Work machine control device, work machine, and work machine control method

Abstract

A technology is provided that can suppress large fluctuations in the manner in which the operating speed of a work device changes depending on the angle of the surface of the work device when a controller controls the alignment of the work device with respect to the work object before work begins. [Solution] The work machine control device 40 is a control device for a work machine 100 that has a machine body and a work implement 3 that is rotatably supported on the machine body, and the work machine control device 40 is equipped with a controller 50 that calculates the intersection P1 between the predicted trajectory PL drawn by a specific part SP of the work implement 3 as the work implement 3 rotates and a target reference line TL that is set to follow the target construction surface S1, and controls the operating speed of the work implement 3 when bringing the specific part SP closer to the intersection P1 based on the difference in elevation between the specific part SP and the intersection P1 or a physical quantity correlated to the difference in elevation.

Description

[Technical Field]

[0001] The present disclosure relates to technology relating to work machines such as excavators. [Background technology]

[0002] Patent Document 1 discloses a method for selecting an automatic operation pattern for a hydraulic excavator. In this automatic operation pattern selection method, a controller calculates the contact angle of the bucket with respect to the excavation plane by inputting a desired excavation angle, and selects automatic plane excavation when the contact angle is greater than a predetermined value, and selects automatic plane rectification when the contact angle is less than the predetermined value. In other words, with the technology in Patent Document 1, the controller automatically determines whether the operator is intending to perform plane excavation or plane rectification based on the relative angle between the bucket and the ground when the operator commands automatic operation, and selects the operation pattern. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 6-39794 Summary of the Invention [Problem to be solved by the invention]

[0004] In order for the controller to cause the work equipment to perform work such as excavation work or leveling work, it is necessary to position a specific part of the work equipment near the work target, such as the ground or a slope, before the work begins. However, Patent Document 1 does not take into consideration the alignment of the work equipment with respect to the work target before the work begins.

[0005] When the controller rotates the working device relative to the machine body to align a specific part of the working device near the work target, it is conceivable that the controller would control the operating speed of the working device according to the distance between the work target and the working device. However, in this case, there is a problem in that the manner in which the operating speed of the working device changes varies greatly depending on the angle of the surface of the work target.

[0006] The present disclosure aims to provide a technology that can suppress large fluctuations in the manner in which the operating speed of a work device changes depending on the angle of the surface of the work device when a controller controls the alignment of the work device with respect to the work device before work begins. [Means for solving the problem]

[0007] A work machine control device according to a first aspect is a control device for a work machine that includes a machine body and a work implement that is rotatably supported on the machine body, and the work machine control device includes a controller that calculates the intersection between a predicted trajectory drawn by a specific part of the work implement as the work implement rotates and a target reference line that is set to follow a target construction surface, and controls the operating speed of the work implement when the specific part approaches the intersection based on the difference in elevation between the specific part and the intersection or a physical quantity that correlates to the difference in elevation.

[0008] In this first aspect, when the work device moves from a start position where it begins operating to a stop position where the specific part reaches the intersection and the work device stops operating, the controller controls the operating speed of the work device when the specific part approaches the intersection based on the elevation difference or a physical quantity correlated to the elevation difference, thereby preventing the manner in which the operating speed of the work device changes when the work device moves from the start position to the stop position from fluctuating greatly depending on the angle of the target construction surface (e.g., the angle of the target construction surface relative to a horizontal plane).

[0009] In this first aspect, the target construction surface is a target surface to be formed by work such as excavation work and ground leveling work.

[0010] A work machine control device according to a second aspect may further include the following configuration in addition to the work machine control device according to the first aspect: That is, in the second aspect, the target reference line may be a straight line parallel to the target construction surface.

[0011] A work machine control device according to a third aspect may be the work machine control device according to the first or second aspect, further including the following configuration. That is, in the third aspect, the target reference line may be a straight line set at a position a predetermined distance away from the target construction surface. The predetermined distance may be set to a size corresponding to the size of an end attachment (e.g., a bucket) of a work implement, for example. In this case, the end attachment can be positioned on or near the target construction surface.

[0012] A work machine control device according to a fourth aspect is preferably the work machine control device according to any one of the first to third aspects, further comprising the following configuration. That is, in the fourth aspect, it is preferable that the controller controls the operating speed so that the operating speed decreases as the difference in elevation decreases. In this fourth aspect, the operating speed of the work device decreases as the specific part of the work device approaches the intersection, so that the operating speed of the work device when the specific part reaches the intersection can be reduced. This makes it easier to relatively accurately position the specific part at or near the intersection.

[0013] A work machine control device according to a fifth aspect is preferably the work machine control device according to any one of the first to fourth aspects, further comprising the following configuration. That is, in the fifth aspect, it is preferable that the controller stops operation of the work device when it is unable to calculate the intersection point between the predicted trajectory and the target reference line. In this fifth aspect, when the controller is unable to calculate the intersection point, it is possible to avoid unnecessary operation of the work device to move the specific portion closer to the intersection point.

[0014] A work machine control device according to a sixth aspect is preferably the work machine control device according to any one of the first to fifth aspects, further comprising the following configuration. That is, in the sixth aspect, it is preferable that the work device includes an end attachment that constitutes the end portion of the work device, the target construction surface is a first target construction surface, the target reference line is a first target reference line, and the controller sets a plurality of target construction surfaces including the first target construction surface, sets a plurality of target reference lines that extend along each of the plurality of target construction surfaces, calculates intersections between the predicted trajectory and the plurality of target reference lines, and determines on which of the plurality of target construction surfaces the end attachment will be placed based on the coordinates of the calculated plurality of intersections. In this sixth aspect, even when a plurality of target construction surfaces exist, the controller can determine on which of the plurality of target construction surfaces the end attachment will be placed.

[0015] A work machine control device according to a seventh aspect is preferably the work machine control device according to any one of the first to sixth aspects, further comprising the following configuration. That is, in the seventh aspect, the work implement includes a boom rotatably supported on the machine body, an arm rotatably supported on the boom, and a bucket rotatably supported on the arm, and the controller calculates a target boom angle change amount, which is a change in the angle of the boom required to move the specific part to the intersection, calculates a target bucket angle value, which is a target value related to the bucket angle and is required to position the bucket at a predetermined relative angle with respect to the target construction surface, using the target boom angle change amount, and changes the attitude of the bucket to an attitude corresponding to the target bucket angle value in control to move the specific part closer to the intersection. In this seventh aspect, it is preferable that the specific part of the work implement can be positioned at or near the intersection, and the bucket can be positioned at the predetermined relative angle with respect to the target construction surface. This allows the controller to immediately start work on a construction target after completing the positioning of the work implement.

[0016] A work machine control device according to an eighth aspect may be the work machine control device according to any one of the first to seventh aspects, further including the following configuration. That is, in the eighth aspect, the work device includes a boom rotatably supported on the machine body, and the controller may calculate a predicted boom angle, which is the angle of the boom when the specific part is moved to the intersection, and control the operating speed of the work device based on an angular difference, which is the difference between the predicted boom angle and an actual boom angle, which is the actual angle of the boom. The angular difference is an example of a physical quantity correlated with the elevation difference. When the controller controls the operating speed of the work device based on the angular difference, the frequency of calculating the coordinates of the specific part can be reduced compared to when the controller controls the operating speed of the work device based on the elevation difference. This reduces the calculation load on the controller.

[0017] A work machine according to a ninth aspect includes the machine main body, the work implement, and the work machine control device according to any one of the first to eighth aspects.

