Work vehicle and display control method

A work vehicle includes: a display device provided in a cab and configured to display work assistance information to be overlaid on an actual view of a work site; a bucket position detector configured to detect a position of a bucket; and a display controller configured to control a content to be displayed on the display device and configured to cause the work assistance information to be displayed around the bucket while causing the work assistance information to follow the movement of the bucket based on the detected position. When work assistance information becomes close to a boundary of a display area of the display device due to the movement of the bucket, the display controller is configured to cause the work assistance information to be displayed on the display device with a relative position between the work assistance information and the bucket in the display area being changed.

TECHNICAL FIELD

The present invention relates to a work vehicle and a display control method, particularly, a work vehicle having a bucket and a display control method in the work vehicle.

BACKGROUND ART

Conventionally, a work vehicle such as a hydraulic excavator has been known. Such a work vehicle has a main body and a work implement connected to the main body. For example, a work implement of a hydraulic excavator has a boom, a dipper stick, and a bucket in the stated order as seen on the side of the main body.

Japanese Patent Laying-Open No. 2009-243073 (Patent Document 1) discloses a hydraulic excavator as an example of a work vehicle. The hydraulic excavator includes a cab, a work implement, a display device, and a display position processor. The work implement is operated as manipulated by an operator in the cab. The display device is provided in the cab and displays a predetermined image. The display position processor changes the display position of the image in the display device in response to a movement of the work implement.

Particularly, the display device is a transparent display provided at the front surface of the cab. Among display positions, the display position processor causes a predetermined image to be displayed at a position that crosses a straight line that connects the distal end of the work implement to a viewpoint of the operator in the cab.

CITATION LIST

Patent Document

SUMMARY OF INVENTION

Technical Problem

A display area of the display device provided at the front surface of the cab is limited to the range of the front surface. Hence, it is considered that in the work vehicle provided with the display device at the front surface of the cab thereof, a display position of a predetermined image such as work assistance information may be unable to be caused to follow the distal end of the work implement. Therefore, in order to improve operability of the work vehicle, it is expected to develop a work vehicle that can handle such a situation.

The present invention has been made in view of the above-described problem, and has an object to provide a work vehicle that can improve operability of the work vehicle by appropriately controlling displaying of work assistance information, as well as a display control method in the work vehicle.

Solution to Problem

According to an aspect of the present invention, a work vehicle includes: a work implement having a bucket; a main body to which the work implement is attached, the main body having a cab; a display device provided in the cab and configured to display work assistance information to be overlaid on an actual view of a work site; a bucket position detector configured to detect a position of the bucket; and a display controller configured to control a content to be displayed on the display device, and configured to cause the work assistance information to be displayed around the bucket while causing the work assistance information to follow a movement of the bucket based on the detected position. When the work assistance information becomes close to a boundary of a display area of the display device due to the movement of the bucket, the display controller is configured to cause the work assistance information to be displayed on the display device with a relative position between the work assistance information and the bucket in the display area being changed.

According to the above-described configuration, when the work assistance information becomes close to the boundary of the display area of the display device, the work assistance information is displayed with the relative position between the work assistance information and the bucket being changed, whereby the work assistance information can continue to be securely displayed. Hence, the operability of the work vehicle can be improved. Further, the operability of the work vehicle can be improved as compared with a configuration in which the work assistance information is not displayed around bucket7.

Preferably, the display controller is configured to: cause a plurality of pieces of the work assistance information to be displayed on the display device in a predetermined arrangement; and change the arrangement of the plurality of pieces of the work assistance information when at least one of the plurality of pieces of the work assistance information becomes close to the boundary due to the movement of the bucket.

According to the above-described configuration, even when there is work assistance information that cannot follow the movement of the bucket, the work assistance information can continue to be displayed.

Preferably, the display controller is configured to control a display position of the work assistance information on the display device such that the work assistance information is visually recognized at a left position or a right position relative to the bucket when viewed from the cab.

According to the above-described configuration, the work assistance information is not displayed at least below the teeth. Therefore, displaying can be performed with excellent workability for the operator.

Preferably, the bucket is movable in a frontward direction and a rearward direction relative to the cab. When the work assistance information becomes close to the boundary due to the movement of the bucket in the rearward direction, the display controller is configured to cause the work assistance information displayed at one of the right position and the left position to be displayed at the other of the right position and the left position.

According to the above-described configuration, even when the bucket becomes close to the cab, the display position of the work assistance information can be caused to follow the bucket.

Preferably, the work implement is provided at a right side relative to the cab. The one of the right position and the left position is the right position. The other of the right position and the left position is the left position.

According to the above-described configuration, the work assistance information can be displayed in a manner suitable in view of the attachment position of the work implement to the main body.

Preferably, the bucket is movable in an upward direction and a downward direction relative to the cab. When the work assistance information becomes close to the boundary due to the movement of the bucket in the upward direction, the display controller is configured to change the relative position between the work assistance information and the bucket at an upper end area of the display area.

According to the above-described configuration, the work assistance information is displayed at the same or close position as or to the position at which the work assistance information has been displayed just before the work assistance information cannot follow the movement of the bucket. Hence, as compared with a case of displaying the work assistance information at a different position, displaying can be performed with excellent convenience for the operator.

Preferably, the bucket is movable in an upward direction and a downward direction relative to the cab. When the work assistance information becomes close to the boundary due to the movement of the bucket in the downward direction, the display controller is configured to change the relative position between the work assistance information and the bucket at a lower end area of the display area.

According to the above-described configuration, the work assistance information is displayed at the same or close position as or to the position at which the work assistance information has been displayed just before the work assistance information cannot follow the movement of the bucket. Hence, as compared with a case of displaying the work assistance information at a different position, displaying can be performed with excellent convenience for the operator.

According to another aspect of the present invention, a work vehicle includes: a work implement having a bucket; a main body to which the work implement is attached, the main body having a cab; a display device provided in the cab and configured to display work assistance information to be overlaid on an actual view of a work site; a bucket position detector configured to detect a position of the bucket; and a display controller configured to control a content to be displayed on the display device, and configured to cause the work assistance information to be displayed around the bucket while causing the work assistance information to follow a movement of the bucket based on the detected position. When the work assistance information becomes close to a boundary of a display area of the display device due to the movement of the bucket, the display controller is configured to stop displaying the work assistance information.

