Work machine

Abstract

This work machine: calculates a requested operation for a front work device on the basis of an operating amount of an operating lever device; determines whether an excavation instruction associated with the operating lever device is an operation for requesting construction of a lower surface, which is a construction target surface located below a bucket, or an operation for requesting construction of a side surface, which is a construction target surface located at the side of the bucket; and if it is determined that the excavation instruction is an operation for requesting construction of the lower surface, outputs an operation command value for an actuator that permits a jacked-up state in which a front portion of a traveling body is lifted up, and if it is determined that the excavation instruction is an operation for requesting construction of the side surface, outputs the operation command value of the actuator so as to avoid the jacked-up state. This makes it easy for the work machine to exhibit its inherent wall surface excavation power.

Description

Working machine

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

[0002] A working machine having a front working device attached to a vehicle body is widely used for road construction, construction works, civil engineering, dredging, demolition works and the like. For example, a hydraulic excavator having a front working device composed of a boom, an arm, a bucket and the like is one example.

[0003] As this type of hydraulic excavator, there is one that has a function of detecting the occurrence of slip and controlling the turning operation to suppress the slip of the traveling body when slip of the traveling body occurs due to the turning operation (Patent Document 1).

[0004] Japanese Unexamined Patent Publication No. 2021-14746

[0005] Some hydraulic excavators are equipped with a so-called machine control function in which, for example, when an operator operates an arm, a boom or the like is automatically driven as necessary so that the bucket moves along a preset construction target surface. The shape of the construction target surface varies, and may include a lower surface constructed by the tip of the bucket teeth or the like and a side surface constructed by the side portion of the bucket or the like. For example, when excavating a trench, while constructing the lower surface, that is, the bottom surface of the trench by the operation of the boom and the arm, the side surface, that is, the side surface of the trench is constructed while combining turning operations. In such a case, if the reaction force of wall surface excavation (side surface excavation) is large, slip may occur between the traveling body of the hydraulic excavator and the ground. When the traveling body slips, the operator has to interrupt the excavation work to correct the orientation of the traveling body, which may reduce the operator's work efficiency.

[0006] On the other hand, by applying the technology described in Patent Document 1, when a large wall excavation force acts and slip of the traveling body occurs, the turning operation can be controlled to suppress the slip amount of the traveling body.

[0007] However, during the trench excavation work described above, if the lower surface is hard or the excavation load on the lower surface is large, the excavation reaction force on the lower surface can cause the front of the vehicle to lift up, resulting in a state where only the rear of the vehicle is in contact with the ground, a so-called jacked-up state. In this jacked-up state, the contact area of ​​the vehicle with the ground is smaller than in the normal state without jacking up, making it more susceptible to slippage.

[0008] Therefore, when the technology described in Patent Document 1 is applied, although the amount of slip of the vehicle can be suppressed by controlling the rotational movement even in the jacked-up state, it is not possible to escape the state in which the vehicle is prone to slipping. As a result, it is conceivable that the wall excavation force inherent in hydraulic excavators cannot be fully utilized, leading to a decrease in work efficiency.

[0009] The objective of this invention is to provide a work machine that can exert its inherent wall-digging power.

[0010] To achieve the above objective, the present invention provides a vehicle, a vehicle, a vehicle mounted on the vehicle so as to be rotatable in the left-right direction, a front work device having a bucket and being swingably mounted on the vehicle, an actuator for driving the vehicle and the front work device respectively, an operating lever device for operating the actuator, a controller that calculates a required operation for the front work device based on the operating signal of the operating lever device and calculates an operation command value for the actuator so as not to exceed the construction target surface based on the required operation, and a drive device that drives the actuator according to the operation command value from the controller. In a work machine, the controller determines, based on the operation signal from the operating lever device, whether the excavation instruction is an operation requesting construction on the lower surface, which is the construction target surface located below the bucket, or an operation requesting construction on the lateral surface, which is the construction target surface located to the side of the bucket. If it is determined that the excavation instruction is an operation requesting construction on the lower surface, the controller outputs an operation command value for the actuator that allows a jack-up state in which the front of the traveling body is lifted. If it is determined that the excavation instruction is an operation requesting construction on the lateral surface, the controller outputs an operation command value for the actuator that avoids the jack-up state.

[0011] According to the present invention, it is possible to make it easier for the work machine to exert its inherent wall-cutting power.

[0012] A side view showing the construction process on the lower surface of a hydraulic excavator, which is an example of a work machine according to one embodiment of the present invention. A plan view showing the construction process on the lower surface of a hydraulic excavator, which is an example of a work machine according to one embodiment of the present invention. A side view showing the configuration of the hydraulic excavator shown in Figures 1A and 1B. A functional block diagram showing an example of the configuration of the drive system of the hydraulic excavator shown in Figures 1A and 1B. A functional block diagram of the controller provided in the hydraulic excavator shown in Figures 1A and 1B. An explanatory diagram of an example of a method for calculating a requested motion vector in response to operator operation. An explanatory diagram of Example 1 of work priority determination. An explanatory diagram of Example 2 of work priority determination. An explanatory diagram of Example 2 of work priority determination. Diagram illustrating the operation of hydraulic excavator 1 when downward excavation is prioritized and the jack-up state is permitted. Diagram illustrating the operation of hydraulic excavator 1 when lateral excavation is prioritized and the jack-up state is prohibited. Diagram illustrating an example of a method for measuring the reaction force of lateral wall excavation. Diagram illustrating an example of a method for predicting slip occurrence. Flowchart showing the calculation procedure of operation command values ​​by the controller.

[0013] Embodiments of the present invention will be described below with reference to the drawings. In each drawing, the same or corresponding elements are denoted by the same reference numerals, and redundant explanations are omitted as appropriate.

[0014] -Applicable Subjects- Figure 1A is a side view showing the construction process on the lower surface of a hydraulic excavator, which is an example of a work machine according to one embodiment of the present invention, and Figure 1B is a plan view showing the construction process on the side of a hydraulic excavator, which is an example of a work machine according to the present invention. In Figure 1A, the left and right directions are the front and rear directions of the hydraulic excavator 1, and in Figure 1B, the left and right directions are the left and right directions of the hydraulic excavator 1. The lower surface is the construction target surface located below the bucket during excavation, in other words, the construction target surface where soil is excavated and constructed by the lower part of the bucket (e.g., the tines). An example of the lower surface is the bottom surface (upward-facing surface) of the trench to be excavated. The side surface is the construction target surface located to the side of the bucket during excavation, in other words, the construction target surface where soil is excavated and constructed by the side of the bucket. An example of the side surface is the inner surface of the trench to be excavated (the surface facing left and right when viewed from the hydraulic excavator 1).

[0015] As shown in Figure 1A or Figure 1B, the hydraulic excavator 1 to which the present invention is applied is equipped with a so-called MC (machine control) function that, for example, when an operator operates the arm 21, the boom 20 and other components are automatically controlled as needed so that the bucket 22 moves along the downward surface S1 or the side surface S2, which are preset construction target surfaces, without exceeding them.

[0016] As shown in Figure 1A, when the lower part of the bucket 22 (for example, the tip 22a) excavates the ground and cuts out the lower surface S1, if the operator moves the arm 21 in the direction of pulling it towards the slewing body 3, the boom 20 is automatically controlled so that the trajectory of the lower part of the bucket 22, which draws a circle when the MC is not working, follows the lower surface S1. In some cases, the bucket 22 is also automatically controlled to maintain a constant posture (angle with respect to the lower surface S1).

[0017] As shown in Figure 1B, when excavating the ground with the side of the bucket 22 (for example, the side edge 22b) to cut out a lateral surface S2, if the operator moves the arm 21 in the direction of pulling it towards the slewing body 3, the slewing body 3 is automatically controlled so that the trajectory of the side of the bucket 22, which moves away from the lateral surface S2 when the MC is not working, follows the lateral surface S2. In some cases, the boom 20 and bucket 22 are also automatically controlled to maintain a constant distance and posture of the bucket 22 relative to the downward surface S1.

