Work vehicle

Abstract

To provide a work vehicle capable of performing automated travelling without using a position acquisition device.SOLUTION: A work vehicle includes a control device capable of performing straight-advancing assist for causing a machine body to automatically advance straight by controlling a steering device. The control device sets a start reference point for straight advancing when a work machine of the machine body is at a predetermined descent position in a state that a first distance from a first point at which a distance from a first distance sensor provided in a center in a right-left direction of the machine body to a ridge is the shortest distance to a second point which is from a second distance sensor to a ridge at a back of the machine body in a direction parallel to a front-back direction, and a second distance from the first point to a third point which is from a third distance sensor to a ridge at the back of the machine body in a direction parallel to the front-back direction are the same.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present invention relates to a work vehicle. [Background technology]

[0002] Conventionally, it is known that when the position of a work vehicle measured by a position acquisition device reaches the end of a work travel route, automatic travel is prohibited (for example, see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6415810 Summary of the Invention [Problem to be solved by the invention]

[0004] However, since the above-mentioned work vehicle performs automatic traveling based on the position information measured by the position acquisition device, automatic traveling cannot be performed if the position acquisition device cannot acquire the position information. Also, the above-mentioned work vehicle cannot perform automatic traveling if it is not provided with a position acquisition device.

[0005] The present invention has been made in consideration of the above, and has an object to provide a work vehicle that is capable of autonomous driving without using a position acquisition device. [Means for solving the problem]

[0006] In order to solve the above-mentioned problems and achieve the object, a work vehicle (1) according to one aspect of the embodiment includes a first distance sensor (160) provided on the rear side of the vehicle body, provided in the center of the vehicle body in the left-right direction, and provided on a first orthogonal line perpendicular to the fore-aft direction of the vehicle body, a second distance sensor (161) provided on the first orthogonal line and arranged so that its distance from the first distance sensor (160) is a first predetermined distance, a third distance sensor (162) provided on the first orthogonal line, arranged so that its distance from the first distance sensor (160) is the first predetermined distance, and provided on the opposite side of the first distance sensor (160) to the second distance sensor (161), a steering device (35) that adjusts the steering amount of the vehicle body's running wheels (10), and a control device (100) capable of performing straight-line assist to automatically move the vehicle in a straight line by controlling the steering device (35). The first distance sensor (160) measures the shortest distance from the first distance sensor (160) to a first point where the distance to the ridge behind the machine is the shortest, the second distance sensor (161) measures the distance from the second distance sensor (161) to a second point which is a ridge behind the machine in a direction parallel to the front-rear direction, and the third distance sensor (162) measures the distance from the third distance sensor (162) to a third point which is a ridge behind the machine in a direction parallel to the front-rear direction. The control device (100) calculates a first distance from the first point to the second point and a second distance from the first point to the third point, and sets a start reference point for straight travel when the work implement (4) of the machine reaches a predetermined descending position with the first distance equal to the second distance. Effect of the Invention

[0007] According to one aspect of the embodiment, automatic driving can be enabled without using a position acquisition device. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a side view showing a work vehicle. [Diagram 2] FIG. 2 is a plan view showing the work vehicle. [Diagram 3]FIG. 3 is a block diagram showing a control system centered on the control device of the seedling transplanter. [Figure 4] FIG. 4 is an explanatory diagram of the autonomous driving of the seedling transplanter in a farm field. [Diagram 5] FIG. 5 is a diagram showing a method for setting the reference start point (point A). [Figure 6] FIG. 6 is a diagram showing a state in which the seedling transplanter is not facing in a direction perpendicular to the ridge. [Figure 7] FIG. 7 is a diagram showing a method for setting the reference end point (point B). [Figure 8] FIG. 8 is a flowchart illustrating the reference start point setting process according to the embodiment. [Figure 9] FIG. 9 is a flowchart illustrating the reference end point setting process according to the embodiment. [Figure 10] FIG. 10 is a diagram illustrating an example of mapping of point cloud data. [Figure 11] FIG. 11 is a side view of the walk-behind seedling transplanter. [Figure 12] FIG. 12 is a diagram for explaining reverse movement along a line that has been divided in between. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a work vehicle disclosed in the present application will be described in detail with reference to the accompanying drawings. Note that the present invention is not limited to the embodiment described below.

[0010] <Overview of the work vehicle> First, an overview of a work vehicle 1 according to an embodiment will be described with reference to Figures 1 and 2. Figure 1 is a side view showing the work vehicle 1. Figure 2 is a plan view showing the work vehicle 1.

[0011] In the following description, the forward / rearward direction is the direction of travel of the work vehicle 1 when traveling straight, with the forward side in the direction of travel being defined as "front" and the rear side being defined as "rear." The forward direction of the work vehicle 1 is the direction from the driver's seat 41 toward the handle 35 (steering device) when traveling straight (see Figures 1 and 2).

[0012] The left-right direction is a direction that is horizontally perpendicular to the front-rear direction and defines left and right facing the "front." In other words, when a pilot (also called an operator) is seated in the pilot's seat 41 and facing forward, the left hand side is the "left" and the right hand side is the "right."

[0013] The up-down direction is the vertical direction. The front-rear direction, the left-right direction, and the up-down direction are perpendicular to each other. Each direction is defined for the convenience of explanation, and the present invention is not limited to these directions.

[0014] In the following description, the work vehicle 1 may be referred to as the "machine body." In the embodiment, the work vehicle is described as a riding seedling transplanter 1 equipped with a seedling planting unit 4 as a field work device and adapted to receive seedlings in a field. As shown in Figs. 1 and 2, the seedling transplanter 1 is equipped with the seedling planting unit 4, which can be raised and lowered via a lifting link mechanism 3 on the rear side of the traveling body 2, for planting seedlings in a field.

[0015] A main body of the fertilizer applicator 5 is disposed on the upper rear side of the traveling body 2. When the work vehicle is not the seedling transplanter 1, a sowing device for supplying seeds or the like may be provided as a work device.

[0016] The traveling body 2 is a four-wheel drive vehicle equipped with left and right front wheels 10 and rear wheels 11, which are traveling wheels and driving wheels. On the front side of the main frame 15 constituting the body skeleton of the traveling body 2, there are provided a transmission case 13 that transmits driving force to the seedling planting section 4 and the like, and a hydraulic continuously variable transmission 14 that outputs the driving force supplied from the engine 30, i.e., the rotation generated by the engine 30, to the transmission case 13.

[0017] The continuously variable transmission 14 is a hydrostatic continuously variable transmission known as HST (Hydro Static Transmission). In the following, a case where the continuously variable transmission is the HST 14 will be described.

