Target excavation surface setting device for excavation machine, recording medium therefor and display unit

[0002] The present invention relates to a target excavating-surface setting system for an excavating machine, such as a hydraulic excavator, which is employed to set work conditions of the excavating machine, a storage medium storing a target excavating-surface setting program for an excavating machine, and a display device for use in the target excavating-surface setting system.

[0003] In a hydraulic excavator, an operator operates front members, such as a boom, by associated manual control levers. There is however a difficulty for the operator to judge whether or not excavation is carried out precisely along a ditch at a predetermined depth or a slope at a predetermined gradient, just by visually observing the front operation. It is therefore known to set the depth of an excavating surface or the gradient of a slope beforehand, and to perform automatic excavation control so that the set depth or gradient is achieved. A target excavating surface must be set to perform the automatic excavation control. A monitoring apparatus for an excavating machine disclosed in JP,A 62-185932 and an excavating machine disclosed in JP,A 5-287782 are proposed as employing a two-dimensional display device for setting a target excavating surface.

[0004] In the excavating machines disclosed in JP,A 62-185932 and JP,A 5-287782, a machine body and a target excavating surface are displayed in the form of pictures on a monitor, and a depth from the machine body to the target excavating surface or a gradient of the target excavating surface is also displayed on the monitor.

[0005] Further, an excavation area setting system for area limiting excavation control in construction machines, disclosed in, e.g., JP,A 9-53253, proposes a system in which an external reference, such as a leveling string or a laser reference surface formed by a laser lighthouse installed outside a machine body, is used in combination with a hydraulic excavator, and excavation is carried out continuously over a long distance along a surface at a certain depth or gradient relative to the external reference.

[0006] In the excavation area setting system disclosed in JP,A 9-53253, a laser beam receiver is attached to a front member, and a vertical shift upon travel of the machine body is compensated for with the aid of a laser beam so that a continuous linear excavating surface is obtained. Also, in that excavation area setting system, the relationship between the machine body and a target excavating surface is set by setting the target excavating surface relative to the laser reference surface.

[0007] In the excavating machines disclosed in JP,A 62-185932 and JP,A 5-287782, however, any external reference is not used. This means that display of an external reference is neither provided nor intended.

[0008] Also, the excavation area setting system disclosed in JP,A 9-53253 has a problem that a setting error is apt to occur because the depth, set by a setting device, from the laser reference surface (external reference) to the target excavating surface is displayed just in the form of a numerical value on the monitor.

[0009] More specifically, in a system employing a laser reference surface (external reference), excavation is carried out continuously over a long distance along a surface at a predetermined depth from the external reference such as the laser reference surface and, to this end, setting of a target excavating surface must be repeated using the external reference. In order to realize precise setting, therefore, it is required that the operator can confirm and recognize not only the positional relationship between a machine body and the target excavating surface, but also the positional relationship between the laser reference surface and the target excavating surface. In the conventional system wherein only a numerical value or only the positional relationship between the machine body and the target excavating surface is displayed, it is difficult for the operator to visually recognize the positional relationship between the laser reference surface and the target excavating surface, and hence a setting error is apt to occur.

[0010] An object of the present invention is to provide a target excavating-surface setting system for an excavating machine, which can easily set a target excavating surface using an external reference when excavation is carried out continuously over a long distance along a surface at a predetermined depth, and which is less apt to cause a setting error relative to the external reference, as well as to a storage medium and a display device for use in the target excavating-surface setting system.

[0011] (1) To achieve the above object, the present invention provides a target excavating-surface setting system for an excavating machine, in which a target excavating surface is set parallel to an external reference installed outside a machine body and a front device is controlled for the target excavating surface, thereby carrying out excavation continuously along the target excavating surface, wherein the system comprises input means for setting the target excavating surface; detecting means for detecting status variables relating to a position and a posture of the front device; first computing means for computing positional relationships among the body, the external reference and the target excavating surface by using signals from the input means and the detecting means; and second computing means for executing picture processing by using the positional relationships computed by the first computing means, and producing and outputting picture signals to display the positional relationships among the body, the external reference and the target excavating surface.

[0012] With the features set forth above, the positional relationships among the external reference, the target excavating surface and the body are displayed on image display means. By looking at the display, therefore, an operator can visually confirm and recognize non only the positional relationship between the body and the target excavating surface, but also the positional relationship between the external reference and the target excavating surface, and can ascertain whether the setting conditions are proper or not. As a result, the target excavating surface can be easily set using the external reference when excavation is carried out continuously over a long distance until and along a surface at a predetermined depth and a setting error is less apt to occur.

[0013] (2) In the above (1), preferably, the first computing means comprises first means for computing the positional relationship of the body relative to the external reference by using the signals from the detecting means; and second means for computing the positional relationship between the external reference and the target excavating surface by using at least the signals from the input means.

[0014] (3) Also, in the above (1), preferably, the input means includes numerical value input means for inputting a depth from the external reference to the target excavating surface, and the first computing means comprises third computing means for computing the positional relationship between the body and the external reference by using the signals supplied from the detecting means when the front device is in a predetermined positional relationship relative to the external reference; and first setting means for setting the positional relationship between the external reference and the target excavating surface by using the signals from the numerical value input means.

[0015] (4) In the above (3), preferably, the first computing means further comprises fourth computing means for computing the positional relationship between the body and the target excavating surface by using values computed by the third computing means and a value set by the first setting means, and the second computing means comprises first transforming means for executing processing to transform the values computed by the third computing means into values on a monitor coordinate system set for a display section of a display device on the basis of the body, and to display the positional relationship between the body and the external reference on the display section; and second transforming means for executing processing to transform values computed by the fourth computing means into values on the monitor coordinate system on the basis of the body, and to display the positional relationship between the body and the target excavating surface on the display section.

[0016] (5) Further, in the above (1), the input means may include direct-teaching instructing means operated when a work implement provided as the front device is at a predetermined depth. In this case, the first computing means comprises fourth computing means for computing the positional relationship between the body and the target excavating surface by using the signals supplied from the detecting means when the direct-teaching instructing means is operated; fifth computing means for computing the positional relationship between the body and the external reference by using the signals supplied from the detecting means when the front device is in a predetermined positional relationship relative to the external reference; and sixth computing means for computing the positional relationship between the external reference and the target excavating surface by using values computed by the fourth and fifth computing means.

[0017] (6) In the above (5), preferably, the first computing means further comprises seventh computing means for computing the positional relationship between the body and the target excavating surface by using values computed by the fifth and sixth computing means, and the second computing means comprises first transforming means for executing processing to transform the values computed by the fifth computing means into values on a monitor coordinate system set for a display section of a display device on the basis of the body, and to display the positional relationship between the body and the external reference on the display section; and second transforming means for executing processing to transform the values computed by the fourth computing means or the seventh computing means into values on the monitor coordinate system on the basis of the body, and to display the positional relationship between the body and the target excavating surface on the display section.

[0018] (7) Further, in the above (1), preferably, the input means includes means for setting a gradient of the external reference, the first computing means computes the positional relationships among the body, the external reference and the target excavating surface, including a set value of the gradient, and the second computing means produces the picture signals for displaying the external reference and the target excavating surface depending on the gradient.

