JP5998977B2 - Intersection guidance system, method and program - Google Patents

Description

  The present invention relates to an intersection guidance system, method, and program for guiding an intersection.

  A technique for switching an image for guiding a branch point depending on whether or not the branch point exists within the visible range of the driver is known (see Patent Document 1). In Patent Document 1, a branch point can be guided with images suitable for a situation where the driver can visually recognize the branch point and a situation where the driver cannot visually recognize the branch point.

JP 2010-181363 A

However, in Patent Document 1, there is a problem that the timing for switching an image for guiding a branch point becomes inappropriate. Since it is visually recognized from the approaching road that enters the branching point, how the branching point is seen depends on the road shape of the approaching road. Therefore, depending on the shape of the approaching road, the timing for switching the image for guiding the branch point may be felt early or late.
The present invention has been made in view of the above problems, and an object of the present invention is to provide a technique capable of guiding an intersection at a timing suitable for the shape of an approaching road.

  In order to achieve the above object, in the present invention, the road shape acquisition means acquires the road shape of the approach road with respect to the intersection. The reference position setting means sets a reference position in the intersection based on the road shape. The guidance means starts guidance of the intersection when the reference position moves within a visible range that can be visually recognized by the driver. In the above configuration, the guidance of the intersection can be started at the timing when the reference position set based on the road shape of the approach road can be visually recognized. Therefore, the intersection guidance can be started at a timing suitable for the shape of the approach road.

  The road shape acquisition unit may acquire the road shape of the approach road, and may acquire the road shape of the approach road based on map information, image recognition of a landscape image in front of the vehicle, and the like. An approach road is a road that travels when a vehicle enters an intersection, and is a road that is composed only of lanes where the vehicle can travel toward the intersection to be guided. An intersection is an area on the road surface including an approach area, which is an area where an approach road and two or more connection roads connected to the approach road intersect at least at the intersection. In addition, when there is an oncoming road on the approach road, the intersection is connected to the approach area where the approach road and the connection road connecting to the approach road intersect at the intersection, and to the opposite road and the opposite road at the intersection. It includes the area where the connecting road intersects. The oncoming road is a road in which the traveling direction of the vehicle is opposite to the traveling direction of the vehicle on the approach road, and is a road that is attached to the approach road. The road shape of the approach road may be the road shape of the approach road within a predetermined distance from the intersection. The road shape of the approach road may be the shape of the approach road in the horizontal direction (curved shape, width, number of lanes, etc.), or the shape of the approach road in the vertical direction (gradient, etc.). .

  The reference position setting means may set the reference position in the intersection area, and may set the position based on the road shape of the approach road in the intersection area as the reference position. Here, the timing at which the reference position moves to the visible range means the timing at which the intersection guidance starts. Therefore, the reference position setting means may set the reference position so that the timing at which the reference position moves to the visible range is the timing at which the intersection guidance should be started. For example, the reference position setting means may set the reference position so that the timing at which the reference position moves to the visible range is the timing at which the driver can recognize the shape of the intersection. The viewable range means a range in front of the vehicle that can be seen by the driver, and may be a range that can be seen in the actual scenery, or can be seen on a screen that displays the scenery in front of the vehicle. It may be a range. The guidance means may start guidance at the timing when the reference position moves within the viewable range, may start guidance by voice, or may start guidance by image. In addition, when the reference position moves within the visible range, the guidance unit may start guidance for superimposing the intersection guidance image on the intersection image. Thereby, a guide image can be superimposed on the image of the intersection in a state where the reference position is visible.

The reference position setting means may set the reference position at an end on the opposite side of the moving direction of the image of the intersection in the target viewing range in the intersection when the road shape of the approach road is a curved shape. When the road shape of the approach road is curved, as the vehicle approaches the intersection, the intersection that originally existed on the left or right side of the traveling direction of the vehicle gradually moves to the front of the vehicle. Become. Therefore, when the road shape of the approach road is a curved shape, the intersection image moves in the horizontal direction. Further, the end on the opposite side of the moving direction of the image of the intersection in the target viewing range is the position that moves within the visible range with the latest delay in the target viewing range. That is, it can be considered that the entire target viewing range can be viewed at the timing at which the opposite end of the moving direction of the image of the intersection in the target viewing range can be viewed.
Therefore, by setting the reference position at the end opposite to the moving direction of the image of the intersection in the target viewing range, the guidance of the intersection can be started at a timing at which the entire target viewing range can be viewed. In addition, a target visual recognition range is a target area | region which should make a driver | operator visually recognize in the timing which starts the guidance of the said intersection among intersections. For example, at the intersection, the approach road and the connection road connected to the approach road intersect so that the guidance of the intersection can be started when it becomes possible to recognize how the approach road is connected to the intersection. The approach area that is being operated may be the target viewing range. Furthermore, the target visual recognition range may be a range depending on the road shape of the approach road, or may be a range independent of the road shape of the approach road.

  The reference position setting means may set the reference position at the end of the approach road on the curvature center side in the target viewing range when the road shape of the approach road is a curved shape. When the road shape of the approach road is curved, as the vehicle approaches the intersection, the intersection that originally existed on the curvature center side of the approach road gradually moves to the front of the vehicle based on the traveling direction of the vehicle It will be. That is, when the road shape of the approach road is a curved shape, the image of the intersection moves to the side opposite to the curvature center of the approach road. Therefore, the reference position can be set at the end of the target viewing range opposite to the moving direction of the image of the intersection in the target viewing range by setting the reference position at the end on the curvature center side of the approach road.

  However, the reference position setting means does not necessarily need to set the reference position at the exact end position of the target viewing range. For example, when the road shape of the approach road is a curved shape, the reference position setting means may correct the reference position to the opposite side of the curvature center by the reference distance from the end of the curvature center side of the approach road in the target viewing range. Good. By setting the reference position at a position corrected to the opposite side of the center of curvature by the reference distance from the end of the center of curvature in the target viewable range, only the period corresponding to the reference distance than the timing at which the entire target viewable range can be seen Intersection guidance can be started at an early timing. Thereby, it can prevent that the guidance of an intersection is overdue. The reference distance may be a distance depending on the shape of the approaching road, or may be a distance independent of the shape of the approaching road.

  By the way, in the map information, when one link is set for each of the approaching road and the opposite road of the approaching road (when the link setting mode for the approaching road is vertically separated), facing the approaching road There is a case where one link is collectively set for a combined road composed of roads (a case where the link setting mode for the approach road is not separated vertically). In general, the larger the size of an intersection or approach road, the higher the possibility that one link is set for each of the approach road and the opposite road of the approach road. When the link setting mode for the approach road is vertical separation, the node at the end point of the link corresponding to the approach road is at the center of the approach area where the approach road and the connection road connecting to the approach road intersect at the intersection. Is set. On the other hand, when the link setting mode for the approaching road is not vertically separated, the end node of the link corresponding to the joining road including the approaching road intersects the joining road and the connecting road connected to the joining road at the intersection. It is set at the center position of the entire area that is the area. Therefore, the position where the node of the end point of the link is set differs between the case where the link setting mode for the approach road is vertical separation and the case where there is no vertical separation. Therefore, the process of setting the reference position starting from the position of the node at the end point of the link may be switched according to the link setting mode for the approach road.