According to the above-described configuration, by stopping displaying the work assistance information when the work assistance information becomes close to the boundary of the display area of the display device, the operator can visually recognize a front view clearly. Hence, the operability of the work vehicle can be improved. Further, the operability of the work vehicle can be improved as compared with a configuration in which the work assistance information is not displayed around the bucket.

Preferably, the display controller is configured to cause a plurality of pieces of the work assistance information to be displayed on the display device. When the plurality of pieces of the work assistance information becomes close to the boundary due to the movement of the bucket, the display controller is configured to stop displaying at least one of the plurality of pieces of the work assistance information.

According to the above-described configuration, work assistance information, other than the at least one piece of work assistance information, from the plurality of pieces of the assistance information can be caused to follow the movement of the bucket.

Preferably, based on the detected position, the display controller is configured to determine whether or not the work assistance information becomes close to the boundary.

According to the above-described configuration, it can be determined whether or not the work assistance information becomes close to the boundary.

Preferably, based on a display position of the work assistance information, the display controller is configured to determine whether or not the work assistance information becomes close to the boundary.

According to the above-described configuration, it can be determined whether or not the work assistance information becomes close to the boundary.

Preferably, based on a position of an intersection between the display area and an imaginary line that connects the detected position to a reference position representing a viewpoint of an operator, the display controller is configured to determine whether or not the work assistance information becomes close to the boundary.

According to the above-described configuration, it can be determined whether or not the work assistance information becomes close to the boundary.

According to still another aspect of the present invention, a display control method is performed in a work vehicle including: a work implement having a bucket; a main body to which the work implement is attached, the main body having a cab; and a display device provided in the cab and configured to display work assistance information to be overlaid on an actual view of a work site. The display control method includes: detecting a position of the bucket; and displaying the work assistance information around the bucket while causing the work assistance information to follow a movement of the bucket based on the detected position, and changing a relative position between the work assistance information and the bucket in a display area of the display device when the work assistance information becomes close to a boundary of the display area.

According to the above-described configuration, when the work assistance information becomes close to the boundary of the display area of the display device, the work assistance information is displayed with the relative position between the work assistance information and the bucket being changed, whereby the work assistance information can continue to be securely displayed. Therefore, according to the above-described display control method, the operability of the work vehicle can be improved. Further, the operability of the work vehicle can be improved as compared with a configuration in which the work assistance information is not displayed around the bucket.

According to yet another aspect of the present invention, a display control method is performed in a work vehicle including: a work implement having a bucket; a main body to which the work implement is attached, the main body having a cab; and a display device provided in the cab and configured to display work assistance information to be overlaid on an actual view of a work site. The display control method includes: detecting a position of the bucket; and displaying the work assistance information around the bucket while causing the work assistance information to follow a movement of the bucket based on the detected position, and stopping displaying the work assistance information when the work assistance information becomes close to a boundary of a display area of the display device.

According to the above-described configuration, by stopping displaying the work assistance information when the work assistance information becomes close to the boundary of the display area of the display device, the operator can visually recognize a front view clearly. Therefore, according to the above-described display control method, the operability of the work vehicle can be improved. Further, the operability of the work vehicle can be improved as compared with a configuration in which the work assistance information is not displayed around the bucket.

Advantageous Effects of Invention

According to the above-described configuration, since the displaying of the work assistance information can be appropriately controlled, the operability of the work vehicle can be improved.

DESCRIPTION OF EMBODIMENTS

The present invention will now be described in an embodiment hereinafter with reference to the drawings. In the following description, identical components are identically denoted. Their names and functions are also identical. Accordingly, they will not be described repeatedly.

A. General Configuration

FIG. 1is a diagram for illustrating an appearance of a work vehicle101according to an embodiment. In the present example, a hydraulic excavator will be described as an example of work vehicle101according to the embodiment as shown inFIG. 1.

Work vehicle101mainly includes a travel unit1, a revolving unit3, and a work implement4. Work vehicle101has a main body composed of travel unit1and revolving unit3. The main body has work implement4attached thereto. Travel unit1has a pair of right and left crawler belts. Revolving unit3is revolvably mounted via an upper revolving mechanism of travel unit1. Revolving unit3has a cab8and the like.

Work implement4is pivotally supported at revolving unit3so as to be movable upward and downward and performs a work such as excavation of soil. Work implement4includes a boom5, a dipper stick6, and a bucket7. Work implement4is provided at a right side relative to cab8.

Boom5has a base movably coupled to revolving unit3. Dipper stick6is movably coupled to the distal end of boom5. Bucket7is movably coupled to the distal end of dipper stick6. Bucket7is movable upward and downward relative to cab8. Further, bucket7is also movable frontward and rearward relative to cab8. Bucket7has teeth7A.

Cab8has a front windshield2. Front windshield2is fixed by a frame9. Particularly, front windshield2is constituted of a front windshield2A and a front windshield2B located below front windshield2A. More particularly, front windshield2A is provided inside an upper opening frame9A (inside the opening frame), and front windshield2B is provided inside a lower opening frame9B.

Display device44is attached in front of an operator's seat in cab8of work vehicle101. In the present embodiment, display device44is composed of a member (a film or the like) which transmits external light incident on cab8, and a projection device (projector). The projection device projects an image which is in turn displayed as a real image on the member (such as a film) that transmits external light. Display device44has a display area provided inside opening frame9A provided on a front surface of cab8of work vehicle101. The operator in cab8can visually observe an actual view of a work site including work implement4through the display area of display device44. Display device44overlays on the actual view of the work site and thus display information for assisting the operator to manipulate work implement4(hereinafter also referred to as a work) (hereinafter also referred to as work assistance information). Display device44functions as a head-up display that directly displays an image in the field of view of the operator.

The member that transmits external light, such as a film, of display device44is placed on front windshield2A. Display device44has a display extending to reach an edge of front windshield2A. Front windshield2A may be the same as or different from the display area of display device44in size.

