SYSTEM INCLUDING WORK MACHINE, CONTROL METHOD OF WORK MACHINE, AND CONTROLLER OF WORK MACHINE

Description

TECHNICAL FIELD

The present disclosure relates to a system including a work machine, a control method of a work machine, and a controller of a work machine.

BACKGROUND ART

JP 2017 043887 A (Patent Literature 1) discloses a control system of a work machine that determines a loading position with respect to a loading target vehicle on the basis of a loading situation in the loading target vehicle.

CITATION LIST

Patent Literature

Patent Literature 1: JP 2017 043887 A

SUMMARY OF INVENTION

Technical Problem

As one of works by a wheel loader, there is a work of filling material in a stockyard. The material is earth, sand, rock, ore, or the like excavated at a work site or carried into the work site by a carrying machine such as a dump truck.

The work of filling material into a stockyard is performed in the following procedure. The first procedure is to stack the material at the same place a plurality of times by a wheel loader to create a heap of the material. The first procedure is referred to as a stacking work. The second procedure is to create heaps having similar shapes by stacking so as to align the heaps in the front-rear/left-right direction of the heap created by stacking in the stockyard. The third procedure is a work in which the wheel loader ascends a heap while excavating the slope of the aligned heap and stacks the material scooped into the bucket on an upper portion of the heap. The third procedure is referred to as a lift-up work.

In order to efficiently fill a material accumulation site such as a stockyard with material, a heap of material is required to be set to an appropriate size in the stacking work. The present disclosure proposes a technique by which the height of a heap of material formed by the stacking work can be appropriately predicted.

Solution to Problem

A system including a work machine according to an aspect of the present disclosure includes a work machine main body including a travel body, a work implement attached to the work machine main body and including a bucket, and a controller that commands operation of the travel body and the work implement. The controller determines a height of a heap of material formed by the material in the bucket being discharged onto a ground in a state where the travel body is grounded to the ground from a mechanical dimension including a dimension of the work machine main body and a dimension of the work implement.

A control method of a work machine according to an aspect of the present disclosure includes the following steps. The first step is to acquire a mechanical dimension including a dimension of a work machine main body including a travel body and a dimension of a work implement attached to the work machine main body and including a bucket. The second step is to determine a height of a heap of material formed by the material in the bucket being discharged onto a ground in a state where the travel body is grounded to the ground from the mechanical dimension.

The controller of a work machine according to an aspect of the present disclosure acquires a mechanical dimension including a dimension of a work machine main body including a travel body and a dimension of a work implement attached to the work machine main body and including a bucket. The controller determines a height of a heap of material formed by the material in the bucket being discharged onto a ground in a state where the travel body is grounded to the ground from the mechanical dimension.

Advantageous Effects of Invention

According to the present disclosure, the height of a heap of material formed by the stacking work can be appropriately predicted.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a side view of a wheel loader as an example of a work machine.

FIG. 2 is a plan view of the wheel loader illustrated in FIG. 1.

FIG. 3 is a block diagram illustrating a schematic configuration of a control system of the wheel loader.

FIG. 4 is a block diagram illustrating a configuration of an automatic control system of the wheel loader.

FIG. 5 is a view for describing an excavation work by the wheel loader.

FIG. 6 is a view for describing a lift-up work by the wheel loader.

FIG. 7 is a flowchart illustrating a flow of processing of executing the stacking work and the lift-up work by automatic control.

FIG. 8 is a diagram illustrating setting of a stacking target point and a stacking height.

FIG. 9 is a view schematically illustrating the wheel loader that advances toward the stacking target point.

FIG. 10 is a view schematically illustrating the wheel loader during the stacking work.

FIG. 11 is a view schematically illustrating a heap of material formed by the stacking work.

FIG. 12 is a view illustrating setting of a lift-up region and a lifted-up region.

FIG. 13 is a view schematically illustrating the wheel loader during continuing the stacking work.

FIG. 14 is a view schematically illustrating heaps of material at the time of completion of the stacking work.

FIG. 15 is a view schematically illustrating heaps of material at the time of completion of the lift-up work.

DESCRIPTION OF EMBODIMENTS

Hereinafter, an embodiment will be described with reference to the drawings. In the following description, the same parts and components are denoted by the same reference signs. This also applies to their names and functions. Therefore, detailed descriptions thereof will not be repeated. It is also originally planned that any configurations are extracted from the embodiment and are freely combined.

<Overall Configuration of Wheel Loader 1>

In the embodiment, the wheel loader 1 will be described as an example of a work machine. FIG. 1 is a side view of the wheel loader 1 as an example of a work machine. FIG. 2 is a plan view of the wheel loader 1 illustrated in FIG. 1.

As illustrated in FIGS. 1 and 2, the wheel loader 1 mainly includes a vehicle body frame 2, a work implement 3, a travel device 4, and a cab 5. The vehicle body frame 2, the cab 5, and the like form the vehicle body of the wheel loader 1. The work implement 3 and the travel device 4 are attached to the vehicle body of the wheel loader 1. The main body of the wheel loader 1 (work machine main body) includes the vehicle body and the travel device 4.

The travel device 4 causes the vehicle body of the wheel loader 1 to travel, and includes travel wheels 4a and 4b. The wheel loader 1 is a wheeled vehicle including the travel wheels 4a and 4b as traveling rotation bodies on both sides of the vehicle body in a left-right direction. The wheel loader 1 is self-propelled by rotationally driving the travel wheels 4a and 4b, and can perform a desired work using the work implement 3. The travel device 4 corresponds to an example of a “travel body”.

In the present specification, a direction in which the wheel loader 1 travels straight is referred to as a front-rear direction of the wheel loader 1. In the front-rear direction of the wheel loader 1, a side on which the work implement 3 is disposed with respect to the vehicle body frame 2 is defined as a front direction, and a side opposite to the front direction is defined as a rear direction. The left-right direction of the wheel loader 1 is a direction orthogonal to the front-rear direction in a plan view of the wheel loader 1 on a flat ground. The right side and the left side in the left-right direction when viewed in the front direction are the right direction and the left direction, respectively. The vertical direction of the wheel loader 1 is a direction orthogonal to a plane defined by the front-rear direction and the left-right direction. In the vertical direction, the side with the ground is the lower side, and the side with the sky is the upper side.

The vehicle body frame 2 includes a front frame 2a and a rear frame 2b. The front frame 2a is disposed in front of the rear frame 2b. The front frame 2a and the rear frame 2b are attached to each other by a center pin 10 so as to be movable in the left-right direction.

A pair of left and right steering cylinders 11 is attached across the front frame 2a and the rear frame 2b. The steering cylinders 11 are hydraulic cylinders. By the steering cylinders 11 being expanded and contracted by hydraulic oil from a steering pump (not illustrated), the travel direction of the wheel loader 1 is changed to the left and right. The front frame 2a and the rear frame 2b form the vehicle body frame 2 having an articulated structure. The wheel loader 1 is an articulated work machine in which the front frame 2a and the rear frame 2b are coupled to each other so as to be bendable.

The work implement 3 and a pair of the travel wheels (front wheels) 4a are attached to the front frame 2a. The work implement 3 is attached to the front of the vehicle body of the wheel loader 1. The work implement 3 is supported by the vehicle body of the wheel loader 1. Specifically, the work implement 3 is rotatably supported by the vehicle body frame 2, more specifically, the front frame 2a. The work implement 3 is disposed in front of the vehicle body frame 2.

