Work machine system, and method for controlling work machine

Abstract

In the present invention, a control device recognizes the states of a swing body and a work machine. The control device executes first automatic control for automatically moving a work tool to a target position in conjunction with the swing body and the work machine in accordance with an automatic control command. During the first automatic control, the control device interrupts the first automatic control in cases where it is determined that the state of the swing body or the work machine is an immobile state.

Description

Work machine system and work machine control method

[0001] This application claims priority to Japanese Patent Application No. 2024-050760, filed on March 27, 2024, the contents of which are incorporated herein by reference.

[0002] Patent Document 1 discloses a technology for automatically operating a hydraulic excavator.

[0003] Japanese Patent Application Laid-Open No. 2019-065661

[0004] If the load on the actuator becomes excessive, the actuator will stall. When the actuator stalls, energy is consumed even though the actuator is stopped, resulting in a decrease in efficiency.

[0005] In the automatic driving described in Patent Document 1, automatic operation signals are generated based on the difference between the attitude of the work machine and the target attitude. Therefore, if the load on the work machine becomes excessive and the actuator stalls, the attitude of the work machine does not reach the target attitude, so the automatic operation signals continue to be output, wasting energy. An object of the present disclosure is to provide a work machine system and a work machine control method that can prevent a decrease in efficiency due to actuator stalling during automatic control.

[0006] According to one aspect of the present disclosure, a work machine system includes a rotating body that can rotate around a rotation center, a work machine that includes a work implement and is operable relative to the rotating body, and a control device that controls the rotating body and the work implement, wherein the control device recognizes the state of the rotating body and the work implement, and executes a first automatic control in accordance with an automatic control instruction to link the rotating body and the work implement to automatically move the work implement to a target position, and if, during the first automatic control, it is determined that the state of the rotating body or the work implement is immobile, the first automatic control is interrupted.

[0007] According to the above aspect, the work machine system can prevent a decrease in fuel efficiency due to stalling of the actuator during automatic control.

[0008] FIG. 1 is a schematic diagram showing the configuration of a work machine according to a first embodiment. FIG. 2 is a block diagram showing the hydraulic circuit of an actuator connected to a control valve according to the first embodiment. FIG. 3 is a diagram showing the internal configuration of a driver's cab according to the first embodiment. FIG. 4 is a schematic block diagram showing the configuration of a control device according to the first embodiment. FIG. 5 is a flowchart (part 1) showing swing control by the control device according to the first embodiment. FIG. 6 is a flowchart (part 2) showing swing control by the control device according to the first embodiment.

[0009] First Embodiment Hereinafter, an embodiment will be described in detail with reference to the drawings.

[0010] <Configuration of Work Machine 100> Figure 1 is a schematic diagram showing the configuration of a work machine 100 according to a first embodiment. The work machine 100 operates at a construction site, excavating earth and sand and transporting the excavated material. The work machine 100 may load the excavated material onto a transport vehicle or the like, or may dump the excavated material at a location that does not interfere with the excavation work. For example, in trench forming work, the work machine 100 excavates a trench in the ground and dumps the excavated material, earth and sand, next to the formed trench.

[0011] Examples of the work machine 100 include a face shovel, a backhoe shovel, and a rope shovel. The work machine 100 may be electrically driven or hydraulically driven. The work machine 100 according to the first embodiment is a backhoe shovel. The work machine 100 includes a traveling body 110, a rotating body 120, a work implement 130, and a cab 140.

[0012] The running body 110 supports the work machine 100 so that it can travel. The running body 110 is equipped with two caterpillar tracks 111, one on the left and one on the right, and two travel motors A10 for driving each caterpillar track 111. The travel motors A10 are an example of actuators A. The rotating body 120 is supported on the running body 110 so that it can rotate about a rotation center. The work implement 130 is hydraulically driven. The work implement 130 is supported on the front part of the rotating body 120 so that it can be driven in the vertical direction. The cab 140 is a space where an operator boards and operates the work machine 100. The cab 140 is provided on the left front part of the rotating body 120. Here, the part of the rotating body 120 to which the work implement 130 is attached is referred to as the front part. Furthermore, with respect to the rotating body 120, the opposite part, left part, and right part are referred to as the rear, left part, and right part, respectively, based on the front part.

[0013] <Configuration of the Swing Structure 120> The swing structure 120 includes an engine 121, a hydraulic pump 122, a control valve 123, and a swing motor A20. The engine 121 is a prime mover that drives the hydraulic pump 122. The engine 121 is an example of a power source. The hydraulic pump 122 is a variable displacement pump driven by the engine 121. The hydraulic pump 122 supplies hydraulic oil to each actuator (the boom cylinder A31, the arm cylinder A32, the bucket cylinder A33, the travel motor A10, and the swing motor A20) via a control valve 123. The control valve 123 controls the flow rate of hydraulic oil supplied from the hydraulic pump 122. The swing motor A20 is driven by the hydraulic oil supplied from the hydraulic pump 122 via the control valve 123 to swing the swing structure 120. The swing motor A20 is an example of an actuator A. Note that the swing motor A20 according to other embodiments may be an electric motor instead of a hydraulic motor.

[0014] <Configuration of Work Machine 130> The work machine 130 includes a boom 131, an arm 132, a bucket 133 as a work implement, a boom cylinder A31, an arm cylinder A32, and a bucket cylinder A33. Other examples of the work implement include tip attachments such as a clam bucket, a tilt bucket, a tilt rotate bucket, a grapple, and a lifting magnet.

[0015] The base end of the boom 131 is rotatably attached to the revolving unit 120 via a boom pin, which is a joint. Note that in the work machine 100 shown in FIG. 1 , the boom 131 is provided in the center portion of the front of the revolving unit 120, but this is not limiting, and the boom 131 may be attached offset in the left-right direction. In this case, the center of rotation of the revolving unit 120 is not located on the operating plane of the work implement 130. The arm 132 connects the boom 131 and the bucket 133. The base end of the arm 132 is rotatably attached to the tip of the boom 131 via an arm pin, which is a joint. The bucket 133 is rotatably attached to the tip of the arm 132 via a pin, which is a joint. The bucket 133 functions as a container for storing excavated soil and sand. The bucket 133 is attached so that its opening faces the revolving unit 120 (rearward). That is, work machine 100, which is a backhoe excavator, performs excavation by pulling bucket 133 toward the front side of rotating body 120. That is, work machine 130 has a boom 131 and an arm 132, which are multiple link members connected to each other by joints. Of these, boom 131 is the link member located furthest from the base end of the multiple link members.

[0016] The boom cylinder A31 is a hydraulic cylinder for operating the boom 131. The base end of the boom cylinder A31 is attached to the rotating bed 120. The tip end of the boom cylinder A31 is attached to the boom 131. The arm cylinder A32 is a hydraulic cylinder for driving the arm 132. The base end of the arm cylinder A32 is attached to the boom 131. The tip end of the arm cylinder A32 is attached to the arm 132. The bucket cylinder A33 is a hydraulic cylinder for driving the bucket 133. The base end of the bucket cylinder A33 is attached to the arm 132. The tip end of the bucket cylinder A33 is attached to a link mechanism that rotates the bucket 133. Note that while each cylinder in the first embodiment is a hydraulic cylinder, in other embodiments, it may be another power cylinder such as an electric cylinder. The hydraulic cylinder has a cylindrical cylinder body with a bottom, a piston that divides the internal space of the cylinder body in two, and a rod that is connected to the piston and protrudes from one end of the cylinder body. Hereinafter, the side of the cylinder body from which the rod protrudes will be referred to as the head side, and the side having the bottom will be referred to as the bottom side. Furthermore, the actuators for driving the work machine 130 are not limited to power cylinders, and may be, for example, electric motors provided at each joint. The electric motors may be driven by battery power. The boom cylinder A31, arm cylinder A32, and bucket cylinder A33 are examples of actuators A.

[0017] <<Relief Valve>> Figure 2 is a block diagram showing the hydraulic circuit of actuator A connected to the control valve according to the first embodiment. Actuator A is driven in a first direction and a second direction. The power cylinder can extend and retract. The motor can rotate clockwise and counterclockwise. Thus, each actuator A has a first port and a second port, and is driven in the first direction by hydraulic oil flowing through the first port, and in the second direction by hydraulic oil flowing through the second port.

[0018] The hydraulic circuit connecting the control valve 123 and the actuator A (travel motor A10, swing motor A20, boom cylinder A31, arm cylinder A32, and bucket cylinder A33) includes a first oil passage R1 connecting the control valve 123 and a first port of the actuator A and a second oil passage R2 connecting the control valve 123 and a second port of the actuator A. A first pressure sensor P1 is provided in the first oil passage R1. A first bypass oil passage B1 bypassing the oil tank is provided in the first oil passage R1. A first relief valve V1 is provided in the first bypass oil passage B1. The first relief valve V1 opens when the internal pressure of the first oil passage R1 exceeds a predetermined relief pressure, thereby bypassing the hydraulic oil to the oil tank. A second pressure sensor P2 is provided in the second oil passage R2. A second bypass oil passage B2 bypassing the oil tank is provided in the second oil passage R2. A second relief valve V2 is provided in the second bypass oil passage B2. The second relief valve V2 opens when the internal pressure of the second oil passage R2 exceeds a predetermined relief pressure, and bypasses the hydraulic oil to the oil tank.

[0019] As a result, the internal pressures of the first oil passage R1 and the second oil passage R2 are maintained at or below the relief pressure. If hydraulic oil continues to be supplied to the head side of the bucket cylinder A33 even though the piston of the bucket cylinder A33 has reached its stroke end on the bottom side, the internal pressure of the first oil passage R1 reaches the relief pressure, and hydraulic oil flows from the first relief valve V1 to the oil tank. If hydraulic oil continues to be supplied to the bottom side of the bucket cylinder A33 even though the piston of the bucket cylinder A33 has reached its stroke end on the head side, the internal pressure of the second oil passage R2 reaches the relief pressure, and hydraulic oil flows from the second relief valve V2 to the oil tank. Furthermore, when the force applied to the bucket 133 during operation of the work implement 130 reaches the upper limit of the bucket cylinder A33, the internal pressure of the passage also reaches the relief pressure. When relief occurs in the bucket cylinder A33, fuel is consumed even though the cylinder is stopped, resulting in reduced fuel efficiency.

[0020] The relief valve is not limited to being provided in the bucket cylinder A33, but may also be provided in the boom cylinder A31, the arm cylinder A32, the travel motor A10, and the swing motor A20. The relief valve may be provided between the hydraulic pump 122 and the control valve 123. In this case, the pressure in the oil passage connecting the hydraulic pump 122 and the control valve 123 is kept at or below the relief pressure. In this case as well, the internal pressure of the first oil passage R1 and the second oil passage R2 can be kept at or below the relief pressure.

[0021] 3 is a diagram showing the internal configuration of the driver's cab 140 according to the first embodiment. A driver's seat 141, an operation terminal 142, and an operation device 143 are provided in the driver's cab 140. The operation terminal 142 is provided near the driver's seat 141, and is a user interface with the control device 160, which will be described later.

[0022] The operation device 143 is a device for driving the traveling body 110, the revolving body 120, and the work machine 130 by manual operation by an operator. The operation device 143 is provided with a start switch 143SW and a teaching switch 143TC in addition to various levers.

[0023] The start switch 143SW is provided, for example, on the handle portion of the left operation lever. The start switch 143SW may be located near the operator seated in the driver's seat 141. When the start switch 143SW is operated, an automatic control instruction signal is output to the control device 160. When the control device 160 receives the input of the automatic control instruction signal, it starts automatic control. The teaching switch 143TC is provided, for example, on the handle portion of the right operation lever. The teaching switch 143TC is a switch for teaching the control point of the bucket 133. When the teaching switch 143TC is operated, a teaching signal is output to the control device 160. When the control device 160 receives the input of the teaching signal, it identifies the point where the bucket 133 is located at that time as the control point.

[0024] Automatic control refers to autonomous control by the work machine 100 of the drive of the work implement 130 and the rotating unit 120 to achieve a predetermined operation. In the first embodiment, the automatic control is control in which the work machine 100 autonomously performs a first swing, which is a series of operations in which the work implement 130 is raised and rotated from a state after excavation of the work target toward the dump target, and a second swing, which is a series of operations in which the work implement 130 is lowered and rotated from a state after soil removal toward the work target. Note that automatic control according to other embodiments may perform only the first swing or only the second swing. In the first embodiment, the target orientations of the rotating unit 120 during the first swing and the second swing are each designated in advance by teaching. Note that the work target is typically located lower than the dump target. For example, in the case of trench excavation, the excavation work is performed below the ground surface, and the soil removal is performed above the ground surface.

[0025] <Configuration of Measurement System> As shown in FIG. 1 , the work machine 100 is equipped with a position and orientation calculator 151 , an inclination measuring device 152 , a boom stroke sensor 153 , an arm stroke sensor 154 , and a bucket stroke sensor 155 .

[0026] The position and orientation calculator 151 calculates the position of the revolving unit 120 and the orientation in which the revolving unit 120 faces. The position and orientation calculator 151 includes two receivers that receive positioning signals from satellites that make up the GNSS. The two receivers are installed at different positions on the revolving unit 120. The position and orientation calculator 151 detects the position of a representative point of the revolving unit 120 in the site coordinate system (the origin of the excavator coordinate system) based on the positioning signals received by the receivers. The position and orientation calculator 151 uses the positioning signals received by the two receivers to calculate the orientation in which the revolving unit 120 faces as the relationship between the installation position of one receiver and the installation position of the other receiver. The orientation in which the revolving unit 120 faces is the direction perpendicular to the front of the revolving unit 120. The direction in which the rotating body 120 faces is equal to the horizontal component of the extension direction of a straight line extending from the boom 131 to the bucket 133 of the work implement 130 .

[0027] The inclinometer 152 measures the acceleration and angular velocity of the rotating unit 120, and detects the attitude (e.g., roll angle, pitch angle) and rotation speed of the rotating unit 120 based on the measurement results. The inclinometer 152 is installed, for example, on the underside of the rotating unit 120. The inclinometer 152 can be, for example, an inertial measurement unit (IMU).

[0028] The boom stroke sensor 153 is attached to the boom cylinder A31 and detects the stroke length of the boom cylinder A31. The stroke length of the boom cylinder A31 can be converted into the relative angle of the boom 131 with respect to the revolving unit 120. The arm stroke sensor 154 is attached to the arm cylinder A32 and detects the stroke length of the arm cylinder A32. The stroke length of the arm cylinder A32 can be converted into the relative angle of the arm 132 with respect to the boom 131. The bucket stroke sensor 155 is attached to the bucket cylinder A33 and detects the stroke length of the bucket cylinder A33. The stroke length of the bucket cylinder A33 can be converted into the relative angle of the bucket 133 with respect to the arm 132. The work machine 100 according to the first embodiment uses the boom stroke sensor 153, the arm stroke sensor 154, and the bucket stroke sensor 155 to identify the angles of the link components of the work implement 130, but this is not limited to this in other embodiments. For example, in other embodiments, instead of a stroke sensor, a potentiometer may be provided to detect the relative rotation angle of the link parts, or an inclination sensor such as an IMU to detect the ground angle of each link part may be provided, or an external sensor such as a Lidar or stereo camera to detect the external shape of the work machine may be provided, and the posture may be estimated from the external shape.

[0029] <Configuration of the Control Device 160> FIG. 4 is a schematic block diagram showing the configuration of the control device 160 according to the first embodiment. The work machine 100 is equipped with the control device 160. The control device 160 may be implemented in the operation terminal 142, or may be provided separately from the operation terminal 142 and receive input and output from the operation terminal 142. The control device 160 receives operation signals from the operation device 143. The control device 160 drives the work implement 130, the revolving body 120, and the traveling body 110 by outputting the received operation signals or operation signals generated for automatic control to the control valve 123. Hereinafter, operation signals received from the operation device 143 will also be referred to as manual operation signals, and operation signals generated for automatic control will also be referred to as automatic operation signals. Note that automatic operation signals consist of operation signals that drive the revolving body 120 and the work implement 130, but do not include operation signals that drive the traveling body 110. If a manual operation signal from the operator is received during automatic control, the control device 160 may stop the automatic control.

[0030] The control device 160 is a computer including a processor 610, a main memory 630, a storage 650, and an interface 670. The storage 650 stores a program. The processor 610 reads the program from the storage 650, loads it into the main memory 630, and executes processing in accordance with the program.

[0031] Examples of storage 650 include semiconductor memory, magnetic disks, magneto-optical disks, optical disks, etc. Storage 650 may be an internal medium directly connected to a common communication line of control device 160, or may be an external medium connected to control device 160 via interface 670. Main memory 630 and storage 650 are non-transitory tangible storage media.

[0032] The processor 610 includes, by executing a program, a measurement data acquisition unit 611, an operation signal input unit 612, an attitude identification unit 613, a target identification unit 614, a movement control unit 615, an operation signal output unit 616, and a stall determination unit 617.

[0033] The measurement data acquisition unit 611 acquires measurement data from the measurement system of the work machine 100. Specifically, the measurement data acquisition unit 611 acquires measurement data from the position and orientation calculator 151, the inclination measuring device 152, the boom stroke sensor 153, the arm stroke sensor 154, the bucket stroke sensor 155, and the first pressure sensor P1 and the second pressure sensor P2 of each actuator A. The measurement data acquisition unit 611 calculates the angle of the revolving unit 120 by integrating the angular velocity of the revolving unit 120 measured by the inclination measuring device 152.

[0034] The operation signal input unit 612 receives input of operation signals manually operated by the operator from the operation device 143. The operation signals include a drive signal for raising or lowering the boom 131, a drive signal for raising or lowering the arm 132, a drive signal for dumping or digging the bucket 133, a drive signal for turning the rotating unit 120 right or left, a drive signal for operating the traveling unit 110 to travel, and an automatic control instruction signal for the work machine 100.

[0035] The target identification unit 614 receives teaching from the operator of the excavation preparation position and dump position of the bucket 133 as reference points for automatic control. Teaching is performed, for example, in the following procedure.

[0036] The target identification unit 614 displays an instruction to move the bucket 133 to the dump position on the operation terminal 142. The operator operates the operation device 143 to move the bucket 133 to the dump position and operates the teaching switch 143TC to output a teaching signal to the control device 160. The target identification unit 614 records the attitude of the revolving unit 120 and the work implement 130 represented by the measurement data at the time the teaching signal is received in the storage 650 as a first target attitude. The target attitude is represented by the orientation of the revolving unit 120 and the relative angle (stroke length) of the boom 131, arm 132, and bucket 133. The first target attitude is the target attitude for the first swing. Hereinafter, the orientation of the revolving unit 120 in the first target attitude will be referred to as the first target orientation.

[0037] Next, the target identification unit 614 displays on the operation terminal 142 an instruction to move the bucket 133 to the excavation preparation position. The operator operates the operation device 143 to move the bucket 133 to the excavation preparation position, and outputs a teaching signal to the control device 160 by operating the teaching switch 143TC. The target identification unit 614 records the attitude of the revolving unit 120 and the work implement 130 represented by the measurement data at the time the teaching signal is received in the storage 650 as a second target attitude. The second target attitude is the target attitude for the second swing. Hereinafter, the direction in which the revolving unit 120 faces in the second target attitude will be referred to as the second target orientation.

[0038] The movement control unit 615 generates an automatic operation signal that realizes automatic control when the operation signal input unit 612 receives input of an automatic control instruction signal. When the automatic control instruction signal is input, the movement control unit 615 executes automatic control that realizes a first swing that moves the bucket 133 to a dump position, or automatic control that realizes a second swing that moves the bucket 133 to an excavation preparation position. The movement control unit 615 determines whether to execute the first swing or the second swing in the automatic control based on whether the orientation of the rotating unit 120 at the time of input of the automatic control instruction signal is closer to the first target orientation or the second target orientation. If the orientation of the rotating unit 120 is closer to the second target orientation than the first target orientation, the movement control unit 615 executes the first swing, and if the orientation of the rotating unit 120 is closer to the first target orientation than the second target orientation, the movement control unit 615 executes the second swing.

[0039] The operation signal output unit 616 outputs the manual operation signal input to the operation signal input unit 612 or the automatic operation signal generated by the movement control unit 615 to the control valve 123 .

[0040] The stall determination unit 617 determines whether any of the actuators A has stalled. When actuator A stalls, the drive amount (operation amount) of actuator A approaches zero even if the control amount of the operation signal is large. Therefore, the stall determination unit 617 determines whether or not a stall has occurred using the following procedure. The stall determination unit 617 calculates the drive amount of actuator A from the measurement data acquired by the measurement data acquisition unit 611. The stall determination unit 617 calculates the expected value of the drive amount of actuator A from the control amount. The stall determination unit 617 determines that actuator A has stalled when the difference between the actual drive amount calculated from the measurement data and the expected value of the drive amount predicted from the operation signal exceeds a predetermined threshold value for a predetermined period of time or longer. The greater the load on the work implement 130, the greater the difference between the actual drive amount and the expected drive amount. In other words, determining whether or not a stall has occurred is an example of determining whether or not the load on the work implement 130 exceeds a threshold value. The stall determination unit 617 can determine whether the revolving body 120 or the work implement 130 is in an immobile state by determining whether or not the actuator A is stalled. The stall determination unit 617 according to the first embodiment can determine whether or not the bucket 133 is in an immobile state due to the work implement 130 being pressed against an obstacle by automatic swing control, for example.

[0041] <<Operation of the Control Device 160>> When the start switch 143SW is operated by an operator, the operation signal input unit 612 of the control device 160 receives an input of an automatic control instruction signal.

[0042] FIG. 5 is a flowchart (Part 1) showing swing control by the control device 160 according to the first embodiment. FIG. 6 is a flowchart (Part 2) showing swing control by the control device 160 according to the first embodiment. When an automatic control signal is input, the measurement data acquisition unit 611 first acquires measurement data on the orientation of the work machine 100 (Step S1). The movement control unit 615 reads the first target orientation and the second target orientation of the revolving bed 120 from the storage 650 and determines whether the orientation of the work machine 100 indicated by the measurement data is closer to the first target orientation or the second target orientation (Step S2). If the orientation of the work machine 100 is closer to the second target orientation, the movement control unit 615 determines to execute a first swing and reads the first target attitude from the storage 650 (Step 3). On the other hand, if the orientation of the work machine 100 is closer to the first target orientation, the movement control unit 615 determines to execute a second swing and reads the second target attitude from the storage 650 (Step 4).

[0043] Next, the measurement data acquisition unit 611 acquires measurement data on the position and orientation of the work machine 100, the tilt angle, the swing speed, the stroke length of each cylinder, and the pressure of the oil passages of each actuator A (step S5). The attitude identification unit 613 identifies the attitude of the work machine 130 based on the measurement data (step S6).

[0044] The movement control unit 615 generates an automatic operation signal for moving the work implement 130 closer to the target attitude based on the target attitude read out in step S3 or step S4. Specifically, the movement control unit 615 generates the automatic operation signal in the following procedure. First, the movement control unit 615 determines whether the attitude of the work implement 130 identified in step S5 is similar to the target attitude read out in step S3 or step S4 (step S7). For example, the movement control unit 615 determines that the attitude of the work implement 130 is similar to the target attitude if the difference between the relative angle of the boom 131 and the arm 132 and the relative angle related to the target attitude is equal to or smaller than a predetermined value. If the attitude of the work implement 130 is similar to the target attitude (step S7: YES), the movement control unit 615 skips generating the operation signal for the work implement 130 in steps S8 to S9. On the other hand, if the posture of the work implement 130 is not close to the target posture (step S7: NO), the movement control unit 615 generates an automatic operation signal to move the boom 131 and the arm 132 closer to the target posture (step S8).

[0045] At this time, the movement control unit 615 generates an automatic operation signal based on the rotation angle of the revolving unit 120 and the relative angles of the boom 131 and arm 132 identified from the measurement data acquired in step S5. Specifically, the movement control unit 615 determines the control amount, i.e., angular velocity, of the automatic operation signal for the boom 131 by substituting the difference between the measured value of the relative angle of the boom 131 and the value of the relative angle of the boom 131 related to the target attitude into a predetermined control amount function. The control amount function is a function in which the control amount increases as the difference in relative angles increases. As with the boom 131, the movement control unit 615 also determines the control amount of the automatic operation signal for the arm 132 based on the measured value of the relative angle of the arm 132 and the control amount function.

[0046] The movement control unit 615 calculates the expected value of the drive amount of the boom 131 and the arm 132 after the control cycle based on the automatic operation signal generated in step S8, and generates an automatic operation signal that drives the bucket 133 so as to cancel out the drive amount of the boom 131 and the arm 132 (step S9).

[0047] Next, the movement control unit 615 determines whether the rotating unit 120 will turn toward the target direction by inertial rotation when the rotation operation signal is stopped, based on the rotation speed of the rotating unit 120 identified in step S5 (step S10). If the rotating unit 120 will not turn toward the target direction by inertial rotation (step S10: NO), the movement control unit 615 generates a rotation operation signal by substituting the difference between the direction the rotating unit 120 is facing, identified in step S5, and the target direction into a control amount function (step S11).

[0048] The operation signal output unit 616 outputs the generated automatic operation signal to the control valve 123 (step S12). As a result, hydraulic oil is supplied from the control valve 123 to each actuator A, and each actuator A is driven. Next, the measurement data acquisition unit 611 acquires measurement data on the position and orientation of the work machine 100, the tilt angle, the swing speed, the stroke length of each cylinder, and the pressure of the oil passages of each actuator A (step S13). The stall determination unit 617 calculates the actual drive amount of the work implement 130 based on the measurement data acquired in step S13 (step S14). The stall determination unit 617 also calculates an expected value for the drive amount of the work implement 130 based on the control amount of the automatic operation signal output in step S12 (step S15). The stall determination unit 617 determines whether or not a stall of actuator A has occurred based on the difference between the drive amount calculated from the measurement data and the expected value for the drive amount calculated from the automatic operation signal (step S16). Specifically, the stall determination unit 617 determines that the actuator A is stalled when the difference between the actual drive amount calculated from the measurement data and the expected drive amount predicted from the operation signal exceeds a predetermined threshold value for a predetermined period of time or longer. In other words, the stall determination unit 617 determines whether the work machine 130 is in an immobile state.

[0049] If actuator A is not stalling (step S16: NO), the control device 160 returns to step S5 and continues the automatic swing control. On the other hand, if actuator A is stalling (step S16: YES), the control device 160 interrupts the automatic swing control (first automatic control) implemented in steps S5 to S12. Note that if the automatic swing control is continued when actuator A is stalling, hydraulic oil will continue to be discharged from the relief valve V.

[0050] When the automatic swing control is interrupted, the movement control unit 615 generates an automatic operation signal to raise the boom 131 at a predetermined speed (step S17). At this time, the movement control unit 615 neutralizes the rotating body 120, the arm 132, and the bucket 133. The operation signal output unit 616 outputs the automatic operation signal generated in step S17 to the control valve 123 (step S18). In other words, when a stall of actuator A occurs, the control device 160 stops the swing of the rotating body 120 and raises only the boom 131, thereby starting automatic avoidance control (second automatic control) to raise the work implement 130.

[0051] During automatic swing control, when actuator A stalls, there is a possibility that the work implement 130 is in contact with an obstacle such as a wall or rock. If the automatic swing control presses the work implement 130 against the obstacle while the work implement 130 is in contact with the obstacle, the strong frictional resistance between the obstacle and the work implement 130 can cause the work implement 130 to become stuck, leading to a stall of actuator A. Examples of obstacles that can cause the work implement 130 to become stuck during excavation work include rocks buried in soil and sand and the walls of trenches formed by excavation work. These obstacles are located below or to the sides of the work implement 130. Therefore, the work implement 130 can be moved away from the obstacle by raising only the work implement 130 using the automatic avoidance control from step S17 to step S18.

[0052] Next, the measurement data acquisition unit 611 acquires measurement data of the pressure in the oil line of actuator A (step S19). The stall determination unit 617 determines whether the pressure in the oil line of actuator A exceeds a predetermined threshold (step S20). The threshold may be the relief pressure or a value slightly lower than the relief pressure. When the work implement 130 abuts against an obstacle and becomes stuck, frictional resistance occurs between the work implement 130 and the obstacle, as described above. This frictional resistance increases the pressure in the oil line of actuator A. Therefore, while the pressure in the oil line of actuator A exceeds the predetermined threshold, the work implement 130 is abutting against the obstacle, and even if automatic swing control is resumed, there is a high possibility that the work implement 130 will stall again. On the other hand, if the pressure in the oil line of actuator A falls below the predetermined threshold, there is a possibility that the work implement 130 has moved away from the obstacle.

[0053] If the stall determination unit 617 determines that the pressure in the oil passage exceeds the threshold value (step S20: YES), the control device 160 returns the process to step S17 and continues the automatic avoidance control to raise the boom 131. On the other hand, if the stall determination unit 617 determines that the pressure in the oil passage is below the threshold value (step S20: NO), the control device 160 returns the process to step S5 and resumes the automatic swing control (first automatic control).

[0054] On the other hand, if it is determined that the revolving body 120 will be oriented in the target direction due to rotation by inertia (step S10: YES), the movement control section 615 determines whether the attitude of the work machine 100 has reached the target attitude (step S21). If the attitude of the work machine 100 has not reached the target attitude (step S21: NO), the control device 160 returns the process to step S5 and continues automatic revolve control.

[0055] On the other hand, if the attitude of the work machine 100 has reached the target attitude (step S21: YES), the control device 160 ends the automatic swing control.

[0056] <<Actions and Effects>> As described above, the control device 160 according to the first embodiment has the following functions. The control device 160 recognizes the states of the revolving unit 120 and the work implement 130. The control device 160 executes automatic swing control in accordance with an automatic control command, interlocking the revolving unit 120 and the work implement 130 to automatically move the bucket 133 to a target position. The control device 160 interrupts the automatic swing control if it is determined during automatic swing control that the revolving unit 120 or the work implement 130 has become immobile. This allows the control device 160 according to the first embodiment to prevent hydraulic oil from being continuously discharged from the relief valve V due to the automatic swing control when a stall of the actuator A occurs. This allows the control device 160 to prevent a decrease in fuel efficiency due to a stall of the actuator A during automatic control. The work machine 100 according to the first embodiment is an example of a work machine system.

[0057] Furthermore, the control device 160 according to the first embodiment executes automatic avoidance control to raise the work machine 130 when the revolving body 120 or the work machine 130 becomes immobile. This allows the automatic swing control to move the work machine 130 away from an obstacle that may cause actuator A to stall. Note that the control device 160 according to other embodiments does not need to execute automatic avoidance control. For example, the control device 160 according to other embodiments may end the automatic swing control and switch to manual control when actuator A stalls.

[0058] Furthermore, the control device 160 according to the first embodiment terminates the automatic avoidance control when the internal pressure of the oil passage related to actuator A falls below a threshold value during the automatic avoidance control. This allows the control device 160 to place the work implement 130 in a position where stalling does not occur. Furthermore, the control device 160 according to the first embodiment resumes the automatic swing control after terminating the automatic avoidance control. This allows the control device to complete automatic control by the work implement 130 while avoiding stalling of actuator A. Note that the control device 160 according to other embodiments may terminate the automatic avoidance control regardless of the internal pressure of the oil passage, for example, when the automatic avoidance control has been executed for a predetermined time, or when the work implement 130 has been raised by a predetermined height by the automatic avoidance control.

[0059] Other Embodiments Although one embodiment has been described in detail above with reference to the drawings, the specific configuration is not limited to the above, and various design modifications are possible. That is, in other embodiments, the order of the above-described processes may be changed as appropriate. Furthermore, some processes may be executed in parallel.

[0060] The control device 160 according to the embodiment described above may be configured by a single computer, or the configuration of the control device 160 may be divided among multiple computers that cooperate with each other to function as the control device 160. In this case, some of the computers that make up the control device 160 may be mounted inside the work machine 100, and other computers may be provided outside the work machine 100.

[0061] The control device 160 according to the embodiment described above performs automatic avoidance control when the work implement 130 becomes immobile during automatic swing control, but this is not limited to this. For example, the control device 160 according to other embodiments may perform automatic avoidance control when the work implement 130 becomes immobile during other automatic control that links the revolving unit 120 and the work implement 130, or automatic control that operates the revolving unit 120 independently, such as broom work. Broom work is work in which the revolving unit 120 is rotated with the bottom plate of the bucket 133 pressed against the ground, and soil is swept and leveled with the side of the bucket 133.

[0062] The control device 160 according to the embodiment described above determines whether the work implement 130 is in an immobile state based on the control amount related to automatic control and the drive amount of the revolving unit 120 and the work implement 130, but this is not limited to this. For example, the control device 160 according to another embodiment may determine whether the work implement 130 is in an immobile state by determining whether the internal pressure of the oil passage has reached the relief pressure. Furthermore, for example, the control device 160 according to another embodiment may determine whether the work implement 130 is in an immobile state based on a drive command and the hydraulic state of the oil passage. Specifically, the control device 160 may determine that the work implement 130 is in an immobile state when the flow velocity of the oil passage that is the target of the drive command is low relative to the drive amount indicated by the drive command. Furthermore, for example, when the external shape of the work machine 130 is measured using an external sensor such as a stereo camera or LiDar, the control device 160 can estimate the inclination angles of the boom 131, arm 132, and bucket 133 from the external shape of the work machine 130, and estimate the drive amount of the work machine 130 from changes in the inclination angles. In this case, the control device 160 may determine whether the work machine 130 is in an immobile state based on the control amount related to automatic control and the drive amount of the work machine 130 estimated from the external sensor.

[0063] Although the target attitude and target orientation in the above-described embodiments are recorded in the storage 650 by teaching, this is not limiting. For example, the work machine 100 in other embodiments may be equipped with an external sensor such as a stereo camera or LiDAR to recognize the dump location and identify the target attitude and target orientation based on this. That is, the target identification unit 614 may identify the target attitude and target orientation based on measurement data of the terrain. In another embodiment, if the dump location is a haulage vehicle, the position of the haulage vehicle may be received through communication with the haulage vehicle, and the target attitude and target orientation may be identified based on this. In another embodiment, if the haulage vehicle is autonomously traveling through communication with a control device, the position of the haulage vehicle may be received from the control device, and the target attitude and target orientation may be identified based on this. In another embodiment, the target identification unit 614 may identify the target attitude and target orientation based on input by the operator to the operation terminal 142.

[0064] Furthermore, the control device 160 according to the embodiment described above identifies the posture of the work implement 130 based on measurement data from a sensor that measures the posture of the work implement 130, but is not limited to this. For example, in another embodiment, if the work machine 100 is equipped with an external sensor such as a stereo camera or LiDAR, the posture of the work implement 130, particularly the height of the lowest point Q of the bucket 133, may be recognized based on the measurement data from the external sensor, and automatic control may be performed based on this.

[0065] The control device 160 according to the embodiment described above calculates the angle of the revolving unit 120 by integrating the angular velocity of the revolving unit 120 measured by the inclinometer 152, but this is not limited to this. For example, the control device 160 according to another embodiment may calculate the angle of the revolving unit 120 based on the difference in the orientation measured by the position and orientation calculator 151. In still another embodiment, the angle of the revolving unit 120 may be determined using the detection value of a rotation angle sensor provided in the revolving motor A20.

[0066] In another embodiment, the control device 160 may generate automatic control signals for each link component and the rotating unit 120 so that the bucket 133 follows a pre-specified trajectory. The trajectory may be determined, for example, by fitting a predetermined curve function or by teaching through manual operation. The trajectory may be represented by a time series of the attitude of the bucket 133, the attitude of each link component and the rotating unit 120, or an operation signal.

[0067] The work machine 100 according to the embodiment described above is operated directly by an operator from inside the cab 140, but this is not limited to this. For example, the work machine 100 according to other embodiments may be operated by remote control. A remote control system according to other embodiments comprises, for example, an operation device 143 provided remotely from the work machine 100, a display device that displays an image of the environment of the work machine 100, and a remote control device that communicates with the work machine 100. When the operator operates the operation device 143 of the remote control system, the remote control device transmits an operation signal to the control device 160 via communication. In this case, the functions of the control device 160 may be implemented in the remote control device, or may be shared and implemented in both the work machine 100 and the remote control device. The remote control system is an example of a work machine system.

[0068] The automatic control according to the above-described embodiment executes a first swing that moves the bucket 133 from a position at the end of excavation to a dump position and a second swing that moves the bucket 133 to a position for starting the next excavation, but is not limited to this. For example, in another embodiment, the control device 160 may perform fully automatic control that automatically executes a series of operations including the first swing, soil discharge, and second swing. Furthermore, the automatic control according to the above-described embodiment is triggered by the operation of the start switch 143SW by the operator, but is not limited to this. For example, in another embodiment, the control device 160 may autonomously determine the timing to start the automatic control and start the automatic control regardless of the operation of the start switch 143SW.

[0069] According to the above aspect, the work machine system can prevent a decrease in fuel efficiency due to stalling of the actuator during automatic control.

[0070] DESCRIPTION OF SYMBOLS 100...Work machine 110...Traveling body 111...Crawler 120...Swing body 121...Engine 122...Hydraulic pump 123...Control valve 130...Work machine 131...Boom 132...Arm 133...Bucket 140...Driver's cab 141...Driver's seat 142...Operation terminal 143...Operation device 143SW...Start switch 143TC...Teaching switch 151...Position and orientation calculator 152...Inclination measuring device 153...Boom stroke sensor 154...Arm stroke sensor 155...Bucket stroke sensor 160...Control device 610...Processor 611...Measurement data acquisition unit 612...Operation signal input unit 613...Attitude identification unit 614...Target identification unit 615...Movement control unit 616...Operation signal output unit 617...Stall determination unit 630...Main memory 650...Storage 670...Interface A...Actuator A10...Travel motor A20...Swing motor A31...Boom cylinder A32...Arm cylinder A33...Bucket cylinder B1...First bypass oil passage B2...Second bypass oil passage P1...First pressure sensor P2...Second pressure sensor R1...First oil passage R2...Second oil passage V1...First relief valve V2...Second relief valve

Claims

1. A work machine system comprising: a rotating body that can rotate around a rotation center; a work machine that includes a work implement and is operable relative to the rotating body; and a control device that controls the rotating body and the work implement, wherein the control device recognizes the state of the rotating body and the work implement, and executes first automatic control in accordance with an automatic control command to link the rotating body and the work implement to automatically move the work implement to a target position, and if it is determined during the first automatic control that the rotating body or the work implement is in an immobile state, the control device interrupts the first automatic control.

2. A work machine system as described in claim 1, wherein the control device, when it is determined during the first automatic control that the state of the rotating body or the work machine is immobile, initiates a second automatic control that stops the drive of the rotating body and raises the work machine.

3. A work machine system as described in claim 2, wherein the work machine has a plurality of link members connected to each other by joints and having the work implement attached to the tip thereof, and the second automatic control is a control to raise the link member located furthest from the base end of the plurality of link members.

4. A work machine system according to claim 2, wherein the control device terminates the second automatic control when the load on the work machine falls below a predetermined threshold.

5. A work machine system according to claim 4, wherein the control device resumes the first automatic control when the load on the work machine falls below a predetermined threshold.

6. A work machine system as described in claim 1, wherein the control device determines whether the rotating body or the work machine is in an immobile state based on the control amount related to the first automatic control and the movement amount of the rotating body and the work machine.

7. A work machine system as described in claim 6, wherein the control device determines that the rotating body or the work machine is in an immobile state when a state in which the difference between the amount of movement of the rotating body or the work machine estimated from the control amount related to the first automatic control and the actual amount of movement of the rotating body or the work machine exceeds a threshold continues for a set time or longer.

8. A work machine system as described in claim 6, wherein the control device determines that the rotating body or the work machine is in an immobile state by determining whether the internal pressure of a hydraulic circuit for driving the rotating body or the work machine has reached a predetermined pressure.

9. A control method for a work machine comprising a rotating body that can rotate around a rotation center, a work implement including a work tool and operable relative to the rotating body, and a control device, the control device having the following steps: a step in which the control device recognizes the state of the rotating body and the work implement; a step in which the control device executes first automatic control in accordance with an automatic control instruction to link the rotating body and the work implement and automatically move the work implement to a target position; and a step in which the control device interrupts the first automatic control if it is determined during the first automatic control that the state of the rotating body or the work implement is immobile.

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