Control system for work vehicle, method, and work vehicle

A work vehicle includes a work implement. A control system for the work vehicle includes an operating device and a controller. The operating device outputs an operation signal indicative of an operation by an operator. The controller communicates with the operating device and controls the work implement. The controller determines a first target design topography. The controller generates a command signal to operate a work implement in accordance with the first target design topography. The controller obtains a displacement amount of the work implement with respect to the first target design topography upon receiving the operation signal indicative of the operation of the work implement during work in accordance with the first target design topography. The controller determines a second target design topography based on the displacement amount. The controller generates a command signal to operate the work implement in accordance with the second target design topography.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a U.S. National stage application of International Application No. PCT/JP2019/005833, filed on Feb. 18, 2019. This U.S. National stage application claims priority under 35 U.S.C. § 119(a) to Japanese Patent Application No. 2018-062238, filed in Japan on Mar. 28, 2018, the entire contents of which are hereby incorporated herein by reference.

BACKGROUND

Field of the Invention

The present invention relates to a control system for a work vehicle, a method, and a work vehicle.

Background Information

A control for automatically adjusting the position of a work implement such as a blade has been conventionally proposed for work vehicles such as bulldozers or graders and the like. For example, Japanese Patent Publication No. 5247939 describes automatically adjusting a blade by controlling the load so that the load applied to the blade matches a target load during excavating work.

SUMMARY

According to the abovementioned conventional control, the occurrence of shoe slip can be suppressed by raising the blade when the load on the blade becomes excessive. As a result, work can be performed with good efficiency.

However, as illustrated inFIG.20, in the conventional control, first the blade is controlled so as to follow a design topography100. Thereafter, when the load on the blade becomes large, the blade is raised due to the load control (see the locus200of the blade inFIG.20). Therefore, when the blade is in a position deep in the design topography100with respect to the actual topography300, the load applied to the blade increases very quickly whereby the blade may be raised very quickly. In this case, because the terrain is formed with large undulations, it may be difficult to carry out excavating work smoothly. Moreover, there is a concern that the excavated terrain may easily become rough and the quality of the finish may decrease.

An object of the present invention is to cause a work vehicle to perform work efficiently and with a good finish quality with automatic control.

A first aspect is a control system for a work vehicle including a work implement, the control system including an operating device and a controller. The operating device outputs an operation signal indicating an operation by an operator. The controller communicates with the operating device and controls the work implement. The controller is programmed so as to execute the following processes. The controller determines a first target design topography. The controller generates a command signal for operating the work implement in accordance with the first target design topography. The controller obtains a displacement amount of the work implement from the first target design topography upon receiving the operation signal which indicates an operation of the work implement by the operator during work in accordance with the first target design topography. The controller determines a second target design topography based on the displacement amount. The controller generates a command signal for operating the work implement in accordance with the second target design topography.

A second aspect is a method executed by the controller in order to control a work vehicle including a work implement, the method including the following processes. A first process includes determining a first target design topography. A second process includes generating a command signal for operating the work implement in accordance with the first target design topography. A third process includes receiving an operation signal which indicates an operation by an operator, from an operating device. A fourth process includes obtaining a displacement amount of the work implement from the first target design topography upon receiving the operation signal which indicates an operation of the work implement by the operator during work in accordance with the first target design topography. A fifth process includes determining a second target design topography based on the displacement amount. A sixth process includes generating a command signal for operating the work implement in accordance with the second target design topography.

A third aspect is a work vehicle, the work vehicle including a work implement, an operating device, and a controller. The operating device outputs an operation signal indicating an operation by an operator. The controller receives the operation signal and controls the work implement. The controller is programmed so as to execute the following processes. The controller determines a first target design topography. The controller generates a command signal for operating the work implement in accordance with the first target design topography. The controller obtains a displacement amount of the work implement from the first target design topography upon receiving the operation signal which indicates an operation of the work implement by the operator during work in accordance with the first target design topography. The controller determines a second target design topography based on the displacement amount. The controller generates a command signal for operating the work implement in accordance with the second target design topography.

