Work machine

Abstract

Provided is a work machine including a control device that calculates a movement command value for an actuator so that a bucket follows a target surface on the basis of a required movement direction relative to the bucket, the required movement direction being calculated in accordance with an operation amount and an orientation, and a drive device that drives the actuator on the basis of the movement command value, wherein: a plurality of candidate bucket lines, which are line segments of an end part of the bucket, are set; the positional relationship between the plurality of candidate bucket lines and the target surface is calculated using at least the distance or the relative angle between each candidate bucket line and the target surface; a bucket line corresponding to required excavation work is selected from among the plurality of candidate bucket lines on the basis of the positional relationship and the operation amount; and the movement command value is corrected so that the angle between the selected bucket line and the target surface decreases. This makes it possible to control the angle of the bucket to an appropriate work orientation that corresponds to the work content, thereby improving operator workability.

Description

Work machinery

[0001] The present invention relates to a work machine equipped with an articulated work front.

[0002] Known work machines used in civil engineering projects and the like include a work machine main body having a rotating body rotatably attached to the upper part of a traveling body that travels via a power system, a multi-jointed work front attached to the main body so that it can swing freely in the vertical direction, and each front member of the work front is driven by a cylinder. One example is a so-called hydraulic excavator, which has a work front composed of a boom, arm, bucket, etc. Some hydraulic excavators of this type perform so-called machine control, in which the target surface to be excavated is set in advance and boom and bucket movements are automatically controlled in accordance with the amount of arm movement operated by the operator so that the bucket can excavate along the target surface. In particular, there is so-called bucket angle control, in which bucket movement is controlled so that the bucket is at a predetermined angle relative to the target surface.

[0003] However, in bucket angle control, if the bucket angle is controlled to a state different from the working posture of the bucket intended by the operator, the operator may feel uncomfortable and workability may be reduced.

[0004] For example, Patent Document 1 discloses a work machine that starts controlling the angle of the bucket at an appropriate time, and that includes an operation determination unit that determines whether the bucket is in an operated or non-operated state based on the amount of operation by the operator, a bucket control determination unit that determines whether a bucket control condition is met based on the determination of the non-operated state, and a work machine control unit that outputs a control signal to control the bucket so that the state of the work machine is maintained when it is determined that the bucket control condition is met.

[0005] International Publication No. 2017 / 086488

[0006] With a hydraulic excavator, the working posture of the bucket required by the operator varies depending on the type of work being done, such as when digging with the toe of the bucket parallel to the target surface, when shaping work is performed with the rear end of the bottom of the bucket parallel to the target surface, or when digging with the side cutters of the bucket parallel to the wall surface of the excavation.

[0007] In contrast, with the above-described conventional technology, the operator must adjust the bucket angle by delicately operating a lever so that the bucket is in an appropriate working position before the control that keeps the bucket angle constant is activated.

[0008] Machine control is required to enable excavation work to be performed as intended by the operator with simple lever operation, but the above-mentioned conventional technology requires the operator to perform delicate lever operation, which may result in a decrease in workability.

[0009] The present invention has been made in consideration of the above, and has an object to provide a work machine that can improve the operator's workability by controlling the bucket angle to an appropriate working posture according to the work content.

[0010] The present application includes a plurality of means for solving the above-mentioned problems, and one example thereof is a machine tool including a traveling body, an upper rotating body provided so as to be rotatable relative to the traveling body, a working device having at least a bucket and capable of swinging freely in the vertical direction relative to the upper rotating body, an actuator for driving the upper rotating body and the working device, an operating device for operating the actuator, an operating amount detecting device for detecting an operating amount of the operating device, an attitude detecting device for detecting an attitude of the upper rotating body and the working device, a target surface setting device for setting a target surface to be excavated by the bucket, and a control device for calculating a required operation direction for the bucket based on the operation amount detected by the operating amount detecting device and the attitude detected by the attitude detecting device, and a control device for controlling the actuator so that the bucket follows the target surface based on the required operation direction. and a drive unit that drives the actuator based on the operation command value calculated by the control unit, the control unit comprises: a bucket line setting unit that sets a plurality of candidates for a bucket line, which is a line segment of an end of the bucket; a bucket line calculation unit that calculates a positional relationship between the plurality of bucket line candidates and the target surface using at least the distance or relative angle therebetween; a requested bucket line selection unit that selects a bucket line that corresponds to a requested excavation work from the plurality of bucket line candidates based on the positional relationship and the operation amount; and a operation command value correction unit that corrects the operation command value for the bucket so that the angle between the bucket line selected by the requested bucket line selection unit and the target surface becomes smaller.

[0011] According to the present invention, the angle of the bucket can be controlled to an appropriate working posture in line with the operator's intention, thereby improving the operator's workability.

[0012] FIG. 1 is a diagram illustrating work performed by a hydraulic excavator, which is an example of a work machine. FIG. 2 is a side view schematically illustrating the overall configuration of a hydraulic excavator, which is an example of a work machine. FIG. 3 is a diagram illustrating a main controller extracted together with related configuration. FIG. 4 is a functional block diagram illustrating processing contents of the main controller. FIG. 5 is a diagram schematically illustrating an example of a representative bucket line. FIG. 6 is a diagram illustrating a requested action of an operator with respect to the bucket in excavation work using machine control. FIG. 7 is a diagram illustrating a requested action of an operator with respect to the bucket in excavation work using machine control. FIG. 8 is a diagram illustrating a requested action of an operator with respect to the bucket in excavation work using machine control. FIG. 9 is a diagram illustrating a method for calculating the distance and relative angle of the bucket line with respect to a construction target surface. FIG. 10 is a diagram illustrating a method for calculating the distance and relative angle of the bucket line with respect to a construction target surface. FIG. 11 is a flowchart illustrating processing contents of the main controller. FIG. 12 is a flowchart of a modified example illustrating processing contents of the main controller.

