Work machine

Abstract

Provided is a work machine comprising a work tool actuator for driving a work tool attached to a work device, an operation device for operating the work device, an orientation sensor for detecting the orientation of the work device or the like, and a controller for controlling the work device so that the work tool does not excavate beyond a construction target surface on the basis of signals from the operation device and the posture sensor. The work tool actuator includes first / second actuators for operating the work tool in different directions. The controller calculates parallelism between the operation direction of the work tool and the construction target surface. When the parallelism is less than a preset threshold value the controller drives the first actuator to cause the work tool to face the construction target surface, and when the parallelism is equal to or greater than the threshold value, the controller restricts the work tool from being operated along the construction target surface by the first actuator and outputs a command signal for driving the second actuator.

Description

Work machinery

[0001] The present invention relates to a work machine such as a hydraulic excavator.

[0002] In civil engineering projects and the like, work machines with a front working implement attached to the vehicle body are used. This type of work machine, for example a hydraulic excavator, may be equipped with a so-called machine control function that automatically controls the movement of the boom and the movement of the bucket in accordance with the amount of arm operation by the operator so that the bucket moves along a predetermined construction target surface. This machine control allows the operator to excavate along the construction target surface with simple lever operation, and generally provides better workability than when operating a work machine by manual operation.

[0003] Hydraulic excavators may be equipped with actuators that change the bucket's attitude, such as a bucket cylinder that swings a bucket, which is a type of working tool, back and forth, as well as a tilt rotator that swings (tilts) and rotates (rotates) the bucket left and right. Patent Documents 1 and 2 disclose techniques for automatically controlling the bucket's attitude relative to a construction target surface by using the bucket's tilt operation as a target of machine control.

[0004] JP 2021-085213 A International Publication No. 2016 / 158779

[0005] However, under machine control, which controls the bucket so that its tip is parallel to the target surface, if the bucket's tilt axis is perpendicular to the target surface, the bucket tilts parallel to the target surface, and the angle of the bucket's tip relative to the target surface remains unchanged. This makes it impossible to align the bucket with the tip parallel to the target surface. Furthermore, if the bucket's tilt axis is close to perpendicular to the target surface, even if it is not perpendicular, the angle of the bucket's tip relative to the target surface will change, but the rate of change will be small relative to the amount of tilt movement. In this case, the machine control functions, causing the bucket to tilt excessively to make the tip of the bucket parallel to the target surface, resulting in excavation work being performed with the bucket not facing the excavation direction.

[0006] Since excavation work cannot be performed satisfactorily if the bucket is not facing the excavation direction, in situations where the bucket automatically turns sideways, the operator is forced to take the time to manually correct the bucket's position. Furthermore, if the operator has to go through the hassle of manually correcting the bucket's position every time an excavation operation is performed, the operator may end up disabling the machine control function and working, which could result in a decrease in the quality of the construction surface created.

[0007] The present invention provides a work machine that can improve workability by suppressing impractical posture changes of a work implement due to machine control.

[0008] In order to achieve the above object, the present invention provides a work machine comprising a work machine main body, a work device rotatably attached to the work machine main body and having a plurality of joints, a work tool constituting part of the work device and attached to the tip of the work device, a work tool actuator for driving the work tool, a control device for operating the work device, an operation detection device for detecting an operation signal of the operation device, a plurality of attitude sensors for detecting the attitudes of the work machine main body and the work device, and a controller for outputting a command signal to control the operation of the work device based on the operation signal of the control device detected by the operation detection device and the attitudes detected by the plurality of attitude sensors so that the work tool does not excavate beyond a predetermined construction target surface, wherein the work tool actuator is a first actuator for operating the work tool in a first direction, and a second actuator that moves the work tool in a second direction different from the first direction, wherein the controller calculates the parallelism between the movement direction of the work tool and the construction target surface based on the operation signal detected by the operation detection device and the attitude detected by the attitude sensor, and if the parallelism is less than a preset threshold value, outputs a command signal to drive the first actuator of the work tool actuators to change the attitude of the work tool so that it faces the construction target surface, and if the parallelism is equal to or greater than the threshold value, outputs a command signal to restrict the movement of the work tool along the construction target surface by the first actuator of the work tool actuators, and outputs a command signal to drive the second actuator of the work tool actuators.

[0009] According to the present invention, it is possible to suppress impractical posture displacement of the work tool due to machine control, thereby improving workability.

[0010] 1 is a diagram showing a hydraulic excavator as an example of a work machine to which the present invention is applicable, together with a construction target surface. FIG. 2 is a side view of a hydraulic excavator as a work machine according to one embodiment of the present invention. FIG. 3 is a schematic diagram of a drive system of a work machine according to one embodiment of the present invention. FIG. 4 is a block diagram showing main functions of a controller provided in a work machine according to one embodiment of the present invention. FIG. 5 is an explanatory diagram of an example operation in which the bucket is tilted to align the toe with the construction target surface. FIG. 6 is an explanatory diagram of an example in which the bucket is tilted but the toe cannot be aligned with the construction target surface. FIG. 7 is an explanatory diagram of another example in which the bucket is tilted but the toe cannot be aligned with the construction target surface. FIG. 8 is an explanatory diagram of an example of bucket attitude control in a work machine according to one embodiment of the present invention. FIG. 9 is an explanatory diagram of another example of bucket attitude control in a work machine according to one embodiment of the present invention. FIG. 10 is a flowchart showing the procedure for bucket attitude control by a controller when a tilt cylinder is set as the first actuator in one embodiment of the present invention. FIG. 11 is a flowchart showing the procedure for bucket attitude control by a controller when a rotator actuator is set as the first actuator in one embodiment of the present invention. FIG. 12 is a flowchart showing the procedure for bucket attitude control by a controller when a bucket cylinder is set as the first actuator in one embodiment of the present invention.

[0011] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0012] 1 is a diagram showing a hydraulic excavator, which is an example of a work machine to which the present invention is applied, together with a work target surface. The left side of Fig. 1 is the work machine, specifically the front side of a revolving body 12, which will be described later.

[0013] The present invention is applicable to work machines used in road construction, building construction, civil engineering, dredging, and the like, and can be suitably applied to, for example, a hydraulic excavator 1 as shown in FIG. 1 . However, the present invention can also be applied to other work machines, such as wheel loaders. The construction target surface S can be set as a single plane as shown in FIG. 1 , or can be set three-dimensionally by combining multiple planes. Setting this construction target surface S makes it possible to limit the area that can be excavated by the front attachment 20. The construction target surface S can also be set relative to the hydraulic excavator 1 in a local coordinate system based on the hydraulic excavator 1, or can be set in a global coordinate system based on the construction site or the Earth. Furthermore, the construction target surface S can be set as a horizontal plane or a gentle slope below the ground G on which the hydraulic excavator 1 touches the ground, or as a steep slope or vertical surface to the side, front, or rear of the hydraulic excavator 1.

[0014] -Working Machine- Figure 2 is a side view of the hydraulic excavator 1. The hydraulic excavator 1 comprises a work machine main body (vehicle body) 10 and a front work implement 20 attached to the work machine main body 10. The work machine main body 10 comprises a running body 11 and a rotating body 12 that is rotatably mounted on the upper part of the running body 11. The running body 11 is a crawler with tracks, but may also be equipped with tires as running wheels. The rotation axis of the rotating body 12 extends in the vertical direction, and the rotating body 12 rotates in the left-right direction. An operator can travel the hydraulic excavator 1 and rotate the rotating body 12 by operating an operating lever device 19, which will be described later.

[0015] The front working implement 20 is configured to rotate at a connecting portion relative to the revolving unit 12. The front working implement 20 is equipped with a working device 21 that is rotatably attached to the work machine body 10 and has multiple joints. A working implement that constitutes part of the working implement 21 is rotatably attached to the tip of the working device 21. The working implement is a type of attachment, and in this embodiment, a case in which a bucket 24 having a tilting device and a rotating device is attached as the working implement will be described as an example.

