallel at a predetermined interval according to the working width in the direction along the long side of the field A in the round trip travel area A2b (step #3).

The target path generating unit 51B performs a turning path generating process to generate multiple turning paths P2 for turning the tractor 1 whose rotary tilling device 3 has been switched to the working state in each turning area A2a (step #4).

The various types of optional setting information described above include the type of direction change route P2, and in this embodiment, as shown in Figures 5 to 15, an example is shown in which a switchback type turning route, in which the tractor 1 changes direction in a fishtail shape by using a switchback, is selected as the direction change route P2.
Incidentally, as the direction change path P2, in addition to a switchback type turning path, a U-shaped turning path in which the tractor 1 turns in a U-shape can be selected.

In the parallel path generation process, as shown in the flowchart of FIG. 17, the target path generation unit 51B performs a first path generation process to generate a first forward path (non-work path described in the claims) P1a that extends from the start position p1 of each parallel path P1 to a first intermediate position p2 that is separated by a first predetermined distance L3 in the forward direction of the tractor 1 on the parallel path P1 (step #31).

The target path generating unit 51B performs a second path generating process to generate a reverse path (a second reverse path described in the claims) P1b that extends from the first intermediate position p2 to a second intermediate position p3 that is separated by a predetermined length L4 in the reverse direction of the tractor 1 on the parallel path P1 (step #32).

The target path generating unit 51B performs a third path generating process to generate a second forward path P1c extending from the second relay position p3 to the end position p4 of the parallel path P1 (step #33). In this third path generating process, the target path generating unit 51B extends the start side of the second forward path P1c by a predetermined length L4 extending from the first relay position p2 to the second relay position p3, and extends the end side of the second forward path P1c by a predetermined length L4 from the boundary between the direction change area A2a and the reciprocating running area A2b, and sets the total length of the second forward path P1c to a length having a second predetermined distance L5 from the second relay position p3 beyond the boundary between the direction change area A2a and the reciprocating running area A2b, where the end side of the second forward path P1c enters the direction change area A2a by the predetermined length L4.

The target route generation unit 51B performs a first switching position setting process to set the first relay position p2 to a first switching position at which the route traveled by the tractor 1 is switched from the first forward route P1a to the reverse route P1b when the tractor 1 reaches the first relay position p2 (step #34).

The target route generation unit 51B performs a second switching position setting process to set the second relay position p3 to a second switching position at which the route traveled by the tractor 1 is switched from the reverse route P1b to the second forward route P1c when the tractor 1 reaches the second relay position p3 (step #35).

In the direction change path generation process, as shown in the flowchart of FIG. 18, the target path generation unit 51B performs a fourth path generation process to generate a starting end side turning path P2a that turns the tractor 1 forward 90 degrees to the right from the starting end position p5 of each direction change path P2 (step #41).

The target path generating unit 51B performs a fifth path generation process to generate a right forward path P2b that moves the tractor 1 forward to the right from the end position p6 of the starting end side turning path P2a (step #42).

The target path generating unit 51B performs a sixth path generating process to generate a left reverse path P2c that moves the tractor 1 backward to the left from the end position p7 of the right forward path P2b (step #43).

The target path generating unit 51B performs a seventh path generating process to generate a terminal side turning path P2d that turns the tractor 1 forward 90 degrees to the right from the terminal position p8 of the left reverse path P2c (step #44).

The target path generating unit 51B performs a third switching position setting process to set the end position p6 of the starting end side turning path P2a to a third switching position at which the path traveled by the tractor 1 is switched from the starting end side turning path P2a to the right forward path P2b as the tractor 1 reaches this end position p6 (step #45).

The target path generating unit 51B performs a fourth switching position setting process to set the end position p7 of the right forward path P2b to a fourth switching position at which the path traveled by the tractor 1 is switched from the right forward path P2b to the left reverse path P2c as the tractor 1 reaches this end position p7 (step #46).

The target path generating unit 51B performs a fifth switching position setting process to set the terminal position p8 of the left reverse path P2c to a fifth switching position at which the path traveled by the tractor 1 is switched from the left reverse path P2c to the terminal side turning path P2d as the tractor 1 reaches this terminal position p8 (step #47).

