JPH04353715A - Vehicle-position detecting apparatus for vehicle mounted navigator - Google Patents

Abstract

PURPOSE:To improve the correcting accuracy for the position of a vehicle by map matching by rewriting bearings memory when it is discriminated that the difference between the bearings of a link to be corrected and the bearings obtained by computa tion exceeds a specified value. CONSTITUTION:At every time the primary position of a vehicle is computed, a vehicle- position correcting part 5f checks map data and searches map-matching candidate roads by a projection method. When the applicable candidate road is present, the primary vehicle position is corrected on the matching candidate road, and the established vehicle position is determined. At every time when the vehicle position is corrected, a discriminating part 5g discriminates whether the difference between the bearings of a link to be corrected and the bearings obtained with a vehicle-bearings computing part 5d exceeds a specified value or not. When the vehicle bearings is not corrected in the halfway and it is discriminated that the difference between the bearings of the link to be corrected and the bearings obtained with the computing part 5d exceeds the specified value continuously a specified number of times in the judging part 5g, a vehicle-bearings memory 5c for the computing part 5d is rewritten with the bearings of the newest link to be corrected through a vehicle-bearings correcting part 5i.

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. 9 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 vehicle's traveling direction) is θ0, the output of the relative direction sensor (change in direction) at point P1, which has traveled a unit distance L0, is Δθ1.
The current vehicle direction θ1 at point P1 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 ・co
s θ1
...(2) Y1 =
Y0 +ΔY =Y0 +
L0 ・sin θ1
...(3) can be calculated by vector composition. Therefore, if the vehicle heading and position coordinates at the starting point are given, the vehicle heading and position can be detected in real time by repeating calculations (1) to (3) every time the vehicle travels a unit distance L0. can do.

[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).
. 10 to 12 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. 10, 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.

At this time, (a) the link is located within a certain distance range from point Pi' and the perpendicular line can be lowered, and the angle difference between the vehicle direction θi at point Pi' and the link is within a certain value. Search for primary map matching candidate roads. Here, the road RDa has a link LKa1 (a straight line connecting nodes Na0 and Na1), and the road RDb has a link LKb1 (a straight line connecting nodes Nb0 and Nb1). (b) A road having a link with a smaller angle difference from the vehicle direction θi at point Pi' is set as a secondary map matching candidate road. Here, it is road RDa. (c) And point Pi
Drop the perpendicular line RLia from ' to the link LKa1 and set the point Pi
The running trajectory SHi connecting −1 and Pi′ is the perpendicular RLi
Point Pi-1 is translated in the direction of a until it is on link LKa1 (or on the extension line of link LKa1), and points Pi-1 and Pi' are moved to points PTi-1 and PTi.
(d) Finally, calculate PT with the point PTi-1 as the center.
The moving point is determined by rotationally moving until i' is on the link LKa1, and the determined vehicle position Pi (Xi, Yi) is determined.

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. 11, 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. 12, when turning at an intersection at point Pi-1, the primary vehicle position Pi' is projected onto the road RDa intersecting 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. 13, 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], [Pj ′], even though map matching is possible on the road RDc, the calculated vehicle direction θj−1
When the primary vehicle position is calculated based on Pj', the road RDd becomes 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 each time the vehicle position is corrected by the vehicle position correction means,
A determination means for determining whether the difference between the direction of the link to be corrected and the direction determined by the vehicle direction calculation means exceeds a certain value; and a determination means for determining whether the difference between the direction of the link to be corrected and the direction determined by the vehicle direction calculating means exceeds a certain value; vehicle bearing correction means for rewriting the vehicle bearing storage means of the vehicle bearing calculation means with the bearing of the latest correction target link when it is determined that the difference between the bearing and the bearing calculated by the vehicle bearing calculation means exceeds a certain value; This is achieved by providing the following.

