JP2004226341A - Map matching method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a map matching method by which the occurrence of a map matching mistake can be prevented certainly even when a frontage road runs in parallel with the running road of a vehicle. <P>SOLUTION: This map matching method is used for navigation system for correcting the location of the vehicle on the running road by performing map matching. Virtual links A1-A3 of the number corresponding to the width of a road or the number of lanes of the road are supposed and the optimum link is found by performing map matching by using the virtual links A1-A3 as links to be subjected to map matching. When the optimum link is one of the virtual links A1-A3, the location of the vehicle is corrected on the road corresponding to the virtual link. It is also possible to use only the outside virtual link as the link to be subjected to map matching when a plurality of virtual lines exists. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a map matching method, and more particularly to a map matching method of a navigation device that corrects a vehicle position on a traveling road by a map matching process assuming a virtual link.
[0002]
[Prior art]
When the detection errors of the position detector are accumulated, the vehicle position is not displayed on the traveling road. Therefore, the navigation device estimates the vehicle position by map matching processing, corrects the estimated vehicle position with the road data, and corrects the estimated vehicle position to the actual vehicle position on the road. 8 and 9 are explanatory diagrams of map matching by the projection method. Assume that the current vehicle position is at point P _i-1 (X _i-1 , Y _i-1 ) and the vehicle direction is θ _i-1 (point P _{i-1 in} FIG. 8 matches road RDa). Not shown). If the relative azimuth when traveling a fixed distance La (for example, 10 m) from the point P _i-1 is Δθi, the estimated vehicle position P _i ′ (X _i ′, Y _i ′) by the self-contained navigation and the P _i ′ The estimated vehicle direction θ _i is given by the following equation: θ _i = θ _i-1 + Δθ _i
X _i ′ = X _i−1 + La · cos θ _i
Y _i ′ = Y _i−1 + La · sin θ _i
Required by
[0003]
At this time, (a) a link (element constituting a road) that is included in a 200 m square centered on the estimated vehicle position P _i ′ and that can descend the vertical line, and is estimated at the estimated vehicle position P _i ′ The angle between the vehicle azimuth θ _i and the link is within a certain value (for example, within 450), and the length of the perpendicular drawn from the estimated vehicle position P _i ′ to the link is within a certain distance (for example, 100 m). Search for Here, a link LKa1 of the direction θa1 on the road RDa (a straight line connecting the nodes Na0 and Na1) and a link LKb1 of the direction θb1 on the road RDb (a straight line connecting the nodes Nb0 and Nb1). Next, (b) the lengths of the perpendiculars RLia and RLib dropped from the estimated vehicle position P _i ′ to the links LKa1 and LKb1 are obtained. (C) Then, the following equation Z = dL · 20 + dθ · 20 (dθ ≦ 350)
Z = dL · 20 + dθ · 40 (dθ> 350)
Is used to calculate the coefficient Z. Note that dL is the length of the perpendicular (the distance from the estimated vehicle position to the link) dropped from the estimated vehicle position P _i 'to the link, and dθ is the angle formed by the estimated vehicle direction θ _i and the link. The weight coefficient is increased.
[0004]
(D) Once the coefficient value Z is obtained, the following conditions (1), (2), and (3)
(1) Distance dL ≦ 75m (maximum attraction distance 75m)
(2) Angle difference dθ ≦ 300 (maximum attractive angle 300)
(3) Coefficient value Z ≦ 1500
Are determined, and the link having the smallest coefficient value is determined as a matching candidate (optimum road). Here, the link is LKa1. (E) Then, the traveling locus SHi connecting the point P _i-1 and the point P _i ′ is translated in the direction of the perpendicular line RLia until the point P _i-1 is on the link LKa1 (or an extension of the link LKa1). , determine the point _{P i-1} and _{P i} 'moving point _{PT i-1} and PT _i' and the (f) Finally, PT _i 'around the point _{PT i-1} is the upper link LKa1 (or link LKa1 (On the extension line), a rotation point is obtained to obtain a moving point, which is set as an actual vehicle position P _i (X _i , Y _i ). Note that the vehicle direction at the actual vehicle position P _i remains at θ _i . Further, as shown in FIG. 9, when the point P _i-1 which is the previous vehicle position is on the road RDa, the moving point PT _i-1 coincides with the point P _i-1 .
