Autopilot System

Abstract

To provide an automatic steering system by which accuracy in entry to a next traveling route is improved in travel for entering the next traveling route after leaving a previous traveling route.SOLUTION: An automatic steering system for an automatic traveling work vehicle which shifts from a previous traveling route Lf to a next traveling route Ln through turning travel includes: a start steering control unit which sets a start steering degree as a turning steering degree for start turning travel in turning travel; and a final steering control unit which sets a final steering degree as a turning steering degree for final turning travel to be performed when a length from a vehicle body 1 to the next travel route Ln reaches a predetermined approach length D1 after the end of the start turning travel based on the start steering degree or when a length from the previous travel route Lf to the vehicle body 1 reaches a predetermined separation length D2.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to an automatic steering system for an automatic traveling vehicle that transitions from a previous traveling route to a next traveling route via turning. [Background technology]

[0002] An autonomous work vehicle performs autonomous driving using its own position calculated using satellite positioning and other methods, and a driving route set for the work site. For example, an autonomous work vehicle deployed in a farm field drives along linear driving routes that extend in parallel and are connected by U-turn driving for field work. In this case, the optimal automatic steering for U-turn driving, which transitions from a linear previous driving route to a next driving route, must take into account the turning speed (time required for turning), turning space (space required for turning), turning accuracy (accuracy of reaching the next driving route), and smooth turning trajectory (without disturbing the work site).

[0003] In the automatic steering system according to Patent Document 1, the first turning maneuver (initial turning maneuver) to leave the previous driving path is performed at a preset steering angle, the second turning maneuver (final turning maneuver) to enter the next driving path is performed along a preset final turning circle, and the intermediate maneuver between the first turning maneuver and the second turning maneuver is performed along a tangent drawn from the vehicle body to the final turning circle.

[0004] In the automatic steering system according to Patent Document 2, a preset starting turning path is used for leaving the previous driving path, and a preset final turning path is used for entering the next driving path, and the turning radius of the starting turning path is larger than the turning radius of the final turning path. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2018-185671 A [Patent Document 2] JP 2020-031593 A Summary of the Invention [Problem to be solved by the invention]

[0006] In the turning travel of Patent Document 1 and Patent Document 2, if the start point of the final turning path that guides the vehicle to the next traveling path is not accurately reached, hunting occurs in the steering control that steers the vehicle along the final turning path, causing the vehicle to not smoothly reach the next traveling path. If the vehicle ends traveling along the final turning path in an overshoot state in the turning control, the vehicle body will slip sideways beyond the next traveling path, and if the vehicle ends traveling along the final turning path in an undershoot state, the vehicle body will slip sideways to the near side of the next traveling path. Furthermore, if hunting occurs in the turning control, the field will be significantly damaged.

[0007] An object of the present invention is to provide an automatic steering system that improves the accuracy of entering a next travel path when leaving a previous travel path and entering a next travel path. [Means for solving the problem]

[0008] The automatic steering system for an automatic traveling vehicle for transitioning from a previous traveling route to a next traveling route via a turning travel according to the present invention sets a starting steering degree as a turning steering degree of a starting turning travel in the turning travel. and perform non-path following control. an initial steering control unit, after the initial turning travel by the initial steering degree is completed, a distance from the vehicle body to the next travel route is Pre-recorded When a predetermined approach distance is reached, or when the distance from the previous travel path to the vehicle body is Pre-recorded When the specified distance is reached a distance determination unit that outputs a final turning start command; In response to the above, a final steering angle is set as the turning steering angle of the final turning travel of the vehicle body toward the next travel route. do Final turning steering control Non-path following control Final steering control unit and a path following steering unit that performs path following control so that the vehicle body travels along a target travel path set by a travel path setting unit. When travel on the previous travel path by the path following steering unit is completed, the steering control is switched to the start steering control unit, and when the final turning steering control by the final steering control unit is completed, the steering control is switched to the path following steering unit. The steering degree means a steering angle when the steering mechanism is a steering wheel, and means a speed difference between the left and right crawlers when the steering mechanism is a crawler. Of course, the steering degree may be a turning radius.

