Patent Publication Number: US-2023160181-A1

Title: Display system, program, and display control method

Description:
TECHNICAL FIELD 
     The present disclosure relates to a display system, a program, and a display control method. 
     BACKGROUND ART 
     When work is performed by a working machine such as a hydraulic excavator, an operator needs to cause the working machine (particularly, a working implement of the working machine) to face a target topography (target construction surface). In order to support such an operation of the operator, the working machine that displays a facing compass is known, for example, as disclosed in Japanese Patent Laying-Open No. 2019-105160 (PTL 1). 
     The working machine of PTL 1 displays posture information such as a picture or an icon, which guides a facing direction with respect to the target topography and a direction in which the hydraulic excavator should be turned, on a display as the facing compass. 
     CITATION LIST 
     Patent Literature 
     PTL 1: Japanese Patent Laying-Open No. 2019-105160 
     SUMMARY OF INVENTION 
     Technical Problem 
     A relationship between the direction of the working implement of the working machine and the direction of the target topography from the working machine is desirably provided in a visually more understandable manner in order to support the operator of the working machine. 
     An object of the present disclosure is to provide a display system, a program, and a method for controlling the display system capable of providing the relationship between the direction of the working implement of the working machine and the direction of the target topography in the visually more understandable manner. 
     Solution to Problem 
     A display system according to one aspect of the present disclosure includes a display and a controller. The controller causes the display to display a third figure representing a relative relationship between a first figure and a second figure, the first figure indicating a direction of a working implement of a working machine, and the second figure indicating a direction of a target topography from the working machine. 
     A display system according to another aspect of the present disclosure includes a display and a controller. The controller causes the display to display an image indicating a working machine, a straight line extended from a working implement of the working machine, and a straight line connecting the image indicating the working machine and a target topography in top view of the working machine. 
     A program according to still another aspect of the present disclosure that causes a processor of a controller to execute: generating a first figure indicating a direction of a working implement of a working machine; generating a second figure indicating a direction of a target topography from the working machine; generating a third figure representing a relative relationship between the first figure and the second figure; and causing a display to display the third figure. 
     A display control method according to yet another aspect of the present disclosure, the display control method includes the following steps. 
     A first figure indicating a direction of a working implement of a working machine is generated. A second figure indicating a direction of a target topography from the working machine is generated. A third figure representing a relative relationship between the first figure and the second figure is generated. The third figure is displayed on a display. 
     Advantageous Effects of Invention 
     According to the present disclosure, the display system, the program, and the display system control method capable of providing the relationship between the direction of the working implement of the working machine and the direction of the target topography in the visually more understandable manner. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG.  1    is a perspective view illustrating a configuration of a hydraulic excavator as an example of a working machine according to an embodiment. 
         FIG.  2    is a side view of the hydraulic excavator. 
         FIG.  3    is a rear view of the hydraulic excavator. 
         FIG.  4    is a block diagram illustrating a control system included in a display system of the embodiment. 
         FIG.  5    is a view illustrating a construction topography and a target topography. 
         FIG.  6    is a view illustrating an image in which a support image is displayed with a hydraulic excavator  100  as a center in a top view of the hydraulic excavator as a first example of a support screen displayed on a display. 
         FIG.  7    is a view illustrating an image in which the support image is displayed with the hydraulic excavator  100  as a center in a bird&#39;s-eye view of the hydraulic excavator as a second example of the support screen displayed on the display. 
         FIGS.  8 (A) to  8 (E)  are views illustrating a method for generating the support image in order of steps. 
         FIGS.  9 (A) to  9 (F)  are views illustrating the method for generating the support image in a side view of the hydraulic excavator in the order of steps subsequent to the steps in  FIG.  8   . 
         FIG.  10    is a flowchart illustrating a method for controlling the display system in the embodiment. 
         FIG.  11    is a view illustrating an image in which another support image is displayed with the hydraulic excavator as a center in the top view of the hydraulic excavator as a modification example of the support image displayed on the display. 
     
    
    
     DESCRIPTION OF EMBODIMENT 
     Hereinafter, an embodiment of the present disclosure will be described in detail with reference to the drawings. In the specification and the drawings, the same components or corresponding components are denoted by the same reference numerals, and redundant description will not be repeated. In the drawings, the configuration may be omitted or simplified for convenience of description. In addition, at least a part of the embodiment and each modification may be arbitrarily combined with each other. 
     &lt;Overall Configuration of Working Machine&gt; 
     With reference to  FIG.  1   , a configuration of a hydraulic excavator as an example of a working machine to which the idea of the present disclosure can be applied will be described. The present disclosure is also applicable to a working machine having an excavation tool other than the following hydraulic excavator. 
     In the following description, a front-rear direction is a front-rear direction of the operator seated on a driver&#39;s seat  4 S in an operator cab  4  in  FIG.  1   . A direction facing the operator seated on driver&#39;s seat  4 S is a forward direction, and a direction behind the operator seated on driver&#39;s seat  4 S is a backward direction. A left-right direction is a left-right direction of the operator seated on driver&#39;s seat  4 S. A right side and a left side when the operator sits on driver&#39;s seat  4 S faces a front are a right direction and a left direction, respectively. A vertical direction is a direction orthogonal to a plane defined by the front-back direction and the left-right direction. In the vertical direction, a side on which the ground exists is a lower side, and a side on which the sky exists is an upper side. 
       FIG.  1    is a perspective view illustrating the configuration of the hydraulic excavator as an example of the working machine according to an embodiment.  FIGS.  2  and  3    are a side view and a rear view of the hydraulic excavator. 
     As illustrated in  FIG.  1   , a hydraulic excavator  100  as the working machine in the embodiment includes a machine body  1  and a working implement  2  as a main body. Machine body  1  includes a revolving body  3  and a traveling device  5 . Revolving body  3  accommodates devices such as a power generator and a hydraulic pump (not illustrated) in a machine chamber  3 EG. Machine chamber  3 EG is disposed on a rear end side of revolving body  3 . 
     For example, hydraulic excavator  100  includes an internal combustion engine such as a diesel engine as a power generation device, but hydraulic excavator  100  is not limited to such the internal combustion engine. For example, hydraulic excavator  100  may include what is called a hybrid type power generation device in which the internal combustion engine, a generator motor, and a power storage device are combined. 
