Patent Description:
Conventionally, work vehicles such as rice transplanters that automatically travel straight forward in a field using a satellite positioning system are known. Such a work vehicle performs autonomous straightforward travel along a linear travel route that is set parallel to a reference route. The reference route is generated on the basis of a set of reference points called point A and point B. In general, the point A and the point B are set as the positions between ridge-adjacent positions in the field so that automatic travel can be performed extensively in the field.

Also, as described in Patent Literatures <NUM> to <NUM>, it is known that a work vehicle executes notification by a buzzer or the like just before the automatic travel is terminated. This allows an operator to be informed in advance that the work vehicle will reach the ridge-adjacent positions. Upon receiving the notification, the operator prepares himself/herself for stop or switches to manual travel.

In a deformed field that is not a simple rectangle, such a situation may occur that the notification is made even if the work vehicle is not approaching the ridge-adjacent position, or that the notification is not made even when the work vehicle is approaching the ridge-adjacent position. Therefore, in a deformed field, the ridge-adjacent position should be updated by erasing and re-setting the point A and the point B each time so that the notification during the automatic travel is made appropriately, which had nonconformity that a complicated operation was forced. Patent Literature <NUM> discloses a work vehicle capable of preventing a reference position for a rectilinear travel from being acquired due to an improper operation and curtailing increase of the quantity of components, Patent Literature <NUM> relates to a path generation device comprising a path generation unit and a control unit. Patent Literature <NUM> describes a work vehicle capable of preventing a reference position for a rectilinear travel from being acquired due to an improper operation and curtailing increase of the quantity of components, and Patent Literature <NUM> discloses a parallel operation work vehicle for enabling operation of an autonomous work vehicle by a long distance operating device installed in an accompanying work vehicle for performing work while accompanying the autonomous work vehicle.

The present invention was made in consideration of the above problem, and its object is to provide a work vehicle capable of flexibly updating the ridge-adjacent position, and capable of appropriately executing notification during automatic travel even in a deformed field.

A work vehicle according to the present invention is a work vehicle configured to be capable of automatic travel along a travel route that is set parallel to a reference route generated on the basis of a first reference point and a second reference point set in advance, while identifying an own vehicle position thereof using a satellite positioning system, including a control unit that activates a notification device if the own vehicle position approaches a first control reference position identified on the basis of the first reference point or a second control reference position identified on the basis of the second reference point when the automatic t ravel is being performed, the control unit is configured to be capable of changing one of the first control reference position and the second control reference position to a third control reference position identified on the basis of a third reference point which is different from the first reference point and the second reference point, and after the change, the notification device is activated on the basis of the third control reference position instead of one of the first control reference position and the second control reference position.

According to such a configuration, after setting the first reference point (one of the point A and the point B) and the second reference point (the other of the point A and the point B), the first control reference position or the second control reference position identified on the basis of them can be changed to the third control reference position after that. After the change, the activation of the notification device is controlled on the basis of the third control reference position instead of the first control reference position or the second control reference position. Therefore, it is possible to update the ridge-adjacent position flexibly, and to properly execute the notification during automatic travel even in a deformed field.

The control unit is preferably configured to be capable of changing one of the first control reference position and the second control reference position to the third control reference position, both when the automatic travel is being performed and when the automatic travel is not being performed. Since the control reference position can be changed when the automatic travel is being performed, the ridge-adjacent position can be updated without interrupting the work. In addition, since the control reference position can be changed when the automatic travel is not performed, it is possible, for example, to update the ridge-adjacent position after moving to the exact ridge-adjacent position by manual travel.

The control unit is preferably configured to change one of the first control reference position and the second control reference position, which is on a rear side of a working direction, to the third control reference position, when the third reference point is set in a work area defined on the basis of the first reference point and the second reference point while the automatic travel is being performed. According to such a configuration, it is not necessary to select which control reference position is to be changed, and it is possible to update the ridge-adjacent position in accordance with an intention of the operator in the work area.

The control unit is preferably configured to identify the working direction when automatic travel is started and to change one of the first control reference position and the second control reference position, which is on the rear side of the working direction, to the third control reference position when the third reference point is set in the work area defined on the basis of the first reference point and the second reference point while automatic travel is not being performed. According to such a configuration, the control reference position is appropriately changed even when the automatic travel is not being performed. Moreover, there is no need to select which control reference position is to be changed, and the ridge-adjacent position can be updated in accordance with the user's intention.