The work implement 3 includes a boom 14. A base end portion of the boom 14 is rotatably attached to the front frame 2a by a boom pin 9. The boom 14 includes a left boom member 14L and a right boom member 14R. The left boom member 14L and the right boom member 14R are joined to each other so as to be unable to relatively move by a joining member that extends in the left-right direction to form the boom 14 having an integrated structure. The boom pin 9 includes a pair of a left boom pin 9L and a right boom pin 9R. The boom 14 is rotatable with respect to the front frame 2a about the left boom pin 9L and the right boom pin 9R. The left boom pin 9L and the right boom pin 9R rotatably support the work implement 3 with respect to the vehicle body frame 2.

The work implement 3 includes a bucket 6. The bucket 6 is disposed at the distal end of the work implement 3. The bucket 6 is a work tool for excavation and loading. A blade edge 6a is a tip portion of the bucket 6. A back surface 6b is a part of the outer surface of the bucket 6. The back surface 6b includes a flat surface. The back surface 6b extends rearward from the blade edge 6a. The bucket 6 is rotatably attached to the boom 14 by a bucket pin 17 located at a distal end of the boom 14. The bucket 6 includes a left boom attachment portion to which the left boom member 14L is attached and a right boom attachment portion to which the right boom member 14R is attached.

The work implement 3 further includes a bell crank 18 and a link 15. A substantially central portion of the bell crank 18 is rotatably supported by the boom 14 by a support pin 18a located substantially at the center of the boom 14 in the longitudinal direction. The link 15 is coupled to a coupling pin 18c included at the lower end (tip portion) of the bell crank 18. The link 15 couples the bell crank 18 and the bucket 6. The bell crank 18 and the link 15 are disposed between the left boom member 14L and the right boom member 14R in the left-right direction.

The front frame 2a and the boom 14 are coupled by a pair of boom cylinders 16. The boom cylinders 16 are hydraulic cylinders. The boom cylinders 16 drive the boom 14 to rotate up and down about the boom pin 9. The base ends of the boom cylinders 16 are attached to the front frame 2a. The distal ends of the boom cylinders 16 are attached to the boom 14. The boom cylinders 16 are hydraulic actuators that move the boom 14 up and down with respect to the front frame 2a. As the boom 14 ascends and descends, the bucket 6 attached to the distal end of the boom 14 also ascends and descends.

A bucket cylinder 19 couples the bell crank 18 and the front frame 2a. The base end of the bucket cylinder 19 is attached to the front frame 2a. The distal end of the bucket cylinder 19 is attached to a coupling pin 18b included at the upper end (base end) of the bell crank 18. The bucket cylinder 19 is a hydraulic actuator that rotates the bucket 6 up and down with respect to the boom 14. The bucket cylinder 19 is a work tool cylinder that drives the bucket 6. The bucket cylinder 19 rotationally drives the bucket 6 around the bucket pin 17. The bucket 6 is formed to be operable with respect to the boom 14. The bucket 6 is formed to be operable with respect to the front frame 2a.

The boom cylinders 16 and the bucket cylinder 19 form a work implement actuator that drives the work implement 3.

The cab 5 on which the operator boards and a pair of the travel wheels (rear wheels) 4b are attached to the rear frame 2b. The box-shaped cab 5 is disposed behind the boom 14. The cab 5 is mounted on the rear frame 2b. The cab 5 is placed on the vehicle body frame 2. In the cab 5, a seat on which the operator of the wheel loader 1 sits, an operation device 8 to be described below, and the like are disposed.

A perception device 111 is included on the cab 5. The perception device 111 is disposed, for example, on a ceiling of the cab 5. The perception device 111 is mounted on, for example, an upper surface of the cab 5. The perception device 111 is disposed, for example, on a front portion of the cab 5. The perception device 111 is attached to the cab 5 facing forward, for example, and can acquire information of the front of the cab 5. Details of the perception device 111 will be described below.

A length L1 illustrated in FIG. 1 is a length (wheelbase length) from the center of the front wheel 4a to the center of the rear wheel 4b in the front-rear direction. A length L2 is a length (rear overhang length) from the center of the rear wheel 4b to the rear end of the vehicle body in the front-rear direction. A length L3 is a diameter (tire diameter) of the rear wheel 4b, and is a length from a ground G to the center of the rear wheel 4b in the vertical direction. A length L4 is a length from the center of the front wheel 4a to the center of the boom pin 9 in the front-rear direction. A length L5 is a length from the ground G to the center of the boom pin 9 in the vertical direction. A length L6 is a length (bucket length) from the center of the bucket pin 17 to the blade edge 6a of the bucket 6. A length L7 is a length (boom length) from the center of the boom pin 9 to the center of the bucket pin 17.

An angle α illustrated in FIG. 1 is an angle (boom angle) formed by a boom reference line A that is a straight line that passes through the center of the boom pin 9 and the center of the bucket pin 17, and a horizontal line H that extends forward from the center of the boom pin 9. In a case where the boom reference line A is horizontal, the angle α=0° is defined. In a case where the boom reference line A is above the horizontal line H, the angle α is positive. In a case where the boom reference line A is below the horizontal line H, the angle α is negative.

An angle β is an angle (bell crank angle) formed by the boom reference line A and a bell crank reference line B that is a straight line that passes through the center of the support pin 18a and the center of the coupling pin 18b. In a case where the back surface 6b of the bucket 6 is horizontal on the ground in a state where the bucket 6 is grounded, the angle β=0° is defined. In a case where the bucket 6 is moved in the excavation direction (upward), the angle β is positive. In a case where the bucket 6 is moved in the dumping direction (downward), the angle β is negative.

An angle γ is an angle (departure angle) of the rear lower portion of the vehicle body. The angle γ (departure angle) is an angle formed by the ground G and a departure-angle defining line that is a straight line that connects the grounding portion where the rear wheel 4b is grounded to the ground G and the lower surface of the rear end of the vehicle body. The departure-angle defining line is a line that defines the angle γ (departure angle).

A length L8 illustrated in FIG. 2 is a length (distance between boom pins) from the left boom pin 9L to the right boom pin 9R in the left-right direction. The length L9 is a length (bucket width) from the left end to the right end of the bucket 6 in the left-right direction.

The lengths L1 to L5 and L8 illustrated in FIGS. 1 and 2 are included in the dimension of the work machine main body. The lengths L6, L7, and L9 illustrated in FIGS. 1 and 2 are included in the dimension of the work implement 3. The lengths L1 to L9 and the angles α, β, and γ are included in the mechanical dimension including the dimension of the work machine main body and the dimension of the work implement 3. The lengths L1 to L9 and the angle γ are values unique to each individual of the wheel loader 1, and are stored in a vehicle body controller 50 to be described below. The angles α and β vary depending on the posture of the work implement 3, and are obtained on the basis of detection results of a boom angle sensor 123 and a bucket angle sensor 124 to be described below.

<System Configuration>

FIG. 3 is a block diagram illustrating a schematic configuration of a control system that controls the wheel loader 1.

An engine 21 is a driving source that generates a driving force for driving the work implement 3 and the travel device 4, and is, for example, a diesel engine. As the driving source, instead of the engine 21, a motor driven by a power storage body may be used, or both the engine and the motor may be used. The output of the engine 21 is controlled by adjusting the amount of fuel injected into the cylinder of the engine 21.

The driving force generated by the engine 21 is transmitted to a transmission 23. The transmission 23 shifts the driving force to an appropriate torque and rotational speed. An axle 25 is connected to an output shaft of the transmission 23. The driving force shifted by the transmission 23 is transmitted to the axle 25. The driving force is transmitted from the axle 25 to the travel wheels 4a and 4b (FIGS. 1 and 2). Thus, the wheel loader 1 travels. In the wheel loader 1 of the embodiment, both the travel wheel 4a and the travel wheel 4b form driving wheels that receive a driving force and cause the wheel loader 1 to travel.

