Route guidance method and route guidance device

Abstract

This provides a route guidance method that allows drivers to relatively easily identify guidance points even in backlit conditions. [Solution] The system is configured to provide guidance information using landmarks B around the guidance point A as markers, so that the driver performs a predetermined driving operation at the guidance point A set on the path that vehicle C1 should take. The system is also configured to determine whether the light from a predetermined light source D is shining from the direction of travel of vehicle C1, resulting in a backlight condition. If it is determined that it is a backlight condition, the system is configured to select a landmark B that is located further away from the virtual straight line L connecting vehicle C1 and light source D than if it were determined that it is not a backlight condition.

Description

Technical Field

[0001] The present disclosure relates to a route guidance method and a route guidance device.

Background Art

[0002] Conventionally, a device has been proposed that sets a guidance point on a route along which a vehicle should travel and provides guidance information using landmarks around the set guidance point as a reference (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the device described in Patent Document 1, for example, when it is in a backlight state where light from the sun irradiates from the direction of travel of the vehicle, it may be difficult for the driver to visually recognize the landmarks around the guidance point. Therefore, it may be difficult for the driver to grasp the guidance point. An object of the present disclosure is to provide a route guidance method and a route guidance device that enable a driver to relatively easily grasp a guidance point even in a backlight state.

Means for Solving the Problems

[0005] A route guidance method according to an aspect of the present disclosure is a route guidance method for providing guidance information using landmarks around a guidance point so that a driver performs a predetermined driving operation at the guidance point set on a route along which a vehicle should travel, the method including determining whether it is in a backlight state where light from a predetermined light source irradiates from the direction of travel of the vehicle, and if it is determined to be in a backlight state, selecting, as a landmark used as a reference, a landmark located at a position farther from a virtual straight line connecting the vehicle and the light source than when it is determined not to be in a backlight state.

[0006] Furthermore, a route guidance device according to one aspect of the present disclosure is a route guidance device that provides guidance information using landmarks around a guidance point as markers so that the driver performs a predetermined driving operation at a guidance point set on the route to which the vehicle should travel, and comprises: a backlight determination unit that determines whether the light from a predetermined light source is shining from the direction of travel of the vehicle in a backlight condition; and a landmark selection unit that, if the backlight determination unit determines that it is a backlight condition, selects a landmark to be used as a marker that is located further away from the virtual straight line connecting the vehicle and the light source than when it is determined that it is not a backlight condition. [Effects of the Invention]

[0007] According to this disclosure, it is possible to provide a route guidance method and route guidance device that enable drivers to relatively easily grasp guidance points even in backlit conditions. [Brief explanation of the drawing]

[0008] [Figure 1] This figure shows a schematic configuration of the path guidance device according to the embodiment. [Figure 2] This is a diagram showing the roads on which vehicles travel. [Figure 3] This diagram shows the various functions that the information provision device provides. [Figure 4] This is a flowchart showing the overall flow of the path guidance method according to the embodiment. [Figure 5] This figure shows a schematic configuration of a path guidance device according to a modified example. [Figure 6] This diagram shows the headlight beam of an oncoming vehicle when both vehicles are traveling on a flat road surface. [Figure 7] This diagram shows the headlight beam of an oncoming vehicle when both vehicles are traveling on an uneven road surface. [Modes for carrying out the invention]

[0009] The embodiments of this disclosure will be described below with reference to the drawings. Note that the drawings are schematic and may differ from actual ones. Furthermore, the embodiments of this disclosure shown below are illustrative examples of devices and methods for realizing the technical concept of this disclosure, and the technical concept of this disclosure is not limited to the structure, arrangement, etc., of the components described below. The technical concept of this disclosure can be modified in various ways within the technical scope defined by the claims described in the patent claims.

