Work machinery

Abstract

The purpose of the present invention is to provide a work machine with which an implement can be accurately operated along a construction target surface in the vicinity of the construction target surface, and when the implement is not in the vicinity of the construction target surface, an operator can perform operation while recognizing the load acting on the work front. For this purpose, the controller calculates the target speed of the actuator on the basis of the operation amount of the operation input device, the attitude of the machine body and the work front, and the distance between the implement and the construction target surface, calculates an operation command value for the actuator on the basis of the target speed, calculates a correction amount for the operation command value on the basis of the load of the actuator detected by a load detection device 27, and adds the correction amount to the operation command value.

Description

[Technical Field]

[0001] The present invention relates to a work machine used for road construction, construction work, civil engineering work, dredging work, demolition work, etc. [Background technology]

[0002] Known work machines used in road construction, building construction, civil engineering, dredging, etc. include a work machine body having a rotating body rotatably attached to the top of a traveling body that travels by a power system, a multi-jointed work front attached to the work machine body so that it can swing freely up and down, and each front member that makes up 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.

[0003] Some hydraulic excavators of this type perform so-called machine control, in which a target surface to be excavated with the bucket is set and boom movement is automatically controlled according to the distance between the target surface and the bucket so that the bucket can excavate along the target surface.

[0004] Incidentally, with this type of hydraulic excavator, it is necessary to accurately control the operating state of the work front, i.e., the operating speed of the hydraulic cylinder, in order to enable the bucket to accurately excavate along the construction target surface. Patent Document 1 discloses a technology for controlling the speed of the hydraulic cylinder by providing a data acquisition unit that acquires data related to an operation command value and cylinder speed, and a derivation unit that derives an operation start operation command value when a stopped hydraulic cylinder starts operating, and slow-speed operation characteristics that indicate the relationship between the operation command value and the cylinder speed in the slow-speed region. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. 2015 / 137524 Summary of the Invention [Problem to be solved by the invention]

[0006] In a work machine, such as a hydraulic excavator, the positional relationship between the target surface and the work front varies for each task. Furthermore, since the work front is moved along the target surface to perform excavation, the posture of the work front is constantly changing. Therefore, the load acting on the hydraulic cylinder changes from moment to moment in response to changes in the working posture during excavation work.

[0007] Generally, the operating speed of a hydraulic cylinder changes depending on the amount of hydraulic oil inserted into the hydraulic cylinder and the load acting on the hydraulic cylinder. Therefore, when the operating command value is constant, the operating speed of the hydraulic cylinder slows down as the load acting on the hydraulic cylinder increases.

[0008] However, the technology described in Patent Document 1 measures the operation command value and the operating characteristics of the hydraulic cylinder in a specific working posture, so if the posture of the work front changes during excavation work, the cylinder speed cannot be accurately controlled, making it impossible to excavate accurately along the construction target surface.

[0009] On the other hand, the operating speed of a hydraulic excavator changes depending on the load acting on the front work surface, i.e., the load acting on the hydraulic cylinder, making it easier for the operator to recognize the load state on the front work surface. Therefore, if the operating speed of the hydraulic cylinder becomes a constant speed regardless of the load on the front work surface, it becomes difficult for the operator to recognize the load acting on the front work surface, resulting in poor operability.

[0010] The present invention has been made in consideration of the above-mentioned problems, and its object is to provide a work machine that is capable of accurately moving a work implement along a work target surface near the work target surface, and that allows the operator to operate the work implement while being aware of the load acting on the work front when the work implement is not near the work target surface. [Means for solving the problem]

[0011] In order to achieve the above object, the present invention provides a work front including a machine body, a work tool attached to the machine body so as to be rotatable in the vertical direction, an actuator for driving the work front, a drive device for driving the actuator, and a front a load detection device that detects the load on the actuator, and the controller calculates a target speed for the actuator based on the amount of operation of the operation input device, the attitude, and the distance between the work tool and the target surface, calculates a motion command value for the actuator based on the target speed, calculates a correction amount to be added to the motion command value based on the load on the actuator detected by the load detection device so that the actuator operates at the target speed regardless of the magnitude of the load on the actuator, limits the correction amount based on the distance between the work tool and the target surface and the motion direction of the work tool relative to the target surface, and adds the limited correction amount to the motion command value.

[0012] According to the present invention configured as described above, an operation command value for the actuator is calculated so as to reduce the distance between the work tool and the work target surface, a correction amount for the operation command value is calculated based on the load on the actuator, and the correction amount is added to the operation command value. This makes it possible to accurately operate the work tool along the work target surface near the work target surface regardless of the magnitude of the load on the actuator, and when the work tool is not near the work target surface, it becomes possible for the operator to perform operations while being aware of the load acting on the work front. [Effects of the Invention]

