Driver assistance systems

Abstract

To make it possible to suppress dazzling of a driver of at least one of the own vehicle and a front vehicle due to a reflection of headlamp irradiation light by a light reflecting structure while suppressing a deterioration of detection accuracy of a camera in a driving support system.SOLUTION: A driving support system comprises a control device and a camera. The control device executes a light distribution control for controlling a light distribution of a headlamp of the own vehicle according to a position of a front vehicle with respect to the own vehicle. The camera images a front of the own vehicle. When a light reflecting structure is detected within a predetermined lateral distance from the own vehicle, the control device shortens an exposure time of the camera and then executes the light distribution control.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a driving assistance system. [Background technology]

[0002] Patent Document 1 discloses a vehicle lighting device that controls the light distribution of headlamps according to the position of a vehicle ahead relative to the vehicle. This light distribution control controls the light distribution pattern and the direction of irradiation of the light distribution pattern to prevent glare (dazzling) from being caused to the vehicle ahead when high beam is selected. Furthermore, the vehicle lighting device is configured to suspend the light distribution control when a light-reflecting structure (e.g., a guardrail) is detected within a predetermined lateral distance from the vehicle. Suspension of the light distribution control is achieved by switching the light distribution pattern from high beam to low beam. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-196999 Summary of the Invention [Problem to be solved by the invention]

[0004] If light distribution control is not always performed (for example, always using low beam) when a light-reflecting structure is detected within a specified lateral distance from the vehicle, even if dazzle for the driver of at least one of the vehicle itself and the vehicle ahead can be reduced, there is a risk that the camera's detection accuracy will decrease due to a decrease in the amount of light emitted by the headlights.

[0005] The present invention has been made in consideration of the above-mentioned problems, and aims to provide a driving assistance system that can suppress dazzle to the driver of at least one of the vehicle itself and the vehicle ahead caused by reflection of headlamp light by light-reflecting structures, while suppressing a decrease in the detection accuracy of the camera. [Means for solving the problem]

[0006] A driving assistance system according to the present invention includes a control device and a camera. The control device performs light distribution control to control the light distribution of headlamps of a host vehicle in accordance with the position of a vehicle ahead relative to the host vehicle. The camera captures an image of the area ahead of the host vehicle. When the control device detects a light-reflecting structure within a predetermined lateral distance from the vehicle, the control device shortens the exposure time of the camera and then performs light distribution control. [Effects of the Invention]

[0007] According to the present invention, when a light reflective structure is detected within a predetermined lateral distance from the host vehicle, the exposure time of the camera 10 is shortened and light distribution control is executed. As a result, compared to an example in which light distribution control is not always executed when a light reflective structure is detected within a predetermined lateral distance from the host vehicle, it is possible to prevent light distribution control from being disabled in scenes where shortening the camera exposure time would not cause overexposure. Therefore, it is possible to suppress dazzle to the driver of at least one of the host vehicle and the vehicle ahead caused by reflection of headlamp light by the light reflective structure, while suppressing a decrease in the detection accuracy of the camera due to the disabled light distribution control. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a diagram schematically illustrating a configuration example of a main part of a driving assistance system according to a first embodiment. [Figure 2] 4 is a flowchart showing a flow of processing related to light distribution control according to the first embodiment. [Figure 3] 10 is a flowchart showing a flow of processing related to light distribution control according to the second embodiment. [Figure 4] 10 is a flowchart showing a flow of processing related to light distribution control according to the third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the embodiments described below, when the number, quantity, amount, range, etc. of each element is mentioned, the present invention is not limited to the mentioned numbers unless otherwise specified or clearly specified in principle. Furthermore, the structures, steps, etc. described in the embodiments described below are not necessarily essential to the present invention unless otherwise specified or clearly specified in principle.

