TWI842657B - Work vehicle - Google Patents

Abstract

Conventional work vehicles such as rice transplanters cannot perform turning control of the vehicle body. The work vehicle of the present invention includes: a steering member driving device that drives the steering member; a control device that controls the steering member driving device; and a detection mechanism that is configured to detect the turning state related to the vehicle body. The control device performs turning control when turning the vehicle body between a first straight moving operation and a second straight moving operation, wherein the turning control performs a first turn and a second turn in sequence; the control device performs turning state determination of the first turn based on the result of the detection, and adjusts the magnitude of the turning locus of the second turn based on the turning state determination of the first turn, and sets that there is no straight moving between the first turn and the second turn, and keeps the steering turning angles of the first turn and the second turn as substantially constant.

Description

Working vehicles

The present invention relates to a working vehicle such as a rice transplanter traveling in a farmland.

The following rice transplanter is known, which has: a planting device that can be mounted on a vehicle body so as to be able to be raised and lowered; a steering motor that drives a steering handle; and a control device that controls the vehicle body to move straight and turn by driving the steering handle with the steering motor (for example, refer to Patent Document 1). [Prior Technical Document] [Patent Document]

[Patent Document 1] Japanese Patent Application Publication No. 2008-92818.

[The problem that the invention wants to solve]

However, the aforementioned conventional working vehicle such as the rice transplanter has a low rotation control accuracy of the vehicle body, and therefore cannot accurately perform continuous driving in a straight-line control to the next process.

The purpose of the present invention is to provide a working vehicle capable of performing rotation control of the vehicle body in consideration of the above-mentioned previous problems. [Means for solving the problem]

Scheme 1 of the present invention is a working vehicle, comprising: a steering component driving device (44) for driving a steering component (52); a control device (200) for controlling the steering component driving device (44); and a detection mechanism for performing detection related to the rotation state of a vehicle body (10), wherein the control device (200) performs rotation control when the vehicle body (10) rotates between a first straight motion and a second straight motion, and the detection mechanism The rotation control performs a first rotation and a second rotation in sequence. The control device (200) determines the rotation state of the first rotation based on the detection result, and adjusts the size of the rotation trajectory of the second rotation based on the rotation state determination of the first rotation, and sets the first rotation and the second rotation to be non-straight, and keeps the turning rotation angles in the first rotation and the second rotation approximately constant.

Scheme 2 of the present invention is a working vehicle as described in scheme 1 of the present invention, wherein in order to make the vehicle body (10) in the aforementioned rotation go straight again, the aforementioned control device (200) changes the turning angle return timing of the aforementioned turning angle in the aforementioned second rotation based on the aforementioned rotation state judgment, thereby controlling the aforementioned turning angle.

A third embodiment of the present invention is a working vehicle as described in the second embodiment of the present invention, wherein the turning angle return timing can be adjusted based on a manual operation of adjusting a predetermined turning angle return level.

The fourth invention is a working vehicle as described in any one of the schemes 1 to 3 of the present invention, wherein the detection mechanism is provided with a rear wheel speed sensor (210) and a positioning system (300). When a turn starts, the rear wheel speed sensor (210) starts measuring the travel distance. When the orientation of the vehicle body (10) reaches a predetermined angle, if the travel distance is longer, the positioning system (300) determines that the turn is a large turn, and if the travel distance is shorter, the positioning system (300) determines that the turn is a small turn.

Scheme 5 of the present invention is a working vehicle as described in any one of schemes 1 to 3 of the present invention, wherein a rear wheel speed sensor (210) and a positioning system (300) are provided in the detection mechanism, and the measurement of the driving distance is started by the rear wheel speed sensor (210) when the rotation starts. When the driving distance reaches a predetermined distance, if the orientation change of the vehicle body (10) from the start of the rotation is small, the positioning system (300) determines that the rotation has become a large rotation, and if the orientation change of the vehicle body (10) from the start of the rotation is large, the positioning system (300) determines that the rotation has become a small rotation. [Effect of the invention]

According to solution 1 of the present invention, the rotation control of the vehicle body can be performed.