[0009] According to this configuration, the turning travel for transitioning from the previous travel path to the next travel path is composed of a starting turning travel, which is the first turning travel, and a final turning travel, which is the turning travel for entering the next travel path. The start of the final turning travel is performed based on the distance from the vehicle body to the next travel path, or the distance from the previous travel path to the vehicle body. The final steering angle used in this final turning travel can be calculated in advance based on the distance from the vehicle body to the next travel path. For the travel from the end of the starting turning travel to the start of the final turning travel, a highly accurate steering control such as setting the final turning travel start point as a target point is not required. When the positional relationship between the vehicle body and the next travel path becomes a predetermined relationship, the vehicle body is steered toward the next travel path. For example, if the vehicle body is configured to be steered toward the next travel path at a predetermined steering angle when the positional relationship between the vehicle body and the next travel path becomes a predetermined relationship, a complex turning control algorithm is not required. In other words, the vehicle always starts the final turning run with a preset positional relationship to the next running route, so the accuracy of entry into the next running route is stable. If the vehicle is a rice transplanter, the stable accuracy of entry into the next running route ensures accurate seedling planting position, which ultimately leads to increased yields.

[0010] A work travel path pattern frequently used in an automatic traveling work vehicle, particularly a work vehicle performing field work, is a pattern in which a plurality of linearly extending travel paths are connected by a 180-degree turn. The 180-degree turn is composed of two 90-degree turns. In one embodiment for suitably applying the present invention to such a 180-degree turn, the previous travel path and the next travel path are target travel paths extending parallel to each other, the turn is a 180-degree turn, and the start steering control unit shifts the steering degree from the start steering degree to a neutral steering degree before or when the change in the direction of the vehicle body in the start turning reaches 90 degrees. In this configuration, when the interval between the previous travel path and the next travel path is long, when the change in the direction of the vehicle body in the start turning reaches approximately 90 degrees, preferably close to 90 degrees, the steering degree starts to be returned to the neutral steering degree, and the vehicle continues to travel straight until the start timing of the final turning comes. Of course, the steering angle may be gradually returned to the neutral steering angle well before the heading change reaches 90 degrees. If the interval between the previous driving path and the next driving path is short and the timing to start the final turning comes before the heading change of the vehicle body reaches 90 degrees in the initial turning, the final turning starts at that point. In either case, the final turning starts with a preset positional relationship with the next driving path, so the accuracy of entry into the next driving path is stabilized.

[0011] In an ideal case, even if the vehicle body has not reached the start point of the next travel path at the end of the final turning, if the vehicle body coincides with the extension line of the next travel path, the vehicle can reach the next travel path by simply moving straight. For this reason, in one preferred embodiment of the present invention, the predetermined approach distance or the predetermined departure distance is set so that the orientation of the vehicle body coincides with the extension line of the next travel path by the final turning using the final steering degree. In this configuration, a deviation in the distance to the start point of the next travel path on the extension line of the next travel path at the end of the final turning is permitted, and the turning control only suppresses lateral deviation with respect to the extension line of the next travel path, so the control burden is lighter than steering control along a turning circle.

[0012] Since the coordinate position of the target travel route for automatic driving is stored in advance, the distance from the vehicle body to the previous travel route or the next travel route in a direction perpendicular to the extension direction of the previous travel route can be easily obtained using the coordinate position of the vehicle body. The coordinate position of the vehicle body can be obtained using satellite positioning technology or inertial navigation technology used for automatic driving. Therefore, in one preferred embodiment of the present invention, the predetermined approach distance or the predetermined departure distance is the distance from the vehicle body to the next travel route in a direction perpendicular to the extension direction of the next travel route or the distance from the vehicle body to the previous travel route in a direction perpendicular to the extension direction of the previous travel route.

[0013] The predetermined approach distance or predetermined departure distance for accurately reaching the next travel path may vary depending on the state of the travelling equipment such as crawlers or wheels and the state of the work site. In order to deal with such variations, in one preferred embodiment of the present invention, a distance adjustment unit is provided that adjusts the predetermined approach distance or the predetermined departure distance, and the distance adjustment unit adjusts the predetermined approach distance or the predetermined departure distance based on at least one of the minimum turning radius, turning speed, working width, and ground condition of the work site. This allows accurate turning travel to be achieved regardless of the state of the travelling equipment of the work vehicle or the state of the work site.

[0014] If the steering degree is maximized, the turning space is reduced and the turning travel time is shortened. For this reason, in one preferred embodiment of the present invention, the initial steering degree is the maximum steering degree, and in another preferred embodiment, the final steering degree is the maximum steering degree. Of course, both the initial steering degree and the final steering degree may be the maximum steering degree.