[0018] The construction target surface, i.e., the lower surface S1 and the lateral surface S2, may be a so-called 2D construction target surface having coordinate information only in the front-to-back direction of the hydraulic excavator 1, or it may be a so-called 3D construction target surface having coordinate information in both the front-to-back and left-to-right directions. Furthermore, the lower surface S1 and the lateral surface S2 may be set in a local coordinate system based on the hydraulic excavator 1, or they may be set in a global coordinate system based on the construction site or the Earth. Note that the construction target surface is not limited to the lower surface S1 and the lateral surface S2, but may also be a wall surface located in front of or behind the hydraulic excavator 1 and extending vertically.

[0019] -Work Machine- Figure 2 is a side view showing the configuration of the hydraulic excavator 1. An example of the configuration of a hydraulic excavator will be explained using Figure 2. The hydraulic excavator 1 shown in Figure 2 is equipped with a front working device 2, a traveling body 4, and a rotating body 3.

[0020] The front working device 2 is attached to the slewing body 3 and is configured to rotate freely in the vertical direction around the connection point with the slewing body 3. The slewing body 3 is mounted on the traveling body 4 and rotates freely in the left-right direction around the connection point with the traveling body 4. The front working device 2 comprises a boom 20 with one end connected to the slewing body 3, an arm 21 with one end connected to the boom 20, and a bucket 22 with one end connected to the arm 21. The front working device 2 also comprises a boom cylinder 20A with both ends connected to the boom 20 and the slewing body 3, respectively, an arm cylinder 21A with both ends connected to the arm 21 and the boom 20, respectively, and a bucket cylinder 22A with both ends connected to the bucket link 22L and the arm 21. Each of these components is rotatable in the vertical plane around the connection point with the mating component.

[0021] The boom cylinder 20A, arm cylinder 21A, and bucket cylinder 22A are multiple actuators that drive the front work device 2. These boom cylinder 20A, arm cylinder 21A, and bucket cylinder 22A are all hydraulic cylinders, and their respective extension and retraction movements rotate and drive the boom 20, arm 21, and bucket 22, respectively. The bucket 22 is a detachable attachment and can be replaced with other attachments (not shown), such as a grapple, breaker, ripper, magnet, rotary tilt bucket, or lawnmower, depending on the work purpose.

[0022] The vehicle 4 comprises a travel motor 41 and tracks 45 driven by the travel motor 41. The travel motor 41 is a hydraulic motor. The operator can operate the travel motor 41 and move the hydraulic excavator 1 by operating the operating lever device 33, which will be described later. The vehicle 4 is not limited to a crawler type with tracks 45, but may also be a wheeled type.

[0023] The slewing body 3 also includes a main frame 31, a cab 32, a controller 34, a drive unit 35, a driving unit 36, and a positioning device 250. The main frame 31 is the base frame of the slewing body 3 and is also called the slewing frame. The main frame 31 is rotatably connected to the upper part of the traveling body 4 via a slewing wheel. Other structures of the slewing body 3, such as the cab 32, are directly or indirectly supported by the main frame 31. The cab 32 houses a driver's seat, an operating lever device 33 for operating the corresponding actuator, a user interface (U / I) 100, and a target surface setting device (target surface management device) 2000. The controller 34 will be described later with reference to Figure 4. The drive unit 35, driving unit 36, positioning device 250, operating lever device 33, user interface 100, and target surface setting device 2000 will be described next with reference to Figure 3.

[0024] -Drive System- Figure 3 is a functional block diagram showing an example of the drive system configuration of the hydraulic excavator 1. As shown in Figure 3, the controller 34 is electrically connected to the operating lever device 33, attitude measuring device 200, load measuring device 210, positioning device 250, drive unit 35, target surface setting device 2000, and user interface 100. The target surface setting device 2000 is also electrically connected to the user interface 100. The drive unit 35 is hydraulically connected to the driving device 36 and actuator 2ACT. Each block will be described below. The controller 34 will be described later using Figure 4.

[0025] <Operating Lever Device> The operating lever device 33 consists of an operating lever and an operating amount sensor that detects the amount of operation of the operating lever. The operating lever is operated by tilting it from the neutral position in a predetermined operating direction. The operating amount sensor consists of, for example, a potentiometer that detects the amount of tilt of the operating lever as the operating amount, or a pressure sensor that detects the pilot pressure output to the corresponding solenoid valve in response to the operation as the operating amount. An operating lever device 33 is provided for each actuator to be operated, and each is equipped with an operating amount sensor corresponding to the actuator being operated. However, the operating lever may be used for the operation of multiple actuators. For example, the slewing operation and arm operation may be shared by one operating lever, and the boom operation and bucket operation may be shared by one operating lever. For example, tilting one operating lever forward or backward causes the slewing motor 3A (Figure 3) that drives the slewing body 3 to rotate forward or backward according to the operating direction, and tilting it left or right causes the arm to extend or retract according to the operating direction. The operating speed of the actuator also depends on the amount of operation of the corresponding operating lever device 33. The controller 34 calculates the requested operation that the operator requests from the target actuator, namely the operating direction and operating speed of the target actuator, based on the output of the manipulated amount sensor.

[0026] The operating lever device 33 is, for example, an electric lever device, but other types are also acceptable as long as they have equivalent functionality, such as a hydraulic pilot type or a remote-controlled type.

[0027] <Attitude Measurement Device> The attitude measurement device 200 is a device that detects the attitude of the front work device 2, the rotating body 3, and the traveling body 4, and is composed of attitude sensors 20S, 21S, 22S, 30S, and 31S.

[0028] Attitude sensor 20S is a sensor that detects the attitude of boom 20 and is attached to boom 20 as illustrated in Figure 2. Attitude sensor 21S is a sensor that detects the attitude of arm 21 and is attached to arm 21. Attitude sensor 22S is a sensor that detects the attitude of bucket 22 and is attached to bucket link 22L. Attitude sensors 20S-22S are, for example, an IMU (Inertial Measurement Unit) and detect the angle relative to the ground (or a corresponding angle) of boom 20, arm 21, and bucket 22 as attitude information. The IMU is, for example, composed of an angular velocity sensor and an acceleration sensor.

[0029] However, angle sensors may be used instead of the IMU as attitude sensors 20S, 21S, and 22S. In this case, for example, the relative angle of the boom 20 with respect to the slewing body 3, the relative angle of the arm 21 with respect to the boom 20, and the relative angle of the bucket 22 with respect to the arm 21 are detected as attitude information for each. Alternatively, stroke sensors that detect the stroke of the boom cylinder 20A, arm cylinder 21A, and bucket cylinder 22A may be used as attitude sensors 20A-22S, and the attitude information for the boom 20, arm 21, and bucket 22 may be calculated based on the extension and retraction amount of each cylinder.

[0030] Attitude sensors 30S and 31S are sensors for detecting the attitude of the rotating body 3 and the driving body 4, and are attached to the rotating body 3 as illustrated in Figure 2. The attitude sensor 30S can use the same IMU as the attitude sensor 20S, and the angle of the rotating body 3 relative to the ground is detected as attitude information of the rotating body 3. The attitude sensor 31S uses an angle sensor that detects the relative angle in the turning direction between the driving body 4 and the rotating body 3.

[0031] Since the boom 20, arm 21, bucket 22, boom cylinder 20A, arm cylinder 21A, bucket cylinder 22A, bucket link 22L, and slewing body 3 are all rotatably connected to each other, the posture of the boom 20, arm 21, bucket 22, and slewing body 3 can be estimated from the mechanical linkage based on the outputs of the posture sensors 20S, 21S, 22S, 30S, and 31S. In addition, the ground angle of the traveling body 4 is also calculated and detected as posture information of the traveling body 4 from the ground angle of the slewing body 3 detected by the posture sensor 30S and the relative angle between the traveling body 4 and the slewing body 3 detected by the posture sensor 31S.