The control unit is preferably configured to change one of the first control reference position and the second control reference position, which is closer to the own vehicle position, to the third control reference position when the third reference point is set outside the work area defined on the basis of the first reference point and the second reference point. According to such a configuration, it is not necessary to select which control reference position is to be changed, and it is possible to update the ridge-adjacent position outside the work area in accordance with the intention of the operator.

An embodiment of the present invention will be described with reference to the drawings. This embodiment shows an example of an automatic travel system that causes a passenger-type rice transplanter to perform automatic travel, an example of a work vehicle, while identifying a vehicle position using a satellite positioning system. The work vehicle is not limited to a rice transplanter, but may be, for example, a tractor, a combine harvester, a seedling transplanter, or any other agricultural work vehicle. Alternatively, it may be a civil engineering and construction vehicle or a snowplow.

First, the overall structure of the rice transplanter will be briefly explained. In <FIG>, a front-rear direction and an up-and-down direction of the rice transplanter <NUM> are indicated by arrows, and the direction perpendicular to the paper surface is a left-right direction. The rice transplanter <NUM> has a traveling unit <NUM> and a planting unit <NUM> as a working portion. The planting unit <NUM> is disposed behind the traveling unit <NUM>. The planting unit <NUM> is connected to a rear part of the traveling unit <NUM>, capable of elevation via an elevating mechanism <NUM>. The rice transplanter <NUM> is configured to perform a seedling planting (rice planting) operation in which seedlings are planted by the planting unit <NUM> while traveling in a field by the traveling unit <NUM>.

The traveling unit <NUM> has a traveling machine body <NUM>, a pair of left and right front wheels <NUM> supporting the traveling machine body <NUM>, and also a pair of left and right rear wheels <NUM>. The front wheels <NUM> are mounted on front axles extending from a front axle case <NUM> to both right and left sides. The front axle case <NUM> is provided on the side of a transmission case <NUM> and is supported at a front part of the traveling machine body <NUM>. The rear wheels <NUM> are mounted on rear axles extending from a rear axle case <NUM> to both right and left sides. The rear axle case <NUM> is provided at a rear end of a tubular frame <NUM> projecting rearwardly from the transmission case <NUM> and is supported at the rear part of the traveling machine body <NUM>.

An engine <NUM>, which is a drive source, is mounted at the front part of the traveling machine body <NUM>. The engine <NUM> is covered by a bonnet <NUM>. The power of the engine <NUM> is transmitted to a transmission case <NUM> disposed behind the engine <NUM>, and is transmitted to the front wheels <NUM> and the rear wheels <NUM> through the transmission case <NUM>. By transmitting power to the front wheels <NUM> and the rear wheels <NUM> to rotate / drive them, the traveling unit <NUM> can travel in the front-rear direction.

A link frame <NUM> is provided upright at the rear end of the traveling machine body <NUM>. The planting unit <NUM> is connected to the link frame <NUM>, capable of elevation, via the elevating mechanism <NUM>. The elevating mechanism <NUM> has a lower link 21a and a top link 21b. A rod end of a hydraulic elevating cylinder <NUM> is connected to the lower link 21a. A cylinder base end of the elevating cylinder <NUM> is supported vertically rotatably at the rear part of the upper surface of the tubular frame <NUM>. It is configured such that, by extending / retracting the elevating cylinder <NUM>, the elevating mechanism <NUM> is rotated in the vertical direction, and the planting unit <NUM> is elevated up and down.

The planting unit <NUM> includes a planting input case <NUM> to which power is transmitted from the engine <NUM> via the transmission case <NUM> and a PTO shaft (power transmission shaft) <NUM>, a plurality of planting transmission cases <NUM> connected to the planting input case <NUM>, a seedling planting mechanism <NUM> provided at the rear end side of each planting transmission case <NUM>, and a seedling loading table <NUM> on which seedling mats are placed. Reserve seedlings to be supplied to the planting unit <NUM> for seedling refill (seedling replenishment) are placed on reserve seedling stands <NUM> disposed on both left and right sides of the bonnet <NUM>. The reserve seedling stand <NUM> is supported on a support frame <NUM> (reserve seedling support) provided upright on both the left and right sides of the front part of the traveling machine body <NUM>.

