Patent Publication Number: US-2022213666-A1

Title: Remote operation system and remote operation server

Description:
TECHNICAL FIELD 
     The present invention relates to a system for remotely operating a work machine and the like. 
     BACKGROUND ART 
     It is essential that the communication is not disrupted to enable a smooth operation of a work machine such as a construction machine when the work machine is remotely operated. There is proposed a method of limiting an information amount of video provided to an operator or selectively providing only a directional video according to a pivoting direction of an upper pivoting body of the work machine among a plurality of different-directional videos with reference to the work machine, in a state where it is assumed that the operator has no intention to remotely operate the work machine (for example, in a state where a gateway cutoff lever is raised), (for example, see Patent Literature 1). 
     CITATION LIST 
     Patent Literature 
     Patent Literature 1
     Japanese Patent Laid-Open No. 2017-092908   

     SUMMARY OF INVENTION 
     Technical Problem 
     However, the above-described state may make it difficult for the operator to grasp the environment of the work machine only by limiting the information amount of video or selectively outputting the specific-directional video. 
     The present invention has an object to provide mainly a system capable of reducing a data communication load for outputting environment information, while avoiding excessive reduction in an information amount of the environment information in an appropriate form from the standpoint of an operator appropriately grasping an environment of a work machine according to an operation state of the work machine by the operator. 
     Solution to Problem 
     A remote operation server of the present invention is a remote operation server having a function of mutual communication with a work machine and a remote operation device for remotely operating the work machine, the remote operation server comprising a state recognition element configured to recognize an operation state of the remote operation device by an operator or a motion state of the work machine, and an environment information control process element configured to perform an environment information control process for adjusting each of a plurality of environment information factors in different modes according to a difference in the operation state of the remote operation device or the motion state of the work machine that is recognized by the state recognition element so that a data amount of environment data is reduced, the environment information factor being output in an information output device included in the remote operation device and defining an information amount of environment information according to the environment data acquired by an environment recognition device included in the work machine, the environment data indicating an environment of the work machine. 
     A remote operation system of the present invention comprises a work machine, a remote operation device for remotely operating the work machine, and the remote operation server. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is an illustrative diagram illustrating a configuration of a remote operation system as one embodiment of the present invention. 
         FIG. 2  is an illustrative diagram illustrating a configuration of a work machine. 
         FIG. 3  is an illustrative diagram illustrating a configuration of a remote operation device. 
         FIG. 4  is an illustrative diagram illustrating functions of a remote operation system as one embodiment of the present invention. 
         FIG. 5A  is an illustrative graph illustrating a control mode for environment information factors in a normal state. 
         FIG. 5B  is an illustrative graph illustrating a first control mode for environment information factors according to an environment information control process. 
         FIG. 5C  is an illustrative graph illustrating a second control mode for environment information factors according to the environment information control process. 
         FIG. 5D  is an illustrative graph illustrating a third control mode for environment information factors according to the environment information control process. 
         FIG. 6A  is an illustrative diagram illustrating environment information in the normal state. 
         FIG. 6B  is an illustrative diagram illustrating the environment information in the environment information control process. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     (Configuration) 
     A remote operation system as one embodiment of the present invention illustrated in  FIG. 1  comprises a remote operation device  10 , a remote operation server  20 , and a work machine  40 . 
     (Configuration of Work Machine) 
     The work machine  40  comprises a slave control device  400 , an environment recognition device  401 , a wireless communication device  402 , and a working mechanism  440 . The slave control device  400  is comprised of an arithmetic processing device (a single core processor, a multi-core processor, or processor cores that constitute the multi-core processor), which reads necessary data and software from a memory or other storage device, and executes arithmetic processing on the data according to the software. 
     The work machine  40  is, for example, a crawler excavator (construction machine), and comprises a crawler type lower traveling body  410 , and an upper pivoting body  420  pivotally mounted on the lower traveling body  410  through the intermediary of a pivoting mechanism  430  as illustrated in  FIG. 2 . A cab (driver compartment)  422  is provided on the left front side of the upper pivoting body  420 . A work attachment  440  is provided at the front center of the upper pivoting body  420 . 
