JP2006004029A - Device for detecting curve section - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a curve section detecting device for reliably determining existence of a curve section. <P>SOLUTION: A plurality of continuous nodes N1-N4 in the anterior road of an observation point are acquired. A curve start is determined when determination is continued twice, that the lengths a, b, c of links are smaller than the threshold of a start link distance and angles generated by the crossing of the links is larger than the threshold of a start link intersection angle, through the use of the acquired nodes, the lengths a, b, c, of the links La, Lb, Lc for connecting the nodes, and the angles α, β generated by the crossing of the links. Not only the intersection angles of the crossing links but the link lengths are added, so as to reliably detect a curve shape which is closesr to an actual travelling feeling. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention uses road map data, in particular road map data including link node data for map drawing, to detect the start and end points of a curve section, and further to obtain a curvature radius of the curve section The present invention relates to a detection device.

Acquiring curve information on the road ahead to be traveled by the in-vehicle device is useful for predicting danger and improving the safety of travel. For this reason, attempts have been made to detect the curve of the road ahead. In addition, it is necessary to grasp the curve section of the road even in the case of running simulation.
As one of the technologies for detecting the curve section, in the road map data, when several nodes in front are acquired and the sum of the refraction angles (intersection angles) of the links connecting the points exceeds a certain value, A determination method has been proposed (Patent Document 1).
Japanese Patent Laid-Open No. 11-232599 Japanese Patent Laid-Open No. 11-232600

However, in the technique described in Patent Document 1, only the crossing angle between the links is checked. Therefore, when a link with a short distance that intersects at a small angle continues, it can be determined as a curve section in an actual sense. However, it may be determined that it is not a curve section.
In view of the above, an object of the present invention is to provide a curve section detection device that can more reliably determine the existence of a curve section.

  The curve section detection device of the present invention includes road map data including node coordinate data, node acquisition means for acquiring a plurality of continuous nodes on a road ahead of an observation point, and nodes acquired by the node acquisition means And a curve start / end determination means for determining the start and end of the curve using the length of the link connecting the nodes and the angle at which the links cross each other.

According to this configuration, by considering not only the angle (intersection angle) at which the links intersect but also the link length, it is possible to reliably detect a curve shape that is close to the actual driving feeling.
For example, when it is determined that the length of the link connecting the nodes is smaller than the start link distance and the angle at which the links cross each other is larger than the start link intersection angle, the curve start position is determined. This “start link distance” is a link length threshold value for determining the start of the curve. A link exceeding the start link distance is regarded as a link forming a straight road and is excluded from the determination target of the curve section. Then, by performing the determination a plurality of times in succession, it is possible to more reliably determine the start of the curve close to the actual driving feeling.

Of the links that satisfy the determination condition, it is preferable that the node constituting the forefront link is determined as the curve start position because it matches the actual feeling.
Further, when determining the end of the curve, it is determined that the curve is ended when it is determined that the angle at which the links connecting the nodes intersect with each other is smaller than the end link intersection angle. By performing the determination a plurality of times in succession, it is possible to make a determination that is more reliable and close to the actual driving feeling.

    In addition, when the determination that the length of the link connecting the nodes is larger than the end link distance and the angle at which the links intersect is smaller than the end link intersection angle is repeated a plurality of times, it is determined as the curve end position. May be. The “end link distance” is a threshold of the link length for determining the end of the curve. A link shorter than the end link distance has a curve even if the angle between the links is smaller than the end link intersection angle. It is not regarded as the end and is excluded from the judgment target of the end of the curve section. Thereby, the determination target of the end of the curve section is a link longer than the “end link distance”. Then, by making the determination a plurality of times in succession, it is possible to make a determination that is more reliable and close to the actual driving feeling.

Of the links that satisfy the determination condition, it is preferable that the node constituting the farthest link is set as the curve end position because it matches the actual feeling.
The curve section detection device of the present invention compares the length of the link connecting the node and the node acquired by the node acquisition means with a threshold, and when the link length is shorter than the threshold, deletes the previous node, The curve start / end determination means may determine the curve start position or end position by replacing the node deleted by the node deletion means with the next node. Thereby, when the link length is short, the nodes constituting the link are thinned out, so that when a link such as a minute crank exists, it can be avoided that the link is erroneously determined.