[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 correction means outputs the primary vehicle position itself as the final vehicle position, and each time the vehicle position is corrected by the vehicle position correction means, the difference between the direction of the link to be corrected and the direction calculated by the vehicle direction calculation means. the vehicle position is corrected a predetermined number of times consecutively by the vehicle position correcting means without the vehicle heading being corrected midway; and the vehicle position is corrected a predetermined number of times. In the modification, when the determination means determines that the difference between the bearing of the link to be modified and the bearing calculated by the vehicle bearing calculation means exceeds a certain value, the vehicle bearing memory of the vehicle bearing calculation means is stored with the latest bearing of the link to be corrected. This is achieved by providing vehicle orientation correction means for rewriting the means.

[0013]

[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 Each time the correction is made, it is determined whether the difference between the direction of the link to be corrected and the direction calculated by the vehicle direction calculation means exceeds a certain value, and the determination means continuously determines whether or not the direction of the link to be corrected exceeds a certain value. When it is determined that the difference between the direction of the link to be corrected and the direction found by the vehicle direction calculation means exceeds a certain value, the vehicle direction storage means of the vehicle direction calculation means is rewritten with the latest direction of the link to be corrected. As a result, regardless of whether the road you are driving on is a straight section or a curve, errors that exist in the calculated vehicle direction can be periodically corrected, and the accumulation of errors in the direction sensor can be prevented. , it is possible to improve the accuracy of correcting the vehicle position by map matching.

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,
Every time the vehicle position is corrected, it is determined whether the difference between the direction of the link to be corrected and the direction calculated by the vehicle direction calculation means exceeds a certain value, and the vehicle position correction means determines whether the difference between the direction of the link to be corrected and the direction calculated by the vehicle direction calculation means exceeds a certain value, and the vehicle position correction means does not correct the vehicle direction midway. The vehicle position is continuously corrected a predetermined number of times, and in each of the predetermined number of corrections of the vehicle position, the determination means determines that the difference between the direction of the link to be corrected and the direction calculated by the vehicle direction calculation means is a constant value. When it is determined that the
The vehicle direction storage means of the vehicle direction calculation means is rewritten with the direction of the latest correction target link. As a result, regardless of whether the road you are driving on is a straight section or a curve, errors that exist in the calculated vehicle direction can be periodically corrected, and the accumulation of errors in the direction sensor can be prevented. , it is possible to improve the accuracy of correcting the vehicle position by map matching.

[0015]

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 confirmed 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 which stores vehicle orientation data. A heading memory 5d calculates a new vehicle heading by adding the change in heading detected by the relative heading sensor 3 to the previous vehicle heading stored in the vehicle heading memory 5c, and uses the calculated heading to the vehicle heading memory 5c. Vehicle position calculation part that rewrites 5
e is a primary vehicle position calculation section, 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 section 5d. The 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 a vehicle position correction unit 5f that outputs the fixed vehicle position data corrected to the fixed vehicle position data, and outputs the primary vehicle position data itself as the fixed vehicle position data when there is no map matching candidate road. Each time a correction is made, a determination section 5h determines whether the difference between the direction of the link to be modified and the vehicle direction calculated by the vehicle direction calculation section 5d exceeds a certain value, and 5h is the latest confirmed vehicle position data. a driving data memory that stores the determination result and the sign of the difference for a predetermined number of times when it is determined that the difference between the direction of the link to be corrected and the vehicle direction determined by the vehicle direction calculation unit 5d exceeds a certain value;
5i, the vehicle position is not corrected midway, and the discrimination part 5g
When it is determined that the difference between the direction of the link to be corrected and the vehicle direction calculated by the vehicle direction calculation unit 5d has exceeded a certain value for a predetermined number of consecutive times, the vehicle direction memory 5c is rewritten with the direction of the link to be corrected. The correction unit 5j 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. , a map drawing control unit that displays a vehicle position mark.

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 5h, and the latest confirmed vehicle position data is S.
is stored as . Further, when the determination unit 5g determines that the difference between the direction of the link to be corrected and the vehicle direction calculated by the vehicle direction calculation unit 5d exceeds a certain value, it is represented by 1, and when it is determined that the difference is below the certain value, it is represented by 0. Flag data is stored from F1 related to the latest correction to F5 related to the four previous corrections, and for each flag F that becomes 1, the difference between the direction of the link to be corrected and the vehicle direction calculated by the vehicle direction calculation unit 5d is stored. The code data of is stored as M (M1 to M5).

