Patent Publication Number: US-2019196494-A1

Title: Autonomous driving system and autonomous driving method

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application claims priority to Japanese Patent Application No. 2017-252151, filed on Dec. 27, 2017, which is hereby incorporated by reference herein in its entirety. 
     BACKGROUND 
     Technical Field 
     The present disclosure relates to an autonomous driving system and an autonomous driving method. 
     Description of the Related Art 
     There have been developed autonomous mobile objects that can run autonomously without driving operations by a human driver. For example. Patent Literature 1 describes transporting a user or goods to a destination by a first mobile object and a second mobile object that cooperates with the first mobile object when the first mobile object becomes inoperative while transporting the user or goods. Patent Literature 1 also discloses employing a mobile object for crime prevention activities in a certain region by creating an operation command that causes the mobile object to patrol that region in a time period (e.g. night time) in which the use of mobile objects is low. 
     CITATION LIST 
     Patent Literature 
     Patent Literature 1: Japanese Patent Application Laid-Open No. 2015-092320 
     SUMMARY 
     In the case of the crime prevention system using mobile objects described in Patent Literature 1, a mobile object receives instructions prepared according to the time, region, and/or other factors. However, such instructions are not instructions suited to actual circumstances at that time but predetermined instructions that have been prepared in advance. If the entire system can perform crime prevention activities utilizing information acquired by a plurality of mobile objects, efficient crime prevention activities can be realized. Thus, existing technologies pertaining to patrol of a certain region needs improving. 
     The present disclosure has been made under the above circumstances, and an object of the present disclosure is to enable crime prevention activities using mobile objects to be performed efficiently. 
     According to one aspect of the present disclosure, there is provided an autonomous driving system including a plurality of mobile objects that perform a patrol autonomously on the basis of an operation command, comprising an acquisitioner provided in each of said plurality of mobile objects and configured to acquire information about surroundings of said mobile object when said mobile object is moving, and a controller configured to determine a patrol plan for each of a plurality of regions on the basis of said information acquired by said acquisitioner of some mobile objects among said plurality of mobile objects that have moved in the same region, and create an operation command according to the patrol plan for each region determined by said controller. 
     The plurality of mobile objects acquire information about their surroundings by the acquisitioner while moving. The information includes information relating to prevention of crimes or information relating to the move of the mobile objects that enables an improvement in the effect of crime prevention activities if the mobile objects are moved on the basis of that information. Examples of such information include information about the number of people, information about illuminance, and information about road width. Such information may be, for example, information obtained by analyzing a captured image or information acquired through sensing by a sensor. A plurality of mobile objects acquire information in a plurality of regions. It is possible to know the present circumstances in the respective regions by collecting information thus acquired. Patrol plans suitable for the present circumstances in the respective regions are determined on the basis of the information acquired by the mobile objects in the respective regions. Thurs, patrol can be performed in a manner suitable for the present circumstances in the respective regions. In this way, crime prevention activities using mobile objects can be performed efficiently. The operation command creation part creates operation commands according to the patrol plans. The mobile objects are caused to patrol along designated patrol routes on the basis of the operation commands. The region mentioned above is defined as a zone to which the same patrol plan is to be applied. The regions do not necessarily agree with administrative divisions. For example, different roads may be set as different regions. Each mobile object may patrol one region or a plurality of regions. Patrolling based on the present circumstances in each region enables efficient crime prevent activities using mobile objects. 
     Said acquisitioner may acquire the number of people as said information, and said controller may determine said patrol plan in such a way as to make the frequency of patrol by said mobile object(s) higher in regions in which the number of people is small than in regions in which the number of people is large. 
