Stop Line Exploration Device

Abstract

To appropriately search for a stop line.SOLUTION: A stop line search device (20) includes: image acquisition means (21) for acquiring an image obtained by photographing a front side of an own vehicle (1); traffic light detection means (22) for detecting a traffic light installed at an intersection in front of the own vehicle based on the image; and setting means (23) for setting a stop line search area for searching for a stop line related to the intersection based on a detection result which indicates whether or not a near side traffic light on a near side of the intersection when viewed from the own vehicle is detected by the traffic light detection means in a case where a depth side traffic light on a depth side of the intersection when viewed from the own vehicle is detected by the traffic light detection means.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to the technical field of stop line search devices. [Background technology]

[0002] As an example of this type of device, a device has been proposed that switches to a stop line recognition mode when a traffic light ahead of the vehicle, which is recognized from an image, is red (see Patent Document 1). Another related prior art document is Patent Document 2. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-123613 [Patent Document 2] Japanese Patent Publication No. 2021-033772 Summary of the Invention [Problem to be solved by the invention]

[0004] When a stop line is recognized from an image, depending on the condition of the road surface reflected in the image, something that is not a stop line may be mistakenly recognized as a stop line, and there is room for improvement in the technology described in the prior art documents.

[0005] The present invention has been made in consideration of the above circumstances, and an object of the present invention is to provide a stop line search device that can appropriately search for a stop line. [Means for solving the problem]

[0006] A stop line search device according to one aspect of the present invention includes: image acquisition means for acquiring an image of an area ahead of a host vehicle; traffic light detection means for detecting a traffic light installed at an intersection ahead of the host vehicle based on the image; and setting means for, when a far-side traffic light at a far side of the intersection as seen from the host vehicle is detected by the traffic light detection means, setting a stop line search area for searching for a stop line at the intersection based on a detection result indicating whether a near-side traffic light at a near side of the intersection as seen from the host vehicle has been detected by the traffic light detection means. When the traffic light detection means detects the traffic light at the rear side and the detection result indicates that the traffic light at the front side is not detected, the setting means sets the stop line search area based on the number of lanes at the intersection extending in an intersecting direction intersecting with the approach direction in which the host vehicle enters the intersection. That is it. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a block diagram showing a configuration of a vehicle according to an embodiment. [Figure 2] 4 is a flowchart showing the operation of an ECU according to the embodiment. [Figure 3] FIG. 2 is a diagram illustrating an example of a stop line search area. [Figure 4] FIG. 10 is a diagram showing an example of a stop line search area according to a first modified example. [Figure 5] FIG. 10 is a diagram showing an example of a stop line search area according to a second modified example. DETAILED DESCRIPTION OF THE INVENTION

[0008] An embodiment of a stop line search device will be described with reference to Figures 1 to 3. In the following, an ECU (Electronic Control Unit) 20 mounted on a vehicle 1 will be taken as an example of the stop line search device.

[0009] In FIG. 1, a vehicle 1 includes a camera 11, an HMI (Human Machine Interface) 12, an actuator 13, and an ECU 20.

[0010] Camera 11 is a camera for capturing images of the area ahead of vehicle 1. Camera 11 may be provided on the interior side of the windshield of vehicle 1. Note that vehicle 1 may be equipped with other cameras in addition to camera 11. In other words, vehicle 1 may be equipped with two or more cameras.

[0011] The HMI 12 is an interface for inputting and outputting information between a passenger (e.g., a driver) of the vehicle 1 and a system (e.g., the ECU 20) of the vehicle 1. The HMI 12 may have a display, a speaker, etc. The display of the HMI 12 may be a HUD (Head Up Display) or a multi-information display provided on an instrument panel.

[0012] The actuator 13 includes a brake actuator. The brake actuator controls a brake system in response to a control signal from the ECU 20, and controls the braking force applied to the wheels of the vehicle 1. The actuator 13 may also include a steering actuator. The steering actuator controls the drive of an assist motor that controls the steering torque of the electric power steering system in response to a control signal from the ECU 20. The actuator 13 may also include a drive actuator. If the vehicle 1 is a vehicle equipped with an engine, the drive actuator controls the amount of air supplied to the engine (e.g., the throttle opening) in response to a control signal from the ECU 20, and controls the driving force of the vehicle 1.

[0013] The ECU 20 has an image acquisition unit 21, an image processing unit 22, a setting unit 23, an attention-call determination unit 24, and a deceleration determination unit 25 as logically configured logic blocks or as physically realized processing circuits.

