Patent Publication Number: US-2022237926-A1

Title: Travel management device, travel management method, and recording medium

Description:
TECHNICAL FIELD 
     The present invention relates to a travel management device, a travel management method, and a recording medium. 
     BACKGROUND ART 
     The phenomenon in which a moving body such as an automobile travels in the direction opposite to the forward travel direction permitted on a travel path (travels the wrong way), whereby an accident such as a collision occurs with another moving body, has become a problem. Patent Document 1 discloses a technique of recognizing a road sign from an image captured in front of and/or behind a vehicle and determining whether or not the vehicle is traveling in the wrong direction. 
     PRIOR ART DOCUMENTS 
     Non-Patent Documents 
     [Patent Document 1] PCT International Publication WO No. 2015/098915 
     SUMMARY OF THE INVENTION 
     Problem to be Solved by the Invention 
     It is desirable to be able to detect whether or not a moving body is traveling in the wrong direction not only when traveling of the moving body in the wrong direction has occurred but also as much as possible before the moving body is in the state of traveling in the wrong direction. 
     An example object of the present invention is to provide a travel management device, a travel management method, and a recording medium that solve the above-mentioned problem. 
     Means for Solving the Problem 
     In a first example aspect of the present disclosure, a travel management device includes: a detection means for detecting that a moving body is traveling in a wrong direction on a travel path on which the moving body is currently traveling, based on at least one of a front recognition result and a rear recognition result, the front recognition result indicating display content displayed by a sign appearing in a front captured image, the front captured image being obtained by capturing an image to front of the moving body, the rear recognition result indicating display content displayed by a sign appearing in a rear captured image, the rear captured image being obtained by capturing an image to rear of the moving body; and a prevention means for detecting a possibility of the moving body traveling in a wrong direction in future on a travel path located ahead in a travel direction of the moving body than the travel path on which the moving body is currently traveling, based on at least one of the front recognition result and the rear recognition result. 
     In a second example aspect of the present disclosure, a travel management method includes: detecting that a moving body is traveling in a wrong direction on a travel path on which the moving body is currently traveling, based on at least one of a front recognition result and a rear recognition result, the front recognition result indicating display content displayed by a sign appearing in a front captured image, the front captured image being obtained by capturing an image to front of the moving body, the rear recognition result indicating display content displayed by a sign appearing in a rear captured image, the rear captured image being obtained by capturing an image to rear of the moving body; and detecting a possibility of the moving body traveling in a wrong direction in future on a travel path located ahead in a travel direction of the moving body than the travel path on which the moving body is currently traveling, based on at least one of the front recognition result and the rear recognition result. 
     In a third example aspect of the present disclosure, a recording medium stores a program for causing a computer of a travel management device to execute: detecting that a moving body is traveling in a wrong direction on a travel path on which the moving body is currently traveling, based on at least one of a front recognition result and a rear recognition result, the front recognition result indicating display content displayed by a sign appearing in a front captured image, the front captured image being obtained by capturing an image to front of the moving body, the rear recognition result indicating display content displayed by a sign appearing in a rear captured image, the rear captured image being obtained by capturing an image to rear of the moving body; and detecting a possibility of the moving body traveling in a wrong direction in future on a travel path located ahead in a travel direction of the moving body than the travel path on which the moving body is currently traveling, based on at least one of the front recognition result and the rear recognition result. 
     Effect of the Invention 
     According to an example embodiment of the present invention, it is possible to detect the possibility that a moving body travels in the wrong direction before the moving body is in a state of traveling in the wrong direction. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a diagram showing a travel management system according to the present example embodiment. 
         FIG. 2  is a hardware configuration diagram of the travel management device according to the present example embodiment. 
         FIG. 3  is a hardware configuration diagram of the travel management device according to the present example embodiment. 
         FIG. 4  is a diagram showing a hardware configuration of a drive recorder according to the present example embodiment. 
         FIG. 5  is a function block diagram of a control device provided in the drive recorder according to the present example embodiment. 
         FIG. 6  is a first diagram showing an outline of processing of the travel management device according to the present example embodiment. 
         FIG. 7  is a second diagram showing an outline of processing of the travel management device according to the present example embodiment. 
         FIG. 8  is a third diagram showing an outline of processing of the travel management device according to the present example embodiment. 
         FIG. 9  is a fourth diagram showing an outline of processing of the travel management device according to the present example embodiment. 
         FIG. 10  is a first diagram showing the flow of processing of the drive recorder according to the present example embodiment. 
         FIG. 11  is a first diagram showing the flow of processing of the travel management device according to the present example embodiment. 
         FIG. 12  is a second diagram showing the flow of processing of the travel management device according to the present example embodiment. 
         FIG. 13  is a third diagram showing the flow of processing of the travel management device according to the present example embodiment. 
