US20200217050A1 - Work machine - Google Patents

Work machine Download PDF

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Publication number
US20200217050A1
US20200217050A1 US16/328,895 US201716328895A US2020217050A1 US 20200217050 A1 US20200217050 A1 US 20200217050A1 US 201716328895 A US201716328895 A US 201716328895A US 2020217050 A1 US2020217050 A1 US 2020217050A1
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United States
Prior art keywords
target surface
bucket
excavation
current landform
section
Prior art date
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Abandoned
Application number
US16/328,895
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English (en)
Inventor
Takaaki CHIBA
Hisami NAKANO
Hiroaki Tanaka
Manabu Edamura
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Hitachi Construction Machinery Co Ltd
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Hitachi Construction Machinery Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Hitachi Construction Machinery Co Ltd filed Critical Hitachi Construction Machinery Co Ltd
Assigned to HITACHI CONSTRUCTION MACHINERY CO., LTD. reassignment HITACHI CONSTRUCTION MACHINERY CO., LTD. ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: CHIBA, Takaaki, EDAMURA, MANABU, NAKANO, HISAMI, TANAKA, HIROAKI
Publication of US20200217050A1 publication Critical patent/US20200217050A1/en
Abandoned legal-status Critical Current

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    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02F—DREDGING; SOIL-SHIFTING
    • E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
    • E02F9/26—Indicating devices
    • E02F9/264—Sensors and their calibration for indicating the position of the work tool
    • E02F9/265—Sensors and their calibration for indicating the position of the work tool with follow-up actions (e.g. control signals sent to actuate the work tool)
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02F—DREDGING; SOIL-SHIFTING
    • E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
    • E02F9/20—Drives; Control devices
    • E02F9/2025—Particular purposes of control systems not otherwise provided for
    • E02F9/2033—Limiting the movement of frames or implements, e.g. to avoid collision between implements and the cabin
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02F—DREDGING; SOIL-SHIFTING
    • E02F3/00—Dredgers; Soil-shifting machines
    • E02F3/04—Dredgers; Soil-shifting machines mechanically-driven
    • E02F3/28—Dredgers; Soil-shifting machines mechanically-driven with digging tools mounted on a dipper- or bucket-arm, i.e. there is either one arm or a pair of arms, e.g. dippers, buckets
    • E02F3/30—Dredgers; Soil-shifting machines mechanically-driven with digging tools mounted on a dipper- or bucket-arm, i.e. there is either one arm or a pair of arms, e.g. dippers, buckets with a dipper-arm pivoted on a cantilever beam, i.e. boom
    • E02F3/32—Dredgers; Soil-shifting machines mechanically-driven with digging tools mounted on a dipper- or bucket-arm, i.e. there is either one arm or a pair of arms, e.g. dippers, buckets with a dipper-arm pivoted on a cantilever beam, i.e. boom working downwardly and towards the machine, e.g. with backhoes
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02F—DREDGING; SOIL-SHIFTING
    • E02F3/00—Dredgers; Soil-shifting machines
    • E02F3/04—Dredgers; Soil-shifting machines mechanically-driven
    • E02F3/28—Dredgers; Soil-shifting machines mechanically-driven with digging tools mounted on a dipper- or bucket-arm, i.e. there is either one arm or a pair of arms, e.g. dippers, buckets
    • E02F3/36—Component parts
    • E02F3/42—Drives for dippers, buckets, dipper-arms or bucket-arms
    • E02F3/43—Control of dipper or bucket position; Control of sequence of drive operations
    • E02F3/435—Control of dipper or bucket position; Control of sequence of drive operations for dipper-arms, backhoes or the like
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02F—DREDGING; SOIL-SHIFTING
    • E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
    • E02F9/20—Drives; Control devices
    • E02F9/22—Hydraulic or pneumatic drives
    • E02F9/2203—Arrangements for controlling the attitude of actuators, e.g. speed, floating function
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02F—DREDGING; SOIL-SHIFTING
    • E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
    • E02F9/20—Drives; Control devices
    • E02F9/22—Hydraulic or pneumatic drives
    • E02F9/2264—Arrangements or adaptations of elements for hydraulic drives
    • E02F9/2271—Actuators and supports therefor and protection therefor
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02F—DREDGING; SOIL-SHIFTING
    • E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
    • E02F9/26—Indicating devices
    • E02F9/261—Surveying the work-site to be treated
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02F—DREDGING; SOIL-SHIFTING
    • E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
    • E02F9/26—Indicating devices
    • E02F9/261—Surveying the work-site to be treated
    • E02F9/262—Surveying the work-site to be treated with follow-up actions to control the work tool, e.g. controller

Definitions

  • the present invention relates to a work machine capable of performing machine control.
  • a hydraulic excavator may be provided with a control system assisting an excavation operation performed by an operator.
  • a control system performs control to force at least one of a boom cylinder, an arm cylinder, and a bucket cylinder that drive a work machine to operate (e.g., to extend the boom cylinder to thereby forcibly perform a boom raising operation) such that, on the basis of a positional relation between a target surface and a distal end (e.g., bucket claw tip) of the work machine, the distal end of the work machine (to be referred to also as a front work implement) is held at a position on the target surface or within an area superior to the target surface.
  • Limiting the area through which the distal end of the work machine can move as described above facilitates work to finish an excavation surface or work to form a slope face.
  • Patent Document 1 discloses a type of control, in which a target speed vector of a bucket distal end is calculated using a signal from an operation device (operation lever) and the boom cylinder is controlled such that a vector component having a direction approaching the target surface in the target speed vector decreases at distances closer to the target surface to thereby hold a front work implement within a deceleration area (set area) set superior to the target surface (a boundary of the set area).
  • Such a type of control may be referred in the following to as “machine control (MC),” “area limiting control,” or “intervention control (with respect to an operator operation).”
  • Patent Document 2 discloses a work assist system for a work machine that includes a controller and a display device.
  • the work assist system operates as follows. Specifically, in a situation in which excavation is performed according to what is called a bench cut method, the excavation amount (estimated excavation amount) to be housed in a bucket per one excavation operation by the work implement is set and an area from which the estimated excavation amount can be obtained from an excavation object by one excavation operation is established as an excavation area S.
  • the controller uses the excavation area S to calculate a work position Pw of the work machine when the work machine performs the next excavation operation.
  • the display device displays information on the work position of the work machine calculated by the controller.
  • the technique disclosed in Patent Document 2 aims, by displaying the next work position in the display device, at maintaining the excavation amount for each excavation operation even when a height (bench height) H of the excavation object on which the work machine is placed varies.
  • Patent Document 1 W01995/030059
  • Patent Document 2 JP-2017-14726-A
  • Patent Document 2 establishes the excavation area S on the basis of a cross-sectional area sb and a bench height H of the excavation area S from which the excavation object is to be excavated in the next excavation operation.
  • the technique calculates the work position Pw on the assumption that the bench height H is a predetermined value.
  • the excavation amount falls short of the estimated excavation amount (target excavation amount) even when the work machine is located at the work position Pw calculated by the controller. This can result in reduced work efficiency.
  • Patent Document 2 assumes excavation by the bench cut method, the same can be pointed out for a case in which, as in Patent Document 1, the target surface (flat surface) is generated through the excavation operation.
  • a method is possible in which an excavation start point and an excavation end point are established in advance in a fore-aft direction of the front work implement to thereby set a distance over which the bucket moves in one excavation operation (excavation distance).