While in the present embodiment, as display device44, a configuration will be described in which an image projected by a projection device (projector) is displayed on a member (such as a film) that transmits external light incident on cab8, this is not exclusive, and it is also possible to have a configuration including display device44which is a transparent display (for example, a transmission type liquid crystal display).

B. Configuration of Control System

FIG. 2is a block diagram showing a configuration of a control system included in work vehicle101. As shown inFIG. 2, work vehicle101includes a manipulation device10, a work implement controller20, a work implement drive device30, and a display system40.

Manipulation device10includes manipulation members11L and11R, a manipulation detector12, a travel manipulation member13, and a travel manipulation detector14.

Manipulation members11L and11R are used by the operator to manipulate work implement4and revolving unit3. Specifically, manipulation member11R is used by the operator to manipulate boom5and bucket7. Manipulation member11L is used by the operator to manipulate revolving unit3and dipper stick6.

Manipulation detector12detects manipulations performed by the operator to manipulation members11L and11R.

Travel manipulation member13is used by the operator to control traveling of work vehicle101. Travel manipulation detector14detects a pilot flow rate according to content of control done via travel manipulation member13. Work vehicle101moves at a speed corresponding to the pilot flow rate.

Work implement controller20includes a storage21and a processor22. Storage21is composed of memory such as RAM (Random Access Memory) and ROM (Read Only Memory). Processor22is composed of a processing device such as a CPU (Central Processing Unit).

Work implement controller20mainly controls the operation of work implement4and the revolution of revolving unit3. Particularly, work implement controller20generates a control signal for operating work implement4and revolving unit3in response to manipulations of manipulation members11L and11R. Work implement controller20outputs the generated control signal to a work implement control device27.

b3. Work Implement Drive Device30

Work implement drive device30has a proportional control valve31. Proportional control valve31operates based on a control signal issued from work implement controller20. Particularly, proportional control valve31supplies a hydraulic cylinder and a revolution motor with hydraulic oil at a flow rate corresponding to the control signal. As a result, work implement4operates and revolving unit3revolves.

Display device44of display system40displays various types of images such as work assistance information. Display system40includes a bucket position detector41, a display controller43, and display device44. In display system40, a predetermined reference position is preset as a viewpoint position for the operator.

Bucket position detector41includes a bucket angle sensor411, a dipper stick angle sensor412, and a boom angle sensor413.

Bucket angle sensor411detects a relative angle of bucket7from a predetermined reference position. Dipper stick angle sensor412detects a relative angle of dipper stick6from a predetermined reference position. Boom angle sensor413detects a relative angle of boom5from a predetermined reference position.

Bucket position detector41detects a position of bucket7with respect to the body of the work vehicle based on information of the three relative angles as detected. Particularly, the position of bucket7in the vehicular body coordinate system is detected. Bucket position detector41detects the position of teeth7A of bucket7as the position of bucket7, for example.

Based on the detected position of bucket7, display controller43causes the work assistance information to be displayed on display device44. Particularly, display controller43controls a content to be displayed by display device44, and causes the work assistance information to be displayed around bucket7while causing the work assistance information to follow the movement of bucket7. More particularly, when the work assistance information becomes close to a boundary441(seeFIG. 3) of display area440of display device44due to the movement of bucket7, display controller43causes the work assistance information to be displayed on display device44with a relative position between the work assistance information and bucket7being changed. It should be noted that an inner side relative to boundary441is display area440.

Typically, based on the display position (coordinates) of the work assistance information in display area440, display controller43determines whether or not the work assistance information becomes close to boundary441of display area440. Moreover, the display position of the work assistance information is determined by the position of bucket7.

The determination as to whether or not the work assistance information becomes close to boundary441is not limited to the manner described above. For example, based on the detected position of bucket7, display controller43may determine whether or not the work assistance information becomes close to boundary441. In this case, display controller43can determine whether or not the work assistance information becomes close to boundary441, by determining whether or not bucket7becomes close to a boundary of a three-dimensional predetermined area (hereinafter, referred to as “three-dimensional area Q”).

It should be noted that three-dimensional area Q is typically defined by respective coordinate values of a three-dimensional coordinate system (particularly, the vehicular body coordinate system) in work vehicle101. These coordinate values are set in advance by a work vehicle manufacturer or the like. More particularly, three-dimensional area Q is defined in accordance with the installation position of display device44in the vehicular body coordinate system. Much more particularly, three-dimensional area Q is defined in accordance with the position of the display area of work vehicle101.

Specifically, three-dimensional area Q is an area in which work assistance information92can follow bucket7. Particularly, when attention is paid to one piece of work assistance information, three-dimensional area Q is defined as a position of bucket7at which the work assistance information can be displayed on display device44without changing the position of the work assistance information relative to bucket7.

As described above, the display position of the work assistance information is determined by the position of bucket7. Hence, the expression “bucket7becomes close to the boundary of three-dimensional area Q” means that the work assistance information becomes close to boundary441in display area440.

Moreover, display controller43may determine whether or not the work assistance information becomes close to boundary441of display area440, based on a position (coordinate values in a display area) of an intersection between display area440and an imaginary line that connects the detected position of bucket7to the position of the viewpoint (reference position described above) of the operator.

Display controller43will be described more in detail as follows. Display controller43has an image generator431and a display position processor432.

Image generator431generates an image to be displayed on display device44. Image generator431generates an image representing a vehicular speedometer, an engine revolution indicator, a fuel indicator, a hydraulic temperature indicator, and the like. Further, image generator431generates images representing a plurality of pieces of work assistance information. A specific example of the work assistance information will be described with reference toFIG. 3and the like.

Particularly, image generator431is connected to a controller (not shown) that controls a motive power system of work vehicle101. Image generator431receives information detected by various sensors, information regarding a content of control performed by the controller, and the like. Based on the received information, image generator431generates an image to be displayed on display device44.

Display position processor432calculates a display position of the image on display device44, and causes the image to be displayed at the calculated display position. Particularly, the display position processor calculates the display position of the work assistance information on display device44, and causes the work assistance information to be displayed at the calculated position.

