Working machinery

Abstract

To provide a work machine capable of avoiding interference on a target surface even in a state a tilt cylinder reaches the vicinity of a stroke end during excavation operation when carrying out machine control on a work machine provided with a tilt bucket.SOLUTION: A member to be actuated arranged at a tip of a work machine is provided with: a bucket provided with a tilt cylinder which is a hydraulic actuator to rotate in a right and left direction regarding to the work machine; and a control device controlling a right / left angle of a part opposite to a predetermined target surface of the bucket so as to align with the target surface, and performing area limit control of the bucket by outputting an operation signal such that the bucket is to be positioned or to be corrected within an area above the target surface, wherein the control device controls the bucket to be separate apart from the target surface when a tilt angle of the target surface is larger than a tilt angle of the bucket in a state the tilt cylinder reaches a stroke end when the area limit control is carried out.SELECTED DRAWING: Figure 10

Description

Technical Field

[0001] The present invention relates to a working machine.

Background Art

[0002] Some hydraulic excavators, which are one type of working machine, may be equipped with a control system that assists the operator's excavation operation. Specifically, when an excavation operation (for example, an instruction for the arm crowd) is input via an operating device, based on the positional relationship between the target surface and the tip of the working machine (for example, the tip of the bucket), at least the boom cylinder among the boom cylinder, arm cylinder, and bucket cylinder that drives the working machine (also referred to as the front working machine) is forced to operate so that the position of the tip of the working machine is held within the area on and above the target surface (for example, control to extend the boom cylinder and forcibly perform a boom raising operation), or a stop control that stops the boom cylinder, bucket cylinder, or tilt cylinder when the bucket is of the tilt type so that the tip of the working machine stops on the target surface.

[0003] By using a control system that restricts the area where the tip of such a working machine can move, the finishing work of the excavation surface and the shaping work of the slope surface are facilitated. Hereinafter, this type of control may be referred to as "area restriction control" or "grading control". And during the operation of the operating device, a control signal for operating a predetermined actuator according to a predetermined condition is calculated, and the general control of controlling the actuator based on the control signal is sometimes referred to as "machine control (MC)" or "(intervention control for operator operation)".

[0004] As a conventional technique related to the machine control (MC) system of a tilt bucket, there is known one that determines the target tilt angle and target bucket angle of the bucket so that the target surface and the bucket are parallel, and controls the tilt cylinder and bucket cylinder.

[0005] As an example of such a machine control system, Patent Document 1 discloses a control system for a construction machine equipped with a work machine including an arm and a bucket that is rotatable relative to the arm about each of a bucket axis and a tilt axis perpendicular to the bucket axis, the control system comprising: an angle determination unit that determines a tilt angle indicating the angle of the specific part of the bucket about the tilt axis so that the target construction terrain indicating the target shape of the excavation target and the specific part of the bucket are parallel; and a work machine control unit that controls a tilt cylinder that rotates the bucket about the tilt axis based on the tilt angle determined by the angle determination unit. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] International Publication No. 2018 / 030220 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] However, the above-mentioned conventional technology has the following problems when the tilt cylinder reaches the stroke end and the inclination of the target surface near the bucket becomes even greater. In other words, in the above case, an attempt is made to control the tilt cylinder by calculating a tilt angle that is greater than the inclination angle reached at the stroke end as the target tilt angle, but the tilt angle cannot rotate any further because the stroke end has been reached. And in this state, if an attempt is made to avoid over-excavating the target surface by raising the bucket position with boom raising compensation, the compensation after acquiring the bucket cutting edge position information is not fast enough, and there is a risk that the bucket will interfere with the target surface which is inclined more than that tilt angle.

[0008] The present invention has been made in view of the above, and aims to provide a work machine equipped with a tilt bucket that can avoid interference with the target surface even when the tilt cylinder has reached near the end of the stroke during excavation. [Means for solving the problem]

[0009] The present invention includes multiple means for solving the above problems, but to give one example, it includes a multi-joint work machine comprising a lower traveling body, an upper rotating body rotatably provided with respect to the lower traveling body, a plurality of driven members attached to the upper rotating body and rotatably connected, a plurality of hydraulic actuators that drive each of the plurality of driven members based on an operation signal, a bucket provided at the tip of the work machine which is a driven member and has a tilt cylinder which is a hydraulic actuator for rotating in the left and right directions about a tilt rotation axis perpendicular to the rotation axis of the work machine, a posture information detection device that detects posture information which is information relating to the posture of the work machine, and a control device that outputs the operation signal to at least one of the plurality of hydraulic actuators or corrects the operation signal output to at least one of the plurality of hydraulic actuators based on the posture information detected by the posture information detection device so that the left and right angles of the part of the bucket facing a predetermined target surface coincide with the target surface and the bucket is located on or above the target surface, and the control device controls the bucket point When performing the region restriction control so that it moves on the target surface, The inclination of the target surface at the predicted position, from the current position of the bucket to a predetermined distance ahead in the direction in which the bucket is moving, When the tilt cylinder reaches its stroke end, the left-right inclination angle of one side of the bucket facing the target surface is greater than The system determines whether the angle is large or small, and if the inclination of the target surface is less than or equal to the left-right inclination angle of one side of the bucket facing the target surface, the system performs an excavation operation so that the control point of the bucket moves along the target surface. If the inclination of the target surface is greater than the left-right inclination angle of one side of the bucket facing the target surface, the system calculates the amount the bucket will penetrate into the target surface when the control point of the bucket is located on the target surface at the predicted position, determines the target position of the bucket so that it moves away from the target surface at the predicted position by the calculated amount of penetration, and performs avoidance control so that one end of the side of the bucket facing the target surface moves along the straight line connecting the determined target position of the bucket and the current position of the bucket. It shall be considered as such. [Effects of the Invention]

[0010] According to the present invention, when performing machine control on a work machine equipped with a tilt bucket, interference with the target surface can be avoided even when the tilt cylinder has reached near the end of its stroke during excavation. [Brief explanation of the drawing]