[0010] In the first embodiment, as shown in Figures 1 and 2, an example is given in which the route guidance method and route guidance device of this disclosure are applied to a route guidance device 1 that provides guidance information using landmarks B around a guide point A so that the driver of vehicle C1 performs a predetermined driving operation at the guide point A set on the path that vehicle C1 should take. Figure 1 is a diagram showing the schematic configuration of the route guidance device 1 according to this embodiment. Figure 2 is a diagram showing the road on which vehicle C1 is traveling. The route guidance device 1 is mounted on vehicle C1 and includes an object detection unit 2, an object detection integration and tracking unit 3, a vehicle position estimation unit 4, a map storage unit 5, a map-based vehicle position estimation unit 6, a target driving route setting unit 7, a headlight light database (DB) 8, and an information provision device 9. The object detection unit 2 detects the position, orientation, size, and speed of objects around the vehicle C1. Examples of objects include vehicles, motorcycles, pedestrians, and obstacles. The object detection unit 2 can employ multiple sensors, such as a camera 2a mounted on the vehicle C1 to image the area around the vehicle C1 (i.e., the external environment), a laser radar 2b, and a millimeter-wave radar 2c. For example, the camera 2a can be a multi-camera system that images the entire area around the vehicle C1. The detection results are presented to the driver, for example, by displaying the two-dimensional position, orientation, size, and speed of objects on a zenith diagram of the vehicle C1 viewed from above on a display (not shown).

[0011] The object detection integration and tracking unit 3 calculates object position information based on the detection results of multiple sensors obtained by the object detection unit 2. For example, the object position information can include the object's two-dimensional position, orientation, size, and velocity. In calculating the object position information, the unit calculates the most rational object position, taking into account the error characteristics of each sensor, based on the two-dimensional position, orientation, size, and velocity of multiple objects obtained by the multiple sensors of the object detection unit 2. It then outputs one set of two-dimensional position, orientation, size, and velocity for each object. Furthermore, the object detection integration and tracking unit 3 may verify the identity of objects obtained at different times (i.e., perform correspondence) and improve the accuracy of the object's velocity based on this correspondence.

[0012] The vehicle position estimation unit 4 measures the absolute position, attitude, and speed of the vehicle C1. For the absolute position, for example, a position relative to a predetermined reference point can be used. Examples include latitude and longitude, and plane rectangular coordinates. For plane rectangular coordinates, examples include coordinates in a map coordinate system such as the Tokyo 9th System. The vehicle position estimation unit 4 can employ, for example, a GPS (Global Positioning System) receiver that receives GPS information from multiple navigation satellites to measure the current position of the vehicle C1, and odometry. Note that the GPS signal also includes date and time data. The map storage unit 5 stores map information for the area in which vehicle C1 is traveling. The map information can include, for example, the absolute position of lanes, lane connections, and relative positional relationships. The vehicle position estimation unit 6 obtains map information about the area around vehicle C1 from the map storage unit 5, and estimates the current position of vehicle C1 on the road it is currently traveling on, based on the obtained map information and the absolute position of vehicle C1 obtained by the vehicle position estimation unit 4. The current position of vehicle C1 may include information indicating which lane vehicle C1 is traveling in. When the driver of vehicle C1 inputs a destination, the target driving route setting unit 7 obtains map information of the vehicle C1's current location from the map storage unit 5 and sets the route that vehicle C1 should take to reach the destination from its current location (hereinafter also referred to as the "target driving route") based on the acquired map information. The destination is input, for example, via a touch panel (not shown) installed inside the vehicle.

[0013] The headlight light DB8 stores information such as the location where the driver of vehicle C1 previously felt the headlights of oncoming vehicle C2 were dazzling. For example, it stores the position, date and time, and direction of the light emitted from the headlights to vehicle C1 when the vehicle C1 was previously subjected to backlighting from the headlights. The storage of information (position, date and time, and direction of light of vehicle C1) in the headlight light DB8 is performed, for example, by the second direction estimation unit 17 (described later) obtaining an estimation result for the direction of the headlights (second direction) captured in the camera image, setting the estimated result of the second direction as the direction of the headlights of oncoming vehicle C2, and storing the direction of the headlights of oncoming vehicle C2, the absolute position of vehicle C1, and the date and time associated with that direction.

[0014] The information providing device 9 comprises a processor 9a and peripheral components such as a storage device 9b for storing computer programs and the like. For example, the processor 9a can be a CPU (Central Processing Unit) or an MPU. For example, the storage device 9b can be a semiconductor storage device, a magnetic storage device, or an optical storage device. The storage device 9b may also include registers, cache memory, and memory such as ROM and RAM used as main memory. Each function of the information providing device 9 described below is realized, for example, by the processor 9a executing a computer program stored in the storage device 9b.