According to the second aspect of the present invention, in addition to the effects of the first aspect of the present invention, high-precision control can be achieved.

According to the scheme 3 of the present invention, in addition to the effects of the scheme 2 of the present invention, highly flexible control can be achieved.

According to aspect 4 of the present invention, in addition to the effects of any one of aspects 1 to 3 of the present invention, highly precise control can be achieved.

According to Scheme 5 of the present invention, in addition to the effects of any one of Schemes 1 to 3 of the present invention, when it is judged that a large rotation has occurred, the steering is controlled in such a way that the body comes to the inside, and when it is judged that a small rotation has occurred, the steering is controlled in such a way that the body comes to the outside, thereby improving the rotation accuracy.

The embodiments of the present invention will be described in detail with reference to the drawings.

The same is true below, but some components are not shown in the drawings, and are sometimes shown in a transparent or omitted manner.

The rice transplanter of this embodiment is an example of a working vehicle in the present invention or inventions related to the present invention.

In a modified embodiment, for example, the working vehicle in the present invention or inventions related to the present invention may also be an agricultural tractor.

The operating handle (52) is an example of a steering member in the present invention or inventions related to the present invention. The operating motor (44) is an example of a steering member driving device for driving the operating handle (52) in the present invention or inventions related to the present invention.

The control device (200) is an example of a control device for controlling a manipulation motor (44) in the present invention or inventions related to the present invention.

The vehicle body (10) is an example of a vehicle body in the present invention or inventions related to the present invention. The rear wheel rotation speed sensor (210) and the positioning system (300) are examples of detection mechanisms for detecting the rotation state of the vehicle body (10) in the present invention or inventions related to the present invention.

The auxiliary wheel (33) is an example of a single or multiple auxiliary wheels installed on at least one of the inner side and the outer side of the vehicle body (10) in the left and right directions of the vehicle body in the present invention or inventions related to the present invention.

The inner rear wheel (32) is an example of a predetermined wheel in the present invention or inventions related to the present invention.

First, the configuration and operation of the rice transplanter according to the present embodiment will be specifically described with reference to Figs. 1 and 2 .

Here, FIG. 1 is a perspective view of a rice transplanter according to an embodiment of the present invention, and FIG. 2 is a block diagram of a power transmission system of the rice transplanter according to an embodiment of the present invention.

While explaining the action of the rice transplanter of this embodiment, the driving control method of the invention related to the present invention is also explained.

The rice transplanter of this embodiment is a riding seedling transplanter for eight-row planting. The planting device (100) has four planting units, and each planting unit has two planting tools in a left and right pair.

The rice transplanter is not limited to the riding pad seedling transplanter for eight-row planting, and for example, it can also be a riding pot seedling transplanter for ten-row planting.

First, the basic structure and operation of the rice transplanter of this embodiment will be described. Therefore, the swivel control and the like will be described in detail later.

The driving unit (50) has a seat (51) disposed above the engine (20).

A control handle (52) for operating the front wheel (31) is provided in front of the seat (51). In addition, horizontal foot pedals (step floors) are provided on the left and right sides of the engine (20). In addition, a prepared seedling loading platform (101) is provided on the vehicle body (10).

The driving device (30) is a device for driving the vehicle body (10) by using the front wheels (31) and the rear wheels (32).

The land leveling device (60) is a device for leveling farmland by using a land leveling rotor mechanism (61) and a land leveling floating mechanism (62).

A marking device (80) for marking a straight line that becomes a target of the next planting driving path toward the farmland is installed on the vehicle body (10) in a retractable manner.

The planting device (100) is installed on the rear side of the vehicle body (10) via the planting device lifting device (90).