The seedling planting mechanism <NUM> includes a rotary case <NUM> having two planting claws <NUM>, <NUM> for one row. In accordance with a rotating movement of the rotary case <NUM>, the two planting claws <NUM>, <NUM> take out seedlings from the seedling mat alternately and plant them in the field. Since the rice transplanter <NUM> of this embodiment is an eight-row planting rice transplanter, it includes four sets of planting transmission cases <NUM> for eight-row planting (two rows forming one set), and the seedling loading table <NUM> is also configured for eight-row planting However, the rice transplanter <NUM> is not limited thereto, and may be, for example, a six-row or ten-row rice transplanter.

Side markers <NUM> are provided on the left and right outer sides of the planting unit <NUM>, respectively. The side marker <NUM> has a marker wheel body 29w for drawing lines and a marker arm 29a that rotatably supports the marker wheel body 29w. A base end of the marker arm 29a is supported at the left and right outer sides of the planting unit <NUM> rotatably in the left and right directions. The side marker <NUM> is configured to be displaceable between a landing posture, in which the marker wheel body 29w is lowered to form a reference trajectory on the rice field for the next process, and a non-landing posture (see <FIG>), in which the marker wheel body 29w is raised to move away from the rice field.

At the center of the traveling machine body <NUM> in the front-rear direction, a driving operation unit <NUM> is provided. The operator boards a work step <NUM> (body cover) provided on the upper surface side of the traveling machine body <NUM> and operates the rice transplanter <NUM> at the driving operation unit <NUM>. An operation panel <NUM> is provided at the front part of the driving operation unit <NUM>. The operation panel <NUM> is disposed on the rear upper surface side of the bonnet <NUM>. Aplurality of operating tools, including a steering wheel <NUM> and a main gearshift lever <NUM>, are disposed on the operation panel <NUM>. A driver's seat <NUM> is disposed behind the operation panel <NUM> via a seat frame <NUM>.

On both the left and right sides of the bonnet <NUM>, a plurality of (four in this embodiment) reserve seedling stands <NUM> are supported by a pair of support frames <NUM>, <NUM> spaced apart in the front-rear direction. A connecting frame <NUM> having a substantial L-shape on a side view is connected to upper ends of the pair of support frames <NUM>, <NUM>. A unit frame <NUM> is connected to an upper end of the connecting frame <NUM> via an intermediate frame <NUM> extending in the up-and-down direction. The unit frame <NUM> is connected rotatably to the upper parts of the left and right intermediate frames <NUM>. A positioning unit <NUM> as a positioning unit is fixed to the unit frame <NUM>.

The positioning unit <NUM> receives positioning signals from a satellite positioning system (GNSS) and identifies the vehicle's position on the basis of the positioning signals. For example, DGPS (Differential GPS) is used as the satellite positioning system. According to this, position information of the rice transplanter <NUM> (mobile station) is corrected by correction information from a base station installed at a predetermined point, and the own vehicle position of the rice transplanter <NUM> can be identified with high accuracy. Not limited to DGPS, satellite positioning systems such as RTK (Real Time Kinematic) and SBAS (Geostationary Satellite Augmentation System) can also be used.

Next, the driving operation unit <NUM> will be described. As shown in <FIG>, various operating tools including the steering wheel <NUM> and a display device <NUM> are disposed on the operation panel <NUM>. The steering wheel <NUM> is provided in front of the driver's seat <NUM>. A gearshift pedal and a brake pedal, not shown, are installed below the operation panel <NUM>. The gearshift pedal is an operating tool for changing a vehicle speed of the rice transplanter <NUM>. The brake pedal is an operating tool for braking the rice transplanter <NUM>. Generally, the gearshift pedal is disposed at lower right of the operation panel <NUM>, and the brake pedal is disposed on the left of the gearshift pedal.

The rice transplanter <NUM> includes an operation member <NUM> for performing operations related to automatic travel and an arm member <NUM> supporting the operation member <NUM>. The arm member <NUM> has a stay-like upper arm 35a fixed to the support frames <NUM>, <NUM>, a forearm 35c which rotates horizontally with respect to the upper arm 35a with a hinge 35b as a fulcrum, and a holder 35e which rotates horizontally with respect to the forearm 35c with a hinge 35d as a fulcrum. The operation member <NUM> is attached to the holder 35e. At both ends of the forearm 35c, elbow portions 35f, 35f which are bent along the up-and-down direction are formed, respectively. The elbow portion 35f may be configured to be rotatable in the up-and-down direction via a hinge. The operation member <NUM> held in the holder 35e can be moved in a movable range of the arm member <NUM>.