[0013] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0014] <Target Device> FIG. 1 is a diagram showing the state of work performed by a hydraulic excavator, which is an example of a work machine according to this embodiment.

[0015] As shown in Figure 1, the subject of this embodiment is made up of a work machine 1 and a construction target surface. The construction target surface may be a so-called 2D construction target surface that has information only in the forward / backward direction of the work machine 1, or it may be a so-called 3D construction target surface that has information in the left / right direction in addition to the forward / backward direction. The construction target surface may also be set relative to the work machine 1, or may be set in a global coordinate system based on the construction site or the Earth. Furthermore, the construction target surface may be set below the work machine 1, or may be set to the side, front, or rear.

[0016] <Configuration of the Device> FIG. 2 is a side view showing a schematic overall configuration of a hydraulic excavator, which is an example of a work machine according to this embodiment.

[0017] As shown in Figure 2, the work machine 1 includes a front work unit 2 (working device), a revolving unit 3 (upper revolving unit), and a running unit 4. The revolving unit 3, together with the running unit 4, constitutes the main body of the work machine.

[0018] The front work unit 2 is configured to rotate relative to the rotating unit 3, and the rotating unit 3 is configured to rotate relative to the running unit 4, each centering on a connecting portion. The front work unit 2 includes a boom 20 connected at one end to the rotating unit 3, an arm 21 connected at one end to the boom 20, a bucket 22 connected at one end to the arm 21, a boom cylinder 20A connected at both ends to the boom 20 and the rotating unit 3, respectively, an arm cylinder 21A connected to the arm 21 and the boom 20, respectively, a link A 22B, a link B 22C, and a bucket cylinder 22A connected to link B 22C and the arm 21. These members are configured to rotate (i.e., swing freely) in the vertical direction, each centering on a connecting portion. The running unit 4 includes a travel motor 41 and a crawler 45.

[0019] The boom cylinder 20A, arm cylinder 21A, and bucket cylinder 22A, which are actuators that drive the front work unit 2, are configured to extend and retract hydraulically, and extend and retract to rotate the boom 20, arm 21, and bucket 22, respectively. The bucket 22 can be replaced with any attachment (not shown), such as a grapple, breaker, ripper, magnet, or rotary tilt bucket.

[0020] The boom 20 and the arm 21 are respectively equipped with an IMU (Inertial Measurement Unit) (boom) 20S and an IMU (arm) 21S for detecting the attitudes of the boom 20 and the arm 21. The link A 22B is equipped with an IMU (bucket) 22S for detecting the attitude of the bucket 22. In other words, the IMU (boom) 20S, the IMU (arm) 21S, and the IMU (bucket) 22S constitute an attitude detection device that detects the attitude of the front work device 2 (working device). The IMU (boom) 20S, the IMU (arm) 21S, and the IMU (bucket) 22S are each composed of an angular velocity sensor and an acceleration sensor.

[0021] The boom cylinder 20A is equipped with a pressure sensor (boom rod) 20RP and a pressure sensor (boom bottom) 20BP for detecting the load. The arm cylinder 21A is equipped with a pressure sensor (arm rod) 21RP and a pressure sensor (arm bottom) 21BP for detecting the load. The bucket cylinder 22A is equipped with a pressure sensor (bucket rod) 22RP and a pressure sensor (bucket bottom) 22BP for detecting the load.

[0022] The rotating body 3 is equipped with a rotation angle sensor 2S, an IMU (rotating body) 30S, a main frame 31, a driver's cab 32, a main controller 34, a drive unit 35, a prime mover 36, a rotation load measuring device 37, and a position measuring device 250.

[0023] The swing angle sensor 2S is attached so as to detect the relative angle between the running body 4 and the swing body 3.

[0024] The IMU (rotating body) 30S includes an acceleration sensor and an angular velocity sensor, and is attached so as to detect the tilt angle of the rotating body 3. In other words, the IMU (rotating body) 30S constitutes an attitude detection device that detects the attitude of the rotating body 3 (upper rotating body).

[0025] The operator's cab 32 is equipped with an operation input device 33 , a setting input display device 100 , and a construction surface management device 2000 .

[0026] The operation input device 33 is composed of an operation lever, which is an operation device for operating the actuator, and an operation input amount sensor (operation amount detection device) that detects the amount by which the operation lever is depressed. The operation input amount sensor is attached so as to detect the amount by which the operator depresses the operation lever, and convert the target operation of each movable part requested by the operator into an electric signal.

[0027] The construction surface management device 2000 is connected to the setting input display device 100 and is installed to manage and store the construction target surface that is the target for excavation by the work front 2.

[0028] The setting input display device 100 is composed of a display monitor and a touch panel, and is attached so that it can display the posture of the work machine 1, information about the construction target surface, the positional relationship and distance between the construction target surface and the work front 2, etc., and can also set various dimensions and mass of the work front 2.

[0029] FIG. 3 is a diagram showing the main controller together with the related components.

