Work machine, system including work machine, and control method of work machine

Abstract

To rearrange the appearance of cargo that has been loaded into a container.SOLUTION: A work machine has a bucket 6 at the end. An actuator of the work machine drives the work machine. A controller operates the actuator of the work machine to lower the bucket 6 above a vessel 301 until the bucket hits a load 310 after the loading operation of the load 310 into the vessel 301 is completed.SELECTED DRAWING: Figure 11

Description

[Technical Field]

[0001] The present disclosure relates to a work machine, a system including a work machine, and a method for controlling a work machine. [Background technology]

[0002] International Publication No. 2016 / 152994 (Patent Document 1) discloses control for moving a boom and a bucket to a target position determined according to the travel distance of a wheel loader. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2016 / 152994 Summary of the Invention [Problem to be solved by the invention]

[0004] The work machine loads cargo into containers such as the vessels of the dump truck. If the loaded cargo is not properly packed, there is a risk that the cargo will spill while the dump truck is traveling.

[0005] The present disclosure proposes a work machine, a system including a work machine, and a method for controlling a work machine that are capable of adjusting the shape of a load loaded into a container. [Means for solving the problem]

[0006] A work machine and a system including a work machine according to an aspect of the present disclosure each include a work machine, a work machine actuator, and a controller. The work machine has an attachment at its tip. The work machine actuator drives the work machine. After loading a load into a container is completed, the controller operates the work machine actuator to lower the attachment above the container until it contacts the load.

[0007] A method for controlling a work machine according to one aspect of the present disclosure includes the following steps: a first step is loading a load into a container; and a second step is, after the container has been loaded with the load, lowering an attachment at the tip of a work implement of the work machine above the container until it contacts the load. [Effects of the Invention]

[0008] According to the work machine, system including the work machine, and control method for the work machine of the present disclosure, it is possible to straighten the shape of the load loaded into the container. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a side view of a wheel loader as an example of a work machine. [Figure 2] FIG. 1 is a block diagram showing a schematic configuration of a control system for a wheel loader. [Figure 3] FIG. 1 is a plan view of a wheel loader performing excavation and loading work. [Figure 4] FIG. 1 is a block diagram showing the configuration of an automatic control system for a wheel loader. [Figure 5] 10 is a flowchart showing the flow of an operation for loading a load loaded in a bucket onto a loading target by automatic control. [Figure 6] FIG. 10 is a schematic diagram showing the arrangement of a target position relative to a vessel. [Figure 7] FIG. 10 is a diagram schematically showing a wheel loader with the cutting edge at a target position d. [Figure 8] FIG. 10 is a diagram schematically illustrating a wheel loader with the cutting edge at a target position g. [Figure 9] FIG. 10 is a diagram schematically illustrating a wheel loader with the cutting edge at a target position h. [Figure 10] FIG. 10 is a diagram schematically illustrating a wheel loader with the cutting edge at a target position i. [Figure 11] FIG. 10 is a diagram showing the change in the shape of a load in a vessel due to pushing. [Figure 12] FIG. 10 is a diagram schematically illustrating a wheel loader with the cutting edge at a target position j. [Figure 13] FIG. 10 is a diagram schematically illustrating a wheel loader with a cutting edge at a target position k. [Figure 14] 10 is a graph showing the change in cylinder length during loading operations. [Figure 15] FIG. 10 is a first diagram showing a modified example of the operation of the work machine when loading is completed. [Figure 16] FIG. 10 is a second diagram showing a modified example of the operation of the work machine when loading is completed. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, the embodiments will be described with reference to the drawings. In the following description, the same parts and components are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed descriptions thereof will not be repeated. In the drawings, configurations may be omitted or simplified for the sake of convenience. It is also intended from the beginning that any configurations may be extracted from the embodiments and arbitrarily combined.

[0011] <Overall configuration of wheel loader 1> In the embodiment, a wheel loader 1 will be described as an example of a work machine. Fig. 1 is a side view of a wheel loader 1 as an example of a work machine.

[0012] As shown in Fig. 1, the wheel loader 1 comprises a body frame 2, a work implement 3, a traveling device 4, and a cab 5. The body frame 2, the cab 5, etc. make up the body of the wheel loader 1. The work implement 3 and the traveling device 4 are attached to the body of the wheel loader 1. The main body of the wheel loader 1 comprises the body and the traveling device 4.

[0013] The traveling device 4 allows the body of the wheel loader 1 to travel, and includes traveling wheels 4a, 4b. The wheel loader 1 is a wheeled vehicle equipped with traveling wheels 4a, 4b on both the left and right sides of the body as rotating bodies for traveling. The wheel loader 1 is self-propelled by driving the traveling wheels 4a, 4b to rotate, and can perform desired work using the work implement 3. The traveling device 4 corresponds to an example of a "traveling body".

[0014] In this specification, the direction in which the wheel loader 1 travels straight ahead is referred to as the fore-and-aft direction of the wheel loader 1. In the fore-and-aft direction of the wheel loader 1, the side on which the work implement 3 is arranged relative to the body frame 2 is referred to as the front direction, and the side opposite the front direction is referred to as the rear direction. The left-and-right direction of the wheel loader 1 is the direction perpendicular to the fore-and-aft direction when the wheel loader 1 is viewed from above on flat ground. Looking forward, the right and left sides of the left-and-right direction are the right direction and the left direction, respectively. The up-and-down direction of the wheel loader 1 is the direction perpendicular to the plane defined by the fore-and-aft direction and the left-and-right direction. In the up-and-down direction, the side with the ground is the bottom side, and the side with sky is the top side.

[0015] 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 so as to be movable relative to each other in the left-right direction.

[0016] A pair of steering cylinders 11 are attached across the front frame 2a and the rear frame 2b. The steering cylinders 11 are hydraulic cylinders. The steering cylinders 11 are extended and retracted by hydraulic oil from a steering pump, thereby changing the direction of travel of the wheel loader 1 from left to right. The front frame 2a and the rear frame 2b make up a body frame 2 with an articulated structure. The wheel loader 1 is an articulated work machine in which the front frame 2a and the rear frame 2b are connected so that they can be bent.

[0017] A work implement 3 and a pair of running wheels (front wheels) 4a are attached to the front frame 2a. The work implement 3 is attached to the front of the main body of the wheel loader 1. The work implement 3 is supported by the vehicle body of the wheel loader 1. The work implement 3 includes a boom 14 and a bucket 6. The work implement 3 has the bucket 6 at its tip. The bucket 6 is a work tool for excavating and loading. The bucket 6 is an example of an "attachment" that is detachably mounted to the tip of the boom 14. Depending on the type of work, the attachment can be changed to a grapple, fork, plow, or the like.

[0018] The bucket 6 has a cutting edge 6a and a bottom surface 6b. The cutting edge 6a is the tip of the bucket 6. The bottom surface 6b is part of the outer surface of the bucket 6. The bottom surface 6b is formed as a flat surface. The bottom surface 6b extends rearward from the cutting edge 6a.

[0019] The base end of the boom 14 is rotatably attached to the front frame 2a by a boom pin 9. The bucket 6 is rotatably attached to the boom 14 by a bucket pin 17 located at the tip of the boom 14.

[0020] The work implement 3 further includes a bell crank 18 and a link 15. The bell crank 18 is rotatably supported on the boom 14 by a support pin 18a located approximately in the center of the boom 14. The link 15 is connected to a connecting pin 18c provided at the tip of the bell crank 18. The link 15 connects the bell crank 18 and the bucket 6.