A part of the driving force of the engine 21 is transmitted to a work implement pump 13. The work implement pump 13 is a hydraulic pump that is driven by the engine 21 and operates the work implement 3 by discharged hydraulic oil. The work implement 3 is driven by hydraulic oil from the work implement pump 13. The hydraulic oil discharged from the work implement pump 13 is supplied to the boom cylinders 16 and the bucket cylinder 19 via a main valve 32. When the boom cylinders 16 expand and contract by receiving the supply of the hydraulic oil, the boom 14 moves up and down. When the bucket cylinder 19 receives the supply of the hydraulic oil and expands and contracts, the bucket 6 rotates up and down.

The wheel loader 1 includes the vehicle body controller 50. The vehicle body controller 50 includes an engine controller 60, a transmission controller 70, and a work implement controller 80.

The vehicle body controller 50 is generally implemented by reading various programs by a central processing unit (CPU). The vehicle body controller 50 includes a memory (not illustrated). The memory functions as a work memory and stores various programs for implementing the function of the wheel loader 1.

The operation device 8 is included in the cab 5. The operation device 8 is operated by the operator. The operation device 8 includes a plurality of types of operation members operated by the operator to operate the wheel loader 1. The operation device 8 includes an accelerator pedal 41 and a work implement operation lever 42. The operation device 8 may include a steering wheel, a shift lever, and the like (not illustrated).

The accelerator pedal 41 is operated to set a target rotation speed of the engine 21. The engine controller 60 controls the output of the engine 21 on the basis of the operation amount of the accelerator pedal 41. When the operation amount (depression amount) of the accelerator pedal 41 is increased, the output of the engine 21 is increased. When the operation amount of the accelerator pedal 41 is reduced, the output of the engine 21 is reduced. The transmission controller 70 controls the transmission 23 on the basis of the operation amount of the accelerator pedal 41.

The work implement operation lever 42 is operated to operate the work implement 3. The work implement controller 80 controls electromagnetic proportional control valves 35 and 36 on the basis of the operation amount of the work implement operation lever 42.

The electromagnetic proportional control valve 35 contracts the bucket cylinder 19 to switch the main valve 32 such that the bucket 6 moves in the dumping direction (the direction in which the blade edge of the bucket 6 is lowered). Furthermore, the electromagnetic proportional control valve 35 extends the bucket cylinder 19 to switch the main valve 32 such that the bucket 6 moves in the tilting direction (the direction in which the blade edge of the bucket 6 is raised). The electromagnetic proportional control valve 36 contracts the boom cylinders 16 to switch the main valve 32 such that the boom 14 is lowered. Furthermore, the electromagnetic proportional control valve 36 extends the boom cylinders 16 to switch the main valve 32 such that the boom 14 is raised.

A machine monitor 51 receives input of a command signal from the vehicle body controller 50 and displays various types of information. The various types of information displayed on the machine monitor 51 may be, for example, information regarding a work executed by the wheel loader 1, vehicle body information such as a remaining amount of fuel, a cooling water temperature, and a hydraulic oil temperature, a peripheral image obtained by imaging the periphery of the wheel loader 1, and the like. The machine monitor 51 may be a touch panel, and in this case, a signal generated by the operator touching a part of the machine monitor 51 is output from the machine monitor 51 to the vehicle body controller 50.

<Automatic Control System of Wheel Loader 1>

In automating a work of the wheel loader 1, an operation of a skilled operator is desirably reproduced by automatic control. FIG. 4 is a block diagram illustrating a configuration of an automatic control system of the wheel loader 1.

An automation controller 100 is formed to be able to transmit and receive signals to and from the vehicle body controller 50 described with reference to FIG. 3. The automation controller 100 is also formed to be able to transmit and receive signals to and from an external information acquisition unit 110. The external information acquisition unit 110 includes the perception device 111 and a position information acquisition device 112. The perception device 111 and the position information acquisition device 112 are mounted on the wheel loader 1.

The perception device 111 acquires information of the surroundings of the wheel loader 1. The perception device 111 is attached to a front portion of the upper surface of the cab 5, for example. The perception device 111 corresponds to an example of an “object sensor” that detects an object around the main body of the wheel loader 1 (work machine main body).

The perception device 111 detects a direction of an object outside the wheel loader 1 and a distance to the object in a non-contact manner. The perception device 111 is, for example, a light detection and ranging (LiDAR) that emits laser light and acquires information of an object. The perception device 111 may be a visual sensor including a camera. The perception device 111 may be a radio detection and ranging (Radar) that acquires information of an object by emitting radio waves. The perception device 111 may be an infrared sensor.

The position information acquisition device 112 acquires information of the current position of the wheel loader 1. The position information acquisition device 112 acquires position information of the wheel loader 1 in a global coordinate system with reference to the earth using, for example, a satellite positioning system. The position information acquisition device 112 uses, for example, global navigation satellite systems (GNSS), and includes a GNSS receiver. The satellite positioning system calculates the position of the antenna of the GNSS receiver from a positioning signal received by the GNSS receiver from a satellite to calculate the position of the wheel loader 1.

External information of the wheel loader 1 by the perception device 111 and the position information of the wheel loader 1 by the position information acquisition device 112 are input to the automation controller 100.

The vehicle body controller 50 is formed to be able to transmit and receive signals to and from a vehicle information acquisition unit 120, and receives input of information of the wheel loader 1 acquired by the vehicle information acquisition unit 120. The vehicle information acquisition unit 120 includes various sensors mounted on the wheel loader 1. The vehicle information acquisition unit 120 includes an articulation angle sensor 121, a vehicle speed sensor 122, the boom angle sensor 123, the bucket angle sensor 124, and a boom cylinder pressure sensor 125.

The articulation angle sensor 121 detects an articulation angle that is an angle formed by the front frame 2a and the rear frame 2b, and generates a signal of the detected articulation angle. The articulation angle sensor 121 outputs the signal of the articulation angle to the vehicle body controller 50.

The vehicle speed sensor 122 detects the moving speed of the wheel loader 1 by the travel device 4, for example, by detecting the rotation speed of the output shaft of the transmission 23, and generates a signal of the detected vehicle speed. The vehicle speed sensor 122 outputs the signal of the vehicle speed to the vehicle body controller 50. The vehicle speed sensor 122 corresponds to an example of a travel sensor that detects a traveling status of the travel device 4 (travel body).

The boom angle sensor 123 includes, for example, a rotary encoder included in the boom pin 9 that is an attachment portion of the boom 14 to the vehicle body frame 2. The boom angle sensor 123 detects an angle of the boom 14 with respect to the horizontal direction (angle α (boom angle) in FIG. 1), and generates a signal indicating the detected angle of the boom 14. The boom angle sensor 123 outputs the signal of the angle of the boom 14 to the vehicle body controller 50.

The bucket angle sensor 124 includes, for example, a rotary encoder included in the support pin 18a that is a rotation shaft of the bell crank 18. The bucket angle sensor 124 detects an angle of the bell crank 18 with respect to the boom 14 (angle β (bell crank angle) illustrated in FIG. 1), and generates a signal of the detected angle of the bell crank 18. The vehicle information acquisition unit 120 or the vehicle body controller 50 calculates an angle of the bucket 6 (bucket angle) with respect to the boom 14 from the detected angle of the bell crank 18. The bucket angle is an angle formed by a straight line that passes through the center of the bucket pin 17 and the blade edge 6a of the bucket 6 and the boom reference line A.