         FIG. 14  is a fourth diagram showing the flow of processing of the travel management device according to the present example embodiment. 
         FIG. 15  is a second diagram showing the flow of processing of the drive recorder according to the present example embodiment. 
         FIG. 16  is a fourth diagram showing the flow of processing of the travel management device according to the present example embodiment. 
         FIG. 17  is a diagram showing an example of the configuration of the travel management device according to the present example embodiment. 
     
    
    
     EXAMPLE EMBODIMENTS 
     Hereinbelow, a travel management system including a travel management device according to an example embodiment of the present invention will be described with reference to the drawings. 
       FIG. 1  is a diagram showing a travel management system  100  according to an example embodiment of the present invention. 
     As shown in  FIG. 1 , the travel management system  100  includes a travel management device  1  and a drive recorder  2  that is an aspect of a driving status sensing device. The travel management device  1  and the drive recorder  2  are connected via a wireless communication network or a wired communication network. The drive recorder  2  is provided in a vehicle  20 . The travel management device  1  is communicatively connected with the drive recorder  2  installed in each of a plurality of vehicles  20  traveling in a city. In the present disclosure, the vehicle  20  is an example of a moving body. 
       FIG. 2  is a hardware configuration diagram of the travel management device  1 . 
     As shown in  FIG. 2 , the travel management device  1  is a computer including hardware such as a CPU (Central Processing Unit)  101 , a ROM (Read Only Memory)  102 , a RAM (Random Access Memory)  103 , a database  104 , and a communication module  105 . 
       FIG. 3  is a hardware configuration diagram of the travel management device  1 . 
     The travel management device  1  is activated when the power is turned on, and executes a travel management program stored in advance. Thereby, the travel management device  1  exhibits at least the functions of a control unit  11 , an acquisition unit  12 , a sign recognition unit  13 , a detection unit (wrong-way travel detection unit)  14 , a prevention unit (wrong-way travel prevention unit)  15 , and an output unit  16 . 
     The control unit  11  controls each function unit of the travel management device  1 . 
     The acquisition unit  12  acquires a front captured image obtained by capturing an image to the front of the vehicle  20  and a rear captured image obtained by capturing an image to the rear of the vehicle  20 . 
     The sign recognition unit  13  generates a front recognition result indicating the display content of a sign displayed in the front captured image and a rear recognition result indicating the display content of a sign displayed in the rear captured image. 
     The detection unit  14  detects that the vehicle  20  is traveling on the travel path in the direction opposite to the forward travel direction permitted on the travel path (traveling the wrong way) on the basis of at least one of the front recognition result and the rear recognition result. The detection unit  14  recognizes the forward travel direction permitted on the travel path on which the vehicle  20  is traveling (the direction that is set on the travel path and in which the vehicle  20  is permitted to travel) on the basis of at least one of the front recognition result and the rear recognition result. 
     The prevention unit  15  detects the possibility of the vehicle  20  traveling in the wrong direction on the travel path in the future on the basis of the front recognition result and the rear recognition result. 
     Upon detecting that the vehicle  20  is traveling in the wrong direction, or upon detecting the possibility of the vehicle  20  traveling in the wrong direction on the travel path in the future, the output unit  16  outputs alarm information to the drive recorder  2  provided in the vehicle  20 . 
       FIG. 4  is a diagram showing the hardware configuration of the drive recorder  2 . 
     The drive recorder  2  includes at least an information acquisition device  21 , a communication device  22 , a front camera  231 , a rear camera  232 , a control device  24 , a storage device  25 , an alarm  26 , and the like. In this disclosure, an example in which the drive recorder  2  is provided with the front camera  231  and the rear camera  232  will be described, but the present invention is not limited to such an example. For example, the front camera  231  and the rear camera  232  may be provided external to the drive recorder  2  and transmit the captured images to the drive recorder  2 . 
     The information acquisition device  21  is connected to a GPS sensor  3  by, for example, a signal line or the like. The information acquisition device  21  acquires position information such as the current latitude and longitude of the vehicle  20  from the GPS sensor  3 . The information acquisition device  21  may acquire information detected by another sensor. The information detected by these sensors is collectively referred to as sensing information. 
     The communication device  22  is communicably connected to the travel management device  1 . The communication device  22  may be communicably connected to the travel management device  1  via a base station device or the like. 
     The front camera  231  generates a captured image by capturing an image to the front of the vehicle  20 . It is assumed that the front camera  231  is installed at a position capable of capturing an image of a sign installed on the road of the vehicle  20 . The captured image generated by the front camera  231  is referred to as a front captured image. 
     The rear camera  232  generates a captured image by capturing an image to the rear of the vehicle  20 . It is assumed that the rear camera  232  is also installed at a position capable of capturing an image of a sign installed on the road of the vehicle  20 . The captured image generated by the rear camera  232  is referred to as a rear captured image. 
