Driving assistance device

Abstract

The purpose of the present disclosure is to provide a driving assistance device capable of providing more appropriate driving assistance. A driving assistance device according to the present disclosure is provided with: an insufficiently illuminated area determination unit that determines the existence of an insufficiently illuminated area in front of a host vehicle, where illumination by the headlights of the host vehicle is insufficient, on the basis of at least gradient information of the road on which the host vehicle is traveling and the installation height of the headlights of the host vehicle, or on the basis of camera information obtained by capturing an image of the area in front of the host vehicle; and a notification drive unit that, if the insufficiently illuminated area determination unit determines that an insufficiently illuminated area exists when the headlights are on, drives a notification device for executing a notification display to visually notify the driver of the host vehicle of the existence of the insufficiently illuminated area. The notification drive unit drives a virtual image generation device that is the notification device, or drives a road surface drawing device that is the notification device.

Description

Driving assistance devices

[0001] The present disclosure relates to a driving assistance device that notifies a driver that there is an area in front of a vehicle where headlight illumination is insufficient.

[0002] Conventionally, a technology has been disclosed for providing driving assistance in which, based on the driver's eye position and changes in the gradient of the road ahead, it is determined whether or not there is an area ahead that the driver cannot see, and if it is determined that an area that cannot be seen exists, the driver is visually notified of the existence of the area that cannot be seen using a virtual image generating device or an illumination device (see, for example, Patent Documents 1 and 2).

[0003] Japanese Patent No. 7052786 Japanese Patent Application Laid-Open No. 2020-24696

[0004] When driving in a dark environment, such as at night, the headlights are turned on to illuminate the road surface ahead of the vehicle. The installation height of the headlights (the height from the road surface at which the headlights are installed) is lower than the driver's eye height. Therefore, even if the area ahead of the road is visible to the driver in a bright environment, when driving with the headlights on, the headlights may not illuminate the area sufficiently, making it difficult for the driver to recognize it. Notifying the driver of the existence of such an area with insufficient headlight illumination is useful for providing driving assistance to the driver.

[0005] In the past, the presence of an area that the driver cannot see was notified, but the presence of an area where the headlights are insufficiently illuminated was not. Thus, there is room for improvement in the driving assistance provided to the driver.

[0006] The present disclosure has been made to solve such problems, and aims to provide a driving assistance device that can provide more appropriate driving assistance.

[0007] In order to solve the above problems, the driving assistance device according to the present disclosure includes an insufficiently illuminated area determination unit that determines the presence of an insufficiently illuminated area in front of the vehicle, where the headlights are insufficiently illuminated, based on at least gradient information of the road on which the vehicle is traveling and the installation height of the headlights of the vehicle, or based on camera information capturing an image of the area in front of the vehicle, and a notification drive unit that drives a notification device that executes a notification display to visually notify the driver of the vehicle of the presence of an insufficiently illuminated area when the insufficiently illuminated area determination unit determines that an insufficiently illuminated area exists when the headlights are on, and the notification drive unit drives a virtual image generation device that is the notification device, or drives a road surface drawing device that is also the notification device.

[0008] According to the present disclosure, it is possible to provide more appropriate driving assistance.

[0009] The objects, features, aspects, and advantages of the present disclosure will become more apparent from the following detailed description and the accompanying drawings.

[0010] 1-1 is a block diagram showing an example of the configuration of a driving assistance device according to embodiment 1. FIG. 1-1 is a block diagram showing an example of the configuration of a driving assistance device according to embodiment 1. FIG. 1-2 is a diagram for explaining driving assistance according to a prerequisite technology. FIG. 1-3 is a diagram for explaining driving assistance according to embodiment 1. FIG. 1-4 is a diagram for explaining driving assistance according to embodiment 1. FIG. 1-5 is a diagram for explaining driving assistance according to embodiment 1. FIG. 1-6 is a diagram for explaining driving assistance according to embodiment 1. FIG. 1-7 is a diagram for explaining an example of a notification display due to driving assistance according to the prerequisite technology. FIG. 1-8 is a diagram for explaining an example of a notification display due to driving assistance according to embodiment 1. FIG. 1-9 is a diagram for explaining an example of a notification display due to driving assistance according to embodiment 1. FIG. 1-10 is a diagram for explaining an example of a notification display due to driving assistance according to embodiment 1. FIG. 1 is a diagram for explaining lighting by a driving assistance device according to Modification 1-2. FIG. 2 is a diagram illustrating an example of a notification display by a driving assistance device according to Modification 1-3. FIG. 3 is a diagram illustrating an example of a notification display by a driving assistance device according to Modification 1-3. FIG. 4 is a diagram illustrating an example of a notification display by a driving assistance device according to Modification 1-3. FIG. 5 is a diagram illustrating an example of a notification display by a driving assistance device according to Modification 1-4. FIG. 6 is a diagram illustrating an example of a notification display by a driving assistance device according to Modification 1-4. FIG. 7 is a diagram illustrating an example of a notification display by a driving assistance device according to Modification 1-4. FIG. 8 is a diagram illustrating an example of a notification display by a driving assistance device according to Modification 1-4.FIG. 1 is a diagram showing an example of a notification display by a driving assistance device according to Modification 1-4. FIG. 2 is a diagram showing an example of a notification display by a driving assistance device according to Modification 1-4. FIG. 3 is a diagram showing an example of a notification display by a driving assistance device according to Modification 1-4. FIG. 4 is a diagram showing an example of a notification display by a driving assistance device according to Modification 1-4. FIG. 5 is a diagram for explaining a notification display by a driving assistance device according to Modification 1-5. FIG. 6 is a diagram for explaining a notification display by a driving assistance device according to Modification 1-6. FIG. 7 is a diagram for explaining a notification display by a driving assistance device according to Modification 1-6. FIG. 8 is a diagram showing an example of a notification display by a driving assistance device according to Modification 1-8. FIG. 9 is a diagram showing an example of a notification display by a driving assistance device according to Modification 1-8. FIG. 10 is a diagram showing an example of a notification display by a driving assistance device according to Modification 1-9. FIG. 11 is a diagram showing an example of a notification display by a driving assistance device according to Modification 1-9. FIG. 12 is a diagram showing an example of a notification display by a driving assistance device according to Modification 1-9. 1-10 is a flowchart showing an example of the operation of a driving assistance device according to Modification 1-10. FIG. 1-10 is a block diagram showing an example of the configuration of a driving assistance device according to Embodiment 2. FIG. 1-2 is a flowchart showing an example of the operation of a driving assistance device according to Embodiment 2. FIG. 1-3 is a diagram showing an example of the detection of an insufficiently illuminated area by a driving assistance device according to Embodiment 2. FIG. 1-4 is a diagram showing an example of the detection of an insufficiently illuminated area by a driving assistance device according to Embodiment 2. FIG. 1-5 is a block diagram showing an example of the configuration of a driving assistance device according to Modification 2-1. FIG. 1-6 is a diagram showing a change in the length of road surface illumination by headlights according to Modification 2-1. FIG. 1-7 is a diagram showing an example of road surface illumination by headlights according to Modification 2-1. FIG. 1-8 is a diagram showing an example of road surface illumination by headlights according to Modification 2-1. FIG. 1-9 is a diagram showing an example of road surface illumination by headlights according to Modification 2-1. FIG. 1-10 is a flowchart showing an example of the operation of a driving assistance device according to Modification 2-1. FIG. 1-11 is a diagram showing an example of the operation of a driving assistance device according to Modification 2-1.1 is a block diagram showing an example of a hardware configuration of a driving assistance device according to Embodiments 1 and 2. FIG. 2 is a block diagram showing an example of a hardware configuration of a driving assistance device according to Embodiments 1 and 2. FIG.

[0011] 1 is a block diagram showing an example of the configuration of a driving assistance device 1 according to embodiment 1. The driving assistance device 1 includes an insufficiently illuminated area determination unit 2 and a notification drive unit 3.

