Agricultural work vehicle

Abstract

To provide a farm working vehicle capable of avoiding the situation where a machine body comes to an emergency stop due to the machine body crossing the border, during a turning travel in the automatic travel.SOLUTION: A farm working vehicle includes: a machine body position calculation part 52 for calculating a machine body position which is the position of the machine body on a field surface bounded by a boundary object; a crossing-border prevention control part 57b for prohibiting the travel of the machine body crossing the boundary based on a boundary set to avoid contact between the machine body and the boundary object and the machine body position; a turning locus estimation part 57c for estimating a turning locus which is the locus of the machine body during a turning travel; and a turning time crossing-border determination part 57d for determining whether or not the machine body crosses the border in the actual turning travel based on the estimated turning locus.SELECTED DRAWING: Figure 7

Description

[[Technical Field]]

[0001] The present invention relates to an automatically drivable agricultural work vehicle that travels on a farm field bounded by boundary objects. [[Background Art]]

[0002] An agricultural work vehicle according to Patent Document 1 comprises: a measurement device that detects the position of a traveling vehicle body using a satellite positioning system; an automatic travel control unit that causes the traveling vehicle body to automatically travel along a set work travel line; and an automatic deceleration unit that stops the traveling vehicle body when the traveling vehicle body approaches a ridge edge line, which is a boundary line between a farm field surface and a ridge. [[Prior Art Documents]] [[Patent Documents]]

[0003] [[Patent Document 1]] Japanese Unexamined Patent Application Publication No. 2018-117559 [[Summary of the Invention]] [[Problem to be Solved by the Invention]]

[0004] In order to travel across an entire farm field bounded by boundary objects such as ridges, an agricultural work vehicle repeats forward traveling toward a boundary object and turning travel (direction change travel) performed when approaching the boundary object. In the case of turning travel, depending on the turning start timing, the road surface condition of the farm field, the vehicle speed during turning, and other factors, the vehicle body may turn along a turning trajectory different from the assumed turning trajectory. When an automatically traveling agricultural work vehicle such as that disclosed in Patent Document 1 performs turning travel near a boundary line, if the vehicle body turns closer to the boundary line than the assumed turning trajectory, the position of the vehicle body reaches the boundary line, and the vehicle body performs an emergency stop. When the vehicle body emergency stops during automatic travel, it is necessary to switch to manual operation and manually perform turning travel so as not to cross the boundary line. Such boundary-crossing avoidance turning travel is labor-intensive, which causes work delays.

[0005] Therefore, there is a demand for agricultural vehicles that can avoid situations where the vehicle crosses a boundary line during autonomous turning maneuvers, causing it to make an emergency stop. [Means for solving the problem]

[0006] The agricultural vehicle according to the present invention is an automatically navigable agricultural vehicle that travels in a field, and comprises a vehicle position calculation unit that calculates the vehicle position, which is the position of the vehicle in the field, and a turning boundary crossing determination unit that determines whether the vehicle crosses a boundary line during actual turning, and has a straight-line boundary crossing prevention mode and a turning boundary crossing prevention mode, in which the vehicle stops when the distance between the vehicle and the boundary line is within a predetermined distance, and in the turning boundary crossing prevention mode, the turning boundary crossing determination unit determines whether the vehicle crosses the boundary line based on the vehicle position and steering angle. death The driving path in the automatic driving includes a circular driving path and a round-trip driving path set inside the circular driving path, and in the circular driving path, only the straight-ahead crossing prevention mode is enabled among the straight-ahead crossing prevention mode and the turning crossing prevention mode, and in the round-trip driving path, both the straight-ahead crossing prevention mode and the turning crossing prevention mode are enabled. ru. Furthermore, the agricultural vehicle according to the present invention is capable of automatically traveling on a field area bounded by boundary objects, and includes: a vehicle position calculation unit that calculates the vehicle position, which is the position of the vehicle on the field area; a boundary crossing prevention control unit that prohibits the vehicle from traveling beyond the boundary line, based on the boundary line set to avoid contact between the vehicle and the boundary object and the vehicle position; a turning trajectory estimation unit that estimates the turning trajectory, which is the trajectory of the vehicle when it turns; and a turning boundary crossing determination unit that determines whether the vehicle crosses the boundary line during actual turning based on the estimated turning trajectory.