     Regions in which there are a large number of people are advantageous from a crime prevention viewpoint only because of the largeness in the number of people, because the public eye potentially prevents crimes from being committed in such regions. Regions in which the number of people is small do not have such advantages. Determining the patrol plan in such a way as to make the frequency of patrol by mobile objects higher in regions in which the number of people is small can improve the effect of crime prevention activities. On the other hand, determining the patrol plan in such a way as to make the frequency of patrol by mobile objects lower in regions in which the number of people is large can prevent mobile objects from patrolling more frequently than necessary. Thus, crime prevention activities using mobile objects can be performed efficiently. The frequency of patrol may be defined as the number of mobile objects that pass through a specific point in each region per unit time. In the case where the sizes of regions are different, the number of people may be construed as the number of people per unit area. The frequency of patrol can be increased by increasing the times of patrol by the same mobile object or increasing the number of mobile objects employed for patrol. Increasing the number of mobile objects employed for patrol in a region makes the frequency of patrol by mobile objects in that region higher. 
     Thus, said acquisitioner may acquire the number of people as said information, and said controller may determine said patrol plan in such a way as to make the number of said mobile objects employed for patrol larger in regions in which the number of people is small than in regions in which the number of people is large. The patrol plan that makes the number of mobile objects employed for patrol larger in regions in which the number of people is small can improve the effect of crime prevention activities. 
     Said acquisitioner may acquire an illuminance as said information, and said controller may determine said patrol plan in such a way as to make the frequency of patrol by said mobile object higher in regions in which the illuminance is low than in regions in which the illuminance is high. 
     Regions in which the illuminance is high (i.e. bright regions) have advantages in terms of crime prevention over regions in which the illuminance is low (i.e. dark regions). Determining the patrol plan in such a way as to make the frequency of patrol by mobile objects higher in regions in which the illuminance is low can improve the effect of crime prevention activities. On the other hand, determining the patrol plan in such a way as to make the frequency of patrol by mobile objects lower in regions in which the illuminance is high can prevent mobile objects from patrolling more frequently than necessary. Thus, crime prevention activities using mobile objects can be performed efficiently. The illuminance may be the average illuminance in each region. 
     Said acquisitioner may acquire an illuminance as said information, and said controller may determine said patrol plan in such a way as to make the number of said mobile objects employed for patrol larger in regions in which the illuminance is low than in regions in which the illuminance is high. Determining the patrol plan in such a way as to make the number of mobile objects employed for patrol larger in regions in which the illuminance is low can improve the effect of crime prevention activities. 
     Said mobile object may be equipped with a light that illuminates the surroundings. In that case, said acquisitioner may acquire an illuminance as said information, and said controller may determine said patrol plan in such a way as to make the illumination by said light brighter in regions in which the illuminance is low than in regions in which the illuminance is high. 
     Determining the patrol plan in such a way as to make the illumination by the light brighter in regions .in which the illuminance is low can improve the effect of crime prevention activities. On the other hand, the illumination by the light can be prevented from becoming unnecessarily bright in regions in which the illuminance is high. Thus, crime prevention activities using mobile objects can be performed efficiently. Making the illumination by the light brighter includes increasing the luminous intensity of the light or increasing the number of lights that, are turned on. 
     Said plurality of mobile objects may include mobile objects having different sizes. In that case, said acquisitioner may acquire a road width as said information, and said controller may determine said patrol plan in such a way as to employ smaller mobile objects for patrol in regions in which the road width is small than in regions in which the road width is large. 
     Employing smaller mobile objects for patrol in regions in which the road width is small enables the patrol to be carried out smoothly. Moreover, this allows mobile objects to patrol roads with smaller road widths, improving the effect of crime prevention activities. The road width mentioned above may be the average road width in each region or the smallest road width in each region. 
     Said acquisitioner may comprise a camera that captures an image of the surroundings of said mobile object. Information about the surrounding of the mobile object can be acquired using an image captured by the camera. Moreover, it is possible to survey the surroundings of the mobile object using an image captured by the camera, enabling a further improvement in the effect of crime prevention activities. 
     According to another aspect of the present disclosure, there is provided an autonomous driving method for a plurality of mobile objects that move autonomously in a plurality of regions on the basis of an operation command, comprising the steps of acquiring by said plurality of mobile objects information about their respective surroundings, determining a patrol plan for each of the plurality of regions that is suitable for each region on the basis of said information acquired by some mobile objects among said plurality of mobile objects that have moved in the same region, and creating an operation command according to said patrol plan. 
