Patent Publication Number: US-2023137344-A1

Title: Work machine

Description:
TECHNICAL FIELD 
     The present invention relates to a work machine. 
     BACKGROUND ART 
     Conventionally, a technique exists in which an environment map is created or deleted based on sensed obstacle information and machine body operation is controlled according to information on the created environment map. 
     For example, in patent document 1, autonomous moving apparatus is disclosed that includes an obstacle sensing section that senses an obstacle, a map creating section that records information of the obstacle sensed by the obstacle sensing section on an environment map, an obstacle erasing section that erases the information of the obstacle recorded by the map creating section from the environment map according to the elapse of time, and a route determining section that sets a movement route on the basis of the information recorded on the environment map. 
     PRIOR ART DOCUMENT 
     Patent Document 
     
         
         Patent Document 1: JP-2019-12504-A 
       
    
     SUMMARY OF THE INVENTION 
     Problem to be Solved by the Invention 
     In the above-described conventional technique, regarding an obstacle outside the sensing range of the on-machine obstacle sensing section, information of the obstacle is deleted from the environment map according to the time when the obstacle has been sensed and the number of times of the sensing and the deletion speed is adjusted. However, the cause of the obstacle getting out of the sensing range is not necessarily sufficiently considered, and contact between the autonomous moving apparatus and the obstacle is of concern when the obstacle has gotten out of the sensing range due to the entry of the obstacle into the blind area of the on-machine obstacle sensing section. Furthermore, because it is impossible to identify the cause of the obstacle getting out of the sensing range, it is also conceivable that the plan of an avoidance route made in consideration of the obstacle that has gotten out of the sensing range becomes excessive regarding the movement route of the autonomous moving apparatus. 
     The present invention is made in view of the above and intends to provide a work machine that can properly process information on an object that has gotten out of a sensing range according to the cause thereof. 
     Means for Solving the Problem 
     The present application includes plural means to solve the above-described problem. To cite one example thereof, in a work machine including a machine body having a moving device, a work device disposed on the machine body, a plurality of actuators that cause the moving device and the work device to operate, an object sensor that senses an object around the machine body, and a controller configured to create an environment map including information relating to an object that exists around the machine body on the basis of information on an object sensed by the object sensor and cause the plurality of actuators to operate on the basis of the environment map created, the controller is configured to determine a type of the object and predict a movement direction of the object on the basis of a sensing result of the object sensed by the object sensor and delete, from the environment map, the information relating to the object that is the object sensed by the object sensor and has been determined to have moved to the outside of a sensing range of the object sensor on the basis of the type and the movement direction of the object. 
     Advantages of the Invention 
     According to the present invention, the information on the object that has gotten out of the sensing range can be properly processed according to the cause thereof. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a perspective view schematically illustrating the appearance of a hydraulic excavator that is one example of a work machine according to a first embodiment. 
         FIG.  2    is a side view schematically illustrating the appearance of the hydraulic excavator. 
         FIG.  3    is a functional block diagram schematically illustrating part of processing functions of a controller mounted in the hydraulic excavator. 
         FIG.  4    is a flowchart illustrating the processing contents of object information deletion processing in the controller. 
         FIG.  5    is a diagram illustrating one example of an environment map. 
         FIG.  6    is a top view schematically illustrating the state of surroundings of a machine body corresponding to the environment map illustrated in  FIG.  5   . 
         FIG.  7    is a diagram illustrating the movable range of the hydraulic excavator that is the work machine. 
         FIG.  8    is a diagram for explaining generation of the environment map when the machine body has swung and a deletion determination method of information of the obstacle. 
         FIG.  9    is a diagram for explaining the deletion determination method of obstacle information when a moving object has moved to a blind area in the state in which the machine body has stopped. 
         FIG.  10    is a diagram for explaining the deletion determination method of the obstacle information when the moving object has moved to the blind area in the state in which the machine body has stopped. 
         FIG.  11    is a functional block diagram schematically illustrating part of processing functions of the controller mounted in the hydraulic excavator in a second embodiment. 
         FIG.  12    is a top view schematically illustrating sensing ranges of environmental obstacle sensors. 
         FIG.  13    is a diagram illustrating the movable range of a wheel loader that is a work machine according to a third embodiment. 
