Patent Publication Number: US-2023144636-A1

Title: Snow removal system and snow removal method

Description:
TECHNICAL FIELD 
     The present invention relates to a snow removal system and a snow removal method. 
     BACKGROUND ART 
     Patent Literature 1 discloses a technique for registering a route on which an autonomous snow removal machine performs a snow removal work. In this technique, a user carries a special device, and registers position information in the device while walking on the route for snow removal target. The autonomous snow removal machine acquires the registered position information from the device, and performs the snow removal work on the basis of the position information. 
     CITATION LIST 
     Patent Literature 
     [Patent Literature 1] 
     United States Patent Application, Publication No. 2018/0143634 A 
     SUMMARY OF INVENTION 
     Technical Problem 
     However, the technique disclosed in Patent Literature 1 requires work for the user to set the route, which requires time and effort. 
     An object of the present invention is to provide a snow removal system and a snow removal method capable of easily setting a region to be a snow removal target in a snow removal machine. 
     Solution to Problem 
     According to an aspect of the present invention, a snow removal system includes a work machine and a snow removal machine. The work machine includes a work unit configured to perform work and a position detector configured to detect a position of the work machine when the work unit has performed the work and generate position information indicating the detected position. The snow removal machine is capable of autonomous movement and includes a snow removal unit configured to perform snow removal work and a controller configured to cause the snow removal unit to perform the snow removal work on the basis of the position information. 
     According to an aspect of the present invention, a snow removal method includes a work step, a detection step, and a snow removal step. A work machine performs work in the work step. When the work machine has performed the work, in the detection step, the work machine detects a position of the work machine and generates position information indicating the detected position. A snow removal machine performs snow removal work on the basis of the position information in the snow removal step. 
     Advantageous Effects of Invention 
     According to the present invention, in the snow removal system and the snow removal method, a snow removal target region can be easily set in the snow removal machine. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG.  1    is a block diagram illustrating a constitution of a snow removal system according to an embodiment of the present invention. 
         FIG.  2    is a flowchart illustrating a procedure of operation of a work machine according to the embodiment of the present invention. 
         FIG.  3    is a flowchart illustrating a procedure of operation of a snow removal machine according to the embodiment of the present invention. 
         FIG.  4    is a diagram illustrating an example of a snow removal target region in the embodiment of the present invention. 
         FIG.  5    is a diagram illustrating an example of a snow removal target region in the embodiment of the present invention. 
         FIG.  6    is a diagram illustrating an example of a snow removal target region in the embodiment of the present invention. 
         FIG.  7    is a diagram illustrating an example of a snow removal target region in the embodiment of the present invention. 
         FIG.  8    is a diagram illustrating an example of position information in the embodiment of the present invention. 
         FIG.  9    is a block diagram illustrating a constitution of a snow removal system according to a modification example of the embodiment of the present invention. 
         FIG.  10    is a diagram illustrating an example of obstacle information according to a modification example of the embodiment of the present invention. 
         FIG.  11    is a diagram illustrating an example of unevenness information according to a modification example of the embodiment of the present invention. 
         FIG.  12    is a diagram illustrating an example of number-of-people information according to a modification example of the embodiment of the present invention. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Hereinafter, an embodiment of the present invention will be described with reference to the drawings.  FIG.  1    illustrates a constitution of a snow removal system  1  according to the embodiment of the present invention. A constitution of the snow removal system  1  will be described with reference to  FIG.  1   . The snow removal system  1  illustrated in  FIG.  1    includes a work machine  10  and a snow removal machine  20 . 
     For example, the work machine  10  is a blower, a vacuum cleaner, a lawn mower, or an edge mower. A blower is used to return, to a lawn on which a mowing operation has been performed, grass popped out onto a road around the lawn. A vacuum cleaner is used to suck up grass popping out onto the road around the lawn. A lawn mower is used to mow grass on the lawn. The grass means lawn grass. The lawn grass is an example of grass, and other examples of grass include weeds. Accordingly, the lawn mower is an example of a grass mower. An edge mower is used to cut grass at a boundary of the lawn. The work machine  10  may be a device other than a blower, a vacuum cleaner, a lawn mower, and an edge mower. Although one work machine  10  is illustrated in  FIG.  1   , the snow removal system  1  may include a plurality of work machines  10 . 
     The worker may perform the work by holding the work machine  10  by hand. The worker may push the work machine  10  from behind to perform the work. The worker may perform the work by riding on the work machine  10  and operating the work machine. The work machine  10  may be an autonomous work machine capable of autonomous movement. The snow removal machine  20  is an autonomous snow removal machine capable of autonomous movement. The autonomous movement means that the device detects the own position thereof and autonomously controls the movement. 
