Road surface evaluation device and road surface evaluation method

Abstract

According to the present invention, road performance is estimated by utilizing outside temperature measurement information obtained by an outside temperature measurement sensor 142 provided in many vehicles 60.　A road surface evaluation device 30 comprises: a travel information acquisition unit 311 that acquires travel information including location information of a plurality of vehicles 60 which are traveling, time information, and outside temperature information; a weather prediction information acquisition unit 313 that acquires second temperature information, which is information on predicted temperature that varies with time, as weather prediction information for each predetermined area; an evaluation unit 314 that, for each road unit of road information, calculates differential temperature information between the first temperature information and the second temperature information for each piece of time information, and estimates road surface performance information on the basis of the differential temperature information; and an output unit 315 that outputs the road surface performance information in association with the road information.

Description

Road surface evaluation device and road surface evaluation method

[0001] The present invention relates to a road surface evaluation device and a road surface evaluation method for evaluating the performance of a road surface.

[0002] In the summer, rising temperatures due to radiant heat from roads are a problem. Understanding the performance and condition of road surfaces for short sections is essential for road repair measures. One known effective road repair measure is heat-shielding pavement construction, which blocks infrared rays that can lead to road surface temperature information. However, it is not easy to measure the road surface temperature of each road and determine which roads have high radiant heat temperatures. Therefore, prioritizing roads for heat-shielding pavement construction, for example, is difficult. In response to this issue, for example, Patent Literature 1 discloses a technology that functions as a comfortable walking route search server, searching for a walking route with a relatively low temperature based on real-time temperature data for each of multiple routes from a starting point to a destination and proposing it as a recommended route. Patent Literature 2 also discloses a technology that functions as a route search system, collecting temperature data from multiple temperature sensors measuring road surface temperature at multiple measurement positions spaced apart from each other, calculating road surface temperature information along a potential walking route from a starting point to a destination input on a user terminal, and transmitting the information to the user terminal.

[0003] Patent No. 4992099 JP 2020-134408 A

[0004] However, both of the technologies in Patent Documents 1 and 2 are intended to assist in the selection of a relatively cool route by calculating the temperature of the route, but do not provide information on the performance of the road surface itself. In the comfortable walking route search system described in Patent Document 1, outside air temperature data from a single adjacent temperature sensor is assigned as temperature data at nodes of walking route sections. In other words, the system described in Patent Document 1 uses outside air temperature data from a single temperature sensor to evaluate the outside air temperature of a walking route section with a substantial distance. Therefore, the outside air temperature may be far removed from the perceived temperature, and the system does not necessarily provide a comfortable walking route. On the other hand, Patent Document 2 collects temperature data from multiple temperature sensors that measure road surface temperature at multiple measurement positions. However, it is difficult to set up multiple temperature sensors to measure road surface temperature for all roads.

[0005] The present invention aims to provide a road surface evaluation device and a road surface evaluation method that can estimate road surface performance information based on the magnitude of the difference between a first temperature, which is the outside air temperature measured by an outside air temperature sensor equipped in each of a plurality of vehicles, and a second temperature, which is the predicted temperature (or actual measured temperature) based on weather forecast information. This makes it possible to estimate the performance of a road surface with a simple configuration that utilizes measurement information from outside air temperature measurement sensors equipped in many vehicles. Furthermore, by providing this information to end users and alerting them, it is possible to avoid the risks of heatstroke, burns, etc. caused by radiant heat in the summer.

[0006] (1) A road surface evaluation device according to one aspect of the present invention (for example, the "road surface evaluation device 30" described below) includes: a driving information acquisition unit (for example, the "driving information acquisition unit 311" described below) that acquires driving information for a plurality of vehicles in motion, including position information, time information, and first temperature information from an outside air temperature measurement sensor (for example, the "outside air temperature measurement sensor 142" described below); a map information acquisition unit (for example, the "map information acquisition unit 312" described below) that acquires map information including road information; a weather forecast information acquisition unit (for example, the "weather forecast information acquisition unit 313" described below) that acquires second temperature information, which is information on changes in predicted temperature with time, as weather forecast information for each predetermined area of ​​the map information; and an evaluation unit (for example, the "evaluation unit 314" described below) that calculates differential temperature information between the first temperature information and the second temperature information for each road unit of the road information for each of the time information, and estimates road surface performance information based on the differential temperature information; an output unit (for example, "output unit 315" described later) that outputs the road surface performance information in association with the road information in the map information.

[0007] According to (1) above, it is possible to estimate road performance with a simple configuration that utilizes measurement information of the outside air temperature of a vehicle by an outside air temperature measurement sensor that is equipped in many vehicles.

[0008] (2) In the road surface evaluation device described in (1) above (for example, the “road surface evaluation device 30” described below), the evaluation unit may calculate the differential temperature information for each piece of time information that includes the time at which the second temperature information records the highest temperature on the day.

[0009] According to the above (2), it is possible to estimate road performance with higher accuracy.

[0010] (3) In the road surface evaluation device described in (1) above (for example, the “road surface evaluation device 30” described below), the evaluation unit may calculate the differential temperature information as the second temperature information being the average value of the daytime air temperature for each hour of the day.

[0011] According to the above (3), it is possible to estimate road performance with higher accuracy.