According to the present invention, a work vehicle can be made to perform work efficiently and with a good finish quality with automatic control.

DETAILED DESCRIPTION OF EMBODIMENT(S)

A work vehicle according to an embodiment is discussed hereinbelow with reference to the drawings.FIG.1is a side view of a work vehicle1according to an embodiment. The work vehicle1according to the present embodiment is a bulldozer. The work vehicle1includes a vehicle body11, a travel device12, and a work implement13.

The vehicle body11has an operating cabin14and an engine compartment15. An operator's seat that is not illustrated is disposed inside the operating cabin14. The engine compartment15is disposed in front of the operating cabin14. The travel device12is attached to a bottom part of the vehicle body11. The travel device12has a pair of left and right crawler belts16. Only the crawler belt16on the left side is illustrated inFIG.1. The work vehicle1travels due to the rotation of the crawler belts16.

The work implement13is attached to the vehicle body11. The work implement13has a lift frame17, a blade18, and a lift cylinder19. The lift frame17is attached to the vehicle body11in a manner that allows movement up and down centered on an axis X that extends in the vehicle width direction. The lift frame17supports the blade18.

The blade18is disposed in front of the vehicle body11. The blade18moves up and down accompanying the up and down motion of the lift frame17. The lift frame17may be attached to the travel device12. The lift cylinder19is coupled to the vehicle body11and the lift frame17. Due to the extension and contraction of the lift cylinder19, the lift frame17rotates up and down centered on the axis X.

FIG.2is a block diagram of a configuration of a drive system2and a control system3of the work vehicle1. As illustrated inFIG.2, the drive system2includes an engine22, a hydraulic pump23, and a power transmission device24.

The hydraulic pump23is driven by the engine22to discharge hydraulic fluid. The hydraulic fluid discharged from the hydraulic pump23is supplied to the lift cylinder19. While only one hydraulic pump23is illustrated inFIG.2, a plurality of hydraulic pumps may be provided.

The power transmission device24transmits driving power from the engine22to the travel device12. The power transmission device24may be a hydrostatic transmission (HST), for example. Alternatively, the power transmission device24, for example, may be a transmission including a torque converter or a plurality of speed change gears.

The control system3includes an operating device25a, an input device25b, a controller26, a storage device28, and a control valve27. The operating device25aand the input device25bare disposed in the operating cabin14. The operating device25ais a device for operating the work implement13and the travel device12. The operating device25ais disposed in the operating cabin14. The operating device25areceives operations from an operator for driving the work implement13and the travel device12, and outputs operation signals in accordance with the operations. The operating device25aincludes, for example, an operating lever, a pedal, and a switch and the like.

The input device25bis a device for performing belowmentioned automatic control settings of the work vehicle1. The input device25breceives an operation by an operator and outputs an operation signal corresponding to the operation. The operation signals of the input device25bare output to the controller26. The input device25bis, for example, a touch screen display. However, the input device25bis not limited to a touch screen and may include hardware keys.

The controller26is programmed so as to control the work vehicle1based on obtained data. The controller26includes, for example, a processing device (processor) such as a CPU. The controller26obtains operation signals from the operating device25aand the input device25b. The controller26is not limited to one component and may be divided into a plurality of controllers. The controller26controls the travel device12or the power transmission device24thereby causing the work vehicle1to travel. The controller26controls the control valve27thereby causing the blade18to move up and down.

The control valve27is a proportional control valve and is controlled with command signals from the controller26. The control valve27is disposed between the hydraulic pump23and hydraulic actuators such as the lift cylinder19. The control valve27controls the flow rate of the hydraulic fluid supplied from the hydraulic pump23to the lift cylinder19. The controller26generates a command signal to the control valve27so that the blade18moves. As a result, the lift cylinder19is controlled. The control valve27may also be a pressure proportional control valve. Alternatively, the control valve27may be an electromagnetic proportional control valve.