[0013] With the work machine of the present invention, when the work tool is near the target surface, it is possible to operate the work tool accurately along the target surface regardless of the magnitude of the load on the actuator, and when the work tool is not near the target surface, the operator can operate the work tool while being aware of the load acting on the work front. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 1 is a side view of a hydraulic excavator according to an embodiment of the present invention. [Figure 2] FIG. 1 is a configuration diagram of a control system according to an embodiment of the present invention. [Figure 3] 1 is a functional block diagram of an information processing device according to an embodiment of the present invention. [Figure 4] FIG. 1 is a diagram illustrating an example of the operation of a hydraulic excavator. [Figure 5] FIG. 2 is a diagram showing the operating characteristics of a hydraulic cylinder. [Figure 6] FIG. 10 is a diagram showing an excavation trajectory by machine control when the operation command value of the boom cylinder is not corrected. [Figure 7] FIG. 10 is a diagram illustrating a required motion vector according to an embodiment of the present invention. [Figure 8] FIG. 10 is a diagram illustrating a correction gain according to an embodiment of the present invention. [Figure 9] 10A and 10B are diagrams illustrating an example of correction of an operation command value in the embodiment of the present invention. [Figure 10] FIG. 10 is a diagram illustrating a method for estimating a load on a boom cylinder according to an embodiment of the present invention. [Figure 11] FIG. 10 is a diagram showing an e-digging trajectory by machine control in an embodiment of the present invention. [Figure 12] 4 is a flowchart illustrating a process of the information processing device according to the embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0015] Hereinafter, a hydraulic excavator will be described as an example of a work machine according to an embodiment of the present invention with reference to the drawings. In each drawing, the same reference numerals are used to designate the same components, and redundant description will be omitted where appropriate.

[0016] <Hydraulic excavator> Fig. 1 is a side view of a hydraulic excavator according to this embodiment. As shown in Fig. 1, the hydraulic excavator 1 includes a front work unit 2, a revolving unit 3 constituting the machine body, and a traveling unit 4.

[0017] The front work unit 2 is configured to rotate relative to the revolving unit 3, and the revolving unit 3 is configured to rotate relative to the running unit 4, each around a connecting portion. The front work unit 2 includes a boom 20 having one end connected to the revolving unit 3, an arm 21 having one end connected to the boom 20, a bucket 22 as a working implement having one end connected to the arm 21, a boom cylinder 20A having both ends connected to the boom 20 and the revolving unit 3, respectively, an arm cylinder 21A having both ends connected to the arm 21 and the boom 20, respectively, a first link 22B having one end connected to the arm 21, a second link 22C having one end connected to the bucket 22, and a bucket cylinder 22A having one end connected to the other ends of the first link 22B and the second link 22C and the other end connected to the arm 21. These members are configured to rotate vertically around their respective connecting portions. The running unit 4 includes a travel motor 41 and a crawler track 42.

[0018] The boom cylinder 20A, arm cylinder 21A, and bucket cylinder 22A are each hydraulically extendable and retractable, allowing the boom 20, arm 21, and bucket 22 to rotate, respectively. Pressure sensors 20BP and 20RP are attached to the boom cylinder 20A for detecting the pressure on the bottom side and rod side, respectively. Pressure sensors 21BP and 21RP are attached to the arm cylinder 21A for detecting the pressure on the bottom side and rod side, respectively. Pressure sensors 22BP and 22RP are attached to the bucket cylinder 22A for detecting the pressure on the bottom side and rod side, respectively. The bucket 22 can be replaced with any attachment (not shown), such as a grapple, breaker, ripper, or magnet.

[0019] A boom IMU (Inertial Measurement Unit) 20S is attached to the boom 20 to detect the attitude of the boom 20. An arm IMU 21S is attached to the arm 21 to detect the attitude of the arm 21. A bucket IMU 22S is attached to the first link 22B to detect the attitude of the bucket 22. The boom IMU 20S, arm IMU 21S, and bucket IMU 22S each include an angular velocity sensor and an acceleration sensor.

[0020] The rotating unit 3 includes a rotating unit IMU 30S, a main frame 31, a cab 32, an information processing device 34, a drive unit 35, a prime mover 36, a counterweight 37, and a rotation motor 38. The rotating unit IMU 30S, the cab 32, the information processing device 34, the drive unit 35, the prime mover 36, the counterweight 37, and the rotation motor 38 are arranged on the main frame 31. The rotating unit IMU 30S is composed of an acceleration sensor and an angular velocity sensor and can detect the tilt angle of the rotating unit 3. The cab 32 is provided with an operation input device 33, a target surface information setting device 100, an image display device 110, and a machine information setting device 120. The operation input device 33, the information processing device 34, the drive unit 35, the prime mover 36, the target surface information setting device 100, the image display device 110, and the machine information setting device 120 will be described later with reference to FIG. 2 or FIG. 3.

[0021] The running body 4 includes a track frame 40, a travel motor 41, and crawler tracks 45. The crawler tracks 45 are installed so as to be able to move around the track frame 40, and are driven by the travel motor 41. The operator can adjust the traveling speed of the hydraulic excavator 1 by operating the operation input device 33 to change the rotation speed of the travel motor 41. Note that the running body 4 is not limited to one equipped with crawler tracks 45, and may also be one equipped with running wheels or legs.