[0018] A work machine control method according to a tenth aspect is a method for a work machine having a machine body and a work implement rotatably supported on the machine body, and includes calculating an intersection between a predicted trajectory drawn by a specific part of the work implement as the work implement rotates and a target reference line that is set to follow a target construction surface, and controlling the operating speed of the work implement when the specific part approaches the intersection based on the elevation difference between the specific part and the intersection or a physical quantity correlated to the elevation difference. [Effects of the Invention]

[0019] According to the present disclosure, a technology is provided that can suppress large fluctuations in the change in the operating speed of a work device depending on the angle of the target construction surface when a controller displaces the work device from an operating start position to an operating stop position. [Brief explanation of the drawings]

[0020] [Figure 1] 1 is a side view showing a work machine equipped with a work machine control device according to an embodiment. [Figure 2] 10A to 10C are diagrams for explaining a target construction surface, a predicted trajectory, a target reference line, and an intersection point. [Figure 3] FIG. 2 is a block diagram illustrating a pilot pump, a control valve, and multiple actuators. [Figure 4] 2 is a block diagram showing the main configuration of the work machine equipped with the work machine control device. FIG. [Figure 5] FIG. 10 is a diagram showing the relationship between the construction surface angle of the target construction surface and the boom lowering speed in a reference example. [Figure 6] FIG. 4 is a diagram showing the relationship between the construction surface angle of the target construction surface and the boom lowering speed in the embodiment. [Figure 7] FIG. 10 is a diagram for explaining a method for determining a target reference line. [Figure 8] 10 is an example of a map showing the relationship between the height difference (or a physical quantity correlated with the height difference) between a specific portion and an intersection point, and the target speed of the boom lowering operation. [Figure 9] 10 is an example of a map showing the relationship between a target speed of a boom lowering operation and a current command value for a proportional valve. [Figure 10] 10 is a diagram for explaining the calculation of a target boom angle change amount, which is the amount of change in the boom angle required to move a specific portion to an intersection point. FIG. [Figure 11] 4 is a flowchart showing an example of a calculation process performed by a controller of the work machine control device. [Figure 12] FIG. 10 is a diagram for explaining a case where no intersection exists. [Figure 13] 10 is a diagram for explaining a case where the speed of the boom lowering operation when the specific portion approaches the intersection is calculated based on a physical quantity that correlates with the difference in elevation between the specific portion and the intersection. FIG. [Figure 14] 10A and 10B are diagrams for explaining a plurality of target construction surfaces in a modified example of the embodiment. [Figure 15] 10 is a flowchart showing an example of calculation processing performed by a controller of a work machine control device according to a modified example. [Figure 16] 10 is an example of a map showing the relationship between the relative speed difference and the target speed of the bucket operation. DETAILED DESCRIPTION OF THE INVENTION

[0021] A work machine control device 40 and a work machine 100 according to an embodiment of the present disclosure will be described with reference to the drawings.

[0022] 1 is a side view showing a work machine 100 equipped with a work machine control device 40 according to an embodiment. This work machine 100 is deployed at a work site and performs various tasks at the work site, such as excavation work and ground leveling work. The work machine 100 according to this embodiment is a shovel.

[0023] The work machine 100 includes a self-propelled lower traveling body 1, an upper rotating body 2 supported on the lower traveling body 1 so as to be rotatable relative to the lower traveling body 1 about a rotation axis CA extending vertically, a work device 3 supported on the upper rotating body 2, and a plurality of actuators. The upper rotating body 2 is an example of a machine body in the present disclosure.

[0024] The lower traveling body 1 includes a pair of left and right crawler traveling devices and a lower frame supported by these crawler traveling devices.

[0025] The upper rotating body 2 includes a rotating frame 2A, a cab 2B, and a rear outer wall 2C. The rotating frame 2A is a frame that is rotatably supported on the lower traveling body 1, and forms a base portion of the upper rotating body 2.

[0026] The cab 2B is disposed, for example, at the left front portion of the revolving frame 2A. Inside the cab 2B, a driver's seat, an operating device 80, and the like (not shown) are disposed.

[0027] The rear outer wall 2C is disposed behind the cab 2B and is an outer wall that defines the machinery room. Various devices are disposed in the machinery room, including power equipment, hydraulic equipment such as a hydraulic pump, and electrical equipment. The power equipment may be an engine, a battery, or a generator. The hydraulic pump is driven by the power equipment. A counterweight is disposed at the rear or behind the rear outer wall 2C. The counterweight is a weight used to balance the work machine 100.

[0028] The work device 3 includes a boom 4 supported on the upper rotating body 2 so as to be able to be raised or lowered, an arm 5 rotatably supported on the boom 4, and a bucket 6 rotatably supported on the arm 5. The boom 4 has a boom base end 4a which is the base end of the boom 4 rotatably attached to the upper rotating body 2, and a boom tip end which is the tip end of the boom 4. The arm 5 has an arm base end which is the base end of the arm 5 rotatably attached to the boom tip end, and an arm tip end 5a which is the tip end of the arm 5. The bucket 6 has a bucket base end which is the base end of the bucket 6 rotatably attached to the arm tip end 5a, and a bucket tip end 6a which is the tip end of the bucket 6. The bucket 6 is an example of a tip attachment. The tip attachment is not limited to the bucket 6 and may be other devices such as a fork, a grapple, or a lifting magnet.

[0029] In the drawings, the fore-and-aft direction is a direction based on the orientation of the upper rotating body 2. Specifically, the front is the horizontal direction in which the work implement 3 extends from the boom base end 4a in a plan view of the work machine 100 seen from directly above. The rear is the opposite direction to the front. The left-right direction is a horizontal direction perpendicular to the fore-and-aft direction.

[0030] Each of the multiple actuators operates by receiving a supply of hydraulic oil discharged from the hydraulic pump. The multiple actuators include a boom cylinder 7 for raising and lowering the boom 4, an arm cylinder 8 for rotating the arm 5, a bucket cylinder 9 for rotating the bucket 6, a swing motor 11 for rotating the upper swing structure 2 relative to the lower traveling structure 1, and left and right traveling motors 12 and 13 for traveling the lower traveling structure 1.

[0031] The work machine 100 is equipped with an operation device 80, an input receiver 20 (construction surface information input device), an attitude information detector 30, and a control valve 70.

[0032] The operation device 80 includes a plurality of operation levers that are operated by the operator. Operations by the operator include a boom operation for raising and lowering the boom 4, an arm operation for rotating the arm 5, a bucket operation for rotating the bucket 6, a swing operation for swinging the upper rotating structure 2 relative to the undercarriage 1, and a travel operation for traveling the undercarriage 1. The operation device 80 is disposed inside the cab 2B of the work machine 100.

[0033] The operating device 80 may include a remote control valve that outputs a pilot pressure corresponding to the operation of the operating lever to a pilot port of a control valve 70 (described later), and a pressure sensor (not shown) that detects the pilot pressure. The detection result by the pressure sensor is input to the controller 50. The operating device 80 may also include a sensor that detects the operation of the operating lever, and may be configured to input an operation command signal corresponding to the detected operation to the controller 50.

[0034] The input receiver 20 may be configured to receive input for setting a target construction surface. The target construction surface is a target surface of a construction object such as the ground or a slope at a work site, and is a target surface to be formed by work such as excavation work or ground leveling work by the work machine 100.

[0035] The input acceptor 20 may be configured to accept construction surface information, which is information related to the construction object. The input acceptor 20 may include a user interface, such as a keyboard, a mouse, or a display, for an operator to input the construction surface information. In this case, the operator inputs the construction surface information to the input acceptor 20, and the input acceptor 20 inputs the input construction surface information to the controller 50.

[0036] The construction surface information may include information about the target construction surface. The construction surface information may include construction surface position information, which is information about the position of the target construction surface, and construction surface angle information, which is information about the angle of the target construction surface.

[0037] The construction surface position information may include three-dimensional position information that is three-dimensional position information about the target construction surface, or may include two-dimensional position information that is two-dimensional position information about the target construction surface.

[0038] The three-dimensional position information may include, for example, coordinate information for identifying the target construction surface in a predetermined three-dimensional Cartesian coordinate system. In this case, the three-dimensional Cartesian coordinate system may be represented by an x-axis, a y-axis, and a z-axis, with a predetermined origin O as the reference. The x-axis may be an axis that passes through the origin O and is parallel to the front-to-back direction. The y-axis may be an axis that passes through the origin O and is parallel to the left-to-right direction. The z-axis may be an axis that passes through the origin O and is parallel to the up-down direction.