[0019] (8) Still further, in the above (1), the target excavating-surface setting system further comprises a display device for displaying, in accordance with the computed positional relationships, a picture representing the body and straight lines representing respectively the external reference and the target excavating surface by using the picture signals outputted from the second computing means.

[0020] (9) Still further, in the above (1), preferably, the first computing means is disposed in a first control unit, and the second computing means is disposed in a second control unit separate from the first control unit.

[0021] (10) To achieve the above object, the present invention also provides a storage medium storing a target excavating-surface setting program for an excavating machine, in which a target excavating surface is set parallel to an external reference installed outside a machine body and a front device is controlled for the target excavating surface, thereby carrying out excavation continuously along the target excavating surface, wherein the program operates a computer to execute the steps of computing positional relationships among the body, the external reference and the target excavating surface by using a signal from input means for setting the target excavating surface and signals from detecting means for detecting status variables relating to a position and a posture of the front device; and executing picture processing by using the computed positional relationships for producing and outputting picture signals to display the positional relationships among the body, the external reference and the target excavating surface.

[0022] (11) To achieve the above object, the present invention further provides a display device for use in a target excavating-surface setting program for an excavating machine, in which a target excavating surface is set parallel to an external reference installed outside a machine body and a front device is controlled for the target excavating surface, thereby carrying out excavation continuously along the target excavating surface, wherein the display device comprises a display section for taking in picture signals representing previously computed positional relationships among the body, the external reference and the target excavating surface, and displaying a picture representing the body and straight lines representing respectively the external reference and the target excavating surface in accordance with the previously computed positional relationships.

[0023] FIG. 1 is a diagram showing a target excavating-surface setting system for an excavating machine according to a first embodiment of the present invention, along with a hydraulic drive system of a hydraulic excavator.

[0024] FIG. 2 is a view showing an external appearance of a hydraulic excavator to which the present invention is applied, along with a laser lighthouse and a laser reference surface formed by the laser lighthouse.

[0025] FIG. 3 is a diagram showing the target excavating-surface setting system in FIG. 1, along with a hardware configuration of a control unit.

[0026] FIG. 4 is a diagram showing the target excavating-surface setting system in FIG. 1, along with processing functions of the control unit.

[0027] FIG. 5 is a representation showing a construction of a setting device in FIG. 1.

[0028] FIG. 6 is a block diagram showing processing functions of a setting/display processing section, shown in FIG. 4, based on a method of inputting numerical values.

[0029] FIG. 7 is an explanatory view showing dimensions of components of the hydraulic excavator to which the target excavating-surface setting system for the excavating machine according to the present invention is applied, a coordinate system used, and the relationship among a machine body, a laser reference surface and a target excavating surface.

[0030] FIG. 8 is an explanatory view of a coordinate system for use in a display device (monitor) according to the first embodiment of the present invention.

[0031] FIG. 9 is an explanatory view of a first display example in the display device of the target excavating-surface setting system of the present invention.

[0032] FIG. 10 is an explanatory view showing an excavating manner using the display device and the target excavating-surface setting system of the present invention.

[0033] FIG. 11 is a block diagram showing processing functions of a setting/display processing section based on the method of inputting numerical values, which are used in a target excavating-surface setting system for an excavating machine according to a second embodiment of the present invention.

[0034] FIG. 12 is an explanatory view of a coordinate system for use in a display device (monitor) according to the second embodiment of the present invention.

[0035] FIG. 13 is a block diagram showing processing functions of a setting/display processing section based on the method of inputting numerical values, which are used in a target excavating-surface setting system for an excavating machine according to a third embodiment of the present invention.

[0036] FIG. 14 is an explanatory view of a coordinate system for use in a display device (monitor) according to the third embodiment of the present invention.

[0037] FIG. 15 is a block diagram showing processing functions of a setting/display processing section based on a direct teaching method, which are used in a target excavating-surface setting system for an excavating machine according to a fourth embodiment of the present invention.

[0038] FIG. 16 is a block diagram showing processing functions of a setting/display processing section based on the direct teaching method, which are used in a target excavating-surface setting system for an excavating machine according to a fifth embodiment of the present invention.

[0039] FIG. 17 is a block diagram showing processing functions of a setting/display processing section based on the direct teaching method, which are used in a target excavating-surface setting system for an excavating machine according to a sixth embodiment of the present invention.

[0040] FIG. 18 is an explanatory view of a second display example in the display device of the target excavating-surface setting system of the present invention.

[0041] FIG. 19 is an explanatory view of a third display example in the display device of the target excavating-surface setting system of the present invention.

[0042] FIG. 20 is a diagram showing a target excavating-surface setting system for an excavating machine according to still another embodiment of the present invention, along with processing functions of a control unit.

[0043] FIG. 21 is a block diagram showing processing functions of a setting processing section in the control unit and a display processing unit in FIG. 20.

[0044] Embodiments of the present invention will be described below with reference to the drawings.

[0045] FIGS. 1 to 10 show a target excavating-surface setting system for an excavating machine according to a first embodiment of the present invention, including a display device for use therein. This embodiment represents the case where the present invention is applied to a hydraulic excavator.

[0046] In FIG. 1, the hydraulic excavator comprises a hydraulic pump 2; a plurality of hydraulic actuators including a boom cylinder 3a, an arm cylinder 3b, a bucket cylinder 3c, a swing motor 3dand left and right travel motors 3e, 3f, which are driven by a hydraulic fluid from the hydraulic pump 2; a plurality of control lever units 4a-4fprovided respectively corresponding to the hydraulic actuators 3a-3f; a plurality of flow control valves 5a-5fcontrolled by the plurality of control lever units 4a-4fand controlling respective flow rates of the hydraulic fluid supplied to the hydraulic actuators 3a-3f; a relief valve 6 which is opened when the delivery pressure of the hydraulic pump 2 exceeds a preset value; and a control unit 9 for receiving operational signals from the control lever units 4a-4fand controlling the flow control valves 5a-5f. These components constitute a hydraulic drive system for driving driven members of the hydraulic excavator.

[0047] In this embodiment, the control lever units 4a-4fare electrical lever units for outputting electrical signals as the operational signals, and the flow control valves 5a-5fare electro-hydraulic converting means for converting the electrical signals into pilot pressures, e.g., electrically or hydraulically operated valves each having proportional solenoid valves provided at opposite ends. The control unit 9 receives the operational signals from the control lever units 4a-4fand produces flow-control-valve driving signals corresponding to the received signals, thereby driving and controlling the flow control valves 5a-5f.

[0048] As shown in FIG. 2, the hydraulic excavator is made up of a multi-articulated front device 1A comprising a boom 1a, an arm 1band a bucket (work implement) 1cwhich are each rotatable in the vertical direction, and a machine body 1B comprising an upper swing structure 1dand a lower travel structure 1e. The boom 1aof the front device 1A is supported at its base end to a front portion of the upper swing structure 1d.