The rotational power of the engine (20) mounted on the main frame is transmitted to the main transmission mechanism (41) as an HST (Hydro Static Transmission; hydraulic stepless transmission) mechanism. The rotational power after the speed change in the main transmission mechanism (41) and the auxiliary transmission mechanism (42) is separated into the driving power used in the driving device (30) and the external extraction power used in the planting device (100) and the like.

A portion of the driving power is transmitted to the left and right front wheel end housings to drive a pair of left and right front wheels (31), and the remaining driving power is transmitted to the left and right rear wheel gear boxes (43) to drive a pair of left and right rear wheels (32). In addition, a portion of the driving power transmitted to the rear wheel gear boxes (43) is transmitted to the land preparation device (60) and the fertilizer application device (70).

Next, the configuration and operation of the rice transplanter of this embodiment will be described in more detail with reference mainly to FIGS. 1 to 3 .

Here, FIG. 3 is a block diagram of a control system of a rice transplanter according to an embodiment of the present invention.

The control device (200) is a device that not only performs lever operations of the main gear lever (53), the auxiliary gear lever (54) or the straight-moving assist lever (55) and switch operations of the assist mode switch (56), but also performs various controls by utilizing the detection results of the rear wheel speed sensor (210) or the planting device lifting sensor (220).

The positioning system (300) is, for example, a system that uses a typical GNSS (Global Navigation Satellite System), namely a GPS (Global Positioning System), to perform positioning using a DGPS (Differential Global Positioning System) technology.

In driving control, since the size of the vehicle body (10), the responsiveness of the operating motor (44), and the state of the farmland must be comprehensively considered, even if the positioning performed by the positioning system (300) is extremely accurate temporarily, it is difficult to achieve precise driving control, so various attempts are known.

In the straight-ahead control, a positioning system (300) for acquiring current position information of a vehicle body (10) is used to pre-register the coordinates of a point A corresponding to the starting point of the straight-ahead driving for planting work and the coordinates of a point B corresponding to the end point of the straight-ahead driving. Furthermore, a driving control motor (44) is used to perform steering so that the straight-ahead driving is performed based on an imaginary line connecting the points A and B, thereby realizing the straight-ahead control.

However, since the straight-line control must be turned on and off every time a manual steering operation is required, the burden on the operator has not been reduced, and the operability and workability may not be sufficient.

Therefore, it is desired to realize not only straight-line control but also rotary control for automatically aligning the rows for the planting row distance, so the following basic rotary control is considered.

Of course, it goes without saying that the method of the swivel control described below can be used in various swivel controls. Specifically, one of the various swivel controls described above is, for example, a swivel control in which the vehicle body (10) does not include a straight-line motion during the swivel, the steering angle is kept substantially constant during the swivel, and the swivel path of the vehicle body (10) is a substantially semicircular path.

((A1)) Next, the configuration and operation of the rice transplanter according to the present embodiment will be described in more detail with reference mainly to FIG. 4 and FIG. 5 .

Here, FIG. 4 is an explanatory diagram (first) of the swirl control of the rice transplanter in the embodiment of the present invention, and FIG. 5 is an enlarged explanatory diagram of the swirl control of the rice transplanter in the embodiment of the present invention.

The rice transplanter of this embodiment is a rice transplanter in which a control device (200) performs rotation control when rotating a vehicle body (10) that is moving straight.

The control device (200) determines the rotation state based on the detection result, and controls the turning angle based on the rotation state determination.

For example, in the automatic rotation control of the rice transplanter, the control is performed in a state where the steering rotation angle is fixed at a constant α (for example, 45 degrees) in the automatic rotation in a manner that does not include a straight-line action during the rotation. In the control of setting the rotation path with the GPS and performing the rotation along the path, it is sometimes difficult to control and unstable. In addition, if the steering is turned during the rotation, the rotation of the rear wheel on the inner side of the rotation changes, that is, the so-called Z turn and other control instability occur. By setting the steering rotation angle to be constant, it is easy to control and the versatility is greater for various machine models. Since the steering turning angle is constant, the rotation of the inner rear wheel is stable, and it is easy to judge that if the rotation speed of the inner rear wheel is low, it is a small turn, and if the rotation speed is high, it is a large turn without adding sensors.

