JPH04340992A - Vehicle position detection device for on-vehicle navigator - Google Patents

Abstract

PURPOSE:To improve the correction accuracy of a vehicle position by map matching by correcting a vehicle azimuth. CONSTITUTION:Every time a distance sensor 4 detects a constant-distance travel, a vehicle azimuth calculation part 5d integrates an azimuth change detected by a relative azimuth sensor 3 to the vehicle azimuth in a vehicle azimuth memory 5c to find a new vehicle azimuth and rewrite the memory 5c, and a primary vehicle position calculation part 5d finds position variation by using the found vehicle azimuth and adds it to a last determined vehicle position to calculate a primary vehicle position; every time the primary vehicle position is found, a vehicle position correction part 5f searches for a matching candidate road by referring to map data and corrects the primary vehicle position on the road as a determined vehicle position. When the vehicle position is corrected, a decision part 5g decides whether or not the corrected link of the vehicle position is at longer than a constant distance by referring to the map data and when so, a vehicle azimuth correction part 5j finds the azimuth of the corrected ling and rewrites the memory 5c with the azimuth.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a vehicle position detection device for an on-board navigator, and more particularly, the present invention relates to a vehicle position detection device for an on-board navigator, and in particular, the vehicle position of an on-board navigator is adapted to correct the vehicle position information obtained by dead reckoning on the road by map matching processing using a projection method. This invention relates to a detection device.

0002

2. Description of the Related Art There is an in-vehicle navigator that provides driving guidance for a vehicle and allows the driver to easily reach a desired destination. In this in-vehicle navigator, the position of the vehicle is detected, map data around the vehicle position is read from the CD-ROM, a map image is drawn in the V-RAM, and a vehicle position mark is superimposed on the map image. - Converting the image in the RAM to a video signal and outputting it to the CRT display for display on the screen. Then, as the current position changes due to the movement of the vehicle, the vehicle position mark on the screen is moved, or the vehicle position mark is fixed at the center of the screen and the map is scrolled, so that the map around the vehicle position is always displayed. Information can be seen at a glance.

[0003] In the map data stored on the CD-ROM, roads are represented by a coordinate set of vertices (nodes) expressed in latitude and longitude, and these drawings are performed by sequentially connecting each node with a straight line. . Note that a portion that connects two or more nodes is called a road link.

By the way, in a vehicle-mounted navigator for dead reckoning, the vehicle position is detected by integrating the outputs of a distance sensor and a relative azimuth sensor, for example. FIG. 12 is an explanatory diagram showing a vehicle position detection method using dead reckoning navigation. The distance sensor outputs a pulse every time the vehicle travels a certain unit distance L0, and if the reference direction (θ = 0) is the positive direction of the X-axis and the counterclockwise rotation from the reference direction is the + direction, then the previous The confirmed vehicle position is point P0 (X0, Y0), and point P0
When the vehicle direction (absolute direction in the direction of vehicle travel) at 1 is θ0, and the output of the relative direction sensor (direction change) at point P1, which has traveled a unit distance L0, is Δθ1, then the vehicle at the current point P1 is The direction θ1 is θ1 = θ0 + Δθ1

...(1). The change in vehicle position is calculated using θ1, ΔX=L0 ・
Since it is expressed as cos θ1 ΔY=L0 ・sin θ1, the position coordinates (X1
, Y1) is X1 = X0 + ΔX
=X0 +L0 ・cos θ1

...(2) Y1 = Y0 +Δ
Y = Y0 + L0 ・s
in θ1
...(3) can be calculated by vector composition. Therefore, if the vehicle direction and position coordinates at the starting point are given, then the vehicle will travel a unit distance L0.
By repeating calculations (1) to (3) each time the vehicle travels, the vehicle direction and position can be detected in real time.

[0005]However, for distance sensors and relative direction sensors,
Even if expensive sensors such as OFG and gas rate are used, there are always errors, so as the vehicle position detected by dead reckoning navigation progresses, the errors accumulate and the vehicle deviates from the road. For this reason, in-vehicle navigators match the vehicle position detected by dead reckoning with the road data in the map data and correct it on the road (map matching process).
. 13 to 15 are explanatory diagrams of map matching using the projection method. The last determined vehicle position is point Pi-1 (
Xi-1 , Yi-1 ), and the vehicle orientation is θi-1
(In Fig. 13, point Pi-1 is road RD
a). If the relative bearing when the pulse is output from the distance sensor after traveling a certain distance L0 from point Pi-1 is Δθi, then the primary vehicle position points Pi ′ (Xi ′, Yi ′) and Pi ′ based on dead reckoning navigation are From equations (1) to (3), the vehicle direction θi is calculated as follows: θi = θi-1 +Δθi Xi '=Xi-1 +L0 ・cos θi Yi
'=Yi-1 +L0 ·sin θi.

In this case, (a) there is a link that allows a perpendicular line to be drawn from point Pi', and the angle formed by the link with the latest traveling trajectory SHi connecting points Pi-1 and Pi' is within a certain value, and , search for a road where the length of the perpendicular drawn from point Pi' to the link is within a certain distance. Here, link LKa1 (
A road RDa with a straight line connecting nodes Na0 and Na1)
and a link LKb1 (a straight line connecting nodes Nb0 and Nb1). (b) The lengths of perpendicular lines RLia and RLib drawn from point Pi' to links LKa1 and LKb1 are determined, and the road with the shorter link is selected as a map matching candidate road. Here, it is road RDa. (c) Point Pi-1 moves along the travel trajectory SHi in the direction of the perpendicular line RLia on the link LKa1 (or on the link LK
point Pi-1.
(d) Finally, rotate and move around point PTi-1 until PTi' is on link LKa1 to find the moving point,
Let the determined vehicle position be Pi (Xi, Yi).

Note that the vehicle orientation at the determined vehicle position Pi remains at θi. If the corresponding road is not found in (a), the primary vehicle position Pi' is directly used as the determined vehicle position Pi (Xi, Yi). Furthermore, as shown in FIG. 14, when point Pi-1, which is the previously determined vehicle position, is on road RDa, moving point PTi-1 is on point Pi-1.
-1. Furthermore, as shown in FIG. 15, when turning at an intersection at point Pi-1, the primary vehicle position Pi' is projected onto the road RDa that intersects with the road RDb by map matching, and is determined as the determined vehicle position Pi (Xi, Yi). Ru.