     The control device  24  controls each function of the drive recorder  2 . The control device  24  is a computer including a CPU, ROM, RAM, and the like. 
       FIG. 5  is a function block diagram of the control device provided in the drive recorder  2 . 
     The control device  24  executes a control program when the drive recorder  2  is activated. As a result, the control device  24  exhibits each function of a captured image transmission unit  241  and a sensing information transmission unit  242 . 
     The captured image transmission unit  241  acquires the front captured image generated by the front camera  231  and the rear captured image generated by the rear camera  232  and transmits the captured images to the travel management device  1 . 
     The sensing information transmission unit  242  acquires sensing information such as the current position information of the vehicle  20  from the information acquisition device  21  and transmits the sensing information to the travel management device  1 . 
     The travel management device  1  according to the present disclosure generates a front recognition result indicating the display content displayed by a sign appearing in the front captured image obtained by capturing an image to the front of the vehicle  20 , and a rear recognition result indicating the display content displayed by a sign appearing in the rear captured image obtained by capturing an image to the rear of the vehicle  20 . The travel management device  1  detects the possibility of the vehicle  20  traveling in the wrong direction on the travel path in the future on the basis of the recognition results. Thereby, the travel management device  1  can detect the possibility of the vehicle  20  traveling in the wrong direction before the vehicle  20  is in a state of traveling in the wrong direction. Further, the travel management device  1  detects that the vehicle  20  is traveling in the wrong direction on the travel path at the position where the vehicle  20  is currently traveling, on the basis of at least one of the front captured image and the rear captured image. 
       FIG. 6  is a first diagram showing the outline of processing of the travel management device  1 . 
     It is assumed that a travel path  61  shown in  FIG. 6  is one-way. When the vehicle  20  is not traveling in the wrong direction on the travel path  61 , the angle formed by an advancing direction  611  of the vehicle  20  and a forward travel direction  612  of the travel path  61  is close to 0 degrees. Then, when the vehicle  20  advances on the travel path  61  in the same direction as the forward travel direction  612  and there is a sign ahead, the sign appears in the front captured image. 
       FIG. 7  is a second diagram showing the outline of processing of the travel management device  1 . 
     When the vehicle  20  is traveling in the direction opposite to the forward travel direction  612  (traveling the wrong way) on the travel path  61 , although there is a possibility of a no-entry sign appearing in the front captured image generated by the imaging of the front camera  231  of the vehicle  20 , a sign directed at the vehicle  20  traveling in the forward travel direction  612  does not appear. On the other hand, a sign for the vehicle  20  heading in the forward travel direction  612  does appear in the rear captured image. When such a situation is detected, the travel management device  1  determines that the vehicle  20  is traveling in the wrong direction. Further, when there is a possibility of traveling in the wrong direction on the travel path  61 , a no entry sign  71  for the vehicle  20  which may travel in the wrong direction on the travel path  61  appears in the front captured image at the time of entering the travel path  61 . When such a situation is detected, the travel management device  1  determines that, although the vehicle  20  is not traveling in the wrong direction, there is a possibility of the vehicle  20  traveling in the wrong direction. 
       FIG. 8  is a third diagram showing an outline of processing of the travel management device  1 . 
     A case is assumed of the vehicle  20  entering the one-way travel path  61  from the roadside of the travel path  61 . For example, if there is a parking lot beside the travel path  61 , or if there is another travel path leading to the travel path  61  and the vehicle  20  enters the one-way travel path  61  from that travel path, there is a possibility of the vehicle  20  accidentally traveling on the travel path  61  in the direction opposite to the forward travel direction of the travel path  61 . In such a situation, the travel management device  1  determines whether the angle formed by the advancing direction of the vehicle  20  and the forward travel direction exceeds 90 degrees, and if the angle exceeds 90 degrees, determines there is a possibility of the vehicle  20  traveling in the wrong direction. 
       FIG. 9  is a fourth diagram showing an outline of processing of the travel management device  1 . 
     There is a possibility of the vehicle  20  trying to turn from a state in which the vehicle  20  is traveling in the forward travel direction on the one-way travel path  61  to a state of traveling in the wrong direction. Even in such a situation, the travel management device  1  determines whether the angle formed by the advancing direction of the vehicle  20  and the forward travel direction exceeds 90 degrees, and if the angle exceeds 90 degrees, determines there is a possibility of traveling in the wrong direction. 
       FIG. 10  is a first diagram showing the flow of processing of the drive recorder  2 . 
     Next, the flow of processing of the drive recorder  2  will be explained step by step. 