[0016] The working device 21 includes a boom 22 having a base end rotatably connected to the revolving unit 12, an arm 23 having a base end rotatably connected to the tip of the boom 22, a bucket 24 having a base end rotatably connected to the tip of the arm 23, a boom cylinder 22A that rotates the boom 22 up and down relative to the revolving unit 12, an arm cylinder 23A that rotates the arm 23 back and forth relative to the boom 22, and a bucket cylinder 24A that rotates the bucket 24 back and forth relative to the arm 23. The bucket 24 is connected to the tip of the arm 23 via a tilt device 25 serving as a swinging device and a rotator 26 serving as a rotation device. The tilt device 25 is composed of a tilt device main body rotatably attached so as to sandwich the tip of the arm 23 with a pin extending in the width direction, and a pair of tilt cylinders attached to the side surfaces of the tilt device main body. The rotator 26 is composed of a rotator main body that is swingably attached to the center of the tip of the tilt device main body by a pin, and a rotary motor that is a hydraulic motor that is provided inside the rotator main body. The bottom sides of the pair of tilt cylinders described above are attached to the tilt device main body, and the rod tips are attached to the rotator main body. The base end of the tilt device 25 is connected to the tip of the arm 23. The base end of the rotator 26 is connected to the tip of the tilt device 25. The bucket 24 is connected to the tip of the rotator 26, or more specifically, to the tip of the rotary motor.

[0017] The front work implement 20 is also equipped with a bucket cylinder 24A as a work implement actuator that drives the bucket 24 to change the attitude of the bucket 24, a tilt cylinder 25A as a tilt actuator, and a rotary motor (hydraulic motor) 26A as a rotator actuator. In this embodiment, the work implement actuator is configured with multiple actuators (bucket cylinder 24A, tilt cylinder 25A, rotary motor 26A) that move the bucket 24 in multiple directions among the pitch direction, yaw direction, and roll direction. For example, when viewed from the tip side of the bucket 24, the bucket 24 rotates (swings) in the pitch direction P by the bucket cylinder 24A, rotates (swings) in the yaw direction Y ( FIG. 5 ) by the tilt cylinder 25A, and rotates in the roll direction R by the rotary motor 26A. The pitch direction P, yaw direction Y, and roll direction R are all different directions. In this embodiment, the rotation axis Px of the bucket cylinder 24A in the pitch direction P, the rotation axis Yx of the tilt cylinder 25A in the yaw direction Y, and the rotation axis Rx of the rotation motor 26A in the roll direction R are perpendicular to each other (defining a three-dimensional Cartesian coordinate system).

[0018] Each of the actuators mounted on the front attachment 20, specifically the boom cylinder 22A, arm cylinder 23A, bucket cylinder 24A, tilt cylinder 25A, and rotation motor 26A, is a hydraulic actuator. Operation of these hydraulic actuators causes the boom 22, arm 23, bucket 24, tilt device 25, and rotator 26 to rotate, respectively.

[0019] The boom 22, arm 23, bucket 24, tilt device 25, and rotator 26 are each equipped with attitude sensors (tilt sensors) 22S-26S. The work machine main body 10, in this embodiment the revolving unit 12, is equipped with an attitude sensor (tilt sensor) 10S. The revolving unit 12 is also equipped with an attitude sensor (swing angle sensor) 12S that measures the relative swing angle of the revolving unit 12 with respect to the running unit 11.

[0020] The revolving unit 12 is also equipped with a main frame 13, a cab 14, a controller 100, a hydraulic system 15, a prime mover 16, a hydraulic pump 17, and a global navigation satellite system (GNSS) 18. The controller 100 will be described later with reference to FIG. 4 .

[0021] The cab 14 has an operator's seat inside, and is supported alongside the front work implement 20 on the left and right sides at the front of the main frame 13, which is the base frame of the revolving body 12. Inside the cab 14, an operating lever device 19, a monitor device 160, and a construction surface management device 170 are provided.

[0022] - Drive System - Figure 3 is a schematic diagram of the drive system of the hydraulic excavator 1. Connected to the controller 100 are an operating lever device 19, attitude sensors 10S, 12S, 22S-26S, GNSS 18, hydraulic system 15, construction surface management device 170, and monitor device 160. Connected to the hydraulic system 15 are a hydraulic pump 17 and each hydraulic actuator.

[0023] The control lever device 19 is an electric control device for operating the front work implement 20 (working implement 21, bucket 24, tilt device 25, rotator 26, etc.), the traveling unit 11, and the revolving unit 12. It includes a control lever and an operation detection device that detects the tilt amount (operation signal) of the control lever. While only one control lever device 19 is shown in FIG. 3 to avoid complication, a plurality of control lever devices 19 are provided corresponding to each driven member, such as the boom 22, arm 23, bucket 24, tilt device 25, rotator 26, revolving unit 12, and traveling unit 11. Each control lever device 19 detects an operation signal generated by the operator's lever operation using the operation detection device, converts the target operation amount requested by the operator for the corresponding driven member into an electrical signal, and outputs the electrical signal to the controller 100. For example, the control lever is configured so that the operating speed of the hydraulic actuator increases as the tilt amount increases. The operator operates the hydraulic excavator 1 by adjusting the operating speed of each hydraulic actuator depending on the lever operation amount. The operating lever device 19 may be a hydraulic pilot type operating device or a remote operating device.

[0024] Attitude sensors 10S, 12S, 22S-26S detect the attitude of each of the corresponding members, such as the work machine main body 10, revolving unit 12, working device 21 (boom 22, arm 23), bucket 24, tilt device 25, rotator 26, etc. Specifically, attitude sensor 22S measures the inclination angle of the boom 22, attitude sensor 23S measures the inclination angle of the arm 23, attitude sensor 24S measures the inclination angle of the bucket 24, attitude sensor 25S measures the inclination angle of the tilt device 25, attitude sensor 26S measures the inclination angle of the rotator 26, and attitude sensor 10S measures the inclination angle of the revolving unit 12, and outputs the results to controller 100. In addition, attitude sensor 12S measures the relative rotation angle of the revolving unit 12 with respect to the traveling unit 11, and outputs the results to controller 100. These attitude sensors may be any type that can measure the attitude of the corresponding member, and may be, for example, an IMU (INERTIAL MEASUREMENT UNIT) type, a type that detects the relative angle between the corresponding member and the member that supports it, or a type that measures the stroke of a hydraulic cylinder that drives the corresponding driven member.

[0025] The GNSS 18 is a position measurement device that acquires position information of the work machine main body 10, specifically the revolving unit 12. In this embodiment, the GNSS 18 is exemplified as the position measurement device, but a position measurement device other than the GNSS, such as a laser positioning meter or a total station, can also be used as long as it can identify the position of the hydraulic excavator 1.

[0026] The hydraulic system 15 is configured to include a hydraulic circuit having valve devices 22V-26V such as solenoid control valves and directional control valves. In FIG. 3, the valve devices corresponding to the traveling unit 11 and the revolving unit 12 are not shown. The solenoid control valves of the valve devices 22V-26V operate in response to the operation of the operating lever device 19 or in response to an operation command value input from the controller 100 by the machine control function. The pilot pressure output from the solenoid control valves thus operated drives the directional control valves of the valve devices 22V-26V, which in turn drives the boom cylinder 22A, arm cylinder 23A, bucket cylinder 24A, tilt cylinder 25A, and rotation motor 26A connected to each of these directional control valves. In the example of Fig. 3, the valve device 22V corresponds to the boom cylinder 22A, the valve device 23V corresponds to the arm cylinder 23A, the valve device 24V corresponds to the bucket cylinder 24A, the valve device 25V corresponds to the tilt cylinder 25A, and the valve device 26V corresponds to the rotary motor 26A. The operating direction and operating speed of these hydraulic actuators such as the arm cylinder 23A are controlled by pressure oil whose supply direction and supply flow rate are controlled by a directional control valve, and they drive the corresponding driven members such as the arm 23. Note that by adding or changing valve devices in the hydraulic system 15, it is possible to add and drive attachments and equipment other than those illustrated in Fig. 3.

