Working machinery

Abstract

To ensure postural stability of a working machinery by taking into consideration the effect of cliff-like terrain on postural stability of a working machinery.SOLUTION: A working machinery 1 comprises: a posture detection device 53 that detects a tilt angle of the working machinery 1 and a rotation angle of a slewing upper structure 7; a surrounding detection device 54 that detects surrounding terrain; and a control device 40 that controls the working machinery 1. The control device 40 has: a cliff determination portion 44 that determines whether or not a bench edge 212 exists around the working machinery 1 based on the detection results of the surrounding detection device 54; a centroid calculation portion 45 that calculates the centroid position of the working machinery 1 based on the detection results of the posture detection device 53; and a stabilization support portion 46 that supports posture stabilization of the working machinery 1. When a distance between the bench edge 212 and the centroid position is less than a threshold value, the stabilization support portion 46 causes the alarm device 56 to issue an alarm as posture stabilization support, or restricts an operator's operation that cause the centroid position to approach the bench edge 212.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a work machine. [Background technology]

[0002] A known work machine includes an upper rotating body rotatably attached to a lower traveling body, and an articulated working device rotatably attached to the upper rotating body. The working device has a boom rotatably attached to the upper rotating body, an arm rotatably attached to the boom, and a bucket rotatably attached to the arm.

[0003] Patent Document 1 describes a technology that estimates the volume of soil to be lifted using a bucket and evaluates the attitude stability of a work machine based on the estimated volume of soil and the attitudes of the upper rotating body, boom, arm, and bucket. Patent Document 1 also mentions obtaining information about the terrain to estimate the volume of soil to be lifted by the bucket. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2022-154674 Summary of the Invention [Problem to be solved by the invention]

[0005] The postural stability of a work machine is affected by the terrain around the work machine. For example, if there is cliff-like terrain around the work machine and the work machine tilts down the cliff, the postural stability of the work machine is likely to decrease. Patent Document 1 describes estimating the volume of soil in the bucket from the terrain and evaluating the postural stability, but does not mention the effect of cliff-like terrain on postural stability.

[0006] The present invention has been made in view of the above, and has as its object to ensure the postural stability of a work machine by taking into consideration the effect that cliff-like terrain has on the postural stability of the work machine. [Means for solving the problem]

[0007] In order to solve the above problem, the work machine of the present invention is a work machine comprising a lower running body and an upper rotating body rotatably provided relative to the lower running body, and is equipped with an attitude detection device that detects the tilt angle of the work machine and the rotating angle of the upper rotating body, a surroundings detection device that detects the terrain around the work machine, and a control device that controls the work machine, wherein the control device has a cliff determination unit that determines whether a cliff edge is present around the work machine based on the detection result of the surroundings detection device, a center of gravity calculation unit that calculates the center of gravity position of the work machine based on the detection result of the attitude detection device, and a stabilization support unit that supports the attitude stabilization of the work machine, and is characterized in that when the distance between the cliff edge determined by the cliff determination unit and the center of gravity position calculated by the center of gravity calculation unit is equal to or less than a predetermined threshold, the stabilization support unit causes an alarm device of the work machine to issue an alarm, or restricts operation of the operator when the center of gravity position approaches the cliff edge, as support for the attitude stabilization. [Effects of the Invention]

[0008] According to the present invention, the postural stability of a work machine can be ensured by taking into consideration the effect that cliff-like terrain has on the postural stability of the work machine. Other problems, components, and advantages will become apparent from the following description of the embodiments. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. [Figure 2] FIG. 2 is a diagram illustrating a state in which a work machine works at a work site. [Figure 3] FIG. 2 is a diagram illustrating the configuration of a hydraulic system mounted on the work machine. [Figure 4]FIG. 2 is a block diagram illustrating the functional configuration of a control device according to the first embodiment. [Figure 5] FIG. 5 is a diagram showing a reference coordinate system set in the control device shown in FIG. 4. [Figure 6] FIG. 6 is a view of the reference coordinate system shown in FIG. 5 from another direction. [Figure 7] FIG. 6 is a view of the reference coordinate system shown in FIG. 5 from another direction. [Figure 8] 5 is a flowchart showing a process related to posture stabilization assistance performed by the control device shown in FIG. [Figure 9] FIG. 10 is a rear view of the work machine illustrating the state in which the work machine is tilted in the roll direction. [Figure 10] FIG. 4 is a side view of the work machine illustrating the state in which the work machine is tilted in the pitch direction. [Figure 11] FIG. 10 is a top view of the work machine illustrating the state during a swing operation when the center of gravity is located on the front work implement side. [Figure 12] 5 is a diagram showing an example of an alarm issued by the alarm device shown in FIG. 4. [Figure 13] FIG. 10 is a block diagram illustrating the functional configuration of a control device according to a second embodiment. [Figure 14] 14 is a flowchart showing a process related to posture stabilization assistance performed by the control device shown in FIG. 13. [Figure 15] 14 is a diagram showing an example of an alarm issued by the alarm device shown in FIG. 13. [Figure 16] FIG. 10 is a block diagram illustrating the functional configuration of a control device according to a third embodiment. [Figure 17] 17 is a diagram showing the relationship between the threshold value changed by the stabilization support unit shown in FIG. 16 and soil information. [Figure 18] FIG. 10 is a diagram illustrating a remote control device for operating a work machine according to a fourth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that components with the same reference numerals in each embodiment have similar components in each embodiment unless otherwise specified, and description thereof will be omitted.

[0011] In this embodiment, the work machine 1 is exemplified as a hydraulic excavator equipped with a bucket 10 as a working implement (attachment) at the tip of a working mechanism (front working mechanism 2). The work machine 1 may also be equipped with an attachment other than the bucket 10. The work machine 1 may be any work machine other than a hydraulic excavator, as long as it has an articulated work mechanism configured by connecting multiple members (a boom 8, an arm 9, an attachment, etc.) on top of a rotatable structure (an upper rotating body 7).

[0012] [First embodiment] A work machine 1 of a first embodiment will be described using Figures 1 to 12. Figure 1 is a side view of the work machine 1. Figure 2 is a diagram illustrating how the work machine 1 works at a work site.