     The present disclosure enables crime prevention activities using mobile objects to be performed efficiently. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a diagram showing the general configuration of an autonomous driving system. 
         FIG. 2  is a block diagram showing an exemplary configuration of the autonomous driving system shown in  FIG. 1 . 
         FIG. 3  is a diagram illustrating the operation of the autonomous driving system. 
         FIG. 4  is a block diagram showing an exemplary configuration of an autonomous driving system according to a second embodiment. 
         FIG. 5  is a block diagram showing an exemplary configuration of an autonomous driving system according to a third embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     In the following, specific embodiments of the present disclosure will be described with reference to the drawings The dimensions, materials, shapes, relative arrangements, and other features of the components that will be described in connection with the embodiments are not intended to limit the technical scope of the present disclosure only to them, unless otherwise stated. It should be understood that the features of the embodiments described below may be employed in any feasible combination. 
     First Embodiment 
     &lt;Outline of the System&gt; 
     The outline of an autonomous driving system  1  according to the first embodiment will be described with reference to  FIG. 1 .  FIG. 1  shows the general configuration of the autonomous driving system  1 . The autonomous driving system  1  according to the first embodiment includes a plurality of autonomous vehicles  100  that can run autonomously according to given operation commands and a center server  200  that issues the operation commands. The autonomous vehicles  100  will also be simply referred to as vehicles  100  hereinafter. The vehicles  100  and the center server  200  are connected with each other by a network N 1 . While  FIG. 1  shows an autonomous driving system  1  including three vehicles  100  for an illustrative purpose, the number of the vehicles  100  may be more than three. The vehicle  100  is one that patrols a road along a predetermined patrol route for the purpose of preventing crimes. 
     The center server  200  creates operation commands for the respective vehicles  100  and sends the operation commands to the respective vehicles  100 . Each vehicle  100  that has received the operation command patrols a road along a predetermined patrol route based on the operation command. The respective patrol routes of the vehicles  100  may be different from each other. When patrolling the road along the predetermined patrol route, each vehicle  100  acquires information about the road and/or information about the surroundings of the road. The information acquired by the vehicle  100  in this way will be hereinafter referred to as “surroundings information”. The surroundings information includes information relevant to passage of the vehicle  100 , which includes information about the road width, information about the brightness of lighting in the night, and information about the number of walkers, and information relevant to the prevention of crimes. The surroundings information acquired by each vehicle  100  is sent to the center server  200 . After receiving surroundings information in certain regions, the center server  200  creates operation commands suited to the respective regions and sends them to the respective vehicles  100 . For example, for a region in which the road width is small, operation commands are created in such a way as to employ small-sized vehicle(s) for patrol in that region. For a region in which the number of walkers (or people) is small, operation commands are created in such a way as to make the number of vehicles  100  patrolling that region greater than that in other regions or to make the frequency of patrol in that region higher than that in other regions. For a region in which lightings in the night are few, operation commands are created in such a way as to make the number of vehicles  100  patrolling that region greater than that in other regions, to make the frequency of patrol in that region higher than that in other regions, or to cause vehicles  100  to illuminate their surroundings by their light in that region. Each autonomous vehicle  100  having received an operation command creates an operation plan according to the operation command and performs a patrol operation according to that operation plan. In this embodiment, we will describe a case where the number of people is acquired as the surroundings information and vehicles  100  are caused to perform a patrol operation on the basis of that number of people. 
     &lt;System Configuration&gt; 
     Elements of the system will be described specifically.  FIG. 2  is a block diagram showing an exemplary configuration of the autonomous driving system  1  shown in  FIG. 1 . While  FIG. 2  shows one vehicle  100  for an illustrative purpose, the system actually includes a plurality of vehicles  100 . 
     The vehicle  100  travels according to an operation command received from the center server  200 . Specifically, the vehicle  100  creates a travel route on the basis of an operation command received through wireless communication and travels on the road in an appropriate manner while sensing its environment. The vehicle  100  includes a sensor  101 , a positional information acquisition unit  102 , a control unit  103 , a driving unit  104 , a communication unit  105 , a camera  106 , and a storage unit  107 . The vehicle  100  operates by electrical power supplied by a battery, which is not shown in the drawings. The vehicle  100  corresponds to the mobile object according to the present disclosure. 
