Wetness brightness information generation device, point brightness information transmission device, road surface state determination device, and road surface state determination method

Abstract

The purpose of the present disclosure is to generate wetness brightness information used for wetness determination of a road surface in front of a target vehicle, or perform wetness determination using the wetness brightness information, even when an oncoming vehicle illuminating the road surface in front of the target vehicle is not present. This wetness brightness information generation device (201) comprises: a point brightness information acquisition unit (21) that acquires a plurality of pieces of point brightness information detected by at least one probe vehicle; a wetness brightness information generation unit (23) that generates wetness brightness information for each road surface range on the basis of the plurality of pieces of point brightness information corresponding to the same road surface range; and a wetness brightness database management unit (24) that creates a wetness brightness database (25) in which the wetness brightness information is associated with position information about the road surface range, and provides the wetness brightness information to an external device. In a vehicle-mounted apparatus of the target vehicle, the wetness brightness information is used for wetness determination of a target road surface area, illuminated by a lighting device of the target vehicle, in comparison with brightness information indicating the brightness of the target road surface area as seen from the target vehicle.

Description

Device for generating dry / wet and light / dark information, device for transmitting location light / dark information, road surface condition determination device, and road surface condition determination method

[0001] This disclosure relates to the determination of the dryness / wetness of a road surface.

[0002] Conventionally, there has been known a technique for determining whether the road surface around a vehicle is dry or wet (hereinafter referred to as "dry / wet determination") and controlling an in-vehicle device. For example, when the road surface in front of the vehicle is determined to be a wet road surface, appropriate driving control is implemented in consideration of the decrease in the road surface friction coefficient to ensure driving safety. Alternatively, when the road surface in front of the vehicle is determined to be a wet road surface, lighting control is implemented to reduce the luminous intensity of the illumination light to the road surface area where the reflected light hits the oncoming vehicle so that the light of the headlight of the target vehicle is specularly reflected on the road surface and does not dazzle the oncoming vehicle.

[0003] At night, due to poor visibility, it is difficult for a driver to determine dryness / wetness visually. When it is raining, by looking at the water droplets falling on the windshield, the driver can clearly judge that the road surface is wet. However, after the rain stops, it is often impossible to visually determine whether the road surface is wet or not, so there is a need to determine the dryness / wetness of the road surface by an in-vehicle device.

[0004] For example, Patent Document 1 discloses a technique for detecting that the light of the headlight of an oncoming vehicle is specularly reflected on the road surface and determining that the road surface is wet.

[0005] [[ID=!International Publication No. 2023 / 176490

[0006] However, the technique of Patent Document 1 has a problem that dry / wet determination cannot be performed when there is no oncoming vehicle that irradiates the road surface in front of the target vehicle with its headlight.

[0007] This disclosure has been made to solve the above problems, and an object thereof is to generate dry / wet and light / dark information used for dry / wet determination of the road surface in front, or to perform dry / wet determination using the dry / wet and light / dark information, even when there is no oncoming vehicle that irradiates light on the road surface in front of the target vehicle. <!

[0008] The wet / damp light information generating device of this disclosure includes: a location brightness information acquisition unit that acquires multiple location brightness information, which represents the brightness of a road surface area illuminated by the lighting device of at least one probe vehicle and is linked to location information of the road surface area, as detected by at least one probe vehicle; a wet / damp light information generation unit that generates wet / damp light information for each road surface area, which serves as a standard for wet / damp determination, based on the multiple location brightness information corresponding to the same road surface area; and a wet / damp light database management unit that creates a wet / damp light database linked to location information of the road surface area, extracts the wet / damp light information from the wet / damp light database and provides it to an external device. The wet / damp light information is used to determine the wet / damp state of a target road surface area by comparing it with brightness information representing the brightness of the target road surface area as seen from the target vehicle, as illuminated by the lighting device of the target vehicle, in an on-board device of the target vehicle, which is an external device or a device connected to the external device.

[0009] The wet / dark information generation device of this disclosure can generate wet / dark information used to determine the wetness of the road surface ahead of the target vehicle, even when there is no oncoming vehicle illuminating the road surface ahead of the target vehicle. The purpose, features, embodiments, and advantages of this disclosure will become clearer from the following detailed description and accompanying drawings.

[0010] This is a block diagram showing the configuration of the location brightness information transmitting device and the wet / dry brightness information generating device according to Embodiment 1. This is a flowchart showing the operation of the location brightness information generating device according to Embodiment 1. This is a plan view showing the observation area of ​​brightness information on the road surface in front of the probe vehicle. This is a diagram showing a captured image including the observation area of ​​brightness information on the road surface in front of the probe vehicle. This is a diagram showing an example where the brightness information changes depending on the type of pavement on the road surface on which the probe vehicle is traveling. This is a flowchart showing the information storage process of the wet / dry brightness information generating device according to Embodiment 1. This is a diagram showing location brightness information stored in the wet / dry brightness information generating device according to Embodiment 1. This is a diagram showing the wet / dry brightness database creation process of the wet / dry brightness information generating device according to Embodiment 1. This is a diagram showing how headlight illumination reflects off a dry road surface. This is a diagram showing how headlight illumination reflects off a wet road surface. This is a diagram showing the frequency distribution of location brightness information on road surfaces A and B. This is a diagram showing the wet / dry brightness database. This is a diagram showing the brightness judgment threshold formulated from the frequency distribution of location brightness information on road surface A. This is a diagram showing the relationship between the elapsed time after the end of rainfall and the dryness of the road surface. This is a diagram showing the relationship between location brightness information on road surface A and the dryness of the road surface. This figure shows how the light from streetlights and headlights reflects off the target vehicle. This figure shows how the brightness information changes due to the reflected light from streetlights. This figure shows the on and off timing of the LED headlights according to Embodiment 2. This figure shows the brightness information observed by the photodiode according to Embodiment 2. This is a block diagram showing the configuration of the road surface condition determination device according to Embodiment 3. This is a flowchart showing the operation of the road surface condition determination device according to Embodiment 3. This is a block diagram showing the configuration of the road surface condition determination device according to Embodiment 4. This figure shows the hardware configuration of the location brightness information transmission device, the dry / wet brightness information generation device, and the road surface condition determination device. This figure shows the hardware configuration of the location brightness information transmission device, the dry / wet brightness information generation device, and the road surface condition determination device.

[0011] <A. Embodiment 1> <A-1. Configuration> Figure 1 is a block diagram showing the configuration of the location brightness information transmitting device 101 and the dry / wet brightness information generating device 201 according to Embodiment 1.

[0012] The location brightness information transmitting device 101 is mounted on at least one probe vehicle and detects the brightness of the surrounding road surface illuminated by the probe vehicle's lighting device 11. The location brightness information transmitting device 101 also collects the brightness information representing the detected brightness of the surrounding road surface, compiles it into location brightness information for each predetermined processing range of the road surface, and transmits it to the wet / dry brightness information generating device. The processing range of the road surface where the location brightness information is created may be a point on the road surface or a section between two points on the road surface.

[0013] The location brightness information transmitting device 101 is comprised of a lighting device 11, a photography device 12, a positioning device 13, a location brightness information generation unit 14, and a location brightness information transmitting unit 15.

[0014] The lighting device 11 is mounted on the probe vehicle and illuminates the road surface surrounding the probe vehicle. Here, the road surface surrounding the probe vehicle refers to the road surface that the lighting device 11 mounted on the probe vehicle can illuminate, but in the following explanation, the road surface in front of the probe vehicle will be used as an example of the surrounding road surface. The lighting device 11 is, for example, a headlight.

[0015] The imaging device 12 photographs the surrounding road surface of the probe vehicle illuminated by the lighting device 11. If the surrounding road surface is the road surface ahead, the imaging device 12 photographs a forward image including the road surface in front of the probe vehicle.

[0016] The positioning device 13 positions the probe vehicle. The positioning device 13 is, for example, a GNSS (Global Navigation Satellite System).

[0017] The location brightness information generation unit 14 calculates brightness information representing the brightness of a predetermined determination area included in the illumination range from the forward image captured by the camera 12 when the lighting device 11 is illuminating the road surface ahead. The location brightness information generation unit 14 also generates location brightness information by associating the brightness information with location information in units of processing range of the road surface ahead.

[0018] The location brightness information transmission unit 15 transmits location brightness information to the dry / wet brightness information generation device 201 at a predetermined timing.

[0019] In this embodiment, the wet / dark information generation device 201 is a server that collects multiple point-specific light / dark information from at least one probe vehicle. The wet / dark information generation device 201 generates wet / dark information for each processing range of the road surface and transmits the generated wet / dark information to the external device 41. The processing range of the wet / dark information is a predetermined point or section of the road surface, and may be the same as or different from the processing range of the point-specific light / dark information. The wet / dark information is created based on multiple point-specific light / dark information. Therefore, the wet / dark information generation device 201 needs to collect multiple point-specific light / dark information for one processing range.

[0020] The external device 41 uses wet / dry and light / dark information to determine the wetness of the road surface around the vehicle. The vehicle whose surrounding road surface wetness is being determined is also called the target vehicle. The target vehicle may be the same vehicle as at least one probe vehicle or a different vehicle. The result of the wetness determination is used, for example, for driving control or lighting control of the target vehicle.

[0021] The wet / dark light information generation device 201 includes a location light / dark information acquisition unit 21, an information storage unit 22, a wet / dark light / dark information generation unit 23, a wet / dark light / dark database (DB) management unit 24, and a wet / dark light / dark database (DB) 25.

[0022] The location brightness information acquisition unit 21 acquires location brightness information associated with location information and stores the location brightness information in the information storage unit 22.

[0023] The information storage unit 22 is a memory that stores location brightness information.

[0024] The dry / wet brightness information generation unit 23 generates dry / wet brightness information for each predetermined processing range of the road surface by statistically processing brightness information from multiple points for each processing range. In this embodiment, a road link is used as an example of a processing range, which is the unit for creating dry / wet brightness information. That is, the dry / wet brightness information generation unit 23 generates dry / wet brightness information on a road link basis. The dry / wet brightness information is a determination criterion that indicates what level of brightness is required for a processing range of the road surface to be determined to be a dry road surface or a wet road surface.

[0025] The dry / wet light / dark DB25 is a database in which dry / wet light / dark information is linked to location information of the corresponding processing range. In this embodiment, the dry / wet light / dark DB25 is created for each road link.

[0026] The wet / dark / dark DB management unit 24 associates location information with the wet / dark / dark information generated by the wet / dark / dark information generation unit 23, and creates and updates the wet / dark / dark DB 25. The wet / dark / dark DB management unit 24 also provides the wet / dark / dark information from the wet / dark / dark DB 25 to the external device 41 upon request from the external device 41. For example, when the wet / dark / dark DB management unit 24 receives location information of the road surface from the external device 41, it provides the wet / dark / dark information corresponding to the specified location information to the external device 41.