  • a target surface is then set at a predetermined depth as measured from a current landform (excavation depth) such that the single excavation operation can excavate a targeted excavation amount (target excavation amount (which corresponds to the estimated excavation amount in Patent Document 1)) and the excavation is performed toward the target surface.
  • target excavation amount which corresponds to the estimated excavation amount in Patent Document 1
  • the resultant excavation amount may be more or less than the target excavation amount.
  • An object of the present invention is to provide a work machine that, while reducing a load on an operator during excavation work for generating a target surface, can prevent an excavation amount from being more or less than a target excavation amount (limit volume) regardless of an excavation distance.
  • one aspect of the present application provides a work machine that includes: a work implement having a bucket, an arm, and a boom; a plurality of hydraulic actuators that drive the work implement; operation devices that instruct the hydraulic actuators on operations; and a controller that controls the hydraulic actuators such that, during operations of the operation devices, an operating range of the work implement is limited on a predetermined first target surface and to an area superior to the first target surface.
  • the controller includes: a storage section that stores position information of a current landform; a bucket position calculation section that calculates a position of a claw tip of the bucket; an estimated excavation volume calculation section that calculates an estimated excavation volume defined by a first position that assumes the position of the claw tip of the bucket calculated by the bucket position calculation section at an excavation start, a second position that assumes the position of the claw tip of the bucket at an excavation end set in advance, the current landform, the first target surface, and a width of the bucket; and a target surface generation section that generates, when the estimated excavation volume exceeds a limit volume set in advance, a second target surface at a position superior to the first target surface.
  • the target surface generation section generates the second target surface at a position at which the excavation volume defined by the first position, the second position, the current landform, the second target surface, and the width of the bucket is closer to the limit volume.
  • the controller controls the hydraulic actuators such that the operating range of the work implement is limited on the second target surface and to an area superior to the second target surface.
  • the target surface is set such that the target excavation amount is maintained even with the excavation distance varying for each excavation sequence.
  • the excavation amount can thus be prevented from being more or less than the target excavation amount (limit volume), so that efficiency in excavation work can be enhanced.
  • FIG. 1 is a configuration diagram of a hydraulic excavator.
  • FIG. 2 is a diagram of a controller for the hydraulic excavator and a hydraulic drive system.
  • FIG. 3 is a diagram detailing a front control hydraulic unit 160 illustrated in FIG. 2 .
  • FIG. 4 is a diagram of a coordinate system in the hydraulic excavator illustrated in FIG. 1 and a target surface (first target surface).
  • FIG. 5 is a hardware configuration diagram of a controller 40 for the hydraulic excavator.
  • FIG. 6 is a functional block diagram of the controller 40 for the hydraulic excavator.
  • FIG. 7 is a functional block diagram of an MG/MC control section 43 illustrated in FIG. 6 .
  • FIG. 8 is a side elevation view of a relation among a current landform 800 , a target surface (first target surface) 700 , and a hydraulic excavator 1 .
  • FIG. 9 is a side elevation view of a relation among a correction amount d, the first target surface 700 , a second target surface 700 A, and the hydraulic excavator 1 .
  • FIG. 10 is a diagram of a positional relation between a bucket claw tip P 4 and the target surfaces 700 and 700 A.
  • FIG. 11 is a graph illustrating a relation between a target surface distance D and a speed correction factor k.
  • FIG. 12 is a diagram of a speed vector V 0 at a bucket distal end.
  • FIG. 13 is a flowchart for setting a target surface by the MG/MC control section 43 .
  • FIG. 14 is a flowchart for MC by the MG/MC control section 43 .
  • FIG. 15 is a diagram of an example of a configuration diagram of a display device 53 a.
  • FIG. 16 is a functional block diagram of an MG/MC control section 43 A according to another embodiment.
  • FIG. 17 is a schematic diagram illustrating updating of a current landform performed by a current landform updating section 43 aa on the basis of position information of the bucket claw tip.
  • FIG. 18 is a schematic diagram illustrating a method for generating the second target surface 700 A when the first target surface 700 is inclined with respect to an excavator coordinate.
  • FIG. 19 is a schematic diagram illustrating a method for generating the second target surface 700 A when the first target surface 700 is formed of a plurality of surfaces having different inclinations from each other.
  • Embodiments of the present invention will be described below with reference to the accompanying drawings.
  • the following embodiments exemplify a hydraulic excavator having a bucket 10 as an attachment fitted at the distal end of a work implement.
  • the present invention may nonetheless be applied to a work machine having any other attachment than the bucket.
  • the present invention may be applied to any type of work machine other than the hydraulic excavator when the work machine includes an articulated work implement consisting of a plurality of link members (an attachment, an arm, a boom, and the like) connected with each other.
  • phrases used with terms denoting shapes such as “on,” “superior to,” and “inferior to,” mean as detailed below, specifically, “on” denotes a “surface” of the shape, “superior to” denotes a “position superior to, or above, the surface” of the shape, and “inferior to” denotes a “position inferior to, or below, the surface” of the shape.
  • an alphabet may be added at the end of a reference character (numeral) to differentiate one from the other. The alphabet may nonetheless be omitted, and the elements of the same kind may be denoted collectively.
  • three pumps 300 a , 300 b , and 300 c may be collectively denoted as a pump 300 .
  • FIG. 1 is a configuration diagram of a hydraulic excavator according to an embodiment of the present invention.
  • FIG. 2 is a diagram of a controller for the hydraulic excavator according to the embodiment and a hydraulic drive system.
  • FIG. 3 is a diagram detailing a front control hydraulic unit 160 illustrated in FIG. 2 .
  • This hydraulic excavator 1 includes an articulated front work implement 1 A and a machine body 1 B.
  • the machine body 1 B includes a lower track structure 11 and an upper swing structure 12 .
  • the lower track structure 11 travels as driven by left and right track hydraulic motors 3 a and 3 b (see FIG. 2 for the hydraulic motor 3 a ).
  • the upper swing structure 12 is mounted on the lower track structure 11 and swung by a swing hydraulic motor 4 .
  • the front work implement 1 A includes a plurality of driven members (a boom 8 , an arm 9 , and a bucket 10 ) that are coupled with each other.
  • the driven members each rotate in a vertical direction.
  • the boom 8 has a proximal end rotatably supported via a boom pin at a front portion of the upper swing structure 12 .
  • the arm 9 is rotatably coupled with a distal end of the boom 8 via an arm pin.
  • the bucket 10 is rotatably coupled with a distal end of the arm 9 via a bucket pin.
  • the boom 8 is driven by a boom cylinder 5 .
  • the arm 9 is driven by an arm cylinder 6 .
  • the bucket 10 is driven by a bucket cylinder 7 .
  • a boom angle sensor 30 is mounted on the boom pin.
  • An arm angle sensor 31 is mounted on the arm pin.
  • a bucket angle sensor 32 is mounted on a bucket link 13 .
  • the boom angle sensor 30 , the arm angle sensor 31 , and the bucket angle sensor 32 measure rotation angles ⁇ , ⁇ , and ⁇ (see FIG. 5 ) of the boom 8 , the arm 9 , and the bucket 10 , respectively.
  • a machine body inclination angle sensor 33 is mounted on the upper swing structure 12 .
  • the machine body inclination angle sensor 33 detects an inclination angle ⁇ (see FIG. 5 ) of the upper swing structure 12 (machine body 1 B) with respect to a reference plane (e.g., a horizontal plane).
