Soil quality determination system and soil quality determination method

Abstract

Provided is a system capable of effectively utilizing data acquired during work. This soil quality determination system comprises: a working machine that has a working implement; an acquiring unit that acquires operation data relating to the operation of the working implement during excavation work in which an excavation target is excavated by the working implement; and a controller (50) that determines soil quality from the operation data on the basis of a correspondence relationship between the operation data and the soil quality of the excavation target.

Description

Soil quality discrimination system and soil quality discrimination method

[0001] The present disclosure relates to a soil type discrimination system and a soil type discrimination method.

[0002] Japanese Patent Laid-Open Publication No. 2020-173150 (Patent Document 1) discloses a soil quality determination device mounted on a construction machine. The soil quality determination device includes a memory 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 camera images 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.

[0003] Japanese Patent Application Laid-Open Publication No. 2019-163621 (Patent Document 2) describes that the hardness of the ground is estimated based on the detection value of the sensor when a predetermined operation is performed in which the attachment contacts the ground at a predetermined speed and a predetermined angle, and data in which the detection value of the sensor when the predetermined operation is performed is associated with the hardness of the ground.

[0004] JP 2020-173150 A JP 2019-163621 A

[0005] The introduction of work machines equipped with ICT (information and communication technology) functions is progressing. The amount of data that can be acquired while work machines are operating is increasing. It is expected that this data can be used to improve the productivity of work machines.

[0006] The present disclosure proposes a system and method that can effectively utilize data acquired during work.

[0007] A 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 excavation work 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.

[0008] A soil type determination method according to the present disclosure includes the following steps: a first step of acquiring operation data related to the operation of a work implement of a work machine during an excavation operation in which the work implement excavates an excavation target; and a second step of determining the soil type from the operation data based on a correspondence between the operation data and the soil type of the excavation target.

[0009] According to the present disclosure, it is possible to realize a system and method that can easily estimate the soil quality of the excavation target from data acquired during excavation work.

[0010] 1 is a side view showing a schematic configuration of a work machine. FIG. 2 is a block diagram showing a schematic configuration of a work machine system. FIG. 3 is a diagram showing an example of the relationship between engine rotation speed and torque. FIG. 4 is a diagram showing functional blocks within a main controller. FIG. 5 is a schematic diagram showing the configuration of a simple N-value meter. FIG. 6 is a diagram showing an example of the correspondence between operation data and soil type. FIG. 7 is a diagram showing an example of the correspondence between operation data and soil type. FIG. 8 is a diagram showing an example of the correspondence between operation data and soil type. FIG. 9 is a 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.

[0011] 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. It is also intended from the beginning that any configuration may be extracted from the embodiments and arbitrarily combined.

[0012] <Configuration of Work Machine> Figure 1 is a side view that schematically shows the configuration of a hydraulic excavator 100 as an example of a work machine based on the present disclosure. As shown in Figure 1, the hydraulic excavator 100 of this embodiment mainly has a traveling body 1, a revolving body 2, and a work implement 3. The traveling body 1 and the revolving body 2 form the vehicle body of the hydraulic excavator 100.

[0013] 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.

[0014] The rotating body 2 is disposed on and supported by the running body 1. The rotating body 2 mainly includes an operator's cab 2a, an operator's seat 2b, an engine room 2c, a counterweight 2d, and a swing motor 2e. The operator's cab 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 operator's cab 2a.

[0015] 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 engine room 2c is covered from above by an engine hood. The counterweight 2d is located behind the engine room 2c.

[0016] The revolving unit 2 is attached to the running unit 1 via a revolving circle portion. The revolving circle portion has a roughly annular shape and has internal teeth for revolving on its inner circumferential surface. A pinion that meshes with these internal teeth is attached to the revolving motor 2e. The revolving unit 2 is rotatable relative to the running unit 1 as a result of the driving force transmitted from the revolving motor 2e being transmitted to rotate the revolving circle portion. The revolving motor 2e is a hydraulic motor that is driven by hydraulic pressure. The revolving motor 2e may also be an electric motor.

[0017] The vibration sensor 2f is mounted on the frame of the revolving structure 2. The vibration sensor 2f detects vibrations occurring in the revolving structure 2.

[0018] The work implement 3 is pivotally supported on the front side of the revolving structure 2, for example, on the right side of the operator's cab 2a. The work implement 3 has, for example, a boom 3a, an arm 3b, a bucket 3c, a boom cylinder 4a, an arm cylinder 4b, and a bucket cylinder 4c. A base end (one end) of the boom 3a is rotatably connected to the revolving structure 2 by a boom bottom pin 5a. A base end (one end) of the arm 3b is rotatably connected to a tip end (other end) of the boom 3a by a boom top pin 5b. (One end) of the bucket 3c is rotatably connected to a tip end (other end) of the arm 3b by an arm top pin 5c.

[0019] The bucket 3c is disposed at the tip of the work implement 3. The tip of the bucket 3c is referred to as a cutting edge 3ca. The bottom surface 3cb is a part of the outer surface of the bucket 3c. The bottom surface 3cb is formed as a flat surface.