The boom angle sensor 123 and the bucket angle sensor 124 correspond to an example of a work implement posture sensor that detects the posture of the work implement 3. The boom angle sensor 123 may be a stroke sensor disposed on the boom cylinder 16. The bucket angle sensor 124 may be a potentiometer or a proximity switch attached to the bucket pin 17, or may be a stroke sensor disposed on the bucket cylinder 19.

The boom cylinder pressure sensor 125 detects pressure on the bottom side (boom bottom pressure) of the boom cylinder 16, and generates a signal of the detected boom bottom pressure. The boom bottom pressure increases in a case where a load is loaded on the bucket 6, and decreases in a case where the load is empty. The boom cylinder pressure sensor 125 outputs the signal of the boom bottom pressure to the vehicle body controller 50.

The vehicle body controller 50 outputs information input from the vehicle information acquisition unit 120 to the automation controller 100. The automation controller 100 receives detection values of the vehicle speed sensor 122, the boom angle sensor 123, and the bucket angle sensor 124 via the vehicle body controller 50.

An actuator 140 is formed to be able to transmit and receive signals to and from the vehicle body controller 50. The actuator 140 is driven upon receiving a command signal from the vehicle body controller 50. The actuator 140 includes a brake electromagnetic proportional control valve (EPC) 141 for operating the brake of the travel device 4, a steering EPC 142 for adjusting the traveling direction of the wheel loader 1, a work implement EPC 143 for operating the work implement 3, and a hydraulic mechanical transmission (HMT) 144.

The electromagnetic proportional control valves 35 and 36 illustrated in FIG. 3 form the work implement EPC 143. The transmission 23 illustrated in FIG. 3 is implemented as the HMT 144 utilizing electronic control. The transmission 23 may be a hydro-static transmission (HST). A power transmission device that transmits power from the engine 21 to the travel wheels 4a and 4b may include an electric drive device of a diesel electric type or the like, or may include any combination of the HMT, the HST, and the electric drive device.

The transmission controller 70 includes a brake control unit 71 and an accelerator control unit 72. The brake control unit 71 outputs a command signal for controlling the operation of the brake to the brake EPC 141. The accelerator control unit 72 outputs a command signal for controlling the vehicle speed to the HMT 144.

The work implement controller 80 includes a steering control unit 81 and a work implement control unit 82. The steering control unit 81 outputs a command signal for controlling the traveling direction of the wheel loader 1 to the steering EPC 142. The work implement control unit 82 outputs a command signal for controlling the operation of the work implement 3 to the work implement EPC 143.

The automation controller 100 includes a position estimation unit 101, a path planning unit 102, and a path follow-up control unit 103.

The position estimation unit 101 estimates the self-position of the wheel loader 1 on the basis of the position information acquired by the position information acquisition device 112. Furthermore, the position estimation unit 101 recognizes the target position on the basis of the external information acquired by the perception device 111. The target position is, for example, a position of a target point (to be described below) set on the ground G, or a position of a heap of material formed by the material in the bucket 6 being discharged onto the ground. The perception device 111 may recognize and input the target position to the automation controller 100, and the position estimation unit 101 may recognize the target position on the basis of the detection result detected by the perception device 111.

The path planning unit 102 generates an optimum path of the wheel loader 1 in a case where the wheel loader 1 is automatically controlled. The optimum path includes a path of traveling by the travel device 4 and a path of operation of the work implement 3. For example, the path planning unit 102 generates an optimum path of a path of traveling of the travel device 4 that linearly advances toward the target point and a path of operation of the work implement 3 that discharges material in the bucket 6 to the target point in the stacking work of stacking the material a plurality of times at the same target point to form a heap of the material. The path planning unit 102 also generates an optimum path of a path of traveling of the travel device 4 that advances toward a heap of material and ascends the heap of the material and a path of operation of the work implement 3 that excavates the slope of the heap of the material and stacks the material scooped up in the bucket 6 on the upper portion of the heap in the lift-up work.

The path follow-up control unit 103 commands operation of the travel device 4 and the work implement 3. The path follow-up control unit 103 controls the accelerator, the brake, and the steering such that the wheel loader 1 travels following the optimum path generated by the path planning unit 102. A command signal for causing the wheel loader 1 to travel along the optimum path is output from the path follow-up control unit 103 to the brake control unit 71, the accelerator control unit 72, and the steering control unit 81. The path follow-up control unit 103 controls the boom cylinders 16 and the bucket cylinder 19 such that the work implement 3 operates along the optimum path generated by the path planning unit 102. A command signal for moving the work implement 3 along the optimum path is output from the path follow-up control unit 103 to the work implement control unit 82.

An interface 130 is formed to be able to transmit and receive signals to and from the vehicle body controller 50. The interface 130 includes an automation switching switch 131, an engine emergency stop switch 132, and a mode lamp 133.

The automation switching switch 131 is operated by the operator. The operator operates the automation switching switch 131 to switch between manually operating the wheel loader 1 and automatically controlling the wheel loader 1. The engine emergency stop switch 132 is operated by the operator. In a case where an event that requires emergency stop of the engine 21 occurs, the operator operates the engine emergency stop switch 132. Operation signals of the automation switching switch 131 and the engine emergency stop switch 132 are input to the vehicle body controller 50.

The mode lamp 133 displays whether the wheel loader 1 is currently in a mode of being manually operated by the operator or in a mode of being automatically controlled. A command signal for controlling lighting of the lamp is output from the vehicle body controller 50 to the mode lamp 133.

<Excavation Work>

The wheel loader 1 of the embodiment executes an excavation work of scooping material such as earth and sand into the bucket 6. FIG. 5 is a view for describing the excavation work by the wheel loader 1.

As illustrated in FIG. 5, the wheel loader 1 travels forward toward material 200 such as earth and sand. The wheel loader 1 pushes the bucket 6 into the material 200 and raises the bucket 6 while applying a traction force in the forward direction in a state where the blade edge 6a of the bucket 6 bites into the material 200. The bucket 6 operates as indicated by a bucket trajectory BL indicated by a curved arrow in FIG. 5. As a result, the excavation work of scooping the material 200 into the bucket 6 is executed.

The wheel loader 1 executes the stacking work of discharging the scooped material 200 in the bucket 6 to the same place on the ground G a plurality of times in a state where both the front wheels 4a and the rear wheels 4b of the travel device 4 are grounded to the ground G to form a heap of the material 200 on the ground G.

<Lift-Up Work>

The wheel loader 1 of the embodiment executes the lift-up work of ascending a slope of a heap of the material 200 upward while excavating the slope of the heap formed by the stacked material 200 by the bucket 6, and stacking new material 200 on an upper portion of the slope of the heap of the material 200. FIG. 6 is a view for describing the lift-up work by the wheel loader 1.

As illustrated in FIG. 6, the wheel loader 1 travels forward toward a heap of the material 200. The bucket 6 is raised in a state where the blade edge 6a of the bucket 6 bites into the material 200. At this time, the wheel loader 1 continues the forward travel, and the wheel loader 1 travels so as to ascend to the middle of the heap while excavating the heap of the material 200 by the bucket 6. The bucket 6 operates as indicated by the bucket trajectory BL indicated by a curved arrow in FIG. 6. When the bucket 6 reaches the upper portion of the heap, the wheel loader 1 causes the bucket 6 to perform a dumping motion to discharge the material 200 in the bucket 6 from the bucket 6. As a result, the lift-up work of stacking the material 200 scooped into the bucket 6 on the upper portion of the heap is executed.