[0012] The insufficiently illuminated area determination unit 2 determines the presence of an insufficiently illuminated area in front of the vehicle based on at least gradient information of the road on which the vehicle is traveling and the installation height of the headlights of the vehicle, or based on camera information capturing an image of the area in front of the vehicle. The details of the insufficiently illuminated area will be described later.

[0013] When the insufficiently illuminated area determination unit 2 determines that an insufficiently illuminated area exists while the headlights are on, the notification drive unit 3 drives the notification device 11 (see Figure 2) that executes a notification display to visually notify the driver of the vehicle of the existence of an insufficiently illuminated area.

[0014] Next, other configurations including the driving assistance device 1 shown in FIG. 1 will be described.

[0015] 2 is a block diagram showing an example of the configuration of a driving assistance device 4 according to another embodiment. The driving assistance device 4 includes a vehicle information acquisition unit 5, a map information acquisition unit 6, an insufficiently illuminated area determination unit 2, a notification drive unit 3, and a lighting drive unit 7. The driving assistance device 4 is also connected to a vehicle information detection device 8, a map database 9, a positioning device 10, a notification device 11, and a headlight 14.

[0016] The vehicle information detection device 8 acquires, as vehicle information, the installation height of the headlights 14 and information relating to whether the headlights 14 are on or off. The vehicle information detection device 8 acquires the installation height of the headlights 14 directly from a storage device (not shown) provided in the host vehicle or via an in-vehicle LAN. Note that, as described below, the vehicle information detection device 8 may also detect the driver's standard eye height taking into account the structure of the host vehicle, the driver's specific eye height detected by a driver monitoring system (DMS), the driver's forward gaze information detected by the DMS, and vehicle speed information of the host vehicle.

[0017] The vehicle information acquisition unit 5 acquires vehicle information from the vehicle information detection device 8 .

[0018] The positioning device 10 measures the position of the vehicle using a Global Navigation Satellite System (GNSS).

[0019] The map database 9 stores map data relating to the three-dimensional shapes of roads. The map database 9 may store map data in any data format that can represent the three-dimensional shapes of roads, such as a coordinate sequence (x: latitude, y: longitude, z: height) of links and shape interpolation points within the links, or a two-dimensional coordinate and gradient information sequence (x: latitude, y: longitude, α: gradient). The map database 9 may also store data such as the positions of features, intersections, pedestrian crossings, and bus stops.

[0020] The map information acquisition unit 6 acquires the vehicle position from the positioning device 10. Then, the map information acquisition unit 6 acquires map data of the surroundings of the vehicle from the map database 9 according to the vehicle position acquired from the positioning device 10.

[0021] The insufficiently illuminated area determination unit 2 determines the presence of an insufficiently illuminated area based on gradient information of the road on which the vehicle is traveling, acquired by the map information acquisition unit 6, and the installation height of the headlights 14, acquired by the vehicle information acquisition unit 5. An insufficiently illuminated area is an area where the illumination from the headlights 14 does not sufficiently reach the road ahead. Note that the insufficiently illuminated area includes an area where the illumination from the headlights 14 does not reach at all, and an area where the illumination from the headlights 14 reaches but the illuminance is insufficient (below a predetermined illuminance).

[0022] When the insufficiently lit area determination unit 2 determines that an insufficiently lit area exists on the road ahead, the notification drive unit 3 drives the notification device 11 that executes a notification display to visually notify the driver of the vehicle of the existence of the insufficiently lit area.

[0023] The lighting driver 7 controls the lighting direction and position of the road surface drawing device 13 or the headlights 14 based on instructions from the notification driver 3, and instructs them to illuminate insufficiently illuminated areas. Note that the control of the lighting direction and position is not limited to a mechanical optical axis adjustment method, and any method may be used, such as a method of controlling the lighting direction and position using a projection method without a mechanical driver, or a method of switching multiple lighting elements according to the direction and position.

[0024] The notification device 11 includes a virtual image generating device 12 and a road surface drawing device 13. When an insufficiently illuminated area exists, the notification device 11 executes a notification display to visually notify the driver of the existence of the insufficiently illuminated area. The virtual image generating device 12 and the road surface drawing device 13 may be used independently or in conjunction with each other.

[0025] The virtual image generating device 12 is a HUD (Head Up Display) that displays a superimposed image on the view ahead of the vehicle. The road surface drawing device 13 draws the road surface by lighting or provides supplementary lighting to areas with insufficient lighting. The road surface drawing device 13 has means for controlling the lighting direction and position in accordance with instructions from the lighting driving unit 7.

[0026] The headlamp 14 has an optical axis adjusting device that adjusts the optical axis in accordance with an instruction from the lighting driving unit 7 .

[0027] <Driving assistance according to the premise technology and driving assistance according to embodiment 1> Figure 3 is a diagram for explaining driving assistance according to the premise technology of the present disclosure. In Figure 3, the vehicle 15 is traveling from a first road surface toward a second road surface. Note that the driving assistance according to the premise technology corresponds to the driving assistance according to the conventional technology described above (driving assistance using the driver's eye level). The triangle shown in Figure 3 indicates the position of the notification display.

[0028] The transition point is a point where the gradient of the first road surface changes to the gradient of the second road surface. In Fig. 3, the gradient transition angle between the first road surface and the second road surface is θ, and the eye height of the driver of the vehicle 15 as seen from the road surface is H1. In the example of Fig. 3, the first road surface and the second road surface are an uphill slope and a horizontal surface, respectively, but the relationship between the first road surface and the second road surface is not limited to this, and in any case, the gradient transition angle θ and the eye height H1 of the driver are defined in the same way. However, it is assumed that θ>0 as seen from the first road surface.

[0029] 3, if there is no change point within a distance B1 defined by B1 = H1 / tan(θ) from the host vehicle 15 (when the host vehicle 15 is traveling in the first area), the driver cannot see the second road surface because the change point blocks the driver's view. If there is a change point within a distance B1 from the host vehicle 15 (when the host vehicle is traveling in the second area), the driver can see the second road surface. For example, if H1 = 1 m and the gradient change angle θ is approximately 1°, B1, the starting point of the second area, is approximately 60 m.

[0030] Therefore, in the driving assistance according to the base technology, it is effective to display a warning of the presence of an invisible second road surface while the host vehicle 15 is traveling in the first area. The timing to start the warning display may be, for example, the timing when the presence of a change point within a distance B0 from the host vehicle 15 is detected. B0 can be set to a distance that allows safe risk avoidance depending on the vehicle speed and driver characteristics. For example, when traveling at 100 km / h, taking into account the risk avoidance time of 3 seconds, B0 is approximately 80 m. The warning display is then terminated when the host vehicle 15 reaches B1 and enters the second area.

[0031] Fig. 4 is a diagram for explaining driving assistance according to embodiment 1. In Fig. 4, the host vehicle 15 is traveling from a first road surface to a second road surface with the headlights 14 on, such as at night. The triangles shown in Fig. 4 indicate the positions of the notification displays.

[0032] In Fig. 4, the installation height of the headlamp 14 as seen from the road surface is designated as H2. Generally, H2 is lower than the driver's eye height H1. The second and third areas in Fig. 4 correspond to the second area in Fig. 3.

[0033] When the host vehicle 15 is traveling through the first and second areas, the illumination from the headlights 14 is blocked at the transition point and does not reach the second road surface (the second road surface cannot be sufficiently illuminated). Then, when the host vehicle 15 enters the third area, where the starting point B2 is defined by B2 = H2 / tan(θ), the illumination from the headlights 14 reaches the second road surface, and the driver gradually becomes able to see the second road surface as the host vehicle 15 approaches the transition point. Thus, when the headlights 14 are on, a warning is displayed indicating the presence of an insufficiently illuminated area when the host vehicle 15 is traveling through the first and second areas. In particular, when the host vehicle 15 is traveling through the second area, the driver can see the second road surface when the headlights 14 are off in bright surroundings, such as during the day (see FIG. 3 ). However, when the headlights 14 are on in dark surroundings, such as at night, the illumination from the headlights 14 does not reach the second road surface, making it difficult for the driver to see the second road surface. Therefore, it is effective to notify the driver of the presence of an insufficiently illuminated area when the vehicle 15 is traveling through the second area with the headlights 14 turned on.