[0018] An auxiliary transmission mechanism 16 is provided in the transmission case 13 for switching the driving mode of the traveling vehicle body 2 between high-speed mode for road driving and low-speed mode for planting seedlings. Front wheel final cases 10a are provided on the left and right sides of the transmission case 13, and front wheels 10 are attached to left and right front axles 10b that protrude outward from front wheel support parts that can change the steering direction of the left and right front wheel final cases 10a.

[0019] In addition, rear wheel gear cases 11a are attached to both the left and right sides of a rear frame 22 (see Figure 2) that is provided on the rear side of the main frame 15 in the lateral direction of the vehicle body, and rear wheels 11 (running wheels) are attached to left and right rear axles 11b that protrude outward from the rear wheel gear case 11a, respectively.

[0020] Left and right link support frames 23 that support the lifting link mechanism 3 protrude upward from the upper part of the rear frame 22. A pair of left and right lower link arms 24 are provided below and between the left and right link support frames 23. A hydraulically operated lifting cylinder 25 (lifting device) is provided between the left and right lower link arms 24.

[0021] An upper link arm 26 is provided above the lifting cylinder 25, forming a parallel link mechanism, the lifting link mechanism 3. The left and right lower link arms 24, the lifting cylinder 25, and the other end of the upper link arm 26, each of which has one end connected to the traveling body 2, are attached to the front of the seedling planting section 4.

[0022] In addition, an engine 30 is mounted on the main frame 15. Rotational power of the engine 30 is transmitted to the transmission case 13 via the belt transmission device 21 and the HST 14. The rotational power transmitted to the transmission case 13 is changed in speed by the sub-transmission mechanism 16 in the transmission case 13, and then separated into traveling power and externally extracted power.

[0023] The rotational power of the engine 30 is transmitted to a hydraulic pump (not shown). The hydraulic pressure generated by the hydraulic pump is supplied to the HST 14, a power steering mechanism 88 (see FIG. 3) of the handle 35, the lift cylinder 25, etc.

[0024] The external extraction power extracted from the rotational power transmitted to the transmission case 13 is transmitted to a planting clutch case 27 provided at the rear of the running body 2, and transmitted from the planting clutch case 27 to the seedling planting section 4 via a planting transmission shaft 67.

[0025] Meanwhile, left and right drive shafts 42 are provided at the rear of the transmission case 13. Rotational power from the engine 30 is transmitted via the transmission case 13 and the drive shafts 42 to the left and right rear wheel gear cases 11a.

[0026] A side clutch 44 (see FIG. 3) that switches on and off the power transmission to the left and right drive shafts 42 is disposed upstream in the transmission direction from the left and right drive shafts 42. As shown in FIG. 1, a side clutch pedal 43a that switches on and off the left and right side clutches 44 is provided at the lower front side of the cockpit 41 and on one of the left and right sides.

[0027] Of the left and right side clutch pedals 43a, when the side clutch pedal 43a on the inside of the turn is depressed to disengage the side clutch 44, and then the steering wheel 35 is operated to make a turn, the drive rotation of the rear wheel 11 on the inside of the turn can be completely cut off.

[0028] A bonnet 39 with an operation panel 38 arranged on top for operating each part is provided on the upper front side of the traveling body 2. The operation panel 38 is provided with a monitor 86 (see FIG. 3) and the like.

[0029] The bonnet 39 is also provided with a handlebar 35 for steering the machine, a speed change lever 36 for operating the HST 14 and the seedling planting section 4, and an auxiliary speed change lever 37 for operating the auxiliary speed change mechanism 16 (vehicle speed adjustment mechanism).

[0030] In addition, an openable and closable front cover 40 is provided in front of the bonnet 39. Inside the front cover 40, a fuel tank, a battery, and an interlocking mechanism for rotating the left and right front wheels 10 and the lower sides of the left and right front wheel final cases 10a in response to steering of the handlebars 35 are provided.

[0031] An engine cover 30a that covers the top and sides of the engine 30 is provided behind the bonnet 39 of the aircraft and above the engine 30, and a cockpit 41 where the pilot is seated is provided above the engine cover 30a.

[0032] The fertilizer applicator 5 is provided behind the driver's seat 41 and at the rear end side of the main frame 15. The driving force of the fertilizer applicator 5 is transmitted by a fertilizer transmission mechanism provided to face the fertilizer applicator 5 from one of the left and right rear wheel gear cases 11a.

[0033] A substantially horizontal floor step 33 is formed on both the left and right sides of the lower portion of the engine cover 30a and the bonnet 39. As shown in Fig. 2, the floor step 33 is partially lattice-shaped, so that even if mud on the shoes of an operator walking on the floor step 33 falls, the fallen mud falls into the field.

[0034] 2, a rear step 330 is connected to the rear of the floor step 33. It is preferable that the surface of the rear step 330 is subjected to an anti-slip treatment, for example, a pattern of multiple projections, so that the feet do not easily slip during work.

[0035] In addition, at the front of the traveling body 2, on both the left and right sides, spare seedling frames 50 are provided, in which multiple spare seedling carrying platforms 52 are arranged at intervals in the vertical direction on seedling frame supports 51, so that work materials such as seedlings and fertilizer bags to be replenished in the seedling planting section 4 can be placed on them.

[0036] A seedling tank 53 for carrying seedlings to be planted in the field is attached to the rear end of the lifting link mechanism 3 together with a sliding mechanism for sliding it left and right. Seedling partition fences 54 that are long in the vertical direction are placed on the seedling tank 53 at predetermined intervals in the horizontal direction. A seedling planting device 55 is placed below the seedling tank 53 to pick up the seedlings loaded therein and plant them in the field.

[0037] The seedling planting device 55 plants the same number of seedling rows as those separated by the seedling partition fence 54, i.e., eight rows at a time. Four planting transmission cases 56 are arranged at intervals below the seedling tank 53, and planting rotaries 57 are attached to both the left and right sides of the planting transmission cases 56, which rotate to pick up seedlings using planting rods 58 and plant them in the field.

[0038] In the fertilizer applicator 5, the fertilizer hopper 70 in which the fertilizer is stored is divided into the same number of sections as the number of working rows in the seedling planting section 4 (8 rows in the example shown in FIG. 2). Since the fertilizer hopper 70 with 8 rows is long in the left-right direction and therefore the convenience of adding fertilizer and attaching and detaching it is reduced, the fertilizer hopper 70 may have a so-called side fertilizer application structure in which sections divided into 4 rows are arranged on each side.