     The sensor  101  is means for sensing the environment of the vehicle, which typically includes a stereo camera, a laser scanner, a LIDAR, a radar, or the like. Data acquired by the sensor  101  is sent to the control unit  103 . The positional information acquisition unit  102  is means for acquiring the current position of the vehicle, which typically includes a GPS receiver. Information acquired by the positional information acquisition unit  102  is sent to the control unit  103 . 
     The control unit  103  is a computer that controls the vehicle  100  on the basis of the information acquired through the sensor  101 . The control unit  103  is, for example, a microcomputer. The control unit  103  includes as functional modules an operation plan creation part  1031 , an environment perceiving part  1032 , a travel control part  1033 , and an information acquisition part  1034 . These functional modules may be implemented by executing programs stored in storage means, such as a read only memory (ROM), by a central processing unit (CPU), neither of which is shown in the drawings. 
     The operation plan creation part  1031  receives an operation command from the center server  200  and creates an operation plan of the vehicle. In this embodiment, the operation plan is data that specifies a route along which the vehicle  100  is to travel and task(s) to be done by the vehicle  100  in a part or the entirety of that route. Examples of data included in the operation plan are as follows. 
     (1) Data that Specifies a Route Along Which the Vehicle is to Travel By a Set of Road Links 
     The route along which the vehicle is to travel may be created automatically according to an operation command with reference to map data stored in storage means. Alternatively, the route may be created using an external service. Still alternatively, the route along which the vehicle is to travel may be provided by the server apparatus. In other words, the route of travel may be specified by the operation command. Still alternatively, the route along which the vehicle is to travel may be selected from a plurality of routes stored in storage means (not shown) by the operation plan creation part  1031  according to an operation command. 
     (2) Data Specifying Task(S) to be Done By the Vehicle 
     Examples of the tasks to be done by the vehicle include, but are not limited to, acquiring surroundings information. The operation plan created by the operation plan creation part  1031  is sent to the travel control part  1033 , which will be described later. 
     The environment perceiving part  1032  perceives the environment around the vehicle using the data acquired by the sensor  101 . What is perceived includes, but is not limited to, the number and the position of lanes, the number and the position of other vehicles present around the vehicle, the number and the position of obstacles (e.g. pedestrians, bicycles, structures, and buildings) present around the vehicle, the structure of the road, and road signs. What is perceived may include anything that is useful for autonomous traveling. The environment perceiving part  1032  may track perceived object(s). For example, the environment perceiving part  1032  may calculate the relative speed of the object from the difference between the coordinates of the object determined in a previous step and the current coordinates of the object. The data relating to the environment acquired by the environment perceiving part  1032  is sent to the travel control part  1033 , which will be described below. This data will be hereinafter referred to as “environment data”. 
     The travel control part  1033  controls the traveling of the vehicle on the basis of the operation plan created by the operation plan creation part  1031 , the environment data acquired by the environment perceiving part  1032 , and the positional information of the vehicle acquired by the positional information acquisition unit  102 . For example, the travel control part  1033  causes the vehicle to travel along a certain route in such a way that obstacles will not enter a specific safety zone around the vehicle. A known autonomous driving method may be employed to drive the vehicle. The travel control part  1033  sends the positional information of the vehicle acquired by the positional information acquisition unit  102  to the center server  200  through the communication unit  105 . In consequence, the center server  200  knows the current position of the vehicles  100 . 
     The information acquisition part  1034  acquires surroundings information. The information acquisition part  1034  according to this embodiment acquires the surroundings information by counting the number of people by analysis of image(s) captured by the camera  106 . The image analysis may be carried out by a known method. While in this embodiment, the number of people is counted using image(s) captured by the camera  106 , the number of people may be counted by the sensor  101 . The information acquisition part  1034  stores the counted number of people in the storage unit  107  in association with the positional information acquired by the positional information acquisition unit  102  or sends it to the center server  200 . The camera  106  functions as the acquisitioner according to the present disclosure. 
