JP2025033951A - Soil quality discrimination system and soil quality discrimination method - Google Patents

Abstract

To provide a system that can effectively utilize data acquired during work.SOLUTION: A soil property discrimination system includes a work machine having a work device, an acquisition section acquiring operation data related to an operation of the work device during an excavation work in which the work device excavates an excavation target, and a controller 50 discriminating soil property from the operation data based on a correspondence between the operation data and a soil property of the excavation target.SELECTED DRAWING: Figure 4

Description

This disclosure relates to a soil type discrimination system and a soil type discrimination method.

JP 2020-173150 A (Patent Document 1) discloses a soil quality determination device mounted on a construction machine. The soil quality determination device includes a storage unit that stores a learning model constructed by machine learning for determining the soil quality of soil captured in an image, and a determination unit that uses a camera image of the soil captured by a camera mounted on the construction machine and the learning model to determine the soil quality of the soil captured in the camera image in real time while the camera is capturing the image.

JP 2019-163621 A (Patent Document 2) describes that the hardness of the ground is estimated based on the sensor detection value when a predetermined operation is performed in which the attachment contacts the ground at a predetermined speed and a predetermined angle, and on data in which the sensor detection value when the predetermined operation is performed is associated with the hardness of the ground.

JP 2020-173150 A JP 2019-163621 A

The introduction of work machines equipped with ICT (information and communication technology) functions is progressing. The amount of data that can be acquired while the work machines are operating is increasing. It is hoped that this data can be used to improve the productivity of the work machines.

This disclosure proposes a system and method that can effectively utilize data acquired during work.

The soil type discrimination system according to the present disclosure includes a work machine having a work implement, an acquisition unit that acquires operation data related to the operation of the work implement during an excavation operation in which the work implement is used to excavate an excavation target, and a controller that discriminates the soil type from the operation data based on the correspondence between the operation data and the soil type of the excavation target.

The soil type discrimination method according to the present disclosure comprises the following steps. The first step is to acquire operation data related to the operation of the work machine during an excavation operation in which the work machine excavates an excavation target. The second step is to discriminate the soil type from the operation data based on the correspondence between the operation data and the soil type of the excavation target.

The present disclosure makes it possible to realize a system and method that can easily estimate the soil quality of the excavation target from data acquired during excavation work.

FIG. 1 is a side view showing a schematic configuration of a work machine. 1 is a block diagram showing a schematic configuration of a system of a work machine. FIG. 4 is a diagram illustrating an example of the relationship between engine speed and torque. FIG. 2 is a diagram showing functional blocks in a main controller. FIG. 2 is a schematic diagram showing the configuration of a simplified N-value meter. FIG. 11 is a first diagram showing an example of a correspondence relationship between operation data and soil type. FIG. 11 is a second diagram showing an example of the correspondence between operation data and soil type. FIG. 13 is a third diagram showing an example of the correspondence between operation data and soil type. FIG. 4 is a fourth diagram showing an example of the correspondence between operation data and soil type. FIG. 4 is a side view of the work machine showing the posture when starting a dedicated soil type discrimination operation. FIG. 5 is a fifth diagram showing an example of the correspondence between operation data and soil type. FIG. 13 is a diagram showing an example of the progress of cutting edge speed during excavation work. FIG. 6 is a sixth diagram showing an example of the correspondence between operation data and soil type. FIG. 2 is a schematic diagram showing a bucket penetrating into the ground. FIG. 7 is a seventh diagram showing an example of the correspondence between operation data and soil type. FIG. 8 is an eighth figure showing an example of the correspondence between operation data and soil type. FIG. 9 is a ninth diagram showing an example of the correspondence between operation data and soil type. FIG. 10 is a tenth diagram showing an example of the correspondence between operation data and soil type.

The following describes the embodiments with reference to the drawings. In the following description, identical parts and components are given the same reference numerals. Their names and functions are also the same. Therefore, detailed descriptions of these will not be repeated. It is also intended from the outset that any configuration may be extracted from the embodiments and that they may be combined in any manner.

<Configuration of the work machine>
Fig. 1 is a side view showing a schematic configuration of a hydraulic excavator 100 as an example of a work machine based on the present disclosure. As shown in Fig. 1, the hydraulic excavator 100 of this embodiment mainly has a traveling body 1, a rotating body 2, and a work implement 3. The traveling body 1 and the rotating body 2 form the body of the hydraulic excavator 100.

The running body 1 has a pair of left and right track devices 1a. Each of the pair of left and right track devices 1a has a travel motor 1b and tracks. The travel motor 1b is provided as a drive source for the running body 1. The travel motor 1b is a hydraulic motor that is driven by hydraulic pressure. The travel motor 1b drives and rotates the pair of left and right tracks, causing the hydraulic excavator 100 to self-propel.

The rotating body 2 is disposed on top of the running body 1 and is supported by the running body 1. The rotating body 2 mainly has a driver's room (cab) 2a, a driver's seat 2b, an engine room 2c, a counterweight 2d, and a swing motor 2e. The driver's room 2a is disposed, for example, on the front left side (front side of the vehicle) of the rotating body 2. A driver's seat 2b for an operator to sit in is disposed in the internal space of the driver's room 2a.

The engine room 2c and the counterweight 2d are each located on the rear side of the rotating body 2 (rear side of the vehicle) relative to the driver's cab 2a. The engine room 2c houses the engine unit (engine, exhaust treatment structure, etc.). The upper part of the engine room 2c is covered by an engine hood. The counterweight 2d is located behind the engine room 2c.

The swivel body 2 is attached to the running body 1 via a swivel circle section. The swivel circle section has a roughly circular ring shape and has internal teeth for rotation on its inner circumferential surface. A pinion that meshes with these internal teeth is attached to the swivel motor 2e. The swivel body 2 can rotate relative to the running body 1 as the driving force is transmitted from the swivel motor 2e to rotate the swivel circle section. The swivel motor 2e is a hydraulic motor that is driven by hydraulic pressure. The swivel motor 2e may also be an electric motor.

The vibration sensor 2f is mounted on the frame of the rotating body 2. The vibration sensor 2f detects vibrations occurring in the rotating body 2.

The working machine 3 is journaled on the front side of the rotating body 2, for example on the right side of the cab 2a. The working machine 3 has, for example, a boom 3a, an arm 3b, a bucket 3c, a boom cylinder 4a, an arm cylinder 4b, a bucket cylinder 4c, etc. The base end (one end) of the boom 3a is rotatably connected to the rotating body 2 by a boom bottom pin 5a. The base end (one end) of the arm 3b is rotatably connected to the tip end (other end) of the boom 3a by a boom top pin 5b. The bucket 3c (one end) is rotatably connected to the tip end (other end) of the arm 3b by an arm top pin 5c.

The bucket 3c is disposed at the tip of the work machine 3. The tip of the bucket 3c is called the cutting edge 3ca. The bottom surface 3cb is part of the outer surface of the bucket 3c. The bottom surface 3cb is formed as a flat surface.

In this embodiment, the positional relationship of each part of the hydraulic excavator 100 will be explained with reference to the work machine 3.

The boom 3a of the work machine 3 rotates around the boom bottom pin 5a relative to the revolving body 2. The trajectory of the movement of a specific part of the boom 3a that rotates relative to the revolving body 2, for example the tip of the boom 3a, is an arc, and a plane that includes the arc is specified. When the hydraulic excavator 100 is viewed from above, the plane is expressed as a straight line. The direction in which this straight line extends is the front-rear direction of the body of the hydraulic excavator 100, or the front-rear direction of the revolving body 2, and is also simply referred to as the front-rear direction below. The left-right direction (vehicle width direction) of the body of the hydraulic excavator 100, or the left-right direction of the revolving body 2, is a direction perpendicular to the front-rear direction in a plan view, and is also simply referred to as the left-right direction below. The up-down direction of the body of the hydraulic excavator 100, or the up-down direction of the revolving body 2, is a direction perpendicular to the plane defined by the front-rear direction and the left-right direction, and is also simply referred to as the up-down direction below.