[0012] (4) In the road surface evaluation device described in (1) above (for example, the “road surface evaluation device 30” described later), the map information acquisition unit may include road link information in the road information, the evaluation unit may treat the road unit of the road information as a road link, and the output unit may output the road surface performance information in association with the road link.

[0013] According to (4) above, it is possible to estimate road performance with higher accuracy.

[0014] (5) In the road surface evaluation device described in (1) above (for example, the “road surface evaluation device 30” described later), the driving information acquisition unit may acquire information on the ground height of the outside air temperature measurement sensor of the vehicle as the driving information, and the evaluation unit may estimate road surface performance information using first temperature information measured by a vehicle whose outside air temperature measurement sensor is mounted at a ground height equal to or less than a predetermined value for each vehicle type information.

[0015] According to (5) above, the lower the position of the outside air temperature measuring sensor, the greater the influence of radiant heat, and therefore the higher the displayed temperature, making it possible to estimate road performance with greater accuracy.

[0016] (6) In the road surface evaluation device described in (1) or (2) above (for example, the “road surface evaluation device 30” described later), the road surface performance information may be evaluated as having lower performance the smaller the difference between the differential temperature information when the time information is daytime and the differential temperature information when the time information is nighttime.

[0017] According to (6) above, by determining that roads on which the temperature does not cool down easily at night have low road surface performance, it becomes possible to estimate road performance with higher accuracy.

[0018] (7) A road surface evaluation method according to one aspect of the present invention is a road surface evaluation method performed by one or more computers, and includes: a driving information acquisition step of acquiring driving information for a plurality of vehicles in motion, including position information, time information, and first temperature information from an outside air temperature measurement sensor; a map information acquisition step of acquiring map information including road information; a weather forecast information acquisition step of acquiring second temperature information, which is information on changes in predicted temperature over time, as weather forecast information for each specified area of ​​the map information; an evaluation step of calculating differential temperature information between the first temperature information and the second temperature information for each road unit of the road information for each of the time information, and estimating road surface performance information based on the differential temperature information; and an output step of outputting the road surface performance information in association with the road information of the map information.

[0019] According to the method (5) above, the same effects as those of the road surface evaluation device (1) above can be achieved.

[0020] According to the present invention, road performance can be estimated using a simple configuration that utilizes measurement information on the outside air temperature of a vehicle from outside air temperature measurement sensors installed in many vehicles. For example, by estimating which road units have high radiant heat temperatures in the summer, it becomes easy to consider the priority of "heat-shielding pavement construction" for road surfaces that are effective in mitigating the heat island effect. Furthermore, by providing users with the latest temperature information (second temperature information) for each specified area including a road unit (e.g., a road link) and the latest road surface temperature information (first temperature information) for that road unit, it is possible to warn them to avoid risks such as heatstroke and burns caused by radiant heat in the summer. Therefore, this contributes to improving the environment and lifestyles and is suitable for achieving the Sustainable Development Goals (SDGs).

[0021] FIG. 1 is a block diagram showing the basic configuration of the entire road surface evaluation system in an embodiment of the present invention. FIG. 2 is a block diagram showing the configuration of an on-vehicle device in an embodiment of the present invention. FIG. 3 is a block diagram showing the overall configuration of a road surface evaluation device 30 in an embodiment of the present invention. FIG. 4 is a diagram showing an example of road link information as road information to be evaluated in an embodiment of the present invention. FIG. 5 is a diagram showing a comparison between first temperature information and second temperature information in a road link in an embodiment of the present invention. FIG. 6 is a diagram showing a comparison in which daytime differential temperature information is compared with nighttime differential temperature information, and road performance is estimated according to the difference between the daytime differential temperature information and the nighttime differential temperature information in an embodiment of the present invention. FIG. 7 is a flowchart showing the basic operation of evaluation processing in an embodiment of the present invention.

[0022] The road surface evaluation system 1 according to the embodiment of the present invention will be described below. FIG.

[0023] As shown in Fig. 1, the road surface evaluation system 1 includes a vehicle 60, an on-board device 10 provided in the vehicle 60, and a road surface evaluation device 30. These devices are connected to each other so that they can communicate with each other via a communication network 50. Note that the figure also shows information transmitted and received by these devices, but this information is merely an example. In this embodiment, information other than that shown in the figure may be transmitted and received.

[0024] The road surface evaluation device 30 acquires, via the communication network 50, from a plurality of traveling vehicles 60 (specifically, the on-board devices 10 equipped in the vehicles 60), for example, position information of the vehicles 60 measured by a GPS sensor 141, the outside air temperature of the vehicles 60 measured by an outside air temperature measurement sensor 142 (hereinafter referred to as "first temperature information"), and travel information 120 including time information when the position information and the first temperature information were measured. Note that the measurement of the position information and the measurement of the first temperature information are performed at a predetermined period. Here, the first temperature information is the temperature at a height above ground level where the outside air temperature measurement sensor 142 is mounted from the road surface, and therefore can be regarded as the road surface temperature of the road surface. In this way, for example, for each road link, road surface temperature information of the road link can be collected at a predetermined period based on the travel information 120 of the plurality of vehicles 60 that have traveled on the road link. Note that, as will be described later, the road surface evaluation device 30 may evaluate the road surface temperature information of the road link at a time interval longer than the predetermined period. For example, if the predetermined time interval is 1 minute, the time in the 12 o'clock range can be set in 60 stages, including 12:00-01, 12:01-02, ... 12:58-59, and 12:59-13:00. Furthermore, if the predetermined time interval is 10 minutes, the time in the 12 o'clock range can be set in six stages, including 12:00-10, 12:10-20, 12:20-30, 12:30-40, 12:40-50, and 12:50-13:00. Furthermore, if the predetermined time interval is 30 minutes, the time in the 12 o'clock range can be set in two stages, and if it is 60 minutes, the time in the 12 o'clock range can be set. The predetermined time interval can be set arbitrarily by the user, but the predetermined time interval cannot be smaller than the periodic interval described above. Hereinafter, the times mentioned in this embodiment are set at predetermined time intervals. For example, if the predetermined time interval is 1 minute, 12:00 means (12:00≦12:XX<12:01), and if the predetermined time interval is 10 minutes, 12:00 means (12:00≦12:XX<12:10).