[0015] In addition to the above-mentioned turning steering control (steering mode), the autonomous driving work vehicle can be equipped with various turning modes. As other turning modes, there are turning modes that realize turning steering control according to the above-mentioned Patent Document 1 and Patent Document 2. Furthermore, a turning mode that realizes turning steering control called MPC (Model Predictive Control), which is highly accurate but has a large control burden, can also be used. In order to effectively utilize the advantages and disadvantages of these turning steering controls, one of the preferred embodiments of the present invention is provided with a first turning mode steering unit that performs a first turning mode, which is turning steering based on the start steering control unit and the final steering control unit and a predetermined turning speed, a second turning mode steering unit that controls the turning steering angle more finely than the first turning mode steering unit and performs a second turning mode, which is turning steering at a slower turning speed than the first turning mode steering unit, and a turning mode selection unit that selects either the first turning mode or the second turning mode. [Brief description of the drawings]

[0016] [Figure 1] FIG. 1 is a side view of a rice transplanter equipped with an automatic steering system. [Diagram 2] FIG. 4 is a schematic diagram illustrating power transmission from the engine to the planting mechanism. [Diagram 3] FIG. 2 is a schematic diagram illustrating a driving route for automatic driving of the rice transplanter. [Figure 4] FIG. 2 is a schematic diagram illustrating turning travel from a start turning travel to a final turning travel. [Diagram 5] FIG. 2 is a functional block diagram showing a control system of the rice transplanter. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Hereinafter, as one embodiment of an autonomous working vehicle equipped with the automatic steering system of the present invention, a rice transplanter traveling in a field will be described as an example. In this embodiment, unless otherwise specified, "front" (the direction of arrow F shown in FIG. 1) means the front in the fore-and-aft direction (traveling direction) of the machine body, and "rear" (the direction of arrow B shown in FIG. 1) means the rear in the fore-and-aft direction (traveling direction) of the machine body. In addition, the left-right direction or lateral direction means the left-right direction of the machine body (machine body width direction) perpendicular to the fore-and-aft direction of the machine body, "left" means the direction toward the front of the paper in FIG. 1, and "right" means the direction toward the back of the paper in FIG. 1.

[0018] [Overall structure] As shown in Fig. 1, the rice transplanter is equipped with a riding type four-wheel drive vehicle body 1. The vehicle body 1 is equipped with a parallel quadruple link type link mechanism 13 connected to the rear of the vehicle body 1 so as to be able to rise and fall and swing, a hydraulic lifting cylinder 13a that drives the link mechanism 13 to swing, a seedling planting device 3A connected to the rear end region of the link mechanism 13 so as to be able to roll, and a fertilizer applicator 3B installed from the rear end region of the vehicle body 1 to the seedling planting device 3A. In this embodiment, the seedling planting device 3A and the fertilizer applicator 3B are the working device 3 provided in the autonomous working vehicle of the present invention.

[0019] The vehicle body 1 includes a wheeled traveling device 12, an engine 2A, and a hydraulic continuously variable transmission 2B that serves as a main transmission. The continuously variable transmission 2B is, for example, a hydrostatic transmission (HST), and changes the speed of the power (rotation speed) output from the engine 2A by adjusting the angles of a motor swash plate and a pump swash plate. The traveling device 12 has left and right front wheels 12A that function as steering wheels for changing the vehicle direction, and left and right rear wheels 12B that cannot be steered.

[0020] As shown in Fig. 1, the vehicle body 1 is provided with a driver's section 14 in its rear side area. The driver's section 14 is provided with a steering wheel 10 for steering the front wheels, a main speed change lever 7A for adjusting the vehicle speed by changing the speed of the continuously variable transmission 2B, an auxiliary speed change lever 7B for enabling the auxiliary speed change operation, an operation lever 11 for operating the seedling planting device 3A to raise and lower it, a driver's seat 16 for passengers (driver, worker, manager), etc. Furthermore, in front of the driver's section 14, a spare seedling storage device 17A for storing spare seedlings is supported on a spare seedling support frame 17.

[0021] The steering wheel 10 is connected to the front wheels 12A via a steering mechanism (not shown), and the steering angle of the front wheels 12A is adjusted by rotating the steering wheel 10. A steering motor M1 is connected to the steering mechanism, and during automatic steering, the steering motor M1 operates based on a steering signal to adjust the steering angle (steering degree) of the front wheels 12A. In addition, a gear shift motor M2 for automatically operating the main gear shift lever 7A is also provided, and during automatic driving, the gear shift position of the continuously variable transmission 2B is adjusted by the gear shift motor M2 operating based on a gear shift signal.

[0022] As shown in FIG. 2, the seedling planting device 3A is illustrated as an 8-row planting type as an example, but may be of other types such as 6-row planting type or 10-row planting type. Power from the engine 2A is distributed to each planting mechanism 22 via the planting clutch C0 and each row clutch EC. The planting clutch C0 switches the drive state of the seedling planting device 3A by turning on and off the power transmission from the engine 2A. The each row clutch EC is configured to be able to select the start and stop of work by the seedling planting device 3A for every two rows. By controlling the each row clutch, the planting type can be changed to 2-row, 4-row, 6-row, or 8-row planting.