[0007] In this configuration, when the aircraft turns, the turning trajectory is estimated in advance, and based on the estimated turning trajectory, it is determined whether the aircraft will cross the boundary line during the actual turning. The estimation of the turning trajectory by the turning trajectory estimation unit and the determination by the boundary crossing determination unit during turning can be performed either before the actual turning, during the actual turning, or both. If the determination result is that the boundary line will be crossed, a recovery measure is taken before the aircraft's movement is prohibited by the boundary crossing prevention control unit. This recovery process can be performed manually or automatically. Such a recovery measure is not only easier to perform than one performed after the aircraft's movement is prohibited by the boundary crossing prevention control unit, but it also has the advantage of reducing time loss.

[0008] The recovery process involves canceling the planned turning maneuver before the aircraft crosses the boundary line and performing a boundary crossing avoidance turning maneuver by moving the starting point of the turning maneuver or changing the turning radius. Therefore, in one preferred embodiment of the present invention, if the boundary crossing determination unit during turning determines that the aircraft will cross the boundary line, a boundary crossing avoidance turning maneuver is performed.

[0009] One example of boundary crossing avoidance turning is that if the steering angle of the planned turning is less than the maximum steering angle, the turning trajectory using the maximum steering angle is estimated, and if the result of the boundary crossing determination during turning based on the estimated turning trajectory is good, the boundary can be avoided by turning at the maximum steering angle. Therefore, in one preferred embodiment of the present invention, the boundary crossing avoidance turning includes turning at the maximum steering angle. To more reliably avoid boundary crossing, a direction change driving using reverse (a type of turning driving), generally called counter-rotation driving, is preferable. For this reason, in one preferred embodiment of the present invention, reverse is included in the boundary crossing avoidance turning driving.

[0010] In many agricultural operations performed by agricultural vehicles in fields, the field area to be worked on is divided into an outer perimeter area and an inner area located inside the outer perimeter area. Work in the inner area is performed by repeatedly alternating between straight-line driving for work and turning driving (mainly U-turns) where no work is performed for changing direction. For this reason, it is not uncommon for the vehicle to be controlled to temporarily stop before transitioning from straight-line driving in the inner area to turning driving in the outer perimeter area. To utilize such control, in one preferred embodiment of the present invention, the field area is divided into an outer perimeter area along the boundary line and an inner area located inside the outer perimeter area. Automatic driving work in the inner area is performed by repeatedly alternating between straight-line driving in the inner area and turning driving in the outer perimeter area. The vehicle is temporarily stopped when transitioning from straight-line driving to turning driving, and during this temporary stop, the turning trajectory is estimated and boundary crossing detection during turning is performed. This makes effective use of the temporary stop of the vehicle that occurs when transitioning from straight-line driving to turning driving. Furthermore, the term "straight-line travel" used in the present invention does not mean only straight-line travel, but also includes curved travel with a large radius of curvature.

[0011] Even if the trajectory of the turn is estimated before the turn is performed and it is determined that the aircraft will not cross the boundary, there is a possibility that the aircraft may cross the boundary during the turn due to slippage or other reasons. To avoid this, even during the turn, it is necessary to perform a boundary crossing determination based on the estimated turn trajectory at that point, and if it is determined that a boundary crossing will occur, the aircraft must be stopped and switched to a new turn that avoids the boundary crossing. For this reason, in one preferred embodiment of the present invention, if the turning boundary crossing determination unit determines that the aircraft will cross the boundary line during the turn, the aircraft is stopped and a new avoidance turn is sought.

[0012] Since control is performed to avoid interference with boundary objects based on the boundary line and the aircraft position, it is preferable that the boundary line and the aircraft position be calculated using the same method. For this reason, in one preferred embodiment of the present invention, the aircraft position calculation unit calculates the aircraft position using satellite positioning, and the position of the boundary line is calculated based on the aircraft position (travel trajectory) when traveling in a circular motion along the outermost perimeter of the field area. [Brief explanation of the drawing]

[0013] [Figure 1] This is a side view of a rice transplanter, an example of an agricultural machine. [Figure 2] This flowchart shows the flow of seedling planting work using automated vehicle operation. [Figure 3] This is a schematic diagram showing the arrangement of obstacle detectors. [Figure 4] This is an explanatory diagram showing the division of the field area into which the travel route is set. [Figure 5] This is an explanatory diagram illustrating the circular travel path set in the outer perimeter area and the movement of the rice transplanter. [Figure 6] This is an explanatory diagram illustrating the reciprocating travel path set within the internal area and the movement of the rice transplanter. [Figure 7] This is a functional block diagram showing the control system of a rice transplanter. [Figure 8] This is a flowchart illustrating an example of a border crossing prevention routine. [Modes for carrying out the invention]

