Display system of turning work vehicle

According to the present invention, a display system of a turning work vehicle is used for the turning work vehicle in which a work machine having a bucket 8 can be offset relative to a revolving superstructure in the horizontal direction. The display system includes: an arithmetic unit that calculates the position of the bucket on the basis of a detection result obtained by a position detecting device provided on the turning work vehicle, and calculates a necessary revolving amount of the revolving superstructure and a necessary offset amount of the work machine that are needed to align a side section of the bucket with a side edge of a predetermined excavation area; and a display device that displays the positional relationship between the bucket and the predetermined excavation area.

This application is a national phase entry under 35 U.S.C. § 371 of PCT Patent Application No. PCT/JP2019/002229, filed on Jan. 24, 2019, which claims priority under 35 U.S.C. § 119 to Japanese Patent Application No. 2018-054383, filed Mar. 22, 2018, both of which are incorporated by reference.

TECHNICAL FIELD

The present invention relates to a display system of a turning work vehicle, a turning work vehicle, and a display method for a turning work vehicle.

BACKGROUND ART

In a turning work vehicle such as a backhoe, by detecting a position of a construction work edge of a work machine, highly accurate control is possible. Being able to do so helps to achieve automation of the work and securing safety of the surroundings. Patent Literature 1 to 3 describes a hydraulic shovel as the turning work vehicle provided with means for detecting a position of the construction work edge of the work machine that has a bucket (that is, a blade edge of the bucket).

In addition, in a compact excavator, in particular, in order to enhance the workability in a narrow space, a function which enables the work machine to be offset relative to a revolving superstructure in a horizontal direction may be provided. In one aspect, the offset of the work machine is realized by swinging the work machine to right and left with respect to the revolving superstructure, and in another aspect, the offset is realized by translating the work machine to the right and left with respect to the revolving superstructure.

Patent Literature 1 describes a technique for detecting a position of a construction work edge, on the basis of outputs from a plurality of position sensors installed on a work machine, and positional information from two GPS antennas installed on a construction machine body. However, when this technique is applied to a turning work vehicle which is capable of offsetting a work machine in the horizontal direction as described above, since a relative relation between the output from the position sensor and the positional information from the antenna varies depending on the offset of the work machine, it is not possible to detect the position of the construction work edge.

Patent Literature 2 describes a technique for detecting a turning central position of an arm, on the basis of positional information from a GPS antenna installed on a construction work edge of the arm, and positional information from a GPS antenna installed on a construction machine body, and further detecting a position of the construction work edge on the basis of outputs from a plurality of position sensors. However, since the antenna needs to be installed at the construction work edge where great vibration and impact are to be applied during the work, the technique is not convenient in performing position detection of the construction work edge at high accuracy.

Patent Literature 3 describes a technique for displaying, on a screen, targeted turning information obtained for a blade edge of a bucket to face a targeted surface. However, when this technique is applied to a turning work vehicle which is capable of offsetting the work machine in the horizontal direction as described above, it is not possible to reflect the positional information of the bucket that has been changed by the offset. In addition, in construction such as digging of a side ditch, while a side section of the bucket needs to be aligned with a side edge of an excavation scheduled area, the technique in question does not consider the offset of the work machine, and the side section of the bucket. Thus, a high skill is required for an operator.

CITATION LIST

Patent Literature

DISCLOSURE OF INVENTION

Problems to be Solved by the Invention

The present invention has been conceived in view of the above circumstances, and an object of the present invention is to provide a display system of a turning work vehicle, in which the turning work vehicle is capable of offsetting a work machine in a horizontal direction, and the display system is useful for operational assistance for construction such as digging of a side ditch, a turning work vehicle, and a display method for a turning work vehicle.

Means for Solving the Problems

A display system of a turning work vehicle according to the present invention is used for the turning work vehicle which can offset a work machine including a bucket relative to a revolving superstructure in a horizontal direction, in which the display system includes: an arithmetic unit, which calculates a position of the bucket on the basis of a result of detection by a position detecting device installed on the turning work vehicle, and calculates a necessary revolving amount of the revolving superstructure and a necessary offset amount of the work machine that are needed to align a side section of the bucket with a side edge of a predetermined excavation area; and a display device which displays a positional relationship between the bucket and the predetermined excavation area. Such a configuration contributes to, in the turning work vehicle capable of offsetting the work machine in the horizontal direction, operational assistance for construction such as digging of a side ditch.