[0013] The work machine 1 performs an excavation operation to excavate the ground to be excavated, and a loading operation to load the excavated material, such as earth and sand, onto a loaded machine 200, such as a transport machine including a dump truck. The work machine 1 is equipped with a multi-joint front work implement 2 that holds the excavated material and rotates up and down or back and forth, and a machine main body 3 on which the front work implement 2 is mounted.

[0014] The machine body 3 includes a lower traveling body 5 that travels using a right traveling hydraulic motor 4a and a left traveling hydraulic motor 4b provided on the right and left parts of the lower traveling body 5, and an upper rotating body 7 that is attached to the upper part of the lower traveling body 5 via a rotating device and rotates using a swing hydraulic motor 6 of the swing device. In this embodiment, the right traveling hydraulic motor 4a and the left traveling hydraulic motor 4b are also collectively referred to as traveling hydraulic motors 4. The lower traveling body 5 includes a right crawler 21a and a left crawler 21b that are paired on the left and right sides. In this embodiment, the right crawler 21a and the left crawler 21b are also collectively referred to as crawlers 21.

[0015] The front working mechanism 2 is an articulated working mechanism made up of multiple front members attached to the front of the upper rotating body 7. The front working mechanism 2 includes a boom 8 connected to the front of the upper rotating body 7 so as to be rotatable in the vertical direction, an arm 9 connected to the tip of the boom 8 so as to be rotatable in the vertical direction, and a bucket 10 connected to the tip of the arm 9 so as to be rotatable in the vertical direction.

[0016] The boom 8 is connected to the upper rotating body 7 by a boom pin 8a, and rotates by the extension and retraction of a boom cylinder 11. The arm 9 is connected to the tip of the boom 8 by an arm pin 9a, and rotates by the extension and retraction of an arm cylinder 12. The bucket 10 is connected to the tip of the arm 9 by a bucket pin 10a and a bucket link 16, and rotates by the extension and retraction of a bucket cylinder 13.

[0017] A boom angle sensor 14 is attached to the boom pin 8a, which detects the rotation angle of the boom 8 relative to the machine body 3 (i.e., the upper rotating body 7). An arm angle sensor 15 is attached to the arm pin 9a, which detects the rotation angle of the arm 9 relative to the boom 8. A bucket angle sensor 17 is attached to the bucket link 16, which detects the rotation angle of the bucket 10 relative to the arm 9.

[0018] The rotation angles of the boom 8, arm 9, and bucket 10 may be obtained by detecting the angles of the boom 8, arm 9, and bucket 10 relative to a reference plane such as a horizontal plane using an inertial measurement unit (IMU) and converting them into rotation angles.The rotation angles of the boom 8, arm 9, and bucket 10 may also be obtained by detecting the strokes of the boom cylinder 11, arm cylinder 12, and bucket cylinder 13 using a stroke sensor and converting them into rotation angles.

[0019] An inclination angle sensor 18 is attached to the upper rotating body 7 to detect the inclination angle of the machine body 3 with respect to a reference plane such as a horizontal plane. A swing angle sensor 19 is attached to the swing device between the lower traveling body 5 and the upper rotating body 7 to detect the swing angle of the upper rotating body 7 with respect to the lower traveling body 5.

[0020] The boom angle sensor 14, arm angle sensor 15, bucket angle sensor 17, tilt angle sensor 18, and swing angle sensor 19 constitute an attitude detection device 53 that detects the tilt angle of the machine body 3, the rotation angles of the front working implement 2, the swing angle of the upper swing body 7, etc.

[0021] An operating device for operating the multiple hydraulic actuators 4, 6, 11, 12, and 13 is installed in the operator's cab 71 provided on the upper rotating body 7. Specifically, the operating device includes a right travel lever 23a for operating the right travel hydraulic motor 4a, a left travel lever 23b for operating the left travel hydraulic motor 4b, a right operating lever 22a for operating the boom cylinder 11 and the bucket cylinder 13, and a left operating lever 22b for operating the arm cylinder 12 and the swing hydraulic motor 6. In this embodiment, the right travel lever 23a, the left travel lever 23b, the right operating lever 22a, and the left operating lever 22b are also collectively referred to as operating levers 22 and 23. For example, electric lever-type operating levers may be used as the operating levers 22 and 23. The operating levers 22 and 23 include switches that can specify whether control is enabled or disabled.

[0022] Furthermore, a surroundings detection device 54 that detects the type and position of objects present around the work machine 1, as well as the terrain, is attached to the upper rotating body 7, for example, above the operator's cab 71. The surroundings detection device 54 may be, for example, a LiDAR (Light Detection And Ranging) or a stereo camera.

[0023] FIG. 2 shows the work machine 1 mining ore or the like in an open-cut mine or the like, as an example of how the work machine 1 works at a work site. In FIG. 2, the height of the ground 220 on which the loaded machine 200 is located is referred to as ground level. The terrain on which the work machine 1 is located and which is also the target of excavation is referred to as bench 210. An upper surface 211 of the bench 210 on which the work machine 1 is located is at a higher position with a height difference of a predetermined value or more relative to the ground level of the ground 220 on which the loaded machine 200 is located. The bench 210 includes the upper surface 211 on which the work machine 1 is located, a bench edge 212 which is the edge of the bench 210 (upper surface 211), and a slope 213 which is a surface connecting the bench edge 212 and the ground 220. The bench edge 212 and slope 213 form a cliff-like terrain. The bench edge 212 and slope 213 are an example of a cliff. Bench edge 212 is an example of a cliff edge.

[0024] The surroundings detection device 54 detects the terrain around the work machine 1. The surrounding terrain includes at least the terrain of the bench 210. Multiple surroundings detection devices 54 may be attached to the work machine 1. The surroundings detection device 54 may acquire information about the terrain detected by a terrain detection device installed at the work site via a communication device.

[0025] FIG. 3 is a diagram illustrating the configuration of a hydraulic system mounted on the work machine 1. As shown in FIG.