[0030] As shown in FIG. 3, the drive device 35 is composed of an electromagnetic control valve and a directional change valve, and is installed so as to operate the drive actuators, that is, the boom cylinder 20A, the arm cylinder 21A, and the bucket cylinder 22A, by driving the electromagnetic control valve and the directional change valve in accordance with operation command values ​​instructed by the main controller 34.

[0031] The prime mover 36 is comprised of an engine and a hydraulic pump, and is attached so as to generate the hydraulic pressure required to operate the work machine 1 as power.

[0032] The swing load measuring device 37 is attached so as to measure the load in the swing direction of the swing body 3 .

[0033] The running body 4 is equipped with tracks, and the operator operates the operation input device 33 to run the work machine 1. The running body 4 is not limited to one equipped with tracks, and may be one equipped with running wheels or legs.

[0034] The configuration of the work machine 1 is an example, and the work machine 1 may have a similar device or configuration.

[0035] FIG. 4 is a functional block diagram showing the processing contents of the main controller.

[0036] As shown in FIG. 4, the main controller 34 provided in the work machine 1 is connected to an operation input device 33, an attitude measuring device 200, a load measuring device 210, a position measuring device 250, a driving device 35, a construction surface management device 2000, and a setting input display device 100.

[0037] The construction surface management device 2000 is connected to the setting input display device 100 .

[0038] The driving device 35 is connected to a prime mover 36 and an actuator 2ACT.

[0039] <Detailed Configuration and Function of Device> <Operation Input Device 33> The operation input device 33 is composed of an operation lever and an operation input amount sensor. The amount of operation by the operator is converted into an electrical signal by the operation input amount sensor. In hydraulic excavators, the operating speed of the actuators is generally set to increase as the amount the lever is tilted increases, and the operator changes the operating speed of each actuator by changing the amount the lever is tilted, thereby operating the work machine. Note that the operation input device 33 may be of a hydraulic pilot type or a remotely controlled type, as long as it has equivalent functions.

[0040] <Attitude measurement device 200> The attitude measurement device 200 is equipped with angular velocity sensors and acceleration sensors in the IMU (swivel unit) 30S, IMU (boom) 20S, IMU (arm) 21S, and IMU (bucket) 22S, respectively, and is also equipped with a swing angle sensor 2S. Attitude information of the work machine 1 is obtained from these IMUs and angle sensors. The boom 20, arm 21, bucket 22, boom cylinder 20A, arm cylinder 21A, bucket cylinder 22A, link A 22B, link B 22C, and revolving unit 3 are each attached so as to be able to swing, and the attitudes of the boom 20, arm 21, bucket 22, and revolving unit 3 can be estimated from the mechanical link relationships. Note that the attitude detection method shown here is just one example, and the relative angles of each part of the front work unit 2 may be directly measured, or the strokes of the boom cylinder 20A, arm cylinder 21A, and bucket cylinder 22A may be detected to calculate the attitude of each part of the work machine 1.

[0041] <Load measuring device 210> Load measuring device 210 detects the load on each actuator using pressure sensor (boom rod) 20RP, pressure sensor (boom bottom) 20BP, pressure sensor (arm rod) 21RP, pressure sensor (arm bottom) 21BP, pressure sensor (bucket rod) 22RP, pressure sensor (bucket bottom) 22BP) attached to boom cylinder 20A, arm cylinder 21A, bucket cylinder 22A, and swing body 3, respectively, and swing load measuring device 37. Alternatively, a load detection device using a load cell may be used. Furthermore, because actuator 2ACT, drive unit 35, and engine / pump 36 are connected hydraulically or mechanically, a method of estimating the load on work machine 1 by measuring the loads on these actuators may also be used.

[0042] <Position measuring device> Position measuring devices include a GNSS (Global Navigation Satellite System), a laser positioner, and a total station. Position measuring devices other than those listed above may also be provided as long as they can identify the position of the work machine 1.

[0043] <Drive unit 35> The drive unit 35 is composed of an electromagnetic control valve and a directional change valve, and controls the amount of pressurized oil supplied to the cylinders and hydraulic motors that drive each part of the work machine in accordance with operation command values ​​issued from the main controller 34. The operation command value output from the main controller 34 is converted into pilot pressure by the electromagnetic control valve, and the pilot pressure drives the directional change valve that controls the amount of movement of the actuator. The hydraulic oil, the flow rate of which is adjusted by the directional change valve, is supplied to the cylinders and hydraulic motors that drive each part of the work machine, and drives each moving part. Furthermore, by adding or changing the configuration, it is possible to drive additional attachments and equipment not included above.

[0044] <Motor unit 36> The motor unit 36 ​​is made up of an engine and a hydraulic pump, and generates hydraulic pressure as power required to operate the work machine 1. In addition to the above, the motor unit 36 ​​may also be one that extracts hydraulic power from an electrically driven motor.

[0045] <Actuator 2ACT> The actuator 2ACT is a general term for actuators including the boom cylinder 20A, the arm cylinder 21A, the bucket cylinder 22A, the hydraulic motor for swinging, the hydraulic motor for traveling, and the like.

[0046] <Construction surface management device 2000> The construction surface management device 2000 uses the setting input display device 100 to set and manage a construction target surface for the work machine 1. The construction target surface can be set to have a single plane or multiple planes, making it possible to set the range that can be excavated by the work front 2. The construction target surface may be set relative to the work machine 1 as the base, or may be set in a coordinate system that uses the construction site or the Earth as the base.