3 to 5 are flowcharts showing map and mark drawing processing, calculation of vehicle orientation, primary vehicle position, and correction processing of vehicle position and vehicle orientation by the system controller 5, and FIG.
and 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.

[0021] In advance, according to the driver's map selection operation, the map readout control unit 5b transfers map data of a predetermined scale including the departure point from the CD-ROM 1 to the map data buffer memory 5a, and performs map drawing control. The section 5j reads the map data from the map data buffer memory 5a and 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. 6, 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 5h is set, and all flags F1 to F5 are cleared and initialized to 0 (step 105). Furthermore, the map drawing control unit 5j 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).

[0023] 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 direction calculation unit 5d inputs the relative direction signal Δθ1 from the relative direction sensor 3, calculates θ1 = θ0 + Δθ1, and calculates P0.
Vehicle orientation θ at the point (P1') that has traveled a distance L0 from
1 is calculated, the vehicle orientation data in the vehicle orientation memory 5c is rewritten, and the data is output to the primary vehicle position calculation unit 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
A link that is within a certain distance range from point P1' and from which a perpendicular line can be lowered, and that the vehicle orientation θ1 at point P1'
The angle difference between the
7.5°) is designated as a primary map matching candidate road. Here, the link LKa
1 (connecting nodes Na0 and Na1)
and link LKb1 (connecting nodes Nb0 and Nb1)
Assume that the road RDb has become. Next, of the links LKa1 and LKb1, the road having the link LKe1 with the smaller angular difference with the vehicle direction θ1 is set as a secondary map matching candidate road. Here, road RD
It is assumed that a.

Next, when a map matching candidate road is found, the vehicle position correction unit 5f drops a perpendicular line RL1a from the point P1' to the link LKa1, and creates a travel trajectory SH1 connecting S=P0 and P1' in the travel data memory 5h. is translated in the direction of the perpendicular line RL1a until the point P0 is on the link LKa1 (or on the extension of the link LKa1), and the points P0 and P1' are moved to the points PT0 and PT1'.
Then, the moving point is determined by rotating around the point PT0 until PT1' is on the link LKa1, and the fixed vehicle position P1 (X1, Y1) is determined by correcting the primary vehicle position P1' to be on the road RDa. , map reading control section 5b, primary vehicle position calculation section 5e, map drawing control section 5
j, and S=P1 of the traveling data memory 5h.
The current determined vehicle position is registered as (X1, Y1) (steps 203 to 205).

Next, since the vehicle position has been corrected by the vehicle position correction unit 5f this time, the determination unit 5g determines that F5 = F4, F4 = F3, F3 = in the travel data memory 5h.
F2, F2 = F1, M5 = M4, M4 = M
3, after shifting the data as M3 = M2 and M2 = M1 (step 206), refer to the map data in the map data buffer memory 5a to obtain the bearing θ' of the link LKa1 to be corrected this time, and also calculate the bearing θ' in the vehicle direction memory. Read the vehicle direction θ1 stored in 5c and calculate Δ
Calculate θ′=θ′−θ1 (step 207),
Determine whether the absolute value of Δθ' exceeds 7.5° (step 208), and if the answer is YES for some reason, such as an error when setting the vehicle heading at the departure point, F1
= 1 (step 209). And Δθ
If the sign of ' is plus, M1 is registered as plus (step 210). Note that if the absolute value of Δθ' is 7.5° or less, F1 is set to 0 (steps 208, 211). Here, F1 = 1, M1
= is assumed to be positive.

Next, the vehicle orientation correction unit 5i determines whether the flag data F1 to F1 in the driving data memory 5h are all 1 (step 301 in FIG. 5);
= 0, which is NO, so no particular correction processing for the vehicle orientation is performed.

If no matching candidate road is found in step 202 of FIG.
f is the primary vehicle position P1 ′ itself determined vehicle position P1 (
X1, Y1), and the running data memory 5g
is registered as S=P1 (steps 203, 212
, 213). At this time, the determining unit 5g does not perform the determining process, and the vehicle orientation correcting unit 5i also does not perform the correcting process.