  • a reference plane e.g., a horizontal plane
  • An operation device 47 a ( FIG. 2 ), an operation device 47 b ( FIG. 2 ), operation devices 45 a and 46 a ( FIG. 2 ), and operation devices 45 b and 46 b ( FIG. 2 ) are mounted in a cab 16 disposed in the upper swing structure 12 .
  • the operation device 47 a includes a right track lever 23 a ( FIG. 2 ) and operates the right track hydraulic motor 3 a (lower track structure 11 ).
  • the operation device 47 b includes a left track lever 23 b ( FIG. 2 ) and operates the left track hydraulic motor 3 b (lower track structure 11 ).
  • the operation devices 45 a and 46 a share a right operation lever 1 a ( FIG.
  • the operation devices 45 b and 46 b share a left operation lever 1 b ( FIG. 2 ) and operate the arm cylinder 6 (arm 9 ) and the swing hydraulic motor 4 (upper swing structure 12 ).
  • the right track lever 23 a , the left track lever 23 b , the right operation lever 1 a , and the left operation lever 1 b may be collectively referred to as operation levers 1 and 23 .
  • An engine 18 as a prime mover mounted on the upper swing structure 12 drives a hydraulic pump 2 and a pilot pump 48 .
  • the hydraulic pump 2 is a variable displacement pump having displacement controlled by a regulator 2 a .
  • the pilot pump 48 is a fixed displacement pump.
  • a shuttle block 162 is disposed midway in pilot lines 144 , 145 , 146 , 147 , 148 , and 149 , as illustrated in FIG. 2 . Hydraulic signals output from operation devices 45 , 46 , and 47 are applied also to the regulator 2 a via the shuttle block 162 . While a detailed configuration of the shuttle block 162 is omitted, briefly, the hydraulic signal is applied to the regulator 2 a via the shuttle block 162 and a delivery flow rate of the hydraulic pump 2 is controlled according to the hydraulic signal.
  • a pump line 170 as a delivery line of the pilot pump 48 is branched after a lock valve 39 to be connected with respective valves in the operation devices 45 , 46 , and 47 and the front control hydraulic unit 160 .
  • the lock valve 39 in the embodiment is a solenoid-operated changeover valve having a solenoid drive section electrically connected with a position sensor of a gate lock lever (not illustrated) disposed in the cab 16 of the upper swing structure 12 .
  • the position sensor detects a position of the gate lock lever and applies a signal corresponding to the position of the gate lock lever to the lock valve 39 .
  • the lock valve 39 closes to interrupt the pump line 170 .
  • the lock valve 39 opens to establish communication of the pump line 170 . Specifically, when the pump line 170 is interrupted, an operation by the operation devices 45 , 46 , and 47 is disabled and swing, excavation, and other operations are prohibited.
  • the operation devices 45 , 46 , and 47 are each a hydraulic pilot type operation device. On the basis of hydraulic fluid delivered from the pilot pump 48 , each of the operation devices 45 , 46 , and 47 generates a pilot pressure (may be referred to also as an operation pressure) corresponding to an operation amount (e.g., lever stroke) and an operating direction of the operation levers 1 and 23 operated by an operator.
  • the pilot pressures thus generated are supplied via pilot lines 144 a to 149 b (see FIG. 3 ) to respective hydraulic drive sections 150 a to 155 b of flow control valves 15 a to 15 f (see FIG. 2 or 3 ) associated with respective control valve units (not illustrated) and used as control signals that drive the flow control valves 15 a to 15 f.
  • the hydraulic fluid delivered from the hydraulic pump 2 is supplied via the flow control valves 15 a , 15 b , 15 c , 15 d , 15 e , and 15 f (see FIG. 3 ) to the right track hydraulic motor 3 a , the left track hydraulic motor 3 b , the swing hydraulic motor 4 , the boom cylinder 5 , the arm cylinder 6 , and the bucket cylinder 7 .
  • the boom cylinder 5 , the arm cylinder 6 , and the bucket cylinder 7 are extended or contracted by the hydraulic fluid thus supplied, so that the boom 8 , the arm 9 , and the bucket 10 are rotated, and the position and posture of the bucket 10 vary.
  • the hydraulic fluid thus supplied rotates the swing hydraulic motor 4 , to thereby swing the upper swing structure 12 relative to the lower track structure 11 .
  • the hydraulic fluid thus supplied rotates the right track hydraulic motor 3 a and the left track hydraulic motor 3 b to thereby cause the lower track structure 11 to travel.
  • a posture of the work implement 1 A can be defined on the basis of an excavator coordinate system (local coordinate system) illustrated in FIG. 4 .
  • the excavator coordinate system illustrated in FIG. 4 is set on the upper swing structure 12 .
  • a base portion of the boom 8 is defined as an origin PO, and in the upper swing structure 12 , a Z-axis is set in a vertical direction and an X-axis is set in a horizontal direction. Additionally, a Y-axis is defined in a direction specified by the X-axis and the Z-axis in a right-handed system.
  • An inclination angle of the boom 8 with respect to the X-axis is defined as a boom angle ⁇ .
  • An inclination angle of the arm 9 with respect to the boom is defined as an arm angle ⁇ .
  • An inclination angle of the bucket claw tip with respect to the arm is defined as a bucket angle ⁇ .
  • An inclination angle of the machine body 1 B (upper swing structure 12 ) with respect to a horizontal plane (reference plane) is defined as an inclination angle ⁇ .
  • the boom angle ⁇ is detected by the boom angle sensor 30 .
  • the arm angle ⁇ is detected by the arm angle sensor 31 .
  • the bucket angle ⁇ is detected by the bucket angle sensor 32 .
  • the inclination angle ⁇ is detected by the machine body inclination angle sensor 33 .
  • the boom angle ⁇ is a minimum when the boom 8 is raised to a maximum (the boom cylinder 5 is at a stroke end in a raising direction, specifically, a boom cylinder length is the longest), and is a maximum when the boom 8 is lowered to a minimum (the boom cylinder 5 is at a stroke end in a lowering direction, specifically, the boom cylinder length is shortest).
  • the arm angle ⁇ is a minimum when an arm cylinder length is the shortest and a maximum when the arm cylinder length is the longest.
  • the bucket angle ⁇ is a minimum when a bucket cylinder length is the shortest (the condition illustrated in FIG. 4 ) and a maximum when the bucket cylinder length is the longest.
  • L 1 denote a length between the base portion of the boom 8 and a connection of the boom 8 with the arm 9
  • L 2 denote a length between the connection of the arm 9 with the boom 8 and a connection of the arm 9 with the bucket 10
  • L 3 denote a length between the connection of the arm 9 with the bucket 10 and a distal end portion of the bucket 10 .
  • the position of the distal end of the bucket 10 in the excavator coordinate system may be given by expressions (1) and (2) given below, where X bk is the position in an X-direction and Z bk is the position in a Z-direction.
  • the hydraulic excavator 1 includes a pair of global navigation satellite system (GNSS) antennas 14 A and 14 B disposed on the upper swing structure 12 .
  • GNSS global navigation satellite system
  • the position of the hydraulic excavator 1 and the position of the bucket 10 in a global coordinate system can be calculated on the basis of information from the GNSS antenna 14 .
  • FIG. 5 is a configuration diagram of a machine guidance (MG) and machine control (MC) system included in the hydraulic excavator according to the embodiment.
  • MG machine guidance
  • MC machine control
  • control is performed to operate the work implement 1 A in accordance with a predetermined condition when the operation devices 45 a , 45 b , and 46 a are operated and the work implement 1 A is located in a deceleration area (first area) 600 , which represents a predetermined closed area set superior to an arbitrarily set target surface 700 (see FIG. 4 ).