[0039] A payout device 71 that supplies a set amount of fertilizer at each row is provided below the fertilizer hopper 70. A ventilation duct 72 through which conveying air that moves the fertilizer passes is provided on the left and right sides of the machine body below the payout device 71. A fertilizer hose 73 that guides fertilizer to the vicinity of the seedling planting position in the seedling planting section 4 is provided below the payout device 71. In addition, a blower 74 that is operated by an electric blower motor 76 to generate conveying air is provided at one end of the ventilation duct 72 on the machine body.

[0040] 1 and 2, a center float 62C that slides on the field surface and two side floats 62L and 62R are provided rotatably around an axis below the seedling planting section 4. The center float 62C and the left and right side floats 62L and 62R are sometimes collectively referred to as floats 62.

[0041] In addition, below the seedling planting section 4, and ahead of the float 62, a ground leveling rotor 63 for leveling unevenness in the field is provided. Driving force is transmitted to the ground leveling rotor 63 from the rear wheel gear case 11a on the other left and right sides via a rotor transmission shaft 63a.

[0042] 1, line drawing markers 65 are provided on the left and right sides of the seedling planting section 4, one of which comes into contact with the field surface to form a groove that serves as a guide for traveling in the next work row (next process). For example, when the seedling planting section 4 is raised during a turn, the left and right line drawing markers 65 move upward on both the left and right sides, and when the seedling planting section 4 is lowered after the turn, one of the left and right sides moves upward and the other side comes into contact with the ground.

[0043] 1 and 2, a center mascot 66 that is long in the vertical direction is provided in the left-right center of the traveling body 2 and in front of the bonnet 39. By aligning the center mascot 66 with the grooves formed in the field by the left and right line markers 65, it becomes possible to travel in accordance with the work position of the previous work row, improving work accuracy and preventing non-working.

[0044] Depending on the soil quality of the field, the guide lines formed by the left and right line-drawing markers 65 may quickly become buried, causing the guide for going straight to disappear. In such a case, it is advisable to use the left and right side markers 19, which are provided further forward on the machine body than the left and right line-drawing markers 65. In other words, by moving the left and right side markers 19 toward the outside of the machine body and positioning the side markers 19 above the planted seedlings, planting work can be performed in accordance with the planting of the seedlings in the previous work row.

[0045] As shown in FIG. 1, the seedling transplanter 1 includes a position acquisition device 150. The position acquisition device 150 acquires the current position of the seedling transplanter 1. The position acquisition device 150 acquires a turning position in the field and detects the distance to the turning position. The position acquisition device 150 is, for example, a camera, an ultrasonic sensor, or a direction sensor. The position acquisition device 150 may also receive positioning information from a positioning means such as a Global Positioning System (GPS) or a Global Navigation Satellite System (GNSS). The position acquisition device 150 may be composed of multiple devices.

[0046] For example, the position acquisition device 150 measures the distance to the ridge and the distance to the turning position. Also, for example, the position acquisition device 150 receives positioning information from the positioning means, and creates and acquires the current position information of the vehicle based on the received positioning information. The position acquisition device 150 is attached to the mounting stay 59, for example, and disposed above the traveling vehicle body 2.

[0047] A straight-line control program and a turning control program, which are created based on position information from position acquisition device 150, are stored in different locations. The straight-line control program is stored, for example, in a straight-line control ECU (Electronic Control Unit) 100a in position acquisition device 150, and the turning control program is stored, for example, in a turning control ECU 100b housed in bonnet 39. Note that straight-line control ECU 100a and turning control ECU 100b are included in a control device 100 (see FIG. 3) described later.

[0048] The seedling transplanter 1 further includes a first distance sensor 160 to a sixth distance sensor 165. The first distance sensor 160 to the sixth distance sensor 165 are, for example, an infrared sensor, an ultrasonic sensor, a laser sensor, or the like.

[0049] The first distance sensor 160 is provided on the rear side of the seedling transplanter 1, at the center in the left-right direction of the seedling transplanter 1. The first distance sensor 160 is provided on a first orthogonal line perpendicular to the front-rear direction of the seedling transplanter 1. The first orthogonal line is a line along the left-right direction. The first distance sensor 160 measures the shortest distance (distance L1) from the first distance sensor 160 to a first point where the distance to the ridge behind the seedling transplanter 1 is the shortest.

[0050] The second distance sensor 161 is provided on the rear side of the seedling transplanter 1. The second distance sensor 161 is provided to the left of the first distance sensor 160. The second distance sensor 161 is provided on a first orthogonal line. The second distance sensor 161 is provided so that the distance from the first distance sensor 160 is a first predetermined distance M1. The first predetermined distance M1 is a distance that is set in advance.

[0051] The second distance sensor 161 measures a distance L2 from the second distance sensor 161 to a second point which is the ridge behind the seedling transplanter 1 in a direction parallel to the front-rear direction.

[0052] The third distance sensor 162 is provided on the rear side of the seedling transplanter 1. The third distance sensor 162 is provided to the right of the first distance sensor 160. The third distance sensor 162 is provided on a first orthogonal line. The third distance sensor 162 is provided at a first predetermined distance M1 from the first distance sensor 160 and on the opposite side of the first distance sensor 160 to the second distance sensor 161. In other words, the second distance sensor 161 and the third distance sensor 162 are provided symmetrically on the left and right sides of the first distance sensor 160.

[0053] The third distance sensor 162 measures a distance L3 from the third distance sensor 162 to a third point, which is the ridge behind the seedling transplanter 1, in a direction parallel to the front-rear direction.

[0054] The fourth distance sensor 163 is provided on the front side of the seedling transplanter 1, at the center in the left-right direction of the seedling transplanter 1. The fourth distance sensor 163 is provided on a second orthogonal line perpendicular to the front-rear direction of the seedling transplanter 1. The second orthogonal line is a line along the left-right direction. The fourth distance sensor 163 measures the shortest distance (distance L4) from the fourth distance sensor 163 to a fourth point where the distance to the ridge in front of the seedling transplanter 1 is the shortest.

[0055] The fifth distance sensor 164 is provided on the front side of the seedling transplanter 1. The fifth distance sensor 164 is provided to the left of the fourth distance sensor 163. The fourth distance sensor 163 is provided on the second orthogonal line. The fifth distance sensor 164 is provided so that the distance from the fourth distance sensor 163 is a second predetermined distance M2. The second predetermined distance M2 is a distance set in advance.

[0056] The fifth distance sensor 164 measures a distance L5 from the fifth distance sensor 164 to a fifth point which is the ridge behind the seedling transplanter 1 in a direction parallel to the front-rear direction.