[0049] The boom 1a, the arm 1b, the bucket 1c, the upper swing structure 1d, and the lower travel structure 1e, shown in FIG. 2, are driven respectively by the boom cylinder 3a, the arm cylinder 3b, the bucket cylinder 3c, the swing motor 3d, and the left and right travel motors 3e, 3fshown in FIG. 1. The operations of these members are instructed by the control lever units 4a-4f.

[0050] The target excavating-surface setting system according to this embodiment is installed in the hydraulic excavator constructed as described above. The target excavating-surface setting system comprises a setting device 7 used for setting a target excavating surface that should be linearly finished; angle sensors 8a, 8band 8cprovided at pivots about which the boom 1a, the arm 1band the bucket 1care rotated, respectively, and detecting rotational angles of the boom 1a, the arm 1band the bucket 1cas status variables relating to the position and the posture of the front device 1A; a laser beam receiver 10battached to a lateral surface of the arm 1band receiving a laser beam formed by the laser lighthouse 10ainstalled outside the body; a two-dimensional display monitor (display device) 12 mounted within a cab at a corner obliquely in front of an operator seat; and later-described processing functions incorporated in the control unit 9. The laser beam formed by the laser lighthouse 10aprovides a laser reference surface (external reference) R.

[0051] FIG. 3 shows a hardware configuration of the control unit 9. The control unit 9 comprises an input section 91, a central processing unit (CPU) 92 constituted by a microcomputer, a read only memory (ROM) 93, a random access memory (RAM) 94, and an output section 95. The input section 91 receives operational signals from the control lever units 4a-4f, instruction signals (setting signal and main switch signal) from the setting device 7, angle signals from the angle sensors 8a, 8band 8c, and a laser beam input signal from the laser beam receiver 10b, and then executes A/D conversion of those signals. The ROM 93 is a storage medium in which a control program (described below) is stored. The CPU 92 executes predetermined processing of the signals taken in through the input section 91 in accordance with the control program stored in the ROM 93. The RAM 94 temporarily stores numerical values used in computation. The output section 95 produces output signals depending on processing results of the CPU 92, outputs the produced signals to the flow control valves 5a-5f, and displays the body 1B, the laser reference surface R and the target excavating surface on the monitor 12.

[0052] FIG. 4 is a functional block diagram showing outline of the control program stored in the ROM 93 of the control unit 9. The control unit 9 comprises a setting/display processing section 11 for setting the target excavating surface and executing processing for display on the monitor 12, and an excavation control section 14 for carrying out area limiting excavation control.

[0053] The setting/display processing section 11 receives the detection signals from the angle sensors 8a, 8band 8c, the signal from the setting device 7 and the signal from the laser beam receiver 10b, and computes the target excavating surface and the laser reference surface based on the x-z coordinate system (described later) set for the body 1B of the hydraulic excavator, thereby setting the target excavating surface. Also, the setting/display processing section 11 executes a combining process for executing coordinate transform of the target excavating surface and the laser reference surface into values on the x_m−z_mcoordinate system (described later) that is fixedly set for an illustration of the hydraulic excavator displayed on the two-dimensional display monitor 12, and then displaying both the target excavating surface and the laser reference surface in a superimposed relation to the illustration of the hydraulic excavator. Further, the setting/display processing section 11 executes a combining process for displaying numerical values such as data representing the distance between the target excavating surface and the laser reference surface, the gradient thereof, and the distance from the laser reference surface to the bucket in the depth direction.

[0054] The excavation control section 14 executes processing to create command signals for the flow control valves 5a-5_fso as to carry out known area limiting excavation control in accordance with the target excavating surface set by the setting/display processing section 11.

[0055] The setting device 7 comprises, as shown in FIG. 5, operating means, e.g., switches disposed on a control panel or a grip, and indicators 7f, 7g, the switches including an up-key 7aand a down-key 7bfor setting the depth from the laser reference surface R, an up-key 7cand a down-key 7dfor setting the gradient, and a direct teaching button 7e. In the case of using a method of inputting numerical values, the depth from the laser reference surface R can be set by operating the up-key 7aand the down-key 7b, and the setting result is indicated on the indicator 7f. In the case of using a direct teaching method, when the direct teaching button 7eis operated, the target excavating surface relative to the body 1B at that time is computed and set, and the bucket position relative to the laser reference surface R is computed and set as the depth from the laser reference surface. Also, in either case, the gradient of the laser reference surface and the target excavating surface can be set by operating the up-key 7cor the down-key 7d, and the setting result is indicated on the indicator 7g. The setting device 7 outputs, to the setting/display processing section 11, a direct teaching signal, an excavating depth signal and a gradient signal, which are related to the excavating surface and entered by the operator.

[0056] The processing functions of the setting/display processing section 11 will now be described with reference to FIG. 6. These processing functions correspond to the method of inputting numerical values and to the case where transform into monitor coordinates is carried out on the basis of the body 1B of the hydraulic excavator.

[0057] FIG. 6 represents, in the form of a block diagram, the processing functions of the setting/display processing section 11. The setting/display processing section 11 includes various functions executed by a section 11afor computing bucket prong-end coordinates; a section 11bfor computing the positional relationship between the body and the laser reference surface; a section 11cfor storing the positional relationship (depth) between the laser reference surface and the target excavating surface; a section 11dfor computing and storing the positional relationship between the body and the target excavating surface; a computing section 11efor transform of the positional relationship between the body and the laser reference surface into monitor coordinates; a computing section 11ffor transform of the positional relationship between the body and the target excavating surface into monitor coordinates; a computing section 11gfor producing a picture of the laser reference surface; a computing section 11hfor producing a picture of the target excavating surface; a computing section 11ifor display of the setting values; and a computing section 11jfor producing a picture of the body.

[0058] The section 11afor computing bucket prong-end coordinates computes, on the basis of the x-z coordinate system set for the body 1B and the dimensions of the respective components shown in FIG. 7, as well as of the detection signals from the angle sensors 8a, 8band 8c, coordinate values (Pvx, Pvz) of the bucket prong end on the x-z coordinate system from the following formulae (1) and (2)

[0059] Pvx=LV×cos(αB+αA+αV)+LA×cos(αB+αA)+LB×cos αB+LF1  (1)

[0060] Pvz=−LV×sin(αB+αA+αV)−LA×sin(αB+αA)−LB×sin αB+LF2  (2)

[0061] LV: bucket length (distance between bucket rotation center and bucket prong end)

[0062] LA: arm length (distance between arm rotation center and bucket rotation center)

[0063] LB: boom length (distance between boom rotation center and arm rotation center)

[0064] LF1: x-coordinate value of boom rotation center on x-z coordinate system

[0065] LF2: z-coordinate value of boom rotation center on x-z coordinate system

[0066] αB: boom rotational angle

[0067] αA: arm rotational angle

[0068] αV: bucket rotational angle

[0069] Herein, the x-z coordinate system is an orthogonal coordinate system with the origin set at a predetermined position of the body 1B of the hydraulic excavator, e.g., the center of a bottom surface of the body 1B. Also, the target excavating surface is denoted by T in FIG. 7.