[0005]
As described above, the map matching process is performed in the projection method. By the way, even if the map matching process is performed, a map matching error is likely to occur where the main road and the side road are parallel. Therefore, even if the actual road ARD has two lanes as shown in FIG. 10A, the road shape link DB is not separated into upper and lower lines in the map database as shown in FIG. As shown in (C), assuming an up virtual link PR1 and a down virtual link PR2 at fixed distances a and b from the road shape link DB, map matching processing is performed using these virtual links. . Note that a and b are equal, and for example, are set to 3 to 4 m as one lane each way.
[0006]
However, if the main road is the highway HWY and the road width is wide as shown in FIG. 11A, the virtual links PR1 and PR2 are considerably displaced from the road ends 1 and 2 as shown in FIG. , (C), the vehicle C1 is drawn to the side road SRD by the map matching process. FIG. 12 is an explanatory diagram showing the situation attracted to the side road SRD in more detail. The vehicle C2 is attracted to the virtual link PR1 and correct map matching is performed.
Japanese Patent Application Laid-Open No. 8-334351 discloses a map matching method in which the attraction force increases as the width of the road increases.
[Patent Document 1] JP-A-8-334351
[Problems to be solved by the invention]
As described above, according to the map matching method of the related art shown in FIG. 10, when the width of the road is widened, the road is attracted to the side road and a map matching error occurs. Although the prior art of Patent Document 1 is one method for preventing the occurrence of a map matching error when the road width is wide, there is a problem that the map matching error cannot be reliably prevented.
From the above, it is an object of the present invention to ensure that map matching errors can be prevented even when side roads are running in parallel.
[0008]
[Means for Solving the Problems]
According to the present invention, in a map matching method of a navigation device for correcting a vehicle position on a traveling road by a map matching process, the number of virtual links according to the road width or the number of lanes of the road is assumed, Is set as a target link of the map matching process, a map matching process is performed to obtain an optimum link, and if the optimum link is a virtual link, the vehicle position is corrected on a road corresponding to the virtual link. When there are a plurality of virtual links, if the outer virtual link is set as the target link of the map matching process, the number of target links of the map matching process can be reduced.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
(A) Schematic of the present invention FIG. 1 is a schematic explanatory view of the present invention. With respect to the road shape link A of the highway HWY, virtual links A1 to A3 corresponding to the road width or the number of lanes of the road are assumed, and these virtual links A1 to A3 and the road shape link B of the side road SRD are targeted. An optimal link is obtained by performing a map matching process as a link. For example, the optimal link of the vehicle C1 is determined as the virtual link A3, and the optimal link of the vehicle C2 is determined as the virtual link A1 by the map matching process. If the obtained optimum link is a virtual link, the vehicle position is corrected on the road link shape A corresponding to the virtual links A1 and A3 on the display map.
When there are a plurality of virtual links, as shown in FIG. 2, if the outer virtual link A3 is set as a target link of the map matching processing, the number of target links of the map matching processing can be reduced, and high-speed processing can be performed. Become.