Specifically, display position processor432calculates the display position of the work assistance information on display device44based on the position of bucket7detected by bucket position detector41and the above-described reference position. Specifically, display position processor432calculates the display position at which the work assistance information is to be visually recognized around bucket7when viewed from cab8. Details of the display position calculated by display position processor432will be described later (FIG. 3toFIG. 8and the like).

More particularly, display controller43calculates the position of bucket7and the position of teeth7A of bucket7on display device44. With such a calculation process, the display position of the work assistance information can be caused to follow the movement of bucket7. It should be noted that display controller43is implemented by a processor such as a CPU, a storage such as RAM and ROM, and the like.

C. User Interface

Next, with reference toFIG. 3toFIG. 8, the following describes a method for displaying the work assistance information on display device44.

c1. Manner of Displaying Work Assistance Information

FIG. 3shows a content displayed on display device44in a certain aspect. As shown inFIG. 3, display controller43causes a plurality of pieces of work assistance information91to94to be displayed at display area440of display device44. Particularly, display controller43causes the plurality of pieces of work assistance information91to94at respective positions at which the plurality of pieces of work assistance information91to94are visually recognized around bucket7. Preferably, display controller43causes the plurality of pieces of work assistance information91to94to be displayed at positions higher than teeth7A of bucket7.

In the example ofFIG. 3, display controller43controls the display positions of pieces of work assistance information91,92on display device44such that the pieces of work assistance information91,92are visually recognized at left positions relative to bucket7when viewed from cab8. Further, display controller43controls the display positions of pieces of work assistance information93,94on display device44such that the pieces of work assistance information93,94are visually recognized at right positions relative to bucket7when viewed from cab8.

Work assistance information91represents a facing angle compass. The facing angle compass indicates whether or not work vehicle101directly faces design topography data. Furthermore, when work vehicle101does not directly face the design topography data, the facing angle compass indicates an amount of displacement by way of a rotation angle indicated by an arrow inside a circle. When work vehicle101does not directly face the design topography data, display controller43may cause work assistance information91to be displayed on display device44in a manner different from the manner shown inFIG. 3by deleting the arrow inside the circle of work assistance information91. Moreover, when the work vehicle cannot directly face the design topography data even if the work vehicle is oriented in all the directions, display controller43may cause work assistance information91to be displayed on display device44in a manner different from the manner shown inFIG. 3.

Work assistance information92represents the design topography and the teeth in a cross section (lateral cross section).

Work assistance information93represents a bar indicator. The bar indicator is displayed when finishing excavation is performed. The bar indicator indicates a distance between the design topography and teeth7A more in detail than below-described work assistance information94. Work assistance information94indicates a direction of the design topography and a distance between the design topography and teeth7A. Work assistance information94is displayed at the time of rough excavation and at the time of finishing excavation.

It should be noted that the pieces of work assistance information91to94shown inFIG. 3are exemplary and the work assistance information displayed on display device44is not limited thereto.

Moreover, although details will be described later, each of the pieces of work assistance information91to94follows the movement of bucket7in the upward direction and the downward direction (FIG. 4toFIG. 7). Moreover, each of the pieces of work assistance information91to94follows the movement of cab8of bucket7in the frontward direction and the rearward direction (FIG. 8).

c2. Following Process in Upward Direction and Boundary Process at Upper End Portion

(1) First Example

FIG. 4illustrates a display position of work assistance information92when bucket7is moved upward. As shown inFIG. 4, bucket7in a state (B) is at a position higher than that of bucket7in a state (A). Moreover, bucket7in a state (C) is at a position higher than that of bucket7in the state (B). It should be noted that each of the state (A) and the state (B) represents a case where bucket7is in three-dimensional area Q. On the other hand, the state (C) represents a case where bucket7is outside three-dimensional area Q.

When bucket7is at the position shown in the state (A), display system40displays work assistance information92at a left position P1relative to bucket7when viewed from the operator in cab8. Particularly, display controller43of display system40causes work assistance information92to be displayed at a position higher than teeth7A of bucket7.

When bucket7is moved upward from the state (A), display controller43performs a process for causing the display position of work assistance information92on display device44to follow the movement of bucket7based on a position of bucket7sequentially detected by bucket position detector41. More particularly, display controller43causes the display position of work assistance information92to follow the movement of bucket7to attain a constant relative positional relation between bucket7and work assistance information92.

When bucket7reaches a position shown in the state (B), display controller43causes work assistance information92to be displayed at position P2. Position P2is a position that is higher than position P1shown in the state (A) and that is located at the left side relative to bucket7. It should be noted that also in this case, since the positional relation between bucket7and the work assistance information is maintained to be constant, work assistance information92is displayed at a position higher than teeth7A of bucket7.

When bucket7is moved further upward from inside three-dimensional area Q to outside three-dimensional area Q after the state (B), work assistance information92cannot follow bucket7because the width of the display area of display device44in the upward and downward directions is narrower than the movable range of bucket7in the upward and downward directions.

Hence, display controller43stops the process for causing the display position of work assistance information92to follow the movement of bucket7. Specifically, as shown in the state (C), display controller43causes work assistance information92to be displayed at position P3higher than position P2. Position P3is an upper end area of display device44. To be precise, position P3is a display position of the work assistance information just before bucket7is moved out of three-dimensional area Q.

It should be noted that although display controller43causes work assistance information92to be displayed at position P3in the state (C), the configuration is not limited thereto. When bucket7is moved from inside three-dimensional area Q to outside three-dimensional area Q, display controller43may cause work assistance information92to be displayed at a left corner or right corner of the display area of display device44or the like. For example, display controller43may cause work assistance information92to be displayed at the left corner (area at the upper left corner) of the upper area.

The above-described process can be summarized as described in (i) to (iii) below.

(i) When bucket7is in three-dimensional area Q, display controller43causes the display position of work assistance information92on display device44to follow the movement of bucket7based on the detected position of bucket7. When bucket7is outside three-dimensional area Q, display controller43does not cause the display position of work assistance information92on display device44to follow the movement of bucket7.