[0027] Note that the configurations of the location brightness information transmission device 101 and the dry / wet brightness information generation device 201 in Figure 1 may be located on either the probe vehicle side or the server side, as long as there is no inconsistency.

[0028] <A-2. Operation> Figure 2 is a flowchart showing the operation of the location brightness information transmission device 101. The operation of the location brightness information transmission device 101 will be explained below in accordance with the flow shown in Figure 2.

[0029] The flow in Figure 2 begins when the probe vehicle starts moving. First, in step S101, the location brightness information generation unit 14 determines whether the lighting device 11 is on or not. Hereafter, the lighting device 11 will be the headlights. If the headlights are off (No in step S101), the location brightness information transmission device 101 proceeds to step S107, and if the headlights are on (Yes in step S101), the location brightness information transmission device 101 proceeds to step S102.

[0030] The location brightness information generation unit 14 may acquire control information from the lighting device 11 and determine whether the headlights are on or off based on this control information. Alternatively, the location brightness information generation unit 14 may acquire a forward image of the probe vehicle from the imaging device 12 and determine whether the headlights are on or off by performing image recognition on the forward image.

[0031] In step S102, the location brightness information generation unit 14 obtains the position of the probe vehicle at time t from the positioning device 13.

[0032] After step S102, in step S103, the location brightness information generation unit 14 acquires a forward image of the probe vehicle from the imaging device 12 and calculates brightness information for the forward road surface observation area E included in the forward image. Any physical quantity or virtual reference quantity that quantitatively represents the degree of brightness may be used for the brightness information. For example, the brightness information may be illuminance Lux or luminance cd / m ２ The following may be used. For brightness information, for example, the average brightness of each pixel corresponding to the observation area E in the forward image may be used. Furthermore, it is possible to calculate the relationship between the brightness value of each pixel and the illuminance from the setting value of the imaging device 12 or the illuminance obtained from an illuminance sensor installed in the imaging device 12.

[0033] Figure 3 is a top view showing the observation area E for brightness information. Figure 4 is a diagram showing the observation area E in the forward image of the probe vehicle 51. In the example in Figure 3, the observation area E is set to a range of 35 m to 40 m in front of the probe vehicle 51. The width of the observation area E is shorter than the road width or lane width, for example, set to 2 m. The observation area E is included within the illumination range 52 of the headlights.

[0034] Figures 3 and 4 are merely examples of observation area E. Observation area E can be set in any area of ​​the road surface ahead, as long as it is an area that can be illuminated by the high beam or low beam of the headlights. Furthermore, observation area E may be set in two or more locations. For example, multiple observation areas E may be set at different distances from the probe vehicle 51, multiple observation areas E may be set at different lateral positions on the road, or multiple observation areas E may be set at different distances from the probe vehicle 51 and at different lateral positions on the road.

[0035] When the probe vehicle is traveling on a straight road, the pixel range of the observation area E in the captured image is uniquely determined by the field of view and installation position of the imaging device 12. Therefore, the location brightness information generation unit 14 may calculate the brightness information of the observation area E from this uniquely determined pixel range. Alternatively, the location brightness information generation unit 14 may recognize the road shape of the road surface ahead by image recognition, identify the pixel range of the observation area E in the forward image from the road shape, and calculate the brightness information of the observation area E from the identified pixel range.

[0036] In the above description, the location brightness information generation unit 14 calculated brightness information based on the image captured by the imaging device 12. However, if a photodiode sensor (PD sensor) is used as the imaging device 12, the location brightness information generation unit 14 may calculate brightness information based on the illuminance or luminance at a predetermined position in front of the probe vehicle, as measured by the PD sensor.

[0037] After step S103, in step S104, the location brightness information generation unit 14 determines whether or not it is time to generate location brightness information. If it is time to generate (YES in step S104), the location brightness information transmission device 101 proceeds to step S105; if it is not time to generate (NO in step S104), the location brightness information transmission device 101 proceeds to step S107.

[0038] The generation timing can be defined in any way, but the following provisions are possible, for example.

[0039] Rule 1) Every fixed distance L. For example, every 10m or every 100m.

[0040] Rule 2) The timing when the brightness information changes to a value greater than or equal to a predetermined value.

[0041] Figure 5 shows an example of the change in brightness information BR(p) when the probe vehicle travels from position p = P0. For the sake of explanation, the brightness information BR(p) is expressed with position p as a parameter, rather than time t. However, since position p changes with time t, expressing the brightness information BR with time t as a parameter would result in similar characteristics to BR(p).

[0042] When the position of the probe vehicle is from P0 to P1, the road pavement of the observation area E is concrete, and when the position of the probe vehicle is after P1, the road pavement of the observation area E is asphalt. At the boundary of the position p = P1, the brightness information decreases to about 2 / 3. This is due to the difference in the light reflection characteristics or hue between concrete and asphalt. In such a case, when determining the generation timing according to the above-mentioned regulation 1), the boundary of a certain distance L may not coincide with the boundary of the point brightness information. In contrast, according to regulation 2), the point brightness information can be generated separately before and after the position p = P1 where the brightness information changes greatly.

[0043] Regulation 3): The timing when the probe vehicle crosses a road link or a sub-link.

[0044] The point brightness information generation unit 14 can identify the timing when the probe vehicle crosses a road link or a sub-link based on the road link information or sub-link information acquired from a map database (not shown).

[0045] Regulation 4): At regular intervals. For example, every 1 second or every 10 seconds.

[0046] In step S105, the point brightness information generation unit 14 generates the point brightness information.

[0047] In the following description, it is assumed that the point brightness information is generated at the timing of the above-mentioned regulation 1). Let the transmission position of the previous point brightness information be Pn - 1, the transmission position of the current point brightness information be Pn, and the distance between Pn - 1 and Pn be Ln. Ln is, for example, 10 m. The point brightness information generation unit 14 calculates a statistical representative value from a plurality of brightness information BR calculated in step S103 between Pn - 1 < p ≤ Pn, and uses this as the point brightness information BR(Pn - 1, Pn) in the interval from Pn - 1 to Pn (hereinafter, this is also denoted as the interval (Pn - 1, Pn)). The statistical representative value is, for example, the average value within the interval or the value with the maximum frequency.

[0048] When the average value is adopted as the statistical representative value, the point brightness information BR(Pn - 1, Pn) = (1 / Ln) × {∫BR(p)dp | p = Pn - 1 to Pn}.

[0049] The location brightness information BR is expressed as BR(p) based on the acquisition location of the source brightness information, but it may also be expressed as BR(t) based on the acquisition time of the source brightness information. Furthermore, the location brightness information BR may be expressed as BR(p(t)) or BR(p,t) using both time and location as parameters. In this embodiment, the location brightness information is expressed as BR(Pn-1, Pn) within the location range where the source brightness information was acquired.

[0050] In the above explanation, location brightness information was created for each section of road surface with a certain distance L. However, location brightness information may also be created for discrete locations. In other words, location brightness information should be created for road surface sections or locations, linked to the location information of the road surface area.

[0051] After step S105, in step S106, the location brightness information transmission unit 15 transmits the location brightness information BR(Pn-1, Pn) to the dry / wet brightness information generation device 201.

[0052] In this embodiment, the timing of generating location brightness information (step S105) and the timing of transmitting it (step S106) are assumed to be synchronized. However, these timings do not necessarily need to be synchronized. Location brightness information may be transmitted at any timing, such as at 10-minute intervals, when passing a link change point, at the end of driving, when the driver's intention to transmit is detected, or when a transmission request is received from the wet / dry brightness information generator 201.

[0053] If the location brightness information is nearly identical across multiple adjacent sections, for example, if the difference is within 5%, the location brightness information for those sections may be combined. For example, if the difference in location brightness information between sections (Ln-2, ​​Ln-1), (Ln-1, Ln), and (Ln, Ln+1) is small, the location brightness information BR(Pn-2, Pn+1) for section (Ln-2, ​​Ln+1) can be combined and calculated as {BR(Pn-2, Pn-1) + BR(Pn-1, Pn) + BR(Pn, Pn+1)} / 3. This reduces the communication resources and data volume required for location brightness information.

[0054] Furthermore, the location brightness information transmission unit 15 may not transmit all of the location brightness information generated by the location brightness information generation unit 14, but may select and transmit location brightness information for an area or link requested by the wet / dry brightness information generation device 201.

[0055] In step S107, the location brightness information transmitting device 101 determines whether the probe vehicle has finished traveling. If the travel has not finished, the processing of the location brightness information transmitting device 101 returns to step S101; if the travel has finished, the processing of the location brightness information transmitting device 101 ends.

[0056] Figure 6 is a flowchart showing the storage process of location brightness information in the dry / wet brightness information generation device 201. In step S201, the location brightness information acquisition unit 21 acquires location brightness information from the location brightness information transmission unit 15. Then, in step S202, the location brightness information acquisition unit 21 stores the location brightness information in the information storage unit 22.

[0057] Figure 7 illustrates the accumulated location brightness information. The information storage unit 22 stores location brightness information linked to vehicle ID, time, and section information.

[0058] The second row of Figure 7 shows the location brightness information Vm(tm11)|BR(Pn-1, Pn) for section Pn-1, Pn transmitted from the probe vehicle with vehicle ID = Vm. Note that tm11 is the time when the probe vehicle with vehicle ID = Vm passed through location Pn. The probe vehicle with vehicle ID = Vm travels from location Pn-1 to location Pn+x in one trip, so tm11, tm12, and tm13 are consecutive times.

[0059] Lines 6 through 9 of Figure 7 show location brightness information when probe vehicles with vehicle ID = Vm travel through the same area (from point Pn-1 to point Pn+x) from different times tm21. Lines 10 through 13 of Figure 7 show location brightness information when probe vehicles with vehicle ID = Vk travel through the same area (from point Pn-1 to point Pn+x) from time tk11. In this way, location brightness information obtained when multiple probe vehicles or the same probe vehicle travel through the same area is stored in the information storage unit 22.

[0060] Figure 8 is a flowchart showing the process of generating wet / dark information by the wet / dark information generation unit 23. In step S301, the wet / dark information generation unit 23 determines whether or not it is the predetermined timing for generating wet / dark information. If it is not the timing for generating wet / dark information in step S301, the wet / dark information generation unit 23 repeats step S301.

[0061] If step S301 is the timing for generating dry / wet light / dark information, then in step S302 the dry / wet light / dark information generation unit 23 generates dry / wet light / dark information in predetermined area units. Dry / wet light / dark information is information that serves as a criterion for determining whether the road surface is dry or wet.

[0062] After step S302, in step S303, the wet / dark DB management unit 24 updates the wet / dark DB 25 with the wet / dark information generated in step S302.

[0063] The timing for generating dry / wet light / dark information may be at regular intervals, such as every week, every month, or every six months. Alternatively, the timing for generating dry / wet light / dark information may be at irregular intervals, such as when a predetermined amount of time has elapsed since an operator operation or a road paving event occurred.

