Work vehicle

Abstract

To provide a work vehicle capable of accurately controlling travel or work, according to a state of a work place, a model, and a travel state.SOLUTION: A work vehicle comprises: a machine body; a travel unit 12 provided on the machine body; a machine body position calculating part 32 for calculating a position of the machine body and a travel azimuth of the machine body; an information acquiring part 24 for acquiring prescribed turning time information 40 in turning travel; and an automatic turning travel control part 36 for controlling a steering angle of the travel unit 12 in the turning travel in a predetermined prescribed procedure. The automatic turning travel control part 36 performs control for returning a steering angle to an original angle so that the machine body travels straightly, when an angle difference between a target azimuth of a straight path where the work vehicle travels after the turning travel, and the travel azimuth becomes a prescribed threshold 45 or lower, during the turning travel, and the automatic turning travel control part 36 changes the threshold according to the turning time information 40.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to a work vehicle in which control parameters (set values) are set and the travel of the work vehicle is controlled using the control parameters (set values). [Background technology]

[0002] For example, in Patent Document 1, in automatic turning control, when the difference between the direction of the vehicle body and the direction in which it is to go straight (the direction of travel on the next route) falls below a predetermined steering angle return level (threshold), the steering angle is controlled to be returned. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2021-185064 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, the control parameters (set values) depend on the model, driving conditions, work site conditions, etc., and constant control parameters (set values) do not necessarily allow optimal control of driving. For example, when the steering wheel angle is returned to a straight-ahead state during turning, the distance traveled by the vehicle before the steering wheel returns to a straight-ahead angle or the driving device returns to straight-ahead driving varies depending on the vehicle speed. Therefore, if the steering angle return level (threshold value) is controlled to be constant, it may not be possible to appropriately transition from turning to straight-ahead driving depending on the vehicle speed.

[0005] An object of the present invention is to precisely control traveling or work in accordance with the type of vehicle, traveling conditions, conditions of the work site, etc. [Means for solving the problem]

[0006] In order to achieve the above object, a work vehicle according to one embodiment of the present invention is a work vehicle that performs work travel in a field by performing reciprocating travel along a plurality of straight paths that are parallel to each other with a turning travel in between, and includes a body, a traveling device provided on the body, a body position calculation unit that calculates the position of the body and the traveling direction of the body, an information acquisition unit that acquires predetermined turning information during the turning travel, and a control unit that controls the movement of the traveling device during the turning travel in a predetermined procedure. Turning Steering and an automatic turning and traveling control unit that controls the automatic turning and traveling control unit. Starts with a specified turning maneuver During the turning run, when the angular difference between the target orientation of the straight path to be traveled following the turning run and the travel orientation becomes equal to or smaller than a predetermined threshold, the vehicle is caused to travel straight ahead. Predetermined turning steering of Back The automatic turning travel control unit changes the threshold value according to the turning time information. This will direct the robot to the next straight line path. .

[0007] The automatic turning is performed according to a predetermined procedure so as to end the turning at a predetermined position. The turning is affected by the vehicle speed during the turning, the field condition, the width of the vehicle, and other conditions of the vehicle, and as a result, the planned turning may not be realized.

[0008] According to the above configuration, any information such as vehicle speed can be acquired as turning information during automatic turning, and the threshold value for terminating the turning can be changed according to the turning information. This makes it possible to terminate the automatic turning under appropriate conditions according to the turning information, and to control the automatic turning with high precision.

[0009] The aircraft may further include a memory unit that stores model information of the aircraft, and the information acquisition unit may include a model information acquisition unit that acquires the model information from the memory unit, and the turning information may include the model information.

[0010] As described above, turning is affected by the width of the machine body, which can be read from the model information. With the above configuration, automatic turning can be ended under appropriate conditions according to the width of the machine body, and automatic turning can be controlled with high precision.

[0011] The automatic turning control unit may change the traveling speed of the vehicle body to a predetermined turning speed at the start of the turning motion.

[0012] With this configuration, automatic turning can be performed at a vehicle speed that is expected to enable appropriate turning, and automatic turning can be performed with high accuracy.

[0013] The information acquisition unit may also include a viscosity detection unit that detects the viscosity of the field and a vehicle speed detection unit that detects the vehicle speed of the vehicle, and the turning information may include viscosity information that is information on the viscosity and the vehicle speed during the turning movement.