  First, a description will be given of a processing example of the reference position setting means when the link setting mode with respect to the approach road is not vertically separated and the road shape of the approach road is a curved shape in the left direction. In this case, the reference position setting means obtains the center position of the area (overall area) where the combined road and the connected road connected to the combined road intersect based on the map information, and determines the approach road from the central position. A position moved leftward by the width may be specified, and the reference position may be set to a position moved rightward by the reference distance from the specified position. Here, the central position of the entire area is the position of the end node of the link corresponding to the combined road, and can be acquired from the map information. Further, in the width direction, the combined road is approximately divided into two by the approach road and the opposite road, and the opposite road is provided on the right side of the approach road. Therefore, the center position of the entire area is located near the right end in the width direction of the entry area. Therefore, the position moved to the left by the width of the approach road from the center position of the entire area becomes the position of the left end of the approach area. Further, when the road shape of the approach road is a curved shape in the left direction, the left direction is the direction of the curve center side, and the right direction is the direction opposite to the curve center. Accordingly, the curvature of the approach area is determined by identifying the position moved leftward from the center position of the entire area by the width of the approach road and setting the position moved rightward from the identified position by the reference distance as the reference position. A position moved from the end on the center side to the opposite side of the center of curvature by a reference distance can be set as the reference position. Therefore, the guidance of the intersection can be started at a timing earlier by the period corresponding to the reference distance than the timing at which the entire width direction of the approach area can be visually recognized.

  Next, a description will be given of a processing example of the reference position setting means in the case where the link setting mode for the approaching road is not vertically separated and the road shape of the approaching road is a curved shape in the right direction. In this case, the reference position setting means acquires, based on the map information, the center position of the area where the combined road composed of the approach road and the opposite road of the approach road intersects with the connection road connected to the connection road. The reference position may be set at a position moved leftward by the reference distance from the center position. As described above, the center position of the entire area is located near the right end of the entry area. Further, when the road shape of the approach road is a curved shape in the right direction, the right direction is the direction toward the center of the curve, and the left direction is the direction opposite to the center of the curve. Therefore, by setting the position moved to the left by the reference distance from the center position of the entire area as the reference position, the position moved to the opposite side of the curvature center by the reference distance from the end of the entrance area on the curvature center side is set as the reference position. Can be set as Therefore, the guidance of the intersection can be started at a timing earlier by the period corresponding to the reference distance than the timing at which the entire width direction of the approach area can be visually recognized.

  Next, a description will be given of a processing example of the reference position setting unit when the link setting mode for the approach road is vertical separation and the road shape of the approach road is a left-hand curved shape. In this case, the reference position setting means acquires the center position of the area (entrance area) where the approach road and the connection road connected to the approach road intersect based on the map information, and from the center position of the approach road A position moved to the left by half the width may be specified, and the reference position may be set at a position moved from the specified position to the right by a reference distance. Here, the center position of the approach area is the position of the end node of the link corresponding to the approach road, and can be acquired from the map information. Further, when the road shape of the approach road is a curved shape in the left direction, the left direction is the direction of the curve center side, and the right direction is the direction opposite to the curve center. Therefore, the position moved to the left by half the width of the approach road from the center position of the approach area becomes the position of the end of the approach area on the curved center side. Therefore, by specifying the position moved leftward from the central position of the approach area by half the width of the approach road, and setting the position moved rightward from the specified position by the reference distance as the reference position, The position moved from the end on the curvature center side to the opposite side of the curvature center by the reference distance can be set as the reference position. Therefore, the guidance of the intersection can be started at a timing earlier by the period corresponding to the reference distance than the timing at which the entire width direction of the approach area can be visually recognized.

  Further, a processing example of the reference position setting unit when the link setting mode for the approach road is vertically separated and the road shape of the approach road is a curved shape in the right direction will be described. In this case, the reference position setting means acquires the center position of the area (entrance area) where the approach road and the connection road connected to the approach road intersect based on the map information, and from the center position of the approach road The position moved rightward by half the width may be specified, and the reference position may be set at a position moved leftward by the reference distance from the specified position. When the road shape of the approach road is a curved shape in the right direction, the right direction is the direction of the curve center side, and the left direction is the direction opposite to the curve center. Therefore, the position moved to the right by half the width of the approach road from the center position of the approach area is the position of the end of the approach area on the curvature center side. Therefore, by specifying the position moved to the right by half the width of the approach road from the center position of the entry area, and setting the position moved to the left by the reference distance from the specified position as the reference position, The position moved from the end on the curvature center side to the opposite side of the curvature center by the reference distance can be set as the reference position. Therefore, the guidance of the intersection can be started at a timing earlier by the period corresponding to the reference distance than the timing at which the entire width direction of the approach area can be visually recognized.

  The guide means ends the first guidance for the intersection when the reference position moves within the viewable range, and starts the second guidance for the intersection, which is different from the first guidance. May be. That is, the intersection may be guided before the timing when the reference position moves within the viewable range, or the intersection guide mode may transition at the timing when the reference position moves within the viewable range. As a result, the guidance of the intersection can be continuously performed, and the guidance mode is suitable for each of the state where the reference position is not moved within the viewable range and the state where the reference position is moved within the viewable range. You can guide the intersection at.

  Furthermore, the method of starting the guidance of the intersection based on the road shape of the approach road as in the present invention can be applied as a program or a method. In addition, the system, program, and method as described above may be realized as a single device, or may be realized by using components shared with each unit provided in the vehicle when realized by a plurality of devices. It can be assumed and includes various aspects. For example, it is possible to provide a navigation system, method, and program. Further, some changes may be made as appropriate, such as a part of software and a part of hardware. Furthermore, the invention can be realized as a recording medium for a program for controlling the system. Of course, the software recording medium may be a magnetic recording medium, a magneto-optical recording medium, or any recording medium to be developed in the future.

It is a block diagram of a navigation apparatus. 2A and 2B are plan views of the road. 3A and 3B are plan views of the road. 4A and 4B are diagrams showing a front image. It is a flowchart of an intersection guidance process.

Here, embodiments of the present invention will be described in the following order.
(1) Configuration of navigation device:
(2) Intersection guidance processing:
(3) Other embodiments:

(1) Configuration of navigation device:
FIG. 1 is a block diagram showing a configuration of a navigation device 10 as an intersection guidance system according to an embodiment of the present invention. The navigation device 10 is provided in a vehicle. The navigation device 10 includes a control unit 20 and a recording medium 30. The control unit 20 includes a CPU, a RAM, a ROM, and the like, and executes a program stored in the recording medium 30 or the ROM. The recording medium 30 records the map information 30a and the position conversion table 30b.

  The map information 30a includes node data indicating the position of a node set on the road, link data indicating information on a link corresponding to a road connecting the nodes, and the width direction of the road connecting the nodes. And shape interpolation point data indicating the position and the like of the shape interpolation point set on the center line. A node to which three or more links connect corresponds to an intersection. The link data includes information indicating the number and width of lanes provided on the road, information indicating the width of the road, and the like.

  2A, 2B, 3A, 3B are plan views of the road. 2A and 2B and FIGS. 3A and 3B have different link setting modes for roads. In the map information 30a, when one link L (two-dot chain line) is set for each of the road and the opposite road of the road (when the link setting mode for the road is vertically separated: FIGS. 2A and 2B) ) And a single link L is set for a combined road composed of the road and the opposite road of the road (when the link setting mode for the road is not vertically separated: FIGS. 3A and 3B). . Note that the traveling direction of the vehicle is opposite between the road and the opposite road of the road.

