Work vehicle

Abstract

To provide a work vehicle which reduces adverse effects of inaccurate steering control on automatic straight-advancing.SOLUTION: A work vehicle includes: a travel mode switch part which switches a travel mode between an automatic straight-advancing mode and a manual mode; an abnormality detection part detecting abnormality regarding traveling in the automatic straight-advancing mode; a warning part notifying that the automatic straight-advancing mode is terminated when abnormality is detected by the abnormality detection part during traveling in the automatic straight-advancing mode. When the termination of the automatic straight-advancing mode is notified by the warning part, a traveling mode is automatically switched to the manual mode or traveling is automatically stopped after a prescribed time passes from when the termination of the automatic straight-advancing mode is notified.SELECTED DRAWING: Figure 7

Description

[Technical field]

[0001] The present invention relates to a work vehicle capable of switching a driving mode between an automatic straight-line mode and a manual mode. [Background technology]

[0002] As an example of such a work vehicle, the one described in Patent Document 1 is already known. This work vehicle is a riding rice transplanter, and is capable of switching the driving mode between an automatic straight-line mode (automatic straight-line steering mode) and a manual mode (a state in which the automatic straight-line steering mode is deactivated). This work vehicle is equipped with a GPS module (GPS receiver) that acquires position information by a satellite positioning system.

[0003] In the automatic straight-line mode, steering control is performed so that the vehicle travels in a straight line based on the positioning data (signals) from the GPS module. In addition, in this work vehicle, the automatic straight-line mode is prohibited when the vehicle speed is equal to or higher than a predetermined value.

[0004] According to this configuration, when the direction of travel of the work vehicle in the automatic straight-line mode is different from that expected by the operator, it is possible to prevent the work vehicle from traveling at high speed in an unexpected direction. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2001-161112 A Summary of the Invention [Problem to be solved by the invention]

[0006] In the above-mentioned work vehicle, while traveling in the automatic straight-line mode, it may be difficult for the GPS module to obtain position information when the vehicle is hidden behind a building, when the GPS module malfunctions, etc. In such cases, accurate positioning data is not output from the GPS module, and automatic straight-line traveling is performed with inaccurate steering control, which may result in the actual traveling line deviating significantly from the target traveling line.

[0007] SUMMARY OF THE PRESENT EMBODIMENT An object of the present invention is to provide a work vehicle in which the adverse effects of automatic straight driving caused by inaccurate steering control as described above are reduced. [Means for solving the problem]

[0008] The work vehicle according to the present invention comprises a driving mode switching unit which switches the driving mode between an automatic straight-line mode and a manual mode, and an abnormality detection unit which detects an abnormality related to driving in the automatic straight-line mode. If an abnormality is detected by the abnormality detection unit while driving in the automatic straight-line mode, the work vehicle is further provided with a warning unit which notifies the driver that the automatic straight-line mode is to be terminated. When the warning unit notifies the driver that the automatic straight-line mode is to be terminated, the driving mode is automatically switched to the manual mode or driving is stopped after a predetermined time has elapsed from the point at which it was notified that the automatic straight-line mode was to be terminated.

[0009] According to the configuration of the first aspect of the invention, when an abnormality occurs related to driving in the automatic straight-line driving mode and the warning unit notifies the vehicle that the automatic straight-line driving mode will be terminated, the driving mode is automatically switched to the manual mode or driving is stopped after a predetermined time has elapsed from the point in time when the vehicle was notified that the automatic straight-line driving mode will be terminated. This makes it possible to avoid continuing driving in the automatic straight-line driving mode for a relatively long distance or long period of time while the steering control remains inaccurate due to an abnormality related to driving in the automatic straight-line driving mode.

[0010] Moreover, since the notification unit notifies the operator of the abnormality, the operator can know in advance that the traveling stop process will be executed after the vehicle has traveled a predetermined distance or time, which makes it easier to avoid a situation in which the operator is surprised by the sudden execution of the traveling stop process.

[0011] The second invention is the above-mentioned first invention, The abnormality stop processing unit does not execute the traveling stop processing when the traveling mode is switched to the manual mode during traveling of the predetermined distance or the predetermined time.

[0012] Even if an abnormality occurs in the automatic straight-line driving mode, if the driving mode is the manual mode, the vehicle can continue to drive without any adverse effects due to the abnormality. In other words, if the driving mode is the manual mode, the actual driving line will not deviate from the target driving line due to automatic straight-line driving caused by inaccurate steering control. Therefore, if the driving mode is switched to the manual mode during driving for a predetermined distance or for a predetermined time, the adverse effects of automatic straight-line driving caused by inaccurate steering control can be avoided without executing the driving stop process.

[0013] According to the configuration of the second aspect of the invention, when the driving mode is switched to the manual mode while the vehicle is traveling a predetermined distance or for a predetermined time, the execution of the travel stop process that has become unnecessary due to the switch to the manual mode is avoided, thereby making it possible to avoid a situation in which the travel of the work vehicle is unnecessarily hindered by the execution of the unnecessary travel stop process.

[0014] The third invention is a driving mode switching unit that switches a driving mode between an automatic straight-line mode and a manual mode; An abnormality detection unit that detects an abnormality related to driving in the automatic straight-line mode; a notification unit that notifies an abnormality when an abnormality is detected by the abnormality detection unit; and an abnormality switching unit that switches the driving mode to the manual mode after driving a predetermined distance or a predetermined time from the point at which the abnormality is detected by the abnormality detection unit if an abnormality is detected by the abnormality detection unit while driving in the automatic straight-line mode.

[0015] According to the third aspect of the present invention, when an abnormality occurs in the automatic straight-line driving mode, the driving mode is switched to the manual mode after a predetermined distance or time has passed since the abnormality was detected. This makes it possible to avoid continuing driving in the automatic straight-line driving mode for a relatively long distance or for a long period of time while the steering control remains inaccurate.

[0016] Moreover, since the notification unit notifies the operator of the abnormality, the operator can know in advance that the driving mode will be switched to the manual mode after a predetermined distance or time of driving, which makes it easy to avoid a situation in which the operator is surprised by the driving mode suddenly being switched to the manual mode.

[0017] The fourth invention is any one of the first to third inventions, The vehicle further includes an abnormality deceleration unit that decelerates the traveling speed when an abnormality is detected by the abnormality detection unit while the vehicle is traveling in the automatic straight-line mode.

[0018] The notification unit may be a visual notification unit (e.g., a lamp) or an audio notification unit (e.g., a buzzer). However, when a visual notification unit is used, it is expected that the notification will be difficult to see due to the influence of sunlight when the work vehicle is used outdoors. Also, when an audio notification unit is used, it is expected that the notification will be difficult to hear due to noise generated by the work vehicle or the surrounding environment.

[0019] According to the fourth aspect of the present invention, the operator can know that an abnormality has occurred based on the fact that the vehicle's travel speed in the automatic straight-line mode has decreased. Therefore, even in a situation where the notification by the notification unit is difficult to recognize, the operator can be reliably notified of the occurrence of an abnormality.