The node acquisition means preferably acquires a node that is within a search distance threshold from the observation point. This is because if the determination of the curve section from the observation point to the long distance destination is determined, the data processing amount increases. In addition, when it is desired to determine a curve section from an observation point to a long distance in this way, it is sufficient to advance the observation point and make a new determination.
Furthermore, the curve section detection device of the present invention may further include a curvature radius calculation unit that uses a value obtained by dividing the sum of the link lengths from the curve start point to the curve end point by the sum of the crossing angles to make the curvature radius of the curve. Good.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a block diagram of a curve section detection apparatus according to the present invention. First, it should be noted that the curve section detection device may be an in-vehicle device or a device realized by a personal computer installed in an office, home, or the like. Hereinafter, a personal computer is assumed.

  The curve section detection device includes a host vehicle position input device 11, a road search processing unit 12, road map data 13, a curve determination processing unit 14, a curve information display unit 15, a determination value setting table 16, and the like. The vehicle position input device 11 is realized by a mouse, a keyboard, or the like. The road map data 13 is stored in a large-capacity storage medium such as a hard disk. The curve information display unit 15 is realized by a display device. The judgment value setting table 16 is written in one setting file. The functions of the road search processing unit 12 and the curve determination processing unit 14 are realized by a personal computer executing a program recorded on a predetermined medium such as a CD-ROM or a hard disk.

  Based on the road map data 13, the road search processing unit 12 searches for a road to be traveled (or traveled) from the destination to the destination. This search method may employ a Dijkstra route search process that searches for a route with the shortest distance or travel time, and the vehicle is currently traveling (or a travel simulation is performed without considering whether it is the shortest). A route search process for searching for the same type of road as possible may be adopted. As a result of the search, the road search processing unit 12 transmits road information constituting the route to the curve determination processing unit 14.

  As shown in Table 1, the road information is classified into link units, road toll / free classification, road type (highway expressway, urban expressway, national highway, prefectural road, municipal road, etc.), road width (road width (Meter display), link type (main line, connecting road, service area side line, inside intersection, etc.), prefecture code, municipal code, route abbreviation, route number, common name, road regulation information (no restrictions, no traffic, one way, etc.) , Node configuration points, node coordinates, and the like.

  Here, “link” refers to a vector representing a road section. Normally, one link is from the intersection to the intersection, but a road section may be divided by interpolation points, and a link may be defined for each interpolation point. The link is automatically set when the road map data 13 is created, but a straight road may be subdivided into a plurality of short zigzag links due to errors in the digital map as a base.

“Node” means the intersection or the interpolation point. A node is defined by a node number, coordinates, and the like. The coordinates may be absolute coordinates such as latitude and longitude, or relative coordinates with respect to the segmented map.
The curve determination processing unit 14 determines a curve start and a curve end based on the road information acquired from the road search processing unit 12.

  Here, terms are defined. “Link length” is a straight line distance between nodes serving as link end points. “Start link intersection angle” is a threshold value for determining the start of the curve for the angle at which the links intersect. “End link intersection angle” is a threshold value for determining the end of the curve for the angle at which the links intersect. The “link distance” is a link length threshold for determining the start of the curve, and the “end link distance” is a link length threshold for determining the end of the curve. Further, the “search distance” refers to a distance where the curve determination process is performed forward from the vehicle position input by the vehicle position input device 11. The curve determination processing unit 14 determines a curve start and a curve end only on a road within the search distance. The “thinning distance” is a threshold for excluding a short link from the target of the curve determination process in consideration of this because the road may be subdivided into short zigzag links.

  The “start link intersection angle”, “end link intersection angle”, “start link distance”, “end link distance”, “search distance”, and “thinning distance” are written in the determination value setting table 16. A description example is shown in Table 2.

In the description example of Table 2, various setting values are set for each toll road / general road.
FIG. 2 is an overall flowchart showing an outline of processing for searching for a curve start position and a curve end position in a curve section.
First, at the first search, “total link length” is initialized to 0 m (step S1). The “total link length” is a variable for following the links ahead and adding up the total of the link lengths that have been followed.