[0014] As described above, the viscosity of the field causes the vehicle to skid sideways, which affects turning. With the above-described configuration, the automatic turning can be ended under appropriate conditions according to the viscosity of the field, and the automatic turning can be controlled with high accuracy.

[0015] In addition, turning is affected by the vehicle speed during turning. With the above-described configuration, automatic turning can be ended under appropriate conditions according to the vehicle speed, and automatic turning can be controlled with high accuracy.

[0016] The information acquisition unit may also include a vehicle speed detection unit that detects the vehicle speed of the vehicle body, and the automatic turning driving control unit may have a reference vehicle speed for the turning driving set in advance, and may include the difference between the vehicle speed and the reference vehicle speed as the turning information.

[0017] With this configuration, the vehicle speed that affects turning can be determined based on the reference vehicle speed. This makes it easy to determine whether the threshold needs to be changed, and when necessary, the automatic turning can be terminated under appropriate conditions according to the vehicle speed. As a result, the automatic turning can be controlled with high accuracy.

[0018] The vehicle may further include a positioning unit that acquires radio waves from a satellite and outputs positioning data for calculating the position of the vehicle, and the automatic turning driving control unit sets a maximum turning vehicle speed that is the upper limit of the driving speed during the turning driving, and the maximum turning vehicle speed may be set based on the positioning accuracy of the positioning unit.

[0019] Turning is also affected by the positioning accuracy of the positioning unit. With the above configuration, the maximum turning vehicle speed during turning can be set according to the positioning accuracy of the positioning unit. Therefore, automatic turning can be controlled with high accuracy according to the positioning accuracy of the positioning unit. [Brief description of the drawings]

[0020] [Figure 1] FIG. 1 is a left side view illustrating the overall configuration of a rice transplanter. [Diagram 2] FIG. 1 is a plan view illustrating an example of the overall configuration of a rice transplanter. [Diagram 3] FIG. [Figure 4] FIG. 11 is a diagram illustrating an example of an automatic turning travel procedure. [Diagram 5] FIG. 2 is a diagram illustrating an example of a functional configuration for controlling automatic driving. [Figure 6] FIG. 11 is a diagram illustrating an example of a flow of automatic turning traveling. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] Below, a rice transplanter that travels through a field for work will be described as an example of a work vehicle.

[0022] For ease of understanding, in this embodiment, unless otherwise specified, "front" (the direction of arrow F shown in Figs. 1 and 2) means the front in the longitudinal direction (traveling direction) of the machine body, and "rear" (the direction of arrow B shown in Figs. 1 and 2) means the rear in the longitudinal direction (traveling direction) of the machine body. In addition, the left-right direction or lateral direction means the transverse direction of the machine body (machine body width direction) perpendicular to the longitudinal direction of the machine body, and "left" (the direction of arrow L shown in Fig. 2) and "right" (the direction of arrow R shown in Fig. 2) mean the leftward and rightward directions of the machine body 1, respectively.

[0023] [Overall structure] As shown in Figures 1 and 2, the rice transplanter is equipped with a riding type four-wheel drive machine body 1. The machine body 1 is equipped with a link mechanism 13 in the form of a parallel four-linkage connected to the rear of the machine body 1 so as to be able to rise and fall and swing, a hydraulic lifting link 13a that drives the link mechanism 13 to swing, and a seedling planting device 3 that is connected to the rear end region of the link mechanism 13 so as to be able to roll. The seedling planting device 3 is an example of a working device, and a fertilizer applicator, a chemical spraying device, etc. may be mounted as other working devices.

[0024] The machine body 1 is equipped with wheels 12 (corresponding to "traveling device") as a mechanism for traveling, an engine 2, and a hydraulic continuously variable transmission 9 which is a main transmission. The continuously variable transmission 9 is, for example, an HST (Hydro-Static Transmission), and changes the speed of the driving force output from the engine 2 by adjusting the angles of a motor swash plate and a pump swash plate. The wheels 12 have left and right front wheels 12A which are steerable, and left and right rear wheels 12B which are not steerable. The engine 2 and the continuously variable transmission 9 are mounted on the front of the machine body 1. The power output from the engine 2 is supplied to the front wheels 12A, the rear wheels 12B, the working device, etc. via the continuously variable transmission 9 etc.