[0034] In the example of Figure 4, the first road surface and the second road surface are an uphill road surface and a horizontal road surface, respectively, but the relationship between the first road surface and the second road surface is not limited to this. In any case, the gradient change angle θ, the driver's eye height H1, and the headlamp installation height H2 are defined in the same way. For example, if H1 = 1 m and H2 = 0.5 m, and the gradient change angle θ is approximately 1°, B1, which is the starting point of the second area, is approximately 60 m, and B2, which is the starting point of the third area, is approximately 30 m. As the gradient change angle θ increases, the vehicle 15 must approach the change point before the second road surface can be illuminated.

[0035] Figure 5 is a diagram for explaining driving assistance according to embodiment 1, showing the timing of notification displays when the vehicle 15 is traveling through each of the first area, second area, and third area.

[0036] When the vehicle 15 is traveling in the first area, the illumination from the headlights 14 does not reach the second road surface, so the driver cannot see the second road surface. In this case, a warning message indicating the presence of an insufficiently illuminated area is displayed. The warning message is initiated when a change point is detected within a distance B0 from the vehicle 15. If the gradient change angle θ is small, points B1 and B2 are farther from the change point B0, whereas if the gradient change angle θ is large, points B1 and B2 are farther from the change point B0. Therefore, depending on the gradient change angle θ, the vehicle 15 may be in the first area, but if the gradient change angle θ is gentler, the warning message may be initiated when the vehicle 15 is in the second area. In the example of FIG. 5 , the warning message is initiated when a change point is detected within a distance B0 from the vehicle 15 while the vehicle 15 is traveling in the first area.

[0037] When the vehicle 15 is traveling in the second area, the illumination from the headlights 14 does not sufficiently reach the second road surface (due to insufficient illumination from the headlights 14), making it difficult for the driver to see the second road surface. In this case, the presence of an insufficiently illuminated area is notified and displayed.

[0038] When the vehicle 15 is traveling in the third area, the illumination from the headlights 14 reaches the second road surface, allowing the driver to see the second road surface. In this case, the notification display of the presence of an insufficiently illuminated area is terminated. The timing for terminating the notification display is, for example, when the vehicle 15 enters the third area.

[0039] Here, a comparison will be made between the notification display by the driving assistance according to the base technology and the notification display by the driving assistance according to the first embodiment. Here, the explanation will be given assuming that the headlights are on and the notification display is executed by the HUD. The HUD display is useful in the daytime when the surroundings are bright, and can naturally also be used at night.

[0040] 6 to 8 are diagrams showing examples of notification displays based on driving assistance according to the underlying technology. Note that the underlying technology is assumed to operate during the daytime. Figures 6 to 8 explain an example in which the underlying technology operates at night.

[0041] As shown in FIG. 6, when the vehicle 15 is traveling in the first area, a notification display is executed by the HUD.

[0042] As shown in Figure 7, when the vehicle 15 is traveling in the second area, the second road surface is not illuminated and is therefore difficult to see, but the driver is determined to be in a position where he or she can see the second road surface, and so the notification display is not executed.

[0043] As shown in FIG. 8, when the vehicle 15 is traveling in the third area, it is determined that the driver is positioned so that the second road surface can be seen, and no notification display is executed.

[0044] 9 to 11 are diagrams showing examples of notification displays by driving assistance according to embodiment 1. The operation is assumed to be performed at night.

[0045] As shown in Fig. 9, when the host vehicle 15 is traveling in the first area, a notification display is executed by the HUD. The notification display is displayed a predetermined distance in front of the change point. This distance may be increased as the distance between the host vehicle 15 and the change point increases or as the host vehicle speed increases. Alternatively, the notification display may be at the position of the change point as shown in Fig. 6.

[0046] As shown in Figure 10, when the vehicle 15 is traveling in the second area, it is determined that the headlights 14 are not illuminating the second road surface (the second road surface is difficult to see because no illumination reaches it), and a warning display is executed.

[0047] As shown in Figure 11, when the vehicle 15 is traveling in the third area, the headlights 14 illuminate the second road surface, so it is determined that the driver can see the second road surface and no warning display is executed.

[0048] <Operation> FIG. 12 is a flowchart showing an example of the operation of the driving assistance device 4 according to the first embodiment.

[0049] In step S101 , the vehicle information acquisition unit 5 acquires the installation height of the headlights 14 from the vehicle information detection device 8 .

[0050] In step S102, the vehicle information acquisition unit 5 acquires information about whether the headlights 14 are on or off from the vehicle information detection device 8, and determines whether the headlights 14 are on. If the headlights 14 are on, the process proceeds to step S103. On the other hand, if the headlights 14 are not on, the process proceeds to step S109.

[0051] In step S103 , the map information acquisition unit 6 acquires the vehicle position from the positioning device 10 .

[0052] In step S104 , the map information acquisition unit 6 acquires map data of the area ahead of the vehicle 15 from the map database 9 .

[0053] In step S105, the insufficiently illuminated area determination unit 2 determines whether a change point exists within a predetermined distance B0 ahead of the vehicle 15. Distance B0 corresponds to distance B0 shown in FIG. 4. If a change point exists within distance B0, the process proceeds to step S106. In this case, the vehicle 15 is traveling in either area 1, area 2, or area 3 shown in FIG. 4. On the other hand, if a change point does not exist within distance B0, the process proceeds to step S110.

[0054] In step S106, the insufficiently illuminated area determination unit 2 determines whether or not an insufficiently illuminated area exists ahead of the vehicle 15. If an insufficiently illuminated area exists, the process proceeds to step S107. In this case, the vehicle 15 is traveling in the first area or the second area. On the other hand, if an insufficiently illuminated area does not exist, the process proceeds to step S109. In this case, the vehicle 15 is traveling in the third area.

[0055] In step S107, the insufficiently illuminated region determination unit 2 determines the position of the notification display based on the change point, which is closer to the vehicle 15 than the change point (see, for example, FIGS. 9 and 10).

[0056] In step S108, the notification drive unit 3 drives the virtual image generation device 12 to superimpose an object of a predetermined display mode on the position of the notification display. The virtual image generation device 12 displays the generated object on the position of the notification display. In this way, the virtual image generation device 12 displays the notification to visually notify the driver of the vehicle 15 of the presence of an insufficiently illuminated area.

[0057] The notification display may be, for example, as shown in FIGS. 9 and 10, but is not limited to this.

[0058] When the road surface drawing device 13 is used to display the notification, a road surface similar to the object shown in FIGS. 9 and 10 may be drawn at the position where the notification is to be displayed.

[0059] In step S109, the notification drive unit 3 controls the notification device 11 to end the notification display.

[0060] In step S110, the driving assistance device 4 determines whether the vehicle 15 has finished traveling. If the vehicle 15 has finished traveling, the operation of FIG. 12 ends. On the other hand, if the vehicle 15 has not finished traveling, the operation returns to step S102. For simplicity, the operation has been described using the transition point as the junction between a first road surface having a linear slope and a second road surface having a linear slope. However, since roads generally have curved slopes, if the point at which the road ahead becomes visible is defined as the first transition point, the position of the first transition point determined at a specific point changes as the vehicle approaches the first transition point. Similarly, if the point at which the road ahead becomes illuminable is defined as the second transition point, the position of the second transition point determined at a specific point changes as the vehicle approaches the second transition point. Furthermore, the first transition point and the second transition point are not necessarily the same. Therefore, the first, second, and third areas may be determined based on road slope shape information and the vehicle position.

[0061] <Effects> According to the first embodiment, when the headlights 14 are on, the presence of an insufficiently illuminated area where the illumination of the headlights 14 is insufficient is determined, rather than determining the presence of an area that is positionally invisible to the driver, and if an insufficiently illuminated area exists, the driver is notified of this. This makes it possible to provide more appropriate driving assistance, contributing to safer driving.

