WORK MACHINE

A working status indicating a status related to the present work of a hydraulic excavator 1 is determined on the basis of operation signals output from a control lever 24, posture information output from inertial measuring devices 27 to 30, load information output from pressure sensors 32 and 33, and a work area set by a display input device 26, an operation form indicating contents of an operation in operation correction control of a front work implement 12 is decided from a plurality of operation forms set in advance, according to the determined working status, and the operation correction control is performed such that the front work implement moves according to the operation form. Thus, an appropriate assisting operation can be performed in machine control, so that the work accuracy can be improved.

TECHNICAL FIELD

The present invention relates to a work machine.

BACKGROUND ART

As a technology for improving work efficiency of a work machine typified by a hydraulic excavator, machine control (MC) is known which semiautomatically controls the operation of a work device (for example, a work device including a boom, an arm, and a bucket) according to an operation made by an operator of the work device who operates an operation device and conditions determined in advance. The machine control (hereinafter referred to simply as MC) assists the operator to operate the work device by, for example, maintaining a distal end position of the bucket in the work device at a distance determined in advance with respect to a target surface or maintaining the posture (angle) of the bucket at an angle determined in advance with respect to the target surface.

As a technology related to MC settings, Patent Document 1, for example, discloses a control system for a work vehicle having a work implement (work device). The work vehicle control system includes a first control lever of the work implement, a first operating member provided to the first control lever, and a controller that performs automatic control of the work implement. The controller performs the function of the automatic control assigned to the first operating member, according to an operation of the first operating member, when execution conditions including a condition that the first control lever is at a neutral position are satisfied.

PRIOR ART DOCUMENT

Patent Document

SUMMARY OF THE INVENTION

Problems to be Solved by the Invention

In order to achieve appropriate operation assistance in MC, it is necessary to switch between the enabling and disabling of MC according to work contents and a work environment and set appropriate assistance contents, for example. In the conventional technology, the operator alternately selects the enabling and disabling of the automatic control by operating the operating member provided to the control lever. In such a case, however, if the operator forgets to operate the operating member, work may be performed while the automatic control is disabled. Consequently, excavation may possibly be performed beyond a design surface. In addition, when the work contents are set through an operation made by the operator, if the operator sets the work contents or the assistance contents erroneously, the work device may not be set in a desired posture. As a result, the work device may erroneously excavate a construction surface excessively or drop soil transported to the construction surface, so that sufficient work accuracy may not be obtained. That is, in the case as described above, an appropriate MC operation may be unable to be performed, and thus, the work accuracy may be decreased.

The present invention has been made in view of the above. It is an object of the present invention to provide a work machine that can perform an appropriate assisting operation in the machine control and consequently improve the work accuracy.

Means for Solving the Problems

The present application includes a plurality of pieces of means for solving the above-described problems. As an example of the means, there is provided a work machine including a lower track structure, an upper swing structure that is swingable with respect to the lower track structure, an articulated front work implement that is attached to the upper swing structure and includes a plurality of front implement members rotatably coupled together, an operation device that outputs operation signals for driving the upper swing structure and the front work implement according to amounts of operations made by an operator, a plurality of front work implement actuators that individually drive the plurality of front implement members on the basis of driving signals generated according to the operation signals output from the operation device, a swing actuator that swing-drives the upper swing structure on the basis of the operation signal output from the operation device, a posture information sensor that senses posture information as information regarding postures of the upper swing structure and the front work implement, and a controller that performs operation correction control to output a driving signal to at least one of the plurality of front work implement actuators such that the front work implement is set in a predetermined position or posture on a predetermined target surface and within one area with respect to the target surface, on the basis of the operation signals output from the operation device and the posture information sensed by the posture information sensor. The work machine further includes a load information sensor that senses load information as information regarding a load on at least one hydraulic actuator of the plurality of front work implement actuators, and a work area setting device that sets a work area over the predetermined target surface. The controller determines a working status indicating a status related to present work of the work machine, on the basis of the operation signals output from the operation device, the posture information sensed by the posture information sensor, the load information sensed by the load information sensor, and the work area set by the work area setting device, decides an operation form indicating contents of an operation in the operation correction control of the front work implement, from a plurality of operation forms set in advance, according to the determined working status, and performs the operation correction control such that the front work implement moves according to the operation form.

Advantages of the Invention

According to the present invention, it is possible to perform an appropriate assisting operation in machine control and consequently improve the work accuracy.

MODES FOR CARRYING OUT THE INVENTION

Embodiments of the present invention will hereinafter be described with reference to the drawings. It is to be noted that, while a hydraulic excavator mounted with an articulated front work implement will be illustrated and described as an example of a work machine in the embodiments, the present invention is also applicable to other work machines provided with a front work implement.

First Embodiment

FIG.1is a diagram schematically illustrating an external appearance of a hydraulic excavator as an example of a work machine according to the present embodiment.

InFIG.1, a hydraulic excavator1essentially includes a lower track structure10, an upper swing structure11swingably provided to the lower track structure10, a front work implement12rotatably provided to the upper swing structure11, and an operation room22where an operator operates the machine.

The front work implement12is of an articulated type and includes a plurality of front implement members (a boom13, an arm14, and a bucket (work tool)15) that each rotate in a vertical direction and that are coupled together. A proximal end of the boom13is supported by a front portion of the upper swing structure11rotatably in the vertical direction. One end of the arm14is supported by an end portion (distal end) of the boom13, which is opposite to the proximal end of the boom13, rotatably in the vertical direction. The bucket15as a work tool is supported by the other end of the arm14rotatably in the vertical direction.

The boom13, the arm14, and the bucket15are rotationally driven by a boom cylinder17, an arm cylinder18, and a bucket cylinder19, respectively, which are hydraulic actuators (front work implement actuators). Further, the upper swing structure11is swing-driven by a swing hydraulic motor16which is a hydraulic actuator (swing actuator). In addition, the lower track structure10is travel-driven by left and right travelling hydraulic motors, not illustrated, which are hydraulic actuators (travelling actuators).

The boom cylinder17includes a pressure sensor32aand a pressure sensor32bthat serve as load information sensors for sensing load information as information regarding a load on the hydraulic actuator. The pressure sensor32asenses a hydraulic pressure on a rod side, and the pressure sensor32bsenses a hydraulic pressure on a bottom side. Similarly, the arm cylinder18includes a pressure sensor33aand a pressure sensor33bthat serve as the load information sensors. The pressure sensor33asenses a pressure on a rod side, and the pressure sensor33bsenses a pressure on a bottom side. Hereinafter, the pressure sensors32aand32band the pressure sensors33aand33bmay collectively be referred to as a pressure sensor32and a pressure sensor33, respectively.

In the operation room22, control levers24aand24b(seeFIG.2) which are operation devices, a controller23, and a display input device26are arranged. The controller23controls the whole operation of the hydraulic excavator1. The display input device26displays information for the operator and receives an instruction input from the operator. Hereinafter, the two control levers24aand24bmay collectively be referred to as a control lever24.

The controller23is constituted by a central processing unit (CPU), a memory, and an interface. The CPU executes a program stored in the memory in advance and performs processing on the basis of set values stored in the memory and a signal input from the interface. Then, the interface outputs a signal.