[0015] Next, we will explain in detail each function of the information-providing device 9. As shown in FIG. 3, the information providing device 9 realizes the functions of a guidance point extraction unit 10, a guidance point relative position calculation unit 11, a light source direction estimation unit 12, a backlight determination unit 13, a target selection unit 14, and a guidance information providing unit 15. FIG. 3 is a diagram showing the functions realized by the information providing device 9. The guidance point extraction unit 10 extracts a guidance point A around the vehicle C1 from the target travel route set by the target travel route setting unit 7. As the guidance point A, for example, a point (right / left turn point, lane change point, railroad crossing position) that causes a driver to perform a predetermined driving operation can be adopted. Examples of the predetermined driving operation include steering operations, accelerator operations, and brake operations for right / left turns, lane changes, stops, etc. Further, for example, based on road work information obtained by wireless communication via a communication device (not shown) or the scene recognition result of the camera image obtained by the camera 2a, the occurrence point of traffic control on the target travel route may be extracted as a guidance point.

[0016] The guidance point relative position calculation unit 11 calculates the relative position of the guidance point A extracted by the guidance point extraction unit 10 with respect to the vehicle C1. For example, based on the map information stored in the map storage unit 5, the absolute position (for example, latitude / longitude, plane rectangular coordinates) of the guidance point A is acquired. Subsequently, based on the absolute position of the vehicle C1 obtained by the own vehicle position estimation unit 4 and the absolute position of the guidance point, the relative position of the guidance point with respect to the vehicle C1 is calculated.

[0017] The light source direction estimation unit 12 includes a first direction estimation unit 16, a second direction estimation unit 17, and a third direction estimation unit 18. The first direction estimation unit 16 estimates the direction of the sun (light source D) with respect to the vehicle C1 (hereinafter also referred to as the "first direction"). For example, based on the GPS information obtained by the host vehicle position estimation unit 4, the current position (absolute position, for example, latitude and longitude) and date and time of the vehicle C1 are acquired, and based on the acquired position and date and time, the direction and elevation angle of the sun with respect to the vehicle C1 are calculated. Then, it is determined whether the calculated elevation angle is within a predetermined angle range (for example, 0° to 45°), and when it is determined that it is within the predetermined angle range, the calculated direction of the sun is used as the estimation result of the first direction. Note that when the weather information acquired by wireless communication via a communication device (not shown) indicates that the weather at the position of the vehicle C1 is not clear, the first direction estimation unit 16 may determine that the estimation result of the first direction cannot be obtained. As the weather information, for example, data provided by the Japan Meteorological Agency or the like can be adopted. As the content of the weather information, for example, it is sufficient to be able to determine whether sunlight reaches the vehicle C1, so it is sufficient to know whether it is sunny or other than sunny (cloudy, rainy).

[0018] The second direction estimation unit 17 estimates the direction (hereinafter also referred to as the "second direction") of a light source D (e.g., the sun, headlights) captured in the camera image relative to the vehicle C1. For example, it acquires camera images of all directions around the vehicle C1 from camera 2a, and calculates the direction and elevation angle of the light source that generated the saturated pixels based on the position of the saturated pixels in the acquired camera images and the installation position of camera 2a. It then determines whether the calculated elevation angle is within a predetermined angular range (e.g., 0° to 45°), and if it is determined to be within the predetermined angular range, the calculated direction of the light source D is used as the estimated result of the second direction. Examples of saturated pixels include pixels with a brightness value that exceeds the upper limit of the allowable light reception amount of the image sensor. In calculating the position of saturated pixels in the camera image, for example, it determines whether saturated pixels have occurred in a predetermined proportion or more of all pixels, and if it is determined that they have occurred in a predetermined proportion or more, the center position of the image region where saturated pixels occurred is used as the position of the saturated pixels in the camera image. Furthermore, the orientation of the center position of the pixel region is determined, for example, by calculating the frequency of saturated pixels with respect to the horizontal axis of the camera image using a histogram, and the orientation with the highest frequency is taken as the orientation of the center position of the pixel region. Similarly, the height of the center position of the pixel region is determined, for example, by calculating the frequency of saturated pixels with respect to the vertical axis of the camera image using a histogram, and the height with the highest frequency is taken as the height of the center position of the pixel region. As for the installation position of camera 2a, for example, the position and orientation of camera 2a on vehicle C1 can be adopted. The second orientation estimation unit 17 may determine that a second orientation estimation result could not be obtained if the control parameter that controls the dynamic range of camera 2a is less than the upper limit corresponding to the maximum brightness that camera 2a can capture. In this embodiment, an example was shown in which camera images were acquired from all directions around the vehicle C1, but this is not the only example. For example, when changing lanes or using ACC (Adaptive Cruise Control), only the camera image in front of the vehicle C1 may be acquired, and when turning right at an intersection or going straight at an intersection, only the camera image behind the vehicle C1 may be acquired.