According to the above-described configuration, even when bucket7is moved from inside three-dimensional area Q to outside three-dimensional area Q (particularly, even when the display position of work assistance information92cannot be caused to follow bucket7), work assistance information92can continue to be securely displayed by stopping causing work assistance information92to follow bucket7. Therefore, according to work vehicle101, the displaying of the work assistance information can be appropriately controlled as described above. Hence, the operability of work vehicle101can be improved.

(ii) Moreover, when bucket7is in three-dimensional area Q, display controller43controls the display position of work assistance information92on display device44such that work assistance information92is visually recognized around bucket7when viewed from cab8. According to the above-described configuration, the operability of work vehicle101can be improved as compared with a configuration in which work assistance information92is not visually recognized around bucket7when viewed from cab8.

(iii) Moreover, when bucket7is moved upward from inside three-dimensional area Q to outside three-dimensional area Q, display controller43causes work assistance information92to be displayed at the upper end area of display area440. According to the above-described configuration, the work assistance information is displayed at the same or close position as or to the position at which the work assistance information has been displayed just before the work assistance information cannot follow bucket7. Hence, as compared with the case of displaying work assistance information92at a different area, displaying can be performed with excellent convenience for the operator.

(2) Second Example

FIG. 5illustrates each display position of a plurality of pieces of work assistance information91,92,94when bucket7is moved upward. As shown inFIG. 5, bucket7in a state (B) is at a position higher than that of bucket7in a state (A). Moreover, bucket7in a state (C) is at a position higher than that of bucket7in the state (B). It should be noted that each of the state (A) and the state (B) represents a case where bucket7is in three-dimensional area Q. On the other hand, the state (C) represents a case where bucket7is outside three-dimensional area Q.

When bucket7is at the position shown in the state (A), display system40respectively displays the three pieces of work assistance information91,92,94at positions P11, P12, P13. It should be noted that positions P11, P12are left positions relative to bucket7when viewed from the operator. Position P13is a right position relative to bucket7when viewed from the operator. More particularly, display controller43causes the pieces of work assistance information91,92,94to be displayed at positions higher than teeth7A of bucket7. Moreover, position P11at which work assistance information91is displayed is higher than position P12at which work assistance information92is displayed and position P13at which work assistance information94is displayed.

When bucket7is moved upward from the state (A), display controller43performs a process for causing the display positions of the pieces of work assistance information91,92,94on display device44to follow the movement of bucket7based on a position of bucket7sequentially detected by bucket position detector41. More particularly, display controller43causes the display positions of the pieces of work assistance information91,92,94to follow the movement of bucket7to attain a constant relative positional relation between bucket7and each of the pieces of work assistance information91,92,94.

When bucket7reaches a position shown in the state (B), display controller43respectively causes the three pieces of work assistance information91,92,94to be displayed at positions P14, P15, P16. Positions P14, P15, P16are positions higher than positions P11, P12, P13shown in the state (A), respectively. Positions P14, P15are left positions relative to bucket7when viewed from the operator. Position P16is a right position relative to bucket7when viewed from the operator. It should be noted that also in this case, since the positional relation between bucket7and the work assistance information is maintained to be constant, the pieces of work assistance information91,92,94are displayed at positions higher than teeth7A of bucket7. Moreover, position P14at which work assistance information91is displayed is higher than position P15at which work assistance information92is displayed and position P16at which work assistance information94is displayed.

When bucket7is moved further upward from inside three-dimensional area Q to outside three-dimensional area Q after the state (B), work assistance information91first cannot follow bucket7. Particularly, at least work assistance information91of the three pieces of work assistance information91,92,94cannot follow bucket7. More particularly, due to existence of work assistance information91, work assistance information92positioned below work assistance information91also cannot follow bucket7.

Hence, display controller43stops the process for causing the display position of work assistance information91to follow the movement of bucket7. Particularly, display controller43changes a relative position between bucket7in display area440and each of the plurality of pieces of work assistance information91,92,94. Specifically, display controller43changes an arrangement of the plurality of pieces of work assistance information91,92,94. Typically, display controller43changes the arrangement of the three pieces of work assistance information91,92,94such that the display positions of the three pieces of work assistance information91,92,94are at the same level in the upward and downward directions (height direction). For example, when the display position of work assistance information94is higher than the display position of work assistance information92, display controller43arranges work assistance information91and work assistance information92adjacent to each other in the lateral direction, whereby the heights of the display positions of the pieces of work assistance information91and92become the same as the height of the display position of work assistance information94.

Specifically, as shown in the state (C), display controller43respectively causes the three pieces of work assistance information91,92,94to be displayed at positions P17, P18, P19at the same height. It should be noted that positions P17, P18, P19are the upper end area of display area440.

It should be noted that although display controller43causes work assistance information91to be displayed at the right side relative to work assistance information92when viewed from the operator in the state (C), the configuration is not limited thereto. When work assistance information91cannot follow bucket7, display controller43may cause work assistance information91to be displayed at the left side relative to work assistance information92when viewed from the operator.

The above-described process can be summarized as described in (i) to (iii) below.

(i) When the work assistance information becomes close to boundary441of display area440of display device44due to the movement of bucket7, display controller43causes the work assistance information to be displayed on display device44with the relative position between the work assistance information and bucket7in display area440being changed.

According to the above-described configuration, when the work assistance information becomes close to boundary441of display area440of display device44, the work assistance information is displayed with the relative position between the work assistance information and bucket7being changed, whereby the work assistance information can continue to be securely displayed. Hence, the operability of work vehicle101can be improved. Further, the operability of work vehicle101can be improved as compared with a configuration in which the work assistance information is not displayed around bucket7.

(ii) When the work assistance information becomes close to boundary441due to the movement of bucket7in the upward direction, display controller43is configured to change the relative position between the work assistance information and bucket7at the upper end area of display area440.

According to the above-described configuration, the work assistance information is displayed at the same or close position as or to the position at which the work assistance information has been displayed just before the work assistance information cannot follow the movement of bucket7. Hence, as compared with a case of displaying the work assistance information at a different position, displaying can be performed with excellent convenience for the operator.