The control system3includes a work implement sensor29. The work implement sensor29detects the position of the work implement13and outputs a work implement position signal which indicates the position of the work implement13. The work implement sensor29may be a displacement sensor that detects displacement of the work implement13. Specifically, the work implement sensor29detects the stroke length (referred to below as “lift cylinder length L”) of the lift cylinder19. As illustrated inFIG.3, the controller26calculates a lift angle θlift of the blade18based on the lift cylinder length L. The work implement sensor29may be a rotation sensor that directly detects the rotation angle of the work implement13.

FIG.3is a schematic view of a configuration of the work vehicle1. The reference position of the work implement13is depicted as a chain double-dashed line inFIG.3. The reference position of the work implement13is the position of the blade18while the blade tip of the blade18is in contact with the ground surface on a horizontal ground surface. The lift angle θlift is the angle from the reference position of the work implement13.

As illustrated inFIG.2, the control system3includes a positional sensor31. The positional sensor31measures the position of the work vehicle1. The positional sensor31includes a global navigation satellite system (GNSS) receiver32and an IMU33. The GNSS receiver32is, for example, a receiving apparatus for a global positioning system (GPS). For example, an antenna of the GNSS receiver32is disposed on the operating cabin14. The GNSS receiver32receives a positioning signal from a satellite, computes the position of the antenna from the positioning signal, and generates vehicle body position data. The controller26obtains the vehicle body position data from the GNSS receiver32. The controller26derives the traveling direction and the vehicle speed of the work vehicle1from the vehicle body position data.

The vehicle body position data may not be data of the antenna position. The vehicle body position data may be data that indicates a position of an arbitrary position having a fixed positional relationship with an antenna inside the work vehicle1or in the surroundings of the work vehicle1.

The IMU33is an inertial measurement device. The IMU33obtains vehicle body inclination angle data. The vehicle body inclination angle data includes the angle (pitch angle) relative to horizontal in the vehicle front-back direction and the angle (roll angle) relative to horizontal in the vehicle lateral direction. The controller26obtains the vehicle body inclination angle data from the IMU33.

The controller26computes a blade tip position Pb from the lift cylinder length L, the vehicle body position data, and the vehicle body inclination angle data. As illustrated inFIG.3, the controller26calculates global coordinates of the GNSS receiver32based on the vehicle body position data. The controller26calculates the lift angle θlift based on the lift cylinder length L. The controller26calculates local coordinates of the blade tip position Pb with respect to the GNSS receiver32based on the lift angle θlift and vehicle body dimension data. The vehicle body dimension data is stored in the storage device28and indicates the position of the work implement13with respect to the GNSS receiver32. The controller26calculates the global coordinates of the blade tip position Pb based on the global coordinates of the GNSS receiver32, the local coordinates of the blade tip position Pb, and the vehicle body inclination angle data. The controller26obtains the global coordinates of the blade tip position Pb as blade tip position data.

The storage device28includes, for example, a memory and an auxiliary storage device. The storage device28may be a RAM or a ROM, for example. The storage device28may be a semiconductor memory or a hard disk and the like. The storage device28is an example of a non-transitory computer-readable recording medium. The storage device28records computer commands for controlling the work vehicle1and that are executable by the processor.

The storage device28stores design topography data and work site topography data. The design topography data indicates the final design topography. The final design topography is the final target shape of the surface of a work site. The work site topography data is, for example, a civil engineering diagram map in a three-dimensional data format. The work site topography data indicates the topography of a wide area of the work site. The work site topography data is, for example, an actual topographical survey map in a three-dimensional data format. The work site topography data can be derived, for example, from an aerial laser survey.

The controller26obtains actual topography data. The actual topography data indicates the actual topography of the work site. The actual topography of the work site is the topography of an area in the traveling direction of the work vehicle1. The actual topography data is obtained by computations by the controller26from the work site topography data, the position of the work vehicle1obtained by the abovementioned positional sensor31, and from the traveling direction. The actual topography data may be obtained by performing distance surveying on the actual topography with an on-board laser imaging detection and ranging device (LIDAR).