[0021] The front frame 2a and the boom 14 are connected by a pair of boom cylinders 16. The boom cylinders 16 are hydraulic cylinders. The boom cylinders 16 rotate the boom 14 up and down around the boom pin 9. The base end of the boom cylinder 16 is attached to the front frame 2a. The tip of the boom cylinder 16 is attached to the boom 14. The boom cylinders 16 are hydraulic actuators that move the boom 14 up and down relative to the front frame 2a. As the boom 14 moves up and down, the bucket 6 attached to the tip of the boom 14 also moves up and down.

[0022] The bucket cylinder 19 connects 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 tip of the bucket cylinder 19 is attached to a connecting pin 18b provided at the base end of the bell crank 18. The bucket cylinder 19 is a hydraulic actuator that rotates the bucket 6 up and down relative to the boom 14. The bucket cylinder 19 is an implement cylinder that drives the bucket 6. The bucket cylinder 19 drives the bucket 6 to rotate around the bucket pin 17. The bucket 6 is configured to be movable relative to the boom 14. The bucket 6 is configured to be movable relative to the front frame 2a.

[0023] The boom cylinder 16 and the bucket cylinder 19 correspond to an example of a “work implement actuator” that drives the work implement 3.

[0024] A cab 5 in which the operator sits and a pair of running wheels (rear wheels) 4b are attached to the rear frame 2b. The box-shaped cab 5 is located behind the boom 14. The cab 5 is mounted on the body frame 2. Inside the cab 5, a seat in which the operator of the wheel loader 1 sits, an operating device 8 (described later), and the like are arranged.

[0025] The cab 5 is provided with a perception device 111. The perception device 111 is arranged, for example, on the ceiling of the cab 5. The perception device 111 is mounted, for example, on the top surface of the cab 5. The perception device 111 is arranged, for example, at the front of the cab 5. The perception device 111 is attached to the cab 5, for example, facing forward, and is capable of acquiring information about the area in front of the cab 5. Details of the perception device 111 will be described later.

[0026] <System configuration> FIG. 2 is a block diagram showing a schematic configuration of a control system that controls the wheel loader 1. As shown in FIG.

[0027] The engine 21 is a drive source, such as a diesel engine, that generates drive power for driving the work implement 3 and the traveling device 4. Instead of the engine 21, a motor driven by an electricity storage device may be used as the drive source, 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.

[0028] The driving force generated by the engine 21 is transmitted to the transmission 23. The transmission 23 changes the driving force to an appropriate torque and rotational speed. An axle 25 is connected to the output shaft of the transmission 23. The driving force changed by the transmission 23 is transmitted to the axle 25. The driving force is transmitted from the axle 25 to the running wheels 4a, 4b (Figure 1). This causes the wheel loader 1 to travel. In the wheel loader 1 of this embodiment, both the running wheels 4a and 4b constitute driving wheels that receive the driving force and cause the wheel loader 1 to travel.

[0029] A portion of the driving force of the engine 21 is transmitted to the 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 the hydraulic oil that it discharges. The work implement 3 is driven by the hydraulic oil from the work implement pump 13. The hydraulic oil discharged from the work implement pump 13 is supplied to the boom cylinder 16 and the bucket cylinder 19 via a main valve 32. The boom cylinder 16 receives a supply of hydraulic oil and extends and contracts, causing the boom 14 to rise and fall. The bucket cylinder 19 receives a supply of hydraulic oil and extends and contracts, causing the bucket 6 to rotate up and down.

[0030] The wheel loader 1 is equipped with a vehicle body controller 50. The vehicle body controller 50 includes an engine controller 60, a transmission controller 70, and a work machine controller 80.

[0031] The vehicle body controller 50 is generally implemented by loading various programs using a CPU (Central Processing Unit). The vehicle body controller 50 has a memory (not shown). The memory functions as a work memory and stores various programs for implementing the functions of the wheel loader 1.

[0032] The operating device 8 is provided in the cab 5. The operating device 8 is operated by an operator. The operating device 8 is equipped with a plurality of types of operating members that the operator operates to operate the wheel loader 1. The operating device 8 includes an accelerator pedal 41 and a work equipment operating lever 42. The operating device 8 may also include a steering handle, a shift lever, etc., which are not shown.

[0033] Accelerator pedal 41 is operated to set a target rotation speed of engine 21. Engine controller 60 controls the output of engine 21 based on the amount of operation of accelerator pedal 41. Increasing the amount of operation (depression amount) of accelerator pedal 41 increases the output of engine 21. Decreasing the amount of operation of accelerator pedal 41 decreases the output of engine 21. Transmission controller 70 controls transmission 23 based on the amount of operation of accelerator pedal 41.

[0034] The work implement control lever is operated to operate the work implement 3. The work implement controller 80 controls the electromagnetic proportional control valves 35, based on the amount of operation of the work implement control lever .

[0035] The electromagnetic proportional control valve 35 switches the main valve 32 so that the bucket cylinder 19 retracts and the bucket 6 moves in the dump direction (the direction in which the cutting edge of the bucket 6 moves down). The electromagnetic proportional control valve 35 also switches the main valve 32 so that the bucket cylinder 19 extends and the bucket 6 moves in the tilt direction (the direction in which the cutting edge of the bucket 6 moves up). The electromagnetic proportional control valve 36 switches the main valve 32 so that the boom cylinder 16 retracts and the boom 14 moves down. The electromagnetic proportional control valve 36 also switches the main valve 32 so that the boom cylinder 16 extends and the boom 14 moves up.

[0036] The machine monitor 51 displays various types of information upon receiving command signals from the vehicle body controller 50. The various types of information displayed on the machine monitor 51 may be, for example, information relating to the work performed by the wheel loader 1, vehicle body information such as the remaining fuel level, coolant temperature, and hydraulic oil temperature, and peripheral images captured of the area around the wheel loader 1. The machine monitor 51 may be a touch panel, and in this case, a signal generated when the operator touches a part of the machine monitor 51 is output from the machine monitor 51 to the vehicle body controller 50.

[0037] <Excavation and loading work> The wheel loader 1 of this embodiment performs excavation and loading work by scooping up excavation objects such as earth and sand and loading them into a loading object such as a dump truck. Fig. 3 is a plan view of a wheel loader 1 performing excavation and loading work. Fig. 3 shows a wheel loader 1 performing so-called V-shape work.

[0038] 3(A) shows a wheel loader 1 moving forward empty. The wheel loader 1 moves forward along an excavation path R1 toward an excavation target 310 such as earth and sand. The wheel loader 1 plunges the bucket 6 into the excavation target 310 and stops moving forward. By raising the bucket 6 with the cutting edge 6a of the bucket 6 digging into the excavation target 310, an excavation operation is performed in which the bucket 6 scoops up the excavation target 310.

[0039] Figure 3(B) shows the wheel loader 1 moving backward with a load. An excavation object 310 is loaded into the bucket 6. The wheel loader 1 moves backward along the excavation path R1 to the position where it started moving forward in Figure 3(A).

[0040] Figure 3(C) shows the wheel loader 1 performing what is called load forward movement. With the object to be excavated 310 loaded in the bucket 6, the wheel loader 1 travels forward toward the vessel 301 of the dump truck 300. The wheel loader 1 travels forward along the loading route R2 toward the dump truck 300 from the position where it started traveling forward in Figure 3(A). When it approaches the dump truck 300 and reaches a predetermined position, the wheel loader 1 loads the object to be excavated 310 in the bucket 6 into the vessel 301.