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 out to 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 5j 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 5j adds a new one containing the vehicle position from the map data buffer memory 5a.
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 section 5d receives 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 here, and it is road RDa, as was the case last time. Next, the vehicle position correction unit 5
f is obtained by correcting the primary vehicle position P2' onto the road RDa in the same manner as described above, and then determining the fixed vehicle position P.
2 (X2, Y2), the map reading control unit 5
b, output to the primary vehicle position calculation unit 5e and map drawing control unit 5j, and also output S=P2 (X2
, Y2) to register the current confirmed vehicle position (steps 203 to 205).

Next, since the vehicle position has been corrected by the vehicle position correction unit 5f this time as well, after the determination unit 5g performs a predetermined data shift operation on the travel data memory 5h (step 206), the map data buffer memory 5a is Referring to the map data of
is calculated (step 207), and the absolute value of Δθ' is 7.
．． Determine whether it exceeds 5° (step 208), YE
When it becomes S, it is registered as F1=1 (step 209). Then, if the sign of Δθ' is the same as the previous time, it is registered as M1=plus (step 21
0).

Next, the vehicle orientation correction unit 5i determines whether the flag data F1 to F5 in the driving data memory 5h are all 1 (step 301 in FIG. 5);
= 0, which is NO, so no particular correction processing for the vehicle orientation is performed.

Note that if no matching candidate road is found in step 202 of FIG.
2 (X2, Y2) and registered as S=P2 (steps 203, 212, 213).

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 5j 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 5j adds a new one containing the vehicle position from the map data buffer memory 5a.
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 unit 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, 212), register it in the travel data memory 5h as S=Pi (step 205 or 213), and
When the vehicle position is corrected by the vehicle position correction unit 5f, after data shift processing is performed on the travel data memory 5h (step 206), the map data buffer memory 5a is
With reference to the map data, the bearing θ' of the link to be corrected this time is determined, and the vehicle bearing θi stored in the vehicle bearing memory 5c is read out to calculate Δθ'=θ'-θi (step 207). , the absolute value of Δθ' is 7.
It is determined whether the angle exceeds 5° (step 208), and if YES, it is registered as F1 = 1 (step 209).
), and the sign of Δθ' is registered as M1 (step 210). When the determination in step 208 is NO, F1 is set to 0 (step 211). Then, the vehicle direction correction unit 5i uses the flag data F in the driving data memory 5h.
1 to F5 are all 1 (step 301 in Figure 5).
), if NO, only predetermined navigation processing by the map reading control unit 5b and map drawing control unit 5j is performed (
Step 112 in FIG. 3).

[0039] Until the determined vehicle position P5 is determined,
The vehicle position is continuously corrected by map matching, and in each vehicle position correction, the absolute value of the difference between the link to be corrected and the calculated vehicle heading exceeds 7.5 degrees, and the link and the link to be corrected are When the sign of the difference in vehicle position calculated by calculation is all positive, F of driving data memory 5h
1 to F5 are all 1, and M1 to M5 are all positive. Then, the vehicle orientation correction unit 5i determines YES in step 301 of FIG. At this time, the vehicle orientation correction unit 5i subsequently determines whether M1 to M5 are all the same (step 302), and the answer is YES here as well. That is, in the five vehicle position corrections made so far,
In both cases, it is determined that there is an offset error in the vehicle direction of a certain value or more in the same direction. At this time, the vehicle direction correction unit 5i refers to the confirmed vehicle position data P5 and the map data in the map data buffer memory 5a, calculates the direction (absolute direction) θ' formed by the link LKa3 to be corrected this time, and stores the information in the vehicle direction memory. Write θ' as θ5 in 5c,
The vehicle orientation is corrected (step 303). As a result,
The accumulated errors from previous vehicle heading calculations have been corrected,
The accuracy of the vehicle orientation and primary vehicle position determined in subsequent calculations will improve, and the accuracy of map matching will also improve accordingly. Next, the vehicle orientation correction unit 5i clears all F1 to F5 in the travel data memory 5h to 0 (step 304).