The target path generating unit 51B performs a sixth switching position setting process to set the terminal position p9 of the terminal side turning path P2d to a sixth switching position at which the path traveled by the tractor 1 is switched from the terminal side turning path P2d to the first forward path P1a of the parallel path P1 as the tractor 1 reaches this terminal position p9 (step #48).

As shown in the flowchart of FIG. 16, the target path generating unit 51B performs a parallel path generating process and a direction change path generating process, and then performs a reverse path generating process to generate an intermediate reverse path (first reverse path described in the claims) P3 that reverses the tractor 1 from the end position p4 of the parallel path P1 to the start position p5 of the direction change path P2 (step #5).

In this way, the target route generation unit 51B generates a target route P suitable for the tractor 1 to perform tilling work in the field A while autonomously driving.

When the tractor 1 is positioned in an appropriate posture that enables automatic driving along the target path P at the start position of the target path P (start position p1 of the parallel path P1), which is the start position pa of automatic driving, and an instruction to start automatic driving is issued, the automatic driving control unit 23F first moves the tractor 1 forward along the first forward path P1a of the parallel path P1 in a non-working driving state in which the rotary tilling device 3 has been switched to a non-working state (see Figures 12-13).

When the tractor 1 reaches the first relay position p2, which is the end position of the first forward path P1a, the automatic driving control unit 23F switches the driving path from the first forward path P1a to the reverse path P1b upon reaching the tractor 1, and based on this, switches the tractor 1 from a forward state to a reverse state via the transmission unit control unit 23B. This causes the tractor 1 to move backward along the reverse path P1b in a non-work driving state (see Figures 13-14).

When the tractor 1 reaches the second relay position p3, which is the end position of the reverse path P1b, the automatic driving control unit 23F switches the driving path from the reverse path P1b to the second forward path P1c as the tractor 1 reaches the second relay position p3, and based on this switching, switches the tractor 1 from the reverse state to the forward state via the transmission unit control unit 23B and switches the rotary tilling device 3 from the non-working state to the working state. This causes the tractor 1 to move forward along the second forward path P1c in a working driving state in which the rotary tilling device 3 has been switched to the working state (see Figures 14-15 and 6).

When the tractor 1 reaches the end position p4 of the parallel path P1, which is the end position of the second forward path P1c, the automatic travel control unit 23F switches the travel path from the second forward path P1c to the intermediate reverse path P3 upon reaching the tractor 1, and switches the rotary tilling device 3 from a working state to a non-working state via the transmission unit control unit 23B. This causes the tractor 1 to travel in reverse along the intermediate reverse path P3 in a non-working travel state (see Figures 7-8).

When the tractor 1 reaches the starting position p5 of the direction change path P2, which is the end position of the intermediate reverse path P3, the automatic driving control unit 23F switches the driving path from the intermediate reverse path P3 to the starting end turning path P2a of the direction change path P2 upon the tractor 1 reaching the starting position p5, and switches the tractor 1 from a reverse state to a forward state via the transmission unit control unit 23B. This causes the tractor 1 to move forward along the starting end turning path P2a in a non-work driving state (see Figures 8-9).

When the tractor 1 reaches the end position p6 of the starting end turning path P2a, the automatic driving control unit 23F causes the tractor 1 to move forward along the right forward path P2b in a non-work driving state based on the fact that the driving path is switched from the starting end turning path P2a to the right forward path P2b upon reaching the end position p6 (see Figures 9-10).

When the tractor 1 reaches the end position p7 of the right forward path P2b, the automatic driving control unit 23F switches the driving path from the right forward path P2b to the left reverse path P2c upon reaching the end position p7, and based on this, switches the tractor 1 from a forward state to a reverse state via the transmission unit control unit 23B. This causes the tractor 1 to move backward along the left reverse path P2c in a non-work driving state (see Figures 10-11).

When the tractor 1 reaches the terminal position p8 of the left reverse path P2c, the automatic driving control unit 23F switches the driving path from the left reverse path P2c to the terminal side turning path P2d upon reaching the terminal position p8, and based on this, switches the tractor 1 from a reverse state to a forward state via the transmission unit control unit 23B. This causes the tractor 1 to move forward along the terminal side turning path P2d in a non-work driving state (see Figures 11-12).