     Revolving body  3  includes operator cab  4 . Operator cab  4  is mounted on a front end side of revolving body  3 . Operator cab  4  is disposed on a side opposite to a side where machine chamber  3 EG is disposed. A display input device  38  and an operation device  25  are disposed in operator cab  4  (see  FIG.  4   ). These will be described later. 
     Traveling device  5  is disposed below revolving body  3 . Traveling device  5  includes crawler belts  5   a,    5   b.  Traveling device  5  causes hydraulic excavator  100  to travel by a hydraulic motor  5   c  rotationally driving crawler belts  5   a,    5   b.  Hydraulic excavator  100  may have tires instead of crawler belts  5   a,    5   b,  or may be a wheel type hydraulic excavator. 
     A handrail  9  is provided on revolving body  3 . Two GNSS antennas  21 ,  22  for real time kinematic-global navigation satellite systems (RTK-GNSS) are detachably attached to handrail  9 . 
     For example, GNSS antennas  21 ,  22  are installed at a certain distance from each other along an axis parallel to a Ya-axis of a machine body coordinate system [Xa, Ya, Za]. GNSS antennas  21 ,  22  may be installed at a certain distance from each other along the axis parallel to an Xa-axis of machine body coordinate system [Xa, Ya, Za]. 
     GNSS antennas  21 ,  22  are preferably installed at positions as far away from each other as possible from the viewpoint of improving detection accuracy of the current position of hydraulic excavator  100 . In addition, GNSS antennas  21 ,  22  are preferably installed at positions that do not obstruct a field of view of the operator as much as possible. GNSS antennas  21 ,  22  may be installed on revolving body  3  and behind a counterweight  3 CW or operator cab  4 . 
     Working implement  2  is attached to a lateral side of operator cab  4  of revolving body  3 . Working implement  2  includes a boom  6 , an arm  7 , a bucket  8 , a boom cylinder  10 , an arm cylinder  11 , and a bucket cylinder  12 . A base end of boom  6  is rotatably attached to the front of machine body  1  through a boom pin  13 . A base end of arm  7  is rotatably attached to a tip of boom  6  through an arm pin  14 . Bucket  8  is attached to the distal end of arm  7  through a bucket pin  15 . 
     Bucket  8  includes a plurality of blades  8 B. The plurality of blades  8 B are attached to an end of bucket  8  on the side opposite to the side on which bucket pin  15  is attached. The plurality of blades  8 B are attached to the end of bucket  8  farthest from the side to which bucket pin  15  is attached. The plurality of blades  8 B are arrayed in a row in the direction parallel to bucket pin  15 . Blade edge  8 T is the tip of blade  8 B. Blade edge  8 T is the tip of bucket  8  at which working implement  2  generates excavation force. The direction parallel to a straight line connecting the plurality of blade edges  8 T is a width direction of bucket  8 . The width direction of bucket  8  is matched with the width direction of revolving body  3 , namely, the left-right direction of revolving body  3 . 
     Bucket  8  is coupled to bucket cylinder  12  through a pin  16 . Bucket cylinder  12  expands and contracts to rotate bucket  8 . Bucket  8  rotates about an axis orthogonal to the extending direction of arm  7 . Boom pin  13 , arm pin  14 , and bucket pin  15  are disposed in a positional relationship parallel to each other. That is, center axes of the pins are parallel to each other. 
     Each of boom cylinder  10 , arm cylinder  11 , and bucket cylinder  12  is a hydraulic cylinder. Each of boom cylinder  10 , arm cylinder  11 , and bucket cylinder  12  operates by adjusting the expansion and contraction and speed according to pressure or a flow rate of a hydraulic oil. 
     Boom cylinder  10  operates boom  6 , and vertically rotates boom  6  about the center axis of boom pin  13 . Arm cylinder  11  operates arm  7 , and rotates arm  7  about the center axis of arm pin  14 . Bucket cylinder  12  operates bucket  8 , and rotates bucket  8  about the center axis of bucket pin  15 . 
     The excavation tool of the hydraulic excavator  100  is not limited to the bucket  8 , but may be another excavation tool such as a breaker. 
     As illustrated in  FIG.  2   , a length of boom  6  (a length between boom pin  13  and arm pin  14 ) is L 1 . The length of arm  7  (the length from the center axis of arm pin  14  to a center axis AX 1  of bucket pin  15 ) is L 2 . The length of bucket  8  (the length from center axis AX 1  of bucket pin  15  to blade edge  8 T) is L 3 . The length of bucket  8  is the length along an axis AX 3  orthogonal to center axis AX 1  of bucket pin  15  and passing through blade edge  8 T of bucket  8 . 
     An inertial measurement unit (IMU)  18 A is disposed on boom  6 . An IMU  18 B is disposed in arm  7 . An IMU  18 C is disposed in bucket  8 . Each of IMUs  18 A,  18 B,  18 C is a working implement posture sensor that detects a posture of working implement  2 . Each of IMUs  18 A,  18 B,  18 C detects a triaxial angle (or angular velocity) and acceleration. 
     The postures of boom  6 , arm  7 , and bucket  8  can be detected from the triaxial angles (or angular velocities) and accelerations detected by IMUs  18 A,  18 B,  18 C. Specifically, an inclination angle θ 1  of boom  6  with respect to the Za-axis of the machine body coordinate system described later can be calculated from the triaxial angle (or angular velocity) and acceleration detected by IMU  18 A. An inclination angle θ 2  of arm  7  with respect to boom  6  can be calculated from the triaxial angle (or angular velocity) and acceleration detected by IMU  18 B. An inclination angle θ 3  of bucket  8  with respect to arm  7  can be calculated from the triaxial angle (or angular velocity) and acceleration detected by IMU  18 C. 
     The working implement posture sensor is not limited to the IMU, but may be a stroke sensor, a potentiometer, an imaging device, or the like. The working implement posture sensors may be hydraulic sensors  37 SBM,  37 SBK,  37 SAM in  FIG.  4   . 
     Machine body  1  includes a position detector  19 . Position detector  19  detects the current position of hydraulic excavator  100 . Position detector  19  includes GNSS antennas  21 ,  22 , an inclination angle sensor  24 , and a controller  39 . Position detector  19  may include a three-dimensional position sensor. 