[0032] <Load Measurement Device> The load measurement device 210 detects the load of actuators 2ACT, such as the boom cylinder 20A, arm cylinder 21A, bucket cylinder 22A, and swing motor 3A. Specifically, in this embodiment, the load measurement device 210 is composed of pressure sensors 20RP, 20BP, 21RP, 21BP, 22RP, 22BP, 3LP, and 3RP. Pressure sensor 20RP detects the pressure in the rod-side oil chamber of the boom cylinder 20A or the hydraulic piping connected thereto. Pressure sensor 20BP detects the pressure in the bottom-side oil chamber of the boom cylinder 20A or the hydraulic piping connected thereto. Pressure sensor 21RP detects the pressure in the rod-side oil chamber of the arm cylinder 21A or the hydraulic piping connected thereto. Pressure sensor 21BP detects the pressure in the bottom-side oil chamber of the arm cylinder 21A or the hydraulic piping connected thereto. Pressure sensor 22RP detects the pressure in the rod-side oil chamber of the bucket cylinder 22A or the hydraulic piping connected thereto. Pressure sensor 22BP detects the pressure in the bottom oil chamber of the bucket cylinder 22A or the hydraulic piping connected thereto. Pressure sensor 3LP detects the pressure in port A of the swing motor 3A (the pressurized oil supply port corresponding to the leftward swing of the swing body 3) or the hydraulic piping connected thereto. Pressure sensor 3RP detects the pressure in port B of the swing motor 3A (for example, the pressurized oil supply port corresponding to the rightward swing of the swing body 3) or the hydraulic piping connected thereto.

[0033] However, the sensors constituting the load measurement device 210 are not limited to pressure sensors; for example, load cells may be used. Also, since the actuator 2ACT is connected to the drive unit 35 or the driving unit 36, a sensor that measures the load of the drive unit 35 or the driving unit 36 ​​may be used as the load measurement device 210, and the load of the actuator 2ACT may be estimated based on its output.

[0034] <Positioning device> The positioning device 250 is, for example, a GNSS (Global Navigation Satellite System) mobile station. However, it is not limited to a GNSS mobile station; any device that can be used to determine the position of the hydraulic excavator 1, such as a laser positioning meter or total station, may be used as the positioning device 250.

[0035] <Drive Unit> The drive unit 35 is composed of a plurality of electromagnetic control valves 35A and a plurality of directional control valves 35B, and controls the amount of pressurized oil supplied to the actuator 2ACT according to the operation command value input from the controller 34, thereby driving the actuator 2ACT. For example, the operation command value input from the controller 34 is converted into pilot pressure by the electromagnetic control valve 35A, and the corresponding directional control valve 35B is driven by the pilot pressure. Pressurized oil whose flow rate has been adjusted by the directional control valve 35B is supplied to the corresponding hydraulic actuator, thereby driving the corresponding hydraulic actuator among the boom cylinder 20A, arm cylinder 21A, bucket cylinder 22A, swing motor 3A, and travel motor 41. Note that by adding or changing the set of electromagnetic control valves 35A and directional control valves 35B of the drive unit 35, hydraulic actuators other than the boom cylinder 20A, arm cylinder 21A, bucket cylinder 22A, and swing motor 3A can also be driven.

[0036] <Powering Device> The powering device 36 consists of a prime mover 36A and a hydraulic pump 36B, and discharges pressurized oil as power for the shovel 1, which is supplied to the actuator 2ACT via the drive device 35. The prime mover 36A can be an engine (internal combustion engine) or an electric motor. The hydraulic pump 36B is driven by the prime mover 36A and pressurizes the hydraulic oil drawn in from a hydraulic oil tank (not shown) and discharges the pressurized oil.

[0037] <Actuators> Actuators 2ACT are a group of actuators that drive the driven members, such as the slewing body 3, the front working device 2, and the traveling body 4. Specifically, actuators 2ACT include hydraulic actuators mounted on the hydraulic excavator 1, such as the boom cylinder 20A, arm cylinder 21A, bucket cylinder 22A, slewing motor 3A, and travel motor 41.

[0038] <Target Surface Setting Device> The target surface setting device 2000 sets, manages, and stores the construction target surface that the hydraulic excavator 1 will excavate and construct using the front work device 2, in response to input signals from the user interface 100 corresponding to the operator's operations. The construction target surfaces, such as the downward surface S1 (Figure 1A) and the side surface S2 (Figure 1B) mentioned above, can be set as a single plane or multiple planes. In the MC, the front work device 2 is controlled so that the bucket 22 does not excavate soil beyond the construction target surface, and the area that the front work device 2 can excavate is limited by the construction target surface. As mentioned above, the construction target surface may be set in a local coordinate system based on the hydraulic excavator 1, or in a global coordinate system based on the construction site or the Earth. In addition, the construction target surface may be received from a server (not shown) and stored in the target surface setting device 2000. The target surface setting device 2000 may also be combined with the controller 34.

[0039] <User Interface> The user interface 100 is a setting input / display device used by the operator to input various settings and check various information. For example, a touch monitor consisting of a display monitor and a touch panel is used. In addition to the touch panel, mechanical buttons and switches may also be used as input devices. The operator can input the dimensions and mass of each component of the front work device 2, the target construction surface, etc. The construction target surface can be set by selecting from those managed by the target surface setting device 2000, or by operating the front work device 2 to move the bucket 22 to multiple points and inputting each point to which the bucket 22 was moved. In the latter case, the target surface setting device 2000 calculates the coordinates of the multiple points that were input, and the construction target surface is set from the coordinates of those multiple points. Furthermore, the operator can check information such as the posture of the hydraulic excavator 1 (the posture of the slewing body 3 and the front working device 2, etc.), information about the construction target surface, and the positional relationship between the construction target surface and the front working device 2 (the angle and distance of the bucket 22 relative to the construction target surface) on the screen displayed on the user interface 100.

[0040] -Controller- The controller 34 controls the actuator 2ACT to drive the driven members such as the front work device 2, the slewing body 3, and the traveling body 4 by outputting command values ​​to the drive device 35 in response to the operation of the operating lever device 33 by the operator. Also, when the MC is enabled, the controller 34 calculates the required operation for the front work device 2 (e.g., the bucket 22) based on the operation signal of the operating lever device 33, and calculates the operation command value for the actuator 2ACT (i.e., the command value to the drive device 35) based on the required operation so that the bucket 22 does not exceed the construction target surface. The MC calculates the distance between the front work device 2 (e.g., a predetermined part such as the toe 22a or side edge 22b of the bucket 22) and the construction target surface, and activates its function when that distance is less than or equal to a preset distance.

[0041] In particular, in this embodiment, when both the lower surface S1 (Figure 1A) and the lateral surface S2 (Figure 1B) are set as construction target surfaces, such as in trench excavation work, the controller 34, as part of the MC's functions, determines, based on the operation signal from the operation lever device 33, whether the excavation instruction is an operation requesting construction on the lower surface S1 or an operation requesting construction on the lateral surface S2. If it is determined that the excavation instruction is an operation requesting construction on the lower surface S1, the lower surface S1 takes precedence over the lateral surface S2 as the current construction target surface, and the controller 34 calculates the operation command value for the actuator 2ACT, prioritizing that the bucket 22 does not excavate beyond the lower surface S1. Conversely, if it is determined that the excavation instruction is an operation requesting construction on the lateral surface S2, the lateral surface S2 takes precedence over the lower surface S1 as the current construction target surface, and the controller 34 calculates the operation command value for the actuator 2ACT, prioritizing that the bucket 22 does not excavate beyond the lateral surface S2. Hereinafter, the determination of whether the operation of the operating lever device 33 is intended for work on the downward surface S1 or the side surface S2 will be described as work priority determination as appropriate.

[0042] Specifically, if the work priority determination determines that the operation of the operating lever device 33 is intended for work on the lower surface S1, the controller 34 outputs an operation command value for the actuator 2ACT so as to allow a so-called jack-up state in which the front of the vehicle 4 is lifted, and so as to prevent the bucket 22 from exceeding the lower surface S1. On the other hand, if the work priority determination determines that the operation of the operating lever device 33 is intended for work on the lateral surface S2, the controller 34 outputs an operation command value for the actuator 2ACT so as to avoid a jack-up state and so as to prevent the bucket 22 from exceeding the lateral surface S2. Avoiding a jack-up state means ensuring a wide contact surface for the vehicle 4, thereby suppressing slippage between the vehicle 4 and the ground.