In the front-to-rear direction, the side where the work machine 3 protrudes from the vehicle body is the front direction, and the opposite direction to the front direction is the rear direction. Looking forward, the right and left sides in the left-right direction are the right direction and the left direction, respectively. In the up-down direction, the side with the ground is the bottom side, and the side with the sky is the top side.

The front-to-rear direction refers to the front-to-rear direction of the operator seated in the driver's seat 2b in the driver's cab 2a. The left-to-right direction refers to the left-to-right direction of the operator seated in the driver's seat 2b. The up-to-down direction refers to the up-to-down direction of the operator seated in the driver's seat 2b. The direction facing the operator seated in the driver's seat 2b is the forward direction, and the direction behind the operator seated in the driver's seat 2b is the rearward direction. The right and left sides of the operator seated in the driver's seat 2b when facing directly ahead are the right and left directions, respectively. The side near the feet of the operator seated in the driver's seat 2b is the down side, and the side above the operator's head is the up side.

The boom 3a can be driven by a boom cylinder (boom hydraulic cylinder) 4a. This drive allows the boom 3a to rotate vertically relative to the rotating body 2 around the boom bottom pin 5a. The arm 3b can be driven by an arm cylinder (arm hydraulic cylinder) 4b. This drive allows the arm 3b to rotate vertically relative to the boom 3a around the boom top pin 5b. The bucket (attachment) 3c can be driven by a bucket cylinder (attachment hydraulic cylinder) 4c. This drive allows the bucket 3c to rotate vertically relative to the arm 3b around the arm top pin 5c. In this manner, the work machine 3 can be driven.

The boom bottom pin 5a is supported by the body of the hydraulic excavator 100. The boom bottom pin 5a is supported by a pair of vertical plates (not shown) of the frame of the rotating body 2. The boom top pin 5b is attached to the tip of the boom 3a. The arm top pin 5c is attached to the tip of the arm 3b. The boom bottom pin 5a, the boom top pin 5b, and the arm top pin 5c all extend in the left-right direction. The boom bottom pin 5a is also called the boom foot pin.

The work machine 3 has a bucket link 3d. The bucket link 3d has a first link member 3da and a second link member 3db. The tip of the first link member 3da and the tip of the second link member 3db are connected via a bucket cylinder top pin 3dc so as to be capable of relative rotation. The bucket cylinder top pin 3dc is connected to the tip of the bucket cylinder 4c. Therefore, the first link member 3da and the second link member 3db are pin-connected to the bucket cylinder 4c.

The base end of the first link member 3da is rotatably connected to the arm 3b by the first link pin 3dd. The base end of the second link member 3db is rotatably connected to a bracket at the base of the bucket 3c by the second link pin 3de.

A pressure sensor 6a is attached to the head side of the boom cylinder 4a. The pressure sensor 6a can detect the pressure (head pressure) of the hydraulic oil in the cylinder head side oil chamber 40A of the boom cylinder 4a. A pressure sensor 6b is attached to the bottom side of the boom cylinder 4a. The pressure sensor 6b can detect the pressure (bottom pressure) of the hydraulic oil in the cylinder bottom side oil chamber 40B of the boom cylinder 4a. The pressure sensors 6a and 6b output hydraulic oil pressure information consisting of the head pressure and bottom pressure to the main controller 50 described below.

A pressure sensor 6c is attached to the head side of the arm cylinder 4b. The pressure sensor 6c can detect the pressure of hydraulic oil in the cylinder head side oil chamber of the arm cylinder 4b (head pressure). A pressure sensor 6d is attached to the bottom side of the arm cylinder 4b. The pressure sensor 6d can detect the pressure of hydraulic oil in the cylinder bottom side oil chamber of the arm cylinder 4b (bottom pressure). The pressure sensors 6c and 6d output hydraulic oil pressure information consisting of the head pressure and bottom pressure to the main controller 50 described below.

A pressure sensor 6e is attached to the head side of the bucket cylinder 4c. The pressure sensor 6e can detect the pressure of the hydraulic oil in the cylinder head side oil chamber of the bucket cylinder 4c (head pressure). A pressure sensor 6f is attached to the bottom side of the bucket cylinder 4c. The pressure sensor 6f can detect the pressure of the hydraulic oil in the cylinder bottom side oil chamber of the bucket cylinder 4c (bottom pressure). The pressure sensors 6e and 6f output hydraulic oil pressure information consisting of the head pressure and bottom pressure to the main controller 50 described below.

The boom 3a, arm 3b and bucket 3c are provided with position sensors to obtain information on their respective positions and attitudes. The position sensors output boom information, arm information and attachment information to obtain the respective positions of the boom 3a, arm 3b and bucket 3c to the main controller 50, which will be described later.

A stroke sensor 7a is attached to the boom cylinder 4a as a position sensor. The stroke sensor 7a detects the amount of displacement of the cylinder rod 4ab relative to the cylinder 4aa in the boom cylinder 4a as boom information. A stroke sensor 7b is attached to the arm cylinder 4b as a position sensor. The stroke sensor 7b detects the amount of displacement of the cylinder rod in the arm cylinder 4b as arm information. A stroke sensor 7c is attached to the bucket cylinder 4c as a position sensor. The stroke sensor 7c detects the amount of displacement of the cylinder rod in the bucket cylinder 4c as attachment information.

The position sensor may be an angle sensor. An angle sensor 9a is attached around the boom bottom pin 5a. An angle sensor 9b is attached around the boom top pin 5b. An angle sensor 9c is attached around the arm top pin 5c. The angle sensors 9a, 9b, and 9c may be potentiometers or rotary encoders. The angle sensors 9a, 9b, and 9c output rotation angle information (boom information, arm information, and attachment information) of the boom 3a and the like to the main controller 50 described below.

As shown in FIG. 1, the angle between a straight line passing through the boom bottom pin 5a and the boom top pin 5b (shown by a two-dot chain line in FIG. 1) and a straight line extending in the vertical direction (shown by a dashed line in FIG. 1) in a side view is the boom angle θb. The boom angle θb is usually an acute angle. The boom angle θb represents the angle of the boom 3a relative to the rotating body 2. The boom angle θb can be calculated from the detection result of the stroke sensor 7a, and can also be calculated from the measurement value of the angle sensor 9a.

In a side view, the angle between a straight line passing through the boom bottom pin 5a and the boom top pin 5b and a straight line passing through the boom top pin 5b and the arm top pin 5c (shown by a two-dot chain line in Figure 1) is the arm angle θa. The arm angle θa represents the angle of the arm 3b relative to the boom 3a in the area in which the arm 3b rotates in a side view. The arm angle θa can be calculated from the detection result of the stroke sensor 7b, and can also be calculated from the measurement value of the angle sensor 9b.

In a side view, the angle between a line passing through the boom top pin 5b and the arm top pin 5c and a line passing through the arm top pin 5c and the cutting edge of the bucket 3c (shown by a two-dot chain line in Figure 1) is the bucket angle θk. The bucket angle θk represents the angle of the bucket 3c relative to the arm 3b in the area where the bucket 3c rotates in a side view. The bucket angle θk can be calculated from the detection results of the stroke sensor 7c, and can also be calculated from the measurement values of the angle sensor 9c.

The position sensor may be an IMU (Inertial Measurement Unit). IMUs 8a, 8b, 8c, and 8d are attached to the rotating body 2, the boom 3a, the arm 3b, and the first link member 3da, respectively. IMU 8a measures the acceleration of the rotating body 2 in the forward/backward, left/right, and up/down directions, and the angular velocity of the rotating body 2 about the forward/backward, left/right, and up/down directions. IMUs 8b, 8c, and 8d measure the acceleration of the boom 3a, the arm 3b, and the first link member 3da in the forward/backward, left/right, and up/down directions, and the angular velocity of the boom 3a, the arm 3b, and the first link member 3da about the forward/backward, left/right, and up/down directions, respectively.

