Driving assistance device and driving assistance method

Abstract

The purpose of the present disclosure is to efficiently assist drivers in visually recognizing a blind spot road surface using a traffic mirror. A driving assistance device (101) according to the present disclosure comprises a mirror detection unit (12) for detecting a traffic mirror (42) in front of a vehicle (41) on the basis of an image captured by a camera (31) mounted on the vehicle (41), a nighttime detection unit (13) for detecting when it is nighttime, and an irradiation control unit (14) for causing the traffic mirror (42) detected at night to be irradiated with a spotlight by a spotlight illumination lamp (33) that is provided to the vehicle (41) and illuminates an area in front of the vehicle (41). The mirror surface of the traffic mirror (42) is configured from a lower region (RB) and an upper region (RU) adjacent to the upper side of the lower region (RB). An irradiation region that is the region of the traffic mirror (42) irradiated with the spotlight does not include at least a portion of the upper region (RU) but does include at least a portion of the lower region (RB).

Description

Driving assistance device and driving assistance method

[0001] The present disclosure relates to a driving assistance system that improves the visibility of convex mirrors.

[0002] At points with poor visibility, such as intersections, there are road surfaces that are in the driver's blind spot (hereinafter referred to as blind spot road surfaces), and convex mirrors are sometimes installed at such points. The driver of a vehicle can use the convex mirror to check for other vehicles or pedestrians on the blind spot road surface.

[0003] However, in dark conditions, such as at night when there are no road lights, it is difficult for drivers to see the condition of the road surface in their blind spot reflected in the convex mirror. This is because, while headlights are usually installed about 50 cm above the ground, convex mirrors are installed about 2.5 m above the ground, so the light emitted from the headlights does not hit the convex mirror and the reflected light does not shine on the road surface in their blind spot. This phenomenon becomes particularly noticeable as the vehicle approaches the convex mirror.

[0004] In addition, convex mirrors are often used for convex mirrors. In such cases, if a vehicle is far from the convex mirror, the light from the headlights reflected by the convex mirror will be diffused, and the illumination of the blind spot road surface will not be improved significantly.

[0005] For this reason, Patent Document 1 discloses a technology that detects the position of a curved mirror and illuminates the mirror to increase the illumination of the blind spot road surface, and also makes traffic participants such as pedestrians moving on the blind spot road surface aware of the presence of a vehicle.

[0006] Japanese Patent Application Laid-Open No. 2023-53532

[0007] Convex mirrors are installed at an angle that allows the reflected light from the blind spot road surface to be seen, based on the eye height of the driver or pedestrian. Therefore, when a vehicle shines light onto a convex mirror, the light that hits the lower side of the mirror is useful for illuminating the blind spot road surface, but the light that hits the upper side is reflected upwards onto the blind spot road surface, which is wasteful from the perspective of illuminating the blind spot road surface and, in urban areas, could cause nuisance lighting for surrounding houses.

[0008] The present disclosure has been made to solve the above-mentioned problems, and aims to efficiently assist drivers in visually recognizing blind spot road surfaces using curved mirrors.

[0009] The driving assistance device of the present disclosure includes a mirror detection unit that detects a convex mirror ahead of the vehicle based on an image captured by a camera mounted on the vehicle, a nighttime detection unit that detects that it is nighttime, and an illumination control unit that causes a spotlight to be emitted onto the convex mirror detected at night using a spotlight lamp that is provided on the vehicle and illuminates the area ahead of the vehicle. The mirror surface of the convex mirror is composed of a lower region and an upper region adjacent to the upper side of the lower region, and the illumination region, which is the region of the convex mirror onto which the spotlight is emitted, excludes at least a portion of the upper region and includes at least a portion of the lower region.

[0010] According to the driving assistance device of the present disclosure, spot illumination is primarily directed to the lower area of ​​the convex mirror while avoiding at least a portion of the upper area, thereby efficiently assisting the driver in visually recognizing the road surface in the blind spot through the convex mirror. Objects, features, aspects, and advantages of the present disclosure will become more apparent from the following detailed description and the accompanying drawings.

[0011] 1 is a block diagram showing the configuration of a driving assistance device according to embodiment 1. FIG. 2 is a flowchart showing the operation of the driving assistance device according to embodiment 1. FIG. 3 is a diagram showing an example of wide-area spot illumination by the driving assistance device according to embodiment 1. FIG. 4 is a diagram showing the relationship between the angle and brightness of wide-area spot illumination. FIG. 5 is a diagram showing illumination from headlights and wide-area spot illumination when a vehicle is traveling on a curved road. FIG. 6 is a block diagram showing the configuration of a driving assistance device according to embodiment 2. FIG. 7 is a flowchart showing the operation of the driving assistance device according to embodiment 2. FIG. 8 is a diagram showing an example of wide-area spot illumination by the driving assistance device according to embodiment 2. FIG. 9 is a diagram showing an example of narrow-area spot illumination by the driving assistance device according to embodiment 2. FIG. 10 is a diagram showing a light path when a camera captures a pedestrian. FIG. 11 is a diagram showing the light path of spot illumination light before coordinate transformation. FIG. 12 is a diagram showing the light path of spot illumination light after coordinate transformation. FIG. 13 is a diagram showing an example of intermediate illumination by the driving assistance device according to embodiment 2. FIG. 14 is a block diagram showing the configuration of a driving assistance device according to embodiment 3. FIG. 15 is a flowchart showing the operation of the driving assistance device according to embodiment 3. FIG. 16 is a diagram showing the lower area of ​​a convex mirror installed on a horizontal left curve. FIG. 17 is a diagram showing the lower area of ​​a convex mirror installed on a left curve with an upslope. FIG. 18 is a diagram showing the lower area of ​​a convex mirror installed on a left curve with a downslope. FIG. 19 is a diagram showing the hardware configuration of a driving assistance device. FIG. 2 is a diagram illustrating a hardware configuration of a driving assistance device.