[0070] The section 11bfor computing the positional relationship between the body and the laser reference surface computes a linear equation of the laser reference surface R on the x-z coordinate system from both coordinate values (PLx, PLz) of the laser beam receiver 10bon the x-z coordinate system resulted when the laser beam receiver 10breceives the laser beam, and a gradient β set by the setting device 7.

[0071] Herein, the coordinate values (PLx, PLz) of the laser beam receiver 10bon the x-z coordinate system resulted when the laser beam receiver 10breceives the laser beam is computed from the following formulae (1A) and (2A), as with the above formulae (1) and (2), based on the dimensions of the respective components and the detection signals from the angle sensors 8a, 8b:

[0072] PLx=LF×cos(αB+αA−αL)+LB×cos αB+LF1  (1A)

[0073] PLz=−LF×sin(αB+αA−αL)+LB×sin αB+LF2  (2A)

[0074] LF: distance between arm rotation center and laser beam receiver 10b

[0075] αL: attachment angle of laser beam receiver relative to straight line connecting arm rotation center and bucket rotation center

[0076] Also, since a linear equation of the laser reference surface R on the x-z coordinate system is represented by a straight line passing the coordinate values (PLx, PLz) and having the gradient β, it is expressed by the following formula (3):

[0077] z=tan β·x+(PLz−tan β·PLx)  (3)

[0078] The section 11cfor storing the positional relationship (depth) between the laser reference surface and the target excavating surface stores a dept setting value Ld set by the setting device 7 relative to the laser reference surface R.

[0079] The section 11dfor computing and storing the positional relationship between the body and the target excavating surface computes a linear equation of the target excavating surface T on the x-z coordinate system from the following formula (4) based on both the positional relationship between the body and the laser reference surface computed by the computing section 11band the depth setting value Ld stored in the storing section 11c. Assuming, for example, that the linear equation of the laser reference surface R is expressed by z=tan β·x+(PLz−tan β·PLx) and the depth setting value is Ld, the linear equation of the target excavating surface T is expressed by:

[0080] z=tan β·x+(PLz−tan β·PLx)+Ld  (4)

[0081] The computing section lie for transform of the positional relationship between the body and the laser reference surface into monitor coordinates transforms the linear equation of the laser reference surface R. e.g., z=tan β·x+(PLz−tan β·PLx), into coordinate values on the x_m−z_mcoordinate system set for a display section 20 of the monitor 12 shown in FIG. 8. In FIG. 8, a coordinate plane of the x_m−z_mcoordinate system is constituted by a two-dimensional dot matrix, and an area defined by coordinates (x_m1, z_m1) and (x_m2, z_m2) serves as a display region. Also, an illustration 12cof the hydraulic excavator is fixedly displayed on the display section 20, and the origin Om of the x_m−z_mcoordinate system is set at the center of the bottom surface of the hydraulic excavator represented by the illustration 12cin match with the origin O of the x-z coordinate system of the body 1B.

[0082] Assuming herein that x_m1corresponds to x₁on the x-z coordinate system, a scale K is given by K=x_m1/x₁. The linear equation z=tan β·x+(PLz−tan β·PLx) of the laser reference surface is therefore expressed by the following formula on the x_m−z_mcoordinate system:

[0083] z_m=tan β·x_m+(PLz−tan βPLx)×K  (6)

[0084] The computing section 11ffor transform of the positional relationship between the body and the target excavating surface into monitor coordinates transforms, as with the computing section 11e, the linear equation of the target excavating surface T, e.g., z=tan β·x+(PLz−tan β·PLx)+Ld expressed by the above formula (4), into coordinate values on the x_m−z_mcoordinate system of the display section 20 shown in FIG. 8. Assuming a scale K=x_m1/x₁also in this case as with the computing section 11e, the linear equation of the target excavating surface T is expressed by the following formula on the x_m−z_mcoordinate system:

[0085] z_m=tan β·x_m+{(PLz−tan β·PLx)+Ld}×K  (7)

[0086] The computing section 11gfor producing a picture of the laser reference surface executes processing to produce and output a picture signal for displaying the linear equation of the laser reference surface R obtained by the computing section 11eas a straight line on the x_m−z_mcoordinate system of the display section 20. A straight line representing the laser reference surface R is then displayed on the display section 20 of the monitor 12 as indicated by a broken line 12ain FIG. 9.

[0087] The computing section 11hfor producing a picture of the target excavating surface executes processing to produce and output a picture signal for displaying a straight line representing the target excavating surface T obtained by the computing section 11fon the x_m−z_mcoordinate plane of the display section 20. A straight line representing the target excavating surface T is then displayed on the display section 20 of the monitor 12 as indicated by a solid line 12bin FIG. 9.

[0088] The computing section 11jfor producing a picture of the hydraulic excavator body executes processing to produce a picture of the body 1B of the hydraulic excavator in the form of an illustration, and processing to produce and output a picture signal for displaying the produced illustration in a fixed position on the x_m−z_mcoordinate plane of the display section 20 such that the center of the bottom surface of the hydraulic excavator is held in match with the origin Om. The illustration is then displayed on the display section 20 of the monitor 12 as indicated by 12cin FIG. 9.

[0089] The computing section 11ifor display of the setting values receives and computes data such as the gradient β of the target excavating surface T, the distance Ld between the laser reference surface R and the target excavating surface T in the depth direction, and the distance LPv from the laser reference surface R to the bucket prong end. Herein, the distance LPv is computed by the following formula (8):

[0090] LPv=Pvz−tan βPvx−(PLz−tan β·PLx)  (8)

[0091] Further, the display computing section 11iexecutes processing to produce and output a picture signal for displaying the gradient (setting gradient) β of the target excavating surface T, the distance (setting depth) Ld between the laser reference surface R and the target excavating surface T in the depth direction, and the distance (prong end depth) LPv from the laser reference surface R to the bucket prong end as numerical values on the x_m−z_mcoordinate plane of the display section 20. Those data are therefore displayed, for example, at the upper left corner in the display section 20 of the monitor 12 as indicated in FIG. 9.

[0092] As described above, the positional relationships among the body 1B, the target excavating surface T and the laser reference surface R, and the associated numerical values are displayed on the display section 20 of the monitor 12 as indicated in FIG. 9.

[0093] Procedures for setting the target excavating surface based on the method of inputting numerical values according to this embodiment and operating procedures for continuously carrying out excavation along a surface at the predetermined depth and gradient from the laser reference surface (external reference) R in accordance with the set target excavating surface will be described below with reference to FIGS. 6 and 10.

[0094] A description is first made of works for setting the target excavating surface at an excavating start position and carrying out excavation.

[0095] (Procedure 1)

[0096] First, as shown in FIG. 10, the operator operates the laser lighthouse 10aand sets the laser reference surface R parallel to the target excavating surface that is to be set.

[0097] (Procedure 2)

[0098] Then, the operator enters and sets the depth (height) Ld from the laser reference surface R to the target excavating surface T by operating the keys 7a, 7bof the setting device 7 shown in FIG. 5. With this setting operation, the storing section 11cstores the depth setting value Ld of the target excavating surface T relative to the laser reference surface R, which is set by the setting device 7. Further, the operator sets the gradient β by employing the keys 7c, 7dof the setting device 7.