[0027] The prime mover 16 and the hydraulic pump 17 constitute the prime mover of the hydraulic excavator 1. The prime mover 16 is an engine (internal combustion engine) or an electric motor. The hydraulic pump 17 is driven by the prime mover 16, and hydraulic pressure is generated as the power required for the hydraulic excavator 1. The pressurized oil discharged from the hydraulic pump 17 is controlled by the hydraulic system 15 as described above, and is supplied to various actuators.

[0028] In FIG. 3, the boom cylinder 22A, arm cylinder 23A, bucket cylinder 24A, tilt cylinder 25A, and rotation motor 26A are shown, and other hydraulic actuators such as a swing hydraulic motor and a traveling hydraulic motor are not shown.

[0029] The construction surface management device 170 is, for example, a computer or storage device, and stores and manages a predetermined construction target surface S that is the target for excavation by the front attachment 20. The construction target surface S is based on, for example, design data for the developed terrain at the site. The construction surface management device 170 is connected to the monitor device 160, and the construction target surface S stored in the construction surface management device 170 is displayed on the monitor device 160. It is also possible to use the monitor device 160 to set the construction target surface S for the hydraulic excavator 1 in the construction surface management device 170.

[0030] The monitor device 160 is a setting input / display device that has a touch panel and buttons for performing various settings and displaying information. By using this monitor device 160, the attitude of the hydraulic excavator 1 (such as the angles of the components of the work machine main body 10 and the front work implement 20), area data of the construction target surface S set in the construction surface management device 170, the positional relationship and distance between the construction target surface S and the front work implement 20, etc. can be displayed to the operator, and various dimensions and mass of the front work implement 20 can be set.

[0031] - Controller - Figure 4 is a block diagram showing the main functions of the controller 100. The controller 100 is a computer having an arithmetic unit 110 such as a CPU and a storage unit 150 such as RAM, ROM, HDD, or SSD. As shown in the figure, the controller 100 is electrically connected to an operating lever device 19, a construction surface management device 170, a monitor device 160, attitude sensors 10S, 12S, 22S-26S, a GNSS 18, and a hydraulic system 15.

[0032] The controller 100 has a machine control function. A machine control program 151 and a necessary database 152 are stored in the storage device 150. These programs 151 and database 152 are loaded into the arithmetic unit 110, which outputs command signals to control the operation of the work device 21 (boom cylinder 22A, arm cylinder 23A) based on the operation signals of the operating lever device 19 and the signals of the attitude sensors 10S, 12S, 22S-26S (i.e., the attitude detected by these sensors) so that the bucket 24 does not excavate beyond a predetermined construction target surface S. The machine control function functions, for example, when the distance between the tip of the bucket 24 and the construction target surface S, calculated based on the signals of the attitude sensors 10S, 12S, 22S-26S, is equal to or less than a predetermined position, and the controller 100 intervenes in the operation of the operating lever device 19 by the operator to control the hydraulic system 15 and control the trajectory of the bucket 24. In addition, the controller 100 has a function as a type of machine control to automatically control the work implement actuator, specifically at least one of the bucket cylinder 24A, tilt cylinder 25A, and rotation motor 26A, so that the parallelism between the toe of the bucket 24 and the construction target surface S is a predetermined value or greater during excavation.

[0033] The "parallelism" between the tip of the bucket 24 and the construction target surface S refers to the degree of parallelism between the edge of the tip of the bucket 24 and the construction target surface S, and can be calculated as cos θ, for example, when the angle formed between the plane including the edges of the left and right undersides of the bucket 24 and the construction target surface S is θ.

[0034] The controller 100 also has a function to calculate the direction of movement of the bucket 24 by the implement actuator (bucket cylinder 24A, tilt cylinder 25A, or rotary motor 26A) and the parallelism with the construction target surface S, based on the operation signal detected by the operation detection device and the work machine main body 10 and the front implement 20 detected by the posture sensor. This function is executed by the calculation device 110. For bucket 24 posture control, a first actuator that is driven preferentially among the bucket cylinder 24A, tilt cylinder 25A, and rotary motor 26A is set in the database 152. In principle, the posture of the bucket 24 is automatically controlled by the first actuator during machine control, and if the first actuator cannot control the bucket 24 to the desired posture, the second actuator is driven. The second actuator is an implement actuator other than the first actuator. In the present embodiment, when there are three or more implement actuators and multiple actuators that can serve as the second actuator, a priority order is set among them, with the second actuator, the third actuator, and so on, in descending order of priority. The settings of the first actuator and the second actuator may be preset when the hydraulic excavator 1 is shipped, or may be set by the operator using the monitor device 160. Furthermore, for example, an actuator that enables the first actuator to control the attitude of the bucket 24 with a smaller amount of movement according to the parallelism (i.e., the attitude of the bucket 24) may be automatically selected as the second actuator during operation.

[0035] The "parallelism" between the direction of movement (pitch direction P, yaw direction Y, or roll direction R) of the bucket 24 by the work implement actuator (bucket cylinder 24A, tilt cylinder 25A, or rotation motor 26A) and the construction target surface S refers to the degree of parallelism between the two, and may be calculated as the angle formed by the rotation axis (rotation axis Px, Yx, or Rx) of the work implement actuator with respect to the construction target surface S, for example, θ in Figure 7(c) as cos θ. Here, if cos θ is a small value, the two described above will not be parallel, and if cos θ is a large value, the two described above will be close to parallel.

[0036] If the calculated parallelism is less than a threshold value previously set in database 152, controller 100 outputs a command signal to drive a first actuator among the work implement actuators to change the attitude of the bucket 24 so that it faces the construction target surface S. If there are multiple work implement actuators, the work implement actuator driven at this time is the first actuator. Conversely, if the parallelism is equal to or greater than the threshold, controller 100 outputs a command signal to restrict the movement of the bucket 24 along the construction target surface S by the first actuator among the work implement actuators, and also outputs a command signal to drive a second actuator among the work implement actuators. If there are multiple work implement actuators, the work implement actuator whose movement is restricted at this time is the first actuator. If there are multiple work implement actuators, the second actuator is driven while the movement of the first actuator is restricted.

[0037] Furthermore, in the above, whether the first actuator can control the bucket 24 to the desired attitude may be determined by setting a permissible angle in advance for the work implement angle (e.g., α in FIG. 7D ), which is the angle (orientation) of the bucket 24 with respect to the excavation direction during machine control. In this embodiment, this permissible angle is set in the database 152 and stored in the storage device 150, which serves as a memory provided within the controller. The permissible angle may be a default value based on actual performance values, or may be set by the operator using the monitor device 160. Alternatively, a configuration may be adopted in which multiple permissible angle candidates are prepared as table values, allowing the operator to select the permissible angle from the candidates, and the operator may trial-select the permissible angle while actually operating the hydraulic excavator 1 to search for a value that suits his or her own intuition. When the parallelism between the movement direction of the bucket 24 by the work implement actuator (the first actuator if there are multiple actuators) and the construction target surface S is equal to or greater than the threshold value, the controller 100 calculates, as a limit amount, the movement amount of the work implement actuator until the work implement angle reaches the permissible angle, and limits the movement amount of the bucket 24 by the work implement actuator by this limit amount.

[0038] To achieve the above operations, the controller 100 includes, as shown in FIG. 4 , an attitude calculation unit 111, a required movement calculation unit 112, a target surface position calculation unit 113, a target speed calculation unit 114, a target speed correction unit 115, a movement command value calculation unit 116, and a bucket control unit 117. The bucket control unit 117 includes a tilt parallelism calculation unit 117A, a rotator parallelism calculation unit 118A, a bucket parallelism calculation unit 119A, a tilt movement determination unit 117B, a rotator movement determination unit 118B, and a bucket movement determination unit 119B. These are functions executed by the calculation device 110 and are realized, for example, by loading a program 151 from a storage device 150 into the calculation device 110. Note that, in addition to software elements such as the program 151, the functions of the attitude calculation unit 111 and the like may also be realized by hardware elements such as circuits.