Next, a curve start position search process is performed (step S2). Although details of this processing will be described later, the link length of the link searched during the processing is added to the “total link length”.
When the curve start position can be searched (YES in step S3), a curve end position search process is performed (step S4). Although details of this processing will be described later, the link length of the searched link during the processing is added to the “total link length”.

If the curve end position can be searched (YES in step S5), the process returns to step S2 to search for the next curve start position and curve end position. In this way, the curve start position and the curve end position are sequentially searched. When the total link length exceeds the set “search distance”, the search is ended (NO in step S3, NO in step S5). .
FIG. 3 is a detailed flowchart showing the curve start position search process.

First, the total link length and the search distance are compared (step T1), and if the total link length is longer than the search distance, the curve start position search process and the curve end position search process that follows within the forward search distance are terminated. .
If the total link length is within the search distance, the process proceeds to step T2 to acquire the coordinates of the first node N1. Here, the 1st node N1 means the nearest node ahead of the own vehicle position.

Further, the coordinates of the second node N2 next to the first node N1 are acquired (step T3). The link from the first node N1 to the second node N2 is La, and the link length is a.
Next, the link length a is compared with the “thinning distance” (step T4). If the link length a is shorter than the thinning distance, the node coordinates and link length information of the second node N2 are deleted, and step T3 is performed. Returning, the next node is searched, and it is set as the second node N2. That is, a link shorter than the “thinning distance” is removed from the curve determination target. Details of the “thinning-out process” will be described later in detail with reference to FIGS.

Next, the coordinates of the third node N3 existing next to the second node N2 are acquired (step T5). The link from the second node N2 to the third node N3 is Lb, and the link length is b. An angle between the link La and the link Lb is α.
The curve determination processing unit 14 compares the link length b with the thinning distance (step T6), and if the link length b is shorter than the thinning distance, deletes the node coordinates and link length information of the third node N3. Returning to step T5, the next node is searched for, and is designated as the third node N3. That is, a link shorter than the “thinning distance” is removed from the curve determination target. Details of the “thinning-out process” will be described later in detail with reference to FIGS.

  Next, the curve determination processing unit 14 acquires the coordinates of the fourth node N4 that exists next to the third node N3 (step T7). The link from the third node N3 to the fourth node N4 is Lc, and the link length is c. An angle between the link Lb and the link Lc is β. Further, the link length c is compared with the thinning distance (step T8). If the link length c is shorter than the thinning distance, the node coordinates and link length information of the fourth node N4 are deleted, and the process returns to step T7. The next node is searched for and is designated as the fourth node N4.

  FIG. 4 is a link diagram illustrating the relationship between the second node N2 to the fourth node N4 that have not been “thinned”, the links La, Lb, and Lc, and the angles α and β. The curve determination processing unit 14 determines whether the links Lb and Lc are curve sections based on the relationship between the link lengths a, b and c of these links La, Lb and Lc and the angles α and β. It is determined whether or not the second node N2 is at the curve start position (step T9).

The curve determination process will be specifically described with reference to FIG. The curve determination processing unit 14 sets the second node N2 as the curve start position when the following determination (A) is satisfied and the determination (B) is satisfied.
(A) α> starting link crossing angle, b <starting link distance (B) β> starting link crossing angle, c <starting link distance When either or both of (A) and (B) are not satisfied, It is determined that the curve is not started, and the link length a is added to the “total link length” (step T11). Then, the node coordinate is advanced by one (step T12), and the process returns to step T1.

In step T1, as long as the total link length is shorter than the search distance, the processing after step T2 is repeated. If the total link length exceeds the search distance (No in step T1), the start of the curve does not exist within the search distance, and the process returns to step S3 in FIG. 2. If it is determined that the start of the curve is present, the second node The start position of the curve is registered (step T10), and the process proceeds to step S4 in FIG.

Next, the “thinning process” will be described. 5 and 6 are link diagrams for explaining the “thinning-out process”.
A road may be composed of a plurality of links connected to a zigzag due to a position detection error on a map. In this case, when these links are used, the curve start / end determination may not work well. Therefore, for these fine links, if the link length is shorter than the “thinning-out process”, the links are skipped.