[0057] The sixth distance sensor 165 is provided on the front side of the seedling transplanter 1. The sixth distance sensor 165 is provided to the right of the fourth distance sensor 163. The sixth distance sensor 165 is provided on the second orthogonal line. The sixth distance sensor 165 is provided such that the distance from the fourth distance sensor 163 is the second predetermined distance M2, and the sixth distance sensor 165 is provided on the opposite side of the fourth distance sensor 163 to the fifth distance sensor 164. In other words, the fifth distance sensor 164 and the sixth distance sensor 165 are provided symmetrically with respect to the fourth distance sensor 163.

[0058] The sixth distance sensor 165 measures a distance L6 from the sixth distance sensor 165 to a sixth point which is the ridge behind the seedling transplanter 1 in a direction parallel to the front-rear direction.

[0059] <Work vehicle control system> Next, the control system of the seedling transplanter 1 will be described with reference to Fig. 3. Fig. 3 is a block diagram showing the control system centered on the control device 100 of the seedling transplanter 1. The seedling transplanter 1 is capable of controlling each part by electronic control, and is equipped with a control device (hereinafter referred to as a controller) 100 that controls each part.

[0060] The controller 100 is provided with a processing section having a CPU (Central Processing Unit) and the like, a storage section such as a ROM (Read Only Memory) and a RAM (Random Access Memory), and an input / output section, which are connected to each other and can exchange signals with each other. The storage section stores computer programs and the like for controlling the seedling transplanter 1. The controller 100 performs each function by reading out the computer programs and the like stored in the storage section.

[0061] The controller 100 is connected to actuators such as a throttle motor 80, hydraulic control valves 81, 82, a planting clutch actuation solenoid 83, a side clutch actuation solenoid 84, an HST motor 85, a line drawing marker lifting motor 87, and a steering motor 95 (motor).

[0062] The throttle motor 80 increases or decreases the rotation speed of the output shaft of the engine 30 by operating a throttle that adjusts the amount of intake air of the engine 30. The hydraulic control valve 81 controls the extension and contraction operation of the lift cylinder 25. The hydraulic control valve 82 controls the power steering mechanism 88. The planting clutch operating solenoid 83 operates the planting clutch 27a.

[0063] The side clutch actuation solenoid 84 actuates the side clutch 44 which switches the state of power transmission to the rear wheels 11 (see FIG. 1). The side clutch 44 is provided on each of the left and right rear wheels 11, and two side clutch actuation solenoids 84 are provided corresponding to each side clutch 44.

[0064] The HST motor 85 changes the rotation angle of the trunnion of the HST 14, thereby changing the inclination angle of the swash plate of the HST 14. The steering motor 95 is a motor that drives the handle 35, which is a steering device that adjusts the steering amount (steering angle) of the front wheels 10 (see FIG. 1), which are the traveling wheels, when automatic turning control is performed. The steering motor 95 rotates the handle 35. The line drawing marker lifting motor 87 lifts and lowers the line drawing marker 65.

[0065] The controller 100 is connected to a rotation speed sensor 90, a steering amount sensor 91, a line drawing marker detection sensor 93, etc. In addition, the controller 100 is connected to a first distance sensor 160 to a sixth distance sensor 165.

[0066] Two rotation speed sensors 90 are provided corresponding to the left and right rear wheels 11, which are traveling wheels, and detect the rotation speeds of the left and right rear wheels 11. The rotation speed sensors 90 may detect the rotation speeds of the left and right front wheels 10.

[0067] The steering amount sensor 91 detects the amount of operation of the steering wheel 35, which is a steering device, i.e., the amount of steering (steering angle) of the front wheels 10. The steering amount is detected in both the left and right directions, with the case where the amount of operation of the steering wheel 35 is zero being taken as a reference position (center position), that is, with the reference position being when the traveling vehicle body 2 is traveling straight ahead.

[0068] The line drawing marker detection sensor 93 is provided for each of the left and right line drawing markers 65, and detects the position of the line drawing marker 65. When the line drawing marker 65 is in a predetermined elevated position, the line drawing marker detection sensor 93 detects that the line drawing marker 65 is in a non-working state. When the line drawing marker 65 descends from the predetermined elevated position, the line drawing marker detection sensor 93 detects that the line drawing marker 65 is in contact with the ground and in a working state.

[0069] In addition, signals are input to the controller 100 as operation signals from the speed change operation lever 36, the sub-speed change operation lever 37, the straight mode switch 46 (operation unit), the planting unit lifting / lowering switch 47, the reference line setting switch 48, and the like.

[0070] The straight-line mode switch 46 is a switch for switching whether or not automatic straight-line driving is performed. Specifically, the straight-line mode switch 46 is a switch for selecting whether manual operation in which the steering wheel 35 is operated by an operator is performed, or automatic straight-line driving in which the steering motor 95 is controlled to operate the steering wheel 35 is performed. When the straight-line mode switch 46 is "ON," automatic straight-line driving can be performed. When the straight-line mode switch 46 is "OFF," automatic straight-line driving is not performed, and manual operation is performed.

[0071] The planting section lifting switch 47 is a switch for switching whether to lift or lower the seedling planting section 4. The planting section lifting switch 47 is changed to the "up" and "down" positions.

[0072] When the planting unit lift switch 47 is in the "up" position, the seedling planting unit 4 is lifted to a predetermined lifted position (non-working position) and the seedling planting device 55 is stopped. When the planting unit lift switch 47 is in the "down" position, the seedling planting unit 4 is lowered to a predetermined lowered position (working position) and the seedling planting device 55 is activated.

[0073] The reference line setting switch 48 is a switch for setting a reference line R0 that serves as a driving reference for automatic straight driving. When the reference line setting switch 48 is "ON", it becomes possible to set the reference line R0. The method for setting the reference line R0 will be described later.

[0074] Additionally, current position information of the machine and the like are input to the controller 100 from the position acquisition device 150. The controller 100 executes an autonomous driving mode in which the machine performs work while traveling autonomously.

[0075] <Autonomous driving mode> Here, referring to Fig. 4, the autonomous travel in the field by the seedling transplanter 1 will be described. Fig. 4 is an explanatory diagram of the autonomous travel in the field of the seedling transplanter 1. The controller 100 (see Fig. 3) has an automatic straight-line mode as an autonomous travel mode in which the steering motor 95 (see Fig. 3) is controlled to operate the handle 35 (see Fig. 3) while feeding back the steering amount of the front wheels 10 (see Fig. 1). The seedling transplanter 1 may be capable of automatic turning, which automatically performs turning travel along a turning travel path R2.

[0076] As shown in FIG. 4, in the automatic straight-line mode, the seedling transplanter 1 automatically performs the work of planting seedlings in a farm field while moving straight along a planned travel route, for example.