[0011] [Figure 1] This is a schematic side view showing the external appearance of a hydraulic excavator, which is an example of a work machine. [Figure 2] This diagram shows the hydraulic drive unit and controller separated from the main unit. [Figure 3] This diagram shows the details of the front control hydraulic unit along with its related components. [Figure 4] This diagram shows the reference coordinate system for a hydraulic excavator, and is a side view showing the XY coordinate system. [Figure 5] This diagram shows the reference coordinate system for a hydraulic excavator, and is a rear view showing the YZ coordinate system. [Figure 6] This is a hardware configuration diagram of a controller that constitutes a control system for machine guidance and machine control of a hydraulic excavator. The diagram shows the controller and its related components in a schematic manner. [Figure 7] This figure shows an example of a display screen for a display device. [Figure 8] This is a functional block diagram showing the processing steps of the controller. [Figure 9] This diagram shows the details of the processing functions of the target velocity calculation unit, along with related functions. [Figure 10] This flowchart shows the processing steps involved in determining whether excavation avoidance is necessary. [Figure 11] This figure shows an example of the bucket position in the current position and the bucket position in the predicted position after moving a certain distance in the excavation direction, along with the target plane. [Figure 12] This figure shows a comparison between the views taken along arrow A and arrow B in Figure 11. [Figure 13]It is a diagram showing an example in which the inclination in the cross-sectional direction of the target surface as seen from the driver's cab increases as the excavation progresses in the excavation direction. [Figure 14] It is a diagram showing the velocity vector of the bucket tip in each state of the normal excavation operation mode. [Figure 15] It is a diagram showing an example of the tilting operation of the bucket with respect to the target surface. [Figure 16] It is a diagram showing an example of the tilting operation of the bucket with respect to the target surface. [Figure 17] It is a diagram showing the relationship between the tilt angle deviation and the tilt target speed. [Figure 18] It is a diagram showing an example of the bucket position in the current posture and the bucket position in the predicted posture when advancing a certain distance in the excavation direction together with the target surface. [Figure 19] It is a diagram showing the view from the arrow B in FIG. 18. [Figure 20] It is a diagram showing the state of target trajectory correction. [Figure 21] It is a diagram showing the corrected target trajectory when advancing in the excavation direction from the bucket position in the current posture to the bucket position in the predicted posture. [Figure 22] It is a diagram showing the view from the arrow B in FIG. 21.

Mode for Carrying Out the Invention

[0012] Hereinafter, an embodiment of the present invention will be described while referring to the drawings. In this embodiment, a hydraulic excavator equipped with a working machine having a bucket with a tilt mechanism will be shown and described, but the present invention can also be applied to other working machines equipped with a working machine having a tilt bucket.

[0013] <The First Embodiment> The first embodiment of the present invention will be described while referring to the drawings.

[0014] Figure 1 is a schematic side view showing the external appearance of a hydraulic excavator, which is an example of a work machine according to this embodiment. Figure 2 is a diagram showing the hydraulic drive unit together with the controller, and Figure 3 is a diagram showing the details of the front control hydraulic unit along with its related components.

[0015] In Figure 1, the hydraulic excavator 100 consists of an articulated workpiece 1A (sometimes called a front workpiece) and a vehicle body 1B. The vehicle body 1B consists of a lower travel body 11 that is driven by left and right travel hydraulic motors 3a and 3b (only hydraulic motor 3a is shown in Figure 1), and an upper slewing body 12 that is mounted on top of the lower travel body 11 and slewing relative to the lower travel body 11 by a slewing hydraulic motor 4.

[0016] The work machine 1A is constructed by connecting multiple driven members (boom 8, arm 9, bucket 10, and tilt mechanism 17) that each rotate vertically.

[0017] The base end of the boom 8 is rotatably supported at the front of the upper slewing body 12 via a boom pin. An arm 9 is rotatably connected to the tip of the boom 8 via an arm pin, and a tilt mechanism 17 and a bucket 10 are rotatably connected to the tip of the arm 9 via a bucket pin. The bucket (tilt bucket) 10 is rotatably connected in the left-right direction about a tilt pivot axis perpendicular to the pivot axis of the tilt mechanism 17 relative to the arm 9.

[0018] The boom 8 is driven by the boom cylinder 5, the arm 9 is driven by the arm cylinder 6, the bucket 10 is driven by the bucket cylinder 7, and the tilt mechanism 17 is driven by the tilt cylinder 14.

[0019] To enable measurement of the rotation angles α, β, γ, Ψ of the boom 8, arm 9, bucket 10, and tilt mechanism 17 (see Figures 4 and 5 below), a boom angle sensor 30 is attached to the boom pin, an arm angle sensor 31 to the arm pin, a bucket angle sensor 32 to the bucket link 13, and a tilt angle sensor 34 to the tilt mechanism. A vehicle body tilt angle sensor 33 is attached to the upper slewing body 12 to detect the tilt angles θ, Φ of the upper slewing body 12 (vehicle body 1B) with respect to a reference plane (e.g., the horizontal plane) (see Figures 4 and 5 below). Note that angle sensors 30, 31, 32, and 34 can each be replaced with angle sensors for reference planes (e.g., inertial measurement units (IMUs)).

[0020] As shown in Figures 2 and 3, the driver's cab 12a located in the upper slewing body 12 contains an operating device 47a with a right travel lever 23a for operating the right travel hydraulic motor 3a (lower travel body 11), an operating device 47b with a left travel lever 23b for operating the left travel hydraulic motor 3b (lower travel body 11), operating devices 45a and 46a sharing the right operating lever 1a for operating the boom cylinder 5 (boom 8) and bucket cylinder 7 (bucket 10), operating devices 45b and 46b sharing the left operating lever 1b for operating the arm cylinder 6 (arm 9) and slewing hydraulic motor 4 (upper slewing body 12), and an operating pedal 1c for operating the tilt mechanism 17. Hereafter, the right travel lever 23a, the left travel lever 23b, the right operating lever 1a, the left operating lever 1b, and the operating pedal 1c may be collectively referred to as operating levers 1 and 23.

[0021] The engine 18, which is the prime mover mounted on the upper rotating body 12, drives the hydraulic pump 2 and the pilot pump 49. The hydraulic pump 2 is a variable displacement pump whose capacity is controlled by the regulator 2a, and the pilot pump 49 is a fixed displacement pump. In this embodiment, a shuttle block 162 is provided in the middle of the pilot lines 143, 144, 145, 146, 147, 148, and 149. Hydraulic signals output from the operating devices 45, 46, 47, and 48 are also input to the regulator 2a via the shuttle block 162. The detailed configuration of the shuttle block 162 is omitted, but the shuttle block 162 selects the maximum value of the input hydraulic signal and inputs it to the regulator 2a, and the discharge flow rate of the hydraulic pump 2 is controlled according to the hydraulic signal.

[0022] The pump line 170, which is the discharge piping of the pilot pump 49, passes through the lock valve 39 and then branches into multiple lines connected to the operating devices 45, 46, 47, 48 and the valves in the front control hydraulic unit 160. In this embodiment, the lock valve 39 is an electromagnetic switching valve, and its electromagnetic drive unit is electrically connected to a position detector of a gate lock lever (not shown) located in the operator's cab of the upper slewing body 12. The position of the gate lock lever is detected by the position detector, and a signal corresponding to the position of the gate lock lever is input from the position detector to the lock valve 39. If the gate lock lever is in the locked position, the lock valve 39 closes and the pump line 170 is shut off, and if it is in the unlocked position, the lock valve 39 opens and the pump line 170 is opened. In other words, when the pump line 170 is shut off, the operation by the operating devices 45, 46, 47, 48 is disabled, and operations such as slewing and excavation are prohibited.

[0023] The operating devices 45, 46, 47, and 48 are hydraulic pilot type and generate pilot pressure (sometimes referred to as operating pressure) corresponding to the amount of operation (e.g., lever stroke) and direction of operation of the operating levers 1 and 23 operated by the operator, based on pressurized oil discharged from the pilot pump 49. The pilot pressure thus generated is supplied to the hydraulic drive units 150a to 156b of the corresponding flow control valves 15a to 15g in the control valve unit via pilot lines 143a to 149b and is used as a control signal to drive these flow control valves 15a to 15g.