     The work attachment  440  serving as a working mechanism comprises a boom  441  liftably attached to the upper pivoting body  420 , an arm  443  rotatably connected to the distal end of the boom  441 , and a bucket  445  rotatably connected to the distal end of the arm  443 . To the work attachment  440 , there are attached a boom cylinder  442 , an arm cylinder  444 , and a bucket cylinder  446  that are comprised of expandable hydraulic cylinders. 
     The boom cylinder  442  is interposed between the boom  441  and the upper pivoting body  420  such that the boom cylinder  442  expands or contracts by receiving the supply of hydraulic oil to thereby cause the boom  441  to pivot in an upward or downward direction. The arm cylinder  444  is interposed between the arm  443  and the boom  441  such that the arm cylinder  444  expands or contracts by receiving the supply of hydraulic oil to thereby cause the arm  443  to pivot on a horizontal axis with respect to the boom  441 . The bucket cylinder  446  is interposed between the bucket  445  and the arm  443  such that the bucket cylinder  446  expands or contracts by receiving the supply of hydraulic oil to thereby cause the bucket  445  to pivot on the horizontal axis with respect to the arm  443 . 
     The environment recognition device  401  is installed in the cab  422 , for example, and is comprised of an imaging device configured to capture an image of an environment including at least a part of the working mechanism  440  through a front windshield of the cab  422 . The environment recognition device  401  may comprise an acoustic input device comprised of a microphone or the like. 
     In the cab  422 , there are provided actual machine operation levers corresponding to respective operation levers (described later) included in the remote operation device  10 , and a drive mechanism or a robot configured to receive a signal according to an operation mode of each operation lever from a remote operation room and move the corresponding actual machine operation lever based on the received signal. 
     (Configuration of Remote Operation Device) 
     The remote operation device  10  comprises a master control device  100 , an input interface  110 , and an output interface  120 . At least a part of the remote operation device  10  may be comprised of a mobile terminal device such as a smartphone, a tablet terminal or a notebook PC. The master control device  100  is comprised of an arithmetic processing device (a single core processor, a multi-core processor, or processor cores that constitute the multi-core processor), which reads necessary data and software from a memory or other storage device, and executes arithmetic processing on the data according to the software. 
     The input interface  110  comprises an operating mechanism  111 , and an operation state detector  112 . The output interface  120  comprises an information output device  121 , and a wireless communication device  122 . 
     The operating mechanism  111  includes a travel operation device, a pivoting operation device, a boom operation device, an arm operation device, a bucket operation device, and a cutoff operation device. Each operation device has an operation lever to be subjected to a pivoting operation. The operation lever (travel lever) of the travel operation device is operated to move the lower traveling body  410 . The travel lever may also serve as a travel pedal. For example, the travel pedal fixed to the base or lower end of the travel lever may be provided. The operation lever (pivoting lever) of the pivoting operation device is operated to move a hydraulic pivoting motor included in the pivoting mechanism  430 . The operation lever (boom lever) of the boom operation device is operated to move the boom cylinder  442 . The operation lever (arm lever) of the arm operation device is operated to move the arm cylinder  444 . The operation lever (bucket lever) of the bucket operation device is operated to move the bucket cylinder  446 . 
     The operation lever (cutoff lever) of the cutoff operation device is locked such that the work machine  40  is not moved even when each operation lever such as the travel lever as described above is operated, while is operated to release the lock. 
     Each operation lever constituting the operating mechanism  111  is arranged, for example, around a seat  1100  for an operator to sit on, as illustrated in  FIG. 3 . The seat  1100  is in the form of a high-back chair with armrests, but may be in any form that allows an operator to sit thereon, such as a low-back chair without a headrest, or a chair without a backrest. 
     A pair of left and right travel levers  1110  corresponding to the left and right crawlers are arranged side by side in front of the seat  1100 . A single operation lever may serve as a plurality of operation levers. For example, a right operation lever  1111  provided in front of a right frame of the seat  1100  illustrated in  FIG. 3  may function as the boom lever when operated in a front-rear direction, and may function as the bucket lever when operated in a left-right direction. Similarly, a left operation lever  1112  provided in front of a left frame of the seat  1100  illustrated in  FIG. 3  may function as the arm lever when operated in the front-rear direction, and may function as the pivoting lever when operated in the left-right direction. The lever pattern may be arbitrarily changed according to an operating instruction of the operator. 
     A cutoff lever  1113  provided below the left operation lever  1112  in front of the left frame of the seat  1100  is locked when the cutoff lever  1113  is raised such that the work machine  40  is not moved even when each operation lever  1110 ,  1111 , or  1112  is operated, while functions as an operation lever for releasing the lock when the cutoff lever is lowered. 
     The information output device  121  includes, for example, a diagonally forward right side image output device  1211 , a forward side image output device  1212 , and a diagonally forward left side image output device  1213  that are arranged in the diagonally forward right direction, the forward direction, and the diagonally forward left direction of the seat  1100 , respectively, as illustrated in  FIG. 3 . The information output device  121  may further comprise a speaker (audio output device) arranged inside or around the seat  1100 . 