[0039] The attitude calculation unit 111 calculates the current attitude of the hydraulic excavator 1 based on the input force signals from the attitude sensors 10S, 12S, 22S-26S, for example, the angles of each of the driven members to which the attitude sensors 10S, 12S, 22S-26S are attached.

[0040] The required movement calculation unit 112 calculates the direction of movement currently required for each hydraulic actuator of the hydraulic excavator 1, such as the boom cylinder 22A, arm cylinder 23A, bucket cylinder 24A, tilt cylinder 25A, and rotary motor 26A that drive the front work implement 20, based on the operation signal from the operating lever device 19 and the current posture information of the hydraulic excavator 1 calculated by the posture calculation unit 111.

[0041] The target surface position calculation unit 113 calculates position information of the construction target surface S, such as the position of the construction target surface S relative to the hydraulic excavator 1, the position of the tip of the bucket 24, the distance between the tip of the bucket 24 and the construction target surface S, based on the current position information of the hydraulic excavator 1 acquired by GNSS 18 and the current attitude information of the hydraulic excavator 1 calculated by the attitude calculation unit 111.

[0042] The target speed calculation unit 114 calculates the target speed of each hydraulic actuator of the hydraulic excavator 1, such as the boom cylinder 22A, arm cylinder 23A, bucket cylinder 24A, tilt cylinder 25A, and rotary motor 26A that drive the front work implement 20, based on the current attitude information of the hydraulic excavator 1 calculated by the attitude calculation unit 111, the position information of the construction target surface S calculated by the target surface position calculation unit 113, and the required action calculated by the required action calculation unit 112.

[0043] The tilt parallelism calculation unit 117A calculates the parallelism between the tilt operation direction of the bucket 24 (tilt operation plane defined by the arc-shaped yaw direction Y) and the construction target surface S. As described above, this parallelism is obtained, for example, by dividing the angle of the rotation axis Yx of the tilt operation in the yaw direction Y with respect to the construction target surface S by 90°. For example, if the construction target surface S is a horizontal plane, and the rotation axis Yx is vertical, the angle of the rotation axis Yx with respect to the construction target surface S is 90°, that is, the rotation axis Yx and the construction target surface S are perpendicular, and the parallelism between the tilt operation direction and the construction target surface S is maximum (= 1). Conversely, if the construction target surface S and the rotation axis Yx are horizontal, that is, if they are parallel, the parallelism between the tilt operation direction and the construction target surface S is minimum (= 0).

[0044] The rotator parallelism calculation unit 118A calculates the parallelism between the rotation operation direction of the bucket 24 (the rotation operation plane defined by the circular roll direction R) and the construction target surface S. As described above, this parallelism is obtained, for example, by dividing the angle of the rotation axis Rx of the rotation operation in the roll direction R with respect to the construction target surface S by 90°. For example, if the construction target surface S is a horizontal plane, and the rotation axis Rx is vertical, the angle of the rotation axis Rx with respect to the construction target surface S is 90°, that is, the rotation axis Rx and the construction target surface S are perpendicular, and the parallelism between the rotation operation direction and the construction target surface S is maximum (= 1). Conversely, if the construction target surface S and the rotation axis Rx are horizontal, that is, if they are parallel, the parallelism between the rotation operation direction and the construction target surface S is minimum (= 0).

[0045] The bucket parallelism calculation unit 119A calculates the parallelism between the direction (bucket operation plane defined by the arc-shaped pitch direction P) of the bucket 24's operation in the dump or crowd direction (hereinafter referred to as bucket operation) and the construction target surface S. As described above, this parallelism is obtained, for example, by dividing the angle of the rotation axis Px of the bucket operation in the pitch direction P with respect to the construction target surface S by 90°. For example, if the construction target surface S is a vertical plane, and the rotation axis Px is horizontal, the angle of the rotation axis Px with respect to the construction target surface S is 90°, that is, the rotation axis Px and the construction target surface S are perpendicular, and the parallelism between the bucket operation direction and the construction target surface S is maximum (= 1). Conversely, if the construction target surface S and the rotation axis Px are horizontal, that is, they are parallel, the parallelism between the bucket operation direction and the construction target surface S is minimum (= 0).

[0046] The tilt operation determination unit 117B determines whether or not operation of the tilt cylinder 25A is necessary based on the operation priority of the bucket cylinder 24A, tilt cylinder 25A, and rotation motor 26A, and the calculation results of the tilt parallelism calculation unit 117A, rotator operation determination unit 118B, and bucket operation determination unit 119B, and calculates the limit amount for the operation of the tilt cylinder 25A.

[0047] The rotator operation determination unit 118B determines whether or not operation of the rotation motor 26A is required, and calculates the limit amount for the operation of the rotation motor 26A, based on the operation priority of the bucket cylinder 24A, tilt cylinder 25A, and rotation motor 26A, and the calculation results of the tilt parallelism calculation unit 117A, rotator operation determination unit 118B, and bucket operation determination unit 119B.

[0048] The bucket operation determination unit 119B determines whether or not operation of the bucket cylinder 24A is required, and calculates the limit amount for the operation of the bucket cylinder 24A, based on the operation priority of the bucket cylinder 24A, the tilt cylinder 25A, and the rotation motor 26A, and the calculation results of the tilt parallelism calculation unit 117A, the rotator operation determination unit 118B, and the bucket operation determination unit 119B.

[0049] The target speed correction unit 115 corrects the target speeds of the hydraulic actuators of the hydraulic excavator 1, such as the boom cylinder 22A, arm cylinder 23A, bucket cylinder 24A, tilt cylinder 25A, and rotary motor 26A that drive the front work implement 20, based on the calculation results of the attitude calculation unit 111, the required operation calculation unit 112, the target surface position calculation unit 113, the target speed calculation unit 114, the tilt operation determination unit 117B, the rotator operation determination unit 118B, and the bucket operation determination unit 119B.

[0050] The operation command value calculation unit 116 generates operation command values ​​for each electromagnetic control valve of the hydraulic system 15 as command signals based on the target speed corrected by the target speed correction unit 115, and outputs the generated command signals to each electromagnetic control valve in the hydraulic system 15.

[0051] - Basic operation of machine control - When machine control is functioning, the front work implement 20 is driven in response to the operation of the operator, and the controller 100 corrects and controls the operation of the front work implement 20 by intervening in the operator's operation so that the bucket 24 does not excavate beyond the construction target surface S and so that the bucket 24 is in a predetermined attitude relative to the construction target surface S.

[0052] For example, if the operator has enabled machine control of the bucket 24, and the bucket 24 is located in an area where machine control functions, specifically when the distance between the tip of the bucket 24 and the construction target surface S is less than a predetermined distance, when the operator performs crowding of the arm 23, the boom 22 automatically rotates upward or downward so that the tip of the bucket 24 moves along the construction target surface S, as shown in Figure 1. This allows the operator to perform excavation work along the construction target surface S without the need for skilled operation.

[0053] Furthermore, in the area where machine control functions, the controller 100 drives the bucket cylinder 24A to control the attitude of the bucket 24 in the pitch direction P so that the attitude of the bucket 24 relative to the construction target surface S is kept constant. This eliminates the need for delicate lever operation to adjust the direction or angle of the bucket 24, and allows the operator to position the bucket 24 in a predetermined attitude by simply crowding the arm 23 to perform excavation work.