The display device should preferably display information for informing about an operation amount of the revolving superstructure according to the necessary revolving amount, and an operation amount of the work machine according to the necessary offset amount. By this feature, it is possible to give operation guidance to the operator regarding revolution of the revolving superstructure and the offset of the work machine for aligning the side section of the bucket with the side edge of the predetermined excavation area.

It is preferable that a safety device, which restricts the revolution of the revolving superstructure and the offset of the work machine so that the bucket does not cross over the side edge of the predetermined excavation area, should be provided. By this feature, it is possible to prevent the bucket from colliding with a wall surface when wall-side excavation is to be performed.

The offset of the work machine may be performed by swinging the work machine to right and left with respect to the revolving superstructure.

The display device should preferably display at least the bucket and the predetermined excavation area in a plan view. By this feature, it is possible to accurately convey to the operator the positional relationship between the bucket and the predetermined excavation area, which is useful in aligning the side section of the bucket with the side edge of the predetermined excavation area.

The display device should preferably display the side edge of the predetermined excavation area by a virtual line extending in an extending direction of the predetermined excavation area. By displaying a position of the side edge of the predetermined excavation area, it is possible to effectively assist the operation of the operator.

A turning work vehicle according to the present invention includes: the display system of the turning work vehicle as described above; a lower traveling body; the revolving superstructure which is provided above the lower traveling body so as to be revolvable; and the work machine which can be offset relative to the revolving superstructure in the horizontal direction. As the above-described display system is provided, such a turning work vehicle contributes to operational assistance for construction such as digging of a side ditch.

A display method for a turning work vehicle according to the present invention is used for the turning work vehicle which can offset a work machine including a bucket relative to a revolving superstructure in a horizontal direction, in which the display method includes: calculating a position of the bucket on the basis of a result of detection by a position detecting device installed on the turning work vehicle, and calculating a necessary revolving amount of the revolving superstructure and a necessary offset amount of the work machine that are needed to align a side section of the bucket with a side edge of a predetermined excavation area; and displaying a positional relationship between the bucket and the predetermined excavation area on a screen of a display device. Such a method contributes to, in the turning work vehicle capable of offsetting the work machine in the horizontal direction, operational assistance for construction such as digging of a side ditch.

DESCRIPTION OF EMBODIMENTS

[Overview of Turning Work Vehicle]

As shown inFIGS.1and2, a turning work vehicle1is provided with: a lower traveling body2; a revolving superstructure3which is provided above the lower traveling body2so as to be revolvable; and a work machine5which can be offset relative to the revolving superstructure3in a horizontal direction. In the present embodiment, the turning work vehicle1is configured as a shovel provided with a boom swing function (i.e., a backhoe), and the offset of the work machine5is performed by swinging the work machine5to right and left with respect to the revolving superstructure3. In general, the boom swing function is provided in a compact excavator of which workability in a narrow space is required.

The lower traveling body2is driven as it receives power from an engine30, and causes the turning work vehicle1to travel and turn. The lower traveling body2is provided with a pair of left and right crawlers21and21, and a pair of left and right traveling motors22and22for driving the aforementioned crawlers21and21. Between the pair of crawlers21and21, a base23revolvably supporting the revolving superstructure3is provided. Also, the lower traveling body2is provided with: a pair of blade arms24and24; a blade25, which serves as an earth-moving plate, extending in a left-right direction between distal end portions of the blade arms24and24; and a blade cylinder26for rotating the blade25up and down.

The revolving superstructure3is configured to be able to perform a revolving operation about an axis extending in a vertical direction at a central portion thereof.FIGS.1and2illustrate a Z-axis which corresponds with the aforementioned axis. The revolving superstructure3is formed in a substantially disk shape in a plan view to be revolvable within a breadth of the lower traveling body2(i.e., a distance between an outer edge of the left crawler21and an outer edge of the right crawler21). The revolving superstructure3is equipped with the engine30, a counterweight31, a cabin32, etc. A driving part surrounded by the cabin32is provided with, for example, a driver's seat (not shown) where an operator is seated, an operating device33(seeFIG.3) for the operator to perform an operation, and a display device37(seeFIG.3) which display various kinds of information.