[0020] The fifth invention is a driving mode switching unit that switches a driving mode between an automatic straight-line mode and a manual mode; An abnormality detection unit that detects an abnormality related to driving in the automatic straight-line mode; The vehicle further includes an abnormality deceleration unit that decelerates the traveling speed when an abnormality is detected by the abnormality detection unit while the vehicle is traveling in the automatic straight-line mode.

[0021] If an abnormality occurs in the automatic straight-line driving mode while the vehicle is driving in the automatic straight-line driving mode, the abnormality may cause the steering control to become inaccurate. If the driving time is constant, the deviation of the actual driving line from the target driving line caused by the inaccurate steering control tends to become smaller as the driving speed becomes slower.

[0022] According to the configuration of the fifth aspect of the present invention, if an abnormality occurs in the automatic straight-line driving mode while the vehicle is driving in the automatic straight-line driving mode, the vehicle speed is decelerated. Therefore, if the driving time is constant, the deviation of the actual driving line from the target driving line is likely to be small compared to the case where the deceleration operation is not performed. In other words, the time until the deviation of the driving line becomes relatively large is secured longer.

[0023] Moreover, the operator can know that an abnormality has occurred based on the deceleration of the vehicle's travel speed in the automatic straight-line mode. The operator who knows that an abnormality has occurred can take measures such as stopping travel or switching to manual mode. This allows the operator more time to consider the above-mentioned measures between the time when an abnormality occurs and the time when the deviation of the travel line becomes relatively large.

[0024] The sixth invention is any one of the first to fifth inventions, A GPS module that outputs positioning data indicating the aircraft's position; A gyro sensor that outputs orientation data indicating the attitude and orientation of the aircraft; The vehicle further includes a steering angle control unit that controls a steering angle based on the orientation data when an abnormality related to the positioning data is detected by the abnormality detection unit in the automatic straight-line driving mode.

[0025] When the vehicle has the configuration of any one of the first to fourth inventions described above, if an abnormality in the positioning data is detected while driving in automatic straight-line mode, a driving stop process or a switch to manual mode is performed after driving a predetermined distance or time from the time the abnormality was detected.

[0026] In this case, if the steering angle is controlled based on the positioning data until a predetermined distance or time is reached, there is a risk that the actual driving line will deviate from the target driving line.

[0027] According to the configuration of the sixth aspect of the present invention, when an abnormality occurs in the positioning data while traveling in the automatic straight-ahead mode, the steering angle is controlled based on the orientation data output by the gyro sensor. That is, when an abnormality occurs in the positioning data, the steering angle is controlled based on the orientation data until a predetermined distance or time is reached.

[0028] Therefore, it is possible to prevent the actual driving line from deviating from the target driving line due to control of the steering angle based on the positioning data until a predetermined distance or time is reached.

[0029] Furthermore, in the case where the configuration of the fifth aspect of the present invention is provided, if an abnormality in the positioning data is detected while the vehicle is traveling in the automatic straight-ahead mode, the traveling speed is reduced.

[0030] In this case, if the steering angle is controlled based on the positioning data after an abnormality in the positioning data is detected, there is a risk that the actual driving line will deviate from the target driving line as deceleration continues.

[0031] According to the configuration of the sixth aspect of the present invention, when an abnormality occurs in the positioning data during driving in the automatic straight-ahead mode, the steering angle is controlled based on the orientation data output by the gyro sensor. That is, after an abnormality occurs in the positioning data, the steering angle is controlled based on the orientation data.

[0032] Therefore, it is possible to avoid a situation in which the actual driving line deviates from the target driving line as the vehicle continues to decelerate after an abnormality in the positioning data is detected.

[0033] The seventh invention is the first or second invention, A GPS module that outputs positioning data indicating the aircraft's position; A gyro sensor that outputs orientation data indicating the attitude and orientation of the aircraft; a steering angle control unit that controls a steering angle based on the orientation data when an abnormality related to the positioning data is detected by the abnormality detection unit in the automatic straight-line mode, When an abnormality in the positioning data is detected by the abnormality detection unit and no abnormality in the positioning data is detected during driving for the specified distance or the specified time, the abnormality stop processing unit executes the driving stop processing after driving for the specified distance or the specified time from the point at which the abnormality was detected by the abnormality detection unit.

[0034] In the first or second invention, it is possible to configure the vehicle to cancel the travel stop process when an abnormality in the positioning data is detected and then the abnormality is no longer detected.

[0035] However, when an abnormality related to the positioning data is detected, even if the abnormality is detected temporarily, there is a possibility that a device related to the positioning data, such as a GPS module, is broken. Therefore, in a configuration in which the traveling stop process is canceled when an abnormality related to the positioning data is detected and then the abnormality is no longer detected, a situation may occur in which traveling in the automatic straight-ahead mode continues for a relatively long distance or for a long time, even if a device related to the positioning data is broken.

[0036] According to the seventh aspect of the present invention, when an abnormality related to the positioning data is detected, even if the abnormality is detected temporarily, the running stop process is executed after the vehicle has run a predetermined distance or time from the time the abnormality was detected. This makes it easy to avoid a situation where the vehicle continues running in the automatic straight ahead mode for a relatively long distance or for a long time even if the device related to the positioning data is broken.

[0037] The eighth aspect of the present invention is the third aspect of the present invention, A GPS module that outputs positioning data indicating the aircraft's position; A gyro sensor that outputs orientation data indicating the attitude and orientation of the aircraft; a steering angle control unit that controls a steering angle based on the orientation data when an abnormality related to the positioning data is detected by the abnormality detection unit in the automatic straight-line mode, When an abnormality in the positioning data is detected by the abnormality detection unit and no abnormality in the positioning data is detected during driving of the specified distance or the specified time, the abnormality switching unit switches the driving mode to the manual mode after driving of the specified distance or the specified time from the point at which the abnormality was detected by the abnormality detection unit.

[0038] In the eighth aspect of the present invention, it is possible to configure such that, after an abnormality in the positioning data is detected, if the abnormality is no longer detected, switching to the manual mode is canceled.

[0039] However, when an abnormality in the positioning data is detected, even if the abnormality is detected temporarily, there is a possibility that a device related to the positioning data, such as a GPS module, is broken. Therefore, in a configuration in which switching to the manual mode is canceled when an abnormality in the positioning data is detected and then no longer detected, a situation may occur in which driving in the automatic straight-ahead mode continues for a relatively long distance or for a long time, even if a device related to the positioning data is broken.

[0040] According to the configuration of the eighth aspect of the present invention, when an abnormality related to the positioning data is detected, even if the abnormality is detected temporarily, the driving mode is switched to the manual mode after a predetermined distance or time of driving from the time the abnormality is detected. Therefore, it is easy to avoid a situation where driving in the automatic straight-line mode continues for a relatively long distance or for a long time even if a device related to the positioning data is broken.

[0041] The ninth aspect of the present invention is any one of the first to eighth aspects of the present invention, When the abnormality detection unit detects an abnormality, the driving mode switching unit prevents the driving mode from being switched to the automatic straight driving mode.