     Revolving body  3  and working implement  2  rotate with respect to traveling device  5  about a predetermined revolving center axis. Machine body coordinate system [Xa, Ya, Za] is a coordinate system of machine body  1 . In the embodiment, in machine body coordinate system [Xa, Ya, Za], a revolving center axis of working implement  2  or the like is defined as the Za-axis, an axis orthogonal to the Za-axis and parallel to an operation plane of working implement  2  is defined as the Xa-axis, and an axis orthogonal to the Za-axis and the Xa-axis is defined as the Ya-axis. For example, the operation plane of working implement  2  is a plane orthogonal to boom pin  13 . The Xa-axis corresponds to the front-rear direction of revolving body  3 , and the Ya-axis corresponds to the width direction of revolving body  3 . 
     A signal corresponding to a GNSS radio wave received by each of antennas  21 ,  22  is input to controller  39 . GNSS antenna  21  receives reference position data P 1  indicating an own installation position from a positioning satellite. GNSS antenna  22  receives reference position data P 2  indicating the own installation position from the positioning satellite. For example, GNSS antennas  21 ,  22  receive reference position data P 1 , P 2  at a cycle of 10 Hz. Reference position data P 1 , P 2  are information about the position where the GNSS antenna is installed. Each time GNSS antennas  21 ,  22  receive reference position data P 1 , P 2 , GNSS antennas  21 ,  22  output reference position data P 1 , P 2  to controller  39 . 
     As illustrated in  FIG.  3   , inclination angle sensor  24  is attached to revolving body  3 . Inclination angle sensor  24  detects an inclination angle θ 4  of the width direction of machine body  1  with respect to the direction in which gravity acts, namely, vertical direction Ng. For example, inclination angle sensor  24  may be the IMU. 
     IMUs  18 A,  18 B,  18 C, GNSS antennas  21 ,  22 , inclination angle sensor  24 , display input device  38 , and controller  39  may be added to hydraulic excavator  100  as a retrofitted kit. Hereinafter, the hydraulic excavator equipped with the retrofitted kit is referred to as the hydraulic excavator  100 , and the hydraulic excavator not equipped with the retrofitted kit is referred to as a hydraulic excavator  100   a.    
     &lt;Display System&gt; 
     With reference to  FIGS.  4  and  5   , a display system of the embodiment will be described below. In the embodiment, the display system in the case where a retrofitted kit  100   b  is mounted on hydraulic excavator  100   a  later will be described as an example of the display system. 
     However, the display system of the present disclosure includes not only the case where retrofitted kit  100   b  is retrofitted to hydraulic excavator  100   a  after sale of hydraulic excavator  100   a,  but also the case where retrofitted kit  100   b  is mounted on hydraulic excavator  100   a  from the beginning of the sale of hydraulic excavator  100 . 
       FIG.  4    is a block diagram illustrating a control system included in the display system of the embodiment.  FIG.  5    is a view illustrating a construction topography and a target topography. As illustrated in  FIG.  4   , a display system  101  of the embodiment is a system that provides information constructing the construction topography in  FIG.  5    for the operator during the excavation using hydraulic excavator  100 , and supports the operation of the operator. Display system  101  includes hydraulic excavator  100   a,  retrofitted kit  100   b,  and a server  40 . 
     Hydraulic excavator  100   a  includes operation device  25 , a working implement electronic control device  26 , a working machine control device  27 , and a hydraulic pump  47 . 
     Operation device  25  is a device that operates the operation of working implement  2  ( FIG.  1   ) and the traveling of hydraulic excavator  100 . Operation device  25  includes working implement operation members  31 L,  31 R, traveling operation members  33 L,  33 R, working implement operation detectors  32 L,  32 R, and traveling operation detectors  34 L,  34 R. For example, working implement operation members  31 L,  31 R and traveling operation members  33 L,  33 R are pilot-pressure type levers, but are not limited thereto. For example, working implement operation members  31 L,  31 R and traveling operation members  33 L,  33 R may be electric type levers. 
     Working implement operation detectors  32 L,  32 R function as operation detectors that detect inputs to working implement operation members  31 L,  31 R as operation units. Traveling operation detectors  34 L,  34 R function as operation detectors that detect inputs to traveling operation members  33 L,  33 R as operation units. 
     Working machine control device  27  is a hydraulic device including a hydraulic control valve and the like. Working machine control device  27  drives and controls boom cylinder  10 , arm cylinder  11 , bucket cylinder  12 , a revolving motor, and hydraulic motor  5   c  based on the operation in operation device  25 . 
     Working machine control device  27  includes a traveling control valve  37 D and a working control valve  37 W. For example, each of traveling control valve  37 D and working control valve  37 W is a proportional control valve. Traveling control valve  37 D is controlled by the pilot pressure from traveling operation detectors  34 L,  34 R. Working control valve  37 W is controlled by the pilot pressure from working implement operation detectors  32 L,  32 R. 
     Working machine control device  27  includes hydraulic sensors  37 Slf,  37 Slb,  37 Srf,  37 Srb. Each of hydraulic sensors  37 Slf,  37 Slb,  37 Srf,  37 Srb detects magnitude of the pilot pressure supplied to traveling control valve  37 D and generates a corresponding electric signal. Hydraulic sensors  37 Slf,  37 Slb,  37 Srf, and  37 Srb function as operation detectors that detect inputs to traveling operation members  33 L,  33 R as operation units. 
     Hydraulic sensor  37 Slf detects the pilot pressure for leftward forward movement. Hydraulic sensor  37 Slb detects the pilot pressure for leftward backward movement. Hydraulic sensor  37 Srf detects the pilot pressure for rightward forward movement. Hydraulic sensor  37 Srb detects the pilot pressure for rightward backward movement. 
     When the operator operates traveling operation members  33 L,  33 R, the hydraulic oil having a flow rate corresponding to the pilot pressure generated in response to the operation flows out from traveling control valve  37 D. The hydraulic oil flowing out of traveling control valve  37 D is supplied to hydraulic motor  5   c  of traveling device  5 . Thus, crawler belts  5   a,    5   b  are rotationally driven. 