[0010] 1. First Embodiment 1-1. Example of a driving assistance system configuration 1 is a diagram schematically illustrating a configuration example of a main part of a driving assistance system 1 according to the first embodiment. The driving assistance system 1 is applied to a vehicle. More specifically, the driving assistance system 1 corresponds to an automated driving system (AD) or an advanced driving assistance system (ADAS) for a vehicle.

[0011] A vehicle (host vehicle) equipped with a driving assistance system 1 is equipped with a headlamp 2. The headlamp 2 is configured to be able to select between a low beam and a high beam for irradiating visible light toward the area ahead of the host vehicle. For "light distribution control" described below, the headlamp 2 includes, for example, a swivel actuator and a shade drive actuator. The swivel actuator is configured to be able to change the direction of the optical axis of the headlamp 2 within a substantially horizontal plane. The shade drive actuator controls the open / close state of a lampshade provided in the headlamp 2. The lampshade is provided to form a light distribution pattern that blocks part of the light emitted from the bulb of the headlamp 2.

[0012] The driving assistance system 1 in the example shown in FIG. 1 includes a camera 10, a radar 12, a lidar 14, a GNSS (Global Navigation Satellite System) receiver 16, a vehicle speed sensor 18, a yaw rate sensor 20, and a control device 30.

[0013] The camera 10 is an imaging element such as a CCD or CMOS, and is mounted on a vehicle so as to capture an image of the area ahead of the vehicle through the windshield of the vehicle. The camera 10 is used for vehicle driving assistance (including the realization of autonomous driving). More specifically, the image captured by the camera 10 is used, for example, to identify an object (e.g., a pedestrian) being imaged. The camera 10 is also configured to be able to change the exposure time t based on a command from the control device 30.

[0014] The radar 12 and the lidar 14, together with the camera 10, are mounted on the vehicle to acquire information about the vehicle's surrounding environment and surrounding objects. The GNSS receiver 16 is used to acquire the position information of the vehicle. The vehicle speed sensor 18 and the yaw rate sensor 20 are mounted on the vehicle to acquire information about the behavior of the vehicle.

[0015] The control device 30 controls the headlamps 2 and the camera 10. Specifically, the control of the headlamps 2 by the control device 30 includes "light distribution control" described below. The control of the camera 10 by the control device 30 includes "control of the exposure time t" of the camera 10. The control device 30 has a processor and a storage device. The storage device stores various programs related to the control of the headlamps 2 and the camera 10 described above. The various programs are executed by the processor to realize the above-mentioned controls.

[0016] 1-2. Control of the first embodiment 1-2-1.Outline of light distribution control The control device 30 executes light distribution control to control the light distribution of the headlamps 2 according to the position of a vehicle ahead relative to the host vehicle. According to this light distribution control, the light distribution is controlled so as to reduce dazzle to the driver of a vehicle ahead (e.g., an oncoming vehicle) when high beams are selected. Note that the detection of the vehicle ahead can be performed, for example, by using image processing of an image captured by the camera 10. The position of the vehicle ahead can also be calculated using the image from the camera 10.

[0017] More specifically, in the light distribution control, a light distribution pattern is controlled so as to reduce dazzle to the driver of the vehicle ahead. For example, various light distribution patterns are realized by changing the open / closed state of the lampshade using a shade driving actuator (see, for example, Japanese Patent Application Laid-Open No. 2012-196999). In addition, the irradiation direction of the light distribution pattern may be controlled so as to reduce dazzle to the driver of the vehicle ahead. The control of the irradiation direction is realized, for example, by changing the optical axis direction using the swivel actuator.

[0018] 1-2-2. Characteristic parts Roadside structures with high light reflectivity, such as guardrails and walls, are examples of light-reflecting structures that reflect the light emitted by the headlamps 2. More specifically, guardrails, which are a typical example of light-reflecting structures, are reflective members installed on the side of a road and are an example of wall-shaped reflective members that extend along the longitudinal direction of the road. If light distribution control is continued without special consideration when such a light-reflecting structure is near the vehicle, there is a risk that the light reflected from the light-reflecting structure will dazzle at least one of the drivers of the vehicle and the vehicle ahead.