[0039] The two-dimensional position information may include, for example, coordinate information for identifying the target construction surface in a predetermined two-dimensional Cartesian coordinate system. In this case, the two-dimensional Cartesian coordinate system may be expressed by an x-axis and a z-axis, with a predetermined origin O as the reference. The x-axis may be an axis that passes through the origin O and is parallel to the front-to-back direction. The z-axis may be an axis that passes through the origin O and is parallel to the up-to-down direction.

[0040] In the specific example shown in Fig. 2, the construction surface position information includes two-dimensional position information of the target construction surface S1 in a two-dimensional Cartesian coordinate system. The origin O of the two-dimensional Cartesian coordinate system is set to a predetermined location. In the specific example shown in Fig. 2, the predetermined location is set to the boom base end 4a (boom foot pin). However, the predetermined location may be set to a location other than the boom base end 4a (for example, any point on the rotation axis CA).

[0041] The construction surface position information may include coordinates (Xzero, Zzero) of a reference point RP1, which is a point that serves as a reference for the target construction surface S1 in the two-dimensional orthogonal coordinate system. The reference point RP1 may be a point on the target construction surface S1 that corresponds to a position that is closest to the upper rotating body 2 of the work machine 100 in the two-dimensional orthogonal coordinate system.

[0042] The construction surface position information may include the coordinates of an end point EP1, which is a point for specifying the range of the target construction surface S1. The end point EP1 may be a point on the target construction surface S1 that corresponds to a position farthest from the upper rotating body 2 of the work machine 100 in the two-dimensional orthogonal coordinate system.

[0043] In addition, with the bucket tip 6a positioned at reference point RP1, which is the reference point of the target construction surface S1, the operator may make a predetermined input to the input receiver 20 (for example, by pressing a predetermined button), and the controller 50 may set the position of the bucket tip 6a at the time the predetermined input was made as the coordinates of the reference point RP1 of the target construction surface S1.

[0044] The construction plane angle information may include information on a construction plane angle θslp, which is the angle of the target construction plane S1, as shown in Fig. 2. The construction plane angle θslp may be, for example, the angle of the target construction plane S1 with respect to a horizontal plane.

[0045] In this embodiment, as shown in Fig. 2, the target construction surface S1 is specified as a straight line that passes through the reference point RP1 in the two-dimensional orthogonal coordinate system and whose angle with respect to the horizontal plane is a construction surface angle θslp. Specifically, when the construction surface angle θslp is a positive value greater than zero, the target construction surface S1 is specified as a straight line that is positioned upward as it moves forward from the reference point RP1 in the two-dimensional orthogonal coordinate system, as shown in the specific example shown in Fig. 2. When the construction surface angle θslp is zero, the target construction surface S1 is specified as a horizontal line extending forward from the reference point RP1 in the two-dimensional orthogonal coordinate system. When the construction surface angle θslp is a negative value less than zero, the target construction surface S1 is specified as a straight line that is positioned downward as it moves forward from the reference point RP1 in the two-dimensional orthogonal coordinate system.

[0046] The attitude information detector 30 acquires attitude information, which is information relating to the attitude of the work machine 100. The attitude information detector 30 may include a plurality of attitude sensors. As shown in FIG. 1 , the plurality of attitude sensors may include a boom attitude sensor 31, an arm attitude sensor 32, a bucket attitude sensor 33, and a rotating bed attitude sensor 34.

[0047] The boom attitude sensor 31 may be a sensor that detects the attitude of the boom 4, or may be a sensor that detects the state of the boom cylinder 7 that correlates with the attitude of the boom 4. The arm attitude sensor 32 may be a sensor that detects the attitude of the arm 5, or may be a sensor that detects the state of the arm cylinder 8 that correlates with the attitude of the arm 5. The bucket attitude sensor 33 may be a sensor that detects the attitude of the bucket 6, or may be a sensor that detects the state of the bucket cylinder 9 that correlates with the attitude of the bucket 6. The rotating structure attitude sensor 34 may be a sensor that detects the attitude of the upper rotating structure 2, or may be a sensor that detects the state of the swing motor 11 that correlates with the attitude of the upper rotating structure 2.

[0048] Each of the plurality of attitude sensors may include, for example, an inertial measurement unit (IMU), a sensor that detects the degree of extension / contraction of a cylinder (e.g., a stroke sensor), or other sensors. The rotating body attitude sensor 34 may include a sensor such as a rotary encoder, resolver, or potentiometer that detects the rotation angle of the upper rotating body 2 relative to the undercarriage 1, or a sensor that detects the tilt angle of the upper rotating body 2 relative to the horizontal plane.

[0049] The attitude information detector 30 inputs the acquired attitude information to the controller 50 of the work machine control device 40. The controller 50 can calculate the attitude of the work machine 100 using the attitude information input to it from the attitude information detector 30. Specifically, the controller 50 can calculate the attitude of the boom 4, the attitude of the arm 5, the attitude of the bucket 6, and the attitude of the upper rotating body 2 based on the attitude information. The controller 50 may represent at least one of the attitude of the boom 4, the attitude of the arm 5, the attitude of the bucket 6, and the attitude of the upper rotating body 2 using coordinates in the two-dimensional orthogonal coordinate system or the three-dimensional orthogonal coordinate system based on the attitude information.

[0050] The control valve 70 may be configured to adjust the direction and flow rate of the hydraulic oil supplied to at least one of the plurality of actuators in accordance with the operation received by the operating device 80. As shown in Fig. 3 , the control valve 70 includes a boom direction switching valve 71, an arm direction switching valve 72, a bucket direction switching valve 73, a swing direction switching valve 74, a right travel direction switching valve 75, a left travel direction switching valve 76, and a plurality of proportional valves 77.

[0051] The boom direction switching valve 71 adjusts the direction and flow rate of hydraulic oil supplied to the boom cylinder 7. The arm direction switching valve 72 adjusts the direction and flow rate of hydraulic oil supplied to the arm cylinder 8. The bucket direction switching valve 73 adjusts the direction and flow rate of hydraulic oil supplied to the bucket cylinder 9. The swing direction switching valve 74 adjusts the direction and flow rate of hydraulic oil supplied to the swing motor 11. The right travel direction switching valve 75 adjusts the direction and flow rate of hydraulic oil supplied to the right travel motor 12 of the right crawler travelling device. The left travel direction switching valve 76 adjusts the direction and flow rate of hydraulic oil supplied to the left travel motor 13 of the left crawler travelling device.

[0052] Each of the boom direction switching valve 71, the arm direction switching valve 72, the bucket direction switching valve 73, the swing direction switching valve 74, the right-side travel direction switching valve 75, and the left-side travel direction switching valve 76 has a pair of pilot ports and a spool that displaces in response to the pilot pressure supplied to the pilot port.

[0053] The work machine 100 is configured so that the multiple actuators operate in response to operations on the control device 80 by the operator. In this case, when the control device 80 is operated by the operator, the pilot pressure output from the proportional valve 77 in response to that operation is supplied to the pilot port of the directional control valve corresponding to that operation. The directional control valve is configured to adjust the direction and flow rate of hydraulic oil supplied to the actuators by displacing a spool in response to the pilot pressure input to that pilot port. In this way, the actuator corresponding to the operation received by the control device 80 operates.

[0054] Each of the plurality of proportional valves 77 may be configured, for example, by an electromagnetic proportional pressure reducing valve. The plurality of proportional valves 77 includes a pair of boom proportional valves 77, a pair of arm proportional valves 77, a pair of bucket proportional valves 77, a pair of swing proportional valves 77, a pair of right-side traveling proportional valves 77, and a pair of left-side traveling proportional valves 77.

[0055] Each of the plurality of proportional valves 77 is disposed in an oil passage between a pilot pump 78 for generating a pilot pressure and a pilot port of a directional control valve corresponding to that proportional valve 77. Each of the plurality of proportional valves 77 is configured to reduce the pilot pressure in accordance with a control command (current command value) input from the controller 50, and to output the reduced pilot pressure to the pilot port. Therefore, the controller 50 can cause the actuator to operate in accordance with the current command value input to the proportional valve 77.