[0041] Figure 3(D) shows the wheel loader 1 moving backward empty. After all of the excavation objects 310 in the bucket 6 have been discharged into the vessel 301 of the dump truck 300 and the bucket 6 is empty, the wheel loader 1 moves backward along the loading route R2 to the position where it started moving forward in Figure 3(C).

[0042] In this way, the wheel loader 1 can repeatedly perform a series of operations including excavation, reversing, dump approach, earth removal, and reversing.

[0043] <Automatic control system for wheel loader 1> When automating the loading operation of the wheel loader 1 onto the dump truck 300, it is desirable to reproduce the operation of the work implement 3 by a skilled operator through automatic control in order to perform the loading operation more quickly while ensuring a sufficient amount of work and without the bucket 6 coming into contact with the vessel 301. Figure 4 is a block diagram showing the configuration of the automatic control system for the wheel loader 1.

[0044] The automation controller 100 is configured to be able to send and receive signals to and from the vehicle body controller 50 described with reference to Fig. 2. The automation controller 100 is also configured to be able to send and receive signals to and from an external world information acquisition unit 110. The external world information acquisition unit 110 has a 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.

[0045] The perception device 111 acquires information about the surroundings of the wheel loader 1. The perception device 111 is attached, for example, to the upper front of the cab 5. The perception device 111 detects objects around the main body of the wheel loader 1.

[0046] The perception device 111 detects the direction of an object outside the wheel loader 1 and the distance to the object in a non-contact manner. The perception device 111 is, for example, a LiDAR (Light Detection and Ranging) that emits laser light to acquire information about the object. The perception device 111 may also be a visual sensor including a camera. The perception device 111 may also be a Radar (Radio Detection and Ranging) that acquires information about the object by emitting radio waves. The perception device 111 may also be an infrared sensor.

[0047] The position information acquisition device 112 acquires information about the current position of the wheel loader 1. For example, the position information acquisition device 112 uses a satellite positioning system to acquire position information of the wheel loader 1 in a global coordinate system based on the Earth. The position information acquisition device 112 uses, for example, GNSS (Global Navigation Satellite Systems) and has a GNSS receiver. The satellite positioning system calculates the position of the antenna of the GNSS receiver based on positioning signals received by the GNSS receiver from satellites, and calculates the position of the wheel loader 1.

[0048] The external environment information of the wheel loader 1 obtained by the perception device 111 and the position information of the wheel loader 1 obtained by the position information acquisition device 112 are input to the automation controller 100.

[0049] The vehicle body controller 50 is configured to be able to send and receive signals to and from the vehicle information acquisition unit 120. Information about the wheel loader 1 acquired by the vehicle information acquisition unit 120 is input to the vehicle body controller 50. The vehicle information acquisition unit 120 is made up of various sensors mounted on the wheel loader 1. The vehicle information acquisition unit 120 has an articulation angle sensor 121, a vehicle speed sensor 122, a boom angle sensor 123, a bucket angle sensor 124, and a boom cylinder pressure sensor 125.

[0050] The articulation angle sensor 121 detects the articulation angle, which is the angle between 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.

[0051] The vehicle speed sensor 122 detects the travel speed of the wheel loader 1 caused by the traveling device 4, for example, by detecting the rotational 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 vehicle speed signal to the vehicle body controller 50. The vehicle speed sensor 122 detects the progress of the traveling device 4 (traveling body).

[0052] The boom angle sensor 123 is configured, for example, by a rotary encoder provided on the boom pin 9, which is the attachment portion of the boom 14 to the body frame 2. The boom angle sensor 123 detects the angle of the boom 14 with respect to the horizontal direction and generates a signal of the detected angle of the boom 14. The boom angle sensor 123 outputs the signal of the angle of the boom 14 to the body controller 50.

[0053] Bucket angle sensor 124 is configured, for example, by a rotary encoder provided on support pin 18a, which is the rotation shaft of bell crank 18. Bucket angle sensor 124 detects the angle of bucket 6 with respect to boom 14 and generates a signal of the detected angle of bucket 6. Bucket angle sensor 124 outputs the signal of the angle of bucket 6 to vehicle body controller 50.

[0054] The boom angle sensor 123 and the bucket angle sensor 124 detect the attitude of the work implement 3 .

[0055] Boom cylinder pressure sensor 125 detects the pressure on the bottom side of boom cylinder 16 (boom bottom pressure) and generates a signal of the detected boom bottom pressure. The boom bottom pressure increases when bucket 6 is loaded and decreases when it is empty. Boom cylinder pressure sensor 125 outputs the boom bottom pressure signal to vehicle body controller 50.

[0056] The vehicle body controller 50 outputs the information input from the vehicle information acquisition unit 120 to the automation controller 100. The automation controller 100 inputs the 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.

[0057] The electromagnetic proportional control valve 140 is configured to be able to send and receive signals to and from the vehicle body controller 50. The electromagnetic proportional control valve 140 is driven upon receiving a command signal from the vehicle body controller 50. The electromagnetic proportional control valve 140 includes a brake EPC (electromagnetic proportional control valve) 141 for actuating the brakes of the traveling device 4, a steering EPC 142 for adjusting the traveling direction of the wheel loader 1, and a work implement EPC 143 for operating the work implement 3.

[0058] The electromagnetic proportional control valves 35 and 36 shown in Fig. 2 constitute the work machine EPC 143. The transmission 23 shown in Fig. 2 is realized as a mechanical transmission. The transmission 23 may be an HST (Hydro-Static Transmission) or an HMT (Hydraulic Mechanical Transmission) that combines an HST and a mechanical transmission. The power transmission device that transmits power from the engine 21 to the running wheels 4a and 4b may include an electric drive device such as a diesel-electric system, or may include any combination of an HMT, an HST, and an electric drive device.

[0059] The transmission controller 70 has a brake control unit 71 and an accelerator control unit 72. The brake control unit 71 outputs a command signal to the brake EPC 141 to control the operation of the brake. The accelerator control unit 72 outputs a command signal to the transmission 23 to control the vehicle speed.

[0060] The work machine controller 80 has a steering control section 81 and a work machine control section 82. The steering control section 81 outputs a command signal to the steering EPC 142 to control the traveling direction of the wheel loader 1. The work machine control section 82 outputs a command signal to the work machine EPC 143 to control the operation of the work machine 3.

[0061] The automation controller 100 includes a position estimation unit 101 , a path planning unit 102 , and a path following control unit 103 .

[0062] The position estimation unit 101 estimates the self-position of the wheel loader 1 based on the position information acquired by the position information acquisition device 112. The position estimation unit 101 also recognizes a target position based on external environment information acquired by the perception device 111. The target position is, for example, the position of the excavation target object 310 or the dump truck 300 shown in FIG. 3. The position estimation unit 101 can acquire a predetermined reference point of the dump truck 300, for example, the position of the upper end of the side of the vessel 301. The perception device 111 may recognize the target position and input it to the automation controller 100, or the position estimation unit 101 may recognize the target position based on the detection result detected by the perception device 111.

[0063] The path planning unit 102 generates an optimal route for the wheel loader 1 when automatically controlling the wheel loader 1. The optimal route includes a route for travel by the traveling devices 4 and a route for operation of the work implement 3. For example, the path planning unit 102 generates an optimal route for the wheel loader 1 moving forward with a load toward the dump truck 300, and an optimal route for the wheel loader 1 moving backward empty and away from the dump truck 300, during the operation of loading the dump truck 300. The path planning unit 102 also generates an optimal route connecting the current position of the wheel loader 1 and a target position to which the wheel loader 1 is heading while the operation of loading the dump truck 300 is being performed.