[0014] As an embodiment of the agricultural vehicle according to the present invention, a ride-on type rice transplanter will be described below. This rice transplanter can automatically travel in a field bounded by boundary objects. In this specification, unless otherwise specified, "front" means the front with respect to the longitudinal direction (travel direction) of the machine, and "rear" means the rear with respect to the longitudinal direction (travel direction) of the machine. Also, the left-right direction or lateral direction means the transverse direction (machine width direction) of the machine that is perpendicular to the longitudinal direction of the machine. "Up" or "down" refers to the positional relationship of the machine in the vertical direction (perpendicular direction), indicating the relationship at ground height.

[0015] Fig. 1 is a side view of a rice transplanter. The rice transplanter includes a riding-type, four-wheel drive traveling body (hereinafter referred to as body 1). The body 1 includes a parallel four-link linkage mechanism 11 that is connected to the rear portion of the body 1 so as to be capable of lifting and swinging, a hydraulic lifting cylinder 11a that drivingly swings the link mechanism 11, a seedling planting device 3 (an example of an agricultural material application device) that is rollably connected to the rear end portion of the link mechanism 11, and a fertilization device 4 that is erected from the rear end portion of the body 1 over the seedling planting device 3.

[0016] The body 1 includes wheels 12, an engine 13, and a hydraulic continuously variable transmission 14 as mechanisms for traveling. The wheels 12 include steerable left and right front wheels 12A, and non-steerable left and right rear wheels 12B. The engine 13 and the continuously variable transmission 14 are mounted on a front portion of the body 1. Power from the engine 13 is supplied to the front wheels 12A, the rear wheels 12B, and the like via the continuously variable transmission 14 and the like.

[0017] As one example, the seedling planting device 3 is configured as an 8-row planting type. The seedling planting device 3 includes a seedling placing table 31, 8 sets of planting mechanisms 32, and the like. Note that this seedling planting device 3 can be changed to formats such as 2-row planting, 4-row planting, and 6-row planting by control of each row clutch (not illustrated).

[0018] The seedling placing table 31 is a table on which 8 rows of mat-shaped seedlings are placed. The seedling placing table 31 reciprocates in the left-right direction with a constant stroke corresponding to the left-right width of the mat-shaped seedlings, and the longitudinal feed mechanism 33 longitudinally feeds each mat-shaped seedling on the seedling placing table 31 toward the lower end of the seedling placing table 31 at a predetermined pitch each time the seedling placing table 31 reaches the left or right stroke end. The eight planting mechanisms 32 are of a rotary type, and are arranged in the left-right direction at a constant interval corresponding to the interval between planting rows. Then, each planting mechanism 32 cuts out one seedling strain from the lower end of each mat-shaped seedling placed on the seedling placing table 31 by power from the body 1, and plants the seedling in a mud portion after soil preparation.

[0019] The seedling planting device 3 is provided with a seedling taking amount adjustment function for adjusting the amount of seedlings taken by the planting mechanism 32. The planting mechanism 32 passes through a seedling take-out port formed in a guide rail that slidably guides the lower end of the seedling placing table 31, takes out one seedling strain, and plants it. The seedling taking amount is adjusted by changing the vertical positions of the seedling placing table 31 and the guide rail that slidably guides the lower end of the seedling placing table 31.

[0020] As shown in Fig. 1, the fertilizing device 4 includes a horizontally long hopper 41, a delivery mechanism 42, an electric blower 43, a plurality of fertilizing hoses 44, and a furrow opener 45 provided for each row. The hopper 41 stores granular or powdery fertilizer. The delivery mechanism 42 is operated by power transmitted from the engine 13, and delivers a predetermined amount of fertilizer for two rows from the hopper 41 at a time. The fertilizing device 4 has a delivery amount adjustment function for changing the delivery amount of fertilizer by the delivery mechanism 42.

[0021] The blower 43 is operated by electric power from a battery (not shown) mounted on the machine body 1, and generates conveying air for conveying the fertilizer delivered by each delivery mechanism 42 toward the mud surface of the field. The fertilizing device 4 can be switched between an operating state in which the fertilizer stored in the hopper 41 is supplied to the field by a predetermined amount at a time and a non-operating state in which the supply is stopped through intermittent operation of the blower 43 and the like.