[0025] The road surface evaluation device 30 can calculate the magnitude of the difference between the first temperature information (considered to be the road surface temperature) and the second temperature information (air temperature) for the same road link for each hour of the day by obtaining temperature information (referred to as the "second temperature information") for a predetermined area including the road link from, for example, a weather forecast site. If the difference is small, it is considered that the road surface of the road suppresses the first temperature information (considered to be the road surface temperature) by highly reflecting infrared rays, which lead to an increase in the road surface temperature. Conversely, if the difference is large, it is considered that the road surface of the road absorbs heat without highly reflecting infrared rays. In this way, by calculating the magnitude of the difference between the first temperature information (considered to be the road surface temperature) and the second temperature information (air temperature) for each hour of the day for each of the multiple roads located within the predetermined area, it is possible to estimate the performance of the multiple roads. This concludes the overview of the road surface evaluation system 1. Next, the devices that make up the road surface evaluation system 1 will be described.

[0026] 2 shows the overall configuration of the in-vehicle device 10. As shown in FIG. 2, the in-vehicle device 10 includes a control unit 11, a storage unit 12, a communication unit 13, a sensor unit 14, a display unit 15, and an input unit 16.

[0027] The control unit 11 is configured with a CPU (Central Processing Unit), a microprocessor, etc. The CPU executes a program read from the ROM or the storage unit 12 and exchanges signals with, for example, the communication unit 13, the sensor unit 14, the display unit 15, and the input unit 16. In this manner, the processing in the first embodiment is realized by the cooperation of hardware and software (programs). Note that the in-vehicle device 10 may be configured with an in-vehicle ECU (Electronic Control Unit) device well known to those skilled in the art. The control unit 11 includes a driving information transmission unit 111, which transmits driving information 120 of the vehicle 60 to the road surface evaluation device 30, for example, periodically, from when the ignition switch of the vehicle 60 is turned on until the ignition switch is turned off.

[0028] The travel information 120 of the vehicle 60 includes identification information of the vehicle 60, location information of the vehicle 60, first temperature information (outside temperature information of the vehicle 60 at the location) measured by an outside temperature measurement sensor 142 (provided in the sensor unit 14) of the vehicle 60, and time information when the location information and the first temperature information were measured or measured. The travel information 120 may also include vehicle model information of the vehicle 60. The identification information of the vehicle 60 is information uniquely assigned to identify the vehicle 60. For example, a serial number uniquely assigned to the in-vehicle device 10, a telephone number assigned to a subscriber identity module (SIM) inserted into the communication unit 13 so that the communication unit 13 can connect to a communication network 50 such as a mobile phone network, a vehicle identification number (VIN) uniquely assigned to the vehicle 60, or a license plate number may be used as the identification information of the vehicle 60. The location information is measured, for example, by a global positioning system (GPS) sensor 141 or the like provided in the sensor unit 14. The measurement of the position information or the first temperature information may be performed at a predetermined cycle. As will be described later, the vehicle type information is information that the road surface evaluation device 30 uses to acquire information about the ground clearance of the outside air temperature measurement sensor 142 provided on the vehicle 60. Therefore, the information about the ground clearance of the outside air temperature measurement sensor 142 itself may be included in the travel information 120 instead of the vehicle type information.

[0029] The memory unit 12 is composed of semiconductor memory, etc., and stores various programs such as control programs called firmware or operating systems, programs for transmitting driving information 120 of the vehicle 60 to the road surface evaluation device 30, a buffer memory area for temporarily storing driving information 120 of the vehicle 60 that is created at a predetermined interval and transmitted to the road surface evaluation device 30, and various other information such as map information.

[0030] The communication unit 13 has a DSP (Digital Signal Processor) and the like, and realizes wireless communication with the road surface evaluation device 30 via the communication network 50 in accordance with standards such as LTE (Long Term Evolution), 4G (4th Generation), 5G (5th Generation), or Wi-Fi (registered trademark). The communication unit 13 is used, for example, to transmit the above-mentioned driving information 120 to the road surface evaluation device 30.

[0031] The sensor unit 14 is composed of, for example, a GPS (Global Positioning System) sensor 141, an outside air temperature measurement sensor 142, etc. The GPS sensor 141 functions as a position detection means for detecting position information, receives GPS satellite signals, and measures the position information (latitude and longitude) of the vehicle 60. Positioning by the sensor unit 14 is performed at a predetermined cycle, as described above. The outside air temperature measurement sensor 142 functions as a road surface temperature detection means for detecting road surface temperature information, which can be considered as the road surface temperature at the traveling position of the vehicle 60. Note that, since the lower the ground clearance of the outside air temperature measurement sensor 142, the greater the influence of radiant heat. Therefore, it is desirable that the ground clearance of the outside air temperature measurement sensor 142 be equal to or less than a predetermined value. Furthermore, it is preferable to set the predetermined value to a value that will result in the outside air temperature measurement sensor 142 being equipped on many vehicles 60 being equal to or less than the predetermined value. For example, the predetermined value may be set to 70 cm.