[0062] Furthermore, the driving assistance device 4 can be realized using an existing map database and positioning device, so there is no need to develop or install new devices, and it can be realized relatively inexpensively.

[0063] <Modification 1-1> In Modification 1-1, a case where a driver monitoring system (DMS) mounted on the host vehicle 15 is used will be described.

[0064] The vehicle information acquisition unit 5 acquires from the DMS the relative position of the driver's eyes as seen from the DMS camera and the installation position of the DMS camera, and calculates the height H1 of the driver's eyes as seen from the road surface (see FIG. 4). The first area and the second area can be determined based on the calculated driver's eye height H1. The third area can be determined from the installation height of the headlights 14, as described in the first embodiment. The gradient information of each of the first and second road surfaces is acquired by the map information acquisition unit 6, as in the first embodiment.

[0065] Since the installation position of the DMS camera is vehicle-specific and known, the position of the driver's eyes can be determined from the relative positional relationship between the DMS camera and the position of the driver's eyes. The position of the driver's eyes can be determined by any method. For example, if the DMS camera is a monocular camera, the direction of the driver's eyes can be detected from the monocular camera's shooting angle and the captured position of the driver's eyes, and the relative positional relationship between the monocular camera and the driver's eyes can be determined based on the apparent distance between the driver's eyes and the binocular distance of a standard person. Alternatively, instead of the binocular distance of a standard person, the distance between the driver's eyes can be input from an input device (not shown). The relative positional relationship between the binocular camera and the driver's eyes can be determined by image ranging using the binocular camera. Alternatively, the relative positional relationship between the monocular camera and the driver's eyes can be determined by combining the monocular camera with a Time of Flight (ToF) sensor.

[0066] Instead of the DMS, the vehicle information acquisition unit 5 may acquire the eye height of a driver with a standard build when seated.

[0067] For example, when the vehicle 15 is traveling uphill, in order to increase the accuracy of the timing of the appearance of an insufficiently illuminated area beyond the change point at the top, the insufficiently illuminated area determination unit 2 classifies the area into a first area where the driver cannot see the area and where the illumination of the headlights 14 is insufficient, a second area where the driver can see the area but where the illumination of the headlights 14 is insufficient, and a third area where the driver can see the area but where the illumination of the headlights 14 is insufficient. The notification drive unit 3 then drives the notification device 11 to display a notification at least when the vehicle 15 is traveling in the second area. For example, as shown in FIGS. 9 and 10 , the notification may be displayed by superimposing an object on the notification display using the virtual image generation device 12. Furthermore, the display mode of the notification display for the first area may be different from the display mode of the notification display for the second area. This makes it possible to determine whether the driver is traveling in the first area or the second area.

[0068] Figure 13 is a flowchart showing an example of the operation of the driving assistance device 4 according to Modification 1-1. Note that steps S201 to S206, step S213, and step S214 in Figure 13 are similar to steps S101 to S106, step S109, and step S110 in Figure 12, and therefore will not be described here. Steps S207 to S212 will be described below.

[0069] In step S207, the vehicle information acquisition unit 5 acquires from the DMS the relative position of the driver's eyes as seen from the DMS camera and the installation position of the DMS camera, and calculates the height H1 of the driver's eyes as seen from the road surface.

[0070] In step S208, the insufficiently illuminated area determination unit 2 determines whether the vehicle 15 is located in the first area or the second area. If the vehicle 15 is located in the first area, the process proceeds to step S209. On the other hand, if the vehicle 15 is located in the second area, the process proceeds to step S211.

[0071] In step S209, the insufficiently illuminated region determining unit 2 determines the position of the notification display based on the change point.

[0072] In step S210, the notification driver 3 drives the virtual image generator 12 to superimpose an object in a predetermined display mode on the notification display position. The virtual image generator 12 displays the notification so that the generated object is superimposed on the notification display position. In this manner, the virtual image generator 12 executes the notification display for the first area (see, for example, FIG. 14 ).

[0073] In step S211, the insufficiently illuminated region determining unit 2 determines the position of the notification display based on the change point.

[0074] In step S212, the notification driver 3 drives the virtual image generator 12 to superimpose an object in a predetermined display mode on the notification display position. The virtual image generator 12 displays the notification so that the generated object is superimposed on the notification display position. In this manner, the virtual image generator 12 executes the notification display for the second area (see, for example, FIGS. 15 and 16 ).

[0075] As described above, according to the modified example 1-1, the driver-specific insufficient lighting area, i.e., the driver-specific second area, is detected, and therefore the notification display can be performed at the optimal timing. This is particularly effective for drivers whose seat height is significantly different from the standard value.

[0076] Although the case of determining the eye position of the driver has been described in Modification 1-1, the eye height estimated from a standard physique may be used instead, in which case the DMS device is not required.

[0077] <Modification 1-2> In Modification 1-2, a case will be described in which the optical axis of at least one of the road surface drawing device 13 and the headlight 14 is adjusted to illuminate the insufficiently illuminated area.

[0078] 17 to 19 are diagrams for explaining illumination by a driving assistance device according to Modification 1-2.

[0079] As shown in Figure 17, before the vehicle 15 reaches the third area (i.e., while traveling through the first and second areas), the headlights 14 cannot illuminate the second road surface, so a warning is displayed by the warning device 11.

[0080] As shown in FIG. 18, when the vehicle 15 reaches the third area, the notification display is terminated.

[0081] As shown in Figure 19, when the vehicle 15 enters the third area, the illumination from the headlights 14 begins to reach the second road surface, but the second road surface is still dark (an insufficiently illuminated area exists on the second road surface). At this time, the illumination drive unit 7 instructs the road surface drawing device 13 to adjust the optical axis to illuminate the insufficiently illuminated area (supplementary illumination) based on an instruction from the notification drive unit 3. In the example of Figure 19, the optical axis of the road surface drawing device 13 is adjusted downward, and the illumination from the headlights 14 and the illumination from the road surface drawing device 13 overlap to illuminate the insufficiently illuminated area. The optical axis of the road surface drawing device 13 may be adjusted based on gradient information of the second road surface.

[0082] Thereafter, when the illumination by the road surface drawing device 13 is finished, the optical axis of the road surface drawing device 13 is returned to the original position.

[0083] Although the above description has been given of the case where the optical axis of the road surface drawing device 13 is adjusted to provide illumination, the optical axis of the headlight 14 may also be adjusted. Alternatively, the optical axis of the headlight 14 may be adjusted to illuminate the insufficiently illuminated area without providing illumination by the road surface drawing device 13.

[0084] As described above, according to Modification 1-2, when the gradient change angle θ between the first road surface and the second road surface is large, the optical axis is adjusted when entering the third area to illuminate the insufficiently illuminated area of ​​the second road surface. This allows the road surface ahead of the vehicle 15 to be illuminated in advance, thereby expanding the visible area ahead of the vehicle 15 and contributing to driving assistance.

[0085] <Modification 1-3> In Modification 1-3, notification display by the road surface drawing device 13 will be described.

[0086] The notification drive unit 3 drives the road surface drawing device 13 to display a notification at a position (notification display position) on the vehicle's side a predetermined distance from the change point. The road surface drawing device 13 projects a road surface drawing pattern, for example, as shown in Figures 20 to 23, onto the notification display position. The road surface drawing pattern indicates the presence of an insufficiently illuminated area.

[0087] FIG. 20 shows a single horizontal bar as an example of a road surface drawing pattern.

[0088] Figure 21 shows three horizontal bars as an example of a road surface drawing pattern. The number of horizontal bars shown in Figure 21 is not limited to three, and any number of bars may be used. The number of bars may be increased as the gradient change angle θ between the first road surface and the second road surface increases.

[0089] FIG. 22 shows a triangle as an example of a road surface drawing pattern.

[0090] FIG. 23 shows a triangle and a curved arrow as an example of a road surface rendering pattern. The curved arrow indicates that the road shape on the other side of the transition point including the insufficiently illuminated area is curved. Since displaying both the triangle and the curved arrow simultaneously can be confusing, they may be displayed alternately in chronological order. The curved arrow may also be displayed when the vehicle 15 is traveling in the second area.