The acceleration of the boom cylinder 4a (the change in the extension/retraction speed of the boom cylinder 4a) can be obtained based on the difference between the acceleration measured by the IMU 8a attached to the rotating body 2 and the acceleration measured by the IMU 8b attached to the boom 3a. The boom angle θb, arm angle θa, and bucket angle θk may be calculated from the detection results of the IMUs 8b, 8c, and 8d, respectively.

Although the position sensors mentioned above include stroke sensors for each hydraulic cylinder, angle sensors for each link such as the boom 3a, and an IMU, the position sensor may also be a six-axis acceleration sensor. The position sensor may also be a combination of several of the above sensors. The position sensor may also be a combination of the above sensors and a Global Navigation Satellite System (GNSS).

<Overall configuration of the work machine system>
Next, the schematic configuration of the system of the work machine will be described with reference to Fig. 2. Fig. 2 is a block diagram showing the schematic configuration of the system of the work machine shown in Fig. 1.

As shown in FIG. 2, the system in this embodiment includes a hydraulic excavator 100 as an example of a work machine shown in FIG. 1, and a main controller 50 shown in FIG. 2.

The engine 31 is, for example, a diesel engine. The output shaft of the engine 31 is connected to the hydraulic pump 34. The engine 31 generates a driving force that rotates the hydraulic pump 34. The governor 32 adjusts the amount of fuel injected by the fuel injection device in the engine 31.

The engine controller 41 adjusts the rotation speed of the engine 31 by outputting a command value for the fuel injection amount based on the command rotation speed of the engine 31 to the governor 32 and controlling the amount of fuel injected by the fuel injection device. A rotation sensor 33 is provided on the output shaft of the engine 31. The rotation sensor 33 detects the rotation speed of the engine 31. The rotation sensor 33 outputs the detection result of the rotation speed of the engine 31 to the engine controller 41.

The hydraulic pump 34 is driven by the rotational driving force of the engine 31, and discharges pressurized oil to generate hydraulic pressure to drive the hydraulic actuators. The hydraulic actuators include hydraulic cylinders also shown in FIG. 1, namely, the boom cylinder 4a, the arm cylinder 4b, and the bucket cylinder 4c, and hydraulic motors also shown in FIG. 1, namely, the travel motor 1b and the swing motor 2e. The hydraulic actuators are connected to the hydraulic pump 34 via the operating valve 35.

The hydraulic pump 34 is a variable displacement hydraulic pump that has, for example, a swash plate and changes the discharge capacity by changing the tilt angle of the swash plate. A swash plate drive device 39 is connected to the hydraulic pump 34. The swash plate drive device 39 changes the tilt angle of the swash plate of the hydraulic pump 34. The pressure sensor 36 detects the pressure of the oil discharged from the hydraulic pump 34. The pressure sensor 36 outputs the detection result of the hydraulic pressure to the pump controller 42. A portion of the oil discharged from the hydraulic pump 34 is supplied to the operation valve 35 as hydraulic oil. A portion of the oil discharged from the hydraulic pump 34 is reduced to a constant pressure by the self-pressure reducing valve 37 and used as pilot oil.

The control valve 35 is, for example, a spool-type valve that moves a rod-shaped spool to switch the direction of hydraulic oil flow. The amount of hydraulic oil supplied to the hydraulic actuator is adjusted by the axial movement of the spool. The control valve 35 is provided with a stroke sensor 35a that detects the movement distance of the spool (spool stroke). By controlling the supply and discharge of hydraulic pressure to the hydraulic actuator, the operation of the work machine 3, the rotation of the revolving body 2, and the traveling operation of the traveling body 1 are controlled.

In this example, the oil supplied to the hydraulic actuator to operate the hydraulic actuator is called hydraulic oil. Also, the oil supplied to the operating valve 35 to operate the spool of the operating valve 35 is called pilot oil. Also, the pressure of the pilot oil is called pilot oil pressure.

The hydraulic pump 34 may be one that delivers both hydraulic oil and pilot oil as described above. The hydraulic pump 34 may have a separate hydraulic pump (main hydraulic pump) that delivers hydraulic oil and a separate hydraulic pump (pilot hydraulic pump) that delivers pilot oil.

An EPC (electromagnetic proportional control) valve 38 is provided in the pilot oil path. The EPC valve 38 outputs pilot oil pressure to the control valve 35 according to a command current from the main controller 50. The control valve 35 controls the hydraulic actuator according to the pilot oil pressure.

The engine controller 41 and the pump controller 42 are mounted on the hydraulic excavator 100. The engine controller 41 and the pump controller 42 are electrically connected and can transmit and receive information to and from each other. The engine controller 41 and the pump controller 42 are also electrically connected to the main controller 50.

The main controller 50 is a controller that controls the entire hydraulic excavator 100, and is composed of a CPU (Central Processing Unit), a non-volatile memory, a timer, etc. The main controller 50 controls the engine controller 41 and the pump controller 42.

The main controller 50 may be mounted on the hydraulic excavator 100. The main controller 50 may be installed outside the hydraulic excavator 100. The main controller 50 may be located at the work site of the hydraulic excavator 100, or may be located in a remote location away from the work site of the hydraulic excavator 100. The main controller 50 may be, for example, a computer, a server, a mobile terminal, etc.

The operating device 25 is disposed in the cab 2a (Figure 1). The operating device 25 is operated by an operator. The operating device 25 accepts an operator operation to drive the work machine 3. The operating device 25 also accepts an operator operation to rotate the rotating body 2. The operating device 25 is, for example, an electric operating device, and has an operating lever 25a and an operation amount sensor 25b.

The control lever 25a is operated by an operator. The operation amount sensor 25b detects the operation of the control lever 25a by the operator. The operation amount sensor 25b is, for example, a potentiometer or a Hall element. The operation amount sensor 25b outputs the detection result of the operation of the control lever 25a to the main controller 50. The main controller 50 controls the EPC valve 38 based on the operation command from the operating device 25 to drive the hydraulic actuator.

The operating device 25 is not limited to an electrical type, and may be a pilot hydraulic operating device. If the operating device 25 is a pilot hydraulic operating device, the operation of the operating lever 25a is detected, for example, by a pressure sensor that detects the pressure of the pilot oil.

Detection signals from the stroke sensors 7a-7c, IMUs 8a-8d, angle sensors 9a-9c, pressure sensors 6a-6f, and vibration sensor 2f are also input to the main controller 50. The main controller 50 may be electrically connected to each sensor by wires, or may be capable of wireless communication.

The main controller 50, as will be described in detail below, determines the soil type of the object to be excavated by the hydraulic excavator 100. The main controller 50 outputs the soil type determination result to the output unit 60. The output unit 60 may be hardware such as a monitor or a printer. The output unit 60 may be mounted on the hydraulic excavator 100. The output unit 60 may be an external controller disposed outside the hydraulic excavator 100. The external controller may be a computer, a server, a mobile terminal, etc. The external controller may be a computer that constitutes a construction management system.

The engine 31 speed detected by the rotation sensor 33 is input to the engine controller 41. Either the engine controller 41, the pump controller 42, or the main controller 50 calculates the output torque of the engine 31 according to the engine 31 speed and the torque absorbed by the hydraulic pump 34. Figure 3 shows an example of the relationship between engine speed and torque.

As shown in FIG. 3, the higher the rotation speed of the engine 31, the smaller the output torque of the engine 31. On the other hand, the hydraulic pump 34 generates an absorption torque according to the rotation speed of the engine 31, and the higher the rotation speed of the engine 31, the greater the torque absorbed by the hydraulic pump 34.

Therefore, when the rotation speed of the engine 31 increases, the output torque of the engine 31 decreases and the absorption torque by the hydraulic pump 34 increases, so the rotation speed of the engine 31 starts to decrease. On the other hand, when the rotation speed of the engine 31 decreases, the output torque of the engine 31 increases and the absorption torque by the hydraulic pump 34 decreases, so the rotation speed of the engine 31 starts to increase. By repeating this, the engine 31 and the hydraulic pump 34 operate stably at the matching point where the rotation speed of the engine 31, the output torque of the engine 31, and the rotation speed and absorption torque of the hydraulic pump 34 match.