[0025] As an example, the seedling planting device 3 is configured for eight rows of planting. The seedling planting device 3 includes a seedling stand 21, eight rows of planting mechanisms 22, and five floats 15. The seedling planting device 3 can be changed to two-row, four-row, six-row, etc. planting by controlling the clutch for each row (planting clutch 23).

[0026] The seedling placing table 21 is a base on which eight mat-shaped seedlings are placed. The seedling placing table 21 moves back and forth in the left and right direction with a constant stroke corresponding to the left and right width of the mat-shaped seedlings, and each time the seedling placing table 21 reaches the left or right stroke end, each mat-shaped seedling on the seedling placing table 21 is vertically fed toward the lower end of the seedling placing table 21 at a predetermined pitch.

[0027] The eight planting mechanisms 22 are rotary type and are arranged in the left-right direction at regular intervals corresponding to the spacing between the planting rows. When the planting clutch 23 is shifted to a transmission state, the driving force is transmitted from the engine 2 to each planting mechanism 22, and the planting mechanism 22 cuts one seedling from the bottom end of each mat-like seedling placed on the seedling placement table 21 and plants it in the muddy soil after the land is leveled. In this way, the seedling planting device 3 can take out the seedlings from the mat-like seedlings placed on the seedling placement table 21 and plant them in the muddy soil of the paddy field.

[0028] The floats 15 level the field when planting seedlings. Each float 15 is provided in correspondence with two rows of planting mechanisms 22.

[0029] The machine body 1 is provided with a driving section 14 in its rear side area. The driving section 14 is provided with a steering wheel 10 for steering the front wheels, a main speed change lever 7 for adjusting the vehicle speed by changing the speed of the continuously variable transmission 9, an operation control lever 11 for controlling the raising and lowering operation of the seedling planting device 3 and the on / off operation of the planting clutch 23 (switching between a transmission state and a non-transmission state), and a driver's seat 16 for an operator (driver / worker). The steering wheel 10, the main speed change lever 7, and the operation control lever 11 are provided on the driver's panel 6 in front of the driver's seat 16. Furthermore, in front of the driving section 14, a spare seedling storage device 17A for storing spare seedlings is supported on a spare seedling support frame 17.

[0030] In addition, the spare seedling support frame 17 is provided with a positioning unit 8. The positioning unit 8 outputs positioning data for calculating the position PP (see FIG. 4) and orientation of the aircraft 1. The positioning unit 8 includes a satellite positioning module 8A that receives radio waves from satellites of the Global Navigation Satellite System (GNSS), and an inertial measurement module 8B that detects the inclination and acceleration of the three axes of the aircraft 1.

[0031] [Work trip] The travel of the rice transplanter when planting rice in a farm field will be described with reference to Figs. 1 and 2 and Fig. 3.

[0032] The rice transplanter in this embodiment can selectively perform manual driving and automatic driving. In manual driving, the driver manually operates the driving operation tools such as the steering wheel 10, the main shift lever 7, and the work operation lever 11 to perform driving for work. In automatic driving, the rice transplanter drives and works under automatic control, and performs straight work driving along a straight path IPL, which will be described later, with turning driving in between. In this case, the turning driving is automatically controlled according to a predetermined procedure, without a driving path being generated.

[0033] When the rice transplanter is planting, the field is divided into an outer area OA and an inner area IA, and the transplanter travels in each area accordingly.

[0034] In the internal area IA, a plurality of straight-line paths IPL (internal round-trip paths) approximately parallel to one side of the field are generated. The straight-line paths IPL are travel paths that travel all over the entire internal area IA, and each straight-line path IPL travels back and forth with a turning run in between. Each time a turning run is performed, the next straight-line path IPL to be traveled is generated in sequence. Each straight-line path IPL has a target orientation RD (see FIG. 4) for automatic travel (straight-ahead travel) along the straight-line path IPL.

[0035] After work travel in the inner area IA is performed, work travel in the outer peripheral area OA is performed. Work travel in the outer peripheral area OA is performed by automatic travel or manual travel. When automatic work travel is performed in the outer peripheral area OA, two travel routes, an inner circular route IRL and an outer circular route ORL, are generated that travel within the outer peripheral area OA along the periphery of the field. Work travel in the entire outer peripheral area OA is performed by work travel on the inner circular route IRL and the outer circular route ORL. Note that the travel routes that travel within the outer peripheral area OA are not limited to the inner circular route IRL and the outer circular route ORL, and may be one or more travel routes.