[0022] <Control System> Fig. 2 is a configuration diagram of a control system mounted on the hydraulic excavator 1. In Fig. 2, the control system 10 is made up of an operation input device 33, an attitude detection device 30, a load detection device 27, an information processing device 34, a driving device 35, a prime mover 36, a target surface information setting device 100, an image display device 110, and a machine information setting device 120.

[0023] The operation input device 33 includes an operation lever 33a that is tilted by the operator, and an operation input amount sensor 33b. The tilt amount (operation amount) of the operation lever 33a is converted into an electric signal by the operation input amount sensor 33b and input to the information processing device 34. The operation input device 33 may be of a hydraulic pilot type or a type that can be operated from a remote location.

[0024] The attitude detection device 30 is equipped with an angular velocity sensor 30a and an acceleration sensor 30b, and can measure the angle between each member of the front work unit 2 and the rotating unit 3. The load detection device 27 is equipped with pressure sensors 20BP, 20RP, 21BP, 21RP, 22BP, and 22RP that detect the loads on the actuators 20A, 21A, and 22A that drive the front work unit 2.

[0025] The information processing device 34 includes an information processing controller 34a, and processes control signals and detection signals from each device. The operation input device 33, the attitude detection device 30, the load detection device 27, the target surface information setting device 100, the image display device 110, and the machine information setting device 120 are connected to the information processing device 34. The information processing device 34 also outputs operation command values ​​for driving the hydraulic excavator 1 to the drive device 35.

[0026] The drive unit 35 is composed of a hydraulic pump 35a, a directional control valve 35b, and an electromagnetic control valve 35c. The hydraulic pump 35a generates the hydraulic pressure required to operate the hydraulic excavator 1. The electromagnetic control valve 35c drives the directional control valve 35b in response to an operation command value from the information processing device 34. The directional control valve 35b controls the flow rate and direction of the pressure oil supplied from the hydraulic pump 35a to each actuator (boom cylinder 20A, arm cylinder 21A, bucket cylinder 22A, swing motor 38, and traveling motor 41). The drive unit 35 can also drive attachments and equipment not included above.

[0027] The prime mover 36 is made up of an engine 36a. The engine 36a drives a hydraulic pump 35a. However, the prime mover 36 is not limited to this configuration, and other power sources such as an electric motor may also be used.

[0028] The target surface information setting device 100 is equipped with a target surface information setting controller 100a, and is capable of setting and managing a construction target surface. The image display device 110 is equipped with a display monitor 110a, and is capable of displaying to the operator the attitude of the hydraulic excavator 1, information about the construction target surface set by the target surface information setting device 100, the positional relationship and distance between the work front 2 and the construction target surface, etc. The machine information setting device 120 is equipped with a machine information setting controller 120a, and is capable of setting the mass of the bucket 22 attached to the work front 2, the position of the center of gravity of the work front 2, etc. as machine information.

[0029] <Operation input device> The hydraulic excavator 1 is generally configured so that the operating speed of the actuators increases as the tilt amount of the control lever 33a increases. The operator can change the operating speed of each of the actuators 20A, 21A, 22A, 38, and 41 by adjusting the tilt amount of the control lever 33a. The operation input device 33 is equipped with an operation input amount sensor 33b that electrically detects the tilt amount of the control lever 33a, and can detect the target operation of each actuator requested by the operator. The operation input amount sensor 33b is not limited to one that directly detects the tilt amount of the control lever 33a, and may be a type that detects the operation pilot pressure.

[0030] <Posture detection device> The posture detection device 30 is composed of angular velocity sensors and acceleration sensors provided in the rotating structure IMU 30S, boom IMU 20S, arm IMU 21S, and bucket IMU 22S, respectively, and can obtain angular velocity information and acceleration information at each position. The boom 20, arm 21, bucket 22, boom cylinder 20A, arm cylinder 21A, bucket cylinder 22A, first link 22B, second link 22C, and rotating structure 3 are each mounted so as to be able to swing, so the postures of the boom 20, arm 21, bucket 22, and rotating structure 3 can be estimated from the mechanical link relationships. Note that the posture detection method shown here is just an example, and the relative angles of each part of the front work unit 2 may be measured directly, or the posture of each part of the hydraulic excavator 1 may be calculated by detecting the strokes of the boom cylinder 20A, arm cylinder 21A, and bucket cylinder 22A.

[0031] <Load detection device> The load detection device 27 is made up of pressure sensors 20BP, 20RP that detect the pressure of the boom cylinder 20A, pressure sensors 21BP, 21RP that detect the pressure of the arm cylinder 21A, and pressure sensors 22BP, 22RP that detect the pressure of the bucket cylinder 22A. The pressure sensors may be attached directly to the cylinders, or may be attached on the path from the drive device 35 to the cylinders. Furthermore, the load detection device 27 is not limited to pressure sensors, and may be a load cell that directly detects the torque acting on the connection, or a system that detects the strain of the work front 2 to estimate the load, or a system that estimates the load from the output of the hydraulic pump 35a or the engine 36a may be used.