[0014] The image acquisition unit 21 acquires images of the area ahead of the vehicle 1 captured by the camera 11. The camera 11 repeatedly captures images of the area ahead of the vehicle 1 at a predetermined imaging period. The image acquisition unit 21 may sequentially acquire a plurality of images captured by the camera 11.

[0015] The image processing unit 22 performs image processing on the image acquired by the image acquisition unit 21. By performing image processing on the image, the image processing unit 22 detects traffic lights installed at the intersection ahead of the vehicle 1. The image processing may include at least one of edge extraction processing, noise removal processing, and pattern matching processing.

[0016] The image processing unit 22 estimates the position of the detected traffic light. The position of the traffic light may be estimated based on the position of the traffic light in the image (particularly the position in the vertical direction of the image) and the size of the traffic light in the image. The position of the traffic light may be estimated using an image processing technique such as Structure from Motion (SfM).

[0017] The image processor 22 determines the light status of the detected traffic light. The light status may include a pass-permit state corresponding to a green light, a pass-prohibited state corresponding to a red light, and a transition state corresponding to a yellow light. If the traffic light is equipped with an arrow light, the light status may include the arrow light state.

[0018] The image processing unit 22 generates traffic light information indicating the position of the detected traffic light and the light status of the traffic light. If the light status of the traffic light indicated by the traffic light information is a no-passing state (i.e., red light) or a transition state (i.e., yellow light), the setting unit 23 sets a stop line search area for searching for a stop line. The stop line search area will be described in detail later.

[0019] When the setting unit 23 sets the stop line search area, the image processing unit 22 detects the stop line at the intersection ahead of the vehicle 1 by performing image processing on a portion of the image that corresponds to the stop line search area. The image processing may include at least one of edge extraction processing, noise removal processing, and pattern matching processing. Note that the stop line at the intersection ahead of the vehicle 1 does not have to be detected from the image captured by the camera 11. For example, the stop line at the intersection ahead of the vehicle 1 may be detected based on the detection results of at least one of a radar sensor and LiDAR (Laser Imaging Detection and Ranging).

[0020] The attention-call determination unit 24 determines whether to issue an attention call to the driver of the vehicle 1. The attention-call determination unit 24 may determine to issue an attention call when the light state of the traffic light is a no-passing state (i.e., red light) or a transition state (i.e., yellow light) and sudden braking is required to stop the vehicle 1 at the detected stop line. In this case, the ECU 20 may control the HMI 12 to display a warning image or issue an alarm.

[0021] The deceleration determination unit 25 determines whether deceleration of the vehicle 1 is necessary when the lighting state of the traffic light is a no-passing state (i.e., red light) or a transition state (i.e., yellow light). The deceleration determination unit 25 may calculate a required deceleration required for the vehicle 1 to stop at the position of the stop line, based on the distance from the current position of the vehicle 1 to the position of the detected stop line and the speed of the vehicle 1. The deceleration determination unit 25 may determine that deceleration of the vehicle 1 is necessary when the current deceleration of the vehicle 1 is smaller than the required deceleration. In this case, the ECU 20 may control the actuator 13 so that the deceleration of the vehicle 1 approaches the required deceleration. The ECU 20 may be configured to be capable of performing automatic driving, in which at least one of acceleration / deceleration and steering of the vehicle 1 is automatically controlled by controlling the actuator 13.

[0022] Next, the stop line search area set by the setting unit 23 will be explained. When a stop line is detected from an image captured by a camera (for example, camera 11), for example, at least one of a road marking having a shape similar to that of a stop line, a shadow extending in the direction of the stop line, and a gap in the road pavement extending in the direction of the stop line may be erroneously recognized as a stop line. If something that is not a stop line is erroneously recognized as a stop line, this may affect the determination results of at least one of the attention alert determination unit 24 and the deceleration determination unit 25, and may result in at least one of unnecessary attention alerts and deceleration of the vehicle 1.

[0023] Since stop lines are set according to predetermined rules, the location of the stop line can be narrowed down from the location of the traffic light. Focusing on this point, the setting unit 23 sets a stop line search area based on the location of the traffic light indicated by the traffic light information. In the following description, among the traffic lights that regulate the travel of the vehicle 1, a traffic light that is located on the far side of the intersection as seen from the vehicle 1 will be referred to as a "far side traffic light." Furthermore, among the traffic lights that regulate the travel of the vehicle 1, a traffic light that is located on the near side of the intersection as seen from the vehicle 1 will be referred to as a "near side traffic light."