[0023] As shown in FIG. 1 and FIG. 2, the seedling planting device 3A includes a seedling platform 21, a planting mechanism 22, and the like. The seedling platform 21 is a platform on which eight rows of mat-shaped seedlings are placed. The seedling platform 21 moves back and forth in the left and right direction with a constant stroke corresponding to the left and right width of the mat-shaped seedlings, and each time the seedling platform 21 reaches the left and right stroke ends, each mat-shaped seedling on the seedling platform 21 is vertically fed at a predetermined pitch toward the lower end of the seedling platform 21. The eight planting mechanisms 22 are of a rotary type and are arranged in the left and right direction at a constant interval corresponding to the spacing between the planting rows. Each planting mechanism 22 receives power from the engine 2A when the planting clutch C0 is shifted to a transmission state, and cuts one seedling (a seedling to be planted) from the lower end of each mat-shaped seedling placed on the seedling platform 21 and plants it in the muddy soil after leveling. As a result, when the seedling planting device 3A is in an operating state, the seedlings can be taken out of the mat-like seedlings placed on the seedling-mounting table 21 and planted in the muddy part of the paddy field.

[0024] The fertilizer application device 3B has a hopper 25 that stores granular or powdered fertilizer (chemicals or other agricultural materials), a delivery mechanism 26 that delivers the fertilizer from the hopper 25, and a fertilizer application hose 28 that transports the fertilizer delivered by the delivery mechanism 26 and discharges the fertilizer into the field. The fertilizer stored in the hopper 25 is delivered in predetermined amounts by the delivery mechanism 26 and sent to the fertilizer application hose 28, transported inside the fertilizer application hose 28 by the delivery wind of the blower 27, and discharged into the field from a furrow former 29. In this way, the fertilizer application device 3B supplies fertilizer to the field.

[0025] The furrow formers 29 are mounted on the ground leveling floats 15. Each furrow former 29 rises and falls together with each ground leveling float 15, and forms a fertilizer furrow in the muddy soil of the paddy field and guides fertilizer into the furrow during work travel in which each ground leveling float 15 touches the ground. The ground leveling floats 15 function as ground contact sensors.

[0026] The communication terminal 9, which is removably attached to the driving unit 14, is composed of, for example, a tablet computer, and can output various information to the operator as visual information and audio information, and can also accept input of various information. The communication terminal 9 is connected to the control system of the rice transplanter wirelessly or via a wire so as to be able to exchange data. Various functions for automatic driving are installed in the communication terminal 9, and it is possible to remotely control the rice transplanter from a position away from the rice transplanter, for example.

[0027] The rice transplanter further includes a positioning unit 8. The positioning unit 8 outputs positioning data for calculating the position and orientation of the vehicle body 1. The positioning unit 8 includes a satellite positioning module 8A that receives radio waves from satellites of the Global Navigation Satellite System (GNSS), and an inertial measurement module 8B that detects the inclination and acceleration of the three axes of the vehicle body 1. The positioning unit 8 is supported on the upper part of the spare seedling support frame 17.

[0028] [Route] The autonomous driving of the rice transplanter to plant seedlings in a field is described below with reference to Figure 3.

[0029] The rice transplanter in this embodiment can selectively be driven manually or automatically. In the manual driving mode, the driver manually (including remote control) operates the steering wheel 10, the main shift lever 7A, the sub-shift lever 7B, the work operation lever 11, etc. to drive the rice transplanter for work. In the automatic driving mode, the rice transplanter drives and works under automatic control along a preset target driving route.

[0030] When the rice transplanter is planting seedlings, the operator first manually drives the rice transplanter around the periphery (edge) of the field without performing any work. As shown in Fig. 3, this circular drive generates the periphery shape of the field (field map), and the field is divided into an outer periphery area OA and an inner area IA.

[0031] When the field map is generated, a driving route that the rice transplanter uses for automatic driving is generated. In the inner area IA, a plurality of straight-line driving routes (hereinafter, these are referred to as straight-line driving routes, but are not necessarily limited to straight lines) that extend substantially parallel to one side of the field are generated. These straight-line driving routes are used by the rice transplanter to travel throughout the entire inner area IA, and automatic steering during automatic driving is performed with these straight-line driving routes as the target driving route. The straight-line driving routes are connected by a U-shaped turning driving route (effectively a 180-degree turning route). Automatic driving control is performed, which consists of automatic steering and automatic gear shifting.

[0032] In the outer peripheral area OA, one or more circular travel routes are generated that travel around the outer peripheral area OA along the outer periphery (edge) of the field. For example, in the example of Fig. 3, the circular travel routes consist of two circular travel routes, an inner one and an outer one. The inner and outer circular travel routes can also be automatically traveled, but either one or both of them may be manually traveled.