     When the electrical system of the vehicle  20  is activated, the drive recorder  2  starts operation (Step S 101 ). When the electrical system of the vehicle is activated, a sensor device such as a GPS sensor  3  starts sensing. The information acquisition device  21  acquires position information from the drive recorder  2  after the drive recorder  2  is started. The information acquisition device  21  outputs the sensing information obtained from the GPS sensor  3  and the like to the control device  24 . 
     In the drive recorder  2 , the front camera  231  generates a front captured image. In the drive recorder  2 , the rear camera  232  generates a rear captured image. The front camera  231  outputs the front captured image to the control device  24 . The rear camera  232  outputs the rear captured image to the control device  24 . The control device  24  acquires at least the sensing information, the front captured image, and the rear captured image (Step S 102 ). In the control device  24 , the captured image transmission unit  241  requests the communication device  22  to transmit the front captured image and rear captured image that were acquired. Further, the sensing information transmission unit  242  requests the communication device  22  to transmit the acquired sensing information. The communication device  22  transmits the front captured image, the rear captured image, and the sensing information to the travel management device  1  (Step S 103 ). The generation time of the information, the ID (identifier) of the drive recorder  2 , and the like are stored in the front captured image, the rear captured image, and the sensing information. 
       FIG. 11  is a first diagram showing the flow of processing of the travel management device  1 . 
     In the travel management device  1 , the acquisition unit  12  acquires the sensing information, the front captured image, and the rear captured image transmitted from the drive recorder  2  (Step S 201 ). The acquisition unit  12  stores the sensing information, the front captured image, and the rear captured image in the database  104  in association with each other. 
     In the database  104 , the sensing information, the front captured image, and the rear captured image may be recorded in association with each other based on the ID of the drive recorder  2  and the time. The acquisition unit  12  acquires the sensing information, the front captured image, and the rear captured image from the drive recorder  2  of the driving vehicle  20  at predetermined timing intervals or sequentially, and records those pieces of information in the database  104 . Then, the control unit  11  instructs the sign recognition unit  13 , the detection unit  14 , and the prevention unit  15  to perform processing. 
     The sign recognition unit  13  acquires from the database  104  a new front captured image acquired from a certain drive recorder  2 . The sign recognition unit  13  analyzes the front captured image to recognize the display content of a sign included in the image (Step S 202 ). Further, the sign recognition unit  13  acquires from the database  104  a new rear captured image acquired from the drive recorder  2 . The sign recognition unit  13  analyzes the rear captured image to recognize the display content of the sign included in the image (Step S 203 ). A known technique may be used for the recognition process of the display contents of these signs. For example, in the recognition process of the display content of a sign, the front captured image and the rear captured image are input to a recognition model generated by machine learning or the like in the past, and the display content of the sign is recognized on the basis of the result output by the recognition model. The sign recognition unit  13  records the front recognition result, which is the analysis result of the front captured image and indicates the presence/absence of a sign and the display content of the sign, in the database  104  in association with the front captured image. Further, the sign recognition unit  13  records the rear recognition result, which is the analysis result of the front captured image and indicates the presence/absence of a sign and the display content of the sign, in the database  104  in association with the rear captured image. The sign recognition unit  13 , upon finishing recording of the front recognition result and the rear recognition result, outputs to the detection unit  14  the ID of the drive recorder  2  that transmitted the front captured image and the rear captured image to be processed. The sign recognition unit  13  repeats the same process on each acquisition of a front captured image and a rear captured image from each drive recorder  2  of the plurality of vehicles  20 . 
     The detection unit  14  acquires the front recognition result and the rear recognition result of the acquired ID and the position information associated therewith from the database  104 . The detection unit  14  detects (determines) whether or not the vehicle  20  is traveling in the wrong direction on the current travel path corresponding to the position indicated by the acquired position information, on the basis of the presence/absence of a sign indicated by the front recognition result, the display content of the sign, the presence/absence of a sign indicated by the rear recognition result, and the display content of the sign (Step S 204 ). 
     When the detection unit  14  has detected that the vehicle  20  is traveling in the wrong direction, the detection unit  14  instructs the output unit  16  to output warning information. The output unit  16  outputs warning information indicating that the vehicle  20  is traveling in the wrong direction to the drive recorder  2  (Step S 205 ). Thereby, the drive recorder  2  acquires the alarm information and emits an alarm sound or a voice alarm. The driver can recognize that the vehicle  20  is traveling in the wrong direction. Even when the vehicle  20  is an autonomous driving vehicle, the detection unit  14  may detect that the vehicle  20  is traveling in the wrong direction. 
     Upon having detected that the vehicle  20  is not traveling in the wrong direction, the detection unit  14  recognizes that the current travel direction is the forward travel direction on the travel path, and records the ID of the travel path corresponding to the current position and information indicating the forward travel direction in the database  104  or the like in association with each other (Step S 206 ). The information of the travel forward direction is used for the processing of the prevention unit  15 . 