[0019] To address the above-mentioned issues, it is conceivable to discontinue light distribution control when a light-reflecting structure such as a guardrail is detected, as in the technology described in Patent Document 1. However, if light distribution control is not always performed (for example, always using low beams) when a light-reflecting structure is detected within a predetermined lateral distance from the vehicle, even if dazzling to the driver of at least one of the vehicle itself and the vehicle ahead can be reduced, there is a risk that the detection accuracy of the camera 10 will decrease due to a decrease in the amount of light emitted by the headlamp 2. Specifically, if there is an object (for example, a pedestrian) ahead in the direction of travel of the vehicle itself that the camera 10 should detect, switching to low beams may result in insufficient light, leading to the object not being detected.

[0020] Therefore, in this embodiment, the following control is executed to suppress the deterioration of the detection accuracy of the camera 10 while suppressing dazzling of the driver of at least one of the vehicle and the vehicle ahead caused by the reflection of the light emitted by the headlamp 2 by the light reflecting structure. That is, when the control device 30 detects a light reflecting structure within a predetermined lateral distance from the vehicle, it shortens the exposure time t of the camera 10 and executes (continues) the light distribution control.

[0021] 1-2-3. Processing flow by the control device 2 is a flowchart showing the flow of processing related to light distribution control according to Embodiment 1. The processing of this flowchart is executed repeatedly while the driver is selecting high beams, for example.

[0022] 2, the control device 30 (processor) first determines whether a light reflective structure has been detected in step S100. For example, when a state in which the distance to an object on the side of the vehicle measured by the radar 12 or the lidar 14 is within a predetermined distance continues for a predetermined traveling distance or for a predetermined time or longer, the control device 30 detects the object on the side of the vehicle as a light reflective structure.

[0023] If a light reflecting structure is not detected in step S100, the process proceeds to step S102. In step S102, the control device 30 executes the above-described light distribution control. On the other hand, if a light reflecting structure is detected in step S100, the process proceeds to step S104.

[0024] In step S104, the control device 30 determines whether the light reflecting structure detected in step S100 is located within a predetermined lateral distance D0 from the vehicle. The predetermined lateral distance D0 here refers to the distance between the vehicle and the light reflecting structure in the width direction of the road on which the vehicle is traveling. This predetermined lateral distance D0 may be set in advance as a lateral distance threshold for determining whether blown-out highlights will occur in the image of the camera 10 due to the presence of the light reflecting structure during light distribution control, for example, under conditions where the exposure time t of the camera 10 is a predetermined basic value. The lateral distance compared with the predetermined lateral distance D0 in this determination can also be detected using, for example, the radar 12 or the lidar 14.

[0025] If the determination result in step S104 is negative, the process proceeds to step S102, where light distribution control is executed. On the other hand, if the determination result in step S104 is positive, the process proceeds to step S106.

[0026] The camera 10 repeatedly captures images at a predetermined imaging cycle. In step S106, for the light reflecting structure detected in step S100, the control device 30 acquires the luminance of the portion of the light reflecting structure in the latest image of the area in front of the vehicle captured by the camera 10 from the image information. The control device 30 then determines whether the acquired luminance is equal to or greater than a predetermined luminance value. This predetermined luminance value is set in advance, for example, as a threshold value for determining whether the portion of the light reflecting structure in the image is overexposed.

[0027] If the determination result in step S106 is negative, that is, if it can be determined that the portion of the light reflecting structure in the camera image is not overexposed, the process proceeds to step S102, where light distribution control is executed. On the other hand, if the determination result in step S106 is positive, the process proceeds to step S108.

[0028] In step S108, the control device 30 controls the camera 10 so that the exposure time t (shutter time) is shortened by a predetermined value X (ms). Thereafter, the process proceeds to step S110.