When the next pulse is input from the distance sensor 4 after the navigation process in step 112 in FIG. is calculated and stored in the vehicle orientation memory 5c (steps 113, 108 to 11).
1). This vehicle heading θ6 does not include the cumulative error of the vehicle heading calculated up to the previous time. Next, the primary vehicle position calculation section 5e uses the previously determined vehicle position P5 and the vehicle orientation θ6 calculated by the vehicle orientation calculation section 5d to determine the current primary vehicle position P6', and outputs it to the vehicle position correction 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 P6' is high because the error in the vehicle direction θ6 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 P6' is corrected by map matching and the final vehicle position P6 is obtained, the discriminator 5g
After shifting the data in the travel data memory 5h, refer to the map data in the map data buffer memory 5a,
In addition to determining the bearing θ' of the link to be corrected this time, the vehicle bearing θ10 stored in the vehicle bearing memory 5c is read out, and Δθ' = θ' - θ10 is calculated, and the absolute value of Δθ' is 7.5°. Determine whether the limit has been exceeded (step 206)
~208). Here, if the vehicle orientation has been corrected first and the answer is NO, F1 is registered as 0 (step 211).

In this case, the vehicle orientation correction section 5i makes a NO determination in step 301 of FIG. 5, and does not perform the vehicle orientation correction process.

[0043] In the following, when the vehicle position is corrected by map matching in the same way, if the absolute value of the difference between the direction of the link to be corrected and the calculated vehicle direction continues to be below a certain value, , without correcting the vehicle position, and then,
Each time the error of the relative orientation sensor 3 accumulates again and the vehicle position is corrected by map matching, the error is repeated nine times in a row.
When the absolute value of the difference between the heading of the link to be corrected and the calculated vehicle heading exceeds a certain value, and moreover, the sign of the difference between the heading of the link to be corrected and the calculated vehicle heading is the same,
The vehicle direction correction unit 5i determines YES in steps 301 and 302 in FIG. 3, and corrects the vehicle direction by rewriting the vehicle direction memory 5c with the direction of the link to be corrected at that time (step 303).

Therefore, if the road you are driving on is curved (see FIG. 6), regardless of whether it is a straight road, the offset error in the vehicle direction may become large due to the cumulative error of the relative orientation sensor 3. Since the vehicle orientation is periodically corrected, the accuracy of the primary vehicle position is improved, the accuracy of the corrected vehicle position by map matching is also improved, and matching errors are less likely to occur.

In the above-described embodiment, as shown in FIG.
If a map matching candidate road is not found for a certain primary vehicle position Pj', such as by entering a road RDH for which no road data exists from Dg, the vehicle position correction unit 5f determines the primary vehicle position itself and determines the vehicle position Pj. (Steps 202, 203, 212, 213 in Figure 4)
. At this time, the determination unit 5g does not perform data shift processing or determination processing. After that, when entering the road RDi, map matching of the primary vehicle position Pk' becomes possible, and the vehicle position is corrected to Pk, the discrimination unit 5g performs a data shift operation and discrimination processing, and stores the results in the travel data memory. 5
h (steps 202-210). Therefore, the vehicle orientation correction unit 5i ignores the fact that the vehicle position correction unit 5f uses the primary vehicle position as the final vehicle position without performing map matching, and focuses only on the determination result when the vehicle position is corrected. Then, if the difference between the calculated vehicle direction and the direction of the link to be corrected is greater than a certain value five times in a row without the vehicle direction being corrected, the vehicle direction is corrected.

On the other hand, when steps 212 and subsequent steps in FIG. 4 are modified as shown in FIG. 8, and the vehicle position correcting section 5f sets the primary vehicle position as the final vehicle position, the vehicle position correcting section 5i stores the travel data memory 5h. All of F1 to F9 are cleared to 0 (step 214), and the vehicle position correction unit 5f clears all of F1 to F9 to 0 (step 214).
The vehicle position has been corrected five times in a row, and in each of the five vehicle position corrections, the differences between the direction of the link to be corrected and the calculated direction in the determination unit 5g all exceed a certain value. Only when it is determined that
may be configured to correct the vehicle orientation.