<Functional blocks in the main controller 50>
Next, the functional blocks in the main controller 50 will be described with reference to Fig. 4. Fig. 4 is a diagram showing the functional blocks in the main controller 50 shown in Fig. 2.

The detection results of the stroke sensors 7a-7c, IMUs 8a-8d, angle sensors 9a-9c, etc., which make up the position sensor, are input to the main controller 50. The work machine attitude acquisition unit 56 acquires the attitude of the work machine 3 based on the detection results of the position sensors. The work machine attitude acquisition unit 56 acquires the trajectory of the cutting edge 3ca of the bucket 3c during excavation work from the attitude of the work machine 3 at each point in time during excavation work.

The earthwork volume calculation unit 51 calculates the weight (payload) of the load L (FIG. 1) loaded on the bucket 3c based on the difference between the head pressure of the boom cylinder 4a detected by the pressure sensor 6a and the bottom pressure of the boom cylinder 4a detected by the pressure sensor 6b. The earthwork volume calculation unit 51 recognizes the change in the pressure difference between the head pressure and the bottom pressure of the boom cylinder 4a relative to the posture of the work implement 3, and calculates the weight of the load L loaded on the bucket 3c by referring to a data table that indicates the load that the bucket 3c is carrying in that posture of the work implement 3. The data table is stored in the memory unit 59.

The excavation time calculation unit 57 receives an input of the detection result of the operation content of the operation lever 25a from the operation amount sensor 25b. The excavation time calculation unit 57 grasps the time when the command to drive the arm 3b in the excavation direction is started and the time when the command to drive the arm 3b in the excavation direction is stopped. The excavation time calculation unit 57 may calculate the time when the command to drive the arm 3b in the excavation direction is issued, and the calculated time may be the excavation time.

The excavation time calculation unit 57 may use the posture of the work machine 3 acquired by the work machine posture acquisition unit 56 to calculate the time required for the work machine 3 to move from the starting point to the end point, taking the time when a predefined excavation start posture of the work machine 3 is detected as the starting point and the time when a predefined excavation end posture of the work machine 3 (for example, the posture when the bucket 3c has finished holding the load L) as the end point, and may treat the calculated time as the excavation time. The excavation start posture and excavation end posture of the work machine 3 are stored in the memory unit 59.

The excavation time calculation unit 57 may use the posture of only the bucket 3c acquired by the work machine posture acquisition unit 56 to calculate the time required for the bucket 3c to move from the start point to the end point, with the time when the excavation start posture of the bucket 3c is detected as the start point and the excavation end posture of the bucket 3c as the end point, and may take the calculated time as the excavation time. The excavation start posture and excavation end posture of the bucket 3c are stored in the memory unit 59.

The work machine attitude acquisition unit 56 acquires the position of the cutting edge 3ca of the bucket 3c based on input from the position sensor. The cutting edge speed calculation unit 52 acquires the time-series position of the cutting edge 3ca from the start of excavation to the end of excavation. The cutting edge speed calculation unit 52 obtains the speed of the cutting edge 3ca by differentiating the time-series position coordinates of the cutting edge 3ca, and calculates the average of these speeds as the average speed of the cutting edge 3ca during excavation work.

The cutting edge speed calculation unit 52 may calculate the distance traveled by the cutting edge 3ca during excavation work from the position of the cutting edge 3ca of the bucket 3c at the start of excavation and the position of the cutting edge 3ca at the end of excavation, and may calculate the average speed of the cutting edge 3ca during excavation work by dividing the distance traveled by the excavation time.

The efficiency calculation unit 53 calculates the amount of earthwork per unit time by dividing the payload calculated by the earthwork amount calculation unit 51 by the excavation time calculated by the excavation time calculation unit 57, and regards this as the work efficiency of the excavation work. The efficiency calculation unit 53 also acquires the fuel injection amount commanded to the governor 32 from the engine controller 41. The efficiency calculation unit 53 calculates the amount of earthwork per unit supply of fuel to the engine 31 by dividing the payload calculated by the earthwork amount calculation unit 51 by the amount of fuel supplied to the engine 31 during the excavation work, and regards this as the fuel efficiency of the excavation work.

The blade load calculation unit 54 calculates the thrust of the boom cylinder 4a based on the head pressure and bottom pressure of the boom cylinder 4a detected by the pressure sensors 6a and 6b. The blade load calculation unit 54 calculates the thrust of the arm cylinder 4b based on the head pressure and bottom pressure of the arm cylinder 4b detected by the pressure sensors 6c and 6d. The blade load calculation unit 54 calculates the thrust of the bucket cylinder 4c based on the head pressure and bottom pressure of the bucket cylinder 4c detected by the pressure sensors 6e and 6f.

The blade load calculation unit 54 can calculate the load on the blade tip 3ca of the bucket 3c from the thrust of each cylinder and the moment of the positional relationship of the work machine 3 based on the detection results of the position sensor.

The work machine attitude acquisition unit 56 acquires the attitude of the bucket 3c based on the detection results of the position sensor. The penetration amount calculation unit 55 recognizes the position of the bucket 3c relative to the ground surface. The penetration amount calculation unit 55 calculates the area of the bucket 3c that has penetrated into the ground when viewed from the side. The penetration amount calculation unit 55 calculates the volume of the bucket 3c that has penetrated into the ground by multiplying the area of the bucket 3c that has penetrated into the ground by the width of the bucket 3c. The penetration amount calculation unit 55 regards the calculated volume of the bucket 3c as the apparent amount of soil scooped into the bucket 3c.

The soil type determination unit 58 determines the soil type of the excavation target from at least one of the following: the speed of the cutting edge 3ca, the load on the cutting edge 3ca, the weight of the load L loaded in the bucket 3c, the fuel efficiency of the excavation work, the work efficiency of the excavation work, the trajectory of the cutting edge 3ca, the operation of the operating lever 25a, and the volume of the bucket 3c penetrated into the ground.

Operation data related to the operation of the work machine 3 during excavation work in which the work machine 3 excavates the excavation target includes the attitude of the work machine 3 detected by the position sensor, the oil pressure of each cylinder 4a, 4b, 4c detected by the pressure sensors 6a to 6f, the operation of the operation lever 25a detected by the operation amount sensor 25b, and the fuel injection amount commanded from the engine controller 41 to the governor 32. Operation data related to the operation of the work machine 3 during excavation work also includes the speed of the cutting edge 3ca, the load on the cutting edge 3ca, the weight of the load L loaded in the bucket 3c, the fuel efficiency of the excavation work, the work efficiency of the excavation work, the trajectory of the cutting edge 3ca, and the volume of the bucket 3c penetrated into the ground, which are obtained by calculating the values of each of the above detected data. The correspondence between the operation data and the soil type is stored in the memory unit 59.

<Simple N value>
In the embodiment, hardness, which is one of the parameters of soil quality, is estimated from operation data acquired during excavation work. A simplified N-value is used as an index of hardness of the soil material to be excavated. The simplified N-value is measured using a simplified N-value meter. Fig. 5 is a schematic diagram showing the configuration of a simplified N-value meter 200.

The simplified N-value meter 200 comprises a tip cone 201, a hammer 202, a penetration rod 203, a guide rod 204, and a knocking head 205. The tip cone 201 is attached to the lower end of the penetration rod 203. The lower end of the tip cone 201 has a pointed shape. The tip cone 201 has an overall cone (circular cone) shape. The knocking head 205 is attached to the upper end of the penetration rod 203. The tip cone 201 and the knocking head 205 are fixed to the penetration rod 203 so that they cannot move relative to the penetration rod 203.