     For example, the work machine  10  operates in a period different from a period in which the snow removal machine  20  performs snow removal work. The snow removal machine  20  operates in winter, and the work machine  10  operates in spring, summer, or autumn. The day on which the work machine  10  operates may be different from the day on which the snow removal machine  20  operates. The time period in which the work machine  10  operates may be different from the time period in which the snow removal machine  20  operates. 
     The work machine  10  includes a work unit  101 , a position detector  102 , a storage  103 , an information outputter  104 , and a communicator  105 . The work unit  101  includes a prime mover and performs work according to the model of the work machine  10 . When the work machine  10  is a blower, the work unit  101  includes a blower unit that sends air. In a case where the work machine  10  is a vacuum cleaner, the work unit  101  includes an intake unit that sucks air. When the work machine  10  is a lawn mower, the work unit  101  includes a cutter for cutting the grass. 
     When the work machine  10  is a blower or a vacuum cleaner, the work unit  101  performs work of removing grass or the like on a snow removal target region. For example, the snow removal target region is a road. The snow removal target region may include a place (for example, a parking lot) connected to a road. In a case where the work machine  10  is a lawn mower, the work unit  101  performs work of cutting grass in a region (lawn) not serving as a snow removal target. For example, the region where the lawn mowing work is performed is adjacent to the snow removal target region. When the work machine  10  is an edge mower, the work unit  101  performs a work of cutting grass at a boundary of the lawn. 
     The position detector  102  detects the position of the work machine  10  when the work machine  10  is performing work, and generates position information indicating the detected position. For example, the position detector  102  is a global positioning system (GPS) receiver including a processor such as a central processing unit (CPU). 
     The storage  103  stores the position information generated by the position detector  102 . The storage  103  is a storage medium such as a flash memory or a hard disk drive. The storage  103  may be attachable to and detachable from the work machine  10 . 
     The information outputter  104  outputs the position information stored in the storage  103 . For example, the information outputter  104  is a processor such as a CPU. The information outputter  104  communicates with the snow removal machine  20  as a result of the work machine  10  controlling the communicator  105 . The communicator  105  may directly communicate with the snow removal machine  20 . The communicator  105  may communicate with the snow removal machine  20  via a server  30  on a network NW. The information outputter  104  communicates with the snow removal machine  20  by the above-described method, and transmits the position information to the snow removal machine  20 . The information outputter  104  may record the position information in a storage device  40  attachable to and detachable from the work machine  10 . The storage device  40  is a storage medium such as a memory card, a DVD, a CD, or a hard disk drive. 
     The position detector  102  and the information outputter  104  may be circuits such as a large scale integration (LSI), an application specific integrated circuit (ASIC), and a field-programmable gate array (FPGA). The functions of the position detector  102  and the information outputter  104  may be implemented by a processor executing a program. 
     The program may be provided by a “computer-readable recording medium” such as a flash memory. The program may be transmitted from a computer holding the program to the work machine  10  via a transmission medium or by a transmission wave in the transmission medium. A “transmission medium” for transmitting a program is a medium having a function of transmitting information. Examples of the medium having the function of transmitting information include a network (communication network) such as the Internet and a communication line (communication wire) such as a telephone line. The program described above may implement part of the functions described above. Furthermore, the above-described program may be a difference file (difference program). A combination of a program already recorded in the computer and a difference program may realize the above-described functions. 
     The snow removal machine  20  includes an information acquisitor  201 , a storage  202 , a position detector  203 , a snow removal unit  204 , a traveling unit  205 , a controller  206 , and a communicator  207 . The information acquisitor  201  acquires position information of the work machine  10 . For example, the information acquisitor  201  is a processor such as a CPU. The information acquisitor  201  communicates with the work machine  10  by controlling the communicator  207 . The communicator  207  may directly communicate with the work machine  10 . The communicator  207  may communicate with the work machine  10  via the server  30  on the network NW. When the storage device  40  is detached from the work machine  10  and attached to the snow removal machine  20 , the information acquisitor  201  may read the position information from the storage device  40 . 
     The storage  202  stores the position information acquired by the information acquisitor  201 . The storage  202  is a storage medium such as a flash memory or a hard disk drive. The storage  202  may be attachable to and detachable from the snow removal machine  20 . 
     The position detector  203  detects the position of the snow removal machine  20  when the snow removal machine  20  is performing snow removal work, and generates position information indicating the detected position. For example, the position detector  203  is a GPS receiver including a processor such as a CPU. 
     The snow removal unit  204  performs snow removal work in the snow removal target region. For example, the snow removal unit  204  includes a prime mover, an auger that collects snow in front of the snow removal machine  20 , a shooter that shoots the collected snow to a position away from the snow removal machine  20 , and the like. 
     The traveling unit  205  causes the snow removal machine  20  to travel. For example, the traveling unit  205  includes a prime mover, wheels, and the like. 