The controller26automatically controls the work implement13based on the actual topography data, the design topography data, and the blade tip position data. The automatic control of the work implement13may be a semi-automatic control that is performed in accompaniment with manual operations by the operator. Alternatively, the automatic control of the work implement13may be a fully automatic control that is performed without manual operations by an operator. The traveling of the work vehicle1may be controlled automatically by the controller26. For example, the travel control of the work vehicle1may be a fully automatic control that is performed without manual operations by an operator. Alternatively, the travel control may be a semi-automatic control that is performed in accompaniment with manual operations by an operator. Alternatively, the travel of the work vehicle1may be performed with manual operations by the operator.

Automatic control of the work vehicle1during excavation and executed by the controller26will be explained below. The controller26starts the automatic control when a predetermined starting condition is met. The predetermined starting condition may be, for example, that an operation signal which indicates a lowering operation of the work implement13is received from the operating device25a. Alternatively, the predetermined starting condition may be that an operation signal indicating an automatic control starting command is received by the controller26from the input device25b.

FIG.4is a flow chart of automatic control processes of the work vehicle1. As illustrated inFIG.4, the controller26obtains the current position data in step S101. The controller26obtains the current blade tip position Pb of the work implement13as indicated above.

In step S102, the controller31obtains the design topography data. As illustrated inFIG.5, the design topography data includes a height Zdesign of a final design topography60at a plurality of reference points Pn (n=0, 1, 2, 3, . . . , A) in the traveling direction of the work vehicle1. The plurality of reference points Pn indicate a plurality of spots at predetermined intervals in the traveling direction of the work vehicle1. The plurality of reference points Pn are on the travel path of the blade18. InFIG.5, while the final design topography60has a shape that is flat and parallel to the horizontal direction, the shape of the final design topography60may be different.

In step S103, the controller26obtains the actual topography data. The controller26obtains the actual topography data by computations of the work site topography data obtained from the storage device28and the vehicle body position data and the traveling direction data obtained by the positional sensor31.

The actual topography data is information which indicates the topography located in the traveling direction of the work vehicle1.FIG.5illustrates a cross-section of actual topography50. InFIG.5, the vertical axis indicates the height of the topography and the horizontal axis indicates the distance from the current position in the traveling direction of the work vehicle1.

Specifically, the actual topography data includes a height Zn of the actual topography50at each of the plurality of reference points Pn from the current position to a predetermined topography recognition distance dA in the traveling direction of the work vehicle1. In the present embodiment, the current position may be a position defined based on the current blade tip position Pb of the work vehicle1. However, the current position may also be defined based on the current position of another portion of the work vehicle1. The plurality of reference points are aligned with a predetermined interval, for example 1 m, between each point.

In step S104, the controller26determines the target design topography data. The target design topography data represents a target design topography70indicated by the dashed line inFIG.5. The target design topography70represents a desired locus of the blade tip of the blade18during the work. The target design topography70is a target profile of the topography that is the work object and represents the desired shape as a result of the excavating work. As illustrated inFIG.5, the controller26determines at least a portion of the target design topography70located below the actual topography50.

The controller26determines the target design topography70so as not to go below the final design topography60. Therefore, the controller26determines the target design topography70located above the final design topography60and below the actual topography50during the excavating work.

In step S105, the controller26controls the work implement13in accordance with the target design topography70. The controller26generates command signals for the work implement13so as to move the blade tip position of the blade18in accordance with the target design topography70. The generated command signal is inputted to the control valve27. Consequently, the blade tip position PB of the blade18moves toward the target design topography70.

In step S106, the controller26updates the work site topography data. The controller26updates the work site topography data with the position data that indicates the most recent locus of the blade tip position Pb. The update of the work site topography data may be performed at any time. Alternatively, the controller26may calculate the location of the bottom surface of the crawler belts16from the vehicle body position data and the vehicle body dimension data, and may update the work site topography data with the position data that indicates the locus of the bottom surface of the crawler belts16. In this case, the updating of the work site topography data can be performed promptly.

Alternatively, the work site topography data may be generated from survey data measured by a survey device outside of the work vehicle1. For example, aerial laser surveying may be used as the external measurement device. Alternatively, the actual topography50may be imaged by a camera and the work site topography data may be generated from image data captured by the camera. For example, aerial photography surveying performed with an unmanned aerial vehicle (UAV) may be used. When using the external surveying device or a camera, the updating of the work site topography data may be performed at predetermined periods or at any time.