     The driving unit  104  is means for driving the vehicle  100  according to a command created by the travel control part  1033 . The driving unit  104  includes, for example, a motor and inverter for driving wheels, a brake, and a steering system. The communication unit  105  serves as communication means for connecting the vehicle  100  to the network HI. In this embodiment, the communication unit  105  can communicate with other devices (e.g. the center server  200 ) via the network using a mobile communication service based on e.g. 3G or LTE. 
     The camera  106  is provided on the body of the vehicle  100  to capture images of the surroundings of the vehicle  100 . The camera  106  captures images using an image sensor such as a charge-coupled device (CCD) image sensor or a complementary metal oxide semiconductor (CMOS) image sensor Images captured by the camera  106  may be either still images or moving images. The vehicle  100  may have a plurality of cameras  106  provided on different portions of the vehicle body. For example, cameras may be provided on the front, rear, and right and left sides of the vehicle body. The storage unit  107  is means for storing information, which includes a storage medium such as a RAM, a magnetic disc, or a flash memory. Information stored in the storage unit  107  includes, for example, map data and surroundings information acquired by the information acquisition part  1034 . 
     Now, the center server  200  will be described. The center server  200  is an apparatus configured to manage the position of the running vehicles  100  and to send operation commands to the vehicles  100 . The center server  200  creates operation commands for vehicles  100  on the basis of surroundings information sent from the vehicles  100  and sends the operation commands to the vehicles  100 . 
     The center server  200  includes a communication unit  201 , a control unit (controller)  202 , and a storage unit  203 . The communication unit  201  is a communication interface, similar to the above-described communication unit  105  of the vehicle  100 , for communication with the vehicles  100  via the network N 1 . The control unit  202  is means for performing overall control of the center server  200 . The control unit  202  is constituted by, for example, a CPU. The control unit  202  includes as functional modules a positional information management part  2021 , an operation command creation part  2022 , a surroundings information collection part  2023 , and a plan determination part  2024 . These functional modules may be implemented by executing programs stored in storage means, such as a read only memory (ROM), by the CPU, neither of which is shown in the drawings. 
     The positional information management part  2021  collects and manages positional information sent from the vehicles  100  under its management. Specifically, the positional information management part  2021  receives positional information from the vehicles  100  at predetermined intervals and stores it in association with the date and time in the storage unit  203 , which will be described later. The operation command creation part  2022  creates operation commands for the vehicles  100 . Each operation command includes data specifying a route along which a vehicle  100  is to travel and data specifying task(s) to be done by the vehicle  100 . The surroundings information collection part  2023  collects surroundings information sent from vehicles  100  and stores the collected information in the storage unit  203 . The surroundings information stored in the storage unit  203  by the surroundings information collection part  2023  is sorted by regions using the positional information of the vehicles  100 . In this embodiment, specifically, the number of people in each of the regions is stored in the storage unit  203 . 
     The plan determination part  2024  determines a plan of operation commands for each of the regions on the basis of the surroundings information collected by the surroundings information collection part  2023 . This plan will also be referred to as “patrol plan” hereinafter. The patrol plan is determined in such a way that the frequency of patrol by vehicles  100  is made higher in regions in which the number of people is relatively small than in regions in which the number of people is relatively large. For example, the number of patrolling vehicles  100  may be made larger in regions in which the number of people is relatively small than in regions in which the number of people is relatively large. Each region is defined in advance as a zone to which the same patrol plan is applied. The number of people may be either the raw value counted by the vehicles  100  or a value calculated as the number of people per unit area in each region. The patrol plan thus determined is sent to the operation command creation part  2022 , and the operation command creation part  2022  creates operation commands according to the patrol plan. The operation command creation part  2022  creates operation commands by executing a certain program for creating operation commands according to the patrol plan. The storage unit  203  is means for storing information, which is constituted by a storage medium such as a RAM, a magnetic disc, or a flash memory. 