[0064] The dry / wet light / dark DB management unit 24 may set a flag indicating that the dry / wet light / dark information in the dry / wet light / dark DB 25 is being updated for areas where road paving has been performed or where road damage has occurred, until the process for generating new dry / wet light / dark information for those areas is completed.

[0065] Here, we will explain the difference in light and dark information between dry and wet road surfaces using Figures 9 and 10. Figure 9 shows the amount of light returning to the imaging device 12 when the lighting device 11 illuminates the road surface 54 ahead, which is a dry road surface. When light from the lighting device 11 shines on the road surface 54 ahead, the light is diffusely reflected by the fine irregularities 55 present on the road surface 54 ahead, and a portion of it returns to the imaging device 12, so that the road surface 54 ahead is observed by the imaging device 12. In Figure 9, the five arrows 56 represent the amount of light returning to the imaging device 12.

[0066] Figure 10 shows the amount of light returning to the imaging device 12 when the lighting device 11 illuminates the forward road surface 54, which is a wet road surface. Because the forward road surface 54 is covered with a water film 57, the light irradiated onto the forward road surface 54 is reflected in the direction of travel of the probe vehicle by specular reflection. Therefore, the ratio of reflected light to emitted light from the lighting device 11 on a wet road surface is smaller than that on a dry road surface. In Figure 10, the two arrows 56 represent the amount of reflected light to the imaging device 12, and the three arrows 58 represent the amount of specularly reflected light. Consequently, the brightness information for a wet road surface is darker than that for a dry road surface. This means that a wet road surface appears darker than a dry road surface.

[0067] Dry / wet light / dark information is represented by a pair of dry road surface light / dark information, which is representative of dry road surface conditions, and wet road surface light / dark information, which is representative of wet road surface conditions. Dry road surface light / dark information is the reference value for determining that a road surface area is a dry road surface in dry / wet determination. Wet road surface light / dark information is the reference value for determining that a road surface area is a wet road surface in dry / wet determination. This data format is also called data format 1. In this case, the road surface condition determination device described later can determine the dry / wet condition of the road surface in front of the target vehicle depending on whether the light / dark information detected while the target vehicle is driving is closer to the dry road surface light / dark information or the wet road surface light / dark information.

[0068] Wet / dry light / dark information is generated, for example, as follows. The wet / dry light / dark information generation unit 23 extracts location light / dark information for specific areas (specific sections). For example, when the wet / dry light / dark information generation unit 23 generates wet / dry light / dark information for a section (Pn-1, Pn), it extracts the wet / dry light / dark information for the section (Pn-1, Pn) shown in Figure 7, namely Vm(tm11)|BR(Pn-1, Pn), Vm(tm21)|BR(Pn-1, Pn), Vk(tk11)|BR(Pn-1, Pn), ... and generates a frequency distribution of location light / dark information.

[0069] Figure 11 shows an example of the frequency distribution of location light / dark information on road surfaces A and B. As shown in Figure 11, the frequency of location light / dark information is generally polarized between dry and wet road surfaces, so the frequency distribution has two peaks. The frequency distribution of location light / dark information for road surface A, shown by the solid line in Figure 11, has a peak for dry road surfaces, location light / dark information BRd(n), and a peak for wet road surfaces, location light / dark information BRw(n). Therefore, the dry / wet light / dark information generation unit 23 uses these two values ​​as dry / wet light / dark information. Road surface A is the road surface of section (Pn-1, Pn) and is concrete pavement.

[0070] The frequency distribution of point-specific brightness information for road surface B, shown by the dashed line in Figure 11, also has two peaks: point-specific brightness information BRd(m) for dry road surfaces and point-specific brightness information BRw(m) for wet road surfaces. Road surface B is the road surface for section (Pm-1, Pm) and is asphalt pavement. The frequency distribution of point-specific brightness information for road surface B is shifted towards the darker side compared to the frequency distribution of point-specific brightness information for road surface A, but still has two peaks.

[0071] In the above explanation, the peak values ​​of the frequency distribution were used as representative values ​​for dry and wet road surfaces, respectively, for the dry / wet light / darkness information. However, any value that represents the peak of the frequency distribution of the location light / darkness information is not limited to the peak value; values ​​obtained through other statistical mathematical processing (average, weighted average) may be used, or values ​​obtained according to a predetermined rule based on the shape of the frequency distribution may be used. The method of using the average value as the representative value for dry / wet light / darkness information is effective when the amount of accumulated location light / darkness information is small.

[0072] Figure 12 shows the wet / darkness database 25, which is a database of wet / darkness information expressed in data format 1. The wet / darkness database 25 is created by associating wet / darkness information with link IDs representing road links and section information. Wet / darkness information includes dry road surface light / darkness information BRd(n) and wet road surface light / darkness information BRw(n). In Figure 12, for the sake of simplicity, the wet / darkness information is database-organized on a link basis, but this is not limited to this. Wet / darkness information may also be database-organized on a sub-link basis, or on an arbitrary section basis. For example, in sections where the light / darkness information at a given location changes frequently, the section to be database-organized may be set to be short.

[0073] Although Figure 12 shows the road link as a single link, it is preferable to have two road links: an uphill link and a downhill link. This allows for a more accurate determination of the road surface condition even when the road surface condition or pavement differs between the uphill and downhill sections.

[0074] When the wet / dark light-dark DB management unit 24 receives a request from the external device 41 to provide wet / dark light-dark information, it performs the necessary authentication process and provides part or all of the wet / dark light-dark DB 25 to the external device 41 according to the request.

[0075] <A-3. Effects> According to this embodiment, it is possible to generate dry / wet light / dark information for determining the dry / wet state of the road surface from light / dark information when there are no oncoming vehicles at night. In vehicles that utilize this dry / wet light / dark information, the on-board device can be controlled according to the dry / wet state of the road, making it possible to effectively control the on-board device and drive safely.

[0076] <A-4. Modification of the Data Format for Dry / Wet Brightness Information> In the above explanation, dry / wet brightness information included dry road surface brightness information and wet road surface brightness information. However, other data formats may be used for dry / wet brightness information as long as it is information that serves as a criterion for determining whether the surrounding road surface is dry / wet or wet by comparing it with the brightness information of the surrounding road surface detected when the target vehicle is driving.

[0077] For example, the dry / wet light / dark information may be a light / dark determination threshold BRth(n) used to determine whether the surrounding road surface is dry or wet by comparing it with the light / dark information of the surrounding road surface detected when the target vehicle is in motion. Let BRth(n) be the dry / wet light / dark information for the road link n corresponding to point p. This data format is also referred to as data format 2.

[0078] The road surface condition determination device may determine that the road surface at point p is a dry road surface if the point brightness information BR(p) ≥ brightness determination threshold BRth(n), and determine that the road surface at point p is a wet road surface if the point brightness information BR(p) < brightness determination threshold BRth(n).

[0079] Any value can be used for the brightness / darkness determination threshold BRth. Figure 13 shows an example of formulating a brightness / darkness determination threshold based on a frequency distribution curve of location brightness / darkness information.

[0080] For example, the brightness threshold BRth may be the midpoint between the point brightness information BRw, which takes the peak PeakAw of a wet road surface A, and the point brightness information BRd, which takes the peak PeakAd of a dry road surface A. That is, BRth = BR3 = (BRw + BRd) / 2.

[0081] Alternatively, the brightness determination threshold BRth may be set to the point brightness information BR4, which has the lowest frequency between the point brightness information BRw, which takes the peak PeakAw for wet road surface A, and the point brightness information BRd, which takes the peak PeakAd for dry road surface A.

[0082] Alternatively, multiple brightness determination thresholds BRth may be provided depending on the type of in-vehicle device that uses wet / dry brightness information. For example, a location brightness information BR1 whose frequency is a fraction of the location brightness information BRw that takes the peak PeakAw of a wet road surface A, for example PeakAw / 3, may be set as the first brightness determination threshold BRth1, and a location brightness information BR2 whose frequency is for example PeakAw / 10 may be set as the second brightness determination threshold BRth1.

[0083] The first brightness determination threshold BRth1 is a brightness determination threshold for a lighting device that performs anti-glare control for oncoming vehicles or light intensity control to ensure forward visibility for the target vehicle. Since anti-glare control for oncoming vehicles is performed when a certain amount of water film is present on the road surface, the first brightness determination threshold BRth1 may be relatively low.

[0084] The second light / darkness threshold, BRth2, is for a system that prevents the target vehicle from slipping. Since slip prevention control needs to be executed even if the road surface is only slightly wet, a relatively high value is desirable for the second light / darkness threshold, BRth2. That is, BRth1 < BRth2.

[0085] In data format 2, the brightness / darkness determination threshold BRth has the type of the corresponding in-vehicle device as an attribute value.

[0086] The following data format 3 may be used for the dry / wet light / dark information. In data format 3, the dry / wet light / dark information has two light / dark determination thresholds: BRth_d(n) which determines whether the road surface is dry or not for each road link n, and BRth_w(n) which determines whether the road surface is wet or not for each road link n.

[0087] If the location brightness information BR(p) ≥ brightness determination threshold BRth_d(n), the road surface condition determination device determines that the road surface ahead of location p is a dry road surface. In this case, the road surface condition determination device sets the likelihood of the road surface ahead of location p to 1.0 and the likelihood of it being a wet road surface to 0. The likelihood of it being a dry road surface + the likelihood of it being a wet road surface = 1.

[0088] If the brightness determination threshold BRth_d(n) ≥ location brightness information BR(p) > BRth_w(n), the road surface condition determination device cannot determine whether the road surface ahead of location p is dry or wet, and determines the likelihood of it being a dry road surface between 0 and 1.0. The closer location brightness information BR(p) is to BRth_d(n), the greater the likelihood of it being a dry road surface, and the closer location brightness information BR(p) is to BRth_w(n), the smaller the likelihood of it being a dry road surface.

[0089] If the brightness / darkness determination threshold BRth_w(n) > point brightness / darkness information(p), the road surface condition determination device determines that the road surface ahead of point p is a wet road surface. In this case, the road surface condition determination device sets the likelihood of the road surface ahead being a dry road surface to 0 and the likelihood of it being a wet road surface to 1.0.

[0090] The following data format 4 may be used for the dry / wet light / dark information. The dry / wet light / dark information in data format 4 includes information showing the distribution of light / dark information at a specific point or area. The information showing the distribution of light / dark information may be, for example, a coordinate sequence, a piecewise linear function, or a curve function that represents the distribution curve of point light / dark information shown in Figure 13. The road surface condition determination device calculates a light / dark determination threshold from this distribution curve and performs a dry / wet determination of the road surface.

[0091] The coordinate sequence representing the distribution curve of location brightness information is, for example, a sequence of 14 points: 7 points of location brightness information where the frequency peaks on a wet road surface (PeekAw, PeekAw / 2, PeekAw / 4, PeekAw / 8) and 7 points of location brightness information where the frequency peaks on a dry road surface (PeekAd, PeekAd / 2, PeekAd / 4, PeekAd / 8).