[0020] In this embodiment, the positional relationship of each part of the hydraulic excavator 100 will be described with reference to the work implement 3.

[0021] The boom 3a of the work implement 3 rotates about the boom bottom pin 5a relative to the revolving unit 2. A specific portion of the boom 3a that rotates relative to the revolving unit 2, for example, the tip of the boom 3a, moves along an arc-shaped trajectory, and a plane that includes this arc is identified. When the hydraulic excavator 100 is viewed from above, this plane is represented as a straight line. The direction in which this straight line extends is the fore-and-aft direction of the vehicle body of the hydraulic excavator 100 or the fore-and-aft direction of the revolving unit 2, and will hereinafter be simply referred to as the fore-and-aft direction. The left-and-right direction (vehicle width direction) of the vehicle body of the hydraulic excavator 100 or the left-and-right direction of the revolving unit 2 is a direction perpendicular to the fore-and-aft direction in a plan view, and will hereinafter be simply referred to as the left-and-right direction. The up-and-down direction of the vehicle body of the hydraulic excavator 100 or the up-and-down direction of the revolving unit 2 is a direction perpendicular to the plane defined by the fore-and-aft direction and the left-and-right directions, and will hereinafter be simply referred to as the up-and-down direction.

[0022] In the front-to-rear direction, the side where the work implement 3 protrudes from the vehicle body is the front direction, and the opposite direction is the rear direction. Looking forward, the right and left sides in the left-right direction are the right and left directions, 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.

[0023] The front-to-rear direction is 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 is the left-to-right direction of the operator seated in the driver's seat 2b. The up-to-down direction is 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 head is the up side.

[0024] 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 revolving unit 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. The work implement 3 can be driven in this manner.

[0025] The boom bottom pin 5a is supported by the vehicle 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 revolving unit 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, boom top pin 5b, and arm top pin 5c all extend in the left-right direction. The boom bottom pin 5a is also called a boom foot pin.

[0026] The work implement 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 a bucket cylinder 4c. Therefore, the first link member 3da and the second link member 3db are connected to the bucket cylinder 4c by a pin.

[0027] The base end of the first link member 3da is rotatably connected to the arm 3b by a first link pin 3dd, and the base end of the second link member 3db is rotatably connected to a bracket at the base of the bucket 3c by a second link pin 3de.

[0028] 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 a main controller 50, which will be described later.

[0029] 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 a main controller 50, which will be described later.

[0030] A pressure sensor 6e is attached to the head side of the bucket cylinder 4c. The pressure sensor 6e can detect the pressure of 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 hydraulic oil in the cylinder bottom-side oil chamber of the bucket cylinder 4c (bottom pressure). The pressure sensors 6e, 6f output hydraulic oil pressure information consisting of the head pressure and bottom pressure to a main controller 50, which will be described later.

[0031] The boom 3 a, arm 3 b, and bucket 3 c are provided with position sensors for obtaining information on their respective positions and attitudes. The position sensors output boom information, arm information, and attachment information for obtaining the respective positions of the boom 3 a, arm 3 b, and bucket 3 c to a main controller 50, which will be described later.

[0032] 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.

[0033] 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 a main controller 50, which will be described later.

[0034] As shown in FIG. 1, in a side view, the angle formed by a 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 line extending in the vertical direction (shown by a dashed line in FIG. 1) is defined as the boom angle θb. The boom angle θb is usually an acute angle. The boom angle θb represents the angle of the boom 3a with respect to the revolving unit 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.

[0035] In a side view, the angle formed by a line passing through the boom bottom pin 5a and the boom top pin 5b and a line passing through the boom top pin 5b and the arm top pin 5c (shown by a two-dot chain line in FIG. 1) is the arm angle θa. The arm angle θa represents the angle of the arm 3b with respect to the boom 3a in the region where 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.

[0036] In a side view, the angle formed by 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 FIG. 1) is the bucket angle θk. The bucket angle θk represents the angle of the bucket 3c with respect to the arm 3b in the region where the bucket 3c rotates in a side view. The bucket angle θk can be calculated from the detection result of the stroke sensor 7c, and can also be calculated from the measurement value of the angle sensor 9c.

[0037] The position sensor may be an IMU (Inertial Measurement Unit). IMUs 8a, 8b, 8c, and 8d are attached to the rotating structure 2, the boom 3a, the arm 3b, and the first link member 3da, respectively. The IMU 8a measures the acceleration of the rotating structure 2 in the front-to-back, left-to-right, and up-to-down directions, and the angular velocities of the rotating structure 2 around the front-to-back, left-to-right, and up-to-down directions. The IMUs 8b, 8c, and 8d measure the acceleration of the boom 3a, the arm 3b, and the first link member 3da in the front-to-back, left-to-right, and up-to-down directions, and the angular velocities of the boom 3a, the arm 3b, and the first link member 3da around the front-to-back, left-to-right, and up-to-down directions, respectively.

[0038] The acceleration of the extension and retraction of the boom cylinder 4a (the amount of change in the extension and 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 revolving unit 2 and the acceleration measured by the IMU 8b attached to the boom 3a. The boom angle θb, the arm angle θa, and the bucket angle θk may be calculated from the detection results of the IMUs 8b, 8c, and 8d, respectively.

