excavator

Abstract

To provide an excavator capable of achieving more efficient excavation.SOLUTION: An excavator 100 includes: an undercarriage 1; an upper rotating body 3 mounted on the undercarriage 1 rotatably; an attachment AT attached to the upper rotating body 3; a status detection unit DT for detecting the status of the attachment AT; an actuator AC for driving the attachment AT; and a controller 30 that controls the movement of the actuator AC. The controller 30 is configured so as to, when the physical quantity representing the attachment status (AT) derived based on the output of the status detection unit (DT) reaches a certain threshold, control the movement of the actuator AC in such a way that the movement of the actuator AC is different when the excavation target is hard and when the excavation target is heavy.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a shovel.

Background Art

[0002] Conventionally, there is known a shovel that raises the boom so that the excavation reaction force decreases when the excavation reaction force exceeds a predetermined value (see Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, the above-described shovel raises the boom as long as the excavation reaction force exceeds a predetermined value, regardless of the state of the excavation target such as the hardness or weight of the earth and sand. Therefore, there is a possibility that efficient excavation cannot be achieved depending on the state of the excavation target.

[0005] In view of the above, it is desirable to provide a shovel that can achieve more efficient excavation.

Means for Solving the Problems

[0006] The excavator according to an embodiment of the present disclosure includes a lower traveling body, an upper revolving body rotatably mounted on the lower traveling body, an attachment attached to the upper revolving body, a state detection device that detects the state of the attachment, an actuator that operates the attachment, and a control device that controls the movement of the actuator. The control device controls the movement of the actuator so that the movement of the actuator is different when the excavation target is hard and when the excavation target is heavy when a physical quantity representing the state of the attachment derived based on the output of the state detection device reaches a predetermined threshold value.

Advantages of the Invention

[0007] The above-described excavator can achieve more efficient excavation.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Embodiments for Carrying Out the Invention

[0009] First, referring to FIG. 1, an excavator (shovel 100) as a construction machine according to an embodiment of the present disclosure will be described. FIG. 1 is a side view of the shovel 100 according to an embodiment of the present disclosure. On the lower traveling body 1 of the shovel 100 shown in FIG. 1, an upper slewing body 3 is rotatably mounted via a slewing mechanism 2. And, a boom 4 is attached to the upper slewing body 3, an arm 5 is attached to the tip of the boom 4, and a bucket 6 is attached to the tip of the arm 5. In this document, for convenience, the side of the upper slewing body 3 to which the boom 4 is attached is defined as the front, and the side to which the counterweight is attached is defined as the rear. The boom 4, the arm 5, and the bucket 6 as working elements constitute an attachment AT. The attachment AT is also called an excavation attachment. The boom 4 is driven by a boom cylinder 7, the arm 5 is driven by an arm cylinder 8, and the bucket 6 is driven by a bucket cylinder 9. The boom cylinder 7, the arm cylinder 8, and the bucket cylinder 9 are an example of an actuator AC.

[0010] An attitude detection device M1 is attached to the attachment AT. The attitude detection device M1 is an example of a state detection device DT that detects the state of the attachment AT. The state detection device DT is also called a state sensor. Specifically, the attitude detection device M1 is configured to be able to detect the attitude of the attachment AT. In the illustrated example, the attitude detection device M1 includes a boom angle sensor M1a, an arm angle sensor M1b, and a bucket angle sensor M1c.

[0011] The boom angle sensor M1a is a sensor that acquires the boom angle. For example, it can be a rotation angle sensor that detects the rotation angle of the boom 4 around the boom foot pin, a stroke sensor that detects the stroke amount of the boom cylinder 7, an inclination (acceleration) sensor that detects the inclination angle of the boom 4, etc. The same applies to the arm angle sensor M1b and the bucket angle sensor M1c.

[0012] In addition, the upper slewing body 3 is provided with a cabin 10 as an operator's cab, and a power source such as an engine 11 is mounted. Inside the cabin 10, an operating device 26, a controller 30, a display device 40, a sound output device 45, etc. are provided. The power source may be an electric motor. Also, a space recognition device 70, a positioning device 71, a communication device 72, etc. are attached to the upper slewing body 3.

[0013] The space recognition device 70 is an example of a state detection device DT and is also called an environmental sensor. In the illustrated example, the space recognition device 70 is configured to recognize the space around the excavator 100. Also, the space recognition device 70 may be configured to detect an object existing around the excavator 100. The object is, for example, a person, an animal, a vehicle, a construction machine, a building, or a hole, etc. Specifically, the space recognition device 70 is a ultrasonic sensor, a millimeter-wave radar, a distance measurement sensor, an imaging device, or an infrared sensor, etc. The imaging device is, for example, a monocular camera, a stereo camera, a LIDAR, or a distance image sensor, etc. The monocular camera may be an RGB camera or an RGB-D camera. The same applies to the stereo camera. In the illustrated example, the space recognition device 70 includes a rear camera 70B attached to the rear end of the upper surface of the upper slewing body 3, a front camera 70F attached to the front end of the upper surface of the cabin 10, a left camera 70L attached to the left end of the upper surface of the upper slewing body 3, and a right camera 70R attached to the right end of the upper surface of the upper slewing body 3.

[0014] The space recognition device 70 may be configured to detect a predetermined object (e.g., a person) within a predetermined area set around the excavator 100. For example, the space recognition device 70 may be configured to distinguish and detect a person from an object other than a person.

[0015] The positioning device 71 is configured to measure the position of the upper swing body 3. The positioning device 71 may be configured to measure the orientation of the upper swing body 3. The state detection device DT may include the positioning device 71. In the present embodiment, the positioning device 71 is, for example, a GNSS compass, which detects the position and orientation of the upper swing body 3 and outputs the detected values to the controller 30. Therefore, the positioning device 71 can function as an orientation detection device that detects the orientation of the upper swing body 3. The orientation detection device may be an azimuth sensor attached to the upper swing body 3.

[0016] The communication device 72 controls communication with an external device outside the excavator 100. In the present embodiment, the communication device 72 controls communication with an external device via a satellite communication network, a mobile phone communication network, the Internet, or the like. The external device may be, for example, a management device such as a server installed in an external facility, or an assistance device such as a smartphone carried by an operator around the excavator 100. The external device is configured to manage construction information related to, for example, one or more excavators 100. The construction information includes information related to at least one of, for example, the operating time, fuel consumption, and work volume of the excavator 100. The work volume is, for example, the amount of earth and sand excavated and the amount of earth and sand loaded on the dump truck bed. The excavator 100 is configured to transmit construction information related to the excavator 100 to the external device at a predetermined time interval via the communication device 72. Further, the excavator 100 is configured to receive information related to the design surface and the like via the communication device 72.

[0017] FIG. 2 is a side view of the excavator 100 showing various physical quantities related to the attachment AT. The boom angle sensor M1a acquires, for example, the boom angle θ1. The boom angle θ1 is the angle with respect to the horizontal line of the line segment P1 - P2 connecting the boom foot pin position P1 and the arm connection pin position P2 in the XZ plane of the XYZ three - dimensional orthogonal coordinate system. Here, the X - axis is an axis parallel to the front - rear axis of the excavator 100, the Y - axis is an axis parallel to the left - right axis of the excavator 100, and the Z - axis is an axis parallel to the slewing axis of the excavator 100. The arm angle sensor M1b acquires, for example, the arm angle θ2. The arm angle θ2 is the angle with respect to the horizontal line of the line segment P2 - P3 connecting the arm connection pin position P2 and the bucket connection pin position P3 in the XZ plane. The bucket angle sensor M1c acquires, for example, the bucket angle θ3. The bucket angle θ3 is the angle with respect to the horizontal line of the line segment P3 - P4 connecting the bucket connection pin position P3 and the bucket tip position P4 in the XZ plane. Note that the bucket angle θ3 may be calculated based on the operation content of the operating device 26. For example, the bucket angle θ3 may be calculated based on the outputs of the pilot pressure sensors 15a, 15b, etc. In this case, the bucket angle sensor M1c may be omitted.