[0054] Additionally, since the hydraulic excavator 1 of this embodiment has a tilt device 25, it is also possible to drive the tilt cylinder 25A to control the attitude of the bucket 24 in the yaw direction Y so that the toe of the bucket 24 and the construction target surface S are parallel (parallelism is a predetermined value or more). Similarly, since the hydraulic excavator 1 has a rotator 26, it is also possible to make the toe of the bucket 24 and the construction target surface S parallel (parallelism is a predetermined value or more) by driving the rotation motor 26A to control the attitude of the bucket 24 in the roll direction R.

[0055] Basic control related to machine control is described in detail in, for example, Japanese Patent No. 6872666.

[0056] --Example of operation in which the bucket is tilted to align the toe with the construction target surface-- As shown in Figure 5, when the direction of bucket tilt operation (yaw direction Y) and the construction target surface S are perpendicular or intersect at an angle close to perpendicular, the amount of change in the angle of the toe of the bucket 24 relative to the construction target surface S per unit angle of tilt operation becomes large. Therefore, even if the toe of the bucket 24 is inclined with respect to the construction target surface S as shown in the left figure, it is easy to change the posture of the bucket 24 so that the toe is aligned with the construction target surface S as shown in the right figure. This often occurs mainly when the arm 23 is in a posture perpendicular or close to perpendicular with respect to the construction target surface S.

[0057] --Example in which the toe cannot be aligned with the construction target surface even when the bucket is tilted-- Figure 6 is an explanatory diagram of an example in which the toe cannot be aligned with the construction target surface even when the bucket is tilted. Figure 6(a) is a top view, Figure 6(b) is a side view, and Figure 6(c) is a front view. As shown in Figure 6, when the direction of the bucket tilt operation (yaw direction Y) and the construction target surface S are parallel (the rotation axis Yx and the construction target surface S are perpendicular), the tilt operation causes the bucket 24 to move parallel to the construction target surface S, so the angle between the toe of the bucket 24 and the construction target surface S does not change, and the toe of the bucket 24 cannot be aligned with the construction target surface S. This often occurs mainly when the arm 23 is in a position parallel or nearly parallel to the construction target surface S.

[0058] FIG. 7 is an explanatory diagram of another example in which the toe of the bucket cannot be aligned with the construction target surface even when the bucket is tilted. Figures 7(a) to 7(c) are views before the bucket tilt operation, and Figures 7(d) and 7(e) are views after the bucket tilt operation. Figure 7(a) is a top view showing the attitude of the bucket 24 before the tilt operation, Figure 7(b) is a side view, and Figure 7(c) is a front view (viewed by arrow VIIc). Figure 7(d) is a top view showing the attitude of the bucket 24 after the tilt operation, and Figure 7(e) is a front view (viewed by arrow VIIe).

[0059] As shown in Figures 7(a) to 7(c), when the bucket tilt operation direction and the construction target surface S are nearly parallel, for example, when the angle θ of the rotation axis Yx with respect to the construction target surface S is close to 90° as shown in Figures 7(b) and 7(c), the amount of change in the angle of the toe of the bucket 24 with respect to the construction target surface S per unit angle of tilt operation is small. Therefore, the angle of the toe of the bucket 24 changes only slightly with changes in the tilt angle, and in order to align the toe of the bucket 24 with the construction target surface S as shown in Figure 7(e), the bucket 24 needs to be tilted significantly (Figure 7(d)). As a result, as shown in Figure 7(d), the work tool angle α, which is the angle of the bucket 24 with respect to the arm 23, i.e., with respect to the excavation direction D (in this example, the angle as viewed in a direction perpendicular to the construction target surface S), is tilted significantly. Because the hydraulic excavator 1 drives the front working implement 20 in various positions, it is rare that the direction of bucket tilt movement and the construction target surface S are completely parallel, and in many cases the direction of bucket tilt movement and the construction target surface S are nearly parallel, as shown in FIG. 7 .

[0060] - Actions Required by the Operator - When operating the arm 23 to move the bucket 24 along the construction target surface S to perform excavation, the operator desires that the toe of the bucket 24 be parallel to the construction target surface S through bucket tilt operation. However, even if the toe of the bucket 24 is parallel to the construction target surface S, satisfactory excavation cannot be performed if the bucket 24 is excessively tilted relative to the arm 23 (the work tool angle α becomes excessively large) as shown in FIG. 7(d) and the bucket 24 is not facing the excavation direction D. If the machine control functions and the bucket 24 assumes an impractical position as shown in FIG. 7(d), the operator is forced to operate the tilt cylinder 25A to correct the direction of the bucket 24, and then manually adjust the position of the bucket 24 relative to the construction target surface S by appropriately operating the bucket cylinder 24A, tilt cylinder 25A, and rotation motor 26A. Therefore, the operator is focused on making the bucket 24 parallel to the construction target surface S, and does not want the bucket 24 to be tilted in a direction that is significantly inclined relative to the excavation direction D by the bucket tilt operation.

[0061] - Bucket attitude control in this embodiment - Figure 8 is an explanatory diagram of an example of bucket attitude control in this embodiment. Figures 8(a) to 8(c) are diagrams before the bucket operation, and Figures 8(d) to 8(f) are diagrams after the bucket operation. Figure 8(a) is a top view showing the attitude of the bucket 24 before the bucket operation, Figure 8(b) is a side view, and Figure 8(c) is a front view (viewed by arrow VIIIc). Figure 8(d) is a top view showing the attitude of the bucket 24 after the bucket operation, Figure 8(e) is a side view, and Figure 8(f) is a front view (viewed by arrow VIIIf). The states illustrated in Figures 8(a) to 8(c) are equivalent to the states illustrated in Figures 7(a) to 7(c).

[0062] In this embodiment, in order to reduce the effort required of the operator to perform manual operations by excessively tilting the orientation of the bucket 24 with respect to the excavation direction D, when the bucket tilt operation direction and the construction target surface S are parallel or nearly parallel (θ = 90° or θ ≈ 90°), as shown in Figures 8(a) to 8(c), control that greatly tilts the orientation of the bucket 24 with respect to the excavation direction D (making the work tool angle α excessively large) (bucket tilt operation in the yaw direction Y in this example) is restricted.

[0063] For example, if the tilt cylinder 25A is set as the first actuator to align the toe of the bucket 24 with the construction target surface S, tilting of the bucket 24 is prohibited when the parallelism between the yaw direction Y in which the bucket 24 tilts and the construction target surface S is equal to or greater than a predetermined threshold, as shown in Figures 8(a) to 8(c). This prevents excessive bucket tilting (an excessively large work tool angle α) unintended by the operator. Another method for preventing excessive tilting of the bucket 24 with respect to the excavation direction D may be to set the allowable angle for the work tool angle α that the operator is willing to accept, as described above, and determine the limit on bucket tilting based on the allowable angle.

[0064] Furthermore, if the parallelism between the bucket tilt movement direction and the construction target surface S is equal to or greater than a threshold value, another work implement actuator, for example, the bucket cylinder 24A, is operated as a second actuator to reduce the parallelism between the bucket tilt movement direction and the construction target surface S to below the threshold value. This makes it possible to make the toe of the bucket 24 parallel to the construction target surface S by bucket tilt movement. In this way, after driving the bucket cylinder 24A to change the posture of the bucket 24, the bucket 24 can be tilted to make the toe of the bucket 24 align with the construction target surface S. This allows the operator to perform excavation work with the toe of the bucket 24 aligned with the construction target surface S simply by operating the arm. Note that, to cancel the parallelism between the bucket tilt movement direction and the construction target surface S, as shown in FIG. 8( e), the bucket cylinder 24A is operated in a direction such that the toe of the bucket 24 approaches or moves away from the construction target surface S, and the angle φ between the rotation axis Yx and the construction target surface S in a side view is made greater or smaller than 90°.