[0039] Although the stroke sensors of the hydraulic cylinders, the angle sensors of the links such as the boom 3a, and the IMU have been cited as position sensors, 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 GNSS (Global Navigation Satellite System).

[0040] <General Configuration of Work Machine System> Next, the general configuration of the work machine system will be described with reference to Fig. 2. Fig. 2 is a block diagram showing the general configuration of the work machine system shown in Fig. 1.

[0041] As shown in FIG. 2, the system of this embodiment includes a hydraulic excavator 100 as an example of the work machine shown in FIG. 1, and a main controller 50 shown in FIG.

[0042] The engine 31 is, for example, a diesel engine. An output shaft of the engine 31 is connected to a hydraulic pump 34. The engine 31 generates driving force to rotate the hydraulic pump 34. The governor 32 adjusts the amount of fuel injected by a fuel injection device in the engine 31.

[0043] The engine controller 41 outputs a command value of the fuel injection amount based on the command rotation speed of the engine 31 to the governor 32, and controls the amount of fuel injected by the fuel injection device, thereby adjusting the rotation speed of the engine 31. 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.

[0044] The hydraulic pump 34 is driven by the rotational driving force of the engine 31, and discharges pressurized oil for generating hydraulic pressure that drives the hydraulic actuators. The hydraulic actuators include hydraulic cylinders also shown in Fig. 1, i.e., boom cylinder 4a, arm cylinder 4b, and bucket cylinder 4c, and hydraulic motors also shown in Fig. 1, i.e., travel motor 1b and swing motor 2e. The hydraulic actuators are connected to the hydraulic pump 34 via operation valves 35.

[0045] 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. A pressure sensor 36 detects the pressure of the oil discharged from the hydraulic pump 34. The pressure sensor 36 outputs the detected oil pressure to a 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 a pressure-reducing valve 37 and used as pilot oil.

[0046] The operating valve 35 is, for example, a spool-type valve that switches the direction of hydraulic oil flow by moving a rod-shaped spool. The amount of hydraulic oil supplied to the hydraulic actuator is adjusted by axial movement of the spool. The operating 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 implement 3, the rotation of the revolving unit 2, and the traveling operation of the traveling unit 1 are controlled.

[0047] In this example, the oil supplied to the hydraulic actuator to operate the hydraulic actuator is referred to as hydraulic oil. Also, the oil supplied to the operating valve 35 to operate the spool of the operating valve 35 is referred to as pilot oil. Also, the pressure of the pilot oil is referred to as pilot oil pressure.

[0048] The hydraulic pump 34 may be one that delivers both the hydraulic oil and the pilot oil as described above. The hydraulic pump 34 may include a hydraulic pump that delivers the hydraulic oil (main hydraulic pump) and a hydraulic pump that delivers the pilot oil (pilot hydraulic pump) separately.

[0049] An EPC (electromagnetic proportional control) valve 38 is provided in the path of the pilot oil. The EPC valve 38 outputs pilot oil pressure to the operation valve 35 in accordance with a command current from the main controller 50. The operation valve 35 controls the hydraulic actuator in accordance with the pilot oil pressure.

[0050] 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 to each other 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 a main controller 50.

[0051] The main controller 50 is a controller that controls the entire hydraulic excavator 100, and is configured with 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.

[0052] 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, or the like.

[0053] The operating device 25 is disposed in the operator's cab 2a (FIG. 1). The operating device 25 is operated by an operator. The operating device 25 receives an operator operation to drive the work implement 3. The operating device 25 also receives an operator operation to rotate the rotating body 2. The operating device 25 is, for example, an electric operating device, and includes an operating lever 25a and an operation amount sensor 25b.

[0054] 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 an operation command from the operating device 25 to drive the hydraulic actuator.

[0055] The operating device 25 is not limited to an electric 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 by, for example, a pressure sensor that detects the pressure of the pilot oil.

[0056] Detection signals from the stroke sensors 7a to 7c, IMUs 8a to 8d, angle sensors 9a to 9c, pressure sensors 6a to 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 wire, or may be capable of wireless communication.

[0057] As will be described in detail below, the main controller 50 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 arranged outside the hydraulic excavator 100. The external controller may be a computer, a server, a mobile terminal, or the like. The external controller may be a computer that constitutes a construction management system.

[0058] The rotation speed of the engine 31 detected by the rotation sensor 33 is input to the engine controller 41. One of the engine controller 41, the pump controller 42, and the main controller 50 calculates the output torque of the engine 31 and the absorption torque of the hydraulic pump 34 according to the rotation speed of the engine 31. Fig. 3 is a diagram showing an example of the relationship between the engine rotation speed and the torque.

[0059] 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.

[0060] Therefore, when the rotation speed of the engine 31 increases, the output torque of the engine 31 decreases and the absorption torque of the hydraulic pump 34 increases, so the rotation speed of the engine 31 begins 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 of the hydraulic pump 34 decreases, so the rotation speed of the engine 31 begins to increase. By repeating this process, the engine 31 and the hydraulic pump 34 operate stably at a 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.