[0018] Next, the basic system of the excavator 100 will be described with reference to FIG. 3. The basic system of the excavator 100 mainly includes an engine 11, a main pump 14, a pilot pump 15, a control valve unit 17, an operating device 26, a controller 30, a display device 40, a sound output device 45, an engine control device 74, an attitude detection device M1, and a cylinder pressure sensor S1, etc.

[0019] The engine 11 is a drive source of the excavator 100 and is, for example, a diesel engine that operates to maintain a predetermined rotational speed. The output shaft of the engine 11 is connected to the input shafts of the main pump 14 and the pilot pump 15.

[0020] The main pump 14 is a hydraulic pump that supplies hydraulic oil to the control valve unit 17 via the hydraulic oil line 16, and is, for example, an inclined plate type variable displacement hydraulic pump. In an inclined plate type variable displacement hydraulic pump, the stroke length of the piston that determines the displacement volume changes according to the change in the inclined plate tilting angle, and the discharge flow rate per revolution changes. The inclined plate tilting angle is controlled by the regulator 14a. The regulator 14a changes the inclined plate tilting angle according to the change in the control current from the controller 30. For example, the regulator 14a increases the inclined plate tilting angle in response to an increase in the control current to increase the discharge flow rate of the main pump 14. The discharge pressure sensor 14b detects the discharge pressure of the main pump 14. The oil temperature sensor 14c detects the temperature of the hydraulic oil sucked by the main pump 14.

[0021] The pilot pump 15 is a hydraulic pump for supplying hydraulic oil to various hydraulic control devices such as the operating device 26 via the pilot line 25, and is, for example, a fixed displacement hydraulic pump. However, the pilot pump 15 may be omitted. In this case, the function that the pilot pump 15 was responsible for may be realized by the main pump 14. That is, the main pump 14 may be provided with a circuit separate from the function of supplying hydraulic oil to the control valve unit 17, and may have a function of supplying hydraulic oil to the operating device 26 etc. after reducing the supply pressure of the hydraulic oil by means of a throttle or the like.

[0022] The control valve unit 17 is configured to be able to control the flow of hydraulic oil related to the hydraulic actuator. In the illustrated example, the control valve unit 17 includes a plurality of flow control valves. The flow control valve is typically a spool valve. The control valve unit 17 can selectively supply the hydraulic oil received from the main pump 14 through the hydraulic oil line 16 to one or more hydraulic actuators according to the change in the pressure (pilot pressure) corresponding to the operation direction and operation amount of the operating device 26. The hydraulic actuators are, for example, the boom cylinder 7, the arm cylinder 8, the bucket cylinder 9, the left traveling hydraulic motor 1A, the right traveling hydraulic motor 1B, and the slewing hydraulic motor 2A, etc. Note that the hydraulic actuator may be replaced by an electric actuator.

[0023] The operating device 26 is a device used by the operator for operating the hydraulic actuator and includes an operating lever, an operating pedal, etc. The operating device 26 receives the supply of hydraulic oil from the pilot pump 15 through the pilot line 25 to generate a pilot pressure. Then, the operating device 26 applies the pilot pressure to the pilot port of the corresponding flow control valve through the pilot line 25a. The pilot pressure changes according to the operation direction and operation amount of the operating device 26. The operating device 26 may be remotely operated. In this case, the operating device 26 generates a pilot pressure according to the information on the operation direction and operation amount received via wireless communication.

[0024] The operating device 26 may be an electric operating device instead of the hydraulic operating device as described above. In this case, a solenoid valve for adjusting the pilot pressure may be arranged between the flow control valve in the control valve unit 17 and the pilot pump 15. And the information on the operation direction and operation amount of the electric operating device is transmitted from the electric operating device to the controller 30 as an electric signal. The controller 30 can adjust the magnitude of the pilot pressure acting on the flow control valve by adjusting the opening area of the solenoid valve according to the electric signal received from the electric operating device. Alternatively, the controller 30 may directly operate the flow control valve as a solenoid valve according to the electric signal received from the electric operating device.

[0025] The controller 30 is a control device for controlling the excavator 100. In the illustrated example, the controller 30 is composed of a computer including a CPU, a volatile memory device, a non-volatile memory device, and the like. The CPU of the controller 30 reads out programs corresponding to various functions from the non-volatile memory device, loads them into the volatile memory device, and executes them, thereby realizing the functions corresponding to each of those programs.

[0026] For example, the controller 30 realizes a function of controlling the discharge flow rate of the main pump 14. In the illustrated example, the controller 30 changes the magnitude of the control current to the regulator 14a according to the pressure of the hydraulic oil in the negative control throttle, and controls the discharge flow rate of the main pump 14 via the regulator 14a.

[0027] The display device 40 is a device for displaying various information, and is arranged near the driver's seat in the cab 10. In the illustrated example, the display device 40 has an image display unit 41 and an input unit 42. The image display unit 41 is a liquid crystal display. The input unit 42 is a membrane switch. The operator can input information and commands to the controller 30 by using the input unit 42. Also, the operator can grasp the operating status and control information of the excavator 100 by looking at the image display unit 41.

[0028] The display device 40 operates by receiving power supply from the storage battery 90. In the illustrated example, the storage battery 90 is charged with the power generated by the alternator 11a. The power of the storage battery 90 is also supplied to other devices other than the controller 30 and the display device 40, such as the positioning device 71 and the communication device 72. The starter 11b of the engine 11 can be driven by the power from the storage battery 90 to start the engine 11.

[0029] The sound output device 45 is a device for outputting sound information. In the illustrated example, the sound output device 45 is a speaker arranged near the driver's seat in the cab 10. The sound output device 45 may be a buzzer.

[0030] The engine control device 74 is a device that controls the engine 11. The engine control device 74 controls, for example, the fuel injection amount and the like so that the engine speed set via the input device is realized.

[0031] The engine 11 is controlled by the engine control device 74. The engine control device 74 transmits various data indicating the state of the engine 11 (for example, data regarding physical quantities such as data indicating the coolant water temperature detected by the water temperature sensor 11c) to the controller 30. The controller 30 stores those data in the temporary storage unit (memory) 30a and can transmit them to the display device 40 or the like as necessary. The same applies to the data indicating the swash plate tilt angle output by the regulator 14a, the data indicating the discharge pressure of the main pump 14 output by the discharge pressure sensor 14b, the data indicating the operating oil temperature output by the oil temperature sensor 14c, and the data indicating the pilot pressure output by the pilot pressure sensors 15a and 15b.

[0032] The cylinder pressure sensor S1 is an example of the state detection device DT, detects the pressure of the hydraulic oil in the hydraulic cylinder such as the boom cylinder 7, and outputs the detected data to the controller 30. In the illustrated example, the cylinder pressure sensor S1 includes cylinder pressure sensors S11 to S16. Specifically, the cylinder pressure sensor S11 detects the boom bottom pressure, which is the pressure of the hydraulic oil in the bottom side oil chamber of the boom cylinder 7. Further, the cylinder pressure sensor S12 detects the boom rod pressure, which is the pressure of the hydraulic oil in the rod side oil chamber of the boom cylinder 7. Similarly, the cylinder pressure sensor S13 detects the arm bottom pressure, the cylinder pressure sensor S14 detects the arm rod pressure, the cylinder pressure sensor S15 detects the bucket bottom pressure, and the cylinder pressure sensor S16 detects the bucket rod pressure.

[0033] The control valve E1 is a valve that operates according to a command from the controller 30. In the illustrated example, the control valve E1 is used to forcibly operate a flow control valve for a predetermined hydraulic cylinder regardless of the content of the operation input to the operating device 26. When the above-described electric operating device is adopted, the control valve E1 corresponds to a solenoid valve disposed between the flow control valve and the pilot pump 15, or a flow control valve as a solenoid valve.