[0065] FIG. 9 is an explanatory diagram of another example of bucket attitude control in this embodiment. FIGS. 9(a) to 9(c) are views before the rotation operation, and FIGS. 9(d) to 9(f) are views after the rotation operation. FIG. 9(a) is a top view showing the attitude of the bucket 24 before the rotation operation, FIG. 9(b) is a side view, and FIG. 9(c) is a front view (viewed by arrow IXc). FIG. 9(d) is a top view showing the attitude of the bucket 24 after the rotation operation, FIG. 9(e) is a side view, and FIG. 9(f) is a front view (viewed by arrow IXf). The states illustrated in FIGS. 9(a) to 9(c) are equivalent to the states illustrated in FIGS. 7(a) to 7(c).

[0066] While Fig. 8 has described an example in which the bucket cylinder 24A is driven as the second actuator, Fig. 9 shows an example in which the rotary motor 26A is driven as the second actuator. As shown in Fig. 9(f), the bucket 24 may also be driven in the roll direction R to reduce the parallelism between the bucket tilt operation direction and the construction target surface S to below a threshold value, thereby bringing the toe of the bucket 24 into a parallel state with the construction target surface S. Furthermore, by driving the bucket 24 in the roll direction R, the toe of the bucket 24 may be made parallel with the construction target surface S by the bucket tilt operation.

[0067] -Control Procedure- Next, the procedure for controlling the attitude of the bucket 24 by the controller 100 will be described with reference to Figures 10 to 12. Figure 10 is a flowchart showing the procedure for controlling the attitude of the bucket 24 by the controller 100 when the tilt cylinder 25A is set as the first actuator. Figure 11 is a flowchart showing the procedure for controlling the attitude of the bucket 24 by the controller 100 when the rotary motor 26A is set as the first actuator. Figure 12 is a flowchart showing the procedure for controlling the attitude of the bucket 24 by the controller 100 when the bucket cylinder 24A is set as the first actuator. Any one of the programs relating to the flows in Figures 10 to 12 may be stored in the storage device 150, or multiple programs may be stored in the storage device 150 and selectively executed by the arithmetic device 110 depending on the setting of the first actuator. The flowcharts in Figures 10 to 12 are executed in parallel with machine control of the boom cylinder 22A and the arm cylinder 23A, and are all repeatedly executed at a predetermined cycle time (for example, approximately 0.1 s) while the machine control function is enabled and the hydraulic excavator 1 is operating.

[0068] (1) Flowchart 1 (FIG. 10) When the flow of FIG. 10 starts, the controller 100 first calculates the current attitude of the hydraulic excavator 1 by the attitude calculation unit 111 in step S101, as described above.

[0069] In step S102, the controller 100 calculates the position information of the construction target surface S by the target surface position calculation unit 113 as described above.

[0070] In step S103, the controller 100 acquires an operation signal generated by the operator operating the lever based on an input from the operating lever device 19. The order of steps S101 to S103 can be changed as appropriate.

[0071] When the procedure proceeds to step S104, the controller 100 uses the required movement calculation unit 112 to calculate the required movement direction for each hydraulic actuator of the front work implement 20 in response to the operation of the operator, based on the attitude of the hydraulic excavator 1, the operation signal of the operating lever device 19, etc.

[0072] In the following step S105, the controller 100 calculates the parallelism between the movement direction of the bucket tilt operation and the construction target surface S using the tilt parallelism calculation unit 117A, as described above.

[0073] When the procedure proceeds to step S106, the controller 100 determines, based on the calculation results of the attitude calculation unit 111 and the target surface position calculation unit 113, whether the tip of the bucket 24 is in the control area where machine control is executed, specifically, whether the distance (for example, the shortest distance) between the tip of the bucket and the construction target surface S is equal to or less than a set distance, using the tilt operation determination unit 117B. In other words, it is determined whether or not to execute the machine control function.

[0074] If the tip of the bucket 24 is outside the control area where machine control is executed, the controller 100 advances the procedure from step S106 to step S107, and sets the tilt operation amount related to machine control to 0 by the bucket control unit 117. Therefore, unless the operator intentionally performs a tilt operation, the bucket 24 does not tilt in the process that goes through step S107.

[0075] If the tip of the bucket 24 is located in a control area where machine control is executed, the controller 100 proceeds from step S106 to step S108, and the tilt operation determination unit 117B determines whether the parallelism calculated in step S105 is equal to or greater than a predetermined threshold. This threshold is a preset value, and is the parallelism set within a range in which the tip of the bucket 24 can be aligned with the construction target surface S by tilt operation alone, so that the work tool angle α does not exceed the above-mentioned allowable angle.

[0076] If the parallelism is equal to or greater than the threshold value, the controller 100 proceeds from step S108 to step S109, and as described above, the tilt operation determination unit 117B calculates the limit amount of the bucket tilt operation in accordance with the allowable angle set for the orientation of the bucket 24.

[0077] In the following step S110, the controller 100 causes the bucket control unit 117 to calculate a target operation amount for the bucket tilt operation within a range that does not exceed the limit amount calculated in step S109. Therefore, the operation amount of the bucket tilt calculated in the process that goes through step S110 is at most the limit amount calculated in step S109. The operation amount of the bucket tilt calculated in step S110 can be set to be limited by the limit amount, or to 0 (that is, bucket tilt operation is prohibited), or can be set to be limited by an intermediate value between the limit amount and 0, for example.

[0078] In step S111, the controller 100 calculates the target operating amount of the second actuator (bucket cylinder 24A or rotary motor 26A) using the bucket control unit 117 so that the parallel state between the bucket tilt operation and the construction target surface S is eliminated (for example, so that the parallelism between the tilt operation direction and the construction target surface S becomes less than the above-mentioned threshold value) or so that the parallelism becomes lower than it is now.

[0079] If the parallelism is less than the threshold value, the controller 100 proceeds from step S108 to step S112, and the bucket control unit 117 calculates a target tilt movement amount so that the toe of the bucket 24 is aligned with the construction target surface S by the bucket tilt movement. Therefore, in the process that goes through step S112, the attitude of the bucket 24 is controlled by the tilt cylinder 25A without driving the bucket cylinder 24A or the rotation motor 26A.

[0080] In step S113, the controller 100 calculates an operation command value for the tilt cylinder 25A (or the tilt cylinder 25A, and the rotary motor 26A or the bucket cylinder 24A) based on the target operation amount calculated by the bucket control unit 117, outputs the calculated value to the hydraulic system 15, and controls the posture of the bucket 24.

[0081] 10, the machine control related to the attitude control of the bucket 24 shown in the same figure is executed in parallel with the machine control of the boom cylinder 22A and the arm cylinder 23A. In the machine control of the boom cylinder 22A and the arm cylinder 23A, the target speeds of the boom cylinder 22A and the arm cylinder 23A calculated by a target speed calculation unit 114 in response to the operation of the operating lever device 19 are corrected as appropriate by a target speed correction unit 115 based on the target plane information, and the boom cylinder 22A and the arm cylinder 23A are driven in accordance with the target speeds.

[0082] The controller 100 repeatedly executes the above procedure while driving the front attachment 20, controlling the attitude of the bucket 24 in real time according to conditions such as the attitude and position of the front attachment 20, which change from moment to moment during operation.

[0083] (2) Flowchart 2 (FIG. 11) When the flow of FIG. 11 starts, the controller 100 first calculates the current attitude of the hydraulic excavator 1 by the attitude calculation unit 111 in step S201, as described above.

[0084] In step S202, the controller 100 calculates the position information of the construction target surface S by the target surface position calculation unit 113 as described above.

[0085] In step S203, the controller 100 acquires an operation signal generated by the operator operating the lever based on an input from the operating lever device 19. The order of steps S201 to S203 can be changed as appropriate.

[0086] When the procedure proceeds to step S204, the controller 100 uses the required movement calculation unit 112 to calculate the required movement direction for each hydraulic actuator of the front work implement 20 in response to the operation of the operator, based on the attitude of the hydraulic excavator 1, the operation signal of the operating lever device 19, etc.

[0087] In the following step S205, the controller 100 calculates the parallelism between the direction of the bucket rotation operation and the construction target surface S using the rotator parallelism calculation unit 118A, as described above.