[0061] <Functional Blocks in Main Controller 50> Next, functional blocks in the main controller 50 will be described with reference to Fig. 4. Fig. 4 is a diagram showing functional blocks in the main controller 50 shown in Fig. 2.

[0062] The detection results of stroke sensors 7a-7c, IMUs 8a-8d, angle sensors 9a-9c, etc., which constitute the position sensor, are input to main controller 50. Work implement attitude acquisition unit 56 acquires the attitude of work implement 3 based on the detection results of the position sensors. Work implement attitude acquisition unit 56 acquires the trajectory of cutting edge 3ca of bucket 3c during excavation work from the attitude of work implement 3 at each point in time during excavation work.

[0063] 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 changes in the pressure difference between the head pressure and the bottom pressure of the boom cylinder 4a in relation to the attitude 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 shows the load being carried by the bucket 3c in that attitude of the work implement 3. The data table is stored in the memory unit 59.

[0064] 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 excavation time calculation unit 57 grasps the time when the command to drive the arm 3b in the excavation direction started and the time when the command to drive the arm 3b in the excavation direction stopped. The excavation time calculation unit 57 may calculate the time when the command to drive the arm 3b in the excavation direction was issued, and may take the calculated time as the excavation time.

[0065] The excavation time calculation unit 57 may use the attitude of the work machine 3 acquired by the work machine attitude acquisition unit 56 to calculate the time required for the work machine 3 to move from the start point to the end point, taking the time when a predetermined excavation start attitude of the work machine 3 is detected as the start point and the time when a predetermined excavation end attitude of the work machine 3 (for example, the attitude when the bucket 3c has finished holding the load L) as the end point, and may take the calculated time as the excavation time. The excavation start attitude and excavation end attitude of the work machine 3 are stored in the memory unit 59.

[0066] The excavation time calculation unit 57 may use the attitude of only the bucket 3c acquired by the work machine attitude 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 attitude of the bucket 3c is detected as the start point and the excavation end attitude of the bucket 3c as the end point, and may treat the calculated time as the excavation time. The excavation start attitude and excavation end attitude of the bucket 3c are stored in the memory unit 59.

[0067] Work machine attitude acquisition unit 56 acquires the position of cutting edge 3ca of bucket 3c based on input from the position sensor. Cutting edge speed calculation unit 52 acquires the time-series positions of cutting edge 3ca from the start to the end of excavation. Cutting edge speed calculation unit 52 obtains the speed of cutting edge 3ca by differentiating the time-series position coordinates of cutting edge 3ca, and calculates the average of these speeds as the average speed of cutting edge 3ca during excavation work.

[0068] 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 calculate the average speed of the cutting edge 3ca during excavation work by dividing the distance traveled by the cutting edge 3ca by the excavation time.

[0069] 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 sets 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 amount of fuel supplied 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 sets this as the fuel efficiency of the excavation work.

[0070] The cutting edge 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 cutting edge 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 cutting edge 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.

[0071] The cutting edge load calculation unit 54 can calculate the load acting on the cutting edge 3ca of the bucket 3c from the thrust of each cylinder and the moment of the positional relationship of the work implement 3 based on the detection results of the position sensor.

[0072] 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.

[0073] The soil quality determination unit 58 determines the soil quality of the object to be excavated 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.

[0074] Operation data related to the operation of the work machine 3 during excavation work in which the work machine 3 excavates an excavation target includes the attitude of the work machine 3 detected by the position sensor, the oil pressure of each of the cylinders 4a, 4b, and 4c detected by the pressure sensors 6a to 6f, the operation of the operating lever 25a detected by the operation amount sensor 25b, and the fuel injection amount commanded from the engine controller 41 to the governor 32. The 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 the above-mentioned detected data. The correspondence between the operation data and the soil type is stored in the memory unit 59.

[0075] <Simplified N-value> In this embodiment, hardness, which is one of the parameters of soil quality, is estimated from operation data acquired during excavation work. The simplified N-value is used as an index of the hardness of the soil material to be excavated. The simplified N-value is measured using a simplified N-value meter. Figure 5 is a schematic diagram showing the configuration of a simplified N-value meter 200.

[0076] The simplified N-value meter 200 includes 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 a cone (circular) shape as a whole. 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 as not to be able to move relative to the penetration rod 203.

[0077] 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 as not to 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 as to be movable relative to the guide rod 204. The hammer 202 is movable along the guide rod 204 relative to the knocking head 205. The lower surface of the hammer 202 is flat, and the upper surface of the knocking head 205 is also flat.

[0078] The assembly consisting of the tip cone 201, the penetration rod 203, and the knocking head 205 corresponds to an example of a "cone-shaped tip part." The tip cone 201 corresponds to the tip of the "cone-shaped tip part," and the knocking head 205 corresponds to the other end opposite to the tip of the "cone-shaped tip part."

[0079] The simplified N-value is measured as follows: The simplified N-value meter 200 is positioned so that the lower end of the tip cone 201 abuts against the ground surface GL, and the penetration rod 203 and guide rod 204 extend in a direction perpendicular to 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.