     The controller  206  controls the snow removal unit  204  and the traveling unit  205 . For example, the controller  206  is a processor such as a CPU. The controller  206  controls the traveling unit  205  on the basis of the position information of the work machine  10  stored in the storage  202  and the position information of the snow removal machine  20  generated by the position detector  203 . As a result of this, the controller  206  causes the snow removal machine  20  to travel in the snow removal target region. 
     The information acquisitor  201 , the position detector  203 , and the controller  206  may be circuits such as LSI, ASIC, and FPGA. The functions of the information acquisitor  201 , the position detector  203 , and the controller  206  may be implemented by a processor executing a program. 
       FIG.  2    illustrates a procedure of the operation of the work machine  10 . The operation of the work machine  10  will be described with reference to  FIG.  2   . 
     When the work machine  10  is powered on, the work unit  101  starts working. The work unit  101  performs work according to the model of the work machine  10  (step S 101 ). 
     After step S 101  is executed, the position detector  102  detects the position of the work machine  10  and generates position information indicating the detected position (step S 102 ). 
     After step S 102  is executed, the position detector  102  stores the generated position information in the storage  103  (step S 103 ). 
     After step S 103  is executed, an unillustrated controller determines whether or not to end the work (step S 104 ). For example, when a button, a switch, or the like for turning off the power of the work machine  10  is operated by the worker, the controller determines to end the work. When the button, the switch, or the like is not operated by the worker, the controller determines to not end the work. 
     In a case where the controller has determined not to end the work, step S 101  is executed again. Until the worker instructs the work machine  10  to end the work, the work unit  101  repeatedly performs the work, and the position detector  102  repeatedly detects the position of the work machine  10 . The work unit  101  may perform the work in step S 101  in parallel with at least part of step S 102 , step S 103 , and step S 104 . 
     When the controller has determined to end the work, the work unit  101  ends the work, and the information outputter  104  outputs the position information (step S 105 ). When the information outputter  104  receives an output request from the snow removal machine  20 , the information outputter  104  may output the position information. The work machine  10  may operate in a mode for outputting the position information. For example, when the work unit  101  is not operating, the information outputter  104  may output the position information. At this time, power may be supplied to the information outputter  104  without supplying the power to the work unit  101 . The information outputter  104  may cause the communicator  105  to sequentially transmit the position information to the server  30  while the work unit  101  is performing the work. 
       FIG.  3    illustrates a procedure of the operation of the snow removal machine  20 . The operation of the snow removal machine  20  will be described with reference to  FIG.  3   . 
     When the snow removal machine  20  is powered on, the information acquisitor  201  acquires the position information of the work machine  10  (step S 201 ). The information acquisitor  201  may acquire the position information after transmitting an output request to the work machine  10 . The snow removal machine  20  may operate in a mode for acquiring the position information. For example, when the snow removal unit  204  is not operating, the information acquisitor  201  may acquire the position information. At this time, power may be supplied to the information acquisitor  201  without supplying the power to the snow removal unit  204 . 
     After step S 201  is executed, the information acquisitor  201  stores the acquired position information in the storage  202  (step S 202 ). After the position information is stored in the storage  202 , the snow removal unit  204  may turn off the power of the snow removal machine  20  without performing the snow removal work. When the power of the snow removal machine  20  is turned on again, the following step S 203  may be executed. 
     After step S 202  is executed, the position detector  203  detects the position of the snow removal machine  20  and generates position information indicating the detected position (step S 203 ). 
     After step S 203  is executed, the controller  206  determines the snow removal target region on the basis of the position indicated by the position information of the work machine  10  stored in the storage  202 . The controller  206  controls the traveling unit  205  on the basis of the position information of the snow removal machine  20  generated by the position detector  203 . That is, the controller  206  controls the traveling unit  205  so that the position of the snow removal machine  20  is included in the snow removal target region (step S 204 ). As a result of this, the snow removal machine  20  travels in the snow removal target region. 
     After step S 204  is executed, the controller  206  causes the snow removal unit  204  to perform snow removal work (step S 205 ). Since the snow removal machine  20  travels in the snow removal target region, the snow removal unit  204  performs the snow removal work in the snow removal target region. 
     For example, in step S 204 , the controller  206  may set the route so that the snow removal machine  20  passes through the entirety of the set snow removal target region, and cause the snow removal machine  20  to travel along the set route. In addition, in a case where the snow removal machine  20  is, for example, a snow removal machine of a type that removes snow by flicking off snow on a road with a rotating brush, the controller  206  may set the direction of the snow removal unit  204  so as to flick off snow toward a region not serving as a snow removal target in step S 205 . In a case where the snow removal machine  20  is a snow removal machine of a type including a blower and a shooter, in step S 205 , the controller  206  may set the direction and angle of the shooter so as to project snow toward a region not serving a snow removal target. 
