JP2023127232A - work vehicle - Google Patents

Abstract

To provide a work vehicle that can prevent work accuracy from being lowered due to unstable automatic travel and meandering, thereby improving work accuracy.SOLUTION: A work vehicle A that automatically travels in a field H along a target travel route LN includes a control device that acquires position information during automatic travel, calculates a the vehicle's position, and automatically steers the vehicle along the set target travel route LN. The control device includes a route guide unit that guides the work vehicle A onto the target route LN when receiving an instruction to switch from manual travel to automatic travel. When the route guide unit receives the instruction information to switch from manual travel to automatic travel, it calculates an approach difference angle θd that indicates the difference between an angle θa formed by an own vehicle direction Da of the work vehicle A against a reference direction Dn and an angle θtg formed by a direction Dtg of a target line parallel to a straight route La having a moving target point against the reference direction. Automatic driving is started on the condition that the calculated approach difference angle is smaller than an allowable angle θw.SELECTED DRAWING: Figure 6

Description

The present invention relates to a work vehicle that performs agricultural work while automatically traveling in a field.

Conventionally, for example, as shown in Patent Document 1 below, there has been known a work vehicle that uses position information obtained from a satellite positioning system to perform agricultural work (hereinafter simply referred to as work) while automatically traveling in a field. . In this type of self-driving work vehicle, a target travel route during automatic travel (hereinafter referred to as a target travel route) is set in advance before work begins. In addition, in order to efficiently travel the entire field, this target travel route is set so that the work vehicle alternates between a straight route where the work vehicle moves straight while working, and a turning route where the vehicle turns and moves between the straight routes. A route is planned in a single stroke. The target travel route is set by storing data regarding the target travel route in the work vehicle.

This conventional work vehicle is capable of switching between manual driving and automatic driving. During manual driving, the worker steers the steering wheel, and during automatic driving, the operator operates the steering wheel at predetermined time intervals. It is configured to acquire position information indicating the current position of the work vehicle (own vehicle position) and calculate the deviation (deviation in direction and distance) of the own vehicle position with respect to the set target travel route, and the calculated deviation By automatically steering the steering wheel based on this, the vehicle automatically travels along the target travel route.

Furthermore, Patent Document 2 describes that during automatic driving, when the own vehicle position is off the target driving route (for example, immediately after switching from manual driving to automatic driving), by searching the area in front of the work vehicle, , a technique has been disclosed for finding a travel route candidate on a target route closest to the own vehicle position and returning a work vehicle to the target travel route.

Japanese Patent Application Publication No. 2018-147163 JP 2018-4589 Publication

As in the technology described in Patent Document 2, when the work vehicle is returned to the target travel route closest to the own vehicle position and continues automatic travel, the direction, distance, and position of the work vehicle with respect to the target travel route Immediately after returning to the target travel route (straight route), the work vehicle's travel becomes unstable due to the difference between the orientation when it enters the target travel route and the direction in which the target travel route extends. There was a problem that meandering was more likely to occur and work accuracy was reduced. As a result, for example, during ridge making work or seeding work, the appearance of the ridges and seed rows becomes poor, and if the ridges and seed rows are crooked when performing intertilling soil or chemical spraying work afterwards, they may be stepped on by machinery. There is also a risk of it happening.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a work vehicle that can eliminate such problems, prevent work accuracy from decreasing due to unstable running and meandering, and thereby improve work accuracy. shall be.

In order to achieve the above object, the first invention
A work vehicle that automatically travels in a field along a target travel route,
Equipped with a control device that acquires position information during automatic driving, calculates the vehicle's position, and automatically steers the vehicle along a set target driving route.
The control device includes a route guide unit that guides the work vehicle onto the target route upon receiving an instruction to switch from manual travel to automatic travel,
Upon receiving the instruction information to switch from manual driving to automatic driving, the route guide unit calculates the angle formed by the own heading of the work vehicle with respect to the reference heading and the target line parallel to the straight route having the movement target point. Calculate the approach difference angle that indicates the difference in angle between the directions,
The vehicle is characterized in that automatic travel is started on condition that the calculated approach difference angle is smaller than an allowable angle.

According to the first invention, the work vehicle is configured to start automatic travel on the condition that the approach difference angle is smaller than the allowable angle, so that the work vehicle enters the straight path at an angle that is likely to cause meandering. This will prevent situations where this happens. This prevents the work accuracy from decreasing due to unstable running and meandering, and improves the work accuracy.