FIG. 5 is a link diagram illustrating a series of nodes N1 to N5 before being “thinned out” and links La to Le connecting these nodes. The lengths of the links La to Le are a to e, respectively. The thinning process is performed as follows. The thinning distance is represented by D.
As a result of calculating the distance a of the link La connecting the node N1 and the node N2, since a is not in the range of the thinning distance D, the node N2 is used as the second node coordinates as it is. Since the distance b of the link Lb connecting the node N2 and the node N3 is within the range of the thinning distance D, the node N3 is thinned out.

Next, the node N2 and the node N4 are directly connected to form a link Lc. As a result of calculating the distance c of the link Lc, since c is also within the range of the thinning distance D, the node N4 is thinned. Next, the node N2 and the node N5 are directly connected to form the link Ld. As a result of calculating the distance d of the link Ld, since d is also outside the range of the thinning distance D, the node N5 is set as the next third node coordinate. Thereby, the node N3 and the node N4 are thinned out, and the node N2 and the node N5 are connected by a new link.

FIG. 6 is a diagram illustrating a state in which the node N2 and the node N5 are connected by a new link. In the figure, the node N5 is anew represented by the node N3, and the new link is represented by Lb.
FIG. 7 is a detailed flowchart showing the curve end position search process.
First, the total link length used in the curve start determination process is compared with the search distance (step U1), and if the total link length becomes longer than the search distance, the end of the curve does not exist within the forward search distance. Finish the process.

If the total link length is within the search distance, the process proceeds to step U2 to acquire the coordinates of the first node N1. Here, the first node N1 is a node closest to the node registered as the curve start point in the curve start determination process.
Further, the coordinates of the second node N2 next to the first node N1 are acquired (step U3). The link from the first node N1 to the second node N2 is Ld, and the link length is d.

  Next, the link length d is compared with the “thinning distance” (step U4). If the link length d is shorter than the thinning distance, the node coordinates and link length information of the second node N2 are deleted, and step U3 is performed. Returning, the next node is searched, and it is set as the second node N2. That is, the link shorter than the “thinning distance” is removed from the curve determination target. The details of this “thinning-out process” are as described above.

Next, the coordinates of the third node N3 existing next to the second node N2 are acquired (step U5). Let the link from the second node N2 to the third node N3 be Le and its link length be e. An angle between the link Ld and the link Le is θ.
The curve determination processing unit 14 compares the link length d with the thinning distance (step U6), and if the link length d is shorter than the thinning distance, deletes the node coordinates and link length information of the third node N3, Returning to step U5, the next node is searched for, and is designated as the third node N3. That is, a link shorter than the “thinning distance” is removed from the curve determination target.

  Next, the curve determination processing unit 14 acquires the coordinates of the fourth node N4 that exists next to the third node N3 (step U7). The link from the third node N3 to the fourth node N4 is Lf, and the link length is f. The angle between the link Le and the link Lf is γ. Further, the link length f is compared with the thinning distance (step U8). If the link length f is shorter than the thinning distance, the node coordinates and the link length information of the fourth node N4 are deleted, and the process returns to step U7. The next node is searched for and is designated as the fourth node N4.

  FIG. 8 is a link diagram illustrating the relationship between the second node N1 to the third node N3 that has not been “thinned”, the links Ld, Le, and Lf, and the angles θ and γ between the links. The curve determination processing unit 14 determines whether the links Ld and Le are curve sections based on the relationship between the link lengths d, e, and f of the links Ld, Le, and Lf and the angles θ and γ. It is determined whether or not the second node N2 is at the curve end position (step U9).

This curve determination process will be described with reference to FIG. The curve determination processing unit 14 sets the second node N2 as the curve end position when the next determination (C) is satisfied and the determination (D) is satisfied.
(C) θ <End link crossing angle (D) γ <End link crossing angle If either or both of (C) and (D) do not hold, it is assumed that the curve end position is not reached, and the link length e is set. Add to the total link length (step U11). Then, the node coordinate is advanced by one (step U12), and the process returns to step U1. In step U1, if the total link length is shorter than the search distance, the processing from step U2 is repeated. If the total link length exceeds the search distance (No in step U1), the search for the end position of the curve is terminated within the search distance, and the process returns to step S5 in FIG.

When it is determined that the curve is ended, the curve end position is registered as the coordinates of the second node (step U10), and a normal end mark is given.
In the determination processes (C) and (D), the determination can be made in consideration of the link lengths e and f. That is, it is possible to determine that the end of the curve is satisfied when the following (C ′) and (D ′) are simultaneously satisfied.