[0099] (Procedure 3)

[0100] Then, as shown in FIG. 10, the operator moves the front device 1A so that the laser beam receiver 10battached to the arm 1breceives the laser beam. With this setting operation, the computing section 11bcomputes, from the formula (3), the linear equation of the laser reference surface R on the x-z coordinate system of the body 1B based on both the coordinate values (PLx, PLz) of the laser beam receiver 10bon the x-z coordinate system resulted when the laser beam receiver 10breceives the laser beam, and the gradient β set by the setting device 7. Also, the computing and storing section 11dcomputes and stores, from the formula (4), the linear equation of the target excavating surface T on the x-z coordinate system of the body 1B based on both the positional relationship between the body 1B and the laser reference surface R computed by the computing section 11band the depth setting value Ld stored in the storing section 11c.

[0101] Incidentally, the operation of the procedure 2 and the operation of the procedure 3 until computing the linear equation of the laser reference surface R may be reversed such that the procedure 2 follows the procedure 3.

[0102] (Procedure 4)

[0103] Based on results of the operation setting in the procedure 2 and the procedure 3, the processing of the computing sections 11e-11jis further executed. Thereby, as shown in FIG. 9, the body 1B, the laser reference surface R and the target excavating surface T are displayed by the illustration 12c, the broken line 12aand the solid line 12bon the display section 20 of the monitor 12, respectively. At the same time, the gradient β of the target excavating surface T, the setting depth Ld of the target excavating surface T relative to the laser reference surface R, and the distance LPv from the laser reference surface R to the bucket prong end are displayed at the upper left corner of the display section 20.

[0104] By looking at the display on the monitor 12, the operator can visually confirm and recognize the positional relationship between the body and the target excavating surface, and the positional relationship between the laser reference surface and the target excavating surface. As a result, the operator can ascertain whether the setting conditions are proper or not.

[0105] (Procedure 5)

[0106] The operator operates the front device 1A for carrying out automatic excavation along the target excavating surface T stored in the computing and storing section 11dunder the area limiting excavation control.

[0107] (Procedure 6)

[0108] After the excavation for the target excavating surface over a predetermined region is completed, the body 1B is traveled as shown in FIG. 10.

[0109] A description is next made of works for setting the target excavating surface and carrying out excavation after the travel of the body 1B.

[0110] (Procedure 7)

[0111] After the travel of the body, as shown in FIG. 10, the operator moves the front device 1A so that the laser beam receiver 10battached to the arm 1breceives the laser beam. With this operation, the computing section 11bcomputes the positional relationship between the body 1B and the laser reference surface R, thereby compensating for change of the body position caused upon the travel of the body 1B.

[0112] Herein, since the depth setting value Ld relative to the laser reference surface, which has been set by the setting device 7 at the initial setting and stored in the storing section 11c, is not changed, the computing and storing section 11dcomputes and stores for update, from the above formula (4), the linear equation of the target excavating surface T on the x-z coordinate system of the body 1B based on both the positional relationship between the body 1B and the laser reference surface R computed by the computing section 11band the depth setting value Ld stored in the storing section 11c. With this processing, also after the body 1B has traveled, change in position of the body 1B relative to the laser reference surface R caused upon the travel of the body 1B can be compensated for, and the area limiting excavation control can be continuously performed for the target excavating surface T that is in the predetermined positional relationship relative to the laser reference surface R.

[0113] (Procedure 8)

[0114] The operator operates the front device 1A for carrying out automatic excavation along the target excavating surface T stored in the computing and storing section 11dunder the area limiting excavation control.

[0115] (Procedure 9)

[0116] Subsequently, by repeating the procedures 6 to 8, the automatic excavation is carried out along the surface having the predetermined depth and gradient relative to the laser reference surface R by employing the laser reference surface R as a reference, while the body 1B is traveled successively.

[0117] According to this embodiment having the above-described construction, since the lines 12a, 12brepresenting the target excavating surface T and the laser reference surface R are displayed on the monitor 12 mounted within the cab in a superimposed relation to the illustration 12cof the body 1B. Therefore, the operator can visually recognize not only the positional relationship between the body 1B and the target excavating surface T, but also the positional relationship between the laser reference surface R and the target excavating surface T. Hence, when carrying out excavation continuously over a long distance until and along a surface at a predetermined depth, the target excavating surface T can be easily set without causing a setting error of the target excavating surface T.

[0118] Furthermore, since data of the distance between the external reference surface R and the target excavating surface T and the gradient thereof, the distance between the work implement and the laser reference surface R, etc. are displayed in the form of numerical values, the positional relationships among the body 1B, the target excavating surface T and the laser reference surface R can be displayed to the operator in an easily recognizable manner, and a setting error of the target excavating surface T can be avoided with higher certainty.

[0119] The processing functions of a setting/display processing section 11A according to a second embodiment of the present invention will be described below with reference to FIGS. 11 and 12. These processing functions correspond to the method of inputting numerical values and to the case where transform into monitor coordinates is carried out on the basis of the target excavating surface. Note that, in FIG. 11, the same symbols as those in FIG. 6 denote the same components.

[0120] The construction of a hydraulic excavator according to this embodiment is the same as that shown in FIGS. 1 and 2, and the hardware configuration of a control unit according to this embodiment is the same as that shown in FIG. 3.

[0121] In FIG. 11, the setting/display processing section 11A differs from the setting/display processing section 11 shown in FIG. 6 in that a computing section ilk for transform of the positional relationship between the laser reference surface and the target excavating surface into monitor coordinates; a computing section 11Af for transform of the positional relationship between the body and the target excavating surface into monitor coordinates; a computing section 11Ag for producing a picture of the laser reference surface; a computing section 11Ah for producing a picture of the target excavating surface; and a computing section 11Aj for producing a picture of the body are provided instead of the computing sections 11e-11hand 11jin FIG. 6.

[0122] The computing section 11kfor transform of the positional relationship between the laser reference surface and the target excavating surface into monitor coordinates computes a linear equation of the laser reference surface R on an intermediate orthogonal coordinate system, in which the origin is set at a predetermined position (e.g., a cross point between an x-axis of the x-z coordinate system and the target excavating surface T) on the target excavating surface T, by using the depth setting value Ld of the target excavating surface T relative to the laser reference surface R, which has been stored in the storing section 11c. Then, the computing section 11ktransforms the computed linear equation into coordinate values on the x_m−z_mcoordinate system of the display section 20 of the monitor 12 shown in FIG. 12. In FIG. 12, a line 12brepresenting the target excavating surface T is displayed on the display section 20, and the origin Om of the x_m−z_mcoordinate system is fixedly set at a position on the line 12bcorresponding to the above-mentioned predetermined position on the target excavating surface T. A manner of coordinate transform into the x_m−z_mcoordinate system is similar to that described above in connection with the computing section 11ein the first embodiment.