[0036] [Automatic turning] Next, automatic turning will be described using FIG. 4 while referring to FIG. 1 and FIG.

[0037] The automatic turning is started by a predetermined manual operation. The automatic turning is performed in the outer peripheral area OA, particularly in an area inside the field a predetermined distance from the ridge RW. The automatic turning is not performed along a travel route, but in a predetermined procedure determined in advance by controlling the travel devices such as the wheels 12 in a predetermined procedure.

[0038] For example, in the automatic turning operation, when the work traveling on the straight path IPL is completed and a predetermined manual operation is performed at the turning start position PSR, the front wheels 12A (traveling device) are first operated to a predetermined steering angle, for example, the maximum steering angle, and turning is performed. During the turning operation, the traveling direction CD of the machine body 1 at the position PP of the machine body 1 is continuously or successively acquired.

[0039] During automatic turning, the target heading RD of the (next) straight path IPL1 to be traveled after the turning is completed is compared with the traveling heading CD. Next, when the angle difference θ between the target heading RD and the traveling heading CD becomes equal to or less than a predetermined threshold value 45 (see FIG. 5), the steering angle is returned so that the vehicle 1 travels straight ahead (the steering angle is set to 0).

[0040] After that, automatic driving control is performed so that the vehicle travels along the straight-line path IPL1. This causes the automatic driving control to transition from automatic turning driving to automatic straight-line driving.

[0041] [Automatic driving control configuration] Next, a control configuration during automatic driving will be described using FIG. 5 while referring to FIG. 1 and FIG.

[0042] The operation and travel of the rice transplanter during automatic travel is controlled by a control unit 30 equipped with a processor such as a CPU, based on various control parameters (set values). The control unit 30 is connected to the positioning unit 8, the information acquisition unit 24, the obstacle detection device 28, the memory unit 29, the wheels 12 which are the travel device, the notification unit 26, and the information terminal 5 in a state in which data communication is possible via a communication unit (not shown) or the like.

[0043] The positioning unit 8 transmits the positioning data, and the control unit 30 calculates the position PP and traveling direction CD of the aircraft 1 based on the positioning data received from the positioning unit 8.

[0044] The information acquisition unit 24 acquires various information acquired during automatic turning travel as turning time information 40. The turning time information 40 is vehicle speed information 40A, which is information on the travel speed Vr (see FIG. 6) of the machine body 1, and model information 40B related to the model. The information acquisition unit 24 includes a vehicle speed detection unit 41 and a model information acquisition unit 42. The vehicle speed detection unit 41 acquires the travel speed Vr of the machine body 1 as vehicle speed information 40A, and stores it in a storage unit 29 described later. The model information acquisition unit 42 acquires model information 40B of the machine body 1, and stores it in a storage unit 29 described later. The model information 40B may be input and stored in the initial setting before the rice transplanter travels, or may be stored in the storage unit 29 in advance (such as when the machine body 1 is shipped).

[0045] The storage unit 29 stores various information such as turning information 40 and various control parameters (set values). The storage unit 29 also stores a preset threshold value 45 for returning the steering angle during automatic turning travel as one of the control parameters (set values). The storage unit 29 may be provided in the control unit 30.

[0046] The notification unit 26 and the information terminal 5 are provided as necessary, and display necessary information, issue warnings, etc. The notification unit 26 is an LED, a voice alarm generator, a speaker, etc. The information terminal 5 displays various information to notify (output) the operator, and has a touch panel (monitor screen) that accepts input of various information.

[0047] The control unit 30 includes a vehicle position calculation unit 32, a route generation unit 33, an automatic work driving control unit 35, and an automatic turning driving control unit 36.

[0048] The machine body position calculation section 32 intermittently or continuously calculates the position PP and traveling direction CD of the machine body 1 in the field based on the positioning data received from the positioning unit 8.

[0049] The path generating unit 33 calculates at least one of a base line and a reference direction for generating a straight path IPL by performing teaching traveling. Then, the path generating unit 33 uses the calculated base line or the reference direction to generate a straight path IPL to be traveled next every time turning traveling is performed.

[0050] The automatic work traveling control unit 35 controls the automatic work traveling along the straight line path IPL based on the position PP of the machine body 1 while controlling the work devices such as the seedling planting device 3 and the wheels 12 .