As shown in <FIG>, the operation member <NUM> includes an AUTO button <NUM>, which is an indicator for instructing start of automatic travel, an A button <NUM>, which is an indicator for instructing setting of the point A, which is a start point of a reference route, and a B button <NUM>, which is an indicator for instructing the setting of the point B, which is an end point of the reference route. The AUTO button <NUM> is disposed at the center of an operation surface 50f of the operation member <NUM>. The A button <NUM> and the B button <NUM> are disposed side by side on the left and right below the AUTO button <NUM>. An indicator lamp <NUM> indicating a positioning state of the positioning unit <NUM> is disposed at upper left of the AUTO button <NUM>.

The AUTO button <NUM> is operated when starting and stopping automatic travel. Since the AUTO button <NUM> is operated more frequently than the A button <NUM> and the B button <NUM>, it is formed larger on a front view than the A button <NUM> and the B button <NUM> so that it can be easily pressed and operated. In addition, the AUTO button <NUM> protrudes larger than the A button <NUM> and the B button <NUM>. The A button <NUM> and the B button <NUM> are the buttons having the same shape and are disposed symmetrically. A ring-shaped light-emitting portion <NUM> is provided around the AUTO button <NUM>. The light emitting portion <NUM> has a function of informing the operator of various states related to automatic travel by its light color and lighting pattern.

In the present embodiment, the operation member <NUM> for performing operations related to automatic travel is provided independently of the operation panel <NUM>. According to such a configuration, there is no need to modify the operation panel <NUM> when an automatic travel system is additionally installed in an existing rice transplanter, which is convenient. However, it is not limited thereto, and it is also possible to incorporate and provide an operation member for performing operations related to automatic travel in the operation panel <NUM>.

The rice transplanter <NUM> is configured to be capable of performing automatic travel along a travel route that is set parallel to a reference route generated on the basis of a preset first reference point (one of the point A and the point B) and a second reference point (the other of points A and B) while identifying an own vehicle position thereof using a satellite positioning system. For straight-travel assistance work by automatic travel, operations of setting a start point of a reference route, called point A, setting an end point of the reference route, called point B, and turning on (start) / off (stop) the automatic travel via the operation member <NUM> are needed.

<FIG> is a block diagram illustrating the major configurations related to the automatic travel. The positioning unit <NUM> includes a positioning antenna 43a, a position measuring machine 43b, and an inertial measurement unit (IMU) 43c. The positioning antenna 43a receives signals from positioning satellites (GPS satellites, for example) that constitute a satellite positioning system. The positioning signal received by the positioning antenna 43a is input to the position measuring machine 43b. The position measuring machine 43b measures the position of the own vehicle by signal processing of the input positioning signal. The inertial measuring machine 43c identifies the posture (roll angle, pitch angle, and yaw angle) of the traveling machine body <NUM>.

The rice transplanter <NUM> includes a control unit <NUM> for controlling the operation of the traveling machine body <NUM> (forward movement, backward movement, stopping and turning and the like) and the operation of the planting unit <NUM>, which is a work unit (elevating up and down, driving and stopping and the like. The control unit <NUM> is constituted by including a CPU, ROM, RAM, I/O, and the like, not shown. The CPU can read various programs and the like from the ROM and execute them. Operation programs, application programs, and various data are stored in the ROM. By collaborating such hardware and software, the control unit <NUM> can be operated as a storage unit <NUM>, a processing unit <NUM>, an automatic travel control unit <NUM>, and the like.

The storage unit <NUM> stores various kinds of information required for automatic travel of the rice transplanter <NUM>. Such information includes, for example, a horizontal distance from the positioning antenna 43a to the seedling planting mechanism <NUM>, the positions of the first and second reference points set by the operator, and the position of the third reference point described below. The processing unit <NUM> executes various processes required for automatic travel of the rice transplanter <NUM>. Such processes include generation of the reference route and change of the control reference route described below (update of a ridge-adjacent position). The automatic travel control unit <NUM> executes control related to automatic travel.