     Then, the detection unit  14  determines whether to end the process (Step S 207 ), and in the case of not ending the process, stands by for input of the ID of the drive recorder  2  from the sign recognition unit  13 , and upon receiving the input repeats the process from Step S 201 . 
       FIG. 12  is a second diagram showing the flow of processing of the travel management device  1 . 
     The process for detecting travel in the wrong direction in Step S 204  described above will be described more specifically. When the front recognition result indicates that there is a sign, the detection unit  14  reads the display content of the sign from that recognition result and determines whether the display content is display content indicating an entry restriction (for example, prohibition of vehicle entry) (Step S 301 ). When the display content shown by the front recognition result is not display content indicating an entry restriction, the detection unit  14  acquires the current position information of the vehicle  20  based on the sensing information. The detection unit  14  determines whether or not the front recognition result shows display content other than an entry restriction in all the front captured images captured up to now on the same travel path currently being traveled that corresponds to that position information (Step S 302 ). When the forward recognition result does not indicate display content other than an entry restriction (Step S 302 : No), the detection unit  14  determines whether the rear recognition result on the current travel path indicates that there is a sign (Step S 303 ). 
     When the display content of a sign shown by the rear recognition result indicates a restriction such as no entry, road closed to all, or the like, the detection unit  14  determines the travel path currently being traveled to be a travel path on which travel in the opposite direction is not permitted. The ID and position information indicating the travel path and information on the forward travel direction of that travel path specified as a result of determining that travel in the opposite direction is not permitted are recorded in association with each other in the database  104 . This information on the forward travel direction is used in the processing of the prevention unit  15 . 
     Upon having determined in Step S 301  that the display content of the forward recognition result is display content indicating an entry restriction, the detection unit  14  determines that the vehicle  20  is traveling in the wrong direction (Step S 304 ). Alternatively, upon having determined that the front recognition result does not indicate display content other than an entry restriction in Step S 302  and that the rear recognition result on the current travel path indicates that there is a sign in Step S 303 , the detection unit  14  determines that the vehicle  20  is traveling in the wrong direction (Step S 304 ). Further, when the front recognition result indicates display content other than an entry restriction in Step S 302  (Step S 302 : Yes), or when the rear recognition result on the current travel path indicates there is no sign in Step S 303 , the detection unit  14  determines that the vehicle  20  is not traveling in the wrong direction (Step S 305 ). 
       FIG. 13  is a third diagram showing the flow of processing of the travel management device  1 . 
     The travel management device  1  performs the following processing for preventing travel in the wrong direction in parallel with the processing for detecting travel in the wrong direction described above. 
     In the travel management device  1 , the acquisition unit  12  acquires the sensing information, the front captured image, and the rear captured image transmitted from the drive recorder  2  (Step S 401 ). The acquisition unit  12  stores the sensing information, the front captured image, and the rear captured image in the database  104  in association with each other. 
     In the database  104 , the sensing information, the front captured image, and the rear captured image may be recorded in association with each other based on the ID of the drive recorder  2  and the time. The acquisition unit  12  acquires the sensing information, the front captured image, and the rear captured image from the drive recorder  2  of the driving vehicle  20  at predetermined timing intervals or sequentially, and records those pieces of information in the database  104 . Then, the control unit  11  instructs the sign recognition unit  13 , the detection unit  14 , and the prevention unit  15  to perform processing. 
     The sign recognition unit  13  acquires from the database  104  a new front captured image acquired from a certain drive recorder  2 . The sign recognition unit  13  analyzes the front captured image to recognize the display content of the sign included in the image (Step S 402 ). Further, the sign recognition unit  13  acquires from the database  104  a new rear captured image acquired from the drive recorder  2 . The sign recognition unit  13  analyzes the rear captured image to recognize the display content of the sign included in the image (Step S 403 ). The sign recognition unit  13  records the front recognition result, which is the analysis result of the front captured image and shows the presence/absence of a sign and the display content of the sign, in the database  104  in association with the front captured image. Further, the sign recognition unit  13  records the rear recognition result, which is the analysis result of the front captured image and shows the presence/absence of a sign and the display content of the sign, in the database  104  in association with the rear captured image. The sign recognition unit  13 , upon finishing recording of the front recognition result and the rear recognition result, outputs the ID of the drive recorder  2  that transmitted the front captured image and the rear captured image to be processed to the prevention unit  15 . Since the processes of steps S 401  to S 403  are the same as the processes of the detection unit  14 , they may be common processes. 