(iii) Display controller43is configured to cause the plurality of pieces of work assistance information91,92,94to be displayed on display device44in a predetermined arrangement. When at least one of the plurality of pieces of work assistance information91,92,94becomes close to boundary441due to the movement of bucket7, display controller43changes the arrangement of the pieces of work assistance information. According to the above-described configuration, even when there is work assistance information that cannot follow bucket7(for example, work assistance information91in the figure), the work assistance information can continue to be displayed.

c3. Following Process in Downward Direction and Boundary Process at Lower End Portion

(1) First Example

FIG. 6illustrates the display position of work assistance information92when bucket7is moved downward. As shown inFIG. 6, bucket7in a state (B) is at a position lower than that of bucket7in a state (A). Moreover, bucket7in a state (C) is at a position lower than that of bucket7in the state (B). It should be noted that each of the state (A) and the state (B) represents a case where bucket7is in three-dimensional area Q. On the other hand, the state (C) represents a case where bucket7is outside three-dimensional area Q.

When bucket7is at the position shown in the state (A), display system40displays work assistance information92at a left position21relative to bucket7. Particularly, display controller43of display system40causes work assistance information92to be displayed at the position higher than teeth7A of bucket7.

When bucket7is moved downward from the state (A), display controller43performs a process for causing the display position of work assistance information92on display device44to follow the movement of bucket7based on a position of bucket7sequentially detected by bucket position detector41. More particularly, display controller43causes the display position of work assistance information92to follow the movement of bucket7to attain a constant relative positional relation between bucket7and work assistance information92.

When bucket7reaches a position shown in the state (B), display controller43causes work assistance information92to be displayed at a position P22. Position P22is a position that is lower than position P21shown in the state (A) and that is located at the left side relative to bucket7. It should be noted that also in this case, since the positional relation between bucket7and the work assistance information is maintained to be constant, work assistance information92is displayed at a position higher than teeth7A of bucket7.

When bucket7is moved further downward from inside three-dimensional area Q to outside three-dimensional area Q after the state (B), work assistance information92cannot follow bucket7because the width of the display area of display device44in the upward and downward directions is narrower than the movable range of bucket7in the upward and downward directions.

Hence, display controller43stops the process for causing the display position of work assistance information92to follow the movement of bucket7. Specifically, as shown in the state (C), display controller43displays work assistance information92at a position P23lower than position P22. Position P23is a lower end area of display device44. To be precise, position P23is a display position of the work assistance information just before bucket7is moved out of three-dimensional area Q.

It should be noted that although display controller43causes work assistance information92to be displayed at position P23in the state (C), the configuration is not limited thereto. When bucket7is moved from inside three-dimensional area Q to outside three-dimensional area Q, display controller43may cause work assistance information92to be displayed at a left corner or right corner of the display area of display device44or the like. For example, display controller43may cause work assistance information92to be displayed at the left corner (area at the upper lower left corner) of the lower area.

As described above, when bucket7is moved downward from inside three-dimensional area Q to outside three-dimensional area Q, display controller43causes work assistance information92to be displayed at the lower end area (position P23in the case ofFIG. 6) of display area440. According to the above-described configuration, the work assistance information is displayed at the same or close position as or to the position at which the work assistance information has been displayed just before the work assistance information cannot follow bucket7. Hence, as compared with a case of displaying the work assistance information at a different area, displaying can be performed with excellent convenience for the operator.

(2) Second Example

FIG. 7illustrates each display position of a plurality of pieces of work assistance information91,92when bucket7is moved downward. As shown inFIG. 7, bucket7in a state (B) is at a position lower than that of bucket7in a state (A). Moreover, bucket7in a state (C) is at a position lower than that of bucket7in the state (B). It should be noted that each of the state (A) and the state (B) represents a case where bucket7is in three-dimensional area Q. On the other hand, the state (C) represents a case where bucket7is outside three-dimensional area Q.

When bucket7is at the position shown in the state (A), display system40respectively displays the two pieces of work assistance information91,92at positions P31, P32. It should be noted that positions P31, P32are left positions relative to bucket7when viewed from the operator. Particularly, display controller43of display system40causes the pieces of work assistance information91,92to be displayed at positions higher than teeth7A of bucket7. Moreover, position P31at which work assistance information91is displayed is higher than position P32at which work assistance information92is displayed.

When bucket7is moved downward from the state (A), display controller43performs a process for causing the display positions of the pieces of work assistance information91,92on display device44to follow the movement of bucket7based on a position of bucket7sequentially detected by bucket position detector41. More particularly, display controller43causes the display positions of the pieces of work assistance information91,92to follow the movement of bucket7to attain a constant relative positional relation between bucket7and each of the pieces of work assistance information91,92.

When bucket7reaches a position shown in the state (B), display controller43respectively causes the two pieces of work assistance information91,92to be displayed at positions P33, P34. Positions P33, P34are positions lower than positions P31, P32shown in the state (A), respectively. Positions P33, P34are left positions relative to bucket7when viewed from the operator. It should be noted that also in this case, since the positional relation between bucket7and the work assistance information is maintained to be constant, the pieces of work assistance information91,92are displayed at positions higher than teeth7A of bucket7. Moreover, position P33at which work assistance information91is displayed is higher than position P34at which work assistance information92is displayed.

When bucket7is moved further downward from inside three-dimensional area Q to outside three-dimensional area Q after the state (B), work assistance information92first cannot follow bucket7. Particularly, at least work assistance information92of the two pieces of work assistance information91,92cannot follow bucket7. More particularly, due to existence of work assistance information92, work assistance information91positioned above work assistance information92also cannot follow bucket7.

Hence, display controller43stops the process for causing the display position of work assistance information92to follow the movement of bucket7. Particularly, display controller43changes a relative position between bucket7in display area440and each of the plurality of pieces of work assistance information91,92. Specifically, display controller43changes an arrangement of the plurality of pieces of work assistance information91,92. Typically, display controller43changes the arrangement of the two pieces of work assistance information91,92such that the display positions of the two pieces of work assistance information91,92are at the same level in the upward and downward directions (height direction). For example, display controller43arranges work assistance information91and work assistance information92adjacent to each other in the lateral direction, whereby the heights of the display positions of the pieces of work assistance information91and92become the same.