[0024] Pressurized oil discharged from hydraulic pump 2 is supplied to the right travel hydraulic motor 3a, left travel hydraulic motor 3b, slewing hydraulic motor 4, boom cylinder 5, arm cylinder 6, bucket cylinder 7, and tilt cylinder 14 via flow control valves 15a, 15b, 15c, 15d, 15e, 15f, and 15g. The supplied pressurized oil causes the boom cylinder 5, arm cylinder 6, bucket cylinder 7, and tilt cylinder 14 to extend and retract, causing the boom 8, arm 9, and bucket 10 to rotate, respectively, and changing the position and orientation of the bucket 10. In addition, the supplied pressurized oil causes the slewing hydraulic motor 4 to rotate, causing the upper slewing body 12 to slewing relative to the lower travel body 11. Finally, the supplied pressurized oil causes the right travel hydraulic motor 3a and left travel hydraulic motor 3b to rotate, causing the lower travel body 11 to travel.

[0025] Figures 4 and 5 show the reference coordinate system for a hydraulic excavator; Figure 4 is a side view showing the XY coordinate system, and Figure 5 is a rear view showing the YZ coordinate system.

[0026] As shown in Figures 4 and 5, the posture of the work machine 1A can be defined based on the reference coordinate system of the hydraulic excavator 100 (hereinafter referred to as the excavator reference coordinate system). The excavator reference coordinate system is a coordinate system set on the upper slewing body 12, with the base of the boom 8 as the origin, and the Z axis set vertically and the X and Y axes set horizontally on the upper slewing body 12. The inclination angle of the boom 8 with respect to the X axis is defined as the boom angle α, the inclination angle of the arm 9 with respect to the boom is defined as the arm angle β, the inclination angle of the bucket tip with respect to the arm is defined as the bucket angle γ, and the inclination angle of the bucket with respect to the Y axis is defined as the tilt angle ψ. The front-to-back inclination angle of the vehicle body 1B (upper slewing body 12) with respect to the horizontal plane (reference plane) is defined as the inclination angle θ, and the left-to-right inclination angle is defined as Φ.

[0027] The boom angle α is detected by the boom angle sensor 30, the arm angle β by the arm angle sensor 31, the bucket angle γ by the bucket angle sensor 32, the tilt angle ψ by the tilt angle sensor 34, and the inclination angles θ and Φ by the vehicle body inclination angle sensor 33. The boom angle α is maximum when the boom 8 is raised to its maximum (highest) position (when the boom cylinder 5 is at the end of its upward stroke, i.e., when the boom cylinder length is at its longest), and minimum when the boom 8 is lowered to its minimum (lowest) position (when the boom cylinder 5 is at the end of its downward stroke, i.e., when the boom cylinder length is at its shortest). The arm angle β is minimum when the arm cylinder length is shortest, and maximum when the arm cylinder length is longest. The bucket angle γ is minimum when the bucket cylinder length is shortest, and maximum when the bucket cylinder length is longest. At this time, the dimensions of each part of the boom 8, arm 9, bucket 10, and tilt mechanism 17, along with the output of each angle sensor, allow for the calculation of the (X,Y,Z) coordinates of the bucket's tip, the center of its rear end, and its left and right ends.

[0028] Furthermore, as shown in Figure 4, the hydraulic excavator 100 is equipped with a pair of GNSS (Global Navigation Satellite System) antennas 16A and 16B on its upper rotating body 12. Based on the information from the GNSS antennas 16, the position of the hydraulic excavator 100, the tip position of the bucket 10, and the rear end position can be calculated in the global coordinate system.

[0029] Figure 6 is a hardware configuration diagram of the controller that constitutes the control system for machine guidance (MG) and machine control (MC) of a hydraulic excavator. It is a schematic diagram that extracts the controller and its related components.

[0030] In the control system according to this embodiment, when at least one of the operating devices 45a, 45b, 46a, 48 is operated, a control control (MC) is performed to operate the work machine 1A according to predetermined conditions. The control of the hydraulic actuators 5, 6, 7, 14 in the MC is performed by forcibly outputting control signals (for example, extending the boom cylinder 5 to forcibly raise the boom) to the corresponding flow control valves 15a, 15b, 15c, 15g. The MCs performed in the machine control system include "ground leveling control (area limiting control)" which is performed when front operation is performed, and "stop control" which is performed when lowering the boom or stopping the tilt.

[0031] The leveling control (area limiting control) is a control motor (MC) that controls at least one of the hydraulic actuators 5, 6, 7, and 14 so that the work implement 1A is positioned on or above a predetermined target surface 700 (see Figure 7 below). For example, it outputs a boom raising speed or boom lowering speed so that the velocity vector of the bucket tip (the tip of the work implement 1A) perpendicular to the target surface 700 becomes zero, so that the bucket tip moves along the target surface 700 due to arm operation. Alternatively, it increases or decreases the tilt rotation speed so that the tilt angle of the bucket matches the left-right angle of the target surface 700 during arm operation.

[0032] The stop control is a motor control (MC) that stops the boom lowering and tilting operations to prevent the bucket tip (e.g., the bucket tip) from entering below the target plane 700, and reduces the boom lowering speed and tilt rotation speed as the distance between the target plane 700 and the bucket tip approaches.

[0033] Furthermore, in this system, the MG of the work machine 1A performs a process to display the positional relationship between the target surface 700 and the work machine 1A (for example, the bucket 10) on the display device 57, as shown in Figure 7 below.

[0034] In this embodiment, the control point of the work implement 1A during MC is set to the tip of the bucket 10 of the hydraulic excavator 100 (the tip of the work implement 1A). However, the control point can be changed to any point on the tip of the work implement 1A other than the bucket tip. For example, the bottom surface of the bucket 10 or the outermost part of the bucket link 13 can be selected as the control point, and the point on the bucket 10 closest to the target surface 700 may be appropriately adopted as the control point.

[0035] The posture information detection device 50 consists of a boom angle sensor 30, an arm angle sensor 31, a bucket angle sensor 32, a vehicle body inclination angle sensor 33, and a tilt angle sensor 34. These angle sensors 30, 31, 32, 33, and 34 function as posture sensors for the work machine 1A and the upper slewing body 12.

[0036] The target surface setting device 51 is an interface that can input information about the target surface 700 (including position information and inclination angle information for multiple or single target surfaces). The target surface setting device 51 is connected to an external terminal (not shown) that stores 3D data of the target surface defined on the global coordinate system (absolute coordinate system). Note that the input of the target surface via the target surface setting device 51 may be performed manually by the operator.

[0037] The operator operation detection device 52a consists of pressure sensors 70a, 70b, 71a, 71b, 72a, 72b, 73a, and 73b that acquire the operating pressure (first control signal) generated in the pilot lines 143, 144, 145, and 146 by the operation of the operating levers 1a, 1b, and 1c (operating devices 45a, 45b, 46a, and 48) by the operator. In other words, it detects operations on the hydraulic cylinders 5, 6, 7, and 14 related to the work machine 1A.