[0010]
(B) In-Vehicle Navigation Device FIG. 3 is an overall configuration diagram of the in-vehicle navigation device of the present invention. The map information storage unit 11 is a DVD or the like that stores map data. The display device 12 draws a map image, a vehicle position mark, a guidance route, and the like according to the current position of the vehicle. Although not shown, the vehicle position detecting unit 13 receives an azimuth sensor such as a vibrating gyroscope for detecting the traveling azimuth of the vehicle, a distance sensor for generating one pulse every predetermined traveling distance, and a radio wave from a GPS satellite to The current position (latitude, longitude) of the vehicle is estimated using a GPS receiver that measures the absolute position of the vehicle. The remote controller or the operation unit 14 is used to select a menu from various menu lists displayed on the screen and to scroll a map. The navigation control unit 15 includes (1) map image generation processing around a vehicle using map data, (2) map matching processing, (3) route search processing, (4) off-route route re-search processing, (5) ) It performs processing for generating vehicle position marks and guidance route images.
[0011]
In the navigation control unit 15, the remote control control unit 15a receives a signal corresponding to the operation of the remote control and instructs each unit. The map matching control unit 15b performs a map matching process by the projection method for each predetermined traveling distance (for example, 10 m) using the map information, the estimated vehicle position, and the vehicle direction, and corrects the own vehicle position on the traveling road. The map image drawing unit 15b reads map data in a wider area than the screen display area around the current location from the map information storage unit 11 based on the vehicle position data, and generates a dot image map image based on the map data. The guide route drawing unit 15d generates a guide route image based on the guide route data from the departure point to the destination obtained by the guide route search process. The video RAM 15e stores a map image and a guidance route image. The map image drawing unit 15c rewrites the video RAM 15e at any time as the vehicle travels so that the display range of the display screen does not exceed the image range of the video RAM 15e, and the guidance route drawing unit 15d also responds to the vehicle travel. Thus, a guidance route image is generated and stored in the video RAM 15e.
The image cutout control unit 15f cuts out a map image for one screen from the video RAM 15e so that the current position of the vehicle is located at the center of the display screen or the center of the lower part. The cutout position is specified by the map image drawing unit 15c. The vehicle position mark generation unit 15g displays the vehicle position mark at the center of the display screen or at the center of the lower part.
[0012]
The guidance route search unit 15h searches for a guidance route from the departure place to the destination based on the map information when the departure place (for example, the current position of the vehicle) and the destination are input. The guidance route search unit 15h constantly monitors whether the vehicle position is on the guidance route, and when the vehicle position deviates from the guidance route (off route), re-searches the route from the current position to the destination. . The guidance route storage unit 15i stores a guidance route from a departure place to a destination. The combining unit 15j combines the map image, the guidance route image, and the vehicle position mark image read from the video RAM 15e and the vehicle position mark generating unit 15g, outputs the combined image to the display device 12, and displays the image.
[0013]
(C) Link record The road layer information of the map information includes a link record constituting each road. FIG. 4 is an explanatory diagram of the structure of the link record. The 1-byte data of item No. 7 of the link record includes lane width information, and the 1-byte data of item No. 10 includes lane number information. FIG. 5 is an explanatory diagram of lane width information of item No. 7, in which bits 4 to 6 indicate the road width, and bits 7 indicate whether the road width is the total road width including the upper and lower lines, or whether the road width is one way. Is shown. If it is a one-way road, 0h and 1h can be regarded as having one lane in one way, 2h can be regarded as having two to three lanes in one way, and 3h can be regarded as having four or more lanes in one way. FIG. 6 is an explanatory diagram of lane number information of item No. 10, where 0h is one-way lane number of four or more lanes, 1h is one-way lane number two-thirds lane, and 2h is one-way lane number one lane. . It should be noted that future map data will include accurate road widths and lane numbers. For example, a map database for ADAS is being provided in the EU / US, and the number of lanes and the road width are to be accurately stored in this map database.
[0014]
(D) Setting Method of Virtual Road Shape Link The map matching control unit 15b determines the number of virtual road shape links based on the road width information or the number of lanes of the road link at the time of the map matching processing, and sets the road shape link A (FIG. 1), a virtual road shape link Ai is set at an appropriate position, and map matching processing is performed using the virtual road shape link Ai as a map matching target link.
A specific method for determining the number of virtual road shape links using the lane number information in FIG. 6 is as follows.