By repeating the above processes, the excavating is performed so that the actual topography50approaches the final design topography60.

The processing for determining the target design topography70is explained in detail below.FIG.6is a flow chart of a process for determining the target design topography70. As illustrated inFIG.6, in step S201, the controller26determines a starting point S0. As illustrated inFIG.7, the controller26determines, as the starting point S, a position that is a predetermined distance L1in front of the blade tip position Pb at the point in time that the automatic control starts. The predetermined distance L1is saved in the storage device28. The input device25bmay be used to allow setting of the predetermined distance L1.

In step S202, the controller26determines a plurality of division points An (n=1, 2, . . . ) based on the actual topography data. As illustrated inFIG.7, the controller26demarcates the actual topography50into a plurality of divisions according to the division points An. The division points An are spots positioned away from each other by a predetermined interval L2on the actual topography50. The predetermined interval L2is, for example, 3 m. However, the predetermined interval L2may be less than 3 m or greater than 3 m. The predetermined interval L2is saved in the storage device28. The input device25bmay be used to allow setting of the predetermined interval L2. The controller26determines, as the division points An, a plurality of spots at each predetermined interval L2in the traveling direction of the work vehicle1from the starting point S0.

In step S203, the controller26smooths the actual topography data. The controller26smooths the actual topography data by linear interpolation. Specifically, as illustrated inFIG.8, the controller26smooths the actual topography data by replacing the actual topography50with straight lines that link each of the division points An.

In step S204, the controller26determines a target depth L3. The controller26determines the target depth L3in accordance with a control mode set with the input device25b. For example, the operator is able to select any of a first mode, a second mode, and a third mode with the input device25b. The first mode is a control mode with the greatest load and the third mode is a control mode with the smallest load. The second mode is a control mode with a load between the first mode and the third mode.

The target depths L3corresponding to each mode are saved in the storage device28. The controller26selects, as the target depth L3, a first target depth of the first mode, a second target depth of the second mode, or a third target depth of the third mode. The first target depth is greater than the second target depth. The second target depth is greater than the third target depth. The input device25bmay be used to allow optional setting of the target depth L3.

In step S205, the controller26determines a plurality of reference points. As illustrated inFIG.9, the controller26determines, as respective reference points B1and B2, spots displaced downward by the target depth L3from the first preceding division point A1and from the second preceding division point A2.

In step S206, the controller26determines a plurality of reference topographies. As illustrated inFIG.9, the controller26determines a first reference topography C1and a second reference topography C2. The first reference topography C1is represented by a straight line that links the starting point S0and the first preceding reference point B1. The second reference topography C2is represented by a straight line that links the starting point S0and the second preceding reference point B2.

In step S207, the controller26determines the target design topography70. The controller26determines the target design topography70for each division demarcated by the plurality of division points An. As illustrated inFIG.10, the controller26determines a first target design topography70_1that passes between the first reference topography C1and the second reference topography C2. The first target design topography70_1is the target design topography70in the division (referred to below as “first division”) between the starting point S0and the first preceding division point A1.

Specifically, the controller26calculates the average angle of the first reference topography C1and the second reference topography C2. The average angle is the average value between the angle of the first reference topography C1with respect to the horizontal direction and the angle of the second reference topography C2with respect to the horizontal direction The controller26determines, as the first target design topography70_1, a straight line that is inclined by the average angle with respect to the horizontal direction.

When the first target design topography70_1is determined as indicated above, the controller26controls the work implement13in accordance with the first target design topography70_1in accordance with the abovementioned process of step S105as illustrated inFIG.11.

In step S208, the controller26determines the next starting point S1. The next starting point S1is the starting point of the next target design topography70, namely a second target design topography70_2. The second target design topography70_2is the target design topography70in the division (referred to below as the “second division”) between the next starting point S1and the first preceding division point A2. As illustrated inFIG.12, the next starting point S1is the end position of the first target design topography70_1and is positioned directly below the division point A1.