[0064] The path following control unit 103 controls the accelerator, brake, and steering so that the wheel loader 1 travels following the optimal path generated by the path planning unit 102. A command signal for causing the wheel loader 1 to travel along the optimal path is output from the path following control unit 103 to the brake control unit 71, accelerator control unit 72, and steering control unit 81. The path following control unit 103 controls the boom cylinder 16 and bucket cylinder 19 so that the work implement 3 operates along the optimal path generated by the path planning unit 102. A command signal for causing the work implement 3 to move along the optimal path is output from the path following control unit 103 to the work implement control unit 82.

[0065] The interface 130 is configured to be able to send and receive signals to and from the vehicle body controller 50. The interface 130 has an automation changeover switch 131, an engine emergency stop switch 132, and a mode lamp 133.

[0066] The automation changeover switch 131 is operated by an operator. By operating the automation changeover switch 131, the operator switches 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. When an event occurs that requires an emergency stop of the engine 21, the operator operates the engine emergency stop switch 132. Operation signals of the automation changeover switch 131 and the engine emergency stop switch 132 are input to the vehicle body controller 50.

[0067] The mode lamp 133 indicates whether the wheel loader 1 is currently in a mode where it is manually operated by an operator, or in a mode where it is automatically controlled. A command signal is output from the vehicle body controller 50 to the mode lamp 133 to control the lighting of the lamp.

[0068] <Automatic dump loading flow> 5 is a flowchart showing the flow of an operation for loading the load in the bucket 6 into a loading target by automatically controlling the wheel loader 1. The vessel 301 of the dump truck 300 corresponds to an example of a "container" into which the load loaded in the work implement 3 (bucket 6) is loaded. The container is not limited to the vessel 301 of the dump truck 300, and may be, for example, a hopper. The container is an example of a loading target into which the load in the bucket 6 is loaded.

[0069] First, as advance preparation, before starting the loading operation, in step S100, the shape of the vessel 301 of the dump truck 300, which is the loading target, is recognized. For example, the shape of the dump truck 300 is acquired by a LiDAR, which is the perception device 111. The LiDAR irradiates the dump truck 300 with laser light from four directions, namely the front, rear, right, and left, to acquire point cloud data indicating three-dimensional coordinate values ​​of measurement points on the dump truck 300. The automation controller 100 compares the acquired point cloud data with a pre-stored master point cloud of the vessel 301, and recognizes the shape of the vessel 301 from the point cloud data.

[0070] The wheel loader 1 and the dump truck 300 may perform vehicle-to-vehicle communication. In addition to the system configuration shown in Fig. 4, the wheel loader 1 may be equipped with a communication unit that communicates with the dump truck 300. Information about the vessel 301, such as the load capacity of the vessel 301 and the shape of the vessel 301, may be transmitted from the dump truck 300 to the wheel loader 1 through vehicle-to-vehicle communication between the communication unit of the wheel loader 1 and the communication unit of the dump truck 300.

[0071] In step S101, the perception device 111 recognizes a reference point P of the dump truck 300. The dump truck 300 is detected by the LiDAR, which is the perception device 111. The automation controller 100 recognizes the position of the vessel 301 of the dump truck 300 using the self-position of the wheel loader 1 and the relative position of the dump truck 300 with respect to the wheel loader 1. The automation controller 100 sets the upper end of the side surface of the vessel 301 of the dump truck 300 as the reference point P.

[0072] In step S102, the automation controller 100 sets the coordinates of target positions d, g, h, i, j, and k of the cutting edge 6a of the bucket 6 that moves under automatic control, relative to the reference point P. The cutting edge 6a of the bucket 6 corresponds to an example of a feature point that is set on the work implement 3. Note that the feature point is not limited to the cutting edge 6a of the bucket 6, and other points on the work implement 3 may also be set as feature points.

[0073] Here, the reference point P and the target positions d, g, h, i, j, and k will be explained. Figure 6 is a schematic diagram showing the arrangement of the target positions relative to the vessel 301. Figure 6 and the subsequent Figures 7 to 13 and 15 to 16 schematically show the vessel 301 as viewed from the front-to-rear direction of the dump truck 300, and also schematically show a portion of the front side of the wheel loader 1 approaching the vessel 301 from the left or right side of the dump truck 300.

[0074] As shown in FIG. 6, an xy coordinate system is set with a reference point P as the origin. The x-axis is the left-right direction of the dump truck 300 that passes through the reference point P. The direction away from the vessel 301 based on the reference point P is the +x direction. The y-axis is the up-down direction that passes through the reference point P. The upward direction from the reference point P is the +y direction.

[0075] The target positions d, g, h, i, j, and k are determined by providing the x-coordinate indicating the position of the cutting edge 6a of the bucket 6 in a direction parallel to the ground and the y-coordinate indicating the position in a direction perpendicular to the ground, with reference to the reference point P. Typically, the y-coordinate indicates the position in the vertical direction (the direction of gravity), and the x-coordinate indicates the position in the horizontal direction perpendicular to the vertical direction. The target position i is set as the position where the height position of the cutting edge 6a is lowest (the y-coordinate is the smallest value) during load pushing to straighten the load loaded in the vessel 301.

[0076] The angle (bucket angle) formed between the ground and the bottom surface 6b of the bucket 6 when the cutting edge 6a of the bucket 6 is at each target position is also set. The attitude of the work implement 3 when the cutting edge 6a of the bucket 6 is at each target position is determined from the x and y coordinates of each target position and the bucket angle at each target position. The automation controller 100 stores the attitude (target attitude) of the work implement 3 when the cutting edge 6a of the bucket 6 is at each target position. Based on the target attitude when the cutting edge 6a of the bucket 6 is at each target position, the length of the boom cylinder 16 and the length of the bucket cylinder 19 when the cutting edge 6a of the bucket 6 is at each target position are determined.

[0077] The x and y coordinates of each target position, as well as the bucket angle at each target position, can be determined by analyzing the trajectory of the cutting edge 6a when an experienced operator performs loading work, extracting characteristic positions, and then extracting the posture of the work implement 3 at those characteristic positions.

[0078] FIG. 7 is a schematic diagram showing the wheel loader 1 with the cutting edge 6a at target position d. Target position d is set as the position through which the cutting edge 6a of the bucket 6 passes when loading the load in the bucket 6 into the vessel 301. As the wheel loader 1 approaches the dump truck 300, it raises the boom 14 to avoid interference between the work implement 3 and the vessel 301. The wheel loader 1 also moves the bucket 6 in the dumping direction to discharge the load in the bucket 6 from the bucket 6. When the cutting edge 6a of the bucket 6 is at target position d, the boom 14 is at its uppermost position, and the bucket 6 is in a fully dumped state. When the cutting edge 6a of the bucket 6 is at target position d, the length of the boom cylinder 16 is at its maximum, and the length of the bucket cylinder 19 is at its minimum. Target position d is above the vessel 301.

[0079] FIG. 8 is a diagram schematically showing the wheel loader 1 with the cutting edge 6a at target position g. Target position g is set as the position that the cutting edge 6a of the bucket 6 will pass through after passing target position d. From the time the cutting edge 6a of the bucket 6 passes target position d until it reaches target position g, the wheel loader 1 travels in reverse, and the work implement 3 maintains that posture. From the time the cutting edge 6a of the bucket 6 passes target position d until it reaches target position g, the boom 14 remains in its uppermost position, and the bucket 6 remains in its fully dumped state. Target position g is directly above reference point P. Target position g is the position at which the wheel loader 1 stops traveling in reverse and starts traveling forward. Target position g is the position at which the bucket 6 starts moving in the tilt direction.