[0056] Specifically, the controller 50 can adjust the speed of the boom lowering operation of the boom 4 by changing the magnitude of the current command value input to one of the pair of boom proportional valves 77, which is for causing the boom 4 to perform a boom lowering operation. The controller 50 can adjust the speed of the boom raising operation of the boom 4 by changing the magnitude of the current command value input to one of the pair of boom proportional valves 77, which is for causing the boom 4 to perform a boom raising operation. The boom lowering operation is an operation in which the boom 4 rotates about the boom base end 4a, thereby moving the boom tip in a direction toward the ground. The boom raising operation is an operation in which the boom 4 rotates about the boom base end 4a, thereby moving the boom tip in a direction away from the ground.

[0057] The controller 50 can adjust the speed of the bucket pulling operation of the bucket 6 by changing the magnitude of the current command value input to one of the pair of bucket proportional valves 77 that causes the bucket 6 to perform a bucket pulling operation. The controller 50 can adjust the speed of the bucket pushing operation of the bucket 6 by changing the magnitude of the current command value input to one of the pair of bucket proportional valves 77 that causes the bucket 6 to perform a bucket pushing operation. The bucket pulling operation is an operation in which the bucket 6 rotates about the bucket base end, causing the bucket tip 6a to move in a direction approaching the upper rotating body 2. The bucket pushing operation is an operation in which the bucket 6 rotates about the bucket base end, causing the bucket tip 6a to move in a direction away from the upper rotating body 2.

[0058] Furthermore, the work machine 100 is configured to operate automatically based on commands from the controller 50, even if the operator does not operate the control device 80. In other words, even if the operator does not operate the control device 80, the controller 50 can cause the actuator to perform an operation in accordance with a current command value input to the proportional valve 77. Specifically, for example, the controller 50 can adjust the speed of the boom lowering operation of the boom 4 by changing the magnitude of the current command value input to the boom proportional valve 77, of the pair of boom proportional valves 77, which is for causing the boom 4 to perform a boom lowering operation.

[0059] In this embodiment, the controller 50 performs automatic operation control to cause the working device 3 to perform work such as excavation work and ground leveling work. The controller 50 also performs positioning control, which is automatic operation control (assist control) to position a specific portion SP of the working device 3 near a construction target such as the ground or a slope before the work begins. This positioning control is automatic control by the controller 50, and is automatic return control that moves the bucket 6, which is located above and away from the construction target, closer to the construction target by causing the boom 4 to perform a boom lowering operation. The positioning control by the controller 50 will be described in detail below.

[0060] The display device 91 shown in FIG. 4 displays information necessary for the operator. The display device 91 may be, for example, a display. Examples of the display include a liquid crystal display, an organic EL display, a head-up display, and a head-mounted display. The display device 91 may be located, for example, inside the cab 2B. In this case, the display device 91 displays the information by being controlled by the controller 50. The display device 91 may be located at a location remote from the work machine 100. When the display device 91 is located at a location remote from the work machine 100, the controller 50 is configured to be able to transmit information to the display device 91, and the display device 91 is configured to receive the information transmitted from the controller 50 and display the information.

[0061] The work machine 100 is equipped with a work machine control device 40. The work machine control device 40 is equipped with a controller 50. The controller 50 is equipped with a computer including an arithmetic processing unit and a memory.

[0062] The work machine control device 40 according to this embodiment can prevent the manner in which the operating speed of the work device 3 changes from fluctuating significantly depending on the angle of the surface of the work object when the controller 50 controls the positioning of the work device 3 relative to the work object before work begins.

[0063] The effects obtained by this embodiment will be explained by comparing it with a reference example. Figure 5 is a diagram showing the relationship between the construction surface angle of the target construction surface and the boom lowering speed in the reference example. Figure 6 is a diagram showing the relationship between the construction surface angle of the target construction surface and the boom lowering speed in this embodiment.

[0064] 5, the controller calculates the intersection P1 between the predicted trajectory PL drawn by the arm tip 5a serving as the specific portion SP of the work machine 100 and a target reference line TL that is set along the target construction surface S1, and controls the boom lowering speed when the specific portion SP approaches the intersection P1 based on the difference in elevation between the specific portion SP and the target reference line TL. In this reference example, the manner in which the boom lowering speed changes varies greatly depending on the angle of the target construction surface S1.

[0065] Specifically, the upper diagram (A) in Figure 5 shows a case where the target construction surface S1 is a horizontal plane and the angle of the target construction surface S1 is zero. The center diagram (B) in Figure 5 shows a case where the angle of the target construction surface S1 is a positive value greater than zero. The lower diagram (C) in Figure 5 shows a case where the angle of the target construction surface S1 is a negative value less than zero.

[0066] When the angle of the target construction surface S1 is zero, as shown in the upper diagram (A) of Figure 5, the difference in elevation between the specific portion SP and the target reference line TL gradually decreases as the boom lowering operation progresses, and the speed of the boom lowering operation (boom lowering speed) also gradually decreases, as shown in the graph on the right.

[0067] When the angle of the target construction surface S1 is a positive value as shown in the center diagram (B) of Figure 5, the rate at which the difference in elevation between the specific part SP and the target reference line TL decreases as the boom lowering operation progresses is higher than when the angle of the target construction surface S1 is zero. Therefore, as shown in the graph on the right, the degree of deceleration of the boom lowering speed is higher than when the angle of the target construction surface S1 is zero.

[0068] When the angle of the target construction surface S1 is a negative value, as shown in the lower diagram (C) of Figure 5, the rate at which the difference in elevation between the specific portion SP and the target reference line TL decreases as the boom lowering operation progresses is slower than when the angle of the target construction surface S1 is zero. Moreover, in the case of the lower diagram (C) of Figure 5, the rate at which the difference in elevation decreases increases rapidly when the specific portion SP reaches the vicinity of the intersection point P1. Therefore, as shown in the graph on the right, the degree of deceleration of the boom lowering speed is gradual in the early and middle stages, but increases rapidly in the final stages. As described above, in the reference example, the manner in which the speed of the boom lowering operation changes varies greatly depending on the construction surface angle of the target construction surface S1.

[0069] On the other hand, in the work machine control device 40 according to this embodiment, the controller 50 calculates the intersection P1 between the predicted trajectory PL traced by the specific portion SP and the target reference line TL set along the target construction surface S1, and controls the speed of the boom lowering operation when the specific portion SP approaches the intersection P1 based on the elevation difference ΔZ between the specific portion SP and the intersection P1 or a physical quantity correlated to the elevation difference ΔZ. This makes it possible to prevent the manner in which the speed of the boom lowering operation changes when the work implement 3 moves from the start position of the boom lowering operation to the stop position of the boom lowering operation from fluctuating greatly depending on the angle of the target construction surface S1, as shown in the upper diagram (A), center diagram (B), and lower diagram (C) of Figure 6. The work machine control device 40 according to this embodiment will be described in detail below.

[0070] 4, the controller 50 includes a target construction surface setting unit 51, a trajectory calculation unit 52, an intersection calculation unit 53, a speed calculation unit 54, a standby necessity determination unit 55, an operation control unit 56, and a position determination unit 57. The functions of the target construction surface setting unit 51, the trajectory calculation unit 52, the intersection calculation unit 53, the speed calculation unit 54, the standby necessity determination unit 55, the operation control unit 56, and the position determination unit 57 are realized by the arithmetic processing device executing a control program stored in the memory.

[0071] The target construction surface setting unit 51 sets the target construction surface S1. The target construction surface setting unit 51 may set the position of the target construction surface S1 and the construction surface angle θslp based on the construction surface information input from the input receiver 20 to the controller 50. Furthermore, as described above, the target construction surface setting unit 51 may set the position of the bucket tip 6a at the time when the predetermined input is made to the input receiver 20 as the coordinates of the reference point RP1 of the target construction surface S1.

[0072] Specifically, the target construction surface S1 is expressed by the following equation (1) using a linear equation in the two-dimensional orthogonal coordinate system.

[0073] Z=aX+b (1)

[0074] The gradient "a" of the straight line in the above formula (1) is expressed by the following formula (2) using the construction surface angle θslp.