[0091] The distance between the change point and the position of the notification display may be changed depending on the speed of the host vehicle or the distance from the host vehicle to the change point. For example, the distance between the change point and the position of the notification display may be greater when the host vehicle is traveling at a high speed than when the host vehicle is traveling at a low speed. Also, the distance between the change point and the position of the notification display may be greater when the distance from the host vehicle to the change point is long than when the distance is short.

[0092] From the above, according to variant example 1-3, by displaying the notification at a position closer to the vehicle 15 than the change point (position of the notification display), the driver can easily recognize the notification display, thereby achieving optimal driving assistance.

[0093] <Modification 1-4> In Modification 1-4, a case where the virtual image generating device 12 and the road surface drawing device 13 are used simultaneously will be described.

[0094] Although it has been described in Fig. 23 that triangles and curved arrows may be displayed alternately in a time series, as shown in Fig. 24, triangles may be displayed as a road surface drawing pattern at the position of the notification display, and curved arrows may be displayed on the HUD. HUD display refers to displaying an object generated by the virtual image generation device 12. Note that the triangles and curved arrows may be displayed in different colors. The curved arrow may be displayed on the HUD on the right side of the road if the road shape on the other side of the turning point is a right curve, and on the left side of the road if the road shape is a left curve.

[0095] Assume that the vehicle 15 is traveling on a slope with a depression ahead, as shown in Fig. 25 . In Fig. 25 , the depression is an insufficiently illuminated area because the illumination from the headlights 14 does not reach the depression. In this case, the road surface drawing device 13 displays a road surface drawing pattern with a hollow as shown in Fig. 26 . Alternatively, as shown in Fig. 27 , the display of the road surface drawing pattern by the road surface drawing device 13 and the HUD display by the virtual image generation device 12 may be combined.

[0096] 28 to 36 show examples of notification displays. These notification displays can be used for both road surface rendering patterns and HUD displays. Note that the examples in FIGS. 28 to 36 are intended for notification displays on a slope with a depression, as shown in FIG. 25.

[0097] 28 and 29 show examples of notification displays when the road ahead of the vehicle is straight. The areas surrounded by dashed lines in Figures 28 and 29 indicate areas of insufficient lighting.

[0098] 30 shows an example of a notification display when the road ahead of the vehicle is curved to the right. The area surrounded by a dashed line in FIG. 30 indicates an insufficiently illuminated area.

[0099] Fig. 31 shows an example of a notification display when the road ahead of the vehicle is curved to the left. The area surrounded by a dashed line in Fig. 31 indicates an insufficiently illuminated area.

[0100] Figures 32 to 36 are examples of notification displays when the road ahead of the vehicle is straight, and are examples other than the notification displays shown in Figures 28 and 29. The areas surrounded by dashed lines in Figures 32 to 36 indicate areas with insufficient lighting.

[0101] 28 to 36, the color of the portion indicating the insufficiently illuminated area may be different from the color of the other portion.

[0102] As described above, according to Modification 1-4, the driver can easily recognize the notification display, thereby realizing optimal driving assistance.

[0103] <Modification 1-5> In Modification 1-5, a case where there are multiple change points in a predetermined section will be described.

[0104] As shown in FIG. 37, when a first change point and a second change point exist in a predetermined section, the change point targeted by the host vehicle 15 changes from the first change point to the second change point.

[0105] If a first change point exists within distance B0 from the host vehicle 15, the notification drive unit 3 drives the notification device 11 to display a notification at the position of the first notification display. Thereafter, if a second change point exists within distance B0 from the host vehicle 15, the notification drive unit 3 drives the notification device 11 to display a notification at the position of the second notification display. In this way, the notification drive unit 3 drives the notification device 11 to update the notification display based on each of the first change point and the second change point.

[0106] As described above, according to Modification 1-5, the position of the notification display is changed in accordance with the change in the change point, so that the driver can easily recognize the notification display, thereby realizing optimal driving assistance.

[0107] <Modification 1-6> In Modification 1-6, a case will be described in which the shape of the road surface drawing pattern is changed depending on the distance from the vehicle 15 to the change point.

[0108] As shown in Fig. 38 , the notification drive unit 3 drives the road drawing device 13 so that the road drawing pattern is larger when the distance from the host vehicle 15 to the change point is longer than when it is shorter. In the example of Fig. 38 , the road drawing pattern is displayed when the host vehicle 15 enters the first area and it is detected that a change point exists within distance B0 from the host vehicle 15. Thereafter, the road drawing pattern is made smaller when the host vehicle 15 enters the second area. Thereafter, the display of the road drawing pattern is terminated when the host vehicle 15 enters the third area.

[0109] As shown in Fig. 39 , the notification drive unit 3 drives the road drawing device 13 so that the road drawing pattern has a shape that is more salient when the distance from the host vehicle 15 to the change point is long than when it is short. In the example of Fig. 39 , the road drawing pattern is displayed when the host vehicle 15 enters a first area and it is detected that a change point exists within a distance B0 from the host vehicle 15. Thereafter, the salience of the road drawing pattern is lowered when the host vehicle 15 enters a second area. Thereafter, the salience of the road drawing pattern is further lowered when the host vehicle 15 enters a third area.

[0110] As described above, according to Modification 1-6, the visibility of a driver who is far from the change point can be improved by enlarging the road surface drawing pattern when the distance from the vehicle 15 to the change point is long. Also, by increasing the conspicuousness of the road surface drawing pattern when the distance from the vehicle 15 to the change point is long, the visibility and attention level of a driver who is far from the change point can be improved.

[0111] <Modification 1-7> In Modification 1-7, a case will be described in which a notification display is executed before the host vehicle 15 reaches the first area.

[0112] For example, based on information obtained from the DMS, the notification drive unit 3 drives the notification device 11 to execute a notification display when it detects that the driver is attempting to view an insufficiently lit area before the vehicle 15 reaches the notification timing position in the first area.

[0113] The notification device 11 that displays the notification may be selected depending on the timing at which the driver's behavior of attempting to view the insufficiently illuminated area is detected. For example, if the distance from the vehicle 15 to the position of the notification display is long when the behavior is detected, the virtual image generation device 12 may be selected, and the road surface drawing device 13 may be selected when the distance from the vehicle 15 to the position of the notification display becomes shorter to a certain extent.

[0114] As described above, according to variant example 1-7, the notification display is executed when the driver's attempt to view the insufficiently lit area is detected, thereby realizing more appropriate driving assistance.

[0115] <Modification 1-8> In Modification 1-8, a case will be described in which the mode of the notification display is changed depending on the driving risk associated with the insufficiently illuminated area.

[0116] 40 and 41 are diagrams showing examples of notification displays. These notification displays can be used for both road surface drawing patterns and HUD displays.

[0117] For example, the higher the risk, the higher the frequency at which the triangle shown in FIG. 40 flashes (for example, changing the frequency from 1 Hz to 5 Hz).

[0118] As shown in FIG. 41, the color of the triangle may change depending on the degree of risk (for example, from red to yellow to blue).

[0119] It is also possible to combine Figure 40 and Figure 41. Specifically, the frequency of flashing may be changed and the hue may be changed according to the level of risk.

[0120] Here, the risks will be explained.

[0121] Risks include, for example, risks due to road structure, risks depending on the speed of the vehicle 15, risks due to the distance or time from the vehicle 15 to the change point, and risks due to the driver's steering operation (the steering angle and the speed of the vehicle 15 are also related).

[0122] For example, consider a case where the hue of the triangle shown in Fig. 41 is changed depending on the risk due to the road structure. If there is no risk on the road beyond the change point (for example, in the case of a straight road), a blue triangle is displayed. If there is a branch road, merging road, intersection, or curve on the road beyond the change point, a yellow triangle is displayed. If there is a crosswalk or bus stop on the road beyond the change point, a red triangle is displayed.

[0123] As described above, according to variant example 1-8, the driver is notified of driving risks related to poorly lit areas, so that the driver can pay attention to the risks in advance.