     
    
    
     MODES FOR CARRYING OUT THE INVENTION 
     Embodiments of the present invention will be described below with reference to the drawings. In embodiments of the present invention, description will be made by exemplifying a hydraulic excavator including a front work implement (work device) as a work machine. However, the present invention can be applied also to other work machines including a work device, such as wheel loaders and cranes. 
     First Embodiment 
     A first embodiment of the present invention will be described with reference to  FIG.  1    to  FIG.  10   . 
       FIG.  1    is a perspective view schematically illustrating the appearance of a hydraulic excavator that is one example of the work machine according to the present embodiment and  FIG.  2    is a side view. Furthermore,  FIG.  3    is a functional block diagram schematically illustrating part of processing functions of a controller mounted in the hydraulic excavator. 
     In  FIG.  1    and  FIG.  2   , a hydraulic excavator  100  includes an articulated front work implement  24  configured by linking plural driven components (boom  8 , arm  9 , and bucket (work equipment)  10 ) to each other that each pivot in the perpendicular direction, and an upper swing structure  22  and a lower track structure  20  that configure the machine body. The upper swing structure  22  is disposed swingably relative to the lower track structure  20  through a swing mechanism  21 . The swing mechanism  21  has a swing motor  23  and a machine body swing angle sensor  27 . The upper swing structure  22  is driven to swing relative to the lower track structure  20  by the swing motor  23  and the swing angle with respect to the lower track structure  20  is sensed by the machine body swing angle sensor  27 . 
     The base end of the boom  8  of the front work implement  24  is supported by the front part of the upper swing structure  22  pivotally in the perpendicular direction. One end of the arm  9  is supported by the end part (tip) different from the base end in the boom  8  pivotally in the perpendicular direction. The bucket  10  is supported by the other end of the arm  9  pivotally in the perpendicular direction. The boom  8 , the arm  9 , the bucket  10 , the upper swing structure  22 , and the lower track structure  20  are driven by a boom cylinder  5 , an arm cylinder  6 , a bucket cylinder  7 , the swing motor  23 , and left and right travelling motors  3  (only one travelling motor is illustrated), respectively, that are hydraulic actuators. 
     Here, the intersection of a swing center axis  25  of the upper swing structure  22  and the lower surface of the upper swing structure  22  is defined as the origin, and a machine body coordinate system is set that has a z-axis that is along the swing center axis  25  and along which the upper side is the positive side, an x-axis that extends from the origin in the forward-rearward direction perpendicular to the z-axis and along which the front side is the positive side, and a y-axis that extends from the origin in the left-right direction perpendicular to the z-axis and the x-axis and along which the right direction is the positive side. 
     A cab  2  on which an operator gets is mounted on the front left side of the upper swing structure  22 . Furthermore, a controller  44  that controls operation of the whole of the hydraulic excavator  100  is disposed on the upper swing structure  22 . In the cab  2 , operation levers (operation devices)  2   a  and  2   b  that output an operation signal for operating the hydraulic actuators  5  to  7  and  23  are disposed. Although not illustrated, the operation levers  2   a  and  2   b  can each be inclined forward, rearward, leftward, and rightward, and include a sensor that electrically detects the inclination amount of the lever that is the operation signal, i.e. the lever operation amount, and is not illustrated in the diagram, and output the lever operation amount sensed by the sensor to the controller  44  (described later) through electrical wiring. That is, operations of the hydraulic actuators  5  to  7  and  23  are each assigned to the forward-rearward direction or the left-right direction of the operation lever  2   a  or  2   b.    
     Operation control of the boom cylinder  5 , the arm cylinder  6 , the bucket cylinder  7 , the swing motor  23 , and the left and right travelling motors  3  is carried out by controlling, control valves or, the direction and the flow rate of a hydraulic operating fluid supplied to the respective hydraulic actuators  3 ,  5  to  7 , and  23  from a hydraulic pump device driven by a prime mover such as an engine or electric motor that is not illustrated in the diagram. Operation of the control valves is controlled by the controller  44  on the basis of the operation signal from the operation lever  2   a  or  2   b  and thereby operation of the respective hydraulic actuators  5  to  7  and  23  is controlled. 