[0075] a = tan(θslp) (2)

[0076] Furthermore, since the target construction surface S1 includes the reference point RP1, the coefficient "b" in equation (1) is expressed by the following equation (3) using the coordinates (Xzero, Zzero) of the reference point RP1 and equation (2).

[0077] b=Zzero-Xzero×tan(θslp) ···(3)

[0078] The trajectory calculation unit 52 calculates a predicted trajectory PL, which is a trajectory predicted to be traced by the specific part SP of the working implement 3. The trajectory calculation unit 52 may calculate the predicted trajectory PL to be traced by the specific part SP when the boom 4 performs a boom lowering operation, on the premise that the posture of the arm 5 relative to the boom 4 does not change. In this embodiment, the specific part SP is set to the arm tip 5a (arm top).

[0079] Specifically, the trajectory calculation unit 52 may calculate the predicted trajectory PL of the specific part SP in the two-dimensional orthogonal coordinate system using the attitude information input to the controller 50 from the attitude information detector 30 and specification information of the work machine 100. The specification information includes information on the dimensions of the boom 4 and the arm 5. The specification information may further include information on the dimensions of the bucket 6. The controller 50 stores the specification information.

[0080] Based on the posture information input to the controller 50 from the posture information detector 30, the controller 50 can calculate the position of the arm tip 5a serving as the specific part SP at that time, i.e., the coordinates (Xnow, Znow) of the specific part SP in the two-dimensional orthogonal coordinate system. If the posture of the arm 5 relative to the boom 4 does not change when the boom 4 performs a boom-lowering operation, the distance R from the origin O to the specific part SP in the two-dimensional orthogonal coordinate system is constant, as shown in FIG. 2. In this case, the predicted trajectory PL of the specific part SP when the boom 4 performs a boom-lowering operation is an arc with a radius R centered at the boom base end 4a (origin O), as shown by the two-dot chain line in FIG. 2. Therefore, the predicted trajectory PL drawn by the arm tip 5a serving as the specific part SP when the boom 4 performs a boom-lowering operation as shown in FIG. 2 is expressed by the following equation (4) using the equation of a circle.

[0081] X 2 +Z 2 =R 2 ···(4)

[0082] "X" and "Z" in the above formula (4) are the coordinates (X, Z) of the specific part SP in the two-dimensional orthogonal coordinate system when the boom 4 performs the boom lowering operation.

[0083] In this embodiment, in the positioning control by the controller 50, the controller 50 does not change the attitude of the arm 5 relative to the boom 4 when causing the boom 4 to perform a boom lowering operation. Therefore, the controller 50 can calculate the distance R (radius R) using the coordinates (Xnow, Znow) of the specific part SP at that time and the following equation (5).

[0084] R=√((Xnow) 2 +(Znow) 2 ) ···(5)

[0085] The intersection calculation unit 53 first sets a target reference line TL along the target construction surface S1. In this embodiment, the intersection calculation unit 53 sets the target reference line TL at a position in the two-dimensional orthogonal coordinate system, as shown in FIG. 2, that is a predetermined distance H upward (in the direction of the z-axis) from the target construction surface S1. In this embodiment, the target reference line TL is a straight line parallel to the target construction surface S1. The predetermined distance H may be set to a value corresponding to the size of the bucket 6, for example. In this case, when the arm tip 5a serving as the specific part SP moves to the intersection point P1 based on a command from the operation control unit 56, which will be described later, the bucket 6 is positioned on or near the target construction surface S1.

[0086] The target reference line TL is a target on which the arm tip 5a serving as the specific part SP should be placed. The target reference line TL is expressed by the following equation (6) using the equation of a straight line in the two-dimensional orthogonal coordinate system.

[0087] Z=aX+b+H (6)

[0088] An example of a method for determining the distance H in the above formula (6) will be described with reference to Fig. 7. The specific example shown in Fig. 7 assumes that the bottom surface 6b of the bucket 6 is placed along the target construction surface S1.

[0089] As shown in FIG. 7, the bucket 6 has an opening between the bucket tip 6a and the arm tip 5a (bucket base end), and the bucket tip 6a is one of the four edges that define this opening, and is, for example, the portion having multiple claws. Of the four edges that define the opening, the bucket 6 has a pair of left and right lateral edges 6c (a left edge 6c located on the left side and a right edge 6c located on the right side). Each of the pair of lateral edges 6c extends from the bucket tip 6a toward the arm tip 5a (bucket base end). The bucket 6 has a bottom surface 6b. The angle of the bottom surface 6b with respect to the lateral edge 6c is θbkt. The bottom surface 6b extends from the bucket tip 6a in a direction that forms an angle θbkt with respect to the lateral edge 6c.

[0090] If the distance from the arm tip 5a to the bottom surface 6b of the bucket 6 is "H'" and the length of the lateral edge 6c is "Lbkt", the distance H is expressed by the following equation (7).

[0091] H=H' / cos(θslp) =(Lbkt×sin(θbkt)) / cos(θslp) ···(7)

[0092] As described above, the predicted trajectory PL drawn by the specific part SP during the boom lowering operation is expressed by equation (4), and the target reference line TL is expressed by equation (6). Therefore, the intersection calculation unit 53 can calculate the coordinates (Xgoal, Zgoal) in the two-dimensional orthogonal coordinate system of the intersection P1 between the predicted trajectory PL drawn by the specific part SP during the boom lowering operation and the target reference line TL, using equations (4) and (6).

[0093] The speed calculation unit 54 calculates the speed of the boom lowering operation of the boom 4 when the specific part SP approaches the intersection point P1 based on the elevation difference ΔZ between the specific part SP and the intersection point P1, i.e., the difference between the Z coordinate (Znow) of the specific part SP and the Z coordinate (Zgoal) of the intersection point P1. In this embodiment, the speed calculation unit 54 calculates the speed of the boom lowering operation so that the speed of the boom lowering operation decreases as the elevation difference ΔZ decreases. In this case, the speed of the boom lowering operation decreases as the arm tip 5a, which serves as the specific part SP, approaches the intersection point P1, so the speed of the boom lowering operation when the specific part SP reaches the intersection point P1 can be reduced. This makes it easier to position the specific part SP relatively accurately at or near the intersection point P1.

[0094] FIG. 8 is an example of a map showing the relationship between the elevation difference ΔZ between the specific portion SP and the intersection point P1 and the target speed of the boom lowering operation. FIG. 9 is an example of a map showing the relationship between the target speed of the boom lowering operation and the current command value for the proportional valve 77. The speed calculation unit 54 may previously store a calculation formula corresponding to the map shown in FIG. 8 and a calculation formula corresponding to the map shown in FIG. 9. In this case, the speed calculation unit 54 calculates the actual elevation difference ΔZ (ΔZ = Znow - Zgoal) between the specific portion SP and the intersection point P1, and calculates the target speed of the boom lowering operation based on the calculated elevation difference ΔZ and the calculation formula corresponding to the map shown in FIG. 8. Then, the speed calculation unit 54 calculates the current command value to be input to the proportional valve 77 based on the calculated target speed of the boom lowering operation and the calculation formula corresponding to the map shown in FIG. 9.

[0095] As shown in Fig. 10, the speed calculation unit 54 preferably calculates a target boom angle change amount Δθboom, which is the amount of change in the angle of the boom 4 required to move the specific site SP to the intersection point P1, and uses the target boom angle change amount Δθboom to calculate a target bucket angle value, which is a target value related to the angle of the bucket 6 and is required to position the bucket 6 at a predetermined relative angle with respect to the target construction surface S1. The predetermined relative angle is the target value of the bucket ground angle θbs, which will be described later. In this embodiment, the predetermined relative angle is set to "0 degrees."

[0096] The speed calculation unit 54 may calculate the target boom angle change amount Δθboom using, for example, the coordinates of the specific part SP at the start of the alignment control, the coordinates (Xgoal, Zgoal) of the intersection point P1, and the distance R (radius R).