In a second invention based on the first invention, the route guide section calculates the shortest distance between the target travel route and the own vehicle position, and the allowable angle is determined according to the calculated shortest distance. , characterized in that it is configured to change.

According to the second invention, in addition to the effects of the first invention, the permissible angle is configured to be changed according to the calculated shortest distance, so that automatic traveling according to the shortest distance can be achieved. It becomes possible to determine whether or not it is possible. As a result, work accuracy can be improved.

A third invention is characterized in that, in the second invention, the allowable angle is configured to be smaller as the calculated shortest distance is shorter.

According to the third invention, in addition to the effect of the second invention, the allowable angle is configured to be smaller (severer) as the calculated shortest distance is shorter, so that Driving immediately after entry can be made more stable.

According to the present invention, it is possible to provide a work vehicle that can prevent work accuracy from decreasing due to unstable automatic travel and meandering, thereby improving work accuracy.

FIG. 1 is a left side view of a work vehicle according to an embodiment of the present invention. FIG. 2 is a block diagram showing the configuration of a control device for the work vehicle shown in FIG. FIG. 3 is an explanatory diagram for explaining the target travel route of the work vehicle. FIG. 4 is a flowchart showing the processing of the route guide section of the work vehicle. FIGS. 5A and 5B are schematic diagrams showing the relationship between the target travel route, the host vehicle reference point, and the movement target point. FIG. 6 is an explanatory diagram for explaining the approach difference angle of the work vehicle. FIGS. 7A, 7B, and 7C are explanatory diagrams showing the relationship between the shortest distance and the allowable angle. FIG. 8 is a schematic diagram showing the reference line of the work vehicle.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. In the following description, unless otherwise specified, the forward direction of the work vehicle is referred to as the front, the opposite direction is referred to as the rear, and the right side facing forward is referred to as the right, and the left side is referred to as the left.

<1. Work vehicle configuration>
FIG. 1 is a left side view of a work vehicle according to an embodiment of the present invention.
The work vehicle A has a structure of a so-called tractor, in which a work machine WM serving as a work means is attached to the rear of a traveling vehicle body a1 equipped with an automatic travel means. Note that the traveling vehicle body a1 and the working machine WM are not necessarily limited to the configuration of a tractor, and may have a configuration of a combine harvester, for example.

As shown in FIG. 1, the running vehicle body a1 has an engine EN serving as a driving source, a fuel tank (not shown), and a control device C that controls each mechanism disposed within a hood a11. The power from the vehicle is shifted by a transmission (not shown) in the transmission case a12, and transmitted to the front wheels a13 and rear wheels a14, respectively, to drive the vehicle.

A cabin a15 in which a worker rides is provided at the rear of the bonnet a11, and a rotary steering handle ST, which is a means for steering the traveling vehicle body a1, is provided on a dashboard within the cabin a15.

When the steering handle ST is rotated, the front wheel a13, which is a steered wheel, is rotated via a steering device (not shown) according to the direction of rotation and the amount of operation. The direction of travel is changed.

The rotation base of the steering handle ST is provided with a steering angle detection means (not shown) capable of detecting a steering angle corresponding to the rotation direction and operation amount of the steering handle ST. This steering angle detection means is constituted by, for example, an angle sensor such as a rotary encoder. The traveling direction of the work vehicle A is determined according to this steering angle.

The work vehicle A operates in an automatic driving mode in which a steering wheel ST is automatically steered by a control device C, which will be described later, by receiving a predetermined operation from a worker via an operation member (not shown), and in a manual driving mode in which the worker steers the vehicle. It is possible to switch between.

Further, a steering actuator (steering motor), not shown, is provided on the rotating shaft (steering shaft) of the steering handle ST to control rotation of the steering handle ST and enable automatic steering. Feedback control using the steering angle of the steering actuator as a control variable makes it possible to control the traveling direction of the work vehicle A during automatic travel.

Furthermore, a PTO clutch, a PTO transmission, and a braking device (not shown) are housed in the mission case a12, and the transmission of power to the PTO shaft can be controlled. This allows the work vehicle A to control the drive of the work machine WM.