[0012] <A. Embodiment 1> <A-1. Overall Configuration> Fig. 1 is a block diagram showing the configuration of a driving assistance device 101 according to Embodiment 1. The driving assistance device 101 controls a spot illumination lamp 33 mounted on a vehicle and causes the spot illumination lamp 33 to illuminate a convex mirror in front of the vehicle with a spot light at night, thereby enabling the driver to see the blind spot road surface through the convex mirror even at night.

[0013] In this specification, a vehicle equipped with a spotlight 33 controlled by a driving assistance device will be simply referred to as a "vehicle."

[0014] The driving assistance device 101 is connected to and configured to be able to use the camera 31, the nighttime determination sensor 32, and the spot lighting fixture 33. The driving assistance device 101 is mounted on, for example, a vehicle to be controlled.

[0015] The camera 31 is a camera that monitors the area ahead of the vehicle. The camera 31 may be installed in the same position as the vehicle's headlights or spotlights 33, or may be installed behind the windshield glass. The camera 31 may also be a camera of a drive recorder installed in the vehicle.

[0016] The nighttime determination sensor 32 is a sensor that acquires information necessary for determining whether it is nighttime or not in the nighttime detection unit 13 of the driving assistance device 101. For example, the nighttime determination sensor 32 is a light amount sensor that measures the amount of light around the vehicle. Alternatively, the nighttime determination sensor 32 is a clock that outputs time information.

[0017] The spot illumination lamp 33 is mounted on a vehicle and emits a spot light ahead of the vehicle. The emission of spot light is called spot illumination, and illumination by spot illumination is called spot lighting. The spot illumination lamp 33 is capable of changing the direction of the spot illumination. For example, the spot illumination lamp 33 is equipped with a swing mechanism for changing the direction of the spot illumination. Alternatively, the spot illumination lamp 33 uses an array LED as a light source, and can change the direction of the spot illumination by turning on which of the multiple LEDs that make up the array LED.

[0018] Typically, two headlights are arranged as a pair on the right and left sides of the front of the vehicle in a vehicle. Similarly, two spot lighting fixtures 33 may be arranged as a pair on the right and left sides of the front of the vehicle. Alternatively, one spot lighting fixture 33 may be arranged on the right, left, or center of the vehicle.

[0019] From the viewpoint of illumination efficiency, it is desirable to install the spot illumination lamps 33 at the driver's eye height. Therefore, for example, the spot illumination lamps 33 may be installed at a location higher than the headlight position, such as one behind the rearview mirror, a pair behind the side mirrors, a pair on the A-pillars, a pair at the blinker positions, or on both sides of the roof. Note that if the spot illumination lamps 33 are installed at the same position as the camera 31, coordinate conversion processing between them is not required, thereby reducing the processing load of the illumination control unit 14.

[0020] The driving assistance device 101 includes an image acquisition unit 11, a mirror detection unit 12, a nighttime detection unit 13, and an illumination control unit 14.

[0021] The image acquisition unit 11 acquires an image captured by the camera 31 .

[0022] The mirror detection unit 12 acquires images captured by the camera 31 from the image acquisition unit 11 and detects convex mirrors installed in front of the vehicle from the acquired images. Specifically, the mirror detection unit 12 detects the position and size of the convex mirror. The position of the convex mirror is specified by the distance and direction from the vehicle. When the vehicle is not stopped, the mirror detection unit 12 detects the position of the convex mirror relative to the vehicle, which changes in real time.

[0023] The nighttime detection unit 13 determines whether it is day or night based on information acquired from the nighttime determination sensor 32. If the nighttime determination sensor 32 is a light quantity sensor that measures the amount of light around the vehicle, the nighttime detection unit 13 may determine that it is nighttime when the amount of light measured by the light quantity sensor is equal to or less than a predetermined threshold. If the nighttime determination sensor 32 is a clock, the nighttime detection unit 13 may determine that it is nighttime when the current time acquired from the clock falls within a predetermined time period, such as between 17:00 and 6:00. The nighttime detection unit 13 may determine the nighttime time period in more detail, taking into account the region or season in which the vehicle is traveling.

[0024] Based on the detection result of the mirror detection unit 12, i.e., the position and size of the convex mirror installed in front of the vehicle, the illumination control unit 14 determines an illumination area, which is an area of ​​the convex mirror to be spot illuminated by the spot illumination lamp 33. Then, the illumination control unit 14 adjusts the illumination position and the size of the illumination pattern of the spot illumination lamp 33 so that spot illumination is performed on the illumination area.