  2A, 2B, 3A, and 3B, a thick black line represents a central separator K that partitions a road and an opposite road of the road, and a white line represents a partition line E that partitions the road and a portion outside the road. In addition, illustration of the division line which divides lanes formed on the road is abbreviate | omitted. A double circle indicates the position of the node N, and a white circle indicates the position of the shape interpolation point M. A broken line that sequentially connects nodes that are continuous in the direction of the road and the shape interpolation point M on the same road constitutes a link L. The link L has a node N as a start point and an end point, and represents a center line in the width direction of the road. The node N is set in the intersection C, and when the vehicle is traveling on a road corresponding to a certain link L, the intersection C existing at the node Nt at the end point of the link L travels next. Intersection C When the link setting mode for the road is vertical separation, the link data defines which of the nodes N at both ends of the link L is the end point of the link L (the point where the vehicle leaves the road). When the link setting mode for the road is not vertically separated, the link data indicates the width of the entire combined road composed of the road and the opposite road of the road. In the link data, a link setting mode is associated with each link.

  The position conversion table 30b is a table that defines a correspondence relationship between a position in the visible range Z based on the position of the camera 44 and a position in the front image. The visually recognizable range Z is a space in the field of view when the camera 44 captures a front landscape of the vehicle in the real space in front of the vehicle. The front image is an image generated when the camera 44 captures a front landscape. The position conversion table 30b is created based on the optical specifications (view angle, optical axis direction, optical magnification, etc.) of the camera 44, and is recorded in the recording medium 30 in advance. The control unit 20 obtains a position at which the image of the object existing at the arbitrary position is projected in the front image by converting an arbitrary position within the viewable range Z by the position conversion table 30b. On the other hand, the control unit 20 obtains the position within the visible range Z of the object on which the image is projected at the arbitrary position by converting the arbitrary position in the front image by the position conversion table 30b.

  The vehicle includes a GPS receiver 41, a vehicle speed sensor 42, a gyro sensor 43, a camera 44, and a display 45. The GPS receiver 41 receives radio waves from GPS satellites and outputs a signal for calculating the position of the vehicle to the controller 20 via an interface (not shown). The vehicle speed sensor 42 outputs a signal corresponding to the rotational speed of the wheels included in the vehicle to the control unit 20. The gyro sensor 43 outputs a signal corresponding to the angular acceleration acting on the vehicle to the control unit 20.

  The camera 44 is an image sensor that captures a landscape in the viewable range Z and generates a front image representing the landscape in the viewable range Z. The front image generated by the camera 44 is output to the control unit 20 via an interface (not shown). The camera 44 has an optical system that is symmetrical with respect to the optical axis in the horizontal direction. The camera 44 is provided at the center position in the width direction of the vehicle, and the optical axis coincides with the traveling direction F of the vehicle. As shown in FIGS. 2A, 2B, 3A, and 3B, the viewable range Z in plan view is a range based on the position of the vehicle (camera 44) indicated by a black triangle, and is a straight line extending in the traveling direction F of the vehicle. The reference is a range in which the left and right angles as references are within half A / 2 of the viewing angle A of the camera 44.

  The control unit 20 specifies the traveling direction F of the vehicle based on the output signal from the gyro sensor 43 and the like. Further, the control unit 20 acquires the current position before map matching based on signals output from the GPS receiving unit 41, the vehicle speed sensor 42, the gyro sensor 43, and the like. Furthermore, the control unit 20 specifies a traveling road that is a road on which the vehicle is traveling based on the traveling direction F of the vehicle and the current position before map matching. For example, the control unit 20 selects a road corresponding to the link L closest to the current position before map matching among the links L whose parallelism with respect to the traveling direction F of the vehicle is equal to or greater than a predetermined reference (for example, the angle difference is within 10 degrees). Identified as a road. As shown in FIGS. 2A and 2B, when the link setting mode for the road is vertically separated, the road and the opposite road of the road are close to each other. In this case, the control unit 20 may specify a road corresponding to the link L whose current position before map matching is approaching the position of the end node Nt as a traveling road. Of the positions on the link L corresponding to the traveling road, the control unit 20 maps the position closest to the current position before map matching, that is, the position on the vertical line that has been lowered to the link L from the current position before map matching. The current position Y is specified later. Hereinafter, unless otherwise indicated, the current position Y means the current position Y after map matching.

  2A, 2B, 3A, and 3B, the white triangle indicates the current position Y. The current position Y is a position on the center line in the width direction of the traveling road, that is, on the link L. It is assumed that the vehicle is traveling upward on a traveling road illustrated below the intersection C in the drawing. As shown in FIGS. 2A and 2B, when the link setting mode for the road is vertically separated, one of the roads constituting the combined road is specified as the traveling road, and after map matching on the center line in the width direction of the traveling road Current position Y is identified. On the other hand, as shown in FIGS. 3A and 3B, when the link setting mode for the traveling road is not vertically separated, the entire combined road is specified as the traveling road, and the current after map matching on the center line in the width direction of the combined road The position Y is specified. When the link setting mode for the travel road is not vertically separated, the control unit 20 identifies the node N that is close to the current position Y among the nodes N at both ends of the travel road as the end node Nt of the travel road.

  The display 45 is a video output device that outputs a front image and an image for performing various types of driving support based on the video signal output from the control unit 20. Since the driver can visually recognize the front image on the display 45, the visual field of the camera 44 that captures the front image constitutes a visible range Z that the driver can visually recognize.

The control unit 20 executes the navigation program 21. The navigation program 21 includes a road shape acquisition unit 21a, a reference position setting unit 21b, and a guide unit 21c.
The road shape acquisition unit 21a is a module that causes the control unit 20 to execute a function of acquiring the road shape of the approach road with respect to the intersection C. The approach road is a road on which the vehicle travels when entering the intersection C. As shown in FIGS. 2A and 2B, when the link setting mode of the traveling road is vertically separated, the traveling road coincides with the approach road. On the other hand, as shown in FIGS. 3A and 3B, when the link setting mode of the approach road is not vertically separated, the road on the left side of the travel road (joint road) with respect to the traveling direction F of the vehicle It becomes.

  By the function of the road shape acquisition unit 21a, the control unit 20 acquires a shape interpolation point M existing within a predetermined distance (for example, 300 m) from the end node Nt among the shape interpolation points M on the traveling road. And the control part 20 acquires the change angle B of the direction of the road in each of the shape interpolation points M which exist within the predetermined distance from the node Nt of the end point of the traveling road, and acquires the average value of the change angle B. The change angle B includes a rear vector that is a vector from the nth shape interpolation point M to the (n + 1) th shape interpolation point M, and the (n + 1) th shape interpolation point M to the (n + 2) th shape interpolation point M. It is an angle formed by a forward vector that is a vector toward (or an end node Nt). n is a natural number representing the order in which the shape interpolation points M within a predetermined distance from the node Nt at the end point of the traveling road are counted in order from the node Nt at the end point of the traveling road. The control unit 20 sequentially acquires the change angle B while incrementing n by 1. In plan view, when the forward vector rotates counterclockwise with respect to the backward vector, the change angle B is positive (FIGS. 2A and 3A), and the forward vector rotates clockwise with respect to the backward vector. In such a case, the change angle B is negative (FIGS. 2B and 3B).