     Posture sensors  34 A,  34 B, and  34 C are attached to the base part of the boom  8 , the connecting part between the boom  8  and the arm  9 , and the connecting part between the arm  9  and the bucket  10 , respectively. The posture sensors  34 A,  34 B, and  34 C are mechanical angle sensors like a potentiometer, for example. As illustrated in  FIG.  2   , the posture sensor  34 A measures an angle β 1  formed by the longitudinal direction (straight line that links the pivot centers of both ends to each other) of the boom  8  and the x-y plane and transmits the angle β 1  to the controller  44 . Furthermore, the posture sensor  34 B measures an angle β 2  formed by the longitudinal direction (straight line that links the pivot centers of both ends to each other) of the boom  8  and the longitudinal direction (straight line that links the pivot centers of both ends to each other) of the arm  9  and transmits the angle β 2  to the controller  44 . Moreover, the posture sensor  34 C measures an angle β 3  formed by the longitudinal direction (straight line that links the pivot centers of both ends to each other) of the arm  9  and the longitudinal direction (straight line that links the pivot center and the claw tip to each other) of the bucket  10  and transmits the angle β 3  to the controller  44 . Here, the machine body swing angle sensor  27  and the posture sensors  34 A to  34 C configure a posture information sensor  35  that senses posture information of the upper swing structure  22  and the front work implement  24 . 
     In the present embodiment, description will be made by exemplifying the case in which a rocking center  38  (connecting part with the upper swing structure  22  in the boom  8 ) of the front work implement  24  is disposed at a different position from the swing center axis  25 . However, the swing center axis  25  and the rocking center  38  may be disposed to intersect. 
     Furthermore, in the present embodiment, description has been made by exemplifying the case in which angle sensors and so forth are used as the posture information sensor  35 . However, inertial measurement devices (IMU: Inertial Measurement Unit) may be used as the machine body swing angle sensor  27  and the posture sensors  34 A to  34 C. Moreover, the configuration may be made in such a manner that a stroke sensor is disposed for each of the boom cylinder  5 , the arm cylinder  6 , and the bucket cylinder  7  and the relative orientation (posture information) at the respective connecting parts of the upper swing structure  22 , the boom  8 , the arm  9 , and the bucket  10  is figured out from the stroke change amount and each angle is obtained from the result thereof. 
     On the upper swing structure  22 , plural (for example, four) on-machine obstacle sensors  26  that sense an object around the machine body (upper swing structure  22 , lower track structure  20 ) are disposed. The installation positions and the number of on-machine obstacle sensors  26  are not particularly limited to the example of the present embodiment and it suffices that the field of view of all directions of the machine body (that is, 360 degrees around the hydraulic excavator  100 ) can be ensured. In the present embodiment, description will be made by exemplifying the case in which the four on-machine obstacle sensors  26  are each installed at the upper part of the cab  2  and the left lateral side, the front part on the right lateral side, and the rear part on the right lateral side in the upper swing structure  22  and cover the field of view of 360 degrees around the machine body. The on-machine obstacle sensors  26  are sensors using a LiDAR (Laser Imaging Detection and Ranging, laser image detection and ranging) technique for example, and sense an object that exists around the hydraulic excavator  100  and transmit coordinate data thereof to the controller  44 . 
     A front work implement length R illustrated in  FIG.  2    is a distance R from the swing center axis  25  to the tip of the front work implement  24 . The lengths of the boom  8 , the arm  9 , and the bucket  10  are defined as L 1 , L 2 , and L 3 , respectively. The angle β 1  formed by the x-y plane and the longitudinal direction of the boom  8  is measured by the posture sensor  34 A. The angle β 2  formed by the boom  8  and the arm  9  and the angle β 3  formed by the arm  9  and the bucket  10  are measured by the posture sensors  34 B and  34 C, respectively. A height ZO from the x-y plane to the rocking center  38  is obtained in advance. Furthermore, a distance L 0  from the swing center axis  25  to the rocking center  38  is also obtained in advance. An angle β 2   a  formed by the xy plane and the longitudinal direction of the arm  9  can be calculated from the angle β 1  and the angle β 2 . An angle β 3   b  formed by the xy plane and the longitudinal direction of the bucket  10  can be calculated from the angle β 1  and the angles  82  and  83 . That is, the front work implement length R can be calculated by the following (expression 1). 