[0042] According to the configuration of the ninth aspect of the present invention, when an abnormality occurs related to driving in the automatic straight-line driving mode, switching to the automatic straight-line driving mode is prevented. This makes it possible to avoid a situation in which the driving mode is switched to the automatic straight-line driving mode despite the occurrence of an abnormality related to driving in the automatic straight-line driving mode, and the actual driving line deviates from the target driving line due to inaccurate steering control caused by the abnormality.

[0043] A tenth aspect of the present invention is any one of the first to ninth aspects of the present invention, The driving mode switching unit has a switch that switches the driving mode when operated, The vehicle further includes a warning unit that issues a warning to prompt the driver to switch the driving mode to the manual mode when an abnormality is detected by the abnormality detection unit during driving in the automatic straight-line mode.

[0044] According to the configuration of the tenth aspect of the present invention, when an abnormality occurs in the automatic straight-line driving mode while the vehicle is driving in the automatic straight-line driving mode, the operator can easily recognize from the issued warning that the situation requires switching to the manual mode. If the operator who recognizes this operates the changeover switch, the driving mode is switched to the manual mode, so that the vehicle can be prevented from continuing to drive in the automatic straight-line driving mode due to inaccurate steering control. [Brief description of the drawings]

[0045] [Figure 1] FIG. [Diagram 2] FIG. [Diagram 3] FIG. 4 is a block diagram showing a control configuration related to traveling in an automatic straight-ahead mode. [Figure 4] FIG. 2 is a plan view showing the structure of a steering unit. [Diagram 5] FIG. 11 is a top view explanatory diagram illustrating the operation of the rice transplanter during work including traveling in an automatic straight-line mode and traveling in a manual mode. [Figure 6] 11 is a top view illustrating generation of a target line, etc. FIG. [Figure 7] 4 is a flowchart of an abnormality control routine. [Figure 8] FIG. 11 is a block diagram showing a control configuration related to traveling in an automatic straight-ahead mode in the first alternative embodiment. [Figure 9] 10 is a flowchart of an abnormality control routine in a first alternative embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0046] An embodiment of the present invention will be described with reference to the drawings. In the following description, unless otherwise specified, the forward, backward, left and right directions are described as follows. That is, the forward traveling direction of the machine body during work travel is "forward", and the backward traveling direction is "rear". Furthermore, the direction corresponding to the right side based on the forward posture in the forward and backward directions is "right", and the direction corresponding to the left side is "left".

[0047] [Overall configuration of the rice transplanter] As shown in FIG. 1 and FIG. 2, a riding type rice transplanter A (corresponding to the "work vehicle" according to the present invention) is provided with a pair of left and right front wheels 1 and a pair of left and right rear wheels 2. A traveling body 3 is supported by the pair of left and right front wheels 1 and the pair of left and right rear wheels 2. A seedling planting device 5 is supported at the rear of the traveling body 3 via a link mechanism 4. A driving section 6 where various driving operations are performed by an operator is provided at the center in the front-rear direction of the traveling body 3. The driving section 6 is provided with a driver's seat 11 and a steering unit U. The steering unit U is provided with a steering handle 18. The pair of left and right front wheels 1 can be steered by the steering unit U. A bonnet 7 is provided in front of the driving section 6. An engine 8 is provided inside the bonnet 7. A spare seedling tray 9 on which spare seedlings can be placed is provided on the left and right sides of the bonnet 7. A rod-shaped center mascot 45 is provided at the tip of the bonnet 7.

[0048] [Configuration of the link mechanism and seedling planting device] As shown in Figures 1 and 2, the link mechanism 4 is equipped with a hydraulic cylinder 12. The link mechanism 4 moves up and down due to the expansion and contraction of the hydraulic cylinder 12. The seedling planting device 5 also moves up and down in accordance with the movement of the link mechanism 4. That is, the seedling planting device 5 is supported at the rear of the traveling body 3 in a state in which it can be freely raised and lowered.

[0049] The seedling planting device 5 is equipped with four transmission cases 13, a rotating case 14 supported on the left and right rear parts of the transmission cases 13 so as to be freely rotatable, a pair of planting arms 15 provided on both ends of the rotating case 14, a number of ground floats 16 for leveling the paddy field surface, and a seedling carrying platform 17. In other words, the seedling planting device 5 is configured as an 8-row planting type.

[0050] The seedling planting device 5 configured in this manner drives the seedling carrying platform 17 back and forth to the left and right while rotating the rotating case 14 with power transmitted from the transmission case 13, so that the seedlings are alternately taken out from the bottom of the seedling carrying platform 17 by the planting arm 15 and planted on the surface of the rice field.

[0051] [Marker device configuration] As shown in FIG. 1, the seedling planting device 5 is provided with a marker device 10 on the left and right sides. The marker device 10 includes a marker arm 10a and a rotating body 10b. The marker arm 10a is supported by the seedling planting device 5 in a state in which it can swing up and down. The rotating body 10b is supported at the tip of the marker arm 10a in a state in which it can rotate freely, and has a plurality of protruding bodies in the circumferential direction. The marker device 10 also includes an electric motor for markers (not shown). The electric motor for markers switches the position of the marker device 10 between an operating position and a stored position. In the operating position, the marker device 10 is in contact with the surface of the field, and in the stored position, the marker device 10 is separated upward from the surface of the field.

[0052] [Configuration of GPS module and gyro sensor] As shown in Figs. 1 and 2, a GPS module 19 is installed above the spare seedling bed 9 in a side view of the rice transplanter A. The GPS module 19 measures the position of the rice transplanter A by a satellite positioning system. A gyro sensor 20 is installed at the rear of the traveling body 3. The gyro sensor 20 detects the yaw angle of the rice transplanter A, that is, the angular velocity of the turning angle of the rice transplanter A (corresponding to the "orientation data" according to the present invention). As shown in Fig. 3, the GPS module 19 is configured to output positioning data indicating the position of the machine to the control device 21. The gyro sensor 20 is configured to output the detected angular velocity to the control device 21. The control device 21 is provided in the rice transplanter A.

[0053] [Drive section configuration] 1 and 2, the driving section 6 is provided with a main speed change lever 22 and a registration switch 24. A push-type changeover switch 23 is provided at the free end of the main speed change lever 22. The registration switch 24 is provided with a push-type first registration button 24A and a push-type second registration button 24B.

[0054] As shown in Fig. 3, the changeover switch 23 is electrically connected to the changeover signal transmission unit 25a. The changeover switch 23, together with the changeover signal transmission unit 25a and the abnormality signal receiving unit 25b, constitutes a traveling mode changeover unit 26. When the changeover switch 23 is pressed, a predetermined signal is output from the changeover signal transmission unit 25a to the control device 21, and the traveling mode of the rice transplanter A is changed. When the first registration button 24A or the second registration button 24B is pressed, a predetermined signal is output from the registration switch 24 to the control device 21.

[0055] As shown in Fig. 2, the driving section 6 is provided with a brake pedal 46. The brake pedal 46 is linked to a braking device 36 (see Fig. 3) provided on the rice transplanter A. When the operator depresses the brake pedal 46, the braking device 36 brakes the rice transplanter A and stops the rice transplanter A from traveling.

[0056] The driving unit 6 is also provided with a display 39. The display 39 is configured to display various information related to the state of the rice transplanter A.