     The operation state detector  112  detects an operation state of the operation device  10  for causing the operator to move the work machine  40 . For example, the operation state detector  112  includes a sensor configured to output a signal according to a deformation amount or displacement amount of an urging mechanism comprised of a spring or an elastic member acting to cause the operation lever to be returned to original position and posture corresponding to a lever operation amount of zero, and an arithmetic processing device configured to estimate, based on the output signal of the sensor, that the pivoting lever is operated to pivot at a certain speed in a counterclockwise direction as viewed from above the upper pivoting body  420 , and the like. 
     Alternatively, the operation state detector  112  may include a pressure sensitive sensor or a contact sensor provided to at least one of the operation levers constituting the operating mechanism  111 , and the arithmetic processing device configured to estimate that the at least one operation lever is gripped by the operator. Alternatively, the operation state detector  112  may include a pressure sensitive sensor or a contact sensor provided to the seat  1110 , and the arithmetic processing device configured to estimate that the operator is sitting on the seat  1110 . 
     Alternatively, the operation state detector  112  may include a pilot pressure sensor configured to output a signal according to a pilot pressure corresponding to an operation amount of the actual machine operation lever provided to the work machine  40 , and the arithmetic processing device configured to estimate, based on the output signal of the pilot pressure sensor, that the pivoting lever is operated to pivot at a certain speed in the counterclockwise direction as viewed from above the upper pivoting body  420 , and the like. 
     (Configuration of Remote Operation Server) 
     The remote operation server  20  comprises a state recognition element  21 , and an environment information control process element  22 . The state recognition element  21  recognizes an operation state of the remote operation device  10  (or the operating mechanism  111  included in the remote operation device  10 ) or a motion state of the work machine  40 . 
     The environment information control process element  22  performs the environment information control process in different modes according to a difference in the operation state of the remote operation device  10  or the motion state of the work machine  40  that is recognized by the state recognition element  21 . The “environment information control process” refers to an arithmetic process for adjusting each of a plurality of environment information factors that defines an information amount of the environment information to be output by the information output device  121  of the remote operation device  10 , such that a data amount of the environment data is reduced. 
     (Function) 
     In the remote operation device  10 , the operating mechanism  111  is operated by the operator (STEP  102  in  FIG. 4 ), and in response to this, the master control device  100  transmits a motion command according to the operation mode to the remote operation server  20  through the wireless communication device  122  (STEP  104  in  FIG. 4 ). 
     In the remote operation server  20 , the state recognition element  21  receives the motion command from the remote operation device  10 , and transmits the motion command to the work machine  40  (STEP  202  in  FIG. 4 ). 
     In the work machine  40 , the slave control device  400  receives the motion command through the wireless communication device  402  (STEP  402  in  FIG. 4 ). In response to this, the motion of the work attachment  440  and the like is controlled by the slave control device  400  (STEP  404  in  FIG. 4 ). For example, work is performed in which earth forward of the work machine  40  is scooped into the bucket  445 , and the upper pivoting body  420  is caused to pivot, to thereafter allow the earth to fall from the bucket  445 . 
     In the work machine  40 , the environment recognition device  401  acquires a captured image as the environment information (STEP  406  in  FIG. 4 ). At this time, the audio information may be acquired as the environment information. When the master control device  100  controls the wireless communication device  122  so that an operation start command is transmitted from the remote operation device  10  to the work machine  40  through the remote operation server  20 , while using this as a trigger, the environment information may start to be acquired. For example, in the remote operation device  10 , the operation start command is output when a button or an operation lever included in the input interface  110  or the operating mechanism  111  is operated at a predetermined mode. The environment information acquired by the environment recognition device  401  is transmitted from the work machine  40  and is received by the remote operation server  20 . 
     In the remote operation server  20 , the environment information control process is performed by the environment information control process element  22  (STEP  206  in  FIG. 4 ). The “environment information control process” refers to an arithmetic process for adjusting each of a plurality of environment information factors that defines an information amount of the environment information to be output by the information output device  121  of the remote operation device  10 , such that a data amount of the environment data is reduced. Specifically, it refers to an arithmetic process for adjusting the plurality of environment information factors in different modes such that a reduction in the information amount of a “low environment information factor” among the plurality of environment information factors is greater than that of a “high environment information factor” among the plurality of environment information factors. The environment information control process is performed by classifying the environment information factors into the high environment information factor and the low environment information factor in different modes, according to the difference in the operation state that is at least one of a motion command from the remote operation device  10  and the motion state of the work machine  40  according to the motion command. 