The turning work vehicle1is provided with a boom bracket4, which is a swing body supported on the revolving superstructure3so as to be horizontally rotatable. The boom bracket4is mounted on a front end portion of the revolving superstructure3via a stay33. The stay33is provided with a pivot pin40in which an axis a (seeFIG.4) is oriented in the vertical direction. The boom bracket4is supported so as to be horizontally rotatable (that is, swingable right and left) about the pivot pin40of the boom bracket4. The boom bracket4is rotated on a horizontal plane (for example, an X-Y plane shown inFIG.5) orthogonal to the axis a. A swing cylinder41, which expands and contracts in a front-rear direction, is provided between the revolving superstructure3and the boom bracket4. The horizontal rotation of the boom bracket4is performed in accordance with the expansion and contraction of the swing cylinder41.

The work machine5is driven as it receives power from the engine30, and performs excavation work of the land, for example, in accordance with an operation performed in the driving part. The work machine5is supported on the boom bracket4so as to be vertically rotatable. The boom bracket4is provided with a pivot pin60in which an axis is oriented in the horizontal direction. A proximal end portion of the work machine5(i.e., a proximal end portion of a boom6which will be described later) is supported so as to be vertically rotatable about the above-mentioned pivot pin60. The work machine5is rotated on a vertical plane (for example, an X-Z plane shown inFIG.4) orthogonal to the axis of the pivot pin60. The work machine5moves horizontally relative to the revolving superstructure3(i.e., is offset in the horizontal direction) by performing a swing operation in tandem with the horizontal rotation of the boom bracket4.

The work machine5includes the boom6, an arm7, and a bucket8, which is an attachment for excavation. The boom6is mounted on the boom bracket4so as to be vertically rotatable. The boom6extends in the vertical direction from the proximal end portion supported on the boom bracket4, and is bent in the shape of a boomerang in a side view. A boom cylinder6a, which is movable in an expandable and contractible manner, is provided between the boom bracket4and a middle portion of the boom6. The vertical rotation of the boom6with respect to the boom bracket4is performed in accordance with the expansion and contraction of the boom cylinder6a.

The arm7is attached to the boom6so as to be vertically rotatable. At a distal end portion of the boom6, a pivot pin70in which an axis is oriented in the horizontal direction is provided. A proximal end portion of the arm7is supported so as to be vertically rotatable (i.e., rotatable to the front and rear) about the above-mentioned pivot pin70. An arm cylinder7a, which is movable in an expandable and contractible manner, is provided between the middle portion of the boom6and the proximal end portion of the arm7. The vertical rotation of the arm7with respect to the boom6is performed in accordance with the expansion and contraction of the arm cylinder7a.

The bucket8is attached to the arm7so as to be vertically rotatable. At a distal end portion of the arm7, a pivot pin80in which an axis is oriented in the horizontal direction is provided. A proximal end portion of the bucket8is supported so as to be vertically rotatable (i.e., rotatable to the front and rear) about the above-mentioned pivot pin80. A bucket link81is interposed between the distal end portion of the arm7and the bucket8. The bucket link81is configured as a link which transmits a driving force to the bucket8. A bucket cylinder8a, which is movable in an expandable and contractible manner, is provided between the bucket link81and the proximal end portion of the arm7. The vertical rotation of the bucket8with respect to the arm7is performed in accordance with the expansion and contraction of the bucket cylinder8a. The bucket8includes a blade edge8E, which serves as a construction work edge, and a side section8S formed by a side panel.

[Control System of Turning Work Vehicle]

An example of a control system provided in the turning work vehicle1will be briefly described. As shown inFIG.3, the turning work vehicle1is provided with: the operating device33; a main unit controller34, which is a vehicle control device; a work machine control device35; a display controller36, which is a display control device; and a display device37. The operating device33includes a lever, a switch, a pedal, an operation panel, etc. The operation panel may also serve as the display device37. The main unit controller34controls a traveling operation of the lower traveling body2and a revolving operation of the revolving superstructure3, on the basis of a control signal from the operating device33. Also, the main unit controller34controls the work machine control device35and the display controller36, on the basis of the control signal from the operating device33.