     Working machine control device  27  includes hydraulic sensors  37 SBM,  37 SBK,  37 SAM,  37 SRM. Each of hydraulic sensors  37 SBM,  37 SBK,  37 SAM,  37 SRM detects the magnitude of the pilot pressure supplied to working control valve  37 W and generates a corresponding electric signal. Hydraulic sensors  37 SBM,  37 SBK,  37 SAM,  37 SRM function as operation detectors that detect inputs to working implement operation members  31 L,  31 R as operation units. 
     Hydraulic sensor  37 SBM detects the pilot pressure corresponding to boom cylinder  10 . Hydraulic sensor  37 SAM detects the pilot pressure corresponding to arm cylinder  11 . Hydraulic sensor  37 SBK detects a pilot pressure corresponding to bucket cylinder  12 . Hydraulic sensor  37 SRM detects the pilot pressure corresponding to the revolving motor. 
     When the operator operates working implement operation members  31 L,  31 R, the hydraulic oil having a flow rate corresponding to the pilot pressure generated in response to the operation flows out of working control valve  37 W. The hydraulic oil flowing out of working control valve  37 W is supplied to at least one of boom cylinder  10 , arm cylinder  11 , bucket cylinder  12 , and revolving motor. Thus, cylinders  10 ,  11 ,  12  expand and contract, and the revolving motor is revolved. 
     Working implement electronic control device  26  acquires the electric signal indicating the magnitude of the pilot pressure generated by working machine control device  27 . Working implement electronic control device  26  controls the engine and the hydraulic pump based on the acquired electric signal. In addition, working implement electronic control device  26  outputs the acquired electric signal to controller  39  in order to generate the support image described later. For example, when the hydraulic sensors  37 SBM,  37 SBK,  37 SAM are used as the working implement posture sensors, working implement electronic control device  26  outputs the acquired electric signals of hydraulic sensors  37 SBM,  37 SBK,  37 SAM to controller  39 . Controller  39  and working implement electronic control device  26  can communicate with each other by wireless or wired communication means. 
     Working implement operation members  31 L,  31 R and traveling operation members  33 L,  33 R may be electric type levers. In this case, working implement electronic control device  26  generates a control signal in order to operate working implement  2 , revolving body  3 , or traveling device  5  according to the operation of working implement operation members  31 L,  31 R or traveling operation members  33 L,  33 R, and outputs the control signal to working machine control device  27 . 
     Working control valve  37 W and traveling control valve  37 D of working machine control device  27  are controlled based on the control signal from working implement electronic control device  26 . The hydraulic oil having the flow rate according to the control signal from working implement electronic control device  26  flows out of working control valve  37 W, and is supplied to at least one of boom cylinder  10 , arm cylinder  11 , and bucket cylinder  12 . Consequently, working implement  2  operates. In addition, the hydraulic oil having the flow rate according to the control signal from working implement electronic control device  26  flows out from traveling control valve  37 D and is supplied to hydraulic motor  5   c.  Consequently, traveling device  5  operates. 
     Working implement electronic control device  26  includes a working implement-side storage  35  including at least one of a random access memory (RAM) and a read only memory (ROM) and an arithmetic unit  36  such as a central processing unit (CPU). Working implement electronic control device  26  mainly controls the operations of working implement  2  and revolving body  3 . Working implement-side storage  35  stores information such as a computer program controlling working implement  2 . 
     Although working implement electronic control device  26  and controller  39  are separated from each other, the present invention is not limited to such the form. Working implement electronic control device  26  and controller  39  may be integrated without being separated. 
     Retrofitted kit  100   b  is mounted on hydraulic excavator  100  in order to implement display system  101 . Retrofitted kit  100   b  includes IMUS  18 A,  18 B,  18 C, GNSS antennas  21 ,  22 , inclination angle sensor  24 , display input device  38 , and controller  39 . 
     Controller  39  performs various functions of display system  101 . Controller  39  includes a storage  43  and a processing unit  44 . Storage  43  includes at least one of the RAM and the ROM. Processing unit  44  includes the CPU and the like. 
     Storage  43  stores working implement data. Working implement data includes a length L 1  of boom  6 , a length L 2  of arm  7 , a length L 3  of bucket  8 , and the like. When bucket  8  is replaced, a value corresponding to the size of replaced bucket  8  is input from input unit  41  and stored in storage  43  as length L 3  of bucket  8  for working implement data. 
     The working implement data includes the minimum value and the maximum value of each of inclination angle θ 1  of boom  6 , inclination angle θ 2  of arm  7 , and inclination angle θ 3  of bucket  8 . Storage  43  stores an image display computer program, information about the coordinate of the machine body coordinate system, and the like. 
     The image display computer program may not be stored in storage  43  but may be stored in server  40 . For example, server  40  is connected to controller  39  through the Internet line. In this case, in response to a request from the operator who operates hydraulic excavator  100 , controller  39  accesses server  40  to execute the image display computer program stored in server  40 . Then, the image as a result of the execution is displayed on a display  42  through the Internet line. 
     GNSS correction information may be transmitted from server  40  to controller  39  through the Internet line. Furthermore, a construction history by hydraulic excavator  100  may be transmitted from controller  39  to server  40  through the Internet line. 
     Storage  43  stores previously-prepared construction topography data. The construction topography data is information about the shape and position of the three-dimensional construction topography. 
     As illustrated in  FIG.  5   , the construction topography indicates a target shape of the ground that becomes a working target. The construction topography is constructed with a plurality of design surfaces  71  each of which is represented by a triangular polygon. 
     The working target is at least one of design surfaces  71 . The operator selects at least one of design surfaces  71  as a target topography  70 . Target topography  70  is a surface to be excavated from among the plurality of design surfaces  71 . Target topography  70  indicates the target shape of a working target. 
     As illustrated in  FIG.  4   , processing unit  44  reads and executes the image display program stored in storage  43  or server  40 . Thus, processing unit  44  causes display  42  to display the support screen. 
     Controller  39  acquires two reference position data P 1 , P 2  (a plurality of pieces of reference position data) represented in the global coordinate system from GNSS antennas  21 ,  22 . Controller  39  generates revolving body disposition data indicating the disposition of revolving body  3  based on two reference position data P 1 , P 2 . 