[0080] 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 attempts to move downward toward the ground surface GL. The tip cone 201 and the penetration rod 203 attempt 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 predetermined depth (for example, a depth of 10 cm from the ground surface GL) is counted, and this number is taken as the simplified N value.

[0081] <Determining Soil Type of Excavation Target> In this embodiment, the soil type determination unit 58 reads out a correspondence between operation data and the soil type of the excavation target, which corresponds to the operation data acquired during the excavation work, from the storage unit 59. The soil type determination unit 58 determines the soil type of the excavation target from the operation data based on the read-out correspondence. Specifically, the soil type determination unit 58 determines the soil type of the excavation target by applying the acquired operation data to the read-out correspondence.

[0082] 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 above-mentioned simplified N value, 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.

[0083] During excavation work, the work implement attitude acquisition unit 56 acquires the attitude of the work implement 3, and the cutting edge speed calculation unit 52 calculates the average speed of the cutting edge 3ca during excavation work. The soil type determination unit 58 reads the data table shown in FIG. 6 from the storage unit 59 and calculates a simplified N value corresponding to the calculated cutting edge 3ca speed. 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 cutting edge 3ca speed. The soil type determination unit 58 can determine that the lower the cutting edge 3ca speed, the harder the excavation target. Because the simplified N value is one of the soil type parameters, it can be said that the soil type determination unit 58 can determine the soil type of the excavation target from the cutting edge 3ca speed.

[0084] 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.

[0085] During excavation work, the work implement attitude acquisition unit 56 acquires the attitude of the work implement 3, and the earthwork volume calculation unit 51 acquires the cylinder pressure of the boom cylinder 4a to calculate 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 determination unit 58 reads the data table shown in FIG. 7 from the storage unit 59 and calculates a simplified N value corresponding to the calculated work efficiency. 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 work efficiency. The soil type determination unit 58 can determine that the lower the work efficiency, the harder the excavation target. Because the simplified N value is one of the soil type parameters, it can be said that the soil type determination unit 58 can determine the soil type of the excavation target from the work efficiency.

[0086] 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 represents the speed (unit: mm / sec) of the cutting edge 3ca during excavation work, and the vertical axis represents the load (unit: kN) applied to 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 applied to the cutting edge 3ca and the speed of the cutting edge 3ca. A data table shown in Figure 8, which associates the load applied to the cutting edge 3ca with the speed of the cutting edge 3ca, is stored in the memory unit 59.

[0087] FIG. 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 FIG. 9 represents the simplified N value, and the vertical axis represents the load (unit: kN) applied to the cutting edge 3ca. As shown in FIG. 6, there is a good correlation between the speed of the cutting edge 3ca and the simplified N value. As shown in FIG. 8, there is a good correlation between the load applied to the cutting edge 3ca and the speed of the cutting edge 3ca. Therefore, as shown in FIG. 9, it is possible to estimate the simplified N value from the load applied to the cutting edge 3ca. A data table shown in FIG. 9, which associates the load applied to the cutting edge 3ca with the simplified N value, is stored in the memory unit 59.

[0088] During excavation work, the work implement attitude acquisition unit 56 acquires the attitude of the work implement 3, and the cutting edge load calculation unit 54 acquires the pressure of each cylinder detected by the pressure sensors 6a to 6f and calculates 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 a 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. Because the simplified N value is one of the soil type parameters, 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.

[0089] Even if the hydraulic excavator 100 does not have a sensor capable of acquiring operational data for calculating the speed of the cutting edge 3ca, the simplified N value can be estimated as long as the cylinder pressure can be acquired. By attaching an external pressure sensor that detects the cylinder pressure, the simplified N value can also be estimated. This makes it possible to expand the range of work vehicles to which the soil type determination of the embodiment can be applied.

[0090] Figure 15 is a 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.

[0091] 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 economy based on the payload and the amount of fuel supplied. The soil type determination unit 58 reads the data table shown in FIG. 15 from the storage unit 59 and calculates a simplified N value corresponding to the calculated fuel economy. 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 fuel economy. The soil type determination unit 58 can determine that the lower the fuel economy, the harder the excavation target. Because the simplified N value is one of the soil type parameters, it can be said that the soil type determination unit 58 can determine the soil type of the excavation target from the fuel economy.

[0092] FIG. 16 is an eighth diagram showing an example of the correspondence between operation data and soil type. The horizontal axis of the graph shown in FIG. 16 represents the horizontal movement distance of the cutting edge 3ca of the bucket 3c when the excavation start point is set to coordinate zero. The vertical axis of the graph shown in FIG. 16 represents the excavation distance in the depth direction of the cutting edge 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 farther the coordinate on the vertical axis is from zero, the deeper the cutting edge 3ca has reached into the ground. In FIG. 16, the trajectory of the cutting edge 3ca during excavation when the simplified N value, an index of the hardness of the excavation target, is 3 is shown by a thick line, and the trajectory of the cutting edge 3ca during excavation when the simplified N value is 49 is shown by a thin line.