In order to make the turned vehicle body (10) go straight again, the control device (200) changes the turning angle return timing of the return turning angle based on the turning state judgment, thereby controlling the turning angle.

The turning angle return timing is the timing when the difference between the orientation of the turned vehicle body (10) and the orientation for making the vehicle body (10) go straight again is lower than a predetermined turning angle return level.

For example, the turn angle back to horizontal is 30 degrees.

The steering angle return timing can be adjusted based on a manual operation to adjust a predetermined steering angle return level.

For example, the turning angle return level can be reduced to 25 degrees or increased to 35 degrees by operating the dial of the threshold adjustment device (400) based on the operator's experience.

The time when the turn state is determined is the time when the arrow (A) is located based on the direction such as the direction of the aircraft or the right angle direction of the aircraft, distance, time, GNSS position, or vehicle speed. The turn state is determined based on the direction, distance, time, GNSS position, or vehicle speed.

For example, the difference between the orientation of the vehicle body (10) being rotated and the orientation that makes the vehicle body (10) go straight again, that is, when the body orientation is 45 degrees, is given time to determine the size of the rotation trajectory.

When it is determined that the turning trajectory of the vehicle body (10) starting from the turning start position (Ps) on the straight line (Lv0) as the front process line is a turning trajectory (C0) of a standard size, the turning angle return timing is not changed, and the turning angle returns at the moment when the turning angle of the standard 30 degrees returns to the horizontal position (P0). Even if the turning angle return timing is not changed, the vehicle body (10) can enter the straight control transition area (Z) as it reaches the imaginary line (Lh0) in front of the planting start line (Lh), thereby performing a smooth transition to the straight control for making the vehicle body (10) automatically go straight again along the straight line (Lv).

The transition from the turning control to the straight-ahead control is performed, for example, when entry into the straight-ahead control transition area (Z) is recognized based on the GNSS position.

In order to make a smooth transition to the straight line control, it is preferable to achieve a state in which not only the approach angle to the straight line (Lv) but also the turning angle does not increase much before the straight line control transition area (Z) as the vehicle approaches the straight line (Lv) as the next process line.

The inventor changes the turning angle return timing based on the turning state determination, thereby making the turning angle return irrelevant to the turning state that is easily affected by the farmland state, etc., and ensuring a smooth transition to this type of straight-ahead control.

Specifically, the turning angle return timing can be changed as follows based on the determination of the size of the turning trajectory.

When it is determined that the turning trajectory is a turning trajectory (C1) with a small turn, the turning angle is returned to the horizontal position (Q1) at a turning angle of 35 degrees, which is larger than 30 degrees, instead of returning to the horizontal position (P1) at the standard turning angle of 30 degrees. In this way, even if the turning trajectory is a turning trajectory (C1) with a small turn, the vehicle body (10) can drive close to the straight line (Lv) and enter the straight control transition area (Z), so that a smooth transition to the straight control is also performed.

When the turning trajectory is determined to be a turning trajectory (C2) of a large turn, the turning angle is returned to a horizontal position (Q2) at a turning angle of 25 degrees, which is smaller than 30 degrees, instead of returning to a horizontal position (P2) at a standard turning angle of 30 degrees. In this way, even if the turning trajectory is a turning trajectory (C2) of a large turn, the vehicle body (10) can enter the straight control transition area (Z) without driving far away from the straight line (Lv), so that a smooth transition to the straight control is also performed.

Of course, the change of the turning angle return timing can be based on the direction in this way, but it can also be based on distance, time, GNSS position or vehicle speed, so as to correct the movement path for a smooth transition to straight-ahead control.