[0057] [Power transmission system configuration] As shown in Fig. 4, the rice transplanter A is provided with a transmission belt 48, a hydrostatic continuously variable transmission 37, and a transmission case 47. The power of the engine 8 is transmitted to the hydrostatic continuously variable transmission 37 and the transmission case 47 via the transmission belt 48. The power is then transmitted from the transmission case 47 to a pair of left and right front wheels 1. Although not shown here, power is also transmitted from the transmission case 47 to a pair of left and right rear wheels 2 in the same manner.

[0058] The hydrostatic continuously variable transmission 37 is configured to be able to change the speed steplessly from a neutral position N to a forward side F and a reverse side R. The hydrostatic continuously variable transmission 37 is configured so that the gear ratio can be changed by operating a main speed change lever 22 (see Figs. 1 and 2) provided in the driver's section 6.

[0059] [Configuration of the control device] 3, the control device 21 includes a steering angle control unit 27, an abnormality detection unit 28, an abnormality stop processing unit 29, an abnormality deceleration unit 30, an information storage unit 31, a teaching storage unit 32, a generation unit 33, and a routine storage unit 34. In addition, various signals are input to the control device 21 from the GPS module 19, the gyro sensor 20, the driving mode switching unit 26, the registration switch 24, and the steering angle sensor 44. Then, based on the various input signals, the control device 21 outputs predetermined signals to the abnormality signal receiving unit 25b, the steering motor 35, the braking device 36, the hydrostatic continuously variable transmission 37, the buzzer 38 (corresponding to the "notification unit" according to the present invention), and the display 39 (corresponding to the "warning unit" according to the present invention).

[0060] The information storage unit 31 is configured to store, by time, the positioning data input from the GPS module 19. Furthermore, the teaching storage unit 32 is configured to calculate, based on the positioning data stored in the information storage unit 31 at the point where the first registration button 24A is pressed and at the point where the second registration button 24B is pressed, a teaching direction TA that is a direction connecting these two points.

[0061] [Configuration of steering unit] 4, the steering unit U includes a steering wheel 18, a steering shaft 40, a pitman arm 41, a pair of left and right linkage mechanisms 42, a steering motor 35, and a gear mechanism 43. The steering wheel 18 is connected to the pitman arm 41 via the steering shaft 40. The pitman arm 41 is connected to the pair of left and right front wheels 1 via the pair of left and right linkage mechanisms 42.

[0062] When the steering wheel 18 is turned, the steering shaft 40 turns in response to the turn. The driving force of the steering motor 35 is transmitted to the steering shaft 40 via a gear mechanism 43. When the steering shaft 40 turns, the pitman arm 41 swings. When the pitman arm 41 swings, a pair of left and right linkage mechanisms 42 are displaced, and the steering angle of the pair of left and right front wheels 1 changes. A steering angle sensor 44 (see FIG. 3) consisting of a rotary encoder is provided at the lower end of the steering shaft 40. The amount of rotation of the steering shaft 40 is detected by the steering angle sensor 44.

[0063] [Calculation of aircraft attitude and heading] The rice transplanter A is configured to be able to calculate the attitude direction NA of the machine body. The attitude direction NA of the machine body is calculated as follows.

[0064] First, while the rice transplanter A is traveling, an initial attitude orientation is calculated as the attitude orientation NA based on the positioning data at the current position and the positioning data at the point where the rice transplanter A was traveling immediately before. Next, when the rice transplanter A travels for a certain period of time after the initial attitude orientation is calculated, the angular velocity detected by the gyro sensor 20 during the certain period of travel is integrated to calculate the amount of change in the attitude orientation NA.

[0065] The calculated amount of change in the attitude direction NA is then added to the initial attitude direction to update the calculation result of the attitude direction NA. After that, the amount of change in the attitude direction NA is calculated in the same manner at regular time intervals, and the calculation result of the attitude direction NA is updated in sequence.

[0066] The result of integrating the angular velocity is equal to the amount of change in the attitude orientation NA of the rice transplanter A. That is, the angular velocity detected by the gyro sensor 20 can be treated as a parameter (hereinafter also referred to as "orientation data") indicating the attitude orientation NA of the body of the rice transplanter A. The above-mentioned method of calculating the attitude orientation NA utilizes such a property of the angular velocity.

[0067] Incidentally, the angular velocity detected by the gyro sensor 20 contains a measurement error (drift). Since this measurement error increases over time, the error contained in the calculated amount of change in the attitude orientation NA increases each time the amount of change in the attitude orientation NA is calculated. Therefore, when calculating the attitude orientation NA as described above, the rice transplanter A is configured to correct the angular velocity detected by the gyro sensor 20 using the positioning data. This allows the attitude orientation NA to be calculated more accurately.

[0068] [About automatic straight-line mode and manual mode] The rice transplanter A is configured to be able to travel in an automatic straight-line mode and in a manual mode. In the automatic straight-line mode, the steering angle of the rice transplanter A is automatically controlled so that the rice transplanter A travels straight. In the manual mode, the steering angle of the rice transplanter A is not automatically controlled, and the operator must operate the steering angle by turning the steering handle 18.

[0069] The traveling modes are switched by pressing the changeover switch 23 provided in the traveling mode switching unit 26. In other words, the traveling mode switching unit 26 has the changeover switch 23 that switches the traveling mode of the rice transplanter A by being operated.

[0070] For example, when the traveling mode is the automatic straight-line mode, if the operator presses the changeover switch 23, a predetermined signal is output from the switching signal transmission unit 25a to the control device 21, and the traveling mode is switched to the manual mode. Also, when the traveling mode is the manual mode, if the operator presses the changeover switch 23, a predetermined signal is output from the switching signal transmission unit 25a to the control device 21, and the traveling mode is switched to the automatic straight-line mode. In this way, the traveling mode of the rice transplanter A is switched between the automatic straight-line mode and the manual mode by the traveling mode switching unit 26.

[0071] In the following, as an example of an operation including driving in the automatic straight-line mode and driving in the manual mode, a case where seedling planting work is performed in a paddy field that is rectangular in top view will be described.

[0072] As shown in Fig. 5, first, the operator positions the rice transplanter A at the first position Q1 at the corner of the field and presses the first registration button 24A of the registration switch 24. Then, the operator lowers the seedling planting device 5 and, with the marker device 10 and the grounding float 16 in contact with the ground, drives the rice transplanter A straight along the straight line of the ridge on the left side of the traveling direction from the first position Q1. At this time, the rice transplanter A drives in manual mode.

[0073] In addition, when the traveling mode is the manual mode, when the operator turns the steering handle 18, the steering motor 35 is driven in a direction to assist the turning. As a result, the steering operation shaft 40 is turned by the operating force of the operator turning the steering handle 18 and the assisting force of the steering motor 35.

[0074] Then, when the rice transplanter A reaches the second position Q2, which is the front ridge edge position, the operator presses the second registration button 24B of the registration switch 24. In response to this, the teaching memory unit 32 calculates the teaching direction TA, which is the direction connecting the first position Q1 and the second position Q2, based on the positioning data measured by the GPS module 19 at each of the first position Q1 and the second position Q2. In addition, as the rice transplanter A travels from the first position Q1 to the second position Q2, the marker device 10 forms an index line LN.