[0051] When the work travel on the straight path IPL ends and a predetermined manual operation is performed at the turning start position PSR, the automatic turning / travel control unit 36 ​​controls the machine body 1 to turn in a predetermined procedure. During the automatic turning / travel, the automatic turning / travel control unit 36 ​​may perform control to stop the planting clutch 23 (see FIG. 2) and raise the seedling planting device 3.

[0052] The automatic turning control unit 36 ​​also includes a threshold value changing unit 38. The threshold value changing unit 38 changes a threshold value 45 of an angle difference θ between the target direction RD and the traveling direction CD for returning the steering angle during automatic turning, from a preset value, based on turning information 40 stored in the memory unit 29, i.e., the turning information 40 acquired by the information acquisition unit 24. When the threshold value 45 is changed, the threshold value changing unit 38 may cause at least one of the notification unit 26 and the information terminal 5 to notify that fact.

[0053] Even if the steering angle is returned to the original position during turning so that the vehicle 1 travels straight, there is a certain time lag before the wheels 12 (front wheels 12A) actually face the straight direction (the steering wheel 10 becomes neutral) and the vehicle 1 travels straight, during which the vehicle 1 moves forward while turning. The distance from when the steering angle is returned to when the vehicle 1 travels straight is affected by the vehicle speed Vr of the vehicle 1 and the size of the vehicle 1, such as the width and the length of the wheelbase of the vehicle 1. If the distance from when the steering angle is returned to when the vehicle 1 travels straight varies during turning, it becomes difficult to turn stably as expected. Also, if the vehicle speed Vr is too fast, the vehicle 1 slips, and the distance from when the steering angle is returned to when the vehicle 1 travels straight becomes long, making it difficult to turn stably as expected.

[0054] Therefore, the threshold change unit 38 changes the threshold 45 of the angle difference θ between the target direction RD and the traveling direction CD for returning the steering angle during automatic turning travel based on the turning time information 40 so that appropriate turning is performed. Specifically, the threshold change unit 38 increases the threshold 45 based on the vehicle speed information 40A so that the steering angle is returned earlier as the traveling vehicle speed Vr is faster. Note that when the traveling vehicle speed Vr is slow, the distance from returning the steering angle to when the vehicle 1 travels straight is not significantly different, and the turning does not become a large turn, so that subsequent correction is not required. Therefore, the threshold change unit 38 may change the threshold 45 only when the traveling vehicle speed Vr is a predetermined speed or higher. In addition, the threshold change unit 38 reads the size of the vehicle 1 from the model information 40B, and increases the threshold 45 so that the steering angle is returned earlier as the size of the width, wheelbase, etc. of the vehicle 1 is larger. The threshold change unit 38 can read out the size of the unit 1 using any method, but it can also store in advance a correspondence table that describes the relationship between the model and the size of the unit 1, and obtain the size of the unit 1 according to the model information 40B.

[0055] In this way, by changing (optimizing) the threshold value 45 in accordance with the turning information 40, the distance from when the steering angle is returned to when the aircraft 1 starts moving straight is constant or within an appropriate range, enabling stable and precise automatic turning driving.

[0056] [Automatic turning control] Next, a control flow in automatic turning will be described using FIGS. 5 and 6 while referring to FIGS. 1 and 4.

[0057] When automatic turning travel is started, first, automatic turning travel control unit 36 ​​acquires vehicle speed information 40A detected by vehicle speed detection unit 41 and stored in memory unit 29 as turning time information 40. In addition, automatic turning travel control unit 36 ​​acquires model information 40B acquired by model information acquisition unit 42 and stored in memory unit 29 as turning time information 40.

[0058] Next, the automatic turning control unit 36 ​​or the threshold value changing unit 38 determines whether or not the traveling vehicle speed Vr acquired as the vehicle speed information 40A is greater than a preset reference vehicle speed Vrr (step #1 in FIG. 6).

[0059] If the traveling vehicle speed Vr is greater than the reference vehicle speed Vrr (step #1 Yes in Figure 6), the threshold change unit 38 changes the threshold 45 that triggers the return of the steering angle during automatic turning based on the traveling vehicle speed Vr (vehicle speed information 40A) and the size of the aircraft 1 obtained from the model information 40B, and corrects the threshold 45 stored in the memory unit 29 (step #2 in Figure 6).