[0092] The wet / dry light / dark DB25 may contain wet / dry light / dark information corresponding to the multiple data formats described above and below, as long as they do not contradict each other.

[0093] <A-5. Modified Method Using Weather Information> The wet / dry / dark information generation unit 23 may obtain weather information from an external weather information server of the wet / dry / dry / dark information generation device 201, compare the location P(t) where the location light / dark information transmission device 101 generated location light / dark information with the weather information at P(t), and generate wet / dry / dry / dark information. The weather information includes information on whether or not it is raining and information on the elapsed time since the end of the rain. In this case, the location light / dark information includes the detection time t of the light / dark information on the road surface.

[0094] Figure 14 shows an example of the relationship between the elapsed time since the end of rainfall and the perceived dryness of the road surface estimated by the wet / dry information generation unit 23. During rainfall and until a predetermined time has elapsed from the end of rainfall T0 to time T1, the perceived dryness of the road surface is 0 (the perceived wetness of the road surface is 1). Furthermore, as time elapses from time T1, the perceived dryness of the road surface increases, and for example, at time T1, 24 hours after the end of rainfall T0, the perceived dryness of the road surface becomes 1. Note that T1 may be shorter if the amount of rainfall is small. Also, T2 may be shorter if the road surface is exposed to sunlight for a longer period of time.

[0095] Furthermore, the wet / dry / light / dark information generation unit 23 may acquire road surface construction information, such as permeable asphalt, from a map DB (not shown), and estimate the wet / dry state of the road surface at detection time t based on the drainage capacity of the road surface estimated from the road surface construction information. In other words, the higher the drainage capacity of the road surface, the shorter the time from time T0 to time T1, and the shorter the time from time T1 to time T2.

[0096] The dry / wet light / dark information generation unit 23 may use only the location light / dark information generated at a time corresponding to T0 ≤ t < T1 in Figure 14 and the location light / dark information generated at a time corresponding to t > T2 in order to prepare dry / wet light / dark information when it is not raining. In this case, the dry / wet light / dark DB can be generated based on information of clearly dry road surfaces and clearly wet road surfaces when it is not raining.

[0097] The dry / wet light / dark information generation unit 23 may assign the dryness of the road surface at position p and time Tx as attribute values ​​to the location light / dark information BR(p) as shown in Figure 14, based on the location light / dark information BR(p), position p, generation time Tx acquired from the information storage unit 22, and the relationship between rainfall information at position p and the dryness of the road surface. In this case, the information storage unit 22 stores the dryness of the road surface as an attribute value for each of the location light / dark information in Figure 7.

[0098] Figure 15 shows the relationship between location brightness information and dry road surface characteristics in a specific road link n. The wet / dry brightness information generation unit 23 picks up all data where the location brightness information is BRx in road link n, and sets the average value of the dry road surface characteristics of each data as the dry road surface characteristics x. The wet / dry brightness information generation unit 23 performs this process from BRx = 0 to the maximum value to determine the relationship between location brightness information and dry road surface characteristics. In the example in Figure 15, the dry road surface characteristics of location brightness information less than BR1 are 0, and the dry road surface characteristics of location brightness information BR2 or higher are 1.

[0099] The dry / wet light / dark information in data format 4 includes information indicating the distribution of light / dark information. In addition, the dry / wet light / dark information may also include the likelihood of a dry road surface for each light / dark information. This data format is referred to as data format 5. In this case, shape information indicating the shape of the two curves or straight lines in Figures 13 and 15 is included in the dry / wet light / dark information. The road surface condition determination device can determine the dry / wet state of the road surface according to the amount of precipitation and the elapsed time since the end of rainfall.

[0100] The dry / wet light / dark information generation unit 23 collects puddle conditions in association with weather information, calculates the relationship between precipitation and the time puddles remain after the rainfall ends through statistical processing, and may include the relationship between precipitation and the time puddles remain after the rainfall ends for each area as an attribute value in the dry / wet light / dark information.

[0101] Furthermore, in areas with infrequent rainfall, the wet / dry light / dark information generator 201 may, in conjunction with rainfall information, request the location light / dark information transmitter 101 to transmit location light / dark information for areas where rainfall has occurred, in order to collect information for about one day after the end of rainfall. In this case, the wet / dry light / dark information generator 201 may provide a predetermined incentive to the owner of the location light / dark information transmitter 101 that responds to the transmission request.

[0102] <A-6. Modified form in which location brightness information includes driving lane information as an attribute value> In the location brightness information transmitting device 101, the location brightness information generation unit 14 may include the driving lane information of the probe vehicle as an attribute value in the brightness information when generating the brightness information, and generate location brightness information from multiple brightness information sets where the driving lane is the same. In this case, the driving lane information of the probe vehicle is also included as an attribute value in the location brightness information.

[0103] In the wet / dark / dark information generation device 201, the location light / dark information acquisition unit 21 acquires location light / dark information that includes lane information. The wet / dark / dark information generation unit 23 generates wet / dark / dark information for each lane from multiple location light / dark / dark information having the same location information and the same lane information. The wet / dark / dark / dark DB management unit 24 creates a wet / dark / dark / dark DB 25 using the lane as an attribute value.

[0104] Lanes with a high volume of traffic, or lanes where heavy vehicles such as trucks have priority, tend to have a greater degree of road surface damage, and this damage is affected by the wet / dry condition of the road surface after rainfall. Therefore, by using wet / dry light / dark information corresponding to the lane the target vehicle is traveling in, the road surface condition judgment device can perform a more accurate wet / dry determination. Furthermore, accurate wet / dry determination is possible even when the target vehicle is traveling on a road where the paving time differs for each lane.

[0105] To obtain lane information, the location brightness information transmitting device 101 can, for example, use a high-definition locator (HDL) in the positioning device 13, which has sub-meter-level positioning performance and a high-precision HD map containing road shape information on a lane-by-lane basis, and estimates the lane the probe vehicle is traveling in.

[0106] <A-7. Modified example in which location brightness information includes vehicle type attribute information as an attribute value> In the location brightness information transmitting device 101, the location brightness information generation unit 14 may include the vehicle type attribute information of the probe vehicle generating the brightness information as an attribute value in the brightness information, and generate location brightness information from multiple brightness information sets with the same vehicle type attribute. In this case, the location brightness information also includes the vehicle type attribute information of the probe vehicle as an attribute value. The vehicle type attribute includes, for example, the vehicle type, vehicle name, or model of the probe vehicle.

[0107] In the wet / dark / dark information generation device 201, the location light / dark information acquisition unit 21 acquires location light / dark information including vehicle type attribute information. The wet / dark / dark information generation unit 23 generates wet / dark / dark information for each vehicle type attribute from multiple location light / dark / dark information having the same location information and the same vehicle type attribute. The wet / dark / dark / dark DB management unit 24 creates a wet / dark / dark / dark DB 25 for each vehicle type attribute.

[0108] Each probe vehicle has different vehicle type attributes, resulting in variations in headlight type, installation position, luminous intensity, and hue. Therefore, the road surface condition determination device can achieve more accurate dry / wet determination by using dry / wet light / dark information corresponding to the vehicle type attributes of the target vehicle.

[0109] The vehicle types represented by the vehicle type attribute may include, for example, large buses, minibuses, large trucks, small trucks, regular passenger cars, small passenger cars, and light vehicles. In this case, the amount of information can be reduced compared to when the vehicle type attribute information covers all vehicle types, thus improving the efficiency of acquiring brightness information and reducing the capacity of the dry / wet brightness DB25.

[0110] Furthermore, vehicle attribute information may represent a combination of vehicle type and lighting type. Examples of lighting types include halogen lamps, HID (High-Intensity Discharge) lamps, and LED (Light-Emitting Diode) lamps.

[0111] <A-8. Modified Example in which Location Brightness Information Includes Light Control Information as an Attribute Value> In the Location Brightness Information Transmitting Device 101, the Location Brightness Information Generation Unit 14 may include the light control information of the probe vehicle's lighting device 11 as an attribute value in the brightness information when acquiring the brightness information, and generate location brightness information from multiple brightness information sets with the same light control information. In this case, the location brightness information also includes the light control information as an attribute value. The light control information represents the control state of the lighting device 11. The control state of the lighting device 11 represents, for example, whether it is high beam (headlight), low beam (passing light), mid-high, or other.

[0112] In the wet / dark light information generation device 201, the location light information acquisition unit 21 acquires location light information including lighting control information. The wet / dark light information generation unit 23 generates wet / dark light information for each piece of lighting control information from multiple pieces of location light information having the same location information and the same lighting control information. The wet / dark light DB management unit 24 creates a wet / dark light DB 25 for each piece of lighting control information.

[0113] The brightness or direction of the illumination light differs depending on the control state of the lighting device 11. Therefore, the road surface condition determination device can determine whether the road surface is wet or dry more accurately by using wet / dry light / dark information corresponding to the lighting control state of the target vehicle.

[0114] <A-9. Modifications concerning the generalization of wet / dark information> <A-7> explained that the illumination characteristics of headlights differ depending on the vehicle type (vehicle type, vehicle name, model). The wet / dark information generation unit 23 may set up a virtual lighting device having virtual illumination characteristics and generate wet / dark information for the virtual lighting device. A virtual lighting device is a lighting device installed at a specific location and having a standard luminous intensity distribution of illumination light.

[0115] The wet / dry light / dark information generation unit 23 acquires multiple location light / dark information corresponding to the same vehicle type attribute from the information storage unit 22. The wet / dry light / dark information generation unit 23 then acquires unique illumination characteristic information representing the illumination characteristics unique to that vehicle type attribute, and based on the unique illumination characteristics and virtual illumination characteristics, maps the acquired multiple location light / dark information to virtual location light / dark information, which is location light / dark information acquired when the illumination characteristics at the time of acquisition of the location light / dark information are replaced from unique illumination characteristics to virtual illumination characteristics. The wet / dry light / dark DB management unit 24 creates a wet / dry light / dark DB 25 using the virtual location light / dark information.

[0116] Assuming that the luminous intensity of the intrinsic illumination characteristic is 8000 cd and the luminous intensity of the virtual illumination characteristic is 10000 cd, and that all other characteristics of both are identical, the mapping process will be explained below. In this case, when the intrinsic illumination characteristic is replaced with the virtual illumination characteristic, the luminous intensity becomes 10000 / 8000 times greater. Therefore, the dry / wet brightness information (dry road surface brightness information, wet road surface brightness information) of data format 1 obtained under the intrinsic illumination characteristic is divided by 10000 / 8000 to obtain the dry / wet brightness information obtained using the virtual location brightness information (hereinafter also referred to as virtual dry / wet brightness information).