[0025] Here, the illumination control unit 14 determines the illumination area so as not to include the entire area of ​​the convex mirror. Specifically, the illumination control unit 14 divides the convex mirror into two areas: a lower area and an upper area. The lower area is the area below the convex mirror where the blind spot road surface is reflected. Alternatively, the lower area is the area where, assuming that a spot light is irradiated from the spot lighting fixture 33 onto the convex mirror, the spot light is reflected by the blind spot road surface. The upper area is the area adjacent to the upper side of the lower area and is the area where the blind spot road surface is not reflected. Alternatively, the upper area is the area where, assuming that a spot light is irradiated from the spot lighting fixture 33 onto the convex mirror, the spot light is not reflected by the blind spot road surface. Spot illumination of the upper area where the blind spot road surface is not reflected not only does not improve the visibility of the blind spot road surface but may also be a nuisance to surrounding houses. Therefore, the illumination control unit 14 mainly determines the lower area as the illumination area. In view of the above, it is desirable that the irradiation area does not include the upper area and includes the entire lower area, but it may also include a portion of the upper area. Also, the irradiation area does not have to include a portion of the lower area. That is, the irradiation area includes at least a portion of the lower area and does not include at least a portion of the upper area. It is desirable that the proportion of the irradiation area that is occupied by the lower area is greater than the proportion of the irradiation area that is occupied by the upper area.

[0026] Strictly speaking, which area of ​​the convex mirror reflects the blind spot road surface is determined by factors such as the installation height of the convex mirror, the driver's viewpoint, the curvature of the convex mirror, and the gradient of the road on which the convex mirror is installed. However, the illumination control unit 14 may ignore these factors and simply determine the illumination area by defining the lower half of the convex mirror as the lower area and the upper half as the upper area. The illumination control unit 14 controls the position of the spot illumination in real time so that spot illumination is always performed on the illumination area even while the vehicle is moving.

[0027] <A-2. Operation> Figure 2 is a flowchart showing the operation of the driving assistance device 101. The operation of the driving assistance device 101 will be described below in accordance with the flow in Figure 2. The flow in Figure 2 starts, for example, when the vehicle starts traveling. First, in step S101, the night detection unit 13 determines whether it is nighttime or not based on information from the nighttime determination sensor 32. The nighttime detection unit 13 may determine that it is nighttime based on the fact that the headlights are on.

[0028] If it is determined in step S101 that it is not nighttime, the illumination control unit 14 ends spot illumination if it is being performed in step S105. That is, the illumination control unit 14 turns off the spot illumination.

[0029] If it is determined in step S101 that it is nighttime, in step S102 the mirror detection unit 12 detects a curved mirror in front of the vehicle from the image captured by the camera 31, and if a curved mirror is detected, it also detects its position and size.

[0030] After step S102, in step S103, the illumination control unit 14 determines whether a convex mirror is present near the vehicle. If a convex mirror is detected in step S102, the illumination control unit 14 determines that the convex mirror is present near the vehicle if the distance from the vehicle to the convex mirror is equal to or less than a predetermined distance. If a convex mirror is not detected in step S102, or if the detected convex mirror is far from the vehicle, the processing of the illumination control unit 14 proceeds to step S105.

[0031] If it is determined in step S103 that a convex mirror is present near the vehicle, in step S104 the illumination control unit 14 identifies the lower region of the convex mirror based on the position and size of the convex mirror, and causes the spot lighting fixture 33 to perform spot illumination on the lower region. Note that the illumination region of the convex mirror that is subjected to spot illumination here may not include part of the lower region, or may include at least part of the upper region.

[0032] After step S104 or step S105, in step S106, the driving assistance device 101 determines whether the vehicle has stopped traveling. If the vehicle is still traveling in step S106, the processing of the driving assistance device 101 returns to step S101. If the vehicle has stopped traveling in step S106, the processing of the driving assistance device 101 ends.

[0033] 3 is a diagram showing an example of spot illumination by the driving assistance device 101. The road on which the vehicle 41 is traveling intersects with another road 48 at an intersection ahead, and there is a portion of the other road that is in a blind spot for the vehicle 41. A convex mirror 42 installed at the intersection reflects the blind spot road surface of the road 48, but it is nighttime and visibility of the convex mirror 42 is poor.

[0034] In such a situation, the driving assistance device 101 causes the spot illumination lamp 33 mounted on the vehicle 41 to emit spot light toward the lower region RB of the curved mirror 42. Note that, hereinafter, the spot illumination in this embodiment will be referred to as wide-area spot illumination to distinguish it from narrow-area spot illumination, which will be described later in a second embodiment.

[0035] The wide-area spotlight emitted from the spotlight 33 is reflected by the convex mirror 42 and illuminates the blind spot road surface. In Fig. 3, reference numeral 43 indicates the range of the wide-area spotlight that is directed onto the convex mirror 42. The area 44 of the convex mirror 42 illuminated by the wide-area spotlight (hereinafter referred to as the "wide-area spotlight area") includes the lower area RB. Reference numeral 45 indicates the range of the wide-area spotlight that is reflected from the convex mirror 42 toward the blind spot road surface. An arrow 47 indicates the optical axis of the wide-area spotlight.

[0036] This illuminates the blind spot road surface of another road 48. This illumination pattern is called a wide-area spot illumination pattern 46. As a result, the driver can see the blind spot road surface on the convex mirror 42 even at night.

[0037] 3, as a comparative example, the optical axis of the spot light irradiated from the spotlight fixture 33 onto the upper region RU of the convex mirror 42 is indicated by an arrow 49. Such spot light is reflected into the air above the blind spot road surface, and therefore does not have the effect of illuminating the blind spot road surface.

[0038] In the example of FIG. 3, the lower region RB and the upper region RU are fixedly defined as the lower half region and the upper half region of the curved mirror 42, respectively.