[0034] FIG. 4 is a diagram showing a configuration example of an excavation control system mounted on the excavator 100 of FIG. 1. The excavation control system mainly includes a state detection device DT, a positioning device 71, a communication device 72, a controller 30, a control valve E1, a display device 40, and a sound output device 45. The state detection device DT includes an attitude detection device M1, a cylinder pressure sensor S1, and a space recognition device 70. The controller 30 includes an autonomous control unit 31 and a determination unit 32.

[0035] The autonomous control unit 31 is configured to control the excavator 100 so that the excavator 100 can operate autonomously. The autonomous operation of the excavator 100 is an operation of the excavator 100 performed without an operation input through the operation device 26 by the operator. That is, the excavator 100 is controlled unmanned by the autonomous control unit 31. In the illustrated example, the autonomous control unit 31 generates a target trajectory based on the information on the position of the excavator 100 acquired by the positioning device 71, the information on the design surface acquired through the communication device 72, and the information on the ground around the excavator 100 acquired by the space recognition device 70. The target trajectory is, for example, a trajectory followed by a point corresponding to a predetermined part of the attachment AT. The predetermined part of the attachment AT is, for example, the tip (toe) of the bucket 6 or a point on the back surface of the bucket 6. In the illustrated example, the target trajectory is a line followed by a point (toe point) corresponding to the tip (toe) of the bucket 6.

[0036] The autonomous control unit 31 may generate a target trajectory before starting each excavation operation, or may collectively generate target trajectories for multiple excavation operations. Specifically, the autonomous control unit 31 outputs a control command to the control valve E1 so that the tip point follows the target trajectory, and expands and contracts at least one of the boom cylinder 7, the arm cylinder 8, and the bucket cylinder 9.

[0037] Also, the autonomous control unit 31 typically expands and contracts at least one of the boom cylinder 7, the arm cylinder 8, and the bucket cylinder 9 so that the moving speed of the tip point moving on the target trajectory (tip moving speed) becomes a predetermined moving speed.

[0038] The determination unit 32 is configured to be able to perform various determinations. In the illustrated example, the determination unit 32 is configured to be able to determine whether it is necessary to correct the target trajectory. Specifically, the determination unit 32 determines whether a predetermined target trajectory correction condition is satisfied. The target trajectory correction condition is, for example, "the state of the attachment AT has become a predetermined state". "The state of the attachment AT has become a predetermined state" is, for example, that the output value of the cylinder pressure sensor S1 has exceeded a predetermined threshold value (such as the boom rod pressure exceeding a predetermined threshold value), the excavation reaction force has exceeded a predetermined threshold value, or the tip moving speed has fallen below a predetermined threshold value, etc.

[0039] The determination unit 32 is configured to calculate the excavation reaction force based on at least the output of the cylinder pressure sensor S1. In the illustrated example, the determination unit 32 calculates the excavation reaction force based on the output of the cylinder pressure sensor S1 and the attitude of the attachment AT detected by the attitude detection device M1. The determination unit 32 may additionally use the output of the vehicle body inclination sensor when calculating the excavation reaction force. The vehicle body inclination sensor may be configured by, for example, an acceleration sensor or a gyro sensor.

[0040] The output of the cylinder pressure sensor S1 includes, for example, at least one of the boom bottom pressure, boom rod pressure, arm bottom pressure, arm rod pressure, bucket bottom pressure, and bucket rod pressure detected by the cylinder pressure sensors S11 to S16.

[0041] The determination unit 32 may calculate the cylinder thrust based on the output of the cylinder pressure sensor S1. The cylinder thrust is calculated, for example, based on the cylinder pressure and the pressure receiving area of the piston sliding inside the cylinder. The cylinder thrust includes, for example, as shown in FIG. 2, the boom cylinder thrust (f1), the arm cylinder thrust (f2), and the bucket cylinder thrust (f3). Specifically, the boom cylinder thrust (f1) is represented by the difference between the cylinder extension force, which is the product of the boom bottom pressure and the pressure receiving area of the piston in the boom bottom side oil chamber, and the cylinder contraction force, which is the product of the boom rod pressure and the pressure receiving area of the piston in the boom rod side oil chamber. The same applies to the arm cylinder thrust (f2) and the bucket cylinder thrust (f3).

[0042] The determination unit 32 may calculate the excavation torque based on the posture of the attachment AT and the cylinder thrust. The magnitude of the bucket excavation torque (τ3) is represented, as shown in FIG. 2, by the value obtained by multiplying the magnitude of the bucket cylinder thrust (f3) by the distance G3 between the action line of the bucket cylinder thrust (f3) and the bucket connection pin position P3. The distance G3 is a function of the bucket angle θ3. The same applies to the boom excavation torque (τ1) and the arm excavation torque (τ2). Note that the distance G1 is the distance between the action line of the boom cylinder thrust (f1) and the boom foot pin position P1, and the distance G2 is the distance between the action line of the arm cylinder thrust (f2) and the arm connection pin position P2.

[0043] The excavation reaction force F is calculated as the product of a mechanism function taking the boom angle θ1, arm angle θ2, and bucket angle θ3 as arguments, as shown in FIG. 2 for example, and a function taking the boom excavation torque (τ1), arm excavation torque (τ2), and bucket excavation torque (τ3) as arguments. The function taking the boom excavation torque (τ1), arm excavation torque (τ2), and bucket excavation torque (τ3) as arguments may be a function taking the boom cylinder thrust (f1), arm cylinder thrust (f2), and bucket cylinder thrust (f3) as arguments.

[0044] The function taking the boom angle θ1, arm angle θ2, and bucket angle θ3 as arguments may be based on the force balance equation, may be based on the Jacobian, or may be based on the principle of virtual work.

[0045] Thus, the value of the excavation reaction force is derived based on the detection values of various sensors at the current time. However, the detection value of the cylinder pressure sensor S1 may be directly used as the value of the excavation reaction force. Alternatively, the value of the cylinder thrust calculated based on the detection value of the cylinder pressure sensor S1 may be used as the value of the excavation reaction force. Alternatively, the value of the excavation torque calculated based on the value of the cylinder thrust calculated based on the detection value of the cylinder pressure sensor S1 and the value related to the attitude of the attachment AT derived based on the detection value of the attitude detection device M1 may be used as the value of the excavation reaction force.

[0046] The tip movement speed is calculated as the distance between the tip point at the first time point and the tip point at the second time point. The time interval between the first time point and the second time point is a preset value.

[0047] When the determination unit 32 determines that a predetermined target trajectory correction condition is satisfied, the autonomous control unit 31 corrects the target trajectory. In the illustrated example, the autonomous control unit 31 newly generates another target trajectory extending from a point on the already generated target trajectory.

[0048] Here, referring to FIGS. 5 and 6, an example of the process in which the controller 30 corrects the target trajectory (hereinafter referred to as the "target trajectory correction process") will be described. FIG. 5 is a flowchart showing an example of the flow of the target trajectory correction process. FIG. 6 is a schematic diagram of the work site when the target trajectory correction process is performed, and includes a cross-section of the ground to be excavated. In the illustrated example, the autonomous control unit 31 of the controller 30 generates the target trajectory TR1 based on the information on the position of the excavator 100 acquired by the positioning device 71, the information on the design surface acquired through the communication device 72, and the image of the ground in front of the excavator 100 captured by the front camera 70F. The target trajectory TR1 is a trajectory connecting the excavation start point C1 and the excavation end point C3, and is represented by a dashed line in FIG. 6. Then, the autonomous control unit 31 outputs a control command to the control valve E1 to expand and contract at least one of the boom cylinder 7, the arm cylinder 8, and the bucket cylinder 9, and moves the tip point along the target trajectory TR1. The controller 30 repeatedly executes this target trajectory correction process at a predetermined control cycle while such control by the autonomous control unit 31 is being performed.

[0049] First, the determination unit 32 of the controller 30 determines whether or not the internal pressure of the cylinder has reached a first threshold value (step ST1). The internal pressure of the cylinder is a value detected by the cylinder pressure sensor S1, and is, for example, the boom rod pressure. Specifically, the determination unit 32 determines whether or not the boom rod pressure has reached a first threshold value registered in advance. This determination is an example of determining whether or not a predetermined target trajectory correction condition is satisfied.