  By the function of the road shape acquisition unit 21a, the control unit 20 determines that the road shape of the traveling road is a left-hand curved shape when the average value of the change angles B is greater than or equal to a positive threshold (for example, 10 degrees). To do. On the other hand, when the average value of the change angles B is equal to or less than a negative threshold (for example, −10 degrees), the control unit 20 determines that the road shape of the traveling road is a right-hand curved shape. When the shape interpolation point M does not exist within a predetermined distance from the end node Nt, and when the average value of the change angles B is larger than the negative threshold and smaller than the positive threshold, the control unit 20 It is determined that the road shape is straight.

  As shown in FIGS. 2A and 2B, when the link setting mode for the traveling road is vertically separated, the traveling road and the approach road match. Therefore, when the link setting mode for the traveling road is vertically separated, the control unit 20 acquires the road shape of the traveling road as the road shape of the approaching road. On the other hand, as shown in FIGS. 3A and 3B, when the link setting mode for the traveling road is not vertically separated, the road on the left side of the traveling road with respect to the traveling direction F of the vehicle is the approach road. However, since the road shape of the combined road (traveling road) composed of the approaching road and the oncoming road and the road shape of the approaching road alone can be regarded as the same, the control unit 20 determines that the link setting mode for the traveling road is up and down. Even without separation, the road shape of the traveling road is acquired as the road shape of the approach road.

  The reference position setting unit 21b is a module that causes the control unit 20 to execute a function of setting the reference position Q in the intersection C based on the road shape of the approach road. Specifically, the control unit 20 uses the function of the reference position setting unit 21b to change the movement direction of the image of the intersection C in the target viewing range T (hatching) in the intersection C when the road shape of the approach road is a curved shape. A reference position Q is set at the opposite end. More specifically, by the function of the reference position setting unit 21b, the control unit 20 sets the reference position Q at the end on the curvature center side of the approach road in the target viewing range T when the road shape of the approach road is a curved shape. To do.

  When the road shape of the approach road is a curved shape, as the vehicle approaches the intersection C, the intersection C that originally existed on the curvature center side of the approach road with respect to the traveling direction F of the vehicle gradually becomes the front of the vehicle. Will be moved to. That is, when the road shape of the approach road is a curved shape, the image of the intersection C moves to the side opposite to the curvature center of the approach road. Therefore, the end on the opposite side of the moving direction of the image of the intersection C in the target viewing range T means the end on the curvature center side of the approach road in the target viewing range T. Accordingly, by setting the reference position Q at the end of the approach road in the target viewing range T on the curvature center side, the reference position is set at the end on the opposite side of the moving direction of the image of the intersection C in the target viewing range T (within the broken line frame). Q can be set.

  As shown in FIGS. 2A and 3A, when the road shape of the approach road is a curved shape in the left direction, the moving direction of the image of the intersection C in the front image is the right direction as the direction opposite to the center of curvature. 4A and 4B show front images when the road shape of the approach road is a left-hand curved shape. FIG. 4B shows a front image in a state where the vehicle is closer to the intersection C than in FIG. 4A. As shown in FIGS. 4A and 4B, when the road shape of the approach road is a left-hand curved shape, the image of the intersection C moves to the right as the vehicle approaches the intersection C. In FIG. 4A, an image of a region that exists on the left side of the visible range Z and on which no image is projected on the front image is also shown for reference. When the road shape of the approaching road is a left-hand curved shape, the image of the area existing on the left side of the viewable range Z also moves in the front image as the vehicle approaches the intersection C. It becomes. On the other hand, as shown in FIGS. 2B and 3B, when the road shape of the approach road is a curved shape in the right direction, the moving direction of the image of the intersection C in the front image is the left direction as the opposite direction of the center of curvature.

In the present embodiment, as shown in FIGS. 2A, 2B, 3A, and 3B, the target visual recognition range T is an entry area that is an area where an approach road and a connection road connected to the approach road intersect at an intersection C. is there. Specifically, the target visual recognition range T is a range surrounded by extension lines at both ends in the width direction of the approach road and extension lines at both ends in the width direction of the connection road connected to the approach road.
Accordingly, the end on the curvature center side of the approach road in the target visual recognition range T is located on the extension line of the end on the curvature center side of the approach road.

However, in this embodiment, the reference position Q is not set at the exact end position on the curvature center side of the approach road in the target visual recognition range T, but at the position corrected from the end on the curvature center side of the approach road. Set Q. By the function of the reference position setting unit 21b, the control unit 20 allows the reference distance S to be opposite to the center of curvature from the end of the approach road at the curvature center side of the approach road when the road shape of the approach road is curved. The reference position Q is corrected. In the present embodiment, the reference distance S is set to a predetermined value smaller than the average lane width, and is recorded on the recording medium 30.
In the above, the reference position Q is the reference distance S from the end on the curvature center side of the approach road in the target viewing range T, which is an area where the approach road intersects with the connection road connected to the approach road at the intersection C. The position corrected to the opposite side of the center of curvature has been described using the concept of the target viewing range T.

  Hereinafter, a substantial process for setting the reference position Q will be described. With the function of the reference position setting unit 21b, the control unit 20 sets the reference position Q starting from the position of the node Nt at the end point of the traveling road. Here, when the link setting mode for the traveling road is vertically separated, the node Nt at the end of the traveling road (entrance road) is an approach where the approach road and the connection road connected to the approach road intersect at the intersection C It is set at the center position of the region (target viewing range T). On the other hand, when the link setting mode for the traveling road is not vertically separated, the node Nt at the end of the traveling road (joint road) is an area where the joint road and the connected road connected to the joint road intersect at the intersection C. It is set at the center position of a certain entire region V (inside the one-dot chain line frame in FIGS. 3A and 3B). Therefore, the position where the node Nt of the end point of the traveling road is set is different between the case where the link setting mode for the traveling road is vertically separated and the case where the link setting aspect for the traveling road is not vertically separated. In addition, the direction of the curvature center of the approach road differs depending on the curve direction of the approach road. Therefore, the function of the reference position setting unit 21b allows the control unit 20 to perform substantive processing for setting the reference position Q starting from the position of the node Nt at the end point of the traveling road. Switch as follows according to the combination with the direction.

  First, as shown in FIG. 3A, the processing of the reference position setting unit 21b in the case where the link setting mode for the traveling road is not vertically separated and the road shape of the approach road is a left-side curved shape will be described. In this case, by the function of the reference position setting unit 21b, the control unit 20 acquires the center position of the entire region V where the combined road and the connected road connected to the combined road intersect based on the map information 30a, and A position moved to the left by the width W of the approach road from the central position is specified, and a reference position Q is set at a position moved to the right by the reference distance S from the specified position.

  Here, the central position of the entire region V is the position of the node Nt at the end point of the traveling road (joint road), and can be acquired from the map information 30a. Further, in the width direction, the combined road is almost divided into an approach road and an opposite road, and the opposite road is provided on the right side of the approach road. Therefore, the central position of the entire area V is located near the right end in the width direction of the target visual recognition range T (entrance area). Therefore, the position moved to the left by the width W of the approach road from the central position of the entire area V is the position of the left end of the target viewing range T. Further, when the road shape of the approach road is a curved shape in the left direction, the left direction is the direction of the curve center side, and the right direction is the direction opposite to the curve center. Accordingly, the position moved leftward from the central position of the entire area V by the width of the approach road is specified, and the position moved rightward by the reference distance S from the specified position is set as the reference position Q. As a reference position Q, the position moved (corrected) from the end of the target visual recognition range T toward the opposite side of the curvature center by the reference distance S can be set.