[0032] <Target surface information setting device> The target surface information setting device 100 can set a construction target surface that is to be an excavation target for the work front 2. The construction target surface may be set to have multiple planes in addition to a single plane, and it may also be possible to set a range that can be excavated by the work front 2. The construction target surface may be set in a coordinate system based on the work machine 1, or in a coordinate system based on the Earth.

[0033] <Drive unit> The drive device 35 is composed of a hydraulic pump 35a, a directional control valve 35b, and an electromagnetic control valve 35c, and drives the actuators 20A, 21A, 22A, 38, and 41 in accordance with an operation command value input from the information processing device 34. The operation command value input from the information processing device 34 is converted into a pilot pressure by the electromagnetic control valve 35c, and the directional control valve 35b is driven by this pilot pressure. The directional control valve 35b controls the operation speed of the actuators 20A, 21A, 22A, 38, and 41 by adjusting the flow rate of pressure oil supplied to the actuators 20A, 21A, 22A, 38, and 41.

[0034] <Information processing device> Fig. 3 is a functional block diagram of information processing device 34. In Fig. 3, information processing device 34 is made up of target speed calculation unit 310, movement command value calculation unit 320, attitude calculation unit 410, target surface distance calculation unit 420, required movement vector estimation unit 510, load estimation unit 520, movement command value correction amount calculation unit 610, and movement command value correction unit 620. Information processing device 34 is made up of controller 34a having a calculation processing function, an input / output interface that inputs and outputs signals to and from external devices, and the functions of each unit are realized by executing a program stored in a storage device such as a ROM.

[0035] The target speed calculation unit 310 calculates the target speed of the actuators 20A, 21A, 22A that drive the work front 2 based on the operation amount input to the operation input device 33 and the distance from the work front 2 to the construction target surface (for example, the distance from the bucket toe to the construction target surface) calculated by the target surface distance calculation unit 420, and outputs the target speed to the operation command value calculation unit 320 and the operation command value correction amount calculation unit 610.

[0036] The motion command value calculation unit 320 calculates a motion command value for driving the driving device 35 based on the target speed calculated by the target speed calculation unit 310 , and outputs the calculated value to the motion command value correction unit 620 .

[0037] The attitude calculation unit 410 calculates the attitudes of the front work unit 2 and the revolving unit 3 based on the angle information from the attitude detection device 30, and outputs them to the target surface distance calculation unit 420, the load estimation unit 520, and the operation command value correction amount calculation unit 610.

[0038] The target surface distance calculation unit 420 calculates the distance from the work front 2 to the construction target surface based on the setting information of the target surface information setting device 100 and the attitude of the work front 2 and the revolving body 3 calculated by the attitude calculation unit 410, and outputs the calculated distance to the operation command value correction amount calculation unit 610 and the image display device 110.

[0039] The required motion vector estimation unit 510 estimates the direction of the motion vector (required motion vector) of the front work tip (e.g., bucket tip) required by the operator based on the operation amount input to the operation input device 33, and outputs the estimated direction to the motion command value correction amount calculation unit 610.

[0040] The load estimation unit 520 estimates the load acting on each actuator that drives the work front 2 based on the load information from the load detection device 27, the setting information from the machine information setting device 120, and the attitude of the work front 2 and the rotating body 3 calculated by the attitude calculation unit 410, and outputs the load to the operation command value correction amount calculation unit 610.

[0041] The movement command value correction amount calculation unit 610 calculates a correction amount of the movement command value for driving the drive unit 35 based on the target speed of the work front 2 calculated by the target speed calculation unit 310, the attitude of the work front 2 and the revolving body 3 calculated by the attitude calculation unit 410, and the load on the work front 2 estimated by the load estimation unit 520, and outputs the calculated amount to the movement command value correction unit 620.

[0042] The motion command value correcting unit 620 limits the correction amount calculated by the motion command value correction amount calculating unit 610 in accordance with the required motion vector estimated by the required motion vector estimating unit 510 and the distance calculated by the target surface distance calculating unit 420, corrects the motion command value by adding the limited correction amount to the motion command value calculated by the motion command value calculating unit 320, and outputs the corrected motion command value to the driving device 35.

[0043] <Machine control operation> As shown in Figure 4, machine control automatically controls the boom 20 according to the operating speed of the arm 21 so that the bucket 22 moves along a preset construction target surface. For example, when an operator performs crowding of the arm 21 in the state shown in Figure 4, the boom 20 automatically rises so that the tip of the bucket moves along the construction target surface. This allows the operator to perform excavation work along the construction target surface without the need for skilled operation.

[0044] <Operation characteristics of hydraulic cylinders> Figure 5 shows an example of the relationship (operation characteristics) between the operation command value for driving the hydraulic cylinder and the hydraulic cylinder speed. When the load on the hydraulic cylinder is low, as shown by the solid line, the operation speed of the hydraulic cylinder increases rapidly as the operation command value increases. On the other hand, when the load on the hydraulic cylinder is high, as shown by the dotted line, the rate of increase in the hydraulic cylinder operation speed relative to the operation command value decreases compared to when the load on the hydraulic cylinder is low. Here, the load on the boom cylinder 20A varies mainly depending on the posture of the front work unit 2. Specifically, the load increases when the front work unit 2 is in the retracting posture and decreases when the front work unit is in the full reach posture. Therefore, to adjust the hydraulic cylinder to a specific speed, the operation command value must be corrected according to the load acting on the hydraulic cylinder. In Figure 5, the operation command value C2 for operating the hydraulic cylinder at speed V under high load is calculated by adding a load-dependent correction amount to the operation command value C1 for operating the hydraulic cylinder at speed V under low load.