[0050] And when it is determined that the internal pressure of the cylinder has not reached the first threshold value (NO in step ST1), the controller 30 ends the current target trajectory correction process without correcting the target trajectory TR1. Therefore, the autonomous control unit 31 continues to move the tip point along the target trajectory TR1.

[0051] On the other hand, when it is determined that the internal pressure of the cylinder has reached the first threshold value (YES in step ST1), the controller 30 corrects the target trajectory TR1 (step ST2). In the example shown in FIG. 6, the controller 30 determines that the boom rod pressure has reached the first threshold value when the claw tip point is located at point C2, and generates a corrected target trajectory TR2 extending from point C2. The corrected target trajectory TR2 is a trajectory connecting point C2 and the excavation end point C4, and is represented by a two-dot chain line in FIG. 6. The controller 30 may be configured to generate a plurality of corrected target trajectories TR2 and select one of the plurality of corrected target trajectories TR2.

[0052] Further, the autonomous control unit 31 is configured to generate the corrected target trajectory TR2 such that the difference between the volume of the region Z1 and the volume of the region Z2 is less than a predetermined value. The predetermined value may be a pre-registered value or a value dynamically calculated according to the properties of the earth and sand, etc. In the example shown in FIG. 6, the autonomous control unit 31 generates the corrected target trajectory TR2 such that the difference between the volume of the region Z1 and the volume of the region Z2 becomes zero, that is, the volumes of the region Z1 and the region Z2 are the same. The volume of the region Z1 is the volume of the earth and sand that is excavated when following the target trajectory TR1 but is not excavated when following the corrected target trajectory TR2, and is calculated by multiplying the area of the range represented by the fine (dense) dot pattern in FIG. 6 by the width of the bucket 6 which is a specified value. The volume of the region Z2 is the volume of the earth and sand that is not excavated when following the target trajectory TR1 but is excavated when following the corrected target trajectory TR2, and is calculated by multiplying the area of the range represented by the coarse dot pattern in FIG. 6 by the width of the bucket 6. That is, the autonomous control unit 31 generates the corrected target trajectory TR2 such that the volume of the earth and sand excavated when the tip point follows the target trajectory TR1 is the same as the volume of the earth and sand excavated when the tip point follows the corrected target trajectory TR2. This is to ensure the initial excavation amount (volume). However, the autonomous control unit 31 may generate the corrected target trajectory TR2 such that the weight of the earth and sand excavated when the tip point follows the target trajectory TR1 is the same as the weight of the earth and sand excavated when the tip point follows the corrected target trajectory TR2. In this case, the weight of the earth and sand is calculated by multiplying the volume of the earth and sand by the density of the earth and sand. The density of the earth and sand may be a preset value or a value calculated based on the output of the state detection device DT, etc. Also, the description with reference to FIG. 6 relates to the case of excavating a flat ground, but it is similarly applicable to the case of excavating an uneven ground. In this case, the volume of each of the regions Z1 and Z2 may be calculated as a value reflecting the unevenness of the ground based on the output of the space recognition device 70.

[0053] Further, the autonomous control unit 31 generates the corrected target trajectory TR2 such that the depth DP2 of the corrected target trajectory TR2 is shallower than the depth DP1 of the target trajectory TR1. This is to reduce the excavation reaction force by correcting the target trajectory TR1. Note that both the depth DP1 and the depth DP2 are depths from the reference plane RP. In the illustrated example, the reference plane RP is a virtual plane including the bottom surface (ground contact surface GP) of the lower traveling body 1.

[0054] Further, the autonomous control unit 31 generates the corrected target trajectory TR2 such that the distance D1 between the excavation end point C3 of the target trajectory TR1 and the excavation end point C4 of the corrected target trajectory TR2 is a value of zero or more, and the excavation end point C4 does not exceed the design surface DS. In the illustrated example, the excavation end point C3 and the excavation end point C4 are located on the reference plane RP.

[0055] Further, when moving the bucket tip point along the corrected target trajectory TR2, the autonomous control unit 31 operates the attachment AT so that the excavation angle θA (see FIG. 9) formed between the extension line of the bucket tip and the reference plane RP does not become larger than the excavation angle θA when the bucket tip point is at point C2. This is to reduce the excavation reaction force by correcting the target trajectory TR1. That is, the excavation angle θA when moving the bucket tip point along the corrected target trajectory TR2 is the same as or smaller than the excavation angle θA when the bucket tip point is at point C2.

[0056] Next, with reference to FIGS. 7 and 8, an example of a process of moving the attachment AT in order for the controller 30 to shift the tip point from the position on the target trajectory TR1 to the position on the corrected target trajectory TR2 (hereinafter referred to as "attachment drive process") will be described. FIG. 7 is a flowchart showing an example of the flow of the attachment drive process. FIG. 8 is a graph showing an example of the time change of the tip movement speed V. In the illustrated example, when the determination unit 32 in the target trajectory correction process determines that a predetermined target trajectory correction condition is satisfied (in the example shown in FIG. 5, when the determination unit 32 determines that the internal pressure in the cylinder has reached the first threshold value), the controller 30 executes this attachment drive process. This is to realize the movement of the attachment AT suitable for the state of the earth and sand to be excavated.

[0057] First, the determination unit 32 determines whether or not the deceleration of the tip movement speed is less than the deceleration threshold (step ST11). This is to determine the state of the excavation target. Specifically, it is to determine whether the earth and sand (the earth and sand in contact with the tip) to be excavated is hard earth and sand or heavy earth and sand. In the present embodiment, heavy earth and sand is earth and sand containing a large amount of moisture, that is, earth and sand having a large density, and is typically earth and sand contained in a mud layer or the like spreading over a relatively wide range. On the other hand, hard earth and sand is earth and sand containing almost no moisture, that is, earth and sand surrounded by earth and sand having a small density, and is typically dry clay buried in a soft sand layer. The determination of whether the earth and sand is hard or heavy is performed based on time-series information such as the internal pressure in the cylinder, the cylinder thrust, the excavation torque, the tip movement speed, the tip movement acceleration, or the excavation reaction force. The time-series information is recorded in a volatile memory device or a non-volatile memory device.

[0058] Specifically, the determination unit 32 determines the state of the earth and sand based on the tip movement speed V. The determination of the state of the earth and sand may be, for example, a determination of whether the earth and sand causes a rapid increase in the excavation reaction force or a slow increase in the excavation reaction force, a determination of whether the earth and sand is cohesive soil or sandy soil, a determination of whether the earth and sand is homogeneous earth and sand containing a large amount of moisture or heterogeneous earth and sand containing little moisture (including rock), etc. In the illustrated example, as shown in FIG. 8, the determination unit 32 determines whether or not the decrease DF of the tip movement speed V in the monitoring period DR, which is a predetermined period preceding the time point t3 when it is determined that a predetermined target trajectory correction condition is satisfied, is less than the decrease threshold value DFt. This determination is based on the fact that when excavating heavy earth and sand containing a large amount of moisture, the tip movement speed V decreases gradually, while when excavating hard earth and sand containing little moisture, the tip movement speed V tends to decrease rapidly. Note that the determination unit 32 may determine the state of the earth and sand based on the maximum value, average value, median value, or intermediate value of the tip movement speed V or its deceleration in the monitoring period DR. In this way, the determination unit 32 determines the state of the earth and sand based on how the tip movement speed V changes (decreases).

[0059] The monitoring period DR is a preset period, and typically is a period with the time point when it is determined that a predetermined target trajectory correction condition is satisfied as the end point. However, the monitoring period DR may be a period before the time point t3 that does not include the time point t3, or may include a period after the time point t3. In the illustrated example, the monitoring period DR is the period from the time point t2 to the time point t3.