At the rear of the traveling vehicle body a1, a work equipment mounting device WJ is disposed, which includes lift arms a22, a22 that protrude rearward from the side of the hydraulic cylinder case a21, a top link a23, a lower link a24, a24, etc. By expanding and contracting the hydraulic cylinder a25, the work machine WM mounted on the work machine mounting device WJ can be raised and lowered. Thereby, the working machine WM is configured to be able to switch between a working position where it performs work on the field and a non-working position where it does not work. For example, if the working machine WM is a tiller, the working position refers to the grounded state, and the non-working position refers to the non-grounded state that has been raised from the grounded state. In the illustrated example, the work machine WM is a rotary tiller, but the work machine WM mounted on the work vehicle A may include a fertilizer spreader, a pesticide sprayer, etc. in addition to the above-mentioned rotary tiller. There are machines such as sowing machines, sowing machines, and harvesting machines.

The positioning device AN is a device that is provided approximately at the center of the vehicle body a1 in the longitudinal direction and measures the position of the vehicle body A. The positioning device AN is equipped with a GNSS (Global Navigation Satellite System) that measures positioning and time by receiving radio waves from a navigation satellite AS orbiting in the sky using a positioning antenna (not shown), and a 3-axis gyroscope. It also includes an inertial measurement unit that measures the posture, orientation, etc. of the work vehicle A using three-direction acceleration sensors and the like.

<2. Control device configuration>
FIG. 2 is a block diagram showing the configuration of a control system including a control device C of the work vehicle A.
The control device C is an information processing device configured by combining a plurality of ECUs (Electronic Control Units). Each of these multiple ECUs is configured with a CPU that performs arithmetic processing and a memory that can read and write information necessary for arithmetic processing, and the CPU operates according to various control programs stored in the memory. As a result, the configuration described as functional blocks in FIG. 2 is realized.

As shown in FIG. 2, the control device C includes an output processing section c1, a communication processing section c2, an input processing section c3, a traveling control section c4, an information storage section c5, and a route management section c6. They are configured to be able to send and receive information to and from each other via bus BA.

The output processing unit c1 is a device that performs the function of an input/output interface, and controls the travel system equipment group MA1 that controls travel functions such as travel, stop, and change of travel direction of the work vehicle A, and lifts, lowers, drives, and stops the work machine WM. It is connected to a work equipment group MA2 that controls operations such as the above, and a notification section MA3 that outputs video and audio to notify the worker of various information. In the present embodiment, the traveling system equipment group MA1 includes mechanisms such as a steering actuator, engine EN, transmission, and brake, and the working equipment group MA2 includes a PTO clutch, a PTO transmission, a braking device, and the like. Mechanisms such as a hydraulic cylinder a25 are included.

The communication processing unit c2 is a communication mechanism that connects the control device C with an external device that is physically separated via the network NW and exchanges information through communication. In this embodiment, the communication processing unit c2 is connected to the operating terminal T, and is capable of sending and receiving information.

The operation terminal T is equipped with a communication control section t1, a display section t2, and an operation section t3, and functions as a user interface for inputting the functions of the computer system and the conditions necessary for automatic driving realized by the control device C. It is an information terminal with For example, the communication control section t1 is an information processing device including a CPU, ROM, RAM, etc., the display section t2 is a liquid crystal panel, and the operation section t3 is composed of a touch panel, buttons, etc.

In addition, the operation terminal T receives an operation for switching the work vehicle A between manual travel and automatic travel using the operation unit t2, transmits information regarding an instruction to switch between manual travel and automatic travel to the control device C, and sends information regarding an instruction to switch between manual travel and automatic travel to the control device is configured to receive this.

The input processing unit c3 is a mechanism that receives information input from a connected external device, and is capable of acquiring various information such as positioning information and detection information. In the present embodiment, the input processing unit c3 is connected to a positioning device AN, a traveling system detection sensor SN1 including a steering angle detection means, and a working system detection sensor SN2 that detects the state of the operation, posture, etc. of the work machine WM. There is.

The control device C also includes a travel control section c4 that controls the travel of the work vehicle A, an information storage section c5 that stores various information, and a route management section c6 that performs processing regarding the target travel route LN.

The travel control unit c4 is a mechanism that includes a program and various circuits that control the travel of the work vehicle A during automatic travel (automatic steering) and manual travel (manual steering), and controls the travel system equipment group MA1 during automatic travel. The vehicle includes an automatic travel control section c41 and a manual travel control section c42 that controls the travel system equipment group MA1 during manual travel.