[0029] In step S110, the control device 30 determines whether the current exposure time t is less than a predetermined time t1. This predetermined time t1 is, for example, the minimum value for the exposure time t under control. While the exposure time t is equal to or greater than the predetermined time t1 in step S110, the processing from step S106 onward is repeatedly executed. If the determination result of step S106 becomes positive and the exposure time t is shortened by the predetermined value X, and the determination result of step S106 changes to "No," the processing proceeds to step S102, and light distribution control is executed. On the other hand, if the determination result of step S106 does not change to "No" even after the exposure time t is shortened by the predetermined value X after the determination result of step S106 becomes positive, the exposure time t is further shortened by the predetermined value X in step S108.

[0030] Also, if the exposure time t falls below the predetermined time t1 (reaches the predetermined time t1) in step S110, the process proceeds to step S102, where light distribution control is executed.

[0031] 1-3.Effects As described above, according to the control of this embodiment, when a light reflecting structure is detected within a predetermined lateral distance D0 from the host vehicle, the exposure time t of the camera 10 is shortened and light distribution control is executed. As a result, compared to an example in which light distribution control is not always executed when a light reflecting structure is detected within the predetermined lateral distance D0 from the host vehicle, it is possible to prevent light distribution control from being disabled (for example, switching to low beam) in scenes where shortening the exposure time t would not cause overexposure. Therefore, it is possible to suppress dazzle to the driver of at least one of the host vehicle and the vehicle ahead caused by reflection of headlamp light by the light reflecting structure, while suppressing a decrease in the detection accuracy of the camera 10 caused by the light distribution control being disabled.

[0032] 2, the exposure time t is changed according to the pixel value (brightness) of the portion of the light reflecting structure in the image of the camera 10. This makes it possible to extend the operating time of the high beam while suppressing a decrease in the detection accuracy of the camera 10.

[0033] 2, when a light reflecting structure is detected within a predetermined lateral distance D0 from the vehicle (step S104; Yes), it is determined in step S106 whether the brightness of the portion of the light reflecting structure in the latest camera image is equal to or greater than a predetermined brightness value before shortening the exposure time t by the predetermined value X. If the determination result is negative (step S106; No), the exposure time t is not shortened and light distribution control is executed. In other words, it is possible to prevent the exposure time t from being shortened more than necessary.

[0034] 2. Second Embodiment The driving assistance system according to the second embodiment differs from the driving assistance system 1 according to the first embodiment in that the processing of the flowchart shown in FIG. 3 is executed instead of the processing of the flowchart shown in FIG.

[0035] Fig. 3 is a flowchart showing the flow of processing related to light distribution control according to embodiment 2. In this flowchart, the following steps S200 to S204 are added to the flowchart shown in Fig. 2. In Fig. 3, if the determination result in step S106 is affirmative, the processing proceeds to step S200.

[0036] In step S200, the control device 30 (processor) determines whether or not blown-out highlights (more specifically, blown-out highlights of the light-reflecting structure detected in step S100) can be avoided even if the exposure time t of the camera 10 is shortened to the limit value (minimum value). This determination can be made, for example, based on brightness information of the image of the camera 10 acquired while temporarily controlling the exposure time t of the camera 10 to the above-mentioned limit value.

[0037] If the determination result in step S200 is affirmative, that is, if it is determined that whiteout cannot be avoided even if the exposure time t is shortened to the limit value (there is a risk that the detectability of objects around the detected light reflecting structure cannot be ensured), the process proceeds to step S202. In step S202, the control device 30 stops the light distribution control. Specifically, for example, a switch to low beam is executed.

[0038] On the other hand, if the determination result in step S200 is negative, that is, if it is determined that it is possible to avoid blown-out highlights (ensuring the detectability of surrounding objects by camera 10) by shortening the exposure time t within the range up to the limit value, the process proceeds to step S204. The process of step S204 is the same as the process of step S106. That is, the processes from step S106 onwards are the same as the processes of steps S106 to S110 shown in FIG. 2.

[0039] The processing related to the "light distribution control" according to the present invention may be executed as in the example of the processing of the flowchart shown in FIG. 3 described above.