[0060] In the example shown in FIG. 8, the dotted line TL1 indicates the temporal change of the tip movement speed V when it is determined that the soil is heavy soil, and the solid line TL2 indicates the temporal change of the tip movement speed V when it is determined that the soil is hard soil. Specifically, FIG. 8 shows that when it is determined that the soil is heavy soil, the tip movement speed V when the tip of the bucket 6 contacts the ground at time t1 is the value V1, and the tip movement speed V has decreased to the value V2 when time t2 is reached. On the other hand, FIG. 8 shows that when it is determined that the soil is hard soil, the tip movement speed V when the tip of the bucket 6 contacts the ground at time t1 is the value V1, and the tip movement speed V is still the value V1 even when time t2 is reached.

[0061] When the tip movement speed V changes along the dotted line TL1, the determination unit 32 determines that the decrease DF1 of the tip movement speed V during the monitoring period DR is less than the decrease threshold value DFt. That is, the determination unit 32 determines that the soil to be excavated is heavy soil. On the other hand, when the tip movement speed V changes along the solid line TL2, the determination unit 32 determines that the decrease DF2 of the tip movement speed V during the monitoring period DR exceeds the decrease threshold value DFt. That is, the determination unit 32 determines that the soil to be excavated is hard soil.

[0062] When it is determined that the deceleration DF1 of the tip movement speed V is lower than the deceleration threshold value DFt (YES in step ST11), the autonomous control unit 31 executes boom raising (step ST12). Specifically, when the autonomous control unit 31 determines that the earth and sand to be excavated is heavy earth and sand, without closing the bucket 6, by raising the boom 4, the tip point is shifted from the target trajectory TR1 to the corrected target trajectory TR2. If the bucket 6 is closed when shifting the tip point from the target trajectory TR1 to the corrected target trajectory TR2, a downward excavation reaction force, that is, a force in the direction of tipping the shovel 100 forward (a force in the direction of lifting the rear part of the shovel 100) is likely to occur. In other words, when the autonomous control unit 31 determines that the earth and sand to be excavated is heavy earth and sand, by avoiding the execution of bucket closing when shifting the tip point from the target trajectory TR1 to the corrected target trajectory TR2, the forward tipping of the shovel 100 can be suppressed.

[0063] On the other hand, when it is determined that the deceleration DF1 of the tip movement speed V is not lower than the deceleration threshold value DFt (NO in step ST11), the autonomous control unit 31 executes bucket closing (step ST13). Specifically, when the autonomous control unit 31 determines that the earth and sand to be excavated is hard earth and sand, by closing the bucket 6, the tip point is shifted from the target trajectory TR1 to the corrected target trajectory TR2. If the bucket 6 is closed when shifting the tip point from the target trajectory TR1 to the corrected target trajectory TR2, the excavation angle θA becomes smaller, and the direction of the tip of the bucket 6 can be made closer to the traveling direction of the tip, making it easier to break up hard earth and sand. In other words, when the autonomous control unit 31 determines that the earth and sand to be excavated is hard earth and sand, by executing bucket closing when shifting the tip point from the target trajectory TR1 to the corrected target trajectory TR2, the excavation (collapse) of hard earth and sand can be promoted.

[0064] Here, referring to FIG. 9, the transition of the state of the bucket 6 when the tip point is shifted from the target trajectory TR1 to the corrected target trajectory TR2 will be described. FIG. 9 is a left side view of the bucket 6 when the tip point is located at point C2 on the target trajectory TR1. Specifically, the upper diagram of FIG. 9 shows the transition of the state of the bucket 6 when the excavation target is hard soil and sand, and the lower diagram of FIG. 9 shows the transition of the state of the bucket 6 when the excavation target is heavy soil and sand.

[0065] When the autonomous control unit 31 determines that the excavation target is hard soil and sand (in the example shown in FIG. 7, when it is determined that the decrease DF2 in the tip movement speed V exceeds the decrease threshold DFt), as shown in the upper diagram of FIG. 9, the bucket 6 is closed by an angle δ to move the tip point to a position on the corrected target trajectory TR2. At this time, the excavation angle θA decreases from the value θA1 to the value θA2.

[0066] On the other hand, when the autonomous control unit 31 determines that the excavation target is heavy soil and sand (in the example shown in FIG. 7, when it is determined that the decrease DF1 in the tip movement speed V is below the decrease threshold DFt), as shown in the lower diagram of FIG. 9, the boom 4 is raised to move the tip point to a position on the corrected target trajectory TR2. At this time, the excavation angle θA remains at the value θA1.

[0067] In this way, even when the autonomous control unit 31 generates the same corrected target trajectory TR2, depending on whether the excavation target soil and sand is hard soil and sand or heavy soil and sand, the movement of the attachment AT when shifting the tip point from the target trajectory TR1 to the corrected target trajectory TR2 can be made different. Therefore, when the autonomous control unit 31 excavates hard soil and sand, it can promote the destruction of the soil and sand while reducing the excavation reaction force. Also, when the autonomous control unit 31 excavates heavy soil and sand, it can continue the excavation while reducing the excavation reaction force while suppressing the lifting of the rear part of the shovel 100. Note that the corrected target trajectory generated when the excavation target soil and sand is hard soil and sand and the corrected target trajectory generated when the excavation target soil and sand is heavy soil and sand may be different from each other.

[0068] It can also be said that the autonomous control unit 31 changes the way of approaching (transitioning) from the target trajectory TR1 to the corrected target trajectory TR2 according to the determination result of the state of the earth and sand. From this perspective, a part of the corrected target trajectory TR2 connecting the point C2 and the point C2T (see FIG. 9) may be generated as a transition trajectory TR2T different from the corrected target trajectory TR2. That is, the autonomous control unit 31 generates a transition trajectory TR2T separately from the corrected target trajectory TR2 according to the determination result of the state of the earth and sand, and closes the bucket 6 or raises the boom 4 in order to move the tip point along the transition trajectory TR2T.

[0069] Thereafter, the autonomous control unit 31 moves the tip point along the corrected target trajectory TR2 while gradually reducing the excavation angle θA at a predetermined reduction rate. Note that the reduction rate of the excavation angle θA when the excavation target is heavy earth and sand is typically set to be smaller than the reduction rate of the excavation angle θA when the excavation target is hard earth and sand. This is to suppress the occurrence of the upward movement of the rear part of the shovel 100 when the excavation operation is performed.

[0070] However, the autonomous control unit 31 may adjust the excavation angle θA according to the internal pressure in the cylinder or the excavation reaction force when moving the tip point along the corrected target trajectory TR2. For example, the autonomous control unit 31 may reduce the excavation angle θA so that the internal pressure in the cylinder or the excavation reaction force decreases to a desired value. Alternatively, in some cases, the autonomous control unit 31 may increase the excavation angle θA so that the internal pressure in the cylinder or the excavation reaction force is maintained at a desired value.

[0071] In addition, when moving the tip point along the corrected target trajectory TR2, the autonomous control unit 31 may further correct the corrected target trajectory TR2 when the internal pressure in the cylinder reaches the second threshold value. That is, another target trajectory different from both the target trajectory TR1 and the corrected target trajectory TR2 may be generated. In this case, the second threshold value may be the same as the first threshold value or different from the first threshold value.

[0072] Further, when the tip point is being moved along the corrected target trajectory TR2, if the excavation angle θA becomes equal to or less than the threshold value and the internal pressure of the cylinder reaches the third threshold value, the autonomous control unit 31 may complete the current excavation operation even before the tip point reaches the excavation end point C4. That is, the autonomous control unit 31 may complete the excavation operation by lifting the bucket 6 into the air while closing the bucket 6 until the opening surface of the bucket 6 becomes horizontal. In this case, the third threshold value may be the same value as the first threshold value or may be a value different from the first threshold value.

[0073] Thereafter, the autonomous control unit 31 turns the upper slewing body 3 to orient the upper slewing body 3 in a desired direction, and discharges (dumps) the earth and sand taken into the bucket 6 at a desired position. That is, the autonomous control unit 31 empties the inside of the bucket 6. In this case, the autonomous control unit 31 may operate (travel) the lower traveling body 1.