     Revolving body disposition data includes one reference position data P of two reference position data P 1 , P 2  and revolving body orientation data Q generated based on two reference position data P 1 , P 2 . In revolving body orientation data Q, an orientation determined from reference position data P acquired by GNSS antennas  21 ,  22  is determined based on an angle relative to a reference orientation (for example, north) of a global coordinate. 
     Revolving body orientation data Q indicates the direction on which revolving body  3  faces (the orientation to which working implement  2  faces). Controller  39  updates the revolving body disposition data, namely, reference position data P and revolving body orientation data Q each time two reference position data P 1 , P 2  are acquired from GNSS antennas  21 ,  22  at a frequency of, for example, 10 Hz. 
     Controller  39  acquires detection information about boom  6 , arm  7 , and bucket  8  from IMUS  18 A,  18 B,  18 C. Controller  39  calculates the attitude of working implement  2  based on the detection information about IMUS  18 A,  18 B,  18 C. Specifically, controller  39  calculates inclination angle θ 1  of boom  6  based on the detection information about IMU  18 A, calculates inclination angle θ 2  of arm  7  based on the detection information about IMU  18 B, and calculates inclination angle θ 3  of bucket  8  based on the detection information about IMU  18 C. 
     When hydraulic sensors  37 SBM,  37 SBK,  37 SAM are used as the working implement posture sensors, working implement posture sensors  18 A,  18 B,  18 C may be omitted from retrofitted kit  100   b.  When hydraulic sensors  37 SBM,  37 SBK,  37 SAM are used as the working implement posture sensors, processing unit  44  of controller  39  calculates inclination angles θ 1 , θ 2 , θ 3  based on the electric signals indicating the magnitudes of the pilot pressures detected by hydraulic sensors  37 SBM,  37 SBK,  37 SAM. 
     Controller  39  acquires inclination information about machine body  1  from inclination angle sensor  24 . As illustrated in  FIG.  3   , the inclination information is an inclination angle θ 4  of the width direction of machine body  1  with respect to vertical direction Ng. 
     As described above, processing unit  44  of controller  39  can calculate the relative position of hydraulic excavator  100  with respect to the target topography and the posture of working implement  2 . Thus, processing unit  44  can display information about the positional relationship between bucket  8  being excavated and the target topography, posture information guiding the operator to the operation of bucket  8 , and the like on display  42 . 
     Display input device  38  includes input unit  41 , display  42 , and storage  45 . For example, input unit  41  is a button, a keyboard, a touch panel, or a combination thereof. For example, display  42  is a liquid crystal display (LCD) or an organic electro luminescence (EL) display. For example, storage  45  stores an application (software) reading and executing the image display computer program. 
     Display input device  38  is connected to controller  39  in a wireless or wired manner. Display input device  38  and controller  39  are wirelessly connected by, for example, Wi-Fi (registered trademark), BLUETOOTH (registered trademark), or Wi-SUN (registered trademark). 
     Display input device  38  may not be included in the above-described retrofitted kit. In this case, the user may substitute an own information portable terminal (smartphone, tablet, personal computer, and the like) as display input device  38 . In addition, a display device existing in hydraulic excavator  100  may be substituted as display input device  38 . 
     Display input device  38  displays the support screen providing information to the operator in order to perform the excavation using working implement  2 . Also, various keys are displayed on the support screen. The operator can perform various functions of display system  101  by touching various keys on the support screen. The support screen will be described later. 
     &lt;Support Screen&gt; 
     With reference to  FIGS.  6  and  7   , first and second examples of the support screen displayed on display  42  in the display system of the embodiment will be described below. 
       FIG.  6    is a view illustrating an image in which a support image is displayed with hydraulic excavator  100  as a center in a top view of the hydraulic excavator as the first example of the support screen displayed on the display.  FIG.  7    is a view illustrating an image in which the support image is displayed with hydraulic excavator  100  as a center in a bird&#39;s-eye view of the hydraulic excavator as the second example of the support screen displayed on the display. 
     As illustrated in  FIG.  6   , the first example of the support screen includes an image  100 G (hereinafter, referred to as image  100 G of the hydraulic excavator) illustrating hydraulic excavator  100 , an image  79  of the construction topography including target topography  70 , and a support image  50 . Image  100 G of the hydraulic excavator is an image of the top view of hydraulic excavator  100  (the image viewed from above the hydraulic excavator  100 ). 
     Controller  39  superimposes image  100 G of the hydraulic excavator on the construction topography, and displays the superimposed image on display  42 . Controller  39  displays image  100 G of the hydraulic excavator on the construction topography based on the positional information indicating the current position of hydraulic excavator  100 . Image  100 G of the hydraulic excavator includes an image  2 G (hereinafter, referred to as image  2 G of the working implement) indicating working implement  2 . 
     Controller  39  causes display  42  to display target topography  70  selected by the operator in the construction topography in a mode different from the construction topography that is not selected in the construction topography. For example, controller  39  changes a display color of the target topography from a default color. Thus, the operator can easily know the position of the target topography. 
     Controller  39  causes display  42  to display support image  50  while support image  50  is superimposed on the construction topography. Support image  50  includes a first  figure  51    indicating the direction of working implement  2  (image  2 G of the working implement), a second  figure  52    indicating the direction of target topography  70  from hydraulic excavator  100  (image  100 G of the hydraulic excavator), and a third  figure  53    representing the relative relationship between first  figure  51    and second  figure  52   . In this example, the direction of working implement  2  (image  2 G of the working implement) is the direction of the neutral axis of working implement  2 . The direction of working implement  2  is the direction from the attachment position of working implement  2  to bucket  8  in machine body  1 . 
     As described above, because at least third  figure  53    is displayed on display  42 , according to display system  101 , the operator can more easily visually understand the relationship between the direction of the working implement of hydraulic excavator  100  and the direction of the target topography from hydraulic excavator  100 . According to display system  101 , when the operator moves hydraulic excavator  100  in the direction of target topography  70 , the direction of the working implement  2  can be guided for the operator so as to approach the direction of target topography  70 . 
     For example, first  figure  51    is both or one of a straight line  51   a  and a  figure  51   b    having a home base shape (pentagonal shape). Straight line  51   a  is a straight line superimposed on a virtual straight line along the neutral axis of working implement  2 . Straight line  51   a  is a straight line extended from bucket  8 . A corner  51   bt  of  figure  51   b    having the home base shape is located on the virtual straight line along the neutral axis of the working implement  2 .  Figure  51   b    may have a polygonal shape such as a triangle or a circular shape such as a circle or an ellipse as long as the direction of working implement  2  of the hydraulic excavator  100  can be specified. 