     It may be configured that the environment information control process is performed by the environment information control process element  22  only in the case where a result of the determination as to whether to perform the execution process is affirmative. For example, it may be determined whether the operation state of the operating mechanism  111  according to the motion command is a specified operation state to be subjected to the environment information control process. The motion state of the work machine  40  according to the motion command may be recognized by the communication between the remote operation server  20  and the work machine  40 , and it may be determined whether the motion state of the work machine  40  is a specified motion state to be subjected to the environment information control process. The environment information control process element  22  may recognize a communication speed of the communication between the remote operation server  20  and the remote operation device  10  or the work machine  40 , and then determine that the communication speed is below the reference value. 
       FIG. 5A  shows a situation where each value of four environment information factors X 1  to X 4  that defines the information amount of the environment information is a reference value Q 2  normalized with reference to a lower limit value Q 1 , in a normal state, i.e., a state where the environment information control process is not performed. When the environment information is an image, the four environment information factors X 1  to X 4  are, for example, a resolution, a frame rate, the number of dimensions of a pixel value, and a width of an output image range. When the audio is included in the environment information, the plurality of environment information factors include at least one of a sampling frequency, a quantization bit count, and a frequency band of sound, for example.  FIGS. 5B to 5D  each show a target value or a command value of the four environment information factors X 1  to X 4 , in the case where the operation states of  FIGS. 7B to 7D  are first to third specified operation states, respectively. 
     In the first specified operation state, the values of the environment information factors X 1  and X 2  are lower than the reference value Q 2 , and the values of the environment information factors X 3  and X 4  are maintained at the reference value Q 2  (see  FIG. 5B ). In this case, the environment information factors X 3  and X 4  correspond to the “high environment information factor,” and the environment information factors X 1  and X 2  correspond to the “low environment information factor” to be adjusted such that the reduction in the information amount of the environment information is greater than that for the high environment information factor. 
     In the second specified operation state, the values of the environment information factors X 3  and X 4  are lower than the reference value Q 2 , the reduction amount for the environment information factor X 3  is greater than that for the environment information factor X 4 , and the values of the environment information factors X 1  and X 2  are maintained at the reference value Q 2  (see  FIG. 5C ). In this case, the environment information factors X 1  and X 2  correspond to the “high environment information factor,” and the environment information factors X 3  and X 4  correspond to the “low environment information factor” to be adjusted such that the reduction in the information amount of the environment information is greater than that for the high environment information factor. Furthermore, the environment information factor X 4  corresponds to the “high environment information factor (or a primary low environment information factor),” and the environment information factor X 3  corresponds to the “low environment information factor (or a secondary low environment information factor)” to be adjusted such that the reduction in the information amount of the environment information is greater than that for the high environment information factor. 
     In the third specified operation state, the value of the environment information factor X 2  is lower than the reference value Q 2 , the value of the environment information factor X 3  is higher than the reference value Q 2 , and the values of the environment information factors X 1  and X 4  are maintained at the reference value Q 2  (see  FIG. 5D ). In this case, the environment information factor X 3  corresponds to the “high environment information factor,” and the environment information factors X 1 , X 2 , and X 4  correspond to the “low environment information factor” to be adjusted such that the reduction in the information amount of the environment information is greater than that for the high environment information factor. Furthermore, the environment information factors X 1  and X 4  correspond to the “high environment information factor (or the primary low environment information factor),” and the environment information factor X 2  corresponds to the “low environment information factor (or the secondary low environment information factor)” to be adjusted such that the reduction in the information amount of the environment information is greater than that for the high environment information factor. 
     For example, each of the plurality of environment information factors may be adjusted, as shown in Table 1, according to the remote operation state of the work machine  40 . 
     