When the tractor 1 reaches the terminal position p9 of the terminal side turning path P2d, the automatic driving control unit 23F causes the tractor 1 to move forward along the first forward path P1a in a non-work driving state based on the fact that the driving path is switched from the terminal side turning path P2d to the first forward path P1a of the parallel path P1 upon reaching the terminal position p9 (see Figures 12-13).

In other words, in this target path P, the second forward path P1c of each parallel path P1 functions as a working path that moves the tractor 1 forward when the rotary tilling device 3 is switched to the working state. The target path P is generated by route setting that connects the second forward paths (working paths) P1c of the multiple parallel paths P1 arranged in parallel at a predetermined interval according to the working width to the traveling order of the tractor 1 via multiple intermediate reverse paths P3, multiple direction change paths P2, and the first forward paths P1a and reverse paths P1b of the multiple parallel paths P1.

In addition, in this target path P, the second forward path P1c is generated such that its end side is extended by a predetermined length L4 and enters the direction change path P2 side at the predetermined length L4. Then, an intermediate reverse path P3 is generated that reverses the tractor 1 from the end position p4 of the extended second forward path P1c to the start position p5 of the direction change path.

As a result, when the tractor 1 is automatically driven according to this target path P, the rotary tilling device 3 can be maintained in a working state until the tractor 1 reaches the terminal position p4 of the extended second forward path P1c beyond the start position p5 of the direction change path P2. As a result, compared to when the end position p4 of the second forward path P1c is set to the start position p5 of the direction change path P2, the working end position pd, which is the ground contact position of the rotary tilling device 3 when the tractor 1 reaches the end position p4 of the second forward path P1c, can be brought closer to the start position p5 of the direction change path P2.

As a result, in each second forward path P1c, the unworked path existing between the end position pd of the work by the tractor 1 and the start position p5 of the direction change path P2 can be shortened by a predetermined length L4 that extends the second forward path P1c. This makes it possible to widen the working area in which the tractor 1 works while automatically traveling, and improves the working efficiency when working while the tractor 1 works while automatically traveling.

Incidentally, in Figures 5 to 15, the position of the rotary tilling device 3 when the tractor 1 reaches the starting position p5 of the direction change path P2 is indicated by the symbol px, and it is shown that the ground contact position pd of the rotary tilling device 3 when the tractor 1 reaches the terminal position p4 of the second forward path P1c and ends the work drive is closer to the starting position p5 of the direction change path P2 than the position px of the rotary tilling device 3 when the tractor 1 reaches the starting position p5 of the direction change path P2.

Then, during the period from when the tractor 1 reaches the terminal position p4 of the second forward path P1c until it changes direction along the direction change path P2, the tractor 1 moves backward along the intermediate reverse path P3 from the terminal position p4 of the second forward path P1c to the starting position p5 of the direction change path P2 in a non-work traveling state, so that the position and width of the direction change area in which the tractor 1 changes direction can be kept the same as before the terminal side of the second forward path P1c was extended, and the tractor 1 can be properly changed direction along the direction change path P2 toward the starting position p1 of the next parallel path P1.

Therefore, the aforementioned unworked route can be shortened without changing the position and width of the direction change area A2a where the tractor 1 changes direction, improving work efficiency when working with the tractor 1 traveling automatically.

In this target path P, a predetermined length L4 extending the terminal side of the second forward path P1c is set to a length based on the second separation distance L2 from the rear wheels 11 of the tractor 1 to the rotary tillage device 3. Specifically, the predetermined length L4 is set to a length shorter than the second separation distance L2 from the axle center X2 of the rear wheels 11 of the tractor 1 to the rotation center position X1 of the tillage tines 3A of the rotary tillage device 3.

This makes it possible to prevent the rear wheels 11 of the tractor 1 from stepping into an area already being worked on by the rotary tilling device 3 when the tractor 1 moves backward along the intermediate reverse path P3 from the terminal position p4 of the second forward path P1c to the starting position p5 of the direction change path P2 in a non-working driving state.