[0038] Figure 7 shows an example of the display screen of a display device.

[0039] As shown in Figure 7, the display device 57 is a touch-panel type liquid crystal monitor installed in the driver's cabin to display the positional relationship between the target surface 700 and the work equipment 1A (for example, the bucket 10). The display screen of the display device 57 shows the positional relationship between the target surface 700 and the bucket 10 from the perspective of the vehicle body in the Y-axis direction and the X-axis direction, and the distance from the target surface 700 to the tip of the bucket 10 is displayed as the target surface distance.

[0040] As shown in Figure 3, the front control hydraulic unit 160 includes pressure sensors 70a and 70b provided on the pilot lines 144a and 144b of the operating device 45a for the boom 8, which detect pilot pressure (first control signal) as the amount of operation of the operating lever 1a; an electromagnetic proportional valve 54a whose primary port is connected to the pilot pump 49 via the pump line 170 and which reduces the pilot pressure from the pilot pump 49 and outputs it; a shuttle valve 82a connected to the pilot line 144a of the operating device 45a for the boom 8 and the secondary port side of the electromagnetic proportional valve 54a, which selects the high-pressure side of the pilot pressure in the pilot line 144a and the control pressure (second control signal) output from the electromagnetic proportional valve 54a and leads it to the hydraulic drive unit 150a of the flow control valve 15a; and an electromagnetic proportional valve 54b installed on the pilot line 144b of the operating device 45a for the boom 8, which reduces the pilot pressure (first control signal) in the pilot line 144b based on a control signal from the controller 40 and outputs it.

[0041] Furthermore, the front control hydraulic unit 160 is provided on the pilot lines 145a and 145b for the arm 9 and includes pressure sensors 71a and 71b that detect pilot pressure (first control signal) as the amount of operation of the operating lever 1b and output it to the controller 40, an electromagnetic proportional valve 55b installed on the pilot line 145b that reduces and outputs pilot pressure (first control signal) based on a control signal from the controller 40, and an electromagnetic proportional valve 55a installed on the pilot line 145a that reduces and outputs pilot pressure (first control signal) in the pilot line 145a based on a control signal from the controller 40.

[0042] Furthermore, the front control hydraulic unit 160 is provided on the pilot lines 146a and 146b for the bucket 10 and includes pressure sensors 72a and 72b that detect pilot pressure (first control signal) as the amount of operation of the operating lever 1a and output it to the controller 40, electromagnetic proportional valves 56a and 56b that reduce and output pilot pressure (first control signal) based on the control signal from the controller 40, electromagnetic proportional valves 56c and 56d whose primary port side is connected to the pilot pump 49 and which reduce the pilot pressure from the pilot pump 49 and output it, and shuttle valves 83a and 83b that select the high-pressure side of the pilot pressure in the pilot lines 146a and 146b and the control pressure output from the electromagnetic proportional valves 56c and 56d and guide it to the hydraulic drive unit 152a and 152b of the flow control valve 15c.

[0043] Furthermore, the front control hydraulic unit 160 is provided on the pilot lines 143a and 143b for the tilt mechanism 17 and includes pressure sensors 73a and 73b that detect pilot pressure (first control signal) as the amount of operation of the operating pedal 1c and output it to the controller 40, electromagnetic proportional valves 53a and 53b that reduce and output pilot pressure (first control signal) based on the control signal from the controller 40, electromagnetic proportional valves 53c and 53d whose primary port side is connected to the pilot pump 49 and which reduce the pilot pressure from the pilot pump 49 and output it, and shuttle valves 84a and 84b that select the high-pressure side of the pilot pressure in the pilot lines 143a and 143b and the control pressure output from the electromagnetic proportional valves 56c and 56d and guide it to the hydraulic drive units 156a and 156b of the flow control valve 15g. Note that in Figure 3, the connection lines between the pressure sensors 70, 71, 72, and 73 and the controller 40 are omitted for space reasons.

[0044] Solenoid proportional valves 53a, 53b, 54b, 55a, 55b, 56a, and 56b have their maximum opening when de-energized, and their opening decreases as the current, which is the control signal from controller 40, increases. On the other hand, solenoid proportional valves 53c, 53d, 54a, 56c, and 56d have an opening of 0 (zero) when de-energized, and have an opening when energized, and their opening increases as the current (control signal) from controller 40 increases. Thus, the opening of each solenoid proportional valve 53, 54, 55, and 56 corresponds to the control signal from controller 40.

[0045] In the front control hydraulic unit 160 configured as described above, when the controller 40 outputs a control signal to drive the electromagnetic proportional valves 53c, 53d, 54a, 56c, and 56d, a pilot pressure (second control signal) can be generated even when there is no operator operation on the corresponding operating devices 45a, 46a, and 48, thereby forcibly generating boom raising, bucket clouding, bucket dumping, tilt right rotation, and tilt left rotation operations. Similarly, when the controller 40 drives the electromagnetic proportional valves 53a, 53b, 54b, 55a, 55b, 56a, and 56b, a pilot pressure (second control signal) can be generated that is less than the pilot pressure (first control signal) generated by the operator operation of the operating devices 45a, 45b, 46a, and 48, thereby forcibly reducing the speed of boom lowering, arm clouding / dumping, bucket clouding / dumping, and tilt right rotation / left rotation from the values ​​set by the operator operation.

[0046] In this embodiment, among the control signals for the flow control valves 15a, 15c, and 15g, the pilot pressure generated by the operation of the operating devices 45a, 45b, 46a, and 48 is referred to as the "first control signal." Furthermore, among the control signals for the flow control valves 15a, 15c, and 15g, the pilot pressure generated by correcting (reducing) the first control signal by driving the electromagnetic proportional valves 53a, 53b, 54b, 55a, 55b, 56a, and 56b with the controller 40, and the pilot pressure newly generated separately from the first control signal by driving the electromagnetic proportional valves 53c, 53d, 54a, 56c, and 56d with the controller 40 are referred to as the "second control signal."

[0047] The second control signal is generated when the speed of the control point of the work implement 1A generated by the first control signal violates a predetermined condition, and is generated as a control signal that generates a speed of the control point of the work implement 1A that does not violate the predetermined condition. In the case where the first control signal is generated for one hydraulic drive unit of the same flow control valve 15a~15c,15g and the second control signal is generated for the other hydraulic drive unit, the second control signal is preferentially applied to the hydraulic drive unit, and the second control signal is input to the other hydraulic drive unit by blocking the first control signal with an electromagnetic proportional valve. Therefore, among the flow control valves 15a~15c,15g for which the second control signal has been calculated, control is performed based on the second control signal; for which the second control signal has not been calculated, control is performed based on the first control signal; and for which neither the first nor the second control signal has been generated, control (drive) is not performed. With the first and second control signals defined as described above, the MC can also be described as the control of the flow control valves 15a~15c,15g based on the second control signal.