The automatic driving control unit c41 includes a vehicle position calculation unit c43 that calculates the vehicle position by acquiring positioning information from the positioning device AN, a vehicle orientation calculation unit c44 that calculates the vehicle orientation, and a deviation calculation unit that calculates the deviation. c45, and a steering angle calculation unit c46 that calculates the steering angle from the detection information of the driving system detection sensor group SN1. The automatic travel control unit c41 configured as described above calculates the deviation using the deviation calculation unit c45, and, based on the calculated deviation, adjusts the steering wheel appropriately for the work vehicle A to travel along the target travel route LN. By calculating the steering angle of the ST and controlling the steering actuator so as to achieve the calculated steering angle, the work vehicle A can travel automatically.

The information storage unit c5 is a storage device that can store various types of information, and includes, for example, an HDD (Hard Disc Drive) or an SSD (Solid State Drive). The information storage section c5 includes a field information storage section c51 that stores information regarding the field, a route information storage section c52 that stores information regarding the travel route during automatic driving, and a work information storage section c53 that stores information regarding the work.

The field information storage unit c51 stores field information (information such as the size, shape, map position of the field to be worked on, and position data of the ridges that define the boundaries of the field), and the work area R in the field. Information such as work area information defining the area to be worked on is stored.

The route information storage unit c52 stores information regarding the target travel route LN, work costs for the target travel route LN (travel distance, fuel consumption, work time, etc. corresponding to the target travel route LN), and the like.

The work information storage unit c53 stores information (hereinafter referred to as work information) regarding the work width W, the type of work (intertilling soil, sowing, etc.), etc., which are preset by the operator.

The route calculation unit c62 calculates the target travel route LN based on the field information, work information, and the like.
FIG. 3 is an explanatory diagram for explaining the target travel route of the work vehicle A. The target travel route LN calculated by the route calculation unit c62 is based on the field information and the work information, as shown in FIG. The route is planned in a single stroke manner by alternately connecting the turning route LN2 that moves between the two directions. The straight route LN1 consists of an actual travel route portion La that functions as an actual travel route, and a route extension portion Lb that is an extension of the actual travel route portion La, and the actual travel route portion La is defined by end points EP at both ends. ing. Information regarding the calculated target travel route LN (hereinafter referred to as target travel route information) is stored in the route information storage section c52.

Returning to FIG. 2, the route guide unit c62 moves the work vehicle A along the target travel route LN based on the position information obtained by the vehicle position calculation unit c43 and the target travel route information stored in the route information storage unit c52. It functions to guide you to. Based on a predetermined condition (for example, the operator has performed a switching operation from manual driving to automatic driving), the route guide unit c62 searches an area in front of the work vehicle and finds a movement target point on the target route to be moved. It is configured to calculate and pass the calculated position information of the movement target point to the automatic travel control unit c41, and return the work vehicle A to the target travel route LN.

Here, in FIG. 3, a self-vehicle reference point CP is shown as a predetermined reference point for the work vehicle A. The distance in the radial direction from the own vehicle reference point CP that indicates the own vehicle position is called a search distance R. In other words, the area within the search distance R is within the circle SC with radius R centered on the host vehicle reference point CP. Furthermore, in the example of FIG. 3, the area surrounding the own vehicle reference point CP is set as the search area SA, and a fan-shaped area (fan-shaped area) is set as the search area SA. The radius of this sector matches the search distance R, and the side thereof is given a symbol Se. Note that the central angle θ of the fan shape may be widened to 180°. The perpendicular line from the own vehicle reference point CP (a reference point that indicates the own vehicle position) to the traveling route LN defines the shortest distance MD between the own vehicle reference point CP and the traveling route LN, so the distance between this perpendicular line and the traveling route LN is The coordinate position indicating the intersection is defined as the shortest position coordinate MP.

<3. Route guidance section processing>
FIG. 4 is a flowchart showing the processing of the route guide section c62 of the work vehicle A.
Note that the process shown in FIG. 4 is executed on the condition that the work vehicle A is in manual travel mode. As shown in Figure 4, when a predetermined condition is met (for example, an instruction to start automatic driving is issued due to an operator switching from manual driving to automatic driving, etc.), route guidance is performed. When the process of the unit c62 is started, the own vehicle position calculation unit c43 that calculates the own vehicle position calculates the own vehicle position and acquires information indicating the own vehicle position (hereinafter simply referred to as position information). Step #10).