     After step S 205  is executed, the controller  206  determines whether or not to end the snow removal work (step S 206 ). For example, when a button, a switch, or the like for turning off the power of the snow removal machine  20  is operated by the worker, the controller  206  determines to end the snow removal work. If the button, the switch, or the like is not operated by the worker, the controller  206  determines to not end the snow removal work. 
     In a case where the controller  206  has determined not to end the snow removal work, step S 203  is executed again. Until the worker instructs the snow removal machine  20  to end the snow removal work, the position detector  203  repeatedly detects the position of the snow removal machine  20 , the controller  206  repeatedly controls the traveling unit  205 , and the snow removal unit  204  repeatedly performs the snow removal work. The snow removal unit  204  may perform the snow removal work in step S 205  in parallel with at least apart of step S 203 , step S 204 , and step S 206 . When the controller  206  has determined to end the snow removal work, the traveling unit  205  stops traveling, and the snow removal unit  204  ends the snow removal work. 
     A method of setting a snow removal target region will be described with reference to  FIGS.  4  to  7   .  FIG.  4    illustrates an example of a snow removal target region in a case where the work machine  10  is a blower or a vacuum cleaner. The work machine  10  performs work of removing grass or the like in a region A 101  which is a snow removal target region. The region A 101  surrounds a region A 102 , which is a lawn. The position detector  102  generates position information of the region A 101  where the work has been performed. 
     The region A 101  where the work machine  10  has performed work is a snow removal target region. The controller  206  detects the region A 101  including a position indicated by the position information of the work machine  10 , and sets the region A 101  as a snow removal target region. The controller  206  controls the traveling unit  205  so that the position of the snow removal machine  20  is included in the region A 101 . The snow removal machine  20  performs the snow removal work in the region A 101 . 
       FIG.  5    illustrates an example of a snow removal target region in a case where the work machine  10  is a lawn mower. The work machine  10  performs work of cutting grass in the region A 102  that is a lawn. The region A 102  is surrounded by the region A 101 , which is a road. The position detector  102  generates position information of the region A 102  where the work has been performed. 
     The controller  206  detects the region A 102  including the position indicated by the position information of the work machine  10 , and sets the region A 101  excluding the region A 102  as a snow removal target region. The region A 101  is outside the region A 102 , is adjacent to the region A 102 , and has a predetermined width W 1  set in advance. The width W 1  is the width of the road. The controller  206  controls the traveling unit  205  so that the position of the snow removal machine  20  is included in the region A 101 . The snow removal machine  20  performs the snow removal work in the region A 101 . The worker may set the width W 1  in the snow removal machine  20  by operating an operation portion included in the snow removal machine  20 . 
     The width of the snow removal target region does not need to be the width of the whole road. For example, a region having a width sufficient for a person to pass through may be set as the snow removal target region. In addition, the road is not limited to a road paved for a person or a vehicle to pass through, and examples thereof also include a non-paved road or the like simply having no lawn. 
     In some cases, the lawn is adjacent to a region that is not a road.  FIG.  6    illustrates an example of a snow removal target region in such a case. A region A 103  is a lawn, and the work machine  10  performs work of cutting the grass in the region A 103 . The region A 103  is adjacent to a region A 104  and a region A 105 . The region A 104  is a road. The region A 105  includes a house  601  and a house  602 . The region A 105  may be a forest, a river, or the like. The region A 105  is not a road, and is therefore not a snow removal target region. 
     For example, the controller  206  determines the snow removal target region on the basis of the position information of the work machine  10  and map information. The map information includes at least position information of the road. When the map information indicates that there is a road on the region A 104  side, the controller  206  sets the region A 104  adjacent to the region A 103  and having a predetermined width as a snow removal target region. When the map information indicates that there is no road on the region A 105  side, the controller  206  excludes the region A 105  adjacent to the region A 103  from the snow removal target region. As described above, the controller  206  determines the snow removal target region on the basis of the information indicating the type (road, lawn, or the like) of a region adjacent to the region where the work machine  10  has performed work. 
       FIG.  7    illustrates an example of a snow removal target region in a case where the work machine  10  is an edge mower. The work machine  10  performs work of cutting grass in a region A 106  including a boundary B 1  between the region A 102 , which is a lawn, and the road outside the region A 102 . The position detector  102  generates position information of the region A 106  where the work has been performed. 
     The controller  206  detects the region A 106  including the position indicated by the position information of the work machine  10 . The controller  206  sets a region A 107  surrounding the region A 106  as a snow removal target region in accordance with a predetermined positional relationship between the region A 106  and the snow removal target region. The region A 107  is adjacent to the region A 106  and has a predetermined width W 2  set in advance. The width W 2  is set in consideration of the width of the road. The worker may set the width W 2  in the snow removal machine  20  by operating an operation portion included in the snow removal machine  20 . 