(C ′) θ <End link crossing angle e> End link distance (D ′) γ <End link crossing angle f> End link distance The advantage of determining in consideration of the link lengths e and f is the angle between the links. Even if θ and γ are smaller than the end link crossing angle, if the link length is short, it may not always be considered as the end of the curve in the actual driving sense, so this case is avoided. .

Although the embodiments of the present invention have been described above, the embodiments of the present invention are not limited to the above-described embodiments. For example, when the curve section is found as a result of the above curve start position search process and curve end position search process, a process for obtaining the curvature radius of the curve may be added.
In order to obtain the curvature radius R of this curve, the sum L of the link lengths from the curve start point to the curve end point may be divided by the sum Ω of intersection angles as shown in the following equation.

R = L / Ω
Further, in the above embodiment of the present invention, the curve section detection device is incorporated in the personal computer, but can also be realized by an in-vehicle device having a vehicle position detection function. The presence of a curve section ahead in the traveling direction can be predicted, and the curvature radius can be calculated if necessary, which can be used for driving safety.

It is a block block diagram of the curve area detection apparatus of this invention. It is a whole flowchart which shows the outline | summary of the process for searching the curve start position and curve end position in a curve area. It is a detailed flowchart which shows a curve start position search process. It is the link figure which illustrated the relationship between 2nd node N2-4th node N4, link La, Lb, Lc, and angle (alpha) and (beta). FIG. 10 is a link diagram (before thinning) for explaining “thinning processing”. FIG. 10 is a link diagram (before thinning) for explaining “thinning processing”. It is a detailed flowchart which shows a curve end position search process. FIG. 6 is a link diagram illustrating the relationship between the second node N1 to the third node N3, links Ld, Le, Lf, and angles θ, γ formed by the links.

Explanation of symbols

11 Car Position Input Device 12 Road Search Processing Unit 13 Road Map Data 14 Curve Determination Processing Unit 15 Curve Information Display Unit 16 Determination Value Setting Table

Claims (9)

Road map data including node coordinate data,
Node acquisition means for acquiring a node on the road ahead of the observation point;
A curve comprising: a curve start / end determination means for determining a curve start and a curve end using a length of a link connecting the nodes acquired by the node acquisition means and an angle at which the links cross each other. Section detection device.   The curve start / end determination means determines whether a curve is obtained when it is determined that the length of the link connecting the nodes is smaller than the start link distance and the angle at which the links intersect is greater than the start link intersection angle. The curve section detection device according to claim 1, wherein the curve section detection device is determined to be a start.   3. The curve section detection device according to claim 2, wherein, when the curve start / end determination means determines that the curve starts, the node constituting the forefront link among the links satisfying the determination condition is set as the curve start position. .   The curve section detection according to claim 1, wherein the curve start / end determination means determines that the curve is ended when it is determined that the angle at which the links connecting the nodes intersect each other is smaller than the end link intersection angle a plurality of times. apparatus.   The curve start / end determination means determines whether a curve is obtained when it is determined that the length of the link connecting the nodes is greater than the end link distance and the angle at which the links meet is smaller than the end link intersection angle a plurality of times. The curve section detection apparatus according to claim 1, wherein the curve section detection apparatus determines that the end is completed.   6. The curve start / end determination unit according to claim 4, wherein, when the curve start / end determination unit determines that the curve ends, a node constituting a farthest link among the links satisfying the determination condition is set as a curve end position. Curve section detection device.   Comparing the length of the link connecting the node acquired by the node acquisition means with a threshold value, and further comprising a node deletion means for deleting the previous node when the link length is shorter than the threshold value, The curve section detection device according to any one of claims 1 to 6, wherein the end determination means determines the curve start position or end position by replacing the node deleted by the node deletion means with the next node. .   The curve section detection device according to any one of claims 1 to 7, wherein the node acquisition unit acquires a node within a search distance threshold from an observation point.   The curvature radius calculation means which makes the curvature radius of a curve the value which divided the sum total of the link length from the curve start point to the curve end point by the sum total of the crossing angle is further provided. The curve section detection apparatus in any one of.

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