[0123] The computing section 11Af for transform of the positional relationship between the body and the target excavating surface into monitor coordinates computes a position of the body 1B on the intermediate coordinate system by using the linear equation of the target excavating surface T on the x-z coordinate system of the body 1B computed by the computing section 11d, and then transforms the computed values into coordinate values on the x_m−z_mcoordinate system of the display section 20 shown in FIG. 12. The position of the body 1B is given by the position of the origin O of the x-z coordinate system.

[0124] The computing section 11Ag for producing a picture of the laser reference surface executes processing to produce and output a picture signal for displaying the linear equation of the laser reference surface R obtained by the computing section 11kas a straight line on the x_m−z_mcoordinate plane of the display section 20. The straight line representing the laser reference surface R is then displayed on the display section 20 of the monitor 12.

[0125] The computing section 11Aj for producing a picture of the body executes processing to produce a picture of the body 1B of the hydraulic excavator in the form of an illustration, and processing to produce and output a picture signal for displaying the produced illustration in a coordinate position, which has been computed by the computing section 11Af, on the x_m−z_mcoordinate plane of the display section 20. The illustration is then displayed on the display section 20 of the monitor 12

[0126] The computing section 11Ah for producing a picture of the target excavating surface executes processing to produce and output, using the gradient β set by the setting device 7, a picture signal for a straight line having the gradient β and passing the origin Om of the x_m−z_mcoordinate plane of the display section 20. The straight line representing the target excavating surface T is then displayed on the display section 20 of the monitor 12.

[0127] As a result of the processing described above, the positional relationships among the body 1B, the target excavating surface T and the laser reference surface R are displayed on the display section 20 of the monitor 12 as shown in FIG. 9.

[0128] This embodiment can also provide similar advantages as those in the first embodiment.

[0129] The processing functions of a setting/display processing section 11B according to a third embodiment of the present invention will be described below with reference to FIGS. 13 and 14. These processing functions correspond to the method of inputting numerical values and to the case where transform into monitor coordinates is carried out on the basis of the laser reference surface. Note that, in FIG. 13, the same symbols as those in FIG. 6 denote the same components.

[0130] The construction of a hydraulic excavator according to this embodiment is the same as that shown in FIGS. 1 and 2, and the hardware configuration of a control unit according to this embodiment is the same as that shown in FIG. 3.

[0131] In FIG. 13, the setting/display processing section 11B differs from the setting/display processing section 11 shown in FIG. 6 in that a computing section 11Be for transform of the positional relationship between the body and the laser reference surface into monitor coordinates; a computing section 11Bk for transform of the positional relationship between the laser reference surface and the target excavating surface into monitor coordinates; a computing section 11Bj for producing a picture of the body; a computing section 11Bh for producing a picture of the target excavating surface; and a computing section 11Bg for producing a picture of the laser reference surface are provided instead of the computing sections 11e-11hand 11jin FIG. 6.

[0132] The computing section 11Be for transform of the positional relationship between the body and the laser reference surface into monitor coordinates computes a position of the body 1B on an intermediate orthogonal coordinate system, in which the origin is set at a predetermined position (e.g., a cross point between an x-axis of the x-z coordinate system and the laser reference surface R) on the laser reference surface R, by using the linear equation of the laser reference surface R on the x-z coordinate system of the body 1B computed by the computing section lib, and then transforms the computed values into coordinate values on the x_m−z_mcoordinate system of the display section 20 shown in FIG. 14. The position of the body 1B is given by the position of the origin O of the x-z coordinate system. Further, in FIG. 14, a line 12arepresenting the laser reference surface R is displayed on the display section 20, and the origin Om of the x_m−z_mcoordinate system is fixedly set at a position on the line 12acorresponding to the above-mentioned predetermined position on the laser reference surface R. A manner of coordinate transform into the x_m−z_mcoordinate system is similar to that described above in connection with the computing section 11ein the first embodiment.

[0133] The computing section 11Bk for transform of the positional relationship between the laser reference surface and the target excavating surface into monitor coordinates computes a linear equation of the target excavating surface T on the intermediate orthogonal coordinate system by using the depth setting value Ld of the target excavating surface T relative to the laser reference surface R, which has been stored in the storing section 11c. Then, the computing section 11Bk transforms the computed linear equation into coordinate values on the x_m−z_mcoordinate system of the display section 20 of the monitor 12 shown in FIG. 14.

[0134] The computing section 11Bj for producing a picture of the body executes processing to produce a picture of the body 1B of the hydraulic excavator in the form of an illustration, and processing to produce and output a picture signal for displaying the produced illustration in a coordinate position, which has been computed by the computing section 11Be, on the x_m−z_mcoordinate plane of the display section 20. The illustration is then displayed on the display section 20 of the monitor 12.

[0135] The computing section 11Bh for producing a picture of the target excavating surface executes processing to produce and output a picture signal for displaying the linear equation of the target excavating surface T obtained by the computing section 11Bk as a straight line on the x_m−z_mcoordinate plane of the display section 20. The straight line representing the target excavating surface T is then displayed on the display section 20 of the monitor 12.

[0136] The computing section 11Bg for producing a picture of the laser reference surface executes processing to produce and output, using the gradient β set by the setting device 7, a picture signal for a straight line having the gradient β and passing the origin Om of the x_m−z_mcoordinate plane of the display section 20. The straight line representing the laser reference surface R is then displayed in the display section 20 of the monitor 12.

[0137] As a result of the processing described above, the positional relationships among the body 1B, the target excavating surface T and the laser reference surface R are displayed on the display section 20 of the monitor 12 as shown in FIG. 9.

[0138] This embodiment can also provide similar advantages as those in the first embodiment.

[0139] The processing functions of a setting/display processing section 11C according to a fourth embodiment of the present invention will be described below with reference to FIGS. 7 and 15. These processing functions correspond to the direct teaching method. Note that, in FIG. 15, the same symbols as those in FIG. 6 denote the same components.

[0140] The construction of a hydraulic excavator according to this embodiment is the same as that shown in FIGS. 1 and 2, and the hardware configuration of a control unit according to this embodiment is the same as that shown in FIG. 3.

[0141] In FIG. 15, the setting/display processing section 11C differs from the setting/display processing section 11 shown in FIG. 6 in that a section 11sfor computing and storing the positional relationship between the body and the target excavating surface and a section 11tfor computing and storing the positional relationship (depth) between the laser reference surface and the target excavating surface are provided instead of the section 11cfor storing the positional relationship (depth) between the laser reference surface and the target excavating surface and the section 11dfor computing and storing the positional relationship between the body and the target excavating surface.