     For example, second  figure  52    is both or one of a straight line  52   a  and a  figure  52   b   . Straight line  52   a  is a straight line superimposed on a straight line  55  connecting target topography  70  and image  100 G of the hydraulic excavator. In this example,  figure  52   b    has a shape in which two pentagons having line symmetry face each other. 
     The shape of  figure  52   b    is not particularly limited as long as the direction of target topography  70  can be specified from hydraulic excavator  100 , and may be a triangle, a polygon such as a home base, or a circular shape such as a circle or an ellipse. 
     The controller may display one of straight line  51   a  and  figure  51   b    on display  42  as a figure indicating the direction of working implement  2  (image  2 G of the working implement). Similarly, the controller may display any one of straight line  52   a  and  figure  52   b    on display  42  as a figure indicating the direction of target topography  70  from hydraulic excavator  100  (image  100 G of the hydraulic excavator). 
     Third  figure  53    is a figure representing a relative relationship between first  figure  51    and second  figure  52   . Third  figure  53    is a figure connecting first  figure  51    and second  figure  52   . Third  figure  53    continuously connects first  figure  51    and second  figure  52    without interruption. For example, third  figure  53    extends in a band shape and connects first  figure  51    and second  figure  52   . 
     For example, support image  50  includes an annular  figure  50 C  centered on a predetermined portion in the support screen. Annular  figure  50 C  is displayed while being superimposed on the image  79  of the construction topography. Annular  figure  50 C  includes an inner circumference  501  and an outer circumference  502 . Annular  figure  50 C  is an image in which a long belt is bent and rounded. 
     Straight line  51   a  of first figure and straight line  52   a  of second  figure  52    are illustrated in the belt of annular  figure  50 C . Each of straight line  51   a  and straight line  52   a  extends in the radial direction of the annular ring included in support image  50 . In the band of annular  figure  50 C , corner  51   bt  of  figure  51   b    having the home base shape and a part of  figure  52   b    are located. Third  figure  53    is illustrated in the belt of annular  figure  50 C . Third  figure  53    has a belt-like arc shape connecting first  figure  51    and second  figure  52   . 
     Controller  39  causes display  42  to display third  figure  53    along a circle centered on the predetermined portion. Controller  39  causes display  42  to display third  figure  53    along the annular  figure  50 C . Controller  39  causes display  42  to display third  figure  53    along inner circumference  501  and outer circumference  502  of annular  figure  50 C . 
     Controller  39  causes display  42  to display annular  figure  50 C  so as to surround the periphery of image  100 G of the hydraulic excavator. Controller  39  causes display  42  to display inner circumference  501  of annular  figure  50 C  so as to surround the periphery of image  100 G of the hydraulic excavator. Controller  39  displays image  100 G of the hydraulic excavator at the center of annular  figure  50 C . Controller  39  causes display  42  to display annular  figure  50 C  such that the display position of image  100 G of the hydraulic excavator is located at the center of annular  figure  50 C . 
     As described above, controller  39  causes display  42  to display third  figure  53    along a circle (annular  figure  50 C , inner circumference  501 , outer circumference  502 ) centered on image  100 G of the hydraulic excavator. Thus, the operator can intuitively know how much the direction of working implement  2  should be changed. 
     As described above, controller  39  displays third  figure  53    in an arc shape. Thus, the operator can easily know how much the direction of the working implement  2  should be changed by the arc shape (central angle). 
     A scale may be illustrated in the belt of the annulus included in support image  50 . The scale extends in the radial direction in the belt of the annulus. 
     Controller  39  displays third  figure  53    on display  42  by making a display mode of a part of annular  figure  50 C  different from a display mode of another part. The arc-shaped portion in third  figure  53    is colored differently from other portions in the belt of the annulus. 
     Controller  39  sets the color of third  figure  53    to a color different from the default color of annular  figure  50 C . For example, the color of the arc shape in third  figure  53    is red, and the color of other portions in the belt of the annulus is black. Thus, it is understood that the operator only needs to change the direction of working implement  2  by an angle corresponding to the proportion occupied by the portion of the color different from the default color in the region of annular  figure  50 C . 
     When the direction of working implement  2  changes due to the movement of working implement  2  or the traveling of hydraulic excavator  100 , first  figure  51    in support image  50  moves in the circumferential direction in the annular band. When the direction from hydraulic excavator  100  to target topography  70  changes due to the movement of working implement  2  or the traveling of hydraulic excavator  100 , second  figure  52    in support image  50  moves in the circumferential direction in the annular band. 
     As a result, the display of third  figure  53    also changes. An area occupied by third  figure  53    in annular  figure  50 C  changes in real time. When visually recognizing support image  50 , the operator can check the relationship between the direction of the working implement of hydraulic excavator  100  and the direction of the target topography from hydraulic excavator  100  in real time. 
     Support image  50  includes information indicating the orientation. The information includes images  91 ,  92 ,  93 ,  94  representing the orientations. Controller  39  causes display  42  to display images  91  to  94  along annular  figure  50 C . Thus, the operator can further know the direction of working implement  2 , the direction from hydraulic excavator  100  to the target topography  70 , and the like. 
     Image  91  indicates the direction of east. Hereinafter, images  92 ,  93 ,  94  indicate west, south, and north, respectively. Image  93  includes an image  93   a  representing a character “S” and a  figure  93   b    protruding in the south direction. Image  94  includes an image  94   a  representing a character “N” and a  figure  94   b    protruding in the south direction. In this example, controller  39  displays images  91 ,  92 ,  93   a,    94   a  on the inner side of inner circumference  501 . 
     Controller  39  causes display  42  to display a straight line  54  connecting first  figure  51    and image  100 G indicating hydraulic excavator  100  and a straight line  55  connecting second  figure  52    and image  100 G of the hydraulic excavator. Thus, the operator can more clearly recognize the difference between the direction of working implement  2  and the direction from hydraulic excavator  100  to target topography  70 . 