[0022] Each fertilizing hose 44 guides the fertilizer conveyed by the conveying air to each furrow opener 45. Each furrow opener 45 is disposed on each ground-leveling float 15. Each furrow opener 45 moves up and down together with each ground-leveling float 15, and forms a fertilizing groove in the mud part of a paddy field and guides the fertilizer into the fertilizing groove during working traveling where each ground-leveling float 15 is in contact with the ground.

[0023] The machine body 1 is equipped with a driver's unit 20 at its rear. The driver's unit 20 is equipped with manual driving controls, including a steering wheel 21 for steering the front wheels, a main transmission lever 22 for adjusting the vehicle speed by shifting gears of the continuously variable transmission 14, a sub-transmission lever 23 for shifting gears of the sub-transmission, and a work operation lever 25 for raising and lowering the seedling planting device 3 and switching its operating state. Furthermore, a general-purpose terminal 9 is provided in front of the driver's seat 16. The general-purpose terminal 9 is equipped with a notification device that displays various information to inform the operator and a touch panel that accepts input of various information. Around the steering wheel 21, there is a driver's operation device 24 for switching driving modes. Furthermore, a spare seedling frame 17 for storing spare seedlings is provided in front of the driver's unit 20.

[0024] The steering wheel 21 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 21. A steering motor M1 is also connected to the steering mechanism, and during automatic driving, the steering motor M1 operates based on a steering signal to adjust the steering angle of the front wheels 12A. Furthermore, a gear shift operation motor M2 is provided for automatically operating the main gear lever 22, and during automatic driving, the gear shift operation motor M2 operates based on a gear shift signal to adjust the gear position of the continuously variable transmission 14.

[0025] An extension frame 17a extending upwards is provided at the top of the reserve seedling frame 17. The extension frame 17a is fitted with a stacked light 18, which consists of multiple color lamps arranged vertically to indicate the status of the rice transplanter to the outside, and a positioning unit 8. The positioning unit 8 outputs positioning data for calculating the position and bearing (aircraft bearing) of the aircraft 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 tilt and acceleration of the three axes of the aircraft 1.

[0026] Figure 2 shows an example of the processing procedure for seedling planting work using this rice transplanter, which combines automatic and manual operation. In the example in Figure 2, this seedling planting work includes pre-operation processing #A, map creation processing #B, boundary calculation processing #C, path generation processing #D, work start point guidance processing #E, inner reciprocal planting processing #F, and outer perimeter planting processing #H.

[0027] In pre-operation processing #A, communication checks are performed between each unit of the rice transplanter's control system and the positioning unit 8. Furthermore, since the rice transplanter is remotely controlled using a remote control 90 (see Figure 1) and obstacle detection is performed using an obstacle detector 80 (see Figure 3), functional checks of the remote control 90 and obstacle detector 80 are also performed as pre-processing. As shown in Figure 3, the obstacle detector 80 in this embodiment is of the sonar type and consists of four front sonars 80f with a detection range in front of the machine 1, two side sonars 80s with detection ranges to the left and right of the machine 1, and two rear sonars 80r with a detection range in front of the machine 1.

[0028] Map creation process #B is the process of measuring the map of the field being worked on, that is, the outline of the field area. The travel trajectory is calculated based on the position signal obtained from the positioning unit 8 when the rice transplanter manually travels along boundary objects such as levees that define the field area, that is, along the outermost perimeter of the field area (map creation teaching travel). From this travel trajectory, the field outline, that is, the field map, is obtained as map information of the field area.

[0029] In boundary calculation process #C, as shown in Figure 4, a boundary line is calculated from the travel trajectory calculated in map creation process #B, indicating the position of the machine 1 that is the limit for the rice transplanter to avoid contact with boundary objects in the field. In the normal operation of the rice transplanter, as long as the position of the machine 1 does not cross this boundary line (also called the boundary crossing line), the rice transplanter will not come into contact with boundary objects such as levees. When the position of the machine 1 reaches the boundary line, the machine 1 is forcibly stopped. Since this rice transplanter is capable of automatic operation, even if unexpected slips or steering instability occur, a safety distance is added to prevent the rice transplanter from coming into contact with boundary objects such as levees, and the final boundary line position is determined.

[0030] In route generation process #D, a target route for automated driving, set within the field map created in map creation process #B, is created using a predetermined algorithm. The route generated for seedling planting work using automated driving is described below.