In addition, in the swivel assist correction control using the rear wheel pulse, the swivel inner rear wheel pulse is measured from the start of the automatic swivel control in order to know the rear wheel rotation speed used to determine the size of the swivel trajectory. The pulse number of the inner rear wheel during automatic swivel has little effect on slippage, etc., so it can be determined whether the swivel action is normal.

In the automatic swing control of the rice transplanter, the pulse number of the inner rear wheel is measured from the start of the automatic swing control to the predetermined position (θ0) of the machine body. (θ0) is set to be greater than 45 degrees. Based on the rear wheel pulse number at the time of the machine body position (θ0), it is determined whether to add correction to the automatic swing control. If (θ0) is less than 45 degrees, even if correction is added to the automatic swing control, there is a risk that the control will not be completed in time and the swing accuracy will be deteriorated.

When the pulse number at this time is from p1 to p2, it is determined that the rotation is progressing normally, and the control is set to not perform correction control. By setting the width from p1 to p2 to the appropriate value of the rear wheel pulse on the inner side of the rotation in the automatic rotation control, the rotation accuracy can be improved without adding unnecessary correction control.

When the pulse number p is p≧p2, it is judged that the rotation has become a large rotation, and the steering return to the starting position is delayed so that the machine body moves to the inside to start planting alignment. When it is judged that it has become a large rotation based on the rear wheel rotation speed, the steering return to the starting position is controlled so that the machine body moves to the inside to start planting alignment, thereby improving the rotation accuracy.

When the pulse number p is p≦p1, it is judged that the rotation has become a small rotation, and the control is performed to delay the turning back to the starting position so that the machine body moves to the outside in advance to start planting alignment. When it is judged that it has become a small rotation based on the rear wheel speed, the steering is controlled to return to the starting position so that the machine body moves to the outside so that planting alignment can be started, thereby improving the rotation accuracy.

Although the size of the turning trajectory can be determined based on the size of the rear wheel rotation speed at the moment when the machine body position reaches a predetermined angle in this way, the size of the turning trajectory can also be determined based on the size of the machine body position at the moment when the rear wheel rotation speed reaches a predetermined number of positions. For example, when the size of the machine body position at the moment when the rear wheel rotation speed reaches a predetermined number of positions is small, it can be determined that the turning is a large turning, and control can be performed to delay the turning back to the starting position so that the machine body moves to the inside so as to start the planting alignment.

The final result is determined based on a single or multiple physical quantities selected from the direction, distance, time, GNSS position or vehicle speed to determine the moment of the rotation state judgment. Although the rotation state can also be determined based on the same physical quantity, the combination of these physical quantities is arbitrary. For example, the moment of the rotation state judgment can be determined based on the distance and GNSS position, and the rotation state judgment can be performed based on the direction and vehicle speed.

Furthermore, although the turning angle return timing can be changed based on a single or multiple physical quantities selected from the azimuth, distance, time, GNSS position or vehicle speed, the turning angle return timing can be determined independently or subordinately based on the physical quantity based on the control of the turning angle, such as the change of the turning angle return timing. For example, the timing of turning state determination can also be determined based on time, the turning state determination is determined based on the vehicle speed, and the turning angle return timing is changed based on the azimuth and GNSS position.

The control device (200) may also control the turning angle by changing the constant angle based on the turning state determination after maintaining the turning angle at a constant angle until the turning state determination time.

When the pulse number p is p≧p2, it is determined that the wheel is turning into a large wheel, and the steering wheel angle α, which is a constant angle, is controlled to become a small wheel with a yaw increase. When it is determined that the wheel is turning into a large wheel based on the rear wheel rotation speed, the steering is controlled to become a small wheel, thereby improving the turning accuracy.