This makes it possible to shorten the previously unworked path while avoiding the risk of the rear wheels 11 of the tractor 1 stepping into an already worked area, thereby improving work efficiency when working with the tractor 1 traveling automatically.

In this target path P, the starting position of the second forward path P1c (second intermediate position p3) is set to a position closer to the starting position p1 of the parallel path P1 by a predetermined length L4 than the first intermediate position p2, which is separated by a first predetermined distance L3 from the starting position p1 of each parallel path P1, so that the work starting position pc, which is the ground contact position of the rotary tilling device 3 when the tractor 1 after turning reaches the second intermediate position p3, which is the starting position of the second forward path P1c, coincides with the work end position pd, which is the ground contact position of the rotary tilling device 3 when the tractor 1 reaches the end position p4 of the extended second forward path P1c.

This allows the ground contact position (work start position) pc of the rotary tilling device 3 when the tractor 1 reaches the start position p3 of the second forward path P1c and starts working travel to be aligned with the ground contact position (work end position) pd of the rotary tilling device 3 when the tractor 1 reaches the end position p6 of the second forward path P1c and ends working travel.

Furthermore, similar to the terminal end of the second forward path P1c, the ground contact position (operation start position) pc of the rotary tilling device 3 when the tractor 1 reaches the start position p3 of the second forward path P1c can be brought closer to the terminal position p9 of the direction change path P2.

Therefore, the unworked path between the end position p9 of each direction change path P2 and the work start position pc by the tractor 1 can be shortened, and the work efficiency can be improved when working with the tractor 1 automatically traveling, and the work accuracy can be improved when working with the tractor 1 automatically traveling.

This target path P includes a first forward path P1a that extends from the end position p9 of the direction change path P2 past the start position p3 of the second forward path P1c, and a reverse path P1b that reverses the tractor 1 from the first intermediate position p2, which is the end position of the first forward path P1a, to the start position p3 of the second forward path P1c.

As a result, if the position or orientation of the tractor 1 deviates beyond the allowable range with respect to the second forward path P1c when the tractor 1 moves from the end position p9 of the direction change path P2 to the start position p3 of the second forward path P1c, the position and orientation of the tractor 1 with respect to the start position p3 of the second forward path P1c can be corrected to within the allowable range by moving the tractor 1 forward on the first forward path P1a and reversing the tractor 1 on the reverse path P1b.

As a result, the position and orientation of the tractor 1 relative to the second forward path P1c can be adjusted appropriately when the tractor 1 reaches the starting position p3 of the second forward path P1c and starts working, improving the work accuracy when working with the tractor 1 traveling automatically.

The various optional setting information described above includes the driving mode of the tractor 1 selected by operating the first selection switch described above. Therefore, in the above-mentioned turn path generation process, the target path generation unit 51B determines the turning radius of the start side turning path P2a and the end side turning path P2d according to the arbitrarily set driving mode of the tractor 1. When the front wheel acceleration mode, the turning brake mode, and the front wheel acceleration turning brake mode are arbitrarily set as the driving mode of the tractor 1, the automatic driving control unit 23F switches the driving mode of the tractor 1 to the arbitrarily set driving mode when the tractor 1 reaches the start position p5 of the turn path P2, which is the end position of the intermediate reverse path P3. When the tractor 1 reaches the end position p6 of the start side turning path P2a, the automatic driving control unit 23F returns the driving mode of the tractor 1 to the original driving mode before being switched to the arbitrarily set driving mode. When the tractor 1 reaches the terminal position p8 of the left reverse path P2c, which is the starting position of the terminal side turning path P2d, the automatic driving control unit 23F switches the driving mode of the tractor 1 to the arbitrarily set driving mode. When the tractor 1 reaches the terminal position p9 of the terminal side turning path P2d, the automatic driving control unit 23F returns the driving mode of the tractor 1 to the original driving mode before being switched to the arbitrarily set driving mode.

As a result, when generating the target route P, the user can arbitrarily set the driving mode of the tractor 1 to any of the front wheel acceleration mode, turning brake mode, and front wheel acceleration turning brake mode, and the target route generating unit 51B generates the target route P based on various arbitrarily set information including the arbitrarily set driving mode of the tractor 1. Therefore, when the tractor 1 turns according to the starting side turning route P2a or the terminal side turning route P2d of this target route P, the tractor 1 can be made to run in any of the front wheel acceleration state, turning inside braking state, and front wheel acceleration turning inside braking state according to the arbitrarily set driving mode of the tractor 1, and the turning radius of the tractor 1 can be reduced.