[0074] Also, when the autonomous control unit 31 lifts the bucket 6 into the air, if the volume or weight of the earth and sand taken into the bucket 6 is less than a predetermined volume or weight, the autonomous control unit 31 may perform the next excavation operation without discharging the earth and sand taken into the bucket 6. In this case, the autonomous control unit 31 generates a new target trajectory in consideration of the volume or weight of the earth and sand taken into the bucket 6. Note that the autonomous control unit 31 may determine to perform the next excavation operation without discharging the earth and sand taken into the bucket 6 when it estimates that the volume or weight of the earth and sand taken into the bucket 6 will be less than a predetermined volume or weight before lifting the bucket 6 into the air.

[0075] Further, the controller 30 may be configured to display the target trajectory TR1, the corrected target trajectory TR2, the design surface DS, the position of the current tip point, the magnitude of the excavation reaction force, the determination result of the nature of the earth and sand (whether it is hard earth and sand or heavy earth and sand), etc. on a display device installed outside the excavator 100. This is to enable the administrator of the excavator 100 or the like to visually recognize it.

[0076] In addition, in the above-described embodiment, the controller 30 makes various determinations based on the internal pressure of the cylinder. However, instead of the internal pressure of the cylinder, various determinations may be made based on the cylinder thrust, the excavation torque, the tip movement speed, or the excavation reaction force, etc.

[0077] In addition, in the above-described embodiment, the controller 30 is configured to correct the target trajectory when a predetermined target trajectory correction condition is satisfied while the excavator 100 is operating autonomously. However, the controller 30 may be configured to correct the target trajectory when a predetermined target trajectory correction condition is satisfied while the excavator 100 is being manually operated. Specifically, the controller 30 may be configured to correct the target trajectory when a predetermined target trajectory correction condition is satisfied during the execution of the machine guidance function or the machine control function.

[0078] The machine guidance function is a function that supports the operation of the excavator 100 by the operator by allowing the operator to recognize the distance (deviation) between the target trajectory and the tip point using sound or an image, etc. The machine control function is a function that supports the operation of the excavator 100 by the operator by assisting the movement of the attachment AT so that the tip point moves along the target trajectory in response to the manual operation by the operator.

[0079] In this case, the controller 30 generates a corrected target trajectory TR2 when a predetermined target trajectory correction condition is satisfied during the execution of the excavation operation using the machine guidance function or the machine control function. Then, before the movement of the tip point along the corrected target trajectory TR2 is started, the controller 30 determines whether the earth and sand to be excavated is hard or heavy. Then, when the controller 30 determines that the earth and sand to be excavated is hard, the bucket 6 is automatically closed by a predetermined angle δ, and when the controller 30 determines that the earth and sand to be excavated is heavy, the boom 4 is raised by a predetermined angle.

[0080] With this configuration, the controller 30 can avoid the excavation operation from being slowed down or stopped due to an increase in the excavation reaction force. Further, when the controller 30 determines that the earth and sand is hard, it closes the bucket 6 by an angle δ so that the excavation reaction force becomes smaller. As a result, the claws of the bucket 6 will pierce into the hard earth and sand, and the hard earth and sand can be broken by the claws of the bucket 6. Further, when the controller 30 determines that the earth and sand is heavy, instead of closing the bucket 6 to reduce the excavation reaction force, it raises the boom 4, thereby avoiding generating a downward excavation reaction force by closing the bucket 6. Therefore, the controller 30 can suppress the attachment AT from being pulled forward and the rear part of the excavator 100 from rising up.

[0081] Further, the controller 30 may be configured to display the target trajectory TR1, the corrected target trajectory TR2, the design surface DS, the position of the current claw tip, the magnitude of the excavation reaction force, the determination result of the nature of the earth and sand (whether it is hard earth and sand or heavy earth and sand), etc. on the image display unit 41 of the display device 40. This is to enable the operator of the excavator 100 to visually recognize them.

[0082] Next, referring to FIG. 10, another example of the work site when the target trajectory correction process is performed will be described. FIG. 10 is a diagram showing another example of the work site when the target trajectory correction process is performed, and includes the excavator 100 having the swing axis PA and the cross-section of the ground to be excavated. Specifically, the upper diagram of FIG. 10 shows the excavator 100 excavating an upward-sloping slope, and the lower diagram of FIG. 10 shows the excavator 100 excavating a downward-sloping slope.

[0083] In the example shown in FIG. 10, the reference plane RP is not parallel to the bottom surface (ground contact surface GP) of the lower traveling body 1, which is different from the example shown in FIG. 6 where the reference plane RP is parallel to the bottom surface (ground contact surface GP) of the lower traveling body 1. Specifically, in the example shown in the upper diagram of FIG. 10, the reference plane RP is an upward-sloping slope, and the angle between the reference plane RP and the ground contact surface GP is angle α1. Also, in the example shown in the lower diagram of FIG. 10, the reference plane RP is a downward-sloping slope, and the angle between the reference plane RP and the ground contact surface GP is angle α2.

[0084] In this way, the controller 30 can realize excavation using the target trajectory not only when excavating a horizontal ground as shown in FIG. 6, but also when excavating a non-horizontal ground such as an upward or downward slope, and can realize correction of the target trajectory as necessary.

[0085] Further, in the above-described embodiment, the excavator 100 is configured to operate autonomously or to be operated by an operator sitting in the driver's seat in the cab 10. However, the excavator 100 may be a remotely operated excavator. FIG. 11 is a schematic diagram showing an example of a construction system 500 including the excavator 100 as a remotely operated excavator. As shown in FIG. 11, the construction system 500 includes the excavator 100, the management device 200, and the support device 300. The construction system 500 is configured to support construction by one or a plurality of excavators 100.

[0086] The information acquired by the excavator 100 may be shared with the administrator and the operators of other excavators, etc. through the construction system 500. Each of the excavator 100, the management device 200, and the support device 300 constituting the construction system 500 may be one or a plurality. In the example shown in FIG. 11, the construction system 500 includes one excavator 100, one management device 200, and one support device 300.

[0087] The management device 200 is typically a fixed terminal device, for example, a server computer (so-called cloud server) installed in a management center outside the construction site or the like. Further, the management device 200 may be, for example, an edge server set in the construction site. Further, the management device 200 may be a portable terminal device (for example, a laptop computer terminal, a tablet terminal, or a mobile terminal such as a smartphone).

[0088] The support device 300 is typically a portable terminal device, such as a laptop computer terminal, a tablet terminal, or a smartphone carried by an operator at a construction site or the like. The support device 300 may be a portable terminal carried by the operator of the excavator 100. The support device 300 may also be a fixed terminal device.

[0089] At least one of the management device 200 and the support device 300 may include a monitor and an operating device for remote operation. In this case, the operator using the management device 200 or the support device 300 may operate the excavator 100 while using the operating device for remote operation. The operating device for remote operation is communicably connected to the controller 30 mounted on the excavator 100 through a wireless communication network such as a short-range wireless communication network, a mobile phone communication network, or a satellite communication network. The operating device for remote operation may be configured to be able to directly communicate with the controller 30 mounted on the excavator 100.

[0090] In addition, various information images (for example, image information representing the state around the excavator 100 and various setting screens) displayed on the display device 40 installed in the cab 10 may be displayed on a display device connected to at least one of the management device 200 and the support device 300. The image information representing the state around the excavator 100 may be generated based on the captured image of the space recognition device 70 (for example, a camera or LIDAR) attached to the excavator 100. Thereby, the administrator using the management device 200, or the operator using the support device 300, etc. can perform remote operation of the excavator 100 or perform various settings related to the excavator 100 while checking the state around the excavator 100.

[0091] For example, in the construction system 500, the controller 30 of the excavator 100 may transmit various information to at least one of the management device 200 and the support device 300. At this time, the controller 30 may transmit the image captured by the space recognition device to at least one of the management device 200 and the support device 300. Further, the controller 30 may transmit information regarding at least one of the data related to the design surface DS, the data related to the position of the excavator 100, the data related to the operation content of the excavator 100, the data related to the posture of the excavator 100, and the data related to the posture of the attachment AT to at least one of the management device 200 and the support device 300. Thereby, the administrator using the management device 200 or the operator using the support device 300 can obtain information regarding the excavator 100.