[0033] [Turning Steering] FIG. 4 shows an example of a 180-degree turning travel path TL for transitioning from a previous travel path Lf, which is a straight-line travel path used in the immediately preceding work travel, to a next travel path Ln, which is a straight-line travel path used in the next work travel.

[0034] This 180-degree turning travel path TL is composed of a starting turning travel path TL1, a final turning travel path TL2, and an intermediate travel path TL0. In Fig. 4, the distance between the previous travel path Lf and the next travel path Ln is indicated by D. Furthermore, the direction of the straight travel path, which is the extension direction of the previous travel path Lf and the next travel path Ln, is the vertical direction AZ1, and the direction perpendicular to the direction of the straight travel path is the horizontal direction AZ2.

[0035] The start turning travel path TL1 indicates a start turning travel of 90 degrees from the end point of the previous travel path Lf or an extension line of the previous travel path Lf toward the next travel path Ln, and the turning steering angle at that time is set in advance as the start steering angle, but the maximum steering angle is preferable. The start turning travel ends when the vehicle body direction becomes the lateral direction AZ2 (when the vehicle body 1 turns 90 degrees), the steering angle is returned to the neutral steering angle (neutral steering degree), and the intermediate travel (straight travel) indicated by the intermediate travel path TL0 starts.

[0036] In the intermediate travel, when the distance from the vehicle body 1 to the next travel path Ln reaches a predetermined approach distance D1, or when the distance from the previous travel path Lf to the vehicle body 1 reaches a predetermined departure distance D2, the final turning travel indicated by the final turning travel path TL2 is started. In this embodiment, the predetermined approach distance D1 is the distance from the vehicle body 1 to the next travel path Ln in the lateral direction AZ2, which is a direction perpendicular to the extension direction of the next travel path Ln. The predetermined departure distance D2 is the distance from the vehicle body 1 to the previous travel path Lf in the lateral direction AZ2, which is a direction perpendicular to the extension direction of the previous travel path Lf. Note that the intermediate travel is omitted when the interval D between the previous travel path Lf and the next travel path Ln is short.

[0037] The final steering angle, which is the turning steering angle in the final turning, is set in advance, but the maximum steering angle is preferable. The final turning ends when the orientation of the vehicle body 1 becomes the vertical direction AZ1. If the final turning is performed ideally, the vehicle body 1 is located on the previous driving path Lf or an extension line of the previous driving path Lf at the end of the final turning. If the position of the vehicle body 1 deviates from the previous driving path Lf or an extension line of the previous driving path Lf in the lateral direction AZ2, automatic steering control for the straight driving path is activated to correct the deviation. In other words, when the final turning ends, a route search is performed for the next driving path Ln, the next driving path Ln is captured, and automatic steering is performed with this as the target driving path.

[0038] The final steering angle used in the final turning run is set in advance, with the maximum steering angle being preferred. The predetermined approach distance D1 or the predetermined departure distance D2 is statistically calculated and set by repeating experiments and simulations using an actual vehicle, with the goal that the orientation of the vehicle body 1 will coincide with the longitudinal direction AZ1, that is, with the extension direction line of the next travel path n, by the final turning run using the final steering angle. Of course, the predetermined approach distance D1 or the predetermined departure distance D2 can be adjusted to deal with the field conditions at each time and the aging of the steering system including the traveling device 12. Similarly, the start steering angle and the final steering angle can also be adjusted.

[0039] A control block diagram of the control system of this rice transplanter is shown in Figure 5. The control system of the rice transplanter consists of a control unit 100 that controls various operations of the rice transplanter, and a communication terminal 9 that can exchange data with the control unit 100. Signals from a positioning unit 8, a manual operation tool sensor group 31, a travel sensor group 32, and a work sensor group 33 are input to the control unit 100. Control signals from the control unit 100 are output to the travel equipment group 1A and the work equipment group 1B.

[0040] The control unit 100 acquires positioning data for calculating the position and orientation (forward / rearward orientation of the vehicle body) of the vehicle body 1 from the satellite positioning module 8A of the positioning unit 8, and acquires inertial measurement data regarding the inclination and acceleration of the three axes of the vehicle body 1 from the inertial measurement module 8B.

[0041] The traveling equipment group 1A includes, for example, a steering motor M1 and a gear shift motor M2, and based on a control signal from the control unit 100, the steering motor M1 is controlled to adjust the steering angle, and the gear shift motor M2 is controlled to adjust the vehicle speed.