The work machine control device35controls the operation of the work machine5. The operation includes not only the vertical rotation of each of the boom6, the arm7, and the bucket8, but also the swing operation (offset) of the work machine5caused by the horizontal rotation of the boom bracket4. The display controller36is provided with a storage device36a, an arithmetic unit36b, and a safety device36c. The storage device36ais configured from random access memory (RAM) and read-only memory (ROM), etc., and stores various kinds of data which will be described later. The arithmetic unit36bexecutes predetermined arithmetic processing, on the basis of the data stored in the storage device36a, and a detection signal or the like from position detecting devices11and12. The display controller36can display a result of the arithmetic processing, etc., on a screen of the display device37.

A display system50is used for the turning work vehicle1capable of offsetting the work machine5having the bucket8relative to the revolving superstructure1in the horizontal direction, and provides the operator with information useful for operational assistance for construction in excavation work such as digging of a side ditch. The display system50is provided with the arithmetic unit36band the display device37as described above. The arithmetic unit36bcalculates the position of the bucket8on the basis of results of detection by the position detecting devices11and12installed on the turning work vehicle1, and calculates a necessary revolving amount of the revolving superstructure3and a necessary offset amount of the work machine5that are needed to align the side section8S of the bucket8with a side edge of a predetermined excavation area90(seeFIG.8). The display device37displays a positional relationship between the bucket8and the predetermined excavation area90.

Next, a method for detecting a position of the bucket8will be described. Strictly speaking, a position of the blade edge8E of the bucket8is detected, and a position of the side section8S is calculated on the basis of the blade edge position. As illustrated inFIG.3, the turning work vehicle1is provided with the position detecting device11(a first position detecting device), and the position detecting device12(a second position detecting device). The position detecting device11detects a horizontal position of the boom bracket4with respect to the revolving superstructure3. The position detecting device12detects a vertical position of the work machine5with respect to the revolving superstructure3. The arithmetic unit36bcalculates the position of the blade edge8E on the basis of the results of detection by the position detecting devices11and12.

In the present embodiment, the position detecting device11is constituted by a position sensor installed on the boom bracket4as shown inFIG.2. The position sensor detects movement of the boom bracket4on a plane where the boom bracket4is movable, or more specifically, the movement on a horizontal plane that is perpendicular to the axis a of the pivot pin40. By installing such a position sensor on the boom bracket4, it is possible to detect the horizontal position of the boom bracket4with respect to the revolving superstructure3comparatively easily. The present embodiment represents an example in which an acceleration sensor is used as the position sensor which constitutes the position detecting device11to detect a swing angle θ2of the boom bracket4with respect to the revolving superstructure3.

The position sensor which constitutes the position detecting device11can alternatively be installed on the swing cylinder41. Also, as the position sensor, although an inertial sensor such as the acceleration sensor can be used as described above, the position sensor is not limited to this example. For example, a gyro sensor, an angle sensor (tilt sensor), or a cylinder sensor (stroke sensor) can be used instead. When a cylinder sensor is used, the swing angle θ2can be detected on the basis of an expansion/contraction amount (stroke amount) of the swing cylinder41, whereby the horizontal position of the boom bracket4with respect to the revolving superstructure3can be detected.

In the present embodiment, the position detecting device12includes a position sensor12ainstalled on the boom6, a position sensor12binstalled on the arm7, and a position sensor12cinstalled on the bucket link81, as shown inFIG.1. Each of the position sensors12ato12cdetects movement of the work machine5on a plane where the work machine5is movable, or more specifically, the movement on a vertical plane including the axis a of the pivot pin40. The present embodiment represents an example in which acceleration sensors are used as the position sensors12ato12cto detect angles α, β and γ, which will be described later. Likewise the position detecting device11, the position sensors which constitute the position detecting device12are not limited to inertial sensors such as the acceleration sensors.