[0060] Next, the automatic turning control unit 36 ​​compares the traveling direction CD of the vehicle 1 at the position PP of the vehicle 1 with the target direction RD, and determines whether the angle difference θ between the target direction RD and the traveling direction CD is equal to or less than the threshold value 45 stored in the memory unit 29 (step #3 in FIG. 6). Here, the threshold value 45 to be compared is the preset threshold value 45 when the traveling vehicle speed Vr is equal to or less than the reference vehicle speed Vrr (step #1 No in FIG. 6), and is the changed threshold value 45 when the threshold value 45 has been changed in step #2.

[0061] Then, if the angle difference θ is greater than the threshold value 45 (Step #3 No in FIG. 6), the automatic turning control unit 36 ​​maintains the steering angle and continues automatic turning until the angle difference θ becomes equal to or less than the threshold value 45. If the angle difference θ becomes equal to or less than the threshold value 45 (Step #3 Yes in FIG. 6), the automatic turning control unit 36 ​​returns the steering angle to 0 or a predetermined angle (Step #4 in FIG. 6).

[0062] Thereafter, the automatic turning travel control unit 36 ​​or the automatic work travel control unit 35 performs automatic steering control of the machine body 1 so that the machine body 1 can automatically travel straight ahead along the next straight-line route IPL1.

[0063] [Another embodiment] (1) In the above embodiment, when the traveling vehicle speed Vr during automatic turning travel deviates from the reference vehicle speed Vrr by a preset speed or more, the threshold changing unit 38 may change the threshold 45 in accordance with the traveling vehicle speed Vr. In other words, the turning information 40 (vehicle speed information 40A) may include the difference between the traveling vehicle speed Vr and the reference vehicle speed Vrr, and the threshold changing unit 38 may change the threshold 45 in accordance with the difference between the traveling vehicle speed Vr and the reference vehicle speed Vrr.

[0064] (2) In each of the above embodiments, the threshold change unit 38 may change the threshold 45 based on the traveling vehicle speed Vr (vehicle speed information 40A) and the size of the machine body 1 (model information 40B) without comparing the traveling vehicle speed Vr with the reference vehicle speed Vrr. In addition, the traveling vehicle speed Vr may be changed (decelerated) to a predetermined turning vehicle speed at the start of turning in automatic traveling and manual traveling. In this case, in the automatic turning traveling, even if the turning vehicle speed is controlled, if the traveling vehicle speed Vr during the automatic turning traveling deviates from the turning vehicle speed, the threshold change unit 38 may change the threshold 45 based on the traveling vehicle speed Vr (vehicle speed information 40A) and the size of the machine body 1 (model information 40B). With such a configuration, the relationship between the traveling vehicle speed Vr during turning traveling and the threshold 45 can be efficiently optimized, and turning traveling can be easily and accurately performed.

[0065] (3) In each of the above embodiments, a maximum turning vehicle speed, which is the upper limit of the traveling vehicle speed Vr during turning, may be set in advance. Furthermore, the maximum turning vehicle speed may be set based on the positioning accuracy of the positioning unit 8.

[0066] The positioning unit 8 acquires positioning data by a Global Navigation Satellite System (GNSS) or the like. There are various types of Global Navigation Satellite Systems (GNSS) with different positioning accuracies. For example, Differential GPS (DGDS) has a lower positioning accuracy than Real Time Kinematic GPS (RTKGDS). Therefore, the control of automatic turning using a positioning unit 8 that uses DGDS is less accurate than the control of automatic turning using a positioning unit 8 that uses RTKGDS, and it becomes difficult to appropriately control automatic turning when the turning vehicle speed increases.

[0067] By setting the maximum turning vehicle speed based on the positioning accuracy of the positioning unit 8, automatic turning can be performed at a turning vehicle speed according to the positioning accuracy of the positioning unit 8, thereby enabling automatic turning to be performed with high accuracy.

[0068] In this case, the threshold value 45 may be changed based on the traveling vehicle speed Vr (vehicle speed information 40A). However, the threshold value 45 may be used in the automatic turning without being changed from the preset threshold value 45.