[0097] In this embodiment, the bucket angle target value is a target bucket relative angle θbat. The target bucket relative angle θbat is a target value of the bucket relative angle θba. The bucket relative angle θba is the relative angle of the bucket 6 with respect to the arm 5. Specifically, as shown in FIG. 10 , for example, the bucket relative angle θba may be the angle between a line passing through the arm base end and the arm tip end 5a and the bottom surface 6b of the bucket 6.

[0098] In this embodiment, the speed calculation unit 54 calculates the target bucket relative angle θbat required to position the bottom surface 6b of the bucket 6 parallel to the target construction surface S1. The operation control unit 56, which will be described later, changes the posture of the bucket 6 in the alignment control for moving the specific site SP closer to the intersection point P1 so that the relative angle difference Δθba, which is the difference between the bucket relative angle θba and the target bucket relative angle θbat, becomes zero. In this case, not only can the arm tip 5a serving as the specific site SP be positioned at or near the intersection point P1, but the bottom surface 6b of the bucket 6 can also be positioned parallel to the target construction surface S1 (the predetermined relative angle = 0 degrees). This allows the controller 50 to immediately start leveling work on the construction target after completing the alignment of the working implement 3.

[0099] The speed calculation unit 54 can calculate the target bucket relative angle θbat using, for example, the following equation (8).

[0100] Target bucket relative angle θbat=(bucket relative angle θba at the start of control)−(bucket ground angle θbs at the start of control)+(boom angle target change amount Δθboom) (8)

[0101] In equation (8), "control start time" refers to the start time of alignment control. The bucket ground angle θbs is the relative angle of the bucket 6 with respect to the target construction surface S1. Specifically, as shown in FIG. 10, for example, the bucket ground angle θbs may be the angle between the target construction surface S1 and the bottom surface 6b of the bucket 6. The speed calculation unit 54 can calculate the bucket ground angle θbs using the construction surface angle θslp, the attitude information input to the controller 50 from the attitude information detector 30, and the specification information.

[0102] The standby necessity determination unit 55 determines whether the relative angle difference Δθba is greater than a predetermined threshold. If the relative angle difference Δθba is greater than the predetermined threshold, the operation control unit 56 may set the speed of the boom lowering operation to zero, that is, may stop the boom lowering operation, until the bucket 6 rotates and the relative angle difference Δθba becomes equal to or less than the predetermined threshold.

[0103] The operation control unit 56 controls the operation of the working implement 3 based on the operating speed of the working implement 3 calculated by the speed calculation unit 54. Specifically, the operation control unit 56 inputs the current command value calculated by the speed calculation unit 54 to one of the pair of boom proportional valves 77, the proportional valve 77 that corresponds to the boom lowering operation. This causes the proportional valve 77 to output a secondary pressure corresponding to the current command value as a pilot pressure, and the output pilot pressure is supplied to one pilot port of the boom direction switching valve 71. As a result, the boom direction switching valve 71 adjusts the flow rate of hydraulic oil supplied to the rod-side chamber of the boom cylinder 7, so that the boom cylinder 7 retracts at a speed corresponding to the current command value, and the boom 4 performs a boom lowering operation at a speed corresponding to the current command value.

[0104] Furthermore, the operation control unit 56 changes the attitude of the bucket 6 so that the relative angle difference Δθba becomes zero during the positioning control for bringing the specific portion SP closer to the intersection point P1.

[0105] The position determination unit 57 determines whether or not the specific portion SP has reached the intersection point P1. If the specific portion SP has reached the intersection point P1, the controller 50 ends control for aligning the work implement 3 with the work target.

[0106] Next, an example of alignment control performed by the controller 50 will be described with reference to Fig. 11. The alignment control shown in Fig. 11 may be started, for example, by an operator or other worker performing an input operation (for example, a button operation) to start the alignment control.

[0107] In step S101, the controller 50 sets a target construction surface S1 and a target reference line TL, and calculates a predicted trajectory PL of the specific portion SP. Then, the controller 50 calculates the coordinates (Xgoal, Zgoal) in the two-dimensional orthogonal coordinate system of an intersection P1 between the predicted trajectory PL drawn by the specific portion SP and the target reference line TL during the boom lowering operation, using equations (4) and (6).

[0108] In step S102, the controller 50 determines whether or not an intersection point P1 exists, i.e., whether or not the intersection point P1 between the predicted trajectory PL and the target reference line TL can be calculated. Fig. 2 shows a case where the intersection point P1 exists, i.e., a case where the intersection point P1 can be calculated, and Fig. 12 shows a case where the intersection point P1 does not exist, i.e., a case where the intersection point P1 cannot be calculated.

[0109] 12, if work machine 100 is too far away from target reference line TL, there is no intersection P1 between the predicted trajectory PL traced by specific part SP and target reference line TL, and controller 50 is unable to calculate intersection P1. In this case (NO in step S102), controller 50 sets the target speed for operation of boom 4 to zero, and also sets the target speed for operation of bucket 6 to zero (step S109). In this case, boom 4 and bucket 6 do not operate and are stopped.

[0110] If the intersection point P1 exists and the controller 50 has been able to calculate the intersection point P1 (YES in step S102), the controller 50 performs the process of step S103.

[0111] In step S103, the controller 50 calculates the target boom angle change amount Δθboom required to move the specific portion SP to the intersection point P1, as shown in FIG.

[0112] Next, in step S104, controller 50 calculates a target bucket relative angle θbat using the bucket relative angle θba at the start of control, the bucket ground angle θbs at the start of control, and the target boom angle change amount Δθboom. Also in step S104, controller 50 calculates a relative angle difference Δθba, which is the difference between the bucket relative angle θba and the target bucket relative angle θbat. Also in step S104, controller 50 calculates a target speed for the movement of the bucket 6 when the relative angle difference Δθba approaches zero in positioning control.

[0113] FIG. 16 is an example of a map showing the relationship between the relative angular difference Δθba and the target speed of the operation of the bucket 6. The controller 50 can calculate the target speed of the operation of the bucket 6 using the relative angular difference Δθba at that time and a calculation formula corresponding to the map shown in FIG. 16. The target speed of the operation of the bucket 6 may be a target value for the rotation speed of the bucket 6 with respect to the arm 5, or may be a target value for the operation speed (extension / contraction speed) of the bucket cylinder 9. By using the map shown in FIG. 16, the controller 50 can calculate the target speed such that the operation speed of the bucket 6 decreases as the relative angular difference Δθba decreases. The controller 50 may previously store a map showing the relationship between the target speed of the operation of the bucket 6 and a current command value for the bucket proportional valve 77. In this case, the controller 50 calculates a current command value to be input to the bucket proportional valve 77 based on the calculated target speed of the operation of the bucket 6 and a calculation formula corresponding to the map (not shown).

[0114] Next, in step S105, the controller 50 calculates the target speed of the boom lowering operation of the boom 4 when bringing the specific portion SP closer to the intersection point P1 based on the elevation difference ΔZ between the specific portion SP and the intersection point P1, i.e., the difference between the Z coordinate (Znow) of the specific portion SP and the Z coordinate (Zgoal) of the intersection point P1.

[0115] In step S105, the controller 50 may calculate a target speed for the boom lowering operation of the boom 4 when the specific part SP approaches the intersection point P1 based on a physical quantity correlated with the elevation difference ΔZ between the specific part SP and the intersection point P1. Specifically, as shown in FIG. 13 , the controller 50 may calculate a predicted boom angle θgoal, which is the angle of the boom when the specific part SP is moved to the intersection point P1, and control the speed of the boom lowering operation of the boom 4 based on an angle difference Δθ, which is the difference between the predicted boom angle θgoal and the actual boom angle θnow, which is the actual angle of the boom 4. The angle difference Δθ is an example of a physical quantity correlated with the elevation difference ΔZ. When the controller 50 controls the speed of the boom lowering operation based on the angle difference Δθ, the frequency of calculating the coordinates of the specific part SP can be reduced compared to when the controller 50 controls the speed of the boom lowering operation based on the elevation difference ΔZ. This reduces the calculation load on the controller 50.