The display input device26is, for example, a pointing device such as a touch panel. The display input device26displays information and receives an instruction from the operator through a graphical user interface (GUI) displayed on a screen.

The upper swing structure11, the boom13, the arm14, and the bucket15have inertial measuring devices (inertial measurement units (IMUs))27,28,29, and30, respectively. Each of the inertial measuring devices serves as a posture information sensor for sensing posture information as information regarding the posture of a corresponding one of the members. Hereinafter, when there is a need to distinguish these inertial measuring devices from one another, the respective inertial measuring devices will be referred to as a machine body inertial measuring device27, a boom inertial measuring device28, an arm inertial measuring device29, and a bucket inertial measuring device30. The relative positions where the inertial measuring devices27,28,29, and30are attached to the respective members can be obtained from design information or the like. Thus, the relative rotational angles of the upper swing structure11, the boom13, the arm14, and the bucket15can be estimated on the basis of sensing results (angular velocities and accelerations) from the inertial measuring devices27,28,29, and30.

In addition, two global navigation satellite system (GNSS) antennas31aand31bwhich are positional information sensors for sensing positional information are attached to an upper portion of the upper swing structure11. Each of the GNSS antennas31aand31bhas a position computing function of computing a signal received from an artificial satellite, to thereby compute the positional information. The GNSS antennas31aand31bcan estimate the azimuth (orientation) of the upper swing structure11from a difference between the positional information obtained by the GNSS antenna31aand the positional information obtained by the GNSS antenna31b. Hereinafter, the two GNSS antennas31aand31bmay collectively be referred to as a GNSS antenna31.

The control lever24disposed in the operation room22includes the two control levers24aand24bthat are swingable forward, rearward, leftward, and rightward. Each of the two control levers24aand24bof the control lever24is capable of receiving, as input, operation amounts of a total of four axial swings in a forward-rearward direction and a left-right direction. By generating driving signals in the controller23on the basis of operation signals generated according to the operation amounts of swinging operations of the control lever24, it is possible to drive the swing hydraulic motor16, the boom cylinder17, the arm cylinder18, and the bucket cylinder19individually according to the operations of the control lever24. In addition, operation buttons25aand25b(seeFIG.2) that can receive operation input through depression by the operator are provided on the control levers24aand24b, respectively. Hereinafter, the two operation buttons25aand25bmay collectively be referred to as an operation button25.

FIG.2is a diagram extracting and illustrating principal parts of a hydraulic circuit related to a driving mechanism of the hydraulic excavator.

InFIG.2, the driving mechanism of the hydraulic excavator1essentially includes a hydraulic pump39, a pilot pump40, control valves34,35,36, and37, a hydraulic operating fluid tank42, and a bleed-off unit43. The hydraulic pump39and the pilot pump40are driven by a prime mover41such as a diesel engine. The control valves34,35,36, and37control the flow rates and directions of hydraulic fluids supplied from the hydraulic pump39to the hydraulic actuators16,17,18, and19. The hydraulic operating fluid tank42supplies hydraulic operating fluids to the hydraulic pump39and the pilot pump40and stores the hydraulic operating fluids discharged from the hydraulic actuators16,17,18, and19. The bleed-off unit43discharges some of the hydraulic fluids delivered from the hydraulic pump39to the hydraulic operating fluid tank42.

The control valves34,35,36, and37are driven by hydraulic pressures (pilot pressures) of the hydraulic fluids delivered from the pilot pump40. The hydraulic fluids delivered from the pilot pump40are introduced into directional control valves34a,35a,36a, and37avia solenoid proportional pressure reducing valves34band34c,35band35c,36band36c, and37band37cof the control valves34,35,36, and37. The solenoid proportional pressure reducing valves34band34c,35band35c,36band36c, and37band37care controlled on the basis of current commands output from the controller23, so that the driving of the directional control valves34a,35a,36a, and37ais controlled. After the hydraulic fluids are supplied from the hydraulic pump39to the directional control valves34a,36a, and37a, the flow rates of hydraulic fluids to be distributed to the hydraulic actuators16,17,18, and19are adjusted according to operations of the solenoid proportional pressure reducing valves34band34c,35band36band36c, and37band37c.

The hydraulic pump39is of a variable displacement type. When a regulator39aoperates on the basis of a current command output from the controller23, the displacement of the hydraulic pump39is adjusted, and thus the flow rate of the hydraulic fluid to be delivered from the hydraulic pump39is controlled.

The bleed-off unit43includes a bleed-off valve43aand a bleed-off valve solenoid proportional pressure reducing valve43b. The bleed-off valve43aallows some of the hydraulic fluids delivered from the hydraulic pump39to return to the hydraulic operating fluid tank42. The bleed-off valve solenoid proportional pressure reducing valve43badjusts the flow rate of the hydraulic fluid to be released by the bleed-off valve43a. Some of the hydraulic fluids delivered from the hydraulic pump39are discharged to the hydraulic operating fluid tank42when the bleed-off valve43amakes a hydraulic line communicate with the hydraulic operating fluid tank42. The bleed-off valve43ais driven by a pilot pressure adjusted by the bleed-off valve solenoid proportional pressure reducing valve43b. That is, the flow rate of the hydraulic fluid returning to the hydraulic operating fluid tank42via the bleed-off valve43ais controlled by the pilot pressure adjusted by the bleed-off valve solenoid proportional pressure reducing valve43bon the basis of a current command output from the controller23.

The controller23is connected to the control lever24, the operation button25, the display input device26, the inertial measuring devices27,28,29, and30, and the GNSS antenna31. The controller23outputs current command signals for driving the solenoid proportional pressure reducing valves34band34c,35band35c,36band36c,37band37c, and43band the regulator39aon the basis of respective input signals from the control lever24, the operation button25, the display input device26, the inertial measuring devices27,28,29, and30, and the GNSS antenna31, and drives the hydraulic actuators16,17,18, and19, the hydraulic pump39, and the bleed-off unit43. Thus, the controller23controls the operation of the hydraulic excavator1.

FIG.3is a functional block diagram illustrating functional sections of the controller according to the present embodiment.

In the present embodiment, a system within the controller23is executed as a combination of some programs. The controller23receives instruction signals from the control lever24, the operation button25, and the display input device26and sensing signals from the inertial measuring devices27,28,29, and30, a rotational angle meter47, and the GNSS antenna31via interfaces, performs processing in the CPU, and then outputs, via interfaces, driving signals for individually driving the control valves34,35,36, and37, the hydraulic pump39, and the bleed-off unit43.