[0024] Specifically, in the flowchart of Figure 2, if the lighting state of the traffic light indicated by the traffic light information is a no-passing state (i.e., red light) or a transition state (i.e., yellow light) (step S101), the setting unit 23 determines whether only the rear traffic light is installed at the intersection ahead of the vehicle 1 based on the position of the traffic light indicated by the traffic light information (step S102).

[0025] If it is determined in the process of step S102 that only the rear traffic light is installed (step S102: Yes), the setting unit 23 sets an area (for example, see area A1 in FIG. 3(a)) extending from the installation position of the rear traffic light (for example, see traffic light S1 in FIG. 3(a)) toward the vehicle 1 as the stop line search area (step S103). Here, the length of area A1 in the approach direction of vehicle 1 entering the intersection may be, for example, 30 meters.

[0026] In the process of step S102, if it is determined that a traffic light on the near side is installed in addition to the traffic light on the far side (step S102: No), the setting unit 23 sets an area (for example, see area A2 in FIG. 3(b)) near the installation position of the traffic light on the near side (for example, see traffic light S2 in FIG. 3(b)) as the stop line search area (step S104). Here, the length of area A2 in the approach direction of vehicle 1 entering the intersection may be several meters.

[0027] (Technical Effects) For example, as shown in Figure 3, the distance from traffic light S1, which corresponds to the traffic light at the back, to the stop line is different from the distance from traffic light S2, which corresponds to the traffic light at the front, to the stop line. If the size of the stop line search area is fixed, the following technical problems arise. If the size of the stop line search area is relatively small and only the traffic light at the back is installed at the intersection, the stop line may not be included in the stop line search area. In this case, the stop line may not be detected, or something different may be mistakenly recognized as a stop line. If the size of the stop line search area is relatively large and a traffic light at the front is installed at the intersection, the stop line search area may include, in addition to the stop line, something with a shape similar to the stop line. In this case, something with a shape similar to the stop line may be mistakenly recognized as a stop line, rather than the actual stop line.

[0028] In response to this, the setting unit 23 changes the size of the stop line search area depending on whether the intersection has only a traffic light on the far side or a traffic light on the near side. Therefore, the ECU 20, which is an example of a stop line search device, can appropriately search for a stop line.

[0029] (First Modification) A first modified example of the embodiment of the stop line search device will be described with reference to Fig. 4. As shown in Fig. 4, the distance from the end of the road extending in the intersecting direction on the vehicle 1 side to the stop line varies depending on the number of lanes extending in the intersecting direction (up and down direction in Fig. 4) that intersects with the approach direction (left and right direction in Fig. 4) in which the vehicle 1 approaches the intersection. Specifically, the greater the number of lanes extending in the intersecting direction, the longer the distance from the end of the road extending in the intersecting direction on the vehicle 1 side to the stop line.

[0030] 2, if it is determined that only the rear traffic light is installed (step S102: Yes), the setting unit 23 may set the stop line search area based on the number of lanes extending in an intersecting direction that intersects with the approach direction in which the vehicle 1 enters the intersection. In this case, the setting unit 23 may set the stop line search area to an area extending toward the vehicle 1 (see area A3a in FIG. 4(a) and area A3b in FIG. 4(b)), starting from the end of the road including the lanes extending in the intersecting direction on the vehicle 1 side. The number of lanes extending in the intersecting direction may be acquired from map information.

[0031] 4, the length of area A3b in the approach direction in which vehicle 1 enters the intersection is longer than the length of area A3a in the approach direction. In other words, the length of the stop line search area in the approach direction when there are a relatively large number of lanes extending in the intersecting direction is longer than the length of the stop line search area in the approach direction when there are a relatively small number of lanes extending in the intersecting direction.

[0032] For example, when a right-turn-only lane is provided, a guide line for right-turning vehicles may be painted within the intersection. If the intersection is included in the stop line search area, there is a possibility that at least a portion of the guide line will be mistakenly recognized as a stop line. In contrast, as described above, if the stop line search area is set to an area extending toward vehicle 1, starting from the end of the road including lanes extending in the intersecting direction on the vehicle 1 side, it is possible to prevent at least a portion of the guide line from being mistakenly recognized as a stop line. Therefore, according to the first modification, it is possible to more appropriately search for a stop line.