[0080] FIG. 9 is a diagram schematically showing the wheel loader 1 with the cutting edge 6a at target position h. Target position h is set as the position through which the cutting edge 6a of the bucket 6 will pass after passing target position g. From the time the cutting edge 6a of the bucket 6 passes target position g until it reaches target position h, the wheel loader 1 travels forward, and the movement of the bucket 6 in the tilt direction continues. From the time the cutting edge 6a of the bucket 6 passes target position g until it reaches target position h, the boom 14 maintains its uppermost position. Target position h is the position where the bottom surface 6b of the bucket 6 is parallel to the ground. Target position h is the position at which the wheel loader 1 stops traveling forward. Target position h is the position at which the lowering operation of the boom 14 starts.

[0081] The position at which the wheel loader 1 stops traveling forward is set at a position where the front wheels 4a of the wheel loader 1 do not come into contact with the dump truck 300. For example, taking into consideration measurement errors of the position information acquisition device 112, the position may be set so that the wheel loader 1 stops traveling forward at a position where the front wheels 4a do not reliably come into contact with the dump truck 300.

[0082] FIG. 10 is a diagram schematically showing the wheel loader 1 with the cutting edge 6a at target position i. Target position i is set as the position through which the cutting edge 6a of the bucket 6 will pass after passing target position h. The wheel loader 1 stops traveling from the time the cutting edge 6a of the bucket 6 passes target position h until it reaches target position i. From the time the cutting edge 6a of the bucket 6 passes target position h until it reaches target position i, the lowering operation of the boom 14 is maintained while keeping the bottom surface 6b of the bucket 6 parallel to the ground. In order to keep the bottom surface 6b of the bucket 6 parallel to the ground, the attitude of the bucket 6 with respect to the boom 14 is changed. Target position i is the position at which the lowering operation of the boom 14 stops and the raising operation starts.

[0083] 11 is a diagram showing a change in the shape of the load 310 in the vessel 301 due to a load being pushed. If, at the time when loading of the load 310 into the vessel 301 is completed, the height of the pile of the load 310 loaded into the vessel 301 is high and the top of the load 310 is higher than the reference point P, there is a risk that the load 310 will spill out of the vessel 301 while the dump truck 300 is traveling. By straightening the shape of the load 310 loaded into the vessel 301, it is possible to prevent the load 310 from spilling out of the vessel 301. For this reason, in the embodiment, after the loading operation of the load into the vessel 301 is completed, the boom cylinder 16 and the bucket cylinder 19 are operated to lower the bucket 6 above the vessel 301 until the bucket 6 contacts the load 310.

[0084] By moving the bucket 6 from top to bottom toward the vessel 301 loaded with the load 310 and bringing the bucket 6 into contact with the load 310, the bottom surface 6b of the bucket 6 pushes the load 310 loaded in the vessel 301 from above. By pushing the load 310 with the bottom surface 6b of the bucket 6, the shape of the load 310 is straightened and the height of the pile of the load 310 becomes smaller. This prevents the load 310 from spilling out of the vessel 301 while the dump truck 300 is traveling.

[0085] When the cutting edge 6a is at target position i, the bucket 6 is in a state where it is lowered most above the vessel 301. In this state, the bucket 6 is positioned directly above the center of the vessel 301 in the longitudinal direction of the wheel loader 1 or the lateral direction of the dump truck 300 (the lateral direction in the drawings in FIGS. 10 and 11). Typically, the x coordinate of the target position i is set so that the midpoint of the line segment representing the bottom surface 6b when the bucket 6 is viewed in the lateral direction of the wheel loader 1 is positioned directly above the center of the vessel 301. The y coordinate of the target position i is set as a position where the work implement 3 is a predetermined distance away from the upper end of the side surface of the vessel 301 (reference point P) so that the work implement 3 does not come into contact with the vessel 301. The target position i may also be set to a position where the y coordinate is on the positive side.

[0086] FIG. 12 is a schematic diagram showing the wheel loader 1 with the cutting edge 6a at target position j. Target position j is set as the position through which the cutting edge 6a of the bucket 6 will pass after passing target position i. The wheel loader 1 stops traveling from the time the cutting edge 6a of the bucket 6 passes target position i until it reaches target position j. From the time the cutting edge 6a of the bucket 6 passes target position i until it reaches target position j, the raising operation of the boom 14 is maintained while keeping the bottom surface 6b of the bucket 6 parallel to the ground. In order to keep the bottom surface 6b of the bucket 6 parallel to the ground, the attitude of the bucket 6 with respect to the boom 14 changes. When the cutting edge 6a moves from target position i to target position j, the bucket 6 is raised while the traveling is stopped. Target position j is the position at which the wheel loader 1 starts traveling backward.

[0087] The bucket 6 moves upward due to the raising operation of the boom 14 from the target position i to the target position j. The bucket 6 moves in a direction away from the vessel 301. The bucket 6 moves in a direction away from the load 310 loaded in the vessel 301. The upward movement distance of the bucket 6 from the target position i to the target position j may be set to a distance that ensures that the bucket 6 does not come into contact with the load 310, taking into account measurement errors of the boom angle sensor 123 and the bucket angle sensor 124. When the y coordinate of the target position i is set to a positive value, the y coordinate of the target position j may be set to a value that is twice the y coordinate of the target position i.

[0088] FIG. 13 is a schematic diagram of the wheel loader 1 with the cutting edge 6a at target position k. Target position k is set as the position through which the cutting edge 6a of the bucket 6 will pass after passing target position j. The wheel loader 1 continues to travel backward from the time the cutting edge 6a of the bucket 6 passes target position j until it reaches target position k. From the time the cutting edge 6a of the bucket 6 passes target position j until it reaches target position k, the boom 14 continues to raise while keeping the bottom surface 6b of the bucket 6 parallel to the ground. The attitude of the bucket 6 with respect to the boom 14 changes to keep the bottom surface 6b of the bucket 6 parallel to the ground. When the cutting edge 6a moves from target position j to target position k, the wheel loader 1 travels backward and raises the bucket 6 simultaneously. Target position k is the position at which the raising operation of the boom 14 stops. Target position k is directly above reference point P.

[0089] When the cutting edge 6a of the bucket 6 is at the target position k, the boom 14 may be at the uppermost position. Dump trucks 300 onto which the load 310 is loaded come in a variety of sizes, and the ground clearance of the upper end of the side surface of the vessel 301 may vary depending on the size. The y coordinate of the target position k may be set so that the target position k is located above the upper end of the side surface of the vessel 301 for the dump truck 300 for which the ground clearance of the upper end of the side surface of the vessel 301 is greatest.

[0090] Figure 14 is a graph showing the change in cylinder length during loading work. The horizontal axis of Figure 14 represents the passage of time, and auxiliary lines are drawn at the times when the cutting edge 6a passes through target positions g, h, i, j, and k. The vertical axis of Figure 14 represents the lengths of the boom cylinder 16 and the bucket cylinder 19.

[0091] As shown in Figure 14 and Figures 7 and 8, the wheel loader 1 is traveling in reverse before the cutting edge 6a reaches target position g. The length of the boom cylinder 16 is constant, and therefore the attitude of the boom 14 relative to the vehicle body is constant. At this time, the height position of the boom 14 is at its highest. The length of the bucket cylinder 19 is constant, and therefore the attitude of the bucket 6 relative to the vehicle body is constant. While the cutting edge 6a moves from target position d to target position g, the wheel loader 1 is traveling in reverse while maintaining the bucket 6 in a fully dumped state.