[0116] The controller 50 calculates the target speed of the boom lowering operation so that the speed of the boom lowering operation decreases as the angular difference Δθ decreases. In this case, the speed of the boom lowering operation decreases as the arm tip 5a serving as the specific part SP approaches the intersection point P1, so the speed of the boom lowering operation when the specific part SP reaches the intersection point P1 can be reduced. This makes it easier to position the specific part SP relatively accurately at or near the intersection point P1.

[0117] The controller 50 may store in advance a calculation formula corresponding to the map shown in Fig. 8 and a calculation formula corresponding to the map shown in Fig. 9. In this case, the controller 50 calculates an angle difference Δθ (θnow - θgoal) which is the difference between the actual boom angle θnow and the predicted boom angle θgoal, and calculates a target speed for the boom lowering operation based on the calculated angle difference Δθ and the calculation formula corresponding to the map shown in Fig. 8. Then, the controller 50 calculates a current command value to be input to the boom proportional valve 77 based on the calculated target speed for the boom lowering operation and the calculation formula corresponding to the map shown in Fig. 9.

[0118] Next, in step S106, controller 50 determines whether relative angle difference Δθba is greater than a predetermined threshold value. If relative angle difference Δθba is greater than the predetermined threshold value (YES in step S106), controller 50 reduces the speed of the boom lowering operation to zero, that is, stops the boom lowering operation, until the attitude of bucket 6 with respect to arm 5 changes and relative angle difference Δθba becomes equal to or less than the predetermined threshold value (step S110).

[0119] If the relative angular difference Δθba is equal to or smaller than the predetermined threshold value (NO in step S106), the controller 50 performs the process of step S107.

[0120] In step S107, the controller 50 inputs the current command value corresponding to the target speed for the boom lowering operation calculated in step S105 to the proportional valve 77 corresponding to the boom lowering operation of the pair of boom proportional valves 77. As a result, the boom cylinder 7 contracts at a speed according to the current command value, and the boom 4 performs the boom lowering operation at a speed according to the current command value.

[0121] Furthermore, in step S107, controller 50 inputs a current command value corresponding to the target speed of the movement of the bucket 6 calculated in step S104 to one of the pair of bucket proportional valves 77. This bucket proportional valve 77 is a proportional valve corresponding to the movement direction required to position the bottom surface 6b of the bucket 6 parallel to the target construction surface S1. As a result, bucket cylinder 9 extends or retracts at a speed corresponding to the current command value, and the bucket 6 moves at a speed corresponding to the current command value.

[0122] In step S108, the controller 50 determines whether the specific part SP has reached the intersection point P1 or whether the actual boom angle θnow has reached the predicted boom angle θgoal. If the specific part SP has reached the intersection point P1 or if the actual boom angle θnow has reached the predicted boom angle θgoal (YES in step S108), the controller 50 ends the alignment control for aligning the work implement 3 with the construction target. If the specific part SP has not reached the intersection point P1 or if the actual boom angle θnow has not reached the predicted boom angle θgoal (NO in step S108), the controller 50 performs the processing from step S104 onwards. Note that the controller 50 may determine whether the specific part SP has reached the intersection point P1 by determining whether the Z coordinate of the specific part SP matches the Z coordinate of the intersection point P1.

[0123] [Variations] FIG. 14 is a diagram for explaining a plurality of target construction surfaces S1, S2, and S3 in a modified example of the embodiment.

[0124] In this modification, the controller 50 sets multiple target construction surfaces, sets multiple target reference lines that respectively extend along the multiple target construction surfaces, calculates the intersections between the predicted trajectory PL and the multiple target reference lines, and determines on which of the multiple target construction surfaces the bucket 6 will be placed based on the coordinates of the calculated multiple intersections. In this modification, even when multiple target construction surfaces exist, the controller 50 can appropriately determine on which of the multiple target construction surfaces the bucket 6 will be placed.

[0125] 14, the multiple target construction surfaces include a first target construction surface S1, a second target construction surface S2, and a third target construction surface S3. The multiple target reference lines include a first target reference line TL1 set to align with the first target construction surface S1, a second target reference line TL2 set to align with the second target construction surface S2, and a third target reference line TL3 set to align with the third target construction surface S3.

[0126] The first target construction surface S1, the second target construction surface S2, and the third target construction surface S3 are set to be arranged in this order. The first target construction surface S1 is set to the position closest to the work machine 100, and the third target construction surface S3 is set to the position farthest from the work machine 100. The construction surface angle θslp of the first target construction surface S1 and the construction surface angle θslp of the second target construction surface S2 are different from each other, and the construction surface angle θslp of the second target construction surface S2 and the construction surface angle θslp of the third target construction surface S3 are different from each other.

[0127] The operator inputs construction surface information for the first target construction surface S1, the second target construction surface S2, and the third target construction surface S3 to the input receiver 20, and the input receiver 20 inputs the input construction surface information to the controller 50. The construction surface information includes construction surface position information, which is information about the respective positions of the first target construction surface S1, the second target construction surface S2, and the third target construction surface S3, and construction surface angle information, which is information about the respective angles of the first target construction surface S1, the second target construction surface S2, and the third target construction surface S3.

[0128] The construction surface position information includes the coordinates of a first reference point RP1, which is a reference point for the first target construction surface S1 in the two-dimensional Cartesian coordinate system; the coordinates of a second reference point RP2, which is a reference point for the second target construction surface S2 in the two-dimensional Cartesian coordinate system; and the coordinates of a third reference point RP3, which is a reference point for the third target construction surface S3 in the two-dimensional Cartesian coordinate system (see FIG. 14). The first reference point RP1 is a point on the first target construction surface S1 that corresponds to a position closest to the upper rotating body 2 of the work machine 100 in the two-dimensional Cartesian coordinate system. The second reference point RP2 is a point on the second target construction surface S2 that corresponds to a position closest to the upper rotating body 2 of the work machine 100 in the two-dimensional Cartesian coordinate system. The third reference point RP3 is a point on the third target construction surface S3 that corresponds to a position closest to the upper rotating body 2 of the work machine 100 in the two-dimensional Cartesian coordinate system.

[0129] The construction surface position information may include the coordinates of a first end point EP1, which is a point for specifying the range of the first target construction surface S1, the coordinates of a second end point EP2, which is a point for specifying the range of the second target construction surface S2, and the coordinates of a third end point EP3, which is a point for specifying the range of the third target construction surface S3. The first end point EP1 is a point on the first target construction surface S1 that corresponds to a position farthest from the upper rotating body 2 of the work machine 100 in the two-dimensional Cartesian coordinate system, and may be the same position as the second reference point RP2. The second end point EP2 is a point on the second target construction surface S2 that corresponds to a position farthest from the upper rotating body 2 of the work machine 100 in the two-dimensional Cartesian coordinate system, and may be the same position as the third reference point RP3. The third end point EP3 is a point on the third target construction surface S3 that corresponds to a position farthest from the upper rotating body 2 of the work machine 100 in the two-dimensional Cartesian coordinate system.

[0130] Using a method similar to that of the above embodiment, the controller 50 can set multiple target construction surfaces S1, S2, S3, set multiple target reference lines TL1, TL2, TL3, calculate a predicted trajectory PL, calculate a first intersection P1 which is the intersection of the predicted trajectory PL and the first target reference line TL1, calculate a second intersection P2 which is the intersection of the predicted trajectory PL and the second target reference line TL2, and calculate a third intersection P3 which is the intersection of the predicted trajectory PL and the third target reference line TL3.

[0131] FIG. 15 is a flowchart showing an example of target height calculation control performed by the controller 50 of the work machine control device 40 according to the modified example.

[0132] In step S201 of FIG. 15, the controller 50 calculates a first intersection P1 between the predicted trajectory PL and the first target reference line TL1.

[0133] Next, in step S202, the controller 50 determines whether the first intersection point P1 is located within a first area corresponding to the first target construction surface S1. The first area may be identified, for example, using the range of the X coordinate of the first target construction surface S1. The range of the X coordinate of the first target construction surface S1 is the range from the X coordinate of the first reference point RP1 to the X coordinate of the first end point EP1.