InFIG.3, the controller23includes: a work tool position and posture computing section50that computes the position and posture of the front work implement12(for example, the claw tip position of the bucket15and the angle of the bucket15with respect to a horizontal plane) on the basis of sensing results from the inertial measuring devices27,28,29, and30and the GNSS antenna31; a work target setting section51that sets a work target (for example, a target surface or a work area) as information regarding the position and shape of a work target for the hydraulic excavator1, on the basis of an instruction input by the operator to the display input device26; a working status determining section54that determines a working status related to the present work of the hydraulic excavator1, on the basis of an operation signal output from the control lever24, sensing results from the pressure sensors32and33, a computation result output from the work tool position and posture computing section50, and the settings made by the work target setting section51; a work tool operation form setting section52that sets a plurality of operation forms corresponding to operations of the bucket (work tool) in operation correction control (at a time of an assisting operation) on the basis of the instruction input by the operator to the display input device26; a work tool operation form storage section53that stores the plurality of operation forms of the bucket15(work tool) which are set by the work tool operation form setting section52; a work tool operation form invoking section55that invokes a work form from the plurality of operation forms stored in the work tool operation form storage section53, on the basis of a determination result (that is, a determined working status) from the working status determining section54; a work tool operation correction amount computing section56that computes an operation correction amount to make the bucket15(work tool) perform a predetermined operation, on the basis of the computation result from the work tool position and posture computing section50, the work target set by the work target setting section51, and the operation form decided by the work tool operation form invoking section55; and a work implement control amount computing section57that computes control amounts of the respective hydraulic actuators16,17,18, and19of the hydraulic excavator1on the basis of the settings made by the work target setting section51, the operation signal (operation instruction from the operator) output from the control lever24, the computation result from the work tool position and posture computing section50, and the computation result (operation correction amount) from the work tool operation correction amount computing section56, and outputs current commands (driving signals) to the control valves34,35,36, and37, the hydraulic pump39(regulator39a), and the bleed-off unit43.

Next, an example of the details of work performed by the hydraulic excavator according to the embodiment of the present invention under the operation correction control (assisting operation) and the like.

FIG.4andFIG.5are overview diagrams illustrating examples of work performed by the hydraulic excavator.FIG.4is a diagram illustrating slope face shaping work.FIG.5is a diagram illustrating groove excavation work.

As illustrated inFIG.4, in the slope face shaping work, the hydraulic excavator1shapes a target surface5into a flat surface by excavating soil. Specifically, the hydraulic excavator1excavates the soil with a claw tip of the bucket15made to coincide with the target surface5, and after the soil is excavated to a certain extent, scoops the excavated soil by the bucket15and transports the excavated soil to a stock4. The hydraulic excavator1repeats the excavating operation and the transporting operation. In addition, in order to make the target surface5resulting from the excavation flatter, the hydraulic excavator1scoops the soil in the stock4by the bucket15, strews the soil over the whole of the target surface5by slightly dropping the soil from above the target surface5, and then presses a bottom surface of the bucket15against the soil.

When such slope face shaping work is executed, the operation correction control (assisting operation) is performed to assist in the excavating operation on the target surface5such that the claw tip of the bucket15does not reach a position below the target surface5, that is, the claw tip of the bucket15is moved along the target surface5. In addition, in the operation of pressing the bucket15against the target surface5, adjustment of the angle of the bucket15is assisted such that the bottom surface of the bucket15coincides with the target surface5while the claw tip of the bucket15is moved along the target surface5. By performing the assisting operation in this way, accuracy of the slope face shaping work can be improved.

Moreover, in the operation of transporting the soil excavated by the target surface5to the stock4and the operation of transporting the soil scooped from the stock4to the target surface5, the adjustment of the angle of the bucket15is assisted such that an opening plane where the bucket15is open is horizontal, so that the soil being transported can be prevented from dropping from the bucket Thus, extra work such as cleaning can be reduced, and work accuracy and work efficiency can be improved.

As illustrated inFIG.5, in the groove excavation work (for example, work of burying a material6), the hydraulic excavator1forms a groove3by excavating the ground, disposes the material6in the groove, and then refills the groove3. Specifically, the hydraulic excavator1sets, to the target surface5, a bottom surface of the groove3that has an appropriate height to dispose the material6therein, and excavates the ground with the claw tip of the bucket15of the hydraulic excavator1made to coincide with the target surface5. After the ground is excavated to a certain extent, the hydraulic excavator1scoops the excavated soil by the bucket15and transports the excavated soil to the stock4. The hydraulic excavator1repeats the excavating operation and the transporting operation. In addition, in order to refill the groove3, the hydraulic excavator1repeats an operation of excavating and scooping the soil in the stock4by the bucket15and an operation of transporting the soil to above the groove3and dropping the soil.

When such groove excavation work is executed, the operation correction control (assisting operation) is performed to assist in the excavating operation on the target surface5such that the claw tip of the bucket15does not reach a position below the target surface5, that is, the claw tip of the bucket15is moved along the target surface5, so that the work accuracy can be improved.

Moreover, in the operation of transporting the soil excavated in forming the groove3to the stock4and the operation of transporting the soil scooped from the stock4to the groove3, the adjustment of the angle of the bucket15is assisted such that the opening plane of the bucket15is horizontal, so that the soil being transported can be prevented from dropping from the bucket15. Thus, extra work such as cleaning can be reduced, and the work accuracy and the work efficiency can be improved.

That is, as illustrated inFIG.4andFIG.5, in order to improve the work accuracy and the work efficiency, the assisting operation for correcting the position and posture of the bucket15is preferably changed according to the working status such as the progress of the work.

FIG.6is a diagram of assistance in explaining computation of the posture of the hydraulic excavator and schematically illustrates the whole of the hydraulic excavator in perspective.

The work tool position and posture computing section50computes the distal end position (claw tip position) and posture (angle) of the bucket15as posture information regarding the hydraulic excavator1by using variables defined inFIG.6. For the hydraulic excavator1, a point of intersection of a swing axis of the upper swing structure11and a plane in contact with a lower side of the lower track structure10is defined as an origin Og of an excavator coordinate system. The position of the origin Og of the excavator coordinate system in a global coordinate system set outside the hydraulic excavator1can be obtained from the position of the GNSS antenna31in the global coordinate system which is sensed by the GNSS antenna31, and from an attachment height Lg1and a forward-rearward direction attachment length Lg2of the GNSS antenna31with respect to the origin Og of the excavator coordinate system. In addition, the orientation of the excavator coordinate system with respect to the global coordinate system can be obtained by matching the orientation of the excavator coordinate system with the orientation (azimuth angle) of the hydraulic excavator1in the global coordinate system which is sensed by the GNSS antenna31, about an axis perpendicular to the horizontal plane. Here, a simultaneous transformation matrix from the global coordinate system to the excavator coordinate system is defined as Tsh.

A distal end position (claw tip position) Pbk of the bucket15with respect to the origin Og of the excavator coordinate system can be obtained by using a swing angle θsw of the upper swing structure11, a swing angle θbm of the boom13, a swing angle θam of the arm14, and a swing angle θbk of the bucket15as well as lengths Lf1, Lf2, Lbm, Lam, and Lbk of the respective members, and applying a D-H method (Denaviet-Hartenberg notation) or the like with the hydraulic excavator1as a link structure constituted of four links, that is, obtaining a product of simultaneous transformation matrices defined for the respective links.

Here, relations between the distal end position Pbk=(Xbk, Ybk, Zbk) of the bucket15, an angle (Pitch_bk) formed between the horizontal plane (global coordinate system) and the excavator coordinate system, and the angles (θsw, θbm, θam, and θbk) between the respective members can be expressed by the following vector equations (Equation 1) to (Equation 3). Incidentally, “{circumflex over ( )}T” in (Equation 1) and (Equation 2) below represents transposition.