[0117] In this case, the attribute values ​​of the virtual wet / dry light / dark information may include information indicating that the lighting characteristics were replaced with virtual lighting characteristics to convert the wet / dry light / dark information.

[0118] The road surface condition determination device converts virtual wet / dry brightness information into wet / dry brightness information corresponding to the target vehicle's inherent lighting characteristics, based on the target vehicle's inherent lighting characteristics and virtual lighting characteristics. It then determines the wet / dry state of the surrounding road surface based on this converted wet / dry brightness information.

[0119] According to this method, the wet / dark information generation device 201 does not need to store wet / dark information for each vehicle attribute, and can share location brightness information from probe vehicles with different vehicle attributes. Therefore, the acquisition efficiency of location brightness information in the wet / dark information generation device 201 is improved, and the capacity of the wet / dark DB 25 can be reduced.

[0120] <A-10. Modified form in which location brightness information includes the road surface lighting conditions of oncoming vehicles as an attribute value> The dry / wet brightness information generation unit 23 may generate dry / wet brightness information based only on location brightness information acquired under conditions in which the headlights of oncoming vehicles are not projected onto the road surface in front of the probe vehicle.

[0121] The location brightness information generation unit 14 may determine whether or not the headlights of an oncoming vehicle are shining onto the road surface ahead by performing image recognition on the forward image of the target vehicle acquired from the camera 12, and may include the result of this determination as an attribute value in the location brightness information. Alternatively, the location brightness information transmission unit 15 does not have to transmit the location brightness information to the wet / dry brightness information generation unit 201 if it is determined that the headlights of an oncoming vehicle are shining onto the road surface ahead.

[0122] As a result, the wet / dark information generation unit 23 can generate wet / dark information that is free from noise components caused by the illumination of oncoming vehicles.

[0123] The above considerations concern the headlights of oncoming vehicles, but the same applies to vehicles traveling alongside. That is, the wet / dark information generation unit 23 may generate wet / dark information based only on location light / dark information acquired under conditions where the headlights of the vehicles traveling alongside are not projected onto the road surface in front of the probe vehicle. Alternatively, the wet / dark information generation unit 23 may generate wet / dark information with the condition that there is illumination from the vehicles traveling alongside.

[0124] The road surface condition determination device can more accurately determine whether a surface is dry or wet by using dry / wet light / dark information generated while excluding the influence of headlights from oncoming or parallel vehicles.

[0125] <A-11. Modifications related to wipers> The location brightness information transmitting device 101 may include the wiper control information of the probe vehicle as an attribute value in the location brightness information and transmit it to the wet / dry brightness information generating device 201. The wiper control information represents the operating state of the wipers, such as strong, weak, or off.

[0126] If the wiper control information included in the location brightness information indicates that the wipers were on, it serves as proof that the road surface around the probe vehicle was wet at the time the location brightness information was detected.

[0127] The dry / wet light / dark information generation unit 23 may generate wet road surface light / dark information (hereinafter referred to as wiper-on wet road surface light / dark information) based on a plurality of location light / dark information including wiper control information indicating that the wipers are on, and may also generate wet road surface light / dark information (hereinafter referred to as wiper-off wet road surface light / dark information) based on a plurality of location light / dark information including wiper control information indicating that the wipers are off. In other words, the dry / wet light / dark information generation unit 23 generates three types of dry / wet light / dark information: dry road surface light / dark information, wiper-on wet road surface light / dark information, and wiper-off wet road surface light / dark information.

[0128] The road surface condition determination device can accurately determine whether the road surface is wet or dry by referring to the light / darkness information of a wet road surface with the wipers on when the target vehicle's wipers are on, and by referring to the light / darkness information of a wet road surface with the wipers off when the target vehicle's wipers are off.

[0129] In the example above, wet road surface brightness information was generated separately for wiper on and wiper off states. However, it is also possible to generate even more detailed wet road surface brightness information separately for the strength of the wiper operation when the wiper is on.

[0130] Furthermore, if the wiper control information included in the location brightness information indicates that the wipers are on, it is possible to estimate, in conjunction with the washer fluid spray, that the road surface is dirty or that other vehicles are splashing muddy water.

[0131] <A-12. Modification regarding road surface gradient> In the same road link, under conditions where ambient light is absent, the road surface pavement, road surface damage status, and road surface wet / dry state are identical, and the road gradient is constant, almost identical brightness information is observed. However, at points where the road gradient changes, the brightness information temporarily changes. This phenomenon occurs when the road gradient during the probe vehicle's journey differs from the road gradient at the point illuminated by the probe vehicle's headlights.

[0132] Therefore, the wet / dark information generation unit 23 may designate points or minute areas where the light / dark information changes due to changes in the road gradient within a single road link as singular points, and generate the wet / dark information of these singular points in addition to the wet / dark information for each road link.

[0133] The road surface condition determination device can accurately determine whether a surface is wet or wet even when the road gradient changes, by using both wet / wet / light-contrast information for each road link and wet / wet / light-contrast information for specific locations.

[0134] <B. Embodiment 2> In this embodiment, a lighting noise reduction function will be described, which removes noise caused by lighting other than the headlights of the probe vehicle when the probe vehicle creates location brightness information.

[0135] <B-1. Configuration> The configuration of the location brightness information transmitting device 102 in Embodiment 2 is the same as the configuration of the location brightness information transmitting device 102 in Embodiment 2. However, in the location brightness information transmitting device 102, the lighting device 11 uses an LED lighting device that can control the on / off state of the illumination light with a response speed on the order of microseconds. In addition, in the location brightness information transmitting device 102, the imaging device 12 uses a photodiode (PD) sensor that acquires brightness information of the road surface at a specific position on the road surface ahead, for example, a predetermined range of 35m ahead. The PD sensor can measure brightness information with a response speed on the order of microseconds.

[0136] <B-2. Operation> Figure 16 shows the state in which the road surface 54 ahead is illuminated by LED headlight light 52 from LED headlight 53 and streetlight illumination light 59 from streetlight 62. The LED headlight 53 corresponds to the lighting device 11. The probe vehicle senses the reflected light (arrow 56) from the LED headlight 52 and the reflected light 60 from the streetlight illumination light 59 as brightness information using the PD sensor 61. The PD sensor 61 corresponds to the imaging device 12.

[0137] Even if the amount of reflected light (arrow 56) from the LED headlight 52 is constant, the amount of reflected light 60 from the streetlight 62 59 fluctuates depending on the positional relationship between the streetlight 62 and the probe vehicle, so the brightness information changes.

[0138] In the area of ​​the road surface 54 ahead illuminated by streetlights 59, one endpoint is designated as P1 and the other endpoint as P2. When the probe vehicle's position p is P0 < p ≤ P1, the brightness information is BR; when P1 < p ≤ P2, the brightness information is BRmix; and when p > P2, the brightness information is BRh. Here, BRst = BRmix - BRh represents the influence of the streetlights on the brightness information.

[0139] Figure 18 shows the on / off timing chart of the LED headlight 53. The LED headlight 53 turns on when T0 ≤ t < T1, T2 ≤ t < T3, T4 ≤ t < T5, and T6 ≤ t < T7, and turns off when T1 ≤ t < T2, T3 ≤ t < T4, and T5 ≤ t < T6. Since the continuous off time is 30 ms or less, the driver does not perceive that the LED is off. The LED has a fast response speed, and the illumination light from the LED headlight becomes 0 almost simultaneously with the LED off signal.

[0140] Figure 19 shows the brightness information sensed by the PD sensor 61 when the LED headlight 53 is operating according to the timing chart shown in Figure 18. Here, it is assumed that there is street lighting from T0 ≤ t < T4, meaning the brightness information includes the influence of reflected light from the street lighting, and that there is no street lighting from T4 ≥ t, meaning the brightness information does not include the influence of reflected light from the street lighting.

[0141] For T0 ≤ t < T1 and T2 ≤ t < T3, the brightness information Aon when the LED is on in the absence of streetlights is obtained, and Aon = BRh.

[0142] For T1 ≤ t < T2 and T3 ≤ t < T4, the brightness information Aoff is obtained when the LED is off in the absence of streetlights, and Aoff = 0.

[0143] For T4 ≤ t < T5 and T6 ≤ t < T7, the brightness information Bon when the LED is on, in the case of street lighting, is obtained, and Bon = BRmix.

[0144] For T5 ≤ t < T6, the brightness information Boff is obtained when the LED is off and streetlights are present, and Boff = BRst.

[0145] Here, the difference A in brightness information between the LED on and off when there is no street lighting is A = Aon - Aoff = BRh - 0 = BRh. Also, the difference B in brightness information between the LED on and off when there is street lighting is B = Bon - Boff = BRmix - BRst = BRh.

[0146] In other words, as indicated by A=BRh and B=BRh, by taking the difference between the brightness information when the LED is on and the brightness information when the LED is off, the influence of ambient lighting such as streetlights can be eliminated. This method can eliminate not only the influence of streetlights but also the influence of headlights from oncoming or parallel vehicles.

[0147] The location brightness information generation unit 14 generates location brightness information with the effects of ambient light removed using the method described above. The location brightness information transmission unit 15 transmits the location brightness information, along with information indicating that this method has been adopted, to the wet / dry brightness information generation device 201.

[0148] In the wet / dark light information generation device 201, the wet / dark light information generation unit 23 generates wet / dark light information using multiple location light / dark information created using a method that removes the effects of ambient light. The wet / dark light DB management unit 24 then adds information indicating that a method for removing the effects of ambient light was adopted as an attribute value to the wet / dark light information thus generated, and creates the wet / dark light DB 25.

[0149] This wet / dry light / dark DB25 is effective for road surface condition determination devices that have this LED control function.

[0150] <B-3. Effects> According to this embodiment, when the probe vehicle creates location brightness information, noise caused by ambient lighting other than the probe vehicle's headlights can be removed.

[0151] <C. Embodiment 3> This embodiment describes a road surface condition determination device that determines the dry / wet state of the road surface using a dry / wet light / dark DB.

[0152] <C-1. Configuration> Figure 20 is a block diagram showing the configuration of the road surface condition determination device 301 according to Embodiment 3. The road surface condition determination device 301 is mounted on the target vehicle 1001 and uses the dry / wet light / dark DB 45 to determine the dry / wet state of the road surface in front of the target vehicle 1001. The area of ​​the road surface in front of the target vehicle 1001 where the dry / wet determination is performed is also called the target road surface area.

[0153] The road surface condition determination device 301 is connected to the lighting device 42, imaging device 43, positioning device 44, wet / dry light / dark DB 45, and on-board device 46 mounted on the target vehicle 1001, and is configured to make these available for use.

[0154] The lighting device 42, the imaging device 43, and the positioning device 44 are the same as the lighting device 11, imaging device 12, and positioning device 13 described in Figure 1.