[0077] The seedling transplanter 1 plants seedlings while traveling back and forth within a predetermined work area in a farm field. In this case, for straight-line travel, the controller 100 executes the automatic straight-line mode and executes straight-line assistance, so that the machine automatically travels along a set straight-line travel route R1.

[0078] The straight travel path R1 is parallel to a reference line R0 that serves as a travel reference. The reference line R0 is set in the field in accordance with the planting direction of the seedlings. The controller 100 acquires the start position of the straight travel as a reference start point (point A) that is a start reference point. The controller 100 also acquires the end position of the straight travel as a reference end point (point B) that is an end reference point. The controller 100 then stores the line segment connecting points A and B as the reference line R0.

[0079] The reference line R0 is updated when the reference start point (point A) and the reference end point (point B) of the straight-line driving are updated. In addition, the straight-line driving path R1 in the next process is set parallel to the updated reference line R0.

[0080] The seedling transplanter 1 may set the reference start point (point A) and the reference end point (point B) of the straight travel based on the current position information of the machine acquired from the position acquisition device 150.

[0081] However, if the current position information of the machine cannot be acquired by the position acquisition device 150, the seedling transplanter 1 cannot set the reference start point (point A) and the reference end point (point B). Furthermore, if the seedling transplanter 1 does not have the position acquisition device 150, it cannot set the reference start point (point A) and the reference end point (point B).

[0082] The seedling transplanter 1 according to this embodiment sets a reference start point (point A) and a reference end point (point B) by the following method. The seedling transplanter 1 sets the reference start point (point A) using the first distance sensor 160 to the third distance sensor 162.

[0083] Here, a method for setting the reference start point (point A) will be described with reference to Fig. 5. Fig. 5 is a diagram showing a method for setting the reference start point (point A). The controller 100 measures a distance L1 to a first point by the first distance sensor 160. The controller 100 also measures a distance L2 to a second point by the second distance sensor 161. The controller 100 also measures a distance L3 to a third point by the third distance sensor 162.

[0084] The controller 100 calculates the distance N1 from the first distance sensor 160 to the second point using the distance L2 and the first predetermined distance M1 according to the formula (1).

[0085] N1=(L2 2 +M1 2 ) 1 / 2 (1)

[0086] The controller 100 calculates a first distance P1 from the first point to the second point using the distance L1 and the distance N1 according to the formula (2).

[0087] P1=(N1 2 -L1 2 ) 1 / 2 (2)

[0088] The controller 100 calculates the distance N2 from the first distance sensor 160 to the third point using the distance L3 and the first predetermined distance M1 according to equation (3).

[0089] N2=(L3 2 +M1 2 ) 1 / 2 (3)

[0090] The controller 100 calculates a second distance P2 from the first point to the third point using the distance L1 and the distance N2 according to equation (4).

[0091] P2=(N2 2 -L1 2 ) 1 / 2 (4)

[0092] When the first distance P1 and the second distance P2 are equal and the seedling planting unit 4 reaches a predetermined lowered position, the controller 100 determines that the seedling transplanter 1 is facing in a direction perpendicular to the ridge and that planting has started. When the first distance P1 and the second distance P2 are equal and the seedling planting unit 4 reaches a predetermined lowered position, the controller 100 sets the reference start point (point A).

[0093] For example, as shown in Fig. 6, when the seedling transplanter 1 is not facing in a direction perpendicular to the ridge, the first distance P1 and the second distance P2 are not equal. In such a case, the controller 100 does not set the reference start point (point A). Fig. 6 is a diagram showing a state in which the seedling transplanter 1 is not facing in a direction perpendicular to the ridge.

[0094] Next, a method for setting the reference end point (point B) will be described with reference to Fig. 7. Fig. 7 is a diagram showing a method for setting the reference end point (point B). The controller 100 measures a distance L4 to a fourth point by the fourth distance sensor 163. The controller 100 also measures a distance L5 to a fifth point by the fifth distance sensor 164. The controller 100 also measures a distance L6 to a sixth point by the sixth distance sensor 165.

[0095] The controller 100 calculates the distance N3 from the fourth distance sensor 163 to the fifth point using the distance L5 and the second predetermined distance M2 according to equation (5).

[0096] N3=(L5 2 +M2 2 ) 1 / 2 (5)

[0097] The controller 100 calculates a third distance P3 from the fourth point to the fifth point using the distance L4 and the distance N3 according to the formula (6).

[0098] P3=(N3 2 -L4 2 ) 1 / 2 (6)

[0099] The controller 100 calculates the distance N4 from the fourth distance sensor 163 to the sixth point using the distance L6 and the second predetermined distance M2 according to equation (7).

[0100] N4=(L6 2 +M2 2 ) 1 / 2 (7)

[0101] The controller 100 calculates a fourth distance P4 from the fourth point to the sixth point using the distance L4 and the distance N4 according to equation (8).

[0102] P4=(N4 2 -L4 2 ) 1 / 2 (8)

[0103] The controller 100 determines that the seedling transplanter 1 has started turning when the state in which the third distance P3 and the fourth distance P4 are equal changes to the state in which the third distance P3 and the fourth distance P4 are not equal and the seedling planting unit 4 reaches a predetermined raised position. The controller 100 then sets the reference end point (point B) when the state in which the third distance P3 and the fourth distance P4 are not equal and the seedling planting unit 4 reaches a predetermined raised position.

[0104] In this manner, the controller 100 sets the reference start point (point A) and the reference end point (point B), and sets the reference line R0.

[0105] In addition, when the straight-line mode switch 46 is ON, the first distance P1 is equal to the second distance P2, and the seedling planting section 4 is in a predetermined lowered position, the controller 100 automatically travels along the straight-line travel path R1.

[0106] Furthermore, when the straight mode switch 46 is ON and the first distance P1 and the second distance P2 are not equal, the controller 100 does not perform automatic travel along the straight travel path R1. In other words, even if the straight mode switch 46 is ON, when the first distance P1 and the second distance P2 are not equal, the controller 100 determines that the seedling transplanter 1 is not facing in a direction perpendicular to the ridge and is not facing in a direction along the straight travel path R1, and does not start automatic travel.

[0107] In addition, when the straight mode switch 46 is ON and the seedling planting unit 4 is not in a predetermined lowered position, the controller 100 does not perform automatic travel along the straight travel path R1. That is, even if the straight mode switch 46 is ON, the controller 100 determines that the seedling planting unit 4 is not ready to plant seedlings, and does not start automatic travel.

[0108] The reference start point setting process according to the embodiment will be described with reference to Fig. 8. Fig. 8 is a flowchart illustrating the reference start point setting process according to the embodiment.

[0109] The controller 100 determines whether or not the reference line setting switch 48 is "ON" (S100). If the reference line setting switch 48 is "OFF" (S100: No), the controller 100 ends the current process.