[0093] As shown in Figure 16, the trajectory of the cutting edge 3ca during excavation work varies depending on the hardness of the excavation target. When 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 underground, resulting in a trajectory of the cutting edge 3ca that scrapes away the ground surface. In order to load a larger load L into the bucket 3c, the operator finely adjusts the angle of the cutting edge 3ca and the load applied to the cutting edge 3ca, resulting in many irregularities in the trajectory of the cutting edge 3ca. On the other hand, when the excavation target is soft, the cutting edge 3ca easily penetrates the ground, resulting in a larger excavation distance in the depth direction. Since it is possible to easily load a larger load L into the bucket 3c without finely adjusting the attitude of the bucket 3c, the trajectory of the cutting edge 3ca has fewer irregularities and is a smoother trajectory.

[0094] 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 calculates the excavation distance in the depth direction when the cutting edge 3ca reaches the deepest position underground, and sets the calculated excavation distance in the depth direction as the maximum depth. If the maximum depths are averaged and compared, a correlation with the simplified N value becomes apparent. A data table correlating maximum depths with simplified N values ​​is stored in the memory unit 59.

[0095] The soil type determination unit 58 reads from the storage unit 59 a data table associating maximum depth with a simplified N value, and determines the simplified N value corresponding to the maximum depth. 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 cutting edge 3ca of the bucket 3c that has penetrated into the ground. The soil type determination unit 58 can determine that the smaller the maximum depth, the harder the excavation target. Because 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 trajectory of the cutting edge 3ca.

[0096] Fig. 17 is a ninth diagram showing an example of the correspondence between operation data and soil type. Fig. 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 Figs. 17 and 18 indicates the passage of time during excavation, with the start of excavation being set to time zero.

[0097] The vertical axes of the graphs shown in Figures 17 and 18 represent 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 set to 0%, and the input when the control lever 25a is tilted to its maximum is set to 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.

[0098] Figure 17 shows the cutting edge speed and lever input during excavation when the simplified N value, which is an index of the hardness of the excavation target, is 3. As shown in Figure 17, when the excavation target is soft, the bucket 3c penetrates into the ground easily, making it possible to easily fill the bucket 3c to capacity without using the maximum excavation force of the vehicle body. If care is taken to prevent a decrease in excavation speed due to the bucket 3c being penetrated too deeply into the ground and being overloaded with load L, the excavation speed will not decrease even without making fine adjustments to the operating lever 25a.

[0099] 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, when the excavation target is hard, the bucket 3c has difficulty penetrating the ground and receives a large reaction force from the excavation target, making the work implement 3 more likely to stop. Operating the control lever 25a in the same way as when the excavation target is soft does not allow a large amount of excavation target to be loaded into the bucket 3c. To increase the load capacity of the bucket 3c even at the expense of excavation speed, the operator adjusts the speed of the cutting edge 3ca and the attitude of the work implement 3 during excavation by finely operating the control lever 25a, thereby taking time to excavate while appropriately releasing the load.

[0100] 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 implement attitude acquisition unit 56 acquires the attitude of the work implement 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.

[0101] The soil type determination unit 58 reads from the storage 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 determination unit 58 can determine the simplified N-value, which is an index of the hardness of the object to be excavated, from the operation of the control lever 25a during excavation work. The soil type determination unit 58 can determine that the harder the object to be excavated is, the more finely the control lever 25a is operated during excavation work. Because 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 object to be excavated from the operation of the control lever 25a during excavation work.

[0102] 10 is a side view of the work machine showing its posture when starting a dedicated soil type discrimination operation. Differences in skill and operating habits exist among operators of the hydraulic excavator 100, which can result in variations in the operational 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.

[0103] Specifically, as shown in FIG. 10 , when the hydraulic excavator 100 is viewed from the side, the work implement 3 is positioned so that a 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 this relative position between the arm 3b and the bucket 3c, the length of the arm cylinder 4b is minimized to position the arm 3b at its most extended position. In this position, the arm angle θa ( FIG. 1 ) is minimized. The boom 3a is then operated to bring the cutting edge 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 movement of the arm 3b causes the cutting edge 3ca of the bucket 3c to move in an arc, penetrating the ground. Operational data is acquired until the cutting edge 3ca stops due to the resistance of the excavation target in the ground.

[0104] The operator can choose whether to perform excavation work at will or to perform excavation work using dedicated soil type discrimination operation, depending on the required accuracy of soil type discrimination. For example, when the soil type of the excavation target is likely to change drastically, excavation work using dedicated soil type discrimination operation can be performed. By performing excavation work using dedicated soil type discrimination operation, the accuracy of soil type discrimination can be improved without the influence of the operator.

[0105] FIG. 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 FIG. 11 is the simplified N value, and the vertical axis is the maximum cutting edge speed (unit: mm / sec). As shown in FIG. 11, there is a good correlation between the simplified N value and the maximum speed at which the cutting edge 3ca penetrates into the ground when performing excavation work using the soil type discrimination dedicated operation. The data table shown in FIG. 11, which associates the maximum speed of the cutting edge 3ca with the simplified N value, is stored in the memory unit 59.

[0106] The cutting edge speed calculation unit 52 acquires the posture of the work implement 3 during excavation work performed 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 performed 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 for each unit time, and sets this as the maximum speed of the cutting edge 3ca.