The automatic travel control unit <NUM> controls an actuator <NUM> for automatic travel so that the rice transplanter <NUM> travels along a travel route on the basis of the information of the own vehicle position measured by the positioning unit <NUM>. The actuator <NUM> for automatic travel refers to various actuators to be activated during automatic travel, including an actuator for steering the steering handle <NUM>, an actuator for shifting the transmission of the transmission case <NUM>, an actuator for elevating the planting unit <NUM> up and down (the elevating cylinder <NUM>), and the like. The automatic travel control unit <NUM> controls the operation of the rice transplanter <NUM> on the basis of the signals from a sensor <NUM> for automatic travel provided in the rice transplanter <NUM>.

The rice transplanter <NUM> includes a buzzer <NUM> as a notification device. The buzzer <NUM> emits a warning sound (buzzer sound) in response to the control by the control unit <NUM>. The buzzer <NUM> may be included in the operation member <NUM>. It is also possible to configure a notification device using a lamp that gives notification using light, or a combination of a buzzer and a lamp, for example, not limited to a buzzer that gives notification using sound.

Afield <NUM> shown in <FIG> is divided by a pair of ridges <NUM>, <NUM> extending in parallel with each other. First, the operator causes the rice transplanter <NUM> to travel from a ridge adjacent 71a close to one ridge <NUM> toward a ridge adjacent 72a close to the other ridge <NUM> in order to generate a reference route SC. At that time, the A button <NUM> is operated at the start point A to set the point A. Also, the B button <NUM> is operated at the end point B to set the point B. In this embodiment, it is described that the point A corresponds to the first reference point and the point B corresponds to the second reference point, but these may be vice versa.

The control unit <NUM> generates the reference route SC on the basis of the point A and the point B set in advance, and defines a work area <NUM> on the basis of the points A and B thereof. The reference route SC can be identified as a line segment connecting the point A and the point B. The work area <NUM> can be identified as the area sandwiched between a ridge-adjacent position L1, which is acquired as a line segment perpendicular to the reference route SC with respect to the point A, and a ridge-adjacent position L2, which is acquired as a line segment perpendicular to the reference route SC with respect to the point B. The lengths of the line segments that constitute the ridge-adjacent positions L1 and L2 are set at predetermined distances (<NUM> on each side, for example) with the points A and B at the centers, respectively.

After generating the reference route SC, when the AUTO button <NUM> is pressed, a travel route C1 passing through the own vehicle position and in parallel to the reference route SC is set, and the working direction WD (traveling direction during automatic travel) is identified on the basis of the direction (azimuth) of the vehicle body, and the automatic travel is started. The working direction WD is parallel to the reference route SC and can be either downward or upward in <FIG>. The working direction WD is switched at each turn, but is not limited to this. The system is configured such that, when the direction of the vehicle body (front-rear direction) is inclined with respect to the reference route SC, the automatic travel is not started unless the inclination angle is not more than a predetermined value (not more than <NUM> degrees, for example).

Thereafter, the travel routes C2, C3. are set in the same manner, and autonomous straight travel is performed along them. Once set, the points A and B are continuously used until they are erased or reset, so that the plurality of travel routes C1, C2. are parallel to each other. In an arc-shaped turning routes R1, R2,. which connect the ends of the travel routes C1, C2,. to each other, a U-turn travel (<NUM>-degree turn of direction) is performed by the operator's operation. However, it is not limited thereto and may be configured such that the autonomous U-turn travel can be performed.

The ridge-adjacent position L1 corresponds to the first control reference position identified on the basis of the first reference point, which is the point A, and the ridge-adjacent position L2 corresponds to the second control reference position identified on the basis of the second reference point, which is the point B. The control unit <NUM> activates the buzzer <NUM> when the position of the own vehicle approaches the ridge-adjacent position L1 or the ridge-adjacent position L2 when the automatic travel is being performed. The control unit <NUM> causes the buzzer <NUM> to sound and give notification when the rice transplanter <NUM> approaches a predetermined distance (<NUM>, for example) with respect to the ridge-adjacent position L1 or the ridge-adjacent position L2, for example. If the gearshift pedal is pressed even when the ridge-adjacent positions L1, L2 are reached, the automatic travel is continued. While the function of traveling at a constant speed without stepping on the gearshift pedal is active, it is desirable to control to stop the rice transplanter <NUM> or to stop the engine <NUM> when the rice transplanter <NUM> reaches the ridge-adjacent positions L1, L2.