Next, the route guide unit c62 calculates a self-vehicle reference point CP based on the acquired position information, and determines whether a straight route LA exists within the search area SA based on the calculated self-vehicle reference point CP. It is determined whether or not (step #11).

If a straight route LA exists within the search area SA, the route guide unit c62 calculates the shortest position coordinates MP and the shortest distance MD of the straight route LA. If a plurality of straight routes LA exist within the search area SA, the shortest straight route LA with the shortest distance MD is selected as the guide destination (movement destination) straight route LA.

Next, the route guide unit c62 calculates a moving target point Pm that is a target point for guiding on the straight route LA (step #12). FIGS. 5A and 5B are schematic diagrams showing the relationship between the target travel route LN, the host vehicle reference point CP, and the moving target point Pm. For example, as shown in FIG. 5A, when the end point EP of the actual travel route portion La is included in the search area SA, the route guide unit c62 determines this end point EP as the movement target point Pm. . Further, as shown in FIG. 5(b), when the end point EP of the actual travel route portion La is not included in the search area SA, the intersection of the side Se of the search distance R and the actual travel route portion La moves. It is determined as the target point Pm.

Next, the route guide unit c62 calculates the approach difference angle θd of the work vehicle A (step #14). FIG. 6 is an explanatory diagram for explaining the approach difference angle θd of the work vehicle A.
As shown in FIG. 6, the approach difference angle θd, which indicates the difference in the orientation of the work vehicle A with respect to the traveling direction of the straight route La, is the approach difference angle θd of the own vehicle orientation Da of the work vehicle A with respect to the reference orientation Dn (for example, north). It is calculated by the difference (θd=|θa−θtg|) between the angle θa and the angle θtg between the direction Dtg of the target line parallel to the straight path La having the moving target point Pm.

Next, the route guide unit c62 determines whether the calculated approach difference angle θd is smaller than the allowable angle θw (step #15).
Here, the allowable angle θw is configured to be determined based on the shortest distance MD.
FIGS. 7A, 7B, and 7C are explanatory diagrams showing the relationship between the shortest distance MD and the allowable angle θw.
For example, the allowable angle θw is determined by one of the patterns among the relationships between the shortest distance MD and the allowable angle θw shown in FIGS. 7(a), 7(b), and 7(c), respectively. It may be provided so that these patterns can be switched and selected by a predetermined operation by the operator (for example, operation of the operation part t3 using the operation terminal T).

As shown in FIG. 7(a), for example, the allowable angle θw is set to a predetermined lower limit setting angle of 15° when the shortest distance MD is 0 m, and as the shortest distance MD becomes longer, a predetermined upper limit setting angle of 90°. is configured to increase with an upper limit of . That is, as the shortest distance MD becomes longer, the approach difference angle θd that allows the vehicle to ride smoothly on the target travel route LN without meandering increases. Further, in the illustrated example, when the shortest distance MD reaches the predetermined set distance of 2 m, it becomes 90°, which is the predetermined upper limit set value. That is, at this time, as will be described later, when the shortest distance MD is a set distance of 2 m or more, the work vehicle A is allowed to run automatically if the approach difference angle θd is smaller than 90°. In other words, if the shortest distance MD is 2 m or more, it is expected that if the approach difference angle θd is smaller than 90°, it will be possible to smoothly get on the target travel route LN without meandering. be.

Here, the predetermined lower limit set angle of 15°, upper limit set angle of 90°, and set distance of 2 m are examples, and depending on the specifications such as the vehicle width of the work vehicle A, it is possible to smoothly follow the target traveling route LN without meandering. Since the relationship between the shortest rideable distance MD and the permissible angle θw changes, it is desirable that these values be set flexibly according to the specifications of the work vehicle A. The configuration may be such that these numerical values can be set or changed as appropriate by a predetermined operation by the operator (for example, operation of the operation unit t3 using the operation terminal T). Here, in the example of FIG. 7(a), as the shortest distance MD becomes longer, the allowable angle θw also increases in direct proportion. Furthermore, in the example of FIG. 7(b), the increase rate of the allowable angle θw is configured to increase gradually as the minimum distance MD becomes longer, and in the example of FIG. 7(c), the minimum distance MD is longer. As the angle increases, the rate of increase in the allowable angle θw gradually decreases.