[0047] <Setting input display device 100> The setting input display device 100 displays to the operator the posture of the work machine 1, area information of the construction target surface set by the construction surface management device 2000, the distance between the work front 2 and the construction target surface, and the like.

[0048] <Main controller 34> As shown in FIG. 4 , the main controller 34 is connected to the operation input device 33, the construction surface management device 2000, the setting input display device 100, the attitude measurement device 200, the load measurement device 210, the position measurement device 250, and the drive device 35, and is made up of an attitude calculation unit 310, a required movement calculation unit 320, a downward distance calculation unit 330, a target speed calculation unit 410, a target speed correction unit 420, a movement command value correction unit 430, a lateral distance calculation unit 500, a bucket line relative angle calculation unit 510, a bucket line setting unit 520, a soil hardness determination unit 530, a required bucket line selection unit 540, a bucket point ground contact request determination unit 550, and a bucket target movement calculation unit 560.

[0049] The attitude calculation unit 310 calculates the attitude of the work machine 1 based on the information from the attitude measurement device 200 .

[0050] The required movement calculation unit 320 calculates the movement direction required of the work machine 1 based on the operation input device 33 and attitude information.

[0051] The below distance calculation unit 330 uses the attitude and position information of the work machine 1 to calculate the distance to the construction target surface located below the bucket 22 .

[0052] The target speed calculation unit 410 calculates the target speed of the actuator 2ACT in accordance with the attitude information of the work machine 1, the target surface distance, and the required operation.

[0053] The target speed correction unit 420 corrects the target speed of the actuator 2ACT based on the calculation result of the target speed calculation unit 410 and taking into consideration the determination result of the bucket target motion calculation unit 560.

[0054] The motion command value correcting unit 430 corrects and generates a motion command value for controlling the driving device 35 based on the target speed of the actuator 2ACT corrected by the target speed correcting unit 420. The corrected motion command value is output to the driving device 35.

[0055] The lateral distance calculation unit 500 uses the posture and position information of the work machine 1 and the bucket line information set in the bucket line setting unit 520 to calculate the distance between the bucket line of the bucket 22 and the construction target surface located to the side.

[0056] The bucket line relative angle calculation unit 510 calculates the relative angle between the bucket line set in the bucket line setting unit 520 and the construction target surface.

[0057] The bucket line setting unit 520 sets multiple candidates for bucket lines, which are line segments at the ends of the bucket 22, through input operations by the operator, etc.

[0058] The soil hardness determination unit 530 determines the hardness of the soil excavated by the bucket 22 based on the attitude information of the work machine 1 and the load information of the load measuring device 210 .

[0059] The requested bucket line selection unit 540 selects the target bucket line requested by the operator from the multiple bucket line candidates set by the bucket line setting unit 520 based on the distance between the bucket line and the target surface, the relative angle between the bucket line and the target surface, the requested action of the operator, the attitude information of the work machine 1, etc.

[0060] The bucket point contact request determination unit 550 determines whether or not there is a request from the operator to contact the bucket 22 at a point with the construction target surface based on the distance between the bucket line and the target surface, the relative angle between the bucket line and the target surface, the requested action of the operator, posture information of the work machine 1, etc.

[0061] The bucket target movement calculation unit 560 calculates the target movement of the bucket 22 based on the calculation results of the required bucket line selection unit 540, the bucket point ground contact request determination unit 550, the attitude calculation unit 310, the required movement calculation unit 320, and the target speed calculation unit 410.

[0062] <Device Operation and Calculation Method>

[0063] <Basic Operation of Machine Control> As shown in FIG. 1, in machine control, the operation of the work machine 1 is controlled based on the operation of the operator so that the work implement of the work machine 1 does not dig too far below the construction target surface.

[0064] For example, when the operator performs crowding of the arm 21 in the state shown in Figure 1, the boom 20 automatically rises and lowers so that the tip of the bucket 22 moves along the construction target surface. This allows the operator to perform excavation work along the construction target surface without requiring skilled operation. The direction of movement of the rotating body 3 is also controlled by machine control so that it follows the construction target surface based on the movement of the work front 2 or the operation of the operator.

[0065] Furthermore, when the operator enables machine control of the bucket 22, the operation of the bucket 22 is controlled so that the attitude of the bucket 22 relative to the construction target surface is kept constant. This allows the operator to perform excavation work by simply crowding the arm 21 to set the bucket 22 in a predetermined attitude, without having to perform delicate lever operations on the bucket 22. For details on the calculation method for the basic operation of machine control, please refer to Patent No. 6872666, etc.

[0066] <Operator's Required Actions Regarding the Bucket> The end of the bucket 22 includes several straight portions, and the operator performs excavation work to make the excavation target smooth by aligning these straight ends with the construction target surface. In this invention, these straight ends of the bucket 22 are referred to as the bucket line.

[0067] FIG. 5 is a diagram schematically illustrating an example of a typical bucket line.

[0068] As shown in FIG. 5 , the bucket lines of a standard bucket include a line segment connecting the toes of the left and right ends of the five or so bucket claws (see "toe"), left and right line segments connecting the top of the bucket to the toe and including the side cutters (see "front left side cutter" and "front right side cutter"), a line segment connecting the left and right rear ends of the bucket bottom (see "bottom rear end"), and left and right line segments connecting the bucket toe and the rear end of the bucket bottom ("bottom left side" and "bottom right side").