[0043] The controller 34 calculates a direction component ratio R (=Y / X), which is the ratio of a downward component Y to a lateral direction (left-right direction) component X corresponding to the requested operation direction for the front work implement 2, and executes the above-described work priority determination based on the level of the direction component ratio R. Specifically, when the direction component ratio R is equal to or greater than a predetermined threshold R1, the controller 34 determines that the operation of the operating lever device 33 is intended for construction on the lower surface S1. Conversely, when the direction component ratio R is less than the threshold R1, the controller 34 determines that the operation of the operating lever device 33 is intended for construction on the lateral surface S2. The threshold R1 may be a fixed value or a variable value.

[0044] FIG. 4 is a functional block diagram of the controller 34. The controller 34 illustrated in FIG. 4 is a computer including an arithmetic device such as a CPU and storage devices such as RAM, ROM, and an auxiliary storage device, and is electrically connected to the operating lever device 33, a target surface setting device 2000, a user interface 100, an attitude measurement device 200, a load measurement device 210, a positioning device 250, and a drive device 35. The controller 34 includes an attitude calculation unit 310, a requested operation calculation unit 320, a downward distance calculation unit 330, a target speed calculation unit 410, a target speed correction unit 420, an operation command value calculation unit 430, a lateral distance calculation unit 500, a jack-up state determination unit 510, a lateral excavation force measurement unit 520, a traveling state determination unit 530, a position information determination unit 540, a work priority determination unit 550, a work history storage unit 560, a slip occurrence prediction unit 570, a slip occurrence detection unit 580, and the like. The functions of the controller 34, such as the attitude calculation unit 310, may be configured by hardware elements such as electronic circuits, or may be configured by software elements. Each function will be described below.

[0045] The attitude calculation unit 310 calculates attitude information of the hydraulic excavator 1 based on the output from the attitude measurement device 200, for example, the position and angle of each member of the front work implement 2, the angle of the bucket 22 with respect to the target construction surface, the angle of the revolving structure 3 relative to the ground, the turning angle of the revolving structure 3 with respect to the traveling structure 4, and the like.

[0046] In the requested motion calculation unit 320, based on the operation signal from the operation lever device 33 and the posture information calculated by the posture calculation unit 310, the requested motion required for the front working device 2, specifically, when an operator operates the operation lever device 33 to drive one or more hydraulic actuators, the moving direction of a specific part of the front working device 2 (for example, the bucket 22) corresponding to the operation is calculated.

[0047] In the lower distance calculation unit 330, based on the position information of the lower surface S1 set by the target surface setting device 2000 and the posture information calculated by the posture calculation unit 310, the lower distance, which is a distance (for example, the shortest distance) between a predetermined part of the bucket 22 (for example, a toe 22a) and the lower surface S1, is calculated.

[0048] In the target speed calculation unit 410, the target speed of the actuator 2ACT is calculated according to the posture information calculated by the posture calculation unit 310, the lower distance calculated by the lower distance calculation unit 330, and the requested motion calculated by the requested motion calculation unit 320.

[0049] In the target speed correction unit 420, based on inputs from the work priority determination unit 550, the slip occurrence prediction unit 570, and the slip occurrence detection unit 580, the target speed of the actuator 2ACT calculated by the target speed calculation unit 410 is corrected as necessary.

[0050] In the motion command value calculation unit 430, a motion command value for the drive device 35 is generated according to the target speed of the actuator 2ACT output from the target speed correction unit 420, and is output to the drive device 35.

[0051] In the lateral distance calculation unit 500, based on the position information of the lateral surface S2 set by the target surface setting device 2000 and the posture information calculated by the posture calculation unit 310, the lateral distance, which is a distance (for example, the shortest distance) between a predetermined part of the bucket 22 (for example, a side edge 22b) and the lateral surface S2, is calculated.

[0052] The jack-up state determination unit 510 determines whether the front of the traveling body 4 is lifted up by the excavation reaction force, i.e., in a jack-up state, based on the attitude information calculated by the attitude calculation unit 310 and the load information calculated from the output of the load measuring device 210. The method for determining the jack-up state is not limited, but for example, the controller 34 can determine the jack-up state based on the decrease in pressure in the oil chamber on the extension side of the boom cylinder 20A (the bottom side oil chamber in the example of Figure 2).

[0053] In the lateral excavation force measurement unit 520, the excavation reaction force acting on the bucket 22 in the rotational direction during construction on the lateral surface S2 is calculated and measured based on the attitude information calculated by the attitude calculation unit 310 and the load information calculated from the output of the load measurement device 210.

[0054] The driving state determination unit 530 determines the driving state of the vehicle 4 based on, for example, an operation signal from the operation lever device 33.

[0055] The position information determination unit 540 calculates the position and positional changes of the hydraulic excavator 1 at the work site based on the positioning information acquired from the positioning device 250.

[0056] The task priority determination unit 550 performs the task priority determination described above. Several examples of task priority determination will be provided later.

[0057] The work history storage unit 560 records the decision history of the work priority determination unit 550.

[0058] The slip occurrence prediction unit 570 predicts whether or not slip is likely to occur between the vehicle 4 and the ground, based on the outputs of the jack-up state determination unit 510 and the lateral excavation force measurement unit 520.

[0059] The slip detection unit 580 determines whether a slip has occurred between the vehicle 4 and the ground based on the outputs of the driving state determination unit 530 and the position information determination unit 540.

[0060] -Machine Control- As shown in Figure 1A or Figure 1B, the MC controls the operation of the front working device 2 and other components based on the operator's actions to prevent the bucket 22 from excavating soil beyond the construction target surface.

[0061] When working on the lower surface S1, for example, if the operator performs a cloud operation of the arm 21 in the state shown in Figure 1A, the boom 20 will automatically rise and fall according to the posture of the arm 21 so that the tip 22a of the bucket 22 moves along the lower surface S1, which is the target surface for construction. As a result, even an operator who is not skilled in operating the hydraulic excavator 1 can make the tip 22a of the bucket 22 follow the lower surface S1 and excavate, thereby cutting out the lower surface S1.

[0062] Furthermore, when working on the lateral surface S2, if the operator performs a cloud operation of the arm 21 in the state shown in Figure 1B, the slewing body 3 will automatically rotate in conjunction with the cloud operation of the arm 21 so that the side edge 22b of the bucket 22 on the side closer to the lateral surface S2, which is the target surface for construction, moves along the lateral surface S2 (in the example of Figure 1B, it rotates to the right). As a result, even an operator who is not skilled in operating the hydraulic excavator 1 can excavate by making the side edge 22b of the bucket 22 follow the lateral surface S2, and cut out the lateral surface S2.

[0063] - Trench Excavation Work - In trench excavation work as shown in Figures 1A and 1B, the operator appropriately switches between excavation operations that require the construction of the lower surface S1 (bottom surface of the trench) and excavation operations that require the construction of the lateral surface S2 (wall surface of the trench) depending on the progress of the work. In a typical example, first the lower part of the bucket 22 (e.g., the tip 22a) excavates the ground to a certain extent in the depth direction to secure space for the bucket 22 to move, then the side of the bucket 22 (e.g., the side edge 22b) rough excavates to the left or right, and then the lower part of the bucket 22 rough excavates in the depth direction to form the general shape of the trench. Then the side of the bucket 22 is used for finishing excavation of the soil to cut out the lateral surface S2, and finally the lower part of the bucket 22 is used for finishing excavation of the soil to cut out the lower surface S1.

[0064] <Required Operation> Figure 5 is an explanatory diagram illustrating an example of a method for calculating a required operation vector in response to operator operation. The operating direction and operating speed of the actuator 2ACT requested by the operator are determined from the operating direction and amount of the operating lever device 33. The operation of the hydraulic excavator 1 requested by the operator, i.e., the required operation, can be calculated based on the lever operation (direction and amount of operation) of the operating lever device 33 and the posture information of the hydraulic excavator 1 calculated by the posture calculation unit 310. All movable members of the hydraulic excavator 1 are mechanically connected to the mating material, and the operation of each movable member can be calculated based on the operation of the actuator which corresponds one-to-one with the operator's lever operation and the dimensional data of the hydraulic excavator 1. Therefore, as shown in Figure 5, the operator's requested operation can be expressed as a vector in three-dimensional space that shows in which direction and by how much the operator's lever operation moves the reference point of the front work device 2 (for example, the tip 22a of the bucket 22). The reference point of the front work device 2 is a point used to determine the desired direction of movement, and is not limited to the tip 22a of the bucket 22, but may be another part of the front work device 2, such as the tip of the arm 21. Multiple reference points may be provided, and the vector of the desired movement may be calculated for these multiple reference points.