[0110] When the reference line setting switch 48 is "ON" (S100: Yes), the controller 100 calculates the first distance P1 and the second distance P2 (S101).

[0111] Next, the controller 100 determines whether the first distance P1 and the second distance P2 are equal to each other (S102).

[0112] If the first distance P1 and the second distance P2 are not equal (S102: No), the controller 100 notifies the user that the first distance P1 and the second distance P2 are not equal (S103). For example, the controller 100 displays on the monitor 86 that the first distance P1 and the second distance P2 are not equal. Next, the controller 100 returns to step S101 and repeats the above process.

[0113] When the first distance P1 and the second distance P2 are equal (S102: Yes), the controller 100 judges whether the seedling planting section 4 is in the predetermined lowered position (S104). When the seedling planting section 4 is not in the predetermined lowered position (S104: No), the controller 100 notifies the user that the seedling planting section 4 is not in the predetermined lowered position (S105). For example, the controller 100 displays on the monitor 86 that the seedling planting section 4 is not in the predetermined lowered position. Next, the controller 100 returns to step S104 and repeats the above process.

[0114] When the seedling planting section 4 is at the predetermined lowered position (S104: Yes), the controller 100 sets the reference start point (point A) (S106).

[0115] The reference end point setting process according to the embodiment will be described with reference to Fig. 9. Fig. 9 is a flowchart for explaining the reference end point setting process according to the embodiment. Here, it is assumed that the seedling transplanter 1 is operated by the operator and travels perpendicular to the ridge. In other words, it is assumed that the third distance P3 and the fourth distance P4 are equal to each other.

[0116] The controller 100 determines whether the reference line setting switch 48 is "ON" (S200). If the reference line setting switch 48 is "OFF" (S200: No), the controller 100 ends the current process.

[0117] When the reference line setting switch 48 is "ON" (S200: Yes), the controller 100 calculates the third distance P3 and the fourth distance P4 (S201).

[0118] Next, the controller 100 determines whether the third distance P3 is equal to the fourth distance P4 (S202).

[0119] If the third distance P3 and the fourth distance P4 are equal (S202: Yes), the controller 100 returns to step S201 and repeats the above processing.

[0120] If the third distance P3 and the fourth distance P4 are not equal (S202: No), the controller 100 determines whether the seedling planting section 4 is at a predetermined raised position (S203).

[0121] If the seedling planting unit 4 is not at the predetermined raised position (S203: No), the controller 100 repeats the process of step S203. If the third distance P3 and the fourth distance P4 are not equal and the seedling planting unit 4 is not at the predetermined raised position, for example, when the seedling transplanter 1 is planting seedlings, it is temporarily shifted from a direction perpendicular to the ridge.

[0122] When the seedling planting section 4 is at the predetermined raised position (S203: Yes), the controller 100 sets the reference end point (point B) (S204).

[0123] As described above, the controller 100 sets the reference line R0 after setting the reference start point (point A) and the reference end point (point B).

[0124] The seedling transplanter 1 includes a first distance sensor 160, a second distance sensor 161, a third distance sensor 162, a handle 35, and a controller 100. The first distance sensor 160 is provided on the rear side of the seedling transplanter 1, in the center of the seedling transplanter 1 in the left-right direction, and on a first orthogonal line perpendicular to the front-rear direction of the seedling transplanter 1. The second distance sensor 161 is provided on the first orthogonal line and is provided so that the distance from the first distance sensor 160 is a first predetermined distance M1. The third distance sensor 162 is provided on the first orthogonal line and is provided so that the distance from the first distance sensor 160 is the first predetermined distance M1, and is provided on the opposite side of the second distance sensor 161 with respect to the first distance sensor 160. The handle 35 adjusts the steering amount of the front wheels 10 of the seedling transplanter 1. The controller 100 can execute a straight-line assist to automatically move the seedling transplanter 1 straight by controlling the handle 35. The first distance sensor 160 measures the shortest distance (distance L1) from the first distance sensor 160 to the first point, which is the shortest distance to the ridge behind the seedling transplanter 1. The second distance sensor 161 measures the distance L2 from the second distance sensor 161 to the second point, which is the ridge behind the seedling transplanter 1, in a direction parallel to the front-rear direction. The third distance sensor 162 measures the distance L3 from the third distance sensor 162 to the third point, which is the ridge behind the seedling transplanter 1, in a direction parallel to the front-rear direction. The controller 100 calculates the first distance P1 from the first point to the second point, and the second distance P2 from the first point to the third point. The controller 100 sets the reference start point (point A) of the straight travel when the seedling planting unit 4 reaches a predetermined lowering position with the first distance P1 and the second distance P2 being equal.

[0125] This allows the seedling transplanter 1 to set the reference start point (point A) for straight-ahead travel even when position information cannot be acquired by the position acquisition device 150 or when the seedling transplanter 1 does not have the position acquisition device 150. For example, the seedling transplanter 1 can accurately set the reference start point (point A) of the reference line R0 that is set in a direction perpendicular to the ridge.

[0126] The seedling transplanter 1 also includes a fourth distance sensor 163, a fifth distance sensor 164, and a sixth distance sensor 165. The fourth distance sensor 163 is provided on the front side of the seedling transplanter 1, in the center in the left-right direction, and on a second orthogonal line perpendicular to the front-rear direction of the seedling transplanter 1. The fifth distance sensor 164 is provided on the second orthogonal line and is provided so that the distance from the fourth distance sensor 163 is the second predetermined distance M2. The sixth distance sensor 165 is provided on the second orthogonal line and is provided so that the distance from the fifth distance sensor 164 is the second predetermined distance M2, and is provided on the opposite side of the fifth distance sensor 164 to the fourth distance sensor 163. The fourth distance sensor 163 measures the shortest distance (distance L4) from the fourth distance sensor 163 to the ridge in front of the seedling transplanter 1. The fifth distance sensor 164 measures a distance L5 from the fifth distance sensor 164 to a fifth point, which is a ridge in front of the seedling transplanter 1, in a direction parallel to the front-rear direction. The sixth distance sensor 165 measures a distance L6 from the sixth distance sensor 165 to a sixth point, which is a ridge in front of the seedling transplanter 1, in a direction parallel to the front-rear direction. The controller 100 calculates a third distance P3 from the fourth point to the fifth point, and a fourth distance P4 from the fourth point to the sixth point. The controller 100 sets a reference end point (point B) of the straight travel when the third distance P3 and the fourth distance P4 change from being equal to being equal to each other to being unequal to each other and the seedling planting unit 4 reaches a predetermined raised position.