[0019] The third direction estimation unit 18 estimates the direction of the headlights (light source D) of the oncoming vehicle C2 relative to vehicle C1 (hereinafter also referred to as the "third direction"). For example, based on the GPS information obtained by the vehicle position estimation unit 4, it acquires the current position and date and time of vehicle C1, and extracts the direction of the headlights associated with the acquired position and date and time of vehicle C1 from the headlight light DB8. The date and time may include, for example, the time of day and the day of the week. The extracted headlight direction is then used as the estimation result for the third direction. On the other hand, if headlight light information corresponding to the position and date and time of vehicle C1 cannot be extracted, it is determined that the estimation result for the third direction could not be obtained.

[0020] The backlight determination unit 13 determines whether the light from a predetermined light source D (sun, headlights) is emitted from the direction of travel of the vehicle C1, based on the first direction obtained by the first direction estimation unit 16, the second direction obtained by the second direction estimation unit 17, and the third direction obtained by the third direction estimation unit 18, that the vehicle C1 is in a backlight state. For example, it determines whether the deviation between any of the first, second, and third directions and the direction of travel of the vehicle C1 is sufficiently small (for example, 0° to 10°), and if it is determined to be sufficiently small, it determines that the vehicle is in a backlight state. In this embodiment, an example is shown in which all of the first, second, and third directions are calculated, but for example, it is also possible to calculate only one of the first to third directions and determine whether the vehicle is in a backlight state based only on the calculated direction.

[0021] The target selection unit 14 includes a first target selection unit 19 and a second target selection unit 20. If the backlight determination unit 13 determines that there is no backlighting, the first target selection unit 19 extracts targets B from the area near guide point A to be used as landmarks when identifying guide point A. For example, it selects targets B located in an area less than a predetermined angle θ from a virtual straight line L connecting vehicle C1 and light source D, with vehicle C1 as the center (hereinafter also called the "inner area E1"). For example, if light source D is the sun, the predetermined angle θ can be set to 20° to 30°. Targets B can be, for example, motorcycles, pedestrians, automobiles, or buildings. As an example, a score is calculated for each target B located within the inner area E1 and around guide point A, and targets B to be used as landmarks are selected from among the targets B whose calculated scores exceed a predetermined threshold. In this case, targets B with higher scores are given a higher priority. The score of target B is calculated based on the external environment and user behavior detected by the object detection unit 2. For example, the score for each target B is calculated by evaluating consistency, visibility, prominence, uniqueness, proximity between target B and guidance point A, and the distance from the vehicle's position to guidance point A, based on the external environment. In the evaluation of consistency, for example, targets B that are visible from vehicle C1 for a long time (i.e., targets B that are in the camera image for a long time) are given higher scores, and targets B that remain at the top of the priority list for a long time are also given higher scores. In the evaluation of visibility, for example, targets B that occupy a larger area in the camera image obtained from camera 2a are given higher scores. The area occupied by target B is larger for targets B that are closer to vehicle C1, and for the same distance from vehicle C1, it is larger for trucks than for passenger cars.