[0155] The wet / dry light / dark DB 45 corresponds, for example, to the wet / dry light / dark DB 25 generated by the wet / dry light / dark information generation device 201 in Embodiment 1. In the wet / dry light / dark DB 45, wet / dry light / dark information is associated with location information or area information. In the example in Figure 20, the wet / dry light / dark DB 45 is installed in the road surface condition determination device 301, but the wet / dry light / dark DB 45 may also be installed on a server or the like, and the wet / dry light / dark information may be downloaded to the road surface condition determination device 301 through communication with the server or the like. In this embodiment, it is assumed that the wet / dry light / dark information is stored in the data format 1 described in Embodiment 1.

[0156] The on-board device 46 controls the control state of the target vehicle 1001 using the results of the road surface condition determination device 301, which determines whether the surrounding road surface is dry or wet. For example, the on-board device 46 is a lighting device.

[0157] The road surface condition determination device 301 is configured to include a location brightness / darkness information generation unit 31, a dry / wet brightness / darkness information acquisition unit 32, and a road surface condition determination unit 33.

[0158] The location brightness information generation unit 31 calculates brightness information of the observation area E of the road surface in front of the target vehicle 1001 from the image captured by the camera 43 when the lighting device 42 is illuminating the road surface in front of the target vehicle 1001, and generates location brightness information by associating the brightness information of the observation area E with location information. Here, the observation area E corresponds to the target road surface area.

[0159] The wet / dark information acquisition unit 32 acquires wet / dark information corresponding to the position of the target vehicle 1001 from the wet / dark light DB 45.

[0160] The road surface condition determination unit 33 compares the location brightness information generated by the location brightness information generation unit 31 with the dry / wet brightness data to determine whether the road surface is dry or wet, and transmits the determination result to the in-vehicle device.

[0161] <C-2. Operation> Figure 21 is a flowchart showing the operation of the road surface condition determination device 301. The operation of the road surface condition determination device 301 will be explained below in accordance with the flow shown in Figure 21.

[0162] Steps S401 to S403 are the same as steps S101 to S103 in Figure 1. In step S401, when the target vehicle 1001 starts moving, the location brightness information generation unit 31 acquires control information for the lighting device 42 and checks whether the headlights, which are the lighting device 42, are turned on or not.

[0163] If the headlights are off in step S401, the road surface condition determination device 301 proceeds to step S408. If the headlights are on in step S401, the road surface condition determination device 301 proceeds to step S402.

[0164] In step S402, the location brightness information generation unit 31 acquires the position P(t) of the target vehicle 1001 from the positioning device 44.

[0165] After step S402, in step S403, the location brightness information generation unit 31 acquires a forward image of the target vehicle 1001 from the imaging device 43, calculates the brightness information of the forward road surface observation area E included in the forward image, and generates location brightness information BR(p) by associating the brightness information with the position information of the observation area E.

[0166] After step S403, in step S404, the wet / darkness information acquisition unit 32 acquires wet / darkness information for the road link n corresponding to position P(t) from the wet / darkness DB 45. In this embodiment, the wet / darkness information is the dry road surface light / darkness information BRd(n) and the wet road surface light / darkness information BRw(n) shown in Figure 12.

[0167] After step S404, in step S405, the road surface condition determination unit 33 sets a brightness determination threshold BRth(n) between the dry road surface brightness information BRd(n) and the wet road surface brightness information BRw(n). For example, the brightness determination threshold BRth(n) is an intermediate value between the dry road surface brightness information BRd(n) and the wet road surface brightness information BRw(n).

[0168] After step S405, in step S406, the road surface condition determination unit 33 compares the location brightness information BR(p) with the brightness determination threshold BRth(n) to determine whether the surface is dry or wet. That is, if BR(p) ≥ BRth(n), the road surface condition determination unit 33 determines that the road surface in observation area E is a dry road surface, and if BR(p) < BRth(n), it determines that the road surface in observation area E is a wet road surface.

[0169] After step S406, in step S407, the road surface condition determination unit 33 transmits the dry / wet determination result of the road surface in observation area E to the on-board device 46.

[0170] The on-board device 46 changes the control parameters of the target vehicle 1001 according to the wet / dry determination result. For example, if the on-board device 46 is a lighting device, the lighting device operates as follows: When the road surface in observation area E is determined to be wet, the lighting device controls the device to increase the luminous intensity (illuminance) of the illumination light reaching the distant road surface in front of the target vehicle 1001 compared to when it is determined to be dry, thereby consuming lighting energy but ensuring forward visibility. The distant road surface is, for example, the road surface that is farther away from the target vehicle 1001 than the observation area E. In addition, if there is an oncoming vehicle, the lighting device controls the device to decrease the luminous intensity (illuminance) of the illumination light illuminating the intermediate area between the oncoming vehicle and the target vehicle 1001 so that the illumination light from the target vehicle 1001 does not reflect off the road surface in the intermediate area between the oncoming vehicle and the target vehicle 1001 and dazzle the driver of the oncoming vehicle.

[0171] When the road on which the target vehicle 1001 is traveling changes from a curve to a straight road, or when there is an obstacle such as a mountain between the target vehicle 1001 and the oncoming vehicle, it becomes possible to perform glare prevention control before the relative positions of the target vehicle 1001 and the oncoming vehicle become such that the road surface reflection from the illumination of the target vehicle 1001's lighting system dazzles the oncoming vehicle.

[0172] In step S408, the road surface condition determination device 301 determines whether or not the target vehicle 1001 has finished driving. If the driving has not finished, the processing of the road surface condition determination device 301 returns to step S401; if the driving has finished, the processing of the road surface condition determination device 301 ends.

[0173] <C-3. Effects> In this embodiment, even when there is no headlight illumination from oncoming vehicles on the road surface surrounding the target vehicle 1001, the dryness / wetness determination of the road surface surrounding the target vehicle 1001 can be accurately performed. As a result, the onboard device of the target vehicle 1001 can appropriately control the target vehicle 1001 based on the dryness / wetness determination of the surrounding road surface.

[0174] <C-4. Modification of the Data Format for Wet / Dry Brightness Information> The Wet / Dry Brightness DB 45 may use data format 2 described in <A-4>. In this case, since the brightness determination threshold BRth(n) already exists in the Wet / Dry Brightness DB 45, the processing in step S405 of Figure 21 is unnecessary.

[0175] Furthermore, if the wet / dry light / dark DB 45 has multiple light / dark determination thresholds BRth depending on the type of in-vehicle device that uses wet / dry light / dark information, the road surface condition determination unit 33 only needs to transmit the light / dark determination threshold BRth corresponding to the type of in-vehicle device 46 to the in-vehicle device 46.

[0176] The dry / wet light / dark DB 45 may use the data format 3 described in <A-4>. In data format 3, the dry / wet light / dark information has two light / dark determination thresholds BRth_d(n) for determining whether the road surface is dry or not for each road link n, and light / dark determination thresholds BRth_w(n) for determining whether the road surface is wet or not for each road link n. In this case, the road surface condition determination unit 33 obtains the dry / wetness determination result as the likelihood of the road surface in the observation area E being dry or wet.

[0177] The dry / wet light / dark DB45 may use the data format 4 described in <A-4>. The dry / wet light / dark information in data format 4 includes information showing the distribution of light / dark information at a specific point or area.

[0178] In this case, the road surface condition determination unit 33 calculates the brightness determination threshold BRth from the distribution of brightness information in step S405 of Figure 21. The calculation method may be, for example, the method described in <A-4>, but is not limited to this.

[0179] The dry / wet light / dark DB45 may use the data format 5 described in <A-4>. The dry / wet light / dark information in data format 5 includes information showing the distribution of location light / dark information and information showing the relationship between location light / dark information and the dryness of the road surface.

[0180] In this case, in step S405 of Figure 21, the road surface condition determination unit 33 calculates a brightness determination threshold BRth from the distribution of location brightness information to determine whether the surface is dry or wet, and also determines whether the road surface is dry based on the location brightness information BR(p) according to the characteristics of Figure 15. The former is referred to as the first determination result, and the latter as the second determination result. The road surface condition determination unit 33 may also use the second determination result as an attribute value of the first determination result.

[0181] The road surface condition determination unit 33 may invalidate the first determination result if the first determination result and the second determination result contradict each other. A contradiction occurs, for example, when the first determination result determines that the road surface is dry, but the second determination result indicates that the likelihood of it being a dry road surface is 0.5 or less. This is a small contradiction, but if the likelihood of it being a dry road surface is less than 0.25 in the second determination result, it may be considered a major contradiction. In other words, contradictions can be categorized into levels, and in-vehicle equipment control can be performed according to the level of contradiction.

[0182] <C-5. Modifications relating to attribute values ​​of wet / dark information> In the wet / dark DB45, the wet / dark information may have attribute values ​​such as driving lane information, vehicle type attribute information, lighting control information, road surface lighting conditions due to oncoming or parallel vehicles, or wiper control information, as described in <A-6>, <A-7>, <A-8>, <A-10>, and <A-11> of Embodiment 1.

[0183] In this case, the road surface condition determination unit 33 calculates the brightness determination threshold BRth using dry / wet brightness information that matches the attributes of the target vehicle 1001.

[0184] <C-6. Modification of attribute values ​​for virtualized dry / wet light / dark information> The dry / wet light / dark DB45 may store the virtual dry / wet light / dark information described in <A-9>.

[0185] In this case, the road surface condition determination unit 33 converts virtual wet / dark information into wet / dark information corresponding to the target vehicle 1001's inherent illumination characteristics, which are the illumination characteristics unique to the target vehicle 1001's lighting device 42, and virtual illumination characteristics of the virtual lighting device, and performs a wet / dark determination of the surrounding road surface based on this converted wet / dark information. If the luminous intensity of the inherent illumination characteristics is 8000 cd and the luminous intensity of the virtual illumination characteristics is 10000 cd, and all other characteristics of both are the same, then the value obtained by multiplying the virtual wet / dark information by (8000 / 10000) becomes the wet / dark information corresponding to the target vehicle 1001's inherent illumination characteristics.

[0186] The road surface condition determination unit 33 determines a light / darkness determination threshold BRth based on the dry / wet light / darkness information corresponding to the unique illumination characteristics of the target vehicle 1001, and performs a dry / wet determination.

[0187] The road surface condition determination device 301 may output the vehicle type attributes of the target vehicle 1001 to the server when acquiring the wet / dark DB 45 from the wet / dark information generation device 201. The wet / dark DB management unit 24 of the wet / dark information generation device 201 may then convert the wet / dark DB 25 compatible with the virtual lighting device into a wet / dark DB 45 corresponding to the vehicle type attributes of the target vehicle 1001 and output it to the road surface condition determination device 301.

[0188] <C-7. Modifications relating to the headlight illumination of oncoming vehicles> In <A-10> of Embodiment 1, it was explained that when an oncoming vehicle projects headlight illumination onto the road surface in front of the probe vehicle, dry / wet light / dark information is not generated.