[0065] While the example given for determining the operator's requested action involves calculating the motion vector of the front work device 2 in response to lever operation, the method is not limited as long as the operator's requested action can be determined. For example, instead of calculating the vector in real time, data relating lever operation (direction and amount of operation) and the requested action could be obtained in advance through experiments, mapped, and then the operator's lever operation could be converted into the requested action using this map.

[0066] Furthermore, the required operating direction can be decomposed into a component of the direction of movement of the bucket 22 due to the operation of the front working device 2 (downward component Y in Figure 5) and a component of the direction of movement of the bucket 22 due to the operation of the slewing body 3 (rightward lateral component X in Figure 5).

[0067] - Determining Task Priority - Several examples of methods for determining task priority are provided below. Multiple examples of the following determination methods can be combined. In addition, the examples described below illustrate a case where the threshold R1 used for determining task priority is defined by a straight line in a two-dimensional feature space of the lateral and downward components of the requested operation, but the threshold R1 may also be defined by a curve or a polyline.

[0068] <Example 1 of Work Priority Determination> Figure 6 is an explanatory diagram of Example 1 of work priority determination. The example in Figure 6 is a method of determining work priority by comparing the downward component and the lateral component of the requested operating direction. For example, as mentioned above, the controller 34 determines that the excavation instruction by the operating lever device 33 is an operation requesting construction on the downward surface S1 when the directional component ratio R (= Y / X), which is the ratio of the downward component Y to the lateral component X of the requested operating direction for the front work device 2, is greater than or equal to the threshold R1. Conversely, the controller 34 determines that the excavation instruction by the operating lever device 33 is an operation requesting construction on the lateral surface S2 when the directional component ratio R is less than the threshold R1. The threshold R1 may be a fixed value or a variable value. This makes it possible to determine whether the operator intends to perform construction on the downward surface S1 or the lateral surface S2 based on the operator's lever operation, and to determine the work priority for the downward surface S1 and the lateral surface S2.

[0069] In Example 1, the threshold value R1 is fixed. In the example in Figure 6, R1 is set to Y / X = 1, but this is not the only option; R1 may be set to a value other than 1 depending on the characteristics of the work site, the operator's preference, etc.

[0070] Furthermore, as shown in Examples 2 to 5 below, R1 may be set as a variable value so that it changes depending on the situation.

[0071] <Example 2 of work priority determination> Figures 7A and 7B are explanatory diagrams of Example 2 of work priority determination. This example shows how to change the threshold R1 according to the distance D1 between the lower surface S1 and the bucket 22. In this example, the controller 34 calculates the distance D1 between the lower surface S1 and the bucket 22 (for example, the toe 22a) in the lower distance calculation unit 330, and the work priority determination unit 550 lowers the threshold R1 in accordance with the decrease in distance D1.

[0072] Figures 7A and 7B show R1 when the distance D1 is different from each other. R1 is lower in the situation shown in Figure 7B, where the bucket 22 is closer to the lower surface S1 than in the situation shown in Figure 7A, compared to the threshold R1 in the situation shown in Figure 7A, where the distance D1 is relatively large (e.g., R1 = 1). The threshold R1 may change in steps, such as in two or three stages, or it may change continuously in proportion to the distance D1.

[0073] <Example 3 of Work Priority Determination> Figures 8A and 8B are explanatory diagrams of Example 3 of work priority determination. This example shows how to change the threshold R1 by comparing the first distance D1 between the lower surface S1 and the bucket 22, and the second distance D2 between the side surface S2 and the bucket 22. This example differs from Example 2 in that it considers not only the distance D1 between the lower surface S1 and the bucket 22, but also the relationship between distances D1 and D2.

[0074] In this embodiment, the controller 34 calculates, for example, a first distance D1, which is the distance between the lower surface S1 and the bucket 22 (e.g., the toe 22a), using a downward distance calculation unit 330, and a second distance D2, which is the distance between the lateral surface S2 and the bucket 22 (e.g., the side edge 22b), using a lateral distance calculation unit 500. The work priority determination unit 550 then changes the threshold R1 according to the distance ratio of distances D1 and D2 (the ratio of the second distance D2 to the first distance D1 = D2 / D1). For example, the controller 34 raises the threshold R1 as the distance ratio (D2 / D1) increases and lowers the threshold R1 as the distance ratio (D2 / D1) decreases.

[0075] Figures 8A and 8B show R1 when the distance ratio of distances D1 and D2 is different from each other. For example, in Figure 8A, D1 < D2, and in Figure 8B, D1 > D2. In the situation in Figure 8A, where the bucket 22 is closer to the lower surface S1 than to the lateral surface S2 and the relative distance ratio (D2 / D1) is large, the threshold R1 (e.g., R1 < 1) is larger than in the situation in Figure 8B, where the bucket 22 is closer to the lateral surface S1 than to the lower surface S1 and the distance ratio (D2 / D1) is smaller than in the situation in Figure 8A. The threshold R1 may change in steps, for example, in three stages of the relative magnitudes of D1 and D2 (D1 < D2, D1 = D2, D1 > D2), or it may change continuously in proportion to the distance ratio (D2 / D1).

[0076] <Example 4 of work priority determination> Figures 9A and 9B are explanatory diagrams of Example 4 of work priority determination. This example shows how to change the threshold R1 according to the past history of work priority determination. In this example, the controller 34 stores the history of work priority determination in the work history storage unit 560, and changes the threshold R1 according to the history of work priority determination in the work priority determination unit 550.

[0077] Figure 9A shows the history of work priority determination for the previous operation (the excavation operation immediately preceding the current excavation operation) when downward excavation was prioritized, and Figure 9B shows the history of work priority determination for the previous operation when lateral excavation was prioritized. The threshold R1 when lateral excavation was prioritized for the previous operation (e.g., R1 > 1) is larger than the threshold R1 when lateral excavation was prioritized for the previous operation (e.g., R1 < 1).

[0078] <Example 5 of work priority determination> Figures 10A and 10B are explanatory diagrams of Example 5 of work priority determination. This example shows how to change the threshold R1 depending on whether the vehicle is currently in a jacked-up state. In this example, the controller 34, for example, determines whether the vehicle 4 is in a jacked-up state with its front lifted based on the output of the attitude sensors 30 and 31S in the jacked-up state determination unit 510 (described later), and if the work priority determination unit 550 determines that the vehicle 4 is in a jacked-up state, it lowers the threshold R1 to a level lower than the normal state (for example, R1 = 1).

[0079] Figure 10A shows the threshold R1 under normal conditions when the vehicle is not jacked up, and Figure 10B shows the threshold R1 when the vehicle is jacked up. As shown in Figures 10A and 10B, in this embodiment, the threshold R1 when the vehicle is jacked up (e.g., R1 < 1) is smaller than the threshold R1 when the vehicle is not jacked up (e.g., R1 = 1).

[0080] Determining whether the hydraulic excavator 1 is in a jacked-up state can be determined by checking whether the front working device 2 is on the ground and whether the front of the traveling body 4 is lifted up while the front working device 2 is on the ground (for example, whether there is a change in angle in the pitch direction). Whether the front working device 2 is on the ground can be determined, for example, by the load on the boom cylinder 20A, and the change in angle of the traveling body 4 can be determined, for example, based on the output of the attitude sensors 30S and 31A. For details on how to determine whether the hydraulic excavator 1 is in a jacked-up state, see, for example, Japanese Patent No. 6872666.