     The predetermined positional relationship indicates that the snow removal target region is outside the region A 106 . When a region not serving as a snow removal target is outside the region A 106  and a snow removal target region is inside the region A 106 , the predetermined positional relationship may indicate that a snow removal target region is inside the region A 106 . For example, the worker inputs the information indicating the positional relationship to the work machine  10  by operating the operation unit of the snow removal machine  20 . The work machine  10  associates that information with the position information of the work machine  10 . 
     The controller  206  determines a snow removal target region on the basis of the position information of the work machine  10  and the above-described information indicating positional relationship. The controller  206  determines that a snow removal target region is outside the region A 106 , and sets the region A 107  as a snow removal target region. The controller  206  controls the traveling unit  205  so that the position of the snow removal machine  20  is included in the region A 107 . The snow removal machine  20  performs snow removal work in the region A 107 . 
     The controller  206  may determine the snow removal target region on the basis of the position information of the work machine  10  and the map information. When the map information indicates that there is a road outside the region A 106 , the controller  206  sets the region A 107  adjacent to the region A 106  and having the predetermined width W 2  as a snow removal target region. When the map information indicates that there is no road inside the region A 106 , the controller  206  excludes the region A 102  adjacent to the region A 106  from the snow removal target region. 
       FIG.  8    illustrates an example of the position information stored in the storage  202 . Model information  801  and position information  802  are associated with each other. The model information  801  indicates the model of the work machine  10 . The position information  802  includes latitude and longitude. In the example illustrated in  FIG.  8   , position information generated by a plurality of work machines  10  is stored in the storage  202 . When the model of the work machine  10  is fixed to one model, the model information  801  is unnecessary. 
     In step S 204  illustrated in  FIG.  3   , the controller  206  determines the snow removal target region in accordance with a method corresponding to the model information  801 . For example, when the model information  801  indicates a blower, the controller  206  determines the snow removal target region in accordance with the method described with reference to  FIG.  4   . In a case where the model information  801  indicates a lawn mower, the controller  206  determines the snow removal target region in accordance with the method described with reference to  FIG.  5    or  FIG.  6   . In a case where the model information  801  indicates an edge mower, the controller  206  determines the snow removal target region in accordance with the method described with reference to  FIG.  7   . 
     The controller  206  may determine the snow removal target region on the basis of the position information of the plurality of work machines  10 . For example, the controller  206  may determine the snow removal target region on the basis of the position information of the blower and the position information of the lawn mower. The controller  206  may determine the snow removal target region on the basis of the position information of the blower and the position information of the edge mower. The controller  206  may determine the snow removal target region on the basis of the position information of the lawn mower and the position information of the edge mower. The controller  206  may determine the snow removal target region on the basis of the position information of the blower, the position information of the lawn mower, and the position information of the edge mower. 
     Since the position information of the plurality of work machines  10  is used, the accuracy of the snow removal target region is improved. In particular, the accuracy of the boundary of the snow removal target region is improved. 
     As described above, when the work machine  10  is performing work, the position detector  102  detects the position of the work machine  10 . The controller  206  determines the snow removal target region on the basis of the position of the work machine  10 . When the work machine  10  is performing work, the position information of the work machine  10  is automatically registered. Therefore, work performed only for registering the position of the snow removal target is unnecessary, and thus the labor of the worker is reduced. Therefore, the snow removal system  1  can easily set the snow removal target region in the snow removal machine  20 . 
     In addition, the work machine  10  can acquire more accurate position information at the work site. Therefore, the accuracy of position recognition is improved as compared with a case where a snow removal target region is designated on the basis of an existing map and the snow removal machine  20  is caused to perform the snow removal work in that region. 
     Modification Example of Embodiment 
       FIG.  9    illustrates a constitution of a snow removal system  1   a  according to a modification example of the embodiment of the present invention. A constitution of the snow removal system  1   a  will be described with reference to  FIG.  9   . The snow removal system  1   a  illustrated in  FIG.  9    includes a work machine  10   a  and a snow removal machine  20 . Description of the same elements as in the constitution illustrated in  FIG.  1    will be omitted. 
     The work machine  10   a  is a blower or a vacuum cleaner, and performs work of removing grass or the like in a snow removal target region. The work machine  10   a  includes a work unit  101 , a position detector  102 , a storage  103 , an information outputter  104 , a camera  106 , and an image processor  107 . 
     The camera  106  includes an imaging element and acquires an image. The image processor  107  processes the image acquired by the camera  106  and generates feature information indicating a feature of the snow removal target region. The image processor  107  includes a processor such as a CPU, a digital signal processor (DSP), or a graphics processing unit (GPU). The storage  103  stores the position information generated by the position detector  102  and the feature information generated by the image processor  107 . The information outputter  104  outputs the position information and the feature information stored in the storage  103 . 