The lower end of the guide rod 204 is attached to the knocking head 205. The knocking head 205 and the guide rod 204 are fixed so that they cannot move relative to each other. The penetration rod 203 and the guide rod 204 extend in the same straight line. The hammer 202 is attached to the guide rod 204 so that it can move relative to the guide rod 204. The hammer 202 can move relative to the knocking head 205 along the guide rod 204. The lower surface of the hammer 202 is flat, and the upper surface of the knocking head 205 is also flat.

The assembly consisting of the tip cone 201, the penetration rod 203, and the knocking head 205 corresponds to an example of a "part with a cone-shaped tip". The tip cone 201 corresponds to the tip of the "part with a cone-shaped tip", and the knocking head 205 corresponds to the other end opposite the tip of the "part with a cone-shaped tip".

The simplified N value is measured as follows. The simplified N value meter 200 is positioned so that the penetration rod 203 and guide rod 204 extend in a direction perpendicular to the ground surface GL, with the lower end of the tip cone 201 abutting the ground surface GL. In this state, the hammer 202 is lifted a specified height from the knocking head 205, and the hammer 202 is allowed to fall freely along the guide rod 204.

The hammer 202 falls along the guide rod 204 and collides with the knocking head 205. When the knocking head 205 is struck by the hammer 202 and an impact is applied to the knocking head 205, the knocking head 205 tries to move downward toward the ground surface GL. The tip cone 201 and the penetration rod 203 try to move downward together with the knocking head 205. The tip cone 201 that has moved downward penetrates into the ground. The number of times the hammer 202 is dropped until the tip cone 201 penetrates to a specified depth (for example, a depth of 10 cm from the ground surface GL) is measured, and this number is taken as the simplified N value.

<Determining the soil type of the excavation target>
In the embodiment, the soil type discrimination unit 58 reads out a correspondence between the operation data acquired during the excavation work and the soil type of the excavation target from the storage unit 59. The soil type discrimination unit 58 discriminates the soil type of the excavation target from the operation data based on the read-out correspondence. Specifically, the soil type discrimination unit 58 discriminates the soil type of the excavation target by applying the acquired operation data to the read-out correspondence.

Figure 6 is a first diagram showing an example of the correspondence between operation data and soil type. The horizontal axis of the graph shown in Figure 6 is the simplified N value described above, and the vertical axis is the speed of the cutting edge 3ca during excavation work (unit: mm/sec). As shown in Figure 6, there is a good correlation between the speed of the cutting edge 3ca during excavation work and the simplified N value. The data table shown in Figure 6, which associates the speed of the cutting edge 3ca with the simplified N value, is stored in the memory unit 59.

During excavation work, the work machine attitude acquisition unit 56 acquires the attitude of the work machine 3, and the cutting edge speed calculation unit 52 calculates the average speed of the cutting edge 3ca during excavation work. The soil type discrimination unit 58 reads the data table shown in FIG. 6 from the memory unit 59 and calculates the simplified N value corresponding to the calculated cutting edge 3ca speed. In this way, the soil type discrimination unit 58 can calculate the simplified N value, which is an index of the hardness of the excavation target, from the speed of the cutting edge 3ca. The soil type discrimination unit 58 can determine that the lower the speed of the cutting edge 3ca, the harder the excavation target is. Since the simplified N value is one of the parameters of soil type, it can be said that the soil type discrimination unit 58 can determine the soil type of the excavation target from the speed of the cutting edge 3ca.

Figure 7 is a second diagram showing an example of the correspondence between operation data and soil type. The horizontal axis of the graph shown in Figure 7 is the simplified N value, and the vertical axis is the work efficiency of excavation work (unit: ton/h). As shown in Figure 7, there is a good correlation between the work efficiency of excavation work and the simplified N value. The data table shown in Figure 7, which associates work efficiency with the simplified N value, is stored in the memory unit 59.

During excavation work, the work machine attitude acquisition unit 56 acquires the attitude of the work machine 3, and the earthwork volume calculation unit 51 acquires the cylinder pressure of the boom cylinder 4a and calculates the weight (payload) of the load L loaded in the bucket 3c. The efficiency calculation unit 53 calculates the work efficiency based on the payload. The soil type discrimination unit 58 reads the data table shown in FIG. 7 from the storage unit 59 and calculates the simplified N value corresponding to the calculated work efficiency. In this way, the soil type discrimination unit 58 can determine the simplified N value, which is an index of the hardness of the excavation target, from the work efficiency. The soil type discrimination unit 58 can determine that the lower the work efficiency, the harder the excavation target is. Since the simplified N value is one of the parameters of soil type, it can be said that the soil type discrimination unit 58 can determine the soil type of the excavation target from the work efficiency.

Figure 8 is a third diagram showing an example of the correspondence between operation data and soil type. The horizontal axis of the graph shown in Figure 8 is the speed (unit: mm/sec) of the cutting edge 3ca during excavation work, and the vertical axis is the load (unit: kN) on the cutting edge 3ca that has penetrated into the ground during excavation work. As shown in Figure 8, there is a good correlation between the load on the cutting edge 3ca and the speed of the cutting edge 3ca. The data table shown in Figure 8 that associates the load on the cutting edge 3ca with the speed of the cutting edge 3ca is stored in the memory unit 59.

Figure 9 is a fourth diagram showing an example of the correspondence between operation data and soil type. The horizontal axis of the graph shown in Figure 9 is the simplified N value, and the vertical axis is the load (unit: kN) on the cutting edge 3ca. As shown in Figure 6, there is a good correlation between the speed of the cutting edge 3ca and the simplified N value, and as shown in Figure 8, there is a good correlation between the load on the cutting edge 3ca and the speed of the cutting edge 3ca. Therefore, as shown in Figure 9, it is possible to estimate the simplified N value from the load on the cutting edge 3ca. The data table shown in Figure 9, which associates the load on the cutting edge 3ca with the simplified N value, is stored in the memory unit 59.

During excavation work, the work machine attitude acquisition unit 56 acquires the attitude of the work machine 3, and the cutting edge load calculation unit 54 acquires the pressure of each cylinder detected by the pressure sensors 6a to 6f to calculate the load on the cutting edge 3ca of the bucket 3c. The soil type determination unit 58 reads the data table shown in FIG. 9 from the storage unit 59 and calculates the simplified N value corresponding to the calculated load on the cutting edge 3ca. In this way, the soil type determination unit 58 can determine the simplified N value, which is an index of the hardness of the excavation target, from the load on the cutting edge 3ca. The soil type determination unit 58 can determine that the greater the load on the cutting edge 3ca, the harder the excavation target is. Since the simplified N value is one of the parameters of soil type, it can be said that the soil type determination unit 58 can determine the soil type of the excavation target from the load on the cutting edge 3ca that has penetrated into the ground.

Even if the hydraulic excavator 100 is not equipped with a sensor capable of acquiring operation data for calculating the speed of the cutting edge 3ca, the simplified N value can be estimated if the cylinder pressure can be acquired. By attaching an external pressure sensor that detects the cylinder pressure, it is also possible to make it possible to estimate the simplified N value. This makes it possible to expand the range of work vehicles to which the soil type discrimination of the embodiment can be applied.

Figure 15 is the seventh diagram showing an example of the correspondence between operation data and soil type. The horizontal axis of the graph shown in Figure 15 is the simplified N value, and the vertical axis is the fuel efficiency of excavation work (unit: t/L). As shown in Figure 15, there is a good correlation between the fuel efficiency of excavation work and the simplified N value. The data table shown in Figure 15, which associates fuel efficiency with the simplified N value, is stored in the memory unit 59.

During excavation work, the earthwork volume calculation unit 51 calculates the payload, and the efficiency calculation unit 53 obtains the amount of fuel supplied to the engine 31. The efficiency calculation unit 53 calculates the fuel efficiency based on the payload and the amount of fuel supplied. The soil type discrimination unit 58 reads the data table shown in FIG. 15 from the storage unit 59, and calculates the simplified N value corresponding to the calculated fuel efficiency. In this way, the soil type discrimination unit 58 can calculate the simplified N value, which is an index of the hardness of the excavation target, from the fuel efficiency. The soil type discrimination unit 58 can determine that the lower the fuel efficiency, the harder the excavation target is. Since the simplified N value is one of the parameters of soil type, it can be said that the soil type discrimination unit 58 can discriminate the soil type of the excavation target from the fuel efficiency.