[0031] The field area defined by the field map is divided into an outer perimeter area and an inner area, as shown in Figure 4. The generated travel path consists of a circular travel path set in the outer perimeter area (see Figure 5) and a round-trip travel path set in the inner area (see Figure 6). The rice transplanter first performs seedling planting work in the inner area along the round-trip travel path (a type of automatic travel operation) (referred to as the inner work travel mode), and then performs seedling planting work in the outer perimeter area along the circular travel path (referred to as the circular work travel mode).

[0032] The circular route consists of a straight circular route extending parallel to the field boundary (bank) and a direction-changing route that incorporates forward and reverse movement to connect the straight circular routes. In Figure 5, the straight circular route is assigned the code R1, and the direction-changing route is assigned the code R2. The out-and-back route consists of numerous nearly parallel straight routes and a turning route (U-turn route) connecting the straight routes. In each straight route, seedling planting begins at the planting start position (which is also the turning end position) and ends at the planting end position (which is also the turning start position). In Figure 6, the planting start position is assigned the code US, the planting end position is assigned the code UF, the straight routes are assigned R3, and the turning routes are assigned R5. In Figures 5 and 6, the transition route for moving from the out-and-back route to the circular route is assigned the code R4. In this example, the transition path is similar to the turning path. Furthermore, in Figures 5 and 6, the working width of the rice transplanter is indicated by the symbol W, and the entrance and exit points of the rice transplanter to the field are depicted with diagonal lines and assigned the symbol GA. Figure 6 shows the starting guide path (assigned the symbol R6 in Figure 6) from the entrance / exit point to the starting position of the round-trip travel path (assigned the symbol S in Figure 6). In the turning path, direction change path, starting guide path, and transition path, the rice transplanter travels without performing any work, so these paths are shown with dotted lines. In the circular straight path and straight path, the rice transplanter travels while performing work, so these paths are shown with solid lines.

[0033] In the work start point guidance process #E, the rice transplanter first enters the field through the entrance / exit via manual drive and stops at a predetermined position. Then, the rice transplanter automatically travels along the start guidance path, which is the travel route to the starting point of the seedling planting work.

[0034] In the internal reciprocating planting process #F, the travel mode becomes the internal work travel mode, and the machine automatically travels along the reciprocating travel path shown in Figure 6, performing seedling planting work in the internal area. If seedling replenishment is required, seedling replenishment process #G is performed.

[0035] Once the inner reciprocating planting process #F is completed, the driving mode switches to the circular operation driving mode, and the outer perimeter planting process #H, which is seedling planting work along the circular driving path shown in Figure 5, is executed. In this embodiment, the circular driving path consists of an inner circular driving path that is driven first and an outer circular driving path that is driven afterward. Basically, the end position of the outer circular driving path is the entrance and exit of the field, so after the seedling planting work along the outer circular driving path, the rice transplanter exits the field through the entrance and exit. The seedling planting work along the inner circular driving path is performed by automatic driving. The seedling planting work along the outer circular driving path requires precise driving, so even in automatic driving, it is preferable to have a driver on board as a supervisor.

[0036] Figure 7 shows a control block diagram of the control system of this rice transplanter. The control system of the rice transplanter consists of a control device 100 that controls various operations of the rice transplanter, a general-purpose terminal 9 that can exchange data with the control device 100, and a remote control 90. Signals from the positioning unit 8, the driving mode switching device 24, the travel sensor group 28, the work sensor group 29, and the obstacle detector 80 are input to the control device 100. Control signals from the control device 100 are output to the travel equipment group 1A and the work equipment group 1B.

[0037] The running gear group 1A includes, for example, a steering motor M1 and a gear shift motor M2. Based on a control signal from the control device 100, the steering angle is adjusted by controlling the steering motor M1, and the vehicle speed is adjusted by controlling the gear shift motor M2.

[0038] The work equipment group 1B includes, for example, a lifting cylinder 11a for adjusting the height of the seedling planting device 3, a seedling quantity adjustment device for adjusting the amount of seedlings picked by the planting mechanism 32, and a dispensing quantity adjustment device for changing the amount of fertilizer dispensed by the dispensing mechanism 42.

[0039] The driving sensor group 28 includes various sensors that detect conditions such as steering angle, vehicle speed, and engine speed, as well as their corresponding set values. The work sensor group 29 includes various sensors that detect the conditions of the linkage mechanism 11, the seedling planting device 3, and the fertilizer application device 4.