       
         
           
               
               
             
               
                   
                 TABLE 1 
               
             
            
               
                   
                   
               
               
                   
                 Environment information factor (    : increase,    |: reduction, —: 
               
               
                   
                 maintenance with reference to reference value) 
               
            
           
           
               
               
            
               
                   
                 Pixel value 
               
            
           
           
               
               
               
               
               
            
               
                 Operation content 
                 Resolution 
                 Frame rate 
                 (color) 
                 Image range 
               
               
                   
               
            
           
           
               
               
               
               
               
               
            
               
                 A 
                 State of cutoff lever being 
                 
                   
                 
                     | 
                     (Gray) 
                 — or    | 
               
               
                   
                 raised 
               
               
                 B 
                 State of cutoff lever being 
                 — 
                     | 
                 — (Color) 
                 — 
               
               
                   
                 raised and gripped 
               
               
                 C 
                 Pivoting operation of upper 
                 
                   
                 
                 — 
                 — (Color) 
                 — or    
               
               
                   
                 pivoting body 
               
               
                 D 
                 Parallel traveling operation 
                 — 
                 — 
                 — (Color) 
                 — 
               
               
                   
                 of lower traveling body 
               
               
                 E 
                 Rough excavation 
                 
                      
                 
                 — 
                       (Gray) 
                 — or    
               
               
                 F 
                 Finish excavation 
                 — 
                 — or       
                 — (Color) 
                 — or    
               
               
                   
               
            
           
         
       
     