[0048] In Figure 6, the controller 40 includes an input interface 91, a central processing unit (CPU) 92 which is a processor, a read-only memory (ROM) 93 and a random access memory (RAM) 94 which are storage devices, and an output interface 95.

[0049] The input interface 91 receives signals from the attitude information detection device 50, which includes angle sensors 30-32, 34 and a vehicle body tilt angle sensor 33; signals from the target surface setting device 51, which is a device for setting the target surface 700; signals from the GNSS antenna 16; and signals from the operator operation detection device 52a, which includes pressure sensors 70a, 70b, 71a, 71b, 72a, 72b, 73a, and 73b. These signals are then converted into a format that the CPU 92 can process.

[0050] ROM93 is a recording medium that stores a control program for executing MC and MG, including the processing described later, and various information necessary for executing said processing. CPU92 performs predetermined calculation processing on signals received from input interface 91, ROM93, and RAM94 according to the control program stored in ROM93. Output interface 95 creates an output signal according to the calculation result of CPU92 and outputs this signal to display device 57 and electromagnetic proportional valves 54, 55, and 56, thereby controlling the display on display device 57 and the operation of work machine 1A.

[0051] Note that the controller 40 in Figure 6 is equipped with semiconductor memory, namely ROM 93 and RAM 94, as storage devices. However, any storage device can be substituted, and for example, a magnetic storage device such as a hard disk drive may also be used.

[0052] Figure 8 is a functional block diagram showing the processing steps of the controller.

[0053] As shown in Figure 8, the controller 40 includes an operation amount calculation unit 43a, a posture calculation unit 43b, a target surface calculation unit 43c, a target velocity calculation unit 43d, an excavation avoidance determination unit 43e, a front MC velocity calculation unit 43f, a tilt MC velocity calculation unit 43g, a target pilot pressure calculation unit 43h, a valve command calculation unit 43i, and a display control unit 374a. The target pilot pressure calculation unit 43h and the valve command calculation unit 43i are collectively referred to as the actuator control unit 81.

[0054] The control amount calculation unit 43a calculates the control amounts of the control devices 45a, 45b, 46a, and 48 (control levers 1a, 1b, and 1c) based on the input from the operator operation detection device 52a. The control amounts of the control devices 45a, 45b, 46a, and 48 can be calculated from the detected values ​​of the pressure sensors 70, 71, 72, and 73. As shown in Figure 8, the boom raising control amount is calculated from the detected value of pressure sensor 70a, the boom lowering control amount from the detected value of pressure sensor 70b, the arm cloud (arm pulling) control amount from the detected value of pressure sensor 71a, the arm dump (arm pushing) control amount from the detected value of pressure sensor 71b, the bucket cloud (bucket pulling) control amount from the detected value of pressure sensor 72a, the bucket dump (bucket pushing) control amount from the detected value of pressure sensor 72b, the tilt left rotation control amount from the detected value of pressure sensor 73a, and the tilt right rotation control amount from the detected value of pressure sensor 73b. The manipulated variables converted from the detected values ​​of the pressure sensors 70, 71, 72, and 73 are output to the target velocity calculation unit 43d.

[0055] Note that the method for calculating the manipulated amount using pressure sensors 70, 71, 72, and 73 is just one example. For example, the system may be configured to detect the manipulated amount of the operating levers of each operating device 45a, 45b, 46a, and 48 using position sensors (e.g., rotary encoders) that detect the rotational displacement of the operating levers. Alternatively, instead of calculating the operating speed from the manipulated amount, stroke sensors may be installed to detect the extension and retraction amounts of each hydraulic cylinder 5, 6, 7, and 14, and the operating speed of each cylinder may be calculated based on the time change of the detected extension and retraction amounts.

[0056] The attitude calculation unit 43b calculates the attitude of the work machine 1A in the local coordinate system (shovel reference coordinates) and the position of the tip of the bucket 10 based on information from the attitude information detection device 50. The attitude calculation unit 43b calculates the tip center position (Xtc, Ytc, Ztc), tip right end position (XtR, YtR, ZtR), tip left end position (XtL, YtL, ZtL), rear end center position (Xbc, Ybc, Zbc), rear right end position (XbR, YbR, ZbR), and rear left end position (XbL, YbL, ZbL) of the bucket 10.

[0057] Furthermore, if the attitude calculation unit 43b requires the attitude of the work machine 1A in the global coordinate system and the position of the tip of the bucket 10, it calculates the position and attitude of the upper rotating body 12 in the global coordinate system from the signal of the GNSS antenna 16 and converts the coordinates in the local coordinate system to global coordinates.

[0058] The target surface calculation unit 43c calculates the position information of the target surface 700 based on the information from the target surface setting device 51 and stores it in the RAM 94. In this embodiment, as shown in Figure 7, the cross-sectional shape obtained by cutting the three-dimensional target surface with the plane on which the work machine 1A moves (the operating plane of the work machine) is used as the target surface 700 (two-dimensional target surface).

[0059] The target speed calculation unit 43d determines whether it is an excavation operation or an avoidance operation, and calculates the target speed (limit speed) for each hydraulic cylinder 5, 6, 7, 14 during leveling control (area limiting control), stop control, and tilt MC control, which determine the front MC speed.

[0060] Figure 9 is a diagram that extracts and shows the details of the processing functions of the target velocity calculation unit along with related functions.

[0061] The excavation avoidance determination unit 43e is a calculation unit that determines whether to perform a normal excavation operation or an avoidance operation to avoid interference with the target surface, based on the operation amount calculation unit 43a, attitude calculation unit 43b, and target surface calculation unit 43c, respectively. Here, a normal excavation operation means an operation in which the bucket line follows the target surface while the tilt cylinder 14 is movable and excavation is performed according to the target surface.

[0062] Figure 10 is a flowchart showing the processing details of the excavation avoidance action determination process.

[0063] In Figure 10, the excavation avoidance determination unit 43e first determines whether the front operating pressure Pi (i.e., the operating pressure applied to the boom 8, arm 9, and bucket 10) is greater than 0.7 MPa (step S100).

[0064] If the result of the determination in step S100 is NO, that is, if the front operating pressure Pi is 0.7 MPa or less, it is considered that no drilling operation is being performed and the bucket 10 does not interfere with the target surface, and commands for the normal drilling operation mode (described later) are output to the front MC speed calculation unit 43f and the tilt MC speed calculation unit 43g (step S101), and the drilling avoidance operation determination process is repeated.

[0065] Furthermore, if the result of the determination in step S100 is YES, that is, if the front operating pressure Pi is greater than 0.7 MPa, it is considered that excavation is being performed, and it is determined whether the inclination of the target surface at the predicted point up to a distance L in the direction in which the front is excavating is greater than the bucket tilt angle of the tilt cylinder 14 at the stroke end (step S110).