[0040] The control device 100 includes a travel control unit 6, a work control unit 51, a machine position calculation unit 52, a travel route management unit 53, a driving control state detection unit 55, a border crossing management unit 57, an input signal processing unit 50a, and a communication unit 50b.

[0041] The input signal processing unit 50a processes signals from various sensors, switches, levers, etc., installed on the rice transplanter and transfers them to the functional unit built into the control device 100. The communication unit 50b has wireless communication capabilities and performs data communication with the outside, for example, with the remote control 90, and the received data is transferred to the input signal processing unit 50a.

[0042] The driving control unit 6 is equipped with an automatic driving control unit 6A, a manual driving control unit 6B, and a control management unit 6C. The automatic driving control unit 6A performs speed control and steering control during automatic driving. Based on the lateral deviation and directional deviation calculated by comparing the target driving path set by the driving path management unit 53 with the aircraft position calculated by the aircraft position calculation unit 52, steering control is performed so as to reduce the lateral deviation and directional deviation.

[0043] In addition to an automatic driving mode that automatically travels along a target travel path, this rice transplanter is equipped with a straight-line maintenance driving mode that automatically travels in a straight line while maintaining the orientation of a reference line defined by at least two points. The straight-line travel path managed by the travel path management unit 53 can be used as the reference line for the straight-line maintenance driving mode.

[0044] In manual driving mode, the manual driving control unit 6B controls the steering motor M1 based on the amount of movement of the steering wheel 21. The control management unit 6C selects one of the following modes based on the signal from the driving mode switching device 24: automatic driving mode, straight-line keeping driving mode, or manual driving mode.

[0045] The work control unit 51 automatically controls the work equipment group 1B based on a pre-programmed setting during automatic driving, and controls the work equipment group 1B based on the operator's input during manual driving. The aircraft position calculation unit 52 calculates the map coordinates (aircraft position) of the aircraft 1 based on satellite positioning data sent sequentially from the positioning unit 8.

[0046] In this embodiment, the general-purpose terminal 9 is equipped with a field information storage unit 91, a field map creation unit 92, a travel route generation unit 93, a boundary line calculation unit 94, and a travel trajectory generation unit 95. The field information storage unit 91 stores information about the field, such as the type of crop planted, the location of the field entrance (exit), and the location where seedlings can be supplied. The field map creation unit 92 performs the map creation process described with reference to Figure 2. The travel route generation unit 93 divides the field into an outer and inner region based on the field map created by the field map creation unit 92, and generates a circular travel route for traveling in the outer region and a round-trip travel route for the inner region. The boundary line calculation unit 94 performs the boundary line calculation process described with reference to Figure 2. The map creation process by the field map creation unit 92 and the boundary line calculation process by the boundary line calculation unit 94 require the travel trajectory from the map creation teaching run. The trajectory generation unit 95 generates the trajectory of the aircraft 1 based on the aircraft position calculated by the aircraft position calculation unit 52.

[0047] The travel path management unit 53 receives and manages the travel paths generated by the travel path generation unit 93 from the general-purpose terminal 9, and sequentially sets the travel paths that will serve as targets for machine steering in automatic driving mode.

[0048] The driving control state detection unit 55 detects the driving control state and the work control state based on the control information handled by the control device 100.

[0049] The border crossing management unit 57 has a function to prevent the machine 1 from coming into contact with boundary objects such as ridges by crossing the boundary line (boundary line data) calculated by the boundary line calculation unit 94. For this purpose, the border crossing management unit 57 is equipped with a boundary line storage unit 57a, a border crossing prevention control unit 57b, a turning trajectory estimation unit 57c, and a turning border crossing determination unit 57d.

[0050] The boundary line storage unit 57a stores the boundary line received from the boundary line calculation unit 94. The boundary crossing prevention control unit 57b determines whether the aircraft 1 will cross the boundary line based on the aircraft's position and gives a stop command to the driving control unit 6 to prohibit the aircraft 1 from traveling beyond the boundary line. The boundary crossing prevention control unit 57b has a straight-line boundary crossing prevention mode that prevents the aircraft 1 from crossing the boundary line when it is traveling in a straight line, and a turning boundary crossing prevention mode that prevents the aircraft 1 from crossing the boundary line when it is traveling in a turning direction.