[0088] When the procedure proceeds to step S206, the controller 100 determines, based on the calculation results of the attitude calculation unit 111 and the target surface position calculation unit 113, whether the tip of the bucket 24 is in the control area where machine control is executed, specifically, whether the distance (for example, the shortest distance) between the tip of the bucket and the construction target surface S is equal to or less than a set distance, using the rotator operation determination unit 118B. In other words, it is determined whether or not to execute the machine control function.

[0089] If the tip of the bucket 24 is outside the control area where machine control is executed, the controller 100 advances the procedure from step S206 to step S207, and sets the rotation operation amount related to machine control by the bucket control unit 117 to 0. Therefore, unless the operator intentionally performs a rotation operation, the bucket 24 does not rotate in the process that goes through step S207.

[0090] If the tip of the bucket 24 is located in a control region where machine control is executed, the controller 100 proceeds from step S206 to step S208, and the rotator operation determination unit 118B determines whether the parallelism calculated in step S205 is equal to or greater than a predetermined threshold. This threshold is a preset value, and is the parallelism set within a range in which the toe of the bucket 24 can be aligned with the construction target surface S by rotation operation alone, so that the work tool angle α does not exceed the above-mentioned allowable angle.

[0091] If the parallelism is equal to or greater than the threshold value, the controller 100 proceeds from step S208 to step S209, and as described above, the rotator operation determination unit 118B calculates the limit amount of the bucket rotation operation in accordance with the allowable angle set for the orientation of the bucket 24.

[0092] In the following step S210, the controller 100 causes the bucket control unit 117 to calculate a target operation amount for the bucket rotation operation within a range that does not exceed the limit amount calculated in step S209. Therefore, the operation amount of the bucket rotation calculated in the process that goes through step S210 is at most the limit amount calculated in step S209. The operation amount of the bucket rotation calculated in step S210 can be set to be limited by the limit amount, or to 0 (i.e., prohibiting the bucket rotation operation), or can be set to be limited by an intermediate value between the limit amount and 0.

[0093] In step S211, the controller 100 calculates the target movement amount of the second actuator (bucket cylinder 24A or tilt cylinder 25A) using the bucket control unit 117 so that the parallel state between the bucket rotation operation and the construction target surface S is eliminated (for example, so that the parallelism between the rotation operation direction and the construction target surface S becomes less than the above-mentioned threshold value) or so that the parallelism becomes lower than it is now.

[0094] If the parallelism is less than the threshold value, the controller 100 proceeds from step S208 to step S212, and the bucket control unit 117 calculates a target rotation movement amount so that the toe of the bucket 24 is aligned with the construction target surface S by the bucket rotation movement. Therefore, in the process that goes through step S212, the attitude of the bucket 24 is controlled by the rotation motor 26A without driving the bucket cylinder 24A or tilt cylinder 25A.

[0095] In step S213, the controller 100 calculates an operation command value for the rotary motor 26A (or the rotary motor 26A and the tilt cylinder 25A or the bucket cylinder 24A) based on the target operation amount calculated by the bucket control unit 117, outputs it to the hydraulic system 15, and controls the attitude of the bucket 24.

[0096] 11, the machine control related to the attitude control of the bucket 24 shown in the same figure is executed in parallel with the machine control of the boom cylinder 22A and the arm cylinder 23A. In the machine control of the boom cylinder 22A and the arm cylinder 23A, the target speeds of the boom cylinder 22A and the arm cylinder 23A calculated by a target speed calculation unit 114 in response to the operation of the operating lever device 19 are corrected as appropriate by a target speed correction unit 115 based on the target plane information, and the boom cylinder 22A and the arm cylinder 23A are driven in accordance with the target speeds.

[0097] The controller 100 repeatedly executes the above procedure while driving the front attachment 20, controlling the attitude of the bucket 24 in real time according to conditions such as the attitude and position of the front attachment 20, which change from moment to moment during operation.

[0098] (3) Flowchart 2 (FIG. 12) When the flow of FIG. 12 starts, the controller 100 first calculates the current attitude of the hydraulic excavator 1 by the attitude calculation unit 111 in step S301, as described above.

[0099] In step S302, the controller 100 calculates the position information of the construction target surface S by the target surface position calculation unit 113 as described above.

[0100] In step S303, the controller 100 acquires an operation signal generated by the operator operating the lever based on an input from the operating lever device 19. The order of steps S301 to S303 can be changed as appropriate.

[0101] When the procedure proceeds to step S304, the controller 100 uses the required movement calculation unit 112 to calculate the required movement direction for each hydraulic actuator of the front work implement 20 in response to the operation of the operator, based on the attitude of the hydraulic excavator 1, the operation signal of the operating lever device 19, etc.

[0102] In the following step S305, the controller 100 calculates the parallelism between the moving direction of the bucket operation and the construction target surface S using the bucket parallelism calculation unit 119A, as described above.

[0103] When the procedure proceeds to step S306, the controller 100 determines, based on the calculation results of the attitude calculation unit 111 and the target surface position calculation unit 113, whether the tip of the bucket 24 is in the control area where machine control is executed, specifically, whether the distance (for example, the shortest distance) between the tip of the bucket and the construction target surface S is equal to or less than a set distance, using the bucket operation determination unit 119B. In other words, it is determined whether or not to execute the machine control function.

[0104] If the tip of the bucket 24 is outside the control area where machine control is executed, the controller 100 moves the procedure from step S306 to step S307, and sets the bucket operation amount related to machine control to 0 by the bucket control unit 117. Therefore, unless the operator is intentionally operating the bucket 24, the bucket 24 does not perform bucket operation in the process that goes through step S307.

[0105] If the tip of the bucket 24 is located in a control area where machine control is executed, the controller 100 proceeds from step S306 to step S308, and the bucket operation determination unit 119B determines whether the parallelism calculated in step S305 is equal to or greater than a predetermined threshold. This threshold is a preset value, and is the parallelism set within a range in which the toe of the bucket 24 can be aligned with the construction target surface S by bucket operation alone, so that the work tool angle α does not exceed the above-mentioned allowable angle.

[0106] If the parallelism is equal to or greater than the threshold value, the controller 100 proceeds from step S308 to step S309, and as described above, the bucket operation determination unit 119B calculates the limit amount of the bucket operation in accordance with the allowable angle set for the orientation of the bucket 24.

[0107] In the following step S310, controller 100 causes bucket control unit 117 to calculate a target operation amount for bucket operation within a range that does not exceed the limit amount calculated in step S309. Therefore, the bucket operation amount calculated in the process that goes through step S310 is at most the limit amount calculated in step S309. The bucket operation amount calculated in step S310 can be set to be limited by the limit amount, can be set to 0 (i.e., bucket operation is prohibited), or can be set to be limited by an intermediate value between the limit amount and 0, for example.

[0108] In step S311, the controller 100 calculates the target operation amount of the second actuator (rotation motor 26A or tilt cylinder 25A) using the bucket control unit 117 so that the parallel state between the bucket operation and the construction target surface S is eliminated (for example, so that the parallelism between the bucket operation direction and the construction target surface S becomes less than the above-mentioned threshold value) or so that the parallelism becomes lower than it is now.

[0109] If the parallelism is less than the threshold value, the controller 100 proceeds from step S308 to step S312, and the bucket control unit 117 calculates a target movement amount for the bucket movement so that the toe of the bucket 24 is aligned with the construction target surface S. Therefore, in the process that goes through step S312, the attitude of the bucket 24 is controlled by the bucket cylinder 24A without driving the rotation motor 26A or tilt cylinder 25A.

[0110] In step S313, the controller 100 calculates an operation command value for the bucket cylinder 24A (or the bucket cylinder 24A and the tilt cylinder 25A or the rotation motor 26A) based on the target operation amount calculated by the bucket control unit 117, outputs the operation command value to the hydraulic system 15, and controls the attitude of the bucket 24.