[0069] The bucket lines of a slope bucket include the line segment connecting the left and right toes of the bucket (see "toe"), the left and right line segments connecting the top of the bucket to the toe and including the side cutters (see "front left side cutter" and "front right side cutter"), the line segment connecting the left and right rear ends of the bucket bottom (see "bottom rear end"), the left and right line segments connecting the bucket toe and the rear end of the bucket bottom (see "bottom left side" and "bottom right side"), and the left and right line segments connecting the top of the bucket and the rear end of the bucket bottom ("rear left side" and "rear right side").

[0070] The bucket 22 has a wide variety of shapes, and this example is merely one example. In this embodiment, the operator can accommodate buckets of any shape by presetting bucket lines in the main controller 34. Furthermore, if there is a bucket line that the operator does not want to use, the operator can disable the bucket line, allowing the operator to use only the necessary bucket lines.

[0071] 6, 7, and 8 are diagrams for explaining the requested operation of the operator with respect to the bucket during excavation work using machine control.

[0072] First, as shown in Figure 6, when working on a slope with the work machine 1 parallel to the slope (construction target surface F1), excavation is performed by combining a boom lowering operation, a swing operation, and a bucket dump operation. At this time, to excavate the slope, which is the construction target surface F1, so that it is smooth, the line segment connecting the toe of the right side of the bucket and the rear end of the bucket bottom (see "right side of bottom surface" in Figure 5) needs to be parallel to the slope, which is the construction target surface F1. Therefore, when the bucket 22 is near the construction target surface F1 and excavating the slope involves boom lowering and swing operations, the operator's required operation of the bucket 22 is to make the line segment connecting the toe of the left side of the bucket and the rear end of the bucket bottom (the bucket line L1 selected by the required bucket line selection unit 540, described below) parallel to the construction target surface F1.

[0073] Next, as shown in Figure 7, when working on a wall such as a trench, with the work machine 1 and the trench parallel, excavation is performed by combining arm crowding, boom raising, left swing, and bucket dumping. At this time, the line segment on the right side of the bucket, connecting the top of the bucket 22 to the toe and including the side cutter, needs to be parallel to the trench wall, which is the construction target surface. Therefore, when the bucket 22 is near the construction target surface and excavating the trench wall by arm crowding and boom raising, the operator's requested operation of the bucket 22 is that the line segment on the right side of the bucket, connecting the top of the bucket to the toe and including the side cutter (see "front right side cutter" in Figure 5), (bucket line L2 selected by requested bucket line selector 540, described below) be parallel to the construction target surface. In particular, if the trench wall surface and the direction of arm movement are not parallel, the excavation operation will be combined with a swing operation, but in order to continuously excavate the trench wall surface with the line segment on the right side of the bucket (bucket line L2) that connects the top of the bucket with the toe and includes the side cutter, the line segment on the right side of the bucket that connects the top of the bucket with the toe and includes the side cutter (bucket line L2) must be parallel to the swing center. Therefore, the operation required of the operator with respect to the bucket 22 is to make the line segment on the right side of the bucket that connects the top of the bucket with the toe and includes the side cutter (bucket line L2) parallel to the swing center axis C.

[0074] 8 , if the construction target surface F3 is tilted with respect to the directions in which the boom 20, arm 21, and bucket 22 can move, simply changing the attitude of the bucket 22 by operating the bucket 22 to either dump or crowd will not make the bucket line of the bucket toe (bucket line L3 selected by a requested bucket line selection unit 540, described below) parallel to the construction target surface F3, and the bucket 22 and the construction target surface F3 will come into contact with the ground at a contact point P. In this way, if the bucket line L3 and the construction target surface F3 cannot be made parallel by simply changing the attitude of the bucket 22, the operator's requested action for the bucket 22 is for the bucket 22 not to be driven. In other words, the relative angle between the arm 21 and the bucket 22 will not change.

[0075] Furthermore, when using the bucket 22 to excavate soil or other objects, if the ground to be excavated is hard, the excavation force will decrease if the bucket 22 makes linear or planar contact with the object. In such cases, the operator may increase the excavation force by point-contacting only the right or left end of the toe with the object. Therefore, if the object to be excavated is hard and contact with the bucket line would decrease the excavation force, the required action of the bucket 22 from the operator is to point-contact the bucket 22 with the construction target surface.

[0076] Note that the above is an example of the operator's required actions for the bucket 22, and the operator changes the required actions for the bucket 22 from moment to moment during excavation work depending on the shape of the construction target surface, the positional relationship between the construction target surface and the work machine 1, and the shape of the bucket 22.

[0077] <Method of calculating operator-requested movement: requested movement calculation unit 320> The movement requested by the operator to the work machine 1 is calculated as a requested movement command value based on the lever operation amount of the operation input device 33 and the attitude of the work machine 1, and is the movement obtained as a result of control using the calculated requested movement command value. All work machines 1 are mechanically connected, and there is a one-to-one correspondence between the levers operated by the operator and the movements of the actuators, so the lever operation amount is obtained as the speed of each actuator, that is, the requested speed. Therefore, for example, it is possible to express as a vector the direction and amount of movement of the tip of the bucket 22 in response to the lever operation amount. Many methods of expressing vectors are discussed in publicly known documents targeting machine control.

[0078] <Method of calculating distance and relative angle of bucket line with respect to construction target surface: downward distance calculation unit 330, lateral distance calculation unit 500, bucket line relative angle calculation unit 510> Figures 9 and 10 are diagrams explaining a method of calculating the distance and relative angle of the bucket line with respect to the construction target surface.