Upon determining the next starting point S1, the controller26determines the second target design topography70_2by repeating the processes from step S205to step S207. The controller26determines the second target design topography70_2while working in accordance with the first target design topography70_1.

Specifically, as illustrated inFIG.12, the controller26determines, as the next first reference topography C1, a straight line that links the next starting point S1and the first preceding reference point B2. The controller26also determines, as the next second reference topography C2, a straight line that links the next starting point S1and the second preceding reference point B3. The controller26determines the second target design topography70_2from the average angle of the first reference topography C1and the second reference topography C2.

When the work vehicle1reaches the next starting point S1, the controller26controls the work implement13in accordance with the second target design topography70_2in accordance with the abovementioned process of step S105. The controller26then continues the excavation of the actual topography50by repeating the above processes.

When a predetermined completion condition is satisfied, the controller26finishes the abovementioned processes for determining the target design topography70. The predetermined completion condition is, for example, that the amount of material held by the work implement13has reached a predetermined upper limit. When the predetermined completion condition is satisfied, the controller26controls the work implement13so as to follow the actual topography50. Consequently, the excavated material can be transported smoothly.

The process when a manual operation of the work implement13is introduced by the operator during the abovementioned automatic control is explained next.FIG.13is a flow chart of a process when a manual operation is introduced. In the following explanation as illustrated inFIG.14, a manual operation of the work implement13is introduced by the operator during the work in accordance with the first target design topography70_1.

In step S301, the controller26determines that a manual operation has been performed. The controller26determines that a manual operation has been performed when an operation signal which indicates an operation for causing the work implement13to move up or down is received from the operating device25a. The process advances to S302when the manual operation is performed.

In step S302, the controller26obtains the displacement amount of the work implement13. Specifically, as illustrated inFIG.14, the controller26calculates a displacement amount L4in the vertical direction of the blade tip position Pb with respect to the first target design topography70_1.

In step S303, the controller26corrects the target design topography70during the current work. That is, as illustrated inFIG.15, the controller26corrects the first target design topography70_1so as to match the modified height of the blade tip position Pb. In addition, the controller26controls the work implement13in accordance with the corrected first target design topography70_1.

The controller26raises the first target design topography70_1to match the height of the blade tip position Pb when a raising operation of the work implement13is performed. The controller26lowers the first target design topography70_1to match the height of the blade tip position Pb when a lowering operation of the work implement13is performed.

In step S304, the controller26corrects the target depth L3based on the displacement amount L4. When a raising operation of the work implement13is performed, the controller26reduces the target depth L3by the displacement amount L4. When a lowering operation of the work implement13is performed, the controller26increases the target depth L3by the displacement amount L4.

In step S305, the controller26determines the target design topography70for the next division based on a corrected target depth L3′. That is, as illustrated inFIG.16, the controller26determines the second target design topography70_2based on the corrected target depth L3′. The second target design topography70_2is determined in accordance with the abovementioned processes from step S205to step S207.

Specifically, the controller26determines the next starting point S1from the corrected first target design topography70_1. The controller26determines respective reference points B2and B3by displacing the division points A2and A3in the vertical direction by the corrected target depth L3′. The controller26determines, as the next first reference topography C1, a straight line that links the next starting point S1and the first preceding reference point B2. The controller26also determines, as the next second reference topography C2, a straight line that links the next starting point S1and the second preceding reference point B3. The controller26determines the second target design topography70_2from the average angle pf the first reference topography C1and the second reference topography C2.

When the work vehicle1reaches the next starting point S1, the controller26controls the work implement13in accordance with the second target design topography70_2in accordance with the abovementioned process of step S105. The controller26then continues the excavation of the actual topography50by repeating the above processes.

In the above examples, the first target design topography70_1is the target design topography70of the first division where the automatic control is started. However, the first target design topography70_1may be the target design topography of another division. That is, the first division signifies the division where work is being performed when the manual introduction occurs and is not limited to the target design topography70of the first division where the automatic control is started.