[0045] A method for correcting the operation command value will be specifically described below. The operation speed of the hydraulic cylinder can be determined using the orifice equation (Equation 1).

[0046]

number

[0047] Q:Flow rate C: Flow coefficient A: Flow path cross-sectional area ΔP: differential pressure before and after Ρ:Fluid density In the hydraulic excavator 1, the flow rate Q is determined by the diameter of the hydraulic cylinder and the target speed, the flow coefficient C and fluid density P are determined by the physical properties of the hydraulic oil used, and the differential pressure ΔP across the hydraulic cylinder is determined by the load on the hydraulic cylinder as described below. The flow path cross-sectional area A can be adjusted by the operation command value.

[0048] That is, if it is desired to operate the hydraulic cylinder at a predetermined speed (that is, flow rate), the flow path cross-sectional area A (that is, operation command value) can be adjusted according to the front-to-back differential pressure ΔP, the flow coefficient C, and the fluid density P. In particular, when the hydraulic excavator 1 is operating, the front-to-back differential pressure ΔP changes significantly depending on the posture of the work front 2, while the changes in the flow coefficient C and fluid density P are small, so the operation command value can be adjusted according to the front-to-back differential pressure ΔP.

[0049] Furthermore, when calculating the operation command value based on the relationship between the operation amount and the operation command value, if the relationship between the operation amount and the operation command value and the relationship between the operation amount and the operation command value and the cylinder speed are identified in advance, the relationship between the operation amount and the operation command value can be set in advance.

[0050] <Effect of actuator load on excavation trajectory> The excavation trajectory by machine control when the operation command value of the boom cylinder 20A is not corrected is shown in Figure 6. When the load on the boom cylinder 20A is small, the error in the excavation trajectory relative to the construction target surface is small, as shown by the solid line. On the other hand, when the load on the boom cylinder 20A is large, the boom cylinder 20A cannot sufficiently lift the boom 20, and as shown by the dotted line, it digs too deep below the construction target surface, making it impossible to excavate accurately along the construction target surface.

[0051] In particular, when using the characteristic relationship between the operating speed and operating command value of the hydraulic cylinder obtained under specific conditions as in Patent Document 1, the greater the difference between the conditions under which the characteristics were obtained and the actual working posture and load, the greater the error between the construction target surface and the excavation trajectory.

[0052] <request action vector> The required operating speed of each actuator of the front work surface 2 is calculated from the operation amount input to the operation input device 33. The required operating speed of each actuator of the front work surface 2 can be converted into a required motion vector of the bucket tip from the geometric structure of the front work surface 2. As shown by the solid arrow in Figure 7, when the required motion vector of the bucket tip is in a direction away from the construction target surface, the operator is trying to move the bucket 22 away from the construction target surface, and therefore excavation controlled by machine control is not necessary. As shown by the dashed arrow in Figure 7, when the required motion vector of the bucket tip is in a direction approaching the construction target surface, the operator is trying to move the bucket 22 closer to the construction target surface, and therefore excavation controlled by machine control is necessary. In this way, it is possible to determine from the operation amount input to the operation input device 33 whether accurate actuator speed control by machine control, that is, correction of the motion command value according to the load acting on the actuator, is necessary.

[0053] <How to correct the operation command value> An example of correcting the movement command value is shown below. First, when the distance between the bucket 22 and the construction target surface is small, that is, when the bucket 22 is moving along the construction target surface, the actuator speed needs to be accurately controlled, so the movement command value is always corrected according to the actuator load, and the limit on the amount of correction is small. On the other hand, when the distance between the bucket 22 and the construction target surface is large, that is, when the bucket 22 is moving at a position far from the construction target surface, it is better for the operator to increase or decrease the actuator speed according to the actuator load, so the movement command value is not corrected and the limit on the amount of correction is large.

[0054] A method for limiting the amount of correction to the operation command value will be described with reference to Fig. 8. Fig. 8 is a diagram showing the relationship between the distance between the bucket 22 and the construction target surface and the correction gain. The correction gain is a weighting coefficient by which the correction amount is multiplied before being added to the operation command value.

[0055] When the bucket 22 approaches the construction target surface (when the required motion vector is moving in a direction toward the construction target surface), as shown in FIG. 8A, if the distance between the bucket 22 and the construction target surface is smaller than the set value D1a, the correction gain is 1, and the correction amount according to the cylinder load is added to the motion command value without any limitation. This makes it possible to operate the bucket 22 accurately along the construction target surface regardless of the magnitude of the actuator load. If the distance is equal to or greater than the second set value D2a, the correction gain is 0, and the motion command value is not corrected. This disables machine control, allowing the operator to operate the bucket 22 while keeping track of the load. If the distance is equal to or greater than the first set value D1a and smaller than the second set value D2a, the correction gain continuously changes from 1 to 0 as the distance increases. This continuously changes the degree of limitation on the correction amount according to the distance between the bucket 22 and the construction target surface, making it possible to reduce the sense of discomfort felt by the operator when switching between machine control and manual operation.