[0134] If the X coordinate of the first intersection P1 is within the range of the X coordinate of the first target construction surface S1, i.e., if the first intersection P1 exists in the first area (YES in step S202), the controller 50 performs the process of step S203. On the other hand, if the X coordinate of the first intersection P1 is not within the range of the X coordinate of the first target construction surface S1, i.e., if the first intersection P1 does not exist in the first area (NO in step S202), the controller 50 performs the process of step S204.

[0135] In step S203, the controller 50 sets the target coordinates of the arm tip 5a as the specific part SP to a first intersection P1 between the predicted trajectory PL and the first target reference line TL1. The controller 50 may set the Z coordinate of the first intersection P1 as the target height of the specific part SP. After the processing of step S203, the controller 50 ends the target height calculation control.

[0136] In step S204, the controller 50 calculates a second intersection P2 between the predicted trajectory PL and the second target reference line TL2.

[0137] Next, in step S205, the controller 50 determines whether the second intersection point P2 is located within a second area corresponding to the second target construction surface S2. The second area may be identified, for example, using the range of the X coordinate of the second target construction surface S2. The range of the X coordinate of the second target construction surface S2 is the range from the X coordinate of the second reference point RP2 to the X coordinate of the second end point EP2.

[0138] If the X coordinate of the second intersection P2 is within the range of the X coordinate of the second target construction surface S2, i.e., if the second intersection P2 exists in the second area (YES in step S205), the controller 50 performs the process of step S206. On the other hand, if the X coordinate of the second intersection P2 is not within the range of the X coordinate of the second target construction surface S2, i.e., if the second intersection P2 does not exist in the second area (NO in step S205), the controller 50 performs the process of step S207.

[0139] In step S206, the controller 50 sets the target coordinate of the arm tip 5a as the specific part SP to a second intersection P2 between the predicted trajectory PL and the second target reference line TL2. The controller 50 may set the Z coordinate of the second intersection P2 as the target height of the specific part SP. After processing in step S206, the controller 50 ends the target height calculation control.

[0140] In step S207, the controller 50 calculates a third intersection P3 between the predicted trajectory PL and the third target reference line TL3.

[0141] Next, in step S208, the controller 50 sets the target coordinates of the arm tip 5a as the specific part SP to a third intersection P3 between the predicted trajectory PL and the third target reference line TL3. The controller 50 may set the Z coordinate of the third intersection P3 as the target height of the specific part SP. After the processing of step S208, the controller 50 ends the target height calculation control.

[0142] [Other variations] Although the embodiments and modifications of the present disclosure have been described above, the present disclosure is not limited to the above-described embodiments and further includes modifications such as those described below.

[0143] (A) Work machine control devices In the embodiment described above, the work machine control device 40 is provided on the work machine 100, but the work machine control device in the present disclosure does not necessarily have to be provided on the work machine 100, and may be located at a location remote from the work machine. In this case, the work machine control device is configured to be able to send and receive information between the work machine control device and the work machine via a network such as the Internet or a mobile phone network.

[0144] (B) Specific parts In the above embodiment, the specific part SP of the working device 3 is set at the arm tip 5a, but in the present disclosure, the specific part of the working device may be set at a part other than the arm tip 5a (for example, the bucket tip 6a).

[0145] (C) Bucket angle target value In the above embodiment, the bucket angle target value is the target bucket relative angle θbat, but the bucket angle target value in the present disclosure may be, for example, a bucket angle target change amount. The bucket angle target change amount is a target value required to position the bucket 6 at a predetermined relative angle with respect to the target construction surface S1, and is a target value for the change amount in the angle of the bucket 6. Specifically, for example, the bucket angle target change amount is the difference between the angle of the bucket 6 at the start of alignment control and the target value of the angle of the bucket 6 at the end of alignment control. In other words, the bucket angle target change amount is the difference between the bucket relative angle θba at the start of alignment control and the target bucket relative angle θbat.

[0146] In this case, the speed calculation unit 54 of the controller 50 calculates the target bucket angle change amount required to position the bottom surface 6b of the bucket 6 parallel to the target construction surface S1, and the operation control unit 56 of the controller 50 changes the attitude of the bucket 6 by the target bucket angle change amount in positioning control to bring the specific site SP closer to the intersection P1. In this case, not only can the arm tip 5a serving as the specific site SP be positioned at or near the intersection P1, but the bottom surface 6b of the bucket 6 can also be positioned parallel to the target construction surface S1 (the predetermined relative angle = 0 degrees). This allows the controller 50 to immediately start leveling work on the construction target after completing the positioning of the work implement 3. [Explanation of symbols]

[0147] 1: Lower running body 2: Upper rotating body 3: Work equipment 4: Boom 4a: Boom base end 5: Arm 5a: Arm tip 6: Bucket 6b: Bottom 20: Input acceptor 30: Attitude information detector 40: Work machine control device 50: Controller 70: Control valve 77: Proportional valve 80: Operating device 100: Work machines P1: Intersection P2: Intersection P3: Intersection PL: Predicted trajectory S1: Target construction surface S2: Target construction surface S3: Target construction surface SP:Specific part TL:Target reference line TL1: Target reference line TL2: Target baseline TL3:Target reference line ΔZ: Height difference Δθboom: Target change in boom angle Δθ: angle difference θba: Bucket relative angle (relative angle of the bucket to the arm) θbat: Target bucket relative angle θbs: Bucket angle to the ground

Claims

1. A work machine control device for a work machine including a machine body and a work device rotatably supported on the machine body, A work machine control device comprising a controller that calculates the intersection between a predicted trajectory drawn by a specific part of the work device as the work device rotates and a target reference line that is set to follow a target construction surface, and controls the operating speed of the work device when the specific part is brought closer to the intersection based on the elevation difference between the specific part and the intersection or a physical quantity that correlates to the elevation difference.

2. The work machine control device according to claim 1 , wherein the target reference line is a straight line parallel to the target construction surface.

3. The work machine control device according to claim 1 , wherein the target reference line is a straight line set at a position a predetermined distance away from the target construction surface.

4. The work machine control device according to claim 1 , wherein the controller controls the movement speed so that the movement speed decreases as the difference in elevation decreases.

5. The work machine control device according to claim 1 , wherein the controller stops operation of the work device when the intersection point between the predicted trajectory and the target reference line cannot be calculated.

6. the working device includes a tip attachment that constitutes a tip portion of the working device, The target construction surface is a first target construction surface, the target reference line is a first target reference line, 2. The work machine control device according to claim 1, wherein the controller sets a plurality of target construction surfaces including the first target construction surface, sets a plurality of target reference lines along each of the plurality of target construction surfaces, calculates intersections between the predicted trajectory and the plurality of target reference lines, and determines on which of the plurality of target construction surfaces the end attachment will be placed based on the coordinates of the calculated plurality of intersections.

7. the working device includes a boom rotatably supported on the machine body, an arm rotatably supported on the boom, and a bucket rotatably supported on the arm, 2. The work machine control device according to claim 1, wherein the controller calculates a target boom angle change amount, which is a change amount in the angle of the boom required to move the specific portion to the intersection, calculates a target bucket angle value, which is a target value related to the angle of the bucket and is required to position the bucket at a predetermined relative angle with respect to the target construction surface, using the target boom angle change amount, and changes the attitude of the bucket to an attitude corresponding to the target bucket angle value in control to move the specific portion closer to the intersection.

8. the working device includes a boom rotatably supported on the machine body, 2. The work machine control device according to claim 1, wherein the controller calculates a predicted boom angle, which is the angle of the boom when the specific part is moved to the intersection, and controls the operating speed of the work device based on an angle difference, which is the difference between the predicted boom angle and an actual boom angle, which is the actual angle of the boom.

9. The machine body; The working device; A work machine comprising: a work machine control device according to any one of claims 1 to 8.

10. A work machine control method for a work machine including a machine body and a work implement rotatably supported on the machine body, comprising: Calculating an intersection between a predicted trajectory drawn by a specific portion of the working device as the working device rotates and a target reference line set along a target construction surface; and controlling the operating speed of the work device when the specific portion is brought closer to the intersection based on the difference in elevation between the specific portion and the intersection or a physical quantity correlated to the difference in elevation.

Images