FIG.7andFIG.8are diagrams illustrating an example of work targets.FIG.7is a diagram illustrating the work targets in the slope face shaping work.FIG.8is a diagram illustrating the work targets in the groove excavation work. Incidentally, inFIG.7andFIG.8, the target surface5and a work area7are illustrated as the work targets, which are pieces of information regarding the position and shape of the work targets.

As illustrated inFIG.7andFIG.8, in the work target setting section51, the target surface5, which is one of the work targets in the slope face shaping work (seeFIG.4) and the groove excavation work (seeFIG.5), is defined as a rectangular plane formed with four representative points Pt1to Pt4as vertices thereof. A vector n=[nx, ny, nz]{circumflex over ( )}T normal to the target surface5can be obtained by normalizing an outer product of a vector (Pt3−Pt2) and a vector (Pt1−Pt2). In addition, supposing that representative points Pt1′ to Pt4′ different from the representative points Pt1to Pt4defining the target surface5are set above the target surface5, the work area7, which is one of the work targets, is defined as a solid in a three-dimensional space which has the target surface5as one of surfaces thereof. That is, the work target setting section51sets the target surface5as a work target on the basis of an instruction (representative points Pt1to Pt4) input by the operator to the display input device26, and sets the work area7as a work target on the basis of the instruction (representative points Pt1to Pt4and Pt1′ to Pt4′).

As illustrated inFIG.9, on the display input device26, a GUI displays a work target display90, which is the whole image of the work target, from information of a construction drawing set on the input screen (work area setting screen) in advance, and displays a selection status of any surface on the work target display90which is to be set as the target surface5. In addition, the GUI displays a confirmation button95and a return button96on the screen and receives a selection input by the operator of the hydraulic excavator1. When the confirmation button95is depressed in a state in which any surface is selected, the target surface5is set as a target to which the work area7is set. When the target surface5is set by depressing the confirmation button95, a work area adjustment display91for setting the work area7is displayed, and a setting of the size of the work area7, that is, a distance from the target surface5to the upper surface of the work area7(surface defined by representative points Pt1′ to Pt4′ inFIG.7andFIG.8), made by the operator of the hydraulic excavator1is received.

In the present embodiment, a case where the target surface5and the upper surface of the work area7are defined to be parallel with each other and where the size of the work area7is set by indicating one of the four representative points constituting the upper surface on the work area adjustment display91has been described by way of example. It is to be noted, however, that the configuration is not limited to this. For example, such a configuration may be adopted that distances from the target surface5to a plurality of points among the four representative points constituting the upper surface of the work area7can be adjusted individually.

In addition, when the size of the work area7is set by depressing of the confirmation button95on the work area setting screen of the display input device26, an intra-work area bucket setting screen92is next displayed on the display input device26. On the intra-work area bucket setting screen92, the details of the assisting operation (operation form) for the bucket15within the work area7is set. The intra-work area bucket setting screen92displays a bucket height adjustment display93and receives a setting of the claw tip position of the bucket15(distance from the target surface5) made by the operator. The intra-work area bucket setting screen92also displays a bucket posture adjustment display94and receive a setting of the posture (angle with respect to the horizontal plane) of the bucket15made by the operator. Incidentally, on the intra-work area bucket setting screen92, the claw tip position and posture of the bucket15are set to correspond to each of a plurality of kinds of operation forms.

The kinds of operation forms of the assisting operation include a “bucket posture maintaining mode,” a “claw tip position designating mode,” and a “bucket horizontal maintaining mode.” The “bucket posture maintaining mode” is an operation form in which the angle of the bucket15is controlled such that the bottom surface of the bucket15is made to coincide with the target surface5. In addition, the “claw tip position designating mode” is an operation form in which the position of the bucket15is controlled such that the claw tip of the bucket15is made to coincide with the target surface5. Moreover, the “bucket horizontal maintaining mode” is an operation form in which the angle of the bucket15is controlled such that the opening plane of the bucket15is held horizontal.

The work tool operation form setting section52sets an operation form on the basis of the instruction input by the operator to the display input device26, and stores the operation form in the work tool operation form storage section53.

Next, working status determination processing in the working status determining section54will be described. The working status determining section54performs work type determination processing and work tool state determination processing as the working status determination processing for determining a working status indicating the status of the work of the hydraulic excavator1. In the work type determination processing, a work type that is a classification indicating the state of the work being performed by the hydraulic excavator1is determined on the basis of the computation result from the work tool position and posture computing section50and the settings made by the work target setting section51. In addition, in the work tool state determination processing, a work tool state that is the state of the bucket15is determined on the basis of the sensing results from the pressure sensors32and33and the computation result from the work tool position and posture computing section50. Incidentally, the working status determination processing (the work type determination processing and the work tool state determination processing) in the controller23is repeatedly performed at intervals of a unit processing time (for example, a sampling time) determined in advance.

In the work type determination processing, the work type, which is the classification indicating the state of the work being performed by the hydraulic excavator1, is set on the basis of the position and operation direction of the front work implement12(specifically, the bucket15).

FIG.11is a flowchart illustrating the details of the work type determination processing.

As illustrated inFIG.11, in the work type determination processing, the controller23first transforms the representative points Pt1to Pt4and Pt1′ to Pt4′ (seeFIG.7andFIG.8) of the work area7that are set by the work target setting section51and the normal vector n, the representative points and the normal vector being expressed in the global coordinate system, from the global coordinate system to the coordinate system of the hydraulic excavator1(machine body coordinate system) (step S100).

The transformation of the representative points Pt1to Pt4and Pt1′ to Pt4′ and the normal vector n from the global coordinate system to the machine body coordinate system can be performed according to (Equation 4) to (Equation 6) below using a simultaneous transformation matrix Tsh (here, suppose that “l” is a positive integer indicating a number).

Next, whether or not a claw tip position Pst of the bucket15is within the work area7is determined on the basis of the computation result from the work tool position and posture computing section50and the settings made by the work target setting section51(step S120).

Whether or not the claw tip position Pst of the bucket15is within the work area7can be determined, for example, by using the magnitude of an inner product of a normal to each surface of a hexahedron formed by the representative points Pt1to Pt4and Pt1′ to Pt4′, the normal extending in a direction towards the area, and a vector connecting each representative point and the claw tip position Pst of the bucket15to each other. For example, as illustrated inFIG.12, when an inner product of a vector nl normal to the target surface5and a vector vpt12connecting the representative point Pt2and the claw tip position Pst of the bucket15to each other is equal to or more than 0 (zero), it can be determined that the claw tip position Pst is located on the upper side of the target surface5, that is, the work area7side. When the inner product is less than 0 (zero), it can be determined that the claw tip position Pst is located on the lower side of the target surface5, that is, outside the work area7. Similar processing is performed for all of the surfaces constituting the work area7. When all of the inner products are equal to or more than 0 (zero), it can be determined that the claw tip position Pst of the bucket15is located within the work area7.

Next, a movement destination of the claw tip position Pst of the bucket15corresponding to an operation made by the operator of the hydraulic excavator1, that is, a demanded claw tip position Pest demanded by the operator, is predicted on the basis of an operation signal output from the control lever24, and whether a result of the prediction (demanded claw tip position Pest) is within the work area7is determined (step S130).