  In addition, the control part 20 should just acquire the width | variety of the traveling road (joining road) from link data, and acquire the width | variety of the width of the said traveling road as the width W of an approach road. Here, the right direction and the left direction when setting the reference position Q are based on the direction of the traveling road (joint road or approach road) at the intersection C. Specifically, the control unit 20 specifies the direction rotated counterclockwise by 90 degrees from the direction of the traveling road at the intersection C in the plan view as the left direction. On the other hand, the control unit 20 specifies the direction rotated clockwise by 90 degrees from the direction of the traveling road at the intersection C as the right direction in plan view. The control unit 20 determines the direction of the vector from the shape interpolation point M closest to the node Nt at the end point of the traveling road among the shape interpolation points M on the road to the intersection C. Obtained as the direction of the traveling road at

  Next, as shown in FIG. 3B, a description will be given of a processing example of the reference position setting unit 21b when the link setting mode for the traveling road is not vertically separated and the road shape of the approach road is a curved shape in the right direction. To do. In this case, the control unit 20 uses the function of the reference position setting unit 21b so that the combined road composed of the approach road and the opposite road of the approach road intersects with the connection road connected to the join road. The center position is acquired based on the map information 30a, and the reference position Q is set at a position moved from the center position to the left by the reference distance S. As described above, the central position of the entire region V is located near the right end of the target viewing range T. Further, when the road shape of the approach road is a curved shape in the right direction, the right direction is the direction toward the center of the curve, and the left direction is the direction opposite to the center of the curve. Therefore, by setting, as the reference position Q, the position moved to the left by the reference distance S from the center position of the entire region V, as a result, the reference road S is the reference distance S from the end of the target viewing range T on the curvature center side. A position moved (corrected) to the opposite side of the center of curvature can be set as the reference position Q.

  Next, as shown in FIG. 2A, a description will be given of a processing example of the reference position setting unit 21b when the link setting mode with respect to the traveling road is vertically separated and the road shape of the approach road is a curved shape in the left direction. To do. In this case, the control unit 20 uses the function of the reference position setting unit 21b to map the center position of the approach area (target viewing range T) that is an area where the approach road intersects with the connection road connected to the approach road. 30a is acquired based on 30a, the position moved leftward from the center position by half W / 2 of the width W of the approach road is specified, and the reference position is set to the position moved rightward from the specified position by the reference distance S Set Q. Since the center position of the target viewing range T matches the position of the node Nt at the end point of the traveling road (entrance road), the control unit 20 can acquire the center position of the target viewing range T from the map information 30a. Since the width of the target viewing range T is the width of the approaching road, the position moved to the left by half W / 2 of the width W of the approaching road from the center position of the target viewing range T is the position of the left end of the target viewing range T It becomes. Further, when the road shape of the approach road is a curved shape in the left direction, the left direction is the direction of the curve center side, and the right direction is the direction opposite to the curve center. Therefore, a position moved leftward by a half W / 2 of the width W of the approach road from the center position of the target viewing range T is specified, and a position moved rightward from the specified position by the reference distance S is determined as the reference position Q. As a result, the position moved (corrected) by the reference distance S from the end on the curvature center side of the target viewing range T to the opposite side of the curvature center can be set as the reference position Q.

  Furthermore, as shown in FIG. 2B, a description will be given of a processing example of the reference position setting unit 21b in the case where the link setting mode for the traveling road is vertically separated and the road shape of the approach road is a curved shape in the right direction. . In this case, the control unit 20 uses the function of the reference position setting unit 21b to map the center position of the approach area (target viewing range T) that is an area where the approach road intersects with the connection road connected to the approach road. 30a is acquired based on 30a, a position moved rightward by half W / 2 of the width W of the approach road from the center position, and a reference position at a position moved leftward by the reference distance S from the specified position Set Q. As described above, the center position of the target viewing range T is the center position in the width direction of the approach road. Therefore, the position moved to the right by half W / 2 of the width W of the approach road from the center position of the target viewing range T is the right end position of the target viewing range T. Further, when the road shape of the approach road is a curved shape in the right direction, the right direction is the direction toward the center of the curve, and the left direction is the direction opposite to the center of the curve. Therefore, a position moved rightward by a half W / 2 of the width W of the approach road from the center position of the target viewing range T is specified, and a position moved leftward by the reference distance S from the specified position is set as the reference position Q. As a result, the position moved from the end of the target visual recognition range T on the curvature center side by the reference distance S to the opposite side of the curvature center can be set as the reference position Q.

  The guide unit 21c is a module that causes the control unit 20 to execute a function of starting the guidance of the intersection C when the reference position Q moves within the visible range Z that can be visually recognized by the driver. That is, the control unit 20 starts guidance at the timing when the reference position Q moves within the visible range Z by the function of the guide unit 21c.

  In determining whether or not the reference position Q has moved within the viewable range Z, the control unit 20 uses the function of the guide unit 21c to determine the position of the camera 44 based on the current position Y and the image recognition of the front image (see FIG. 2A, 2B, 3A, 3B) is specified. The control unit 20 recognizes an image of a line existing at the right end or the left end in the width direction of the approach road from the front image by executing a known line recognition method or pattern recognition method on the front image. In the present embodiment, the control unit 20 recognizes an image of a line at the lower end of the median strip K existing at the right end of the approach road in the front images shown in FIGS. 4A and 4B. Then, the control unit 20 converts the position of the intersection point R between the lower side of the front image and the lower end line of the central separation band K by the position conversion table 30b, whereby the distance between the central separation band K and the camera 44 in the real space. Get X.

  As shown in FIGS. 3A and 3B, when the link setting mode for the traveling road is without vertical separation, the current position Y on the link L can be considered to exist on the central separation zone K. An auxiliary line G (broken line) passing through the current position Y and perpendicular to the link L is generated, and the position moved leftward from the current position Y by the distance X on the auxiliary line G is specified as the position of the camera 44 To do. On the other hand, as shown in FIGS. 2A and 2B, when the link setting mode for the traveling road is vertically separated, the position of the link L is the position on the center line in the width direction of the approach road. An auxiliary line G that passes through the position Y and is perpendicular to the link L is generated, and moved on the auxiliary line G from the current position Y on the link L to the right by a half W / 2 of the width W of the approach road. The position is specified as the position of the median strip K. Then, the control unit 20 identifies the position moved leftward from the position of the central separation band K by the distance X on the auxiliary line G as the position of the camera 44. In the above, the procedure for specifying the position of the camera 44 based on the position of the median strip K has been described. However, when the image of the lane marking E at the left end of the approach road is included in the forward image, the approach road The position of the camera 44 may be specified on the basis of the position of the image of the lane marking E at the left end. Further, the traveling lane in which the vehicle is traveling may be identified based on the recognition result of the image of the lane marking E that divides the plurality of lanes on the approach road, and the position of the camera 44 may be identified based on the traveling lane. .

  When the position of the camera 44 is specified as described above, the control unit 20 forms a straight line extending from the position of the camera 44 in the traveling direction F of the vehicle and a straight line extending from the position of the camera 44 to the reference position Q. The absolute value of the angle is calculated, and when the absolute value of the angle is equal to or less than half A / 2 of the viewing angle A of the camera 44, it is determined that the reference position Q has moved within the viewable range Z.

  When the reference position Q moves within the viewable range Z by the function of the guide part 21c, the control part 20 ends the first guidance for the intersection C and is the guidance for the intersection C, which is different from the first guidance. The second guidance in the guidance mode is started. That is, the control unit 20 guides the intersection C even before the timing when the reference position Q moves within the viewable range Z, and guides the intersection C when the reference position Q moves within the viewable range Z. Aspect transitions.