[0092] In this way, the construction system 500 enables the information regarding the excavator 100 to be shared with the administrator and the operators of other excavators, etc.

[0093] Note that, as shown in FIG. 11, the communication device 72 mounted on the excavator 100 may be configured to transmit and receive information to and from the communication device T2 installed in the remote operation room RC via wireless communication. In the example shown in FIG. 11, the communication device 72 mounted on the excavator 100 and the communication device T2 are configured to transmit and receive information via a fifth-generation mobile communication line (5G line), an LTE line, or a satellite line, etc.

[0094] In the remote operation room RC, a remote controller 30R, a sound output device AD, an indoor imaging device CA, a display device RD, a communication device T2, etc. are installed. Also, in the remote operation room RC, a driver's seat RS on which the operator OP who remotely operates the excavator 100 sits is installed.

[0095] The remote controller 30R is an arithmetic unit (electronic circuit) that executes various operations. In the example shown in FIG. 11, the remote controller 30R is composed of a computer including a CPU, a RAM, a ROM, etc., similar to the controller 30. And various functions of the remote controller 30R are realized, for example, by the CPU executing a program stored in the ROM.

[0096] The sound output device AD is configured to output sound. In the example shown in FIG. 11, the sound output device AD is a speaker and is configured to reproduce the sound collected by a sound collecting device (not shown) attached to the excavator 100.

[0097] The indoor imaging device CA is configured to image the inside of the remote operation room RC. In the example shown in FIG. 11, the indoor imaging device CA is a camera installed inside the remote operation room RC and is configured to image the operator OP sitting on the driver's seat RS.

[0098] The communication device T2 is configured to control wireless communication with the communication device 72 attached to the excavator 100.

[0099] In the example shown in FIG. 11, the driver's seat RS has the same structure as the driver's seat installed in the cabin 10 of the excavator 100. Specifically, a left console is arranged on the left side of the driver's seat RS, and a right console is arranged on the right side of the driver's seat RS. And a left operation lever is arranged at the front of the left console, and a right operation lever is arranged at the front of the right console. Also, a travel lever and travel pedals are arranged in front of the driver's seat RS. Each of the left operation lever, the right operation lever, the travel lever, and the travel pedals constitutes the operating device 26T.

[0100] The operating device 26T is provided with an operation sensor 29T for detecting the operation content of the operating device 26T. The operation sensor 29T is, for example, an inclination sensor for detecting the inclination angle of an operation lever, or an angle sensor for detecting the swing angle around the swing axis of the operation lever. The operation sensor 29T may be composed of other sensors such as a pressure sensor, a current sensor, a voltage sensor, or a distance sensor. The operation sensor 29T outputs information regarding the detected operation content of the operating device 26T to the remote controller 30R. The remote controller 30R generates an operation signal based on the received information and transmits the generated operation signal toward the excavator 100. The operation sensor 29T may be configured to generate an operation signal. In this case, the operation sensor 29T may output the operation signal to the communication device T2 without passing through the remote controller 30R.

[0101] The display device RD is configured to display information regarding the situation around the excavator 100. In the example shown in FIG. 11, the display device RD is a multi-display composed of nine monitors arranged in three rows and three columns vertically, and is configured to be able to display the states of the spaces in front of, to the left of, and to the right of the excavator 100. Each monitor is a liquid crystal monitor, an organic EL monitor, or the like. However, the display device RD may be composed of one or a plurality of curved monitors, or may be composed of a projector.

[0102] The display device RD may be a display device that the operator OP can wear. For example, the display device RD is a head-mounted display and may be configured to be able to transmit and receive information to and from the remote controller 30R by wireless communication. The head-mounted display may be wired-connected to the remote controller. The head-mounted display may be a transmissive head-mounted display or a non-transmissive head-mounted display. The head-mounted display may be a single-eye type head-mounted display or a binocular type head-mounted display.

[0103] The display device RD is configured to display an image that enables the operator OP in the remote operation room RC to visually recognize the surroundings of the excavator 100. That is, the display device RD displays an image so that the operator can check the situation around the excavator 100 as if he / she were inside the cab 10 of the excavator 100, even though the operator is in the remote operation room RC.

[0104] As described above, as shown in FIG. 1, the excavator 100 according to the embodiment of the present disclosure includes a lower traveling body 1, an upper swing body 3 rotatably mounted on the lower traveling body 1, an attachment AT attached to the upper swing body 3, a state detection device DT for detecting the state of the attachment AT, an actuator AC for operating the attachment AT, and a controller 30 as a control device for controlling the movement of the actuator AC. The actuator AC may be a hydraulic actuator or an electric actuator. When a physical quantity representing the state of the attachment AT derived based on the output of the state detection device DT reaches a predetermined threshold value, the controller 30 is configured to control the movement of the actuator AC such that the movement of the actuator AC is different when the excavation target is hard and when the excavation target is heavy. The physical quantity representing the state of the attachment AT is, for example, the internal pressure of hydraulic cylinders such as the boom cylinder 7, the arm cylinder 8, and the bucket cylinder 9, the cylinder thrust, the excavation torque, the excavation reaction force, or the moving speed of the tip of the bucket 6. And "when the physical quantity representing the state of the attachment AT reaches a predetermined threshold value" is, for example, when the excavation reaction force reaches the threshold value and the movement of the attachment AT becomes slow or stops. The excavation target is, for example, earth and sand, industrial waste, or wood. Both "when the excavation target is hard" and "when the excavation target is heavy" are examples of the state of the excavation target when the physical quantity representing the state of the attachment AT reaches a predetermined threshold value. And "when the excavation target is heavy" is typically when the excavation target contains a large amount of moisture. In this case, "when the excavation target is hard" may be a state other than "when the excavation target is heavy" among the states of the excavation target when the physical quantity representing the state of the attachment AT reaches a predetermined threshold value. That is, when the physical quantity representing the state of the attachment AT reaches a predetermined threshold value, the controller 30 may determine that "the excavation target is hard" when it cannot be determined that "the excavation target is heavy". In this way, the controller 30 may alternatively determine between "when the excavation target is hard" and "when the excavation target is heavy".

[0105] With this configuration, the excavator 100 can achieve more efficient excavation. For example, when the tip of the attachment AT hits a hard or heavy excavation target and the excavation reaction force increases, the controller 30 controls the movement of the actuator AC so that the excavation reaction force decreases. This allows the excavation operation to continue without reducing the excavation amount and without slowing down or stopping the movement of the attachment AT. In addition, the controller 30 makes the operation of the actuator AC "when the excavation target is hard" different from the operation of the actuator AC "when the excavation target is heavy". Therefore, compared with the case where the actuator AC is operated in exactly the same way both "when the excavation target is hard" and "when the excavation target is heavy", the appropriate operation of the actuator AC for "when the excavation target is hard" can be realized "when the excavation target is hard", and the appropriate operation of the actuator AC for "when the excavation target is heavy" can be realized "when the excavation target is heavy". For example, when the excavation target is hard, if the tip of the bucket 6 faces the excavator 100, the tip of the bucket 6 contacts the excavation target in its advancing direction, so the excavation target is easily broken. On the other hand, when the excavation target is heavy, if the bucket 6 is closed so that the tip of the bucket 6 faces the excavator 100, the direction of the excavation reaction force becomes downward and the attachment AT is pulled downward, which may cause a problem that the rear part of the excavator 100 floats up. On the contrary, when the excavation target is heavy, if excavation is performed by moving at least one of the boom 4 and the arm 5 without closing the bucket 6, the downward direction of the excavation reaction force can be avoided, so that the floating of the rear part of the excavator 100 during excavation is suppressed. On the other hand, if the tip of the bucket 6 remains directed vertically downward when the excavation target is hard, there may be a problem that the front surface of the claw of the bucket 6 hits the excavation target in the advancing direction and it is difficult to break the excavation target. The configuration of the present disclosure can solve such problems by making the operation of the actuator AC "when the excavation target is hard" different from the operation of the actuator AC "when the excavation target is heavy".