[0127] This allows the seedling transplanter 1 to set the reference end point (point B) of straight-ahead travel even when position information cannot be acquired by the position acquisition device 150 or when the seedling transplanter 1 does not have the position acquisition device 150. For example, the seedling transplanter 1 can accurately set the reference end point (point B) of the reference line R0 that is set in a direction perpendicular to the ridge.

[0128] The seedling transplanter 1 is equipped with a straight-line mode switch 46. The straight-line mode switch 46 accepts ON and OFF operations of automatic straight-line movement. The controller 100 starts automatic straight-line movement when the straight-line mode switch 46 is "ON", the first distance P1 is equal to the second distance P2, and the seedling planting unit 4 is at a predetermined lowered position. In addition, the controller 100 does not start automatic straight-line movement when the straight-line mode switch 46 is "ON", the first distance P1 is not equal to the second distance P2, or the seedling planting unit 4 is not at a predetermined lowered position.

[0129] As a result, the seedling transplanter 1 can start automatic straight travel when the seedling transplanter 1 faces a direction perpendicular to the ridge and the seedling planting unit 4 is ready to plant seedlings. Therefore, the seedling transplanter 1 can improve the accuracy of seedling planting by automatic straight travel. In addition, when the seedling transplanter 1 starts automatic straight travel after manual planting by the operator's operation, for example, the seedling transplanter 1 can start planting by automatic straight travel with the seedling transplanter 1 facing a direction perpendicular to the ridge. In addition, even if the straight travel mode switch 46 is set to "ON", the seedling transplanter 1 does not start automatic straight travel when, for example, the first distance P1 and the second distance P2 are not equal, so that safety can be improved compared to the case where automatic straight travel is started when the straight travel mode switch 46 is set to "ON".

[0130] The seedling transplanter 1 in the modified example detects the rotation speed of the left and right front wheels 10 or the left and right rear wheels 11 using the rotation speed sensor 90, and may obtain the reference starting point (point A) for straight-ahead travel, for example, when the rotation speed of the left and right front wheels 10 is below a threshold value and the seedling planting section 4 is in a predetermined descending position.

[0131] As a result, the seedling transplanter 1 can set the reference start point (point A) for straight travel even when the position acquisition device 150 cannot acquire position information or when the position acquisition device 150 is not provided.

[0132] The seedling transplanter 1 in the modified example detects the rotation speed of the left and right front wheels 10 or the left and right rear wheels 11 using the rotation speed sensor 90, and may obtain the reference end point (point B) of straight-ahead travel, for example, when the rotation speed of the left and right front wheels 10 is greater than a threshold value and the seedling planting section 4 is in a predetermined raised position.

[0133] As a result, the seedling transplanter 1 can set the reference end point (point B) of straight travel even when the position acquisition device 150 cannot acquire position information or when the position acquisition device 150 is not provided.

[0134] The seedling transplanter 1 in the modified example may obtain a reference end point (point B) of straight-ahead travel when the operation amount of the handle 35 is in the neutral position, i.e., a position outside a predetermined range from the straight-ahead position, and the seedling planting part 4 is in a predetermined raised position.

[0135] As a result, the seedling transplanter 1 can set the reference end point (point B) of straight travel even when the position acquisition device 150 cannot acquire position information or when the position acquisition device 150 is not provided.

[0136] The seedling transplanter 1 according to the modified example may start automatic straight-line driving when the operation amount of the handle 35 is within a predetermined range and the vehicle speed is equal to or higher than a predetermined vehicle speed. The vehicle speed is detected, for example, by the number of rotations detected by the rotation speed sensor 90.

[0137] The seedling transplanter 1 according to the modified example may set a straight line in the automatic straight movement by the following method without setting a reference start point (point A) and a reference end point (point B).

[0138] Specifically, the controller 100 acquires the current position information of the seedling transplanter 1 by the position acquisition device 150 every time the seedling transplanter 1 travels a predetermined distance. For example, the controller 100 calculates the travel distance of the seedling transplanter 1 based on the number of rotations detected by the number of rotations sensor 90. Then, the acquired position of the seedling transplanter 1 is mapped as point cloud data as shown in Fig. 10. Fig. 10 is a diagram showing an example of mapping of point cloud data.

[0139] The controller 100 linearly approximates the position of the seedling transplanter 1 obtained in the point cloud data by the least squares method. Then, the controller 100 judges whether the change in the inclination of the straight line calculated by the linear approximation is within a predetermined change range set in advance. If the change in the inclination is outside the predetermined change range, the controller 100 does not set a straight line for automatic straight traveling. If the change in the inclination is within the predetermined change range, the controller 100 sets the calculated straight line as the straight line for automatic straight traveling.

[0140] For example, when the positions F1 and F2 are acquired as the positions of the seedling transplanter 1, the controller 100 linearly approximates the positions F1 and F2 by the least squares method, thereby calculating a straight line G1.

[0141] Next, when a position F3 is further acquired as the position of the seedling transplanter 1, the controller 100 linearly approximates the positions F1, F2, and F3 by the least squares method, thereby calculating a straight line G2.

[0142] The controller 100 calculates the change in the slope of the straight line G2 relative to the slope of the straight line G1. For example, the change in the slope of the straight line G2 relative to the slope of the straight line G1 is greater than a predetermined change range. Therefore, at this stage, the controller 100 does not set a straight line.

[0143] Next, when a position F4 is further acquired as the position of the seedling transplanter 1, the controller 100 linearly approximates the positions F1, F2, F3, and F4 by the least squares method, thereby calculating a straight line G3.

[0144] The controller 100 calculates the change in the slope of the straight line G3 relative to the slope of the straight line G2. For example, the change in the slope of the straight line G3 relative to the slope of the straight line G2 is within a predetermined change range. Therefore, the controller 100 sets the straight line G3 as the automatic straight line.

[0145] The straight line includes the straight travel path R1. The straight line may also include the reference line R0. That is, the seedling transplanter 1 executes the above process when traveling straight in the field without setting a reference start point (point A) and a reference end point (point B), and after the straight line for automatic straight travel is set, automatic straight travel can be performed. Therefore, the seedling transplanter 1 can perform automatic straight travel in the first straight travel in the field. In addition, when the straight line is set, the controller 100 may notify the fact that the straight line has been set by the monitor 86 or the like.

[0146] By using the above method, the seedling transplanter 1 can quickly execute automatic straight movement by setting a straight line.

[0147] The seedling transplanter 1 may execute the above process after setting the reference start point (point A), and may be made capable of executing automatic straight movement after the straight movement line for automatic straight movement is set.