[0008] In this way, by detecting the vehicle position by combining dead reckoning and map matching, it is possible to obtain a vehicle position in which the primary vehicle position error caused by the error between the distance sensor and the relative orientation sensor is corrected.

[0009]

[Problems to be Solved by the Invention] However, in map matching using the projection method described above, the error itself in the vehicle direction due to the error in the relative orientation sensor is not corrected, so as the vehicle continues to travel, the error accumulates. , the calculated vehicle heading may deviate significantly from the actual vehicle heading. At this time, as shown in FIG. 16, the vehicle is on the road RDc.
If the vehicle is traveling above the previous confirmed vehicle position Pj-
Assuming that the vehicle heading calculated in step 1 is θj-1, the actual vehicle heading is [θj-1], and the change in heading when traveling from Pj-1 to L0 is Δθj, the primary vehicle position based on θj-1 is Pj' , [θj-1] is [Pj'], and the determined vehicle position corrected upward on the road RDc by map matching is Pj, respectively.
If the primary vehicle position is calculated based on the actual vehicle direction [θj−1], if there is a road RDd running parallel to the road as shown in FIG. Although map matching is possible on RDc, there is a problem in that when the primary vehicle position is calculated based on the calculated vehicle orientation θj-1, the road RDd is closer, which may cause a map matching error.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a vehicle position correction device for an on-vehicle navigator that can improve the accuracy of correcting the vehicle position by map matching by correcting errors in vehicle direction.

[0011]

[Means for Solving the Problems] In one aspect of the present invention, the above-mentioned problem is solved by having a map data storage means that stores map data, and a direction change detected by a direction sensor that is stored in the vehicle direction storage means. A vehicle heading calculation means calculates a new vehicle heading by integrating the vehicle heading of the vehicle, and rewrites the vehicle heading storage means with the obtained vehicle heading. A vehicle position calculation means calculates a change in the vehicle position using the obtained vehicle heading, and calculates the primary vehicle position by dead reckoning by vector combining it with the previously determined vehicle position, and the vehicle position calculation means calculates the primary vehicle position. Each time the calculation is performed, the map data is referenced to search for map matching candidate roads based on the projection method.
When a map matching candidate road exists, the primary vehicle position is corrected on the matching candidate road as a determined vehicle position, and when a map matching road does not exist, the primary vehicle position itself is output as the determined vehicle position. and, when the vehicle position is corrected by the vehicle position correcting means, a determining means refers to the map data to determine whether the link to be corrected for the latest vehicle position is longer than a certain distance; This is achieved by providing a vehicle heading correction means that, when determined, determines the heading of the link to be corrected and rewrites the vehicle heading storage means of the vehicle heading calculation means with the heading.

[0012] In another aspect of the present invention, the map data storage means that stores the map data and the direction change detected by the direction sensor are integrated into the previous vehicle direction stored in the vehicle direction storage means. A vehicle heading calculation means that calculates a new vehicle heading and rewrites the vehicle heading storage means with the obtained vehicle heading; A vehicle position calculation means calculates the change in the vehicle position using , Search for a map matching candidate road by the projection method by referring to the map data, and if a map matching candidate road exists, correct the primary vehicle position to be on the matching candidate road to determine the final vehicle position, and if there is no map matching road. At this time, the vehicle position correcting means outputs the primary vehicle position itself as the determined vehicle position, and each time the vehicle position is determined by the vehicle position correcting means, it is determined whether the vehicle position has been continuously corrected a predetermined number of times. In addition, a determining means refers to the map data and determines whether the link for which the latest vehicle position is to be corrected is longer than a certain distance; This is achieved by providing vehicle heading correction means for determining the heading of the link to be corrected when it is determined that the link to be corrected is a certain distance or more, and rewriting the vehicle heading storage means of the vehicle heading calculating means with the direction. Ru.

[0013] In still another aspect of the present invention, the map data storage means that stores map data and the direction change detected by the direction sensor are integrated into the previous vehicle direction stored in the vehicle direction storage means. a vehicle heading calculation means that calculates a new vehicle heading and rewrites the vehicle heading storage means with the obtained vehicle heading; and a vehicle heading calculation means that calculates a new vehicle heading by the vehicle heading calculation means each time the distance sensor detects traveling a certain distance. a vehicle position calculation means for calculating a primary vehicle position by dead reckoning navigation by vector-synthesizing the vehicle position with the previously determined vehicle position; Map matching candidate roads are searched by the projection method by referring to the map data, and when a map matching candidate road exists, the primary vehicle position is corrected to be on the matching candidate road as a final vehicle position, and when no map matching road exists. , a vehicle position correction means that outputs the primary vehicle position itself as a final vehicle position, and when the vehicle position is corrected by the vehicle position correction means, the map data is referred to and the link to be corrected for the latest vehicle position is determined to be over a certain distance. a determining means for determining whether the link to be corrected is located at a certain distance, and determining whether the absolute value of the difference between the bearing of the link to be corrected and the vehicle heading calculated by the vehicle heading calculation means is greater than or equal to a certain value; If the above exists, and it is determined that the absolute value of the difference between the direction of the link to be corrected and the vehicle direction calculated by the vehicle direction calculation means is greater than a certain value, the vehicle direction is calculated using the direction in which the vehicle direction is corrected by a certain value. This is achieved by providing a vehicle orientation correction means for rewriting the vehicle orientation storage means of the means.