[0022] Furthermore, in the evaluation of splendor, for example, conspicuous features based on human visual characteristics are evaluated, and the more conspicuous a target B is, the higher the score. For example, in the evaluation of conspicuous features, a red vehicle is evaluated as being more conspicuous than a gray vehicle. Furthermore, in the evaluation of uniqueness, for example, the uniqueness of target B in a landscape is evaluated, and the less ambiguous a target is, the higher the score. For example, in a situation where many white vehicles are visible from vehicle C1 (a situation where many are visible in the camera image), if there is only one blue vehicle, the blue vehicle is evaluated as being less ambiguous than the white vehicles. For example, in a situation where many vehicles are visible from vehicle C1, if there is only one bicycle, the bicycle is evaluated as being less ambiguous than the vehicles. Furthermore, in the evaluation of proximity between target B and guide point A, target B and guide point A are mapped on a map, and the closer target B is to guide point A on the map, the higher the score. For example, if guide point A is an intersection, the building at the corner of the intersection is scored higher than a sign visible in the distance at the intersection. Furthermore, when evaluating the distance from the vehicle's position to guidance point A, the evaluation to be prioritized will differ depending on the distance to guidance point A. For example, if the distance to guidance point A is short, the "evaluation of prominence" will be prioritized, and if the distance to guidance point A is far, the "evaluation of consistency" will be prioritized. Furthermore, for example, the score for each target B is calculated by evaluating the probability of understanding and the hesitation level based on user behavior. In evaluating the probability of understanding, for example, the probability that the driver correctly understood the guidance point A and performed appropriate driving operations when guidance information using the target target B as a landmark was provided in the past is calculated, and the higher the probability, the higher the score. In evaluating the hesitation level, for example, the hesitation level is calculated based on factors such as whether or not confirmation conversations were held, the number of round trips, biometric measurements, changes in driving behavior such as sudden braking and slow driving, and direct user input when guidance information using the target target B as a landmark was provided in the past, and the lower the calculated hesitation level, the higher the score.

[0023] The second target selection unit 20, when the backlight determination unit 13 determines that it is in a backlit state, extracts a target B from an area away from the guide point A to be used as a landmark when identifying the guide point A. For example, when it is determined that it is in a backlit state, it selects a target B that is located further away from the virtual straight line L connecting the vehicle C1 and the light source D than when it is determined that it is not in a backlit state. More specifically, it selects a target B located in an area (hereinafter also called the "outer area E2") that is at a predetermined angle θ or more from the virtual straight line L connecting the vehicle C1 and the guide point, with the vehicle C1 as the center. As an example, if the guide point A is an intersection, it selects a target (e.g., a motorcycle, pedestrian, or car) or a landmark (e.g., a tall building, or a building with a distinctive color or shape) that is located in the outer area E2 and is moving on a road that intersects with the road on which the vehicle C1 is traveling (hereinafter also called the "intersecting road"). Furthermore, if there are multiple intersecting roads, the system may select a landmark B that is moving along the intersecting road where no light (e.g., sunlight, headlights) is shining on vehicle C1. Also, if the road on which vehicle C1 is traveling is a straight road and guide point A is located on that straight road, the second landmark selection unit 20 will select a landmark located in the outer region E2 and close to guide point A. Furthermore, if there are multiple landmarks close to guide point A, the system may select a landmark where no light is shining on vehicle C1.

[0024] The guidance information provision unit 15 provides the driver of vehicle C1 with guidance information using landmark B selected by the landmark selection unit 14 (first landmark selection unit 19 or second landmark selection unit 20) as a guide, so that the driver can perform a predetermined driving operation at guidance point A extracted by the guidance point extraction unit 10. For example, if guidance point A is an intersection and the selected landmark B is a convenience store (landmark), the guidance information provided will be "Turn left soon. You will soon see an intersection with a convenience store," using the convenience store as a landmark. Alternatively, for example, if the selected landmark B is a blue vehicle traveling on the intersecting road in front of vehicle C1, the guidance information provided will be "Turn left soon. Follow the blue vehicle in front," using the blue vehicle as a landmark. This allows the driver of vehicle C1 to identify the intersection, which is guidance point A, using landmark B such as the convenience store or the blue vehicle in front as a guide, and to perform the driving operation necessary to turn left at the intersection. Guidance information is provided, for example, via a display (not shown) or speaker (not shown) installed inside the vehicle C1, which can be seen and heard by the driver of vehicle C1.

[0025] (operation) Next, we will explain the process flow for providing guidance information to the driver of vehicle C1. Figure 4 is a flowchart showing the overall flow of the route guidance method in this embodiment. First, when the driver of vehicle C1 inputs a destination, the target driving route setting unit 7 sets a target driving route to the destination (S101 in Figure 4). Next, the object detection unit 2 detects the positions of objects (e.g., vehicles, motorcycles, pedestrians, obstacles) around vehicle C1 (S102 in Figure 4). Then, the object detection integration and tracking unit 3 calculates object position information (e.g., the object's 2D position, posture, size, and speed) based on the detected positions (S103 in Figure 4). Next, the vehicle position estimation unit 4 measures the absolute position of vehicle C1 (S104 in Figure 4). Then, the map-based vehicle position estimation unit 6 obtains map information about the area around vehicle C1 from the map storage unit 5 (S105 in Figure 4), and estimates the current position of vehicle C1 on the road it is currently traveling on based on the obtained map information and the measured absolute position of vehicle C1 (S106 in Figure 4).