Figure 16 is the eighth diagram showing an example of the correspondence between operation data and soil type. The horizontal axis of the graph shown in Figure 16 is the horizontal movement distance of the blade tip 3ca of the bucket 3c when the excavation start point is set to coordinate zero. The vertical axis of the graph shown in Figure 16 is the excavation distance in the depth direction of the blade tip 3ca of the bucket 3c when the excavation start point is set to coordinate zero. In other words, the point where the coordinate on the vertical axis is zero is the ground surface, and the further away from zero the coordinate on the vertical axis is, the deeper the blade tip 3ca has reached into the ground. In Figure 16, the trajectory of the blade tip 3ca during excavation when the simplified N value, which is an index of the hardness of the excavation target, is 3 is shown by a thick line, and the trajectory of the blade tip 3ca during excavation when the simplified N value is 49 is shown by a thin line.

As shown in FIG. 16, the trajectory of the cutting edge 3ca during excavation work varies depending on the hardness of the excavation target. If the excavation target is hard, the cutting edge 3ca has difficulty penetrating the ground, so the cutting edge 3ca moves a long distance at a shallow position in the ground, resulting in a trajectory of the cutting edge 3ca that scrapes away the ground surface. In order to load more load L into the bucket 3c, the operator finely adjusts the angle of the cutting edge 3ca and the load on the cutting edge 3ca, so the trajectory of the cutting edge 3ca becomes more uneven. On the other hand, if the excavation target is soft, the cutting edge 3ca easily penetrates the ground, so the excavation distance in the depth direction becomes larger. Since it is possible to easily load a large load L into the bucket 3c without finely adjusting the attitude of the bucket 3c, the trajectory of the cutting edge 3ca has fewer unevenness and is a smooth trajectory.

During excavation work, the work machine attitude acquisition unit 56 acquires the attitude of the work machine 3 and acquires the trajectory of the cutting edge 3ca from the excavation start point to the excavation end point. From the trajectory of the cutting edge 3ca, the work machine attitude acquisition unit 56 determines the excavation distance in the depth direction when the cutting edge 3ca reaches the deepest position underground, and the determined excavation distance in the depth direction is set as the maximum depth. If the maximum depths are averaged and compared, a correlation with the simplified N value appears. A data table correlating the maximum depth with the simplified N value is stored in the memory unit 59.

The soil type discrimination unit 58 reads from the memory unit 59 a data table associating maximum depth with the simplified N value, and determines the simplified N value corresponding to the maximum depth. In this way, the soil type discrimination unit 58 can determine the simplified N value, which is an index of the hardness of the excavation target, from the cutting edge 3ca of the bucket 3c that has penetrated into the ground. The soil type discrimination unit 58 can determine that the smaller the maximum depth, the harder the excavation target is. Since the simplified N value is one of the parameters of soil type, it can be said that the soil type discrimination unit 58 can determine the soil type of the excavation target from the trajectory of the cutting edge 3ca.

Figure 17 is a ninth diagram showing an example of the correspondence between operation data and soil type. Figure 18 is a tenth diagram showing an example of the correspondence between operation data and soil type. The horizontal axis of the graphs shown in Figures 17 and 18 indicates the passage of time during excavation, with the start of excavation being time zero.

The vertical axis of the graphs shown in Figures 17 and 18 indicates the speed (unit: mm/sec) of the cutting edge 3ca during excavation work, and the operation of the control lever 25a during excavation work. The input when the control lever 25a is neutral is 0%, and the input when the control lever 25a is fully tilted is 100%. The operation of the control lever 25a to operate the boom 3a is the boom lever input. The operation of the control lever 25a to operate the arm 3b is the arm lever input. The operation of the control lever 25a to operate the bucket 3c is the bucket lever input.

Figure 17 shows the cutting edge speed and lever input during excavation when the simplified N value, an index of the hardness of the excavation target, is 3. As shown in Figure 17, if the excavation target is soft, the bucket 3c penetrates the ground easily, so it is possible to easily fill the bucket 3c without using the maximum excavation force of the vehicle body. If attention is paid to the decrease in excavation speed caused by the bucket 3c penetrating too deeply into the ground and loading too much load L, the excavation speed will not decrease even without fine adjustments made to the operating lever 25a.

Figure 18 shows the cutting edge speed and lever input during excavation when the simplified N value, an index of the hardness of the excavation target, is 70. As shown in Figure 18, if the excavation target is hard, the bucket 3c has difficulty penetrating the ground, and the reaction force from the excavation target is also high, making it easy for the work machine 3 to stop. It is not possible to load a large amount of the excavation target into the bucket 3c by operating the control lever 25a in the same way as when the excavation target is soft. To increase the load of the bucket 3c even if it means sacrificing the excavation speed, the operator adjusts the speed of the cutting edge 3ca during excavation and the attitude of the work machine 3 by finely operating the control lever 25a, and excavates over a long period of time while appropriately releasing the load.

During excavation work, the excavation time calculation unit 57 receives an input of the detection result of the operation content of the operating lever 25a from the operation amount sensor 25b. The work machine attitude acquisition unit 56 acquires the attitude of the work machine 3, and the cutting edge speed calculation unit 52 calculates the speed of the cutting edge 3ca during excavation work. A correlation appears between the excavation time and the simplified N value, and a correlation appears between the operation content of the operating lever 25a during excavation work and the simplified N value. The memory unit 59 stores a data table correlating the excavation time with the simplified N value, and a data table correlating the operation content of the operating lever 25a with the simplified N value.

The soil type discrimination unit 58 reads out from the memory unit 59 a data table that associates the operation of the control lever 25a with the simplified N value, and determines the simplified N value that corresponds to the operation of the control lever 25a during excavation work. In this way, the soil type discrimination unit 58 can determine the simplified N value, which is an index of the hardness of the excavation target, from the operation of the control lever 25a during excavation work. The soil type discrimination unit 58 can determine that the harder the excavation target is, the more finely the control lever 25a is operated during excavation work. Since the simplified N value is one of the parameters of soil type, it can be said that the soil type discrimination unit 58 can determine the soil type of the excavation target from the operation of the control lever 25a during excavation work.

Figure 10 is a side view of the work machine showing the posture when starting a dedicated soil type discrimination operation. Due to differences in skill and operating habits between operators who operate the hydraulic excavator 100, there may be variation in the operation data that can be acquired during excavation work. To reduce this variation, a dedicated soil type discrimination operation can be set in the hydraulic excavator 100, and the work machine 3 can be controlled to perform a predetermined operation during excavation work.

Specifically, as shown in FIG. 10, the working machine 3 is oriented so that, when the hydraulic excavator 100 is viewed from the side, the straight line passing through the boom top pin 5b and the arm top pin 5c is perpendicular to the bottom surface 3cb of the bucket 3c. While maintaining the relative orientation of the arm 3b and the bucket 3c, the length of the arm cylinder 4b is minimized to make the arm 3b in the most extended position. In this position, the arm angle θa (FIG. 1) is minimized. The boom 3a is also operated to bring the blade tip 3ca of the bucket 3c into contact with the ground surface. From this position, the arm 3b is operated in the excavation direction. Typically, the arm 3b is operated at maximum speed in the excavation direction. This operation of the arm 3b causes the blade tip 3ca of the bucket 3c to perform an arc motion, and the blade tip 3ca penetrates into the ground. Operation data is acquired until the blade tip 3ca stops when the excavation target in the ground becomes a resistance to the movement of the blade tip 3ca.

The operator can choose whether to perform excavation work at will or to perform excavation work using dedicated soil type discrimination operations, depending on the required accuracy of soil type discrimination. For example, excavation work using dedicated soil type discrimination operations can be performed when the soil quality of the excavation target is likely to change drastically. By performing excavation work using dedicated soil type discrimination operations, the accuracy of soil type discrimination can be improved without the influence of the operator.