[0092] Target position g is the position where the traveling direction of the wheel loader 1 switches from reverse to forward. Target position g is the position where tilting of the bucket 6 begins. As shown in FIG. 14 and FIGS. 8 and 9, the wheel loader 1 travels forward after the cutting edge 6a passes target position g until it reaches target position h. The length of the boom cylinder 16 is constant, and therefore the attitude of the boom 14 relative to the vehicle body is constant. Movement of the bucket 6 in the tilt direction begins when the cutting edge 6a reaches target position g, and the bucket 6 continues to move in the tilt direction until it reaches target position h. The length of the bucket cylinder 19 increases after the cutting edge 6a passes target position g until it reaches target position h.

[0093] While the cutting edge 6a moves from target position g to target position h, the wheel loader 1 travels forward while tilting the bucket 6. After loading of the load 310 into the dump truck 300 is complete, the wheel loader 1 tilts the bucket 6 while traveling forward to move the bucket 6 above the vessel 301. The attitude of the boom 14 remains constant while the bucket 6 is tilted. After unloading of the load 310 from the bucket 6 is complete, the boom 14 is held and the bucket 6 is tilted. During this tilting of the bucket 6, the wheel loader 1 travels forward, traveling in a direction approaching the vessel 301 of the dump truck 300.

[0094] Target position h is the position where the wheel loader 1 stops traveling. Target position h is the position where the lowering operation of the boom 14 starts. As shown in FIG. 14 and FIGS. 9 and 10, the wheel loader 1 stops traveling after the cutting edge 6a passes target position h until it reaches target position i. The length of the boom cylinder 16 is reduced, and therefore the boom 14 is lowered. If the length of the bucket cylinder 19 is kept constant while the boom 14 is lowering, the bucket 6 moves relative to the boom 14 in the tilt direction, so by reducing the length of the bucket cylinder 19 and performing a dumping operation on the bucket 6 relative to the boom 14, the bottom surface 6b of the bucket 6 is kept parallel to the ground.

[0095] Target position i is the position where the operation of the boom 14 switches from boom-down to boom-up. When the cutting edge 6a is at target position i, the work implement 3 has the bucket 6 lowered to the lowest position. As shown in FIG. 14 and FIGS. 10 and 12, the wheel loader 1 stops traveling after the cutting edge 6a passes target position i until it reaches target position j. The length of the boom cylinder is increased, and therefore the boom 14 is raised. If the length of the bucket cylinder 19 is kept constant while the boom 14 is raised, the bucket 6 moves relative to the boom 14 in the dumping direction; therefore, by increasing the length of the bucket cylinder 19 and tilting the bucket 6 relative to the boom 14, the bottom surface 6b of the bucket 6 is kept parallel to the ground.

[0096] Target position j is the position where the wheel loader 1 starts to travel backward. As shown in FIG. 14 and FIGS. 12 and 13, the wheel loader 1 travels backward after the cutting edge 6a passes target position j until it reaches target position k. The length of the boom cylinder continues to increase, and therefore the boom 14 continues to rise. By increasing the length of the bucket cylinder 19 and tilting the bucket 6 relative to the boom 14, the bottom surface 6b of the bucket 6 is kept parallel to the ground. The wheel loader 1 moves away from the dump truck 300 while performing the combined operations of traveling backward, raising the boom, and tilting the bucket.

[0097] Target position k is the position where the raising operation of the boom 14 stops. As shown in FIG. 14, after the cutting edge 6a passes target position k, the wheel loader 1 continues traveling backward. The length of the boom cylinder 16 is constant, and the attitude of the boom 14 relative to the vehicle body is constant. The length of the bucket cylinder 19 is constant, and the attitude of the bucket 6 relative to the boom 14 is constant. Therefore, the attitude of the bucket 6 relative to the vehicle body is constant.

[0098] By moving cutting edge 6a of bucket 6 so that it passes through target position d, target position g, target position h, target position i, target position j, and target position k in that order, it is possible to straighten out load 310 loaded into vessel 301 without causing bucket 6 or the vehicle body to come into contact with vessel 301. By applying automatic control that moves bucket 6 in this way to wheel loader 1, it is possible to achieve operation of work implement 3 that is equivalent to operation performed by a skilled operator.

[0099] Returning to Figure 5, the description of the loading operation under automatic control will continue. In step S103, the automation controller 100 recognizes the current positions of the wheel loader 1 and the work implement 3. The current position of the wheel loader 1 and the work implement 3 in the global coordinate system can be recognized by acquiring the current position of the vehicle body of the wheel loader 1 using the position information acquisition device 112 and acquiring the attitude of the work implement relative to the vehicle body using the boom angle sensor 123 and the bucket angle sensor 124. Based on the current positions of the wheel loader 1 and the work implement 3 and the current position of the dump truck 300 in the global coordinate system, the relative position of the cutting edge 6a of the bucket 6 with respect to the vessel 301 of the dump truck 300 can be calculated.

[0100] Alternatively, the perception device 111 may be used to obtain the direction and distance of a reference point P of the vessel 301 of the dump truck 300 relative to the location of the perception device 111, thereby calculating the current relative position of the cutting edge 6a of the bucket 6 relative to the reference point P.

[0101] From the current position of the work machine 3, the position of the cutting edge 6a of the bucket 6 relative to each of the target positions d, g, h, i, j, and k is recognized. For example, it is recognized that the cutting edge 6a has not yet reached target position d, that the cutting edge 6a has passed target position d and is between target position d and target position g, or that the cutting edge 6a has passed target position g and is between target position g and target position h. Furthermore, the target position to which the cutting edge 6a will next head is recognized. For example, if the cutting edge 6a has not yet reached target position d, the next target position is target position d, and if the cutting edge 6a is between target position d and target position g, the next target position is target position g.

[0102] In step S104, the automation controller 100 recognizes the length of the boom cylinder 16 and the length of the bucket cylinder 19 at the current position. The boom angle sensor 123 detects the angle of the boom 14. The bucket angle sensor 124 detects the angle of the bucket 6. The attitude of the work implement 3 is determined from the angle of the boom 14 and the angle of the bucket 6. The length of the boom cylinder 16 and the length of the bucket cylinder 19 at the current position are recognized based on the attitude of the work implement.

[0103] Instead of or in addition to boom angle sensor 123 and bucket angle sensor 124, an angle sensor that detects the angle of bell crank 18 and an angle sensor that detects the angle of link 15 may be provided. Boom cylinder 16 and bucket cylinder 19 may be provided with stroke sensors that detect the cylinder stroke lengths.

[0104] In step S105, the automation controller 100 calculates the difference between the length of the boom cylinder 16 and the length of the bucket cylinder 19 at the current position recognized in step S104 and the length of the boom cylinder 16 and the length of the bucket cylinder 19 at the target position to which the cutting edge 6a is next heading (hereinafter referred to as the target cylinder length). The automation controller 100 calculates how far the cylinder needs to be moved until the cutting edge 6a reaches the next target position.

[0105] In step S106, the automation controller 100 determines a target cylinder stroke speed that will result in the target cylinder length when the cutting edge 6a reaches the next target position. The automation controller 100 controls the boom cylinder 16 and the bucket cylinder 19 so that when the cutting edge 6a reaches the next target position, the work implement 3 assumes a target posture corresponding to that target position. The automation controller 100 can refer to the current vehicle speed. The current vehicle speed is acquired by the vehicle speed sensor 122. The time required to reach the next target position can be calculated from the current position of the cutting edge 6a and the current vehicle speed. The target cylinder stroke speed can be determined by dividing the difference in cylinder length calculated in step S105 by the time required to reach the next target position.