[0042] The work equipment group 1B includes, for example, a lifting cylinder 13a that adjusts the lifting and lowering of the seedling planting device 3A, a seedling harvesting amount adjustment device that adjusts the amount of seedlings harvested by the planting mechanism 22, a feed amount adjustment device that changes the amount of fertilizer fed by the feed mechanism 26, and on / off control devices for the planting clutch C0 and the individual row clutch EC.

[0043] The manual operation tool sensor group 31 includes sensors and switches that detect the operation state of various manual operation tools. The travel sensor group 32 includes various sensors that detect the state of the steering angle, vehicle speed, engine RPM, etc., and the corresponding set values. The work sensor group 33 includes various sensors that detect the state of the link mechanism 13, the seedling planting device 3A, and the fertilizer application device 3B.

[0044] The control unit 100 includes a driving control unit 6, an operation control unit 51, a vehicle body position calculation unit 52, a driving route setting unit 53, and a driving trajectory management unit .

[0045] The vehicle body position calculation unit 52 calculates the map coordinates (vehicle body position) of the vehicle body 1 based on the satellite positioning data and inertial navigation data successively transmitted from the positioning unit 8. The map coordinates may be not only latitude and longitude but also coordinates in a field coordinate system or a specific coordinate system.

[0046] In this embodiment, the communication terminal 9 is equipped with a touch panel IF90, a field information storage unit 91, a travel route map generation unit 92, a travel route generation unit 93, a remote control unit 94, etc. The touch panel IF90 is a graphic interface, and has a function of displaying and inputting information through a touch panel equipped in the communication terminal 9. Therefore, this communication terminal 9 can function as an input / output interface for information and data of the control unit 100.

[0047] The field information storage unit 91 stores information about the field, such as the entrance (exit) positions of the field and positions where seedlings and fertilizer can be replenished. The travel route map generation unit 92 calculates the external dimensions of the field based on a travel trajectory obtained by making the vehicle body 1 travel around the outermost periphery of the outer periphery area OA (see FIG. 3) of the field, i.e., along the boundary line with the bank. The travel route generation unit 93 divides the field into an outer periphery area OA and an inner area IA based on the external dimensions of the field, and generates a travel route for automatic travel. As shown in FIG. 3, the travel route consists of a round travel route for traveling in the outer periphery area OA and a straight travel route for traveling in the central area. The generated travel route is sent to the control unit 100.

[0048] The remote control unit 94 has a program that causes the communication terminal 9 to function as a remote control for operating the rice transplanter. When the remote control unit 94 operates, the manager can remotely operate the rice transplanter using hardware switches attached to the communication terminal 9 or software switches displayed on the touch panel of the communication terminal 9.

[0049] The driving route setting unit 53 built in the control unit 100 receives and manages the driving route generated by the driving route generation unit 93 from the communication terminal 9, and sequentially sets the driving route that is to be the target for path following steering control as the target driving route.

[0050] The travel locus management unit 54 generates and stores a travel locus of the vehicle body 1 based on the vehicle body position calculated by the vehicle body position calculation unit 52.

[0051] In automatic driving, the work control unit 51 automatically controls the work equipment group 1B based on a program provided in advance, and in manual driving, it controls the work equipment group 1B based on the operation of the driver.

[0052] The travel control unit 6 is equipped with an automatic travel control unit 6A, a manual travel control unit 6B, and a control management unit 6C. This rice transplanter can be switched between an automatic travel mode for automatic travel and a manual travel mode for manual travel. The control management unit 6C selects either the automatic travel mode or the manual travel mode based on a signal from a manual operation tool sensor (one of a manual operation tool sensor group) that detects the state of a travel mode switching operation tool (not shown) or a switching signal that is generated by the control unit 100.

[0053] The manual driving control unit 6B operating in the manual driving mode controls the steering motor M1 based on the amount of operation of the steering wheel 10, and also controls the gear shift operation motor M2 based on the operation of manual operating tools such as the main gear shift lever 7A and the sub gear shift lever 7B.

[0054] The automatic driving control unit 6A operating in the automatic driving mode includes a path following steering unit 61 and an automatic turning steering unit 62. The path following steering unit 61 performs path following control so that the vehicle body 1 travels along the target driving route set in the driving route setting unit 53. In the path following control, the vehicle body position calculated by the vehicle body position calculation unit 52 is used to calculate the position deviation (lateral deviation from the target driving route) and the orientation deviation (deviation angle of the vehicle body orientation from the orientation of the target driving route) of the vehicle body 1 with respect to the target driving route, and steering control is performed so that the position deviation and orientation deviation are reduced.

[0055] The automatic turning steering unit 62 performs steering control for turning to change the direction of the vehicle body 1, for example, turning 90 degrees or 180 degrees. In particular, the automatic turning steering unit 62 has a start steering control unit 621, a final steering control unit 622, an intermediate steering control unit 623, a distance determination unit 624, a distance adjustment unit 625, and a turning mode selection unit 626 to perform turning that connects straight driving paths as described with reference to FIG.