[0032] The display unit 15 is configured with a display device such as a liquid crystal display or an organic electroluminescence panel. The input unit 16 is configured with an input device (not shown) such as a physical switch called a numeric keypad or a touch panel provided over the display surface of the display unit 15, and enables a user to perform selection operations.

[0033] Although not shown, a mobile terminal 20 may be used to communicate with the road surface evaluation device 30. For example, when a user gets into the vehicle 60 carrying the mobile terminal 20 and turns on an activation switch of the vehicle 60, such as an ignition switch, the vehicle 60 and the mobile terminal 20 are connected (paired), and the mobile terminal 20 starts transmitting the traveling information 120, including the moving object identification information, the position information measured by the mobile terminal 20, the first temperature information measured by the outside air temperature measurement sensor 142, etc., to the road surface evaluation device 30. When the activation switch of the vehicle 60, such as the ignition switch, is turned off, the pairing between the vehicle 60 and the mobile terminal 20 is released, and the transmission of the traveling information 120 to the road surface evaluation device 30 is terminated. The in-vehicle device 10 has been described above.

[0034] Next, a description will be given of the road surface evaluation device 30. Fig. 3 shows the overall configuration of the road surface evaluation device 30. As shown in Fig. 3, the road surface evaluation device 30 includes a control unit 31, a storage unit 32, and a communication unit 33.

[0035] The control unit 31 is composed of a processing unit such as a microprocessor, and controls each unit constituting the road surface evaluation device 30. The control unit 31 will be described in detail later.

[0036] The storage unit 32 is composed of a semiconductor memory or the like, and stores various programs such as control programs called firmware or operating systems, programs for performing information analysis processing, and other various information such as map information. The figure shows, as information stored in the storage unit 32, map information 321, which is information particularly related to the evaluation processing of road surface performance information, a driving information database 322, and a second temperature information database 323, which is information on changes in predicted temperature (or measured temperature information) over time as weather forecast information for each predetermined area of ​​the map information 321.

[0037] The map information 321 includes information on features such as roads and facilities, road information, and other information. The road information includes road network data, including location information and type information on nodes (e.g., road intersections, bends, and endpoints), location information and type information on road links, which are routes connecting each node, and link cost data on cost information (e.g., distance, required time, etc.) for all links. The road information may also include road type (e.g., national highway, prefectural road, or municipal road). In this way, for example, national highways, prefectural roads, or municipal roads may be used as road surface evaluation targets in the present invention. FIG. 4 shows an example of road link information as a road unit for road performance evaluation, using an intersection as an example of a node and a route connecting two intersections as an example of a road link. In this way, as described below, the evaluation unit 314 can use road link information as a road unit for evaluating road performance. As described below, the output unit 315 can output the road surface performance information in association with each road link.

[0038] The map information 321 may be configured to be stored in advance in the storage unit 32, or may be configured to be downloaded as needed from a server device (not shown) connected to the communication network 50. Furthermore, the map information 321 may be modified as needed in response to user input or the like.

[0039] The travel information database 322 is a database constructed based on travel information 120 of the traveling vehicle 60 (such as identification information of the vehicle 60, location information of the vehicle 60, time information, outside air temperature information measured by the outside air temperature measurement sensor 142 of the vehicle 60, vehicle model information of the vehicle 60, and mounting location information of the outside air temperature measurement sensor 142) acquired by the travel information acquisition unit 311 (described later). Here, the mounting location information of the outside air temperature measurement sensor 142 may be included in the travel information 120 transmitted from the vehicle 60, as described above. Furthermore, the travel information acquisition unit 311 may acquire mounting location information of the outside air temperature measurement sensor 142 of the vehicle 60 based on the vehicle model information 125. The location information includes not only information indicating the measured location but also the time when the positioning was performed. By linking this time-discretely changing location information, the travel information database 322 can identify the traveled roads by identifying the travel route of the vehicle 60. Furthermore, by using the position information and time information, it is possible to calculate the time information for passing through each road link, which is a route connecting each node on the travel route (for example, road intersections, bends, endpoints, etc.). Note that in an environment where this embodiment is implemented, if the accuracy of the position information is low, the travel information acquisition unit 311, which will be described later, may perform map matching to compare the position information with map information 321 to identify the road traveled. However, if the accuracy of the position information is high, map matching is not necessarily required.

[0040] The second temperature information database 323 is a database constructed based on information on changes in predicted temperature over time as weather forecast information for each predetermined area in the map information 321 acquired by the weather forecast information acquisition unit 312 (described later). The second temperature information database 323 is a database configured of predicted temperature information 127 (or measured temperature information) for each hour in a predetermined area including road information (e.g., link information) that is the subject of road performance evaluation. Here, it is desirable that the predicted temperature information be constructed for each piece of road information (e.g., road link), but it may also be temperature information predicted for each area including one or more road links.