  • At least one of the hydraulic actuators 5 , 6 , and 7 is controlled such that, in the deceleration area 600 , a vector component having a direction approaching the target surface 700 in a speed vector at a distal end portion (e.g., the claw tip of the bucket 10 ) of the work implement 1 A decreases at distances of the distal end portion of the work implement 1 A closer to the target surface 700 (details will be given later).
  • the hydraulic actuator 5 , 6 , or 7 is controlled by forcibly outputting a control signal (e.g., extend the boom cylinder 5 to thereby forcibly perform a boom raising operation) to a corresponding one of the flow control valves 15 a , 15 b , and 15 c .
  • This MC prevents the claw tip of the bucket 10 from entering a zone inferior to the target surface 700 , so that excavation in line with the target surface 700 can be performed regardless of the level of expertise of the operator.
  • the MC is not performed when the work implement 1 A is located in a non-deceleration area (second area) 620 set superior to the deceleration area 600 and adjacent to the deceleration area 600 , and the work implement 1 A operates as operated by the operator.
  • the dotted line 650 denotes a boundary between the deceleration area 600 and the non-deceleration area 620 .
  • a control point of the front work implement 1 A during MC is set at the claw tip of the bucket 10 (distal end of the work implement 1 A) of the hydraulic excavator.
  • the control point may, however, be changed to any point other than the bucket claw tip as long as the point falls within the distal end portion of the work implement 1 A.
  • a bottom surface of the bucket 10 or an outermost portion of the bucket link 13 may also be selected.
  • a point on the bucket 10 at a distance closest from the target surface 700 may be configured as the control point as appropriate.
  • the MC may be referred to as “semi-automatic control” in which the operation of the work implement 1 A is controlled by a controller 40 only when the operation devices 45 and 46 are operated, as against “automatic control” in which the operation of the work implement 1 A is controlled by the controller 40 when the operation devices 45 and 46 are not operated.
  • processing is performed, in which a positional relation between the target surface 700 and the work implement 1 A (e.g., bucket 10 ) is displayed on a display device 53 a as illustrated in FIG. 15 , for example.
  • the work implement 1 A e.g., bucket 10
  • the system illustrated in FIG. 5 includes a work implement posture sensor 50 , a target surface setting device 51 , an operator operation sensor 52 a , the display device 53 a , a current landform acquisition device 96 , and the controller 40 .
  • the display device 53 a is disposed in the cab 16 and can display the positional relation between the target surface 700 and the work implement 1 A.
  • the current landform acquisition device 96 acquires position information of a current landform 800 which the work implement 1 A is to work on.
  • the controller 40 controls MG and MC.
  • the work implement posture sensor 50 is formed to include the boom angle sensor 30 , the arm angle sensor 31 , the bucket angle sensor 32 , and the machine body inclination angle sensor 33 . These angle sensors 30 , 31 , 32 , and 33 function as posture sensors of the work implement 1 A.
  • the target surface setting device 51 is an interface through which information on the target surface 700 (including position information and inclination angle information on each target surface) can be input.
  • the target surface setting device 51 is connected with an external terminal (not illustrated) that stores three-dimensional data of the target surface defined on the global coordinate system (absolute coordinate system). The input of the target surface via the target surface setting device 51 may be made manually by the operator.
  • the operator operation sensor 52 a is formed to include pressure sensors 70 a , 70 b , 71 a , 71 b , 72 a , and 72 b .
  • the pressure sensors 70 a , 70 b , 71 a , 71 b , 72 a , and 72 b acquire operation pressures (first control signals) developing in the pilot lines 144 , 145 , and 146 as a result of the operator's operating the operation levers 1 a and 1 b (operation devices 45 a , 45 b , and 46 a ).
  • the pressure sensors 70 a , 70 b , 71 a , 71 b , 72 a , and 72 b detect operations on the hydraulic cylinders 5 , 6 , and 7 relating to the work implement 1 A.
  • a stereo camera, a laser scanner, or an ultrasonic sensor, for example, provided in the excavator 1 may be used as the current landform acquisition device 96 . These devices measure a distance between the excavator 1 and a point on the current landform.
  • the current landform acquired by the current landform acquisition device 96 is defined by an enormous amount of point group position data.
  • the current landform acquisition device 96 may be configured as an interface such that three-dimensional data of the current landform is acquired in advance by, for example, a drone in which a stereo camera, a laser scanner, an ultrasonic sensor, or the like is mounted, for loading the three-dimensional data in the controller 40 .
  • the front control hydraulic unit 160 includes the pressure sensors 70 a and 70 b , a solenoid proportional valve 54 a , a shuttle valve 82 a , and a solenoid proportional valve 54 b , disposed in the pilot lines 144 a and 144 b of the operation device 45 a for the boom 8 .
  • the pressure sensors 70 a and 70 b detect the pilot pressures (first control signals) as operation amounts of the operation lever 1 a .
  • the solenoid proportional valve 54 a has a primary port side connected with the pilot pump 48 via the pump line 170 and reduces and outputs the pilot pressure from the pilot pump 48 .
  • the shuttle valve 82 a is connected with the pilot line 144 a of the operation device 45 a for the boom 8 and a secondary port side of the solenoid proportional valve 54 a .
  • the shuttle valve 82 a selects a high-pressure side of the pilot pressure in the pilot line 144 a and a control pressure (second control signal) output from the solenoid proportional valve 54 a and guides the high-pressure side to the hydraulic drive section 150 a of the flow control valve 15 a .
  • the solenoid proportional valve 54 b is disposed in the pilot line 144 b of the operation device 45 a for the boom 8 and reduces and outputs the pilot pressure (first control signal) in the pilot line 144 b on the basis of a control signal from the controller 40 .
  • the front control hydraulic unit 160 further includes the pressure sensors 71 a and 71 b , a solenoid proportional valve 55 b , and a solenoid proportional valve 55 a , disposed in the pilot lines 145 a and 145 b for the arm 9 .
  • the pressure sensors 71 a and 71 b detect the pilot pressures (first control signals) as operation amounts of the operation lever 1 b and output the pilot pressures to the controller 40 .
  • the solenoid proportional valve 55 b is disposed in the pilot line 145 b and reduces and outputs the pilot pressure (first control signal) on the basis of the control signal from the controller 40 .
  • the solenoid proportional valve 55 a is disposed in the pilot line 145 a and reduces and outputs the pilot pressure (first control signal) in the pilot line 145 a on the basis of the control signal from the controller 40 .
  • the front control hydraulic unit 160 further includes the pressure sensors 72 a and 72 b , solenoid proportional valves 56 a and 56 b , solenoid proportional valves 56 c and 56 d , and shuttle valves 83 a and 83 b , disposed in the pilot lines 146 a and 146 b for the bucket 10 .
  • the pressure sensors 72 a and 72 b detect the pilot pressures (first control signals) as operation amounts of the operation lever 1 a and output the pilot pressures to the controller 40 .
  • the solenoid proportional valves 56 a and 56 b reduce and output the pilot pressures (first control signals) on the basis of a control signal from the controller 40 .
  • the solenoid proportional valves 56 c and 56 d each have a primary port side connected with the pilot pump 48 and each reduce and output the pilot pressure from the pilot pump 48 .