The demanded claw tip position Pest can be obtained by (Equation 7) and (Equation 8) below. In the following Equations, ωlev represents angular velocity target values of the angles θsw, θbm, θam, and θbk of the respective parts which are obtained by geometric transformation of speed target values of the swing hydraulic motor16, the boom cylinder17, the arm cylinder18, and the bucket cylinder19, the speed target values being proportional to operation amounts (operation signals) of the control lever24, and an estimated time Δtest determined in advance is used.

Whether or not the demanded claw tip position Pest is located within the work area7can be determined by subjecting the obtained demanded claw tip position Pest to computation similar to that of step S120.

Next, whether the present claw tip position Pst of the bucket15is within the work area7is determined on the basis of a result of the computation in step S120(step S140). When a result of the determination is YES, whether the demanded claw tip position Pest is within the work area7is next determined on the basis of a result of the computation in step S130(step S150).

When a result of the determination in step S150is YES, that is, when both the claw tip position Pst and the demanded claw tip position Pest of the bucket15are within the work area7, the work type indicating the state of the work of the hydraulic excavator1is set to “intra-target work” which indicates that the work is being performed within the work area7(step S151). The processing is then ended.

In contrast, when the result of the determination in step S150is NO, that is, when the present claw tip position Pst of the bucket15is within the work area7but the demanded claw tip position Pest is outside the work area7, the work type is set to “target leaving work” which indicates that the position of the bucket15is moving from the inside of the work area7towards the outside of the work area7(step S152). The processing is then ended.

In addition, when a result of the determination in step S140is NO, that is, when the present claw tip position Pst of the bucket15is outside the work area7, whether or not the demanded claw tip position Pest is outside the work area7is next determined on the basis of the result of the computation in step S130(step S160).

When a result of the determination in step S160is YES, that is, when both the present claw tip position Pst and the demanded claw tip position Pest of the bucket15are outside the work area7, the work type indicating the state of the work of the hydraulic excavator1is set to “extra-target work” which indicates that work is being performed outside the work area7(step S161). The processing is then ended.

In contrast, when the result of the determination in step S160is NO, that is, when the present claw tip position Pst of the bucket15is outside the work area7but the demanded claw tip position Pest is within the work area7, the work type is set to “target approaching work” which indicates that the position of the bucket15is approaching the target surface5within the work area7from the outside of the work area7(step S162). The processing is then ended.

In the work tool state determination processing, the work tool state, which is the classification indicating the state of the bucket15(work tool), is set on the basis of the posture (angle) of the bucket15with respect to the target surface5and a load on the front work implement12.

FIG.13is a flowchart illustrating the details of the work tool state determination processing.

Incidentally, in the work tool state determination processing, the work tool state includes both a filling state of the bucket15(determination result indicating whether or not the bucket15is filled with soil) and a coincidence state of the bucket15(determination result indicating whether or not the bottom surface of the bucket is close to a state of coinciding with the target surface Each of the states is stored independently.

Incidentally, as the work tool state, a work tool state at a time of a previous processing cycle is taken over and stored. Here, it is assumed that, as initial values, the filling state is a “soil unfilled state” and the coincidence state is a “posture coincidence state,” for example.

As illustrated inFIG.13, in the work tool state determination processing, the controller23first determines whether or not a bottom pressure Pam of the arm cylinder18is lower than a threshold value Pth_am determined in advance and the work tool state (filling state) is the “soil unfilled state” which indicates a state in which no soil is present within the bucket15, on the basis of the sensing result from the pressure sensor33and the stored contents of the work tool state (filling state) (step S200).

When a result of the determination in step S200is YES, that is, when the bottom pressure Pam of the arm cylinder18is higher than the threshold value Pth_am and the work tool state (filling state) is the “soil unfilled state,” an excavation start flag indicating that the excavating operation is started is set to “ON” (step S210).

FIG.14is a diagram illustrating a result of sensing of the bottom pressure of the arm cylinder as an example of the sensing result from the pressure sensor.

In the excavating operation by the hydraulic excavator1, the arm14is driven in a crowding direction, that is, the arm cylinder18is extended. Hence, as illustrated inFIG.14, the bottom pressure Pam of the arm cylinder18is high during excavation. Therefore, it can be determined that the excavating operation is started, when the bottom pressure Pam of the arm cylinder18becomes equal to or higher than an excavation start threshold value (Pth_am). That is, whether or not the excavating operation is started can be determined on the basis of the determination in step S200.

Next, when the result of the determination in step S200is NO or when the processing of step S210is ended, whether or not the bottom pressure Pam of the arm cylinder18is equal to or lower than the threshold value Pth_am determined in advance and the excavation start flag is “ON” is next determined on the basis of the sensing result from the pressure sensor33and the stored contents of the work tool state (filling state) (step S220).

When a result of the determination in step S220is YES, that is, when the bottom pressure Pam of the arm cylinder18is equal to or lower than the threshold value Pth_am and the excavation start flag is “ON,” the excavation start flag is set to “OFF,” and an excavation end flag indicating that the excavating operation is ended is set to “ON” (step S230).

When the excavating operation by the hydraulic excavator1is ended, the bottom pressure Pam of the arm cylinder18becomes low, as illustrated inFIG.14. Thus, it can be determined that the excavating operation is ended, when the bottom pressure Pam of the arm cylinder18becomes equal to or lower than the excavation start threshold value (Pth_am) after the excavating operation is started, that is, in a state in which the excavation start flag is “ON.” That is, whether or not the excavating operation is ended can be determined on the basis of the determination in step S220.

Next, when the result of the determination in step S220is NO or when the processing of step S230is ended, whether or not a bottom pressure Pbm of the boom cylinder17is higher than a threshold value Pth_bm determined in advance and an angle θst of the bottom surface of the bucket15with respect to the horizontal plane is smaller than a threshold value θth_hr determined in advance and the excavation end flag is “ON” is then determined on the basis of the sensing result from the pressure sensor32, the contents of the excavation end flag, and the computation result from the work tool position and posture computing section50(step S240). Incidentally, the angle θst can be computed as a sum of the angles θbm, θam, and θbk and an angle formed between the opening plane and the bottom surface of the bucket15.

When a result of the determination in step S240is YES, that is, when the bottom pressure Pbm of the boom cylinder17is higher than the threshold value Pth_bm and the angle θst is smaller than the threshold value th_hr and the excavation end flag is “ON,” the excavation end flag is set to “OFF,” and the work tool state (filling state) is set to a “soil filled state” which indicates that the bucket15is filled with soil (step S250).

FIG.15is a diagram illustrating a result of sensing of the bottom pressure of the boom cylinder as an example of the sensing result from the pressure sensor. In addition,FIG.16andFIG.17are diagrams of assistance in explaining the posture of the bucket.

In the transporting operation performed by the hydraulic excavator1after the excavating operation, the bucket15is filled with soil, and therefore, the weight of the bucket15is increased. Thus, as illustrated inFIG.15, it can be determined that the bucket15is in a state of being filled with soil, when the bottom pressure Pbm of the boom cylinder17supporting the weight of the whole of the front work implement12including the bucket15is increased and the bottom pressure Pbm of the boom cylinder17becomes equal to or more than a soil filling determination threshold value (Pt_bm). In addition, in the soil transporting operation, as illustrated inFIG.17, the opening plane of the bucket15needs to be close to the horizontal. That is, it can be determined that the soil transporting operation is started, when the bottom pressure Pbm of the boom cylinder17is high, when the opening plane of the bucket15is close to the horizontal, and when the excavating operation is ended (the excavation end flag is “ON”). That is, whether or not the transporting operation is started can be determined on the basis of the determination in step S240.