[0039] However, the lower region RB and the upper region RU may be dynamically determined depending on the position of the vehicle 41. For example, the illumination control unit 14 may determine the lower region RB and the upper region RU based on the height of the convex mirror 42, the height of the spotlights 33, and the positional relationship between the vehicle 41 and the convex mirror 42. As the vehicle 41 approaches the convex mirror 42, the elevation angle at which the vehicle 41 views the convex mirror 42 increases, and the area of ​​the convex mirror 42 that does not reflect the blind spot road surface expands. Therefore, it is desirable that the lower region RB shrinks below the convex mirror 42 as the vehicle 41 approaches the convex mirror 42. This reduces unnecessary spot lighting when the vehicle 41 approaches the convex mirror 42.

[0040] The illumination control unit 14 may obtain curvature information and height information of the convex mirror 42 from a map database not shown in FIG. 1 and use the information to calculate the lower region RB and the upper region RU.

[0041] Furthermore, the illumination control unit 14 may perform image recognition of the blind spot road surface reflected in the convex mirror 42, thereby spotlighting the blind spot road surface reflected in the convex mirror 42. In this case, the illumination control unit 14 performs direction change processing in consideration of the positions of the camera 31 and the spot lighting fixture 33, thereby realizing accurate spot illumination.

[0042] FIG. 4 shows an example of a convex mirror 42 and an illumination area 44 on the convex mirror 42. In the example of FIG. 4, the radius of the illumination area 44 on the convex mirror 42 by wide spot illumination is set to be equal to or less than the radius of the convex mirror 42. In addition, the brightness of the peripheral part of the illumination area 44 is smaller than the brightness of the central part. In other words, the amount of light of the wide spot illumination light is less in the peripheral part of the illumination area than in the central part. In this way, flickering in the peripheral part of the spot illumination pattern when the direction of the spot illumination changes due to vibration of the vehicle 41 is suppressed.

[0043] <A-3. Modifications> In the above example, spot illumination was performed regardless of whether the headlights were illuminating the convex mirror 42. However, the illumination control unit 14 may determine whether the headlights were illuminating the convex mirror 42, and cause the spot illumination lamp 33 to perform spot illumination only when the headlights were not illuminating the convex mirror 42.

[0044] An example of a case in which the headlights do not illuminate the convex mirror 42 is when the distance between the vehicle 41 and the convex mirror 42 is short and the illumination position of the headlights is lower than the convex mirror 42 .

[0045] Also, as shown in Figure 5, when a vehicle 41 is traveling on a curved road 50, the headlight illumination range 51 may be shifted left or right relative to the curved mirror 42, and as a result, the headlight may not illuminate the curved mirror 42.

[0046] Even at night, for example, a blind spot road surface may be sufficiently illuminated by streetlights, lighting from private homes, or headlights from other vehicles, making it sufficiently visible through the convex mirror 42. To avoid unnecessary spot illumination in such cases, the mirror detection unit 12 may detect the illuminance of the road surface reflected in the convex mirror 42 based on the image captured by the camera 31. The illumination control unit 14 may then prevent the spot illumination fixture 33 from illuminating the road surface when the road surface reflected in the convex mirror 42 has an illuminance equal to or greater than a predetermined threshold (hereinafter also referred to as a "bright road surface"). This allows energy savings in the spot illumination fixture 33.

[0047] The illumination control unit 14 may adjust the hue of the spot illumination light depending on whether the road surface reflected in the convex mirror 42 is a bright road surface or not, so that the driver can easily find a person on the road surface. For example, if the blind spot road surface reflected in the convex mirror 42 is not a bright road surface, the proportion of blue wavelength components in the spot illumination light may be increased compared to when the blind spot road surface is a bright road surface. This has the effect of making it easier for the driver to find a person on the blind spot road surface on the convex mirror 42.

[0048] Furthermore, when the blind spot road surface reflected in the convex mirror 42 is a bright road surface, the ratio of red wavelength components in the spot light may be increased compared to when the road surface is not bright. This has the effect of making it easier for the driver to find a person in the blind spot road surface on the convex mirror 42.

[0049] The mirror detection unit 12 may detect the hue of the blind spot road surface reflected in the convex mirror 42 based on the image captured by the camera 31. Then, the illumination control unit 14 may control the hue of the spot illumination light based on the hue of the blind spot road surface reflected in the convex mirror 42.

[0050] For example, the illumination control unit 14 controls the hue of the spot illumination light so that it is white when the blind spot road surface is asphalt, and is close to the hue of the blind spot road surface when the blind spot road surface is other than asphalt. Note that "when the blind spot road surface is asphalt" here may be interpreted as "when the blind spot road surface is black and white, not color."

[0051] In this way, by making the spotlight the same color as the blind spot road surface, the road outline or obstacles become more clearly visible, especially at night or in bad weather, thereby improving the visibility of pedestrians or vehicles on the blind spot road surface.

[0052] <B. Second Embodiment> <B-1. Configuration> Fig. 6 is a block diagram showing the configuration of a driving assistance device 102 according to a second embodiment. The driving assistance device 102 includes a human detection unit 16 in addition to the configuration of the driving assistance device 101 according to the first embodiment.

[0053] The human detection unit 16 detects a person reflected in the convex mirror 42 based on the image captured by the camera 31 acquired by the image acquisition unit 11. The person detected here is, for example, a pedestrian or a person riding a bicycle.