     &lt;Operation of the System&gt; 
     The operation of the autonomous driving system  1  according to the first embodiment will be described in the following with reference to  FIG. 3 . In the process shown in  FIG. 3 , the operation command creation part  2022  of the center server  200  creates operation commands for the respective vehicles  100  (processing of S 11 ). In the first round of the operation, operation commands are created in such a way as to cause the vehicles  100  to travel along respective designated patrol routes and captures images by the camera  106  so as to enable the information acquisition part  1034  to acquire information. Such operation commands are sent to the respective vehicles  100  through the communication unit  201  of the center server  200  (processing of S 12 ). The operation plan creation part  1031  of each vehicle  100  that has received the operation command creates an operation plan based on the patrol route specified in the operation command (processing of S 13 ). Then, the travel control part  1033  performs travel control according to this operation plan (processing of S 14 ). Specifically, the travel control part  1033  controls the driving unit  104  to cause the vehicle  100  to travel along the designated patrol route. Alternatively, the operation plan may be created by the center server  200  and sent to the vehicle  100  from the center server  200 . While the vehicle  100  travels along the designated patrol route, the information acquisition part  1034  acquires surroundings information using the camera  106  (processing of S 15 ). The information acquisition part  1034  stores the surroundings information thus acquired in the storage unit  107  in association with the positional information acquired by the positional information acquisition unit  102 . The information acquisition part  1034  sends the surroundings information to the center server  200  through the communication unit  105  at an appropriate time (processing of S 16 ). 
     After the center server  200  receives the surroundings information from the vehicles  100 , the surroundings information collection part  2023  of the center server  200  collects surroundings information from the vehicles  100  that have traveled the same region with reference to the positional information of the vehicles  100  and stores the surroundings information in the storage unit  203  on a region-by-region basis (in other words, in such a way as to sort the surrounding information by regions) (processing of S 17 ). After a sufficient amount of surroundings information that is large enough to determine a patrol plan is collected, the plan determination part  2024  accesses the data stored in the storage unit  203  on a region-by-region basis to determine patrol plans according to the surroundings information of the respective regions (processing of S 18 ). For example, the patrol plans for the respective regions are determined in such a way as to make the frequency of patrol by vehicles  100  higher or to make the number of patrolling vehicles  100  larger in regions in which the number of people is relatively small than in regions in which the number of people is relatively large. 
     The operation command creation part  2022  creates operation commands for the respective vehicles  100  according to the patrol plan sent from the plan determination part  2024  (processing of  319 ). For example, the operation command creation part  2022  may create such operation commands for some vehicles  100  that cause them to move from a region in which the number of people is large to a region in which the number of people is small. The operation commands are sent to the respective vehicles  100  through the communication unit  201  of the center server  200  (processing of S 20 ). The aforementioned operation commands are created in such a way as to cause the information acquisition part  1034  to acquire information by image-capturing by the camera  106 . The processing of S 21  to S 23  is the same as the processing of S 13  to S 15  described above. The processing of S 13  to S 20  is executed repeatedly at predetermined intervals. Thus, in every round of the processing, a patrol plan suitable for the circumstances in each region at that time can be created, and patrol by the vehicles  100  can be performed according to that plan. 
     In the system according to the first embodiment, images captured by the camera  106  of the vehicle  100  may be used for the purpose of preventing crimes. For example, the information acquisition part  1034  may acquire an image of a person using the camera  106  and send the image to the center server  200  through the communication unit  105 . Then, the control unit  202  of the center server  200  may judge whether or not the person appearing in the image is a person without problems from a crime prevention viewpoint. This judgement may be conducted by comparing the person appearing in the image with data of persons having a problem (e.g. wanted criminals) from a crime prevention viewpoint stored in the storage unit  203 . This comparison may be carried out using known technologies. Detecting a person having a problem from a crime prevention viewpoint in this way helps prevention of crimes. 
     In this embodiment and the embodiments that will be described in the following, some or all of the functions of the center server  200  may be provided by a vehicle  100 , and some of the functions of a vehicle  100  may be provided by the center server  200 . For example, the vehicles  100  may include a vehicle that creates operation commands, a vehicle that collects surroundings information from other vehicles, and/or a vehicle that determines a patrol plan. 