<Automatic Control of Stacking/Lift-Up Work>

FIG. 7 is a flowchart illustrating a flow of processing of executing the stacking work and the lift-up work by automatic control. Automatic control of the stacking work and the lift-up work will be described with reference to FIG. 7 and subsequent FIGS. 8 to 15 as appropriate.

First, in step S1, the path planning unit 102 of the automation controller 100 sets a stacking target point O on the ground G. The stacking target point O may be set on the ground G in a stockyard, for example, for the stacking work into the stockyard. Alternatively, the stacking target point O may be set to a vacant land.

In step S2, the path planning unit 102 determines a stacking height H1. FIG. 8 is a diagram illustrating setting of the stacking target point O and the stacking height H1. A peak P of the heap of the material 200 formed by the stacking work is set straight above the stacking target point O. The stacking height H1 is a distance from the ground G to the peak P. An angle θ illustrated in FIG. 8 is the angle of repose of the material 200. The path planning unit 102 determines the peak P at which the stacking height H1 is the maximum from the mechanical dimension of the wheel loader 1.

Specifically, the angle of repose θ of the material 200 varies depending on the material and the state of the material 200. If the angle of repose θ of the material is small, the peak P needs to be set at a position farther away from the vehicle body of the wheel loader 1 in order to prevent the heap of the material 200 from interfering with the front wheels 4a, and the stacking height H1 at this time is relatively small. If the angle of repose θ of the material is large, the heap of the material 200 is less likely to collapse spontaneously, and thus the peak P can be set to a position closer to and higher than the vehicle body of the wheel loader 1, and the stacking height H1 is relatively large.

The path planning unit 102 calculates a region where the blade edge 6a of the bucket 6 can be disposed with respect to the work machine main body from the mechanical dimension of the wheel loader 1. Specifically, the path planning unit 102 calculates a region in which the blade edge 6a of the bucket 6 can be disposed with respect to the work machine main body from the length L5 indicating the height of the boom pin 9, the dimension of the work implement 3 (the length L6 (bucket length) and the length L7 (boom length)), the angle of the boom 14 that can be taken with respect to the work machine main body (boom angle, angle α), and the angle of the bucket 6 that can be taken with respect to the boom 14 (bucket angle) illustrated in FIG. 1. The boom pin 9 is an attachment position of the boom 14 to the work machine main body. The dimension of the work implement 3 includes the length from the boom pin 9 to the blade edge 6a of the bucket 6.

As described above, the lengths L5 to L7 are stored in the vehicle body controller 50. The boom angle and the bucket angle are obtained from detection results of the boom angle sensor 123 and the bucket angle sensor 124.

The path planning unit 102 determines the peak P at which the stacking height H1 can be maximized in a state where the front wheels 4a and the rear wheels 4b are grounded to the ground G from the mechanical dimension of the wheel loader 1 and the angle of repose θ of the material. The path planning unit 102 calculates the position of the blade edge 6a that satisfies a condition that the heap of the material 200 to be formed does not interfere with the front wheels 4a in a case where the material 200 is discharged from the bucket 6 in a state where the blade edge 6a of the bucket 6 is disposed at each position in a region where the blade edge 6a of the bucket 6 can be disposed with respect to the work machine main body. The path planning unit 102 determines the position of the blade edge 6a at the farthest and highest position from the ground G among calculated positions of the blade edge 6a. The path planning unit 102 sets the highest position of the blade edge 6a as the peak P of the heap of the material 200 formed by the stacking work.

The path planning unit 102 determines the peak P at which the stacking height H1 can be the highest, and determines the stacking height H1 corresponding to the peak P. The path planning unit 102 sets the height of the heap of the material 200 formed by the stacking work as the stacking height H1. The path planning unit 102 determines the positions of the travel device 4 and the work implement 3 in a case where a heap of the material 200 having the peak P and the stacking height H1 is formed, and generates an optimum path of the wheel loader 1 toward the positions.

The angle of repose θ of the material may be input by the operator via the interface 130 and stored in the vehicle body controller 50. The path planning unit 102 of the automation controller 100 may appropriately read the angle of repose θ stored in the vehicle body controller 50 and use the angle of repose θ for other calculations including calculation of the stacking height H1, calculation of a lift-up height H2 to be described below, and the like. Alternatively, the path planning unit 102 may recognize the material and the state of the material 200 by collating information of the material 200 in front of the vehicle body detected by the perception device 111 with a database stored in the automation controller 100 or the vehicle body controller 50, and determine the angle of repose θ.

Returning to FIG. 7, in step S3, the path follow-up control unit 103 of the automation controller 100 causes the wheel loader 1 to operate following the optimum path so as to execute the stacking work along the straight line that passes through the stacking target point O.

FIG. 9 is a view schematically illustrating the wheel loader 1 that advances toward the stacking target point O. A center line CL illustrated in FIG. 9 is a center line of the wheel loader 1 in the left-right direction. The center line CL is a straight line. The stacking target point O is on the center line CL. The center line CL illustrated in FIG. 9 is an example of a straight line that passes through the stacking target point O. The wheel loader 1 travels straight along the center line CL and advances toward the stacking target point O. In the wheel loader 1 that advances toward the stacking target point O, the material 200 is mounted on the bucket 6.

FIG. 10 is a view schematically illustrating the wheel loader 1 during the stacking work. In FIG. 10 and subsequent FIGS. 11,13, and 15, only the front frame 2a, the rear frame 2b, the front wheel 4a, the rear wheel 4b, the bucket 6, and the boom 14 are representatively illustrated in the configurations of the wheel loader 1 illustrated in FIGS. 1 and 2.

The path follow-up control unit 103 of the automation controller 100 linearly advances the wheel loader 1 along the center line CL illustrated in FIG. 9 to approach the stacking target point O. When the blade edge 6a of the bucket 6 reaches above the stacking target point O (that is, above the peak P), the path follow-up control unit 103 causes the bucket 6 to perform a dumping motion to discharge the material 200 in the bucket 6 onto the ground G. As a result, a heap of the material 200 is formed on the ground G. By the discharge of the material 200 being repeated a plurality of times, a heap of the material 200 having the stacking height H1 is formed. In the middle of the stacking work illustrated in FIG. 10, the peak of the heap of the material 200 is at a position lower than the peak P determined in step S2 (closer to the ground G).

Returning to FIG. 7, in step S4, whether the height of the heap of the material 200 has reached the stacking height H1 is determined. The perception device 111 detects the heap of the material 200. The perception device 111 detects the shape of the current heap of the material 200. The detection result detected by the perception device 111 is input to the position estimation unit 101 of the automation controller 100. The position estimation unit 101 recognizes the current height of the heap from the shape of the heap of the material 200 detected by the perception device 111. The current height of the heap of the material 200 is equal to or less than the stacking height H1.

The automation controller 100 compares the current height of the heap of the material 200 with the stacking height H1 determined in step S2. If it is determined that the current height is lower than the stacking height H1, it is determined that the height of the heap of the material 200 has not reached the stacking height H1 (NO in step S4). In that case, the processing returns to step S3, and the stacking work is continued.

FIG. 11 is a view schematically illustrating a heap of the material 200 formed by the stacking work. FIG. 11 illustrates a state after the path follow-up control unit 103 of the automation controller 100 controls the travel device 4 and the work implement 3 such that the material 200 is discharged to the stacking target point O a plurality of times. The height of the heap of the material 200 illustrated in FIG. 11 reaches the stacking height H1. At this time, the automation controller 100 determines that the current height of the heap of the material 200 reaches the stacking height H1 (YES in step S4), and ends the stacking work.