[0069] (4) In each of the above embodiments, the vehicle speed detection unit 41 may obtain the traveling vehicle speed Vr, which is the vehicle speed information 40A, by any method, but the traveling vehicle speed Vr may be obtained from the distance traveled by the position PP of the aircraft 1 per unit time obtained from the positioning unit 8. This makes it possible to obtain the traveling vehicle speed Vr with high accuracy and perform automatic turning with high accuracy.

[0070] (5) In each of the above embodiments, the threshold change unit 38 is not limited to a configuration in which the threshold change unit 38 changes the threshold 45 based on the vehicle speed information 40A and the model information 40B, but may change the threshold 45 based on either the vehicle speed information 40A or the model information 40B. This makes it easier to perform automatic turning.

[0071] (6) In each of the above embodiments, the turning information 40 may include various information together with the vehicle speed information 40A and the model information 40B, or instead of at least one of the vehicle speed information 40A and the model information 40B. Such information may include travel information related to the travel state other than the travel speed, various types of work land information including viscosity information 40C indicating the viscosity of the field, and the like. This allows the threshold value 45 to be changed to a more appropriate value in accordance with the turning travel, and allows automatic turning travel to be performed with greater accuracy.

[0072] For example, when turning, if the field is slippery, the turning radius becomes larger. In other words, turning is affected by the viscosity of the field. For this reason, a viscosity detection unit 43 may be provided as the information acquisition unit 24, and the turning information 40 may include viscosity information 40C. Then, the threshold change unit 38 changes the threshold 45 based on the turning information 40 including the viscosity information 40C.

[0073] Furthermore, the model information 40B may include information indicating the type (positioning accuracy) of the positioning system of the positioning unit 8. Then, the threshold change unit 38 may change the threshold 45 in consideration of the positioning accuracy of the positioning unit 8 included in the model information 40B.

[0074] (7) In each of the above embodiments, the information acquisition unit 24 may acquire various control information, such as not only turning time information 40 during automatic turning travel, but also other travel information when the rice transplanter (work vehicle) travels, work information when the work vehicle works, and environmental information such as information on the work site (field), etc. Then, the automatic work travel control unit 35 or the automatic turning travel control unit 36 ​​(control unit 30) may optimize various control parameters (setting values) other than the threshold value 45 in the automatic turning travel in accordance with one or more pieces of control information acquired by the information acquisition unit 24.

[0075] For example, the rice transplanter may be connected to a work device to travel during work, and the external dimensions of the rice transplanter change depending on the connected work device. Also, the vehicle body position that is the reference for the position PP of the machine body 1 is calculated from the positioning data based on the position of the positioning unit 8, and changes depending on the external dimensions of the rice transplanter. Therefore, the model information 40B and the type of the connected work device are acquired as control information, and the control unit 30 may change the vehicle body position based on the acquired control information.

[0076] Also, the number of rows and row spacing in the seedling planting work are determined according to the connected work equipment. Therefore, the automatic work travel control unit 35 may set (change) the number of rows and row spacing in the automatic work travel based on the control information including the type of work equipment. Furthermore, the threshold change unit 38 may obtain the number of rows of the rice transplanter from the model information 40B and change the threshold 45 based on the number of rows and the travel vehicle speed Vr. Also, the control parameters (setting values) such as the PI gain in the automatic travel are determined according to the dimensions of the connected work equipment. Therefore, the automatic work travel control unit 35 may set (change) the control parameters (setting values) such as the PI gain in the automatic work travel based on the control information including the type of work equipment.

[0077] When the width of the connected working implement is greater than the width of the machine body 1, the turning motion is affected by the width of the working implement. Therefore, the width of the connected working implement may be included in the model information 40B. The threshold value changing unit 38 may change the threshold value 45 based on the turning information 40 including the width of the working implement.

[0078] (8) In each of the above embodiments, the turning procedure in the automatic turning travel is not limited to the procedure shown in Fig. 4 and may be any procedure. For example, after the turning travel is started by operating to the maximum steering angle, when the turning angle reaches a predetermined turning angle, the steering angle may be reduced.

[0079] (9) When the automatic traveling starts or during the automatic traveling, if there is an obstacle ahead in the traveling direction or around the machine body 1, problems may occur in traveling or work. Therefore, the rice transplanter of this embodiment may be equipped with a sonar sensor as an example of the obstacle detection device 28 that detects obstacles around the machine body 1 in each of the above embodiments. The sonar sensor detects an object within a predetermined distance as an obstacle. The obstacle is basically detected during the automatic traveling, but it may also be configured to detect the obstacle during the manual traveling. At least one of the automatic work traveling control unit 35 and the automatic turning traveling control unit 36 ​​controls the traveling so that the traveling is stopped, decelerated, or avoided when an obstacle is detected. Then, the automatic work traveling control unit 35 and the automatic turning traveling control unit 36 ​​may optimize the distance at which the obstacle is detected according to the control information.