[0079] As shown in FIG. 9, the work machine 1 has an X-axis and a Z-axis that are perpendicular to each other and extend in the directions in which the boom 20, arm 21, and bucket 22 move relative to the boom foot pin, and a Y-axis is defined that is perpendicular to these axes.

[0080] When the construction target surface F4 is located below the bucket 22, one of the angles between the bucket line L4 at the bucket toe and the construction target surface F4 is the angle θ1 formed by the construction target surface F4 and an extension of the bucket line L4 when viewed from the YZ plane, with the point where the bucket line L4 extends and intersects with the construction target surface F4 as the vertex. The distance between the bucket line L4 and the construction target surface F4 is the shortest distance D1 from the end point of the bucket line L4 to the construction target surface F4.

[0081] 10, if the construction target surface F5 is located on the front side of the bucket 22, and the line segment connecting the top end of the bucket and the toe of the bucket is defined as bucket line L5, one of the angles between the construction target surface F5 and the bucket line L5 is angle θ2 when viewed from the X-Z plane, with the point where the bucket line L5 is extended and intersects with the Y-Z plane as the vertex. The distance between the bucket line L5 and the construction target surface F5 is the shortest distance D2 from the end point of the bucket line L5 to the construction target surface F5.

[0082] Although one bucket angle for one bucket line has been described above as a typical example, up to three angles can be determined from the XY plane, YZ plane, and XZ plane depending on the positional relationship between the bucket 22 and the construction target surface. If multiple angles between the bucket line and the construction target surface can be defined, angle information to be determined for each work scene can be determined in advance, or judgment criteria can be set for up to all three angles.

[0083] <Method for Selecting a Bucket Line Requested by the Operator: Requested Bucket Line Selector 540> First, the construction target surface that the operator requests to follow using machine control is selected based on the distance between the construction target surface and the bucket 22 and the requested movement direction of the operator relative to the front work surface 2 based on lever operation. Next, the relative angle of the bucket line with respect to the selected construction target surface and the distance between the selected construction target surface and the bucket line are calculated. At this time, the relative angle of the bucket line with respect to the construction target surface and the distance between the construction target surface and the bucket line are calculated for multiple bucket lines, and the bucket line that is closest to the construction target surface for the bucket line with the smallest calculated relative angle is selected as the bucket line requested by the operator. Furthermore, if the specific movement direction requested by the operator relative to the arm 21 or the boom 20 has been determined, the bucket line requested by the operator may be selected taking into account the state of the construction target surface that exists in the direction of movement of the arm 21 or the boom 20.

[0084] Specifically, as shown in FIG. 6 , when the right side of the bottom of the bucket has a small relative angle with the construction target surface and is the bucket line closest to the construction target surface, if the operator performs a swing operation and also performs a boom or arm operation, it can be determined that the operator wants to use the right side of the bottom of the bucket to perform shaping excavation on the slope that is the construction target surface, and therefore it can be determined that the bucket line required by the operator is the right side of the bottom of the bucket.

[0085] <Method for determining a requirement for bucket point contact: bucket point contact requirement determination unit 550> As described above, when the bucket line cannot be made parallel to the construction target surface by the operation of the bucket 22 alone, or when the ground to be excavated is hard and it is necessary to ensure excavation force, it may be necessary to make point contact between the bucket 22 and the object to be excavated rather than making linear contact with the bucket line.

[0086] First, a method for determining when the bucket line cannot be made parallel to the construction target surface by the operation of the bucket 22 will be described. Whether the bucket line can be made parallel to the construction target surface is determined by calculating the operating range of the bucket 22 from a mechanical model built into the controller. The operating range of the bucket 22 is calculated mechanically from the maximum extended length and minimum retracted length of the bucket cylinder 22A. Within the calculated operating range of the bucket 22, a bucket line is selected from among multiple bucket lines, and whether the selected bucket line can be made parallel to the construction target surface is determined based on the angle between the bucket line and the construction target surface. If no bucket line can be made parallel to the construction target surface (all bucket lines form an angle with the construction target surface greater than a predetermined angle), and it is determined that the bucket line cannot be made parallel to the construction target surface, it is determined that the operator has requested that the bucket 22 and the excavation object be brought into point contact with each other. 8, if the construction target surface is tilted with respect to the direction in which the boom 20, arm 21, and bucket 22 can move, operating the bucket 22 to either dump or crowd will not reduce the angle between the selected bucket line related to the bucket toe and the construction target surface to a predetermined angle or less simply by changing the attitude of the bucket 22, so it is determined that the bucket line cannot be made parallel to the construction target surface, as described above, and it is determined that point contact is required. Note that the predetermined angle here refers to an angle that is preset as an allowable value for determining that the bucket line and the construction target surface are parallel, and is stored in a memory (not shown).

[0087] If the ground to be excavated is hard and it is necessary to ensure excavation force, the hardness of the ground can be judged, and if the ground is hard, it can be determined that the operator requires the bucket 22 to make point contact with the object to be excavated.

[0088] <Method of Determining Soil Hardness: Soil Hardness Determination Unit 530> The soil hardness is determined by calculating the excavation reaction force of the bucket 22 from a pressure sensor attached to the front work unit 2 and the attitude of the front work unit 2. Note that known prior art (for example, WO 2020 / 049623) can be used as the determination method.