         R=L 0+ L 1 cos β1+ L 2 cos β2 a+L 3 cos β3 b    (expression 1)
 
     In  FIG.  3   , the controller  44  includes a map creating section  51 , a map recording section  52 , a route determining section  53 , a type determining section  54 , a movement direction determining section  55 , a detected-information recording section  56 , an operation direction computing section  57 , and an obstacle deleting section  58 . 
     The map creating section  51  creates an environment map including information on an object that exists around the machine body on the basis of position information of the object (obstacle) sensed by the on-machine obstacle sensor  26  and transmits the created environment map to the map recording section  52 . The obstacle in the present embodiment is an object that exists around the machine body and is an object excluding the ground. For example, the obstacle is a moving object such as another work machine or a worker or is an object such as a building or a rock with a size larger than a certain size or is a fixed object such as a sign. 
     The type determining section  54  determines the type of the obstacle sensed by the on-machine obstacle sensor  26  and transmits the determination result to the obstacle deleting section  58 . In the determination of the type in the type determining section  54 , for example, by using a pattern matching technique such as image recognition for an image obtained in the on-machine obstacle sensor  26  to compare the image with images of objects that are prepared in advance and whose type has been selected, the type of the most similar object is determined as the type of the obstacle sensed by the on-machine obstacle sensor  26 . 
     The movement direction determining section  55  determines, on the basis of position information and sensed orientation of the object sensed by the on-machine obstacle sensor  26 , whether or not the movement direction in which the object (obstacle) is expected to move is a blind area (described later) from the movement direction and the movement speed. Then, the movement direction determining section  55  transmits the determination result to the obstacle deleting section  58 . In the discrimination of the movement direction in the movement direction determining section  55 , the distance of the movement, the movement speed, and the orientation (movement direction) are computed from the difference between the position of the object sensed at a time (t-1) and the position of the same object sensed at a time (t), for example. 
     The detected-information recording section  56  records the position of the obstacle sensed by the on-machine obstacle sensor  26 , the sensing time, the sensed orientation, and the position of the on-machine obstacle sensor  26  that has sensed the obstacle and transmits these pieces of information to the obstacle deleting section  58 . 
     The operation direction computing section  57  computes the operation directions of the front work implement  24  (bucket (work equipment)  10 ) and the machine body (upper swing structure  22 , lower track structure  20 ) on the basis of information on the front work implement length R and the swing angle computed by the posture information sensor  35  and transmits the computation result to the obstacle deleting section  58 . In the computation of the operation directions in the operation direction computing section  57 , the operation directions of the front work implement  24  and the machine body are computed from the difference between information of the previous step in the unit processing time in the controller  44  and the present information, for example. 
     The map recording section  52  records the environment map created by the map creating section  51 . Furthermore, the map recording section  52  deletes, from the environment map, information of the obstacle about which a deletion request has been received from the obstacle deleting section  58 . 
     The obstacle deleting section  58  decides information of the obstacle to be deleted from the environment map on the basis of information obtained from the type determining section  54 , the movement direction determining section  55 , the detected-information recording section  56 , and the operation direction computing section  57  and transmits a request to delete the information of the obstacle to the map recording section  52 . 
     The route determining section  53  refers to the environment map recorded in the map recording section  52  and corrects a route input through operating the operation lever  2   a ,  2   b  by an operator or computes the movement route to the target position, and outputs an operation command to the actuator  5  to  7  and  23 . 
     In the present embodiment configured as above, the controller  44  executes object information deletion processing in which the controller  44  computes the operation directions of the machine body and the front work implement  24  on the basis of posture information sensed by the posture information sensor  35  and determines the type of an object and predicts the movement direction of the object on the basis of the sensing result of the object sensed by the on-machine obstacle sensor  26  and immediately deletes, from the environment map, information relating to the object that is the object sensed by the on-machine obstacle sensor  26  and has moved to the outside of the sensing range of the on-machine obstacle sensor  26  on the basis of the operation directions of the machine body and the front work implement  24  and the type and the movement direction of the object. 
       FIG.  4    is a flowchart illustrating the processing contents of the object information deletion processing in the controller. The processing to be described below is executed for each obstacle. 
     In  FIG.  4   , the controller  44  determines whether or not an obstacle has been sensed by the on-machine obstacle sensor  26  (step S 110 ), and ends the processing when the determination result is NO, that is, when an obstacle has not been sensed. 