[0081] - Correction of target speed - Figure 11A is a schematic diagram illustrating how the hydraulic excavator 1 performs excavation when downward excavation is prioritized and the jack-up state is permitted, and Figure 11B is a schematic diagram illustrating how the hydraulic excavator 1 performs excavation when lateral excavation is prioritized and the jack-up state is prohibited.

[0082] In this embodiment, when prioritizing downward excavation, the controller 34 increases the excavation force for downward excavation by allowing a jacked-up state and controlling the operation of the boom 20 by the motor control (MC), as shown in Figure 11A. On the other hand, when prioritizing lateral excavation, the controller 34 controls the operation of the boom 20 by the MC so that the entire contact surface of the vehicle 4 is in contact with the ground and conditions are such that the vehicle 4 is less likely to slip. The control method of the boom 20 regarding the allowance / avoidance of a jacked-up state is described in detail, for example, in Japanese Patent No. 6872666. A jacked-up state can be allowed or avoided by controlling the force with which the bucket 22 presses against the ground due to the boom lowering operation. In this embodiment, the correction of the actuator operation command value to avoid jacking up is performed by correcting the control signal that lowers the boom cylinder to reduce the pressure in the direction of retracting the boom cylinder. This correction weakens the force with which the boom lowering operation presses against the ground, thereby avoiding a jacked-up state and increasing the contact area between the vehicle and the ground. On the other hand, the actuator operation command value for allowing jacking up may be a control signal that lowers the boom cylinder 20A to maintain pressure in the direction of retracting the boom cylinder 20A, or it may be a control signal that lowers the boom cylinder 20A to increase pressure in the direction of retracting the boom cylinder 20A, and this can be corrected.

[0083] Here, as shown in Figure 11A, when the hydraulic excavator 1 is jacked up, its weight is supported at three points: the bucket 22 and the rear of the left and right crawlers of the vehicle 4. As shown in Figure 11B, when the vehicle 4 is not jacked up, its weight is supported by the entire contact surface of the vehicle 4. As can be seen from the general friction equation (1), when the vehicle 4 is jacked up, the normal force generated on the vehicle 4 is small. F' = μN ...Equation (1) F': Maximum static friction force μ: Static friction coefficient N: Normal force Therefore, the frictional force between the vehicle 4 and the ground is smaller when it is jacked up compared to when it is not jacked up.

[0084] Furthermore, the ground on which the hydraulic excavator 1 makes contact is often soil or rock, and on ground composed of soil, rock, etc., it is important to ensure a large contact area of ​​the vehicle 4 in order to secure a large frictional force between the vehicle 4 and the ground. By maximizing the contact area of ​​the vehicle 4, the lateral digging force (wall digging force) of the bucket 22 can be increased.

[0085] Therefore, in this embodiment, when the slip occurrence prediction unit 570 predicts that the traveling body 4 will slip, the controller 34 corrects the operation command value of the actuator 2ACT in the target speed correction unit 420 to avoid the jack-up state. In this embodiment, for example, the pressure sensors 3LP and 3RP that detect the load of the swing motor 3A can function as measuring instruments for measuring the excavation reaction force on the side surface S2 (the reaction force of excavating the side wall surface with the side of the bucket 22). The slip occurrence prediction unit 570 also stores predetermined allowable values ​​for the excavation reaction force on the side surface S2. The slip occurrence prediction unit 570 predicts that the traveling body 4 will slip if the excavation reaction force on the side surface S2 measured by the measuring instrument exceeds the allowable value.

[0086] Furthermore, the controller 34 uses the output of the driving state determination unit 530 and the position information determination unit 540 to determine whether the vehicle 4 has slipped using the slip occurrence detection unit 580. If it is determined that the vehicle 4 has slipped, the target speed correction unit 420 corrects the operation command value of the actuator 2ACT to avoid the jack-up state.

[0087] The following provides specific examples of methods for predicting and detecting slippage, which is necessary for determining whether or not a target speed correction is required.

[0088] -Method for predicting slip occurrence- The controller 34 measures the reaction force of lateral wall excavation using the lateral excavation force measuring unit 520, as described below. If the slip occurrence prediction unit 570 determines that slip of the traveling body 4 is predicted based on the measured reaction force of lateral wall excavation, the target speed is corrected in the target speed correction unit 420.

[0089] <Reaction Force of Lateral Wall Excavation> Figure 12 is a schematic diagram illustrating an example of a method for measuring the reaction force of lateral wall excavation. In the lateral excavation force measurement unit 520, the reaction force of lateral wall excavation is calculated by measuring the torque generated in the slewing body 3. As shown in Figure 12, if L is the distance between the slewing body 3 and the bucket 22, and τ is the torque generated in the slewing body 3, the reaction force F of lateral wall excavation can be obtained by equation (2). The torque τ can be calculated, for example, from the pressure difference between port A and port B of the slewing motor 3A. F = τ / L …Equation (2) Alternatively, a strain gauge may be installed on the front working device 2 to directly measure the strain of the front working device 2, and the lateral excavation force measurement unit 520 may calculate the reaction force of lateral wall excavation based on the output of the strain gauge.

[0090] <Prediction and Determination of Slip Occurrence> Figure 13 is a schematic diagram illustrating an example of a slip occurrence prediction method. In the slip occurrence prediction unit 570, the prediction of whether or not a slip will occur between the traveling body 4 and the ground is made by comparing the allowable reaction force F' of lateral wall excavation that is permissible within the range in which slip occurrence can be avoided with the reaction force F that actually occurs during lateral wall excavation. The allowable reaction force F' is defined and mapped in relation to the horizontal distance L (Figure 12) between the rotating body 3 and the bucket 22, as shown in Figure 13. For example, the allowable reaction force F' can be defined based on the slip occurrence reaction force F1, which is the reaction force when a slip occurs, measured at each distance L in a prior experiment. The allowable reaction force F' can also be defined as the slip occurrence reaction force F1 at each distance L, but it is desirable to set it to a value that is lower by a predetermined margin than the slip occurrence reaction force F1 at each distance L. Furthermore, when the hydraulic excavator 1 is jacked up, the allowable reaction force F' decreases even if the distance L is the same. Therefore, it is desirable to also prepare a separate map for the case when the hydraulic excavator 1 is jacked up, as shown in Figure 13. As can be seen from equation (2) shown earlier, the allowable reaction force F' decreases as the distance L increases, as shown in Figure 13.

[0091] The slip occurrence prediction unit 570 considers whether the hydraulic excavator 1 is jacked up or not, and determines that if the reaction force F for lateral wall excavation, which is sequentially calculated from the torque τ generated in the slewing body 3 during excavation, exceeds the allowable reaction force F', it is estimated that the traveling body 4 is likely to slip, and therefore a slip occurrence is predicted. Conversely, the slip occurrence prediction unit 570 considers whether the hydraulic excavator 1 is jacked up or not, and determines that if the reaction force F for lateral wall excavation, which is sequentially calculated, is less than or equal to the allowable reaction force F', then a slip occurrence is unlikely for the traveling body 4, and therefore a slip occurrence is not predicted.

[0092] As described above, if the slip occurrence prediction unit 570 determines that a slip of the vehicle 4 is predicted, the target speed correction unit 420 corrects the target speed.

[0093] -Method for detecting slip occurrence- The controller 34 determines the travel state of the hydraulic excavator 1 using the travel state determination unit 530, and determines the displacement of the hydraulic excavator 1 using the position information determination unit 540, and based on the determination results of the travel state determination unit 530 and the position information determination unit 540, the slip occurrence detection unit 580 detects the occurrence of slip of the traveling body 4, and if the occurrence of slip of the traveling body 4 is detected, the target speed correction unit 420 corrects the target speed.

[0094] <Determination of Driving State> In the driving state determination unit 530, the driving state can be determined using the operation input state of the operating lever device 33. Specifically, if the amount of driving operation by the operating lever device 33 exceeds a predetermined value set according to the dead zone of the lever operation, the hydraulic excavator 1 is determined to be in a driving state, and if the amount of driving operation is less than or equal to the predetermined value, the hydraulic excavator 1 is determined to not be in a driving state. In addition, the driving state may be determined by directly detecting the movement of movable parts that operate in conjunction with the driving of the traveling body 4, such as by attaching rotation angle sensors to the drive wheels or driven wheels of the traveling body 4.