[0089] <Method for Calculating Bucket Target Motion: Bucket Target Motion Calculation Unit 560> The method for calculating the bucket target motion will be described. First, when the bucket 22 is a predetermined distance from the construction target surface, machine control angle control of the bucket 22 becomes effective. Next, as described above, the operator's requested motion direction is calculated, and the bucket line requested by the operator is selected. Then, it is determined whether or not there is a bucket point contact request. If a bucket point contact request is requested, the target motion is calculated so that the bucket 22 is not driven. In other words, the bucket target speed is set to zero so that the relative angle between the bucket 22 and the arm 21 is maintained. On the other hand, if there is no bucket point contact request, the target motion is to drive the bucket 22 so that the construction target surface becomes parallel to the selected bucket line when the selected bucket line is within a predetermined distance and a predetermined relative angle from the construction target surface. To calculate the target speed of the bucket 22, a general proportional-integral-differential controller (PID) control may be performed for the error in the relative angle between the bucket line and the construction target surface, or a pre-designed table value may be used. In addition, when the operator is performing manual operation on the bucket 22, the target movement resulting from the operator's manual operation may be given priority, or the target movement resulting from the operator's manual operation may be compared with the target movement of the bucket 22 described above, and the value with the greater movement speed in the movement direction may be given priority.

[0090] Furthermore, depending on the positional relationship between the bucket line and the construction target surface, there may be multiple postures of the bucket 22 where the bucket line and the construction target surface are parallel. In this case, the posture of the bucket 22 that has the least amount of change from the posture of the bucket 22 at that time is set as the target posture.

[0091] <Control Procedure> FIG. 11 is a flowchart showing the processing contents of the main controller.

[0092] As shown in FIG. 11 , first, the main controller acquires and calculates the attitude of the work machine (step S100), acquires information about the construction target surface (step S110), acquires the amount of operation by the operator (step S120), calculates the direction of movement requested by the operator from the attitude of the work machine and the amount of operation by the operator (step S130), calculates the distance between the construction target surface and the bucket line (step S140), calculates the relative angle between the construction target surface and the bucket line (step S150), determines the operation requested by the operator with respect to the bucket (in other words, selects the requested bucket line) (step S170), and calculates a basic machine control target speed with respect to the work front (step S180).

[0093] Here, it is determined whether or not there is a request for the bucket to touch down at a point based on whether or not the angle formed by the bucket line and the construction target surface is greater than a predetermined angle (step S190).

[0094] If the determination result in step S190 is YES, that is, if the angle between the bucket line and the construction target surface is greater than a predetermined angle (if there is a point contact request), the target speed of the bucket is not corrected (step S200).

[0095] If the determination result in step S190 is NO, that is, if there is no point contact request, the target speed of the bucket is calculated and corrected so that the selected bucket line and the construction target surface are parallel (step S210).

[0096] Once the processing of step S200 or S210 is completed, the target speed calculated from the amount of operation of the bucket by the operator is compared with the target speed of the bucket calculated in step S180 or S210, and it is determined whether the target speed calculated from the amount of operation of the bucket by the operator (see step S180) is greater than the corrected target speed (see step S210) (step S220).

[0097] If the determination result in step S220 is YES, that is, if the target speed calculated from the amount of operation of the operator with respect to the bucket (see step S180) is greater than the corrected target speed (see step S210), the target speed of the bucket is set to the target speed calculated from the amount of operation of the operator with respect to the bucket (step S230).

[0098] If the determination result in step S220 is NO, the target speed of the bucket is set to the corrected target speed of the bucket (see step S210) (step S240).

[0099] After the processing of step S230 or S240 is completed, an operation command value is calculated in accordance with the set target speed of the bucket (step S250), and the processing ends.

[0100] Instead of the flowchart of the embodiment shown in Figure 11 described above, step S160 for determining soil hardness may be added between steps S150 and S170 in Figure 11, as in the modified example shown in Figure 12. In step S190 of the modified example shown in Figure 12, if the soil hardness is determined to be hard based on the excavation reaction force of the bucket 22, it is determined that there is a point ground contact request (YES), and if the soil hardness is determined to be soft based on the excavation reaction force of the bucket 22, it is determined that there is no point ground contact request (NO). The rest is the same as the flowchart of Figure 11.

[0101] <Effects of this embodiment> As described above, according to this embodiment, a bucket line is set with respect to the linear end of the bucket, the bucket movement intended by the operator is determined based on the distance and relative angle between the target surface and the bucket line, and the bucket movement can be controlled so that the target surface and the bucket line are parallel to match the bucket movement intended by the operator, or the bucket movement can be controlled so that the target surface and the bucket line come into point contact with each other. This allows the bucket to have the working posture and perform the bucket work intended by the operator, improving the operability of the work machine.

[0102] <Others> The present invention is not limited to the above-described embodiments and includes various modifications within the scope of the gist thereof. For example, the present invention is not limited to those including all of the configurations described in the above-described embodiments and includes those in which some of the configurations are omitted. It is also possible to add or replace part of the configuration of one embodiment with the configuration of another embodiment. Furthermore, the components of the above-described control device, as well as their functions and execution processes, may be implemented in part or in whole by hardware (e.g., by designing logic that executes each function using an integrated circuit). Furthermore, the components of the above-described control device may be implemented as a program (software) that is read and executed by an arithmetic processing device (e.g., a CPU) to realize the functions of the control device. Information related to the program may be stored, for example, in semiconductor memory (e.g., flash memory, SSD), magnetic storage device (e.g., hard disk drive), or recording medium (e.g., magnetic disk, optical disk), etc.