[0189] The road surface condition determination unit 33 may change the logic for determining whether the road surface is wet or dry in front of the target vehicle 1001 depending on whether or not an oncoming vehicle is shining its headlights onto the road surface in front of the target vehicle 1001.

[0190] If the road surface condition determination unit 33 does not detect headlight illumination on the road surface ahead from an oncoming vehicle, it performs a dry / wet determination using the method described in <C-2>.

[0191] Furthermore, when the road surface condition determination unit 33 detects headlight illumination on the road surface ahead from an oncoming vehicle, it determines whether the road surface is wet or dry based on whether a high-luminance area exists near the midpoint between the target vehicle 1001 and the oncoming vehicle. A high-luminance area is an area where the brightness is higher than other areas, and it is caused by the reflection of the oncoming vehicle's headlights onto the road surface. If a high-luminance area exists, the road surface condition determination unit 33 determines the road surface ahead as wet, and if no high-luminance area exists, it determines the road surface ahead as dry.

[0192] When the light from the headlights reflects off a wet road surface, it creates a pattern called an i-pattern. Therefore, the road surface condition determination unit 33 may determine that the road surface ahead is a wet road surface if it recognizes the i-pattern from the image captured by the camera 43.

[0193] <C-8. Modifications concerning black ice> The road surface condition determination unit 33 may detect not only the dryness or wetness of the road surface ahead, but also other road surface conditions that affect the driving of the target vehicle 1001. An example of a special road surface condition is the phenomenon of black ice caused by the freezing of asphalt. In this case, the road surface becomes much darker than a wet road surface.

[0194] Therefore, if the temperature near the target vehicle 1001 is below freezing point and the road surface in front of the target vehicle 1001 is paved with asphalt, and the light / dark information BR(p) is lower than the wet road surface light / dark information BRw(n) by a predetermined value or more, for example BR(p) < BRw(n) / 2, then it may be determined that black ice has formed on the road surface in front.

[0195] The road surface condition determination unit 33 can acquire temperature information representing the temperature near the target vehicle 1001 from weather information or an outside temperature sensor (not shown) mounted on the target vehicle 1001. The road surface condition determination unit 33 also acquires pavement information representing the pavement type of the road surface area. The road surface condition determination unit 33 can acquire pavement information from road surface construction information included in a map DB (not shown) or by sensing. Based on the pavement information, temperature information, dry / wet / bright information corresponding to the target vehicle's location information, and location brightness / bright information, the road surface condition determination unit 33 performs a freeze determination for the road surface area.

[0196] <C-9. Modifications concerning on-board devices> In Embodiment 3, the on-board device 46 was described as a lighting device. However, the on-board device 46 is not limited to a lighting device, but may also be a driving control device for the target vehicle 1001. The driving control device may be, for example, an anti-skid device, an automatic driving control device, or a notification device. The road surface friction coefficient is lower on wet road surfaces compared to dry road surfaces. Taking this into consideration, the anti-skid device sets different brake control parameters for wet road surfaces and dry road surfaces, respectively.

[0197] When the target vehicle 1001 is traveling on a wet road surface, the automatic driving control system may set a longer distance between the vehicle and the preceding vehicle, or a lower driving speed, compared to when the vehicle is traveling on a dry road surface.

[0198] Furthermore, when road markings such as zebra zones are located on a wet road surface, the coefficient of road friction decreases significantly. Therefore, the automatic driving control system may refer to a map database (not shown) containing the locations of road markings and, if the road markings are located on a wet road surface, perform driving control to prevent slipping at that location.

[0199] If the in-vehicle device 46 is a safety driving notification device, the notification device may notify the driver that the road surface is wet using an LCD instrument panel, road surface illumination display, HUD (Head-Up Display), etc. The notification device should notify the driver that the road surface is wet when the speed of the vehicle 1001 is high. The notification device may also issue a warning when hydroplaning is anticipated.

[0200] <D. Embodiment 4> In Embodiment 3, the dry / wet light / dark DB 45 was provided outside the road surface condition determination device 301. In contrast, in Embodiment 4, the road surface condition determination device has the function of generating the dry / wet light / dark DB 45. That is, the road surface condition determination device according to Embodiment 4 does not require a server and is completed within the target vehicle 1001.

[0201] <D-1. Configuration> Figure 22 is a block diagram showing the configuration of the road surface condition determination device 302 according to Embodiment 4. The road surface condition determination device 302 is mounted on the target vehicle 1001 and is connected to the lighting device 42, imaging device 43, positioning device 44, and on-board device 46, which are also mounted on the target vehicle 1001, and configured to enable their use. The lighting device 42, imaging device 43, positioning device 44, and on-board device 46 are the same as in Embodiment 3.

[0202] The road surface condition determination device 302 includes, in addition to the configuration of the road surface condition determination device 301 according to Embodiment 3, an information storage unit 34, a wet / dry / bright / dark information generation unit 35, and a wet / dry / dry / bright / dark DB 36.

[0203] The information storage unit 34, the wet / dark information generation unit 35, and the wet / dark DB 36 are the same as the information storage unit 22, the wet / dark information generation unit 23, and the wet / dark DB 25 shown in Figure 1. However, the wet / dark information generation unit 35 performs an operation to update the contents of the wet / dark DB 35. This update operation is the same as part of the operation of the wet / dark DB management unit 24 described in Embodiment 1.

[0204] <D-2. Operation> As described in Embodiment 3, the location brightness information generation unit 31 generates location brightness information by associating location information with the brightness information of the observation area E of the road surface in front of the target vehicle 1001. The location brightness information generated by the location brightness information generation unit 31 is output to the road surface condition determination unit 33 and used for determining the dryness or wetness of the road surface corresponding to that location brightness information. In addition, the location brightness information generated by the location brightness information generation unit 31 is stored in the information storage unit 34. In Embodiment 1, the information storage unit 22 stored location brightness information created by multiple probe vehicles, but in this embodiment, the information storage unit 34 stores only location brightness information created by the target vehicle 1001.

[0205] The wet / dark information generation unit 35 generates wet / dark information based on the multiple location light / dark information stored in the information storage unit 34, and generates a wet / dark DB 36 by associating the wet / dark information with location information. These processes are the same as the wet / dark information generation process by the wet / dark information generation unit 23 and the wet / dark DB creation process by the wet / dark DB management unit 24 according to Embodiment 1.

[0206] The wet / dark information acquisition unit 32 acquires wet / dark information corresponding to the location information of the target vehicle 1001 from the wet / dark light DB 36.

[0207] The road surface condition determination unit 33 compares the location brightness information generated by the location brightness information generation unit 31 with the dry / wet brightness information acquired by the dry / wet brightness information acquisition unit 32 to determine the dry / wet condition of the road surface in front of the target vehicle 1001. The dry / wet determination process in this embodiment is the same as in Embodiment 3, except that the source of the dry / wet brightness information is the dry / wet brightness DB 36.

[0208] <D-3. Effects> Since this embodiment does not require a server, the road surface condition determination device 302 can be easily realized in a simple, closed system within the target vehicle 1001. Furthermore, since dry / wet light / dark information is generated based on the point light / dark information of the road surface ahead illuminated by the lighting device 42 of the target vehicle 1001, accurate dry / wet determination is performed. However, there is a limitation that the dry / wet determination of the road surface can only be performed in the area that the target vehicle 1001 has traveled.

[0209] <D-4. Modification> The dry / wet light / dark information of data format 1 includes both dry road surface light / dark information and wet road surface light / dark information. The dry / wet light / dark DB36 may contain only dry road surface light / dark information.

[0210] The wet / dry light / dark information generation unit 35 may generate dry road surface light / dark information only from location light / dark information that can be clearly determined to be a dry road surface, and may generate a wet / dry light / dark DB 36 using wet / dry light / dark information that includes only dry road surface light / dark information. The wet / dry light / dark information generation unit 35 acquires weather forecast information or wiper information of the target vehicle 1001, and based on this information, for example, if several days have passed since the end of rainfall and the wipers are off, it can determine that the location light / dark information generated by the location light / dark information generation unit 31 is light / dark information for a clearly dry road surface.

[0211] While road surface condition determination using the dry / wet light / dark DB36, which contains only dry road surface light / dark information, is less accurate, it can be used in areas with infrequent rainfall.

[0212] The road surface condition determination unit 33 may compare the acquired location brightness information BR(p) with a value obtained by multiplying the dry road surface information BRd(n) at the driving position of the target vehicle 1001 by a coefficient α (<1) to determine whether the road surface is dry or wet. α is, for example, 2 / 3. The road surface condition determination unit 33 determines that the road surface at position p is a dry road surface if BR(p) ≥ α・BRd(n). The road surface condition determination unit 33 also determines that the road surface at position p is a wet road surface if BR(p) < α・BRd(n).

[0213] Alternatively, the road surface condition determination unit 33 may use the location brightness information BR(p) of position p, which it has determined to be a wet road surface, as the wet road surface brightness information BRw(n) of link n, and write the information BRw(n) = BR(p) to the dry / wet brightness DB 36.

[0214] This modification is also applicable to embodiments 1 and 3. The wet / dark information generation device 201 according to embodiment 1 may also generate the wet / dark DB 25 using only dry road surface light / dark information. The wet / dark DB 45 according to embodiment 3 may also be generated using only dry road surface light / dark information.

[0215] <E. Hardware Configuration> The location brightness information generation unit 14 and location brightness information transmission unit 15 in the location brightness information transmission devices 101 and 102 described above, the location brightness information acquisition unit 21, information storage unit 22, dry / wet brightness information generation unit 23, dry / wet brightness DB management unit 24 and dry / wet brightness DB 25 in the dry / wet brightness information generation device 201, and the location brightness information generation unit 31, dry / wet brightness information acquisition unit 32, road surface condition determination unit 33, information storage unit 34, dry / wet brightness information generation unit 35 and dry / wet brightness DB 36 in the road surface condition determination devices 301 and 302 are realized by the processing circuit 81 shown in Figure 23. That is, the processing circuit 81 has each of the above configurations. Dedicated hardware may be applied to the processing circuit 81, or a processor that executes a program stored in memory may be applied. The processor is, for example, a central processing unit, a processing unit, an arithmetic unit, a microprocessor, a microcomputer, a DSP (Digital Signal Processor), etc.

[0216] If the processing circuit 81 is dedicated hardware, it may be, for example, a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC (Application Specific Integrated Circuit), an FPGA (Field-Programmable Gate Array), or a combination thereof. Each function of the location brightness / darkness information generation unit 14, etc., may be implemented by multiple processing circuits 81, or the functions of each part may be implemented together by a single processing circuit.