  In the present embodiment, the guidance mode of the first guidance is a guidance mode in which an arrow image U indicating the recommended traveling direction at the intersection C is displayed above the image of the intersection C as shown in FIG. 4A. On the other hand, the guidance mode of the second guidance is a guidance mode in which the arrow image U is displayed superimposed on the image of the intersection C as shown in FIG. 4B. With the function of the guide unit 21c, the control unit 20 searches for a planned travel route by a known route search method in advance. Then, when the approach road is a road on the planned travel route, the control unit 20 acquires a recommended traveling direction at the intersection C where the vehicle travels next. The control unit 20 obtains an exit road on which the vehicle is scheduled to travel next to the intersection C on the planned travel route, and recommends the direction of travel when taking the course from the entrance road to the exit road. Get as the direction of travel. The arrow image U represents a broken line arrow in which a portion (vertical linear portion) representing the traveling direction of the vehicle on the approach road and a portion representing the traveling direction of the vehicle on the exit road are bent at the inflection point U1. 4A and 4B show an example in which the recommended traveling direction is the left turn direction. The arrow image U is recorded in the recording medium 30 for each angle of the vehicle traveling direction on the exit road with respect to the vehicle traveling direction on the approach road.

  When the reference position Q has not moved within the viewable range Z, the control unit 20 superimposes the arrow image U on the background image J. The background image J is a plain image having a height and width that are larger than the height and width of the arrow image U by a predetermined amount, and is recorded on the recording medium 30. The control unit 20 superimposes the background image J on which the arrow image U is superimposed at a position higher than the horizon in the front image, and connects the upper end to the lower end of the background image J and the lower end to a position in the image of the intersection C. The connection image I to be connected is further superimposed on the front image. Specifically, the control unit 20 specifies a position in the front image corresponding to the superimposition reference position by converting a predetermined superimposition reference position set in the target viewing range T by the position conversion table 30b. The lower end of the connection image I is superimposed on the specified position. For example, the overlapping reference position may be the center position in the width direction of the target viewing range T. In the case of vertical separation, the position of the node Nt at the end point of the traveling road can be acquired as the superposition reference position. In the case where there is no vertical separation, a position moved to the left by half W / 2 of the width W of the approach road from the position of the node Nt at the end point of the traveling road can be acquired as the overlapping reference position. Then, the control unit 20 performs the first guidance by causing the display 45 to display a front image in which the arrow image U, the background image J, and the connection image I are superimposed.

  When the reference position Q moves within the viewable range Z, the control unit 20 superimposes the arrow image U on the front image as it is, and causes the display 45 to display the front image on which the arrow image U is superimposed. Give guidance. The control unit 20 specifies the position of the image of the intersection C in the forward image, and superimposes the arrow image U on the image of the intersection C. For example, the control unit 20 may superimpose the arrow image U on the front image so that the bending point U1 of the arrow image U is superimposed on the position in the front image corresponding to the superimposition reference position.

  The said structure WHEREIN: The 2nd guidance about the intersection C can be started at the timing when the reference position Q set based on the road shape of the approach road became visible. Therefore, the second guidance for the intersection C can be started at a timing suitable for the road shape of the approach road. The end on the opposite side of the moving direction of the image of the intersection C in the target visual recognition range T is a position that moves in the visual recognition range Z with the latest delay in the target visual recognition range T. That is, it can be considered that the entire target viewing range T can be viewed at the timing at which the end of the image of the intersection C in the target viewing range T can be viewed on the opposite side. Accordingly, the second guidance for the intersection C can be started at a timing at which the entire target viewing range T can be viewed. Moreover, since the target visual recognition range T is an approach area where the approach road is connected at the intersection C, the intersection C can be recognized at the timing when the approach road can be recognized with respect to the intersection C. The second guidance can be started. As described above, when the road shape of the approach road is a curved shape, the image of the intersection C moves to the side opposite to the curvature center of the approach road. Therefore, by setting the reference position Q at the end of the approach road in the target viewing range T on the curvature center side, the reference position Q can be set at the end of the target viewing range T opposite to the moving direction of the image of the intersection C.

  Further, the reference position Q is not set at the exact end position on the curvature center side of the approach road in the target visual recognition range T, but on the opposite side of the curvature center by the reference distance S from the end on the curvature central side in the target visual recognition range T. By setting the reference position Q at the corrected position, the guidance of the intersection C can be started at a timing earlier by the period corresponding to the reference distance S than the timing at which the entire target viewing range T can be visually recognized. Thereby, it can prevent that the transition to 2nd guidance is overdue. In the present embodiment, the target visual recognition range T is an approach area where an approach road and a connection road connected to the approach road intersect at an intersection C, and the reference distance S is a predetermined value smaller than the average lane width. Is set to Therefore, it can be considered that the lane configuration of the approach road before the intersection C can be recognized at the timing when the reference position Q can be visually recognized. Therefore, the second guidance can be started at the timing when the lane configuration of the approach road before the intersection C can be recognized.

  As described above, regardless of the combination of the link setting mode for the traveling road and the curve direction of the approaching road, the end of the target viewing range T on the curvature center side starts from the position of the node Nt at the end of the traveling road. The position moved from the center of curvature to the opposite side of the center of curvature from the distance can be set as the reference position Q. Therefore, regardless of the combination of the link setting mode for the traveling road and the curve direction of the approach road, the timing at which the entire target viewing range T, which is the approach area to which the approach road is connected, can be visually recognized at the intersection C. In addition, guidance for the intersection C can be started at an earlier timing for a period corresponding to the reference distance S.

  Further, the control unit 20 uses the function of the guide unit 21c to end the first guidance for the intersection C when the reference position Q moves within the viewable range Z, and also guides the intersection C to the first guidance. The 2nd guidance of a different guidance mode is started. As a result, the guidance of the intersection C can be continued, and the reference position Q is not moved within the viewable range Z and the reference position Q is moved within the viewable range Z. The intersection C can be guided in a guidance mode suitable for the above. In particular, in this embodiment, the arrow image U can be superimposed on the image of the intersection C where the reference position Q is visible. Further, since the position of the camera 44 is accurately specified by image recognition of the front image, it can be accurately determined whether or not the reference position Q has moved within the viewable range Z with the position of the camera 44 as a reference.

(2) Intersection guidance processing:
FIG. 5 is a flowchart of the intersection guidance process. The intersection guidance process is a process executed every predetermined time period or mileage period. First, the control part 20 acquires the road shape of the approach road by the function of the road shape acquisition part 21a (step S100). Specifically, the control unit 20 determines the nth shape in the order counted from the end point Nt of the travel road in the shape interpolation point M within a predetermined distance (for example, 300 m) from the end point node Nt of the travel road. A backward vector that is a vector from the interpolation point M to the (n + 1) th shape interpolation point M and a (n + 1) th shape interpolation point M to the (n + 2) th shape interpolation point M (or the end node Nt). Based on the average value of the change angle B which is an angle formed by the front vector which is a vector, the road shape of the traveling road is a straight line, a left curve, or a right curve. Determine whether. Since the road shape of the traveling road can be regarded as the same as the road shape of the approaching road regardless of the link setting mode for the traveling road, the control unit 20 acquires the road shape of the traveling road as the road shape of the approaching road.