[0075] Next, as shown by the two-dot chain line in Fig. 5, the operator operates the steering handle 18 to manually turn the rice transplanter A. When the steering angle sensor 44 detects the start of turning the rice transplanter A, the seedling planting device 5, the ground float 16, and the marker device 10 are automatically raised from the surface of the field. Then, when the steering angle sensor 44 detects the end of turning the rice transplanter A, the positioning data at the third position Q3, which is the point where the turning is completed, is stored in the information storage unit 31.

[0076] A dead zone is set in which the operation input of the changeover switch 23 is not accepted until a certain time has elapsed since the steering angle sensor 44 detected the end of turning of the rice transplanter A, and until the deviation angle between the attitude direction NA and the teaching direction TA falls within a predetermined range. In other words, while the state of the rice transplanter A is in the dead zone, the driving mode is not switched from the manual mode to the automatic straight-line mode even if the changeover switch 23 is pressed.

[0077] While the state of rice transplanter A is in the dead zone, the operator can align rice transplanter A by operating the steering handle 18 so that the index line LN is aligned with the line of sight when viewing the tip of the center mascot 45.

[0078] When the state of the rice transplanter A leaves the dead zone, the operation input of the changeover switch 23 becomes acceptable. At this time, when the changeover switch 23 is pressed, the traveling mode of the rice transplanter A switches from the manual mode to the automatic straight-line mode. Then, as shown in Fig. 6, a linear target line LM parallel to the teaching direction TA is generated by the generation unit 33 (see Fig. 3) starting from the fourth position Q4, which is a point a predetermined distance away from the position where the GPS module 19 is installed in the direction of the attitude orientation NA.

[0079] In addition, in Figure 5, for convenience of illustration, the index line LN formed by the marker device 10 and the target line LM are slightly shifted, but in reality, manual alignment is performed so that the operator's line of sight coincides with the tip of the center mascot 45 and the index line LN, and the target line LM is generated so that it approximately coincides with the index line LN.

[0080] 6, for convenience of illustration, the deviation angle between the attitude direction NA and the teaching direction TA is exaggerated, and the indicator line LN is deviated from the target line LM. However, in reality, as described above, the mode does not switch to the automatic straight ahead mode until the deviation angle between the attitude direction NA and the teaching direction TA falls within a predetermined range. Therefore, the deviation angle between the attitude direction NA and the teaching direction TA is relatively small, and the target line LM is generated so as to substantially coincide with the indicator line LN.

[0081] After the target line LM is generated, the steering unit U is controlled so that the position of the aircraft measured by the GPS module 19 moves along the target line LM and so that the attitude direction NA coincides with the teaching direction TA. Specifically, the steering unit U is controlled as follows.

[0082] In the automatic straight-line mode, if there is no angular deviation (hereinafter referred to as the "deviation angle") between the attitude direction NA and the teaching direction TA, and there is no distance deviation (hereinafter referred to as the "deviation distance") between the aircraft position indicated by the positioning data measured by the GPS module 19 and the target line LM, the steering unit U is maintained in its current state.

[0083] Also, in the automatic straight ahead mode, when there is a deviation angle but no deviation distance, the steering unit U is controlled in a direction to reduce the deviation angle.

[0084] Furthermore, in the automatic straight ahead mode, when there is a deviation angle and a deviation distance, the steering unit U is controlled in a direction to reduce the deviation angle.

[0085] Also, in the automatic straight ahead mode, when there is no deviation angle but there is a deviation distance, the steering unit U is controlled in a direction to reduce the deviation distance.

[0086] In the automatic straight-line mode, the steering unit U is controlled as described above, so that the rice transplanter A travels accurately along the target line LM. Accordingly, the seedling planting device 5 accurately plants the seedlings along the target line LM.

[0087] The above-described control of the steering unit U is performed by controlling the drive of the steering motor 35 by a steering angle control unit 27 (see FIG. 3) provided in the control device 21. The steering motor 35 provided in the steering unit U is controlled to control the steering angle of the rice transplanter A. That is, the steering angle control unit 27 is configured to control the steering angle of the rice transplanter A based on the deviation angle and the deviation distance.

[0088] After the target line LM is generated, the rice transplanter A travels along the target line LM, and when it reaches the front ridge, the operator presses the changeover switch 23. This switches the travel mode from the automatic straight-line mode to the manual mode. Then, as shown by the two-dot chain line in Figure 5, the operator operates the steering handle 18 in the same manner as above to manually turn the rice transplanter A.

[0089] Thereafter, by repeating the above-described operations, the operator can plant seedlings in the field in the same manner as described above. This allows the operator to plant seedlings more accurately and more easily in the automatic straight-line mode without operating the steering wheel 18.

[0090] [Control during abnormal conditions] The abnormality detection unit 28 (see FIG. 3) included in the control device 21 is configured to detect an abnormality related to traveling in the automatic straight-ahead mode. When the abnormality detection unit 28 detects an abnormality related to the positioning data as an abnormality related to traveling in the automatic straight-ahead mode, the abnormality control routine shown in FIG. 7 is executed. This abnormality control routine is stored in the routine storage unit 34 included in the control device 21.

[0091] The abnormality control routine in Fig. 7 will be described below. First, a case where the operator does not switch to the manual mode after the abnormality detection unit 28 detects an abnormality in the positioning data while driving in the automatic straight ahead mode will be described as case C1. Note that in all cases described below, it is assumed that radio interference occurs in the GPS module 19 as a specific example of an abnormality in the positioning data.

[0092] [Case C1] When radio interference occurs in the GPS module 19, the radio interference is detected by the abnormality detection unit 28 as an abnormality related to the positioning data, and the abnormality control routine is executed. When the abnormality control routine is executed, the process of step S1 is executed first. In step S1, a predetermined signal is output from the control device 21 to the buzzer 38. Then, the buzzer 38, which has received this signal, issues an alarm sound to notify the abnormality. Then, the process proceeds to step S2.

[0093] In this manner, the buzzer 38 is configured to notify the abnormality when the abnormality detection unit 28 detects the abnormality.

[0094] In step S2, it is determined whether the current driving mode is the automatic straight-line mode. In this case C1, since the vehicle is traveling in the automatic straight ahead mode (YES), the process proceeds to step S3.

[0095] In step S3, a predetermined signal is output from the abnormality deceleration unit 30 (see FIG. 3) of the control device 21 to the hydrostatic continuously variable transmission 37. Then, the hydrostatic continuously variable transmission 37 to which this signal is input changes the speed ratio to the deceleration side. This causes the traveling speed of the rice transplanter A to decelerate. After that, the process proceeds to step S4.

[0096] In this manner, the abnormality deceleration section 30 is configured to decelerate the traveling speed when an abnormality is detected by the abnormality detection section 28 during traveling in the automatic straight-ahead mode.

[0097] In step S4, abnormality steering angle control, which is control of the steering angle based on the angular velocity, is started.