[0014]

[Operation] According to one aspect of the present invention, the direction change detected by the direction sensor is integrated with the previous vehicle direction stored in the vehicle direction storage means to obtain a new vehicle direction. The vehicle heading storage means is rewritten, and each time the distance sensor detects traveling a certain distance, the calculated vehicle heading is used to find the change in the vehicle position, and the vector is combined with the previously determined vehicle position to perform dead reckoning navigation. Calculate the primary vehicle position by , and every time the primary vehicle position is calculated, refer to the map data to search for a map matching candidate road by the projection method,
When a map matching candidate road exists, the primary vehicle position is corrected to the matching candidate road and becomes the final vehicle position, and when no map matching road exists, the primary vehicle position itself is output as the final vehicle position and the vehicle position is determined. When a correction is made, the map data is referred to to determine whether the link to be corrected in the latest vehicle position is longer than a certain distance, and when it is determined that the distance is longer than a certain distance, the direction of the link to be corrected is determined and the direction is The vehicle direction storage means of the vehicle direction calculation means is rewritten. As a result, when the vehicle position is corrected by map matching, if the link to be corrected is over a certain distance, the vehicle direction will be corrected to the direction of the link, which is almost the same as the actual road direction. The accuracy of position correction can be improved.

According to another aspect of the present invention, a new vehicle direction is determined by integrating the change in direction detected by the direction sensor with the previous vehicle direction stored in the vehicle direction storage means. Rewrite the vehicle orientation storage means with the calculated vehicle orientation, and each time the distance sensor detects traveling a certain distance, calculate the change in vehicle position using the calculated vehicle orientation,
The primary vehicle position is calculated by dead reckoning by vector combining with the previously determined vehicle position, and each time the primary vehicle position is calculated,
Map matching candidate roads are searched by the projection method by referring to the map data, and when a map matching candidate road exists, the primary vehicle position is corrected to be on the matching candidate road as a final vehicle position, and when no map matching road exists. , outputs the primary vehicle position itself as the final vehicle position,
Each time the vehicle position is determined, it is determined whether the vehicle position has been corrected a predetermined number of times in succession, and it is determined whether the link to which the latest vehicle position is to be corrected is longer than a certain distance by referring to map data; If the vehicle position has been corrected a predetermined number of times and it is determined that the latest link to be corrected is a certain distance or more, the direction of the link to be corrected is determined, and the vehicle direction calculation means is Rewrite the vehicle direction memory means. Thereby, when the vehicle position is determined, the vehicle heading can be corrected only when the vehicle position is corrected to be on the correct road, and mistakes in vehicle heading correction can be avoided.

According to still another aspect of the present invention, a new vehicle direction is determined by integrating the change in direction detected by the direction sensor with the previous vehicle direction stored in the vehicle direction storage means. The vehicle orientation storage means is rewritten with the determined vehicle orientation, and each time the distance sensor detects traveling a certain distance, the calculated vehicle orientation is used to determine the change in vehicle position, and vector synthesis is performed on the previously determined vehicle position. The primary vehicle position is calculated using dead reckoning, and each time the primary vehicle position is calculated, a map matching candidate road is searched by the projection method by referring to the map data, and when a map matching candidate road exists, the primary vehicle position is calculated. The vehicle position is corrected on the matching candidate road as the confirmed vehicle position. When there is no map matching road, the primary vehicle position itself is output as the confirmed vehicle position. When the vehicle position is corrected, the map data is referred to and the latest vehicle position is output. It is determined whether the link to be corrected in the vehicle position is longer than a certain distance, and it is also determined whether the absolute value of the difference between the bearing of the link to be corrected and the vehicle heading calculated by the vehicle heading calculating means is greater than a certain value, and the link to be corrected is determined. is over a certain distance,
In addition, when it is determined that the absolute value of the difference between the direction of the link to be corrected and the vehicle direction calculated by the vehicle direction calculation means is greater than a certain value, the vehicle direction calculated by the vehicle direction calculation means is changed in the direction in which the vehicle direction is corrected by the fixed value. Rewrite the direction memory means. As a result, when the vehicle position is corrected through map matching, if the link to be corrected is a certain distance or longer, the vehicle direction will be corrected in stages to bring it closer to the direction of the link, which is almost the same as the actual road direction. Therefore, the accuracy of correcting the vehicle position by map matching can be improved.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram of the main parts of an on-vehicle navigator according to the present invention.

In the figure, 1 is a CD-ROM serving as a map data storage means, 2 is an operation panel, and includes left, right, up, and down scroll keys for scrolling the map with respect to the vehicle position mark, map search, It is equipped with various keys for enlarging/reducing. 3 is a relative azimuth sensor that detects the relative azimuth and outputs a relative azimuth signal; 4 is a distance sensor that outputs a pulse indicating that the vehicle has traveled a certain distance every time the vehicle travels a certain distance L0.

Reference numeral 5 denotes a system controller composed of a microcomputer, which displays a map around the vehicle position together with a vehicle position mark on a display device to be described later. 5a is a map data buffer memory for temporarily storing map data;
Reference numeral b indicates a map reading control unit which inputs fixed vehicle position data from a vehicle position correction unit which will be described later and reads out map data around the vehicle position from the CD-ROM 1 into the map data buffer memory 5a, and 5c indicates a vehicle direction which stores vehicle direction data. A memory 5d calculates a new vehicle orientation by integrating the change in orientation detected by the relative orientation sensor 3 to the previous vehicle orientation stored in the vehicle orientation memory 5c, and also stores the determined vehicle orientation in the vehicle orientation memory 5c. Rewrite vehicle direction calculation part,
5e is a primary vehicle position calculation unit, which is energized by a pulse input from the distance sensor 4 every time the vehicle travels a certain distance L0, and calculates the position of the vehicle by dead reckoning using the vehicle orientation calculated by the vehicle orientation calculation unit 5d. Current position (absolute longitude, absolute latitude)
is calculated and used as primary vehicle position data. 5f searches for a map matching candidate road based on the projection method by referring to the road data in the map data read out to the map data buffer memory 5a based on the primary vehicle position data, and when a map matching candidate road exists, it searches for a map matching candidate road on the road. 5g is the latest confirmed vehicle position data and vehicle position correction unit that outputs the fixed vehicle position data that has been corrected and outputs the primary vehicle position data itself as the fixed vehicle position data when there is no map matching candidate road. A traveling data memory 5h stores the correction status of the vehicle position in the vehicle position correction unit 5f for a predetermined number of times (9 times in this embodiment); The first determining unit 5i refers to the map data and determines whether it has been modified nine times in a row including this time. A second determining unit 5j that determines whether the latest link to be modified is a straight section of a certain distance or more, when the second determining unit 5i determines that the latest link to be modified is a straight section of a certain distance or more, the map data This is a vehicle direction correction unit that refers to the direction of the link to obtain the latest direction of the link to be corrected, and rewrites the vehicle direction data in the vehicle direction memory 5c using the direction. 5k reads map data around the vehicle position from the map data buffer memory 5a and outputs it to the display device to draw a map, and also outputs the confirmed vehicle position data input from the vehicle position correction unit 5f to the display device to determine the vehicle position. This is a map drawing control unit that displays marks.