  Next, the control part 20 acquires the link setting aspect with respect to a travel road by the function of the reference | standard position setting part 21b (step S105). The link setting mode for the traveling road can be acquired based on the link data of the map information 30a. Thus, a combination of the link setting mode for the traveling road and the road shape of the approach road is obtained. In the subsequent processing (steps S100 to S145), the control unit 20 sets the reference position Q in the intersection C based on the road shape of the approach road by the function of the reference position setting unit 21b.

  By the function of the reference position setting unit 21b, the control unit 20 determines whether or not the link setting mode for the traveling road is vertical separation and the road shape of the approach road is a left-hand curved shape (step S110). ). When it is determined that the link setting mode for the traveling road is not vertically separated and the road shape of the approach road is a curved shape in the left direction (step S110: Y), the control unit 20 is controlled by the function of the reference position setting unit 21b. Acquired the center position of the entire area V where the connecting road and the connecting road connecting to the connecting road intersect based on the map information 30a, and moved to the left by the width W of the approach road from the center position. The position is specified, and the reference position Q is set to the position moved to the right by the reference distance S from the specified position (step S115, FIG. 3A). Note that the control unit 20 can acquire the position of the node Nt at the end point of the traveling road (joint road) as the central position of the entire region V. By setting the reference position Q as described above, as a result, on the curvature center side of the target visual recognition range T that is an approach area where the approach road and the connection road connected to the approach road intersect at the intersection C. A position moved (corrected) by the reference distance S from the end to the opposite side of the center of curvature of the approach road can be set as the reference position Q.

  Next, by the function of the reference position setting unit 21b, the control unit 20 determines whether or not the link setting mode for the traveling road is vertical separation and the road shape of the approach road is a right-hand curved shape. (Step S120). When it is determined that the link setting mode for the traveling road is not vertically separated and the road shape of the approach road is a curved shape in the left direction (step S120: Y), the control unit 20 is controlled by the function of the reference position setting unit 21b. Is based on the map information 30a, and acquires the central position of the entire area V where the combined road composed of the approach road and the opposite road of the approach road intersects with the connection road connected to the connection road. A reference position Q is set at a position moved leftward by a reference distance S from the position (step S125, FIG. 3B). By setting the reference position Q as described above, as a result, the position moved (corrected) to the opposite side of the curvature center of the approach road from the end of the target viewing range T on the curvature center side by the reference distance S is obtained. Q can be set.

  Next, by the function of the reference position setting unit 21b, the control unit 20 determines whether or not the link setting mode with respect to the traveling road is vertically separated, and the road shape of the approach road is a left-side curved shape. (Step S130). When it is determined that the link setting mode for the traveling road is vertically separated and the road shape of the approaching road is a curved shape in the left direction (step S130: Y), the approaching road and the connecting road connected to the approaching road The center position of the approach area (target viewing range T) that is an area intersecting with is acquired based on the map information 30a, and moved to the left by half W / 2 of the width W of the approach road from the center position. The position is specified, and the reference position Q is set to the position moved to the right by the reference distance S from the specified position (step S135, FIG. 2A). The control unit 20 can acquire the position of the node Nt at the end point of the traveling road (entrance road) as the center position of the target viewing range T. By setting the reference position Q as described above, as a result, the position moved (corrected) by the reference distance S from the end of the target viewing range T on the curvature center side to the opposite side of the curvature center is set as the reference position Q. it can.

  Next, by the function of the reference position setting unit 21b, the control unit 20 determines whether or not the link setting mode for the traveling road is vertically separated and the road shape of the approach road is a right-hand curved shape. (Step S140). When it is determined that the link setting mode for the traveling road is vertically separated and the road shape of the approach road is a curved shape in the right direction (step S140: Y), the control unit 20 is controlled by the function of the reference position setting unit 21b. Acquires the center position of the approach area (target viewing range T), which is the area where the approach road and the connection road connecting to the approach road intersect, based on the map information 30a, A position moved rightward by half W / 2 of the width W is specified, and a reference position Q is set to a position moved leftward by the reference distance S from the specified position (step S145, FIG. 2B). By setting the reference position Q as described above, as a result, it is possible to set, as the reference position Q, the position moved from the end of the target visual recognition range T to the opposite side of the curvature center by the reference distance S.

  As described above, when the reference position Q is set when the road shape of the approach road is a curved shape, the control unit 20 determines whether the reference position Q has moved within the visible range Z by the function of the guide unit 21c. Is determined (step S150). Specifically, the control unit 20 includes a straight line extending from the position of the camera 44 specified based on the current position Y and the image recognition of the front image (black triangle in FIGS. 2A, 2B, 3A, and 3B) to the reference position Q, When the absolute value of the angle formed by the straight line extending in the traveling direction F of the vehicle from the position of the camera 44 is not more than half A / 2 of the viewing angle A of the camera 44, the reference position Q moves within the viewable range Z. It is determined that

  When it is determined that the reference position Q has moved within the viewable range Z (step S150: Y), the control unit 20 uses the function of the guide unit 21c to determine whether the remaining distance from the vehicle to the intersection C is equal to or less than a threshold value. Is determined (step S155). The threshold value (for example, 300 m) is recorded on the recording medium 30. The control unit 20 acquires a straight line distance between the current position Y after the map matching and the position of the node Nt at the end point of the traveling road as the remaining distance.

  When it is not determined that the remaining distance from the vehicle to the intersection C is equal to or less than the threshold (step S155: N), the control unit 20 performs the first guidance for the intersection C by the function of the guide unit 21c (step S160, FIG. 4A). Even when it is not determined that the reference position Q has moved within the viewable range Z (step S150: N), the control unit 20 performs the first guidance for the intersection C by the function of the guide unit 21c. Specifically, the control unit 20 acquires the recommended travel direction at the intersection C based on the planned travel route searched in advance, and acquires the arrow image U indicating the recommended travel direction from the recording medium 30. Then, the control unit 20 superimposes the background image J on which the arrow image U is superimposed at a position higher than the horizon in the forward image, connects the upper end to the lower end of the background image J, and the lower end in the image of the intersection C. The connection image I connected to the position is further superimposed on the front image. Furthermore, the control unit 20 performs the first guidance by causing the display 45 to display a front image in which the arrow image U, the background image J, and the connection image I are superimposed.

  On the other hand, when it is determined that the remaining distance from the vehicle to the intersection C is equal to or less than the threshold (step S155: Y), the control unit 20 performs the second guidance for the intersection C by the function of the guide unit 21c (step S165, FIG. 4B). That is, the control unit 20 starts the second guidance for the intersection C when the reference position Q moves within the viewable range Z visible to the driver by the function of the guide unit 21c. Specifically, the control unit 20 superimposes the arrow image U on the image of the intersection C in the front image. By the above processing, when the road shape of the approach road is a curved shape, guidance of the intersection C is performed at the timing when the reference position Q moves within the viewable range Z in a state where the remaining distance from the vehicle to the intersection C is equal to or less than the threshold value. Can be changed from the first guide to the second guide. That is, the guidance of the intersection C can be changed from the first guidance to the second guidance at a timing at which it can be considered that the lane configuration of the approach road before the intersection C can be recognized.

  If the road shape of the approach road is not curved (steps S110, S120, S130, and S140: N), the control unit 20 uses the function of the guide unit 21c to set the reference position Q (steps S115 and S125). , S135, S145) and the process of determining whether or not the reference position Q has moved within the viewable range Z (step S150) is skipped and step S155 is executed. That is, when the road shape of the approaching road is a straight line, the guidance at the intersection C is changed from the first guidance to the second guidance at the timing when the remaining distance from the vehicle to the intersection C is equal to or less than the threshold value.