  • the shuttle valves 83 a and 83 b select a high-pressure side of the pilot pressures in the pilot lines 146 a and 146 b and control pressures output from the solenoid proportional valves 56 c and 56 d and guide the high-pressure side to the hydraulic drive sections 152 a and 152 b of the flow control valve 15 c . It is noted that FIG. 3 omits illustrating connection lines between the pressure sensors 70 , 71 , and 72 and the controller 40 for want of space.
  • the solenoid proportional valves 54 b , 55 a , 55 b , 56 a , and 56 b each open at a maximum angle when not energized and reduce an opening degree with an increasing value of current as the control signal from the controller 40 .
  • the solenoid proportional valves 54 a , 56 c , and 56 d reduce the opening degree to zero when not energized and each start opening when energized to increase the opening degree with an increasing value of current (control signal) from the controller 40 .
  • the solenoid proportional valves 54 , 55 , and 56 each have an opening degree corresponding to the control signal from the controller 40 .
  • control hydraulic unit 160 configured as described above, driving the solenoid proportional valve 54 a , 56 c , or 56 d by outputting the control signal from the controller 40 allows the pilot pressure (second control signal) to be generated even without an operation performed by the operator on the corresponding operation device 45 a or 46 a , so that a boom raising operation, a bucket crowding operation, or a bucket dumping operation can be forcibly generated.
  • the pilot pressures generated through operations on the operation devices 45 a , 45 b , and 46 a are referred to as the “first control signals.”
  • the pilot pressures generated through correction (reduction) of the first control signals made through driving of the solenoid proportional valves 54 b , 55 a , 55 b , 56 a , and 56 b with the controller 40 and the pilot pressures generated differently from the first control signals through driving of the solenoid proportional valves 54 a , 56 c , and 56 d with the controller 40 are referred to as the “second control signals.”
  • the second control signal is generated when the speed vector of a control point of the work implement 1 A generated by the first control signal contradicts a predetermined condition.
  • the second control signal is generated as a control signal that generates a speed vector of the control point of the work implement 1 A not contradicting the predetermined condition.
  • the flow control valves 15 a to 15 c one for which the second control signal is calculated is controlled on the basis of the second control signal, one for which the second control signal is not calculated is controlled on the basis of the first control signal, and one for which neither the first nor the second control signal is generated is not controlled (driven).
  • the above definitions of the first control signal and the second control signal result in the MC being referred to also as control of the flow control valves 15 a to 15 c on the basis of the second control signal.
  • the controller 40 includes an input interface 91 , a central processing unit (CPU) 92 as a processor, a read only memory (ROM) 93 and a random access memory (RAM) 94 as storage devices, and an output interface 95 .
  • Signals from the angle sensors 30 to 32 and the inclination angle sensor 33 which serve as the work implement posture sensor 50 , a signal from the target surface setting device 51 , which serves as a device for setting the target surface 700 , and a signal from the current landform acquisition device 96 , which acquires the current landform 800 , are applied to the input interface 91 .
  • the CPU 92 performs conversion to enable calculation.
  • the ROM 93 is a recording medium that stores a control program for performing MC and MG including processing relating to flowcharts to be described later and various types of information required for performing steps of the flowcharts.
  • the CPU 92 performs predetermined computational processing for signals fetched from the input interface 91 , the ROM 93 , and the RAM 94 in accordance with the control program stored in the ROM 93 .
  • the output interface 95 generates an output signal in accordance with results of calculations performed by the CPU 92 and outputs the signal to the display device 53 a to thereby activate the display device 53 a.
  • controller 40 illustrated in FIG. 5 includes semiconductor memories of the ROM 93 and the RAM 94 as the storage devices, any other type of storage device maybe substitutable.
  • the controller 40 may include a magnetic storage device, such as a hard disk drive.
  • FIG. 6 is a functional block diagram of the controller 40 .
  • the controller 40 includes an MG/MC control section 43 , a solenoid proportional valve control section 44 , and a display control section 374 a.
  • the MG/MC control section 43 When the operation devices 45 a , 45 b , and 46 a are operated, the MG/MC control section 43 performs MC for at least one of the hydraulic actuators 5 , 6 , and 7 in accordance with a predetermined condition.
  • the MG/MC control section 43 in the present embodiment performs MC that controls an operation of at least either one of the boom cylinder 5 (boom 8 ) and the arm cylinder 6 (arm 9 ) such that the claw tip (control point) of the bucket 10 is located on the target surface 700 or a position superior to the target surface 700 , on the basis of a position of the target surface 700 , a posture of the front work implement 1 A and a position of the claw tip of the bucket 10 , and the operation amounts of the operation devices 45 a , 45 b , and 46 a .
  • the MG/MC control section 43 calculates target pilot pressures of the flow control valves 15 a , 15 b , and 15 c of the respective hydraulic cylinders 5 , 6 , and 7 and outputs the calculated target pilot pressures to the solenoid proportional valve control section 44 .
  • FIG. 7 is a functional block diagram of the MG/MC control section 43 illustrated in FIG. 6 .
  • the MG/MC control section 43 includes a current landform updating section 43 a , a current landform storage section 43 b , a target surface storage section 43 c , a bucket position calculation section 43 d , a target speed calculation section 43 e , an estimated excavation volume calculation section 43 f , a target surface generation section 43 g , a distance calculation section 43 h , a correction speed calculation section 43 i , and a target pilot pressure calculation section 43 j.
  • the current landform storage section 43 b stores position information of the current landform around the hydraulic excavator (current landform data).
  • the current landform data represents, for example, a point group having three-dimensional coordinate data acquired by the current landform acquisition device 96 at appropriate timing in the global coordinate system.
  • the current landform updating section 43 a updates, when an estimated excavation volume Va (to be described later) is calculated by the estimated excavation volume calculation section 43 f , the position information of the current landform stored in the current landform storage section 43 b using position information of the current landform 800 , which is acquired by the current landform acquisition device 96 .
  • the target surface storage section 43 c stores position information (target surface data) of the target surface (first target surface) 700 , which is calculated using information from the target surface setting device 51 .
  • position information target surface data
  • FIG. 4 a cross-sectional shape cut by a plane (operating plane of the work implement) that represents a three-dimensional target surface over which the work implement 1 A travels is used as the target surface 700 (two-dimensional target surface).
  • FIG. 4 illustrates one target surface 700
  • possible methods for setting the target surface include: setting a surface closest to the work implement 1 A as the target surface; setting a surface disposed inferior to the bucket claw tip as the target surface; and selecting any surface as the target surface.
  • the bucket position calculation section 43 d calculates a posture of the front work implement 1 A in the local coordinate system (excavator coordinate system) and the position of the claw tip of the bucket 10 using information from the work implement posture sensor 50 .
  • the position information (X bk , Z bk ) of the claw tip of the bucket 10 can be calculated using Expression (1) and Expression (2).
  • the current landform data and design surface data can be translated to a machine body coordinate system having the machine body reference position PO as the origin. An example based on the machine body coordinate system will be described below.
  • the estimated excavation volume calculation section 43 f calculates the estimated excavation volume Va on the basis of the current landform data, the target surface data, bucket position data, and an excavation end position set in advance (reference position x 0 to be described later).
  • the estimated excavation volume Va is a volume of a closed area defined by an X-coordinate of the bucket claw tip position (x 1 to be described later), an X-coordinate of the bucket claw tip position at the excavation end set in advance (excavation end position) (reference position x 0 to be described later), the current landform 800 , the target surface 700 , and the width of the bucket 10 .
  • the estimated excavation volume calculation section 43 f calculates the volume Va (volume of the area shaded with dots in FIG.