FIG.4is a left side view conceptually showing a coordinate system and the turning work vehicle1. The coordinate system is an orthogonal coordinate system defined by a horizontal X-axis extending from right to left inFIG.4, a horizontal Y-axis (seeFIG.5) that is perpendicular to the plane ofFIG.4, and a vertical Z-axis extending upward and downward inFIG.4. The X-axis extends in a front-rear direction of the lower traveling body2, and the Y-axis extends in a left-right direction (width direction) of the lower traveling body2. The Z-axis corresponds with an axis, which is the center of revolution, of the revolving superstructure3. The X-Y plane including an origin O is located at the height of the axis of the pivot pin60, and the axis a of the pivot pin40is orthogonal to the X-Y plane.

FIG.5is a plan view conceptually showing a coordinate system and the turning work vehicle1. The position of the work machine5illustrated inFIG.4is indicated by a chain line inFIG.5. InFIGS.4and5, the axis a of the pivot pin40is arranged on the X-axis. A revolving angle θ1(seeFIG.6) of the revolving superstructure3with respect to the lower traveling body2is assumed with reference to the above-described state, and the revolving angle θ1is zero inFIGS.4and5. Further, inFIG.4, the work machine5is arranged on the vertical plane (X-Z plane) including the axis a of the pivot pin40and the Z-axis. The swing angle θ2of the boom bracket4with respect to the revolving superstructure3is assumed with reference to the above state, and the swing angle θ2is zero inFIG.4.

InFIG.4, the work machine5is in state of being movable on the X-Z plane, in other words, each of the boom6, the arm7and the bucket8is in a state of being vertically rotatable (i.e., rotatable to the front and rear) on the X-Z plane. The angle α is a tilt angle (rotation angle) of the boom6with reference to the axis a of the pivot pin40. The angle β is a tilt angle (rotation angle) of the arm7with reference to an extending direction of the boom6(i.e., the direction of length L1). The angle γ is a tilt angle (rotation angle) of the bucket8with reference to an extending direction of the arm7(i.e., the direction of length L2). As described above, these angles α, β and γ can be detected by the position sensors12ato12cwhich constitute the position detecting device12.

The length L1is a length from the proximal end portion of the boom6to the distal end portion of the same, or more specifically, corresponds to a direct distance from the axis of the pivot pin60to the axis of the pivot pin70. The length L2is a length from the proximal end portion of the arm7to the distal end portion of the same, or more specifically, corresponds to a direct distance from the axis of the pivot pin70to the axis of the pivot pin80. The length L3is a length from the proximal end portion of the bucket8to a distal end portion of the same, or more specifically, corresponds to a direct distance from the axis of the pivot pin80to the blade edge8E. Data regarding the lengths L1to L3is stored in the storage device36ain advance.

The turning work vehicle1of the present embodiment includes two GPS antennas9and9. Three-dimensional positional information of the antennas9and9is received by a receiving device19(seeFIG.3). The antennas9and9are fixed at predetermined positions on the turning work vehicle1. In the present embodiment, the antennas9and9are arranged on a horizontal plane parallel to the X-Y plane. A relative position of the axis, which is the center of revolution, of the revolving superstructure3(more specifically, the Z-axis), and eventually, a relative position of the origin O (global coordinates) with respect to the antennas9and9are previously acquired on the basis of the specifications of the turning work vehicle1, or by measurement carried out in advance. Further, such data is stored in the storage device36a.

FIG.6is a plan view conceptually showing the coordinate system and the turning work vehicle1as inFIG.5. However,FIG.6is different fromFIG.5in that the revolving superstructure3is revolved. InFIG.6, the position of the work machine5when the swing angle θ2is zero is shown by a chain line. Since a turning radius r of the axis a can be previously acquired, the acquired data is stored in the storage device36a. The revolving angle θ1of the revolving superstructure3with respect to the lower traveling body2can be calculated on the basis of the three-dimensional positional information of the antennas9and9, and the data stored in the storage device36a, and processing therefor is performed by the arithmetic unit36b. As long as the information necessary for calculating the revolving angle θ1can be obtained, the location for installing the antennas9and9on the turning work vehicle1is not particularly limited.