[0098] As described above, the rice transplanter A is usually configured to correct the angular velocity detected by the gyro sensor 20 using the positioning data when calculating the attitude azimuth NA. However, in the abnormality steering angle control, the angular velocity is not corrected using the positioning data. That is, the attitude azimuth NA is calculated based on only the angular velocity, without using the positioning data, of the positioning data and the angular velocity.

[0099] As described above, the rice transplanter A is normally configured to control the steering angle in the automatic straight-line mode based on the deviation angle and deviation distance. The positioning data is used to calculate the deviation distance. However, in the abnormal steering angle control, the deviation distance is not used to control the steering angle. Therefore, in the abnormal steering angle control, the steering angle is controlled by the steering angle control unit 27 based only on the deviation angle.

[0100] Therefore, in the abnormality steering angle control, the attitude direction NA is calculated based only on the angular velocity, and the steering angle is controlled by the steering angle control unit 27 so that the attitude direction NA coincides with the teaching direction TA. That is, in this case, the steering angle is controlled based on the angular velocity.

[0101] In this manner, the steering angle control unit 27 is configured to control the steering angle based on the azimuth data when the abnormality detection unit 28 detects an abnormality in the positioning data in the automatic straight driving mode.

[0102] After the abnormality steering angle control is started in step S4, the process proceeds to step S5. In step S5, a predetermined signal is output from the control device 21 to the display 39. The display 39, to which the signal is input, displays a warning prompting the driver to switch the driving mode to the manual mode. Then, the process proceeds to step S6.

[0103] In this manner, the display 39 is configured to issue a warning urging the driver to switch the driving mode to the manual mode if an abnormality is detected by the abnormality detection unit 28 while the vehicle is driving in the automatic straight-ahead mode.

[0104] In step S6, it is determined whether or not a predetermined distance or time has been traveled since the time when the abnormality was detected by the abnormality detection unit 28. In this embodiment, the process is configured to proceed to step S6 for the first time at a time sufficiently earlier than the time when the predetermined distance or time has been traveled. Therefore, after the process proceeds from step S5 to step S6, NO is determined in step S6, and the process proceeds to step S7.

[0105] The predetermined distance, which is the criterion in step S6, can be set to any distance.Similarly, the predetermined time, which is the criterion in step S6, can be set to any time.

[0106] In step S7, it is determined whether the driving mode has been switched to the manual mode. In this case C1, the driving mode is not switched to the manual mode (NO), so the process returns to step S6. In this case C1, the process thereafter repeats steps S6 and S7 until the vehicle has been driven a predetermined distance or time since the abnormality detection unit 28 detected the abnormality.

[0107] Then, after the vehicle has traveled a predetermined distance or a predetermined time from the time when the abnormality was detected by the abnormality detection unit 28, the determination in step S6 is YES, and the process proceeds to step S8.

[0108] In step S8, a predetermined signal is output from the abnormality stop processing unit 29 (see FIG. 3) of the control device 21 to the brake device 36. The brake device 36, to which this signal is input, brakes the rice transplanter A and stops the rice transplanter A from traveling (corresponding to the "traveling stop processing" of the present invention). After that, this abnormality control routine is temporarily terminated.

[0109] In this manner, when an abnormality is detected by the abnormality detection unit 28 while driving in the automatic straight-line mode, the abnormality stop processing unit 29 is configured to execute driving stop processing after driving a predetermined distance or a predetermined time from the point at which the abnormality was detected by the abnormality detection unit 28.

[0110] [Case C2] Next, as case C2, we will explain a case where, after an abnormality in the positioning data is detected by the abnormality detection unit 28 while driving in the automatic straight-line mode, the operator does not switch to the manual mode, and the abnormality in the positioning data is no longer detected during driving for a specified distance or for a specified time.

[0111] The control flow in case C2 is the same as that in case C1 up to step S5, so the description will start from the point where the process moves from step S5 to step S6.

[0112] In step S6, it is determined whether or not the vehicle has traveled a predetermined distance or for a predetermined period of time since the abnormality was detected by the abnormality detection unit 28. Since this is the first time the process has proceeded to step S6, it is determined that the vehicle has not traveled a predetermined distance or for a predetermined period of time (NO), as in case C1, and the process proceeds to step S7.

[0113] In step S7, it is determined whether the driving mode has been switched to the manual mode. In this case C2, switching to the manual mode has not been performed (NO), so the process returns to step S6.

[0114] In this case C2, an abnormality related to the positioning data is no longer detected during traveling a predetermined distance or for a predetermined time from the time when the abnormality detection unit 28 detected the abnormality.

[0115] However, in this abnormality control routine, there is no step for determining whether an abnormality in the positioning data continues to be detected, and for temporarily terminating the abnormality control routine when the abnormality is no longer detected. Therefore, although an abnormality in the positioning data is no longer detected, the process goes back and forth between step S6 and step S7 until the vehicle has traveled a predetermined distance or time since the abnormality was detected by the abnormality detection unit 28, as in case C1. Then, the process after the vehicle has traveled a predetermined distance or time since the abnormality was detected by the abnormality detection unit 28 is also executed in the same manner as case C1.

[0116] In other words, under the condition that switching to manual mode is not performed after an abnormality in the positioning data is detected by the abnormality detection unit 28 while driving in the automatic straight-line mode, the driving stop process is executed even if an abnormality in the positioning data continues to be detected or even if the abnormality in the positioning data is no longer detected.

[0117] Furthermore, in this manner, the abnormality stop processing unit 29 is configured to execute driving stop processing after driving a predetermined distance or a predetermined time from the point at which the abnormality was detected by the abnormality detection unit 28, if an abnormality in the positioning data is no longer detected during driving a predetermined distance or a predetermined time after the abnormality detection unit 28 detects the abnormality.

[0118] [Case C3] Next, as case C3, we will explain a case where an abnormality in the positioning data is detected by the abnormality detection unit 28 while driving in the automatic straight-line mode, and then the operator switches to manual mode while driving a specified distance or for a specified time.

[0119] The flow of control in case C3 is the same as that in case C1 up to step S5, so the description will start from the point where the process moves from step S5 to step S6.

[0120] In step S6, it is determined whether or not the vehicle has traveled a predetermined distance or for a predetermined period of time since the abnormality was detected by the abnormality detection unit 28. Since this is the first time the process has proceeded to step S6, it is determined that the vehicle has not traveled a predetermined distance or for a predetermined period of time (NO), as in case C1, and the process proceeds to step S7.

[0121] In step S7, it is determined whether the driving mode has been switched to the manual mode. In this case C3, after an abnormality in the positioning data is detected by the abnormality detection unit 28, the driving mode is switched to the manual mode during driving for a predetermined distance or a predetermined time. That is, until the driving mode is switched to the manual mode, the process goes back and forth between step S6 and step S7, as in case C1.

[0122] After the mode is switched to the manual mode, the result of the determination in step S7 is YES, and the abnormality control routine is temporarily terminated. Therefore, in this case, the running stop process is not executed.

[0123] In this manner, the abnormality stop processing unit 29 is configured not to execute the traveling stop processing when the traveling mode is switched to the manual mode during traveling a predetermined distance or a predetermined time.

[0124] [Case C4] Next, a case C4 will be described in which the abnormality detection unit 28 detects an abnormality in the positioning data while the vehicle is traveling in the manual mode.