  • the reference position x 0 is set to the X-coordinate of the frontmost portion in the lower track structure 11 when the upper swing structure 12 and the lower track structure 11 are aligned with each other in the anterior direction.
  • the volume of earth (estimated excavation volume) Va can be obtained from Expression (3) given below.
  • the reference position x 0 (excavation end position) may be referred to as a “second position” as against a first position that is the bucket claw tip position at the excavation start (excavation start position).
  • z denotes a difference in Z-coordinate between a point on the current landform and a point on the target surface, the two points having identical X- and Y-coordinates
  • w denotes the width of the bucket 10 . While the present embodiment uses the bucket width w for simplified calculation, the estimated excavation volume Va may be obtained by integrating the point group of the current landform existing within the bucket width also in the Y-axis direction.
  • the estimated excavation volume calculation section 43 f outputs the estimated excavation volume Va to the target surface generation section 43 g.
  • the limit volume Vb can be set to any value that is maximum volume or smaller of an object that is to be excavated and that can be held by the bucket 10 .
  • the limit volume Vb is typically set to a value doubling the bucket capacity or smaller.
  • the limit volume Vb may be said, from a work efficiency viewpoint, to be a target value of excavated volume (target excavated amount) to be housed in the bucket 10 during one excavation sequence by the work implement 1 A.
  • a relation among the correction volume Vc, an excavation distance L, the bucket width w, and the correction amount d may be expressed by Expression (5) given below.
  • the excavation distance L represents a difference in the X-coordinate between the bucket claw tip position and the excavation end position.
  • the excavation distance L can be found by subtracting the reference position x 0 from the bucket position information x 1 .
  • the correction amount d can be obtained, as in Expression (6) given below.
  • the target surface generation section 43 g calculates the excavation distance L using, as the excavation start position (first position), the bucket claw tip position (x 1 ) calculated by the bucket position calculation section 43 d when the bucket claw tip position is located within a predetermined range from the current landform 800 and a crowding operation of the arm 6 (arm pull command) is input via the operation device 45 b .
  • the target surface generation section 43 g then generates the second target surface 700 A by offsetting the first target surface 700 superiorly by the correction amount d, which is obtained from the excavation distance L, the correction volume Vc, the bucket width w, and Expression (6) given above.
  • the target surface generation section 43 g does not generate the second target surface 700 A and the MG/MC control section 43 performs MC on the basis of the first target surface 700 .
  • the distance calculation section 43 h calculates a distance (target surface distance) D between a bucket claw tip P 4 (see FIG. 10 ) and the first target surface 700 or the second target surface 700 A, whichever is closer to the bucket claw tip P 4 (which is an MC-applied target surface).
  • the target surface distance D represents a distance between P 4 and the second target surface 700 A when the second target surface 700 A is generated by the target surface generation section 43 g , and represents a distance between P 4 and the first target surface 700 when the second target surface 700 A is not generated by the target surface generation section 43 g .
  • FIG. 10 is a diagram illustrating a positional relation between the bucket claw tip P 4 and the MC-applied target surfaces 700 and 700 A.
  • the distance between a foot of a vertical line extended from the bucket claw tip P 4 to the MC-applied target surfaces 700 and 700 A and the bucket position coordinate is the target surface distance D between the MC-applied target surfaces 700 and 700 A and the bucket claw tip P 4 .
  • the target speed calculation section 43 e calculates the operation amounts of the operation devices 45 a , 45 b , and 46 a (operation levers 1 a and 1 b ) on the basis of an input from the operator operation sensor 52 a . On the basis of the operation amounts, the target speed calculation section 43 e calculates target operating speeds of the boom cylinder 5 , the arm cylinder 6 , and the bucket cylinder 7 .
  • the operation amounts of the operation devices 45 a , 45 b , and 46 a can be calculated from detection values of the pressure sensors 70 , 71 , and 72 . Calculation of the operation amounts using the pressure sensors 70 , 71 , and 72 is illustrative only.
  • the operation amount of the operation lever may be detected using a position sensor (e.g., rotary encoder) that detects rotational displacement of the operation lever for each of the operation devices 45 a , 45 b , and 46 a .
  • a possible configuration includes a stroke sensor that detects an extension or contraction amount of each of the hydraulic cylinders 5 , 6 , and 7 to thereby allow the operating speed of each cylinder to be calculated on the basis of changes over time in the detected extension or contraction amount.
  • the correction speed calculation section 43 i calculates, on the basis of the target surface distance D output from the distance calculation section 43 h , a correction factor k of a component V 0 z (vertical component) perpendicular to the target surface (the MC target surface that has been used for calculation of the target surface distance D, specifically, the target surface 700 or the target surface 700 A) in a speed vector V 0 of the bucket claw tip P 4 .
  • FIG. 11 is a graph illustrating a relation between the target surface distance D and the speed correction factor k.
  • the target surface distance D is assumed to be positive when the bucket claw tip P 4 is located superior to the target surface.
  • the speed correction factor k decreases from 1 with decreasing the target surface distance D from a predetermined distance d 1 .
  • FIG. 12 is a diagram illustrating the speed vector V 0 at the bucket distal end.
  • the correction speed calculation section 43 i calculates the speed vector V 0 of the bucket claw tip P 4 on the basis of the actuator speed output from the target speed calculation section 43 e .
  • the bucket speed vector V 0 is then decomposed into the vertical component V 0 z and a horizontal component V 0 x of the target surface and the vertical component V 0 z is multiplied by the correction factor k to obtain a correction speed V 1 z .
  • the speed vector composed of the correction speed V 1 z and the horizontal component V 0 x of the original speed vector V 0 assumes a speed vector V 1 of the bucket claw tip P 4 after the correction. This results in the following.
  • the speed in the vertical direction of the speed vector at the bucket claw tip P 4 approaches zero as the distance D approaches zero as a result of the bucket claw tip P 4 approaching the target surface. Then, MC where the bucket claw tip P 4 moves along the target surface is performed.
  • the speed correction factor k is invariably 1 regardless of the distance D. Thus, the speed in the boom raising operation is not reduced.
  • the target pilot pressure calculation section (control signal calculation section) 43 j calculates the target speed of each of the hydraulic cylinders 5 , 6 , and 7 capable of being output by the speed vector V 1 (V 1 z , V 0 x ) of the bucket claw tip P 4 after the correction.
  • software has been programmed to perform MC that translates the distal end speed vector V 0 to the target speed vector V 1 through a combination of boom raising and arm crowding deceleration, a cylinder speed in the direction of extending the boom cylinder 5 and a cylinder speed in the direction of extending the arm cylinder 6 are calculated.
  • the target pilot pressure calculation section 43 j then calculates, on the basis of the calculated target speed of each of the cylinders 5 , 6 , and 7 , a target pilot pressure (control signal) for each of the flow control valves 15 a , 15 b , and 15 c of the hydraulic cylinders 5 , 6 , and 7 .
  • the target pilot pressure calculation section 43 j then outputs the target pilot pressure for the corresponding one of the flow control valves 15 a , 15 b , and 15 c of the hydraulic cylinders 5 , 6 , and 7 to the solenoid proportional valve control section 44 .
  • the solenoid proportional valve control section 44 calculates commands for solenoid proportional valves 54 to 56 on the basis of the target pilot pressures for the flow control valves 15 a , 15 b , and 15 c output from the target pilot pressure calculation section 43 j . It is noted that, when the pilot pressure based on an operator operation (first control signal) coincides with the target pilot pressure calculated by an actuator control section 81 , the current value (command value) for the corresponding one of the solenoid proportional valves 54 to 56 is zero and the corresponding one of the solenoid proportional valves 54 to 56 is not operated.