     As above, the system according to this embodiment causes vehicles  100  to operate according to the number of people in each region. Thus, crime prevention activities using mobile objects can be performed efficiently. 
     Second Embodiment 
     In the system according to the second embodiment, the vehicles  100  are equipped with a lighting unit (light)  108 , and a patrol plan is determined in such a way as to cause the lighting unit  108  of the vehicles  100  to illuminate surroundings more brightly in regions that are dark at night.  FIG. 4  is a block diagram showing an exemplary configuration of an autonomous driving system  1  according to the second embodiment. While  FIG. 4  shows only one vehicle  100  for an illustrative purpose, the autonomous driving system  1  according to the second embodiment actually includes a plurality of vehicles  100 . In the following, features of the autonomous driving system  1  that are different from the system according to the first embodiment will be mainly described. The vehicle  100  is equipped with the lighting unit  108  that illuminates the surroundings of the vehicle  100  and an illuminance sensor  109  that measures the outside illuminance. The lighting unit  108  is typically a lighting device including an illumination lamp. However, the lighting unit  108  is not limited to this, but anything that can illuminate the surroundings of the vehicle  100  may be employed as the lighting unit  108 . For example, a liquid crystal display, an organic electro-luminescence display, or a plasma display may be employed as the lighting unit  108 . The information acquisition part  1034  according to the second embodiment acquires the surroundings information by measuring the illuminance using the illuminance sensor  109 . While the illuminance outside the vehicle  100  is measured by the illuminance sensor  109  in the second embodiment, the outside illuminance may be determined by analyzing an image captured by the camera  106 . The surroundings information thus acquired is sent to the center server  200  with positional information. The camera  106  or the illuminance sensor  109  functions as the aquisitioner according to the present disclosure. 
     In the system according to the second embodiment, the surroundings information collection part  2023  collects illuminance data in each region and stores the illuminance data in the storage unit  203  on a region-by-region basis using the positional information of the vehicles  100 . The illuminance may be the average illuminance in each region. The plan determination part  2024  determines a patrol plan for each region on the basis of the illuminance in each region collected by the surroundings information collection part  2023 . The patrol plan may be determined, for example, in such a way as to make the luminous intensity of the lighting unit  108  higher in regions in which the illuminance is relatively low than in regions in which the illuminance is relatively high or to turn on the lighting unit  108  in regions in which the illuminance is lower than a threshold and not turn on in regions in which the illuminance is higher than the threshold. In cases where the vehicle  100  is equipped with a plurality of lighting units  108 , the patrol plan may be determined in such a way as to change the number of lighting units  108  to be turned on according to the illuminance in the regions. The patrol plan thus determined is sent to the operation command creation part  2022 , and the operation command creation part  2022  creates operation commands according to the patrol plan. The operation command creation part  2022  creates operation commands by executing a certain program for creating operation commands according to the patrol plan. 
     The operation of the autonomous driving system  1  according to the second embodiment is similar to the operation of the system according to the first embodiment, shown in  FIG. 3 . Specifically, in the processing of S 15  in  FIG. 3 , the information acquisition part  1034  acquires the surroundings information (namely, information about the surroundings of the vehicle  100 ) using the illuminance sensor  109 , while the vehicle  100  is travelling along a designated patrol route. Each vehicle  100  sends the surroundings information to the center server  200 . Then in the processing of S 17 , the illuminance data is stored in the storage unit  203  on a region-by-region basis. In the processing of S 18 , the plan determination part  2024  determines a patrol plan for each of the regions, for example, in such a way as to make the luminous intensity of the lighting unit  108  higher in regions in which the illuminance is relatively low than in regions in which the illuminance is relatively high. 