In the control system3of the work vehicle1according to the present embodiment explained above, the controller26operates the work implement13in accordance with the target design topography70. As a result, when the final design topography60is still in a deep position, excavating by the work implement13is performed in accordance with the target design topography70that is positioned above the final design topography60. As a result, a situation in which the load on the work implement13becomes excessive is suppressed. In addition, the sudden raising or lowering of the work implement13is suppressed. Accordingly, the work vehicle1can be made to perform work efficiently and with a good finish quality.

When a manual operation of the work implement13is introduced by the operator during the automatic control, the controller26corrects the first target design topography70_1in response to the displacement amount L4of the work implement13. The controller26also corrects the target depth L3in response to the displacement amount L4of the work implement13and determines the second target design topography70_2based on the corrected target depth L3′. As a result, the intention of the operator can be reflected in the automatic control.

Although an embodiment of the present invention has been described so far, the present invention is not limited to the above embodiments and various modifications may be made within the scope of the invention.

The work vehicle1is not limited to a bulldozer, and may be another type of work vehicle such as a wheel loader, a motor grader, a hydraulic excavator, or the like.

The work vehicle1may be a vehicle that can be remotely operated. In this case, a portion of the control system3may be disposed outside of the work vehicle1. For example, the controller26may be disposed outside the work vehicle1. The controller may be disposed inside a control center spaced away from the work site. In this case, the work vehicle1may not be provided with the operating cabin14.

The work vehicle1may be driven by an electric motor. In this case, the power source may be disposed outside of the work vehicle1. The internal combustion engine or the engine compartment may not be provided in the work vehicle1in which the power source is supplied from the outside.

The controller26may have a plurality of controllers26separate from each other. For example, as illustrated inFIG.17, the controller26may include a remote controller261disposed outside of the work vehicle1and an on-board controller262mounted in the work vehicle1. The remote controller261and the on-board controller262may be able to communicate wirelessly via communication devices38and39. A portion of the abovementioned functions of the controller26may be executed by the remote controller261, and the remaining functions may be executed by the on-board controller262. For example, the processing for determining the target design topography70may be performed by the remote controller261, and the process for outputting the command signals to the work implement13may be performed by the on-board controller262.

The operating device25aand the input device25bmay also be disposed outside of the work vehicle1. In this case, the operating cabin may be omitted from the work vehicle1. Alternatively, the operating device25aand the input device25bmay be omitted from the work vehicle1.

The actual topography50may be obtained with another device and is not limited to being obtained with the abovementioned positional sensor31. For example, as illustrated inFIG.18, the actual topography50may be obtained with an interface device37that receives data from an external device. The interface device37may wirelessly receive the actual topography data measured by an external measurement device41. Alternatively, the interface device37may be a recording medium reading device and may receive the actual topography data measured by the external measurement device41via a recording medium.

The method for setting the target design topography70is not limited to the method of the above embodiment and may be changed. For example, the target design topography70is determined based on two preceding reference points from the starting point in the above embodiment. However, the target design topography70may be determined based on three or more preceding reference points from the starting point. The controller26may determine the first target design topography70_1based on another parameter without being limited to the target depth. For example, the controller26may determine the first target design topography70_1based on the load on the work implement13, a target angle, a target position, or another parameter. Alternatively, the first target design topography70_1may be determined ahead of time.

The controller26determines the target design topography70based on the average angle between the first reference topography C1and the second reference topography C2in the above embodiment. However, the determination is not limited to the average angle and the controller26may determine the target design topography70by implementing a process such as weighting the angle of the first reference topography C1and the angle of the second reference topography C2.

The controller26determines the second target design topography70_2during the work on the first target design topography70_1and before reaching the next starting position S1in the above embodiment. However, the controller26may determine the second target design topography70_2upon reaching the next starting point S1.

The controller26may determine the target design topography70above the actual topography50. For example, as illustrated inFIG.19, when the operator raises the blade tip position Pb to a position above the actual topography50, the controller26may raise the first target design topography70_1to a position above the actual topography50to match the height of the blade tip position Pb. The controller26may determine the second target design topography70_2so as to be positioned above the actual topography50. Consequently, for example, the material held by the work implement13can be leveled on the actual topography50.

According to the present invention, a work vehicle can be made to perform work efficiently and with a good finish quality with automatic control.