[0051] In straight-line crossing prevention mode, the crossing prevention control unit 57b calculates the distance between the aircraft 1 and the boundary line from the aircraft position given by the aircraft position calculation unit 52 and the boundary line facing the direction of aircraft movement read from the boundary line storage unit 57a. When the calculated distance falls within a predetermined distance, the crossing prevention control unit 57b issues a stop command to the driving control unit 6.

[0052] During turning maneuvers, the rear or front end of the aircraft 1 swings laterally, so cross-boundary prevention control based on calculations of separation distance, such as in the straight-line cross-boundary prevention mode, is not used. Instead, cross-boundary prevention control is performed using the turning cross-boundary prevention mode. In this turning cross-boundary prevention mode, cross-boundary prevention control based on the estimated turning trajectory of the aircraft 1 is performed using the turning trajectory estimation unit 57c and the turning cross-boundary determination unit 57d. The turning trajectory estimation unit 57c estimates the turning trajectory, which is the trajectory of the aircraft 1 during turning maneuvers. The turning cross-boundary determination unit 57d determines whether the aircraft crosses the boundary line during actual turning maneuvers based on the estimated turning trajectory.

[0053] Next, the control routine for preventing crossing the boundary by the boundary crossing management unit 57 (boundary crossing prevention routine) will be explained using the flowchart in Figure 8. In this routine, first, it is checked whether the start of a turning maneuver is approaching from the set driving path for automatic driving (#01). If the start of a turning maneuver is not approaching, step #01 is repeated. Just before the start of the turning maneuver (#01 Yes branch), it is further checked whether at least a part of the machine 1 is in a pre-set boundary crossing prevention area (in this embodiment, the area between the boundary crossing prevention line set on the inner side of the boundary line and boundary objects such as ridges, or the outer perimeter area as described above) (#02). If the machine 1 is outside the boundary crossing prevention area (#02 "Outside" branch), the process returns to step #01. If the machine 1 is inside the boundary crossing prevention area (#02 "Inside" branch), the following pre-turning boundary crossing determination process is performed.

[0054] In the pre-turn crossing determination process, the turning trajectory during the turn is estimated by the turning trajectory estimation unit 57c based on the aircraft's position and the steering angle used for the turn (#11). Next, the turning crossing determination unit 57d determines, based on the estimated turning trajectory, whether the aircraft 1 will cross the boundary line during the actual turn (#12). If the result of this crossing determination is "not crossing" (#12 "not crossing" branch), the turn is permitted (#21), and the turn begins (#22).

[0055] If the result of the boundary crossing determination is "boundary crossing" (#12 "boundary crossing" branch), the boundary crossing prevention control unit 57b sets a first boundary crossing avoidance turning maneuver to avoid crossing the boundary (#13), and the turning trajectory of this set boundary crossing avoidance turning maneuver is estimated by the turning trajectory estimation unit 57c (#14). Based on the estimated turning trajectory, it is determined whether the aircraft 1 will cross the boundary line during this boundary crossing avoidance turning maneuver (#12). If the result of this boundary crossing determination is "non-boundary crossing" (#12 "non-boundary crossing" branch), the boundary crossing avoidance turning maneuver is permitted (#21), and the turning maneuver begins (#22). If the result of the boundary crossing determination is "boundary crossing" (#12 "boundary crossing" branch), the process returns to step #13, and a second boundary crossing avoidance turning maneuver is set. Boundary crossing avoidance maneuver using reverse (so-called reverse maneuver) is a reliable way to avoid crossing the boundary, but it results in a loss of time. Crossing avoidance driving using only forward movement (turning driving using maximum steering angle or speed difference between left and right wheels) is not a guaranteed way to avoid crossing, but it does result in less time loss. For this reason, the first crossing avoidance turning maneuver uses only forward movement, while the second crossing avoidance turning maneuver uses crossing avoidance driving with reverse movement.

[0056] When turning is initiated, the system checks whether the turning has ended based on information from the driving control state detection unit 55 (#23). If the turning is completed (#23 Yes branch), the system returns to step #01 and this boundary crossing prevention routine is repeated. If the turning is still in progress (#23 No branch), the following boundary crossing determination process during turning is performed.