     Controller  39  numerically displays an angle formed by the direction of working implement  2  (image  2 G of the working implement) and the direction from hydraulic excavator  100  (image  100 G of the hydraulic excavator) to target topography  70 . Controller  39  displays the angle formed by straight line  54  and straight line  55  as a numerical value. Controller  39  displays the angle of the arc by third  figure  53    as a numerical value while image  100 G of the hydraulic excavator is set to the center of the arc. In the example of the state in  FIG.  6   , controller  30  displays “71.8°” above annular  figure  50 C  as the numerical value. Such numerical information is also included in support image  50 . 
     In the present example, support image  50  is displayed in top view similarly to image  79  of the construction topography and image  100 G of the hydraulic excavator. Annular  figure  50 C , first  figure  51   , second  figure  52   , third  figure  53   , straight lines  54 ,  55 , and images  91  to  94  are displayed as viewed from above. As illustrated, the support screen displayed on display  42  may include the facing compass at the position not overlapping with the support image  50  (for example, a corner of the screen such as the upper left of the screen). 
     As illustrated in  FIG.  7   , similarly to the first example, the second example of the support screen includes image  100 G of the hydraulic excavator, image  79  of the construction topography including target topography  70 , and support image  50 . Image  100 G of the hydraulic excavator is an image of hydraulic excavator  100  in a bird&#39;s eye view. 
     In this example, controller  39  displays image  79  of the construction topography and image  100 G illustrating hydraulic excavator  100  in a bird&#39;s eye view. Controller  39  stereoscopically displays support image  50 . Controller  39  displays annular  figure  50 C  included in support image  50  in a three-dimensional shape. Controller  39  displays annular  figure  50 C  on display  42  while annular  figure  50 C  has a width in the vertical direction. 
     The operator can switch the screen between the top-view display ( FIG.  6   ) and the bird&#39;s-eye view display by performing input on display  42 . By switching the screen display on display  42  from the top view display to the bird&#39;s-eye view display, the operator can three-dimensionally grasp image  79  of the construction topography. According to the bird&#39;s-eye view display, when the operator moves hydraulic excavator  100  in the direction of target topography  70 , the direction of working implement  2  can be guided in detail for the operator. 
     &lt;Method for Generating Support Image&gt; 
     With reference to  FIGS.  8  and  9   , a method for generating the first example of the support screen of the embodiment will be described below. 
       FIGS.  8 (A) to  8 (E)  illustrate the method for generating the support image in order of steps.  FIGS.  9 (A) to  9 (F)  illustrate the method for generating the support image in top view of the hydraulic excavator in the order of steps subsequent to the steps in  FIG.  8   . 
       FIGS.  8 (A) to  8 (E)  illustrate viewpoints when an Xa-Ya plane is viewed from the Za-axis direction, where the horizontal axis is the Xa-axis and the vertical axis is the Ya-axis. 
     As illustrated in  FIG.  4   , processing unit  44  of controller  39  reads and executes the image display program stored in storage  43  or server  40 , generates the support screen, and displays the support screen on display  42 . The reason is as follows. 
     As illustrated in  FIG.  8 (A) , processing unit  44  of controller  39  acquires two reference position data P 1 , P 2  (a plurality of reference position data) represented in the global coordinate system from GNSS antennas  21 ,  22 . Processing unit  44  of controller  39  determines the position in the coordinate system based on one reference position data of two reference position data P 1 , P 2 . Thereafter, processing unit  44  of controller  39  determines which direction the line connecting the coordinates of two reference position data P 1 , P 2  is directed with respect to the reference orientation (for example, north) of the global coordinate. 
     As illustrated in  FIG.  8 (B) , processing unit  44  of controller  39  positions the construction topography with respect to reference position data P 1 , P 2  in the coordinate system based on the reference position data and the determined orientation. At this point, processing unit  44  of controller  39  acquires the previously-produced construction topography data from storage  43  or server  40 , and collates the shape and coordinates of the three-dimensional construction topography included in the construction topography data with the coordinates of reference position data P 1 , P 2 . 
     As illustrated in  FIG.  8 (C) , processing unit  44  of controller  39  determines a direction DW of the operation plane of working implement  2  based on two reference position data P 1 , P 2 . 
     As illustrated in  FIG.  8 (D) , processing unit  44  of controller  39  determines the posture of working implement  2 . At this point, processing unit  44  of controller  39  acquires the postures of boom  6 ,  18 A arm  7 , and bucket  8  from working implement posture sensors  18 A,  18 B,  18 C. Processing unit  44  of controller  39  determines a position LB 1  of boom  6 , a position LB 2  of arm  7 , and a position LA of bucket  8  based on the acquired posture of working implement  2 . 
     As illustrated in  FIG.  8 (E) , processing unit  44  of controller  39  disposes a 3D (dimension) model of hydraulic excavator  100  based on reference position data P 1 , P 2  determined above, direction DW of the operation plane of working implement  2 , the posture (θ 1 , θ 2 , θ 3 ) of working implement  2 , and the like. At this point, processing unit  44  of controller  39  acquires the 3D model of hydraulic excavator  100  stored in storage  43  or server  40 . 
     As illustrated in  FIG.  9 (A) , processing unit  44  of controller  39  produces image  100 G of the hydraulic excavator in top view based on the 3D model obtained in  FIG.  8 (E) . Image  100 G of the hydraulic excavator includes image  2 G of the working implement. In addition, processing unit  44  of controller  39  produces image  79  of the construction topography in top view. 
     As illustrated in  FIG.  9 (B) , processing unit  44  of controller  39  generates annular  figure  50 C  centered on a predetermined portion (for example, a mounting position of working implement  2  with respect to machine body  1 ) in image  100 G of the hydraulic excavator in top view. Annular  figure  50 C  is generated so as to surround the periphery of image  100 G of the hydraulic excavator. 
     As illustrated in  FIG.  9 (C) , processing unit  44  of controller  39  generates images  91 ,  92 ,  93 ,  94  representing the orientations in top view. Processing unit  44  generates images  91 ,  92 ,  93 ,  94  representing the orientations along annular  figure  50 C  in top view. 
     As illustrated in  FIG.  9 (D) , processing unit  44  of controller  39  generates first  figure  51    indicating the direction of working implement  2  and straight line  54  extending the image of the bucket of working implement  2  in the direction of image  2 G of the working implement in top view. 