[0026] An engine 103, which is a prime mover mounted on the upper rotating structure 7, drives a main hydraulic pump 102 and a pilot pump 104. The control device 40 controls the rotational movement of the front working implement 2, the traveling movement of the undercarriage 5, and the swinging movement of the upper rotating structure 7 in accordance with operation information (amount and direction of operation) of the control levers 22, 23 by the operator. Specifically, the control device 40 detects operation information of the control levers 22, 23 by the operator using sensors 52a-52f such as rotary encoders or potentiometers, and outputs control commands in accordance with the detected operation information to the electromagnetic proportional valves 51a-51l. The electromagnetic proportional valves 51a-51l are provided in a pilot line 100, and are activated when a control command is input from the control device 40, outputting pilot pressure to a flow control valve 101 to operate the flow control valve 101. In this embodiment, the sensors 52a to 52f that detect operation information of the operating levers 22, 23 by the operator are also collectively referred to as an operation detection device 52.

[0027] The flow control valve 101 controls the pressurized oil supplied from the hydraulic pump 102 to each of the swing hydraulic motor 6, the arm cylinder 12, the boom cylinder 11, the bucket cylinder 13, the right traveling hydraulic motor 4a, and the left traveling hydraulic motor 4b, in accordance with the pilot pressures from the electromagnetic proportional valves 51a to 51l. The electromagnetic proportional valves 51a and 51b output pilot pressures for controlling the pressurized oil supplied to the swing hydraulic motor 6 to the flow control valve 101. The electromagnetic proportional valves 51c and 51d output pilot pressures for controlling the pressurized oil supplied to the arm cylinder 12 to the flow control valve 101. The electromagnetic proportional valves 51e and 51f output pilot pressures for controlling the pressurized oil supplied to the boom cylinder 11 to the flow control valve 101. The electromagnetic proportional valves 51g and 51h output pilot pressures for controlling the pressurized oil supplied to the bucket cylinder 13 to the flow control valve 101. The electromagnetic proportional valves 51i and 51j output pilot pressures for controlling the pressure oil supplied to the right traveling hydraulic motor 4a to the flow control valve 101. The electromagnetic proportional valves 51k and 51l output pilot pressures for controlling the pressure oil supplied to the left traveling hydraulic motor 4b to the flow control valve 101.

[0028] The boom cylinder 11, arm cylinder 12, and bucket cylinder 13 each extend and retract using the supplied pressure oil, rotating the boom 8, arm 9, and bucket 10, respectively. This changes the position and attitude of the bucket 10. The swing hydraulic motor 6 rotates using the supplied pressure oil, rotating the upper swing structure 7. The right traveling hydraulic motor 4a and the left traveling hydraulic motor 4b rotate using the supplied pressure oil, causing the lower traveling structure 5 to travel. Note that even when the operator has not operated the operation levers 22, 23, the hydraulic actuators 4, 6, 11, 12, and 13 can be driven by operating the electromagnetic proportional valves 51a to 51l and the flow control valve 101 using a control command from the control device 40.

[0029] Fig. 4 is a block diagram illustrating the functional configuration of the control device 40 of the first embodiment. Fig. 5 is a diagram illustrating a reference coordinate system set in the control device 40 shown in Fig. 4. Fig. 6 is a diagram illustrating the reference coordinate system shown in Fig. 5 viewed from another direction. Fig. 7 is a diagram illustrating the reference coordinate system shown in Fig. 5 viewed from another direction.

[0030] Although not shown, the control device 40 is configured by a computer in which a CPU (Central Processing Unit), RAM (Random Access Memory), ROM (Read Only Memory), an external I / F (Interface), etc. are connected to one another via a bus. An electromagnetic proportional valve 51, an operation detection device 52, an attitude detection device 53, a surrounding detection device 54, a weight acquisition device 55, an alarm device 56, and a storage device (for example, a hard disk drive or a large-capacity flash memory) are connected to the external I / F of the control device 40.

[0031] The weight acquisition device 55 is a device that acquires the weight of the excavated material excavated by the excavation operation and held in the bucket 10. The weight acquisition device 55 is configured by a known weight acquisition device. The notification device 56 is a device that notifies the operator of information from the control device 40. The notification device 56 is configured by, for example, a display. The notification device 56 may be configured to include a speaker.

[0032] A reference coordinate system that specifies the positions and attitudes of the components of the work machine 1 is set in advance in the control device 40. The reference coordinate system in this embodiment is defined as a right-handed coordinate system with the origin O being the point on the turning central axis where the undercarriage 5 contacts the ground G, as shown in Figs. 5 to 7. In the reference coordinate system, the forward direction of the undercarriage 5 is defined as the positive direction of the X-axis. In the reference coordinate system, the direction in which the turning central axis extends upward is defined as the positive direction of the Z-axis. In the left-right directions of the undercarriage 5 that are orthogonal to each of the X-axis and Z-axis, the left side is defined as the positive direction of the Y-axis. In addition, in the reference coordinate system, the tilt angle in the fore-and-aft direction of the work machine 1 with respect to the direction of gravity is defined as the pitch angle, and the tilt angle in the left-right direction is defined as the roll angle.

[0033] In the reference coordinate system of this embodiment, the rotation angle of the upper rotating structure 7 is defined as 0 degrees when the front working implement 2 is parallel to the X-axis. When the rotation angle of the upper rotating structure 7 is 0 degrees, the operating plane of the front working implement 2 is parallel to the XZ plane, the direction of the lifting operation of the boom 8 is the positive direction of the Z-axis, and the direction of the dumping operation of the arm 9 and bucket 10 is the positive direction of the X-axis.

[0034] The control device 40 has a topography calculation unit 41, an attitude calculation unit 42, a movement direction calculation unit 43, a cliff determination unit 44, a center of gravity calculation unit 45, and a stabilization support unit 46.

[0035] The attitude calculation unit 42 calculates the attitudes and the like of the components of the work machine 1 in the reference coordinate system based on the detection results of the attitude detection device 53. Specifically, the attitude calculation unit 42 calculates the rotation angle θbm of the boom 8 with respect to the X-axis from the detection signal of the rotation angle of the boom 8 output from the boom angle sensor 14. The attitude calculation unit 42 calculates the rotation angle θam of the arm 9 with respect to the boom 8 from the detection signal of the rotation angle of the arm 9 output from the arm angle sensor 15. The attitude calculation unit 42 calculates the rotation angle θbk of the bucket 10 with respect to the arm 9 from the detection signal of the rotation angle of the bucket 10 output from the bucket angle sensor 17. The attitude calculation unit 42 calculates the swing angle θsw of the upper swing structure 7 with respect to the X-axis (undercarriage 5) from the detection signal of the swing angle of the upper swing structure 7 output from the swing angle sensor 19.