[0026] Next, the guidance point extraction unit 10 of the information provision device 9 extracts guidance points around vehicle C1 from the target driving route (S107 in Figure 4). Next, the guidance point relative position calculation unit 11 calculates the relative position of the extracted guidance point A (S108 in Figure 4). Next, the first direction estimation unit 16 estimates the direction of the sun (first direction) (S109 in Figure 4). Next, the second direction estimation unit 17 estimates the direction of light source D captured in the camera image (second direction) (S110 in Figure 4). Next, the third direction estimation unit 18 estimates the direction of the headlights of oncoming vehicle C2 (third direction) (S111 in Figure 5). Next, the backlight determination unit 13 determines, based on the estimated first, second, and third directions, whether the light from the light source D (e.g., the sun, headlights) is emitted from the direction of travel of the vehicle C1, resulting in a backlight condition (S112 in Figure 4).

[0027] Then, if it is determined that there is no backlighting condition (S112 "No" in Figure 4), the first target selection unit 19 selects target B from the area near guide point A (inner area E1) (S113 in Figure 4). Subsequently, the guidance information provision unit 15 provides guidance information to the driver of vehicle C1, using the selected target B as a landmark, so that the driver can perform a predetermined driving operation at guide point A, which was extracted in S107 (S115 in Figure 4). With the provision of guidance information, the driver of vehicle C1 identifies guide point A using target B as a landmark and performs a predetermined driving operation at guide point A. On the other hand, if it is determined that the vehicle is in a backlit condition (S112 "Yes" in Figure 4), the second target selection unit 20 selects a target B located away from the virtual straight line L connecting the vehicle C1 and the light source D (S114 in Figure 4). More specifically, it selects a target B located in an area (outer area E2) at a predetermined angle θ or more from the virtual straight line L with the vehicle C1 as the center. This ensures that if the vehicle is in a backlit condition and the driver has difficulty seeing the target B near the guidance point A, a target B located in a direction that avoids the driver having to look directly at the light source D is selected. Subsequently, the guidance information provision unit 15 provides the driver of vehicle C1 with guidance information using the selected target B as a landmark, so that the driver can perform a predetermined driving operation at the guidance point A extracted in S107 (S115 in Figure 4).

[0028] (Effects of this embodiment) (1) As a comparative example, consider the case where a landmark B near guide point A is always used as a landmark for guidance information. In this case, for example, if the light from a predetermined light source D shines from the direction of travel of the vehicle C1, creating a backlit condition, it may become difficult for the driver to see landmark B near guide point A. Therefore, it may become difficult for the driver to identify guide point A. In contrast, in this embodiment, it is determined whether the light from a predetermined light source D is shining from the direction of travel of the vehicle C1, creating a backlight condition. If it is determined to be a backlight condition, the system selects a target B that is located further away from the virtual straight line L connecting the vehicle C1 and the light source D than if it were determined not to be a backlight condition. This allows, for example, when the driver has difficulty seeing a target B near guidance point A due to a backlight condition, a target B located in a direction that does not require the driver to directly look at the light source D is used as a marker for guidance information. Therefore, guidance information can be provided using a target B located in a relatively easily visible location as a marker. As a result, the driver can relatively easily grasp guidance point A. Furthermore, as another comparative example (hereinafter also referred to as "the second comparative example"), consider the case where guidance information is provided without using target B as a landmark in backlit conditions. For example, guidance information such as "You will soon turn left at the intersection" is provided. The ease of understanding of the guidance information for the route guidance device 1 of this second comparative example and the route guidance device 1 of this embodiment was evaluated on a 5-point scale, and the result was that the ease of understanding for the second comparative example was 3.0, and the ease of understanding for this embodiment was 4.3.

[0029] (2) In this embodiment, the predetermined light source D is the sun. This makes it possible to provide guidance information using landmarks located in a relatively easily visible location as markers, for example, when the driver has difficulty seeing landmarks near guidance point A due to the rising sun or setting sun (sun) at dawn or dusk.

[0030] (3) In this embodiment, the azimuth of the sun relative to vehicle C1 is estimated based on the position (absolute position, e.g., latitude and longitude) and date and time, and it is determined whether the vehicle is in a backlit state based on the estimated azimuth. By calculating the position of the sun based on the position of vehicle C1 and the date and time, it is possible to accurately determine whether the vehicle is in a backlit state where sunlight is shining from the direction of travel of vehicle C1.