     The snow removal machine  20  includes an information acquisitor  201 , a storage  202 , a position detector  203 , a snow removal unit  204 , a traveling unit  205 , and a controller  206 . The information acquisitor  201  acquires position information and feature information of the work machine  10 . The storage  202  stores the position information and the feature information acquired by the information acquisitor  201 . The controller  206  controls the traveling unit  205  on the basis of the position information of the work machine  10  stored in the storage  202 , the feature information stored in the storage  202 , and the position information of the snow removal machine  20  generated by the position detector  203 . 
     An example in which obstacle information is used as the feature information will be described with reference to  FIG.  10   .  FIG.  10    illustrates obstacle information stored in storage  202 . The obstacle information indicates the position of an obstacle that hinders traveling of the snow removal machine  20  in the snow removal target region. 
     Position information  1001  and obstacle information  1002  are associated with each other. The obstacle information  1002  indicates the presence or absence of an obstacle at a position where the work machine  10  has performed work. For example, the obstacle is a damage such as a hole on a road. The obstacle may be an artifact such as a traffic light, a guardrail, or a road sign. The image processor  107  detects an obstacle by processing the image acquired by the camera  106 . When the obstacle information  1002  indicates that an obstacle is present, the position information  1001  associated with the obstacle information  1002  indicates the position of the obstacle. In the example illustrated in  FIG.  10   , an obstacle exists at a position “NAAk, EXXk” indicated by the position information  1001 . 
     The controller  206  excludes the position of the obstacle from the snow removal target region. The controller  206  controls the traveling unit  205  so that the position of the snow removal machine  20  is included in the snow removal target region and the snow removal machine  20  does not pass the position of the obstacle. As a result, the snow removal system  1  can cause the snow removal machine  20  to perform the snow removal work at a position excluding the position where the obstacle exists. 
     The obstacle information  902  may include information indicating the type of obstacle. The worker may input the obstacle information to the work machine  10  by operating an operation unit included in the snow removal machine  20 . 
     An example of using unevenness information as the feature information will be described with reference to  FIG.  11   .  FIG.  11    illustrates the unevenness information stored in storage  202 . The unevenness information indicates the position of unevenness on the surface of the snow removal target region. 
     Position information  1101  and unevenness information  1102  are associated with each other. The unevenness information  1102  indicates the presence or absence of unevenness at a position where the work machine  10  has performed work. The unevenness is a portion where the height of the surface is uneven. For example, the unevenness is a protrusion such as a stone or a recess such as a depression of a road. The unevenness may be a step. The image processor  107  detects unevenness by processing the image acquired by the camera  106 . When large unevenness that makes traveling of the snow removal machine  20  difficult is detected, the unevenness is recorded as obstacle information. In a case where the unevenness information  1102  indicates that there is unevenness, the position information  1101  associated with the unevenness information  1102  indicates the position of the unevenness. In the example illustrated in  FIG.  11   , unevenness exists at a position “NAAk, EXXk” indicated by the position information  1101 . 
     The controller  206  controls the traveling unit  205  so that the position of the snow removal machine  20  is included in the snow removal target region. In addition, the controller  206  controls the speed of the snow removal machine  20  on the basis of the unevenness information  1102 . For example, the controller  206  causes the snow removal machine  20  to travel at a speed lower than a predetermined speed at a position where the unevenness exists. The controller  206  causes the snow removal machine  20  to travel at a speed higher than the predetermined speed at a position where there is no unevenness. As a result, the snow removal system  1  can control the speed of the snow removal machine  20  in accordance with the unevenness on the road. The worker may input the unevenness information to the work machine  10  by operating an operation unit included in the snow removal machine  20 . 
     An example of using number-of-people information as the feature information will be described with reference to  FIG.  12   .  FIG.  12    illustrates the number-of-people information stored in the storage  202 . The number-of-people information indicates the number of people in the snow removal target region and a time period of work performed by the work machine  10 . 
     Position information  1201 , number of people  1202 , and time  1203  are associated with each other. The number of people  1202  indicates the number of people at the position where the work machine  10  has performed work. The image processor  107  detects a person&#39;s face by processing the image acquired by the camera  106 . The number of detected faces is recorded as the number of people  1202 . The time  1203  indicates the time when the position of the work machine  10  is detected. 
     The controller  206  extracts the number of people  1202  associated with each of two or more times  1203  included in the time period in which the snow removal machine  20  travels. The controller  206  calculates an average value of the extracted two or more times  1203 . The number-of-people information corresponds to a combination of the calculated average value and the time period thereof. The length of the predetermined time period is 5 minutes, 10 minutes, 15 minutes, 30 minutes, 1 hour, or the like. 