     In the above-described case, the patrol plan is determined in such a way as to make the luminous intensity of the lighting unit  108  high in the regions in which the detected illuminance is low. Alternatively, the patrol plan may be determined in such a way as to make the frequency of patrol by vehicles  100  higher in regions in which the illuminance is relatively low than in regions in which the illuminance is relatively high. In that case, the number of vehicles  100  employed for patrol may be made larger in regions in which the illuminance is relatively low than in regions in which the illuminance is relatively high. As above, in regions in which the illuminance is low, the frequency of patrol by vehicles  100  or the number of vehicles  100  may be increased to improve crime prevention activities. Thus, regions in which the number of people is small and regions in which the number of people is large mentioned in the first embodiment are replaced respectively by regions in which the illuminance is low and regions in which the illuminance is high. 
     As above, the system according to this embodiment causes vehicles  100  to operate according to the illuminance in each region. Thus, crime prevention activities using mobile objects can be performed efficiently. 
     Third Embodiment 
     The autonomous driving system  1  according to the third embodiment includes vehicles  100  having different sizes, and determines patrol plans in such a way that smaller vehicles  100  are employed for patrol in regions in which the road width is relatively small than in regions in which the road width is relatively large. The vehicles  100  in the system according to the third embodiment include at least two types of vehicles  100  that differ in the width and/or length. Vehicles  100  having a shorter width and/or length may be employed for roads with shorter widths. The road width may be measured by the sensor  101  shown in  FIG. 2 or 4  or determined by analyzing image(s) captured by the camera  106 . The information acquisition part  1034  sends the road width data to the center server  200  through the communication unit  105 . Data about the size of each vehicle  100  or data about the road width corresponding to each vehicle  100  are stored in the storage unit  203  of the center server  200 . The sensor  101  or the camera  106  functions as the acquisitioner according to the present disclosure. 
     According to the third embodiment, the surroundings information collection part  2023  collects road width data in each region and stores the road width data in the storage unit  203  on a region-by-region basis using the positional information of the vehicles  100 . The average road width in each region may be calculated, and the average value may be stored in the storage unit  203  on a region-by-region basis. The plan determination part  2024  determines a patrol plan for each region on the basis of the road width in each region collected by the surroundings information collection part  2023 . For example, smaller vehicles  100  are employed in regions in which the road width is relatively small than in regions in which the road width is relatively large. The patrol plan thus determined is sent to the operation command creation part  2022 , and the operation command creation part  2022  creates operation commands according to the patrol plan. The operation command creation part  2022  creates operation commands by executing a certain program for creating operation commands according to the patrol plan. 
       FIG. 5  is a diagram showing the general configuration of the autonomous driving system  1  including small-sized vehicles  100 A and large-sized vehicles  100 B. The length, width, and height of the small-sized vehicle  100 A are smaller than these of the large-sized vehicle  100 B. In cases where the system includes two types of vehicles  100  having different sizes as above, small-sized vehicles  100 A may be employed for patrol in regions in which the road width is smaller than a threshold, and large-sized vehicles  100 B may be employed for patrol in regions in which the road width is larger than the threshold. The threshold is set according to the width of roads that the large-sized vehicles  100 B can run. 
     The operation of the autonomous driving system  1  according to the third embodiment is similar to the operation of the system according to the first embodiment shown in  FIG. 3 . Specifically, in the processing of S 15  in  FIG. 3 , the information acquisition part  1034  acquires the surroundings information (namely, information about the surroundings of the vehicle  100 ) using the sensor  101  or the camera  106 , while the vehicle  100  is travelling along a designated patrol route. Each vehicle  100  sends the surroundings information to the center server  200 . Then in the processing of S 17 , the road width data is stored in the storage unit  203  on a region-by-region basis. In the processing of S 18 , the plan determination part  2024  determines a patrol plan for each of the regions, for example, in such a way as to employ smaller vehicles  100  in regions in which the road width is small than in regions in which the road width is large. In the processing of S 19 , the operation command creation part  2022  creates operation commands for vehicles  100  in such a way that vehicles  100  having suitable sizes are dispatched to respective regions. 
     As above, even in regions in which the road width is small, patrol can be performed smoothly by employing vehicles  100  having a smaller size. Thus, the system according to the third embodiment can also perform crime prevention activities using mobile objects efficiently.