(1) If the lane number information is 0h, there are four or more lanes, so a virtual link is placed on the first to fourth lanes (the distance is calculated by the average road width × the number of lanes). Although there are not many roads with five or more lanes, even in this case, if there is a link in the fourth lane or if there is only a link in the conventional first lane, a map matching error is much less likely to occur.
(2) When the road information is 1 h, it is 2-3 lanes, so the following two can be handled.
Create the first and second lanes as virtual links (calculate the distance by average road width x number of lanes).
-Create the first to third lanes as virtual links, and delete the third lane if another road (side road, etc.) overlaps at the same height (ground or elevated) in the range of the third lane. . The distinction between surface and elevated is stored in the map database.
(3) If the road width information is 2h, one virtual link is created.
(4) If the road width information is 3h, nothing is performed because it is currently unused.
[0015]
In the above description, in the case of a multi-lane road as shown in FIG. 1, virtual road shape links A1 to A3 are provided in all lanes, and these are used as map matching target links. However, as shown in FIG. Only the road shape link A3 may be provided and used as a map matching target link.
[0016]
(E) Map Matching Process FIG. 7 is a flowchart of the map matching process of the present invention.
The map matching control unit 15b performs a map matching process for each predetermined traveling distance of the vehicle. That is, a virtual road shape link (virtual link) is set based on the road width or the number of lanes by the method shown in (D) (step 101). Next, map matching processing is executed using the virtual link as a processing target link (step 102), and an optimum link (map matching candidate link) is determined (step 103). Next, it is checked whether the obtained optimum link is a virtual link (step 104). If the link is a virtual link, the vehicle position is corrected on the road shape link corresponding to the virtual link on the displayed map (step 105). ). On the other hand, if it is not a virtual link, the vehicle position is corrected on the link on the side road (step 106).
[0017]
【The invention's effect】
As described above, according to the present invention, the number of virtual links according to the road width or the number of lanes on the road is assumed, and the virtual link is subjected to map matching processing as a target link of the map matching processing to obtain an optimum link. In the case of a virtual link, the vehicle position is corrected on the road corresponding to the virtual link, so that even if the side road runs in parallel, a map matching error can be reliably prevented. When there are a plurality of virtual links, the number of target links can be reduced by using the outer virtual link as a target link of the map matching processing, and high-speed map matching processing can be performed.
[Brief description of the drawings]
FIG. 1 is a schematic explanatory diagram of the present invention.
FIG. 2 is a schematic explanatory diagram of the present invention when a plurality of virtual links exist.
FIG. 3 is an overall configuration diagram of a vehicle-mounted navigation device according to the present invention.
FIG. 4 is a diagram illustrating the configuration of a link record.
FIG. 5 is an explanatory diagram of lane width information.
FIG. 6 is an explanatory diagram of lane number information.
FIG. 7 is a flowchart of a map matching process according to the present invention.
FIG. 8 is an explanatory diagram of a first map matching by a projection method.
FIG. 9 is an explanatory diagram of a second map matching by a projection method.
FIG. 10 is an explanatory view of a conventional technique.
FIG. 11 is an explanatory diagram of a problem in the related art.
FIG. 12 is another diagram for explaining a problem of the related art.
[Explanation of symbols]
A Road shape links A1 to A3 Virtual road shape link B Road shape links C1 and C2 on the side road

Claims (2)

In a map matching method of a navigation device for correcting a vehicle position on a traveling road by a map matching process,
Assuming the number of virtual links according to the road width or the number of lanes on the road,
Using the virtual link as a target link for the map matching process, the map linking process is performed to obtain an optimal link,
If the optimal link is a virtual link, correct the vehicle position on a road corresponding to the virtual link;
A map matching method characterized in that: When there are a plurality of virtual links, the outer virtual link is set as a target link of the map matching process.
2. The map matching method according to claim 1, wherein:

Images