[0106] Also, the attachment AT desirably includes the boom 4, the arm 5, and the bucket 6. In this case, the controller 30 may be configured to close the bucket 6 when the excavation target is hard and raise the boom 4 when the excavation target is heavy.

[0107] With this configuration, the excavator 100 can achieve more efficient excavation. The controller 30 closes the bucket 6 "when the excavation target is hard", so that the direction of the tip of the bucket 6 can be brought closer to the traveling direction of the tip, making it easier to break the excavation target in that traveling direction. Note that if the controller 30 can bring the tip of the bucket 6 closer to its traveling direction, instead of closing the bucket 6, the arm 5 may be closed, or the bucket 6 may be closed while closing the arm 5. Also, the controller 30 raises the boom 4 "when the excavation target is heavy" so that excavation can be continued without generating a downward digging reaction force, and it can suppress the rear part of the excavator 100 from lifting during excavation.

[0108] Also, the controller 30 desirably determines whether the excavation target is hard or heavy based on the transition of the physical quantity in a predetermined monitoring period including a period prior to the time when the physical quantity representing the state of the attachment AT derived based on the output of the state detection device DT reaches a predetermined threshold value. In the example shown in FIG. 8, the controller 30 determines whether the earth and sand as the excavation target is hard or heavy based on the decrement DF of the tip movement speed V as the physical quantity (second physical quantity) in a predetermined monitoring period DR including a period prior to the time t3 when the tip movement speed V as the physical quantity (first physical quantity) representing the state of the attachment AT reaches a predetermined threshold value Vt. Note that in the example shown in FIG. 8, the first physical quantity and the second physical quantity are the same physical quantity (tip movement speed V), but they may be different physical quantities.

[0109] With this configuration, the controller 30 can easily and quickly determine whether the excavation target is hard or heavy based on the output of the state detection device DT. Therefore, the controller 30 can realize the movement of the attachment AT suitable for "when the excavation target is heavy" without delay, and can also realize the movement of the attachment AT suitable for "when the excavation target is hard" without delay.

[0110] Further, the state detection device DT may detect or calculate the excavation reaction force as a physical quantity representing the state of the attachment AT. In this case, the controller 30 may determine whether the excavation target is hard or heavy when the excavation reaction force exceeds the threshold value.

[0111] With this configuration, the controller 30 can more accurately determine whether the excavation target is hard or heavy. Therefore, the controller 30 can more accurately distinguish between the movement of the attachment AT suitable for "when the excavation target is heavy" and the movement of the attachment AT suitable for "when the excavation target is hard", and can further improve the excavation efficiency in each of "when the excavation target is heavy" and "when the excavation target is hard".

[0112] Further, as shown in FIG. 8, the controller 30 may determine that the excavation target is hard when the decrease DF of the tip movement speed V during the monitoring period DR exceeds the decrease threshold DFt, and may determine that the excavation target is heavy when the decrease DF of the tip movement speed V during the monitoring period DR is less than or equal to the decrease threshold DFt. Alternatively, the controller 30 may determine that the excavation target is hard when the increase in the excavation reaction force during the monitoring period DR exceeds the increase threshold, and may determine that the excavation target is heavy when the increase in the excavation reaction force during the monitoring period DR is less than or equal to the increase threshold.

[0113] With this configuration, the controller 30 can more accurately determine whether the excavation target is hard or heavy.

[0114] The preferred embodiments of the present disclosure have been described above. However, the present invention is not limited to the above-described embodiments, nor is it limited to the embodiments described below. Various modifications, substitutions, etc. can be applied to the above-described or below-described embodiments without departing from the scope of the present invention. Further, each of the features described with reference to the above-described or below-described embodiments may be appropriately combined as long as there is no technical contradiction.

Explanation of Signs

[0115] 1 ··· Lower traveling body 1A ··· Hydraulic motor for left traveling 1B ··· Hydraulic motor for right traveling 2 ··· Slewing mechanism 2A ··· Hydraulic motor for slewing 3 ··· Upper slewing body 4 ··· Boom 5 ··· Arm 6 ··· Bucket 7 ··· Boom cylinder 8 ··· Arm cylinder 9 ··· Bucket cylinder 10 ··· Cabin 11 ··· Engine 11a ··· Alternator 11b ··· Starter 11c ··· Water temperature sensor 14 ··· Main pump 14a ··· Regulator 14b ··· Discharge pressure sensor 14c ··· Oil temperature sensor 15 ··· Pilot pump 15a, 15b ··· Pilot pressure sensor 16 ··· Hydraulic oil line 17 ··· Control valve unit 25, 25a ··· Pilot line 26, 26T ··· Operating device 29T ··· Operation sensor 30 ··· Controller 30a ··· Temporary storage unit 30R ··· Remote controller 31 ··· Autonomous control unit 32 ··· Judgment unit 40 ··· Display device 41 ··· Image display unit 42 ··· Input unit 45 ··· Sound output device 70 ··· Space recognition device 70B ··· Rear camera 70F ··· Front camera 70L ··· Left camera 70R ··· Right camera 71 ··· Positioning device 72 ··· Communication device 74 ··· Engine control device 90 ··· Battery 100 ··· Excavator 200 ··· Management device 300 ··· Support device 500 ··· Construction system AC ··· Actuator AD ··· Sound output device AT ··· Attachment C1 ··· Excavation start point C2 ··· Point C2T ··· Point C3 ··· Excavation end point C4 ··· Excavation end point CA ··· Indoor imaging device D1 ··· Distance DP1, DP2 ··· Depth DS ··· Design surface DT ··· State detection device E1 ··· Control valve GP ··· Ground contact surface M1 ··· Attitude detection device M1a ··· Boom angle sensor M1b ··· Arm angle sensor M1c ··· Bucket angle sensor OP ··· Operator PA ··· Slewing axis RC ··· Remote operation room RD ··· Display device RP ··· Reference surface RS ··· Driver's seat S1, S11~S16 ··· Cylinder pressure sensor T2 ··· Communication device TR1 ··· Target trajectory TR2 ··· Corrected target trajectory TR2T ··· Transition trajectory Z1, Z2 ··· Region θA ··· Excavation angle

Claims

1. A lower traveling body, an upper slewing body rotatably mounted on the lower traveling body, an attachment attached to the upper slewing body, a state detection device for detecting the state of the attachment, an actuator for operating the attachment, and a control device for controlling the movement of the actuator, wherein the control device controls the movement of the actuator such that the movement of the actuator is different when the excavation target is hard and when the excavation target is heavy when a physical quantity representing the state of the attachment derived based on the output of the state detection device reaches a predetermined threshold value. A hydraulic excavator characterized by the above.

2. The attachment includes a boom, an arm, and a bucket, and the control device closes the bucket when the excavation target is hard and raises the boom when the excavation target is heavy. The hydraulic excavator according to Claim 1.

3. The control device determines whether the excavation target is hard or heavy based on the transition of the state of the attachment in a predetermined monitoring period including a period preceding the time when a physical quantity representing the state of the attachment derived based on the output of the state detection device reaches a predetermined threshold value. The hydraulic excavator according to Claim 1.

4. The state detection device detects, as a physical quantity representing the state of the attachment, the moving speed of the tip of the bucket or the excavation reaction force, and the control device determines whether the excavation target is hard or heavy when the moving speed is lower than a first threshold value or when the excavation reaction force exceeds a second threshold value. The hydraulic excavator according to Claim 3.

5. The control device determines that the excavation target is hard when the decrease in the moving speed in the monitoring period exceeds a decrease threshold value or when the increase in the excavation reaction force in the monitoring period exceeds an increase threshold value, and determines that the excavation target is heavy when the decrease in the moving speed in the monitoring period is equal to or less than the decrease threshold value or when the increase in the excavation reaction force in the monitoring period is equal to or less than the increase threshold value. The hydraulic excavator according to Claim 4.

Images