     In Table 1, the state of the cutoff lever being raised (state A) refers to a state where the operator has no intention to operate the work machine  40 , and the values of the environment information factors are reduced. However, the value of the image range may be maintained to maintain the field of view. 
     The state of the cutoff lever being raised and gripped (state B) refers to a state where the operator has no intention to operate the work machine  40 , similarly to the state A, and achieves a state where the reduction in the environment information factor is relieved when the operator grips the operation lever. For example, the state indicates a state of the environment information factors being adjusted when it is confirmed that a truck for transporting earth and sand will be moved to a predetermined position. Since the work such as excavation is nor performed, the frame rate can be reduced. 
     When the pivoting operation of the upper pivoting body (state C) is performed, the resolution is reduced. This object is to reduce the difficulty of viewing the image and the discomfort that are caused by a high-speed movement of the image. On the other hand, the image range can be increased, to secure the visibility in the pivoting direction. 
     When the parallel traveling operation of the lower traveling body (state D) is performed, highly accurate information is required mainly about the moving direction, and it is desirable that the values of the environment information factors are not reduced. In the case where the reduction in communication load is forced, the maintenance of the image range can take precedence, to secure the visibility in the traveling direction. 
     The rough excavation operation (state E) refers to a state where the excavation is performed up to a surface away from an excavation plan surface while placing importance on the working speed. The frame rate is maintained, but a problem in work does not appear even when the values of the other environment information factors are reduced. When the work involving movement such as the pivoting is performed, it is desirable that the image range is not reduced. 
     The finish excavation operation (state F) refers to a state where a remaining earth and sand region on the excavation plan surface after the rough excavation is excavated, for example. In this state, it is desirable that the values of the environment information factors are not reduced. In the case where the reduction in communication load is forced, when the bucket and the like are operated, the values of the environment information factors are reduced without affecting the workability by maintaining the frame rate while reducing the image range. Additionally, in the case where the operation of bucket and the like is poor such as when the operator confirms the working surface, for example, the image range may be maintained while reducing the frame rate. 
     A grading operation (a combination of the state D and the state E) is also assumed as a combination of the above-described states. When only a leveling work is performed by the bucket, the image range is reduced, but when the traveling operation is added, it is desirable that the image range is not reduced. 
     Subsequently, in the remote operation server  20 , the environment information control process element  22  transmits an environment information control command to the work machine  40  (STEP  208  in  FIG. 4 ). The environment information control command includes the data for specifying the adjustment state of the plurality of factors in addition to the data as to whether the state is the normal state or the specified operation state (whether the environment information control process is performed). 
     In the work machine  40 , the slave control device  400  receives the environment information control command through the wireless communication device  402  (STEP  408  in  FIG. 4 ). The slave control device  400  adjusts a data amount of the environment data indicating the captured image according to the environment information control command, and transmits the data to the remote operation server  20  (STEP  410  in  FIG. 4 ). 
     In the remote operation server  20 , the environment information control process element  22  receives the environment data from the work machine  40 , and transmits the environment data to the remote operation device  10  (STEP  210  in  FIG. 4 ). 
     In the remote operation device  10 , the master control device  100  receives the environment data through the wireless communication device  122  (STEP  106  in  FIG. 4 ). The master control device  100  outputs, to the information output device  121 , the environment information according to the environment data (all or a part of the captured image itself or a simulated environment image generated based on the captured image, as well as all or a part of recorded audio itself or a simulated environment audio generated based on the recorded audio) (STEP  108  in  FIG. 4 ). 
     In this way, in the normal state, as illustrated in  FIG. 6A , for example, the environment information including the boom  441 , the arm  443 , the bucket  445 , and the arm cylinder  444  that are a part of the work attachment  440  serving as the working mechanism is output to each of a high information output device  121  and a low information output device  221 . When the environment information factor X 1  is the “output image range the same as that in the normal state” and the environment information factor X 2  is the “resolution,” in the first specified operation state (see  FIG. 5B ), the environment information is output to the information output device  121 , the information indicating that a part of the environment information (for example, a rectangular region at a center) has the resolution similar to that in the normal state, and the other parts (for example, a region surrounding the partial region in a rectangular shape) have the resolution lower than that in the normal state. Alternatively, when the environment information factor X 1  is the “output image range” and the environment information factor X 2  is the “resolution,” in the first specified operation state, the environment information is output to the information output device  121 , the information indicating that only a part has the resolution lower than that in the normal state (see  FIG. 6B ). 