  • the display control section 374 a performs processing for displaying on the display device 53 a a positional relation between the target surface 700 and the work implement 1 A (claw tip of the bucket 10 ) on the basis of the posture information of the front work implement 1 A, the position information of the claw tip of the bucket 10 , and the position information of the target surface 700 that are input from MG/MC control section 43 .
  • This causes a display screen of the display device 53 a to display the positional relation between the target surface 700 and the work implement 1 A (claw tip of the bucket 10 ) as illustrated in FIG. 15 .
  • FIG. 13 illustrates a flowchart through which the MG/MC control section 43 sets the target surface.
  • the MG/MC control section 43 starts processing at predetermined control cycles and the current landform updating section 43 a updates the position information of the current landform stored in the current landform storage section 43 b using the latest position information of the current landform acquired by the current landform acquisition device 96 (Step S 1 ).
  • the bucket position calculation section 43 d calculates the bucket claw tip position (X bk , Z bk ) on the basis of the information output from the work implement posture sensor 50 (Step S 2 ).
  • the estimated excavation volume calculation section 43 f acquires the current landform data and the first target surface data that fall within a predetermined range on the basis of the bucket claw tip position calculated at Step S 2 (Step S 3 ). The estimated excavation volume calculation section 43 f then calculates the estimated excavation volume Va using the bucket claw tip position, the current landform data, and the first target surface data (Step S 4 ).
  • the target surface generation section 43 g determines whether the estimated excavation volume Va exceeds the limit volume Vb set in advance (Step S 5 ). When it is determined at Step S 5 that the estimated excavation volume Va does not exceed the limit volume Vb (specifically, the estimated excavation volume Va is equal to or smaller than the limit volume Vb), the target surface generation section 43 g does not generate the second target surface 700 A, so that the first target surface 700 assumes the MC target surface (MC-applied target surface) (Step S 6 ).
  • Step S 5 when it is determined at Step S 5 that the estimated excavation volume Va exceeds the limit volume Vb, the target surface generation section 43 g calculates the correction amount d of the target surface (Step S 7 ). Step S 8 is then performed.
  • the target surface generation section 43 g determines whether the bucket claw tip position (X bk , Z bk ) is located within a predetermined range from the current landform 800 . When it is determined by this determination that the bucket claw tip is located within the predetermined range, Step S 9 is then performed. When it is determined by this determination that the bucket claw tip is located outside the predetermined range, Step S 6 is then performed.
  • Step S 9 the target surface generation section 43 g determines whether an arm pull command (arm crowding operation) has been input via the operation device 45 b . When it is determined by this determination that the arm pull command has not been input, Step S 6 is then performed. When it is determined by this determination that the arm pull command has been input, a surface offset by the correction amount d superiorly from the first target surface 700 is generated as the second target surface 700 A (Step S 10 ) and Step S 11 is then performed. Step S 10 sets the second target surface 700 A as the MC target surface (MC-applied target surface).
  • an arm pull command arm crowding operation
  • the target surface generation section 43 g determines whether the input of the arm pull command is terminated. As long as the arm pull command continues, use of the second target surface 700 A corrected at Step S 10 in MC is maintained. On the other hand, when the arm pull command is terminated, use of the second target surface 700 A in MC is terminated.
  • FIG. 14 is a flowchart for MC by the MG/MC control section 43 .
  • the MG/MC control section 43 starts processing illustrated in FIG. 13 .
  • the bucket position calculation section 43 d calculates the bucket claw tip position (bucket position data) on the basis of the information from the work implement posture sensor 50 (Step S 12 ).
  • the distance calculation section 43 h acquires the position information (target surface data) of the first target surface 700 or the second target surface 700 A set as the MC-applied target surface by the flowchart of FIG. 13 from the target surface generation section 43 g .
  • the distance calculation section 43 h calculates the target surface distance D using the bucket position data calculated at Step S 12 and the target surface data acquired at Step S 13 .
  • the correction speed calculation section 43 i calculates the speed correction factor k ( ⁇ 1 ⁇ k ⁇ 1) of the component V 0 z perpendicular to the MC-applied target surface in the speed vector V 0 of the bucket claw tip P 4 using the target surface distance D calculated at Step S 14 .
  • the target speed calculation section 43 e calculates the operation amounts of the operation devices 45 a , 45 b , and 46 a (operation levers 1 a and 1 b ) using the input from the operator operation sensor 52 a and, on the basis of the operation amounts, and calculates the target operating speeds of the boom cylinder 5 , the arm cylinder 6 , and the bucket cylinder 7 .
  • the correction speed calculation section 43 i calculates the speed vector V 0 of the bucket claw tip P 4 using each actuator speed calculated at Step S 16 .
  • the bucket speed vector V 0 is then decomposed into the vertical component V 0 z and the horizontal component V 0 x of the target surface and the vertical component V 0 z is multiplied by the correction factor k to obtain the correction speed V 1 z .
  • the correction speed calculation section 43 i combines the correction speed V 1 z with the horizontal component V 0 x of the original speed vector V 0 to thereby calculate the corrected speed vector V 1 of the bucket claw tip P 4 .
  • the target pilot pressure calculation section 43 j calculates the target speed of each of the hydraulic cylinders 5 , 6 , and 7 on the basis of the corrected speed vector V 1 (V 1 z , V 0 x ) calculated at Step 517 .
  • the target pilot pressure calculation section 43 j then calculates target pilot pressures for the flow control valves 15 a , 15 b , and 15 c of the respective hydraulic cylinders 5 , 6 , and 7 on the basis of the calculated target speeds of the hydraulic cylinders 5 , 6 , and 7 and outputs the target pilot pressures to the solenoid proportional valve control section 44 .
  • MC is thereby performed so as to control an operation of at least one of the hydraulic cylinders 5 , 6 , and 7 such that the bucket claw tip is located on or superior to the target surface 700 .
  • the correction amount d is then calculated such that the volume defined by the bucket claw tip position (x 1 ) at that particular point in time, the previously set excavation end position (x 0 ), the current landform 800 , the second target surface 700 A, which is the first target surface 700 setback superiorly by the correction amount d, and the bucket width w is the limit volume Vb (Steps S 5 to S 7 ).
  • An excavation operation is typically started by the hydraulic excavator 1 with the input of an arm pull command (crowding operation of the arm 6 ) via the operation device 45 b under a condition in which the bucket claw tip is moved on the current landform to a position away from the machine body 1 B through raising and lowering operations of the boom 5 and dumping operations of the arm 6 .
  • the bucket claw tip can be considered to be located on the current landform when the arm pull command is input and the excavation operation can be considered to be started from that position.
  • Step S 9 when the estimated excavation volume Va is greater than the limit volume Vb, it is determined at Step S 9 whether the arm pull command is input and, when it is determined that the arm pull command is input, the second target surface 700 A is generated on the assumption that the bucket claw tip position at that point in time is the excavation start position (first position) (Step S 10 ).
  • the second target surface 700 A is generated at a position at which the estimated excavation volume is Vb with reference to the excavation start position (first position) and the second target surface 700 A is set as the MC-applied target surface (processing by way of Step S 10 in FIG. 13 is performed).
  • the first target surface 700 is set as the MC-applied target surface (processing by way of Step S 6 in FIG. 13 is performed).