[0033] (Second Modification) A second modified example of the embodiment of the stop line search device will be described with reference to Fig. 5. As shown in Fig. 5, when an intersection is relatively wide (see Fig. 5(b)), there are more traffic lights installed at the intersection than when the intersection is relatively narrow (see Fig. 5(a)). At the intersection shown in Fig. 5(a), only traffic light S1 is installed as a traffic light that regulates the travel of vehicle 1. In contrast, at the intersection shown in Fig. 5(b), traffic lights S1 and S3 are installed as traffic lights that regulate the travel of vehicle 1.

[0034] 2, if it is determined that only rear traffic lights are installed (step S102: Yes), the setting unit 23 may set a stop line search area (see area A4a in FIG. 5(a) and area A4b in FIG. 5(b)) based on the number of rear traffic lights. As shown in FIG. 5, the length of area A4b in the approach direction in which vehicle 1 enters the intersection is longer than the length of area A4a in the approach direction.

[0035] With this configuration, the stop line search area can be set so that the stop line is included. Therefore, according to the second modification, the stop line can be more appropriately searched for.

[0036] Aspects of the invention derived from the above-described embodiment and modifications will be described below.

[0037] A stop line search device according to one aspect of the invention includes: image acquisition means for acquiring an image of an area ahead of the host vehicle; traffic light detection means for detecting a traffic light installed at an intersection ahead of the host vehicle based on the image; and setting means for, when a far-side traffic light at the far end of the intersection as seen from the host vehicle is detected by the traffic light detection means, setting a stop line search area for searching for a stop line at the intersection based on a detection result indicating whether a near-side traffic light at the near end of the intersection as seen from the host vehicle has been detected by the traffic light detection means. In the above-described embodiment, the ECU 20 corresponds to an example of a stop line search device, the image acquisition unit 21 corresponds to an example of the image acquisition means, the image processing unit 22 corresponds to an example of the traffic light detection means, the setting unit 23 corresponds to an example of the setting means, and traffic light information corresponds to an example of the detection result.

[0038] In the stop line search device, when the traffic light detection means detects the traffic light at the rear and the detection result indicates that the traffic light at the front is not detected, the setting means may set the stop line search area based on the number of lanes at the intersection extending in an intersecting direction that intersects with the entry direction in which the vehicle enters the intersection.

[0039] In this case, the setting means may set an area extending toward the vehicle as the stop line search area, starting from an end of a road including lanes extending in the intersecting direction that is closer to the vehicle.

[0040] Alternatively, in the stop line search device, when the traffic light detection means detects the traffic light at the rear and the detection result indicates that the traffic light at the front is not detected, the setting means may set the stop line search area based on the number of traffic lights at the rear.

[0041] The present invention is not limited to the above-described embodiments, but can be modified as appropriate within the scope that does not contradict the gist or idea of ​​the invention that can be read from the claims and the entire specification, and stop line search devices that involve such modifications are also included in the technical scope of the present invention. [Explanation of symbols]

[0042] 1... vehicle, 20... ECU, 21... image acquisition unit, 22... image processing unit, 23... setting unit, 24... attention-call determination unit, 25... deceleration determination unit

Claims

1. an image acquisition means for acquiring an image of an area ahead of the vehicle; a traffic light detection means for detecting a traffic light installed at an intersection ahead of the vehicle based on the image; a setting means for setting a stop line search area for searching for a stop line at the intersection based on a detection result indicating whether or not a near side traffic light at a near side of the intersection as seen from the host vehicle has been detected by the traffic light detection means when a far side traffic light at a far side of the intersection as seen from the host vehicle has been detected by the traffic light detection means; Equipped with When the traffic light detection means detects the traffic light at the rear side and the detection result indicates that the traffic light at the front side is not detected, the setting means sets the stop line search area based on the number of lanes at the intersection extending in an intersecting direction intersecting with the approach direction in which the host vehicle enters the intersection. A stop line search device characterized by the above.

2. 2. The stop line search device according to claim 1, wherein the setting means sets an area extending toward the vehicle as the stop line search area, starting from an end of a road including lanes extending in the intersecting direction that is closer to the vehicle.

3. The stop line search device according to claim 1, characterized in that, when the traffic light detection means detects the traffic light at the rear and the detection result indicates that the traffic light at the front is not detected, the setting means sets the stop line search area based on the number of traffic lights at the rear.

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