     Furthermore, when the determination result in the step S 110  is YES, that is, when an obstacle has been sensed by the on-machine obstacle sensor  26 , the controller  44  creates an environment map by the map creating section  51  (step S 120 ) and records the created environment map by the map recording section  52  (step S 130 ). In the environment map recorded in the map recording section  52 , information on an obstacle included in an environment map newly created by the map creating section  51  is accumulated and recorded. 
       FIG.  5    is a diagram illustrating one example of the environment map. Moreover,  FIG.  6    is a top view schematically illustrating the state of surroundings of the machine body corresponding to the environment map illustrated in  FIG.  5   . 
     As illustrated in  FIG.  5   , the environment map is created based on the coordinates, the shape, and the reliability of information regarding obstacles  37  obtained by the on-machine obstacle sensors  26 . Furthermore, as illustrated in  FIG.  6   , information of the obstacles  37  sensed in sensing ranges  26 A to  26 D of the on-machine obstacle sensors  26  is recorded on the environment map. In the present embodiment, the outside of the sensing ranges  26 A to  26 D of the on-machine obstacle sensors  26 , i.e. the range in which sensing is impossible, is referred to as the blind area. 
     The environment map is what is obtained by recording the existence probabilities of the obstacle  37  at positions corresponding to the respective lattice points in the case in which a lattice of 10 cm×10 cm is set around the machine body as the values of the respective lattice points. The existence probability of the obstacle  37  recorded on the environment map is decided depending on the reliability of information and the shape when the obstacle  37  is sensed by the on-machine obstacle sensor  26 . That is, regarding the existence probability of the obstacle  37 , the existence probability at the center position thereof is the highest (for example, existence probability=100%) and the existence probability gradually decreases in the radial direction as the position gets farther away from the center position and the state in which the obstacle  37  does not exist (for example, existence probability=0%) is obtained at a certain distance. 
     The environment map may be used in a contact prevention function to prevent contact with an obstacle and a movement route planning function to compute the movement route to the target position with avoidance of obstacles, for example. That is, for example, the route determining section  53  estimates positions at which the possibility of existence of an obstacle is high based on the existence probability of the obstacle in the environment map, and determines the route on which the existence probability of the obstacle is the lowest from the present position of the bucket  10  to the target position, and outputs instruction signals to the actuators  23 ,  5 ,  6 , and  7  to cause the bucket  10  to move along the route. Furthermore, it is also possible to display the environment map to the operator or use the environment map for processing of alleviating collision based on the existence probability of the obstacle  37  and so forth also at the time of manual and semiautomatic operation. In  FIG.  5   , the existence probability of the obstacle  37  in the environment map is represented by one kind of hatching for convenience. However, for example, in the case of presentation to the operator, the existence probability may be represented by a color scheme in which the existence probability becomes higher as the color becomes darker and the existence probability becomes lower as the color becomes paler. 
     Referring back to  FIG.  4   , when the processing of the step S 130  ends, subsequently the controller  44  determines whether or not the obstacle  37  is in the movable range (step S 140 ). When the determination result is NO, that is, when the obstacle  37  has been sensed outside the movable range, a deletion instruction is transmitted to the map recording section  52  to immediately delete the information (existence probability) relating to the obstacle  37  from the environment map (step S 141 ), and the processing is ended. 
       FIG.  7    is a diagram illustrating the movable range of the hydraulic excavator that is the work machine. 
     In  FIG.  7   , a movable range  24 A relating to the front work implement  24  of the hydraulic excavator  100  is the range that can be reached by the front work implement  24  when the upper swing structure  22  swings by 360 degrees in the case in which the posture with which the front work implement length R is the longest is taken. Furthermore, a movable range  20 A relating to the lower track structure  20  is the range that can be reached by the machine body in e.g. T seconds at the time of travelling of the hydraulic excavator  100 . Moreover, the movable range obtained by integrating the movable ranges  20 A and  24 A is defined as a movable range  100 A relating to the hydraulic excavator  100 . 
     Referring back to  FIG.  4   , when the determination result in the step S 140  is YES, the controller  44  determines whether or not the obstacle has moved to the blind area due to machine body operation (step S 150 ). When the determination result in the step S 150  is NO, the controller  44  holds the information (existence probability) relating to the obstacle  37  in the environment map (step S 161 ) and ends the processing. 