Figure 11 is a fifth diagram showing an example of the correspondence between operation data and soil type. The horizontal axis of the graph shown in Figure 11 is the simplified N value, and the vertical axis is the maximum cutting edge speed (unit: mm/sec). As shown in Figure 11, there is a good correlation between the maximum speed of the cutting edge 3ca that penetrates into the ground when performing excavation work using the soil type discrimination dedicated operation, and the simplified N value. The data table shown in Figure 11 that associates the maximum speed of the cutting edge 3ca with the simplified N value is stored in the memory unit 59.

The cutting edge speed calculation unit 52 acquires the posture of the work machine 3 during excavation work using the dedicated soil type discrimination operation, and calculates the speed of the cutting edge 3ca by differentiating the position coordinates of the cutting edge 3ca. The cutting edge speed calculation unit 52 calculates the speed of the cutting edge 3ca in a time series for unit times that are equal divisions of the time from the start to the end of excavation work using the dedicated soil type discrimination operation. The cutting edge speed calculation unit 52 calculates the change in the speed of the cutting edge 3ca over time. The cutting edge speed calculation unit 52 obtains the maximum value of the speeds of the cutting edge 3ca in each unit time, and sets this as the maximum speed of the cutting edge 3ca.

The soil type discrimination unit 58 reads the data table shown in FIG. 11 from the memory unit 59 and determines the simplified N value corresponding to the calculated maximum speed of the cutting edge 3ca. In this way, the soil type discrimination unit 58 can determine the simplified N value, which is an index of the hardness of the excavation target, from the maximum speed of the cutting edge 3ca when performing dedicated soil type discrimination operations. The soil type discrimination unit 58 can determine that the harder the excavation target is, the smaller the maximum cutting edge speed is. Since the simplified N value is one of the parameters of soil type, it can be said that the soil type discrimination unit 58 can determine the soil type of the excavation target from the maximum speed of the cutting edge 3ca that penetrates into the ground when performing dedicated soil type discrimination operations.

Figure 12 shows an example of the progress of the cutting edge speed during excavation work. The horizontal axis of the graph shown in Figure 12 is time, and the vertical axis is the cutting edge speed. At time zero, excavation work is started using an operation dedicated to soil type discrimination. Figure 12 shows an example of excavating an excavation target with a relatively small simplified N value.

When the hardness of the excavation target is low, as shown in FIG. 12, the speed of the cutting edge 3ca reaches a peak value immediately after the excavation work begins. After passing the peak, the cutting edge 3ca continues to move at a low speed until the excavation work ends, i.e., until the movement of the cutting edge 3ca stops. The speed of the cutting edge 3ca from passing the peak until it stops is much smaller than the maximum speed of the cutting edge 3ca. If the average speed of the cutting edge 3ca is calculated as shown in FIG. 6, the peak of the cutting edge speed is hidden, making it difficult to distinguish the characteristics of the soil type. For this reason, when performing operations dedicated to soil type discrimination, the soil type is characterized by the maximum speed of the cutting edge 3ca. This makes it possible to accurately distinguish the soil type of the excavation target.

To obtain the maximum speed of the cutting edge 3ca, it is not necessary to obtain operation data for the entire excavation process. The maximum speed at which the cutting edge 3ca penetrates into the ground can be obtained from operation data for only a portion of the excavation process during a certain period of time after the excavation process begins, and the soil type of the excavation target can be determined from the obtained maximum speed of the cutting edge 3ca. It is not necessary to determine the soil type from operation data for all steps during the excavation process. Because the soil type can be determined only from operation data at the start of excavation, the process of obtaining operation data can be simplified, and the soil type can be determined quickly.

Fig. 13 is a sixth diagram showing an example of the correspondence between operation data and soil type. The horizontal axis of the graph shown in Fig. 13 is the simplified N value, and the vertical axis is the penetration amount of the bucket 3c into the ground (unit: ^m3 ). The penetration amount of the bucket 3c into the ground indicates the volume of the bucket 3c that has penetrated into the ground from the ground surface GL, which is calculated using the attitude of the bucket 3c acquired from the detection result of the position sensor.

Figure 14 is a schematic diagram showing a bucket 3c that has penetrated into the ground. The bucket 3c shown in Figure 14 has a portion, including the cutting edge 3ca, that is in the ground, and a portion that is above the ground surface GL. As described above, the volume of the bucket 3c that has penetrated into the ground can be calculated by multiplying the area of the bucket 3c that has penetrated into the ground when viewed from the side by the width of the bucket 3c. For simplicity, the volume of the bucket 3c may be calculated as the product of the depth of the cutting edge 3ca of the bucket 3c from the ground surface GL and the width of the bucket 3c.

When performing excavation work using the dedicated soil type discrimination operation, it is possible to calculate the amount of penetration of the bucket 3c into the ground when the movement of the cutting edge 3ca stops. As shown in FIG. 13, there is a good correlation between the amount of penetration of the bucket 3c when performing the dedicated soil type discrimination operation and the simplified N value. The data table shown in FIG. 13, which associates the amount of penetration of the bucket 3c into the ground with the simplified N value, is stored in the memory unit 59.

The penetration amount calculation unit 55 acquires the posture of the work machine 3 during excavation work by the dedicated soil type discrimination operation, and calculates the penetration amount of the bucket 3c into the ground. The soil type discrimination unit 58 reads the data table shown in FIG. 13 from the storage unit 59, and calculates the simplified N value corresponding to the calculated penetration amount. In this way, the soil type discrimination unit 58 can calculate the simplified N value, which is an index of the hardness of the excavation target, from the volume of the bucket 3c that penetrated into the ground when performing the dedicated soil type discrimination operation. The soil type discrimination unit 58 can determine that the excavation target is harder when the volume of the bucket 3c that penetrated into the ground is smaller. Since the simplified N value is one of the parameters of soil type, it can be said that the soil type discrimination unit 58 can determine the soil type of the excavation target from the volume of the bucket 3c that penetrated into the ground when performing the dedicated soil type discrimination operation.

＜Other＞
The operation data related to the operation of the working machine 3 during excavation work is not limited to the examples described in the above embodiment. The operation data may include the spool stroke of the operating valve 35 detected by the stroke sensor 35a, the discharge pressure of the hydraulic pump 34 detected by the pressure sensor 36, the rotation speed of the engine 31 detected by the rotation sensor 33, the output torque of the engine 31 and the absorption torque of the hydraulic pump 34 calculated according to the rotation speed of the engine 31, the vibration of the rotating body 2 detected by the vibration sensor 2f, the angle of the vehicle body (rotating body 2) detected by the IMU 8a, and the like, as shown in Figures 2 and 3. The operation data may be data related to the power for operating the working machine 3 during excavation work, or may be data that can be acquired in association with the operation of the working machine 3.

The sensor that acquires the operation data may be a sensor that is equipped on the hydraulic excavator 100 at the time of shipment of the hydraulic excavator 100. The sensor may be a sensor that is retrofitted to the hydraulic excavator 100 after shipment of the hydraulic excavator 100.

The operation data is not limited to data acquired when an operator manually operates the hydraulic excavator 100 to perform excavation work. Data acquired during excavation work using an automatic excavator or the like may be included in the operation data. The operation data may be data for only a part of the excavation process, such as data at the start of excavation or data during excavation.

Operation data is not limited to data acquired in real time. Only data from excavation work may be extracted from operational data from when the work machine worked in the past. The type of soil to be excavated during the excavation work may be determined from operation data acquired during the past excavation work.

The soil type determination unit 58 is not limited to the example of determining the soil type by reading out the data table stored in the memory unit 59. The data table showing the correspondence between the operation data and the soil type of the excavation target may be stored in an external storage device, not in the memory unit 59 inside the main controller 50.