[0066] In step S110, the tilt angle value measured in advance at the stroke end is used as a set value, and the determination is made by comparing this set value with the inclination of the target surface. Furthermore, the calculation of the attitude of the predicted positions p1, p2, ..., pn (where n is a positive integer) in the section up to a distance L is performed by assuming, for example, that the cutting edge of the bucket 10 is at each position from the current position at intervals l up to distance L, and then calculating the attitude (including the tilt attitude) of the boom 8, arm 9, and bucket 10 by working backward from the assumed position information. For the tilt attitude, the set value measured at the stroke end of the tilt cylinder 14 is used as the upper limit for the calculation.

[0067] If the determination result in step S110 is NO, that is, if the slope of the target surface at the predicted points p1, p2, ..., pn (where n is a positive integer) up to a distance L in the excavation direction is less than or equal to the bucket tilt angle, the bucket 10 is considered not to interfere with the target surface, and commands for the normal excavation operation mode (described later) are output to the front MC speed calculation unit 43f and the tilt MC speed calculation unit 43g (step S101), and the excavation avoidance operation determination process is repeated.

[0068] Furthermore, if the determination result in step S110 is YES, that is, if the slope of the target surface at predicted points p1, p2, ..., pn (where n is a positive integer) up to a distance L in the excavation direction is greater than the bucket tilt angle, the bucket is considered to interfere with the target surface, and a command for avoidance operation mode (described later) is output to the front MC speed calculation unit 43f and the tilt MC speed calculation unit 43g (step S120), and the excavation avoidance operation determination process is repeated.

[0069] Here, we will explain an example of the operation in the excavation avoidance action determination process.

[0070] Figure 11 shows an example of the bucket position in the current position and the bucket position in the predicted position after moving a certain distance in the drilling direction, along with the target plane. Figure 12 compares the views from arrow A and arrow B in Figure 11.

[0071] In Figure 11, the direction from left to right is the excavation direction, and the target surface rises towards the back, and the slope (angle of rise) of the target surface increases as you move to the right. That is, as shown in Figure 12, the slope of the target surface is greater in the direction of arrow B than in the direction of arrow A in Figure 11.

[0072] The excavation avoidance action determination process shown in Figure 11 illustrates a case where the front of the vehicle is defined at point a (current position) and at point b (pn: predicted position), which is assumed to be the position when the vehicle moves a distance L forward in the excavation direction from point a, and the toe position and front attitude of each point p1, p2, ..., pn (n is a positive integer) at intervals of l are calculated.

[0073] As shown in Figure 12, the view from arrow A in Figure 11, i.e., point a (current position) as seen from inside the driver's cab 12a, indicates that the inclination of the target surface is not greater than the tilt angle of the stroke end, and MC control is possible so that the tip of the bucket 10 (one side forming the tip) coincides with the target surface.

[0074] On the other hand, at point b (predicted position) as seen from inside the cab 12a, as shown by arrow B in Figure 11 in Figure 12, the inclination of the target surface is greater than the tilt angle of the stroke end, and if no avoidance maneuver is performed, it is predicted that a part of the bucket 10 will interfere with the target surface (penetrate below the target surface). This corresponds to the case in step S110 of the excavation avoidance operation determination process (Figure 10) where the inclination is greater than the angle of the stroke end of the tilt cylinder 14 at a distance L in the excavation direction. In other words, in this case, the excavation avoidance determination process in Figure 10 outputs a command for the avoidance operation mode. Here, the distance L is set to a length (for example, 1m) that allows for gradual avoidance when detecting a point on the target surface with an inclination angle greater than the tilt angle at the stroke end and performing an avoidance maneuver. The interval l is set to an interval (for example, 0.1m) that allows for more detailed acquisition of information on the front attitude and the inclination of the target surface.

[0075] Figure 13 shows an example where the inclination of the target surface in the cross-sectional direction, as viewed from the operator's cabin, increases as the excavation progresses.

[0076] Figure 13 illustrates a case where, starting from a position (current position) where the work machine 1A is extended directly facing the slope S (target surface), the arm is pulled back while rotating to the left to perform a downward cut in the leftward diagonal direction (excavation direction). In this case, rotating relative to the slope S changes the inclination of the target surface (slope S) relative to the bucket 10 to an increased degree, and further pulling operations may cause the bucket 10 to interfere with the target surface depending on the inclination of the slope S.

[0077] In the excavation avoidance determination process in this embodiment (Figure 10), if it is predicted that the bucket 10 will interfere with the target surface during excavation, the system transitions to an avoidance operation mode (step S120 in Figure 10), and controls the work machine 1A in a direction that prevents the bucket 10 from interfering with the target surface, i.e., in a direction that moves the bucket 10 away from the target surface. However, even in the avoidance operation mode, if the front operation is less than 0.7 MPa, no operation is input, and the control to move away from the target surface is stopped. Furthermore, when the system transitions to the avoidance operation mode and controls the work machine 1A in a direction that moves the bucket 10 away from the target surface, the operator is notified of the intention to control the bucket 10 to move away from the target surface, for example, by displaying it on the display device 57 or by sounding a buzzer (not shown).

[0078] Here, we will describe in detail the MC control in the normal excavation operation mode (see step S101 in Figure 10) and the MC processing in the avoidance operation mode (see step S120 in Figure 10).

[0079] (MC control in normal drilling operation mode) The calculation processes of the front MC speed calculation unit 43f and the tilt MC speed calculation unit 43g in the normal drilling operation mode will be described below.

[0080] Figure 14 shows the velocity vectors of the bucket tip in each state of the normal drilling operation mode.

[0081] In the normal excavation operation mode, the front MC speed calculation unit 43f receives the operating amounts of the operating devices 45a, 45b, and 46a from the operating amount calculation unit 43a and calculates the target speed of each hydraulic cylinder 5, 6, and 7. Furthermore, it determines the target speed vector Vc of the bucket tip and rear end from the target speed of each hydraulic cylinder 5, 6, and 7, the tip and rear end positions of the bucket determined by the attitude calculation unit 43b, and the dimensions of each part of the work machine 1A stored in the ROM 93.

[0082] As shown in Figure 14, as the distance H1 between the bucket tip and the target surface 700 (target surface distance) approaches zero, control (direction change control) is performed to convert the bucket tip velocity vector to Vca by correcting the target speed of the necessary hydraulic cylinders among hydraulic cylinders 5, 6, and 7 so that the component Vcy perpendicular to the target surface 700 in the target velocity vector Vc of the bucket tip becomes zero. When the target surface distance H1 is zero, the velocity vector Vca consists only of the component Vcx parallel to the target surface 700. This ensures that the tip of the bucket 10 (control point) is positioned on or above the target surface 700.

[0083] When the MC control is designed to perform direction change control using a combination of boom raising / lowering and arm cloud, if the velocity vector Vc includes a component in the direction approaching the target surface 700 (i.e., when the vector component Vcy perpendicular to the target surface 700 is negative), the front MC velocity calculation unit 43f calculates a target velocity for the boom cylinder 5 in the boom raising direction that cancels out that component. Also, if the velocity vector Vc includes a component in the direction away from the target surface 700 (i.e., when the vector component Vcy perpendicular to the target surface 700 is positive), it calculates a target velocity for the boom cylinder 5 in the boom lowering direction that cancels out that component. Furthermore, taking into account the response delay of the solenoid valves and structures for boom raising and boom lowering, the rate of increase of the target velocity of the arm cloud is limited and output immediately after arm cloud operation.