[0041] The communication unit 33 has a DSP and the like, and realizes wireless communication with the vehicle 60 (on-board device 10) via the communication network 50 in accordance with communication standards such as LTE (Long Term Evolution), 4G (4th Generation), 5G (5th Generation), or Wi-Fi (registered trademark).

[0042] Next, the control unit 31 will be described. The control unit 31 is composed of a microprocessor having a CPU, RAM, ROM, I / O, etc. The CPU executes each program read from the ROM or the storage unit 32. During execution, the CPU reads information from the RAM, ROM, and storage unit 32, writes information to the RAM and storage unit 32, and exchanges signals with the communication unit 33, the display unit 34, and the input unit 35. In this manner, the processing in this embodiment is realized by the cooperation of hardware and software (programs). By executing each program, the control unit 31 causes the road surface evaluation device 30 to function as predetermined means (hereinafter collectively referred to as the "road surface evaluation control unit"). Furthermore, by executing each program, the control unit 31 causes the road surface evaluation device 30, which serves as a computer, to execute predetermined steps (hereinafter collectively referred to as the "road surface evaluation device steps"). Below, the functions of the control unit 31 will be described from the perspective of the road surface evaluation control unit. Note that a description from the perspective of the road surface evaluation control steps (method) will be omitted because it can be explained by replacing "unit" with "step." As shown in Figure 3, the control unit 31 includes, as functional blocks, a driving information acquisition unit 311, a map information acquisition unit 312, a weather forecast information acquisition unit 313, an evaluation unit 314, and an output unit 315.

[0043] The travel information acquisition unit 311 acquires travel information 120 including position information, time information, and first temperature information of the outside air temperature measurement sensor 142 for a plurality of vehicles 60 that are traveling. In this case, as described above, the travel information acquisition unit 311 may acquire information on the ground height of the outside air temperature measurement sensor 142 provided in the vehicle 60 as the travel information 120. Note that it is preferable that the travel information acquisition unit 311 acquires travel information 120 on sunny days, rather than on cloudy days or rainy days. This makes it possible to acquire the first temperature information and the second temperature information more accurately.

[0044] The map information acquisition unit 312 acquires map information including road information. Specifically, as described above, road link information may be acquired for each road in the road information to be used for road performance evaluation. In this way, as will be described later, the evaluation unit 314 can acquire road link information on the roads along which the vehicles 60 are traveling, based on the position information included in the travel information 120 of the multiple vehicles 60 that are traveling and that is acquired by the travel information acquisition unit 311.

[0045] The weather forecast information acquisition unit 313 acquires second temperature information, which is information on changes in predicted temperature (or measured temperature) over time and date, as weather forecast information (or weather measurement information) for each predetermined area of ​​the map information. As a result, as described below, the evaluation unit 314 provides the user with the latest temperature information (second temperature information) for each predetermined area including a road unit (e.g., a road link) and the latest road surface temperature information (first temperature information) for each road unit, thereby alerting the user to avoid risks such as heatstroke and burns caused by radiant heat in the summer. The weather forecast information acquisition unit 313 may also acquire temperature measurement information at a predetermined date and time for each predetermined area of ​​the map information as the second information. By doing so, the evaluation unit 314 can more accurately estimate road surface performance information for each road unit by using the measured temperature instead of the predicted temperature as the second temperature information.

[0046] The evaluation unit 314 may calculate differential temperature information between the first temperature information and the second temperature information for each road unit (e.g., road link) of the road information at a predetermined time, and estimate the road surface performance information based on the differential temperature information. Note that, as described above, the time may be set at a predetermined time interval.

[0047] For this reason, first, the evaluation unit 314 identifies road link information on which each vehicle 60 is traveling at a certain time based on the position information included in the travel information 120 of the multiple vehicles 60 currently traveling and the position information of the road links included in the map information 321, which are acquired by the travel information acquisition unit 311. Note that the identified road link information may be stored in association with the travel information 120 stored in the travel information database 322. Specifically, based on the travel information 120 of the multiple vehicles 60 stored in the travel information database 322, the evaluation unit 314 identifies road link information on which each vehicle 60 is traveling based on the position information of all vehicles 60 traveling within a predetermined area at a certain time in chronological order of a time period on a predetermined day (e.g., from midnight to midnight or a daytime time period), and acquires first temperature information measured at that time by the outside air temperature measurement sensor 142 of each vehicle 60. In this way, for each road link within the area, the evaluation unit 314 can acquire first temperature information measured by the vehicle 60 traveling on the road link at a time included in a time slot on a preset day. As described above, vehicles 60 whose ground clearance for the outside air temperature measurement sensor 142 exceeds a predetermined value may be excluded from the target vehicle 60. Since the closer the outside air temperature measurement sensor 142 mounted on the vehicle 60 is to the road surface, the closer the first temperature information is to road surface temperature information, the evaluation unit 314 may acquire first temperature information only for vehicles 60 whose ground clearance information for the outside air temperature measurement sensor 142 mounted on the vehicle 60 is equal to or less than a predetermined value (i.e., the evaluation unit 314 may not use the travel information 120 of vehicles 60 whose ground clearance information for the outside air temperature measurement sensor 142 exceeds or exceeds a predetermined value). This is expected to result in more accurate first temperature information. Furthermore, the evaluation unit 314 acquires the first temperature information measured by the vehicle 60 traveling on each road link during a time period of a day, for example, from 0:00 to 24:00, for each road link within the area, but this is not limited to this.For example, instead of the time period from midnight to midnight, the first temperature information may be acquired in chronological order during the daytime hours (for example, the eight hours from 9:00 AM to 6:00 PM, 8:00 AM to 4:00 PM, or from sunrise to sunset, which are the time periods used by the Japan Meteorological Agency and other organizations in weather forecasts).