<FIG> shows an example in which the field <NUM> is a deformed field. In <FIG>, the ridge <NUM> is bent so as to narrow the field <NUM>, and accordingly the ridge adjacent 71a has a step. Since the ridge-adjacent position L1 is identified on the basis of the point A set in advance, and the activation of the buzzer <NUM> is controlled on the basis of the ridge-adjacent position L1 and the ridge-adjacent position L2, the buzzer <NUM> is not activated even if the rice transplanter <NUM> reaches the ridge adjacent 71a in the case of the automatic travel along the travel route C5. In addition, there are deformed fields where the ridge adjacent has steps or the ridge adjacent is curved in a direction opposite to that in <FIG>, and depending on the shape thereof, the buzzer may be activated even when the rice transplanter is not approaching the ridge adjacent.

In the past, in order to ensure that the notification is properly executed, the points A and B must be erased once after traveling on the travel route C4, and the points A and B must be reset while traveling manually on the travel route C5 so as to update the ridge-adjacent position. However, such a complicated operation is inconvenient for the operator. In addition, whether or not the parallelism of the travel route is properly maintained before and after the update of the ridge-adjacent positions tends to depend on the skill of the operator. If the operator is an unskilled person, there is a risk that the travel routes C5 to C7 may be set with inclination to the travel routes C1 to C4.

Therefore, with this rice transplanter <NUM>, the control unit <NUM> is configured to be capable of changing one of the ridge-adjacent position L1 and the ridge-adjacent position L2 to the third control reference position identified on the basis of the third reference point (point P) different from the first reference point (point A) and the second reference point (point B), and after the change, the buzzer <NUM> is activated on the basis of the third control reference position instead of one of the ridge-adjacent position L1 and the ridge-adjacent position L2. In addition, the control unit <NUM> is configured to be capable of changing one of the ridge-adjacent position L1 and the ridge-adjacent position L2 to the third control reference position either when the automatic travel is being performed or when the automatic travel is not being performed.

In <FIG>, the ridge-adjacent position L1 is updated to a ridge-adjacent position L3. The updated ridge-adjacent position L3 is acquired as a line segment perpendicular to the reference route SC with a set point P as the reference. The point P corresponds to the third reference point. The ridge-adjacent position L3 corresponds to the third control reference position identified on the basis of the third reference point. The point P is set in response to a predetermined operation by the operator, and the control reference position is changed accordingly, that is, the ridge-adjacent position is updated Before the change, the activation of the buzzer <NUM> is controlled on the basis of the ridge-adjacent position L1 and the ridge-adjacent position L2, and after the change, the activation of the buzzer <NUM> is controlled on the basis of the ridge-adjacent position L3 and the ridge-adjacent position L2. For this reason, the buzzer <NUM> is appropriately activated when the position of the own vehicle approaches the ridge adjacent 71a in the automatic travel on and after the travel route C5. After the update, the work area <NUM> is defined on the basis of the point P and the point B.

The control unit <NUM> is configured to change one of the first control reference position and the second control reference position, which is on the rear side of the working direction WD, to the third control reference position when the third reference point is set in the work area <NUM> when the automatic travel is being performed. In other words, the control unit <NUM> is configured such that, while the automatic travel is being performed along the working direction WD with either of the first control reference position and the second control reference position as the starting point, when the third reference point is set in the work area <NUM>, the control unit <NUM> changes either of the first control reference position and the second control reference position, which is the starting point, to the third control reference position. Since the control reference position can be changed during the automatic travel, the ridge-adjacent position can be updated without interrupting the work.

Accordingly, as shown in <FIG>, when the point P, which is the third reference point, is set in the work area <NUM> during the automatic travel along the travel route C4, the ridge-adjacent position L1 on the rear side of the working direction WD in the pair of ridge-adjacent positions L1 and L2 is changed to the ridge-adjacent position L3. In other words, the ridge-adjacent position L1 that was the starting point of the travel route C4 in the pair of ridge-adjacent positions L1 and L2 is changed to the ridge-adjacent position L3. This eliminates the need for the operator to select which control reference position to change, that is, the ridge-adjacent position L1 or the ridge-adjacent position L2. Such update patterns are easy to understand sensually, and the update of the ridge-adjacent position in accordance with the intention of the operator is possible.