     Furthermore, when the determination result in the step S 150  is YES, the controller  44  determines whether or not the obstacle is a moving object (step S 160 ). When the determination result in the step S 160  is NO, the controller  44  holds the information (existence probability) relating to the obstacle  37  in the environment map (step S 161 ) and ends the processing. 
     Moreover, when the determination result in the step S 160  is YES, the controller  44  determines whether or not the obstacle (moving object) is in movement (step S 180 ). When the determination result in the step S 170  is YES, the controller  44  holds the existence probability of the obstacle for n/a seconds (step S 151 ) and thereafter deletes the existence probability (that is, decreases the existence probability to 0 (zero)) over a time of m/b seconds (step S 190 ) and ends the processing. Furthermore, when the determination result in the step S 170  is NO, the controller  44  proceeds to processing of a step S 151 . 
     Here, the above-described processing will be described in more detail. 
       FIG.  8    is a diagram for explaining generation of the environment map when the machine body has swung and a deletion determination method of information of the obstacle. 
     For example, when the machine body swings and an obstacle in the movable range  24 A gets out of the sensing ranges  26 A to  26 D of the on-machine obstacle sensors  26  in the state in which the obstacle (obstacle  37  in  FIG.  6   , fixed object  39  or moving object  40 A in  FIG.  8   , or the like) is not moving, the existence probability is held irrespective of the type of the obstacle. On the other hand, regarding the obstacle outside the movable range  24 A, the existence probability is immediately deleted irrespective of the type of the obstacle. 
     Furthermore, when the machine body stops at the movement destination for a certain time, for example n seconds, and has not carried out swing operation, whether to delete the existence probability is determined according to the type of the obstacle. For example, suppose that obstacles are classified into an obstacle that moves (moving object  40 A) and a fixed obstacle (fixed object  39 ). Suppose that the moving object  40 A mainly represents a worker or another machine and the fixed object  39  represents a column, wall, cone, or the like. 
     The possibility that the fixed object  39  moves from a position at which the fixed object  39  was sensed in the past is low even after the elapse of n seconds, and therefore, the existence probability does not need to be deleted even when the fixed object  39  gets out of the sensing ranges  26 A to  26 D. On the other hand, the possibility that the moving object  40 A has moved from a position at which the moving object  40 A was sensed in the past after n seconds is high. If the existence probability of the moving object  40 A with a high possibility of movement from the position at which it was sensed is kept, there is a possibility that it is impossible to generate an efficient route at the time of route planning. Thus, for the moving object  40 A after the elapse of n seconds, the existence probability is deleted. Here, for example the n seconds is set equal to or longer than the time over which an average operator operates the hydraulic excavator  100  to carry out excavating and loading operation. 
     Moreover, the moving object  40 A after the elapse of n seconds is discriminated and the existence probability is gradually lowered and is completely deleted after m seconds. The m seconds is decided according to the original existence probability and the distance from the machine body regarding the moving object  40 A. For example, the moving object  40 A that exists at a position separate from the machine body, such as the outside of the movable range  24 A of the hydraulic excavator  100 , has a low risk of contact with the machine body, and therefore the deletion speed is set faster. On the other hand, the moving object  40 A that exists in the vicinity of the machine body, such as the inside of the movable range  24 A of the hydraulic excavator  100 , has a high risk of contact with the machine body, and therefore the speed of the deletion is set slower. 
     Furthermore, for example, regarding the moving object  40 A with a low existence probability, the possibility that the moving object  40 A exists at a sensing position after n seconds is extremely low, and therefore the deletion speed is set faster. On the other hand, for example, regarding the moving object  40 A with a high existence probability, the possibility that the moving object  40 A exists near a sensing position after n seconds remains, and therefore the deletion speed is set slower. 
     When the same obstacle  37  is sensed by the different on-machine obstacle sensors  26  for example, deletion determination is carried out with priority given to information with higher reliability. Moreover, when the reliability of information of the obstacle  37  is low and it is difficult to determine the type of the obstacle  37 , the obstacle  37  is treated as the moving object  40 A. 