[0054] The illumination control unit 14 controls the spot illumination fixture so that spot light is illuminated toward a person detected by the person detection unit 16. In this case, the illumination area, which is the area of ​​the convex mirror illuminated by the spot light, is narrower than the illumination area when no person is detected and includes the area of ​​the convex mirror that reflects the person or the person's feet. The spot illumination performed when such a person is detected is referred to as narrow-area spot illumination to distinguish it from the wide-area spot illumination described in the first embodiment.

[0055] <B-2. Operation> Fig. 7 is a flowchart showing the operation of the driving assistance device 102. The flow in Fig. 7 is obtained by adding step S110 and step S111 to the flow in Fig. 2 described in the first embodiment.

[0056] If a curved mirror 42 near the vehicle is detected (Yes in step S103), the human detection unit 16 determines in step S110 whether or not a human is captured in the image captured by the camera 31.

[0057] If a person is shown in the image in step S110, the illumination control unit 14 causes the spot illumination lamp 33 to illuminate the periphery of the person image on the curved mirror 42 with a narrow spot in step S111.

[0058] If no person is shown in step S110, the illumination control unit 14 causes the spot illumination lamp 33 to perform wide-area spot illumination on the lower region in step S104, as in the first embodiment.

[0059] 8 and 9 are diagrams showing the state of spot illumination when a pedestrian 52 is present on a blind spot road surface. It is assumed that an image 53 of the pedestrian 52 is reflected on the convex mirror 42.

[0060] The mirror detection unit 12 detects the convex mirror 42 ahead of the vehicle 41. If the human detection unit 16 cannot detect a pedestrian 52 reflected in the convex mirror 42 at this point, the spotlight 33 emits a wide-area spot light onto the lower region RB of the convex mirror 42, as shown in Fig. 8. This illuminates the blind spot road surface including the pedestrian 52, making the image 53 of the pedestrian 52 on the convex mirror 42 easier to see.

[0061] When the human detection unit 16 detects the image 53 of the pedestrian 52 on the convex mirror 42, the illumination control unit 14 reduces the illumination range of the spot illumination to the range around the feet of the image 53 of the pedestrian 52, and narrow spot illumination is performed from the spot illumination lighting device 33. In Fig. 9, the range of the narrow spot illumination light emitted from the spot illumination lighting device 33 to the convex mirror 42 is indicated by reference numeral 54, and the range of the narrow spot illumination light reflected from the convex mirror 42 onto the feet of the pedestrian 52 is indicated by reference numeral 56.

[0062] The illumination area 55 of the convex mirror 42 by narrow spot illumination is narrower than the illumination area 44 by wide spot illumination shown in Fig. 8. Also, the illumination pattern 57 of the blind spot road surface by narrow spot illumination is narrower than the illumination pattern 46 of the blind spot road surface by wide spot illumination shown in Fig. 8. Therefore, narrow spot illumination is more effective in alerting pedestrians 52 to the presence of the vehicle 41. Also, the driver of the vehicle 41 can be more aware of the presence of pedestrian 52 in the blind spot road surface.

[0063] <B-3. Coordinate Conversion> When the camera 31 and the spot illumination fixture 33 are positioned differently, coordinate conversion is required to determine the spot illumination direction. This coordinate conversion will be described below with reference to Figs. 10 to 12.

[0064] FIG. 10 shows the optical path when a pedestrian reflected on a convex mirror 42 is observed by a camera 31. In FIG. 10, the position of the pedestrian is designated P1, and the position of the camera 31 is designated P3. Light emitted from P1 is reflected at a reflection point P2 on the convex mirror 42 and reaches P3. In other words, the optical path used by the camera 31 to monitor the image of a pedestrian reflected on the convex mirror 42 is the optical path indicated by the solid arrows P1 → P2 → P3 in FIG. 10. The normal L1 of the convex mirror 42 at P2 is included in a plane PL1 that passes through P1, P2, and P3. The angle of incidence θ1 at P2 is equal to the angle of reflection θ2. The intersection of the normal L1 and the line segment P1-P3 is designated P4.

[0065] Next, using Fig. 11, consider the optical path when spot light is emitted from spot lighting fixture 33, which is located at a height h lower than camera 31, toward reflection point P2. If the position of spot lighting fixture 33 is P5, the spot light travels within plane PL2 defined by normal line L1 to reflection point P2 and point P5, so that the angle of incidence θ3 and the angle of reflection θ4 are equal. As a result, as shown by the dashed arrow in Fig. 11, the spot light passes above P1, and therefore cannot illuminate the pedestrian located at P1.

[0066] Therefore, in order to irradiate a spotlight on the pedestrian located at P1 detected by the camera 31 located at P3, the irradiation control unit 14 sets a reflection point P6 of the spotlight at a position lower than the reflection point P2, as shown in Fig. 12. The spotlight luminaire 33 performs spotlight irradiation toward the reflection point P6. The spotlight travels within the plane PL3 determined by the normal L2 of the reflection point P6 and the point P5 so that the angle of incidence θ5 and the angle of reflection θ6 are equal, and reaches P1 where the pedestrian is located. This achieves spotlighting of the pedestrian.

[0067] When the spotlight 33 applies narrow spot illumination to the curved mirror 42, the illumination area due to the narrow spot illumination is captured in the image captured by the camera 31. Therefore, the mirror detection unit 12 can detect the position of the illumination area from the captured image. Based on this position, the illumination control unit 14 can dynamically adjust the position of the illumination area to an appropriate position.