In step S5, the path planning unit 102 of the automation controller 100 determines the lift-up height H2. FIG. 12 is a view illustrating setting of a lift-up region V1 and a lifted-up region V2. The lift-up height H2 is a distance from the ground G to a peak Q of a heap of the material 200 after being formed by the lift-up work. The peak Q is at a position higher than the peak P.

The lift-up work is work in which the wheel loader 1 ascends the heap of the material 200 while excavating the heap of the material 200 by the bucket 6. As the wheel loader 1 ascends the heap, the vehicle body of the wheel loader 1 is inclined such that the front of the wheel loader 1 faces upward. The wheel loader 1 can ascend a slope by inclining the vehicle body to an angle at which the vehicle body comes into contact with the ground G.

The path planning unit 102 of the automation controller 100 determines the lift-up height H2 from the mechanical dimension of the wheel loader 1. The path planning unit 102 determines a range in which the vehicle body of the wheel loader 1 can be inclined without the lower surface of the rear end of the rear frame 2b of the wheel loader 1 contacting the ground G in a case where the wheel loader 1 ascends the slope of the heap of the material 200 from the wheelbase length (length L1, FIG. 1), the rear overhang length (length L2, FIG. 1), and the departure angle (angle γ, FIG. 1).

The path planning unit 102 sets a virtual straight line VL1 parallel to a slope that extends from the peak P of the heap of the material 200 in the lower right direction in FIG. 12. The virtual straight line VL1 illustrated in FIG. 12 corresponds to an example of a slope of a heap of the material 200 after being formed by the lift-up work. Furthermore, the path planning unit 102 sets a virtual straight line VL2 obtained by extending a slope that extends from the peak P of the heap of the material 200 in the lower left direction in FIG. 12 in the upper right direction of the peak P. The virtual straight lines VL1 and VL2 are indicated by broken lines in FIG. 12.

The path planning unit 102 calculates the posture of the wheel loader 1 capable of ascending the slope of the heap of the material 200 along the virtual straight line VL1 and disposing the blade edge 6a of the bucket 6 on the virtual straight line VL2 without bringing the lower surface of the rear end of the rear frame 2b into contact with the ground G. The path planning unit 102 calculates at least one, preferably a plurality of, preferably all possible postures of the wheel loader 1.

The path planning unit 102 calculates the posture of the wheel loader 1 in which the slope of the heap of the material 200 can be ascended along the virtual straight line VL1 and the blade edge 6a of the bucket 6 can be disposed on the virtual straight line VL2 from the length L1 indicating the wheelbase length, the length L2 indicating the rear overhang length, the length L5 indicating the height of the boom pin 9, the dimension of the work implement 3 (the length L6 (bucket length) and the length L7 (boom length)), the angle of the boom 14 that can be taken with respect to the work machine main body (boom angle, angle α), the angle of the bucket 6 that can be taken with respect to the boom 14 (bucket angle), and the angle γ indicating the departure angle illustrated in FIG. 1. The boom pin 9 is an attachment position of the boom 14 to the work machine main body. The dimension of the work implement 3 includes the length from the boom pin 9 to the blade edge 6a of the bucket 6.

As described above, the lengths L1 to L2 and L5 to L7 and the angle γ are stored in the vehicle body controller 50. The boom angle and the bucket angle are obtained from detection results of the boom angle sensor 123 and the bucket angle sensor 124.

The path planning unit 102 determines the position of the blade edge 6a at the farthest and highest position from the ground G in the range in which the blade edge 6a of the bucket 6 can be disposed on the virtual straight line VL2. The path planning unit 102 sets the highest position of the blade edge 6a as the peak Q of the heap of the material 200 formed by the lift-up work. The path planning unit 102 determines the peak Q having the highest lift-up height H2, determines the virtual straight line VL1 corresponding to the peak Q as a slope of a heap formed by the material 200, and determines the lift-up height H2 corresponding to the peak Q. The path planning unit 102 sets the height of the material 200 formed by the lift-up work as the lift-up height H2.

The path planning unit 102 determines the positions of the travel device 4 and the work implement 3 in a case where a heap of the material 200 having the peak Q and the lift-up height H2 is formed, and generates an optimum path of the wheel loader 1 toward the positions. The path planning unit 102 sets the peak Q of the heap of the material 200 as a target position, and generates an optimum path so as to cause the travel device 4 to travel forward to cause the wheel loader 1 to ascend a slope while scooping the material 200 into the bucket 6. When the blade edge 6a of the bucket 6 reaches the position of the peak Q of the heap that is the target position, the path planning unit 102 generates an optimum path so as to cause the bucket 6 to perform a dump motion to discharge the material 200 in the bucket 6 and to stack the material 200 on the upper portion of the slope of the heap of the material 200.

Returning to FIG. 7, in step S6, the path planning unit 102 calculates the lift-up region V1. Referring again to FIG. 12, the path planning unit 102 sets a virtual plane that passes through the peak P of the heap of the material 200 formed by the stacking work and extends parallel to the ground G, typically horizontally. An angle formed by the virtual plane and the virtual straight line VL1 that extends from the peak Q of the heap of the material 200 formed by the lift-up work in the lower right direction in FIG. 12 is the angle of repose θ. Therefore, a triangle indicated by a broken line in FIG. 12 including the peak P and the peak Q as two peaks is an isosceles triangle because both base angles are the angle of repose θ and are equal. The base of the isosceles triangle extends in the left-right direction in FIG. 12, and a length of the base is a side length SL1. The path planning unit 102 sets a region surrounded by the isosceles triangle as the lift-up region V1.

The height of the isosceles triangle illustrated in FIG. 12 is a difference between the lift-up height H2 and the stacking height H1. The two equal sides of the isosceles triangle are determined by the angle of repose θ of the material 200, and the base of the isosceles triangle that connects the two equal sides is determined. The length of the base of the isosceles triangle is the side length SL1. The area of the isosceles triangle is calculated from the stacking height H1, the lift-up height H2, and the side length SL1 determined from the angle of repose θ of the material 200.

The heap formed by the lift-up work (and the stacking work) has a three-dimensional shape and has a width in a perpendicular direction on the paper surface in FIG. 12. Therefore, the volume of the material 200 is determined for the material 200 stacked on the lift-up region V1 by the lift-up work. The volume of the material 200 stacked on the lift-up region V1 is also referred to as a stacking volume. For example, assuming that the material 200 having the same width is stacked in the perpendicular direction on the paper surface of FIG. 12 by the lift-up work, and assuming that the width of the material 200 is equal to the width of the bucket 6, the stacking volume can be calculated by multiplying the area of the isosceles triangle illustrated in FIG. 12 by the length L9 (FIG. 2) indicating the bucket width.

Returning to FIG. 7, in step S7, the path planning unit 102 calculates the lifted-up region V2 and sets a virtual plane VP. The lifted-up region V2 is a region where the material 200 to be carried to the lift-up region V1 by the lift-up work is stacked. The path planning unit 102 calculates the lifted-up region V2 on the basis of the stacking volume such that the stacking volume that is the volume of the lift-up region V1 and the lifted-up region V2 are equal in volume. The path planning unit 102 sets the virtual plane VP that forms a part of the boundary of the lifted-up region V2.