Next, when the result of the determination in step S240is NO or when the processing of step S250is ended, whether or not the angle θst of the bottom surface of the bucket15with respect to the horizontal plane is equal to or higher than the threshold value θth_hr determined in advance is then determined on the basis of the computation result from the work tool position and posture computing section50(step S260).

When a result of the determination in step S260is YES, that is, when the opening plane of the bucket15is not horizontal, the work tool state (filling state) is set to the “soil unfilled state,” which indicates that the bucket15is not filled with soil (step S270).

As illustrated inFIG.17, when the opening plane of the bucket15is not horizontal, the contents of the bucket drop therefrom, and therefore, it can be determined that no soil is present within the bucket15. That is, whether or not the bucket15contains no soil can be determined on the basis of the determination in step S260.

Next, when the result of the determination in step S260is NO or when the processing of step S270is ended, whether or not the angle θst of the bottom surface of the bucket15with respect to the horizontal plane is smaller than a sum of an angle θtgt formed between the target surface5and the horizontal plane and a threshold value θth determined in advance and the angle θst is larger than a difference (θtgt−θth) between the angle θtgt and the threshold value θth is then determined (step S280).

When a result of the determination in step S280is YES, the work tool state (coincidence state) is set to the “posture coincidence state” which indicates that the orientations of the bottom surface of the bucket15and the target surface5substantially coincide with each other (step S281). The processing is then ended. In contrast, when the result of the determination in step S280is NO, the work tool state (coincidence state) is set to a “posture non-coincidence state” which indicates that the angle of the bottom surface of the bucket15and the angle of the target surface5do not coincide with each other (step S282). The processing is then ended.

As illustrated inFIG.16, when the angle θst of the bottom surface of the bucket15with respect to the horizontal plane falls within the range of the threshold value θth set in advance with respect to the angle θtgt formed between the target surface5and the horizontal plane, it can be determined that the orientations of the bottom surface of the bucket15and the target surface5substantially coincide with each other. That is, whether or not the orientations of the bottom surface of the bucket15and the target surface5coincide with each other can be determined on the basis of the determination in step S280.

Next, operation form invocation processing in the work tool operation form invoking section55will be described. The work tool operation form invoking section55performs operation form readout processing for reading an operation form stored in the work tool operation form storage section53, on the basis of a processing result of the working status determination processing (the work type determination processing and the work tool state determination processing) in the working status determining section54. Incidentally, the operation form readout processing in the controller23is repeatedly performed at intervals of a unit processing time (for example, a sampling time) determined in advance.

FIG.18is a flowchart illustrating the details of the operation form readout processing.

As illustrated inFIG.18, in the operation form readout processing, the controller23first determines whether or not the work type determined by the work type determination processing in the working status determining section54has changed from the extra-target work to the target approaching work (step S300). In addition, when a result of the determination in step S300is YES, whether or not the work type determined by the work type determination processing in the working status determining section54is the posture coincidence state is then determined (step310).

When a result of the determination in step S310is YES, that is, when the work type has changed to the target approaching work and the work tool state is the posture coincidence state, the “bucket posture maintaining mode” is read out from the work tool operation form storage section53and set as an operation form (step S320).

A state in which the work type has changed from the extra-target work to the target approaching state can be considered to be a state in which the bucket15is to enter the work area7, and can thus be determined to be a working status in which the operator of the hydraulic excavator1intends to make a transition to the work in the vicinity of the target. In addition, at this time, when the work tool state is the posture coincidence state, it can be determined that it is a working status in which the bottom surface of the bucket15is to coincide with the target surface5. That is, it is possible to determine, on the basis of the determinations in steps S300and S310, whether or not an assisting operation appropriate for the present working status is the “bucket posture maintaining mode,” which is the operation form in which the angle of the bucket15is controlled to make the bottom surface of the bucket15coincide with the target surface5.

Next, when the result of the determination in step S300or S310is NO or when the processing of step S320is ended, whether or not the work type has changed to the intra-target work is then determined (step S330). In addition, when a result of the determination in step S330is YES, whether or not the work tool state is the soil filled state is determined (step S340).

When a result of the determination in step S340is NO, that is, when the work type has changed to the intra-target work and the work tool state is not the soil filled state, the “claw tip position designating mode” is read out from the work tool operation form storage section53and set as an operation form (step S341).

A state in which the work type has changed to the intra-target work can be considered to be a state in which the work is being performed within the work area7. In addition, at this time, when the work tool state is not the soil filled state, it can be determined that it is a working status in which excavation is to be performed within the work area. That is, it is possible to determine, on the basis of the determinations in steps S330and S340, whether or not an assisting operation appropriate for the present working status is the “claw tip position designating mode,” which is the operation form in which the position of the bucket15is controlled to make the claw tip of the bucket15coincide with the target surface5. Incidentally, when the result of the determination in step S340is YES, that is, when the work tool state is the soil filled state, it can be estimated that the work of strewing soil, such as laying and leveling of the soil, is performed within the work area7, and therefore, such control that makes the claw tip of the bucket15coincide with the target surface5is not performed.

Next, when the result of the determination in step S330is NO, when the result of the determination in step S340is YES, or when the processing of step S341is ended, whether or not the work type has changed to the target leaving work is then determined (step S350). When a result of the determination in step S350is YES, the bucket posture maintaining mode is cancelled (step S360), and the claw tip position designating mode is cancelled (step S370).

A state in which the work type has changed to the target leaving work is a state in which the bucket15is to leave the work area7, and can be determined to be a working status in which the operator of the hydraulic excavator1intends to make a transition to the work at a place separated from the target surface5. That is, it is possible to determine, on the basis of the determination in step S350, whether or not to cancel the assisting operation for work on the target surface5.

Next, when the result of the determination in step S350is NO or when the processing of steps S360and S370is ended, whether or not the work type is one of the extra-target work and the intra-target work is then determined (step S380). In addition, when a result of the determination in step S380is YES, whether or not the work tool state has changed to the soil filled state is next determined (step S390).

When a result of the determination in step S390is YES, that is, when the work type is the extra-target work or the intra-target work and the work tool state has changed to the soil filled state, the “bucket horizontal maintaining mode” is read out from the work tool operation form storage section53and set as an operation form (step S400).

A state in which the work tool state has changed to the soil filled state at a position separated from the target surface5in the case of the extra-target work or within the work area in the case of the intra-target work can be determined to be a working status in which transportation is started after soil is excavated. That is, it is possible to determine, on the basis of the determinations in steps S380and S390, whether or not to set the “bucket horizontal maintaining mode,” which is the operation form in which the angle of the bucket15is controlled so as to hold the opening plane of the bucket15horizontal.