     The controller  206  controls the speed of the snow removal machine  20  on the basis of the number-of-people information. For example, the controller  206  causes the snow removal machine  20  to travel at a speed lower than a predetermined speed in a time period in which the average value is larger than a predetermined value. The controller  206  causes the snow removal machine  20  to travel at a speed higher than the predetermined speed in a time period in which the average value is equal to or less than the predetermined value. As a result, the snow removal system  1  can control the speed of the snow removal machine  20  in accordance with the degree of congestion of people on the road. The worker may input the number of people to the work machine  10  by operating the operation unit included in the snow removal machine  20 . 
     The controller  206  may set the work time (schedule of snow removal work) of the snow removal unit  204  on the basis of the number-of-people information. For example, the controller  206  sets the work time of the snow removal unit  204  so that the snow removal unit  204  works a lot in a time period when there are few people or the snow removal unit  204  works only in a time period when there are few people. 
     The work machine  10   a  may be an edge mower. When the work machine  10   a  performs work in the region A 106  illustrated in  FIG.  7   , the image processor  107  may determine whether or not each of the region A 102  and the region A 107  illustrated in  FIG.  7    is a snow removal target region. For example, the image processor  107  may determine whether or not a characteristic structure on the road is captured in the image. The characteristic structure is a traffic light, a guardrail, a road sign, or the like. In a case where the characteristic structure is captured in the image, the image processor  107  may determine that the region shown in the image is a snow removal target region. The image processor  107  may generate positional relationship information indicating a predetermined positional relationship between the region A 106  and the snow removal target region. In the example illustrated in  FIG.  7   , since the region A 107  is a snow removal target region, the predetermined positional relationship indicates that the snow removal target region is outside the region A 106 . 
     The storage  103  may store the position information generated by the position detector  102  and the positional relationship information. The information outputter  104  may output the position information and the positional relationship information stored in the storage  103 . The information acquisitor  201  may acquire the position information of the work machine  10  and the positional relationship information of the work machine  10 . The storage  202  may store the position information and the positional relationship information acquired by the information acquisitor  201 . The controller  206  may determine the snow removal target region on the basis of the position information of the work machine  10  and the positional relationship information. 
     The snow removal machine  20  may include an image processor without the work machine  10   a  including the image processor  107 . The storage  103  may store the position information generated by the position detector  102  and the image generated by the camera  106 . The information outputter  104  may output the position information and the image stored in the storage  103 . The information acquisitor  201  may acquire the position information and the image of the work machine  10 . The storage  202  may store the position information and the image acquired by the information acquisitor  201 . The image processor of the snow removal machine  20  may generate the feature information by processing the image stored in the storage  202 . 
     The storage  103  may store the position information generated by the position detector  102  and accuracy information indicating the accuracy of the position indicated by the position information. For example, the accuracy information indicates the number of GPS satellites detected by the position detector  102 . The information outputter  104  may output the position information and the accuracy information stored in the storage  103 . The information acquisitor  201  may acquire the position information and the accuracy information of the work machine  10 . The storage  202  may store the position information and the accuracy information acquired by the information acquisitor  201 . The controller  206  may control the traveling unit  205  on the basis of the position information of the work machine  10  and the accuracy information. 
     For example, in a region having low accuracy such as a region close to a building or a region close to a tree, the controller  206  may cause the snow removal machine  20  to travel at a speed lower than a predetermined speed. Alternatively, the controller  206  may cause the position detector  102  to recognize the position thereof by using a method (odometry, camera, LiDAR, or the like) other than a method using a global navigation satellite system (GNSS). 
     Summary of Embodiments 
     The above-described embodiment discloses the following snow removal system and snow removal method. 
     According to a first aspect of the present invention, a snow removal system  1  includes a work machine  10  and a snow removal machine  20 . The work machine  10  includes a work unit  101  configured to perform work and a position detector  102  configured to detect a position of the work machine  10  when the work unit  101  has performed the work and generate position information indicating the detected position. The snow removal machine  20  is capable of autonomous movement and includes a snow removal unit  204  configured to perform snow removal work and a controller  206  configured to cause the snow removal unit  204  to perform the snow removal work on the basis of the position information. As a result, the snow removal system  1  can easily set a snow removal target region in the snow removal machine  20 . 
     According to a second aspect of the embodiment, in the first aspect, the work machine  10  further includes an obstacle information generator (for example, camera  106 ) configured to generate obstacle information indicating a position of an obstacle that hinders traveling of the snow removal machine  20  in a first region (for example, region A 101 ) serving as a snow removal target. The controller  206  causes the snow removal unit  204  to perform the snow removal work on the basis of the obstacle information in the first region determined on the basis of the position indicated by the position information. As a result, the snow removal system  1  can avoid performing the snow removal work at a position where an obstacle exists. 