In other words, when generating the target path P, if any of the front wheel acceleration mode, turning brake mode, and front wheel acceleration turning brake mode is arbitrarily set as the driving mode of the tractor 1, the target path generating unit 51B can narrow the pair of direction change areas A2a in which the direction change path P2 is generated and widen the round trip driving area A2b in which the parallel path P1 is generated in the second division process described above. Then, the working area Aw can be widened accordingly, and the working efficiency can be improved when working with the tractor 1 automatically traveling.

In addition, the driving mode of the tractor 1 may be configured so that the target path generating unit 51B automatically sets the optimal driving mode to widen the working area Aw and improve work efficiency, rather than being arbitrarily set by the user as described above.

While the tractor 1 is automatically traveling along the second forward path (work path) P1c of the parallel path P1, the automatic travel control unit 23F performs a jump-out determination process to determine whether or not the tractor 1 is likely to jump out of the field by comparing the braking distance calculated based on the vehicle speed of the tractor 1 with the straight-line distance from the tractor 1 to the edge of the field contained in the detection information of the front obstacle sensor 86. If the automatic travel control unit 23F determines in the jump-out determination process that there is a possibility that the tractor 1 will jump out of the field, it performs an emergency stop process to instruct the gear change unit control unit 23B and the like to make an emergency stop of the tractor 1 to bring the tractor 1 to an emergency stop in order to prevent the tractor 1 from jumping out of the field.

In addition, while the tractor 1 is automatically traveling along the second forward path (work path) P1c of the parallel path P1, the automatic travel control unit 23F executes a vehicle speed limit control to limit the vehicle speed of the tractor 1 via the transmission unit control unit 23B so that the calculated braking distance is maintained shorter than the straight-line distance minus the set distance for preventing sudden departure.

This allows the second forward path (work path) P1c of the parallel path P1, in which the target vehicle speed is set to be faster than the direction change path P2 and the like, to be extended toward the edge of the field, while preventing a decrease in work efficiency caused by an emergency stop of the tractor 1 due to a determination in the jump-out determination process that there is a possibility that the tractor 1 will jump out of the field.

The target path P shown in FIG. 5 is merely an example, and the target path generating unit 51B can generate various target paths P suitable for the various conditions based on vehicle body information that differs depending on the model of the tractor 1 and the type of work implement, and field information such as the shape and size of the field A that differs depending on the field A.

[Another embodiment]
Another embodiment of the present invention will now be described.
The configurations of the respective alternative embodiments described below are not limited to being applied alone, but may also be applied in combination with the configurations of other alternative embodiments.

(1) The configuration of the work vehicle 1 can be modified in various ways.
For example, the work vehicle 1 may be configured as a semi-crawler type having left and right front wheels 10 and left and right crawlers instead of the left and right rear wheels 11 as a traveling device.
For example, the work vehicle 1 may be configured as a full crawler type in which the travelling device is provided with left and right crawlers instead of the left and right front wheels 10 and the left and right rear wheels 11 .
In these configurations, it is conceivable to set a predetermined length L4 for extending each second forward path (work path) P1c based on the distance from the rear end of each crawler to a work implement such as a rotary tiller 3.
For example, the work vehicle 1 may be configured to be electrically powered and equipped with an electric motor instead of an engine as the driving unit 14 .
For example, the work vehicle 1 may be configured as a hybrid vehicle having an engine and an electric motor as the driving unit 14 .

(2) The second distance L2 from the rear wheel (traveling device) 11 to the working device 3 may be set, for example, to the distance from the rear end of the contact surface of the rear wheel 11 to the working position of the working device 3.
In this case, the predetermined length L4 by which each second forward path (work path) P1c extends may be set to the same length as the second separation distance L2.