[0148] The walk-behind seedling transplanter 200 shown in Fig. 11 may have a camera 201 installed at the center of the machine body in the left-right direction. The camera 201 is installed so that the front end of the seedling transplanter 1 is captured within the shooting range. Fig. 11 is a side view of the walk-behind seedling transplanter 200. This allows the seedling transplanter 1 to measure the positional relationship between an arbitrary point and the seedling transplanter 1 from the oblique angle of the seedling transplanter 1 captured by the camera 201.

[0149] The infrared device may be provided at the center of the machine body in the left-right direction of the walk-behind seedling transplanter 200. The seedling transplanter 200 detects the edge of the field when the infrared acquisition range falls below a certain range.

[0150] Information may be transmitted to the walk-behind seedling transplanter 200 from a mobile terminal (e.g., a smartphone). The walk-behind seedling transplanter 200 determines the average value of the mobile terminal's travel direction information over a certain period of time as the straight-line direction of the seedling transplanter 1. If the walk-behind seedling transplanter 200 is about to deviate from the determined straight-line direction, it adjusts the rotation speed of the left and right drive wheels to suppress deviation from the straight-line direction. In this way, the walk-behind seedling transplanter 200 can perform simple straight-line assistance.

[0151] When the walk-behind seedling transplanter 200 is about to deviate from the determined straight-line direction, it may control the resistance rods that are grounded in the left and right directions to suppress deviation from the straight-line direction. For example, the walk-behind seedling transplanter 200 suppresses deviation from the straight-line direction by extending the resistance rods in the direction in which deviation is likely to occur.

[0152] The walk-behind seedling transplanter 200 stops the straight-line assistance when the angle reaches or exceeds a certain angle for a certain period of time based on information from an angle sensor included in the mobile terminal.

[0153] The above configuration may also be applied to a walk-behind cultivator.

[0154] In addition, when the setting of the reference line is completed and the middle division is performed along the reference line, the combine harvester 300 may perform straight-line assist along the direction of the row alignment by pressing a specific button after the row alignment. In addition, the combine harvester 300 may perform reverse assist when a specific button is pressed and the reverse range is operated. This allows the combine harvester 300 to automatically reverse along the mowed line, for example, as shown in FIG. 12. For example, after mowing in the middle division work, the main gear shift is set to the reverse position, and the combine harvester 300 automatically reverses along the middle division line by pressing the same specific button as during mowing. FIG. 12 is a diagram explaining reverse movement along the middle division line.

[0155] Further advantages and modifications may readily occur to those skilled in the art. Thus, the invention in its broader aspects is not limited to the specific details and representative embodiments shown and described above. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and equivalents thereof. [Explanation of symbols]

[0156] 1. Seedling transplanter (work vehicle) 2 Running vehicle 4 Seedling planting section (work machine) 10 Front wheels (running wheels) 35 Handle (steering device) 46 Straight-line mode switch (operation part) 100 Controller (control device) 150 Location acquisition device 160 1st distance sensor 161 Second distance sensor 162 3rd Distance Sensor 163 4th distance sensor 164 5th Distance Sensor 165 6th Distance Sensor

Claims

1. A first distance sensor is provided on the rear side of the aircraft, at the center of the aircraft in the left-right direction, and on a first orthogonal line perpendicular to the front-rear direction of the aircraft; a second distance sensor provided on the first orthogonal line and disposed at a first predetermined distance from the first distance sensor; a third distance sensor provided on the first orthogonal line, the third distance sensor being spaced from the first distance sensor by the first predetermined distance, and being provided on an opposite side of the first distance sensor to the second distance sensor; A steering device for adjusting the steering amount of the traveling wheels of the vehicle; a control device capable of executing straight-line assist to automatically move the aircraft in a straight line by controlling the steering device; Equipped with The first distance sensor measures a shortest distance from the first distance sensor to a first point where a distance to a ridge behind the aircraft is shortest, The second distance sensor measures a distance from the second distance sensor to a second point that is a ridge behind the aircraft in a direction parallel to the longitudinal direction, The third distance sensor measures a distance from the third distance sensor to a third point, which is a ridge behind the aircraft, in a direction parallel to the front-rear direction; The control device includes: Calculating a first distance from the first point to the second point and a second distance from the first point to the third point; A work vehicle in which a start reference point for straight ahead travel is set when the work implement of the vehicle body reaches a predetermined lowered position while the first distance and the second distance are equal.

2. a fourth distance sensor provided on a front side of the airframe, at a center in the left-right direction, and on a second orthogonal line perpendicular to a front-rear direction of the airframe; a fifth distance sensor disposed on the second orthogonal line and disposed at a second predetermined distance from the fourth distance sensor; a sixth distance sensor provided on the second orthogonal line, the sixth distance sensor being at the second predetermined distance from the fifth distance sensor and being provided on an opposite side of the fifth distance sensor from the fourth distance sensor; Equipped with The fourth distance sensor measures a shortest distance from the fourth distance sensor to a fourth point where a distance to a ridge in front of the aircraft is the shortest, The fifth distance sensor measures a distance from the fifth distance sensor to a fifth point which is a ridge in front of the aircraft in a direction parallel to the longitudinal direction, The sixth distance sensor measures a distance from the sixth distance sensor to a sixth point, which is a ridge in front of the aircraft, in a direction parallel to the longitudinal direction; The control device includes: calculating a third distance from the fourth point to the fifth point and a fourth distance from the fourth point to the sixth point; 2. The work vehicle according to claim 1, wherein an end reference point for straight-ahead travel is set when the third distance changes from an equal state to an unequal state to the fourth distance, and the work implement reaches a predetermined elevated position.

3. An operation unit that receives an operation to turn the automatic straight-line driving function on and off Equipped with The control device includes: When the operation unit is ON and the first distance and the second distance are equal, the automatic straight travel is started when the working machine is at a predetermined lowering position. The work vehicle of claim 1, wherein the automatic straight-line driving is not initiated when the operating unit is ON and the first distance and the second distance are not equal, or when the work machine is not in the specified lowering position.

4. a position acquisition device provided on the aircraft, for receiving positioning information from the positioning means and acquiring current position information of the aircraft based on the received positioning information; A steering device for adjusting the steering amount of the traveling wheels of the vehicle; a control device capable of executing straight-line assist to automatically move the aircraft in a straight line by controlling the steering device; Equipped with The control device includes: Mapping the position of the aircraft as point cloud data based on the position information acquired at each predetermined distance; In the point cloud data, the position of the aircraft for each predetermined distance is linearly approximated by a least squares method; When a change in gradient of the straight line calculated by the straight-line approximation is within a predetermined change range, the straight line calculated by the straight-line approximation is set as a straight line for automatic straight driving.

Images