[0056] The correction gain when the bucket 22 moves away from the construction target surface (when the required movement vector is in a direction away from the construction target surface) is also determined according to the distance between the bucket 22 and the construction target surface, as shown in Fig. 8(B). However, the first set value D1b and the second set value D2b are set to values ​​smaller than the first set value D1a and the second set value D2a when the bucket 22 approaches the construction target surface (when the required movement vector is in a direction approaching the construction target surface).

[0057] Figure 9 is a diagram showing the corrected motion command value when the boom cylinder 20A is under a high load. When the bucket 22 approaches the construction target surface (when the required motion vector is in a direction approaching the construction target surface), as shown in Figure 9(A), when the actuator is under a low load, the motion command value is determined according to the motion characteristics at low load, as indicated by the thin solid line. On the other hand, when the actuator is under a high load, in the region where the distance between the bucket 22 and the construction target surface is smaller than the set value D1a, the motion command value is determined according to the motion characteristics at high load, as indicated by the thick solid line, and as the distance between the bucket 22 and the construction target surface increases, the motion command value approaches the motion command value determined according to the motion characteristics at low load.

[0058] When the bucket 22 moves away from the construction target surface (when the required movement vector is in a direction away from the construction target surface), as shown in Figure 9(B), when the actuator is under a low load, the movement command value is determined according to the movement characteristics at low load, as indicated by the thin solid line. On the other hand, when the actuator is under a high load, in the region where the distance between the bucket 22 and the construction target surface is smaller than the set value D1b, the movement command value is determined according to the movement characteristics at high load, as indicated by the thick solid line, and as the distance between the bucket 22 and the construction target surface increases, the movement command value approaches the movement command value based on the movement characteristics at low load. Here, because the set values ​​D1b and D2b are set to values ​​smaller than the set values ​​D1a and D2a, respectively, when the toe of the bucket moves away from the construction target surface, the movement command value at low load is output when the distance between the bucket 22 and the construction target surface is smaller than when the toe of the bucket approaches the construction target surface.

[0059] From the above, when the bucket toe approaches the construction target surface, the operating speed of actuators 20A, 21A, and 22A can be accurately controlled by reducing the degree of limitation on the amount of correction of the operation command value, and when the bucket toe moves away from the construction target surface, the operability can be improved by increasing the degree of limitation on the amount of correction of the operation command value.

[0060] <Method for estimating actuator load> A method for estimating the load acting on the actuator will be described using the boom cylinder 20A as an example. The load acting on the boom cylinder 20A can be calculated from the cylinder thrust required to support the weight Mg of the front work unit 2, as shown in Figure 10.

[0061] The thrust force FBm of the boom cylinder 20A can be found by solving, for example, the equation for balancing the moment about the origin (Equation 2) shown in FIG.

[0062]

number

[0063] L1: Distance between the origin and boom cylinder 20A θ1: Angle between the origin and the thrust FBm of the boom cylinder 20A M: Mass of the working front g:Gravity acceleration L2: Distance between the origin and the center of gravity of the front working surface 2 θ2: Angle between the origin and the center of gravity of work front 2 <Excavation trajectory after correcting the operation command value> When the load on the actuator is large, the excavation trajectory before the operation command value is corrected exhibits a large deviation between the requested speed and the actual speed of actuators 20A, 21A, and 22A, and therefore exhibits a large downward sinking relative to the construction target surface, as shown in Figure 11. On the other hand, the excavation trajectory after the operation command value is corrected taking the load on the actuator into consideration exhibits a small deviation between the requested speed and the actual speed of the actuator, and therefore exhibits a small downward sinking relative to the construction target surface.

[0064] <Control procedure> 12 is a flowchart showing the processing of the information processing device 34. Each step will be explained below in order.

[0065] In step S110, the attitudes of the front work unit 2 and the revolving unit 3 are calculated based on the angle information from the attitude detection device 30.

[0066] In step S120, the distance from the tip of the work front to the work target surface is calculated.

[0067] In step S130, the amount of operation input to the operation input device 33 is acquired.

[0068] In step S140, the target speeds of the actuators 20A, 21A, and 22A that drive the work front 2 are calculated based on the attitude of the work front 2 and the revolving body 3, the distance from the tip of the work front to the construction target surface, and the operation amount input to the operation input device 33.

[0069] In step S150, operation command values ​​are calculated based on the target speeds of actuators 20A, 21A, and 22A.

[0070] In step S160, based on the attitudes of the front work unit 2 and the revolving unit 3 and the load information obtained from the load detection device 27, the loads on the actuators 20A, 21A, and 22A are estimated.