(3) As shown in FIG. 19 , in the second forward path (work path) P1c of each parallel path P1, a switching position p10 may be set at a position a braking distance La before the terminal position p4 on the second forward path P1c that corresponds to the target vehicle speed of the tractor 1 on the second forward path P1c, at which the path traveled by the tractor 1 is switched from the second forward path P1c to the intermediate reverse path P3 as the tractor 1 arrives.
Regarding this other embodiment (3), when the tractor 1 is to be switched between forward and reverse, a distance (braking distance for forward and reverse switching) is required to allow the tractor 1 to move from the start of the forward and reverse switching operation to the completion of the operation. Therefore, as illustrated in the above embodiment, if the route on which the tractor 1 travels is set to be switched from the second forward path P1c to the intermediate reverse path P3 when the tractor 1 reaches the terminal position p4 of the second forward path P1c, the tractor 1 will unnecessarily overrun from the terminal position p4 of the second forward path P1c by the braking distance. And since this overrun becomes longer as the vehicle speed of the tractor 1 becomes faster, the faster the target vehicle speed of the tractor 1 set for the second forward path P1c, the more the unnecessary overrun will lead to a decrease in work efficiency.
Therefore, in this alternative embodiment (3), as shown in FIG. 19, the aforementioned switching position p10 is set at a position that is the aforementioned braking distance before the terminal position p4 of the second forward path P1c. This makes it possible to prevent the tractor 1 from unnecessarily overrunning from the terminal position p4 of the second forward path P1c, and to avoid a decrease in work efficiency due to unnecessary overrunning.
Furthermore, this alternative embodiment (3) may be applied not only to the second forward path (work path) P1c of each parallel path P1, but also to the first forward path P1a and reverse path P1b of each parallel path P1 related to forward/reverse switching of the tractor 1, each intermediate reverse path P3, and the right forward path P2b and left reverse path P2c of each direction change path P2.

(4) However, simply setting the switching position p10 as exemplified in the above alternative embodiment (3) will not allow the automatic driving control unit 23F to switch the rotary tilling device 3 from an operating state to a non-operating state based on the switching of the route traveled by the tractor 1 from the second forward path P1c to the intermediate reverse path P3, as described above. Therefore, the faster the target vehicle speed on the second forward path P1c, the shorter the distance over which the tractor 1 operates by automatic driving on the second forward path P1c.
Therefore, in this alternative embodiment (4), in addition to the above-mentioned alternative embodiment (3), the automatic driving control unit 23F is configured to perform a target vehicle speed reduction process to reduce the target vehicle speed on the work route as the tractor 1 approaches the terminal position p4 of the second forward route P1c.
This allows the vehicle speed of the tractor 1 to be reduced as the tractor 1 approaches the terminal position p4 of the second forward path P1c, thereby shortening the above-mentioned braking distance La. As a result, the distance over which the tractor 1 works by automatic travel on each second forward path P1c can be increased.
Therefore, the working area Aw can be expanded when working with the tractor 1 traveling automatically, without causing a decrease in working efficiency due to overrunning from the second forward path P1c of the tractor 1, thereby improving working efficiency.

(5) In the above-mentioned alternative embodiment (4), in addition to the configuration exemplified in the alternative embodiment (3), a configuration was exemplified in which the automatic driving control unit 23F performs a target vehicle speed reduction process. However, instead of this, the automatic driving control unit 23F may be configured to calculate the braking time required from when the tractor 1 reaches the switching position p10 to when it switches to the reverse state based on the detection of the vehicle speed sensor 22E when the tractor 1 reaches the switching position p10, and to switch the driving state of the tractor 1 from a work driving state to a non-work driving state at the timing when the braking time has elapsed after the tractor 1 reaches the switching position p10, or at the timing shortly before the braking time has elapsed.
As a result, even after the tractor 1 reaches the switching position p10, the tractor 1 can be maintained in a working driving state until the braking time has elapsed or until just before the braking time has elapsed, thereby improving work efficiency by expanding the working area Aw.