[0106] It is also possible to determine the amount of cylinder stroke while the wheel loader 1 travels a unit distance. The fact that the wheel loader 1 has traveled a unit distance can be determined from the vehicle speed, or can also be detected by the perception device 111.

[0107] In step S107, the automation controller 100 outputs a command current corresponding to the target cylinder stroke speed to the vehicle body controller 50. The automation controller 100 outputs a command to the work machine control unit 82 of the work machine controller 80 to extend and retract the boom cylinder 16 and the bucket cylinder 19 at the target cylinder stroke speed. The work machine control unit 82 outputs a command to the work machine EPC 143 to extend and retract the boom cylinder 16 and the bucket cylinder 19 at the target cylinder stroke speed.

[0108] In step S108, the work implement EPC 143 that has received the command signal adjusts the opening degree, thereby supplying appropriate hydraulic oil to the boom cylinder 16 and the bucket cylinder 19. As a result, the boom cylinder 16 and the bucket cylinder 19 operate.

[0109] In step S109, similar to step S104, the automation controller 100 recognizes the current lengths of the boom cylinder 16 and the bucket cylinder 19. The automation controller 100 determines whether the current lengths of the boom cylinder 16 and the bucket cylinder 19 have reached the target cylinder lengths.

[0110] If it is determined in step S109 that the target cylinder length has been reached (YES in step S109), the process proceeds to step S110, where the automation controller 100 determines whether or not there is a next target position.

[0111] If it is determined in step S109 that the target cylinder length has not been reached (NO in step S109), or if it is determined in step S110 that a next target position exists (YES in step S110), the process returns to step S103, and the process of extending and retracting the boom cylinder 16 and the bucket cylinder 19 based on the current position of the work implement 3 is repeated. The cylinder speed is changed successively according to the current position of the cutting edge 6a of the bucket 6. If the current position of the cutting edge 6a deviates from the position based on the cylinder speed set in the previous process, the cylinder speed is adjusted.

[0112] In the judgment of step S110, if it is determined that there is no next target position (NO in step S110), the loading operation ends. In this embodiment, this corresponds to the case where the next target position has not been set after the completion of target position k.

[0113] <Modification of the operation of the work machine 3 at the end of loading> Figure 15 is a first diagram showing a modified example of the operation of the work implement 3 at the end of loading. In the wheel loader 1 shown in Figure 15, the cutting edge 6a of the bucket 6 is at target position d. The work implement 3 (boom 14 and bucket 6) is in the same position in the wheel loader 1 shown in Figure 7 with the cutting edge 6a at target position d and the wheel loader 1 shown in Figure 15.

[0114] The vessel 301 shown in Fig. 15 has a larger load capacity than the vessel 301 shown in Fig. 6, and the height above the ground of the upper end of the side of the vessel 301 is higher than in Fig. 6. The target position d shown in Fig. 15 has a y coordinate with respect to the reference point P that is different from that of the target position d shown in Fig. 6. The target position d shown in Fig. 6 is set at a position where the y coordinate is on the positive side, whereas the target position d shown in Fig. 15 is set at a position where the y coordinate is on the negative side.

[0115] Figure 16 is a second diagram showing a modified example of the operation of the work implement 3 at the end of loading. If the wheel loader 1 travels backward from the attitude shown in Figure 15 while maintaining the attitude of the work implement 3 as explained with reference to Figures 7 and 8, the bucket 6 will come into contact with the side of the vessel 301, so a target position g1 is set whose y coordinate is different from that of target position d. Target position g1 is directly above reference point P. Target position g1 is set to a position on the positive y coordinate side.

[0116] From the time the cutting edge 6a of the bucket 6 passes target position d until it reaches target position g1, the wheel loader 1 travels backward, and the bucket 6 moves in the tilt direction. When the cutting edge 6a reaches target position g1, the movement of the bucket 6 in the tilt direction is stopped. When the cutting edge 6a of the bucket 6 is at target position g1, the bottom surface 6b of the bucket 6 is parallel to the ground. While the cutting edge 6a moves from target position d to target position g1, the wheel loader 1 travels backward while tilting the bucket 6.

[0117] After loading work into dump truck 300 has been completed, bucket 6 is tilted before cutting edge 6a of bucket 6 straddles the side surface of vessel 301, and bucket 6 is moved so as to avoid the side surface of vessel 301. This makes it possible to prevent cutting edge 6a and bottom surface 6b of bucket 6 from coming into contact with vessel 301, even when target position d is located lower than reference point P.

[0118] <Action and effect> Although some of the description overlaps with the above description, the characteristic configuration and effects of this embodiment can be summarized as follows.

[0119] As shown in Fig. 7, the bucket 6 is brought into a full dump state when the cutting edge 6a of the bucket 6 is located at a target position d above the vessel 301. When the bucket 6 is in a full dump position, the load in the bucket 6 falls from the bucket 6, and the work of loading the load into the vessel 301 is performed. As shown in Figs. 9 to 11, after the work of loading the load 310 into the vessel 301 is completed, the automation controller 100 operates the work equipment actuator to lower the bucket 6 above the vessel 301 until it contacts the load 310.

[0120] After the load 310 is loaded into the vessel 301, the work equipment actuator is operated to lower the bucket 6 above the vessel 301 until it contacts the load 310. The load 310 loaded into the vessel 301 is pushed from above by the bucket 6, and the shape of the load 310 is straightened. This makes it possible to prevent the load 310 from spilling out of the vessel 301 while the dump truck 300 is traveling.

[0121] 9 to 11, the automation controller 100 may lower the bucket 6 while maintaining the attitude of the bucket 6. If the bucket 6 makes unnecessary movements while in contact with the load 310, the load 310 may spill out of the vessel 301. By maintaining the attitude of the bucket 6 relative to the vessel 301 when pushing the load 310 with the bucket 6, it is possible to prevent the load 310 pushed by the bucket 6 from spilling out of the vessel 301.

[0122] 9 to 11, the automation controller 100 may lower the bucket 6 while keeping the bottom surface 6b of the bucket 6 parallel to the ground. By pushing the load 310 from above with the flat bottom surface 6b of the bucket 6, the load 310 can be reliably kept in a straight position.

[0123] 12 to 14, the automation controller 100 may raise the bucket 6 after completing the operation of lowering the bucket 6 above the vessel 301. After lowering the bucket 6 and pushing the load 310 from above to straighten the shape of the load 310, the bucket 6 is raised to separate the bucket 6 from the load 310 and the vessel 301 in which the load 310 is loaded. This makes it possible to prevent the bucket 6 from coming into contact with the vessel 301, and also to prevent the bucket 6 from rubbing against the load 310 as it moves, causing the shape of the load 310 to become distorted.

[0124] 12 to 14, the automation controller 100 may simultaneously perform reverse traveling to move the traveling device 4 away from the vessel 301 and the operation of raising the bucket 6. By performing the multiple operations of reverse traveling and the operation of raising the bucket 6 in a time-overlapping manner, the wheel loader 1 can move away from the dump truck 300 more quickly than when multiple operations are performed in sequence, such as starting reverse traveling after raising the bucket 6. This makes it possible to shorten the cycle time of the loading operation and improve workability.

[0125] 12 and 14, the automation controller 100 may perform an operation to raise the bucket 6 while traveling is stopped, and then perform the operations of reverse traveling and raising the bucket 6 simultaneously. If reverse traveling is started while the bucket 6 is lowered and pushing the load 310 from above, the bottom surface 6b of the bucket 6 may drag the load 310, causing the shape of the trimmed load 310 to become distorted. By raising the bucket 6 and moving the bucket 6 away from the load 310 before starting reverse traveling, it is possible to reliably prevent the shape of the trimmed load 310 from becoming distorted.