  • the MG/MC control section 43 follows the steps of the flowchart of FIG. 14 to perform the MC that controls at least one of the hydraulic actuators 5 , 6 , and 7 such that the vertical component (component perpendicular to the target surface 700 ) of the speed vector of the claw tip is reduced as the claw tip gets closer to the MC-applied target surface, during a period of time over which the claw tip of the bucket 10 moves through the deceleration area 600 by the arm crowding operation.
  • the vertical component of the speed vector of the claw tip is zero on the MC-applied target surface, so that the operator can perform excavation along the MC-applied target surface by simply inputting the arm crowding operation. Load on the operator during the excavation work can thereby be reduced.
  • the flowchart of FIG. 13 ensures that the target surface is determined in accordance with the bucket claw tip position (first position) at the excavation start such that the excavation amount is always equal to or smaller than the limit volume Vb.
  • the excavation start position (first position) varying among different excavation operations (specifically, even when the excavation distance L varies for each excavation operation), the actual excavation amount can be prevented from exceeding the limit volume Vb.
  • the estimated excavation volume Va is calculated on the basis of the posture of the hydraulic excavator 1 at the excavation start and the MC-applied target surface is generated such that the actual excavation amount is always equal to or smaller than the limit volume Vb, so that the MC-applied target surface can be generated at an appropriate position even when the excavation distance L varies and the actual excavation amount can be prevented from exceeding the limit volume Vb (e.g., maximum bucket capacity).
  • the front work implement 1 A is controlled such that the bucket 10 is prevented from entering an area beneath the MC-applied target surface and the bucket 10 operates along the MC-applied target surface, so that operating load on the operator during the excavation work can be reduced.
  • the excavation work can be performed, in which the design surface is not damaged under a condition in which the excavation amount in one excavation operation is held within the maximum bucket capacity.
  • a current landform acquisition device may nonetheless be prepared independently of the hydraulic excavator 1 , as with a drone, for example, in which a laser scanner is mounted as the current landform acquisition device for acquiring the current landform information and the current landform information acquired by such a current landform acquisition device may be input and used.
  • a hydraulic excavator in the present embodiment is identical to the hydraulic excavator in the preceding embodiment except that a controller in the hydraulic excavator in the present embodiment (more specifically, details of processing performed by the current landform updating section) differs from the controller in the preceding embodiment. The following describes only the differences from the preceding embodiment.
  • FIG. 16 is a functional block diagram of an MG/MC control section 43 A according to the present embodiment.
  • the MG/MC control section 43 A in the present embodiment differs from the MG/MC control section 43 of the preceding embodiment in that the MG/MC control section 43 A includes a current landform updating section 43 aa.
  • Position information of the current landform stored in the current landform storage section 43 b and position information of the bucket claw tip calculated by the bucket position calculation section 43 d are input to the current landform updating section 43 aa .
  • the position information of the current landform stored in the current landform storage section 43 b is updated with the position information of the bucket claw tip calculated by the bucket position calculation section 43 d .
  • the position information of the current landform stored in the current landform storage section 43 b is not updated.
  • a trajectory drawn by the bucket claw tip during excavation of the current landform is regarded as the current landform after the excavation and the current landform data is updated accordingly.
  • FIG. 17 is a schematic diagram illustrating updating of the current landform performed by the current landform updating section 43 aa on the basis of the position information of the bucket claw tip.
  • a coordinate z 1 in the bucket height direction is compared with a coordinate z 0 in the current landform height direction.
  • z 1 is updated as new current landform data.
  • Such use of the bucket claw tip position information for updating the current landform eliminates the need for the current landform acquisition device 96 to acquire the current landform data for each excavation sequence, so that time required for acquisition of the current landform data can be shortened.
  • the current landform data is thereafter updated sequentially by an updating function of the current landform updating section 43 aa . This can eliminate the current landform acquisition device 96 from the hydraulic excavator 1 .
  • the first target surface 700 described above may be considered as a design surface defining a final excavation work shape.
  • FIG. 18 is a schematic diagram illustrating a method for generating the second target surface 700 A when the first target surface 700 is inclined with respect to the excavator coordinate.
  • FIG. 19 is a schematic diagram illustrating a method for generating the second target surface 700 A when the first target surface 700 is formed of a plurality of surfaces having different inclinations from each other.
  • the above embodiment solves the problem through the following approach. Specifically, when the estimated excavation volume Va calculated on the basis of the position of the original target surface (first target surface 700 ) exceeds a desired limit volume Vb, a new target surface (second target surface 700 A) is generated at a position superior to the original target surface (first target surface 700 ), to thereby bring the volume calculated on the basis of the position of the new target surface close to the limit volume Vb.
  • the hydraulic excavator may nonetheless be configured such that the target surface is set directly at a position at which the estimated excavation volume to be excavated by one excavation sequence matches, or is close to, the limit volume Vb.
  • the controller 43 which includes the current landform storage section 43 b for storing the position information of the current landform 800 and the bucket position calculation section 43 d for calculating the position of the claw tip of the bucket 10 , the controller 43 further includes the target surface generation section 43 g that generates the target surface at a position at which the excavation volume defined by the first position that assumes the position of the claw tip of the bucket calculated by the bucket position calculation section 43 d at the excavation start, the second position that assumes the position of the claw tip of the bucket at the excavation end set in advance, the current landform 800 , the target surface, and the width w of the bucket is closer to the limit volume Vb set
  • correction factor k specified in FIG. 11 is illustrative only and may take any value that results in the vertical component V 0 z of the speed vector approaching 0 at the target surface distance D in the positive range approaching 0.
  • the present invention is not limited to the above-described embodiments and may include various modifications without departing from the scope and spirit of the present invention.
  • the entire detailed configuration of the embodiments is not always necessary to embody the present invention and part of the configuration may be deleted.
  • Part of the configuration of one embodiment may be replaced with the configuration of another embodiment, or the configuration of one embodiment may be combined with the configuration of another embodiment.

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US20210017738A1 (en) * 2018-03-27 2021-01-21 Sumitomo Heavy Industries, Ltd. Shovel
US20220106767A1 (en) * 2020-10-01 2022-04-07 Caterpillar Sarl Virtual boundary system for work machine
US20230097563A1 (en) * 2021-09-28 2023-03-30 Deere & Company System and method for blade control on a utility vehicle

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JP2022168730A (ja) * 2021-04-26 2022-11-08 コベルコ建機株式会社 目標軌跡生成システム
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US20210017738A1 (en) * 2018-03-27 2021-01-21 Sumitomo Heavy Industries, Ltd. Shovel
US11959254B2 (en) * 2018-03-27 2024-04-16 Sumitomo Heavy Industries, Ltd. Shovel
US20200370281A1 (en) * 2018-03-29 2020-11-26 Komatsu Ltd. Control system for work vehicle, method, and work vehicle
US11746504B2 (en) * 2018-03-29 2023-09-05 Komatsu Ltd. Control system for work vehicle, method, and work vehicle
US20220106767A1 (en) * 2020-10-01 2022-04-07 Caterpillar Sarl Virtual boundary system for work machine
US11572671B2 (en) * 2020-10-01 2023-02-07 Caterpillar Sarl Virtual boundary system for work machine
US20230097563A1 (en) * 2021-09-28 2023-03-30 Deere & Company System and method for blade control on a utility vehicle

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CN109757113B (zh) 2021-03-16
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JPWO2019049248A1 (ja) 2019-11-07
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CN109757113A (zh) 2019-05-14
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WO2019049248A1 (ja) 2019-03-14

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