     A single image region in the information output device  121  may be specified by the “output image range (or the output image range the same as that in the normal state)” as the environment information factor, or a plurality of image regions may be specified. An image region in which a spread state (specified by shape, size, the position of the center of gravity, and the like) is constant in time series in the information output device  12  may be specified by the “output image range” as the environment information factor, or an image region in which the spread state changes in time series in the information output device  121  such as an image region including the bucket  445  may be specified. 
     When the environment information factor X 3  is the “number of dimensions of a pixel value” and the environment information factor X 4  is the “frame rate,” in the second specified operation state (see  FIG. 7C ), the environment information is output to the information output device  121 , the information indicating, for example, that the frame rate of the environment information is reduced (24 to 30 FPS to 2 to 10 FPS) and a two-dimensional (four-dimensional in the case where the color is represented by a three-dimensional vector such as RGB values) pixel value including the color and the brightness value in the normal state has a one-dimensional pixel value including only a brightness value (gray scale). 
     In the case where the information amount of the present environment information is lower than that of the previous environment information, in addition to the present environment information, a predetermined number of pieces of environment information before the previous time may be output from the information output device  121 . For example, in the case where the resolution of the present environment image as the environment information is lower than that of the previous environment image, in addition to the present environment information, the previous environment information of a predetermined number of pieces or environment information before the previous time may be output to and displayed on the information output device. 
     (Effect) 
     According to the remote operation system thus configured and the remote operation server  20  included in the remote operation system, when the “environment information control process” is performed, each value of the plurality of environment information factors that defines the information amount of the environment information is adjusted. Specifically, the data amount of the environment data is reduced such that the reduction in the information amount of one or a plurality of low environment information factors is greater than the reduction in the information amount of one or a plurality of high environment information factors (meaning the reduction in the information amount of the environment information due to a change in the environment information factor) (STEP  206  in  FIG. 4 , see  FIGS. 5A to 5D ). In correspondence to a data amount adjusted such that the reduction in the information amount of the low environment information factors is relatively greater than the reduction in the information amount of the high environment information factors, the data amount can be reduced, and the communication load of the environment data can be reduced. On the other hand, in correspondence to a data amount adjusted such that the reduction in the information amount of the high environment information factors is relatively smaller than the reduction in the information amount of the low environment information factors, the excessive reduction in the data amount, and the excessive reduction in the information amount of the environment information can be avoided. 
     In the case where the environment information control process is performed by classifying the environment information factors into the high environment information factor and the low environment information factor in different modes such that one of the low environment information factors becomes a high environment information factor for another one of the low environment information factors, the width of the adjustment of the plurality of environment information factors is extended according to the difference in the operation state. Therefore, the excessive reduction in the information amount of the environment information can be avoided in an appropriate form further minutely from the standpoint of an operator appropriately grasping the environment of the work machine  40  according to the operation state of the work machine  40  by the operator while reducing the data communication load for outputting the environment information. 
     In the case where the environment information control process element  22  performs the environment information control process on condition that a communication speed of at least one of the remote operation device  10  and the work machine  40  falls below a reference value, the excessive reduction in the data amount of the environment data, and the excessive reduction in the information amount of the environment information can be avoided in the state where the necessity to reduce the communication load of the environment data is low. 
     The environment information control process adjusts each of the plurality of environment information factors in different modes according to a difference in the operation state (at least one state of the motion command according to the operation state of the operating mechanism  111  by the operator and the motion state of the work machine  40  according to the motion command) Specifically, the environment information control process is performed by classifying the environment information factors into the high environment information factor and the low environment information factor in different modes according to the difference (see  FIGS. 5A to 5D ). Therefore, the excessive reduction in the information amount of the environment information can be avoided in an appropriate form from the standpoint of an operator appropriately grasping the environment of the work machine  40  according to the remote operation state of the work machine  40  by the operator while reducing the data communication load for outputting the environment information (see  FIGS. 6A to 6B ). 