[0124] <Modification 1-9> In Modification 1-9, a case will be described in which a notification display is executed that allows the type of road present in an insufficiently illuminated area to be identified.

[0125] 42 to 46 are diagrams showing examples of notification displays that enable the type of road present in an insufficiently lit area to be identified. FIG. 42 shows the presence of a branch road in the insufficiently lit area. FIG. 43 shows the presence of a merging road in the insufficiently lit area. FIG. 44 shows the presence of an intersection in the insufficiently lit area. FIG. 45 shows the presence of a pedestrian crossing in the insufficiently lit area. FIG. 46 shows the presence of a temporary parking area or a bus stop in the insufficiently lit area. The branch road, approach road, intersection, pedestrian crossing, temporary parking area, and bus stop correspond to road types. In FIGS. 42 to 46, the portion indicating the road type is highlighted. The highlighted portion may also be flashed. The curved arrows shown in FIGS. 23 and 24 also correspond to notification displays that enable the type of road to be identified.

[0126] The above-mentioned notification display can be used for both road surface drawing patterns and HUD displays. In the case of HUD displays, the notification display can be superimposed on the position (direction) where the road type is located. In particular, when using a virtual image generating device 12 that has a function of varying the virtual image distance, it is effective to adjust the virtual image distance to the position where the road type is located. In the case of HUD displays, an icon that indicates the road type may be displayed.

[0127] As described above, according to variant example 1-9, a warning display is provided that allows the type of road to be identified, so the driver can determine the risk according to the type of road and can pay attention to the risk in advance.

[0128] <Modification 1-10> In the first embodiment, a case has been described in which a notification is displayed to inform the driver of the presence of an insufficiently illuminated area when the headlights 14 are on. In Modification 1-10, a case has been described in which a notification is displayed to inform the driver of the presence of an invisible area that cannot be seen by the driver when the headlights 14 are off.

[0129] FIG. 47 is a flowchart showing an example of the operation of a driving assistance device according to Modification 1-10. Note that steps S301 to S308 in FIG. 47 are similar to steps S101 to S108 in FIG. 12, but in step S308, a road surface drawing pattern is displayed as a notification display. Steps S309 to S312 in FIG. 47 are similar to steps S203, S204, S207, and S206 in FIG. 13. Steps S316 and S317 in FIG. 47 are similar to steps S109 and S110 in FIG. 12. Therefore, a description of each of these processes will be omitted. Steps S313 to S315 will be described below.

[0130] In step S313, the insufficiently illuminated area determination unit 2 determines whether or not an invisibility area exists based on the driver's eye height. If an invisibility area exists, the process proceeds to step S314. On the other hand, if an invisibility area does not exist, the process proceeds to step S316.

[0131] In step S314, the insufficiently illuminated region determining unit 2 determines the position of the notification display based on the change point.

[0132] In step S315, the notification drive unit 3 drives the virtual image generation device 12 so that an object in a predetermined display mode is superimposed on the position of the notification display. The virtual image generation device 12 displays the generated object as a notification so that it is superimposed on the position of the notification display. In this way, the virtual image generation device 12 executes a notification display that visually notifies the driver of the host vehicle 15 of the existence of an invisible area.

[0133] From the above, according to Modification 1-10, when the headlights 14 are off in bright conditions such as daytime, the presence of an invisible area calculated based on the driver's eye height can be notified to the driver using the virtual image generating device 12, which has a high notification effect even during the day. When the headlights 14 are on at night, the presence of an invisible area calculated based on whether the illumination light illuminates the second road surface can be notified using a road surface drawing pattern, which has a high notification effect at night. Generally, visibility is good during the daytime because of the brightness, but the driver's visual characteristics and the degree of concentration on driving can reduce the awareness of the invisible area ahead of the road. Modification 1-10 has the effect of strengthening daytime recognition assistance.

[0134] Note that the notification display may be executed with the headlights 14 turned off only when the DMS detects a decline in the driver's awareness. Also, the notification display may be executed with the headlights 14 turned off only when the DMS detects the driver's behavior of checking the invisible area ahead of the road (for example, the driver's gaze concentrating on the invisible area).

[0135] <Modification 1-11> In Modification 1-11, a notification display during bad weather will be described.

[0136] In bad weather such as rain, snow, or fog, visibility of the road surface decreases, so it is useful to display a notification using the virtual image generation device 12. Specifically, when the road on which the vehicle 15 is traveling is in bad weather, the notification drive unit 3 drives the virtual image generation device 12 with priority over the road surface drawing device 13. Furthermore, when the road on which the vehicle 15 is traveling is uphill, the notification drive unit 3 may drive the virtual image generation device 12 to display a notification of the top position of the slope and the road shape of the insufficiently illuminated area beyond the top of the slope.

[0137] Furthermore, when a preceding vehicle or an oncoming vehicle is present ahead of the host vehicle 15, a situation may arise in which the preceding vehicle obstructs the projection of the road surface drawing pattern, or illumination by the headlights of the oncoming vehicle reduces the visibility of the driver of the host vehicle 15, and therefore the notification display by the virtual image generating device 12 is useful. Note that when a preceding vehicle or an oncoming vehicle is present ahead of the host vehicle 15, it is easy to predict the travel route of the host vehicle 15, so the notification display may not be executed.

[0138] <Embodiment 2> <Configuration> Fig. 48 is a block diagram showing an example of the configuration of a driving assistance device 16 according to embodiment 2. The driving assistance device 16 includes a vehicle information acquisition unit 5, a camera information acquisition unit 17, an insufficiently illuminated area determination unit 18, and a notification drive unit 3. The driving assistance device 16 is also connected to each of a vehicle information detection device 8, a front camera 19, and a notification device 11. The vehicle information acquisition unit 5, the notification drive unit 3, the vehicle information detection device 8, and the notification device 11 are the same as those in embodiment 1, and therefore detailed description thereof will be omitted here.

[0139] The front camera 19 captures an image of the area ahead of the vehicle 15, and uses image processing to detect the range (angle and distance) of the road surface illuminated by the headlights from the vehicle's position, or to detect areas of insufficient illumination. The headlights are not shown in the figure because they are not connected to the driving assistance device 16, but they are the same as the headlights 14 described in the first embodiment.

[0140] The camera information acquisition unit 17 acquires illumination range information relating to the illumination range of the headlights from the front camera 19. The illumination range information includes the shortest distance from the vehicle position to the insufficient illumination area (the distance from the vehicle 15 to the change point).

[0141] <Operation> Figure 49 is a flowchart showing an example of the operation of the driving assistance device according to embodiment 2. Note that steps S401, S402, and S404 to S409 in Figure 49 are similar to steps S101, S102, and S105 to S110 in Figure 12, and therefore will not be described here. Step S403 will be described below.

[0142] In step S403 , the camera information acquisition unit 17 acquires illumination range information ahead of the vehicle 15 from the front camera 19 .

[0143] Any method may be used to detect the shortest distance from the vehicle position to the insufficiently illuminated area (the distance from the vehicle 15 to the change point). For example, if the front camera 19 is a monocular camera, the distance can be calculated using the parameters shown in FIG. 50. FIG. 50 shows the capture range of the front camera 19 as seen from above the vehicle 15. The capture range of a road with a constant gradient without gradient changes is determined by the direction and height of the front camera 19. In FIG. 50, the camera is designed to capture scenery farther away than the distance Y0. In this case, the lateral capture range X0 at the distance Y0 is also determined as a design value.

[0144] As shown in Figure 51, the bottom edge of the captured image corresponds to a position at a distance Y0. The ratio of the number of pixels PXmax in the horizontal direction of the captured image to the number of pixels Pw(Y0) in the x direction corresponding to the lane width corresponds to the ratio of the horizontal capture range X0 at the distance Y0 to the lane width Ww. Therefore, the lane width near the host vehicle 15 can be calculated from the number of pixels Pw(Y0) in the x direction corresponding to the lane width.