[0071] In step S170, the amount of correction to the operation command value is calculated from the estimated loads on actuators 20A, 21A, and 22A.

[0072] In step S180, a required motion vector of the front end of the work front is estimated from the attitudes of the work front 2 and the revolving unit 3, the amount of operation input to the operation input device 33, and the position of the construction target surface.

[0073] In step S190, the correction amount of the operation command value is limited in accordance with the distance from the tip of the work front to the work target surface and the required operation vector.

[0074] In step S200, the operation command value calculated in step S150 is corrected by adding the post-limit correction amount to the operation command value, and is output to the driving device 35.

[0075] (summary) In this embodiment, the system includes a machine body 3, a work front 2 having a work implement 22 attached to the machine body 3 so as to be rotatable in the vertical direction, actuators 20A, 21A, and 22A that drive the work front 2, a drive unit 35 that drives the actuators 20A, 21A, and 22A, an operation input device 33 that instructs the operation of the actuators 20A, 21A, and 22A, a posture detection device 30 that detects the posture of the machine body 3 and the work front 2, a target surface information setting device 100 that sets a work target surface for the work implement 22, and a controller 34a that outputs operation command values ​​for the actuators 20A, 21A, and 22A to the drive unit 35 based on information input from the operation input device 33, the posture detection device 30, and the target surface information setting device 100 so that the work implement 22 is positioned along or above the work target surface. In a work machine (1) comprising the above, a load detection device (27) is provided that detects the load on the actuators (20A, 21A, 22A), and a controller (34a) calculates target speeds for the actuators (20A, 21A, 22A) based on the operation amount of the operation input device (33), the attitude, and the distance between the work implement (22) and the construction target surface, calculates operation command values ​​for the actuators (20A, 21A, 22A) based on the target speeds so as to operate the actuators (20A, 21A, 22A) at the target speeds, calculates a correction amount to be added to the operation command value based on the load on the actuators (20A, 21A, 22A detected by the load detection device (27), limits the correction amount based on the distance between the work implement (22) and the construction target surface and the direction of operation of the work implement (22) relative to the construction target surface, and adds the limited correction amount to the operation command value.

[0076] According to the present embodiment configured as described above, the operation command values ​​of the actuators 20A, 21A, and 22A are calculated so as to reduce the distance between the work tool 22 and the construction target surface, and a correction amount for the operation command value is calculated based on the load on the actuators 20A, 21A, and 22A, and the correction amount is added to the operation command value. This makes it possible to accurately operate the work tool 22 along the construction target surface near the construction target surface regardless of the magnitude of the load on the actuators 20A, 21A, and 22A, and when the work tool 22 is not near the construction target surface, the operator can perform operations while recognizing the load acting on the work front.

[0077] Furthermore, in this embodiment, the controller 34a increases the correction amount as the load on the actuators 20A, 21A, and 22A increases, thereby making it possible to keep constant the speed of the actuators 20A, 21A, and 22A relative to the operation amount of the operation input device 33, regardless of the load on the actuators 20A, 21A, and 22A.

[0078] Furthermore, in this embodiment, the controller 34a does not limit the correction amount when the distance is smaller than a first set value D1a (D1b), sets the correction amount to zero when the distance is equal to or greater than a second set value D2a (D2b) that is larger than the first set value D1a (D1b), and increases the degree of limitation on the correction amount as the distance increases when the distance is equal to or greater than the first set value D1a (D1b) and smaller than the second set value D2a (D2b). This continuously changes the degree of limitation on the correction amount according to the distance between the bucket 22 and the construction target surface, making it possible to reduce the sense of discomfort felt by the operator when switching between machine control and manual operation.

[0079] Furthermore, the controller 34a in this embodiment calculates a required movement vector of the front end of the work front machine based on the amount of operation, and sets the first set value D1b and the second set value D2b when the required movement vector is in a direction away from the construction target surface to values ​​that are smaller than the first set value D1a and the second set value D2a when the required movement vector is in a direction approaching the construction target surface. This allows machine control to be quickly released when the bucket 22 is operated in a direction away from the construction target surface, thereby improving the operability of the front work machine 2.

[0080] Furthermore, in this embodiment, when the distance is smaller than the second set value D2a (D2b), the controller 34a calculates the correction amount based on the load on the actuators 20A, 21A, 22A detected by the load detection device 27, and when the distance is equal to or greater than the second set value D2a (D2b), the controller 34a calculates the operation command value by assuming that the load on the actuators 20A, 21A, 22A is the load when the front work unit assumes a predetermined posture. This makes it possible to reduce the processing load on the controller 34a when the distance between the bucket 22 and the construction target surface is equal to or greater than the second set value D2a (D2b).

[0081] Furthermore, in this embodiment, the controller 34a calculates the correction amount based on the load of the actuators 20A, 21A, 22A detected by the load detection device 27 when the distance is smaller than the second set value D2a (D2b), and calculates the operation command value based on a preset relationship between the operation amount and the operation command value when the distance is equal to or larger than the second set value D2a (D2b). This makes it possible to improve the operability of the front work unit 2 when the distance between the bucket 22 and the construction target surface is equal to or larger than the second set value D2a (D2b).