[0142] The section 11sfor computing and storing the positional relationship between and the target excavating surface computes and stores a linear equation of the target excavating surface T on the x-z coordinate system of the body 1B from the following formula (9) based on both coordinate values (Pcx, Pcz) of the bucket prong end on the x-z coordinate system, which has been computed by the section 11afor computing bucket prong-end coordinates upon inputting of the direct teaching signal from the setting device 7, and the gradient f set by the setting device 7:

[0143] z=tan β·x+(Pcz−tan β·Pcx)  (9)

[0144] The section lit for computing and storing the positional relationship (depth) between the laser reference surface and the target excavating surface computes and stores the distance Ld between the laser reference surface R and the target excavating surface T in the depth direction based on both the positional relationship between the body 1B and the laser reference surface R computed by the computing section 11b(i.e., the linear equation of the laser reference surface R on the x-z coordinate system, which is expressed by the above-mentioned formula (3) and has been computed from both the coordinate values (PLx, PLz) of the laser beam receiver 10bon the x-z coordinate system resulted when the laser beam receiver 10breceives the laser beam, and the gradient β set by the setting device 7), and the linear equation of the target excavating surface T, expressed by the above formula (9), on the x-z coordinate system of the body 1B, which has been stored in the computing and storing section 11s. Herein, a formula for computing the distance Ld in the depth direction is expressed by the following one (10):

[0145] Ld=(segment of linear equation of target excavating surface)−(segment of linear equation of laser reference surface)  (10)

[0146] Further, broken lines in FIG. 15 represent a flow of the processing after travel of the body. Specifically, after the travel of the body, based on both the linear equation (above-mentioned formula (3)) of the laser reference surface R on the x-z coordinate system of the body 1B, which has been computed by the computing section 11b, and the distance Ld between the laser reference surface R and the target excavating surface T in the depth direction, which has been stored in the computing and storing section 11t, the linear equation of the target excavating surface T on the x-z coordinate system of the body 1B is computed from the above-mentioned formula (4):

[0147] z=tan β·x+(PLz−tan β·PLx)+Ld  (4)

[0148] The processing functions of the computing sections 11e-11iare the same as those in the first embodiment shown in FIG. 6. In the computing section 11f, however, the linear equation of the target excavating surface T is transformed into coordinate values on the x_m−z_mcoordinate system of the monitor 12 by employing, as the linear equation of the target excavating surface T on the x-z coordinate system of the body 1B, the above-mentioned formula (9) at the initial excavating position before the travel of the body and the above-mentioned formula (4) after the travel of the body.

[0149] As a result of the processing described above, the positional relationships among the body, and the target excavating surface and the laser reference surface, and the associated numerical values are displayed on the monitor 12 as shown in FIG. 9.

[0150] Procedures for setting the target excavating surface based on the direct teaching method according to this embodiment and processing procedures for continuously carrying out excavation along a surface at the predetermined depth and gradient from the laser reference surface (external reference) R in accordance with the set target excavating surface will be described below with reference to FIGS. 15 and 10.

[0151] A description is first made of works for setting the target excavating surface at an excavating start position and carrying out excavation.

[0152] (Procedure 1)

[0153] First, as shown in FIG. 10, the operator operates the laser lighthouse 10aand sets the laser reference surface R parallel to the target excavating surface that is to be set.

[0154] (Procedure 2)

[0155] Then, the operator moves the front device 1A so that the prong end of the bucket 1cmoves to a target point of the excavation, as indicated by two-dot-chain lines in FIG. 7, and then depresses the direct teaching key 7eshown in FIG. 5. Also, before or after this operation, the operator sets the gradient β by employing the keys 7c, 7dof the setting device 7.

[0156] With the above setting operation, the computing section 11acomputes, on the basis of the x-z coordinate system set for the body 1B and the dimensions of the respective components shown in FIG. 7, coordinate values (Pcx, Pcz) of the bucket prong end on the x-z coordinate system from the formulae (1) and (2). Further, the computing and storing section 11scomputes and stores a linear equation of the target excavating surface T on the x-z coordinate system of the body 1B from the equation (9) based on both the computed coordinate values (Pcx, Pcz) of the bucket prong end on the x-z coordinate system and the gradient β of the laser reference surface.

[0157] (Procedure 3)

[0158] Then, as shown in FIG. 10, the operator moves the front device 1A so that the laser beam receiver 10battached to the arm 1breceives the laser beam. With this setting operation, the computing section 11bcomputes, from the formula (3), a linear equation of the laser reference surface R on the x-z coordinate system of the body 1B based on both the coordinate values (PLx, PLz) of the laser beam receiver 10bon the x-z coordinate system resulted when the laser beam receiver 10breceives the laser beam, and the gradient β set by the setting device 7. Also, the computing and storing section 11tcomputes and stores, from the formula (10), the depth setting value Ld based on both the positional relationship between the body 1B and the laser reference surface R, which has been computed by the computing section 11b, and the linear equation of the target excavating surface T on the x-z coordinate system of the body 1B, which has been stored in the computing and storing section 11s.

[0159] Incidentally, the operation of the procedure 2 and the operation of the procedure 3 until computing the linear equation of the laser reference surface R may be reversed such that the procedure 2 follows the procedure 3.

[0160] (Procedure 4)

[0161] Based on results of the operation setting in the procedure 2 and the procedure 3, the processing of the computing sections 11e-11jis further executed. Thereby, as shown in FIG. 9, the body 1B, the laser reference surface R and the target excavating surface T are displayed by an illustration 12c, a broken line 12aand a solid line 12bon the display section 20 of the monitor 12, respectively. At the same time, the gradient β of the target excavating surface T, the setting depth Ld of the target excavating surface T relative to the laser reference surface R, and the distance LPv from the laser reference surface R to the bucket prong end are displayed at the upper left corner of the display section 20.

[0162] By looking at the display on the monitor 12, the in operator can visually confirm and recognize the positional relationship between the body and the target excavating surface, and the positional relationship between the laser reference surface and the target excavating surface. As a result, the operator can ascertain whether the setting conditions are proper or not.

[0163] (Procedure 5)

[0164] The operator operates the front device 1A for carrying out automatic excavation along the target excavating surface stored in the computing and storing section 11sunder the area limiting excavation control.

[0165] (Procedure 6)

[0166] After the excavation for the target excavating surface over a predetermined region is completed, the body 1B is traveled as shown in FIG. 10.

[0167] A description is next made of works for setting the target excavating surface and carrying out excavation after the travel of the body 1B.

[0168] (Procedure 7)

[0169] After the travel of the body, as shown in FIG. 10, the operator moves the front device 1A so that the laser beam receiver 10battached to the arm 1breceives the laser beam. With this operation, the computing section 11bcomputes the positional relationship between the body 1B and the laser reference surface R, thereby compensating for change of the body position caused upon the travel of the body 1B.

[0170] Herein, since the depth setting value Ld relative to the laser reference surface R, which is stored in the computing and storing section 11t, is not changed, the computing and storing section 11scomputes and stores for update, from the above formula (4), the linear equation of the target excavating surface T on the x-z coordinate system of the body 1B based on both the positional relationship between the body 1B and the laser reference surface R computed by the computing section 11band the depth setting value Ld stored in the computing and storing section 11t. With this processing, also after the body 1B has traveled, change in position of the body 1B relative to the laser reference surface R caused upon the travel of the body 1B can be compensated for, and the area limiting excavation control can be continuously performed for the target excavating surface T that is in the predetermined positional relationship relative to the laser reference surface R.

[0171] (Procedure 8)

[0172] The operator operates the front device 1A for carrying out automatic excavation along the target excavating surface T stored in the computing and storing section 11sunder the area limiting excavation control.