[0031] (4) In this embodiment, the azimuth of the light source D (e.g., the sun) relative to the vehicle C1 is estimated based on the position of the saturated pixels in the camera image acquired from the camera 2a mounted on the vehicle C1 and imaging the area around the vehicle C1, and the installation position of the camera 2a, and it is determined whether the vehicle is in a backlit state based on the calculated azimuth. By calculating the position of the light source D (sun) based on the saturated pixels in the camera image and the installation position of the camera 2a, it is possible to accurately determine whether the vehicle is in a backlit state where light from the light source D (sun) is shining from the direction of travel of the vehicle C1.

[0032] (5) In this embodiment, the predetermined light source D is the headlight of the oncoming vehicle C2. This makes it possible to provide guidance information using a landmark B located in a relatively easily visible location as a reference point, for example, when the driver has difficulty seeing the landmark B near the guidance point A due to the headlight.

[0033] (6) In this embodiment, the headlight beam DB8 stores the position, date and time of vehicle C1 and the direction of the light emitted from the headlights of vehicle C1 when the vehicle C1 was previously in a backlit state due to the light from the headlights of oncoming vehicle C2. The headlight beam direction corresponding to the current position and date and time of vehicle C1 is extracted from the DB8, and it is determined whether the vehicle is in a backlit state based on the extracted direction. By referring to the database that stores past records, it is possible to accurately determine whether the headlight beam is shining from the direction of travel of vehicle C1, resulting in a backlit state.

[0034] (7) In this embodiment, if it is determined that the vehicle is in a backlit condition, a target B is selected to be used as a landmark, which is located in an area (outer region E2) that is at a predetermined angle θ or more from the virtual straight line L with the vehicle C1 as the center. By using a target B in the outer region E2 that is at a predetermined angle θ or more from the light source D, guidance information can be provided using a landmark that is relatively easy to see even in a backlit condition. Therefore, the driver can relatively easily grasp the guidance point A.

[0035] (8) In this embodiment, if it is determined that the vehicle is in a backlit condition, the object B used as a landmark is selected to be an object moving on a road that intersects with the road on which the vehicle C1 is traveling (intersecting road), or a landmark. By selecting object B from objects moving on an intersecting road (motorcycles, pedestrians, automobiles) or landmarks (tall buildings, buildings with distinctive colors or shapes), guidance information can be provided using an object that is relatively easy to see even in a backlit condition. Therefore, the driver can relatively easily grasp the guidance point A.

[0036] (modified version) In this embodiment, an example is shown in which a backlighting condition caused by the headlights of an oncoming vehicle C2 is determined by referring to the headlight light DB8, but other configurations can also be adopted. For example, as shown in Figure 5, such a backlighting condition may be determined by referring to a terrain database (DB) 21 that stores terrain information representing the terrain of the road on which the vehicle C1 is traveling. As terrain information, for example, information on the road shape and information on elevation differences can be used. Figure 5 is a diagram showing a schematic configuration of a modified route guidance device 1. As an example, the third direction estimation unit 18 and the backlighting condition determination unit 13 acquire the current position of the vehicle C1 based on the GPS information obtained by the vehicle position estimation unit 4, extract terrain information of the acquired current position of the vehicle C1 from the terrain DB 21, and determine whether it is a place where a backlighting condition is likely to occur due to the headlights of an oncoming vehicle C2 based on the extracted terrain information, and if it is determined that it is a place where a backlighting condition is likely to occur, it is determined that it is a backlighting condition caused by the headlights of an oncoming vehicle C2.