Reference numeral 6 denotes a display device, which includes a CRT controller 7, a video RAM (V-RAM) 8, a readout control section 9, a CRT 10, etc., and is adapted to display desired maps and marks on the CRT screen. .

FIG. 2 is an explanatory diagram of data stored in the travel data memory 5g, and the latest confirmed vehicle position data is S.
is stored as . Furthermore, when the vehicle position correction unit 5f outputs the confirmed vehicle position, the flag data, which is represented by 1 when the vehicle position is corrected by map matching and 0 when the vehicle position is not corrected, is set to the latest confirmed vehicle position. Related F1
The information is stored from F9 to F9, which corresponds to the eight previous confirmed vehicle position.

3 and 4 are flowcharts showing map and mark drawing processing, vehicle orientation, primary vehicle position calculation, and vehicle position and vehicle orientation correction processing performed by the system controller 5, and FIG.
-FIG. 7 are explanatory diagrams of a method for correcting the vehicle position by the system controller 5, and the following description will be made with reference to these diagrams.

[0023] In advance, according to the driver's map selection operation, the map reading control unit 5b transfers map data of a predetermined scale including the starting point from the CD-ROM 1 to the map data buffer memory 5a, and performs map drawing control. The section 5k reads the map data from the map data buffer memory 5a, outputs it to the display device 6, and displays the desired map on the CRT 10.
Assume that the image is being drawn on the screen.

As shown in FIG. 5, when the driver performs an operation to set (X0, Y0) as the position coordinates of the departure point on the operation panel 2, (X0, Y0) is set as the fixed vehicle position P0 of the departure point.
0) is initially set in the primary vehicle position calculation unit 5e (Fig. 3
Steps 101 and 102), and when θ0 is set as the vehicle direction (absolute direction in the direction of vehicle movement),
θ0 is the vehicle orientation at the departure point in the vehicle orientation memory 5c.
(steps 103, 104). Following this initial setting process, S=P0 in the travel data memory 5g is set, and all flags F1 to F9 are cleared and initialized to 0 (step 105). Further, the map drawing control unit 5k outputs the determined vehicle position data of the starting point to the display device 6 as vehicle position mark data, and displays the vehicle position mark at a predetermined location on the map screen (step 106).

[0025] When the vehicle starts traveling, a certain distance L0
Every time the vehicle travels, the distance sensor 4 outputs a pulse. When the first pulse is input from the distance sensor 4, the vehicle orientation calculation unit 5d inputs the relative orientation signal Δθ1 from the relative orientation sensor 3, calculates θ1 = θ0 + Δθ1, and calculates the point (P1) which is a distance L0 from P0.
The vehicle heading θ1 at point ') is determined, the vehicle heading data in the vehicle heading memory 5c is rewritten, and the same is output to the primary vehicle position calculating section 5e (steps 107 to 111).

Furthermore, the primary vehicle position calculation unit 5e which receives the first pulse from the distance sensor 4 calculates the set unit distance L0.
, Determined vehicle position coordinates of departure point P0 (X0, Y0)
Using the vehicle orientation θ1 calculated by the vehicle orientation calculation unit 5e, ΔX=L0 ・cos θ1 ΔY=L0 ・sin θ1 Find the coordinates of the current primary vehicle position P1 ′ (X1 ′, Y1 ′) that has advanced from L0 (
Step 201 in FIG. 4). The primary vehicle position P1' is output to the vehicle position correction section 5f.

Next, the vehicle position correction unit 5f searches for a map matching candidate road using the projection method for the primary vehicle position P1' (step 202). That is, first, point P
S=P0 and P1', which have a link that allows a perpendicular line to be lowered from 1', and are stored in the traveling data memory 5g.
A search is made for a road in which the angle formed by the link and the latest travel trajectory SH1 connecting the link is within a certain value, and the length of the perpendicular line drawn from point P1' to the link is within a certain distance. Here, a road RDe having a link LKe1 (a straight line connecting nodes Ne0 and Ne1) and a link LKf1 (a straight line connecting nodes Ne0 and Ne1) are shown.
The road RDf has a straight line connecting f0 and Nf1).

Next, link LKe1,L from point P1'
The lengths of perpendicular lines RL1e and RL1f drawn to Kf1 are determined, and the road having the shorter link is determined as a matching candidate road. Here, it is road RDe.

When a matching candidate road is found, the vehicle position correction unit 5f then moves the travel trajectory SH1 in parallel in the direction of the perpendicular line RL1e until the point P0 is on the link LKe1 (or on the extension line of the link LKe1). ,
Move points P0 and P1' to find points PT0 and PT1', and further move PT1' to link LK with point PT0 as the center.
The map reading control unit 5b, primary vehicle position calculation unit 5e, map drawing control unit 5k,
First discrimination section 5h, second discrimination section 5i, vehicle orientation correction section 5j
Also, S=P1 (
The current confirmed vehicle position is registered as (X1, Y1) (steps 203 to 205). Also, F9 = F8, F8 = F7, F7 = F6 in the driving data memory 5g.
, F6 = F5 , F5 = F4 , F4 = F3
, F3 = F2, F2 = F1, and after shifting the flag data, the vehicle position was corrected this time, so F1
= 1 (steps 206, 207). If no matching candidate road is found in step 202, the primary vehicle position P1' itself is output as the determined vehicle position P1 (X1, Y1), and is registered in the travel data memory 5g as S=P1 (step 202). 203, 208, 209), after shifting the flag data in the travel data memory 5g, the vehicle position was not corrected, so it is registered as F1 = 0 (step 210
, 211). However, here it is assumed that F1 =1.

Next, the first determining unit 5h determines whether all of the flag data F1 to F9 in the travel data memory 5g are 1, and determines whether the vehicle position has been corrected nine times in a row (step 212). ). Here, F2 ~F
Since 9 = 0, it is judged as NO, and no action is taken to correct the vehicle orientation.