Referring to FIG. 12 again, the virtual straight line VL1 that extends in the lower right direction in FIG. 12 from the peak Q of the heap of the material 200 formed by the lift-up work and is set in step S6 corresponds to the slope of the heap of the material 200 after the end of the lift-up work. The path planning unit 102 sets a region surrounded by the slope of the heap, the virtual plane VP that is a plane that extends in parallel with the virtual straight line VL1 and extends in the perpendicular direction on the paper surface of FIG. 12, the ground G, and a plane that extends in parallel with the ground G and passes through the peak P as the lifted-up region V2. The path planning unit 102 sets the lifted-up region V2 along the slope of the heap of the material 200 after the end of the lift-up work. The path planning unit 102 sets the lifted-up region V2 outside the heap of the material 200 after the end of the lift-up work. The angle that is formed by the virtual plane VP and the ground G and is an acute angle is the angle of repose θ.

A quadrangle that sets the lifted-up region V2 illustrated in FIG. 12 is a parallelogram. The upper side of the parallelogram extends in the left-right direction in FIG. 12, and the length of the upper side (and the lower side) is a side length SL2. The height of the parallelogram is the stacking height H1. The lifted-up region V2 has a quadrangular prism shape having the parallelogram as the bottom surface. A side having the side length SL1 and a side having the side length SL2 illustrated in FIG. 12 are on a straight line. The bottom surface of the lift-up region V1 and the top surface of the lifted-up region V2 are on the same plane.

Since the volume of the lift-up region V1 is equal to the volume of the lifted-up region V2, assuming that the width of the material 200 in the perpendicular direction on the paper surface of FIG. 12 is equal between the lift-up region V1 and the lifted-up region V2, the area of the isosceles triangle illustrated in FIG. 12 is equal to the area of the parallelogram illustrated in FIG. 12. Therefore, the side length SL2 can be calculated by the following Formula 1.

SL ⁢ 1 * ( H ⁢ 2 - H ⁢ 1 ) / 2 = SL ⁢ 2 * H ⁢ 1 ( Formula ⁢ 1 )

The height of the lifted-up region V2 is not necessarily the stacking height H1. The shape of the lifted-up region V2 is not limited to a quadrangular prism. The lifted-up region V2 may have any shape as long as the volume of the lifted-up region V2 is equal to the volume of the lift-up region V1. The entire lifted-up region V2 may be set at a position lower in height than the peak P. The width of the lift-up region V1 and the width of the lifted-up region V2 in the perpendicular direction on the paper surface of FIG. 12 may be different from each other.

Returning to FIG. 7, in step S8, the automation controller 100 continues the stacking work. FIG. 13 is a view schematically illustrating the wheel loader 1 during continuing the stacking work. The path planning unit 102 sets a next target point on the ground G behind the stacking target point O set in step S1 (rear side of the wheel loader 1 in the front-rear direction. Right side in FIG. 13). The path planning unit 102 determines a point straight above the next target point and having the same height as the peak P set in step S2 as the peak of the next heap. The path planning unit 102 determines the positions of the travel device 4 and the work implement 3 in a case where the next heap is formed, and generates an optimum path of the wheel loader 1 toward the positions.

The path follow-up control unit 103 causes the wheel loader 1 to operate following the newly generated optimum path, thereby executing the stacking work of the next heap. The path follow-up control unit 103 repeatedly executes the stacking work of a plurality of heaps. FIG. 13 illustrates a state in which three heaps are formed behind the heap of the material 200 formed by the first stacking work.

Returning to FIG. 7, in step S9, the automation controller 100 determines whether the inside of the virtual plane VP is filled. The perception device 111 detects the heap of the material 200. The perception device 111 detects the shape of the current heap of the material 200. The detection result detected by the perception device 111 is input to the position estimation unit 101 of the automation controller 100. The position estimation unit 101 recognizes the current shape of the heap of the material 200 formed by the stacking work from the detection result of the perception device 111, and recognizes the current height of the heap of the material 200.

The automation controller 100 compares the slope of the heap of the material 200 formed by the stacking work with the virtual plane VP determined in step S7. If it is determined that the slope of the heap of the material 200 has not reached the virtual plane VP (NO in step S9), the processing returns to step S8 and the stacking work is continued. For example, in the state of the heap illustrated in FIG. 13, the slope of the heap of the material 200 created by the most recent stacking is in front of the virtual plane VP (on the left in the drawing), and the slope of the heap of the material 200 does not reach the virtual plane VP. Therefore, the material 200 is not stacked on the lifted-up region V2.

The automation controller 100 controls the travel device 4 and the work implement 3 such that the material 200 is stacked on the lifted-up region V2 by the stacking work and the lifted-up region V2 is filled with the material 200. If it is determined that the slope of the heap of the material 200 formed by the stacking work has reached the virtual plane VP and the current height of the heap has reached the stacking height H1 (YES in step S9), it is determined that the material 200 is stacked on the lifted-up region V2, and the stacking work is completed.

FIG. 14 is a view schematically illustrating heaps of the material 200 at the time of completion of the stacking work. FIG. 14 illustrates a state in which six heaps are formed behind the heap of the material 200 formed by the first stacking work (right side in FIG. 14). The slope of the heap of the material 200 created by the most recent stacking reaches the virtual plane VP, and the material 200 is stacked almost entirely in the lifted-up region V2.

If the material 200 is stacked on the lifted-up region V2, the stacking work is shifted to the lift-up work. Returning to FIG. 7, in step S10, the path follow-up control unit 103 of the automation controller 100 causes the wheel loader 1 to operate following the optimum path generated in step S5, thereby executing the lift-up work.

The path follow-up control unit 103 causes the wheel loader 1 to travel forward toward the heap of the material 200, and causes the blade edge 6a of the bucket 6 to bite into the material 200 in the lifted-up region V2. The path follow-up control unit 103 causes the wheel loader 1 to travel forward in this state so that the wheel loader 1 ascends the slope of the heap of the material 200 while scooping the material 200 in the lifted-up region V2 into the bucket 6. When the bucket 6 reaches the peak Q that is the target position on the upper portion of the heap, the path follow-up control unit 103 discharges the material 200 in the bucket 6 and stacks the material 200 on the upper portion of the slope of the heap. In this way, movement of the material 200 in the lifted-up region V2 to the lift-up region V1 is executed.

In step S11, whether the height of the heap of the material 200 has reached the lift-up height H2 is determined. The perception device 111 detects the heap of the material 200. The perception device 111 detects the shape of the current heap of the material 200. The detection result detected by the perception device 111 is input to the position estimation unit 101 of the automation controller 100. The position estimation unit 101 recognizes the current height of the heap from the shape of the heap of the material 200 detected by the perception device 111.

The automation controller 100 compares the current height of the heap of the material 200 formed by the lift-up work with the lift-up height H2 determined in step S5. If it is determined that the current height is lower than the lift-up height H2, it is determined that the height of the heap of the material 200 has not reached the lift-up height H2 (NO in step S11). In that case, the processing returns to step S10, and the lift-up work is continued.

FIG. 15 is a view schematically illustrating heaps of the material 200 at the time of completion of the lift-up work. FIG. 15 illustrates a state after the path follow-up control unit 103 of the automation controller 100 controls the travel device 4 and the work implement 3 so as to move the entire material 200 in the lifted-up region V2 to the lift-up region V1. The height of a heap of the material 200 illustrated in FIG. 15 reaches the lift-up height H2. The automation controller 100 determines from the detection result of the perception device 111 that the current height of the heap of the material 200 has reached the lift-up height H2 (YES in step S11), and ends the lift-up work.

In this way, a series of processing for executing the stacking work and the lift-up work is ended (“end” in FIG. 7).