The soil type discrimination unit 58 may have a soil type discrimination model that has been trained by machine learning. The trained soil type discrimination model may be generated by a learning process using learning data in which operation data when an excavation operation is performed on an excavation target is labeled with a simplified N value measured by a simplified N value meter 200 for the excavation target. The trained soil type discrimination model may be trained using a learning data set so that when operation data related to the operation of the work machine is input, a simplified N value is output from the operation data.

The acquisition unit that acquires operation data related to the operation of the work machine 3 is not limited to various sensors mounted on the hydraulic excavator 100. The acquisition unit that acquires operation data may be disposed outside the hydraulic excavator 100. For example, an imaging device that captures images of the hydraulic excavator 100 from outside may be included in the acquisition unit that acquires operation data. The imaging device may acquire still images of the work machine 3, or may acquire video of the work machine 3. Operation data related to the operation of the work machine 3 may be acquired by analyzing the acquired images.

As described above, the main controller 50 may be mounted on the hydraulic excavator 100, or may be installed outside the hydraulic excavator 100. Therefore, the determination of the soil type of the excavation target may be performed within the hydraulic excavator 100, or may be performed on a server, tablet computer, or the like external to the hydraulic excavator 100.

In the embodiment, a hydraulic excavator 100 has been described as an example of a work machine, but the concept of the present disclosure may be applied to other types of work machines that perform excavation work, such as a wheel loader, without being limited to the hydraulic excavator 100. The work machine is not limited to a tracked vehicle 1 having a track device 1a, but may also include a wheeled vehicle. In addition, the work machine may be a remote-operated type that can be operated remotely via wireless communication.

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

(Appendix 1)
A work machine having a work implement;
an acquisition unit that acquires operation data related to an operation of the work machine during an excavation operation of excavating an excavation target with the work machine;
A soil type discrimination system comprising: a controller that discriminates the soil type from the operation data based on a correspondence between the operation data and the soil type of the excavation target.

(Appendix 2)
The work machine includes a bucket having a cutting edge,
2. The soil type discrimination system of claim 1, wherein the operational data includes a speed of the cutting edge.

(Appendix 3)
3. The soil type discrimination system of claim 2, wherein the operational data includes a maximum speed at which the cutting edge penetrates into the ground.

(Appendix 4)
4. The soil type discrimination system according to claim 1, wherein the controller discriminates the soil type from the operational data of a portion during an excavation operation.

(Appendix 5)
The work machine includes a bucket having a cutting edge,
The soil type discrimination system according to any one of claims 1 to 4, wherein the operational data includes a load applied to the cutting edge that has penetrated into the ground.

(Appendix 6)
The work machine has a bucket,
6. The soil type discrimination system of claim 1, wherein the operational data includes a weight of a load loaded in the bucket.

(Appendix 7)
The working machine further includes an engine that generates a driving force for operating the working machine,
7. The soil type discrimination system of claim 6, wherein the operational data includes an amount of fuel supplied to the engine per unit weight of the load.

(Appendix 8)
8. The soil type discrimination system according to claim 6, wherein the operational data includes a work efficiency of an excavation work performed by the bucket.

(Appendix 9)
The work machine has a bucket,
9. The soil type discrimination system according to claim 1, wherein the operational data includes an attitude of the bucket.

(Appendix 10)
10. The soil type discrimination system of claim 9, wherein the operational data includes a volume of the bucket penetrated into the ground.

(Appendix 11)
The bucket has a cutting edge,
11. The soil type discrimination system of claim 9 or 10, wherein the operational data includes a trajectory of the cutting edge penetrating into the ground.

(Appendix 12)
The work machine further includes an operating device that receives an operation to drive the work machine,
The soil type discrimination system according to any one of claims 1 to 11, wherein the operation data includes operation content of the operating device.

(Appendix 13)
13. The soil type discrimination system according to any one of claims 1 to 12, wherein the work machine is controlled to perform a predetermined operation during excavation work.

(Appendix 14)
14. The soil type discrimination system according to claim 1, wherein the acquisition unit is mounted on the work machine.

(Appendix 15)
The soil type discrimination system according to any one of appendices 1 to 14, wherein the soil type is an index obtained based on the number of times a cone-shaped tip part is placed against the ground and an impact is applied to the part from the opposite side of the tip until the tip penetrates to a predetermined depth.

Although the embodiments have been described above, the embodiments disclosed herein are illustrative in all respects and should not be considered as limiting. The scope of the present invention is indicated by the claims, not by the above description, and is intended to include all modifications within the meaning and scope of the claims.

1 Traveling body, 2 Swivel body, 2f Vibration sensor, 3 Work machine, 3a Boom, 3b Arm, 3c Bucket, 3ca Cutting edge, 3cb Bottom surface, 4a Boom cylinder, 4b Arm cylinder, 4c Bucket cylinder, 6a, 6b, 6c, 6d, 6e, 6f, 36 Pressure sensor, 7a, 7b, 7c, 35a Stroke sensor, 8a, 8b, 8c, 8d IMU, 9a, 9b, 9c Angle sensor, 25 Operation device, 25a Operation lever, 25b Operation amount sensor, 31 Engine, 33 Rotation sensor, 34 Hydraulic pump, 35 Operation valve, 50 Main controller, 51 Earthwork amount calculation unit, 52 Cutting edge speed calculation unit, 53 Efficiency calculation unit, 54 Cutting edge load calculation unit, 55 Penetration amount calculation unit, 56 Work machine attitude acquisition unit, 57 Excavation time calculation unit, 58 soil type determination unit, 59 memory unit, 60 output unit, 100 hydraulic excavator, 200 simple N value meter, GL ground surface, L load.

Claims (16)

A work machine having a work implement;
an acquisition unit that acquires operation data related to an operation of the work machine during an excavation operation of excavating an excavation target with the work machine;
A soil type discrimination system comprising: a controller that discriminates the soil type from the operation data based on a correspondence between the operation data and the soil type of the excavation target. The work machine includes a bucket having a cutting edge,
The soil type discrimination system of claim 1 , wherein the operational data includes a speed of the cutting edge. The soil type discrimination system of claim 2, wherein the operational data includes a maximum speed at which the cutting edge penetrates into the ground. The soil type discrimination system according to claim 3, wherein the controller discriminates the soil type from the operation data of a portion during excavation work. The work machine includes a bucket having a cutting edge,
The soil type discrimination system according to claim 1 , wherein the operational data includes a load applied to the cutting edge that has penetrated into the ground. The work machine has a bucket,
The soil type determination system of claim 1 , wherein the operational data includes a weight of a load placed in the bucket. The working machine further includes an engine that generates a driving force for operating the working machine,
The soil type discrimination system of claim 6 , wherein the operational data includes an amount of fuel supplied to the engine per unit weight of the load. The soil type discrimination system according to claim 6, wherein the operational data includes the work efficiency of the excavation work performed by the bucket. The work machine has a bucket,
The soil type discrimination system of claim 1 , wherein the operational data includes an attitude of the bucket. The soil type discrimination system according to claim 9, wherein the operational data includes a volume of the bucket penetrated into the ground. The bucket has a cutting edge,
The soil type discrimination system according to claim 9 , wherein the operational data includes a trajectory of the cutting edge as it penetrates into the ground. The work machine further includes an operating device that receives an operation to drive the work machine,
The soil type discrimination system according to claim 1 , wherein the operation data includes operation details of the operation device. The soil type discrimination system according to any one of claims 1 to 12, wherein the work machine is controlled to perform a predetermined operation during excavation work. The soil type discrimination system according to any one of claims 1 to 12, wherein the acquisition unit is mounted on the work machine. The soil type discrimination system according to any one of claims 1 to 12, wherein the soil type is an index obtained by applying an impact to a part with a cone-shaped tip from the opposite side of the tip when the part is placed on the ground and the impact is applied to the part from the opposite side of the tip, based on the number of times the tip penetrates to a predetermined depth. Acquiring operation data related to an operation of a work implement of a work machine during an excavation operation of excavating an excavation target with the work implement;
and determining the soil type from the operation data based on a correspondence between the operation data and the soil type of the excavation target.

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