There are two possible situations when the third reference point is to be set, or in other words, when the ridge-adjacent position is to be updated, that is, when the rice transplanter <NUM> is inside the work area <NUM> (case <NUM>), and when the rice transplanter <NUM> is outside the work area <NUM>. Furthermore, the latter may include a case in which the work area <NUM> is on the front side of the rice transplanter <NUM> (case <NUM>) and a case in which the work area <NUM> is on the rear side of the rice transplanter <NUM> (case <NUM>). <FIG> schematically show the update patterns of the ridge-adjacent positions in the cases <NUM> to <NUM>, respectively. Since the case <NUM> has already been described, the explanation of <FIG> is omitted.

The control unit <NUM> is configured to change one of the first control reference position and the second control reference position, which is closer to the own vehicle position, to the third control reference position when the third reference point is set outside the work area <NUM>. Accordingly, when the point P is set outside the work area <NUM> as shown in <FIG>, the ridge-adjacent position L1 closer to the own vehicle position in the pair of ridge-adjacent positions L1 and L2 is changed to the ridge-adjacent position L3, and thereafter the activation of the buzzer <NUM> is controlled on the basis of the ridge-adjacent position L3 and the ridge-adjacent position L2. Similarly, when the point P is set outside the work area <NUM> as shown in <FIG>, the ridge-adjacent position L2 closer to the own vehicle position in the pair of ridge-adjacent positions L1 and L2 is changed to the ridge-adjacent position L3, and thereafter the activation of the buzzer <NUM> is controlled on the basis of the ridge-adjacent position L3 and the ridge-adjacent position L1.

In other words, it is configured such that, when the point P is set closer to the rear side of the working direction WD than the work area <NUM> as shown in <FIG>, the control unit <NUM> changes one of the pair of ridge-adjacent positions L1 and L2, which is on the rear side of the working direction WD (ridge-adjacent position L1), to the ridge-adjacent position L3, and when the point P is set closer to the front side of the working direction WD than the work area <NUM> as shown in <FIG>, one of the pair of the ridge-adjacent positions L1 and L2, which is on the front side of the working direction WD (ridge-adjacent position L2), is changed to the ridge-adjacent position L3. These may be done either when the automatic travel is being performed or when it is not. When automatic travel is not being performed, the working direction when the automatic travel is started only needs to be the reference in the same way as when the third reference point is set in the work area <NUM> described below.

<FIG> is different from <FIG> in that the point P is set when automatic travel is not performed. It is configured such that, when the point P is set in the work area <NUM> when the automatic travel is not being performed, the control unit <NUM> identifies the working direction WD in the case where the automatic travel is started, and changes one of the ridge-adjacent position L1 and the ridge-adjacent position L2, which is on the rear side of the working direction WD (the ridge-adjacent position L1), to the ridge-adjacent position L3. The working direction WD when the automatic travel is started is the working direction when the automatic travel is assumed to have been started. Although the working direction is not determined when the automatic travel is not being performed, such as during stop and during manual travel, the ridge-adjacent position can be updated without hindrance by using the working direction WD when the automatic travel is started as a reference.

As previously described, the updated ridge-adjacent position L3 is defined as a line segment perpendicular to the reference route SC with respect to the point P set after that. Not limited to this, the ridge-adjacent position L3 can be also identified as a line segment parallel to at least one of the ridge-adjacent position L1 and the ridge-adjacent position L2 when using the point P as a reference, for example. If the rice transplanter <NUM> has a function that can adjust the angle of the ridge-adjacent position L1 or the ridge-adjacent position L2, there may be a situation in which the pair of ridge-adjacent positions L1 and L2 are not parallel to each other but in such a case, the ridge-adjacent position L3 can be identified as a line segment parallel to the ridge-adjacent position to be updated.

The operator can set a third reference point, that is, the point P, by a predetermined operation both when the automatic travel is being performed and when the automatic travel is not being performed. From the viewpoint of simplification of the operation, it is preferable that the setting of the third reference point can be indicated using an indicator for indicating the setting of the first reference point and/or the second reference point. In this embodiment, the A button <NUM> can be used to indicate the setting of the point P. When the A button <NUM> is pressed in a situation where the points A and B are set, the position of the own vehicle at that time is set as the point P. <FIG> is a table showing the relationship between the operation modes of the A button <NUM> as well las the B button <NUM> and the operation. Various variations of these operations are possible, as shown in the remarks column of the table.