Next, when the result of the determination in step S380or S390is NO or when the processing of step S400is ended, whether or not the work tool state is the soil filled state is next determined (step S410). In addition, when a result of the determination in step S410is YES, whether or not the work type has changed to one of the intra-target work and the extra-target work is next determined (step S420).

When a result of the determination in step S420is YES, that is, when the work tool state is the soil filled state and the work type is the intra-target work or the extra-target work, the bucket horizontal mode is cancelled (step S430). The processing is then ended. In addition, the processing is ended when the result of the determination in either step S410or S420is NO.

A state in which the work tool state is the soil filled state and the work type has changed to the intra-target work or the extra-target work can be determined to be a working status in which soil has been transported to a position separated from the target surface5within the work area7or to above the target surface5outside the work area7. That is, it is possible to determine, on the basis of the determinations in steps S410and S420, whether or not to cancel the bucket horizontal maintaining mode to enable a soil discharge operation.

Next, computation processing in the work tool operation correction amount computing section56will be described. The work tool operation correction amount computing section56computes a control amount (operation correction amount) to perform the assisting operation, on the basis of the computation result from the work tool position and posture computing section50, the settings made by the work target setting section51, the work type invoked by the work tool operation form invoking section55, and the operation state of the operation button25.

FIG.19is a diagram of assistance in explaining a method of computing a bucket assisting operation amount and illustrates, in perspective, the relation between the bucket and the target surface.

The work tool operation correction amount computing section56first calculates a point Pn on the target surface5that is the closest to a distal end position Pst of the bucket15, by using (Equation 9) below.

Incidentally, “|n|” in the above (Equation 9) represents the norm of a vector.

In addition, an angular difference dθ between the angle θst of the bottom surface of the bucket15with respect to the horizontal plane and the angle of the target surface5or the horizontal is computed. With this, a movement correction speed vadj for the distal end position Pst of the bucket15is calculated by (Equation 10) below by using predetermined gains Kadjp and Kadjθ.

Then, each swing angular velocity of the hydraulic excavator1is computed by converting the movement correction speed vadj. In addition, when a Jacobian matrix J corresponding to the relations between (Equation 1) to (Equation 3) is used, a correction swing angular velocity ωadj of the hydraulic excavator1can be expressed as in (Equation 11) and (Equation 12) below by using the speed vadj of the distal end position Pst of the bucket15.

Then, the work tool operation correction amount computing section56selects an actuator(s) to which ωadj is to be applied, on the basis of the setting made by the work tool operation form invoking section55. For example, in the bucket horizontal maintaining mode or the bucket posture maintaining mode for correcting the posture of the bucket only a component of ωadj related to rotation of the bucket15is extracted. In the claw tip position designating mode, only components of ωadj related to rotation of the boom13and the arm14are extracted. In addition, ωadj is set to 0 (zero) when the operation button is depressed, so that the assisting operation is forcibly prevented from being performed when the hydraulic excavator1performs an operation different from an intention of the operator.

The work implement control amount computing section57computes and outputs current commands (driving signals) for driving the control valves34,35,36, and37, the hydraulic pump39, and the bleed-off unit43, on the basis of an operation instruction amount indicated by the operation signal output from the control lever24and of the correction swing angular velocity ωadj output by the work tool operation correction amount computing section56. That is, the work implement control amount computing section57converts the operation amount of the control lever24into a swing angular velocity command value ωope of the hydraulic excavator1which is proportional to the operation amount, and calculates a current command Cctrl by (Equation 13) below by using the correction swing angular velocity ωadj and a predetermined conversion map Kctrl(q) of swing angular velocity and the current command.

Next, a method of displaying the state of the assisting operation to the operator will be described.

FIG.20is an external view illustrating a bucket state display during the assisting operation. The controller23displays a bucket state display97and an excavator state display98as well as an assisting operation contents display99on the display input device26. The bucket state display97includes a front view and a side view of the bucket15for indicating the positional relation between the bucket15and the target surface5. The excavator state display98includes a bird's-eye view of the hydraulic excavator1for indicating the positional relation between the hydraulic excavator1and the target surface5. The controller23thus notifies a result of the estimation of the working status and the contents of the assisting operation to the operator of the hydraulic excavator1. In such a manner, the working status of the hydraulic excavator1is determined, and the assisting operation form is changed to control the assisting operation. Accordingly, it is possible to perform an appropriate operation of the bucket according to the work contents and the work target of the hydraulic excavator1, thereby improving the work accuracy.

Effects of the present embodiment configured as described above will be described.

In order to achieve appropriate operation assistance in MC, it is necessary to switch between the enabling and disabling of MC according to the work contents and a work environment and set appropriate assistance contents. In the conventional technology, the operator alternately selects the enabling and disabling of the automatic control by operating the operating member provided to the control lever. In such a case, however, if the operator forgets to operate the operating member, work may be performed while the automatic control is disabled. Consequently, excavation may possibly be performed beyond a design surface. In addition, when the work contents are set through an operation made by the operator, if the operator sets the work contents or the assistance contents erroneously, the work device may not be set in a desired posture. As a result, the work device may erroneously excavate a construction surface excessively or drop the soil transported to the construction surface, so that sufficient work accuracy may not be obtained. For example, in work of shaping the terrain profile of a construction object into a desired shape, a shaping operation and a transporting operation may alternately be performed. In the shaping operation, while the position and posture of the bucket are adjusted, the hydraulic excavator1excavates soil with the bottom surface of the bucket made to coincide with the construction surface to be shaped. In the transporting operation, while the bucket opening plane is kept parallel to the horizontal plane so as not to drop soil onto the shaped surface, the hydraulic excavator1moves the soil that becomes a surplus during the shaping. In the shaping work where the automatic control is performed such that the posture of the bucket corresponds to a predetermined angle, if the operating member is operated erroneously and the automatic control of the shaping operation and the transporting operation is performed conversely, the bucket may not be set in a desired posture. As a result, the hydraulic excavator1may erroneously excavate the construction surface excessively or drop the transported soil onto the construction surface, so that sufficient work accuracy may not be obtained. That is, in such a case as described above, an appropriate MC operation may be unable to be performed, and thus, the work accuracy may be decreased.

On the other hand, in the present embodiment, the work machine (hydraulic excavator1) includes the lower track structure10; the upper swing structure11that is swingable with respect to the lower track structure10; the articulated front work implement12that is attached to the upper swing structure11and includes a plurality of front implement members (the boom13, the arm14, and the bucket rotatably coupled together; the operation device (control lever24) that outputs operation signals for driving the upper swing structure11and the front work implement12according to amounts of operations made by the operator; a plurality of front work implement actuators (the boom cylinder17, the arm cylinder18, and the bucket cylinder19) that individually drive the plurality of front implement members on the basis of driving signals generated according to the operation signals output from the operation device; the swing actuator (swing hydraulic motor16) that swing-drives the upper swing structure11on the basis of the operation signal output from the operation device; the posture information sensor (inertial measuring devices27to that senses posture information as information regarding the postures of the upper swing structure11and the front work implement12; and the controller (controller23) that performs the operation correction control to output a driving signal to at least one of the plurality of front work implement actuators such that the front work implement12is set in a predetermined position or posture on the predetermined target surface5and within one area with respect to the target surface, on the basis of the operation signals output from the operation device and the posture information sensed by the posture information sensors. The work machine further includes the load information sensor (pressure sensors32and33) that senses load information as information regarding a load on at least one of the plurality of front work implement actuators, and a work area setting device (display input device26) that sets the work area7over the predetermined target surface5. The controller determines a working status indicating a status related to the present work of the work machine, on the basis of the operation signals output from the operation device, the posture information sensed by the posture information sensor, the load information sensed by the load information sensor, and the work area set by the work area setting device, decides an operation form indicating contents of an operation in the operation correction control of the front work implement, from a plurality of operation forms set in advance, according to the determined working status, and performs the operation correction control such that the front work implement moves according to the operation form. It is thus possible to perform an appropriate assisting operation in machine control and consequently improve the work accuracy.

Second Embodiment

A second embodiment of the present invention will be described with reference toFIG.21andFIG.22.

The present embodiment represents a case where a rotary tilt bucket44is used in place of the bucket15used as a work tool in the first embodiment.

FIG.21is a diagram illustrating the rotary tilt bucket on an enlarged scale. InFIG.21, members similar to those of the first embodiment are identified by the same reference signs, and description thereof will be omitted.

InFIG.21, the rotary tilt bucket44is provided to the distal end of the arm14, which is a front implement member of the front work implement12, rotatably about a rotational axis A4. In addition, the rotary tilt bucket44is rotatable about each of two rotational axes, i.e., a rotary rotational axis A6and a tilt rotational axis A5, which are perpendicular to the rotational axis A4with respect to the front work implement12. The rotary rotational axis A6and the tilt rotational axis A5are perpendicular to each other. The rotary tilt bucket44includes a rotation motor46as a rotary actuator that rotationally drives the rotary tilt bucket44about the rotational axis A6, and tilt cylinders45aand45bas tilt actuators that rotationally drive the rotary tilt bucket44about the rotational axis A5. That is, the rotary tilt bucket44is rotated about the rotational axis A4at the distal end of the arm14by the bucket cylinder19, rotated about the rotational axis A5orthogonal to the rotational axis A4by the tilt cylinders45aand45bat a coupling member of the rotary tilt bucket44, and rotated about the rotational axis A6orthogonal to the rotational axes A4and A5by the rotation motor46at a coupling member of the rotary tilt bucket44.

A rotational angle meter47which is a posture information sensor is attached to the rotary tilt bucket44and is capable of sensing a rotational angle (rotary angle) of the rotary tilt bucket44about the rotational axis A6. In addition, an inertial measuring device30which is a posture information sensor can sense a rotational angle (tilt angle) about the rotational axis A5in addition to a rotational angle about the rotational axis A4. That is, the orientation of the rotary tilt bucket44can be calculated on the basis of sensing results from the inertial measuring device30and the rotational angle meter47.

In such a work machine, the position and posture of the rotary tilt bucket can be adjusted independently with three degrees of freedom with respect to the machine body of the hydraulic excavator1, so that complex operations can be performed. With such a hydraulic excavator1, the operation form of the work tool in the work tool operation form setting section52is not limited to the posture of the bucket15and the position of the claw tip as illustrated in the first embodiment, and, for example, a plurality of postures of the rotary tilt bucket44about the A5axis and the A6axis can be set individually, together with the direction in which the rotary tilt bucket44moves and the posture of the rotary tilt bucket44about the A4axis.

FIG.22is an overview diagram illustrating an example of work of the hydraulic excavator provided with the rotary tilt bucket.

FIG.22illustrates an example of laying and leveling work. In the laying and leveling work, the hydraulic excavator1slightly drops the soil scooped from the stock4onto a ground at the bottom of a retaining wall with the use of the rotary tilt bucket44, and thus uniformly strews the soil. At this time, in order to strew the soil uniformly in the vicinity of a vertical wall surface, it is preferable that the target surface5be set at an appropriate distance from the wall surface and that the rotary tilt bucket44be movable in a state of facing the target surface5while turning in a direction perpendicular to a direction in which the rotary tilt bucket44is facing the target surface5. The operation form of the work tool in the work tool operation form setting section52may be set as described above.

In addition, the working status determining section54may determine the working status by a different method. For example, the working status may be computed by using a reaction force acting on the rotary tilt bucket44, on the basis of the posture of the front work implement12and thrusts of the respective cylinders, the thrusts being computed on the basis of the pressures of the boom cylinder17, the arm cylinder18, and the bucket cylinder19. Needless to say, a result of estimation of a payload of the soil within the rotary tilt bucket44may also be used.

In addition, the combination of the work area and the work tool operation form that are set by the work target setting section51and the work tool operation form setting section52is not limited to only one combination as in the first embodiment. For example, as in the laying and leveling work performed by the hydraulic excavator1provided with the rotary tilt bucket44illustrated inFIG.22, the work area may be set for each retaining wall, and the assisting operation may be performed in different operation forms.

Incidentally, an example has been described above in which the work implement control amount computing section57calculates the current command Cctrl by using the conversion map Kctrl(q) of the swing angular velocity and the current command. However, it is needless to say that the current command Cctrl may be computed by a different method and that the control command may be generated by using a map that uses a pressure of the hydraulic circuit or a control law of model predictive control or the like.

The other configurations are similar to those of the first embodiment.

The present embodiment configured as described above can also provide effects similar to those of the first embodiment.

It is to be noted that the present invention is not limited to the foregoing embodiments and includes various modifications and combinations of embodiments within a scope not departing from the spirit of the present invention. Further, the present invention is not limited to those including all of the configurations described in the foregoing embodiments and also includes those from which some of the configurations are omitted. In addition, a part or the whole of each of the configurations, the functions, and the like described above may be implemented by, for example, being designed in an integrated circuit or the like. Moreover, each of the configurations, the functions, and the like described above may be implemented by software causing a processor to interpret and execute a program for implementing the respective functions.

DESCRIPTION OF REFERENCE CHARACTERS

1: Hydraulic excavator3: Groove4: Stock5: Target surface6: Material7: Work area10: Lower track structure11: Upper swing structure12: Front work implement13: Boom14: Arm15: Bucket16: Swing hydraulic motor17: Boom cylinder18: Arm cylinder19: Bucket cylinder22: Operation room23: Controller24: Control lever25: Operation button26: Display input device27to30: Machine body inertial measuring device31: GNSS antenna32,33: Pressure sensor34to37: Control valve37a: Directional control valve37b: Solenoid proportional pressure reducing valve37c: Solenoid proportional pressure reducing valve39: Hydraulic pump40: Pilot pump41: Prime mover42: Hydraulic operating fluid tank43: Bleed-off unit44: Rotary tilt bucket45b: Tilt cylinder46: Rotation motor47: Rotational angle meter50: Work tool position and posture computing section51: Work target setting section52: Work tool operation form setting section53: Work tool operation form storage section54: Working status determining section55: Work tool operation form invoking section56: Work tool operation correction amount computing section57: Work implement control amount computing section90: Work target display91: Work area adjustment display92: Intra-work area bucket setting screen93: Adjustment display94: Bucket posture adjustment display95: Confirmation button96: Return button97: Bucket state display98: Excavator state display99: Assisting operation contents displayA4: Rotational axisA5: Tilt rotational axisA6: Rotary rotational axis