     As illustrated in  FIG.  9 (E) , when one topography (target topography  70 ) is selected from the construction topography by the operator, processing unit  44  of controller  39  generates second  figure  52    indicating the direction of target topography  70  from image  100 G of the hydraulic excavator in top view. Processing unit  44  displays the display state of target topography  70  so as to be distinguishable from the surrounding topography. For example, processing unit  44  changes the display color of the target topography from a default color to a specific color (for example, green). 
     As illustrated in  FIG.  9 (F) , processing unit  44  of controller  39  generates third  figure  53    representing the relative relationship between first  figure  51    and second  figure  52    in top view. Third  figure  53    continuously connects first  figure  51    and second  figure  52    without interruption. For example, third  figure  53    extends in a band shape and connects first  figure  51    and second  figure  52   . 
     For example, third  figure  53    is generated as the arc portion in the belt in annular  figure  50 C . For example, third  figure  53    is generated in a color different from other arc portions in the belt in annular  figure  50 C . 
     When the direction of working implement  2  changes due to the movement of working implement  2  or the traveling of hydraulic excavator  100 , first  figure  51    in support image  50  moves in the circumferential direction in the annular band. When the direction from hydraulic excavator  100  to target topography  70  changes due to the movement of working implement  2  or the traveling of hydraulic excavator  100 , second  figure  52    in support image  50  moves in the circumferential direction in the annular band. Thus, the circumferential length of third  figure  53    having the arc shape changes. 
     &lt;Method for Controlling Display System&gt; 
     With reference to  FIG.  10   , a method for controlling the display system of the embodiment will be described below. 
       FIG.  10    is a flowchart illustrating the method for controlling the display system of the embodiment. As illustrated in  FIG.  10   , processing unit  44  of controller  39  generates first  figure  51    indicating the direction of working implement  2  (step S 1 ). Processing unit  44  of controller  39  generates first  figure  51    as described with reference to  FIG.  9 (D) . 
     Processing unit  44  of controller  39  generates second  figure  52    indicating the direction of target topography  70  from hydraulic excavator  100  (step S 2 ). Processing unit  44  of controller  39  generates second  figure  52    as described with reference to  FIG.  9 (E) . 
     Processing unit  44  of controller  39  generates third  figure  53    representing the relative relationship between first  figure  51    and second  figure  52    (step S 3 ). Processing unit  44  of controller  39  generates third  figure  53    as described with reference to  FIG.  9 (F) . 
     Processing unit  44  of controller  39  displays support image  50  including first  figure  51   , second  figure  52   , and third  figure  53    on display  42  (step S 4 ). As illustrated in  FIG.  6  or  7   , processing unit  44  of controller  39  displays support image  50  on display  42  together with image  100 G of the hydraulic excavator, image  79  of the construction topography, and the like. Processing unit  44  of controller  39  switches between the display in  FIG.  6    and the display in  FIG.  7    based on the display switching operation by the operator. 
     &lt;Modifications&gt; 
     With reference to  FIG.  11   , a modification of the display system of the embodiment will be described below. 
       FIG.  11    is a view illustrating an image in which another support image is displayed with hydraulic excavator  100  as a center in the top view of hydraulic excavator  100  as a modification example of the support image displayed on the display. 
     As illustrated in  FIG.  11   , controller  39  causes display  42  to display image  79  of the construction topography and image  100 G illustrating hydraulic excavator  100 . Controller  39  superimposes image  100 G of the hydraulic excavator on image  79  of the construction topography and displays the superimposed image on display  42 . Controller  39  displays image  100 G of the hydraulic excavator  100  on image  79  of the construction topography based on the positional information indicating the current position of hydraulic excavator  100 . Image  100 G of the hydraulic excavator includes image  2 G of the working implement. 
     Controller  39  causes display  42  to display target topography  70  selected by the operator in the construction topography in a mode different from the construction topography that is not selected in the construction topography. 
     Controller  39  causes display  42  to display support image  50 A while support image  50 A is superimposed on the construction topography. Support image  50 A includes image  100 G indicating hydraulic excavator  100 , a straight line  98  extended from working implement  2  of hydraulic excavator  100 , and a straight line  99  connecting the image indicating hydraulic excavator  100  and target topography  70 . Straight line  98  is a straight line superimposed on the virtual straight line along the neutral axis of working implement  2 . Straight line  98  is a straight line extended from bucket  8 . 
     In such the display, according to display system  101 , the operator can more easily visually understand the relationship between the direction of the working implement of hydraulic excavator  100  and the direction of the target topography from hydraulic excavator  100 . According to such the display, when the operator moves hydraulic excavator  100  in the direction of target topography  70 , the direction of working implement  2  can be guided for the operator. 
     The above embodiment is only by way of example, and the present invention is not limited to the above embodiment. The scope of the present invention is indicated by the claims, and it is intended that all modifications within the meaning and scope of the claims are included in the present invention. 
     REFERENCE SIGNS LIST 
       1 : machine body,  2 : working implement,  2 G,  79 ,  91 ,  92 ,  93 ,  93   a,    94 ,  94   a,    100 G: image,  3 : revolving body,  4 : operator cab,  4 S: driver&#39;s seat,  5 : traveling device,  6 : boom,  7 : arm,  8 : bucket,  10 : boom cylinder,  11 : arm cylinder,  12 : bucket cylinder,  13 : boom pin,  14 : arm pin,  15 : bucket pin,  18 A: working implement posture sensor,  21 ,  22 : antenna,  24 : inclination angle sensor,  25 : operation device,  26 : working implement electronic control device,  27 : working machine control device,  35 : working implement-side storage,  36 : arithmetic unit,  38 : display input apparatus,  39 : controller,  40 : server,  42 : display,  43 ,  45 : storage,  44 : processing unit,  50 ,  50 A: support image,  50 C: annular figure,  51 : first figure,  51   a,    52   a,    54 ,  55 ,  98 ,  99 : straight line,  51   b,    52   b,    93   b,    94   b:  figure,  51   bt:  corner,  52 : second figure,  53 : third figure,  70 : target topography,  71 : design surface,  100 : hydraulic excavator,  101 : display system,  501 : inner circumference,  502 : outer circumference