[0217] When the processing circuit 81 is a processor, the functions of the location brightness information generation unit 14, etc., are realized by a combination of software, firmware, or software and firmware. The software, etc., is written as a program and stored in memory. As shown in Figure 24, the processor 82 applied to the processing circuit 81 realizes the functions of each part by reading and executing the program stored in memory 83. In other words, the location brightness information transmission devices 101, 102, the wet / dry brightness information generation device 201, and the road surface condition determination devices 301, 302 are equipped with memory 83 for storing a program that will result in the execution of each of the above functions when executed by the processing circuit 81. In other words, this program can be said to cause the computer to execute the procedures or methods of the location brightness information generation unit 14, etc. Here, memory 83 may be, for example, non-volatile or volatile semiconductor memory such as RAM (Random Access Memory), ROM (Read Only Memory), flash memory, EPROM (Erasable Programmable Read Only Memory), EEPROM (Electrically Erasable Programmable Read Only Memory), HDD (Hard Disk Drive), magnetic disk, flexible disk, optical disk, compact disk, minidisc, DVD (Digital Versatile Disk) and its drive device, or any storage medium that may be used in the future.

[0218] The above describes a configuration in which each function of the location brightness information generation unit 14, etc., is realized by either hardware or software. However, this is not the only configuration, and some parts of the location brightness information generation unit 14, etc., may be realized by dedicated hardware, and other parts by software, etc. For example, in the dry / wet brightness information generation device 201, the dry / wet brightness information generation unit 23 can be realized by a processing circuit as dedicated hardware, while the other functions can be realized by a processing circuit 81 as a processor 82 that reads and executes a program stored in memory 83.

[0219] As described above, the processing circuit can realize each of the above-mentioned functions through hardware, software, or a combination thereof.

[0220] Furthermore, it is possible to freely combine the embodiments, and to modify or omit them as appropriate. The above description is illustrative in all embodiments. It is understood that countless variations not illustrated are conceivable.

[0221] 11 Lighting device, 12 Imaging device, 13 Positioning device, 14 Location light / dark information generation unit, 15 Location light / dark information transmission unit, 21 Location light / dark information acquisition unit, 22 Information storage unit, 23 Wet / dark light / dark information generation unit, 24 Wet / dark light / dark DB management unit, 25 Wet / dark light / dark DB, 31 Location light / dark information generation unit, 32 Wet / dark light / dark data acquisition unit, 33 Road surface condition determination unit, 34 Information storage unit, 35 Wet / dark light / dark information generation unit, 41 External device, 42 Lighting device, 43 Imaging device, 44 Positioning device, 46 On-board device, 51 Probe vehicle, 54 Forward road surface, 61 PD sensor, 62 Street light, 81 Processing circuit, 82 Processor, 83 Memory, 101 Location light / dark information transmission device, 102 Location light / dark information transmission device, 201 Wet / dry / light information generation device, 301, 302; Road surface condition determination device, 1001; Target vehicle.

Claims

1. A dry and wet light and dark information generating device comprising: a location brightness information acquisition unit that acquires multiple location brightness information, which represents the brightness of a road surface area illuminated by the lighting device of at least one probe vehicle, as detected by at least one probe vehicle, and is linked to location information of the road surface area; a dry and wet light and dark information generation unit that generates dry and wet light and dark information for each road surface area, which serves as a standard for dry and wet determination, based on the multiple location brightness and dark information corresponding to the same road surface area; and a dry and wet light and dark database management unit that creates a dry and wet light and dark database linked to location information of the road surface area, extracts the dry and wet light and dark information from the dry and wet light and dark database and provides it to an external device, wherein the dry and wet light and dark information is used to determine the dry and wet state of the target road surface area by comparing it with brightness information representing the brightness of the target road surface area as seen from the target vehicle, as illuminated by the lighting device of the target vehicle, in an on-board device of the target vehicle, which is an external device or a device connected to the external device.

2. The dry / wet light / dark information generating device according to claim 1, wherein the dry / wet light / dark information generating unit generates dry road surface light / dark information, which is a reference value for determining that the road surface area is a dry road surface in the dry / wet determination, and wet road surface light / dark information, which is a reference value for determining that the road surface area is a wet road surface in the dry / wet determination, by performing statistical processing on a plurality of point light / dark information corresponding to the same road surface area.

3. The dry / wet light / dark information generating device according to claim 1, wherein the dry / wet light / dark information generating unit generates a light / dark determination threshold for determining whether the road surface area is a dry road surface or a wet road surface in the dry / wet determination, based on the frequency distribution of a plurality of light / dark information points corresponding to the same road surface area.

4. The wet / dark information generating device according to claim 3, wherein the wet / dark information generating unit generates the light / dark determination threshold for each type of in-vehicle equipment that utilizes the wet / dark information.

5. The wet / dry light / dry information generating device according to claim 1, wherein the wet / dry light / dry information includes information showing the frequency distribution of multiple locations of light / dry information corresponding to the same road surface area.

6. The dry / wet light / dark information generating device according to claim 1, wherein the location light / dark information includes information on the detection time by the probe vehicle, the dry / wet light / dark information generating unit acquires weather information including the amount of precipitation and the end time of rainfall in the road surface area, estimates the likelihood of the road surface area being dry at the detection time based on the weather information and the detection time, and the dry / wet light / dark database management unit creates the dry / wet light / dark database by associating the likelihood of the road surface being dry with the dry / wet light / dark information.

7. The dry / wet light / dark information generating device according to claim 1, wherein the location light / dark information represents the brightness of each lane within the road surface area, and the dry / wet light / dark information generating unit generates the dry / wet light / dark information for each lane within the road surface area.

8. The wet and dry light information generating device according to claim 1, wherein the location light / dark information includes vehicle type attribute information including the vehicle type of the probe vehicle, or lighting control information representing the control state of the lighting device of the probe vehicle, and the wet and dry light / dark information generating unit generates the wet and dry light / dark information for each of the vehicle type attribute information or the lighting control information.

9. The wet and dry light information generating device according to claim 1, wherein the location light and dark information includes vehicle type attribute information including the vehicle type of the probe vehicle, and unique illumination characteristics information representing the illumination characteristics of a lighting device unique to the vehicle type of the probe vehicle, and the wet and dry light and dark information generating unit converts the location light and dark information into virtual location light and dark information obtained when the probe vehicle illuminates the road surface area with a virtual lighting device having predetermined virtual illumination characteristics based on the unique illumination characteristics information, and generates the wet and dry light and dark information based on the virtual location light and dark information corresponding to the same vehicle type attribute information.

10. The dry / wet light / dark information generating device according to claim 1, wherein the dry / wet light / dark information generating unit generates the dry / wet light / dark information based only on the location light / dark information detected by the probe vehicle when no oncoming vehicle is illuminating the road surface area with its headlights.

11. A location brightness information transmission device comprising: a location brightness information generation unit that detects the brightness of a road surface area illuminated by the lighting device of a probe vehicle in the probe vehicle, and generates location brightness information by linking the detected brightness of the road surface area to location information of the road surface area; and a location brightness information transmission unit that transmits the location brightness information to the wet / dry brightness information generation device described in claim 1, wherein the lighting device repeatedly switches between being off and on for a predetermined time of 30 ms or less; the location brightness information generation unit generates location brightness information with the influence of ambient lighting removed based on the location brightness information when the lighting device is on and the location brightness information when the lighting device is off; and the location brightness information transmission unit transmits the location brightness information with the influence of ambient lighting removed to the wet / dry brightness information generation device.

12. A road surface condition determination device comprising: a location brightness information generation unit that detects the brightness of a road surface area illuminated by the lighting device of the target vehicle in the target vehicle and generates location brightness information by linking the detected brightness of the road surface area to the location information of the road surface area; a dry / wet brightness information acquisition unit that acquires the dry / wet brightness information corresponding to the location information of the target vehicle from a dry / wet brightness database in which dry / wet brightness information that serves as a criterion for determining the dryness or wetness of the road surface area is associated with the location information of the road surface area; and a road surface condition determination unit that compares the location brightness information with the dry / wet brightness information acquired from the dry / wet brightness database to determine the dryness or wetness of the road surface area and transmits the result of the dry / wet determination to the on-board device of the target vehicle.

13. The road surface condition determination unit determines, based on the forward image of the target vehicle, whether the headlights of an oncoming vehicle illuminate the road surface area and whether there is a high-luminance area with a higher brightness than other areas in the road surface area between the target vehicle and the oncoming vehicle; if it determines that the headlights of the oncoming vehicle do not illuminate the road surface area, it compares the location brightness information with the dry / wet brightness information obtained from the dry / wet brightness database to determine the dry / wet condition of the road surface area; if it determines that the headlights of the oncoming vehicle illuminate the road surface area, it determines the road surface area to be a wet road surface if there is a high-luminance area, and determines the road surface area to be a dry road surface if there is no high-luminance area, the road surface condition determination device according to claim 12.

14. The road surface condition determination device according to claim 12, wherein the location brightness information generation unit generates location brightness information by linking the brightness of the road surface area of ​​the target vehicle's driving lane with the location information of the road surface area and the driving lane information, and the road surface condition determination unit obtains the dry / wet brightness information for each lane from the dry / wet brightness database and performs a dry / wet determination of the road surface area of ​​the target vehicle's driving lane by comparing the location brightness information with the dry / wet brightness information corresponding to the same driving lane.

15. The road surface condition determination device according to claim 12, wherein the road surface condition determination unit determines whether the road surface area is frozen based on pavement information relating to the pavement type of the road surface area, temperature information near the target vehicle, dry / wet / bright information corresponding to the location information of the target vehicle, and location brightness / bright information.

16. The road surface condition determination device according to claim 12, wherein the in-vehicle device controls the driving of the target vehicle according to the dry / wet determination result of the road surface area.

17. The road surface condition determination device according to claim 12, wherein the on-board device is a lighting device that controls the lighting of the target vehicle according to the dry / wet determination result of the road surface area.

18. A road surface condition determination device according to claim 12, comprising: an information storage unit for storing location brightness information; a dry / wet brightness information generation unit for creating dry / wet brightness information based on a plurality of location brightness information corresponding to the same road surface area extracted from a plurality of location brightness information stored in the information storage unit; and a dry / wet brightness database management unit for creating a dry / wet brightness database by linking the dry / wet brightness information to location information of the road surface area, wherein the dry / wet brightness information acquisition unit acquires the dry / wet brightness information from the dry / wet brightness database created by the dry / wet brightness database management unit.

19. A road surface condition determination method comprising: a location brightness information generation unit detects the brightness of a road surface area illuminated by the vehicle's lighting device in the target vehicle; the location brightness information generation unit generates location brightness information by linking the detected brightness of the road surface area to the location information of the road surface area; a wet / dry brightness information acquisition unit acquires the wet / dry brightness information corresponding to the location information of the target vehicle from a wet / dry brightness database, which is linked to the location information of the road surface area and serves as a criterion for determining the wet / dry state of the road surface area; and a road surface condition determination unit compares the location brightness information with the wet / dry brightness information acquired from the wet / dry brightness database to determine the wet / dry state of the road surface area and transmits the result of the wet / dry determination to the on-board device of the target vehicle.

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