     The prevention unit  15  acquires the front recognition result, the rear recognition result, and the position information recorded in the database  104  in association with the ID acquired from the sign recognition unit  13 . The prevention unit  15  also acquires from the database  104  the forward travel direction of the travel path currently being traveled or a travel path in the vicinity of the current position. Then, the prevention unit  15  detects whether or not there is a possibility of traveling in the wrong direction on the travel path in the future on the basis of the presence/absence of a sign and the display content of the sign that are indicated by the front recognition result, the presence/absence of a sign and the display content of the sign that are indicated by the rear recognition result, and the forward travel direction of the travel path currently being traveled or a travel path in the vicinity of the present position (Step S 404 ). 
     Upon having detected that there is a possibility of traveling in the wrong direction, the prevention unit  15  instructs the output unit  16  to output warning information. The output unit  16  outputs warning information to the drive recorder  2  indicating there is a possibility of traveling in the wrong direction. As a result, the drive recorder  2  acquires the alarm information and emits an alarm sound or a voice alarm. The driver is able to recognize that there is a possibility of traveling in the wrong direction. Even when the vehicle  20  is an autonomous driving vehicle, the prevention unit  15  may detect there is a possibility of traveling in the wrong direction. 
     In the case of having detected that there is no possibility of traveling in the wrong direction, or in the case of having output the warning information in Step S 405 , the prevention unit  15  determines whether to end the process (Step S 406 ). In the case of not ending the process, the prevention unit  15  stands by for input of the ID of the drive recorder  2 , and upon receiving the input repeats the process from Step S 401 . 
       FIG. 14  is a fourth diagram showing the flow of processing of the travel management device  1 . 
     The process for preventing travel in the wrong direction in Step S 404  described above will be described more specifically. When the front recognition result indicates that there is a sign, the prevention unit  15  reads the display content of the sign from that recognition result and determines whether the display content is display content indicating an entry restriction (Step S 501 ). When the display content shown by the front recognition result is not display content indicating an entry restriction, the prevention unit  15  acquires the current position information of the vehicle  20  based on the sensing information. The prevention unit  15  detects the travel direction at the current position. Further, the prevention unit  15  acquires from the database  104  information on the forward travel direction of the travel path located ahead in the travel direction, on the basis of the current position information and the travel direction. The prevention unit  15  compares the current travel direction with the acquired forward travel direction of the travel path, and determines whether only one forward travel direction is recorded in the database  104  for the travel path located ahead or the travel path currently being traveled, and whether the angle formed by the vector between the current travel direction and that forward travel direction is 90 degrees or more (Step S 502 ). 
     In the process of Step S 502 , for example, in the case of returning to a travel path from a parking lot in the vicinity of that travel path, on which only one-way traffic is permitted, when the angle between the advancing direction of the vehicle and the forward travel direction of the travel path is 90 degrees or more, it is determined that there is a possibility of the vehicle traveling the wrong direction in the one-way traffic. For example, in the case of returning from the service area of an expressway to the main expressway, when the angle between the forward travel direction of the travel path leading to the main expressway and the current advancing direction of the vehicle is 90 degrees or more, it is determined that there is a possibility of the vehicle traveling in the wrong direction on the one-way travel path from the main expressway to the service area. 
     Upon having determined in Step S 501  that the display content of the front recognition result is display content indicating an entry restriction, the prevention unit  15  determines that there is a possibility of traveling in the wrong direction (Step S 503 ). 
     Alternatively, when only one forward travel direction is recorded in the database  104  for the travel path located ahead or the travel path currently being traveled, and the angle formed by the vector between the current travel direction and the forward travel direction is 90 degrees or more in Step S 502 , the prevention unit  15  determines there is a possibility of the vehicle traveling in the wrong direction (Step S 503 ). If NO in Step S 502 , the prevention unit  15  determines there is no possibility of the vehicle traveling in the wrong direction (Step S 504 ). 
     The travel management device  1  of the present disclosure has been described above. According to the above processing, the travel management device  1  can detect the state in which the vehicle  20  is traveling in the wrong direction or the possibility of the vehicle  20  (moving body) traveling in the wrong direction before the vehicle  20  travels in the wrong direction. According to the processing of the travel management device  1  of the present disclosure, since detection of travel in the wrong direction and detection of the possibility of travel in the wrong direction are performed by utilizing the information of signs, it is possible to perform those detections over the entire road area where a sign would exist. That is, the detectable area can be widened. According to the above-mentioned processing of the travel management device  1 , since information of road signs at the time of traveling of the moving body is utilized, it is possible to prevent erroneous detection of travel in the wrong direction or the possibility of travel in the wrong direction due to out-of-date map information. 