[0111] Although not shown in the flowchart of Figure 12, the machine control related to the attitude control of the bucket 24 shown in the figure is executed in parallel with the machine control of the boom cylinder 22A and the arm cylinder 23A. In the machine control of the boom cylinder 22A and the arm cylinder 23A, the target speeds of the boom cylinder 22A and the arm cylinder 23A calculated by a target speed calculation unit 114 in response to the operation of the operating lever device 19 are corrected as appropriate by a target speed correction unit 115 based on the target plane information, and the boom cylinder 22A and the arm cylinder 23A are driven in accordance with the target speeds.

[0112] The controller 100 repeatedly executes the above procedure while driving the front attachment 20, controlling the attitude of the bucket 24 in real time according to conditions such as the attitude and position of the front attachment 20, which change from moment to moment during operation.

[0113] Effect As described above, in this embodiment, when the parallelism between the direction of movement of the bucket 24 caused by the work implement actuator, such as the tilt cylinder 25A, and the construction target surface S is equal to or greater than a preset threshold, the movement of the bucket 24 caused by the work implement actuator along the construction target surface S is limited. In other words, when the parallelism is equal to or greater than the threshold and, for example, the tilt cylinder 25A is unable to align the tip of the bucket with the construction work surface S, or when the bucket 24 is aligned but is excessively tilted with respect to the excavation direction D, the movement of the bucket 24 caused by the tilt cylinder 25A is limited. This prevents the bucket 24 from tilting excessively with respect to the excavation direction D against the operator's intention, in other words, prevents the bucket 24 from being displaced by machine control in a way that is unpractical. Because it is possible to prevent the bucket 24 from being displaced in a way that is unpractical, it is possible to prevent situations where the operator has to manually adjust the attitude of the bucket 24, thereby improving operator operability.

[0114] In particular, in this embodiment, a specific allowable angle is set for the work tool angle α, which is the angle of the bucket 24 with respect to the excavation direction D, and when the parallelism is equal to or greater than a threshold value, the amount of movement of the work tool actuator (e.g., the amount of tilt movement) until the work tool angle α reaches the allowable angle is set as a limit amount, and the amount of movement of the bucket 24 by the work tool actuator is limited. In other words, by setting the allowable angle for the work tool angle α that is allowable by the operator, it is possible to prevent the orientation of the bucket 24 from changing beyond the operator's tolerance, and it is possible to rationally reduce the occurrence of occasions where the operator needs to manually adjust the attitude of the bucket 24.

[0115] The hydraulic excavator 1 according to this embodiment also includes multiple implement actuators, such as a bucket cylinder 24A, a tilt cylinder 25A, and a rotation motor 26A. These actuators each operate the bucket 24 in a different direction. For example, if the yaw direction Y in which the tilt cylinder 25A operates the bucket 24 is defined as a first direction, the bucket cylinder 24A or the rotation motor 26A can operate the bucket 24 in a second direction (pitch direction P or roll direction R) different from the first direction. Therefore, for example, if the tilt cylinder 25A is configured to be preferentially driven as the first actuator to change the attitude of the bucket 24, when the parallelism related to the tilt operation direction is equal to or greater than a threshold, the amount of operation of the tilt cylinder 25A can be limited by a limit amount corresponding to the allowable angle, while the bucket cylinder 24A or the rotation motor 26A can be driven to reduce the parallelism. In this way, when it is difficult to properly align the tip of the bucket 24 with the construction target surface S using the first actuator, the second actuator can be driven to reduce the parallelism, allowing the first actuator to control the attitude of the bucket 24. In some cases, it is also possible to drive the second actuator to suitably align the tip of the bucket 24 with the construction target surface S.

[0116] -Modifications- The present invention is not limited to the above-described embodiments and may include various modifications. For example, the present invention is not necessarily limited to configurations that include all of the components described in the above-described embodiments. For example, it is possible to replace some of the components with other components. It is also possible to delete some of the components of the embodiments or add other components.

[0117] For example, the invention has been described as being applied to a hydraulic excavator 1 equipped with a bucket 24 as a working implement, but as mentioned above, the working implement can be replaced with another attachment. Also, the invention has been described as being applied to a hydraulic excavator 1 as an example of an electric construction machine, but the invention can also be applied to other construction machines such as wheel loaders.

[0118] 10 to 12 show an example in which, when the calculated parallelism is equal to or greater than a threshold, the operation of the first actuator is limited (including prohibited), while the second actuator is driven to reduce the parallelism, and when the equilibrium state between the operation direction of the first actuator and the construction target surface S is resolved, the first actuator drives the bucket 24 until the toe becomes parallel to the construction target surface S (e.g., step S108 → step S112). However, this example is not limiting. When the second actuator is driven, the bucket 24 may be driven by the second actuator until the toe becomes parallel to the construction target surface S. Furthermore, even if the parallelism is equal to or greater than a threshold, simply limiting (including prohibiting) the operation of the first actuator without driving the second actuator can be effective in reducing excessive expansion of the work tool angle α and thus the effort required to manually adjust the posture of the bucket 24.

[0119] 1... Hydraulic excavator (work machine), 10... Work machine body, 10S, 12S, 22S-26S... Posture sensor, 19... Operating lever device (operating device), 21... Work device, 24... Bucket (work tool), 24A... Bucket cylinder (work tool actuator), 25A... Tilt cylinder (work tool actuator), 26A... Rotation motor (work tool actuator), 100... Controller, P... Pitch direction (operation direction), R... Roll direction (operation direction), S... Construction target surface, Y... Yaw direction (operation direction), α... Work tool angle

Claims

1. A work machine comprising: a work machine body; a working device rotatably attached to the work machine body and having a plurality of joints; a working tool forming part of the work device and attached to the tip of the work device; a working tool actuator for driving the working tool; an operating device for operating the work device; an operation detection device for detecting an operation signal from the operating device; a plurality of attitude sensors for detecting the attitudes of the work machine body and the work device; and a controller for outputting command signals to control the operation of the work device based on the operation signal of the operating device detected by the operation detection device and the attitudes detected by the plurality of attitude sensors so that the working tool does not excavate beyond a predetermined construction target surface, wherein the working tool actuator includes a first actuator for operating the working tool in a first direction and a second actuator for operating the working tool in a second direction different from the first direction, and the controller calculates the parallelism of the operating direction of the working tool with respect to the construction target surface based on the operation signal detected by the operation detection device and the attitude detected by the attitude sensor, a command signal for driving the first actuator of the work implement actuators to change the attitude of the work implement so that it faces the work target surface when the parallelism is less than a predetermined threshold value; and a command signal for restricting movement of the work implement along the work target surface by the first actuator of the work implement actuators when the parallelism is equal to or greater than the threshold value, and a command signal for driving the second actuator of the work implement actuators.

2. A work machine according to claim 1, wherein the controller stores a preset allowable angle for the work tool angle, which is the angle of the work tool relative to the excavation direction, and when the parallelism is equal to or greater than the threshold value, calculates a limit amount for the amount of movement of the work tool actuator until the work tool angle reaches the allowable angle, and outputs a command signal that limits the amount of movement of the work tool by the work tool actuator using the limit amount.

3. A work machine according to claim 1, wherein the controller stores a preset allowable angle for the work tool angle, which is the angle of the work tool relative to the excavation direction, preferentially drives the first actuator to change the attitude of the work tool, and when the parallelism is equal to or greater than the threshold value, calculates the amount of movement of the first actuator until the work tool angle reaches the allowable angle as a limit amount, and limits the amount of movement of the work tool by the first actuator with the limit amount, while outputting a command signal to drive the second actuator to reduce the parallelism.

4. A work machine according to claim 1, characterized in that the work implement actuator is configured by a plurality of actuators so as to move the work implement in a plurality of directions selected from the pitch direction, yaw direction, and roll direction.

5. A work machine according to claim 1, wherein the implement actuator includes a bucket cylinder, a tilt cylinder, and a rotary motor.

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