[0145] The ratio between the number of pixels Pw(y) in the x direction corresponding to the lane width at distance y and the number of pixels Pw(Y0) in the x direction corresponding to the lane width at distance Y0 corresponds to the ratio between distance Y0 and distance y. Therefore, distance y can be determined from the number of pixels Pw(y) in the x direction corresponding to the lane width at distance y.

[0146] 52 and 53 are diagrams showing the number of pixels Pw(y) of the lane width at the change point. Fig. 52 is an image taken by the front camera 19 when the host vehicle 15 was traveling in the first area, and Fig. 53 is an image taken by the front camera 19 when the host vehicle 15 was traveling in the second area. As shown in Figs. 52 and 53, the distance from the host vehicle 15 (front camera 19) to the change point can be calculated using the lane width at the farthest illuminated position in the captured image.

[0147] The function of calculating the distance from the vehicle 15 to the change point may be provided by the camera information acquisition unit 17 or by the insufficiently illuminated area determination unit 18. In this case, the front camera 19 has a function of outputting an image of the area ahead of the vehicle 15.

[0148] Although the above description has been given of distance measurement using a monocular camera, distance measurement may be performed using any method, such as distance measurement using a binocular camera or distance measurement using invisible light.

[0149] <Effects> According to the second embodiment, the same effects as those of the first embodiment can be achieved. When a camera is mounted to control the headlights using ADB (Adaptive Driving Beam), it is possible to use images captured by the camera without using a map database and a positioning device, thereby reducing costs.

[0150] Furthermore, after the notification display is executed, the position of the notification display is detected from the image captured by the front camera 19, thereby making it possible to dynamically adjust the position of the notification display through feedback control.

[0151] In Modification 2-1, the road illumination length of the headlights is detected sequentially, and based on the detected change in the road illumination length, it is determined whether an insufficiently illuminated area exists, the timing of displaying a warning, and the end of the warning. Here, the road illumination length refers to the longest distance that the light from the headlights illuminates the road surface.

[0152] 54 is a block diagram showing an example of the configuration of a driving assistance device 20 according to Modification 2-1. The driving assistance device 20 is characterized by including an insufficiently illuminated area determination unit 21. The rest of the configuration is the same as that of the driving assistance device 16 described in embodiment 2 (see FIG. 48), so detailed description will be omitted here. Note that headlights are not shown because they are not connected to the driving assistance device 20, but they are the same as the headlights 14 described in embodiment 1.

[0153] The front camera 19 has the function of capturing images of oncoming vehicles, pedestrians, obstacles, road conditions, and the like in front of the vehicle, and measuring the distance to the objects by image processing.

[0154] The camera information acquisition unit 17 acquires, from the front camera 19, analysis information of the image captured by the front camera 19. In the modified example 2-1, information on the length of the road surface illumination is acquired.

[0155] With the headlights on, the insufficiently illuminated area determination unit 21 determines whether or not an insufficiently illuminated area exists based on the road surface illumination length measured from the image captured by the front camera 19. Specifically, the insufficiently illuminated area determination unit 21 determines whether the host vehicle 15 is traveling in the first area, the second area, or the third area based on changes in the road surface illumination length, and determines whether or not an insufficiently illuminated area exists.

[0156] In the driving assistance device 20 of variant example 2-1, unlike the driving assistance device 4 of embodiment 1, the positions of the first area, second area, and third area and the presence or absence of insufficiently lit areas cannot be obtained in advance, but are obtained in real time from information obtained from the forward camera 19.

[0157] Here, the change in road surface lighting length will be explained.

[0158] Fig. 55 is a diagram showing a schematic diagram of the change in road surface illumination length Li when the headlights illuminate the road surface with a low beam. Figs. 56 to 58 are diagrams showing the change in road surface illumination length Li when the headlights illuminate the road surface with a low beam, as viewed from above.

[0159] The road surface illumination length Li when the vehicle 15 is traveling on a slope with a constant gradient is defined as L1. Ignoring the tilt due to the vehicle's own weight, L1 is the same as when the vehicle 15 is traveling on a flat road (see FIG. 56). In this case, the locus of the road surface illumination length Li corresponds to the first area in FIG. 55.

[0160] Furthermore, when the vehicle 15 travels uphill and the leading edge of the low beam passes the change point, the reflected light from the other side of the change point (the second road surface) disappears, and the road surface illumination length Li shortens from L1 to L2 (see FIG. 57). At this time, the trajectory of the road surface illumination length Li corresponds to the second area in FIG. 55. The insufficiently illuminated area determiner 21 determines that an insufficiently illuminated area exists at the timing when the road surface illumination length Li changes from L1 to L2.

[0161] After that, when the vehicle 15 continues traveling uphill, the road surface illumination length Li becomes the shortest distance L3. At this time, the trajectory of the road surface illumination length Li corresponds to area 3 in Figure 55. As the vehicle 15 continues traveling, the road surface illumination length Li increases from L3 by L4 (see Figure 58). At this time, the trajectory of the road surface illumination length Li corresponds to area 3a in Figure 55. Furthermore, because the low beam is illuminating an insufficiently illuminated area, the notification display is terminated.

[0162] Note that any known method may be used to calculate the road surface illumination length from the image captured by the front camera 19. For example, if a monocular camera is used as the front camera 19, the installation position, angle, angle of view, etc. of the monocular camera are known, and therefore the road surface illumination length may be calculated from the longest position in the illumination range of the headlights and the change in the width of the white lines illuminated by the headlights or the distance between the white lines in the width direction. Alternatively, the road surface illumination length may be calculated using a binocular camera as the front camera 19. Furthermore, the road surface illumination length may be calculated using the method described in embodiment 2.

[0163] <Operation> FIG. 59 is a flowchart showing an example of the operation of the driving assistance device according to Modification 2-1.

[0164] In step S501, the vehicle information acquisition unit 5 acquires information on whether the headlights are on or off from the vehicle information detection device 8 and determines whether the headlights are on. If the headlights are on, the process proceeds to step S502. On the other hand, if the headlights are not on, the process proceeds to step S507.

[0165] In step S502, the insufficiently illuminated area determination unit 21 detects the road surface illumination length of the headlights. At this point, the vehicle 15 is traveling in the first area, so the road surface illumination length Li is L1 (first length) (see FIGS. 55 and 56).

[0166] In step S503, the insufficiently illuminated area determination unit 21 determines whether the host vehicle 15 has reached the second area. Specifically, the insufficiently illuminated area determination unit 21 determines whether the road surface illumination length Li of the headlights has reached L2 (second length, L2<L1), and determines that the host vehicle 15 has reached the second area when the road surface illumination length Li has reached L2. If the host vehicle 15 has reached the second area, the process proceeds to step S504. On the other hand, if the host vehicle 15 has not reached the second area, the process returns to step S501.

[0167] In step S504, the notification driver 3 drives the notification device 11 to display a notification. The process of step S504 is the same as that in the first embodiment (see, for example, step S108 in FIG. 12).

[0168] In step S505, the insufficiently illuminated area determination unit 21 detects the length of the road surface illuminated by the headlights.

[0169] In step S506, the insufficiently illuminated area determination unit 21 determines whether the host vehicle 15 has entered the third area. Specifically, the insufficiently illuminated area determination unit 21 determines whether the road surface illumination length Li of the headlights becomes L3 (L3<L2, the road surface illumination length is the shortest) and then becomes L3+L4 (the third length, L4>0), and determines that the host vehicle 15 has entered the third area when the road surface illumination length Li becomes L3+L4. If the host vehicle 15 has entered the third area, the process proceeds to step S507. On the other hand, if the host vehicle 15 has not entered the third area, the process returns to step S505.

[0170] In step S507, the notification drive unit 3 controls the notification device 11 to end the notification display.

[0171] In step S508, the driving assistance device 20 determines whether or not the driving of the vehicle 15 has ended. If the driving of the vehicle 15 has ended, the operation of Fig. 59 ends. On the other hand, if the driving of the vehicle 15 has not ended, the process returns to step S501.

[0172] As described above, according to variant example 2-1, images captured by a camera can be used, so no additional hardware is required and the presence of an insufficiently lit area can be notified to the driver in a simple manner.