As shown in <FIG>, in this embodiment, the ridge-adjacent position is updated by the point-A operation (pressing operation of the A button <NUM>). Since the processing is executed in accordance with the update pattern shown in <FIG>, it is not necessary to select which of the ridge-adjacent positions L1 and L2 is to be updated. Instead of the point-A operation, the point-B operation (press operation of the B button <NUM>) may be used. Alternatively, both the A button <NUM> and the B button <NUM> can be used. For example, the ridge-adjacent position on the rear side of the working direction (upstream side of the traveling direction) may be updated by the point-A operation in the work area <NUM>, and the ridge-adjacent position on the front side of the working direction (downstream side of the traveling direction) may be updated by the point-B operation as well (see the remarks column in <FIG>). According to such a configuration, the system can be updated at both the ridge-adjacent positions L1 and L2 regardless of the direction of the vehicle body.

<FIG> are flowcharts showing processes executed by the control unit <NUM> regarding automatic travel of the rice transplanter <NUM>. As shown in <FIG>, when the rice transplanter <NUM> is turned on, it is "START", and first, the conditions for performing straight-travel assistance work by automatic travel are set (work condition setting process S1). Next, the automatic travel is executed on the basis of the set conditions (automatic travel execution process S2). Thereafter, if a predetermined end condition is satisfied, the automatic travel is terminated, otherwise the automatic travel is continued (automatic travel end /continuation process S3), and these processes S1 to S3 are repeated.

As shown in <FIG>, in the work condition setting process S1, when the point-A operation is performed, if the point A has not yet been set, the point A is set in response to the operation (steps S11, S12 and S14). If the both point A and point B are set when the point-A operation is performed, the ridge-adjacent positions are updated in accordance with the operation (steps S11 to S13 and S15). This means that the third reference point (point P) is set in response to the point-A operation, thereby changing the control reference position. If the point-B operation is performed and the point B has not yet been set, the point B is set in response to the operation (steps S16-<NUM>).

Although not shown in <FIG>, the set points A and B can be erased by long-pressing the A button <NUM> and the B button <NUM>. Specifically, as shown in <FIG>, if the A button <NUM> is long-pressed in a situation where only the point A is set, the set point A is erased. In addition, if the A button <NUM> is long-pressed in a situation where both the points A and B have been set, both the set points A and B are erased. If the B button <NUM> is long-pressed in a situation where both the points A and B have been set, the set point B is erased. As another operation mode, it may be configured such that the points A and B are erased by simultaneously pressing the A button <NUM> and the B button <NUM>.

As shown in <FIG>, in the automatic travel execution process S2, when automatic travel is not being performed and the points A and B have already been set, the reference route SC is generated on the basis of the set points A and B, and the ridge-adjacent positions L1 and L2 are identified (steps S21 to S24). If the positioning state of the positioning unit <NUM> is good, automatic travel is permitted by the control unit <NUM> (step S25). When start of automatic travel is instructed by the ON operation of the AUTO button <NUM>, a travel route is set and automatic travel is started along the travel route (steps S26 to S28). On the other hand, if the automatic travel is in progress at step S21, the buzzer <NUM> is activated to execute notification based on the ridge-adjacent position that has been identified (step S29).

As shown in <FIG>, in the automatic travel end / continuation process S3, it is determined whether or not a predetermined end condition is satisfied during the automatic travel (steps S31 and S32). The end condition of the automatic travel is satisfied, for example, when the end of the automatic travel is instructed by the OFF operation of the AUTO button <NUM>, or when it is determined that the positioning state of the positioning unit <NUM> is not satisfactory to such an extent that the automatic travel cannot be continued. If the end condition is satisfied, the automatic travel is terminated; otherwise, the automatic travel is continued (steps S32 to S34).

Claim 1:
A work vehicle (<NUM>) capable of automatic travel along a travel route that is set parallel to a reference route generated on the basis of a first reference point and a second reference point set in advance, while identifying an own vehicle position thereof using a satellite positioning system, comprising:
a control unit (<NUM>) that is configured to activate a notification device, if the own vehicle position approaches a first control reference position identified on the basis of the first reference point (A) or a second control reference position identified on the basis of the second reference point (B) when the automatic travel is being performed, characterized in that
the control unit (<NUM>) is configured to change one of the first control reference position and the second control reference position to a third control reference position identified on the basis of a third reference point which is different from the first reference point (A) and the second reference point (B), and
after the change, the notification device is activated on the basis of the third control reference position instead of one of the first control reference position and the second control reference position.