     Other Embodiments of the Present Invention 
     In the other embodiments, the environment information control process element  22  included in the remote operation server  20  receives the environment data from the work machine  40  in the same manner as in the normal state, and then performs the environment information control process, whereby the data amount of the environment data to be transmitted to the remote operation device  10  may be adjusted to be increased or reduced. 
     In the other embodiments, the remote operation server  20  or the environment information control process element  22  may be included in the master control device  100 , so that the remote operation device  10  and the work machine  40  can mutually communicate directly or through a radio communication base station. In this case, the environment information control process is performed by the master control device  100  having the same function as that of the environment information control process element  22 , whereby the data amount of the environment data to be transmitted from the work machine  40  to the remote operation device  10  may be adjusted to be increased or reduced. The master control device  100  and the remote operation server  20  can mutually communicate through the communication circuit in a common processor or the communication circuit connecting a separate processor. 
     In the other embodiments, the remote operation server  20  or the environment information control process element  22  may be included in the slave control device  400 , so that the remote operation device  10  and the work machine  40  can mutually communicate directly or through a radio communication base station. In this case, the environment information control process is performed by the slave control device  400  having the same function as that of the environment information control process element  22 , whereby the data amount of the environment data to be transmitted from the work machine  40  to the remote operation device  10  may be adjusted to be increased or reduced. The slave control device  400  and the remote operation server  20  can mutually communicate through the communication circuit in a common processor or the communication circuit connecting a separate processor. 
     In the above-described embodiment, the plurality of environment information factors are adjusted by being classified into the high environment information factor and the low environment information factor. However, as the other embodiments, a plurality of environment information factors may be adjusted uniformly without being classified into the high environment information factor and the low environment information factor according to at least one specified operation state of the remote operation device  10  or at least one specified motion state of the work machine  40 . That is, all of the plurality of environment information factors may be controlled so that the reduction amount from the reference value Q 2  becomes uniform. 
     In the above-described embodiment, the motion command is transmitted from the remote operation device  10  to the work machine  40  through the remote operation server  20  (see STEP  104  STEP  202  STEP  402  in  FIG. 4 ). However, as the other embodiments, the motion command may be transmitted from the remote operation device  10  to the work machine  40  through a radio communication base station. In this case, the environment information control process element  22  may recognize the motion command or the operation state of the remote operation device  10  according to the motion command based on a result of the communication between the remote operation server  20  and the remote operation device  10 . Alternatively, the environment information control process element  22  may recognize the motion state of the work machine  40  according to the motion command based on a result of the communication between the remote operation server  20  and the work machine  40 . 
     In the above-described embodiment, the environment data is transmitted from the work machine  40  to the remote operation device  10  through the remote operation server  20  (see STEP  410 →STEP  210 →STEP  106  in  FIG. 4 ). However, as the other embodiments, the environment data may be transmitted from the work machine  40  to the remote operation device  10  through a radio communication base station. 
     In the above-described embodiment, the environment information control process may be performed on condition that the state of the reduction in the information amount of the environment information when the environment information control process is performed is output to the information output device  121 , and the performance of the environment information control process is permitted through the input interface  110 . 
     The environment data may include “internal environment data” indicating the motion state of the work machine  40  in addition to “external environment data” indicating external environment of the work machine  40 . In this case, the data indicating angles detected by an angle sensor is acquired as the environment data, the angle sensor being provided to the work attachment  440  and configured to detect the angles representing postures of the boom and the arm. For example, in the case where a crawler crane serving as the work machine  40  performs a suspension work, the data indicating the angles of the boom and arm is omitted from the environment data, whereby the data amount of the environment data can be reduced. 
     REFERENCE SIGNS LIST 
       10  . . . Remote operation device,  20  . . . Remote operation server,  21  . . . State recognition element,  22  . . . Environment information control process element,  40  . . . Work machine,  100  . . . Master control device,  110  . . . Input interface,  111  . . . Operating mechanism,  112  . . . Operation state detector,  120  . . . Output interface,  121  . . . Information output device,  122  . . . Wireless communication device,  400  . . . Slave control device,  401  . . . Environment recognition device,  402  . . . Wireless communication device,  440  . . . Work attachment (working mechanism)