[0084] Furthermore, if the MC control is designed to perform direction change control using a combination of boom raising / lowering and arm dumping, when the velocity vector Vc includes a component in the direction approaching the target surface 700, the front MC velocity calculation unit 43f calculates a target velocity for the boom cylinder 5 in the boom raising direction that cancels out that component. Also, when the velocity vector Vc includes a component in the direction away from the target surface 700, it calculates a target velocity for the boom cylinder 5 in the boom lowering direction that cancels out that component. In addition, taking into account the response delay of the solenoid valves and structures for boom raising and boom lowering, the rate of increase of the target velocity of the arm cloud is limited and output immediately after the arm dumping operation. Furthermore, a target velocity for the bucket cylinder 7 is calculated in order to maintain a constant bucket posture at the start of excavation. Hereafter, MC control will be performed while maintaining a constant bucket posture.

[0085] Next, we will explain the calculations performed by the tilt MC speed calculation unit 43g.

[0086] The target tilt angle calculation unit 43g-1 of the tilt MC speed calculation unit 43g calculates the target tilt speed to match the tilt angle of the bucket 10 to the roll angle of the target surface.

[0087] Figures 15 and 16 show examples of bucket tilt motion relative to the target surface. Figure 17 shows the relationship between tilt angle deviation and tilt target velocity.

[0088] In Figures 15 and 16, the tilting motion of the bucket 10 is explained with the clockwise direction being the positive direction and the counterclockwise direction being the negative direction, as viewed from the driver's seat.

[0089] As shown in Figures 15 and 16, the target speed for the tilt angle is calculated according to the tilt angle deviation ΔTilt, which is the angular deviation from the line segment of the bucket cutting edge to the target terrain (target surface). As shown in Figure 17, the larger the tilt angle deviation ΔTilt is in the negative direction (counterclockwise direction), the larger the target speed becomes so that the leftward tilt rotation speed of the bucket 10 increases (see Figure 15). Also, the larger the tilt angle deviation ΔTilt is in the positive direction, the larger the target speed becomes so that the rightward rotation speed of the bucket 10 increases (see Figure 16).

[0090] In this way, the bucket's tilt angle matches the angle of the target surface, eliminating the need for manual adjustment of the tilt angle and thus improving work efficiency.

[0091] Furthermore, this target speed may be multiplied by a larger gain as the distance of the bucket from the tilt angle target surface increases, or a high speed may always be output unless the distance of the bucket from the target terrain falls below a certain threshold. By correcting the tilt target speed based on the distance of the bucket from the target surface, it is possible to adjust how close to the target surface the control to match the tilt angle of the bucket to the angle of the target surface becomes effective.

[0092] In the tilt MC speed calculation unit 43g shown in Figure 9, the condition for actually commanding the tilt Pi pressure boosting valve from the target tilt speed calculated from the target tilt angle calculation unit 43g-1 is that front operation is input. This is to prevent the tilt bucket from moving on its own when not being operated in the air, and is intended to automatically tilt to match the terrain when leveling operations are being performed by pulling / pushing the arm, rotating, etc., or when positioning is being performed by raising / lowering the boom, pulling / pushing the bucket, etc.

[0093] In Figure 9, the tilt MC speed calculation unit 43g-4 switches to the tilt target speed when the command speed is 0 mm / s due to front operation. However, it is also possible to smoothly transition to the tilt target speed gradually as the command speed increases from 0 mm / s according to the maximum value of the front operation.

[0094] With the above configuration, the tilt angle can be matched to the angle of the target surface when operating the front.

[0095] (MC control in avoidance operation mode) The calculation process of the front MC speed calculation unit 43f and the tilt MC speed calculation unit 43g when a command for avoidance operation mode is output from the excavation avoidance determination unit 43e will be described. Here, it is assumed that the inclination of the target surface at point b (predicted posture), which is a distance L away from the current point a (current posture) in the excavation direction, is greater than the tilt angle of the tilt cylinder 14 at the stroke end.

[0096] Figure 18 shows an example of the bucket position in the current attitude and the bucket position in the predicted attitude after moving a certain distance in the drilling direction, along with the target plane. Figure 19 is a view from arrow B in Figure 18. Figure 20 shows the target trajectory correction process.

[0097] In Figure 18, the direction from left to right is defined as the excavation direction, and the target surface rises towards the back, while the slope (angle of rise) of the target surface increases as you move to the right.

[0098] As shown in Figures 18 and 19, the front MC speed calculation unit 43f compares the tilt angle based on the predicted posture at point b calculated by the excavation avoidance determination unit 43e with the target surface angle, and calculates the bucket depth d when the target surface angle is greater than the angle at the stroke end of the tilt cylinder 14 and the bucket interferes with the target surface.

[0099] Next, as shown in Figure 20, the bucket cutting edge position is raised by the amount of the submersion d to determine the target bucket position at point b.

[0100] Figure 21 shows the corrected target trajectory when moving in the drilling direction from the bucket position in the current attitude to the bucket position in the predicted attitude. Figure 22 shows the view from arrow B in Figure 21.

[0101] As shown in Figures 21 and 22, the system calculates a corrected target trajectory from point a to point b so that one end of the bucket touches the target surface at point b, and corrects the target trajectory. Figure 21 illustrates the case where the shortest distance from point a to point b is calculated as a straight line, which is the corrected target trajectory. The corrected target speed of each cylinder at the front is calculated in the same way as in the normal drilling operation mode so as to follow the calculated corrected target trajectory.

[0102] In the tilt MC speed calculation unit 43g, during avoidance maneuvers, the tilt cylinder 14 adjusts the tilt angle so that the angle of the tip edge of the bucket 10 matches the angle of the target surface until it reaches the stroke end. When it reaches the stroke end, where the tilt angle can no longer be increased, it issues a command to set the target tilt angular velocity to 0 (zero) so that the tilt angle is fixed at the angle at the stroke end.

[0103] The effects of this embodiment, configured as described above, will now be explained.

[0104] In conventional technology, when the tilt cylinder reaches the stroke end and the inclination of the target surface near the bucket becomes even greater, the following problems arise. Specifically, in the above case, an attempt is made to control the tilt cylinder by calculating a tilt angle greater than the inclination angle reached at the stroke end as the target tilt angle, but because the stroke end has been reached, the tilt angle cannot rotate any further. Furthermore, in this state, if an attempt is made to avoid over-excavating the target surface by raising the bucket position using boom lifting compensation, the compensation after acquiring the bucket cutting edge position information is not fast enough, and there is a risk that the bucket will interfere with the target surface that is inclined more than that tilt angle.