(6) In addition to the configuration exemplified in the above-mentioned alternative embodiment (3), the automatic driving control unit 23F may be configured to start driving state switching control to switch the driving state of the tractor 1 from a work driving state to a non-work driving state based on the detection of the vehicle speed sensor 22E when the tractor 1 reaches the switching position p10, and in this driving state switching control, the driving state of the tractor 1 may be switched from the work driving state to the non-work driving state at the timing when it is detected that the tractor 1 has switched from a forward state to a reverse state based on the detection of the vehicle speed sensor 22E.
As a result, even after the tractor 1 reaches the switching position p10, the tractor 1 can be maintained in a working driving state until the tractor 1 actually starts reversing, thereby improving work efficiency by expanding the working area Aw.

<Notes on the invention>
A first characteristic configuration of the present invention is an automatic driving system for a work vehicle,
A positioning unit that measures the position of a work vehicle having a working implement at its rear that can be switched between a working state and a non-working state;
a target route generating unit that generates a target route that enables automatic travel of the work vehicle;
a control unit that automatically drives the work vehicle along the target route based on the positioning information of the positioning unit,
the target route includes a work route along which the work vehicle whose working device has been switched to the working state moves forward, and a turning route along which the work vehicle whose working device has been switched to the non-working state changes direction,
The target route generation unit generates the target route by route setting that connects a plurality of the work routes arranged in parallel at a predetermined interval to a travel order of the work vehicle via a plurality of the direction change routes, and
the target path generating unit extends a terminal end side of the work path by a predetermined length to generate the work path with a length such that the terminal end side enters the direction change path side by the predetermined length, and generates a first reverse path for moving the work vehicle backward from the terminal position of the extended work path to a starting position of the direction change path,
The control unit switches the working implement from the working state to the non-working state based on a change in the route on which the work vehicle travels from the working route to the first reverse route.

With this configuration, the work device can be maintained in a working state until the work vehicle passes the start position of the direction change path and reaches the end position of the extended work path. This makes it possible to bring the position of the work device (work end position) when the work vehicle reaches the end position of the work path closer to the start position of the direction change path, compared to when the end position of the work path is set to the start position of the direction change path.

As a result, for each work route, the unworked route that exists between the end position of the work performed by the work vehicle and the start position of the direction change route can be shortened by a predetermined length that extends the work route. This makes it possible to widen the work area in which the work vehicle can work while autonomously driving, and improves the work efficiency when working while autonomously driving the work vehicle.

Then, during the period from when the work vehicle reaches the end position of the work path until it changes direction according to the turning path, the work vehicle reverses from the end position of the work path to the start position of the turning path according to the first reverse path with the working device switched to a non-working state, so that the position and width of the turning area in which the work vehicle changes direction can be kept the same as before the end side of the work path was extended, and the work vehicle can be properly turned toward the start position of the next work path according to the turning path.

Therefore, the aforementioned unworked route can be shortened without changing the position and width of the turning area in which the work vehicle changes direction, improving work efficiency when working with an autonomous work vehicle.

The second characteristic configuration of the present invention is as follows:
The predetermined length is set to a length based on the distance between a traveling device provided on the work vehicle and the working device.

With this configuration, when a work vehicle whose working equipment has been switched to a non-working state travels backward along the first reverse path from the end position of the working path to the start position of the direction change path, it is possible to avoid the risk of the travel gear of the work vehicle entering an area already being worked on by the working equipment.

This makes it possible to shorten the unworked route described above while avoiding the risk of the work vehicle's travel device entering an already-worked area, thereby improving work efficiency when working with an autonomous work vehicle.

The third characteristic configuration of the present invention is as follows:
The target route generation unit sets the starting position of the work route so that the position of the work device when the work vehicle reaches the starting position of the work route after changing direction coincides with the position of the work device when the work vehicle reaches the terminal position of the work route after extension.

With this configuration, the position of the work device when the work vehicle reaches the start position of the work path and starts work travel (work start position) can be aligned with the position of the work device when the work vehicle reaches the end position of the work path and ends work travel (work end position). And, just like the end side of the work path, the position of the work device when the work vehicle reaches the start position of the work path (work start position) can be brought closer to the end position of the direction change path.

As a result, the unworked path between the end position of the direction change path and the start position of the work by the work vehicle can be shortened, which not only improves the work efficiency when working with an automatically navigating work vehicle, but also improves the work accuracy when working with an automatically navigating work vehicle.