[0036] Furthermore, the posture calculation unit 42 calculates the planar positions and heights of the boom 8, arm 9, and bucket 10 based on the calculated rotation angles θbm, θam, θbk of the front working implement 2 and the swing angle θsw of the upper swing structure 7, as well as the dimension Lbm of the boom 8, the dimension La of the arm 9, and the dimension Lbk of the bucket 10. Note that the dimension Lbm of the boom 8 is the length from the boom pin 8a to the arm pin 9a. The dimension Lam of the arm 9 is the length from the arm pin 9a to the bucket pin 10a. The dimension Lbk of the bucket 10 is the length from the bucket pin 10a to the tip of the bucket 10. Furthermore, when the swing angle θsw is set to zero, the boom pin 8a is offset by Lox in the positive direction of the X-axis from the swing central axis.

[0037] Furthermore, the attitude calculation unit 42 calculates the inclination angle of the machine body 3 and the lower traveling structure 5 relative to the reference plane DP from the detection signal of the inclination angle of the machine body 3 output from the inclination angle sensor 18. The reference plane DP is, for example, a horizontal plane perpendicular to the direction of gravity. The inclination angle of the machine body 3 and the lower traveling structure 5 relative to the reference plane DP includes a pitch angle θp, which is a rotation angle about the Y axis, and a roll angle θr, which is a rotation angle about the X axis. The attitude calculation unit 42 can calculate the pitch angular velocity and the roll angular velocity by differentiating the pitch angle θp and the roll angle θr. The attitude calculation unit 42 calculates the pitch angle θp, the roll angle θr, the pitch angular velocity, and the roll angular velocity of the machine body 3 and the lower traveling structure 5 relative to the reference plane DP from the pitch angle relative to the direction of gravity, the roll angle relative to the direction of gravity, and the swing angle θsw.

[0038] The terrain calculation unit 41 calculates the terrain around the work machine 1 in the reference coordinate system based on the detection results of the perimeter detection device 54 and the calculation results of the attitude calculation unit 42. If a bench 210 is present around the work machine 1, the terrain calculated by the terrain calculation unit 41 includes the terrain of the bench 210. The terrain of the bench 210 includes the terrain of the bench edge 212.

[0039] The cliff determination unit 44 determines whether or not a cliff edge (bench edge 212) exists around the work machine 1 based on the detection results of the surroundings detection device 54. Specifically, the cliff determination unit 44 detects the bench edge 212 using the calculation results of the terrain calculation unit 41. The technique described in JP 2023-69275 A, for example, can be used to detect the bench edge 212. In this case, the bench edge 212 is detected by determining whether or not a height H1 of the upper surface 211 on which the work machine 1 is located and a ground surface 220 at a height H2 that has a height difference from the height H1 of a predetermined value or more are detected. Note that the method for detecting the bench edge 212 does not have to be limited to this method.

[0040] The cliff determination unit 44 then determines whether or not the bench edge 212 exists within a range of the threshold value th from the origin of the reference coordinate system. The threshold value th may be, for example, the distance that the bucket 10 can reach. The distance that the bucket 10 can reach may be, for example, the maximum working radius of the work machine 1.

[0041] The cliff determination unit 44 then calculates the distance between the bench edge 212 and each component of the work machine 1. Specifically, the cliff determination unit 44 calculates the distance between the bench edge 212 and the tip of the crawler 21, and the distance between the bench edge 212 and the side of the crawler 21. The cliff determination unit 44 may calculate the distance between the bench edge 212 and a point of the crawler 21 that is closest to the bench edge 212, rather than the distance between a specific point of the crawler 21 and the bench edge 212.

[0042] The movement direction calculation unit 43 calculates the speed of each of the hydraulic actuators 6, 11, 12, and 13 based on the detection results of the operation detection device 52. The movement direction calculation unit 43 calculates a velocity vector generated in the front working implement 2 (bucket 10) based on the calculated speeds of each of the hydraulic actuators 6, 11, 12, and 13 and the attitude of the work machine 1 calculated by the attitude calculation unit 42.

[0043] Specifically, the control device 40 stores in advance a table indicating the correspondence between the operation amounts of the control levers 22 and 23 and the speeds of the hydraulic actuators 6, 11, 12, and 13. By referring to this table, the movement direction calculation unit 43 calculates the speeds of the hydraulic actuators 6, 11, 12, and 13 from the operation amounts included in the operation information of the control levers 22 and 23 output from the operation detection device 52. The movement direction calculation unit 43 can then convert the speed of the swing hydraulic motor 6 into the swing angular velocity of the upper swing body 7. The movement direction calculation unit 43 can convert the speed of the boom cylinder 11 into the rotation angular velocity of the boom 8. The movement direction calculation unit 43 can convert the speed of the arm cylinder 12 into the rotation angular velocity of the arm 9. The movement direction calculation unit 43 can convert the speed of the bucket cylinder 13 into the rotation angular velocity of the bucket 10.

[0044] The movement direction calculation unit 43 then calculates a velocity vector generated in the bucket 10 based on the rotation angles θbm, θam, θbk of the front working implement 2 and the swing angle θsw of the upper rotating structure 7 calculated by the attitude calculation unit 42, and the rotation angular velocities of the front working implement 2 and the swing angular velocity of the upper rotating structure 7.

[0045] The center of gravity calculation unit 45 calculates the position of the center of gravity of the work machine 1 based on the detection results of the attitude detection device 53. Specifically, the center of gravity calculation unit 45 calculates the current position of the center of gravity of the work machine 1 relative to the reference coordinate system based on the rotation angles of the front working implement 2, the swing angle of the upper rotating body 7, and the tilt angle of the machine main body 3 detected by the attitude detection device 53, and the weight of the excavated material in the bucket 10 acquired by the weight acquisition device 55. Furthermore, the center of gravity calculation unit 45 calculates the current position of the center of gravity of the work machine 1 relative to the upper rotating body coordinate system, which has the orientation of the front working implement 2 in a plan view as the first axis and a direction perpendicular to the first axis as the second axis.