[0126] 7 and 8, the automation controller 100 may cause the traveling device 4 to travel in reverse away from the vessel 301 while the load 310 is being loaded into the vessel 301. By moving backward with the bucket 6 in a full dump state, if there is a load remaining in the bucket 6, an inertial force acts on the remaining load. This can promote the discharge of the load remaining in the bucket 6 from the bucket 6. Since the load loaded in the bucket 6 can be reliably discharged from the bucket 6, the loading operation can be completed reliably.

[0127] 10 and 11, with the bucket 6 at its lowest position above the vessel 301, the bucket 6 may be positioned directly above the center of the vessel 301 in the front-to-rear direction (left-to-right direction in the drawings) of the wheel loader 1. This makes it possible to more reliably push against the tops of the piles of loads 310 loaded on the vessel 301 with the bucket 6 from above, leveling the loads 310 and lowering the height of the piles of loads 310 to make it less likely for the loads 310 to spill out of the vessel 301.

[0128] The automation controller 100 constituting the automatic control system for the wheel loader 1 explained in the above embodiment does not necessarily have to be mounted on the wheel loader 1. A system may be configured in which a controller mounted on the wheel loader 1 processes information acquired by the external environment information acquisition unit 110 and the vehicle information acquisition unit 120, etc., to transmit the information to an external controller, and the external controller receiving the signal automatically controls the wheel loader 1. The external controller may be located at the work site of the wheel loader 1, or may be located in a remote location away from the work site of the wheel loader 1.

[0129] In the embodiment, an example has been described in which the wheel loader 1 is equipped with a cab 5 and is a manned vehicle in which an operator rides in the cab 5. The wheel loader 1 may be an unmanned vehicle. The wheel loader 1 does not have to be equipped with a cab 5 for an operator to ride in and operate. The wheel loader 1 does not have to be equipped with a control function by an operator on board. The wheel loader 1 may be a work machine exclusively for remote control. The wheel loader 1 may be controlled by a radio signal from a remote control device.

[0130] In the embodiment, an example has been described in which the wheel loader 1 performs the work of loading the load 310 onto the vessel 301, and after the loading work is completed, the wheel loader 1 pushes the load 310 from above with the bucket 6. The loading machine that performs the work of loading the load 310 onto the vessel 301 and the work machine that performs the load pushing, that is, pushing the load 310 loaded onto the vessel 301 from above, may be separate work machines. The work machine that performs the load pushing is not limited to the wheel loader 1, and may be a backhoe, a loading shovel, or the like.

[0131] <Additional Notes> The above description includes the following additional features.

[0132] (Appendix 1) a work machine having an attachment at its tip; a work machine actuator that drives the work machine; a controller that operates the work machine actuator to lower the attachment above the container after loading of the container into the load is completed.

[0133] (Appendix 2) 2. The work machine of claim 1, wherein the controller lowers the attachment while maintaining the attitude of the attachment.

[0134] (Appendix 3) the attachment is a bucket having a bottom surface; 3. The work machine of claim 2, wherein the controller lowers the bucket while keeping the bottom surface parallel to the ground.

[0135] (Appendix 4) 4. The work machine according to any one of Supplementary Note 1 to Supplementary Note 3, wherein the controller raises the attachment after completing the operation of lowering the attachment.

[0136] (Appendix 5) Further provided with a running body, The work machine according to claim 4, wherein the controller simultaneously performs the operation of moving the traveling body away from the container and the operation of raising the attachment.

[0137] (Appendix 6) The work machine according to claim 5, wherein the controller performs an operation to raise the attachment while the traveling body is stopped, and then performs an operation to cause the traveling body to travel and an operation to raise the attachment simultaneously.

[0138] (Appendix 7) Further provided with a running body, The work machine according to any one of Supplementary Note 1 to Supplementary Note 6, wherein the controller controls the traveling body to move away from the container during the loading operation.

[0139] (Appendix 8) 8. The work machine of any one of Supplementary Notes 1 to 7, wherein the attachment is positioned directly above the center of the container in a fore-and-aft direction of the work machine when the attachment is in its lowest position above the container.

[0140] The embodiments disclosed herein are to be considered in all respects as illustrative and not restrictive. The scope of the present invention is defined not by the above description but by the claims, and it is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0141] 1 Wheel loader, 2 Body frame, 2a Front frame, 2b Rear frame, 3 Work implement, 4 Traveling device, 4a, 4b Traveling wheels, 5 Cab, 6 Bucket, 6a Cutting edge, 6b Bottom, 8 Operating device, 9 Boom pin, 11 Steering cylinder, 13 Work implement pump, 14 Boom, 15 Link, 16 Boom cylinder, 17 Bucket pin, 18 Bell crank, 18a Support pin, 18b, 18c Connecting pin, 19 Bucket cylinder, 21 Engine, 23 Transmission, 25 Axle, 32 Main valve, 35, 36, 140 Electromagnetic proportional control valve, 41 Accelerator pedal, 42 Work implement operation lever, 50 Body controller, 51 Machine monitor, 60 Engine controller, 70 Transmission controller, 71 Brake control unit, 72 Accelerator control unit, 80 Work implement controller, 81 Steering control unit, 82 work machine control unit, 100 automation controller, 101 position estimation unit, 102 path planning unit, 103 path following control unit, 110 external information acquisition unit, 111 perception device, 112 position information acquisition device, 120 vehicle body information acquisition unit, 121 articulation angle sensor, 122 vehicle speed sensor, 123 boom angle sensor, 124 bucket angle sensor, 125 boom cylinder pressure sensor, 130 interface, 131 automation changeover switch, 132 engine emergency stop switch, 133 mode lamp, 141 brake EPC, 142 steering EPC, 143 work machine EPC, 300 dump truck, 301 vessel, 310 load.

Claims

1. a work machine having an attachment at its tip; a work machine actuator that drives the work machine; a controller that, after loading of the load into the container is completed, operates the work machine actuator to lower the attachment above the container until it contacts the load.

2. The work machine according to claim 1 , wherein the controller lowers the attachment while maintaining the attitude of the attachment.

3. the attachment is a bucket having a bottom surface; The work machine of claim 2 , wherein the controller lowers the bucket while keeping the bottom surface parallel to the ground.

4. The work machine of claim 1 , wherein the controller raises the attachment after completing the operation of lowering the attachment.

5. Further provided with a running body, The work machine according to claim 4 , wherein the controller simultaneously performs the operation of moving the traveling body away from the container and the operation of lifting the attachment.

6. The work machine according to claim 5 , wherein the controller performs an operation to raise the attachment while the traveling body is stopped, and then performs an operation to cause the traveling body to travel and an operation to raise the attachment simultaneously.

7. Further provided with a running body, The work machine according to claim 1 , wherein the controller controls the traveling body to move away from the container during the loading operation.

8. The work machine according to claim 1 , wherein the attachment is positioned directly above the center of the container in the longitudinal direction of the work machine when the attachment is lowered to its lowest position above the container.

9. a work machine having an attachment at its tip; a work machine actuator that drives the work machine; and a controller that, after loading of the load into the container is completed, operates the work machine actuator to lower the attachment above the container until it contacts the load.

10. Loading the container, After loading of the load into the container is completed, an attachment at the tip of a working implement of the work machine is lowered above the container until it contacts the load.

Images