[0173] (Procedure 9)

[0174] Subsequently, by repeating the procedures 6 to 8, the automatic excavation is carried out along the surface having the predetermined depth and gradient relative to the laser reference surface R by employing the laser reference surface R as a reference, while the body 1B is traveled successively.

[0175] According to this embodiment having the above-described construction, similar advantages as those in the first embodiment can also be obtained in the case of employing the direct teaching method.

[0176] In the embodiment shown in FIG. 15, the processing to execute transform into monitor coordinates and then to produce and output picture signals after computing the positional relationships among the body 1B, the laser reference surface R and the target excavating surface T by the computing section 11band the computing and storing sections 11s, 11tis assumed to be the same as the processing executed by the computing sections 11e-11hand 11jin the first embodiment shown in FIG. 6. The computing sections 11e-11hand 11jare employed in the case of transform into monitor coordinates on the basis of the body. However, transform into monitor coordinates may be executed on the basis of the target excavating surface or the laser reference surface as with the second and third embodiments.

[0177] FIGS. 16 and 17 are block diagrams showing the processing functions executed by setting/display processing sections in such cases. More specifically, FIG. 16 shows, as a fifth embodiment of the present invention, the processing functions of a setting/display processing section 11D adapted for the case where transform into monitor coordinates is executed on the basis of the target excavating surface, and FIG. 17 shows, as a sixth embodiment of the present invention, the processing functions of a setting/display processing section 11E adapted for the case where transform into monitor coordinates is executed on the basis of the laser reference surface. In FIG. 16, the same symbols as those in FIGS. 11 and 15 denote the same components. In FIG. 17, the same symbols as those in FIGS. 13 and 15 denote the same components.

[0178] These embodiments can also provide similar advantages as those in the first embodiment in the case of employing the direct teaching method.

[0179] A second display example in the display device for the target excavating-surface setting system of the present invention will be described below with reference to FIG. 18.

[0180] As described above in connection with FIG. 9, the straight line 12arepresenting the laser reference surface R, the straight line 12brepresenting the target excavating surface T, and the illustration 12cof the body 1B of the hydraulic excavator are displayed on the display section 20 of the monitor 12. In addition, in this display example, a current bucket end position 12dis displayed on a screen of the display section 20 in a superimposed manner for clearly indicating the positional relationship between the target excavating surface and the bucket end, and a line 12eextended along the lower travel structure of the body 1B and representing the ground is displayed as an auxiliary line on the screen of the display section 20. This second display example enables the operator to more precisely confirm current situations including a current position of the work implement and a relation relative to the ground.

[0181] A third display example in the display device for the target excavating-surface setting system of the present invention will be described below with reference to FIG. 19.

[0182] This third display example differs from the second display example of FIG. 18 in that a current position of the work implement, e.g., the bucket, is displayed in the form of an illustration 12fof the bucket. Also, by providing an inclinometer to detect a gradient of the body in the back-and-forth direction, a line 12eextended along the lower travel structure of the body 1B and representing the ground and the illustration 12cof the body 1B are displayed at an inclination depending on the detected gradient. Accordingly, this third display example enables the operator to more precisely confirm current situations including a current position of the work implement, an inclination of the body, and a ground condition.

[0183] Still another embodiment of the present invention will be described with reference to FIGS. 20 and 21. In this embodiment, a display processing section is separated from the setting/display processing section disposed in the control unit, and is provided as a display processing unit separate from the control unit. In FIGS. 20 and 21, members identical to those in FIGS. 4 and 6 are denoted by the same symbols.

[0184] In FIG. 20, a control unit 9F comprises a setting processing section 11Fa for setting the target excavating surface T and computing the positional relationships among the body 1B, the laser reference surface R and the target excavating surface T, and an excavation control section 14 for carrying out area limiting excavation control. Also, a display processing unit 11Fb is provided separately from the control unit 9F.

[0185] In FIG. 21, the setting processing section 11Fa includes respective functions executed by a section 11afor computing bucket prong-end coordinates; a section 11bfor computing the positional relationship between the body and the laser reference surface; a section 11cfor storing the positional relationship (depth) between the laser reference surface and the target excavating surface; and a section 11dfor computing and storing the positional relationship between the body and the target excavating surface. The display processing unit 11Fb comprises a computing section 11efor transform of the positional relationship between the body and the laser reference surface into monitor coordinates; a computing section 11ffor transform of the positional relationship between the body and the target excavating surface into monitor coordinates; a computing section 11gfor producing a picture of the laser reference surface; a computing section 11hfor producing a picture of the target excavating surface; and a computing section 11ifor display of the setting values; and a computing section 11jfor producing a picture of the body.

[0186] A monitor 12 is mounted within a cab at a corner obliquely in front of an operator seat. A control unit 9Fa is mounted within the cab at a position, for example, behind and below the operator seat, and the display processing unit 11Fb is mounted, for example, in a console box disposed laterally of the operator seat.

[0187] This embodiment can also provide similar advantages as those in the first embodiment.

[0188] Further, with this embodiment, since the processing to produce and output a picture signal is executed by the dedicated processing unit 11Fb, it is easily possible for the display processing unit 11Fb to have an additional processing function to produce and output a picture signal for another information, such as information of maintenance and inspection transmitted through a communicating satellite. The display device is therefore adaptable for multiple purposes in use.

[0189] The target excavating-surface setting system and the display device of the present invention are not limited in details to the embodiments described above, but may be modified in various ways. For example, while the laser reference surface defined by a laser beam is used as the external reference in the above-described embodiments, any other suitable external reference, e.g., a leveling string, may also be used. In the case of using a leveling string as the external reference, the positional relationship between the body and the laser reference surface may be computed by the computing section 11bby moving the front device such that the bucket prong end contacts the leveling string, depressing a trigger switch in that condition, and then employing detection values of the angle sensors 8a, 8band 8cat that time. Also, while the laser beam receiver 10bis attached to the lateral surface of the arm in the case of using the laser reference surface, a front reference may be marked on the lateral surface of the arm by the use of a panel, painting or the like, instead of the laser beam receiver 10b. In such a case, the positional relationship between the body and the laser reference surface can also be computed by the computing section 11b, as with the case of using a leveling string, by depressing the trigger switch at the time when a laser beam impinges upon the front reference mark.

[0190] Further, in the present invention, when carrying out excavation after setting the target excavating surface, the excavation is not limited to be performed under area limiting excavation control, but may be performed under any other suitable excavation control. Moreover, the display example on the display device, shown in FIG. 9, 18 or 19, may be modified such that the target excavating surface and the external reference surface are drawn in different display colors and/or different line types, thus allowing the operator to more easily visually discern those surfaces.

[0191] Additionally, while electrical levers are used as the control levers in the above-described embodiments, they may be replaced by hydraulic pilot levers. Also, while angle sensors for detecting rotational angles are employed as means for detecting the status variables relating to the position and the posture of the front device 1A, the stroke of each cylinder may be detected instead.

[0192] According to the present invention, a target excavating surface can be easily set using an external reference when excavation is carried out continuously over a long distance until and along a surface at a predetermined depth.