[0125] The control flow in case C4 is the same as that in case C1 up to step S1, so the description will start from the point where the process moves from step S1 to step S2.

[0126] In step S2, it is determined whether the current driving mode is the automatic straight-ahead mode. In this case C4, the vehicle is traveling in the manual mode (NO), so the process proceeds to step S9.

[0127] In step S9, a predetermined signal is output from the control device 21 to the abnormality signal receiving unit 25b included in the driving mode switching unit 26. When this signal is input, the driving mode switching unit 26 is configured to prohibit the transmission of a signal from the switching signal transmitting unit 25a to the control device 21. In other words, after the predetermined signal is input to the abnormality signal receiving unit 25b, the driving mode will not be switched to the automatic straight driving mode even if the changeover switch 23 is pressed. After that, this abnormality control routine is temporarily terminated.

[0128] In this manner, the driving mode switching unit 26 is configured to prevent the driving mode from being switched to the automatic straight driving mode when an abnormality is detected by the abnormality detection unit 28.

[0129] According to the configuration described above, if an abnormality occurs with respect to driving in the automatic straight-line mode, the driving stop process is executed after driving a predetermined distance or a predetermined time from the time when the abnormality is detected. Therefore, it is possible to avoid continuing driving in the automatic straight-line mode for a relatively long distance or long time while the steering control remains inaccurate due to an abnormality with respect to driving in the automatic straight-line mode.

[0130] Moreover, since the buzzer 38 notifies the operator of the abnormality, the operator can know in advance that the traveling stop process will be executed after the vehicle has traveled a predetermined distance or time. This makes it easy to avoid a situation in which the operator is surprised by the sudden execution of the traveling stop process.

[0131] In addition, if an abnormality occurs in the automatic straight-line driving mode while the vehicle is driving in the automatic straight-line driving mode, the abnormality may cause the steering control to become inaccurate. If the driving time is constant, the deviation of the actual driving line from the target driving line (target line LM) caused by such inaccurate steering control tends to become smaller as the driving speed becomes slower.

[0132] According to the configuration described above, if an abnormality occurs in the automatic straight-line driving mode while the vehicle is driving in the automatic straight-line driving mode, the vehicle speed is decelerated. Therefore, if the driving time is constant, the deviation of the actual driving line from the target driving line is likely to be small compared to the case where the deceleration operation is not performed. In other words, the time until the deviation of the driving line becomes relatively large is secured longer.

[0133] Moreover, the operator can know that an abnormality has occurred based on the fact that the traveling speed of the rice transplanter A in the automatic straight-line mode has decreased. Then, the operator who knows that an abnormality has occurred can take measures such as stopping the traveling or switching to the manual mode. Therefore, it is possible to secure more time for the operator to consider the above-mentioned measures between the occurrence of an abnormality and the deviation of the traveling line becoming relatively large.

[0134] [First Alternative Embodiment] The control device 21 in the above embodiment is provided with an abnormality stop processing unit 29. The abnormality control routine is configured to execute a travel stop process in step S8.

[0135] However, the present invention is not limited thereto. The following describes the first embodiment of the present invention, focusing on the differences from the above embodiment. The configuration other than the parts described below is the same as the above embodiment. Also, the same reference numerals are used for the same configuration as the above embodiment.

[0136] 8 and 9 are a functional block diagram and a diagram showing an abnormality control routine in a first alternative embodiment according to the present invention. As shown in Fig. 8, the control device 21 does not include an abnormality stop processing unit 29, but instead includes an abnormality switching unit 49. Also, as shown in Fig. 9, if the determination in step S6 in the abnormality control routine is YES, the process proceeds to step S10. Then, in step S10, the driving stop process is not executed, and the driving mode is switched to the manual mode.

[0137] The abnormality control routine in Fig. 9 will now be described. First, a case where the operator does not switch to the manual mode after the abnormality detection unit 28 detects an abnormality in the positioning data while traveling in the automatic straight ahead mode will be described as case C5.

[0138] [Case C5] The flow of control in case C5 is the same as that in case C1 in the above embodiment from when an abnormality is notified by the buzzer 38 in step S1 to when a YES determination is made in step S6. Therefore, the description will begin from the point at which the process moves from step S6 to step S10.

[0139] In step S10, the abnormality switching unit 49 (see FIG. 8) switches the driving mode to the manual mode, after which the abnormality control routine ends.

[0140] Furthermore, in this manner, when an abnormality is detected by the abnormality detection unit 28 while driving in the automatic straight-line mode, the abnormality switching unit 49 is configured to switch the driving mode to the manual mode after driving a predetermined distance or a predetermined time from the point at which the abnormality was detected by the abnormality detection unit 28.

[0141] [Case C6] Next, as case C6, we will explain a case where, after an abnormality in the positioning data is detected by the abnormality detection unit 28 while driving in the automatic straight-line mode, the operator does not switch to manual mode, and the abnormality in the positioning data is no longer detected during driving for a specified distance or for a specified time.

[0142] The control flow in case C6 is the same as that in case C1 up to step S5, so the description will start from the point where the process moves from step S5 to step S6.

[0143] In step S6, it is determined whether or not the vehicle has traveled a predetermined distance or for a predetermined period of time since the abnormality was detected by the abnormality detection unit 28. Since this is the first time the process has proceeded to step S6, it is determined that the vehicle has not traveled a predetermined distance or for a predetermined period of time (NO), as in case C1, and the process proceeds to step S7.

[0144] In step S7, it is determined whether the driving mode has been switched to the manual mode. In this case C6, switching to the manual mode has not been performed (NO), so the process returns to step S6.

[0145] In this case C6, an abnormality related to the positioning data is no longer detected during traveling a predetermined distance or for a predetermined time from the time when the abnormality detection unit 28 detected the abnormality.

[0146] However, in this abnormality control routine, there is no step for determining whether an abnormality in the positioning data continues to be detected, and for temporarily terminating the abnormality control routine when the abnormality is no longer detected. Therefore, although an abnormality in the positioning data is no longer detected, the process goes back and forth between step S6 and step S7 until the vehicle has traveled a predetermined distance or a predetermined time since the abnormality was detected by the abnormality detection unit 28, as in case C1. Then, after the vehicle has traveled a predetermined distance or a predetermined time since the abnormality was detected by the abnormality detection unit 28, the process proceeds to step S10, and the process in step S10 is executed in the same manner as in case C5.

[0147] In other words, under the condition that switching to manual mode is not performed after an abnormality in the positioning data is detected by the abnormality detection unit 28 while driving in the automatic straight-line mode, switching to manual mode is performed by the abnormality switching unit 49 even if an abnormality in the positioning data continues to be detected or even if an abnormality in the positioning data is no longer detected.

[0148] Furthermore, in this way, if an abnormality in the positioning data is detected by the abnormality detection unit 28 and then no abnormality in the positioning data is detected during driving for a specified distance or for a specified time, the abnormality switching unit 49 is configured to switch the driving mode to the manual mode after driving for a specified distance or for a specified time from the point at which the abnormality was detected by the abnormality detection unit 28.