[0040] Furthermore, in order to determine whether to proceed to the processing of step S202 (stopping light distribution control), the following processing may be executed together with or instead of the processing of step S200 described above. That is, it may be determined whether shortening the exposure time t to a limit value will increase the adverse effect on the detectability of other objects (more specifically, objects other than objects (objects affected by blown-out highlights) surrounding the light reflecting structure detected in step S100). Then, a positive result of this determination may be used as a condition for proceeding to step S202. In addition, in an example using such a determination, the minimum value of the exposure time t that can suppress the adverse effect on the detectability of the above-mentioned "other objects" to an acceptable level may be calculated (for example, obtained in advance), and light distribution control may be continued within a range in which the exposure time t does not fall below this minimum value.

[0041] 3. Embodiment 3 The driving assistance system according to the third embodiment differs from the driving assistance system 1 according to the first embodiment in that the processing of the flowchart shown in FIG. 4 is executed instead of the processing of the flowchart shown in FIG.

[0042] Fig. 4 is a flowchart showing the flow of processing related to light distribution control according to embodiment 3. The processing of this flowchart differs from the processing of the flowchart shown in Fig. 2 in that step S202 is added as in Fig. 3, and the processing of steps S300 and S302 are added instead of the processing of step S104.

[0043] In step S300, the control device 30 (processor) determines whether the light reflecting structure detected in step S100 is present within a first predetermined lateral distance D1 from the vehicle. If the result of this determination is negative, the process proceeds to step S102, where light distribution control is executed. On the other hand, if the result of this determination is positive, the process proceeds to step S302.

[0044] In step S302, the control device 30 determines whether or not the light reflecting structure detected in step S100 is present within a second predetermined lateral distance D2 (<first predetermined lateral distance D1) from the vehicle.

[0045] If the determination result of step S302 is negative, that is, if the lateral distance from the vehicle to the light reflecting structure is shorter than the first predetermined lateral distance D1 but equal to or greater than the second predetermined lateral distance D2, the process proceeds to step S106. The process from step S106 onwards is the same as in the first embodiment.

[0046] On the other hand, if the determination result of step S302 is positive, that is, if the lateral distance from the light reflecting structure to the subject vehicle is shorter than the second predetermined lateral distance D2, the process proceeds to step S202, and the light distribution control is discontinued. That is, in this embodiment, even if the exposure time t is within the first predetermined lateral distance D1 for determining whether or not to continue the light distribution control while shortening the exposure time t, if the distance falls below a second predetermined lateral distance that is smaller than the first predetermined lateral distance D1, it is determined that there is a high risk of dazzling the driver of at least one of the subject vehicle and the vehicle ahead, and the light distribution control is discontinued.

[0047] The process of the third embodiment may be combined with the process of the second embodiment. Specifically, after the process of step S106 in Fig. 4, the processes of step S200 and step S204 similar to those in Fig. 3 may be added.

[0048] The processing related to the "light distribution control" according to the present invention may be executed as in the example of the processing of the flowchart shown in FIG. 3 described above. [Explanation of symbols]

[0049] 1. Driving assistance systems 2 headlamps 10 Camera 12 Radar 14 Rider 16 GNSS receivers 18 Vehicle speed sensor 20 Yaw rate sensor 30 Control device

Claims

[Claim 1] a control device that executes light distribution control to control light distribution of headlamps of the host vehicle in accordance with the position of a vehicle ahead relative to the host vehicle; a camera that captures an image ahead of the vehicle; A driving assistance system comprising: When the control device detects a light reflecting structure within a predetermined lateral distance from the host vehicle, If it is not possible to avoid blown-out highlights in the image of the camera due to the presence of the light reflecting structure even when the exposure time of the camera is shortened to the limit value, the light distribution control is stopped, If the blown-out highlights can be avoided by shortening the exposure time within the range up to the limit value, the exposure time is shortened and then the light distribution control is performed. A driving assistance system characterized by:

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