       FIG.  9    and  FIG.  10    are diagrams for explaining the deletion determination method of obstacle information when a moving object has moved to the blind area in the state in which the machine body has stopped. 
     In  FIG.  9   , for example, when the moving object  40 A has moved to the blind area in a gap between the sensing ranges by oneself, the existence probability is held for n seconds and is gradually deleted according to the elapse of time. On the other hand, in  FIG.  10   , regarding the moving object  40 A that moves to the outside of the movable range  24 A of the hydraulic excavator  100 , the risk of collision with the machine is low, and therefore the existence probability of the obstacle  37  is immediately deleted. 
     When the machine body carries out swing action (see  FIG.  7   ) and the moving object  40 A moves by oneself to move to the outside of the sensing range (see  FIG.  8   ), the operation direction of the machine body is computed in the operation direction computing section  57  and the obstacle deleting section  58  computes the deletion speed of the existence probability from the movement direction of the moving object  40 A and the machine body operation direction obtained from the movement direction determining section  55  and the operation direction computing section  57 . For example, when the moving object  40 A moves in a direction toward the outside of the movable range  24 A and has moved to the blind area due to swing operation of the machine body before having moved to the outside of the sensing range, it is determined that the moving object  40 A is attempting to get farther away from the machine body, and the existence probability is held for n/a seconds and is deleted over m/b seconds. The variables a and b are adjustment values equal to or larger than 1 and vary according to the positions of the machine body and the moving object  40 A sensed last, and the values become larger as the moving object  40 A is remoter from the machine body. Furthermore, for example, when the moving object  40 A moves in a direction toward the blind area and has moved to the blind area due to swing operation of the machine body before having moved to the outside of the sensing range, the existence probability is held for n seconds and is deleted after m seconds as described above. 
     Effects of the present embodiment configured as above will be described. 
     In the conventional technique, regarding an obstacle outside the sensing range of the on-machine obstacle sensing section, information of the obstacle is deleted from the environment map according to the time when the obstacle has been sensed, and the number of times of the sensing and the deletion speed is adjusted. However, the cause of the obstacle getting out of the sensing range is not necessarily sufficiently considered, and contact between the machine body and the obstacle is of concern when the obstacle has gotten out of the sensing range due to the entry of the obstacle into the blind area of the on-machine obstacle sensing section. Furthermore, because it is impossible to identify the cause of the obstacle getting out of the sensing range, it is also conceivable that the plan of an avoidance route made in consideration of the obstacle that has gotten out of the sensing range becomes excessive regarding the movement route of the machine body. 
     In contrast, in the present embodiment, the configuration is made in such a manner that the operation directions of the machine body and the work device are computed based on the posture information sensed by the posture information sensor  35  and the type of an object is determined and the movement direction of the object is predicted based on the sensing result of the object sensed by the on-machine obstacle sensor  26  and information relating to the object that is the object sensed by the object sensor and has moved to the outside of the sensing range of the on-machine obstacle sensor  26  is immediately deleted from the environment map on the basis of the operation directions of the machine body and the work device and the type and the movement direction of the object. Therefore, the information on the object that has gotten out of the sensing range can be properly processed according to the cause thereof, and improvement in the work efficiency can be intended while lowering of the safety is suppressed. 
     Second Embodiment 
     A second embodiment of the present invention will be described with reference to  FIG.  11    and  FIG.  12   . 
     In the first embodiment, the case in which an object (obstacle) is sensed by using the on-machine obstacle sensors  26  is illustrated. The present embodiment is what illustrates the case in which an object (obstacle) is sensed also in other obstacle sensors (environmental obstacle sensors  41 ). 
       FIG.  11    is a functional block diagram schematically illustrating part of processing functions of the controller mounted in the hydraulic excavator in the present embodiment. Furthermore,  FIG.  12    is a top view schematically illustrating the sensing ranges of the environmental obstacle sensors. In the diagrams, a component similar to that of the first embodiment is given the same numeral and description thereof is omitted. 