First, in a state where the revolving superstructure3is not revolved and the work machine5is not swung (that is, when θ1=0 and θ2=0), as shown inFIG.4and by the chain line inFIG.5, given that the three-dimensional coordinates of the blade edge8E where the position of the axis a on the X-Y plane is a base point are (Xa, Ya, Za), the coordinates (Xa, Ya, Za) can be obtained by the following formula:
Xa=L1 sin α+L2 sin(α+β)+L3 sin(α+β+γ)
Ya=0
Za=L1 cos α+L2 cos(α+β)+L3 cos(α+β+γ)

Next, in a state where the work machine5is swung without revolving the revolving superstructure3(i.e., when θ1=0 and θ2≠0), as shown by a solid line inFIG.5, given that the three-dimensional coordinates of the blade edge8E where the position of the axis a on the X-Y plane is the base point are (Xa1, Ya1, Za1), the coordinates (Xa1, Ya1, Za1) can be obtained by the following formula:

Further, in the state where the revolving superstructure3is revolved (θ1≠0), as shown inFIG.6, given that the three-dimensional coordinates of the axis a where the origin O on the X-Y plane is the starting point are (Xo0, Yo0, Zo0), and that the turning radius of the axis a is r, the coordinates (Xo0, Yo0, Zo0) can be obtained by the following formula:
Xo0=r·cos θ1
Yo0=r·sin θ1
Zo0=0

Furthermore, in a state where the revolving superstructure3is revolved, and the work machine5is not swung (i.e., when θ1≠0 and θ2=0), as shown by the chain line inFIG.6, given that the three-dimensional coordinates of the blade edge8E where the origin O on the X-Y plane is the starting point are (Xo1, Yo1, Zo1), the coordinates (Xo1, Yo1, Zo1) can be obtained by the following formula:

Moreover, in a state where the revolving superstructure3is revolved, and the work machine5is swung (i.e., when θ1≠0 and θ2≠0), as shown by a solid line inFIG.6, given that the three-dimensional coordinates of the blade edge8E where the origin O on the X-Y plane is the starting point are (Xo2, Yo2, Zo2), the coordinates (Xo2, Yo2, Zo2) can be obtained by the following formula:

Therefore, given that the global coordinates of the origin O are (A, B, C), the global coordinates (Xg2, Yg2, Zg2) of the blade edge8E can be obtained by converting the three-dimensional coordinates (Xo2, Yo2, Zo2) of the blade edge8E by the following formula:

As described above, in the present embodiment, the horizontal position (and eventually, the swing angle θ2) of the boom bracket4with respect to the revolving superstructure3is detected by the position detecting device11, and the vertical position (and eventually, angles α, β and γ) of the work machine5with respect to the revolving superstructure3is detected by the position detecting device12, thereby calculating the position of the blade edge8E on the basis of those results of detection. Such arithmetic processing is executed by the arithmetic unit36bwhile the data stored in the storage device36a, and the information transmitted from the receiving device19are being referred to as appropriate. A result of the calculation can be notified to the operator by displaying the result on the display device37, for example.

As described above, according to the present embodiment, in the turning work vehicle1having the boom swing function, the position of the blade edge8E, which is the construction work edge of the work machine5, can be detected with high accuracy. Further, based on the detected position of the blade edge8E, and a mutual positional relationship between the blade edge8E and the side section8S, the position of the side section8S can be calculated by the arithmetic unit36b. The mutual positional relationship between the blade edge8E and the side section8S is previously acquired on the basis of the specifications of the work machine5, or by measurement carried out in advance, and such data is stored in the storage device36a.

[Operation Guidance Given During Construction]

Next, operation guidance given during construction of digging of a side ditch will be described.FIG.7is a flowchart showing operation guidance given during the construction.FIGS.8to10each show a screen of the display device37that is exhibited during the construction. On the screen, the revolving superstructure3, the work machine5, and the bucket8are indicated by icons93,95, and98, respectively. In the present embodiment, the left side of the screen is configured as a display field C1showing the turning work vehicle in a plan view. The turning work vehicle is schematically represented by the revolving superstructure3, and the work machine5including the bucket8. The right side of the screen is configured as a display field C2showing the revolving superstructure3and the work machine5that are separated from each other in a plan view.

First, information about the current position and a posture of the turning work vehicle1is acquired (step S1). The aforementioned information can be acquired from, for example, the three-dimensional positional information of the antenna9and9, and a relative positional relationship between the antenna9and9and the axis, which is the center of revolution, of the revolving superstructure3. Next, positional information of the bucket8, or specifically, the positional information of the blade edge8E of the bucket8is obtained (step S2). As described previously, the above information can be calculated by the arithmetic unit36b, on the basis of the results of detection by the position detecting devices11and12installed on the turning work vehicle1. Then, the predetermined excavation area90where a ditch is to be excavated is set (step S3). The above setting is performed on the screen using the operation panel of the operating device33, for example.