     In the above process, the sign recognition unit  13  may recognize a sign installed on the roadside or may recognize a sign printed on the road. The sign recognition processing unit  13  may perform recognition of the presence/absence of a sign and recognition of the display content on the basis of the pixel information of only a predetermined area where a sign is likely to appear in the front captured image and the rear captured image. The sign recognition unit  13  may determine the position of the predetermined area where the sign appears based on the detection of a guardrail, a travel line on the road surface, or the like. Further, the travel management device  1  may specify position information indicating a position at which it is detected that the vehicle  20  is traveling in the wrong direction and position information indicating a position at which the possibility of the vehicle  20  traveling in the wrong direction is detected, and statistically process the positions where it is detected that the vehicle travels in the wrong direction or where there is a high possibility of traveling in the wrong direction. This statistically processed information may be used for city planning and the like. 
     The travel management device  1  may store information of the result of detecting that the vehicle  20  is traveling in the wrong direction and the result of detecting the possibility that the vehicle  20  is traveling in the wrong direction, which are generated by the above processing, for use in driving tendency analysis of the driver who drives the vehicle  20 . Further, the travel management device  1  may use information of the result of detecting that the vehicle  20  is traveling in the wrong direction and the result of detecting the possibility that the vehicle  20  is traveling in the wrong direction for output as driving history information. 
     The above-mentioned process is a process assuming a case where the travel management device  1  and the drive recorder  2  are communicably connected and the travel management device  1  is configured as a server device connected to a communication network. However, the function of the travel management device  1  may be provided in an in-vehicle device such as a drive recorder  2 . Hereinbelow, processing when the drive recorder  2  is provided with the function of the travel management device  1  will be described. 
       FIG. 15  is a second diagram showing the flow of processing of the drive recorder  2 . 
     When the electric system of the vehicle  20  is activated, the drive recorder  2  starts operation (Step S 601 ). When the electrical system of the vehicle is activated, a sensor device such as a GPS sensor  3  starts sensing. The information acquisition device  21  acquires position information from the drive recorder  2  after the drive recorder  2  is started. The information acquisition device  21  outputs the sensing information such as GPS information to the control device  24 . 
     In the drive recorder  2 , the front camera  231  generates a front captured image. In the drive recorder  2 , the rear camera  232  generates a rear captured image. The front camera  231  outputs the front captured image to the control device  24 . The rear camera  232  outputs the rear captured image to the control device  24 . The control device  24  acquires at least the sensing information, the front captured image, and the rear captured image (Step S 602 ). The control device  24  performs a process corresponding to the above-mentioned travel management device  1 . That is, the control device  24  exhibits the function of each processing unit shown in  FIG. 3 . Hereinbelow, a case where the control device  24  includes the travel management device  1  will be described. 
     The acquisition unit  12  of the travel management device  1  acquires sensing information, a front captured image, and a rear captured image from the control device  24 . The acquisition unit  12  stores the sensing information, the front captured image, and the rear captured image in the storage device  25  in association with each other. In the storage device  25 , the sensing information, the front captured image, and the rear captured image may be recorded in association with each other based on the ID of the drive recorder  2  and the time. The acquisition unit  12  sequentially acquires the sensing information, the front captured image, and the rear captured image, and records those pieces of information in the storage device  25 . Then, the control unit  11  instructs the sign recognition unit  13 , the detection unit  14 , and the prevention unit  15  to perform processing. 
     The sign recognition unit  13  acquires from the storage device  25  a new front captured image that was acquired. The sign recognition unit  13  analyzes the front captured image to recognize the display content of a sign included in the image (Step S 604 ). Further, the sign recognition unit  13  acquires from the storage device  25  a new rear captured image that was acquired. The sign recognition unit  13  analyzes the rear captured image to recognize the display content of a sign included in the image (Step S 605 ). The sign recognition unit  13  records the front recognition result, which is the analysis result of the front captured image and indicates the presence/absence of a sign and the display content of the sign, in the storage device  25  in association with the front captured image. Further, the sign recognition unit  13  records the rear recognition result, which is the analysis result of the front captured image and indicates the presence/absence of a sign and the display content of the sign, in the storage device  25  in association with the rear captured image. The sign recognition unit  13 , upon finishing recording of the front recognition result and the rear recognition result, instructs the detection unit  14  to perform processing. The sign recognition unit  13  repeats the same process on each acquisition of a front captured image and a rear captured image. 
     The detection unit  14  acquires a new front recognition result, a rear recognition result, and position information associated therewith from the storage device  25 . The detection unit  14  detects whether or not the vehicle is traveling in the wrong direction on the current travel path corresponding to the position indicated by the acquired position information, on the basis of the presence/absence of a sign and the display content of the sign that are indicated by the front recognition result, and the presence/absence of a sign and the display content of the sign that are indicated by the rear recognition result (Step S 606 ). 
     When the detection unit  14  has detected that the vehicle  20  is traveling in the wrong direction, the detection unit  14  instructs the output unit  16  to output warning information. The output unit  16  outputs alarm information to the alarm  26  (Step S 607 ). Thereby, the alarm  26  emits an alarm sound or a voice alarm. The driver can recognize that the vehicle  20  is traveling in the wrong direction. 