Specifically, as shown in the state (C), display controller43respectively causes the two pieces of work assistance information91,92to be displayed at positions P35, P36at the same height. It should be noted that positions P35, P36are the lower end area of display area440.

It should be noted that although display controller43causes work assistance information91to be displayed at the left side relative to work assistance information92when viewed from the operator in the state (C), the configuration is not limited thereto. When work assistance information91cannot follow bucket7, display controller43may cause work assistance information91to be displayed at the right side relative to work assistance information92when viewed from the operator.

As described above, when the work assistance information becomes close to boundary441of display area440of display device44due to the movement of bucket7, display controller43causes the work assistance information to be displayed on display device44with the relative position between the work assistance information and bucket7being changed. Particularly, when the work assistance information becomes close to boundary441due to the movement of bucket7in the downward direction, display controller43is configured to change the relative position between the work assistance information and bucket7at the lower end area of display area440.

More particularly, display controller43is configured to cause the plurality of pieces of work assistance information91,92to be displayed on display device44in a predetermined arrangement. When at least one of the plurality of pieces of work assistance information91,92becomes close to boundary441due to the movement of bucket7, display controller43changes the arrangement of the pieces of work assistance information. According to the above-described configuration, even when there is work assistance information that cannot follow bucket7, the work assistance information can continue to be displayed.

c4. Following Process in Rearward Direction and Boundary Process

FIG. 8illustrates a display position of work assistance information94when bucket7is moved in the direction (rearward direction) in which bucket7becomes close to cab8. As shown inFIG. 8, bucket7in a state (B) is at a position closer to cab8than bucket7in a state (A). Moreover, bucket7in a state (C) is at a position closer to cab8than bucket7in the state (B). It should be noted that each of the state (A) and the state (B) represents a case where bucket7is in three-dimensional area Q. On the other hand, the state (C) represents a case where bucket7is outside three-dimensional area Q.

When bucket7is at the position shown in the state (A), display system40displays work assistance information94at a right position P41relative to bucket7when viewed from the operator in cab8. Particularly, display controller43of display system40causes work assistance information94to be displayed at a position higher than teeth7A of bucket7.

When bucket7is moved rearward (toward the cab8side) from the state (A), display controller43performs a process for causing the display position of work assistance information94on display device44to follow the movement of bucket7based on a position of bucket7sequentially detected by bucket position detector41. More particularly, display controller43causes the display position of work assistance information94to follow the movement of bucket7to attain a constant relative positional relation between bucket7and work assistance information94.

When bucket7reaches a position shown in the state (B), display controller43causes work assistance information94to be displayed at position P42. Position P42is a right position relative to bucket7when viewed from the operator. It should be noted that also in this case, since the positional relation between bucket7and the work assistance information is maintained to be constant, work assistance information94is displayed at a position higher than teeth7A of bucket7.

When bucket7is moved further rearward from inside three-dimensional area Q to outside three-dimensional area Q after the state (B), the width of the display area of display device44at the right side relative to bucket7becomes narrow. Particularly, since the visually recognized area of bucket7in display device44is increased, the area around the bucket at the right side relative to bucket7when viewed from the operator becomes narrow. Accordingly, display controller43cannot cause work assistance information94to be displayed at the right side relative to bucket7when viewed from the operator. Particularly, display controller43cannot cause work assistance information94to follow the movement of bucket7in an area at the right side relative to bucket7when viewed from the operator.

Therefore, display controller43changes the relative position between bucket7and work assistance information94. Particularly, in order to cause the display position of work assistance information94to follow the movement of bucket7, display controller43stops displaying work assistance information94at the right side relative to bucket7when viewed from the operator, and causes work assistance information94to be displayed at the left side relative to bucket7when viewed from the operator. As such, display controller43causes work assistance information94to be displayed at an opposite position relative to bucket7. Typically, display controller43causes work assistance information94to be displayed above teeth7A of bucket7.

Then, display controller43causes work assistance information94to follow the movement of bucket7in the rearward direction. For example, when bucket7reaches a position shown in the state (C), display controller43causes work assistance information94to be displayed at position P43.

As described above, when work assistance information94becomes close to boundary441of display area440of display device44due to the movement of bucket7, display controller43causes work assistance information94to be displayed on display device44with the relative position between work assistance information94and bucket7being changed.

Particularly, when work assistance information94becomes close to boundary441due to the movement of bucket7in the rearward direction (direction toward cab8), display controller43causes work assistance information94displayed at the right position relative to bucket7to be displayed at the left position relative to bucket7. According to the above-described configuration, even when bucket7becomes close to cab8, the display position of work assistance information94can be caused to follow bucket7.

It should be noted that in a work vehicle in which the work implement is provided at a position that can be visually recognized at a forward left side relative to the cab, display controller43may be configured to cause work assistance information94displayed at the left position relative to bucket7to be displayed at the right position relative to bucket7when work assistance information94becomes close to boundary441due to the movement of bucket7in the rearward direction (direction toward cab8).

D. Control Structure

FIG. 9is a flowchart for illustrating a process for displaying the work assistance information. As shown inFIG. 9, in a step S1, display controller43calculates three-dimensional position information of work vehicle101on a global coordinate system. In a step S2, display controller43calculates the position of bucket7and the position of teeth7A on the vehicular body coordinate system. In a step S3, display controller43calculates the position of bucket7and the position of teeth7A on the global coordinates. It should be noted that the position of bucket7on the global coordinate system and the like are calculated in order to display, on display device44, information employing target topography information stored in advance.

In a step S4, display controller43calculates distance information between the target design topography and teeth7A based on the current position of teeth of bucket7on the global coordinates and the above-described target topography information. In a step S5, display controller43generates a display content of the work assistance information based on the distance information calculated in step S4.

In steps S6to S8, display controller43calculates the display position of the work assistance information based on the current position of bucket7(for example, the current position of teeth7A). Particularly, in step S6, based on the position of bucket7calculated in step S2, display controller43determines whether or not bucket7is in three-dimensional area Q. More particularly, based on the bucket position detected by bucket position detector41, display controller43determines whether or not bucket7is in three-dimensional area Q.