[0068] Furthermore, the illumination control unit 14 may set the illumination area by narrow spot illumination so as not to include the area of ​​the convex mirror 42 in which a person's eyes are reflected. If the illumination area is the area in which a person's feet are reflected, it is possible to prevent a person illuminated by narrow spot illumination from feeling dazzled.

[0069] The wide spot illumination and the narrow spot illumination may be used in combination. For example, the spot illumination fixture 33 may perform wide spot illumination and then switch to narrow spot illumination. The narrow spot illumination may also be flashing illumination.

[0070] The human detection unit 16 may detect that a pedestrian is holding a flashlight or that a bicycle has its lights on from the image captured by the camera 31. In such cases, the driver can confirm the presence of the person through the convex mirror 42, so the illumination control unit 14 does not need to switch from wide-area spot illumination to narrow-area spot illumination.

[0071] <B-4. Modifications> The illumination pattern by narrow spot illumination is not limited to a circle as shown in Fig. 9, and may be other shapes or characters. Furthermore, the pattern of narrow spot illumination that is illuminated on the area of ​​the convex mirror 42 that reflects a person's feet may be an arrow pattern that indicates the traveling direction of the vehicle 41 when reflected from the convex mirror 42 onto the road surface.

[0072] When the human detection unit 16 detects a human on the blind spot road surface, the illumination control unit 14 may control the spot lighting fixture 33 to perform intermediate illumination, in which spot light is irradiated onto an area visible to both the vehicle 41 and the human (hereinafter referred to as the intermediate area), in addition to the wide-area spot illumination or narrow-area spot illumination described above.

[0073] FIG. 13 illustrates the manner in which narrow-area spot illumination and intermediate illumination are performed. FIG. 13 illustrates a case in which a vehicle 41 is about to turn right at an intersection ahead. A convex mirror 42R that reflects the road surface in the right blind spot and a convex mirror 42L that reflects the road surface in the left blind spot are installed at the intersection. The spotlight fixture 33 performs narrow-area spot illumination on the convex mirror 42R to illuminate a pedestrian 52 in the road surface in the right blind spot. On the road surface ahead of the vehicle 41, there is an intermediate area 59 that is visible to the pedestrian 52. The illumination control unit 14 controls the spotlight fixture 33 to illuminate the intermediate area 59 with spot light. The illumination pattern 60 formed by spotlighting the intermediate area 59 is an arrow pattern that indicates the traveling direction of the vehicle 41. The pedestrian 52 who sees the illumination pattern 60 can recognize that the vehicle 41 is turning toward them.

[0074] <C. Embodiment 3> <C-1. Configuration> Fig. 14 is a block diagram showing the configuration of a driving assistance device 103 according to Embodiment 3. The driving assistance device 103 includes a gradient detection unit 17 in addition to the configuration of the driving assistance device 101 according to Embodiment 1. Furthermore, the driving assistance device 103 is connected to a map information device 34 in addition to the camera 31, the nighttime determination sensor 32, and the spot illumination lamp 33, and is configured to be able to use these.

[0075] The map information device 34 stores map information, which includes road gradient information.

[0076] The gradient detection unit 17 detects the gradient of the road on which the convex mirror to be illuminated is installed, and outputs the gradient to the illumination control unit 14. The gradient detection unit 17 may detect the gradient of the road based on gradient information acquired from the map information device 34. Alternatively, the gradient detection unit 17 may estimate the gradient of the road on which the convex mirror is installed from an image captured by the camera 31, or may estimate the gradient of the road on which the convex mirror is installed from road surface gradient information for the current traveling position held by a vehicle attitude control device of the vehicle 41 (not shown).

[0077] The illumination control unit 14 determines the illumination area of ​​the convex mirror 42 in accordance with the gradient of the road detected by the gradient detection unit 17 .

[0078] <C-2. Operation> Figure 15 is a flowchart showing the operation of the driving assistance device 103. Compared to the flow of Figure 2 described in embodiment 1, the flow of Figure 15 includes steps S120 to S123 instead of step S104. The operation of the driving assistance device 103 will be described below, focusing on the differences from embodiment 1.

[0079] If the mirror detection unit 12 detects a curve mirror ahead of the vehicle 41 and the curve mirror is close to the vehicle 41 (Yes in step S103), in step S120 the gradient detection unit 17 determines whether the road on which the curve mirror is installed is a curved or bending road.

[0080] If it is determined in step S120 that the road on which the convex mirror is installed is not a curved or winding road, the processing of the driving assistance device 103 proceeds to step S105.

[0081] If it is determined in step S120 that the road on which the convex mirror is installed is a curved or bending road, then in step S121 the gradient detection unit 17 detects the road direction of the road on which the convex mirror is installed from the map information stored in the map information device 34 or the image captured by the camera 31. The road direction refers to the direction of the curve or bending.

[0082] After step S121, in step S122, the gradient detection unit 17 detects the gradient of the road on which the convex mirror is installed from the gradient information included in the map information stored in the map information device 34.

[0083] After step S122, in step S123, the illumination control unit 14 sets the illumination range of the curve mirror 42 based on the road direction detected in step S121 and the road gradient detected in step S122, and causes the spot lighting fixture 33 to perform wide-area spot illumination on the set illumination range.