Furthermore, in the above-described embodiment, the results of five determinations are stored in the driving data memory 5h, and the vehicle orientation correction unit 5i determines whether or not to correct the vehicle orientation based on the results of the five determinations. However, the number of times may be set to six or more times or any number of times from two to four times.

[0048]

[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 each time the vehicle position is corrected, the link to be corrected is It is determined whether the difference between the heading of the link and the heading calculated by the vehicle heading calculating means exceeds a certain value, and the determining means calculates the heading of the link to be corrected and the heading of the vehicle a predetermined number of times in succession without the vehicle heading being corrected on the way. When it is determined that the difference in direction calculated by the means exceeds a certain value, the vehicle direction storage means of the vehicle direction calculation means is rewritten with the direction of the latest correction target link, so that the road on which the vehicle is traveling is straight. Regardless of whether it is a section or a curve, it is possible to periodically correct errors that exist in the calculated vehicle direction, prevent the accumulation of errors in the direction sensor, and improve the accuracy of vehicle position correction using 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,
Every time the vehicle position is corrected, it is determined whether the difference between the direction of the link to be corrected and the direction calculated by the vehicle direction calculation means exceeds a certain value, and the vehicle position correction means determines whether the difference between the direction of the link to be corrected and the direction calculated by the vehicle direction calculation means exceeds a certain value, and the vehicle position correction means does not correct the vehicle direction midway. The vehicle position is continuously corrected a predetermined number of times, and in each of the predetermined number of corrections of the vehicle position, the determination means determines that the difference between the direction of the link to be corrected and the direction calculated by the vehicle direction calculation means is a constant value. When it is determined that the
Since the vehicle direction storage means of the vehicle direction calculation means is rewritten with the direction of the latest link to be corrected, regardless of whether the road you are driving on is a straight section or a curve, the vehicle direction calculated by the calculation will be updated. Existing errors can be periodically corrected to prevent the accumulation of errors in the orientation sensor, and 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 a flowchart showing the operation of the system controller of 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 an explanatory diagram of a general vehicle position detection method using dead reckoning navigation.

FIG. 10 is an explanatory diagram of map matching using a conventional projection method.

FIG. 11 is an explanatory diagram of map matching using a conventional projection method.

FIG. 12 is an explanatory diagram of map matching using a conventional projection method.

FIG. 13 is an explanatory diagram showing a problem with map matching using a conventional projection method.

FIG. 14 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 Discrimination part 5h driving data memory 5i Vehicle orientation correction department 5j Map drawing control section 6 Display device

Claims (2)

[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 correction means for outputting the output, and a determination means for determining whether the difference between the direction of the link to be corrected and the direction calculated by the vehicle direction calculation means exceeds a certain value each time the vehicle position is corrected by the vehicle position correction means. ,
When the determination means determines that the difference between the direction of the link to be corrected and the direction calculated by the vehicle direction calculation means exceeds a certain value for a predetermined number of consecutive times without the vehicle direction being corrected on the way, the latest correction target is determined. 1. A vehicle position detection device for an on-vehicle navigator, comprising: a vehicle orientation correction means for rewriting a vehicle orientation storage means of a vehicle orientation calculation means with the direction of the link. 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. A vehicle position correction means for outputting the output, and a determination means for determining whether the difference between the direction of the link to be corrected and the direction calculated by the vehicle direction calculation means exceeds a certain value each time the vehicle position is corrected by the vehicle position correction means. ,
The vehicle position is continuously corrected a predetermined number of times by the vehicle position correction means without the vehicle direction being corrected midway, and in each correction of the vehicle position for the predetermined number of times, the determination means determines the direction of the link to be corrected. Vehicle bearing correction means is provided for rewriting the vehicle bearing storage means of the vehicle bearing calculation means with the bearing of the latest link to be corrected when it is determined that the difference in bearing calculated by the vehicle bearing calculation means exceeds a certain value. A vehicle position detection device for an in-vehicle navigator, characterized in that: