Work machine system, and method for controlling work machine

Abstract

Provided is a control device of a work machine, which commands the operation of the actuator of a work tool according to a target position of said work tool. The control device changes the target position when the state of the actuator satisfies predetermined conditions.

Description

Work machine system and work machine control method

[0001] This application claims priority to Japanese Patent Application No. 2024-051631, 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. In Patent Document 1, a control device for the hydraulic excavator controls the bucket angle to be constant when the hydraulic excavator automatically swings toward a transport vehicle while carrying a load, so as to prevent the load from spilling from the bucket.

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

[0004] A hydraulic circuit having an actuator is provided with a relief valve to prevent an excessive increase in the internal pressure of the circuit. The relief valve opens to return hydraulic oil to the oil tank when the internal pressure of the circuit exceeds a relief pressure.

[0005] In the automatic operation described in Patent Document 1, an automatic operation signal is generated based on the difference between the attitude of the work machine and the target attitude. Therefore, if the target attitude of the work machine exceeds the movable range of the actuator, the attitude of the work machine does not reach the target attitude, and the automatic operation signal continues to be output. This causes the actuator to stall, resulting in a decrease in efficiency. An object of the present disclosure is to provide a work machine system and a control method for a work machine that can prevent a decrease in efficiency due to actuator stall.

[0006] According to one aspect of the present disclosure, a work machine system includes a work implement that includes multiple joints and a work tool and is operable relative to a main body, an actuator that drives the work implement, and a control device that controls the actuator, and the control device commands the operation of the actuator in accordance with a target attitude of the work tool and changes the target attitude when the state of the actuator satisfies a predetermined condition.

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

[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 a hydraulic circuit for a bucket cylinder 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 diagram showing an example of the movement of the work machine during a first swing according to the first embodiment; FIG. 6 is a diagram showing an example of the movement of the work machine during a second swing according to the first embodiment; FIG. 7 is a flowchart (part 1) showing first swing control by the control device according to the first embodiment; and FIG. 8 is a flowchart (part 2) showing first 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 loading it as cargo onto a loading platform such as a vessel of a loading object T such as a dump truck. 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 revolving body 120, a work implement 130, and a cab 140. Examples of the loading object T include a dump truck and a hopper.

[0011] 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 112 for driving each caterpillar track 111. The rotating body 120 is supported on the running body 110 so that it can rotate around 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.

[0012] <Configuration of the Swing Unit 120> The swing unit 120 includes an engine 121, a hydraulic pump 122, a control valve 123, and a swing motor 124. 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 (boom cylinder 131C, arm cylinder 132C, bucket cylinder 133C, travel motor 112, and swing motor 124) 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 124 is driven by hydraulic oil supplied from the hydraulic pump 122 via the control valve 123 to swing the swing unit 120. Note that the swing motor 124 according to other embodiments may be an electric motor instead of a hydraulic motor.

[0013] <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 131C, an arm cylinder 132C, and a bucket cylinder 133C. 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.

[0014] 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, the work machine 100 , which is a backhoe excavator, performs excavation by pulling the bucket 133 towards the front side of the rotating body 120 .

[0015] The boom cylinder 131C is a hydraulic cylinder for operating the boom 131. The base end of the boom cylinder 131C is attached to the revolving unit 120. The tip end of the boom cylinder 131C is attached to the boom 131. The arm cylinder 132C is a hydraulic cylinder for driving the arm 132. The base end of the arm cylinder 132C is attached to the boom 131. The tip end of the arm cylinder 132C is attached to the arm 132. The bucket cylinder 133C is a hydraulic cylinder for driving the bucket 133. The base end of the bucket cylinder 133C is attached to the arm 132. The tip end of the bucket cylinder 133C is attached to a link mechanism that rotates the bucket 133. 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. Although each cylinder according to the first embodiment is a hydraulic cylinder, in other embodiments, it may be another type of power cylinder, such as an electric cylinder. Furthermore, the actuators for driving the work machine 130 are not limited to power cylinders, and may be, for example, electric motors provided at the joints. The electric motors may be driven by battery power.

[0016] FIG. 2 is a block diagram showing a hydraulic circuit for the bucket cylinder 133C according to the first embodiment. The hydraulic circuit connecting the control valve 123 and the bucket cylinder 133C includes a first oil passage R1 connecting the control valve 123 and the head side of the bucket cylinder 133C and a second oil passage R2 connecting the control valve 123 and the bottom side of the bucket cylinder 133C. 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.

[0017] 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 133C even though the piston of the bucket cylinder 133C 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 133C even though the piston of the bucket cylinder 133C 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 reaches the upper limit of the bucket cylinder 133C during operation of the work implement 130, the internal pressure of the passage also reaches the relief pressure. When relief occurs in the bucket cylinder 133C, fuel is consumed even though the cylinder is stopped, resulting in reduced fuel efficiency. Therefore, in the first embodiment, when the cylinder has reached its stroke end, the direction toward the side where the stroke end has been reached is set as the non-operation direction. For example, when the cylinder has reached the bottom-side stroke end, the direction toward the bottom side is set as the non-operation direction. When the cylinder has reached the head-side stroke end, the direction toward the head side is set as the non-operation direction.

[0018] Note that the relief valve is not limited to being provided in the bucket cylinder 133C, but may also be provided in the boom cylinder 131C, the arm cylinder 132C, the travel motor 112, and the swing motor 124. 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.

[0019] 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.

[0020] 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.

[0021] 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.

[0022] 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 performed autonomously by the work machine 100. The first rotation is a series of operations in which the bucket 133 is positioned to the side of the loading target T due to excavation of the excavation target, and the boom 131 is raised while the bucket 133 is rotated to a direction facing the loading target T. The second rotation is a series of operations in which the bucket 133 is positioned above the loading target T due to loading, and the boom 131 is lowered while the bucket 133 is rotated to a predetermined direction. The side of the loading target T refers to the outside of a loading platform, such as a vessel, onto which cargo is loaded. Note that automatic control according to other embodiments may only involve the first rotation. In the first embodiment, the target orientations of the rotating unit 120 during the first rotation and the second rotation are each specified in advance by teaching. Note that the excavation target is typically located lower than the height of the loading target T. Therefore, during the first and second turns, the work machine 100 controls the drive of the work machine 130 so that the loading target T does not come into contact with the work machine 130. Details of the automatic control will be described later.

[0023] <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 .

[0024] 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 .

[0025] 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).

[0026] The boom stroke sensor 153 is attached to the boom cylinder 131C and detects the stroke length of the boom cylinder 131C. The stroke length of the boom cylinder 131C 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 132C and detects the stroke length of the arm cylinder 132C. The stroke length of the arm cylinder 132C 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 133C and detects the stroke length of the bucket cylinder 133C. The stroke length of the bucket cylinder 133C 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 stereo camera or LiDar to detect the external shape of the work machine 130 may be provided, and the posture may be estimated from the external shape.

[0027] <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 the automatic operation signals include at least operation signals for driving the revolving body 120 and the work implement 130. The automatic operation signals may or may not include an operation signal for driving the traveling body 110. If a manual operation signal is received from the operator during automatic control, the control device 160 may stop the automatic control.

[0028] 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.

[0029] 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.

[0030] The processor 610 includes, by executing a program, a measurement data acquisition unit 611, an operation signal input unit 612, an attitude determination unit 613, a reference determination unit 614, an angle determination unit 615, a movement control unit 616, and an operation signal output unit 617.

[0031] 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, the first pressure sensor P1, and the second pressure sensor P2. 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.

[0032] 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.

[0033] The attitude identifying unit 613 identifies the attitude of the work implement 130 in a vehicle body coordinate system that uses the revolving unit 120 as a reference, based on the measurement data acquired by the measurement data acquiring unit 611. Specifically, the attitude identifying unit 613 identifies the position of the tip P of the arm 132 ( FIG. 5 ), the position of the lowest point Q of the bucket 133 ( FIG. 5 ), and the ground angle of the bucket 133. The lowest point Q of the bucket 133 refers to the point on the outer shape of the bucket 133 that is the shortest distance from the ground surface.

[0034] A specific method for identifying the posture of the work machine 130 by the posture identifying unit 613 will be described below. The posture identifying unit 613 determines the vertical and horizontal components of the length of the boom 131 based on the relative angle of the boom 131 and the known length of the boom 131 (the distance from the pin at the base end to the pin at the tip end). Similarly, the posture identifying unit 613 determines the vertical and horizontal components of the length of the arm 132. The posture identifying unit 613 identifies, as the position of the tip P of the arm 132, a position that is away from the position of the work machine 100 in a direction identified from the orientation and posture of the work machine 100 by the sum of the vertical and horizontal components of the lengths of the boom 131 and the arm 132. In addition, the posture identifying unit 613 determines the position of the lowest point Q of the bucket 133 based on the relative angle of the bucket 133 and the known shape of the bucket 133. For example, the posture identification unit 613 calculates the position of each of a plurality of points on the outer hull of the bucket 133 based on the relative angle of the bucket 133, and identifies the point with the lowest height among the plurality of points as the lowest point Q. The posture identification unit 613 calculates the ground angle of the bucket 133 by adding the relative angle of the boom 131, the relative angle of the arm 132, and the relative angle of the bucket 133 to the pitch angle of the work machine 100.

[0035] The reference specifying unit 614 receives teachings from the operator of the excavation preparation position, the interference avoidance position, and the loading position of the bucket 133 as reference points for automatic control. Teaching is performed, for example, in the following procedure.

[0036] The reference identification unit 614 displays an instruction to move the bucket 133 to the excavation preparation position on the operation terminal 142. The operator operates the operation device 143 to move the bucket 133 to the excavation preparation position, and operates the teaching switch 143TC to output a teaching signal to the control device 160. The reference identification unit 614 sets the attitude of the work implement 130 identified by the attitude identification unit 613 as the target attitude for the second swing, sets the position of the tip P of the arm 132 as the target position for the second swing, and records in the storage 650 the orientation of the swing unit 120 as the target orientation for the second swing.

[0037] Next, the reference identification unit 614 displays on the operation terminal 142 an instruction to move the bucket 133 to an interference avoidance position that is the same height as the upper end of the vessel wall of the loading target T and where the work implement 130 and the loading target T do not overlap in a plan view from above. The vessel wall used for teaching may be any of the side, front, or rear walls of the vessel. The operator operates the operation device 143 to move the bucket 133 to the interference avoidance position and operates the teaching switch 143TC to output a teaching signal to the control device 160. The interference avoidance positions are input for both the right and left ends of the loading target T. This allows the reference identification unit 614 to identify the range of the loading platform of the loading target T. The height of the interference avoidance position may be offset upward by a certain amount to allow for control errors and measurement errors. The reference identification unit 614 records in the storage 650 the height of the lowest point Q of the bucket 133 identified by the posture identification unit 613 as the wall height Ht of the loading object T, and the direction in which the rotating body 120 is facing as the interference avoidance direction.

[0038] Next, the reference specification unit 614 displays on the operation terminal 142 an instruction to move the bucket 133 to a loading position above the loading target T. The operator operates the operation device 143 to move the bucket 133 to the loading position and operates the teaching switch 143TC to output a teaching signal to the control device 160. The reference specification unit 614 sets the attitude of the work implement 130 as the target attitude for the first swing, the position of the tip P of the arm 132 as the target position for the first swing, and the orientation of the rotating body 120 specified by the attitude specification unit 613 as the target orientation for the first swing, and records these in the storage 650. The height of the lowest point Q of the bucket 133 specified at the loading position may also be set as the wall height Ht. In other embodiments, the height of the loading target T does not necessarily have to be the wall height Ht, which is the height of the side wall of the loading platform, but may be the height of the highest point of the entire loading target T.

[0039] Furthermore, before executing automatic control, the reference identification unit 614 accepts the setting of a target holding angle for the bucket 133 in the first swing process of automatic control. The reference identification unit 614 causes, for example, the operation terminal 142 to display an input screen for the target holding angle for the bucket 133. When the operator operates the operation terminal 142 and inputs the target holding angle, the reference identification unit 614 records the input target holding angle in the storage 650. Note that the reference identification unit 614 according to other embodiments may set the target holding angle by teaching.

[0040] The angle identification unit 615 identifies, as a target swing angle, the angle between the initial orientation to which the revolving unit 120 faces when an automatic control instruction signal is input to the operation signal input unit 612 and the target orientation recorded in the storage 650. The angle identification unit 615 identifies, as an interference avoidance angle, the angle between the initial orientation to which the revolving unit 120 faces when an automatic control instruction signal is input to the operation signal input unit 612 and the interference avoidance orientation recorded in the storage 650. The interference avoidance angle is the swing angle at which the work implement 130 and the loading target T do not overlap in a plan view from above. The target swing angles include a first target swing angle that is the target swing angle for the first swing, and a second target swing angle that is the target swing angle for the second swing.

[0041] The movement control unit 616 generates an automatic operation signal that realizes automatic control when the operation signal input unit 612 receives an input of an automatic control instruction signal. When the automatic control instruction signal is input, the movement control unit 616 executes automatic control that realizes a first swing that moves the bucket 133 to a loading position, or automatic control that realizes a second swing that moves the bucket 133 to an excavation preparation position. The movement control unit 616 determines whether to execute the first swing or the second swing in the automatic control based on whether the bucket 133 is within the range of the loading target T in a plan view from above when the automatic control instruction signal is input. If the bucket 133 is not within the range of the loading target T's bed, the movement control unit 616 executes the first swing, and if the bucket 133 is within the range of the loading target T's bed, the movement control unit 616 executes the second swing. At this time, the movement control unit 616 controls the revolving unit 120 and the work implement 130 to prevent contact between the loading target T and the work implement 130 based on the wall height Ht and the interference avoidance angle stored in the storage 650.

[0042] The operation signal output unit 617 outputs the manual operation signal input to the operation signal input unit 612 or the automatic operation signal generated by the movement control unit 616 to the control valve 123 .

[0043] <<Operation During Automatic Control>> Here, the movement of the work machine 100 during automatic control according to the first embodiment will be described with reference to the drawings. Figure 5 is a diagram showing an example of the movement of the work machine 100 during a first swing according to the first embodiment. Figure 6 is a diagram showing an example of the movement of the work machine 100 during a second swing according to the first embodiment.

[0044] When automatic control for the first swing is initiated, as shown in Figure 5, the control device 160 first starts driving the work implement 130 (boom 131, arm 132, and bucket 133), and moves the bucket 133 upward by raising the boom 131. At this time, the control device 160 controls the bucket 133 so that the ground angle of the bucket 133 becomes the target holding angle. After a delay, the control device 160 starts swinging the swing unit 120. The control device 160 controls the swing angle of the swing unit 120 to the first interference avoidance angle θ ａ１The timing of starting the swing is adjusted so that the posture of the work implement 130 reaches the target posture for the first swing by the time the swing angle of the swing unit 120 reaches the first interference avoidance angle θ ａ１ If the posture of the work implement 130 reaches the target posture for the first swing before the posture of the work implement 130 coincides with the target posture, that is, if the height of the lowest point Q of the bucket 133 is higher than the wall height Ht of the loading target T, the work implement 130 will not come into contact with the loading target T due to the swing of the swing body 120. Note that the work implement 130 is driven simultaneously with the swing, and the swing angle is set to the first interference avoidance angle θ ａ１ If the attitude of the work implement 130 reaches the target attitude for the first swing before it matches the target attitude, the control device 160 may simultaneously start driving and swinging the work implement 130. Thereafter, when the bucket 133 reaches the loading position, the automatic control ends. Thereafter, the operator manually performs a dumping operation by rotating the bucket 133 in the dumping direction.

[0045] When the automatic control for the second rotation is started, the control device 160 starts the rotation of the rotating body 120. The control device 160 controls the rotation angle of the rotating body 120 to be equal to the second interference avoidance angle θ ａ２ The rotating body 120 is rotated without moving the work implement 130, and the height of the lowest point of the bucket 133 is maintained until the rotation angle of the rotating body 120 exceeds the second interference avoidance angle θ ａ２ When the rotation angle of the rotating body 120 exceeds the second target rotation angle θ ｔ２ When the attitude of the work implement 130 reaches the target attitude at the start of excavation, the control device 160 ends the driving of the work implement 130.

[0046] 5 and 6 show an example in which the positional relationship between the excavation position and the loading target T is approximately 90 degrees around the rotating unit 120, but this is not limited to this in other embodiments. For example, in other embodiments, the positional relationship between the excavation position and the loading target T may be another rotation angle position, such as approximately 180 degrees around the rotating unit 120.

[0047] <<Operation of the control device 160>> When the operator operates the start switch 143SW, the operation signal input unit 612 of the control device 160 accepts input of an automatic control instruction signal. When the automatic loading instruction signal is input, the control device 160 determines whether to execute the first swing or the second swing based on whether the bucket 133 is within a range above the loading platform of the loading target T in a plan view from above.

[0048] FIG. 7 is a flowchart (part 1) showing first swing control by the control device 160 according to the first embodiment. FIG. 8 is a flowchart (part 2) showing first swing control by the control device 160 according to the first embodiment. When performing a first swing, the control device 160 executes the first swing control shown in FIG. 6. First, the measurement data acquisition unit 611 acquires measurement data of the orientation of the work machine 100 (step S1). The movement control unit 616 reads out the target orientation (orientation toward the loading target T) of the rotating unit 120, the target posture, the wall height Ht of the loading target T, the interference avoidance orientation, and the target holding angle of the bucket 133 from the storage 650 (step S2). The angle identification unit 615 calculates a first target swing angle θ based on the orientation of the rotating unit 120 identified in step S1 and the target orientation and interference avoidance orientation read out in step S2. ｔ１ and the first interference avoidance angle θ ａ１ (Step S3).

[0049] Next, the measurement data acquisition unit 611 acquires measurement data on the position and orientation, tilt angle, swing speed, and stroke length of each cylinder of the work machine 100 (step S4). The attitude identification unit 613 identifies the attitude of the work implement 130 based on the measurement data (step S5). That is, the attitude identification unit 613 identifies the position of the tip P of the arm 132, the position of the lowest point Q of the bucket 133, and the angle of the bucket 133 with respect to the ground.

[0050] The movement control unit 616 calculates the target direction, target posture, and wall height Ht read out in step S2, and the first interference avoidance angle θ ａ１Based on this, the movement control unit 616 generates an automatic operation signal for moving the bucket 133 to above the loading target T. That is, the movement control unit 616 determines whether the lowest point Q of the bucket 133 is moved from the position of the lowest point Q at the start of the first swing control to the position corresponding to the wall height Ht and the first interference avoidance angle θ ａ１ At this time, the movement control unit 616 generates an automatic operation signal for the bucket 133 so that the ground angle of the bucket 133 becomes the target holding angle.

[0051] Specifically, the movement control unit 616 generates an automatic operation signal in the following procedure. First, the movement control unit 616 determines whether the posture of the work implement 130 identified in step S5 is similar to the target posture acquired in step S1 (step S6). For example, the movement control unit 616 determines that the posture of the work implement 130 is similar to the target posture if the difference between the position of the tip of the arm 132 in the target posture and the current position of the tip of the arm 132 is equal to or smaller than a predetermined value. If the posture of the work implement 130 is not similar to the target posture (step S6: NO), the movement control unit 616 generates an automatic operation signal that moves the boom 131 and the arm 132 closer to the target posture (step S7).

[0052] At this time, the movement control unit 616 generates an automatic operation signal based on the relative angle of the boom 131 and the arm 132 identified from the measurement data acquired in step S4. Specifically, the movement control unit 616 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 616 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.

[0053] The movement control unit 616 determines whether the bucket cylinder 133C has reached the stroke end based on the stroke length of the bucket cylinder 133C identified from the measurement data acquired in step S4 (step S8).

[0054] If the bucket cylinder 133C has reached the stroke end (step S8: YES), the movement control unit 616 updates the target holding angle to an angle obtained by adding the ground angle of the arm 132 to the relative angle of the bucket 133 at the stroke end of the bucket cylinder 133C (step S9). As a result, the movement control unit 616 restricts the movement of the bucket cylinder 133C in a direction that drives the bucket cylinder 133C beyond the stroke end (operation disallowed direction). In other words, the movement control unit 616 sets the direction toward the stroke end after the stroke end is reached as the operation disallowed direction.

[0055] If the bucket cylinder 133C has not reached the stroke end (step S9: NO) or if the target holding angle has been updated in step S9, the movement control unit 616 calculates the amount of change in the angles of the boom 131 and the arm 132 after the control cycle based on the automatic operation signal generated in step S7 (step S10). The movement control unit 616 generates an operation signal to maintain the ground angle of the bucket 133 at the target holding angle by substituting the difference between the target holding angle and the angle obtained by adding the amount of change in the angle calculated in step S8 to the ground angle of the bucket 133 calculated in step S5 into a control amount function (step S11). This allows the movement control unit 616 to generate an automatic operation signal that brings the ground angle of the bucket 133 closer to the target holding angle while canceling out the angle changes of the boom 131 and the arm 132 due to the automatic operation signal.

[0056] The movement control unit 616 determines whether the work machine 130 is swinging (step S12). The movement control unit 616 determines that the work machine 130 is swinging, for example, when the swing speed of the swing unit 120 is equal to or greater than a predetermined speed. If the work machine 130 is not swinging (step S12: NO), the movement control unit 616 calculates the completion time until the work machine 130 reaches the target posture based on the speeds of the boom 131 and arm 132 identified in step S7 (step S13). Furthermore, the movement control unit 616 calculates the completion time until the swing angle of the swing unit 120 reaches the first interference avoidance angle θ identified in step S3 when the swing unit 120 starts swinging. ａ１ (Step S14). The movement control unit 616 determines whether the completion time calculated in step S13 is less than the arrival time calculated in step S14 (Step S15). That is, the movement control unit 616 determines whether the turning angle is equal to the first interference avoidance angle θ ａ１ It is determined whether the work implement 130 will be in the target posture when it reaches the target posture.

[0057] If the completion time is equal to or longer than the arrival time (step S15: NO), that is, if the turning angle is equal to the first interference avoidance angle θ ａ１ If the work implement 130 does not assume the target posture by the time the work implement 130 reaches the target posture, the movement control unit 616 does not generate a swing operation signal for the swing structure 120. On the other hand, if the completion time is shorter than the arrival time (step S15: YES), that is, if the swing angle is equal to or smaller than the first interference avoidance angle θ ａ１ If the work implement 130 reaches the target attitude before reaching the target position, the movement control unit 616 generates a swing operation signal for the swing unit 120 (step S16). This allows the control device 160 to prevent the work implement 130 from swinging while the height is still low, resulting in contact with the loading target T.

[0058] The operation signal output unit 617 outputs the generated automatic operation signal to the control valve 123 (step S17), thereby driving the work machine 100. The control device 160 then returns the process to step S4 and continues control.

[0059] On the other hand, if it is determined in step S12 that the work implement 130 is swinging (step S12: YES), the movement control unit 616 determines whether or not the swing angle will reach the first target swing angle by inertial swing when the swing operation signal is stopped, based on the swing speed of the work implement 130 identified in step S4 (step S18). If the swing angle does not reach the first target swing angle by inertial swing (step S18: NO), the movement control unit 616 generates a swing operation signal in step S16, and the operation signal output unit 617 outputs the swing operation signal to the control valve 123 in step S17.

[0060] On the other hand, if it is determined that the swing angle will reach the first target swing angle due to the swing caused by inertia (step S18: YES), the movement control unit 616 determines whether the swing angle has reached the target swing angle and the attitude of the work machine 130 has become the target attitude (step S19). If the swing angle has reached the first target swing angle and the attitude of the work machine 130 has not become the target attitude (step S19: NO), the control device 160 returns the process to step S4.

[0061] On the other hand, if the swing angle reaches the target swing angle and the attitude of the work implement 130 becomes the target attitude (step S19: YES), the control device 160 ends the first swing process.

[0062] <<Actions and Effects>> In this way, the control device 160 according to the first embodiment commands operation of the bucket cylinder 133C in accordance with the target holding angle of the bucket 133, and when the state of the bucket cylinder 133C reaches the stroke end, restricts operation in an operation-prohibited direction that would drive the bucket cylinder 133C beyond the stroke end. This makes it possible for the control device 160 according to the first embodiment to prevent cylinder stall from occurring when the bucket cylinder 133C reaches the stroke end. This makes it possible for the control device 160 to prevent a decrease in fuel efficiency due to cylinder stall. The work machine 100 according to the first embodiment is an example of a work machine system.

[0063] Here, an example in which the bucket cylinder 133C reaches its stroke end during the first swing process will be described. For example, if the first swing process is started when the target holding angle is close to horizontal and the attitude of the work machine 100 is such that the boom 131 and the arm 132 are extended greatly forward, the bucket cylinder 133C reaches its stroke end on the head side before the ground angle of the bucket 133 reaches the target holding angle. The control device 160 controls the bucket cylinder 133C based on the difference between the ground angle of the bucket 133 and the target holding angle, and therefore commands the supply of hydraulic oil to the bottom side of the bucket cylinder 133C even though the bucket cylinder 133C has reached its stroke end on the head side. This results in a cylinder stall of the bucket cylinder 133C. In response to this, the control device 160 according to the first embodiment can prevent cylinder stall by changing the target holding angle of the bucket 133 to an angle corresponding to the relative angle of the bucket 133 at the stroke end when the bucket cylinder 133C reaches its stroke end.

[0064] 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.

[0065] 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.

[0066] The control device 160 according to the embodiment described above changes the target holding angle in accordance with the stroke end of the bucket cylinder 133C in the first swing process, but is not limited to this. For example, if the control device 160 according to another embodiment performs control to maintain the angle of the bucket 133 at the target holding angle in the second swing process, the control device 160 may change the target holding angle in accordance with the stroke end of the bucket cylinder 133C in the second swing process.

[0067] A control device 160 according to another embodiment may change the target holding angle in accordance with the stroke end of the bucket cylinder 133C in control for maintaining the angle of the bucket 133 at a constant angle for ground leveling. A control device 160 according to another embodiment may change the target angle in accordance with the stroke end of the bucket cylinder 133C in control for changing the target angle of the bucket 133, such as in automatic excavation or automatic earth removal.

[0068] The control device 160 according to the embodiment described above determines whether the bucket cylinder 133C has reached the stroke end based on the measured value of the stroke length of the bucket cylinder 133C, but this is not limited to the above. For example, a control device 160 according to another embodiment may determine whether the bucket cylinder 133C has reached the stroke end by determining whether the relative angle of the bucket 133 exceeds a movable angle range determined by the movable range of the bucket cylinder 133C. For example, when the attitude of the bucket 133 is measured using an inclination sensor such as an IMU, it is possible to determine whether the bucket cylinder 133C has reached the stroke end based on the relative angle of the bucket 133. Furthermore, a control device 160 according to another embodiment may determine whether the bucket cylinder 133C has reached the stroke end based on the measured values ​​of the pressure in the first oil passage R1 and the second oil passage R2. When the bucket cylinder 133C reaches the stroke end, the pressure in the oil passages rises to the relief pressure. Therefore, the control device 160 can determine whether the bucket cylinder 133C has reached its stroke end by determining whether the measured pressure values ​​in the first oil passage R1 and the second oil passage R2 have reached the relief pressure. Furthermore, for example, when measuring the external shape of the work implement 130 using an external sensor such as a stereo camera or LiDAR, the control device 160 may estimate the inclination angles of the boom 131, arm 132, and bucket 133 from the external shape of the work implement 130 and determine whether the relative angle between the bucket 133 and the arm 132 exceeds the movable angle range, thereby determining whether the bucket cylinder 133C has reached its stroke end. Furthermore, the work machine 100 according to other embodiments may be equipped with a motor instead of a power cylinder as an actuator. While the motor does not have a stroke end, because each joint of the work implement 130 has a defined movable range, the control device 160 limits the rotation of the motor in a direction that exceeds the movable range (a direction that does not permit operation). The control device 160 may determine whether the bucket 133 has reached the limit of its movable range, for example, using an angle sensor provided in the bucket 133 .

[0069] In another embodiment, when the bucket 133 has a tilt function and the control device 160 controls the bucket 133 according to a target tilt angle, the control device 160 may change the target tilt angle in accordance with the stroke end of the power cylinder that drives the bucket 133 to tilt.

[0070] The target attitude, target orientation, interference avoidance orientation, and wall height Ht in the embodiments described above are recorded in storage 650 by teaching, but this is not limited to this. For example, a work machine 100 according to other embodiments may be equipped with an external sensor such as a stereo camera or LiDAR to recognize the position and shape of the loading object T, and identify the target attitude, target orientation, interference avoidance orientation, and wall height Ht based on this. In other words, the reference identification unit 614 may identify the target attitude, target orientation, interference avoidance orientation, and wall height Ht based on shape data of the loading object T. Furthermore, in other embodiments, the position, attitude, and orientation of the loading object T may be received by communication with the loading object T, and the target attitude, target orientation, interference avoidance orientation, and wall height Ht may be identified based on this and the known shape of the loading object T. In another embodiment, when the loading object T travels autonomously through communication with a control device, the position and orientation of the loading object T may be received from the control device, and the target posture, target orientation, interference avoidance orientation, and wall height Ht may be determined based on this and the known shape of the loading object T. In another embodiment, the reference specification unit 614 may specify the target posture, target orientation, interference avoidance orientation, and wall height Ht based on input by the operator to the operation terminal 142. In another embodiment, the work machine 100 may specify the target posture, target orientation, and interference avoidance orientation, and the wall height Ht separately. That is, in another embodiment, the control device 160 may separately include a first reference specification unit that specifies the target posture, target orientation, and interference avoidance orientation, and a second reference specification unit that specifies the wall height Ht. For example, the work machine 100 may specify the target posture, target orientation, and interference avoidance orientation through teaching, and specify the wall height Ht through input by the operator. The operator may also specify the wall height, which is the height of the loading target, by inputting the type of work machine. That is, the control device 160 specifies the wall height Ht by reading the height associated with the input type of machine from a table that associates the type of machine with the wall height in advance.

[0071] 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.

[0072] 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 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 124.

[0073] Although the control device 160 according to the embodiment described above performs automatic control based on a comparison between the swing angle and the interference avoidance angle, this is not limited to this. For example, the control device 160 according to another embodiment may perform automatic control based on a comparison between the position of the bucket 133 and the rearmost point in the swing direction of the rotating unit 120 on the outline of the loading target T. For example, the control device 160 according to another embodiment may adjust the swing start timing so that the bucket 133 is positioned in an area near the rearmost point in the swing direction of the rotating unit 120. In still 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 predetermined trajectory. The trajectory may be determined, for example, by fitting a predetermined curve function or by manual teaching. 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.

[0074] 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.

[0075] The automatic control according to the embodiment described above executes a first swing, which moves the bucket 133 from a position at the end of excavation to a loading point, and a second swing, which moves the bucket 133 to a position for starting the next excavation. However, this is not limited to this. For example, in another embodiment, the control device 160 may perform fully automatic control, which automatically executes a series of operations, including the first swing, soil removal, and second swing. Furthermore, for example, in another embodiment, the control device 160 may execute only the second swing without executing the first swing. Furthermore, the automatic control according to the embodiment described above is triggered by the operation of the start switch 143SW by the operator, but this 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.

[0076] According to the above aspect, the work machine system can prevent a decrease in efficiency due to stalling of the actuator.

[0077] DESCRIPTION OF SYMBOLS 100...Work machine 110...Traveling body 111...Crawler 112...Travel motor 120...Swinging body 121...Engine 122...Hydraulic pump 123...Control valve 124...Swing motor 130...Working machine 131...Boom 131C...Boom cylinder 132...Arm 132C...Arm cylinder 133...Bucket 133C...Bucket cylinder 140...Driver's cab 141...Driver's seat 142...Operation terminal 143...Operation device 143SW...Start switch 143TC...Teaching switch 151...Position and direction calculator 152...Inclination measuring device 153...Boom stroke sensor 154...Arm stroke sensor 155...Bucket stroke sensor 160...Control device 610...Processor 630...Main memory 650...Storage 670...Interface T...Loading object 611...Measurement data acquisition unit 612...Operation signal input unit 613...Attitude determination unit 614...Reference determination unit 615...Angle determination unit 616...Movement control unit 617...Operation signal output unit R1...First oil passage R2...Second oil passage P1...First pressure sensor B1...First bypass oil passage V1...First relief valve P2...Second pressure sensor B2...Second bypass oil passage V2...Second relief valve

Claims

1. A work machine system comprising: a work machine including a plurality of joints and a working implement, operable relative to a main body; an actuator that drives the work machine; and a control device that controls the actuator, wherein the control device commands the operation of the actuator in accordance with a target attitude of the working implement, and when the operation of the actuator based on the command is in a direction in which operation is not permitted, restricts the operation in the direction in which operation is not permitted.

2. A work machine system as set forth in claim 1, wherein the control device commands the operation of the actuator in accordance with the target attitude of the work implement when the work implement is moving the load upward or downward after excavation.

3. A work machine system according to claim 2, wherein the work implement is a bucket, and the target attitude of the work implement is an attitude in which the opening of the bucket is horizontal with respect to the ground.

4. A work machine system as described in claim 1, wherein the actuator is a power cylinder that drives the work implement, the non-permitted direction of operation is a direction toward the stroke end when the power cylinder reaches the stroke end, and the control device limits the operation so that the actuator does not exceed the stroke end when the power cylinder reaches the stroke end.

5. A control method for a work machine comprising a work implement including a plurality of joints and a working tool that is operable relative to a main body, and an actuator that drives the work implement, the control method for a work machine comprising: a step of commanding operation of the actuator in accordance with a target posture of the working tool; and a step of restricting operation of the actuator in a non-permitted direction when the operation of the actuator based on the command is in the non-permitted direction.

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