When the pulse number p is p≦p1, it is determined that the turn is a small turn, and the steering turn angle α, which is a constant angle, is controlled to turn back to a large turn. When it is determined that the turn is a small turn based on the rear wheel rotation speed, the steering is controlled to a large turn, thereby improving the turn accuracy.

It goes without saying that the change of the constant angle such as the deflection increase or deflection return of the manipulation rotation angle α can also be performed simultaneously with the rotation state judgment. For example, it can also be performed 0.2 seconds after the rotation state judgment.

In order to make the turned vehicle body (10) go straight again, the control device (200) can also change the turning angle return speed of the return turning angle based on the turning state judgment, thereby controlling the turning angle.

Of course, the change of the turning angle return speed can replace the change of the turning angle return time, or can be carried out simultaneously with the change of the turning angle return time, so as to smoothly correct the movement path. For example, the body orientation of the return turning angle can also be constant, or only the turning angle return speed can be changed.

The return of the turning angle can also be performed simultaneously with the turning state determination. It goes without saying that, for example, it can also be performed 0.2 seconds after the turning state determination.

In the configuration capable of adjusting the turning angle return speed, even if the timing of the turning state determination is very close to the turning angle return timing, the turning angle can be returned without delay by increasing the turning angle return speed.

(A2) Next, the configuration and operation of the rice transplanter according to the present embodiment will be described in more detail mainly with reference to FIG. 6 .

Here, FIG. 6 is an explanatory diagram of the reverse turning control of the rice transplanter according to the embodiment of the present invention.

The rice transplanter of this embodiment is a rice transplanter in which a control device (200) performs a swivel control when a vehicle body (10) that is moving straight stops and moves backward, stops again, and then swivels.

After going straight backward from the point (S1) to the point (S2), the vehicle automatically or semi-automatically turns from the point (S2) to the point (S5) via the points (S3) and (S4).

Of course, in the case of the automatic control HST mode such as the hole planting control and the hole approach control in the rotation control, the configuration of not starting the rotation assist control is also considered. This is because if the rotation assist starts due to mistakenly approaching the hole, the HST may produce unexpected movements. Therefore, it is desired to prevent unexpected HST movements.

The rice transplanter of this embodiment is as follows: the control device (200) performs straight-moving control before the rotation when the rotating vehicle body (10) is made to move straight, performs rotation control when the vehicle body (10) is made to move straight, and performs straight-moving control after the rotation when the rotating vehicle body (10) is made to move straight again.

The switch from the straight-ahead control to the turning control is performed manually.

Of course, the switching from the straight control before the rotation to the rotation control is the same as the switching from the rotation control to the straight control after the rotation. Both automatic implementations and manual implementations are considered.

In order to make the turned vehicle body (10) go straight again, the turning angle return timing for returning the turning angle is set to a timing before the straight-moving control start timing of the straight-moving control after the start of the turn.

The turning angle return timing is the timing when the difference between the orientation of the turned vehicle body (10) and the orientation for making the vehicle body (10) go straight again is lower than a predetermined turning angle return level.

As described above, for example, the turning angle back to horizontal is 30 degrees.

The steering angle return timing can be adjusted based on a manual operation to adjust a predetermined steering angle return level.

As described above, for example, the turning angle return level can be reduced to 25 degrees or increased to 35 degrees by operating the dial of the threshold adjustment device (400) based on the operator's experience. [Industrial Applicability]

The working vehicle of the present invention can perform the rotation control of the vehicle body, and is useful for the purpose of being used in working vehicles such as rice transplanters.