     According to a third aspect of the embodiment, in the first or second aspect, the work machine  10  further includes an unevenness information generator (for example, camera  106 ) configured to generate unevenness information indicating a position of unevenness on a surface of a first region (for example, region A 101 ) serving as a snow removal target. The controller  206  controls a speed of the snow removal machine  20  on the basis of the unevenness information in the first region determined on the basis of the position indicated by the position information. As a result, the snow removal system  1  can cause the snow removal machine  20  to travel safely on a road having unevenness. 
     According to a fourth aspect of the embodiment, in any one of the first to third aspects, the work machine  10  further includes a number-of-people information generator (for example, camera  106 ) configured to generate number-of-people information indicating a number of people in a first region (region A 101 ) serving as a snow removal target and a time period of the work. The controller  206  controls a speed of the snow removal machine  20  or a work time of the snow removal unit  204  on the basis of the number-of-people information in the first region determined on the basis of the position indicated by the position information. As a result, the snow removal system  1  can cause the snow removal machine  20  to travel safely on a road on which many people are present. 
     According to a fifth aspect of the embodiment, in any one of the first to fourth aspects, when the work machine  10  is in a first region (for example, region A 101 ) serving as a snow removal target, the work unit  101  performs the work. The controller  206  causes the snow removal unit  204  to perform the snow removal work in the first region including the position indicated by the position information. As a result, the snow removal system  1  can easily set a region where the work machine  10  has performed the work as a snow removal target region in the snow removal machine  20 . 
     According to a sixth aspect of the embodiment, in any one of the first to fourth aspects, when the work machine  10  is in a second region (for example, A 102 ) that is adjacent to a first region (for example, A 101 ) serving as a snow removal target and that does not serve as the snow removal target, the work unit  101  performs the work. The controller  206  causes the snow removal unit  204  to perform the snow removal work in the first region determined on the basis of the position indicated by the position information. As a result, the snow removal system  1  can easily set a region adjacent to the region where the work machine  10  has performed the work as a snow removal target region in the snow removal machine  20 . 
     According to a seventh aspect of the embodiment, in the sixth aspect, the controller  206  determines the first region (for example, region A 104 ) on the basis of information indicating a type of a region (for example, region A 104  and region A 105 ) adjacent to the second region (for example, region A 103 ). As a result, the snow removal system  1  can set the snow removal target region in the snow removal machine  20  in consideration of the type of the region adjacent to the region where the work machine  10  has performed the work. 
     According to an eighth aspect of the embodiment, in any one of the first to fourth aspects, when the work machine  10  is in a third region (for example, region A 106 ) including a boundary between a first region (for example, region A 101 ) serving as a snow removal target and a second region (for example, region A 102 ) not serving as the snow removal target, the work unit  101  performs the work. The controller  206  causes the snow removal unit  204  to perform the snow removal work in the first region determined on the basis of the position indicated by the position information. As a result, the snow removal system  1  can easily set a region adjacent to the region where the work machine  10  has performed the work as a snow removal target region in the snow removal machine  20 . 
     According to a ninth aspect of the embodiments, in any one of the first to eighth aspects, the work machine  10  includes at least one of a blower, a vacuum cleaner, a grass mower, and an edge mower. As a result, the snow removal system  1  can easily set the snow removal target region in the snow removal machine  20  in accordance with the type of the work machine  10 . 
     According to a tenth aspect of the embodiment, a snow removal method includes a work step, a detection step, and a snow removal step. A snow removal method includes a work step, a detection step, and a snow removal step. The work machine  10  performs work in the work step (for example, step S 101 ). When the work machine  10  has performed the work, in the detection step (for example, step S 102 ), the work machine  10  detects a position of the work machine  10  and generates position information indicating the detected position. The snow removal machine  20  performs snow removal work on the basis of the position information in the snow removal step (for example, steps S 203  and S 204 ). 
     Although the embodiments of the present invention have been described in detail with reference to the drawings, the specific constitution is not limited to the above embodiments, and design changes and the like without departing from the gist of the present invention are also included. The elements described in the above embodiments may be appropriately combined. 
     INDUSTRIAL APPLICABILITY 
     According to each embodiment of the present invention, in the snow removal system and the snow removal method, a snow removal target region can be easily set in the snow removal machine. 
     REFERENCE SIGNS LIST 
     
         
         
           
               1 ,  1   a  Snow removal system 
               10 ,  10   a  Work machine 
               20  Snow removal machine 
               101  Work unit 
               102 ,  203  Position detector 
               103 ,  202  Storage 
               104  Information outputter 
               105 ,  207  Communicator 
               106  Camera 
               107  Image processor 
               201  Information acquisitor 
               204  Snow removal unit 
               205  Traveling unit 
               206  Controller