[0082] Furthermore, the work machine 1 in this embodiment is equipped with a machine information setting device 120 that sets the center of gravity position and mass of the front work unit 2, and the controller 34a calculates the loads on the actuators 20A, 21A, 22A based on the attitude of the machine main body 3 and front work unit 2 detected by the attitude detection device 30 and the center of gravity position and mass of the front work unit 2 set by the machine information setting device 120. This makes it possible to omit the load detection device 27 that detects the loads on the actuators 20A, 21A, 22A.

[0083] Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above-described embodiments and includes various modifications. For example, the above-described embodiments have been described in detail to clearly explain the present invention, and the present invention is not necessarily limited to those having all of the described configurations. [Explanation of symbols]

[0084] 1...hydraulic excavator (work machine), 2...work front, 3...swinging body (machine body), 4...traveling body, 10...control system, 20...boom, 20A...boom cylinder (actuator), 20BP, 20RP...pressure sensor, 20S...boom IMU, 21...arm, 21A...arm cylinder (actuator), 21BP, 21RP...pressure sensor, 21S...arm IMU, 22...bucket (work tool), 22A...bucket cylinder (actuator), 22B...first link, 22BP...pressure sensor, 22C...second link, 22RP...pressure sensor, 22S...bucket IMU, 27...load detection device, 27a...pressure sensor, 30...attitude detection device, 30a...angular velocity sensor, 30b...acceleration sensor, 30S...swinging body IMU, 31...main frame, 32...operator's cab, 33...operation input device, 3 3a...operation lever, 33b...operation input amount sensor, 34...information processing device, 34a...information processing controller, 35...drive device, 35a...hydraulic pump, 35b...directional switching valve, 35c...electromagnetic control valve, 36...prime mover, 36a...engine, 37...counterweight, 38...swing motor, 40...track frame, 41...travel motor, 42...crawler, 100...target surface information setting device, 100a...target surface information setting controller, 110...image display device, 110a...display monitor, 120...machine information setting device, 120a...machine information setting controller, 310...target speed calculation unit, 320...motion command value calculation unit, 410...attitude calculation unit, 420...target surface distance calculation unit, 510...requested motion vector estimation unit, 520...load estimation unit, 610...motion command value correction amount calculation unit, 620...motion command value correction unit.

Claims

1. The machine body, a work front having a work tool attached to the machine body so as to be rotatable in the vertical direction; an actuator that drives the work front; a drive device that drives the actuator; an operation input device for instructing the operation of the actuator; a posture detection device for detecting the postures of the machine body and the front work unit; a target surface information setting device for setting a construction target surface of the work tool; a controller that outputs an operation command value of the actuator to the drive device based on information input from the operation input device, the attitude detection device, and the target surface information setting device so that the work tool is positioned along or above the construction target surface, a load detection device for detecting a load on the actuator; The controller calculating a target velocity of the actuator based on the operation amount of the operation input device, the attitude, and the distance between the work tool and the construction target surface; calculating an operation command value for the actuator based on the target speed; calculating a correction amount to be added to the operation command value based on the load of the actuator detected by the load detection device so that the actuator is operated at the target speed regardless of the magnitude of the load on the actuator; limiting the correction amount based on a distance between the work tool and the construction target surface and a movement direction of the work tool relative to the construction target surface; The limited correction amount is added to the operation command value. A work machine characterized by:

2. 2. The work machine according to claim 1, The controller increases the correction amount as the load on the actuator increases. A work machine characterized by:

3. 2. The work machine according to claim 1, The controller If the distance is smaller than a first set value, the correction amount is not limited, When the distance is equal to or greater than a second set value that is greater than the first set value, the correction amount is set to zero; When the distance is equal to or greater than the first set value and smaller than the second set value, the degree of limitation on the correction amount is increased as the distance increases. A work machine characterized by:

4. 4. The work machine according to claim 3, The controller calculating a required motion vector of the tip of the work front device based on the operation amount; The first set value and the second set value when the required motion vector is in a direction away from the construction target surface are set to values ​​smaller than the first set value and the second set value when the required motion vector is in a direction approaching the construction target surface. A work machine characterized by:

5. 4. The work machine according to claim 3, The controller If the distance is smaller than the second set value, the correction amount is calculated based on the load of the actuator detected by the load detection device; If the distance is equal to or greater than the second set value, the load on the actuator is assumed to be the load when the front work surface assumes a predetermined posture, and the operation command value is calculated. A work machine characterized by:

6. 4. The work machine according to claim 3, The controller If the distance is smaller than the second set value, the correction amount is calculated based on the load of the actuator detected by the load detection device; If the distance is equal to or greater than the second set value, the operation command value is calculated based on a preset relationship between the operation amount and the operation command value. A work machine characterized by:

7. 2. The work machine according to claim 1, a machine information setting device for setting the center of gravity position and mass of the front work mechanism; The controller calculates the load of the actuator based on the postures of the machine body and the work front detected by the posture detection device and the center of gravity position and mass of the work front set by the machine information setting device. A work machine characterized by:

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