[0095] <Displacement Determination> In the position information determination unit 540, the displacement of the hydraulic excavator 1 is determined by comparing the amount of change in position information within a predetermined time period with a preset threshold, based on the current position information of the hydraulic excavator 1 acquired by the positioning device 250. Specifically, if the position information of the hydraulic excavator 1 changes by more than the threshold within a predetermined time period, it is determined that the hydraulic excavator 1 has been displaced. If the amount of change in position information of the hydraulic excavator 1 within a predetermined time period is less than or equal to the threshold, it is determined that the hydraulic excavator 1 has not been displaced.

[0096] <Determination of Slip Occurrence> In the slip occurrence detection unit 580, if the travel state determination unit 530 determines that the hydraulic excavator 1 is not in a travel state, and the position information determination unit 540 determines that the hydraulic excavator has been displaced, then the occurrence of a slip of the travel body 4 is detected. In this case, by adding the state of the reaction force of the lateral wall excavation to the basic information for determination, the occurrence of a slip of the travel body 4 due to the reaction force of the wall excavation can be detected with higher accuracy. For example, if the reaction force of the lateral wall excavation is greater than or equal to a predetermined value, and the hydraulic excavator 1 is displaced even though the travel body 4 is not in a travel state, the system can be configured to detect the occurrence of a slip of the travel body 4.

[0097] As described above, when the slip detection unit 580 detects a slip of the vehicle 4, the target speed is corrected in the target speed correction unit 420.

[0098] -Control Procedure- Figure 14 is a flowchart showing the calculation procedure for the operation command value by the controller 34. During operation of the hydraulic excavator 1, the controller 34 repeatedly executes the calculation process shown in Figure 14 at a predetermined cycle (for example, 10 ms).

[0099] When the process shown in Figure 14 is started, the controller 34 first calculates the posture of each component of the hydraulic excavator 1 based on the real-time output of the posture measurement device 200 (step S100), and obtains information on the construction target surface from the target surface setting device 2000 (step S110). Then, the controller 34 obtains the operation signal from the operator of the operation lever device 33 (step S120), and calculates the required operating direction based on the posture of the hydraulic excavator 1 and the operation signal from the operation lever device 33 (step S130).

[0100] Next, the controller 34 calculates the distance between the bucket 22 and the first construction target surface, the downward surface S1 (downward distance) (step S140), and calculates the distance between the bucket 22 and the second construction target surface, the side surface S2 (sideways distance) (step S150). Then, the controller 34 calculates the target speed of the actuator 2ACT based on the downward distance and the requested direction of operation (step S160), and sets a determination method for determining the work priority between downward excavation and sideways excavation (step S170). The determination criteria are the determination method exemplified in Example 1-5 above, and for example, the determination method setting selected by the operator on the menu screen displayed on the user interface 100 (Figure 2) is read into the controller 34 in step S170.

[0101] Next, the controller 34 determines the priority of downward excavation and lateral excavation according to the current requested direction of operation (step S180), and determines whether downward excavation should be prioritized at this time (step S190). If it is determined that downward excavation should be prioritized, the controller 34 determines whether it is necessary to excavate by jacking up the hydraulic excavator 1 (step S200). Whether jacking up is necessary is determined by whether the distance between the downward surface S1 and the bucket 22 (e.g., the tip 22a) (downward distance) is decreasing at a required speed corresponding to the amount of movement of the operating lever device 33. If the excavation resistance is large and the decrease in downward distance is smaller than the required speed, it is estimated that an increase in excavation force is required. Therefore, the controller 34 determines that jacking up is necessary if the rate of decrease in downward distance is less than or equal to a predetermined value relative to the required speed, and determines that jacking up is unnecessary if the difference between the rate of decrease in downward distance and the required speed is less than a predetermined value.

[0102] If downward excavation is prioritized and it is determined that jacking up is necessary, the controller 34 adjusts and determines the target speed of the actuator 2ACT, including the boom cylinder 20A, as necessary to allow jacking up of the hydraulic excavator 1 during excavation, or to actively jack up the hydraulic excavator 1 for excavation (step S210).

[0103] If lateral excavation is prioritized, or if it is determined that jacking up is unnecessary, the controller 34 corrects and determines the target speed of the actuator 2ACT, including the boom cylinder 20A, as necessary so that the hydraulic excavator 1 does not jack up (step S220).

[0104] Finally, the controller 34 calculates an operation command value for operating the actuator 2ACT based on the target speed determined in step S210 or S220 and outputs it to the drive unit 35 (step S230).

[0105] The controller 34 repeatedly executes the above process.

[0106] -Summary- (1) As described above, in this embodiment, the controller 34 determines whether the excavation instruction by the operating lever device 33 is an operation requesting construction on the downward surface S1 or an operation requesting construction on the side surface S2, based on the requested operation to the front work device 2 by the operation of the operating lever device 33. If the controller 34 determines that the excavation instruction is an operation requesting construction on the downward surface S1, it prioritizes downward excavation and corrects the operation command value of the actuator 2ACT so that the bucket 22 does not exceed the downward surface S1, while allowing the jack-up state. On the other hand, if the controller 34 determines that the excavation instruction is an operation requesting construction on the side surface S2, it prioritizes side excavation and corrects the operation command value of the actuator 2ACT so that the bucket 22 does not exceed the side surface S2, while avoiding the jack-up state.

[0107] This allows the downward excavation force to be increased by correcting the operation command so that jacking up is permitted or actively performed when construction on the downward surface S1 is intended. On the other hand, when it is determined that construction on the side surface S2 is intended, the operation command value is corrected to avoid jacking up and secure the contact area of ​​the traveling body 4, thereby increasing the lateral excavation force by making it less likely for slippage to occur, and making it easier for the hydraulic excavator 1 to exert its inherent wall excavation force. In this way, the MC functions in accordance with the operator's intentions, improving work efficiency.

[0108] (2) In this embodiment, the controller 34 determines whether the downward surface S1 or the side surface S2 is intended to be worked on by comparing the side (left-right) component X and the downward component Y of the requested operating direction. Specifically, the controller 34 calculates the directional component ratio R (= Y / X) of the downward component Y to the side component X of the requested operating direction, and determines that the downward surface S1 is intended to be worked on if the directional component ratio R is greater than or equal to the threshold R1, and determines that the side surface S2 is intended to be worked on if the directional component ratio R is less than the threshold R1. By decomposing the requested operating direction into components in this way, the controller 34 can objectively estimate whether the operator's operation is intended to work on the downward surface S1 or the side surface S2.

[0109] By using a fixed value for the threshold R1, the computational load on the controller 34 can be suppressed.

[0110] (3) The controller 34 may also be configured to lower the threshold R1 in accordance with the decrease in the distance D1 between the lower surface S1 and the bucket 22, as explained in Figures 7A and 7B.

[0111] As mentioned above, for example, during trench excavation work as described in Figures 1A and 1B, the operator generally excavates downwards, then laterally, and then downwards again. Therefore, when the bucket 22 is close to the downward surface S1, it is highly likely that the operator is intending to perform finishing excavation near the downward surface S1. By lowering the threshold R1 in accordance with the decrease in distance D1, it becomes easier to determine that downward excavation takes priority when the bucket 22 is close to the downward surface S1. This suppresses an overly sensitive switch in priority determination according to the distance D1 when the bucket 22 is close to the downward surface S1, thereby suppressing a deterioration in the quality of the downward surface S1 due to misjudgment. The process of lowering the threshold R1 in accordance with the decrease in distance D1 is effective when prioritizing the downward surface S1, which is important for the completed work.

[0112] (4) The controller 34 may also be configured to change the threshold R1 according to the distance ratio (= D2 / D1) of the distance D1 between the lower surface S1 and the bucket 22 and the distance D2 between the lateral surface S2 and the bucket 22, as explained in Figures 8A and 8B.