The fourth characteristic configuration of the present invention is as follows:
The target path generating unit generates a non-work path extending from the end position of the direction change path beyond the starting position of the work path, and a second reverse path that reverses the work vehicle from the rear end position of the non-work path to the starting position of the work path.

According to this configuration, when the work vehicle moves from the end position of the direction change path to the start position of the work path, if the position or orientation of the work vehicle deviates beyond the allowable range with respect to the work path, the position and orientation of the work vehicle relative to the start position of the work path can be corrected to within the allowable range by moving the work vehicle forward on the non-work path and reversing the work vehicle on the second reverse path.

As a result, the position and orientation of the work vehicle relative to the work path can be adjusted appropriately when the work vehicle reaches the start position of the work path and begins work travel, improving the work accuracy when the work vehicle is traveling automatically.

The fifth characteristic configuration of the present invention is
The target route generation unit sets a switching position at a position a braking distance before the end position of the work route that corresponds to the target vehicle speed of the work vehicle on the work route, at which the route traveled by the work vehicle is switched from the work route to the first reverse route as the work vehicle arrives.

When switching between forward and reverse travel on a work vehicle, a distance is required to allow the work vehicle to move from when the forward/reverse travel switching operation is started until it is completed (braking distance for forward/reverse switching). For this reason, for example, if the route on which the work vehicle travels is set to switch from the work route to the first reverse route when the work vehicle reaches the end position of the work route, the work vehicle will unnecessarily overrun from the end position of the work route by the braking distance. And since this overrun becomes longer the faster the work vehicle speed is, the faster the target vehicle speed of the work vehicle set for the work route is, the more likely it is that unnecessary overrun will lead to reduced work efficiency.

Therefore, in this configuration, the switching position is set at a position that is the braking distance before the end position of the work path, which makes it possible to prevent the work vehicle from unnecessarily overrunning the end position of the work path, and avoids a decrease in work efficiency due to unnecessary overruns.

The sixth characteristic configuration of the present invention is
The control unit reduces the target vehicle speed as the work vehicle approaches an end position of the work path.

As described above, the control unit switches the working device from a working state to a non-working state based on the switching of the route traveled by the work vehicle from the working route to the first reverse route. Therefore, if the switching position is set to a position that is a braking distance before the end position of the working route as in the fifth characteristic configuration described above, the faster the target vehicle speed on the working route, the shorter the distance that the work vehicle will work by automatic travel on the working route.

Therefore, in this configuration, in addition to the fifth characteristic configuration described above, the control unit reduces the target vehicle speed on the work path as the work vehicle approaches the end position of the work path.

This allows the work vehicle's speed to be reduced as the work vehicle approaches the end position of the work route, shortening the braking distance mentioned above. As a result, the distance that the work vehicle works by autonomous driving on each work route can be increased.

This makes it possible to improve work efficiency when working with an automatically driven work vehicle, without causing a decrease in work efficiency due to the work vehicle overrunning the work path.

1 Work vehicle 3 Work device 11 Travel device 23 Control unit 42 Positioning unit 51B Target path generation section L2 Separation distance L4 Predetermined length La Braking distance P Target path P1a Non-work path P1b Second reverse path P1c Work path P2 Direction change path P3 First reverse path p2 Rear end position p3 of non-work path Start position p4 of work path Terminal position p5 of work path Start position p9 of direction change path Terminal position p10 of direction change path Switching position

Claims (2)

An automatic driving method for a work vehicle equipped with a work device at a rear portion, the work device being switchable between a working state and a non-working state, comprising:
After the work vehicle has been turned, the work vehicle is caused to travel forward until it passes a next work start position, and after the work vehicle has passed the work start position, the work vehicle is caused to travel backward, and after the work vehicle has been traveled backward, the working device is switched to the work state.
Automated driving method. An automatic driving system including a control unit that automatically drives a work vehicle having a working device at a rear portion thereof that can be switched between a working state and a non-working state,
The control unit
After the work vehicle has been turned, the work vehicle is caused to travel forward until it passes a next work start position, and after the work vehicle has passed the work start position, the work vehicle is caused to travel backward, and after the work vehicle has been traveled backward, the working device is switched to the work state.
Autonomous driving system.