[0105] In contrast, this embodiment comprises a multi-joint work machine consisting of a lower traveling body, an upper rotating body rotatably mounted relative to the lower traveling body, a plurality of driven members attached to the upper rotating body and rotatably connected, a plurality of hydraulic actuators that drive each of the plurality of driven members based on an operation signal, a bucket provided at the tip of the work machine which is a driven member and is equipped with a tilt cylinder, which is a hydraulic actuator for rotating it left and right around a tilt rotation axis perpendicular to the rotation axis relative to the work machine, a posture information detection device that detects posture information which is information related to the posture of the work machine, and based on the posture information detected by the posture information detection device, the left and right angles of the part of the bucket facing a predetermined target surface coincide with the target surface. The system includes a control device that outputs an operating signal to at least one of a plurality of hydraulic actuators, or performs region limiting control to correct the operating signal output to at least one of a plurality of hydraulic actuators, so that the bucket is located on or above the target surface. The control device is configured to control the bucket away from the target surface when performing region limiting control so that the control point of the bucket moves on the target surface, and when the tilt angle of the target surface becomes greater than the left-right tilt angle of one side of the bucket facing the target surface when the tilt cylinder has reached the stroke end. This makes it possible to avoid interference with the target surface even when the tilt cylinder has reached near the stroke end during excavation.

[0106] <Modified form of the first embodiment> A modified example of the first embodiment of the present invention will now be described.

[0107] In the first embodiment, the avoidance operation to avoid contact (intrusion) of the bucket 10 with the target surface was explained using an example of an avoidance operation by raising the boom. However, this modified example shows a case where the avoidance operation is performed by slewing.

[0108] In this modified example, in the hydraulic drive system of the first embodiment (see Figure 2), a hydraulic unit for swing control is connected between the operating device 46b for operating the swing hydraulic motor 4 and the shuttle valve, and control is performed by an electromagnetic proportional valve, thereby enabling avoidance maneuvers by swinging.

[0109] The other configurations are the same as in the first embodiment.

[0110] In this embodiment configured as described above, the same effects as in the first embodiment can be obtained.

[0111] Furthermore, the system may have both the function of avoidance by raising the boom, as in the first embodiment, and avoidance by slewing, as in this modified example. The system may be configured to compare the amount of correction required for avoidance of the bucket 10 by raising the boom and the avoidance by slewing, and select the one with the smaller movement amount (correction amount) as the avoidance operation.

[0112] <Other variations of the first embodiment> In the first embodiment and its modified form, the tilt operation is controlled by increasing or decreasing the hydraulic operating pressure Pi, but the tilt operation may also be controlled by increasing or decreasing the electrical signal associated with the operation of an electric lever.

[0113] <Note> It should be noted that the present invention is not limited to the embodiments described above, and includes various modifications and combinations that do not depart from the spirit of the invention. Furthermore, the present invention is not limited to having all the configurations described in the embodiments described above, and includes configurations in which some of the configurations are omitted. In addition, some or all of the above configurations, functions, etc. may be realized by designing, for example, an integrated circuit. Furthermore, each of the above configurations, functions, etc. may be realized in software by having a processor interpret and execute a program that realizes each function. [Explanation of symbols]

[0114] 1...Operating lever, 1A...Work implement, 1B...Vehicle body, 1c...Operating pedal, 2...Hydraulic pump, 2a...Regulator, 3...Travel hydraulic motor, 4...Slewing hydraulic motor, 5...Boom cylinder, 6...Arm cylinder, 7...Bucket cylinder, 8...Boom, 9...Arm, 10...Bucket (Tilt bucket), 11...Lower travel body, 12...Upper slewing body, 12a...Driver's cab, 13...Bucket link, 14...Tilt cylinder, 15...Flow control valve, 16...GNSS antenna, 17...Tilt mechanism, 18...Engine 23...Operating lever, 30...Boom angle sensor, 31...Arm angle sensor, 32...Bucket angle sensor, 33...Vehicle tilt angle sensor, 34...Tilt angle sensor, 39...Lock valve, 40...Controller (control device), 43a...Operation amount calculation unit, 43b...Attitude calculation unit, 43c...Target surface calculation unit, 43d...Target speed calculation unit, 43e...Excavation avoidance determination unit, 43f...Front MC speed calculation unit, 43g...Tilt MC speed calculation unit, 43g-1...Target tilt angle calculation unit, 43g-4...Tilt MC speed calculation unit, 4 3h...Target pilot pressure calculation unit, 43i...Valve command calculation unit, 45,46,47,48...Operating device, 49...Pilot pump, 50...Attitude information detection device, 51...Target surface setting device, 52a...Operator operation detection device, 53,54,55,56...Solenoid proportional valve, 57...Display device, 70,71,72,73...Pressure sensor, 81...Actuator control unit, 82a...Shuttle valve, 83...Shuttle valve, 91...Input interface, 92...Central processing unit (CPU), 93...Read-only memo ROM, 94...Random Access Memory (RAM), 95...Output Interface, 100...Hydraulic Excavator, 143, 144, 145, 146, 147, 148...Pilot Line, 149b...Pilot Line, 150a...Hydraulic Drive Unit, 152a, 152b...Hydraulic Drive Unit, 156a, 156b...Hydraulic Drive Unit, 159...Pilot Line, 160...Front Control Hydraulic Unit, 162...Shuttle Block, 170...Pump Line, 374a...Display Control Unit, 700...Target Surface

Claims

[Claim 1] Lower running body and An upper slewing body is provided so as to be rotatable relative to the lower traveling body, A multi-jointed work machine consisting of a plurality of driven members attached to the upper rotating body and rotatably connected, A plurality of hydraulic actuators that drive the plurality of driven members based on an operation signal, A bucket provided at the tip of the work machine is a driven member, which includes a tilt cylinder, a hydraulic actuator for rotating in the left-right direction about a tilt pivot axis perpendicular to the pivot axis of the work machine, A posture information detection device for detecting posture information, which is information relating to the posture of the aforementioned work machine, The system includes a control device that, based on the attitude information detected by the attitude information detection device, outputs the operation signal to at least one of the plurality of hydraulic actuators, or performs region limiting control to correct the operation signal output to at least one of the plurality of hydraulic actuators, so that the left-right angle of the portion of the bucket facing a predetermined target surface coincides with the target surface, and the bucket is positioned on or above the target surface. When the control device performs the area limiting control so that the control point of the bucket moves on the target surface, it determines whether the inclination of the target surface at a predicted position up to a predetermined distance ahead in the direction in which the bucket is moving from the current position of the bucket is greater than the left-right inclination angle of one side of the bucket facing the target surface when the tilt cylinder has reached its stroke end. If the inclination of the target surface is less than or equal to the left-right inclination angle of one side of the bucket facing the target surface, the control device performs the excavation operation so that the control point of the bucket moves on the target surface. The work machine is characterized in that, if the inclination of the target surface is greater than the left-right inclination angle of one side of the bucket facing the target surface, the amount of descent of the bucket into the target surface when the control point of the bucket is located on the target surface at the predicted position is calculated, the target position of the bucket is determined to move the bucket away from the target surface at the predicted position by the calculated amount of descent, and avoidance control is performed so that one end of the side of the bucket facing the target surface moves along a straight line connecting the determined target position of the bucket and the current position of the bucket.

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