[0113] As mentioned above, for example, during trench excavation work as described in Figures 1A and 1B, the operator generally excavates downwards, then laterally, and then downwards again. Therefore, when the bucket 22 is closer to the downward surface S1 than to the lateral surface S2, it is assumed that the operator is operating with the intention of working on the downward surface S1. Thus, for example, when the bucket 22 is relatively closer to the downward surface S1, lowering the threshold R1 makes it easier to determine that work on the downward surface S1 is prioritized. On the other hand, when the bucket 22 is closer to the lateral surface S2 than to the downward surface S1, it is assumed that the operator is operating with the intention of working on the lateral surface S2. Thus, when the bucket 22 is relatively closer to the lateral surface S2, raising the threshold R1 makes it easier to determine that work on the lateral surface S2 is prioritized.

[0114] This can improve the accuracy of determining the operator's intent in trench excavation and other operations.

[0115] (5) The controller 34 may also be configured to store a history of work priority determinations and change the threshold R1 according to the determination history, as explained in Figures 9A and 9B.

[0116] As mentioned above, when an operator excavates a trench, they often go through a series of steps, such as the initial downward excavation step, the lateral rough excavation step, the downward rough excavation step, the lateral surface S2 finish excavation step, and the downward surface S1 finish excavation step. However, each excavation step is rarely completed in a single excavation operation, and is often repeated multiple times. For example, if downward excavation is performed, the next excavation operation is often also downward excavation. Therefore, by recording the result of the work priority determination for each excavation operation and using the history of work priority determinations, for example, if the work priority determination for the previous excavation operation was downward excavation priority, the threshold R1 can be lowered to make it easier for the work priority determination for the current excavation operation to be downward excavation priority. Conversely, based on the history of work priority determinations, if the work priority determination for the previous excavation operation was lateral excavation priority, the threshold R1 can be raised to make it easier for the work priority determination for the current excavation operation to be lateral excavation priority.

[0117] This can improve the accuracy of determining the operator's intent in trench excavation and other operations.

[0118] (6) The controller 34 may also be configured to lower the threshold R1 when it is determined that the hydraulic excavator 1 is in a jacked-up state, as explained in Figures 10A and 10B.

[0119] As mentioned above, when performing trench excavation work, operators often repeat excavation operations multiple times for each process. Therefore, when working under conditions where the ratio of the lateral component X and the downward component Y of the required operation is near the threshold R1, if the priority of downward excavation and lateral excavation switches too quickly, the hydraulic excavator 1 may repeatedly switch between jacked-up and unjacked states, potentially reducing the operator's work efficiency due to vibrations of the hydraulic excavator 1. In addition, because the hydraulic excavator 1 is heavy and has a large inertial force, there is a slight time lag between the output of the operation command value and the actual operation of the hydraulic excavator 1 in accordance with the operation command value. This can also lead to repeated switching between jacked-up and unjacked states when working under conditions near the threshold R1. Therefore, when the hydraulic excavator 1 is jacked up, the threshold R1 related to determining work priority is lowered compared to when it is not jacked up, thereby ensuring hysteresis. This prevents the work priority determination from switching excessively when jacking up is actually occurring, even under conditions where the work priority determination could switch with a slight change in the amount of operation. This suppresses overly sensitive switching of work priority and improves the operator's work efficiency.

[0120] (7) Furthermore, as described above, the controller 34 may be configured to correct the operation command value of the actuator 2ACT to avoid the jacked-up state when slippage of the traveling body 4 is predicted or when it is determined that the traveling body 4 has slipped. In this case, the contact area of ​​the traveling body 4 can be secured before slippage occurs or quickly after slippage occurs, thereby suppressing the occurrence of subsequent slippage and securing the lateral wall excavation force.

[0121] (8) As mentioned above, the controller 34 predicts the occurrence of a slip in the traveling body 4 if, for example, the measured reaction force of the lateral wall excavation exceeds a specified allowable value. By measuring the reaction force of the lateral wall excavation and comparing it with the allowable value in this way, the controller 34 can be made aware of the possibility of a slip occurring.

[0122] -Additional Note- The present invention is not limited to the embodiments described above and may include various modifications. The present invention is not necessarily limited to a configuration having all the components described in each of the embodiments above. For example, it is possible to replace some of the components with other components. It is also possible to delete some of the components of the embodiments or add other components.

[0123] 1...Hydraulic excavator (working machine), 2...Front working device, 2ACT...Actuator, 3...Slewing body, 3A...Slewing motor, 3LP, 3RP...Pressure sensor (measuring instrument), 4...Travel body, 20A...Boom cylinder (actuator), 20S...Attitude sensor, 21A...Arm cylinder (actuator), 21S...Attitude sensor, 22...Bucket, 22A...Bucket cylinder (actuator), 22S...Attitude sensor, 30S, 31S...Attitude sensor, 33...Operating lever device, 34...Controller, 35...Drive device, D1...Distance (first distance), D2...Second distance, R...Directional component ratio, R1...Threshold, S1...Downward surface (construction target surface), S2...Sideward surface (construction target surface), X...Left / right direction component, Y...Downward direction component

Claims

1. A work machine comprising: a traveling body; a slewing body mounted on the traveling body so as to be rotatable in the left-right direction; a front working device having a bucket and being attached to the slewing body so as to be swingable in the up-down direction; actuators for driving the slewing body and the front working device, respectively; an operating lever device for operating the actuators; a controller that calculates a required operation for the front working device based on the operating signal from the operating lever device and calculates an operation command value for the actuator so as to prevent the bucket from exceeding the construction target surface based on the required operation; and a drive device that drives the actuator according to the operation command value from the controller, wherein the controller determines, based on the operating signal from the operating lever device, whether the excavation instruction is an operation requesting construction on the lower surface which is the construction target surface located below the bucket, or an operation requesting construction on the lateral surface which is the construction target surface located to the side of the bucket, and if it is determined that the excavation instruction is an operation requesting construction on the lower surface, it outputs an operation command value for the actuator that allows a jacked-up state in which the front of the traveling body is lifted up. A work machine characterized in that, when it is determined that the excavation instruction is an operation requiring construction on the side, it outputs an operation command value for the actuator in order to avoid the jack-up state.

2. The work machine according to claim 1, wherein the determination of whether the controller requests work on the downward surface and whether the controller requests work on the side is determined based on the operation signal from the operation lever device, the posture information of the front work device or the rotating body, and the target surface for work.

3. The work machine according to claim 1, wherein the controller calculates the ratio of the downward component to the left-right component of the requested operation, determines that the excavation instruction by the operating lever device is an operation requesting construction on the downward surface when the ratio of 4. The work machine according to claim 3, wherein the controller calculates the distance between the lower surface and the bucket, and lowers the threshold in accordance with the decrease in the distance.

5. The work machine according to claim 3, wherein the controller calculates a first distance which is the distance between the lower surface and the bucket, and a second distance which is the distance between the side surface and the bucket, and changes the threshold according to the distance ratio of the first distance and the second distance.

6. The work machine according to claim 5, wherein the distance ratio is the ratio of the second distance to the first distance, and the controller raises the threshold as the distance ratio increases and lowers the threshold as the distance ratio decreases.

7. The work machine according to claim 3, wherein the controller stores the history of the determination and changes the threshold according to the history of the determination.

8. A work machine according to claim 3, comprising a posture sensor for detecting the posture of the traveling body, wherein the controller determines, based on the output of the posture sensor, whether the traveling body is in a jacked-up state with its front end lifted, and if it is determined that the traveling body is in the jacked-up state, it lowers the threshold.

9. A work machine according to claim 1, wherein the controller corrects the operating command value of the actuator to avoid the jack-up state when slippage of the traveling body is predicted.

10. The work machine according to claim 9, wherein it has a measuring instrument for measuring the lateral excavation reaction force, the controller stores a specified allowable value for the lateral excavation reaction force, and predicts the occurrence of slippage of the traveling body when the lateral excavation reaction force measured by the measuring instrument exceeds the allowable value.

11. A work machine according to claim 1, wherein the work machine is equipped with a posture sensor for detecting the posture of the traveling body, and the controller determines whether the traveling body has slipped based on the output of the posture sensor, and if it is determined that the traveling body has slipped, corrects the operation command value of the actuator to avoid the jacked-up state.

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