10: Vehicle body 20: Engine 30: Driving device 31: Front wheel 32: Rear wheel 33: Auxiliary wheel 41: Main transmission mechanism 42: Auxiliary transmission mechanism 43: Rear gearbox 44: Steering motor (steering member drive device) 50: Driving unit 51: Seat 52: Steering handle (steering member) 53: Main transmission lever 54: Auxiliary transmission lever 55: Straight driving auxiliary lever 56: Auxiliary mode switch 60: Soil leveling device 61: Soil leveling rotor mechanism 62: Soil leveling floating mechanism 70: Fertilizer device 80: Line marker 90: Planting device lifting device 100: Planting device 101: Prepared seedling platform 200: Control device 210: Rear wheel speed sensor 220: Planting device lifting sensor 300: Positioning system 400: Threshold adjustment device A: Arrow C0, C1, C2: Rotation track Lh: Planting start line Lh0: Imaginary line Lv, Lv0: Straight line P0, P1, P2, Q1, Q2: Position Ps: Rotation start position S1, S2, S3, S4, S5: Location Z: Straight control transition area θ0: Direction

[Figure 1] is a three-dimensional diagram of a rice transplanter in an embodiment of the present invention. [Figure 2] is a block diagram of a power transmission system of a rice transplanter in an embodiment of the present invention. [Figure 3] is a block diagram of a control system of a rice transplanter in an embodiment of the present invention. [Figure 4] is an explanatory diagram (part 1) of the rotation control of a rice transplanter in an embodiment of the present invention. [Figure 5] is an enlarged explanatory diagram of the rotation control of a rice transplanter in an embodiment of the present invention. [Figure 6] is an explanatory diagram of the reverse turning control of a rice transplanter in an embodiment of the present invention. [Figure 7] is a partial three-dimensional diagram of a rice transplanter in an embodiment of the present invention. [Figure 8] is a partial top view of a rice transplanter in an embodiment of the present invention. [Figure 9] is an enlarged top view of the auxiliary wheel vicinity of the rice transplanter in the embodiment of the present invention.

10: Vehicle body A: Arrow C0, C1, C2: Turning track Lh: Planting start line Lh0: Imaginary line Lv, Lv0: Straight line P0: Position Ps: Turning start position Z: Straight control transition area

Claims (5)

A working vehicle comprises: A steering member driving device (44) for driving a steering member (52); A control device (200) for controlling the steering member driving device (44); and A detection mechanism for performing detection related to the rotation state of a vehicle body (10); The control device (200) performs rotation control when causing the vehicle body (10) to rotate between a first straight motion and a second straight motion, and the rotation control performs a first rotation and a second rotation in sequence; The control device (200) determines the rotation state of the first rotation based on the detection result, and adjusts the size of the rotation trajectory of the second rotation based on the rotation state determination of the first rotation, and sets the first rotation and the second rotation to be non-straight, and keeps the turning rotation angle in the first rotation and the second rotation substantially constant. As described in claim 1, in order to make the vehicle body (10) in the aforementioned rotation go straight again, the aforementioned control device (200) changes the turning angle return timing of the aforementioned turning angle in the aforementioned second rotation based on the aforementioned rotation state judgment, thereby controlling the aforementioned turning angle. A working vehicle as described in claim 2, wherein the turning angle return timing can be adjusted based on a manual operation to adjust a predetermined turning angle return level. A working vehicle as described in any one of claims 1 to 3, wherein a rear wheel speed sensor (210) and a positioning system (300) are provided in the detection mechanism, and when a turn starts, the rear wheel speed sensor (210) starts measuring the travel distance. When the orientation of the vehicle body (10) reaches a predetermined angle, if the travel distance is longer, the positioning system (300) determines that the turn is a large turn, and if the travel distance is shorter, the positioning system (300) determines that the turn is a small turn. A working vehicle as described in any one of claims 1 to 3, wherein a rear wheel speed sensor (210) and a positioning system (300) are provided in the detection mechanism, and when a turn starts, the rear wheel speed sensor (210) starts measuring the driving distance. When the driving distance reaches a predetermined distance, if the orientation change of the vehicle body (10) from the start of the turn is small, the positioning system (300) determines that the turn has become a large turn, and if the orientation change of the vehicle body (10) from the start of the turn is large, the positioning system (300) determines that the turn has become a small turn.