[0173] <Hardware Configuration> The functions of the vehicle information acquisition unit 5, the map information acquisition unit 6, the insufficiently illuminated area determination unit 2, the notification drive unit 3, and the illumination drive unit 7 in the driving assistance device 4 according to the first embodiment are realized by processing circuits. That is, the driving assistance device 4 includes a processing circuit for acquiring vehicle information, acquiring map data of the area around the vehicle 15, determining whether or not an insufficiently illuminated area exists, driving the notification device 11, and driving at least one of the headlights 14 and the road surface drawing device 13. The processing circuit may be dedicated hardware, or may be a processor (also referred to as a CPU, central processing unit, processing device, arithmetic unit, microprocessor, microcomputer, or DSP (Digital Signal Processor)) that executes a program stored in a memory.

[0174] When the processing circuit is dedicated hardware, the processing circuit 30 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, as shown in Fig. 60. The functions of the vehicle information acquisition unit 5, the map information acquisition unit 6, the insufficient illumination area determination unit 2, the notification drive unit 3, and the illumination drive unit 7 may be realized individually by the processing circuit 30, or these functions may be realized collectively by a single processing circuit 30.

[0175] When the processing circuit 30 is the processor 40 shown in FIG. 61 , the functions of the vehicle information acquisition unit 5, the map information acquisition unit 6, the insufficiently illuminated area determination unit 2, the notification drive unit 3, and the illumination drive unit 7 are realized by software, firmware, or a combination of software and firmware. The software or firmware is written as a program and stored in the memory 41. The processor 40 realizes each function by reading and executing the program recorded in the memory 41. That is, the driving assistance device 4 includes the memory 41 for storing a program that results in the execution of steps of acquiring vehicle information, acquiring map data around the vehicle 15, determining whether or not an insufficiently illuminated area exists, driving the notification device 11, and driving at least one of the headlights 14 and the road surface drawing device 13. Furthermore, these programs can also be said to cause a computer to execute the procedures or methods of the vehicle information acquisition unit 5, the map information acquisition unit 6, the insufficiently illuminated area determination unit 2, the notification drive unit 3, and the illumination drive unit 7. Here, the memory may be, for example, a 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), a magnetic disk, a flexible disk, an optical disk, a compact disk, a DVD (Digital Versatile Disc), or any storage medium that will be used in the future.

[0176] It is also possible to realize some of the functions of the vehicle information acquisition unit 5, map information acquisition unit 6, insufficient lighting area determination unit 2, notification drive unit 3, and lighting drive unit 7 by using dedicated hardware, and other functions by using software or firmware.

[0177] Thus, the processing circuitry can implement each of the above-described functions through hardware, software, firmware, or a combination thereof.

[0178] Although the above describes the hardware configuration of the driving assistance device 4 according to embodiment 1, the same applies to the hardware configuration of the driving assistance device 16 according to embodiment 2 and the hardware configuration of the driving assistance device 20 according to variant example 2-1.

[0179] Within the scope of the present disclosure, the embodiments can be freely combined, modified, or omitted as appropriate.

[0180] Although the present disclosure has been described in detail, the above description is illustrative in all respects and is not restrictive. It is understood that countless variations not illustrated can be envisioned.

[0181] REFERENCE SIGNS LIST 1 Driving assistance device, 2 Insufficiently illuminated area determination unit, 3 Notification drive unit, 4 Driving assistance device, 5 Vehicle information acquisition unit, 6 Map information acquisition unit, 7 Lighting drive unit, 8 Vehicle information detection device, 9 Map database, 10 Positioning device, 11 Notification device, 12 Virtual image generation device, 13 Road surface drawing device, 14 Headlight, 15 Vehicle, 16 Driving assistance device, 17 Camera information acquisition unit, 18 Insufficiently illuminated area determination unit, 19 Front camera, 20 Driving assistance device, 21 Insufficiently illuminated area determination unit, 30 Processing circuit, 40 Processor, 41 Memory.

Claims

1. A driving assistance device comprising: an insufficient illumination area determination unit that determines the presence of an insufficiently illuminated area in front of the host vehicle, where the illumination by the headlights is insufficient, based on at least gradient information of a road on which the host vehicle is traveling and the installation height of the headlights of the host vehicle, or based on camera information capturing an image of the area in front of the host vehicle; and a notification drive unit that drives a notification device that executes a notification display to visually notify a driver of the host vehicle of the presence of the insufficiently illuminated area, when the insufficiently illuminated area determination unit determines that the insufficiently illuminated area exists when the headlights are on, wherein the notification drive unit drives a virtual image generation device which is the notification device, or drives a road surface drawing device which is the notification device.

2. The driving assistance device of claim 1, wherein the insufficiently illuminated area determination unit further classifies areas into a first area where the driver cannot see and where the headlight illumination is insufficient, a second area where the driver can see and where the headlight illumination is insufficient, and a third area where the driver can see and where the headlight illumination is sufficient, based on the height of the driver's eyes; and the notification drive unit drives the notification device to display the notification at least when the vehicle is traveling through the second area.

3. The driving assistance device according to claim 1, further comprising an illumination driving unit that drives an optical axis adjusting device that adjusts the optical axis of the road surface drawing device or the headlights based on an instruction from the notification driving unit to instruct the driving device to illuminate the insufficiently illuminated area.

4. A driving assistance device as described in claim 1, wherein a point where the gradient of the road ahead of the vehicle changes is defined as a change point, and the notification drive unit drives the notification device to display the notification on the vehicle side a predetermined distance from the change point.

5. A driving assistance device as described in claim 4, wherein, when there are a plurality of change points in a predetermined section, the notification drive unit drives the notification device to update the notification display based on each of the change points.

6. A driving assistance device as described in claim 4, wherein the notification drive unit drives the road surface drawing device so that the road surface drawing pattern, which is the notification display, is larger when the distance from the vehicle to the change point is long than when it is short.

7. A driving assistance device as described in claim 4, wherein the notification drive unit drives the road surface drawing device so that the road surface drawing pattern, which is the notification display, has a shape that is more noticeable when the distance from the vehicle to the change point is long than when it is short.

8. A driving assistance device as described in claim 1, wherein when the notification drive unit detects an action by the driver attempting to view the insufficiently illuminated area before the insufficiently illuminated area determination unit determines that the insufficiently illuminated area exists, the notification drive unit prioritizes driving the virtual image generating device over a case in which the notification drive unit does not detect such action.

9. A driving assistance device as described in claim 1, wherein the notification drive unit determines a driving risk related to the insufficiently illuminated area based on information regarding the road on which the vehicle is traveling, and drives the notification device so that the notification display is more noticeable when the risk is high than when the risk is low.

10. A driving assistance device as described in claim 1, wherein the notification drive unit drives the notification device to execute the notification display capable of determining the type of road based on the type of road present in the poorly illuminated area.

11. A driving assistance device as described in claim 2, wherein, when the headlights are off, the insufficiently illuminated area determination unit determines the presence of an area that cannot be seen by the driver based on the height of the driver's eyes, and the notification drive unit drives the virtual image generation device to display the notification of the presence of the insufficiently visible area; and, when the headlights are on, the notification drive unit drives the road surface drawing device to display the notification of the presence of the insufficiently illuminated area.

12. A driving assistance device as described in claim 1, wherein, when the road on which the vehicle is traveling is in bad weather, the notification drive unit drives the virtual image generating device with priority over the road surface drawing device, and drives the virtual image generating device to notify and display the top position of a slope and the road shape of the insufficiently illuminated area beyond the top of the slope.

13. The driving assistance device of claim 1, wherein the insufficient illumination area determination unit determines, based on the camera information, that the insufficient illumination area exists when the road surface illumination length of the headlight reaches a second length that is shorter than a reference first length, and determines that the insufficient illumination area does not exist when the road surface illumination length reaches a third length that is the shortest length equal to or shorter than the second length; and the notification drive unit drives the notification device based on the determination result of the insufficient illumination area determination unit.

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