<Actions and Effects>

Although there is a description partially overlapping with the above description, the characteristic configurations and actions and effects of the present embodiment will be collectively described as follows.

As illustrated in FIGS. 7, 8, and 11, the path planning unit 102 of the automation controller 100 determines the stacking height H1 that is a height of a heap of the material 200 formed by the material in the bucket 6 being discharged onto the ground G in a state where the front wheels 4a and the rear wheels 4b are grounded to the ground G from the mechanical dimension including the dimension of the work machine main body and the dimension of the work implement 3.

The height of a heap of the material 200 can be appropriately determined by the stacking height H1 that is the height of the heap of the material 200 formed by the stacking work being determined from the mechanical dimension of the wheel loader 1 determined by the main body of the wheel loader 1 (work machine main body) and the geometric shape of the work implement 3. In a case where a limited space, such as a stockyard, is filled with the material 200, the material 200 to fill can be increased.

As illustrated in FIG. 1, the boom pin 9 is an attachment position of the boom 14 to the work machine main body, and the mechanical dimension of the wheel loader 1 may include the length L5 that is the height of the boom pin 9. The height of a heap of the material 200 can be appropriately determined by the stacking height H1 being determined from the height of the boom pin 9.

As illustrated in FIG. 1, the mechanical dimension of the wheel loader 1 may include the length from the boom pin 9 that is the attachment position of the boom 14 to the blade edge 6a of the bucket 6. The height of a heap of the material 200 can be appropriately determined by the stacking height H1 being determined from the mechanical dimension of the work implement 3.

As illustrated in FIG. 8, the path planning unit 102 may determine the stacking height H1 from the mechanical dimension of the wheel loader 1 and the angle of repose θ of the material 200. The height of a heap of the material 200 can be appropriately determined by the stacking height H1 being determined in consideration of the angle of repose θ of the material 200 in addition to the mechanical dimension of the wheel loader 1.

As illustrated in FIGS. 7, 10, and 11, the automation controller 100 may recognize a current height of a heap of the material 200 from the shape of the heap of the material 200 detected by the perception device 111, and determine whether the current height of the material 200 has reached the stacking height H1. If the current height of the material 200 does not reach the stacking height H1, the stacking work is continued, and at a time when the current height of the material 200 reaches the stacking height H1, the stacking work is ended, thereby the heap of the material 200 having the stacking height H1 can be reliably formed.

As illustrated in FIGS. 7, 8, and 11, a heap of the material 200 may be formed by the path planning unit 102 setting the stacking target point O on the ground G, and the path follow-up control unit 103 controlling the travel device 4 and the work implement 3 such that the material 200 is discharged to the stacking target point O a plurality of times. In this way, the heap of the material 200 having the stacking height H1 can be reliably formed at the stacking target point O. If where the stacking target point O is set in a stockyard, the amount of the material 200 filled in the stockyard can be increased.

As illustrated in FIGS. 7, 11, and 13, if it is determined that the current height of the heap of the material 200 has reached the stacking height H1, the automation controller 100 may stop discharging the material 200 to the stacking target point O and set a next target point on the ground G. By the next target point being set at an appropriate position slightly away from the stacking target point O, a heap of the material 200 having a similar shape can be aligned and formed by the stacking work as illustrated in FIG. 14. As illustrated in FIG. 15, by the material 200 being stacked at the center of a series of heaps by the lift-up work, the amount of the material 200 filled in a limited space can be further increased.

The automation controller 100 that forms the automatic control system of the wheel loader 1 described in the above embodiment is not necessarily mounted on the wheel loader 1. A system may be formed in which a controller mounted on the wheel loader 1 performs processing of transmitting information acquired by the external information acquisition unit 110, the vehicle information acquisition unit 120, and the like to an external controller, and the external controller that has received a signal automatically controls the wheel loader 1. The external controller may be disposed at a work site of the wheel loader 1, or may be disposed at a remote place away from the work site of the wheel loader 1.

In the embodiment, an example has been described in which the wheel loader 1 includes the cab 5 and is a manned vehicle in which the operator boards the cab 5. The wheel loader 1 may be an unmanned vehicle. The wheel loader 1 may not include the cab 5 for the operator to board and operate. The wheel loader 1 may not include a steering function by a boarded operator. The wheel loader 1 may be a work machine dedicated to remote control. The operation of the wheel loader 1 may be performed by a wireless signal from a remote control device.

Supplementary Note

The above description includes the following features.

(Supplement 1)

A system including a work machine, the system including:

• • a work machine main body including a travel body;
  • a work implement attached to the work machine main body and including a bucket; and
  • a controller that commands operation of the travel body and the work implement, in which
  • the controller determines a height of a heap of material formed by the material in the bucket being discharged onto a ground in a state where the travel body is grounded to the ground from a mechanical dimension including a dimension of the work machine main body and a dimension of the work implement.

(Supplement 2)

The system according to Supplement 1, in which

• • the work implement includes a boom to which the bucket is attached at a distal end, and
  • the mechanical dimension includes a height of an attachment position of the boom to the work machine main body.

(Supplement 3)

The system according to Supplement 1 or 2, in which

• • the bucket includes a blade edge, and
  • the mechanical dimension includes a length from the attachment position of the boom to the blade edge.

(Supplement 4)

The system according to any one of Supplements 1 to 3, in which the controller determines the height of the heap from the mechanical dimension and an angle of repose of the material.

(Supplement 5)

The system according to any one of Supplements 1 to 4 further including an object sensor that detects an object around the work machine main body, in which

• • the controller recognizes a current height of the heap from a shape of the heap detected by the object sensor, and determines whether the current height of the heap has reached the height.

(Supplement 6)

The system according to any one of Supplements 1 to 5, in which the controller forms the heap by setting a target point on the ground and controlling the travel body and the work implement such that the material is discharged to the target point a plurality of times.

(Supplement 7)

The system according to Supplement 6, in which the controller stops discharging the material to the target point and sets a next target point on the ground in a case where the current height of the heap is determined to have reached the height.

It should be understood that the embodiments disclosed herein are illustrative in all respects and not restrictive. The scope of the present invention is defined not by the above description but by the claims, and is intended to include meanings equivalent to the claims and all modifications within the scope.

REFERENCE SIGNS LIST

• • 1 Wheel loader
  • 2 Vehicle body frame
  • 2a Front frame
  • 2b Rear frame
  • 3 Work implement
  • 4 Travel device
  • 4a Front wheel
  • 4b Rear wheel
  • 6 Bucket
  • 6a Blade edge
  • 6b Back surface
  • 9 Boom pin
  • 14 Boom
  • 17 Bucket pin
  • 18 Bell crank
  • 18a Support pin
  • 18b, 18c Coupling pin
  • 100 Automation controller
  • 101 Position estimation unit
  • 102 Path planning unit
  • 103 Path follow-up control unit
  • 110 External information acquisition unit
  • 111 Perception device
  • 120 Vehicle information acquisition unit
  • 123 Boom angle sensor
  • 124 Bucket angle sensor
  • 125 Boom cylinder pressure sensor
  • 130 Interface
  • 140 Actuator
  • 200 Material
  • A Boom reference line
  • B Bell crank reference line
  • BL Bucket trajectory
  • CL Center line
  • G Ground
  • H Horizontal line
  • H1 Stacking height
  • H2 Lift-up height
  • L1 to L9 Length
  • O Stacking target point
  • P, Q Peak
  • V1 Lift-up region
  • V2 Lifted-up region
  • VP Virtual plane
  • α Boom angle
  • β Bell crank angle
  • γ Departure angle
  • θ Angle of repose.