(3) Other embodiments:
In the embodiment, the road shape of the approach road is acquired based on the shape interpolation point M data of the map information 30a. However, the road shape of the approach road may be acquired based on image recognition of the front image. The road shape of the approach road may be the shape (gradient or the like) of the approach road in the vertical direction. For example, when the approaching road has an uphill road shape, the control unit 20 sets the reference position Q at a predetermined position in the direction of the approaching road (front-rear direction) at the intersection C by the function of the reference position setting unit 21b. Also good. And the control part 20 may start the guidance of the intersection C, when the reference position Q moves to the height within the viewing angle of the vertical direction of the camera 44 by the function of the guide part 21c. Further, the road shape of the approach road may be the width of the approach road, the number of lanes, or the like, or the reference position Q may be set based on the width of the approach road, the number of lanes, or the like. .

  With the function of the reference position setting unit 21b, the control unit 20 may set the reference position Q so that the timing at which the reference position Q moves to the viewable range Z is the timing at which the guidance of the intersection C should be started. For example, the control unit 20 may set the reference position Q so that the timing at which the reference position Q moves to the visible range Z becomes the timing at which the driver can recognize the shape of the intersection C. Specifically, the control unit 20 may set the reference distance S to be smaller as the curvature radius of the approach road is smaller. That is, the reference distance S may be a distance depending on the road shape of the approach road. Here, as the radius of curvature of the approach road is smaller, the shape of the image of the intersection C in the forward image becomes more irregular, and the shape of the intersection C becomes difficult to recognize. Accordingly, by setting the reference distance S to be smaller as the curvature radius of the approaching road is smaller, the reference position Q is in the visible range Z so that the driver can recognize the delay in the timing at which the shape of the intersection C can be recognized. The movement timing can be delayed. By the way, when the road shape of the approach road is a curved shape in the right direction, the image of the intersection C is shielded by the median strip K, and the timing at which the driver can recognize the shape of the intersection C may be delayed. Therefore, the control unit 20 may set the reference distance S smaller when the road shape of the approach road is a curved shape in the right direction than when the road shape of the approach road is a curved shape in the left direction. Further, the target visual recognition range T may be a range depending on the shape of the approaching road, and the width of the target visual recognition range T may be reduced as the curvature radius of the approaching road is smaller.

  Furthermore, the control part 20 should just start the guidance of the intersection C at the timing which the reference position Q moved in the visible range Z by the function of the guidance part 21c, and may start guidance by an audio | voice. Moreover, the guidance of the intersection C should just be the guidance which shows the information about the intersection C, and does not necessarily need to guide the advancing direction in the intersection C. For example, the control unit 20 may guide the intersection C, the name, the name of the connection road, the destination of the connection road, the lane configuration before the intersection C, and the like. The control unit 20 determines whether or not the reference position Q has moved within the viewable range Z with reference to the position of the camera 44 specified based on the image recognition of the front image by the function of the guide unit 21c. It may be determined whether or not the reference position Q has moved within the viewable range Z with reference to the current position Y after map matching or the current position before map matching.

  Further, the target visual recognition range T may not be an approach area where the approach road and the connection road connected to the approach road intersect at the intersection C, and the joint road and the connection road connected to the joint road intersect. The entire area V (FIGS. 3A and 3B) that is being displayed may be the target viewing range T. When the vehicle turns to the right, since the vehicle travels toward the oncoming road, the control unit 20 may set the entire entire region V as the target viewing range T.

  In the embodiment, the viewable range Z is set based on the field of view of the camera 44 that captures the front image. However, the control unit 20 recognizes the viewable range Z based on the field of view when the driver views the actual scenery. May be set. In addition, when the map information 30a in which the link setting mode for the road is unified with either vertical separation or no vertical separation is used, the control unit 20 determines the reference position Q according to the link setting mode for the road. There is no need to switch the process of setting.

  In the above, an example in which guidance for the intersection C is performed on a so-called left-hand road is given, but the present invention can be applied even when guidance for the intersection C is performed on a right-hand road. With the function of the reference position setting unit 21b, when the road shape of the approach road is a leftward curved shape, the control unit 20 connects to the combined road composed of the approach road and the opposite road of the approach road, and the connected road. The center position of the entire area V intersecting with the connecting road to be acquired is acquired based on the map information 30a, and the reference position Q is set to the position moved to the right by the reference distance S from the center position. The reference position Q can be appropriately set even on a traffic road. Similarly, by the function of the reference position setting unit 21b, when the road shape of the approach road is a curved shape in the right direction, the control unit 20 and the joint road including the approach road and the opposite road of the approach road, and the joint Based on the map information 30a, the central position of the entire area where the connecting road connecting to the road intersects is acquired, the position moved rightward from the central position by the width of the approach road is specified, and the specified position By setting the reference position Q at the position moved to the left by the reference distance S from the vehicle, the reference position Q can be appropriately set even on a right-handed road.

  DESCRIPTION OF SYMBOLS 10 ... Navigation apparatus, 20 ... Control part, 21 ... Navigation program, 21a ... Road shape acquisition part, 21b ... Reference | standard position setting part, 21c ... Guide part, 30 ... Recording medium, 30a ... Map information, 30b ... Position conversion table, DESCRIPTION OF SYMBOLS 41 ... GPS receiving part, 42 ... Vehicle speed sensor, 43 ... Gyro sensor, 44 ... Camera, 45 ... Display, A / 2 ... Half, B ... Change angle, C ... Intersection, E ... Dividing line, F ... Traveling direction, G ... auxiliary line, M ... shape interpolation point, N ... node, Q ... reference position, S ... reference distance, T ... target visual recognition range, U ... arrow image, Y ... current position, Z ... visual recognition range.

Claims (6)

Road shape acquisition means for acquiring the road shape of the approach road with respect to the intersection;
Reference position setting means for setting a reference position in the intersection based on the road shape of the approach road;
Guidance means for starting guidance of the intersection when the reference position moves within a viewable range visible to the driver;
Intersection guidance system with The reference position setting means, when the road shape of the approach road is a curved shape, sets the reference position at the opposite end of the moving direction of the image of the intersection in the target viewing range in the intersection;
The intersection guidance system according to claim 1. The reference position setting means, when the road shape of the approach road is a curved shape, sets the reference position at the end of the approach road on the curvature center side in the target viewing range in the intersection ;
The intersection guidance system according to claim 1 . When the road shape of the approach road is a curved shape, the reference position setting means is opposite to the curvature center of the approach road by a reference distance from an end on the curvature center side of the approach road in the target viewing range in the intersection. Correct the reference position to the position moved to the side,
The intersection guidance system according to claim 3. A road shape acquisition step in which the road shape acquisition means acquires the road shape of the approach road with respect to the intersection;
A reference position setting step in which a reference position setting means sets a reference position in the intersection based on a road shape of the approach road;
A guidance step of starting guidance for the intersection when the reference position moves within a viewable range visible to the driver;
Intersection guide method including Computer
Road shape acquisition means for acquiring the road shape of the approach road with respect to the intersection ;
Reference position setting means for setting a reference position in the intersection based on the road shape of the approach road ;
Guidance means for starting guidance of the intersection when the reference position moves within a viewable range visible to the driver ;
Intersection guide program to function as .

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