FIG.8shows the state before guidance is displayed. In the display field C1, the current position and the posture of the turning work vehicle1obtained in step S1, and the position of the bucket8obtained in step S2are reflected. When wall-side excavation is to be performed, a wall surface W as shown inFIG.8should preferably be displayed. Information regarding the position and shape of the wall surface W is acquired or generated in advance, and such data is stored in the storage device36a. Alternatively, the wall surface W may be set on the screen using the operation panel. In the display field C2, the revolving superstructure3and the work machine5in the initial state in which the predetermined excavation area90is set are each displayed to be oriented upward on the screen.

In the display field C1, the predetermined excavation area90that has been set in step S3is displayed. In the present embodiment, the side edge of the predetermined excavation area90is displayed by a virtual line VL extending in an extending direction (i.e., a vertical direction inFIG.8) of the predetermined excavation area90. The side edge refers to the one located on the outer side in a width direction of the turning work vehicle1of a pair of side edges defining the predetermined excavation area90. By displaying the side edge of the predetermined excavation area90in this way, it is possible to effectively assist the operation of the operator. However, the element to be displayed is not limited to the above. That is, a center line of the predetermined excavation area90may be displayed, or the predetermined excavation area90may be displayed as a belt-like area having a predetermined width.

The display device37displays the positional relationship between the bucket8and the predetermined excavation area90as shown inFIG.8, and the positional relationship can be observed by the icon98and the virtual line VL in the present embodiment. In order to excavate a ditch in the predetermined excavation area90, having ensured a state (hereinafter referred to as a “set state”) in which the side section8S of the bucket8is aligned with the virtual line VL, which is the side edge of the predetermined excavation area90, it is necessary to make the work machine5perform an excavation operation. In order to shift the state from the initial state ofFIG.8to the set state, the posture of the turning work vehicle must be changed by making full use of the revolving operation of the revolving superstructure3and the swing operation of the work machine5, and a high manipulation skill is required for the operator.

Therefore, in the display system50, in order to serve for operational assistance for construction, the arithmetic unit36bcalculates the necessary revolving amount of the revolving superstructure3and the necessary offset amount of the work machine5that are needed to align the side section8S of the bucket8with the side edge of the predetermined excavation area90(step S4). The necessary revolving amount can be rephrased as the revolving angle of the revolving superstructure3that is necessary to shift to the set state. Also, the necessary offset amount can be rephrased as the swing angle of the work machine5that is necessary to shift to the set state in the present embodiment. As described above, the arithmetic unit36bobtains by computation the revolving angle of the revolving superstructure3, and the swing angle of the work machine5that are suitable for digging a side ditch.

The display device37displays information for informing about an operation amount of the revolving superstructure3according to the necessary revolving amount, and an operation amount of the work machine5according to the necessary offset amount (step S5).FIG.9is an example of a guidance screen displaying such information. In the display field C1, icons93sand95sindicating the revolving superstructure3and the work machine5in the set state are displayed. In the display field C2, an icon93gof the revolving superstructure3for informing about the revolution that is necessary to shift to the set state, and an icon95gof the work machine5for the same purpose are displayed. In this example, the operator is informed that the revolving superstructure3must be revolved to the right, and the work machine5must be swung to the left.

In the icon93gin the display field C2shown inFIG.9, a revolving angle θ3, which is the operation amount of the revolving superstructure3according to the necessary revolving amount that has been calculated, is reflected. Similarly, in the icon95g, a swing angle θ4, which is the operation amount of the work machine5according to the necessary offset amount that has been calculated, is reflected. The operator can visually recognize how much the revolving superstructure3should be revolved to the right, in view of the positional relationship between the icon93and the icon93g. Also, the operator can visually recognize how much the work machine5should be swung to the left, in view of the positional relationship between the icon95and the icon95g. Numerical values of the revolving angle θ3and the swing angle θ4, and the display of arrows A3and A4may be omitted as appropriate. In addition, visual effects may be enhanced by using light, or an acoustic effect may be added by using sound.