[0103] 1...work machine, 2...work front, 2ACT...actuator, 2S...swing angle sensor, 3...swing body, 4...traveling body, 20...boom, 20A...boom cylinder, 20BP...pressure sensor (boom bottom), 20RP...pressure sensor (boom rod), 20S, 21S, 22S, 30S...IMU (inertial measurement unit), 21...arm, 21A...arm cylinder, 21BP...pressure sensor (arm bottom), 21RP...pressure sensor (arm rod), 22...bucket, 22A...bucket cylinder, 22BP...pressure sensor (bucket bottom), 22RP...pressure sensor (bucket rod), 31...main frame, 32...operator's cab, 33...operation input device, 34...main controller, 3 5...Drive unit, 36...Engine / pump (prime mover), 37...Swing load measuring device, 41...Travel motor, 45...Crawler, 100...Setting input display device, 200...Attitude measuring device, 210...Load measuring device, 250...Position measuring device, 310...Attitude calculation unit, 320...Required movement calculation unit, 330...Downward distance calculation unit, 410...Target speed calculation unit, 420...Target speed correction unit, 430...Motion command value correction unit, 500...Side distance calculation unit, 510...Bucket line relative angle calculation unit, 520...Bucket line setting unit, 530...Soil hardness judgment unit, 540...Required bucket line selection unit, 550...Bucket point ground contact request judgment unit, 560...Bucket target movement calculation unit, 2000...Construction surface management device, A22B, B22C...Link

Claims

1. A working machine comprising: a traveling body; an upper swing body rotatably provided with respect to the traveling body; a working device having at least a bucket and swingable in the vertical direction with respect to the upper swing body; an actuator for driving the upper swing body and the working device respectively; an operating device for operating the actuator; an operation amount detection device for detecting an operation amount of the operating device; a posture detection device for detecting postures of the upper swing body and the working device; a target surface setting device for setting a target surface to be excavated by the bucket; a control device for calculating a required operation direction for the bucket based on the operation amount detected by the operation amount detection device and the posture detected by the posture detection device, and calculating an operation command value for the actuator such that the bucket follows the target surface based on the required operation direction; and a driving device for driving the actuator based on the operation command value calculated by the control device. In the working machine, the control device includes: a bucket line setting unit for setting a plurality of candidates for a bucket line which is a line segment at an end of the bucket; a bucket line calculation unit for calculating a positional relationship between the plurality of bucket line candidates and the target surface using at least their distances or relative angles; a required bucket line selection unit for selecting a bucket line corresponding to a required excavation operation from the plurality of bucket line candidates based on the positional relationship and the operation amount; and an operation command value correction unit for correcting the operation command value of the bucket so that an angle between the bucket line selected by the required bucket line selection unit and the target surface becomes smaller.

2. The working machine according to claim 1, wherein the bucket line setting unit sets, as candidates for the bucket line, at least one or more line segments including a line segment connecting the tips of the right and left ends of the bucket, a line segment connecting the rear ends of the right and left ends of the bucket, a line segment connecting the upper right end and the lower right end on the front surface of the bucket, a line segment connecting the upper left end and the lower left end on the front surface of the bucket, a line segment connecting the tip of the right end and the rear end of the right end on the bottom surface of the bucket, a line segment connecting the tip of the left end and the rear end of the left end of the bucket on the bottom surface of the bucket, a line segment connecting the upper and lower parts of the rear end of the right end of the bucket, and a line segment connecting the upper and lower parts of the rear end of the left end of the bucket.

3. In the working machine according to claim 1 or 2, the control device includes a point grounding requirement determination unit that determines a requirement for grounding the bucket and the target surface at one point based on the operation amount for the working device, the target surface, and the posture of the working device. When the point grounding requirement determination unit determines that there is a point grounding requirement between the bucket and the target surface, the operation command value correction unit corrects the operation command value of the bucket so that the target speed of the actuator that drives the bucket becomes zero. A working machine characterized by this.

4. In the working machine according to claim 3, the point grounding requirement determination unit determines whether the target surface and the bucket line can be made parallel when only the posture of the bucket is changed. When it is determined that they cannot be made parallel, it is determined that there is a requirement to point - ground the bucket line to the target surface. A working machine characterized by this.

5. In the working machine according to claim 3, the point grounding requirement determination unit determines the hardness of the ground excavated by the bucket. When it is determined that the ground is hard, it is determined that there is a requirement to point - ground the bucket line to the target surface. A working machine characterized by this.

6. In the working machine according to claim 1 or 2, the required bucket line selection unit determines, as the bucket line corresponding to the excavation work required by the operator, the candidate bucket line with the smallest distance or relative angle from the candidate bucket lines to the target surface. A working machine characterized by this.

7. In the working machine according to claim 1 or 2, when the operation command value correction unit of the control device includes the slewing operation of the upper slewing body in the operation amount, and when it is determined that there are a plurality of postures of the bucket in which the bucket line and the target surface are parallel, the operation command value of the bucket is corrected so that the bucket line and the rotation center axis of the slewing operation of the upper slewing body are parallel. A working machine characterized by this.

8. In the working machine according to claim 1 or 2, when it is determined that there are a plurality of postures of the bucket in which the bucket line and the target surface are parallel, the operation command value correction unit of the control device corrects the operation command value of the bucket so that the displacement amount of the bucket is minimized. A working machine characterized by this.

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