Then, when it is determined that the calculated approach difference angle θd is smaller than the allowable angle θw, the system switches to automatic driving. That is, the configuration is such that automatic driving is permitted (step #16).
That is, as shown in FIGS. 7(a), 7(b), and 7(c), the allowable angle θw is configured to become smaller as the shortest distance MD becomes shorter, so the approach difference angle θd becomes shorter than the shortest distance. When the allowable angle θw corresponding to the MD is exceeded, automatic driving is not started. As a result, automatic driving prevents the work vehicle A from entering the straight route La at an angle that would easily cause meandering. This prevents the work accuracy from decreasing due to unstable running and meandering, and improves the work accuracy.

In addition, in the example of FIG. 7(b), as the shortest distance MD becomes shorter, the allowable angle θw can also become smaller rapidly, which is particularly suitable when the work vehicle A is on steep soil or on a vehicle body where it is difficult to turn. It is. On the other hand, in the example of FIG. 7(c), the allowable angle θw can be gradually reduced as the shortest distance MD becomes shorter, so it is especially useful when the work vehicle A is on soil or on a vehicle body where it is easy to turn around. suitable. In this way, by configuring the allowable angle θw to be changed according to the calculated shortest distance MD, it becomes possible to suitably determine whether or not automatic driving is possible according to the shortest distance MD. . As a result, work accuracy can be improved.

<4. Others＞
FIG. 8 is a schematic diagram showing the reference line of work vehicle A. As shown in FIG. When using work information, it is desirable to set the route passing through the previous starting position Pst as the new reference line Lnw based on the past reference line Lps. Conventionally, a reference line is set on the outline of the field, and when used in field cultivation, depending on the working conditions, a route that crushes the ridges may be generated. In a field, work can be started from the same starting position, and a reference line passing through the starting position can be automatically set.

The present invention is not limited to the embodiments described above, and various modifications can be made within the scope of the invention described in the claims, and these are also included within the scope of the present invention. Needless to say.

In step #15 of FIG. 4, when it is determined whether the calculated approach difference angle θd is smaller than the allowable angle θw, the display section t2 of the operation terminal Vehicle A may display "easy to ride" and "difficult to ride" on the target travel route LN. That is, when the approach difference angle θd is smaller than the allowable angle θw, and the difference between the difference angle θd and the allowable angle θw is larger than a predetermined threshold value, "Easy to ride" is displayed, and the entry angle θd is smaller than the allowable angle θw. If it is small, "difficult to ride" is displayed, and on the other hand, if No in step #15, "automatic driving is not possible" is displayed. As a result, when the worker performs the switching operation to automatic driving, he or she can quickly visually check whether the work vehicle A can easily ride on the target travel route LN, improving convenience. . For example, if "difficult to ride" is displayed, by temporarily switching to manual running, it is possible to suitably prevent disturbances in the sowing rows, etc. Furthermore, the smaller the difference in angle (θw - θd), the more difficult it is to get on the target travel route LN. Therefore, the system is configured to decelerate automatically and is configured to make it easier to get on the target travel route LN. It's okay.

A Working vehicle a1 Traveling vehicle body a11 Bonnet a12 Mission case a13 Front wheel a14 Rear wheel a15 Cabin a21 Hydraulic cylinder case a22 Lift arm a23 Top link a24 Lower link a25 Hydraulic cylinder BA Communication bus C Control device LN Target travel route T Operating terminal AS Navigation satellite

Claims (3)

A work vehicle that automatically travels in the field along a target travel route is equipped with a control device that acquires position information during automatic travel, calculates the vehicle's position, and automatically steers the vehicle along the set target travel route. The device includes a route guide unit that guides the work vehicle onto the target route when receiving an instruction to switch from manual drive to automatic drive, and the route guide unit receives instruction information to switch from manual drive to automatic drive. Then, an approach difference angle is calculated, which is the difference between the angle formed by the own direction of the work vehicle and the direction formed by the direction of the target line parallel to the straight path with the moving target point, with respect to the reference direction, and the calculated approach angle is calculated. The vehicle is configured to start automatic travel on the condition that the differential angle is smaller than the allowable angle. The route guide unit calculates the shortest distance between the target travel route and the own vehicle position,
The work vehicle according to claim 1, wherein the allowable angle is configured to be changed depending on the calculated shortest distance. The work vehicle according to claim 2, wherein the allowable angle is configured to be smaller as the calculated shortest distance is shorter.