[0046] Furthermore, the center of gravity calculation unit 45 predicts the direction of movement of the center of gravity position according to the operation information detected by the operation detection device 52, and the rotation angles of the front working implement 2, the swing angle of the upper swing body 7, and the tilt angle of the machine main body 3, detected by the attitude detection device 53. Specifically, the center of gravity calculation unit 45 predicts the direction of movement of the center of gravity position of the work machine 1 based on the velocity vector calculated by the movement direction calculation unit 43. The center of gravity calculation unit 45 may predict the movement trajectory of the center of gravity position based on the velocity vector.

[0047] In particular, the center of gravity calculation unit 45 can predict the movement direction of the center of gravity position of the work machine 1 when the upper rotating body 7 performs a swing operation in accordance with operation information of the swing operation on the upper rotating body 7. When the loaded machine 200 is detected by the surroundings detection device 54, the center of gravity calculation unit 45 can predict the movement direction of the swing operation of the upper rotating body 7, assuming that a loading operation after an excavation operation will be performed on the loaded machine 200. This allows the center of gravity calculation unit 45 to predict the movement direction of the center of gravity position of the work machine 1 when the upper rotating body 7 performs a swing operation, without using the velocity vector calculated by the movement direction calculation unit 43.

[0048] The stabilization support unit 46 supports the stabilization of the posture of the work machine 1. The stabilization support unit 46 supports the stabilization of the posture of the work machine 1 when the distance between the bench edge 212 determined by the cliff determination unit 44 and the center of gravity position calculated by the center of gravity calculation unit 45 is equal to or less than a preset threshold value.

[0049] Specifically, the stabilization assistance unit 46 determines whether the work machine 1 is in a state where it is tilted so that the distance between the bench edge 212 and the center of gravity position fluctuates, based on the tilt angle of the work machine 1 calculated by the attitude calculation unit 42 based on the detection results of the attitude detection device 53, and the center of gravity position calculated by the center of gravity calculation unit 45. For example, the stabilization assistance unit 46 may determine whether the work machine 1 is in a state where it is tilted so that the distance fluctuates by determining whether a tilt angular velocity of the undercarriage 5 is occurring in a direction in which the center of gravity position approaches the bench edge 212.

[0050] The stabilization assist unit 46 then determines whether the work machine 1 is in a tilted state and the distance between the bench edge 212 and the center of gravity position is equal to or less than a first threshold value th1. If the distance between the bench edge 212 and the center of gravity position is equal to or less than the first threshold value th1, the stabilization assist unit 46 assists in stabilizing the posture of the work machine 1.

[0051] As a result, when the work machine 1 is actually in a tilted state, the stabilization assistance unit 46 can prevent the bench edge 212 from collapsing, reducing the postural stability of the work machine 1, or causing the work machine 1 to fall off the bench edge 212, which could be caused by the center of gravity position coming too close to the bench edge 212. Therefore, the work machine 1 can reliably ensure postural stability of the work machine 1 by taking into account the effect of cliff-like terrain on the postural stability of the work machine 1.

[0052] The first threshold value th1 is a value that distinguishes whether or not the risk of the bench edge 212 collapsing or the risk of the work machine 1 falling off the bench edge 212 significantly increases due to the center of gravity of the work machine 1 approaching the bench edge 212.

[0053] The first threshold th1 may be set to a different value between the first threshold th1a used to determine the distance between the center of gravity and an edge 212 present in the traveling direction of the crawler 21 and the position of the center of gravity and the first threshold th1b used to determine the distance between the center of gravity and an edge 212 present in the left and right direction of the crawler 21. The crawler 21 is more likely to retreat from an edge 212 present in the traveling direction of the crawler 21 than from an edge 212 present in the left and right direction of the crawler 21. Therefore, the first threshold th1b used to determine the edge 212 present in the left and right direction of the crawler 21 may be set to a larger value than the first threshold th1a used to determine the edge 212 present in the traveling direction of the crawler 21. In this way, when the edge 212 present in the left and right direction of the crawler 21 is present, the stabilization assistance unit 46 can assist in posture stabilization from a situation where the work machine 1 is further away from the edge 212 of the bench than when the edge 212 is present in the traveling direction of the crawler 21. Therefore, the stabilization assisting section 46 can ensure the posture stability of the work machine 1 more reliably.

[0054] Furthermore, the stabilization assistance unit 46 predicts the distance between the bench edge 212 and the center of gravity position based on the direction of movement of the center of gravity position predicted by the center of gravity calculation unit 45, and determines whether the predicted distance between the bench edge 212 and the center of gravity position is equal to or less than a second threshold value th2. If the predicted distance between the bench edge 212 and the center of gravity position is equal to or less than the second threshold value th2, the stabilization assistance unit 46 assists in stabilizing the posture of the work machine 1 even if the work machine 1 is not in a tilted state.

[0055] As a result, the stabilization assistance unit 46 can assist in postural stabilization from a stage before the work machine 1 actually tilts, to prevent the postural stability of the work machine 1 from decreasing due to the center of gravity position coming too close to the bench edge 212. Therefore, the work machine 1 can reliably ensure postural stability of the work machine 1 by taking into account the effect of cliff-like terrain on the postural stability of the work machine 1.

[0056] The second threshold value th2 is a value that distinguishes whether or not the risk of the bench edge 212 collapsing or the risk of the work machine 1 falling off the bench edge 212 is predicted to significantly increase due to the position of the center of gravity of the work machine 1 approaching the bench edge 212. The second threshold value th2 may be set to the same value as the first threshold value th1, or may be set to a value different from the first threshold value th1. For example, the first threshold value th1 may be set to a value greater than the second threshold value th2. The second threshold value th2 is a threshold used when the work machine 1 is not tilted, while the first threshold value th1 is a threshold used when the work machine 1 is tilted. By setting the first threshold value th1 to a value greater than the second threshold value th2, when the work machine 1 is in a tilted state, the stabilization assistance unit 46 can assist in posture stabilization from a situation where the work machine 1 is farther away from the bench edge 212 than when the work machine 1 is not tilted. Therefore, the stabilization assistance unit 46 can more reliably ensure the posture stability of the work machine 1.