On the other hand, the map readout control section 5b determines whether the vehicle is out of the range of the map that has been read out to the map data buffer memory 5a, based on the current confirmed vehicle position data input from the vehicle position correction section 5f, and when it is out of the range of the map that has been read into the map data buffer memory 5a. reads new map data containing the vehicle position from the CD-ROM 1 to the map data buffer memory 5a. Furthermore, the map drawing control unit 5k outputs the currently determined vehicle position data to the display device 6 as vehicle position mark data, and moves the vehicle position mark on the map screen. Furthermore, when the vehicle position is off the screen, the map drawing control unit 5k adds a new one from the map data buffer memory 5a into which the vehicle position is entered.
The map data for the screen is read out and output to the display device 6 to change the displayed map (the above is the navigation process, step 112 in FIG. 3).

When the second pulse is input from the distance sensor 4, the vehicle direction calculation unit 5d inputs the relative direction signal Δθ2 from the relative direction sensor 3, calculates θ2 = θ1 + Δθ2, and finds a point that has advanced a distance L0 from P1. (P2
') is determined, the vehicle orientation data in the vehicle orientation memory 5c is rewritten, and the vehicle orientation data is output to the primary vehicle position calculation unit 5e (steps 113, 108 to 111).
).

Furthermore, the primary vehicle position calculation unit 5e that receives the second pulse from the distance sensor 4 calculates the set unit distance L0.
, the current primary vehicle position P2'(X2',Y2') is determined and output to the vehicle position correction section 5f (step 201 in FIG. 4).

Next, the vehicle position correction unit 5f searches for a map matching candidate road using the projection method for the primary vehicle position P2' in the same manner as described above (step 202). Assume that a matching candidate road is found and becomes road RDe. Next, the vehicle position correction unit 5f obtains a vehicle position by correcting the primary vehicle position P2' on the road RDe in the same manner as described above, and determines the fixed vehicle position P2 (X2
, Y2), a map readout control section 5b, a primary vehicle position calculation section 5e, a map drawing control section 5k, and a first discrimination section 5h.
, is outputted to the second discrimination unit 5i and the vehicle orientation correction unit 5j, and S=P2 (X2, Y2
) to register the current confirmed vehicle position (step 20
3-205). Also, after shifting the flag data in the driving data memory 5g, I corrected the vehicle position this time, so F
1 = 1 (steps 206, 207). If no matching candidate road is found in step 203, the primary vehicle position P2' itself is output as the determined vehicle position P2 (X2, Y2), and S=P2
(Steps 208, 209)
, since the vehicle position was not corrected after the flag data in the travel data memory 5g was shifted, F1 = 0 is registered (steps 210, 211). However, here it is assumed that F1 =1.

Next, the first determining section 5h determines whether all of the flag data F1 to F9 in the travel data memory 5g are 1, and determines whether the vehicle position has been corrected nine times in a row (step 212). ). Here, F3 ~F
Since 9 = 0, it is judged as NO, and no action is taken to correct the vehicle orientation.

On the other hand, the map readout control unit 5b determines whether the vehicle is out of the range of the map that has been read out to the map data buffer memory 5a, based on the current confirmed vehicle position data input from the vehicle position correction unit 5f, reads new map data containing the vehicle position from the CD-ROM 1 to the map data buffer memory 5a. Furthermore, the map drawing control unit 5k outputs the currently determined vehicle position data to the display device 6 as vehicle position mark data, and moves the vehicle position mark on the map screen. Furthermore, when the vehicle position is off the screen, the map drawing control unit 5k adds a new one from the map data buffer memory 5a into which the vehicle position is entered.
The map data for the screen is read out and output to the display device 6 to change the displayed map (the above is the navigation process, step 112 in FIG. 3).

Similarly, every time a pulse is output from the distance sensor 4, the vehicle direction calculation section 5d calculates the relative direction Δθi indicated by the relative direction signal input from the relative direction sensor 3.
The vehicle orientation θi-1 stored in the vehicle orientation memory 5c
(Step 1)
13, 108 to 110), and the vehicle orientation memory 5c is rewritten with θi (step 111), and the primary vehicle position calculation unit 5e calculates the position change Δx, using the vehicle orientation θi calculated by the vehicle orientation calculation unit 5d. ΔY is calculated and vector-combined with the previous determined vehicle position Pi-1 (Xi-1, Yi-1) to obtain the current primary vehicle value Pi'(Xi'
, Yi') (step 201 in FIG. 4), and the vehicle position correction unit 5f refers to the map data to determine the primary vehicle position P.
A map matching candidate road is searched by the projection method for i ′ (Xi ′, Yi ′) (step 202), and if a map matching candidate road exists, the vehicle position is corrected on the road and the determined vehicle position Pi (Xi , Yi
) (steps 203, 204), and if there is no map matching candidate road, the primary vehicle position Pi' is output as the determined vehicle position Pi (step 20
3, 208), and after registering S=Pi in the driving data memory 5g (step 205 or 209) and shifting the flag data in the driving data memory 5g (step 206 or 209), the vehicle position was corrected this time. If so, set F1 = 1 (step 207), and if no correction is made, register F1 = 0 (step 211).
). Then, the first determination unit 5h determines whether the flag data F1 to F9 in the travel data memory 5g are all 1, and if NO, the map reading control unit 5b and the map drawing control unit 5k
Only predetermined navigation processing is performed (step 2
12, step 112 in FIG. 3).

[0038] Until the determined vehicle position P9 is determined,
When the vehicle position is continuously corrected by map matching, F1 to F9 in the travel data memory 5g all become 1. Then, the first determination unit 5h performs step 212 in FIG.
The answer is YES. That is, since the vehicle position has been corrected nine times in succession, it is determined that the determined vehicle position P9 has been correctly corrected to the road on which the vehicle is actually traveling. At this time, the second determination unit 5i refers to the confirmed vehicle position data P9 and the map data in the map data buffer memory 5a, and calculates the link LKe2 from the coordinates of the nodes Ne1 and Ne2 at both ends of the correction target link LKe2 of the confirmed vehicle position P9. The distance is calculated and it is determined whether the straight section is longer than a certain distance Lc (step 213).