[0056] With reference to FIG. 4, the function of the automatic turning steering unit 62 in turning travel connecting straight travel routes (previous travel route Lf and next travel route Ln) will be described. The turning travel here is a 180-degree turning travel. The start steering control unit 621 controls the start turning travel for turning travel toward the next travel route Ln after the vehicle body 1 finishes traveling on the previous travel route Lf. At that time, the start steering degree is set as the turning steering degree for performing the start turning travel. This start turning travel is a 90-degree turn, and ends when the vehicle body orientation becomes the lateral direction AZ2 (when the orientation change of the vehicle body 1 reaches 90 degrees). When the start turning travel ends, the steering control is handed over to the intermediate steering control unit 623, which returns the steering angle to the neutral steering angle and causes the vehicle body 1 to travel in the lateral direction AZ2.

[0057] The distance determination unit 624 records a predetermined approach distance D1 or a predetermined departure distance D2, and when the distance in the lateral direction AZ2 from the vehicle body 1 to the next driving path Ln reaches the predetermined approach distance D1, or when the distance in the lateral direction AZ2 from the previous driving path Lf to the vehicle body 1 reaches the predetermined departure distance D2, a final turning start command is given to the final steering control unit 622.

[0058] The final steering control unit 622 controls the start turning travel for turning the vehicle body 1 toward the next travel route Ln in the longitudinal direction AZ1 in response to a final turning start command from the distance determination unit 624. At this time, the final steering degree is set as the turning steering degree for performing the final turning travel. The final turning travel by the final steering control unit 622 ends when the orientation of the vehicle body 1 coincides with or nearly coincides with the longitudinal direction AZ1.

[0059] The distance adjustment unit 625 adjusts the predetermined approach distance D1 or the predetermined departure distance D2 used in the distance determination unit 624. This adjustment may be performed automatically based on at least one of the turning performance, turning speed, and ground condition of the work site, or based on the lateral deviation of the vehicle body position with respect to the next travel route Ln at the end of the final turning run. Of course, the manager may adjust the distance using a dial switch or the like provided on the vehicle body 1, or the distance may be adjusted through the communication terminal 9 using the touch panel IF90 of the communication terminal 9.

[0060] In this embodiment, the initial steering angle and the final steering angle are set to the maximum steering angle, but can be changed to any steering angle.

[0061] When the final turning by the final steering control unit 622 is completed, the steering control is handed over to the path following steering unit 61. The path following steering unit 61 captures the next traveling path Ln or an extension line of the next traveling path Ln, and performs steering control so that the vehicle body 1 is on the next traveling path Ln or an extension line of the next traveling path Ln. If the path following steering unit 61 cannot capture the next traveling path Ln or an extension line of the next traveling path Ln, the vehicle is stopped.

[0062] In this embodiment, the automatic turning steering unit 62 also has a turning mode other than the turning mode (called the first turning mode) in which the start timing of the final turning is determined using the above-mentioned predetermined approach distance D1 or the predetermined departure distance D2. For example, a turning mode in which a 90-degree turn is performed at a predetermined steering angle in the start turning, and then a final turning is performed with the start point of the next traveling route Ln as the traveling target point can be used. Alternatively, the turning modes disclosed in Patent Document 1 and Patent Document 2 can be used. Furthermore, as a more accurate turning mode, a turning mode using MPC (model predictive control) can be used. The turning mode selection unit 626 registers such turning modes as the second turning mode, the third turning mode, and the further turning mode, and selects the turning mode to be executed from among them. This selection is performed automatically or manually. Furthermore, it is also possible to set the turning mode in advance depending on the turning location. In Figure 5, the functional unit that performs turning steering in the first turning mode is shown as first turning mode steering unit 62A, the functional unit that performs turning steering in the second turning mode is shown as second turning mode steering unit 62B, and the functional unit that performs turning steering in the third turning mode is shown as third turning mode steering unit 62C.

[0063] [Another embodiment] (1) In the above-described embodiment, a rice transplanter was cited as an example of an autonomous work vehicle equipped with the automatic steering system of the present invention. However, the present invention can also be applied to autonomous work vehicles such as field work machines such as seeding machines and harvesters, or grass cutters and land levelers. (2) In the above embodiment, a turning pattern is described in which the vehicle moves from the previous travel path Lf to the next travel path Ln via a 180-degree turning run, but the present invention can also be used for turning runs of other angles, for example, a turning pattern consisting of a 45-degree start turning run and a 45-degree final turning run. Furthermore, the turning angles of the start turning run and the final turning run may be different. (3) In the above embodiment, the traveling device 12 is a steering wheel type. However, it may be a crawler type. (4) The functional blocks described using FIG. 5 are just an example, and various modifications are possible, such as each functional unit being integrated with other functional units, each functional unit being divided into multiple functional units, or the control unit 100 being distributed into multiple control subunits.