[0107] The soil type discrimination unit 58 reads the data table shown in FIG. 11 from the storage unit 59 and calculates 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 calculate 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 the dedicated soil type discrimination operation. The soil type discrimination unit 58 can determine that the harder the excavation target is, the smaller the maximum cutting edge speed. Because the simplified N value is one of the soil type parameters, 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 the dedicated soil type discrimination operation.

[0108] Figure 12 shows an example of the progress of cutting edge speed during excavation work. The horizontal axis of the graph shown in Figure 12 represents time, and the vertical axis represents cutting edge speed. At time zero, excavation work using a dedicated soil type discrimination operation begins. Figure 12 shows an example of excavating an excavation target with a relatively small simplified N value.

[0109] 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 start of the excavation operation. After passing the peak, the cutting edge 3ca continues to move at a low speed until the excavation operation is completed, 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. Therefore, when performing an operation dedicated to soil type discrimination, the soil type is characterized using the maximum speed of the cutting edge 3ca. This allows the soil type of the excavation target to be accurately distinguished.

[0110] To obtain the maximum speed of the cutting edge 3ca, it is not necessary to acquire operation data for all steps during the excavation work. 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 work during a certain time period after the start of the excavation work, 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 work. Because the soil type can be determined only from operation data at the start of excavation, the process of acquiring operation data can be simplified, and the soil type can be determined quickly.

[0111] 13 is a sixth diagram showing an example of the correspondence between operation data and soil properties. 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: m ３ 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.

[0112] Fig. 14 is a schematic diagram showing a bucket 3c that has penetrated the ground. The bucket 3c shown in Fig. 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 the ground can be calculated by multiplying the area of ​​the bucket 3c that has penetrated the ground as viewed from the side by the width of the bucket 3c. Simply put, the volume of the bucket 3c may be calculated by multiplying the depth of the cutting edge 3ca of the bucket 3c from the ground surface GL by the width of the bucket 3c.

[0113] When performing excavation work using the dedicated soil type discrimination operation, the amount of penetration of the bucket 3c into the ground when the movement of the cutting edge 3ca stops can be calculated. As shown in Figure 13, there is a good correlation between the penetration amount of the bucket 3c when performing the dedicated soil type discrimination operation and the simplified N value. The data table shown in Figure 13, which associates the penetration amount of the bucket 3c into the ground with the simplified N value, is stored in the memory unit 59.

[0114] The penetration amount calculation unit 55 acquires the posture of the work implement 3 during excavation work using 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 a 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 excavated object, 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 smaller the volume of the bucket 3c that penetrated into the ground, the harder the excavated object. Because the simplified N value is one of the soil type parameters, it can be said that the soil type discrimination unit 58 can determine the soil type of the excavated object from the volume of the bucket 3c that penetrated into the ground when performing the dedicated soil type discrimination operation.

[0115] <Others> The operation data related to the operation of the work unit 3 during excavation work is not limited to the examples described in the above embodiment. As shown in Figures 2 and 3, the operation data may include the spool stroke of the control 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 unit 2 detected by the vibration sensor 2f, and the angle of the vehicle body (swinging unit 2) detected by the IMU 8a. The operation data may be data related to the power required to operate the work unit 3 during excavation work, or may be data that can be acquired in conjunction with the operation of the work unit 3.

[0116] The sensor that acquires the operation data may be a sensor that is equipped on the hydraulic excavator 100 at the time of shipping the hydraulic excavator 100. The sensor may also be a sensor that is retrofitted to the hydraulic excavator 100 after shipping the hydraulic excavator 100.

[0117] 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 also be data for part of the excavation process, such as data at the start of excavation or data during excavation.

[0118] The operation data is not limited to data acquired in real time. Only data from excavation work may be extracted from operational data from past work performed by the work machine. The soil type of the excavation target during the past excavation work may be determined from the operation data acquired during that excavation work.

[0119] The soil type determination unit 58 is not limited to 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 instead of the memory unit 59 inside the main controller 50.

[0120] 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 training data in which operation data obtained when an excavation operation is performed on an excavation target is labeled with a simplified N-value measured for the excavation target using the simplified N-value meter 200. The trained soil-type discrimination model may have been trained using a training data set so that, when operation data related to the operation of the work machine is input, the trained soil-type discrimination model outputs a simplified N-value from the operation data.

[0121] The acquisition unit that acquires operation data related to the operation of the work machine 3 is not limited to the 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. The operation data related to the operation of the work machine 3 may be acquired by analyzing the acquired images.

[0122] 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 by a server, tablet computer, or the like external to the hydraulic excavator 100.

[0123] 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. Furthermore, the work machine may be a remote-controlled type that can be operated remotely via wireless communication.

[0124] <Additional Notes> The above description includes the following additional features.

[0125] (Supplementary Note 1) A soil quality discrimination system comprising: a work machine having a work implement; an acquisition unit that acquires operation data related to the operation of the work implement during excavation work in which the work implement is used to excavate an excavation target; and a controller that determines the soil quality from the operation data based on a correspondence between the operation data and the soil quality of the excavation target.

[0126] (Supplementary Note 2) The soil type determination system according to Supplementary Note 1, wherein the work machine includes a bucket having a cutting edge, and the operation data includes a speed of the cutting edge.