When it is determined that bucket7is in three-dimensional area Q (YES in step S6), in step S7, display controller43causes the display position of the work assistance information on display device44to follow the movement of bucket7based on the position of bucket7. When it is determined that bucket7is outside three-dimensional area Q (NO in step S6), display controller43does not cause the display position of the work assistance information on display device44to follow the movement of bucket7(step S8).

After steps S7and S8, in a step S9, display controller43causes the work assistance information to be displayed at the display position calculated in step S5.

e1. First Modification

In the description above, there has been illustratively described the configuration in which display device44is provided in opening frame9A; however, the configuration is not limited thereto. Another display device may be included also in opening frame9B. Particularly, cab8may be configured to include a transparent dual display. In this case, display controller43controls displaying in two display devices.

A work vehicle having such a configuration can also achieve an effect similar to that obtained by work vehicle101described above. It should be noted that in this case, the work assistance information can also be displayed in the lower display device. Hence, when bucket7is moved in the downward direction, display controller43can cause the work assistance information to follow bucket7to a position lower than that in the case shown inFIG. 6and the like.

e2. Second Modification

FIG. 10illustrates each display position of a plurality of pieces of work assistance information91,92,94when bucket7is moved upward. As shown inFIG. 10, bucket7in a state (B) is at a position higher than that of bucket7in a state (A). Moreover, bucket7in a state (C) is at a position higher than that of bucket7in the state (B). It should be noted that each of the state (A) and the state (B) represents a case where bucket7is in three-dimensional area Q. On the other hand, the state (C) represents a case where bucket7is outside three-dimensional area Q.

Particularly, the state (A) ofFIG. 10represents the same state as the state (A) ofFIG. 5. The state (B) ofFIG. 10represents the same state as the state (B) ofFIG. 5. Therefore, the states (A) and (B) ofFIG. 10will not be repeatedly described here.

When bucket7is moved further upward from inside three-dimensional area Q to outside three-dimensional area Q after the state (B), work assistance information91first cannot follow bucket7. Particularly, at least work assistance information91of the three pieces of work assistance information91,92,94cannot follow bucket7. More particularly, due to existence of work assistance information91, work assistance information92positioned below work assistance information91also cannot follow bucket7. Therefore, display controller43stops displaying work assistance information91.

As such, when work assistance information91becomes close to boundary441of display area440of display device44due to the movement of bucket7, display controller43stops displaying work assistance information91.

According to the above-described configuration, by stopping displaying work assistance information91when work assistance information91becomes close to boundary441of display area440, the operator can visually recognize a front view clearly. Moreover, by stopping displaying work assistance information91, the other pieces of work assistance information92,94can be caused to follow the bucket. Hence, the operability of the work vehicle can be improved.

e3. Third Modification

Work vehicle101may include a display device having a configuration different from that of display device44. Specifically, work vehicle101may include a combiner as a display device.

FIG. 11shows another display device having a configuration different from that of display device44according to an embodiment. As shown inFIG. 11, a display device70is provided in cab8, and has a projection device71, an optical lens system72, and a combiner73.

Projection device71is a projector. Optical lens system72is disposed between projection device71and combiner73. Optical lens system72has a plurality of lenses. Optical lens system72has the plurality of lenses with some thereof movable along the optical axis.

Combiner73is disposed at front windshield2A. Combiner73may be disposed at front windshield2A and front windshield2B. Combiner73is composed of a half mirror which reflects a part of light and transmits a remainder thereof. Combiner73reflects an image projected by projection device71to the side of the operator in cab8and transmits light from the outside of cab8to the interior of cab8.

Thus, display device70allows the operator to recognize the image projected on combiner73as a virtual image overlaid and thus displayed on an actual view in front of cab8.

Thus a work vehicle comprising display device70using combiner73can also achieve an effect similar to that of work vehicle101of an embodiment.

e4. Fourth Modification

In the description above, there has been illustratively described the configuration in which the work assistance information follows the movement of bucket7in the whole of display area440of display device44. Particularly, there has been illustratively described the configuration in which the work assistance information follows the movement of bucket7to an end area of display area440of display device44(typically, to the upper end area and lower end area). However, the configuration is not limited thereto.

Display system40may be configured to cause the work assistance information to follow the movement of bucket7in a part of display area440(display screen) of display device44. For example, the part of display area440can be an area that includes a central portion of display area440of display device44and that does not include at least one of the four end portions (the upper end portion, lower end portion, left end portion, and right end portion) of display area440of display device44. It should be noted that display system40may be configured to permit the operator to set the part of display area440.

Moreover, in this case, a three-dimensional area Q′ narrower than three-dimensional area Q may be set as the predetermined area and display controller43may be configured as follows. When the bucket is in three-dimensional area Q′, display controller43causes the display position of work assistance information92on display device44to follow the movement of bucket7based on the detected position of the bucket. When bucket7is outside three-dimensional area Q′, display controller43does not cause the display position of the work assistance information on display device44to follow the movement of bucket7.

According to the above-described configuration, the work assistance information can be caused to follow the movement of bucket7only in a part of the display area.

While in the above description a configuration in which display device44displays in a display area inside opening frame9A has been described as an example, the present invention is not limited thereto. Display device44may also display an inside of opening frame9B as a display area. That is, cab8may be configured to include a transparent dual display. In that case, display controller43will control displaying in two display areas. It is also possible to provide another display device for the display area of opening frame9B.

A work vehicle having such a configuration can also achieve an effect similar to that obtained by work vehicle101described above. Note that in the above case, the work assistance information can also be displayed in a display area of the lower display device.

While a hydraulic excavator has been described as an example of a work vehicle, the work vehicle is also applicable to a backhoe loader and other work vehicles.

It should be understood that the embodiments disclosed herein are illustrative and not limited to the above disclosure. The scope of the present invention is defined by the terms of the claims, and is intended to include any modifications within the meaning and scope equivalent to the terms of the claims.

REFERENCE SIGNS LIST