[0057] In particular, the stabilization assistance unit 46 can predict the distance between the bench edge 212 and the center of gravity position when a turning operation is performed based on the direction of movement of the center of gravity position predicted by the center of gravity calculation unit 45, and determine whether the predicted distance between the bench edge 212 and the center of gravity position is less than or equal to the second threshold value th2.

[0058] As a result, the stabilization assistance unit 46 can predict that the posture stability of the work machine 1 will decrease due to the swing operation even before the swing operation of the upper swing body 7 is performed, and can assist in posture stabilization. Therefore, the work machine 1 can reliably ensure posture stability of the work machine 1 by taking into account the effect of cliff-like terrain on the posture stability of the work machine 1.

[0059] As support for posture stabilization, the stabilization assistance unit 46 causes the notification device 56 to issue, for example, an alarm. At this time, the stabilization assistance unit 46 causes the notification device 56 to issue at least one of an alarm notifying the operator of the details of an operation that will cause the center of gravity position to approach the bench edge 212, and an alarm that warns that the operator has performed an operation that will cause the center of gravity position to approach the bench edge 212.

[0060] FIG. 8 is a flowchart showing a process related to posture stabilization assistance performed by the control device 40 shown in FIG.

[0061] In step S1, the control device 40 acquires information about the topography around the work machine 1. Specifically, the control device 40 calculates the topography around the work machine 1 in the reference coordinate system from the detection results of the surroundings detection device 54.

[0062] In step S2, the control device 40 determines whether or not a bench edge 212 exists around the work machine 1. Specifically, the control device 40 determines whether or not a bench edge 212 exists within a range of the threshold value th from the origin of the reference coordinate system. If a bench edge 212 exists around the work machine 1, the control device 40 proceeds to step S3. If a bench edge 212 does not exist around the work machine 1, the control device 40 ends the processing shown in FIG. 8.

[0063] In step S3, the control device 40 determines whether the work machine 1 is in a state of tilting so that the distance between the bench edge 212 and the position of the center of gravity varies. If the work machine 1 is in a state of tilting so that the distance between the bench edge 212 and the position of the center of gravity varies, the control device 40 proceeds to step S4. If the work machine 1 is not in a state of tilting so that the distance between the bench edge 212 and the position of the center of gravity varies, the control device 40 proceeds to step S5.

[0064] In step S4, the control device 40 determines whether the distance between the bench edge 212 and the center of gravity position is equal to or less than a first threshold value th1. If the distance between the bench edge 212 and the center of gravity position is equal to or less than the first threshold value th1, the control device 40 proceeds to step S7. If the distance between the bench edge 212 and the center of gravity position is not equal to or less than the first threshold value th1, the control device 40 ends the processing shown in FIG.

[0065] In step S5, the control device 40 determines whether the center of gravity is located on the front working implement 2 side or the counterweight side relative to the upper rotating body 7. If the center of gravity is located on the front working implement 2 side, the control device 40 proceeds to step S6. If the center of gravity is located on the counterweight side, the processing shown in FIG. 8 ends.

[0066] In step S6, the control device 40 determines whether or not the distance between the bench edge 212 and the center of gravity position is predicted to be equal to or less than the second threshold value th2 when the upper rotating body 7 performs a rotating operation. If the distance between the bench edge 212 and the center of gravity position is predicted to be equal to or less than the second threshold value th2, the control device 40 proceeds to step S7. If the distance between the bench edge 212 and the center of gravity position is predicted not to be equal to or less than the second threshold value th2, the processing shown in FIG. 8 ends.

[0067] In step S7, the control device 40 causes the alarm device 56 to issue an alarm notifying the user of the operation that will cause the center of gravity position to approach the bench edge 212.

[0068] In step S8, the control device 40 determines whether or not the operator has performed an operation corresponding to the warning in step S7. If an operation corresponding to the warning in step S7 has been performed, the control device 40 proceeds to step S9. If an operation corresponding to the warning in step S7 has not been performed, the control device 40 ends the process shown in FIG.

[0069] In step S9, the control device 40 causes the alarm device 56 to issue an alarm to warn that the operator has performed an operation that causes the center of gravity position to approach the bench edge 212. Thereafter, the control device 40 ends the processing shown in FIG.

[0070] The effects of the work machine 1 will be described with reference to Figures 9 to 12. Figure 9 is a rear view of the work machine 1 illustrating the state in which the work machine 1 is tilted in the roll direction.

[0071] As shown in Figure 9, if the collapse of the bench edge 212 near the left crawler 21b causes the lower running body 5 to tilt in the roll direction, there is a risk that the postural stability of the work machine 1 will decrease. The work machine 1 issues an alarm notifying the operator of the details of an operation that will cause the center of gravity position to approach the bench edge 212. The operator who has been notified of this alarm will not have to perform the operation. This allows the work machine 1 to prevent a large load from being applied to the bench edge 212, which would cause the bench edge 212 to collapse, thereby ensuring the postural stability of the work machine 1. Therefore, the work machine 1 can ensure the postural stability of the work machine 1 by taking into account the effect of cliff-like terrain on the postural stability of the work machine 1.

[0072] FIG. 10 is a side view of the work machine 1 illustrating the state in which the work machine 1 is tilted in the pitch direction.

[0073] If the collapse of the bench edge 212 near the front of the crawler 21 causes the lower running body 5 to tilt in the pitch direction, there is a risk that the postural stability of the work machine 1 will decrease. The work machine 1 issues an alarm notifying the operator of the details of the operation that will cause the center of gravity position to approach the bench edge 212. The operator who has been notified of this alarm will not have to perform the operation. This allows the work machine 1 to prevent a large load from being applied to the bench edge 212, which would cause the bench edge 212 to collapse, thereby ensuring the postural stability of the work machine 1.