[0064] In addition, the configurations disclosed in the above embodiments (including other embodiments, the same applies below) can be applied in combination with configurations disclosed in other embodiments, provided no contradiction arises. Furthermore, the embodiments disclosed in this specification are illustrative, and the embodiments of the present invention are not limited thereto, and can be appropriately modified within the scope that does not deviate from the purpose of the present invention. [Industrial Applicability]

[0065] The automatic steering system of the present invention can be applied to an automatic working vehicle that transitions from a previous driving route to a next driving route via turning. [Explanation of symbols]

[0066] 1: Body 3: Working equipment 8: Positioning unit 51: Work control section 52: Vehicle position calculation unit 53: Travel route setting unit 6: Driving control unit 6A: Automatic driving control unit 6B: Manual driving control unit 6C: Control Management Department 61: Path following steering unit 62: Automatic turning steering unit 62A: First turning mode steering section 62B: Second turning mode steering section 62C: 3rd turning mode steering section 621: Start steering control unit 622: Final steering control unit 623: Intermediate steering control unit 624: Distance determination unit 625: Distance adjustment section 626: Rotation mode selection section 9: Communication terminal 93: Route generation unit 94: Remote control unit 100: Control unit AZ1: Vertical orientation AZ2: Horizontal direction D1: Predetermined approach distance D2: Predetermined departure distance Lf: Previous route Ln: Next route OA: outer area TL0: Intermediate travel route TL1: Start turning path TL2: Final turning route

Claims

1. An automatic steering system for an automatic driving work vehicle that transitions from a previous driving route to a next driving route via a turning route, an initial steering control unit that sets an initial steering degree as a turning steering degree of an initial turning travel in the turning travel and performs non-path following control; a distance determination unit that outputs a final turning start command when a distance from the vehicle body to the next traveling path reaches a predetermined approach distance recorded in advance, or when a distance from the previous traveling path to the vehicle body reaches a predetermined departure distance recorded in advance, after the initial turning travel based on the initial steering degree is completed; a final steering control unit that, in response to the final turning start command, sets a final steering degree as the turning steering degree of the final turning travel in which the vehicle body moves toward the next travel path, and performs final turning steering control by the non-path following control; a route tracking steering unit that performs route tracking control so that the vehicle body travels along the target travel route set by the travel route setting unit, An automatic steering system in which, when driving along the previous driving path by the path following steering unit is completed, steering control is switched to the starting steering control unit, and when the final turning steering control by the final steering control unit is completed, the steering control is switched to the path following steering unit.

2. The previous travel path and the next travel path are the target travel paths extending parallel to each other, and the turning travel is a 180-degree turning travel, The automatic steering system according to claim 1, wherein the initial steering control unit transitions the steering degree from the initial steering degree to a neutral steering degree before the change in orientation of the vehicle body during the initial turning reaches 90 degrees or when the change reaches 90 degrees.

3. The automatic steering system according to claim 1 or 2, wherein the specified approach distance or the specified departure distance is set so that the orientation of the vehicle body coincides with the extension direction line of the next driving route by the final turning using the final steering angle.

4. An automatic steering system described in any one of claims 1 to 3, wherein the specified approach distance or the specified departure distance is a distance from the vehicle body to the next driving path in a direction perpendicular to the extension direction of the next driving path or a distance from the vehicle body to the previous driving path in a direction perpendicular to the extension direction of the previous driving path.

5. An automatic steering system as described in any one of claims 1 to 4, further comprising a distance adjustment unit that adjusts the specified approach distance or the specified departure distance, the distance adjustment unit adjusting the specified approach distance or the specified departure distance based on at least one of a minimum turning radius, a turning speed, a working width, and a ground condition of the working area.

6. The automatic steering system according to claim 1 , wherein at least one of the initial steering degree and the final steering degree is a maximum steering degree.

7. The automatic steering system according to any one of claims 1 to 6, further comprising: a first turning mode steering unit that performs a first turning mode, which is turning steering based on the initial steering control unit and the final steering control unit and a predetermined turning speed; a second turning mode steering unit that performs a second turning mode, which is turning steering that controls the turning steering angle more finely than the first turning mode steering unit and has a slower turning speed than the first turning mode steering unit; and a turning mode selection unit that selects either the first turning mode or the second turning mode.

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