[0149] According to the configuration of the first alternative embodiment described above, if an abnormality occurs in the automatic straight-line driving mode, the driving mode is switched to the manual mode after a predetermined distance or time of driving from the time the abnormality is detected. This makes it possible to avoid continuing driving in the automatic straight-line driving mode for a relatively long distance or long time while the steering control remains inaccurate.

[0150] Moreover, because the buzzer 38 warns of an abnormality, the operator can know in advance that the driving mode will be switched to the manual mode after a predetermined distance or time of driving. This makes it easy to avoid a situation in which the operator is surprised by the driving mode suddenly being switched to the manual mode.

[0151] Other embodiments (1) In the above embodiment and the first alternative embodiment, the driving mode switching unit 26 is provided with the changeover switch 23. The driving mode is switched between the automatic straight-line mode and the manual mode by the operator pressing the changeover switch 23. However, the present invention is not limited to this. For example, the driving mode switching unit 26 may not be provided with the changeover switch 23, and may be configured to automatically switch the driving mode.

[0152] (2) In the above embodiment and the first alternative embodiment, it is assumed that radio interference occurs in the GPS module 19 as a specific example of an abnormality related to the positioning data. However, the abnormality related to the positioning data according to the present invention is not limited to radio interference. For example, a malfunction of the measurement function of the positioning data in the GPS module 19 and a malfunction of the input / output system of the positioning data between the GPS module 19 and the control device 21 are also included in the abnormality related to the positioning data. Therefore, the abnormality detection unit 28 may be configured to detect these malfunctions.

[0153] (3) In the above embodiment and the first alternative embodiment, when an abnormality related to the positioning data is detected by the abnormality detection unit 28, the abnormality control routine is executed. However, the present invention is not limited to this. The abnormality control routine may be configured to be executed not only when an abnormality related to the positioning data is detected, but also when an abnormality related to driving in the automatic straight-line mode is detected. Note that an abnormality related to the positioning data is included in the abnormality related to driving in the automatic straight-line mode. In addition, for example, a malfunction of the steering angle control unit 27 or a malfunction of the steering motor 35 is also included in the abnormality related to driving in the automatic straight-line mode. Therefore, the abnormality detection unit 28 may be configured to detect these malfunctions.

[0154] (4) In the above embodiment and the first alternative embodiment, the gyro sensor 20 is configured to output the angular velocity of the turning angle of the rice transplanter A as the equivalent of the orientation data according to the present invention. However, the present invention is not limited to this. The gyro sensor 20 may be configured to output the integral value of the angular velocity or the attitude orientation NA of the vehicle as the equivalent of the orientation data according to the present invention.

[0155] (5) In the abnormality control routine in the above embodiment and the first alternative embodiment, after the determination in step S2 is NO, the process proceeds to step S9. Then, in step S9, the transmission of a signal from the switching signal transmission unit 25a to the control device 21 is prohibited, thereby preventing the driving mode from being switched to the automatic straight-line mode. However, the present invention is not limited to this. For example, the control device 21 may be configured to output a predetermined signal to the driving mode switching unit 26 in step S9, and the driving mode switching unit 26 may be configured to permit switching to the manual mode and prohibit switching to the automatic straight-line mode when the signal is input. In addition, the position of step S9 may be changed to a position upstream of step S2, between step S2 and step S3, or downstream of step S3.

[0156] (6) In the above embodiment and the first alternative embodiment, in step S3 of the abnormality control routine, the abnormality deceleration unit 30 changes the speed ratio of the hydrostatic continuously variable transmission 37 to the deceleration side, thereby decelerating the traveling speed of the rice transplanter A. However, the present invention is not limited to this. The abnormality deceleration unit 30 may be configured to operate the brake device 36 in step S3, thereby decelerating the traveling speed of the rice transplanter A.

[0157] (7) In the above embodiment, as the travel stop processing in step S8 of the abnormality control routine, the abnormality stop processing unit 29 stops the travel of the rice transplanter A by operating the brake device 36. However, the present invention is not limited to this. The abnormality stop processing unit 29 may be configured to stop the travel of the rice transplanter A by stopping the drive of the engine 8 as the travel stop processing.

[0158] (8) In the above embodiment and the first alternative embodiment, the buzzer 38 is provided as the notification unit. However, the present invention is not limited to this. For example, a lamp may be provided as the notification unit. Furthermore, the display 39 provided as the warning unit may be configured to also function as the notification unit.

[0159] (9) In the above embodiment and the first alternative embodiment, the display 39 is provided as the warning unit. However, the present invention is not limited to this. For example, a lamp may be provided as the warning unit. In addition, the buzzer 38 provided as the notification unit may be configured to also function as the warning unit.

[0160] (10) In the above embodiment and the first alternative embodiment, when planting seedlings in a paddy field that is rectangular in top view, the first straight-line travel is performed in manual mode, and the teaching direction TA must be determined using the first registration button 24A and the second registration button 24B. Also, each time a turn in manual mode is completed at the edge of a paddy field and travel in automatic straight-line mode is started, only one target line LM is generated in front of the rice transplanter A. However, the present invention is not limited to this. The shape of the paddy field may be stored in the control device 21, and multiple target lines LM suitable for the shape of the paddy field may be generated throughout the entire paddy field when work is started. [Industrial Applicability]

[0161] In addition to the above-mentioned riding rice transplanter equipped with a seedling planting device as a working device, the present invention can be used in various work vehicles, such as a riding direct seeder, which is a planting-type paddy field work vehicle equipped with a sowing device as a working device, a tractor equipped with a plow or the like as a working device, or an agricultural work vehicle such as a combine harvester equipped with a harvesting section or the like as a working device, or a construction work vehicle equipped with a bucket or the like as a working device. [Explanation of symbols]

[0162] 19 GPS Module 20 Gyro sensor 23 Changeover switch 26 Driving mode switching section 27 Steering angle control unit 28 Anomaly detection unit 29. Abnormal stop processing section 30 Abnormality reduction section 38 Buzzer (alarm section) 39 Display (Warning section) 49 Abnormality switching section NA attitude heading

Claims

1. a driving mode switching unit that switches a driving mode between an automatic straight-line mode and a manual mode; An abnormality detection unit that detects an abnormality related to traveling in the automatic straight-line mode, a warning unit that notifies the user that the automatic straight-line driving mode will be terminated when the abnormality is detected by the abnormality detection unit during driving in the automatic straight-line driving mode, When the warning unit notifies the end of the automatic straight-line driving mode, the work vehicle automatically switches the driving mode to the manual mode or stops driving after a predetermined time has elapsed from the time when the end of the automatic straight-line driving mode was notified.

2. 2. The work vehicle according to claim 1, wherein even if the abnormality is resolved within a predetermined time from the time when it is notified that the automatic straight-line driving mode will be terminated, the driving mode is automatically switched to the manual mode or driving is stopped after the predetermined time has elapsed from the time when it is notified that the automatic straight-line driving mode will be terminated.

3. 3. The work vehicle according to claim 1, wherein the automatic straight-line driving mode is a driving mode in which the work vehicle automatically drives in a straight line based on positioning data obtained by a satellite positioning system.

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