[0057] In the boundary crossing determination process during turning, first, an actual boundary crossing determination is made to determine whether at least a part of the aircraft 1 is crossing the boundary at the current position (#31). If the result of the actual boundary crossing determination is "not crossing" (#31 "not crossing" branch), the process returns to step #23 and the turning continues. If the result of the actual boundary crossing determination is "crossing" (#12 "crossing" branch), the boundary crossing prevention control unit 57b gives a stop command to the driving control unit 6, and the aircraft 1 stops (#33). Next, the boundary crossing prevention control unit 57b sets up a boundary crossing avoidance turning maneuver that moves away from the boundary line using reverse (#34), and the turning trajectory of this set boundary crossing avoidance turning maneuver is estimated by the turning trajectory estimation unit 57c (#35). Based on the estimated turning trajectory, it is determined whether the aircraft 1 crosses the boundary line during this boundary crossing avoidance turning maneuver (#36). If the result of this border crossing check is "not border crossing" (#36 "not border crossing" branch), this border crossing avoidance turning maneuver is permitted, turning maneuver resumes (#37), and control returns to step #23.

[0058] If the result of the boundary crossing detection is "boundary crossing" (#12 "boundary crossing" branch), a warning is sent via the general-purpose terminal 9 that the aircraft 1 cannot leave the boundary line while automatically driving (#41). At the same time, automatic driving is canceled (#42), and this boundary crossing prevention routine ends. After that, the boundary crossing prevention control is turned off, and the aircraft 1 is manually driven away from the boundary line, carefully avoiding interference between the aircraft 1 and the boundary object.

[0059] In step #02, if aircraft 1 is just before starting a turn and is inside the border crossing prevention area, aircraft 1 may be temporarily stopped before proceeding to the next step.

[0060] [Another embodiment] (1) In the above embodiment, in steps #13, #14, and #15, a first boundary avoidance turning maneuver using only forward movement and a second boundary avoidance turning maneuver using reverse movement were applied in sequence as boundary avoidance turning maneuvers, but the second boundary avoidance turning maneuver alone may also be used. (2) In the above embodiment, the field map creation unit 92, the travel route generation unit 93, the boundary line calculation unit 94, and the travel trajectory generation unit 95 were built on the general-purpose terminal 9, but at least some of them may be built on the control device 100. Furthermore, they may be built on an external management computer that can exchange data with the control device 100. (3) The steering angle of the automatic driving control unit 6A in the turning path may be controlled to follow the generated turning path, or it may be controlled to use a predetermined steering angle to achieve a predetermined turning path. (4) In the above embodiment, a rice transplanter was used as the agricultural work vehicle, but other agricultural work vehicles such as a combine harvester, tractor, direct seeder, or spraying (dispersing) management machine may also be used.

[0061] Furthermore, the configurations disclosed in the above embodiments (including other embodiments, the same applies hereinafter) can be applied in combination with configurations disclosed in other embodiments, as long as no inconsistencies arise. Moreover, the embodiments disclosed herein are illustrative, and the embodiments of the present invention are not limited thereto, and can be modified as appropriate without departing from the object of the present invention. [Industrial applicability]

[0062] This invention is applicable to autonomous agricultural vehicles. [Explanation of Symbols]

[0063] 1: Aircraft 6: Driving control unit 8: Positioning Unit 8A: Satellite positioning module 8B: Inertial Measurement Module 9: General-purpose terminal 52: Aircraft position calculation unit 53: Route Management Department 55: Operation control state detection unit 57: Cross-border management department 57a: Boundary line storage section 57b: Border crossing prevention control unit 57c: Turning trajectory estimation unit 57d: Boundary crossing determination unit during turning 94: Boundary Calculation Unit 95: Track generation unit 100: Control device

Claims

[Claim 1] An autonomous farm vehicle that travels in fields, A unit for calculating the position of the machine in the field, It includes a turning boundary crossing determination unit that determines whether the aircraft crosses the boundary line during actual turning, It has a straight-ahead crossing prevention mode and a turning crossing prevention mode. In the straight-line crossing prevention mode, when the distance between the aircraft and the boundary line falls within a predetermined distance, the aircraft stops. In the turning boundary crossing prevention mode, the turning boundary crossing determination unit determines whether the aircraft crosses the boundary line based on the aircraft position and steering angle. The driving path in the aforementioned automated driving includes a circular driving path and a round-trip driving path set inside the circular driving path. In the aforementioned circular travel route, only the straight-ahead border crossing prevention mode is active among the straight-ahead border crossing prevention mode and the turning border crossing prevention mode, and in the aforementioned round-trip travel route, the straight-ahead border crossing prevention mode and the turning border crossing prevention mode are active in the agricultural vehicle.

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