     As illustrated in  FIG.  11    and  FIG.  12   , plural (for example six) environmental obstacle sensors  41  that sense an object around the machine body (upper swing structure  22 , lower track structure  20 ) are disposed around the hydraulic excavator  100 . The environmental obstacle sensors  41  are installed mainly for the purpose of reducing the blind area in the movable range  24 A of the hydraulic excavator  100 . The installation positions and the number of environmental obstacle sensors  41  are not particularly limited to the example of the present embodiment. The environmental obstacle sensors  41  are sensors, cameras, or the like that have a tripod or the like and use a LiDAR (Laser Imaging Detection and Ranging, laser image detection and ranging) technique of a self-standing type for example, and sense an object that exists around the hydraulic excavator  100  and transmit coordinate data thereof to the controller  44 . 
     In the present embodiment, the environmental obstacle sensors  41  transmit the position of the sensed obstacle  37  (moving object  40 A), the sensing time, and the sensed orientation to the controller  44 . In each of the type determining section  54 , the movement direction determining section  55 , and the detected-information recording section  56 , information with higher reliability of the obstacle  37  (moving object  40 A) sensed by the on-machine obstacle sensors  26  and the environmental obstacle sensors  41  are preferentially used and determination and recording are carried out. 
     The environmental obstacle sensors  41  are not affected by operation of the hydraulic excavator  100  and therefore can always monitor the obstacle  37  (moving object  40 A) in sensing ranges  41 A to  41 F. Thus, the position of the obstacle  37  (moving object  40 A) can be sensed in a wider range. For example, when it is possible to sense the whole thing in the movable range  24 A of the hydraulic excavator  100  by the on-machine obstacle sensors  26  and the environmental obstacle sensors  41 , the obstacle deleting section  58  immediately deletes all of the existence probability of the obstacles  37  (moving objects  40 A) outside the movable range  24 A. 
     The present embodiment is the same as the first embodiment regarding the other configurations. 
     Effects similar to those of the first embodiment can be obtained also in the present embodiment configured as above. 
     Third Embodiment 
     A third embodiment of the present invention will be described with reference to  FIG.  13   . 
     The present embodiment is what illustrates the case in which for example a work machine of a wheeled type, such as a wheel loader, is used as the work machine. 
       FIG.  13    is a diagram illustrating the movable range of the wheel loader that is the work machine. 
     In  FIG.  13   , a movable range  200 A of a wheel loader  200  is a range in which the wheel loader  200  can move in the forward-rearward direction in T seconds in the state in which a steering wheel is turned left or right to the limit. 
     The other configurations are the same as the first and second embodiments. 
     Effects similar to those of the first and second embodiments can be obtained also in the present embodiment configured as above. 
     &lt;Additional Notes&gt; 
     The present invention is not limited to the above-described embodiments and various modification examples and combinations in such a range as not to depart from the gist thereof are included. Furthermore, the present invention is not limited to what include all configurations described in the above-described embodiments and what are obtained by deleting part of the configurations are also included. Moreover, the above-described respective configurations, functions, and so forth may be implemented through designing part or all of them by an integrated circuit for example, or the like. In addition, the above-described respective configurations, functions, and so forth may be implemented by software through interpreting and executing, by a processor, a program that implements the respective functions. 
     DESCRIPTION OF REFERENCE CHARACTERS 
     
         
           2 : Cab 
           2   a ,  2   b : Operation lever (operation device) 
           3 : Travelling motor 
           5 : Boom cylinder 
           6 : Arm cylinder 
           7 : Bucket cylinder 
           8 : Boom 
           9 : Arm 
           10 : Bucket 
           20 : Lower track structure 
           20 A: Movable range 
           21 : Swing mechanism 
           22 : Upper swing structure 
           23 : Swing motor 
           24 : Front work implement 
           26 : On-machine obstacle sensor 
           26 A to  26 D: Sensing range 
           27 : Machine body swing angle sensor 
           34 A to  34 C: Posture sensor 
           35 : Posture information sensor 
           37 : Obstacle 
           38 : Rocking center 
           39 : Fixed object 
           40 A: Moving object 
           41 : Environmental obstacle sensor 
           41 A to  41 F: Sensing range 
           44 : Controller 
           51 : Map creating section 
           52 : Map recording section 
           53 : Route determining section 
           54 : Type determining section 
           55 : Movement direction determining section 
           56 : Detected-information recording section 
           57 : Operation direction computing section 
           58 : Obstacle deleting section 
           100 : Hydraulic excavator 
           100 A: Movable range 
           200 : Wheel loader 
           200 A: Movable range