[0127] (Supplementary Note 3) The soil type discrimination system according to Supplementary Note 2, wherein the operational data includes a maximum speed at which the cutting edge penetrates into the ground.

[0128] (Supplementary Note 4) The soil type determination system according to any one of Supplementary Note 1 to Supplementary Note 3, wherein the controller determines the soil type from the operation data of a portion during excavation work.

[0129] (Supplementary Note 5) The soil type determination system according to any one of Supplementary Note 1 to Supplementary Note 4, wherein the work machine includes a bucket having a cutting edge, and the operation data includes a load acting on the cutting edge that has penetrated into the ground.

[0130] (Supplementary Note 6) The soil type determination system according to any one of Supplementary Note 1 to Supplementary Note 5, wherein the work machine has a bucket, and the operation data includes a weight of a load loaded in the bucket.

[0131] (Supplementary Note 7) The soil type discrimination system according to Supplementary Note 6, further comprising an engine that generates driving force to operate the work machine, and the operation data includes an amount of fuel supplied to the engine per unit weight of the load.

[0132] (Supplementary Note 8) The soil type discrimination system according to Supplementary Note 6 or Supplementary Note 7, wherein the operation data includes work efficiency of excavation work using the bucket.

[0133] (Supplementary Note 9) The soil type discrimination system according to any one of Supplementary Note 1 to Supplementary Note 8, wherein the work machine has a bucket, and the operation data includes an attitude of the bucket.

[0134] (Supplementary Note 10) The soil type determination system according to Supplementary Note 9, wherein the operational data includes a volume of the bucket penetrated into the ground.

[0135] (Supplementary Note 11) The soil type determination system according to Supplementary Note 9 or Supplementary Note 10, wherein the bucket has a cutting edge, and the operation data includes a trajectory of the cutting edge as it penetrates into the ground.

[0136] (Supplementary Note 12) The soil type discrimination system according to any one of Supplementary Note 1 to Supplementary Note 11, further comprising an operation device that accepts an operation to drive the work machine, and the operation data includes an operation content of the operation device.

[0137] (Supplementary Note 13) The soil type discrimination system according to any one of Supplementary Note 1 to Supplementary Note 12, wherein the work machine is controlled to perform a predetermined operation during excavation work.

[0138] (Supplementary Note 14) The soil type discrimination system according to any one of Supplementary Note 1 to Supplementary Note 13, wherein the acquisition unit is mounted on the work machine.

[0139] (Appendix 15) The soil quality discrimination system according to any one of Appendices 1 to 14, wherein the soil quality is an index obtained by applying an impact to a part with a cone-shaped tip on the ground from the opposite side of the tip, and then measuring the number of impacts it takes for the tip to penetrate to a predetermined depth.

[0140] Although the embodiments have been described above, the embodiments disclosed herein are illustrative in all respects and should not be considered limiting. The scope of the present invention is defined by the claims, not by the above description, and is intended to include all modifications within the meaning and scope of the claims.

[0141] 1 Traveling body, 2 Swing body, 2f Vibration sensor, 3 Work machine, 3a Boom, 3b Arm, 3c Bucket, 3ca Cutting edge, 3cb Bottom, 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 volume 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

1. A soil type discrimination system comprising: a work machine having a work implement; an acquisition unit that acquires operation data related to the operation of the work implement during excavation work in which the work implement is used to excavate an object to be excavated; and 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 object to be excavated.

2. The soil type discrimination system according to claim 1, wherein the work machine includes a bucket having a cutting edge, and the operation data includes a speed of the cutting edge.

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.

4. The soil type determination system according to claim 3, wherein the controller determines the soil type from the operation data of a portion during an excavation operation.

5. The soil type discrimination system according to claim 1, wherein the work machine includes a bucket having a cutting edge, and the operation data includes a load acting on the cutting edge that has penetrated into the ground.

6. The soil type discrimination system according to claim 1, wherein the work machine has a bucket, and the operation data includes a weight of a load loaded in the bucket.

7. The soil type discrimination system according to claim 6, further comprising an engine that generates driving force to operate the work machine, and the operation data includes an amount of fuel supplied to the engine per unit weight of the load.

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

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

10. The soil type determination system of claim 9, wherein the operational data includes a volume of the bucket penetrated into the earth.

11. The soil type discrimination system according to claim 9, wherein the bucket has a cutting edge, and the operational data includes a trajectory of the cutting edge as it penetrates into the ground.

12. The soil type discrimination system according to claim 1, further comprising an operating device that accepts operations to drive the work machine, and the operation data includes the operation content of the operating device.

13. A 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.

14. A soil type discrimination system according to any one of claims 1 to 12, wherein the acquisition unit is mounted on the work machine.

15. A soil type discrimination system as claimed in any one of claims 1 to 12, wherein the soil type is an index obtained based on the number of times a cone-shaped tip is placed against the ground and impacted from the opposite side of the tip until the tip penetrates to a specified depth.

16. A soil type discrimination method comprising: acquiring operation data related to the operation of a work machine during an excavation operation in which the work machine is used to excavate an excavation target; and discriminating 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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