[0084] Next, a method for setting the illumination area of ​​wide-area spot illumination in accordance with the gradient of the road will be described with reference to Figures 16 to 18. Figures 16 to 18 show the mirror image of a convex mirror 42 installed on a left curve where the road gradient varies. When a vehicle is traveling on a horizontal left curve with no gradient, the blind spot road surface is reflected in the lower half of the convex mirror 42, with the dotted line A-A' as the boundary, as shown in Figure 16. Therefore, the illumination control unit 14 sets the area above the dotted line A-A' as an upper area RU and the area below the dotted line A-A' as a lower area RB, and sets the lower area RB as the illumination area of ​​the wide-area spot illumination.

[0085] When a vehicle is traveling on an uphill left curve, the blind spot road surface is reflected in the diagonally lower half of the convex mirror 42, with the dotted line B-B' as the boundary, as shown in Figure 17. Therefore, the illumination control unit 14 sets the area above the dotted line B-B' as an upper region RU and the area below the dotted line B-B' as a lower region RB, and sets the lower region RB as the illumination area for the wide-area spotlight. In this case, the inclination of the dotted line B-B' as viewed from the dotted line A-A', which is the horizontal axis, is in the range of -45° to -60°.

[0086] When a vehicle is traveling on a downward-sloping left curve, the blind spot road surface is reflected in the diagonally lower half of the convex mirror 42, with the dotted line CC' as the boundary, as shown in Figure 18. Therefore, the illumination control unit 14 sets the area above the dotted line CC' as an upper region RU and the area below the dotted line CC' as a lower region RB, and sets the lower region RB as the illumination area for the wide-area spotlight. In this case, the inclination of the dotted line CC' as viewed from the dotted line A-A', which is the horizontal axis, is in the range of 45° to 60°.

[0087] 16 to 18 have described a method for setting the illumination area of ​​the wide-area spotlight using a left curve as an example. When the road on which the convex mirror 42 is installed is a right curve, the illumination area is set symmetrically to the illumination area shown in Fig. 16 to 18. In this way, the driving assistance device 103 determines the illumination area of ​​the spotlight according to the gradient of the road on which the convex mirror 42 is installed, so that it can appropriately illuminate only the blind spot road surface regardless of the gradient, and can efficiently assist the driver in viewing the blind spot road surface using the convex mirror 42.

[0088] <D. Hardware Configuration> The image acquisition unit 11, mirror detection unit 12, night detection unit 13, illumination control unit 14, human detection unit 16, and gradient detection unit 17 in the driving assistance devices 101, 102, and 103 described above are realized by a processing circuit 81 shown in FIG. 19 . That is, the processing circuit 81 includes the image acquisition unit 11, mirror detection unit 12, night detection unit 13, illumination control unit 14, human detection unit 16, and gradient detection unit 17 (hereinafter, referred to as the “image acquisition unit 11, etc.”). The processing circuit 81 may be implemented by dedicated hardware or by a processor that executes a program stored in memory. The processor may be, for example, a central processing unit, a processing unit, an arithmetic unit, a microprocessor, a microcomputer, a DSP (Digital Signal Processor), or the like.

[0089] When the processing circuitry 81 is dedicated hardware, the processing circuitry 81 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. The functions of each unit, such as the image acquisition unit 11, may be realized by multiple processing circuits 81, or the functions of each unit may be realized together by a single processing circuit.

[0090] When the processing circuitry 81 is a processor, the functions of the image acquisition unit 11 and the like are realized by a combination of software, etc. (software, firmware, or software and firmware). The software, etc. is written as a program and stored in a memory. As shown in FIG. 20 , the processor 82 applied to the processing circuitry 81 realizes the functions of each unit by reading and executing a program stored in a memory 83. That is, the driving assistance devices 101, 102, and 103 include a memory 83 for storing a program that, when executed by the processing circuitry 81, results in the function of the image acquisition unit 11 and the like being executed. In other words, the program can be said to cause a computer to execute a procedure or method of the image acquisition unit 11 and the like. Here, the memory 83 may be, for example, a non-volatile or volatile semiconductor memory such as a RAM (Random Access Memory), a ROM (Read Only Memory), a flash memory, an EPROM (Erasable Programmable Read Only Memory), or an EEPROM (Electrically Erasable Programmable Read Only Memory), a HDD (Hard Disk Drive), a magnetic disk, a flexible disk, an optical disk, a compact disk, a mini disk, a DVD (Digital Versatile Disk) and its drive device, or any storage medium that will be used in the future.

[0091] The above describes a configuration in which each function of the image acquisition unit 11 and the like is realized either by hardware or software, etc. However, the present invention is not limited to this, and a configuration in which part of the image acquisition unit 11 and the like is realized by dedicated hardware and another part is realized by software, etc. For example, the function of the irradiation control unit 14 can be realized by a processing circuit as dedicated hardware, and the other functions can be realized by the processing circuit 81 as the processor 82 reading and executing programs stored in the memory 83.

[0092] As described above, the processing circuit can realize each of the above-described functions by hardware, software, or a combination of these.

[0093] Furthermore, although the driving assistance devices 101, 102, and 103 have been described above as in-vehicle devices, they may also be applied to a system constructed by appropriately combining a PND (Portable Navigation Device), a communication terminal (e.g., a mobile terminal such as a mobile phone, a smartphone, or a tablet), the functions of applications installed thereon, a server, etc. In this case, the functions or components of the driving assistance devices 101, 102, and 103 described above may be distributed among the devices that construct the system, or may be concentrated in one of the devices.