[0037] Here, for example, as shown in Figure 6, when vehicle C1 and oncoming vehicle C2 are traveling on a flat road surface, the headlight beam 22 of oncoming vehicle C2 illuminates only the road surface, and the possibility of the driver of vehicle C1 being dazzled by the headlight beam 22 is low. However, for example, as shown in Figure 7, when vehicle C1 and oncoming vehicle C2 are traveling on an uneven road surface (for example, a road surface that is uphill on both the vehicle C1 and oncoming vehicle C2 sides), the headlight beam 22 of oncoming vehicle C2 illuminates not only the road surface but also the area above the road surface, increasing the possibility of the driver of vehicle C1 being dazzled. Therefore, in this modified example, by referring to the terrain DB 21 which stores terrain information, it is possible to determine whether the headlight beam 22 is in a backlight condition, shining from the direction of travel of vehicle C1. Figure 6 shows the headlight beam 22 of oncoming vehicle C2 when vehicle C1 and oncoming vehicle C2 are traveling on a flat road surface. Figure 7 shows the headlight beam 22 of oncoming vehicle C2 when vehicle C1 and oncoming vehicle C2 are traveling on an uneven road surface. [Explanation of Symbols]

[0038] 1...Route guidance device, 2...Object detection unit, 2a...Camera, 2b...Laser radar, 2c...Millimeter-wave radar, 3...Object detection integration and tracking unit, 4...Vehicle position estimation unit, 5...Map storage unit, 6...Vehicle position estimation unit on map, 7...Target driving route setting unit, 8...Headlight light DB, 9...Information provision device, 9a...Processor, 9b...Storage device, 10...Guidance point extraction unit, 11...Guidance point relative position calculation unit, 12...Light source direction estimation unit, 13...Backlight determination unit, 14...Target selection unit, 15...Guidance information provision unit, 16...First direction estimation unit, 17...Second direction estimation unit, 18...Third direction estimation unit, 19...First target selection unit, 20...Second target selection unit, 21...Terrain DB, 22...Headlight light, A...Guidance point, B...Target, C1...Vehicle, C2...Oncoming vehicle, D...Light source, E1...Inner area, E2...Outer area, L...Virtual straight line

Claims

1. A route guidance method that provides guidance information using landmarks around a guide point so that the driver performs a predetermined driving operation at a guide point set on the route the vehicle should take, Determine whether the light from a predetermined light source is shining from the direction of travel of the vehicle, resulting in a backlight condition. If it is determined that the conditions are backlit, the target used as a landmark will be located further away from the imaginary line connecting the vehicle and the light source than if it were determined that the conditions are not backlit. Route guidance method.

2. The aforementioned predetermined light source is the sun. The path guidance method according to claim 1.

3. Based on the vehicle's position and the date and time, the azimuth of the sun relative to the vehicle is estimated, and based on the estimated azimuth, it is determined whether the conditions are backlit. The path guidance method according to claim 2.

4. Based on the position of the saturated pixels in the camera image acquired from a camera mounted on the vehicle that captures images of the area around the vehicle, and the installation position of the camera, the azimuth of the sun relative to the vehicle is estimated, and based on the estimated azimuth, it is determined whether the conditions are backlit. The path guidance method according to claim 1.

5. The aforementioned predetermined light source is the headlight of an oncoming vehicle. The path guidance method according to claim 1.

6. From a headlight light database that stores the vehicle's position, date and time, and the direction of light emitted from the headlights when the vehicle experienced the aforementioned backlighting condition due to the headlights in the past, the direction of the headlights corresponding to the vehicle's current position and date and time is extracted, and based on the extracted direction, it is determined whether the vehicle is experiencing the backlighting condition. The route guidance method according to claim 5.

7. From a terrain database that stores terrain information representing the terrain of the road on which the vehicle is traveling, terrain information for the current location of the vehicle is extracted, and based on the extracted terrain information, it is determined whether the location is prone to the occurrence of the backlight condition due to the light from the headlights, and if it is determined that the location is prone to the occurrence of the backlight condition, it is determined that the backlight condition exists. The route guidance method according to claim 5.

8. If the aforementioned backlighting condition is determined, the object to be used as the landmark is selected to be located in an area at or above a predetermined angle from the virtual straight line with respect to the vehicle. The path guidance method according to claim 1.

9. If the aforementioned backlighting conditions are determined, the object used as the marker will be a marker or landmark that moves along a road intersecting the road on which the vehicle is traveling. The path guidance method according to claim 1.

10. A route guidance device that provides guidance information using landmarks around a guide point so that the driver performs a predetermined driving operation at a guide point set on the route the vehicle should take, A backlight determination unit that determines whether the light from a predetermined light source is shining from the direction of travel of the vehicle, The vehicle also includes a target selection unit that, when the backlight determination unit determines that a backlight condition exists, selects a target to be used as a marker that is located further away from the virtual line connecting the vehicle and the light source than when the vehicle is determined not to be in a backlight condition. Route guidance device.

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