[0048] In this way, the evaluation unit 314 can calculate a set of first temperature information for road links included in the area, for example, every 10 minutes, during a predetermined time period in one day. Note that if the same vehicle 60 is traveling (or stopped) on the same road link within a 10-minute period, multiple pieces of first temperature information measured by the same vehicle 60 are included in the first temperature set as independent pieces of first temperature information. By doing so, the evaluation unit 314 can estimate the statistical value of the first temperature information at each 10-minute time period as road surface temperature information (first temperature information) for each road link by calculating a statistical value, such as a maximum or average value, of the first temperature information based on the set of first temperature information for each 10-minute period. Note that although the method of calculating road surface temperature information (first temperature information) for each road link every 10 minutes has been exemplified, the calculation is not limited to 10 minutes. For example, the calculation may be performed in any unit, such as every minute, every 20 minutes, every 30 minutes, or every hour. Furthermore, if there is a time period between midnight and midnight when the vehicle 60 is not traveling on the road link, the first temperature information may be calculated by replacing the time period between midnight and midnight with a daytime time period, as described above.

[0049] Next, the evaluation unit 314 acquires second temperature information for a predetermined area including the road link to be evaluated, for example, every 10 minutes during a time period of one day, thereby enabling the evaluation unit 314 to calculate differential temperature information between the first temperature information and the second temperature information during the time period for each road link to be evaluated.

[0050] By doing so, the evaluation unit 314 may calculate, for example, the difference between the first temperature information and the second temperature information at the time when the second temperature information records the highest temperature of the day as the road surface performance information of the road link. Furthermore, the evaluation unit 314 may compare the road surface temperatures of each road link at the time when the highest temperature of the day is recorded. Specifically, the smaller the difference, the lower the road surface temperature of the road link, i.e., the better the road surface performance of the road link may be estimated. Conversely, the larger the difference, the higher the road surface temperature of the road link, i.e., the worse the road surface performance may be estimated.

[0051] When calculating the differential temperature information as road surface performance, the evaluation unit 314 may use the average value of the second temperature information for the time period during the day on the current day as the second temperature information, and may also use the average value of the first temperature information for the time period during the day on the current day as the first temperature information. In this way, the evaluation unit 314 may estimate the quality of road surface performance based on the difference between the average value of the second temperature information for the time period during the day on the road link to be evaluated and the average value of the first temperature information for the time period during the day on the current day.

[0052] FIG. 5 is a diagram illustrating a comparison between the first temperature information and the second temperature information for a road link. The road surface temperature information is also shown for reference to indicate that it is higher than the second temperature information. As shown in FIG. 5, it is estimated that the difference between the first temperature information and the second temperature information for a road link will be large from 12:00 to 14:00. Therefore, when comparing the road performance of different road links, the evaluation unit 314 preferably performs evaluation based on the values ​​from 12:00 to 14:00, when the difference between the first temperature information and the second temperature information is large.

[0053] It is estimated that when road performance is poor, the road surface temperature will be high at night due to the release of the thermal energy of sunlight absorbed by the road surface during the day. Therefore, it is estimated that the differential temperature information at night will not change significantly compared to the differential temperature information during the day. The evaluation unit 314 can evaluate that road performance is poor by comparing the differential temperature information during the day with the differential temperature information during the night. FIG. 6 is a comparison table that compares the differential temperature information during the day with the differential temperature information during the night, and estimates road performance based on the difference between the differential temperature information during the day and the differential temperature information during the night. In this way, the evaluation unit 314 can supplement the estimated result of road performance by comparing the differential temperature information during the day with the differential temperature information during the night. The evaluation unit 314 has been described above.

[0054] Finally, the output unit 315 outputs road surface performance information in association with the road link. For example, the output unit 315 outputs road surface performance information (differential temperature information) in association with each of multiple road information (road links) to be compared. This makes it possible to compare the performance of multiple road links and estimate their relative merits. For example, by estimating which road units have high radiant heat temperatures in the summer, it becomes easy to determine the priority of "heat-shielding pavement construction" for road surfaces that are effective in mitigating the heat island effect. The output unit 315 may also output road surface performance information (differential temperature information) over time. This makes it easy to identify areas where the radiant heat temperature is significantly increasing, or areas where "heat-shielding pavement construction" was previously performed but has deteriorated, causing radiant heat to rise again, thereby enabling prioritization of "heat-shielding pavement construction." The output unit 31 may also enable an intuitive understanding of the performance of the road link by, for example, coloring each road link (or using shades of black and white, etc.) according to the road surface performance information of the road link on the map shown in Fig. 4. The output unit 315 may also provide the road surface performance information of the road link to the end user and alert them, thereby making it possible to avoid risks such as heatstroke and burns due to radiant heat in the summer.

[0055] The above describes embodiments of the functional units of the road surface evaluation system 1 of the present invention based on the configuration of the on-board device 10 mounted on the vehicle 60 and the road surface evaluation device 30. Note that the embodiments of the functional units provided in the road surface evaluation device 30 of the present invention can be deployed so as to be executed by a single computer, or in a distributed manner on multiple computers located in one location or distributed across several locations and interconnected by a communication network. They can also be configured using multiple virtual computers on the cloud.