[0080] (10) In each of the above embodiments, the control unit 30 is not limited to being composed of the above-mentioned functional blocks, and may be composed of any functional blocks. For example, each functional block of the control unit 30 may be further subdivided, or conversely, some or all of the functional blocks may be combined. In addition, the functions of the control unit 30 are not limited to the above-mentioned functional blocks, and may be realized by a method executed by any functional block. In addition, some or all of the functions of the control unit 30 may be composed of software. A program related to the software is stored in any storage device such as the storage unit 29, and is executed by a processor such as a CPU provided in the control unit 30, or a processor provided separately. In addition, the control unit 30 may be configured to be mounted on the aircraft 1, but some or all of the functions of the control unit 30 may be provided in the information terminal 5.

[0081] (11) In each of the above embodiments, the traveling device is not limited to the wheels 12, and may be any traveling device such as a crawler. [Industrial Applicability]

[0082] The present invention can be applied to rice transplanters, agricultural work vehicles that travel in fields while making turns, and various other work vehicles that travel in work areas while making turns. [Explanation of symbols]

[0083] 1 Aircraft 8 Positioning Unit 12 Wheels (running gear) 24 Information Acquisition Department 29 Memory section 32 Aircraft position calculation unit 33 Route Generation Unit 36 Automatic turning control unit 38 Threshold change unit 40 Turning Information 40A Vehicle speed information 40B Model Information 40C viscosity information 41 Vehicle speed detection unit 42 Model information acquisition unit 43 Viscosity detector 45 Threshold CD Driving direction IRL Inner Loop Route PP position VR running vehicle speed Vrr Reference vehicle speed θ angle difference

Claims

1. A work vehicle that performs work travel in a field by performing reciprocating travel along a plurality of straight paths that are parallel to each other with turning travel in between, The aircraft and A running device provided on the airframe; an aircraft position calculation unit that calculates the position of the aircraft and the traveling direction of the aircraft; An information acquisition unit that acquires predetermined turning information during the turning travel; an automatic turning control unit that controls turning steering of the traveling device during the turning travel in a predetermined procedure; the automatic turning control unit performs control to return the predetermined turning steering to its original state so that the vehicle travels straight ahead when an angular difference between a target orientation of the straight path traveled following the turning traveling and the traveling orientation becomes equal to or less than a predetermined threshold during the turning traveling started by a predetermined turning steering, The automatic turning control unit changes the threshold value in accordance with the turning information to direct the vehicle to the next straight path.

2. A storage unit for storing model information of the aircraft is further provided, a model information acquisition unit that acquires the model information from the storage unit as the information acquisition unit, The work vehicle according to claim 1 , wherein the turning information includes model information.

3. 3. The work vehicle according to claim 1, wherein the automatic turning control unit changes the traveling speed of the vehicle body to a predetermined turning speed when starting the turning motion.

4. The information acquisition unit includes a viscosity detection unit that detects the viscosity of the field and a vehicle speed detection unit that detects the traveling speed of the vehicle; 3. The work vehicle according to claim 1, wherein the turning information includes viscosity information that is information about the viscosity and the vehicle speed during the turning travel.

5. The information acquisition unit includes a vehicle speed detection unit that detects a traveling vehicle speed of the vehicle; The automatic turning control unit is configured to set a reference vehicle speed in the turning motion in advance, The work vehicle according to claim 1 or 2, wherein the turning information includes a difference between the traveling vehicle speed and the reference vehicle speed.

6. A positioning unit is further provided which receives radio waves from a satellite and outputs positioning data for calculating the position of the aircraft. The automatic turning travel control unit sets a maximum turning vehicle speed which is an upper limit of a traveling vehicle speed during the turning travel, 3. The work vehicle according to claim 1, wherein the maximum turning speed is set based on the positioning accuracy of the positioning unit.

7. A work vehicle described in any one of claims 1 to 6, wherein the threshold value is changed during the turning movement.

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