     Upon having detected that the vehicle  20  is not traveling in the wrong direction, the detection unit  14  recognizes that the current travel direction is the forward travel direction on the travel path, and records the ID of the travel path corresponding to the current position and information indicating the forward travel direction in the storage device  25  in association with each other (Step S 608 ). The information of the forward travel direction is used for the processing of the prevention unit  15 . The detection unit  14  determines whether to end the process (Step S 609 ), and in the case of not ending the process, stands by for a process instruction from the sign recognition unit  13 , and upon receiving input of the process instruction, repeats the same process from the Step S 603 . The details of the process for detecting travel in the wrong direction are the same as the process described with reference to  FIG. 12  described above. 
     The prevention unit  15  acquires the front recognition result, the rear recognition result, and the position information recorded in the storage device  25  in association with the ID acquired from the sign recognition unit  13 . The prevention unit  15  also acquires from the storage device  25  the forward travel direction of the travel path currently being traveled or a travel path in the vicinity of the current position. Then, the prevention unit  15  detects whether or not there is a possibility of traveling in the wrong direction on the travel path in the future on the basis of the presence/absence of a sign and the display content of the sign that are indicated by the front recognition result, the presence/absence of a sign indicated by the rear recognition result and the display content of the sign that are indicated by the front recognition result, and the forward travel direction of the travel path currently being traveled or a travel path in the vicinity of the present position (Step S 610 ). 
     Upon having detected that there is a possibility of traveling in the wrong direction, the prevention unit  15  instructs the output unit  16  to output warning information by the process of Step S 607 . The output unit  16  outputs alarm information to the alarm  26  indicating there is a possibility of traveling in the wrong direction. As a result, the alarm  26  acquires the alarm information and emits an alarm sound or a voice alarm. The driver is able to recognize that there is a possibility of traveling in the wrong direction. 
     In the case of having detected that there is no possibility of traveling in the wrong direction, the prevention unit  15  determines whether to end by the process of Step S 609 . The prevention unit  15 , in the case of not ending the process, repeats the process from Step S 603 . The details of the process for preventing travel in the wrong direction are the same as the process described with reference to  FIG. 14  described above. 
       FIG. 16  is a diagram showing an example of the configuration of the travel management device  1 . 
       FIG. 17  is a diagram showing the flow of processing by the travel management device  1  shown in  FIG. 16 . 
     It is sufficient that that the travel management device  1  include at least a detection unit  14  and a prevention unit  15 . 
     The detection unit  14  detects that a moving body is traveling in the wrong direction on a travel path on the basis of at least one of a front recognition result indicating the display content displayed by a sign appearing in a captured image obtained by capturing an image to the front of the moving body, and a rear recognition result indicating the display content displayed by a sign appearing in a rear captured image obtained by capturing an image to the rear of the moving body (Step S 701 ). 
     The prevention unit  15  detects the possibility that the moving body will travel in the wrong direction on the travel path in the future on the basis of the front recognition result and the rear recognition result (Step S 701 ). 
     The above-mentioned travel management device  1  and drive recorder  2  have a computer system inside. The process of each process described above is stored in a computer-readable recording medium in the form of a program, with the process being performed by the computer reading and executing this program. Here, the computer-readable recording medium refers to a magnetic disk, a magneto-optical disk, a CD-ROM, a DVD-ROM, a semiconductor memory, or the like. Further, this computer program may be distributed to a computer via a communication line, and the computer receiving the distribution may execute the program. 
     The aforementioned program may be one for realizing some of the functions described above. 
     Further, a so-called differential file (differential program) may be used, which can realize the above-mentioned functions in combination with a program already recorded in the computer system. 
     This application is based upon and claims the benefit of priority from Japanese patent application No. 2019-108134, filed Jun. 10, 2019, the disclosure of which is incorporated herein in its entirety by reference. 
     INDUSTRIAL APPLICABILITY 
     The present invention may be applied to a travel management device, a travel management method, and a recording medium. 
     REFERENCE SYMBOLS 
       1 : Travel management device 
       2 : Drive recorder 
       3 : GPS sensor 
       11 : Control unit (control means) 
       12 : Acquisition unit (acquisition means) 
       13 : Sign recognition unit (sign recognition means) 
       14 : Detection unit (wrong-way travel detection unit, detection means) 
       15 : Prevention unit (wrong-way travel prevention unit, prevention means) 
       16 : Output unit (output means) 
       21 : Information acquisition device 
       22 : Communication device 
       231 : Front camera 
       232 : Rear camera 
       24 : Control device 
       241 : Captured image transmission unit (captured image transmission means) 
       242 : Sensing information transmission unit (sensing information transmission means)