However, here, the distance of link LKe2 is L
If it is shorter than c, it will be judged as NO. Link LK
When the distance of e2 is short, it is often near an intersection or a place where the road is curved, and the map data itself is created by manual input, and the orientation accuracy of link LKe2 is low, so it was calculated. Figure 3 without correcting the vehicle orientation.
Only the navigation processing in step 112 is performed.

After that, while continuously correcting the vehicle position by map matching, as shown in FIG. 6, when the confirmed vehicle position reaches P11 and the link LKe3 to be corrected becomes longer than a certain distance Lc, The determination unit 5h determines YES in step 212, and determines that the determined vehicle position P11 has been correctly corrected to the road RDe on which the vehicle is actually traveling. Subsequently, the second determining unit 5i performs step 2.
13 is YES, and it is determined that the correction target link LKe3 of the confirmed vehicle position P11 is a long straight section with a fixed distance Lc or more, and that the azimuth accuracy of the link LKe3 is high.

At this time, the vehicle orientation correction unit 5j refers to the confirmed vehicle position data P11 and the map data in the map data buffer memory 5a, and calculates the orientation (absolute orientation) θ' formed by the link LKe3 to be corrected this time. Vehicle position memory 5
θ' is written as θ11 in c, and the vehicle direction is corrected (step 214). As a result, the errors accumulated in previous vehicle heading calculations are corrected, and the accuracy of the vehicle heading and primary vehicle position determined in subsequent calculations is improved, and map matching accuracy is also improved accordingly.

When the next pulse is input from the distance sensor 4 after the navigation processing in step 112 in FIG. is calculated and stored in the vehicle orientation memory 5c (steps 113, 108 to 11).
1). This vehicle heading θ12 does not include the cumulative error of the vehicle heading calculated up to the previous time. Next, the primary vehicle position calculating section 5e uses the previously determined vehicle position P11 and the vehicle orientation θ12 calculated by the vehicle orientation calculating section 5d to find the current primary vehicle position P12', and outputs it to the vehicle position correcting section 5f. (Step 201 in FIG. 4). Vehicle position correction unit 5
f searches for a map matching candidate road using the projection method (step 202) and corrects the vehicle position (step 20).
3-205). At this time, the accuracy of the primary vehicle position P12' is high because the error in the vehicle direction θ12 used for calculation is small. Therefore, the accuracy of the map matching process in the vehicle position correction unit 5f is increased, and the accuracy of the corrected vehicle position is improved. Furthermore, matching errors (correcting the vehicle position to a road different from the road on which the vehicle is traveling) are less likely to occur.

When the primary vehicle position P12' is corrected by map matching to obtain the final vehicle position P12, all F1 to F9 in the travel data memory 5g become 1 again (steps 206 and 207), so the first determination The unit 5h again determines YES in step 212. Subsequently, the second determination unit 5i determines that the current correction target link LKe3 is at a certain distance Lc.
It is determined whether the above is the case (step 219), and if YES, the vehicle direction correction unit 5j calculates the direction θ' of the link LKe3,
Rewrite the data in the vehicle orientation memory 5c to set the vehicle orientation θ
12 is corrected again (step 214). Therefore, since the error in the previously calculated vehicle direction θ12 is immediately corrected, the error does not accumulate.

[0044] Thereafter, in the same way, as long as the primary vehicle position is continuously corrected by map matching and the final vehicle position continues to be determined, on the condition that the link to be corrected has a length of a certain distance Lc or more. , Every time a confirmed vehicle position is obtained, the vehicle heading is corrected using the almost exact direction of the link to be corrected, so the accuracy of the primary vehicle position calculated using the vehicle heading is improved, and the corrected vehicle position by map matching is The accuracy of matching is improved, and matching errors are less likely to occur.

As shown in FIG. 7, when a vehicle enters a road RDh where no road data exists from a road RDg where road data exists in the map data, map matching is performed for a certain primary vehicle position Pj'. If no candidate road is found, the vehicle position correction unit 5f sets the primary vehicle position itself as the final vehicle position Pj (step 2 in FIG. 4).
02, 203, 208, 209). At this time, the vehicle position correction unit 5f shifts the flag data in the travel data memory 5g and registers that the vehicle position has not been corrected by setting F1=0 (steps 210, 211). Therefore, the first determination unit 5h will determine NO in step 212 at least nine times in the future, including this time, and during this time,
No corrections will be made to the vehicle orientation. As a result, when the correction of the vehicle position by map matching is resumed after map matching becomes impossible, there is a possibility that a matching error occurs on a road different from the road on which the vehicle is actually driving. However, there is no possibility that the vehicle direction will be incorrectly corrected due to the wrong road direction, and it becomes possible to reliably make corrections only to the correct direction.

In the above-mentioned embodiment, as shown in the flowchart of FIG. 4, when the second determining section determines that the distance of the link to be modified is Lc or more (YES in step 213), the vehicle position modifying section selects the link to be modified. The direction θ' of the link is calculated and the vehicle direction memory is rewritten with the direction data (step 214), but the system controller is told that there is a difference between the direction θ' of the link to be corrected and the vehicle direction θi stored in the vehicle direction memory. A third determining unit is provided to determine whether the absolute value of When it is determined that Lc or more, the third determination unit further determines whether the absolute value of the difference between the direction θ' of the link to be corrected and the vehicle direction θi stored in the vehicle direction memory is greater than or equal to a certain value (step 301), YES
When , the vehicle orientation correction unit sets the vehicle orientation θi to a constant value θ
The vehicle direction memory may be rewritten with the vehicle direction corrected by c1 (steps 302, 303, or steps 302, 304). This makes it possible to correct the vehicle heading in stages every time the vehicle position is corrected through map matching.