When the operator revolves the revolving superstructure3and/or swings the work machine5, the positional information of (the blade edge8E of) the bucket8according to such an operation is obtained (step S6), and whether the bucket8has come into contact with the virtual line VL is determined (step S7). If the bucket8is not in contact with the virtual line VL, the positions of the revolving superstructure3and the work machine5are displayed on the screen (in the display field C1) (step S8), and the positional information of the bucket8is continuously obtained. If the bucket8has come into contact with the virtual line VL, a further revolving operation of the revolving superstructure3is prohibited (step S9).

FIG.10shows an example of the screen when the bucket8has come into contact with the virtual line VL. If the revolving superstructure3is revolved to the right from this state, the bucket8will collide with the wall surface W. Thus, clockwise turning of the revolving superstructure3is restricted in order to prevent the collision. For the same reason, it is also possible to restrict rightward swing operation of the work machine5. The display system50is provided with the safety device36c(seeFIG.3), which restricts revolution of the revolving superstructure3and an offset (a swing in the present embodiment) of the work machine5so that the bucket8does not cross over the side edge of the predetermined excavation area90. The safety device36csends a signal to the main unit controller34when the bucket8has come into contact with the virtual line VL, and executes restriction of the revolution and offset as described above. In addition to prohibition of the revolving operation, the screen may be blinked or a sound effect may be produced, for example, to notify the operator of the fact that the bucket8is in contact with the virtual line VL.

When the bucket8is in contact with the virtual line VL, the display device37displays that the revolution of the revolving superstructure3is restricted, and information for informing about the swing angle of the work machine5that is necessary to shift to the set state, as shown inFIG.10(step S10). By operating the revolving superstructure3and the work machine5in accordance with such instructions on the screen, it is possible to achieve the set state in which the side section8S of the bucket8is aligned with the virtual line VL without making the bucket8collide with the wall surface W. As described above, the display system50provides the operator with information useful for construction of digging of a side ditch, such as in which direction and how much the revolving superstructure3should be revolved, and in which direction and how much the work machine5should be swung.

In the present embodiment, the display device37displays the revolving superstructure3, and the work machine5extending from the front end portion of the revolving superstructure3. However, the display is not limited to the above, and the other screen layout can alternatively be adopted. However, it is preferable that the display device37should display at least the bucket8and the predetermined excavation area90in a plan view. The plan view may be a view seen from above along the axial direction of central axis of revolution of the revolving superstructure3. Also, the display of the predetermined excavation area90may be indicated by only the side edge.

In the present embodiment, an example in which the offset of the work machine is performed by swinging the work machine to right and left with respect to the revolving superstructure is described. However, the offset is not limited to the aforementioned example. That is, the offset may be performed by translating (the arm or the boom of) the work machine to the right and left with respect to the revolving superstructure. Such a turning work vehicle is disclosed in, for example, Japanese Unexamined Patent Application No. Hei 8-326086 A or Japanese Unexamined Patent Application No. 2011-184965 A, the applications of which were filed by the present applicant. In that case, the position of the bucket, and the necessary offset amount of the work machine may be calculated, on the basis of an actuation amount of an actuator (for example, the expansion/contraction amount of the cylinder) which translates the work machine to the right and left, instead of the swing angle of the work machine described above (i.e., the swing angle of the boom bracket).

In the present embodiment, an example of calculating a three-dimensional position of a blade edge of the bucket is described. However, the calculation is not limited to the above, and a two-dimensional position may be obtained by calculation. For example, the position of the blade edge of the bucket when the predetermined excavation area is set may be assumed as a work start point, and the necessary revolving amount and the necessary offset amount as described above may be calculated in consideration of the mutual positional relationship between the position of the blade edge and the predetermined excavation area. In that case, since the global coordinates do not need to be used, the GPS antennas can be omitted. In that event, a configuration may be made to detect a revolving angle of the revolving superstructure with respect to the lower traveling body by a position sensor (for example, an angle sensor) installed on the revolving superstructure.

The present invention is in no way limited to the embodiment described above, and various improvements and modifications can be made within the scope not departing from the spirit of the present invention.

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