[0074] FIG. 11 is a top view of the working machine 1 illustrating the state during a swing operation when the center of gravity is located on the front working implement 2 side.

[0075] When the bucket 10 is carrying an excessively large excavated object, the center of gravity of the work machine 1 shifts toward the front work machine 2. If a left swing is performed in this state, the center of gravity approaches the bench edge 212 near the left crawler 21b, and a large load is applied to the bench edge 212. This could cause the bench edge 212 to collapse, and the postural stability of the work machine 1 could be reduced. The work machine 1 issues an alarm notifying the operator of the operation that will cause the center of gravity to approach the bench edge 212. When the alarm is issued, the operator does not need to perform the operation. As a result, the work machine 1 can prevent a large load from being applied to the bench edge 212, which could cause the bench edge 212 to collapse, thereby ensuring the postural stability of the work machine 1.

[0076] FIG. 12 is a diagram showing an example of an alarm issued by the alarm device 56 shown in FIG.

[0077] Figure 12 shows an example of an alarm that is issued in a situation where, when the upper rotating body 7 performs a left swing operation, the center of gravity position approaches the bench edge 212. The alarm shown in Figure 12(a) is an example of an alarm that notifies the operator of the operation that will cause the center of gravity position to approach the bench edge 212, and corresponds to the alarm issued in step S7 of Figure 8. The alarm shown in Figure 12(b) is an example of an alarm that warns that the operator has performed an operation that will cause the center of gravity position to approach the bench edge 212, and corresponds to the alarm issued in step S9 of Figure 8. By issuing such an alarm, the work machine 1 can reliably make the operator aware of an operation that will reduce the postural stability of the work machine 1, and therefore the postural stability of the work machine 1 can be reliably ensured.

[0078] [Second embodiment] A working machine 1 of the second embodiment will be described using Figures 13 to 15. In the working machine 1 of the second embodiment, explanations of the same components as those in the first embodiment will be omitted.

[0079] FIG. 13 is a block diagram illustrating the functional configuration of the control device 40 of the second embodiment.

[0080] The control device 40 of the second embodiment is configured by adding an operation control unit 47 that controls the operation of the work machine 1 to the control device 40 of the first embodiment. The operation control unit 47 generates a control command for the electromagnetic proportional valve 51 and outputs it to the electromagnetic proportional valve 51.

[0081] In the second embodiment, when the distance between the bench edge 212 determined by the cliff determination unit 44 and the center of gravity position calculated by the center of gravity calculation unit 45 is equal to or less than a preset threshold, the stabilization support unit 46 restricts the operator's operation that causes the center of gravity position to approach the bench edge 212 as support for stabilizing the posture of the work machine 1.

[0082] Specifically, the stabilization assist unit 46 sets an upper limit value for the amount of operation for the operation of approaching the center of gravity position to the bench edge 212, and notifies the operation control unit 47 of the set upper limit value. The operation control unit 47 generates a control command by keeping the amount of operation for the operation of approaching the center of gravity position to the bench edge 212 equal to or less than the upper limit value notified by the stabilization assist unit 46, and outputs the control command to the solenoid proportional valve 51. Note that the upper limit value for the amount of operation may be zero. In other words, the stabilization assist unit 46 may limit the operation so that the operation of approaching the center of gravity position to the bench edge 212 is invalid.

[0083] FIG. 14 is a flowchart showing the processing related to the posture stabilization assistance performed by the control device 40 shown in FIG.

[0084] In the process shown in Fig. 14, steps S17 and S18 are added instead of steps S7 to S9 of the process shown in Fig. 8. That is, the control device 40 of the second embodiment proceeds to step S17 when the work machine 1 is in a tilted state and the distance between the bench edge 212 and the center of gravity position is equal to or less than the first threshold value th1 (step S4: Yes). When the upper rotating body 7 is performing a rotating operation, the control device 40 proceeds to step S17 when it is predicted that the distance between the bench edge 212 and the center of gravity position will be equal to or less than the second threshold value th2 (step S6: Yes).

[0085] In step S17, the control device 40 restricts the operation that causes the center of gravity position to approach the bench edge 212.

[0086] In step S18, the control device 40 causes the notification device 56 to issue an alarm notifying that an operation that would cause the center of gravity position to approach the bench edge 212 is restricted. Thereafter, the control device 40 ends the processing shown in FIG.

[0087] The work machine 1 of the second embodiment can prevent the center of gravity from approaching the bench edge 212 by limiting the operation that would cause the center of gravity to approach the bench edge 212, thereby more reliably ensuring the postural stability of the work machine 1. For example, in the situation shown in FIG. 9 , if the operator performs a left swing operation and the upper swing body 7 swings left, depending on the posture of the front working implement 2 and the weight of the excavated material, the center of gravity of the work machine 1 may approach the bench edge 212, and the postural stability of the work machine 1 may decrease. In such a case, the work machine 1 of the second embodiment can prevent the postural stability of the work machine 1 from decreasing because the left swing operation is limited. Therefore, the work machine 1 of the second embodiment can more reliably ensure the postural stability of the work machine 1 by taking into account the effect of cliff-like terrain on the postural stability of the work machine 1.

[0088] FIG. 15 is a diagram showing an example of an alarm issued by the alarm device 56 shown in FIG.

[0089] Figure 15 shows an example of an alarm that is issued in a situation where, when the upper rotating body 7 performs a left swing operation, the center of gravity position approaches the bench edge 212. The alarm shown in Figure 15 is an example of an alarm that notifies that an operation that would cause the center of gravity position to approach the bench edge 212 is restricted, and corresponds to the alarm issued in step S18 in Figure 14. By issuing such an alarm, the work machine 1 can reliably let the operator know that an operation that reduces the posture stability of the work machine 1 is restricted, thereby reducing the sense of discomfort felt by the operator due to the restriction on the operation.

[0090] [Third embodiment] A work machine 1 of the third embodiment will be described using Figures 16 and 17. Descriptions of components of the work machine 1 of the third embodiment that are the same as those of the second embodiment will be omitted.