Furthermore, the absolute value of the difference between the heading θ' of the link to be corrected in the system controller and the vehicle heading θi stored in the vehicle heading memory is set to a constant value θc2 (for example, 0.5 degrees).
In addition to providing a fourth determining unit that determines whether there is a
Step 214 is modified as shown in FIG. 9, and when the second determination unit determines that the distance of the link to be modified is Lc or more, the fourth determination unit further stores the bearing θ' of the link to be modified and the vehicle direction memory. It is determined whether the absolute value of the difference in the stored vehicle direction θi is greater than or equal to a certain value θc2 (step 401), and Y
In the case of ES, the vehicle direction correction section may rewrite the vehicle direction memory with the direction θ' of the link to be corrected (step 402), and in the case of NO, the vehicle direction may not be corrected. As a result, when the in-vehicle navigator is capable of heads-up display, it is possible to prevent the image from wobbling more than necessary when displaying the map image on the screen at a head-up angle of 0°.

Furthermore, in the above-described embodiment, when the second determining section determines that the link to be corrected is a straight section of a certain distance Lc or more, the vehicle direction is unconditionally corrected. Even if the target link is over a certain distance, if the vehicle is near the edge of the link, there may be a relatively large error between the actual vehicle direction and the link direction due to proximity to an intersection or a curve in the road. Therefore, as shown in FIG. 10, the correction target link LK (nodes N0 and N1
When the length (connecting the
c is a positive predetermined decimal value and has the relationship a+b+c=1)
The correction accuracy may be maintained above a certain level by correcting the vehicle heading only while the confirmed vehicle position is within the interval of distance b·Ls divided by the ratio of . In this case, any of a=c, a>c, and a<c may be satisfied.

Furthermore, in step 212 of FIG. 4, when it is determined that the vehicle position has been corrected nine times in a row, the process moves to the next step 213. Not limited, 10 times or more,
Alternatively, it may be set to any number of times from 2 to 8 times, or only S and F1 may be stored in the travel data memory, and the process in step 212 may be replaced with step 501 in FIG. 11. If F1 = 1, the process may simply proceed to step 213.

[0050]

[Effects of the Invention] According to one aspect of the present invention, the direction change detected by the direction sensor is integrated with the previous vehicle direction stored in the vehicle direction storage means to obtain a new vehicle direction. The vehicle orientation storage means is rewritten with the determined vehicle orientation, and each time the distance sensor detects traveling a certain distance, the calculated vehicle orientation is used to determine the change in vehicle position, and vector synthesis is performed on the previously determined vehicle position. The primary vehicle position is calculated using dead reckoning navigation, and each time the primary vehicle position is calculated, map data is referred to to search for a map matching candidate road using a projection method, and when a map matching candidate road exists,
The primary vehicle position is corrected on the matching candidate road to become the confirmed vehicle position, and when there is no map matching road, the primary vehicle position itself is output as the confirmed vehicle position, and when the vehicle position is corrected, the map data is It is determined whether the link to be corrected of the latest vehicle position is at least a certain distance by referring to the link, and when it is determined that the distance is at least a certain distance, the direction of the link to be corrected is determined, and the direction is stored in the vehicle direction calculation means using the direction. Since the method is configured to rewrite, when the vehicle position is corrected by map matching, if the link to be corrected is over a certain distance, the vehicle direction will be corrected to the direction of the link, which is almost the same as the actual road direction. Therefore, the accuracy of correcting the vehicle position by map matching can be improved.

According to another aspect of the present invention, a new vehicle direction is determined by integrating the change in direction detected by the direction sensor with the previous vehicle direction stored in the vehicle direction storage means. Rewrite the vehicle orientation storage means with the calculated vehicle orientation, and each time the distance sensor detects traveling a certain distance, calculate the change in vehicle position using the calculated vehicle orientation,
The primary vehicle position is calculated by dead reckoning by vector combining with the previously determined vehicle position, and each time the primary vehicle position is calculated,
Map matching candidate roads are searched by the projection method by referring to the map data, and when a map matching candidate road exists, the primary vehicle position is corrected to be on the matching candidate road as a final vehicle position, and when no map matching road exists. , outputs the primary vehicle position itself as the final vehicle position,
Each time the vehicle position is determined, it is determined whether the vehicle position has been corrected a predetermined number of times in succession, and it is determined whether the link to which the latest vehicle position is to be corrected is longer than a certain distance by referring to map data; If the vehicle position has been corrected a predetermined number of times and it is determined that the latest link to be corrected is a certain distance or more, the direction of the link to be corrected is determined, and the vehicle direction calculation means is Since the vehicle orientation storage means is configured to be rewritten, when the vehicle position is determined, the vehicle orientation can be corrected only when the vehicle position is corrected on the correct road, thereby avoiding errors in vehicle orientation correction. can do.

According to still another aspect of the present invention, a new vehicle direction is determined by integrating the change in direction detected by the direction sensor to the previous vehicle direction stored in the vehicle direction storage means, and The vehicle orientation storage means is rewritten with the determined vehicle orientation, and each time the distance sensor detects traveling a certain distance, the calculated vehicle orientation is used to determine the change in vehicle position, and vector synthesis is performed on the previously determined vehicle position. The primary vehicle position is calculated using dead reckoning, and each time the primary vehicle position is calculated, a map matching candidate road is searched by the projection method by referring to the map data, and when a map matching candidate road exists, the primary vehicle position is calculated. The vehicle position is corrected on the matching candidate road as the confirmed vehicle position. When there is no map matching road, the primary vehicle position itself is output as the confirmed vehicle position. When the vehicle position is corrected, the map data is referred to and the latest vehicle position is output. It is determined whether the link to be corrected in the vehicle position is longer than a certain distance, and it is also determined whether the absolute value of the difference between the bearing of the link to be corrected and the vehicle heading calculated by the vehicle heading calculating means is greater than a certain value, and the link to be corrected is determined. is over a certain distance,
In addition, when it is determined that the absolute value of the difference between the direction of the link to be corrected and the vehicle direction calculated by the vehicle direction calculation means is greater than a certain value, the vehicle direction calculated by the vehicle direction calculation means is changed in the direction in which the vehicle direction is corrected by the fixed value. Since the direction storage means is configured to be rewritten, when the vehicle position is corrected by map matching, if the link to be corrected is a certain distance or more, steps are taken to bring the direction of the link closer to the direction of the link, which is almost the same as the actual road direction. Since the vehicle orientation is corrected automatically, the accuracy of correcting the vehicle position by map matching can be improved.