[0056] <Operation of this embodiment> Next, the operation of the evaluation unit 314 of this embodiment will be described with reference to the flowchart in Fig. 7. It is assumed that, when the evaluation unit 314 makes an evaluation, the area including the road to be subjected to performance evaluation and the date on which the difference between the first temperature information and the second temperature information is to be calculated are set in advance. For example, these may be set by the user via the input unit 35 or a user terminal connected via the communication network 50.

[0057] In step S1, the evaluation unit 314 identifies the road link on which all vehicles 60 are traveling in a predetermined area at a predetermined time, in chronological order of a predetermined time period (e.g., from midnight to midnight or a daytime time period) on a predetermined day, based on the travel information 120 of the vehicle 60 stored in the travel information database 322, based on the location information of the time, and acquires first temperature information measured at the time by the outside air temperature measurement sensor 142. Note that, as described above, travel information 120 of a vehicle 60 whose ground clearance above the ground of the outside air temperature measurement sensor 142 exceeds a predetermined value may be excluded from the evaluation.

[0058] In step S2, the evaluation unit 314 calculates a statistical value such as the maximum or average value of the outside air temperature information (first temperature information) based on a set of the outside air temperature information (first temperature information) measured by the vehicle 60 traveling on each road link at each predetermined time, and regards the calculated statistical value as the road surface temperature of each road unit at that time. In this way, the evaluation unit 314 can calculate the road surface temperature information (first temperature information) of each road link at each predetermined time during a predetermined time slot on a preset day.

[0059] In step S3, the evaluation unit 314 acquires second time information, which is information about changes in predicted temperature (or measured temperature) for each predetermined time interval during a predetermined time period on a preset day in an area including a road link, by referring to the second temperature information database 323. This allows the evaluation unit 314 to calculate second temperature information within the area (or each road link included therein) during a predetermined time period on a preset day.

[0060] In step S4, the evaluation unit 314 calculates the maximum temperature and the time at which the maximum temperature will occur based on the set of second temperature information within the area (or each road link included therein) at a specified time during a specified time period (for example, a range from midnight to midnight, or a daytime period, etc.).

[0061] In step S5, the evaluation unit 314 acquires the first temperature information of each road link at the time when the second temperature information indicates the highest temperature in a predetermined time period.

[0062] In step S6, the evaluation unit 314 calculates the difference temperature information between the first temperature information of each road link at the time when the second temperature information indicates the maximum temperature and the second temperature information indicating the maximum temperature.

[0063] In step S7, the output unit 315 calculates the priority of road performance between each road unit based on the differential temperature information for each road link, and can display, for example, the priority of road performance for each road unit. The output unit 315 may also create a diagram showing a comparison between the first temperature information and the second temperature information for the road link shown in Figure 5.

[0064] In step S6 of the operation of the evaluation unit 314, the evaluation unit 314 calculates the difference temperature information between the first temperature information of each road link at the time when the second temperature information of the area (i.e., each road link) is the highest temperature and the second temperature information of the highest temperature, but this is not limited to this. As described above, the evaluation unit 314 may calculate the second temperature information as the average temperature during the daytime, and calculate the difference temperature information from the average temperature of the first temperature information during the daytime.

[0065] According to the operation of this embodiment described above, the road surface evaluation device 30 can estimate the performance of a road surface with a simple configuration that utilizes location information obtained by the GPS sensor 141 and outdoor temperature measurement information obtained by the outdoor temperature measurement sensor 142, both of which are equipped in many vehicles 60. Furthermore, by providing this information to end users and raising their awareness, it is possible to avoid risks such as heatstroke and burns caused by radiant heat in the summer. Furthermore, by estimating which road units have high radiant heat temperatures in the summer, it becomes easier to determine the priority of "heat-shielding pavement construction" for road surfaces that are effective in mitigating the heat island effect. Furthermore, by outputting road surface performance information (differential temperature information) over time, it becomes easier to identify, for example, areas where the radiant heat temperature is significantly increasing, or areas where "heat-shielding pavement construction" was previously performed but has deteriorated and radiant heat is once again increasing, thereby enabling prioritization of "heat-shielding pavement construction." This concludes the description of this embodiment.

[0066] <Modifications> Although the above-described embodiment is a preferred embodiment of the present invention, the scope of the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the gist of the present invention. For example, the present invention can be made in modifications such as the modifications described below.

[0067] For example, the functional configurations shown in Figures 1, 2, and 3 are merely examples and do not limit the functional configuration of this embodiment. In other words, it is sufficient for each device to have the function of executing a series of processes related to the road surface evaluation function of the present invention as a whole, and the type of functional block used to realize this function is not particularly limited to the examples shown in Figures 1, 2, and 3.

[0068] As another modification, the on-board device 10 may be realized by, for example, an on-board ECU device. Furthermore, as another modification, although the above embodiment has been described as realizing the road surface evaluation device 30 by a single server device or the like, the road surface evaluation device 30 may be realized as a distributed processing system in which the functions of the road surface evaluation device 30 are appropriately distributed among a plurality of server devices. Furthermore, the functions of the road surface evaluation device 30 may be realized by using a virtual server function or the like on the cloud.