[0094] It should be noted that the embodiments can be freely combined, and each embodiment can be modified or omitted as appropriate. The above description is an example in all respects. It is understood that countless variations not illustrated can be envisioned.

[0095] 11 Image acquisition unit, 12 Mirror detection unit, 13 Night detection unit, 14 Illumination control unit, 16 Person detection unit, 17 Gradient detection unit, 31 Camera, 32 Night determination sensor, 33 Spot lighting fixture, 34 Map information device, 41 Vehicle, 42 Convex mirror, 42L Convex mirror, 42R Convex mirror, 81 Processing circuit, 82 Processor, 83 Memory, 101, 102, 103 Driving assistance device, RB Lower region, RU Upper region.

Claims

1. A driving assistance device comprising: a mirror detection unit that detects a convex mirror in front of a vehicle based on an image captured by a camera mounted on the vehicle; a nighttime detection unit that detects that it is nighttime; and an illumination control unit that causes a spotlight to be emitted onto the convex mirror detected at night using a spotlight fixture mounted on the vehicle that illuminates the area in front of the vehicle, wherein the mirror surface of the convex mirror is composed of a lower area and an upper area adjacent to the upper side of the lower area, and the illumination area of ​​the convex mirror that is the area onto which the spotlight is emitted does not include at least a part of the upper area, but includes at least a part of the lower area.

2. A driving assistance device as described in claim 1, wherein the lower region is a region where, assuming that spot light is irradiated from the spot lighting fixture onto the convex mirror, the spot light is reflected by a blind spot road surface, and the upper region is a region where, assuming that spot light is irradiated from the spot lighting fixture onto the convex mirror, the spot light is not reflected by a blind spot road surface.

3. The driving assistance device according to claim 1, wherein the illumination area narrows as the vehicle approaches the curve mirror.

4. The driving assistance device according to claim 1, wherein the radius of the illumination area is equal to or smaller than the radius of the convex mirror, and the amount of spot light is less in the periphery of the illumination area than in the center.

5. The driving assistance device according to claim 1, wherein the illumination control unit controls the spotlight fixture to emit spot light only when the headlights of the vehicle do not illuminate the curved mirror.

6. The driving assistance device according to claim 1, wherein the mirror detection unit detects the illuminance of the blind spot road surface reflected in the convex mirror based on the captured image, and the illumination control unit does not cause the spot lighting fixture to emit spot light when the blind spot road surface reflected in the convex mirror is a bright road surface with an illuminance equal to or greater than a predetermined threshold.

7. The driving assistance device described in claim 1, wherein the mirror detection unit detects the illuminance of the blind spot road surface reflected in the convex mirror based on the captured image, and the illumination control unit increases the ratio of red wavelength components in the spot light when the blind spot road surface reflected in the convex mirror is a bright road surface with an illuminance equal to or greater than a predetermined threshold, compared to when the blind spot road surface is not a bright road surface.

8. The driving assistance device described in claim 1, wherein the mirror detection unit detects the illuminance of the blind spot road surface reflected in the convex mirror based on the captured image, and the illumination control unit increases the ratio of blue wavelength components in the spot light when the blind spot road surface reflected in the convex mirror is not a bright road surface with an illuminance equal to or greater than a predetermined threshold, compared to when the blind spot road surface is a bright road surface.

9. The driving assistance device described in claim 1, wherein the mirror detection unit acquires the hue of the blind spot road surface reflected in the convex mirror based on the captured image, and the illumination control unit controls the hue of the spot light based on the hue of the blind spot road surface reflected in the convex mirror.

10. A driving assistance device as described in claim 1, further comprising a person detection unit that detects a person reflected in the convex mirror based on the captured image, wherein the illumination area when the person is detected is narrower than the illumination area when the person is not detected, and includes an area of ​​the convex mirror that reflects the person or the person's feet.

11. The driving assistance device according to claim 10, wherein the illuminated area when the person is detected does not include an area of ​​the convex mirror in which the person's eyes are reflected.

12. A driving assistance device as described in claim 10, wherein the pattern irradiated from the spotlight fixture onto the area of ​​the convex mirror in which the person's feet are reflected becomes an arrow pattern indicating the direction of travel of the vehicle when reflected from the convex mirror onto the road surface.

13. A driving assistance device as described in claim 10, wherein, when the person is detected, the illumination control unit uses the spot lighting fixture to illuminate a middle area of ​​the road surface ahead of the vehicle that is visible to the person, in addition to illuminating the curved mirror with spot light.

14. The driving assistance device according to claim 13, wherein the pattern of the spotlight irradiated onto the intermediate region is a pattern that represents the traveling direction of the vehicle.

15. The driving assistance device according to claim 1, further comprising a gradient detection unit that detects the gradient of a road on which the convex mirror is installed, and the illumination area is determined according to the gradient.

16. A driving assistance method that detects a convex mirror in front of a vehicle based on an image captured by a camera mounted on the vehicle, detects that it is nighttime, and uses a spotlight fixture mounted on the vehicle to illuminate the area in front of the vehicle, to illuminate the convex mirror detected at night with a spotlight, wherein the mirror surface of the convex mirror is composed of a lower area and an upper area adjacent to the upper side of the lower area, and the illuminated area of ​​the convex mirror onto which the spotlight is illuminated does not include at least a part of the upper area, but includes at least a part of the lower area.

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