[Brief explanation of drawings]

FIG. 1 is a block diagram of main parts of an in-vehicle navigator according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram of data stored in the travel data memory of FIG. 1;

FIG. 3 is a flowchart showing the operation of the system controller of FIG. 1;

FIG. 4 is a flowchart showing the operation of the system controller of FIG. 1;

FIG. 5 is an explanatory diagram illustrating the operation of the system controller in FIG. 1;

FIG. 6 is an explanatory diagram illustrating the operation of the system controller in FIG. 1;

FIG. 7 is an explanatory diagram illustrating the operation of the system controller in FIG. 1;

FIG. 8 is a partially omitted flowchart showing the operation of a modification of FIG. 1;

FIG. 9 is a partially omitted flowchart showing the operation of another modification of FIG. 1;

10 is an explanatory diagram illustrating the operation of still another modification of FIG. 1. FIG.

FIG. 11 is a partially omitted flowchart showing the operation of another modification of FIG. 1;

FIG. 12 is an explanatory diagram of a general vehicle position detection method using dead reckoning navigation.

FIG. 13 is an explanatory diagram of map matching using a conventional projection method.

FIG. 14 is an explanatory diagram of map matching using a conventional projection method.

FIG. 15 is an explanatory diagram of map matching using a conventional projection method.

FIG. 16 is an explanatory diagram showing a problem with map matching using a conventional projection method.

FIG. 17 is an explanatory diagram showing a problem with map matching using a conventional projection method.

[Explanation of symbols]

1 CD-ROM 3 Relative orientation sensor 4 Distance sensor 5 System controller 5c Vehicle position memory 5d　Vehicle orientation calculation section 5e Primary vehicle position calculation section 5f Vehicle position correction section 5g Travel data memory 5h 1st discrimination part 5i Second discrimination section 5j　Vehicle orientation correction section 5k Map drawing control section 6 Display device

Claims (3)

[Claims] 1. A map data storage means storing map data and a direction change detected by a direction sensor, which is integrated with the previous vehicle direction stored in the vehicle direction storage means to obtain a new vehicle direction; A vehicle heading calculation means that rewrites the vehicle heading storage means with the obtained vehicle heading, and a change in the vehicle position is calculated using the vehicle heading calculated by the vehicle heading calculation means each time the distance sensor detects traveling a certain distance. ,
A vehicle position calculation means calculates a primary vehicle position by dead reckoning by vector combining the previously determined vehicle position, and a map by a projection method with reference to map data each time the primary vehicle position is calculated by the vehicle position calculation means. A matching candidate road is searched, and when a map matching candidate road exists, the primary vehicle position is corrected to be on the matching candidate road as the final vehicle position, and when no map matching road exists, the primary vehicle position itself is used as the final vehicle position. A vehicle position correcting means for outputting a vehicle position, a determining means for determining whether a link to be corrected for the latest vehicle position is longer than a certain distance by referring to map data when the vehicle position is corrected by the vehicle position correcting means, and a determining means. An in-vehicle navigator characterized by being provided with vehicle heading correction means for determining the heading of the link to be corrected and rewriting the vehicle heading storage means of the vehicle heading calculation means with the said heading when it is determined that the link is a certain distance or more. vehicle position detection device. 2. A map data storage means that stores map data, and a direction change detected by a direction sensor, which is integrated with the previous vehicle direction stored in the vehicle direction storage means to obtain a new vehicle direction; A vehicle heading calculation means that rewrites the vehicle heading storage means with the obtained vehicle heading, and a change in the vehicle position is calculated using the vehicle heading calculated by the vehicle heading calculation means each time the distance sensor detects traveling a certain distance. ,
A vehicle position calculation means calculates a primary vehicle position by dead reckoning by vector combining the previously determined vehicle position, and a map by a projection method with reference to map data each time the primary vehicle position is calculated by the vehicle position calculation means. A matching candidate road is searched, and when a map matching candidate road exists, the primary vehicle position is corrected to be on the matching candidate road as the final vehicle position, and when no map matching road exists, the primary vehicle position itself is used as the final vehicle position. Each time the vehicle position is determined by the output vehicle position correction means and the vehicle position correction means, it is determined whether the vehicle position has been corrected a predetermined number of times in succession, and the map data is referred to to determine the latest vehicle position. a determining means for determining whether a link whose position is to be corrected is at least a certain distance; A vehicle position detecting device for an on-vehicle navigator, characterized in that a vehicle position detecting device for an on-vehicle navigator is provided, comprising: a vehicle direction correction means for determining the direction of the link to be corrected and rewriting the vehicle direction storage means of the vehicle direction calculation means with the direction. 3. A map data storage means that stores map data, and a direction change detected by the direction sensor is integrated with the previous vehicle direction stored in the vehicle direction storage means to obtain a new vehicle direction; A vehicle heading calculation means that rewrites the vehicle heading storage means with the obtained vehicle heading, and a change in the vehicle position is calculated using the vehicle heading calculated by the vehicle heading calculation means each time the distance sensor detects traveling a certain distance. ,
A vehicle position calculation means calculates a primary vehicle position by dead reckoning by vector combining the previously determined vehicle position, and a map by a projection method with reference to map data each time the primary vehicle position is calculated by the vehicle position calculation means. A matching candidate road is searched, and when a map matching candidate road exists, the primary vehicle position is corrected to be on the matching candidate road as the final vehicle position, and when no map matching road exists, the primary vehicle position itself is used as the final vehicle position. When the vehicle position is corrected by the output vehicle position correction means and the vehicle position correction means, it refers to the map data to determine whether the correction target link of the latest vehicle position is longer than a certain distance, and also determines whether the correction target link of the latest vehicle position is longer than a certain distance. and determining means for determining whether the absolute value of the difference between the bearing and the vehicle bearing calculated by the vehicle bearing calculation means is greater than or equal to a certain value; When it is determined that the absolute value of the difference between the vehicle heading and the vehicle heading calculated by the vehicle heading calculation means is greater than or equal to a certain value, the vehicle heading storage means of the vehicle heading calculation means is rewritten with the heading in which the vehicle heading is corrected by a certain value. A vehicle position detection device for an in-vehicle navigator, characterized in that a correction means is provided.