[0091] Fig. 16 is a block diagram illustrating the functional configuration of the control device 40 of the third embodiment. Fig. 17 is a diagram illustrating the relationship between the threshold value changed by the stabilization support unit 46 shown in Fig. 16 and the soil information.

[0092] The work machine 1 of the third embodiment is further equipped with a soil property acquisition device 57 that acquires soil property information around the work machine 1, including the bench edge 212. The soil property information may include information related to the hardness of the ground around the work machine 1. The information related to the hardness of the ground may be information indicating the hardness of the ground itself. Alternatively, the information related to the hardness of the ground may be information indicating parameters that affect the hardness of the ground, such as the moisture content of the ground, the type of ground (sand, sandy soil, gravel, clayey soil, ore, etc.), the particle size of the ground, or the specific gravity of the ground. The soil property acquisition device 57 may be configured as a receiving device that receives soil property information around the work machine 1 from outside the work machine 1 (for example, a control system, etc.). Alternatively, the soil property acquisition device 57 may acquire soil property information by detecting resistance generated in the bucket 10 during an excavation operation of the front work implement 2. Alternatively, the soil property acquisition device 57 may have an imaging device that captures images of the excavated object, and acquire soil property information from images of the excavated object captured by the imaging device. The soil property acquisition device 57 may acquire soil property information when the work machine 1 starts working, or may acquire soil property information in real time while the work machine 1 is working.

[0093] The stabilization support unit 46 of the third embodiment changes the threshold value (at least one of the first threshold value th1 and the second threshold value th2) used to determine the distance between the bench edge 212 and the center of gravity position, in accordance with the soil information acquired by the soil property acquisition device 57. For example, as shown in FIG. 12, a map indicating the relationship between the ground hardness and the threshold value is preset in the stabilization support unit 46. This map may indicate a relationship in which the threshold value decreases as the ground hardness increases and becomes constant after a certain level of ground hardness. The stabilization support unit 46 estimates the ground hardness from the soil information acquired by the soil property acquisition device 57. The stabilization support unit 46 refers to the map shown in FIG. 12 to identify the threshold value corresponding to the estimated ground hardness and set the identified threshold value. In this manner, the stabilization support unit 46 can change the threshold value.

[0094] As a result, the work machine 1 of the third embodiment can change the conditions for starting to assist with posture stabilization of the work machine 1 depending on surrounding soil information, thereby reliably ensuring posture stability of the work machine 1 while further reducing the discomfort felt by the operator due to alarm notifications or operation restrictions.

[0095] [Fourth embodiment] A working machine 1 of the fourth embodiment will be described using Figure 18. In the working machine 1 of the fourth embodiment, explanations of the same components as those of the first to third embodiments will be omitted.

[0096] FIG. 18 is a diagram illustrating a remote control device 300 that operates a work machine 1 according to the fourth embodiment.

[0097] The work machine 1 of the fourth embodiment is operated by a remote control device 300 that is placed in a remote location away from the work machine 1. The remote control device 300 is equipped with a wireless communication device 301 that communicates wirelessly with the communication device 60 of the work machine 1, a remote control lever 302 that is operated by an operator in the remote location, and a display 303 that displays the terrain around the work machine 1.

[0098] An operator in a remote location can operate the remote control lever 302 to move the work machine 1 while viewing the topography around the work machine 1 displayed on the display 303. Operation information of the remote control lever 302 by the operator is transmitted from the wireless communication device 301 to the communication device 60 of the work machine 1. The communication device 60 of the work machine 1 receives the operation information transmitted from the wireless communication device 301 of the remote operation device 300 and outputs it to the control device 40. The control device 40 controls the work machine 1 in accordance with the operation information transmitted from the wireless communication device 301 of the remote operation device 300.

[0099] In such a remotely controlled work machine 1, when the distance between the bench edge 212 and the center of gravity position falls below a threshold value, the control device 40 assists in stabilizing the posture of the work machine 1, similar to the first to third embodiments. This allows the work machine 1 of the fourth embodiment to ensure the posture stability of the work machine 1 by taking into account the effect that cliff-like terrain has on the posture stability of the work machine 1, similar to the first to third embodiments.

[0100] Furthermore, when restricting an operation that would cause the center of gravity to approach the bench edge 212, the remote control device 300 can apply a force (reaction force) to the remote control lever 302 that acts in the opposite direction to the operation direction of the remote control lever 302. As a result, in the fourth embodiment, the postural stability of the work machine 1 is reliably ensured while the operator can be made to reliably understand that an operation that would reduce the postural stability of the work machine 1 is being restricted, thereby reducing the sense of discomfort felt by the operator due to the restriction on operation. Note that instead of the above-mentioned reaction force, the remote control device 300 may apply vibrations or the like to the remote control lever 302 to stimulate the operator's tactile sense.

[0101] The present invention is not limited to the above-described embodiments and includes various modifications. For example, the above-described embodiments have been described in detail to clearly explain the present invention, and are not necessarily limited to those including all of the described components. Furthermore, some of the components of one embodiment can be replaced with components of another embodiment, and components of another embodiment can be added to components of one embodiment. Furthermore, some of the components of each embodiment can be added, deleted, or replaced with other components.

[0102] Furthermore, the above-described components, functions, processing units, or processing means may be partially or entirely implemented in hardware, for example, by designing them as integrated circuits. The above-described components or functions may also be implemented in software, with a processor interpreting and executing a program that implements each function. Information such as the programs, tables, or files that implement each function may be stored in a storage device such as a memory, a hard disk, or an SSD (solid state drive), or in a storage medium such as an IC card, SD card, or DVD.

[0103] In addition, the control lines and information lines shown are those that are considered necessary for the explanation, and do not necessarily show all the control lines and information lines in the product. In reality, it can be assumed that almost all components are interconnected. [Explanation of symbols]

[0104] 1...working machine, 2...front working device (working device), 5...undercarriage, 7...upper rotating body, 21...crawler, 40...control device, 44...cliff determination unit, 45...center of gravity calculation unit, 46...stabilization support unit, 52...operation detection device, 53...posture detection device, 54...surroundings detection device, 56...alarm device, 57...soil quality acquisition device, 60...communication device, 212...bench edge (cliff edge), 300...remote control device, 302...remote control lever

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