[0069] As another modification, a FCD (Floating Car Data) server (tentative name) may be provided separately from the road surface evaluation device 30, and the FCD server may receive the driving information 120 of each vehicle 60 from the vehicle 60. As a result, the road surface evaluation device 30 may acquire the driving information 120 of each vehicle 60 from the FCD server. As another modification, the FCD server may construct a driving information database 322 based on the driving information 120 received from each vehicle 60, and create and update the database as needed. In this case, the road surface evaluation device 30 may acquire the information stored in the driving information database 322 from the FCD server as needed.

[0070] Furthermore, as another modified example, an input / output interface with a user may be realized via a user terminal (not shown) that is connected to the communication network 50 and capable of communicating with the road surface evaluation device 30. Specifically, for example, after logging in to the road surface evaluation device 30 from the user terminal and the road surface evaluation device 30 determines that the user ID is valid, the road surface evaluation device 30 generates a user interface screen and provides the generated user interface screen to the user terminal, so that the user can inquire of the road surface evaluation device 30 via the user terminal about the risk of heatstroke, burns, and the like due to radiant heat in summer, for example.

[0071] <About Hardware and Software> Each device included in the above navigation system can be realized by hardware, software, or a combination of these. Furthermore, the navigation method performed by the devices included in the above navigation system working together can also be realized by hardware, software, or a combination of these. Here, "realized by software" means that it is realized by a computer reading and executing a program.

[0072] The program can be stored and supplied to a computer using various types of non-transitory computer-readable media. Non-transitory computer-readable media include various types of tangible storage media. Examples of non-transitory computer-readable media include magnetic recording media (e.g., flexible disks, magnetic tapes, hard disk drives), magneto-optical recording media (e.g., magneto-optical disks), CD-ROMs (Read Only Memory), CD-Rs, CD-RWs, and semiconductor memories (e.g., mask ROMs, programmable ROMs (PROMs), erasable PROMs (EPROMs), flash ROMs, and random access memories (RAMs)). The program may also be supplied to a computer by various types of transitory computer-readable media. Examples of transitory computer-readable media include electrical signals, optical signals, and electromagnetic waves. The transitory computer-readable media can be supplied to a computer via wired communication paths such as electric wires and optical fibers, or via wireless communication paths.

[0073] REFERENCE SIGNS LIST 1 Road surface evaluation system 10 In-vehicle device 11 Control unit 111 Traveling information transmission unit 12 Memory unit 120 Traveling information 13 Communication unit 14 Sensor unit 141 GPS sensor 142 Outside air temperature measurement sensor 15 Display unit 16 Input unit 20 Mobile terminal 30 Road surface evaluation device 31 Control unit 311 Traveling information acquisition unit 312 Map information acquisition unit 313 Weather forecast information acquisition unit 314 Evaluation unit 315 Output unit 32 Memory unit 321 Map information 322 Traveling information database 323 Second temperature information database 33 Communication unit 34 Display unit 35 Input unit 50 Communication network 60 Vehicle

Claims

1. A road surface evaluation device comprising: a driving information acquisition unit that acquires driving information for a plurality of vehicles in motion, including position information, time information, and first temperature information from an outside air temperature measurement sensor; a map information acquisition unit that acquires map information including road information; a weather forecast information acquisition unit that acquires second temperature information, which is information on changes in predicted temperature over time, as weather forecast information for each specified area of ​​the map information; an evaluation unit that calculates differential temperature information between the first temperature information and the second temperature information for each road unit of the road information for each of the time information, and estimates road surface performance information based on the differential temperature information; and an output unit that outputs the road surface performance information in association with the road information of the map information.

2. The road surface evaluation device according to claim 1, characterized in that the evaluation unit calculates the differential temperature information for each piece of time information including the time at which the second temperature information records the highest temperature of the day.

3. The road surface evaluation device according to claim 1, wherein the evaluation unit calculates the differential temperature information as the average value of the daytime temperature for each hour of the day on which the second temperature information is calculated.

4. The road surface evaluation device according to claim 1, characterized in that the map information acquisition unit includes road link information in the road information, the evaluation unit defines the road unit of the road information as a road link, and the output unit outputs the road surface performance information in association with the road link.

5. The road surface evaluation device described in claim 1, characterized in that the driving information acquisition unit acquires information on the ground height of the vehicle's outside air temperature measurement sensor as the driving information, and the evaluation unit estimates road surface performance information using first temperature information measured by a vehicle whose outside air temperature measurement sensor is mounted at a ground height equal to or less than a predetermined value.

6. A road surface evaluation device as described in claim 1 or 2, characterized in that the evaluation unit evaluates the road surface performance information as having lower performance the smaller the difference between the differential temperature information when the time information is daytime and the differential temperature information when the time information is nighttime.

7. A road surface evaluation method carried out by one or more computers, comprising: a driving information acquisition step of acquiring driving information for a plurality of vehicles in motion, including position information, time information, and first temperature information from an outside air temperature measurement sensor; a map information acquisition step of acquiring map information including road information; a weather forecast information acquisition step of acquiring second temperature information, which is information on changes in predicted temperature over time, as weather forecast information for each specified area of ​​the map information; an evaluation step of calculating differential temperature information between the first temperature information and the second temperature information for each road unit of the road information for each of the time information, and estimating road surface performance information based on the differential temperature information; and an output step of outputting the road surface performance information in association with the road information of the map information.

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